Notice: We are in the process of migrating Oral History Interview metadata to this new version of our website.
During this migration, the following fields associated with interviews may be incomplete: Institutions, Additional Persons, and Subjects. Our Browse Subjects feature is also affected by this migration.
Please contact [email protected] with any feedback.
This transcript may not be quoted, reproduced or redistributed in whole or in part by any means except with the written permission of the American Institute of Physics.
This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.
Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event. Disclaimer: This transcript was scanned from a typescript, introducing occasional spelling errors. The original typescript is available.
In footnotes or endnotes please cite AIP interviews like this:
Interview of H. Richard Crane by Charles Weiner on 1973 March 28,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
Family background and early education; early science interests (telegraph and radio transmission), wins American Chemistry Society Contest in high school. Caltech for both undergraduate and graduate studies, 1926-1934, comments on courses, teachers (Richard C. Tolman, Paul Epstein) and fellow students (Chet Carlson, the inventor of Xerox). Joins Charles Lauritsen's group as graduate student (nuclear physics), gets involved in research projects. J. Robert Oppenheimer's interest in their work, Ernest Lawrence's interest and objections to Lauritsen/Crane work on the radiative captive process (Enrico Fermi), Merle Tuve's involvement. Involvement in building machines for the Kellogg Laboratory (Seeley W. Mudd); Ph.D 1934 (The capture of protons by Carbon-12). Accepts offer from University of Michigan at Ann Arbor; planning and building of a high voltage accelerator. Department involvement in applied work (GE, Ford), strong interest in biology; rising biophysics interest in the department. Wartime work. Recruited for MIT's Radiation Laboratory, later involved in Tuve's proximity fuse project; Manhattan District interest. Establishment of Biophysics Lab within Physics Department in Ann Arbor. The Racetrack Synchrotron. Also prominently mentioned are: Carl David Anderson, Ted Berlin, Sir John Cockcroft, John, Sir, Walter Francis Colby, James M. Cork, Leo Delsasso, David Mathias Dennison, William Alfred Fowler, Samuel Abraham Goudsmit, Halpern, Fred Hodges, Lampe, Otto Laporte, Gilbert Newton Lewis, Edwin Mattison McMillan, Harrison McAllister Randall, William Ralph Smythe, Robert Thornton, George Eugène Uhlenbeck, A. E. White, Robley Williams, Ralph Walter Graystone Wyckoff; and Randall Laboratory of University of Michigan.
Let's start at the beginning. That's where I know the least amount of information. I know you were born in 1907, in Turlock, California. I don't know where it is, what kind of environment, how large a town.
Well, Turlock is exactly in the center of California. If you take a map and put a point at the center, east and west and north and south, why, that's about it. It's in the San Joaquin Valley, and when I was there — I guess still is — it was entirely a farming area. Happens to be one of the centers of the wine industry now, but in those days it was just farming, melons, all kinds of crops. In the early days when I was there I think the main product was watermelons. We used to send them out by the trainload. Kids used to go down and snitch them off the back of wagons as they were going in. Then it turned to cantaloupe after that. Same thing, everybody planted cantaloupe and they sent those out by the trainload. It was a farming environment. The town was small, three or four thousand at that time... Some of the streets were paved and some were not. Kids all went barefooted half the year. The summers were hotter than the devil. It's about 100 miles southeast of San Francisco and 100 miles south of Sacramento.
The nearest larger town you'd get to would be what?
Oh, I guess the nearest larger town — it was roughly midway between Fresno and Stockton.
Was your family involved in farming?
Yes, they were involved in farming. My father was involved in a lot of things. Like many of the pioneering type of people, he was involved in farming and some business and he owned some property and generally was a — involved in a lot of things. Our family was a fairly prosperous family so I didn't have any hardships when I grew up. I went to the grammar school in Turlock, then to Turlock High School, from there to Cal Tech.
Let me ask about the educational background of your parents?
My father had never been to college. I guess he went through high school or something. He and his family came from Connecticut, migrated from Connecticut. My mother's family came from Nebraska. My mother was a school teacher for a while.
Did she go to college? In those days it wasn't necessary.
Well, not a college in a formal sense. She had some kind of teacher's training.
She taught in Turlock?
Yes. That was before I was born.
How large a family — brothers and sisters?
I just had one brother.
Was he older, younger?
Younger, four years younger. He's not living now. There were just the two of us.
What field did he end up in?
He was a businessman. Had no interest in science.
What about the family atmosphere, in the house itself? Was it on land being farmed where you lived?
I was born in a house that was in the center of the small town, on a dirt street, across from a blacksmith shop, where I got my early introduction to science. After that, I don't remember how long later but we moved out to a ranch for a while, two or three years. Then we moved back to another part of town which was on the edge of town. Then eventually back into town. So I've lived on a ranch part of the time, on a farm part of the time, or whatever, cows and chickens and things, and also in the small town, which is really now very much like urban living but it was at least inside of the small town.
You mentioned the blacksmith shop. At what age was this? Obviously it was something that fascinated young boys.
Oh, I think this was when I was four or five years old. I used to go across the street and spend hours and hours in the blacksmith shop, watching them hammer out the shoes. They had to make shoes in those days. They didn't buy them like they do now. Make them from the raw iron, pound them out, fit them to the horse and nail them on... That fascinated me.
Other than watching the fascinating blacksmith process, was there any other hobby or interest you had in those early years?
Well, yes. I had a lot of hobbies. I don't know where I'll get them in the right order or not. I was an ardent birds' egg collector at one time, had quite a collection of them when I was a small boy. We used to climb trees and get the eggs and blow the insides out of them, try to label them as best we could. There were several other boys in the town who did the same thing. We had quite a collection. In those early days there were lots of birds around. They'd nest in the trees and nobody cared whether you robbed the nests or not. So that's one thing we did. I made model planes at one time, rubber band type. I think that must have been later because that kind of hobby didn't come into general practice until I'm sure later than those very early days.
It might have been after World War I, as a matter of fact?
No, I think I made the airplanes out of sticks and glue and paper and rubber bands and things when I was fairly small. Sure it must have been after airplanes were quite generally seen — I didn't invent the airplane!
So birds' eggs, model airplanes —
— I did a lot of hunting too. It was mostly I guess during the few years I lived way out on a ranch, on a cattle ranch. I used to do a lot of hunting of doves and ducks and things like that. I guess my first real serious hobby was radio. I got interested at the very beginning of the days of broadcasting, and there were only about two broadcast stations that could be heard from where I was. There was one in San Francisco. I think it was 10 watts or something like that. There was one in Los Angeles. I've forgotten the call letters. I think KG0 was in San Francisco and one in Los Angeles; there were just two fairly small broadcast stations, and I got started on radio, and I eventually became the town expert on building radio receivers and actually made several receivers for people. They paid me to make receivers for them. They were made out of the old audion tubes and batteries, headphones and that kind of thing. I made these up, made several sets for people in town — and from there I went to amateur radio, started up with a station that consisted of a Ford spark coil. There was one other young fellow in town who did it with me, and we each had a Ford spark coil and a key and very rudimentary receivers, and we could talk over half a dozen blocks or so that separated us — and gradually I kept upgrading that till I had a CW station with a five watt tube, NV 202 tube, — are you familiar with the little tubes? From there to a 50 watt tube, and I continued that until I went away to college. I continued to have a radio station at home. I had my transmitting license from about 1921 up until I think the last renewal was 1928. I started Cal Tech in 1930 — no — that's graduate work —
It must have been '26, you got your bachelor's in '31.
Well, I got my first license in about 1921, and I went to Cal Tech about '25, as I remember it, and I guess I must have continued to keep my radio station for another two or three years at home, so that ended about 1928.
What got you started on broadcast radio in the first place? Was there something you had read, someone you'd talked with at home that got you interested, to develop these skills?
I don't know who showed me how to do it. There was another young fellow in Modesto which was 12 or 13 miles away, and he also, I guess he was a little ahead of me at that time and had a station, and I got my ' mother to drive me up there two or three times, and I got a lot of information from him. My only source of scientific information I guess in those days was that I was an avid reader of the old SCIENTIFIC AMERICAN, the big size old one. I read every word of that and got some of my information from that. Before I went into radio I was very much interested in electricity, and I set up a very extensive telegraph system from our barn to the house, to the tank house and all around, and the thing was made with old pieces of clock spring. I made my key by taking a piece of clock spring, which was a nice springy flexible piece of metal — nail one end of it on the board, then put a nail under the other end of it, so it could be tapped down on the nail, and that was the key. Then I made the receiver in a similar way with a big nail wrapped with magnet wire, then a piece of clock spring that would be attracted up and down on top of the nail. That was the transmitter and receiver. It was all powered with discarded dry cells that I used to pick up behind garages. In those days all automobiles had spark coils that were run by dry cells, so every garage had a pile of dry cells out in back. Dry cells were taken out of cars before they were really dead, and if you'd go around with a piece of wire and just spark them, you could tell good ones from bad ones, and I used to collect just piles of those old dry cells and connect them up in series, and that was power, for the telegraph system. That was before I got interested in radio, that was earlier. I don't know to this day who told me that if you wind wire around a nail it will make it magnetic, and you can make a telegraph that way, but I imagine that I must have gone down, looked at the telegraph in the railroad station to see how it was made. I'm sure I must have done that. I know I didn't invent the telegraph.
What about the line, what did you use for that?
Oh likewise, I used to get all my wire from old discarded spark coils from cars — the primary winding on an old spark coil, Ford coil or any other spark coil from a car has about, oh, at least 50 feet of No. 20 wire, something like that. That's the primary. The secondary of course has very fine wire, but the fine wire was usually covered with green silk. That was fine, a very fine source of wire. You could pick up lots of those if you'd go around behind the garages too. So supplies were not in any shortage at that time.
How old were you when the telegraph — when you developed it?
Well, let me think back, when I started in radio. I was a ham in 1920 or '21, which made me 14 years old, and I imagine that the preceding three or four years was when I set up these telegraph sets, maybe 11 years old, 11 to 13,14, something like that.
I'm trying to find, in a relatively small farming community, the spark that started you. You mention reading SCIENTIFIC AMERICAN. Was that the thing that got you interested, or were you already interested and found SCIENTIFIC AMERICAN?
Well, I don't know how I came to — I guess — well, I think I was fascinated by scientific mechanical things, from the time I was you know, five years old maybe, I was interested in mechanical things. And I suppose that my mother, somebody suggested to her that subscribing to the SCIENTIFIC AMERICAN for me — maybe I got it for a Christmas present or something. I would imagine that's the way it started. But I had quite a pile of them. I kept them all and I had a big pile of these — right up until the time the SCIENTIFIC AMERICAN folded. The one one folded.
You don't mean '48 when it was taken over?
'48 was the start of the new one. I don't know when they stopped publishing the old one.
What about your father? Did he have any of these abilities or interests? Did he encourage you in any way?
I don't remember that I had any strong encouragement. My parents were always very willing and anxious to provide things I thought I needed. I remember — I'm not sure I remember it, I guess I was probably told about it afterwards, but I think I remember it — when I had my tonsils out at the age of about six, my mother asked me what I'd like to have to play with when I was recuperating in the hospital bed, and I said I wanted some pliers and some wire. So they brought me a pair of pliers and some wire and I amused myself by twisting up little things out of wire.
What about books at home? Was there any family library? Were new books added to it?
Not very much, no.
And you shared the radio interest with someone you mentioned in town, and in a nearby town. Did you share this with your brother?
No. He was not interested in science. He was interested in horses and motorcycles and various things like that. More the extravert normal boy. Well, the radio, there were a few other people at that time, boys, interested in it. There was one particularly in my own town, and I don't remember anybody else. This one boy and I sort of started together, and I remember this fellow in Modesto who had evidently started just a little ahead of us, so he was a source of information for us. And then, after I was a ham for a while, I took the exam for a commercial license, operator's license, and I got that. Then because of that, I was offered the job of running the radio broadcast station in Stockton during summers. So for a couple of summers I spent some time running the small broadcast station in Stockton. I guess that was during my high school years. It was 10 watts and was supported by a local department store, and completely a one man operation. I was the operator, the announcer, the advertiser, the whole works.
What was broadcast over the station?
Well, I was a disc jockey most of the time, playing records. But then I had to put in ads, mostly from this department store, between the records. At times we had to move, not the station but the microphone end of it. We had to move it to the local County Fair grounds, and broadcast trotting races, stock judging and things like that. It was just a single man small station but I enjoyed that. I also was the operator of the local movie house for a couple of summers. I didn't have to have a license for that. Or belong to a union.
Did the broadcasting work require much technical work? Did you have to maintain equipment?
I just had to do a minor amount of trouble shooting. The station was an operating station when I went on the job. Mostly I just had to know how to turn it on, keep something going over it at all times and not have any silent spaces.
During this period did you start reading other things? Hugo Gernsbach I guess had a magazine on electricity or science, things like that — do you remember any other popular scientific magazines or books?
No, No, I don't.
I wonder if you have any recollection of Haley's Comet which was 1910? You were very young — just curious.
No. I got interested in physics really when I took physics in high school. I didn't know, up to that time it was electricity, radio, things like that. I took the high school physics course. I guess I took the chemistry course first, then the physics, that was the sequences, but in both courses where was a physics and chemistry teacher who was very interested in helping anybody who seemed to show a real interest. His name was Senter. I never knew what happened to him after I left high school. But he was very good to me. He let me do experiments on my own after school and such things, and I got interested in gas discharge tubes, Gessler tubes. They had a torch there that was fairly good for glass blowing and a little supply of glass tubing, so I blew my own Gessler tubes, and then had to make myself a vacuum pump. I made it by the old method of letting a mercury drop fall down through a tube, trapping the air between mercury drops. It takes a hell of a long time but you evacuate that way. By working it long enough I could get down to where I could get a gas discharge, and I was fascinated by the striations in the gas discharge. The high voltage source I used was one that I brought from home, from my ham radio. I had a high voltage transformer, and I brought that over and used it to power these Giesler tubes. I guess I — oh, I don't know, put different gases in. I don't know where I got the gases. Maybe the high school had one or two different kinds of gases available. Then they also had a big old electrostatic machine, huge plates, three feet in diameter and so on, heavy thing. I worked with that till I got it put into shape and got it operating. I don't think I ever did anything constructive with it except to run it and get great big sparks. Then this fellow Senter heard that the American Chemical Society was putting on a chemistry contest for high school students. I think it was the American Chemical Society section in the San Francisco Bay Area, something like that. And there were some prizes. So he entered me. I think it was a two day exam. They sent down a whole sheaf of questions, and I had to do it at the high school. It was administered by the high school. And I won it. I got a trip to San Francisco and got to go to the ACS section meeting and hear a couple of talks. One of them was on liquid ammonia, I remember. I sat in the front row and got doused with liquid ammonia. But anyway the prize was, any three or four, I've forgotten which, three I think, books that I could select from a list. So I selected Sommerfeld's ATOMIC STRUCTURE AND SPECTRAL LINES, in English, it was the English translation. I selected Crowther's IONS IN GASES or something like that, anyway about gas discharges by Crowther. And one other, I can't remember — well, I guess it didn't make much impression on me. I think there was one other one. Anyway I spent a great deal of time reading Sommerfeld and Crowther. That's when I got those two books. That was still during my high school days.
This laboratory in high school was the one lab for all science in the high school, is that right?
No, they had a suite — they had a classroom in the middle, and on one side was the physics lab, on the other side was the chemistry lab. I'm well aware of that because when I took the chemistry course I got interested in making sulphur dioxide and other kinds of gases that could be liquified under pressure, so I blew myself an all glass system out of pyrex, for making SO2. I had the reactants in a couple of flasks and they were connected by glass that was all sealed together, so when I got it together, I could dump one of the reactants into the other, and I had a cold bath on the other side with ice and salt, for the S02 to condense. I got it all together and it worked just fine. I put the reactants together and the S02 started to condense over on the other side. This was in the room adjoining the classroom. This was behind the wall. Then I had to go to math class or something, so I thought everything was going fine and I left it, plenty of salt and water and everything. But while I was away, the thing blew up, and the S02 filled the laboratory and came under the door and drove the class out of the classroom and all hell broke loose.
Had you had any science courses before, in elementary school, any kind of exposure?
No books or magazines other than ones you've talked about.
No, up to that time, if you're talking about real science, I think the only available material I had came when I won these books, Sommerfeld and Crowther. That was my first real stuff that I started to read seriously.
You did that on your own anyway.
I know what the other book was. It was a geology book. I think it was by Hobbes. University of Michigan professor, died at the age of nearly 100 here not too long ago. Very fascinating book about volcanoes and various things. But I didn't follow geology.
You came back to it later a little bit. Interesting how these things begin to jell. Before we get back into high school — the general environment of the family, the house — was it a religious family?
No. It was a town of 3000 and there were 30 churches there, but we didn't — my mother went fairly regularly to church and they sent me to Sunday school, the early part of my life, but it didn't take very much. My father I think completely ignored the church. My mother as I say went, as I remember, fairly regularly, at the time when I was small. But you wouldn't call it a religious family.
No orientation in that direction in the family, no philosophical or religious discussions that you recall? Let me get on then to high school. When did it occur to you in your high school experience that the science you were learning was something you'd really want to pursue further in higher education?
Well, I think I would have been just as happy at that time to have become a radio engineer, something like that. I didn't look upon physics as THE thing. I guess I went to Cal Tech as a kind of an accident, because at that time Ernest Watson, whose name you probably know, used to go out on junkets around to the high schools and give recruiting talks. And he took a supply of liquid air with him always and showed the kids some amazing tricks with liquid air, to get the kids interesting and then talked about science and Cal Tech. So I took the exam. The exam was given at the high school. If you just indicated you wanted to take it, they would send the exam and the high school would administer it. So I took the exam at the high school and was admitted. But if somebody had come with a bucket of liquid air from Berkeley, I'd have gone to Berkeley.
What kind of exam was it? Did it require math or knowledge of engineering, or basic science?
As I remember it, it had all the different components like some math, some physics, chemistry, and then part of it was to write an essay about some preferably scientific subject that you were interested in, just write an essay. I suspect that's mainly what they looked at.
Do you recall the subject of yours?
I wish I could remember it but it was — well, I'm just guessing, but it probably was on something to do with radio or something like that. And also I think they wanted you to write a little essay on what you thought you would like to do, and I'm sure I, whether I believed it or not, I was able to come up with a good story of some kind.
What did you have in mind at Cal Tech? Could have been many things, engineering, radio design, science — when you took the exam, what did you have in mind that you'd do once you got there, if you got there?
Well, remember, this was after I'd had my physics and chemistry course in high school, after I'd studied Sommerfeld and these things and had had a little more taste of physics and of chemistry, so I think by that time I probably was oriented toward science rather than engineering. As a matter of fact, now that I think of it, I think after I — either before or after I took that exam, in connection with this barnstorming tour, I think they invited applicants to come down to their open house that they have every spring. I don't know whether they paid my way or not but anyway since I was an applicant, going to be, was interested at least, they invited me to come down to their open house, and I remember, I did go and I went around through the various buildings, and they let us see the research, look into the research rooms. In many of them the researchers were in there and they would explain some things to you. That was an eye opener. That was my first view of any real science going on.
This would have been Bridge Laboratory then?
Yes, that was in Bridge Lab.
Did you know any of the individuals by name or reputation before you went?
I knew of Millikan, but I don't know whether I knew anybody else or not, I doubt it though.
Do you recall what you saw when you went in, specific people you may have identified later?
That's pretty hard, you know — when you see people later and you don't know if you're remembering them from —
But this experience was another constructive one for you —
What about the amount of math that you had in high school? How far did you get?
Well, I think I had advanced algebra, second year algebra, and of course the usual trig and geometry. That's probably all they gave, is two years of algebra, I don't know if it was a year or half year, probably at that time a year of trig and a year of geometry. I don't think they teach much geometry any more but I had a whole year. The first half of the year was plane geometry, the second half solid geometry.
Pretty decent dose. ...(phone)... Just on the general subject about going to Cal Tech, we talked about high school math and so on — I think that clears up for me the background. Had you been away from home prior to that? You'd been up to Stockton, to San Francisco for the ACS thing, to Pasadena for the Cal Tech open house. Had you had other occasions, trips, taking you away from California, up to that time?
Nothing that would be of any great interest. We took some trips — oh, the family used to go to San Francisco for a day or two — fairly often — well, as a matter of fact, when I was a radio amateur and I decided to get a commercial operator's license, I went and stayed in San Francisco for a few weeks, went to the Pacific Radio School to get my — get the necessary special knowledge for the commercial operator's license. Well, there were some trips. 0ne I guess — at the time, the furthest I went from home, my father and cousin and her father and I went to Alaska on just an excursion trip, and back. I'd never been East at that time.
0n one of the coastal ships to Alaska?
It goes up the Inland Passage. Then you get on a narrow gauge railroad and go across the mountains; then you get on a river boat and go down the Yukon River that goes to about the Arctic Circle; then come back the same way.
During summer vacation?
Yes, it was in the summertime.
Busy summers — you were running a movie projector, going to commercial broadcasting —
Well, I did other things too. At that time we had a summer cottage in the Sierras. I spent a great deal of time in the summers up there, and I got to be an expert fly fisherman and wasted an awful lot of time doing that in the summers. I used to make my own flies, and I used to buy cheap fly rods and then re-do them all over, re-scrape them and re-do them, etc., make better fly rods out of them. I got quite ... (off tape)
I found out something when I was making flies that I was able to apply to physics teaching later, and that is that I made flies for quite a long time before I realized that I was making them to appeal to myself instead of the fish. And that was a good lesson to carry over to physics teaching.
Let's pin down the date that you went to Cal Tech. I'm assuming you took the exam in your senior year of high school, and were notified that you were accepted. You said '25. Note you graduated, got your Bachelor of Science degree in 1930 — was it a five year program?
No. The dates — we must have the dates a little wrong, because I graduated, got my bachelor's degree in '30, and I took a straight four years, the usual four years. I spent actually I think 4 1/2 years in high school. I went in I guess at an odd time. But definitely 1930 for my bachelor's and I spent the standard four years there, getting that.
You would have entered then in the fall of '26; that's what I'm getting at. Was any financial aid given by Cal Tech? First, was it possible for your family to pay your tuition?
I didn't need any. My parents were able to send me. I guess I wasn't very keenly aware of what was available because I didn't have to have it. I doubt if there was very much at that time.
The exam was not competitive for a scholarship, just for entrance.
That's right, it was just an entrance exam.
Did you have to go through an interview in addition to the exam? 0r was that what you did when Watson was coming through?
I don't remember an interview. It could conceivably have been taking place at the time that I went down for the open house. That may have been their reason for asking us down there. I don't remember that, explicitly. I don't remember an interview.
You may have been interviewed without knowing it. 0K, you left to take up residence there late summer, early fall of '26, and I'd like to talk a little bit about your courses, the kind of program you had, also your impression of the faculty, your knowledge of the research that was going on there. First let me ask, I just thought of something I meant to ask before, when you read the Sommerfeld and Crowther books, did you understand it or just plow through it or were there big gaps in your understanding of what you were reading?
That's a hard question. I know I puzzled a great deal about the — about a couple of things, about the quantum condition that appeared all through Sommerfeld's book. And I think I — you know, I understood enough — I knew what the terms meant and I just repeated back the rules and things like that. That's about as far as my understanding went, I'm sure. Then the relativity part, I was quite interested in. I remember I tried for a long time to understand the Fitzgerald contraction, and I doubt that I ever did really at that time. Maybe I don't now. At least I remember, I agonized over it quite a bit.
There was no one to discuss it with at the time?
No, there wasn't anybody to discuss it with. I got these books from the American Chemical Society, and there was nobody, I was all by myself from then on, till I went to Cal Tech.
Your teacher wasn't able to handle that.
No, he couldn't do it, no.
I just wanted to get a feeling of whether — sometimes a book like that can be very discouraging at that point in your career. At Cal Tech, how would you characterize the life in terms of courses and your growing awareness of what was going on? Do you remember specific courses? I have a list, not for '26, the earliest I brought with me is 1930 indicating some of the courses, so we can check various names, people who are teaching, and maybe some did go back to earlier. But do you remember what kind of sequence you went through?
Everybody took the same. You differentiate yourself as to what specialty. You didn't differentiate yourself even between science and engineering until after two years. I don't believe. I think everybody had the same thing for two years. Well, you had a math course at all times all the way through Cal Tech, and we had — I'm trying to think how much chemistry. I think chemistry went through the first two years. Physics of course went right along, the whole — for those who decided on physics after two years, then physics kept right on. But then they tried to give us a broad base as well as they could, and I'm grateful for it. I think they did a good job. They gave us a course in ancient history — these were not all full year courses. They may have been a term.
Robbey Evans told me about Two Button Benny who taught history there. I don't know if you know that nickname but his first name was Benny, Benny something —
MacArthur was the one who taught history. They gave us a course in — these must have been all one term courses, but they gave us a course in ancient history, economics, it seems to me there was another one of the same type and then they gave us some other sciences. They gave us a term of paleontology and one of geology and one of biology. They kept us going with those — I don't know if I've named six, maybe I've only named five, but I think the first two years we were on a term system where there were three terms per year, and I think there were six of these general type courses that were outside of your specialty. I think I've named five, ancient history — economics, paleontology, geology, biology. There must have been one more. But you get the general idea. The biology one at that time, I just had good luck that I had this course that was a series of lectures that were given by three people. They shared sort of went on rotation, and they were Thomas Hunt Morgan, Bridges and Sturtevant. You can't find three more famous names in biology than those people, and they were the ones that gave all the lectures in that term course, and they were very interesting — mostly about fruit flies because that's what they were working on at that time.
Did you have people at that high a level in your physics courses?
We didn't have that type of survey course. I did have a semester course that was given by Millikan. That was not given to everybody. That was kind of an optional course. Supposed to be on atomic physics or something. It turned out to be mostly reminiscing. I should have had a tape recorder on that one. But we had the bread and butter courses in physics. We had a whole year by Paul Epstein, who gave a semester of thermo and a semester of E and M and a semester of — what, I don't remember, it was statistical mechanics or something like that — and then we had some other bread and butter courses. 0ne was given by William Smythe on electricity and magnetism. We went through Jeans' book. Then we had optics from Bowen.
Apparently he used Drude's book.
— Yes — terrible book, to understand. It's probably correct in every fly speck but it's an awful book to read.
It remained the standard for a long, long time. Did you have optics laboratory too? Was that required?
I don't think I had an optics lab. Then we had two years of — we had a year of German and a year of French and we had English I guess for those first two years of the general course.
How about Houston, did you have him for any courses?
No, I didn't have Houston. I had Tolman in a series of evening seminars, but at the time nuclear physics was just beginning. This must have happened about 1931 or '32, when people were trying to understand Gamow's book and various new things in nuclear physics. Tolman gave a series of evening seminars, just out of the kindness of his heart, where you learned these things about penetration through potential barriers and so on, and gave us a seminar, so I went to that.
As a graduate?
0h, we were graduates by that time, yes.
I was talking about the undergraduates.
Several people gave seminars like that, just because they felt like it. 0ne year we had a seminar that was given in the Kellogg lab — I guess nominally under Lauritsen's auspices, but anyway Dumond was a featured performer and he helped us go through Siegbahn's new book, which has just come out at that time, on x-rays, so Dumond came every time, and helped us understand that.
So when something new came up there'd be some response from someone on the faculty.
We had an evening seminar that lasted quite a long time, I don't know how long, three months or six months, at the time that Rutherford, Chadwick and Ellis's book, I don't know whether to say new what, but anyway a book — it was probably just a new edition but it came out in the early thirties, —
1930 yes —
When that came out, that was the occasion for a series of seminars, and we just damn well went through that book, you know, page by page, in a seminar.
There's an awful lot in there. Great big compendium of everything.
Just a volunteer group of mostly graduate students and a few professors, met once a week and just went through that.
So the appearance of a book precipitated this — Siegbahn, Gamow and —
Definitely in two cases, the appearance of Rutherford, Chadwick and Ellis and the appearance of Siegbahn's book were occasions for a seminar in which we just tried to go through them, more or less, and understand them.
Just after you arrived there, the whole quantum mechanics breakthrough occurred. Do you recall any awareness of this? Do you remember whether any of it got into the coursework?
As an undergraduate in those years '26 to '30.
As an undergraduate? No. I don't recollect seeing any of it get into the undergraduate. 0h, yes, I do. No. No. And I told you — the reason I was hesitating. I told you one wrong thing a while ago: Paul Epstein's series of three topics that he treated in a year was at the graduate level, not the undergraduate.
You weren't exposed to Epstein on the undergraduate level?
I'm trying specifically to see if you got any theory as an undergraduate — nothing but straightforward theoretical physics; and of the faculty those are the two, Epstein, Tolman, you'd think most readily would be able to supply that.
When I was a graduate student, the early part of my graduate work, 0ppenheimer came down. You know, he used to go to Cal Tech one semester of every year. He had a class on quantum mechanics. I sat in on that. But this was graduate. No, I don't specifically remember any quantum mechanics coming into it when I was an undergraduate — in the undergraduate program at that time.
I'm looking for the list of courses, to see if it's reflected at that level — looking under advanced subjects too. "Heat Radiation and Quantum Theory" taught by Epstein, that's an advanced course.
Well, Epstein, I don't know whether you have the picture of how he taught. As far as I know, he never taught in the classroom. He was a very formal type of a lecturer. He had these several lectures that he could turn on and off. They were very fine lectures. I don't mean to say they were prefunctory or anything like that. He was an expert and they were very fine lectures, but nevertheless, he gave them in a formal way and he had a one term lecture on E and M and a one term lecture series on thermo, a one term lecture series on something else, and he would give these in rotation. The graduate students were supposed to hear all of this series of lectures. And Epstein would come in at the beginning of the hour and everybody knew enough to be there in their seats when the hour began, because he would be very bothered if they weren't. He'd come in and start out by saying, "Gentlemen, last time we were considering —" and he'd start in the exact place that he left off the time before, and he had exactly an hour's worth of things to say. Just at the end of the hour when the bell would ring, he would be putting the last period after that lecture, and if somebody stopped him in the middle to ask a question, that was very disturbing to him. It threw him clear off schedule.
The European style of lecturing.
European style, yes. But they were beautifully organized lectures. They were not available in written form and students all had to sit there and copy all this stuff into the notebooks. That was the only way to get
Did you save those notebooks?
I think they're somewhere at Cal Tech. Also his lecture notes are preserved, Epstein's.
I'm sure they must be. There were thousands of them copied down, you know.
I mean, his own notes. I'm looking at the course list here and I see Epstein was listed for the following courses: and under each of these, it's indicated for this catalog, "Not given in 1930-31" which is the year of this catalog. Higherdynamics, heat, radiation and quantum theory, physical optics and Quantum Theory of Spectral lines, Modern Aspects of the Quantum Theory, which gets into principles of correspondence, Heisenberg's form of it, Born, Jordan's matrix calculus, Schrödinger's wave equations, still not given in '30, '31. The one that was given was Introduction to Quantum Mechanics where he deals with matrices and tensors, Schrodinger's partial differential equations, Dirac's transformation theory, that kind of thing. 0ppenheimer gave quantum theory but not in 1930 and '31. Quantum Theory of Radiation. I should get the catalog of the early years and get an idea when these more modern things were introduced, interesting to find out.
My other courses were pretty much routine. I took mechanics from Zwicky. We went through Lamb's Mechanics. I guess I already told you, I took E and M from Smythe and went through Jeans. That was an interesting course. At the time I took it I thought it was the worst taught course I'd ever witnessed in my life, because Smythe didn't do a thing except come in and force us to do our own work. He'd come in and, we had assignments every day to do these longwinded problems that are in Jeans, British type problems, and we were supposed to have done them before we came back the next day. And then he would pick somebody to go to the board and put the problems on one after another, and that constituted the entire course, and he just sat there. I remember particularly Selby Skinner — you know him? — was the star performer. He always had the biggest and longest solution, most erudite solution to all these problems, and he'd put it on. I thought it was a hell of a way to run a course because Smythe didn't ever tell us anything. But in later years, I realized that I retained a great deal more from Smythe's course than I did from a lot of others. And Zwicky was a little bit the same. He'd just sort of grunt at us and make us put the problems on the board.
A lab, in a sense. But, what about lab for example? What did you do? It seems to me that kind of education was taken up a great deal by the amount of time you have to spend in the laboratory.
I don't think we spent a great deal of time in labs. 0f course, I had physics lab with the undergraduate beginning physics. As a matter of fact, Walter Michels was my teaching fellow when I took lab, when I began, in the beginning. Yes, I just don't remember much laboratory work that we had.
For example, you were required to take certain chemistry courses.
0h, chem lab, yes, we took chem lab. I think I probably had two years of chem lab. I think we had two years of chem, and I think we had lab all the way through. We had general chemistry, then we had analytical chemistry, and we had P Chem which is Physical Chemistry — which was pretty much a theoretical course, solution of problems, like mass action and all this, fairly complicated problems. We used Noyes's book. I had a fairly famous guy for chemistry instructor. That was Arnold Beckman.
Was the P Chem course something where you'd get involved in thermodynamics or did that come in some other, some physics course?
Yes, I think we had some. I don't clearly remember what was in Noyes's book, but that's what we went through, and worked a lot of problems. But I don't think — all of this certainly didn't take more than two years. Because there was general chemistry, then we had analytical, and P-chem. I'm glad I had it though.
Were there any other research discussions or keeping up with trends in science, other than strict involvement in coursework?
Yes. Journal club activities an undergraduate could get involved in or some kind of science club, something like that.
There wasn't a science club, as I remember. There was a lecture once a week in the afternoon in Culbertson Hall where we were all supposed to go and absorb knowledge, but I think that was more of a generalized type of lecture. They brought a lot of people to the campus, like Sir James Jeans.
Sommerfeld was there during this period.
0h, Einstein was there. Cockcroft. He wouldn't have come till after 1930.
He came in 1933, your graduate days.
Earlier, they brought quite a number of important people there, and they gave lectures and we were supposed to go and hear those. But there wasn't any journal club as far as I remember. Most of that kind of thing was in graduate years.
What about extracurricular activities? Did you get involved in any as an undergraduate?
Not much. I played in the orchestra, I think all my undergraduate days, so that was one late afternoon every week. I also played in the orchestra through high school. Then when I graduated from college that was the end of that.
Violin. I played tennis, for an accidental, almost, reason. When we arrived at Cal Tech as freshmen, they told us to select a sport. There was an honor system. They had a little box. Every Friday afternoon you were supposed to fill out a little 3 by 4 inch note as to what you did, how many hours you put in at your sport that week, and drop it in the box, so it was the honor system. You could select your sport. Well, I don't like the contact type of game, football, things like that. I wasn't that type. So I just picked tennis. Well, I had to put in, I've forgotten how many hours, two or three hours a week, for four years, tennis. I got to be a pretty damned good tennis player.
You weren't involved in teams?
No, I didn't go in for that. I always did sports against my will. I did some in high school too, but I did what they forced me to do. I never went out for any teams if I could avoid it. At one point I threw the discus too far and I got put into the lightweight discus track team, you know, put on the track team as a lightweight discus thrower and I got sent to I guess the last of the county meets and had to throw the discus. That was a great mistake that I threw it too far when I was practicing and got put on that team. I didn't like it a bit.
Did you ever duplicate it with
— I don't think I won anything.
I wanted to ask you about some of your classmates. In that period there's a whole group of people I know who I think must have gone — must have overlapped with you. I'm not sure, there was a whole generation of — Carl Anderson at one stage may have been an undergraduate when you were, I'm not sure how it worked out with McMillan and Evans for example, a number of other people.
Well, I remember about those guys. I remember Robley Evans. He was a year ahead of me. At that time, every year Cal Tech gave a travel prize to the top students. I don't know how many received it every year, at least a couple I think.
Eight — when he got it there were eight.
Eight? He got one of the travel prizes. When they came back they had to give a speech before the rest of the students and tell about what wonderful things they saw. I always remember Robley's speech because it was a very cultural type of speech. He'd gotten interested in music in Europe and brought back a lot of records, and his speech consisted mostly of having a phonograph on the stage and playing music for us.
He played in a dance band in his college days. Percussion — I'm not sure. You weren't in classes with him, he was a year ahead?
No, he was a year ahead. McMillan I guess was a year ahead or somewhere, because be wasn't a contemporary.
They were classmates, McMillan and Robley, and Anderson was still further ahead.
He was still further ahead because when I was a graduate student I think Anderson was already on the faculty. He was working with Millikan, and he had built that magnetic cloud chamber in the Aeronautics building at the time I was a graduate student. In fact, when he first got our high voltage tube going and made (telephone interrupts)... Well, when we first got our high voltage tube running, and this was the time when, very soon after artificial radioactivity had been discovered, we made sources — they happened to be positron sources — and we ran over to Carl's lab and he would open up his cloud chamber, and put them in there, then close up the cloud chamber and condition it and get pictures. Quite a job, because the cloud chamber was put together with a whole row of screws that held the glass plate down. He had to disassemble that, put our hot source in there, and this was for — as I remember it, Nitrogen -13 which is ten minutes' half life, so he had to work pretty fast to get those in there and then get pictures of the positrons, very strongly bent, of course, because he had a high energy field. And these pictures that he took were the pictures I used in my thesis, because I was working on these radioactive samples for my thesis, and he took the pictures that I used for my thesis. But I think he was on the faculty.
How about your own classmates, the people in your own class? I'm talking about the ones who went on in physics. It would be nice to know who some of them were. Do you recall, you were particularly friendly with them?
My PhD class, you mean?
No, this is still undergraduate.
0h, undergraduate. Let me see if I can help you out a little —
I have the graduate lists but that's something else. There were 15 in physics in 1930-31, I don't know if that
You have a list?
I have the names of those people — the thing's broken down by fields.
I have the Alumni Directory but it's only an alphabetical list, and then — oh, yes, here's the class list. Well, in science, you want —
Science but I'm curious if you can remember anyone specifically in physics that you graduated with.
Well, here's Chet Carlson, the inventor of Xerox. He was a good friend of mine. He was in my class. In fact, I take a little special pride in the Xerox invention too because when he left Cal Tech, he went to work for Bell Telephone Labs. I'm not sure that's the first job he had but at any rate, very soon he ended up there, and he got into the patent department. Then he went to night school and got to a patent lawyer, got his papers so he was a lawyer. Then he got interested in the possibility of electrostatic printing and various other things too, I think, and started doing some work at home on his own. Finally the conflict of interest became too great, because he was in the patent department of Bell Labs and trying to make inventions of his own. So he left Bell Labs and went on his own. At any rate, during that period when he was working on things at home and working on the electrostatic process, I used to, every time I'd go to New York I'd have lunch with him, and he would always try to pump me on things about electrostatics and so on because that was his main interest at that time. We talked about this series that you can take various substances and put them in a series such as everyone above — you pick any one above something else, why, that'll steal charges, any one above will steal charges from anyone below. You can put them in a list like that. We used to talk about that, and he used to tell me all about what he was doing and how he was doing it and so on. At that time I didn't think too much of it. Something that might amount to something possibly.
He was a long time I think in coming to it —
You know, the electrostatic printing process goes back way before Carlson. There were attempts at it that of course didn't work out to a practical system. I know that some German inventors played with it a long long time ago.
I think Carlson himself wrote an historical account of this — the first section of a book that was published, that we have in the library. A 30 page pre-history of his own book. Who else in that class do you recall?
I see some other names but I don't know that they're prominent in physics at all. Let me just look through the list here. Nope.
When you were approaching the completion of your undergraduate work, was it clear to you that you wanted to go on to advanced work, and that you would be allowed and encouraged to do it? How did that occur to you?
No, it wasn't clear. It wasn't clear. I did a little bit of floundering and there was a little bit of indecision, when I did get my bachelor's degree. In fact, let's see — in the summer after I got my bachelor's degree, I wanted to go to Europe. My mother was interested in going too, so the two of us got on a freight ship that went from San Francisco through the Panama Canal and took 28 days to get to Europe — that's one hell of a long time, it seemed before we got there. So we went around and saw a lot of the usual things, you know, cathedrals and all that, and I had a kind of a half an idea that I might want to go take some graduate work in Europe. So in the course of this, I went and looked around at Zurich and also at Gottingen, just kind of window shopping, you know. I finally didn't stay there, decided to come back. We stayed on, I guess we must have gone about the middle of the summer and we came back a little late, September or something, and then she came on back but I stayed in the East because I wanted to see some other things. I spent a little time in New York and at that time I saw quite a bit of Chet Carlson. Then I went to Pittsburgh and went through the steel mills. I went to Detroit and went through the automobile factories. Did a lot of things, that I wanted to see. But also while I was in New York I went out to the Bell Labs and talked to their personnel man about a job. Well, it wouldn't have made any difference whether I wanted a job or not at that time, because they didn't have any jobs. That was 1930. Late in 1930. And I even went out and I guess more to visit than to ask for a job, but anyway I did talk to them about jobs, at the Edison Laboratories out in 0range, New Jersey. As I remember it, I wasn't really — you know, I was still indecisive about what I wanted to do. I was looking around, floundering around. So I finally decided, better go back to Cal Tech, get my degree. So I went back and I was late. I didn't get there for the opening in the fall, but I got there late and started in, and then stayed right there till I got my degree.
Didn't you have to make any prior application?
Yes, but I had a decent record as an undergraduate and when I applied, they just said yes. I guess things were different in those days.
But you hadn't applied till after this summer?
I see. What did you have in mind to do if you didn't... (off tape)
I was asking whether you had any specific plans in mind that you would pursue if you didn't go to graduate school.
Not any more specific than that it would be scientific or technical work.
Certainly physics though?
Well, yes, sure, more or less.
Your undergraduate degree was specifically a BS in physics, but you hadn't picked out any particular faculty member to work with?
You mean whether I wanted to do nuclear X-rays?
In other words, you presented yourself and were accepted for advanced work. Then what was the procedure that got you into a specific research problem?
When I got there, I was told to go and talk to somebody and I guess maybe it was Ernest Watson, to try to get situated. He told me of one or two faculty members who had openings for graduate students to work with them on projects, and told me to go around and talk with them — just like it is now. So I went around. I've forgotten who else I talked to besides Charlie Lauritsen, but Charlie at that time had that big X-ray tube. He hadn't gone into nuclear physics at that time yet but he wanted to. But he had an X-ray tube that he'd had up to 800,000 volts or something. And that appealed to me, and Charlie and I seemed to get along all right, so he said he'd put me on. 0f course I didn't have a lot of time to put on his project because I had graduate courses to take, but I started in at that time and helped him with his tube. Then my job I guess immediately was to start getting an ion source into that, very soon after that anyway, getting an ion source into that tube so we could make an ion beam and start trying some nuclear physics. Now, this was '30 — no —
'32 was when you did that, it was after the Cockcroft-Walton.
Let's get the dates straight. I got started with Charlie about the winter of — no, I got my degree of '30. Then I must have gotten started with Charlie just about the end of '30 or first of '31. I was working on Charlie's project when the news came through from Curie-Joliot about making radioactive nitrogen-13, so I had already, I was already working there, so I guess we must have — the job of turning the tube into an ion beam tube — no, that was —
— early in '32 —
— no, I know how it is now. We started right away when I went on with Charlie to start in building gadgets and things to get ions into the tube, and the motivation for that was Cockcroft's work.
0h, you mean before their disintegration?
No, Cockcroft's disintegration of lithium. 0r was that '32?
That was '32. It was around May of '32, in the spring. You got a paper, I think it's on your own, in '32, your first paper as a matter of fact, with Lauritsen, High Potential Porcelain X-ray Tube, which was presented at the Pasadena meeting of the Physical Society. Then the next paper is the Artificial Production of Neutrons, in '33.
0K, I guess after I want to work with Charlie we continued to work on X-ray tubes for a while, because I know that his motivation for putting ions in certainly came from Cockcroft's discovery.
Do you recall how he heard of it or you heard of the Cockcroft-Walton work?
I don't know but it certainly was the talk all over Cal Tech. This guy had disintegrated lithium with protons. I suppose it came out in Comptes Rendus or some —
it was in PR0CEEDINGS of the Royal Society or NATURE or both. I was wondering if there was any personal contact because I'm not clear on the details. I think R.H. Fowler was in Berkeley at the time.
The reason I said Comptes Rendus is that at that time, that was one of the means of quick publication.
That's interesting. In this case I think Rutherford rushed it into the PR0CEEDINGS of the Royal Society and within two weeks it was published. But I want to focus on this period from '30 to '32, what I call the pre-nuclear physics period. At the time, the tube was being developed, the highpotential X-ray tube, it was being partially supported with medical money, which paid for —
— well, that was a little later. It wasn't at the very beginning, don't think. You remember, I'm sure you know, that Cal Tech used to have what's called the high voltage lab. When the Southern California Edison Co. built one of their big power lines, they had to test the insulators and things, and instead of building their own test laboratory they built this high voltage lab on the Cal Tech campus, and they did their testing in that, but the lab contained a set of transformers that would give one million volts at one ampere. That's a lot of stuff. Huge transformers. Well, the Southern California Edison Co. of course only used it once a month or something like that. They had very little use for it at that time. They kept the privilege but other people could use it other times. So Charlie went in there and set up his X-ray tube in a kind of an igloo in the middle of the floor and used those transformers. That's how he got started in high volt X-rays. Then a little later Seeley W. Mudd — who was interested in rather long term big experiments on treating cancer patients — built the Kellogg Laboratory and financed the X-ray tube which Charlie and I built, Charlie built it, and I was very much involved in setting it up, in that Kellogg Lab. I suppose, now that I think of it, maybe all that came before we started in on nuclear physics.
Let's try to pin down the exact sequence. The second tube was built. An electron source was in one and an ion source in the other, and there were two tubes operating, one in the old High Voltage Lab, one in the Kellogg Lab, which then meant the high volts one could be used more for nuclear physics and the Kellogg one in therapeutic work. I think this was around '33, after the Cockcroft Walton, but we can pin it down with publications.
You're saying that probably
I should get the date of the Kellogg thing, I know it. (1930-31)
See, they even brought patients into high volts before the Kellogg thing was ready, and I suppose you're right in saying that they couldn't convert the high volts tube to ions until they could move this cancer business over to the Kellogg Lab and get rid of that, then the other —
I'll check on the exact story. Let me ask the things that would maybe we're more sure of than the dates; first of all about the work you reported on in '32, about the high potential porcelain X-ray tube, the name of that paper. This is a period when you're taking courses. Were you teaching, doing any instruction. Whatever time you weren't in courses, were you in research? About how much time per week did it work out that you worked with Lauritsen?
It's hard to say, but I — it seems to me an awful lot of it was in the evening. Charlie was a great evening worker. His wife is a medical doctor and she was usually busy with her own business, and Charlie liked to stay over at the lab or go over to the lab in the evening. His wife would work on her medical degree that she was working on and he'd work at the lab. An awful lot of time was put it in the evening, so I think I did a lot of this in the evening. I'd say at that time I probably put in half my time on research.
The first part of it was not as much research as building this setup — converting the material so it could be used for ion work.
Well, you see, I think the sequence was that we built this high voltage porcelain tube, which was made of an enormous conical shaped porcelain insulator that came off the top of a big transformer or something, five feet high or more. We built that to see if X-ray tubes could be built that way, and I think it did work up to 600,000 volts or something like that. Previous to that Charlie had built his X-ray tubes out of these glass gasoline cylinders. But we built this one out of porcelain and it did work. Then that was the one, I think, the first one we put an ion source in.
Yes, right. You were working on that before the Cockcroft Walton.
The X-ray tube. It's an interesting interlude about the little brouhaha, you might say, about heavy water that came about this time, beginning of our adventures in nuclear physics. I don't want to forget to tell you, it's sort of funny.
Make sure you read the letter from Lawrence to Cockcroft, September 23, 1933, and he said, we're skipping a little — "Richard Crane who was working with Lauritsen was in our laboratory last week and we gave him a sample of heavy hydrogen with the request that he bombard various elements and look for neutrons. Day before yesterday we received an airmail letter from him to the effect that he got no appreciable number of neutrons when lead was bombarded with 900,000 volts deutons. This result conformed to our expectations that the threshold would be around 10 to the 6th volts. This morning we received a telegram from Crane saying that he has bombarded beryllium with deutons and has found neutron emission starting at 400,000 volts which rises rapidly to a peak of 900,000 volts, 500 times that obtained when beryllium was bombarded by 900,000 volts alpha particles." Then he said, "This is in agreement with our expectations though interpretation is as yet ambiguous. Whether or not the beryllium-9 is disintegrated without capture of the deutons or the deuton itself is split is yet to be determined." Then the issue of the neutrons came in here. There are a couple of things involved. 0ne is the experiments that you were doing with Lauritsen, which depended on production of gamma rays, and which implied or suggested the mechanism of radiative capture, which 'Lawrence apparently was unwilling to accept at first.
That was my thesis. That was my thesis. "The Capture of Protons by Carbon-12."
0K, but I'm trying to get the sequence. Then we can reconstruct it. Apparently this was after Lawrence's idea of the disintegration of the deutons, as he called it, had been proved to be wrong because of the deuterium contamination, and he was then claiming that the same situation was involved in your case. 0K. I do understand the bare outline and we can reconstruct.
But you see, what I worked on was the resonant capture of protons by Carbob-12, at about 400,000 volts, and it's very sharp, so it couldn't possibly be due to contamination. It was a sharp line at 400,000 volts, although it didn't look very sharp to us because of the poor energy resolution in our tubes at the time. Anyway, it is a sharp resonance, and that distinguished it from the background effect. That made nitrogen-13 — and that's the thing that we ran across the street to Carl Anderson with and had him put in the cloud chamber and he measured the positrons from the nitrogen-13, which pictures I put in my thesis. There again it couldn't have been contamination because you wouldn't have gotten the positrons from it, with a ten minute half life, which — you know, everything proved it was nitrogen-13. But maybe in the first flush we didn't have that proof and Lawrence had reason to suspect it was contamination. But I wanted to tell you a little story, and I want to tell you right now, about my run-in with G.N. Lewis over the hydrogen, over the deuterium.
I want to pick up that and pick up the story about Tuve's involvement in this too. It seems to me that great care was used by you and Lauritsen, in making sure there could be no question about the results, for example, the absorption curve, and then the comparative energy excitation curve again, later on, the gamma ray work. Also the question of the misleading results on the Compton electrons and the gamma rays. That did turn out to be an error later on. There are a lot of issues that did seem to cluster in a three year period there. 0K, why don't we say, whenever we can get back to it, we pick up at this point. I have to look at some letters and so forth in between.
We're resuming on the 29th of March, hopefully where we left off yesterday.
I want to go back and add one thing to the question of where I got my information about radio and things when I first started fiddling with it. I mentioned the SCIENTIFIC AMERICAN which really wasn't radio but it was technical stuff. But I remember now that as soon as I began the ham work — I suppose I started fiddling with it around 1920, I think my first license was '21 — I surely must have subscribed to QST, because the American Radio Relay League which put out QST was the main organization for hams at that time, and every ham belonged and every ham got QST, so I surely started in at that time, and of course QST is just for the purpose of giving information to hams about how to build equipment and things. So I must have gained a lot of my stuff from QST beginning at that time. But in my town, in Turlock, there was very little, except what I got by such things as QST and SCIENTIFIC AMERICAN. It was not a technically oriented town. They were interested in watermelons.
Maybe in mechanical harvesters or watermelon pickers? But there was enough technology of the time available, for example, on automobiles, that kind of thing going on —
oh for picking up, getting scraps of materials and things like that, sure.
We were talking when we broke off yesterday about graduate work at Cal Tech, after you had switched over with Lauritsen to nuclear physics. I have a number of questions on the whole period. You raised a point, though, regarding your relationship with G.N. Lewis, at Berkeley, and I don't know what the story is.
Yes, I wanted to tell you a story about that which is somewhat amusing in some respects. Let me preface it by saying, when heavy water was first made or soon after it was first made, there were a lot of wild stories in the papers about the fact that heavy water was extremely toxic, and in particular there was an article in which somebody had made some sugar solution out of heavy water, a very small drop of it and fed it to some flies, and he claimed the flied died immediately — which of course was not true, but anyway this was in the newspaper. Well, now, let me go back to my own experience with heavy water and this thing about the flies will come back in. I went to Berkeley soon after heavy water became known and we knew that G.N. Lewis at Berkeley was making heavy water in small quantities. I guess we learned that through Ernest Lawrence and his group because they were of course interested in it too. So I went to Berkeley, and succeeded in coming back with one cubic centimeter of water which was 20 percent heavy. I got this from G.N. Lewis upon all kinds of promises as to what I would and would not do with it and so on — considered it a great privilege to have a little bit of this water. So I brought it back to Pasadena. We had our tube operating at that time with an ion source so we could put it right in. I had to set up some equipment to decompose the water and make hydrogen gas out of it, deuterium resulted in the first Letter to the Editor on the production of neutrons by deutons as they were called at that time, I think on beryllium. gas, and we did that successfully and got it into the ion source, and that Well, actually — this is incidental to the story — but we fired off our Letter to the Editor, and it turned out that we beat the Berkeley people to it on making neutrons by bombardment with deutons, and they were a little bit — well, it got them a little excited, so I think they fired off a letter also or telegram to the editor and got their report in also. That was all friendly competition, but we did beat them to it. But at that time there was a guy at Cal Tech by the name of Rudolph Langer, a somewhat colorful character. I don't believe he was actually on the Cal Tech faculty but he was around there doing some kinds of theoretical research, and among other things he hired himself out to the Hollywood movie studios to design scientific apparatus for when they had science or "amazing story" type movies. He designed the fantastic apparatus for them. And he used to write various things for the newspapers. I think later he had something to do with the Planetarium in Los Angeles. At any rate, about the time, right after I got this heavy water from G.N. Lewis, Langer got excited about the report about it killing flies. So he wrote an article, first telling about the fact that we'd gotten heavy water from G.N. Lewis, and then went on to say that deuterium was going to be the eventual death of mankind on the earth, because light hydrogen being more volatile than heavy hydrogen would slowly disappear from the earth and leave a residue of heavy hydrogen and that would kill all living things on the earth. As I remember it, this article contained G.N. Lewis's name in some connection or other. Well, that blew the whole thing. That was the end of our source of heavy hydrogen from G.N. Lewis, — he got sore as hell about it. So, realizing that, I decided that I had to put up a factory of my own to make deuterium, and so I went to Los Angeles to the industrial section one day and looked around the second hand places that carried electric generators and things, and I found an old antique low voltage DC generator of several kilowatts. I think it was six volts or something like that, which is what you need for electrolysis. I got it transported to the high voltage lab, and then one Sunday I mustered a whole bunch of other graduate students and we hoisted the thing up onto the balcony of the high voltage lab and set it up. Well, the next week, Royal W. Sorenson, who was the head of the electrical engineering department and I guess formally in charge of the high voltage lab, created a storm, because he said we had no permission to put this horrible looking old generator up on the balcony of the high volt lab which is supposed to be a place for people to walk around and look at the sparks, and we had to get it off... So I had to re-assemble the graduate students and we got the thing off the balcony and down on the floor. Then I set it up on the floor next to our high voltage tube. I got some electrolytic cells made over in the, I think they were made in the astrophysics shop, which at that time had just started, they were building the parts for the 200 inch telescope.
Were they on Santa Barbara St.?
No, right across the street from the high voltage lab. I got them to make some big electrolytic cells out of iron, and of course you had to have a whole series of cells getting smaller and smaller as you concentrated the stuff down. Then you had to have provision for recycling and you had to have provision for decomposing the water. It was quite a little factory that I set up. And then for some years I guess I ran that thing. It just sort of ran itself with some tending every day or so, and we ran that and made our own heavy water, for all the rest of our experiments — not all the rest of them but for quite a period, before it was possible to buy heavy water, and when it did become possible to buy heavy water it was extremely expensive, $100 a gram or something like that. Now it's cheap as soda pop practically. So that's the story of how we got into the heavy water business.
You were forced into it essentially.
I was forced into it by Rudy Langer, who blasted all our changes of getting more from Berkeley. I don't know whether we would have anyway or not.
The letter that I started to read the other day touches on that. I wonder if he's referring to the same thing. It was Lawrence writing to Cockcroft, September 23, remember, and said "Richard Crane who is working with Lauritsen, was in our laboratory last week" about September 16, I'd say, '33. "We gave him a sample of heavy hydrogen, — bombard various elements and look for neutrons." Is that the time you're talking about?
Well, we only get one sample, so I guess that must be it. When he says "we" he means G.N. Lewis.
Here's the thing interesting about your publishing results in that paper with Soltan and Lauritsen. Lawrence knew about it before the paper because you wrote him and telegraphed him. In other words, he couldn't have been caught by surprise with publication, because you informed him. He regarded that as confirmation of what he had done, and the telegram — that you'd found something else — so that story you told me is right around that date. Am I right in saying that this is the beginning of Lawrence's discussion of the disintegration of the deuteron or deuton as he called it. It's mentioned here, just before he went to the meeting of the Solvay Congress, where he argued with people about the mass of the neutron, and —
— Well, understandably, they got off into kind of a blind alley for a little while, because they started bombarding things with deuterons. I suppose we should call them deutons. And they got neutron production from almost anything they bombarded. And that of course as you know later turned out that the deuterium was being absorbed into the target, so what he was actually observing was the dd reaction. And it wasn't the element of the target at all. It was collecting some of the deuterium from the gas in the chamber that we being bombarded.
Well, what was the reaction at Cal Tech to that, to his results? When those results were published and his ideas were coming out, was there skepticism at Cal Tech, or just complete independence? Was an issue developing, in the fact that your results were different? You weren't doing exactly the same experiment, of course, but was there any discussion of reading his papers and raising the question regarding contamination?
I guess there was, but you know, nobody knew enough about nuclear physics in those days and what reactions were possible to really dispute things like that. I think Lawrence himself found the answer to it as rapidly as anyone else. Just a matter that you have to do more experiments and —
I think 0ppenheimer played a role in bringing the news to him of results that were taking place in Pasadena. From the Lawrence biography, there's a point on this, and "The new cloud chamber showed nothing to support the deuteron hypothesis." That's the new cloud chamber at, well, I don't know where, anyway, "Word from Lauritsen through 0ppenheimer of his 'beautifully clean' experiment seems to clinch the argument against it by showing that calcium deteroxide bombarded by protons 'loses hydrogen-2 which joins the beam and terminates it.' "That is," the disintegrated calcium deuteroxide releases deuterium gas in the cyclotron chamber, contaminates the ion source" and so forth. This is what I'm getting at here. Your experiments were very clean, from reading the papers, great care being taken with the line absorption curves —
Yes, we, I guess, had that extra check on our results, in that we did run a lot of gamma ray absorption curves and neutron absorption curves, in order to get some idea of the — well, first of all, whether it was gamma rays or neutrons, and secondly to get some idea of the energy of the gamma rays if they were there. So right from the very start we depended fairly heavily on absorption methods for identifying the radiation. And I think maybe at Berkeley they didn't do so much of that. It wasn't possible with their experimental arrangement. See, our target was much more accessible than the target in a cyclotron, because in an accelerator tube you have the target down at the end of the long pipe so you can put absorbers right around the target very easily. So I suppose it was partly that reason that we did quite a lot of absorption.
Right. The implication of the thing that I read is that it was because yours were better controlled that Lawrence had to respect it, this played a major role. 0f course you were getting feedback, I know from the letters from Lawrence — there were arguments about this. Now, let me ask at this point about 0ppenheimer. When you started doing graduate work, was he involved? Was he talking at that time, on his visits with Lauritsen, about the tube you were working on prior to 1932?
To 1932. I think as long as I knew Lauritsen, I think it goes back to the very beginning when I knew him, when I first came to work with him, he and 0ppenheimer were great friends. Every time 0ppenheimer came to Pasadena, why, he spent a good deal of time with Charlie. They were very good friends. I think this situation went back as far as I remember Charlie, he and 0ppenheimer were close friends, and I'm sure for that reason 0ppenheimer followed closely and gave a lot of advice to Charlie on everything Charlie was doing at that time.
Do you remember discussions of this work, for example? 0nce you got into nuclear physics do you remember discussions with 0ppenheimer? Certainly by 1934 when you had the paper for the Cambridge meeting in England you talked about 0ppenheimer's ideas.
Yes, I'm quite positive that from the very beginning of our experiments on nuclear physics, 0ppenheimer used to come around and look at our results and talk about it. The only question is my mind is whether this goes back into the X-ray period. I'm a little more vague as to whether, before the nuclear physics period, when Charlie was still working on X-ray tubes and things and of course I worked on X-ray tubes for a while too before we started nuclear physics. I just don't remember whether during that X-ray period 0ppenheimer followed the work very much. I know he followed the nuclear work very closely. Q; For a minute I'd like to get back to Lauritsen. You came, looked around as a graduate student. You explained how you got involved working with Lauritsen on this project, but had you had any contact with him prior to that time? He came in '26 himself and took graduate courses. He got his PhD in 1929, but I realize he was over age.
No, I hadn't had any contact with him. I think contrary to the way we do things nowadays — where graduate students are put in a holding pattern for a couple of years while they take courses and are not given any chance to get connected with projects — I believe at that time at Cal Tech, as soon as a graduate student showed up who wanted to do experimental work, he was put on as a floor sweeper or something with some project, with some professor, and made an association right away. So I'm quite sure that I went over and I started my association with Charlie's project essentially as soon as I came to Cal Tech as a graduate student. It was just a matter of helping around, doing a little carpenter work or something like that. That's the way you started. I think my first, one of my first real jobs that I did was to make a vacuum pump, you know, get it drawn up and get the shops to weld it and things like that. And of course the porcelain X-ray tube was my first real piece of construction, and the heavy water machinery I set up, and then also I was drawn into the construction of the X-ray equipment in the Kellogg Lab. I remember I built a huge long water column, consisting of a zigzag glass tube about a few hundred feet long all folded up, which was used as a protective resistance in series with the X-ray tube. I made all that thing, did the glass blowing for it and put it all together and hung it up in the Kellogg Lab, and I assisted on setting up the X-ray tube in the Kellogg Lab, and I remember one thing in particular. The thing consisted of a metal pipe, you might call it, about maybe 18 inches in diameter or so that extended from floor to ceiling in the treatment room, that is went from the floor to ceiling of one of the middle floors on the lab. That was the floor where the treatments and control room and so on were. Then the glass part of the tube stuck out above the ceiling and below the floor of that treatment room. There was the glass part of the tube on one end, and then below the floor there was a glass part on the other end, so the metal part of the tube occupied one floor and the glass parts were on the floor above and the floor below. This metal part had some ports and various things in it, and I was the only guy around the lab that had narrow enough hips so that I could be lowered by a block and tackle down into this metal part of the tube. So I made many trips down into there on a rope and block and tackle from above, to work on this thing on the inside. The other guys that were around the place at the time were Delsasso, who had a pretty wide bottom and he could never think of going down in there, and Willie Fowler, I don't think could get in there either. So I was elected. That's just a little interesting aside. Anyway, this is to the point that I did spend a great deal of time, at that period when Charlie was setting up the X-ray tube in Kellogg for the purpose of treating these patients, on the program that Sealey Mudd was embarking on.
For good reason, because according to the Cal Tech directory, they list you as being supported by the High Potential Radiation Research Fund, getting a stipend or something from them. Certainly after your PhD you were a fellow there.
I was a research fellow for a year after my PhD.
I'm not sure you were on that payroll.
I think I was on the payroll — maybe in the summer time or something like that. I never did, up until I got my PhD, I was never on a stipend, not on a regular fellowship or something like that.
Let's talk again about Lauritsen. I wanted to ask about the working relationship. It seems that it began very soon after you started. Certainly your publications started coming with this paper at the American Physical Society meeting in '32, the X-ray tube, and then in '33 the whole series. What kind of a working relationship — in terms of choice of problem and approach to it, discussion of results, writing of the paper, apportioning of credit and so forth — did you have?
Well, we were a small group. I think we sort of operated in a way like equals. I mean we sort of alternated on the order of our names on the papers, and I think the way a lot of the papers got written is that I wrote them first and Charlie would help us go over them, and I think actually in most cases that the rough part of it anyway was started by me and I did all of the draftsman work for all of these papers. I had a couple of years of mechanical drawing in high school and I still kept my instruments, and it turned out that I did all those graphs and things like that. All those were done during that period. I kept the drawing board in my office all the time and anything that needed to be made up for publication like that, I did.
Do you have a full spread of your reprints?
Well, up to a time I do.
Enough to make a duplicate set?
I only have one, I only kept one of each, that early period. think I have one of each.
I was thinking we could have — if you had an extra set — otherwise I could get it from journals.
Well, it's easier to get it from my file. You alternated the names. But I get the impression from the few I looked at in the early period that it was alphabetical basically, as it worked out, Crane and Lauritsen — I guess later on when Delsasso and others were involved that there was a different approach.
Well, that may be true. I'm a little vague at this time on how we divided things like that.
I'm looking at a paper, "The Artificial Production of Neutrons" in April of '34, and in that you were acknowledging G.N. Lewis who furnished the heavy hydrogen for your experiment.
Is that the PHYSICAL REVIEW article?
Well, I guess that's the — you know, in those days we used to send in a letter to the editor to get a patent on things, and then we wrote a full article for the PHYSICAL REVIEW, and this is probably the way.
Received January 36? It would have been the same material spoken about in this letter. You're saying one supply you got, no more.
0ne supply, that's all we got.
Getting back to Lauritsen again, as to him as an individual, how can you characterize what you learned from him? He was your advisor, not only co-worker but thesis advisor. Any particular thing relating to approach to physics, style, personality, anything else?
Well, I think he was always very skeptical of new results, until they were really nailed down. He was a very careful guy, in what he believed was true, out of an experiment. He'd always want to cross-check it every way he could. Now, in deciding what we would do, I guess we all had a hand in that. If I or Delsasso or Willie Fowler or any of the graduate students had good ideas, why, they were certainly welcomed by Charlie and developed, and we did them.
For example, Soltan was working in the same experiment I guess there just for a year, an international research fellow from France, I think.
Poland, Warsaw, University of Warsaw.
Poland. I don't know why I thought France, I guess because one of the papers was published in Comptes Rendus. He was from Warsaw. Was he from Wertenstein's Laboratory?
I don't know.
He came in for a year, then he just became part of the group. Was he on a postdoctoral basis?
I see. Then as the group expanded with Delsasso and Fowler and so forth there wasn't any particular change in the working style of the relationship?
The very clear division of labor that evolved, let's say when you were working with Delsasso, Fowler and Lauritsen, —?
Well, I guess we were all different. Delsasso was quite an expert on making things in the shop, how to make things, was a good machinist himself and he used to like to take on instrument problems. Willie Fowler was not so mechanically inclined. He liked to do a little more the abstract parts, theoretical parts, although he did an experimental thesis, I believe. I guess most of my contribution in the way of housekeeping anyway was designing and building equipment also. I, as you know, set up the porcelain X-ray tube. I made the ion sources for the tubes. I built platforms on top with the generators that supplied the power for the ion sources. I made the heavy water and I did wiring and plumbing and everything. We didn't have any union man coming in there to do our wiring and plumbing, things like that, in those days. I used to be the one, both in the high voltage lab — the high voltage lab has a ceiling that's 40 feet high, I guess more than that. The Kellogg Lab had one room in which there was the X-ray tube and the two transformers. That room was the full height of the building, I guess about five stories or more. I was always the one that had to crawl out onto the ceiling, not onto the ceiling but on the girders and things up in the tops of both of those rooms to hang up equipment and things like that... So I was a human fly as well as —
— not only going up but going down, lowering metal, into the pipe — Another aspect of division of labor at a different level is someone perhaps being responsible for the sources, someone responsible for the running, someone responsible for detection equipment. I know Fowler built the cloud chamber, first I guess you were working with him —
— Delsasso made the cloud chamber. He designed and made the cloud chamber. Charlie was always the guy who made the electroscopes. In fact, you know he invented the little pocket electroscope. The precursor of that was an electroscope that was made on a similar principle but it had a chamber about two inches by three inches or something like that, aluminum can with a microscope in front of it and a little fibre. Be he spent a great deal of time working out that type of electroscope, and when we first stated on nuclear physics, then his electroscope was one of our principle means of detecting, and was very well adapted to making gamma ray absorption measurements for example, because you just use his electroscope and start putting slabs of material in front and you have an absorption curve. And for — when we first started making beta ray activities, artificial radioactive materials like nitrogen-13 and so on, why, he made absorption measurements. He'd take those up into his office and get it set up there, then make absorption measurements of the positrons. Then he also made gamma ray absorption measurements of the annihilation radiation from the positrons, and established that that was 500,000 volt radiation. 0f course we were taking them across the street to Carl Anderson as well, and putting them in there to actually see the positrons, but Charlie was at the same time making absorption measurements of the annihilation radiation. So be built an electroscope just at the right place at the right time. He started that electroscope earlier, with the motivation of using it for X-ray measurements, which grew out of his work with X-ray tubes.
Some day someone should write a little essay on the role of the quartz fibre electroscope. The subsequent development of it and wide use — it's very important — apparently Tommy Lauritsen was manufacturing them, making them and selling them.
Well, when Charlie finally reduced it down to a pocket, to a fountain pen size, then it became very much in demand. He made it fountain pen size and also made the capacitants, the internal capacitants such that it would show a tolerable dose of radiation in about a day, and it had about the right time constant, so that if you carried it for a day, then you could naturally read the amount of stray radiation that you'd picked up. This was the reason for the demand. It was really for a personal monitoring of your exposure that these things were used. People carried them in their pockets like a fountain pen. Take it out at the end of the day, hold it up to the light, look and see how much radiation you'd had.
Not that they could do very much about it. Was there concern, discussion regarding the exposure to radiation during the mid-thirties period?
There wasn't very much. We knew we should stay out of it, that we should not get much exposure. But I remember, I shudder a little bit when I remember that in the days when Charlie was running his high voltage X-ray tube, trying to condition it and get it so it would stand the voltage and so on, and also into the nuclear period, these tubes were built in little igloos, cubicles, concrete cubicles were built on the floor of the high volts lab — the high voltage lab being like a big barn. This thing was filled with little concrete cubicles 10 by 10 feet or so, and the tube was above this cubicle, and the business end of the tube would stick down through the ceiling of it, of the little hut, to the target — business end down inside. Then out in front of these two cubicles — there were two of them, one that eventually I used for the porcelain X-ray tube, and the other one was Charlie's original X-ray experiments — about 15 feet or so out in front of these two cubicles we had some old wicker furniture. There were lots of room on the floor, we had some wicker furniture there, and I can remember while these tubes were running. 0f course, the business end of the tube was inside the concrete hut, but nevertheless there's an awful lot of radiation that gets made in the glass part up above by electrons and ions that just get lost out of the beam or hit these glass tubes, I know from actual measurements that the whole high voltage lab was full of radiation when these things were running. And after lunch, Charlie and 0ppenheimer or Charlie and Tolman would come in and sit in this wicker, this old beat up wicker furniture in front of the tubes and talk about it, talk about physics, while the tubes were running. But nevertheless, we did not stay inside these huts when the things were running, you know. 0ne of the huts, the one we did the first nuclear physics on, was one that had a dividing concrete wall in the middle of it, and the end of the tube was in one of these parts and the control was in the other part, so we just — through a wall. As I say, we didn't ever stay in the huts when the tubes were running, but people did come in and sit in that furniture right out in front of them and get sprayed with radiation from the tops of the tubes.
A question about how you selected your thesis problem, how you knew what you were going to work on, that you were going to define it as a thesis and submit it?
Well, I think it was a matter of timing. Just at the time when I had to settle on a problem and start doing actual work for my thesis, it just happened that at about that time we had found that this resonance absorption of protons by carbon was a very interesting thing because it did have a resonance, or appeared to, and needed investigation. It was a nice hot problem at that time and so that's why I did it. I think if I hadn't done it for a thesis the group would have done it anyway, because it was something that needed to be done.
Within the general matrix, context of the work, this appeared to be defined as a problem you could wrap up.
I don't think you could say at any time that you could wrap anything up. I think all you could say was that it looked like a very interesting thing to do research on.
How long did it take once you really started on it?
Well, it didn't take long to actually do the experiments. I remember that I made measurements of the cross-section by changing the voltage on the tubes up and down and getting the threshold of it and the cross-section curves, and I took these samples over to Carl Anderson and got pictures of the positrons, and between Charlie and myself we did absorption measurements on the radiation, and I don't think the data gathering took more than a few months.
Was it published before it was submitted as a thesis?
I suspect it was, because everything that we did at that period — things moved fast, and when we did anything, we usually fired off a letter to the editor, then eventually wrote a paper.
Do you recall when you submitted it for the thesis? How much time after the completion of the work did you actually submit it?
Well, I got my degree in '34.
June of '34?
Yes, I got my degree at the June graduation in '34. I'm sure I submitted it just before the deadline, whenever that was. As a matter of fact, I remember I submitted the thesis by the deadline and then I had to go back and paste the pictures in after I'd put it in ahead of deadline, so it was close. It was typed for me — by the office over in the Sealey Mudd, in the Kellogg Building. They typed it up for me.
Did you keep a copy of the thesis?
I don't think I have a copy of it now.
Was it just one publication that came out of it or several? Seems to me there was the possibility — in '34, there appeared —
— I don't seem to even identify them.
What was the title of the thesis as submitted, do you recall?
0h, I've forgotten the exact words, but it was a fairly general kind of title like "Artificial Disintegrations" or something like that. And it probably included bombardment of carbon with deuterons also, because we were doing that at the time.
Let me ask about the other thesis things. Was there a defense before the group?
Who were you defending against? Who was on your committee?
Well, the system at Cal Tech at that time was that everybody had to have a three hour doctoral oral, and it was not mainly on defense of the thesis, it was wide open, to see how much you'd learned from your courses and everything else, and the committee was usually I think fairly large. I know I had Epstein and I believe Smythe, and of course Lauritsen, I think Bowen, essentially all the people you'd taken your work from seemed to be on the committee. And they didn't all sit there for three hours. They would sort of drift in and out. There'd always be a few of them there. Then some would go, others would come in, but the candidate was there for three hours under questioning first from one, then another, as they came in and out. These things were fairly grueling. The students at that time and for a long time before had kept what they called a "bone book" going. This was a big bound notebook. It was the duty of every candidate after his exam to go and write down what questions various faculty members asked, so that the accumulated effect of this was what they called a bone book for candidates. But it was a harder exam than we give here. Partly because of this relay operation. You were there all the time, and the faculty members sort of came and went, and they were fresh.
Wasn't wearing them down. Was there any particular thing that tripped you up?
No — everything tripped me up. Sure. I thought I did terribly on the exam. I'm sure I did. I was nervous, like everybody. Everything I was asked, I felt I had gave a bad answer. But maybe that's characteristic.
The intention, I guess — to get you off your guard. While we're on that let me pursue one other point. When you knew you were coming up for your degree, you had some expectations of what you'd do next. What were the options open to you? What were your expectations?
Well, at the time I finished my degree, I felt that there were so many interesting things cooking in our own program there that I wanted to stay another year and continue to work on them. Charlie arranged a fellowship, postdoctoral fellowship of some kind. I remember I got $100 a month for 12 months and as you pointed out, that came from the medical program. Then by that time, toward the spring of that year I guess, no, it was summer time, I got an offer from Michigan. I know it was summer because I came here to look the place over (Michigan) and it was during the time of one of their summer symposia that I came.
You came either July 13 or 14, because your (visit is mentioned by Randall in) a letter to someone who was in Berkeley at the time.
I wouldn't remember the date, but I came.
Before we get to that point, you did get married in 1934. Was that after your degree?
No, that was — well, it was in December, 1934, so what would that make it? That would be before, half a year.
No, you said your degree was June of '34.
0h, yes, then it would be after.
Was your wife from the Pasadena area? How did you meet her?
Yes, she was from — well, actually her family lived in Los Angeles, and she spent a year or more of her life working at the Athenaeum which is the faculty club. That's where I met her. She interrupted her college work to come over and work for a year. That was Depression days and she needed money so she took a year off from school — or maybe it was somewhat more than a year — came over and worked at the faculty club, then went back to UCLA and got her degree.
In what field?
I think it was economics. It was just a bachelor's degree.
Getting back to the scientific work, this question of either deuterium or nitrogen reaction, led to another exchange with Lawrence. Apparently he didn't accept the results that you were getting, and was using the argument that he had experienced against his own results earlier, which was the possibility of deuterium contamination. The response as far as I know was that you then ran excitation curves. Charlie was very careful showing specific differences between protons and deuterons, and then Merle Tuve was involved, to check it, more precisely with his Van de Graaf setup in Washington, because he could get discrete energies, and as far as I know the story, he took the Lauritsen electroscope with him. I'm not quite sure, why, because it gives completely reliable comparisons using the same detection techniques? 0r perhaps that was the only one that would be appropriate. I would like you to fill in, tell that story again, what the issues were, how it developed, if you recall.
I'll think about that till I come back... (Pause)
Nitrogen? carbon? ... Fowler talked about it to me, and I think he's referring to the story here. Yes, "there was a lot of difference in excitation curves that convinced Lauritsen and Crane that protons did indeed produce nitrogen-13 in carbon bombardment." The radiative capture process, I think he referred to it as, was a matter of considerable controversy at the time. To make a long story short — he starts off by saying that Tuve borrowed the electroscope to check it out. This was June of '34, at the Physical Society Pacific Coast meeting in Berkeley. Were you there?
In March apparently Lauritsen and you had detected the 10-minute activity — we talked about running over to —
I wouldn't know just which stage of the experiment we did this running across the street to Carl Anderson. I don't know whether we — we probably took those things to Carl and got the pictures of the positrons when we first started getting the activities, and that would be before we started to explore the excitation curves and things. This was just the initial identification of positrons that he was helping us with. And that must have been in the first flush of getting activity.
Now, getting to the Tuve thing, do you recall that incident? He (Fowler) was saying, it was at that Berkeley meeting in '34, with the dispute coming up — he'd run it in Washington to see if —
Well, I suppose if the dispute was about the excitation curve and about the radiative capture, then I can see why Tuve would have thought he could help out, because his Van de Graaf machine had a much better mono- energetic beam than we did. See, our tube was run on raw AC.
That's the 60 cycle.
Yes, raw AC. So our beam had a definite maximum energy but it also had all kinds of stuff in it at lower energies. Tuve on the other hand, had the Van de Graaf, which gave a supposedly more energetic beam. I'm just kind of putting things together now and I assume the reason he thought he could answer this problem was because of his Van de Graaf beam which was much better than ours, cleaner in energy. Now, this is all just putting two and two together. I don't remember the exact circumstances.
Do you remember 0ppenheimer's reaction to that, whether there was any discussion about this whole concept of radiative capture as a mechanism for the production of gamma rays?
Well, 0ppenheimer was very interested in it and I'm sure he worked on it. See, I suppose that this was the first instance of radiative capture.
When Fermi talked about resonance and when it made such a great splash was in late '34, beginning of '35. And that's what I had known of before I'd known about this earlier work at Cal Tech. The Fermi work I guess was hung onto by people since, because it had a direct effect on Bohr's thinking on the compound nuclei model which developed out of that. But the other work I'd like to talk about for a bit, the work using the Compton electron — where the erroneous results were given because of the problem of converting the gamma rays produced in the target, and the energy losses, using this thin piece of lead. Now, the interpretation of what you were getting, the correct interpretation wasn't until later, but I'm not clear whether that continued even after you came here?
Well, we did some more of it after I came here (Michigan), when we got our high voltage ion tube going here, and we got similar erroneous results here. So yes, it did continue, and it was finally cleared up by Lauritsen, in which he gave up the method of using Compton recoils. Neither we here nor the group at Cal Tech ever got it resolved with Compton recoils. They just apparently gave screwy results, misleading results, and it was finally cleared up very nicely when Charlie and I guess Delsasso and Fowler did the whole thing over by measuring the energy of pairs instead of Compton electrons. Then that showed a nice single energy, and that was resolved, very nicely, but it was only as I remember it when they turned to doing the job by means of pair energies instead of Compton.
Had people, though, noted it in the literature? Had they complained about the results? Had they pointed out that there was a problem? Did you notice that you were getting into difficulty with it?
Well, I guess the reason was just internal disagreements in the data, disagreements between data taken on one occasion and data taken on another occasion, that taken in one laboratory with that taken in another laboratory. The whole thing just never did make sense. Every time you did it you got something different, with Comptons. And the pair just cleaned it up.
But you published the results.
Yes. Well, it showed, it seemed to show a lot of lines, a lot of energies, and who was there to say that lithium wasn't giving out those energies at that time?
What was the response to the news of the artificial radioactivity by Curie-Joliot? Was it something that was immediately apparent? First of all, how did you learn about it? Then what was the specific response? Do you recall that?
I don't know whether we learned if ,it by word of mouth before we got — I think it came out in Comptes Rendes didn't it, the first? Just a letter or something? We started immediately on it because we were all in position to do it. We had a beam and all we had to do was put some carbon in the — see, Curie-Joliot said that it was nitrogen-13. They had done enough experiments. So we knew what targets to put in and particles and stuff. We were all ready to do it. So immediately we did it, rechecked it. Charlie measured the absorption of the annihilation radiation with his little electroscope, and even Louis Ridenouer who was just a beginning graduate student at the time, went over to the chemistry department and got somebody to tell him how to set up a little chemical analysis system. He put these targets, I guess they were carbon targets, I don't remember clearly, and I guess burned them to get nitrogen dioxide or something like that — no — yes, it would be nitrogen dioxide, which had the nitrogen-13 in it. Then he put them through a chemical separation so that he also rechecked chemically the identification of the nitrogen.
You were really set up to do it.
We could have discovered artificial radioactivity earlier than Curie and Joliot, if we had just looked at some of our targets with Charlie's electroscope, after we'd bombarded them. It never occurred to us. There are a million stories like that, you know.
That particular story is true of many others who were capable at that moment of doing the same thing. What I'd like to do is ask a general question. It seems this dominated a great deal of what you were doing. You explained you had a particularly good setup for it and these were interesting questions. Was it clear that this was a well-defined program of research, that this group was specializing in this?
Well, I'll tell you one reason that we could do experiments with gamma rays probably better than any other thing was that we had this AC accelerator tube, working on raw AC, and so we couldn't do very much in the way of excitation curves and things, except in a very rough way. But we could activate targets, and then the gamma rays of course came out in discrete energies, so we could measure the gamma ray spectrum or attempt to measure it, even though it was produced by this very poor kind of a beam that we had. So the gamma rays were really, not because we like gamma rays better than anything else, but we couldn't do much in the way of excitation work. We never did put up a magnetic energy analyzer at the bottom of our tubes in order to select out a discrete energy from the beam. 0h, I guess we tried it a little bit, but we didn't adopt that as one of our experimental methods. I think we should have. I think we could have done it quite easily. Somehow we didn't.
Did you discuss the possibility of it?
0h yes, sure, we knew the possibility. As I say, I think we made a little feeble attempt at doing it, but we didn't — we just didn't go in that direction. See, there are two branches of experimentation. You can ... (off tape) ... as I was saying, you can really — at least at that time there were two lines of experimentation. You could do one on the excitation functions, cross-sections and so on for the production of radioactive isotopes, that is measuring beam energy against number of atoms produced and cross-sections for different primary reactions and so on. That has always been the thing that Van de Graaf machines have done best, because they have monoenergetic beams. That was the thing that we could do worst because of our particular beam. The other branch of experimentation is in the study of the radioactive or excited nuclei after they're produced. That was the branch that we had to go on, because of our equipment. Except for this one case, or maybe a couple of cases, the one case being the resonance capture of protons on carbon, the one that was part of my thesis, and then later on we found that the capture of protons by lithium-7 that produced beryllium-8 was a resonance thing also, and that was of course as you know, the gamma rays from lithium-8 and protons, the subject for a lot of our experimentation, and that was a resonance reaction. But there again, we didn't do much studying of the resonance reaction. We established that it was a resonance and it was about 400,000 volts, but there again our main interest was in the products.
You were essentially in the midst of this work when you left.
Well, the work was continuous. It never stopped. There wasn't any stopping point.
You said you wanted —
— I have to stop pretty quick now.
I just wanted to announce to ourselves, so that we can remind ourselves of what point we're at. What I want to get into next, next time, is the transition to Michigan, just the idea of how that came about. Let me tell you what I know about it very briefly. I know for one thing that Lauritsen talked with Uhlenbeck at a meeting in Minneapolis regarding you, and the letter from Randall which is undated but has to have been written some time between mid-May and July 12 because you were out here July 13. The letter was written and I'll make a copy for you if you don't have it in your file. It will remind you of those things before we talk next time. I want to talk about that transition, what else was in your mind, what your expectations were here, in terms of line of research that you wanted to pursue, how you saw the opportunity developing, what other options you might have had, and then we'll take it through this period, through the thirties up until the war period, for as much time as we have. I'd like to get into the postwar period as well. Fair enough?