Oral History Transcript — Dr. Margaret Law
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Margaret Law; December 13, 1976
ABSTRACT: Includes discussions on her decision to become an experimental physicist and her training in England up through the Ph.D.; her employment experience as a woman at Harvard and involvement in women in science movement; details of her work with the Bubble Chamber Group and the decline of high energy physics at Harvard after the explosion of the new hydrogen bubble chamber in 1965; start of her teaching and administrative duties at Harvard.
Sopka:This is Katherine Sopka speaking. I am visiting today, December 13th, 1976, with Dr. Margaret Law in her office in the Lyman Laboratory of Physics at Harvard University.
Dr. Law has kindly consented to speak with me today about her professional experiences at Harvard and elsewhere in a field where there are few women active. She is presently the only female member of the permanent physics faculty at Harvard. Dr. Law, perhaps we can best begin by asking you what attracted you to physics in the first place and at what age.
Well, I was educated in England, and I think the system there is somewhat different in that, at least in my time, one had to make a decision at the age of 16 on the subjects one was going to specialize in. At the age of 16 most people left school. Those that were staying on preparing for university entrance would specialize in three subjects. So I made a decision at the age of 16 that I wanted to be a physicist which is a terrible age to have to make it, looking back, although at the time it didn't seem to be a problem. Why was I interested in physics? Well, I was good in science, I was good in math, I think I knew I wanted to do some kind of science, and then those days, of course one only knew of chemistry, biology and physics. You didn't know of biophysics, geophysics, biochemistry sort of things, one didn't even know those existed, and so it was a choice between those three. And biology was ruled out because I couldn't possibly cut up things — hopeless — and so it was physics and chemistry. And looking back at it now, and this obviously wasn't apparent to me then, I really made the choice of physics for three different reasons about equally weighted. One, I really did feel that physics explained a lot of things that I didn't understand in those days — everyday things like radio and telephone and light and sound and all these things which I was interested in. And that then I thought was my only reason. To be honest now, and I always say this when I talk in workshops, two very more important reasons were the fact that the physics teacher at school was someone I admired very much and we didn't have a very good chemistry teacher, and another one, which is another important fact, that my boyfriend at the time was doing physics. I think if he'd been doing chemistry I would have ended up as a chemist. So there are all these extraneous things which affect your decisions in this way that make a lot of difference later in life. Anyway, at the age of 16 I decided I was going to be a physicist, which meant I specialized in physics, chemistry and mathematics. And again, in England you don't apply just to a college or university. You apply to the department. So I had to apply for admission to a physics department. I applied to several different universities. I ended up going to Birmingham, which was the university in my own hometown, much against the advice of all my teachers in school who said I should get away from home. And I admit they were right, but nevertheless it was one I knew, and also again my boyfriend was going there. So I ended up going to Birmingham.
The undergraduate degree there is three years. I took three years as an undergraduate and ended up with the first class honors degree, which I guess, is the equivalent to — what is the highest honors here?
Sopka:Summa cum laude.
Law:Summa. I should know that, after the lunch meeting. At that point again the graduate school situation is somewhat different. Not so many people — I'm talking now 25 years. I got my undergraduate degree in '55, so things may have changed in England. Not so many people stayed on into graduate school. We had a class in physics. My class was about 36 people, and I think about seven or eight of us stayed and went on to graduate school.
Sopka:How many were girls?
Law:We started off with four. One dropped out, was actually sent down to an ordinary degree. So we ended up with three people, three girls. Of those, I was the only one who did undergraduate work, who got first class honors. Usually you need a first class or a very good second class to be able to get into graduate school. And again you tended in England to stay at your own university — which meant that you ended up doing research in the fields that were there, unless you had a very strong inclination to do some other subject. Birmingham was very strong in high-energy physics, at least in those days. It was called nuclear physics in England. When I was an undergraduate, they had just built and completed the 1 Bev proton synchrotron which Oliphant built, which was actually the first synchrotron designed. In actual fact the cosmotron at Brookhaven beat it to it in operation, but it was the first one designed. So in England it was a very strong department in those days for what was then called high-energy physics; now it's low-energy physics. Now the department did some other things, lower energy nuclear physics, there was a cyclotron there, and nuclear structure sort of things, but it was almost inevitable really if I stayed on for a Ph.D. at Birmingham I'd end up in that field. I know, and I remember when I graduated I was interested, still had a sort of inclination towards radio astronomy, but that meant applying to Manchester and Jodrell Bank and you know just the inertia was too great. So — I didn't really make a choice for high-energy physics. It was made for me in that the department was doing that.
Sopka:You were definitely committed to experimental physics —
Law:Oh, very much so, yes, very much so, because I had taken an experimental degree. There was a strong math (people here you call theoretical physics), we call it math physics program, and you could take a joint math physics program but I wasn't in that so having got a degree in ordinary physics that sort of inevitable that I would do experimental work. It's interesting. I don't know whether you are interested in sort of experience I've had that was special to me being a woman in this interview or whether you want to just stick to my history, because it was interesting that was the first time I came up against any kind of discrimination. Are you interested?
Sopka:I think you should include it.
Law:Because up until that point it hadn't struck me that I was different from anyone doing physics. I had been to an all-girl school of course, for High School, and the people at school were surprised I wanted to do physics, but I just took it for granted.
But it was very amusing in retrospect, not at the time. Again, you don't so much apply to graduate school, you're invited by the department to apply, and in the end of my final year as an undergraduate when we were doing labs one day I suddenly noticed that a lot of the men were disappearing to the prof's office in the afternoon and he was calling them one after another, and I asked them what's happening. “He was asking me if I wanted to stay on to do research" is what he told me. And so I waited, because I wanted to do that, and I knew I was up at the top part of the class, and no invitation came to me, so looking back I don't know how I had the courage that I just went and knocked on his door and said, "I want to stay too. I want to do research.”
Sopka:Good for you.
Law:And he looked at me — Yes, but at the time it was so funny. I didn't have any feeling of militant feeling. I was just sort of gee, you know, I want to do this, and so I did it.
Otherwise I'm sure if I hadn't, it just would never have come.
Sopka:Were you accepted then once —?
Law:Oh yes. I mean he sort of looked a little bit taken aback.
Once I took the initiative he had to include me. I expect they thought maybe I wouldn't get a good enough degree or something, but I did. So anyway, that was really my first brush with being different. I hadn't realized it until then. Graduate school, which wasn't called — it was called research students then. That was typically just three years, with no course work. I think mainly because we had got a much better grounding up to the B.S. degree in courses, although I think, to be honest, Ph.Ds. here end up ahead of the English Ph.Ds.. But anyway, it was just three years. And I was working on the synchrotron, which was then working, and my thesis was on total cross-sections PPNP. I helped in the group I suppose. My thesis was just PP, which had that energy which was just the low one, the one Bev and I built and operated the first liquid hydrogen target in the department, which is part of it is back in the days which were very amusing of having to — we didn't have our own liquefier to start the equipment had to drive 30 miles to Norman to get liquid hydrogen and drive back with the liquid hydrogen in the back.
Sopka:Excuse me. Did you have to master shop techniques?
Oh yes. The first — I think that was in fact much better there than it is here. The first two weeks of research student, graduate student, we had to take a 2-week shop course which was really fun and with two students at a time. The head of the shop, the machine shop, was a very good teacher, and he had a set program. You made a nut and bolt out of three-quarter thick bolt which you had to cut the thread and you had to cut the nut and you had to mill the sides of the nut. You had to learn to braise and to weld and do these kinds of things. And we actually had to do a lot of our shop work ourselves. Now I say I built a hydrogen target [?], a lot of — the main point of that was not — I didn't do it, the machinists did it, but little things, fixing it, making [???] with counters and things. I would go in and use the lab myself, and it was something I was very much enjoying, something I miss now, because if I walk into the shop here to try and do something, everybody rushes and says, "Well, let me do that for you" sort of thing. And so it's something I miss. I enjoyed that very much. And we had to build a lot of our electronics ourselves. That sort of counting electronics wasn't just shelf item in those days and so that we had to build. So it was very practical. Most of the time it was practical techniques and not very much physics when you get down to it, but it was useful. At the end of those three years I had to make a decision what to do next. So here again I think it came a second time and probably the fact that I was a woman and the expectations of me were somewhat different in that it was clear that the prof in the department really just expected me to go and teach in a good girl's high school. I got married one year before my Ph.D., which was also very unusual. Most people waited until they'd gotten a Ph.D. and then got married. We got married just one year before.
Sopka:Was your husband also a physics student?
Law:He was a physicist who was two years ahead of me in the same department. He didn't take a Ph.D. He doesn't have a
Ph.D., so he actually was working at a lab in Maulden [?], actually about 35 miles from Birmingham, and part of the reason we ended up getting married was because he was traveling backwards and forwards every weekend and I was wasting every weekend. It was much easier; I could work much better once we were married and I didn't have to bother going out every weekend. So it was unusual. Anyway, it is clear the expectations were that I would just teach at some good girl's high school. This Law, was now in 1958, and there was the traditional route then and for many years afterwards was the so-called "brain drain," that people would come over here for a post-doc for two years at the States or to Canada, and often they would stay, and this was called the "brain drain" from England, and that whole period is from the '60s. It's only recently it's stopped in fact. As everybody else was taking post-docs over here, that's what I wanted to do, and I applied. It was a bad year, it was 1958, and there was some sort of minor recession here, there weren't many jobs in the States, and I couldn't get a job in the States. And it was my husband had to get a job, we needed two in the same place, and I ended up getting a National Research Council Fellowship post-doc fellowship in Canada at McMaster University, and not in high-energy physics, in nuclear physics and nuclear structure. And that worked out well because my husband got a job at Preston House in Hamilton, they're both in Hamilton. So in '58 we came over to this side of the Atlantic for two years only, [laughs], as everybody else said, and for two years I was at McMaster and it was very interesting, because although it was nuclear physics, very close, it was a different experimental field. It was beta and gamma ray spectroscopy, looking at energy levels and nuclei [???] with the spectrometers that they had. And it was really learning a new field, and I enjoyed it for the two years. I don't think I wanted to stay in that field, because it was getting pretty worked out even then. So we were there for two years. Each were enjoyable years. Obviously there was no future for me at McMaster, and I didn't really want to stay in that field, so we decided to look around for another job. At this point going to Hamilton, really on my initiative, my husband managed to get a job there too. I felt it was only fair to let him get the job this time, and we looked around various places, he ended up getting an offer of a job at the Cambridge Electronic Accelerator, which was a joint Harvard-MIT project which was just being built at that time, as an electronic engineer. And that seemed reasonable, because it was the Boston area where there was lots of opportunity. So we came down here in January of '61, and at that point I hadn't done anything about looking for a job myself, and deliberately so. Because you know, back in '61 life was very easy, and I wrote letters around to various colleges and then had about five different interviews and five different opportunities. I had I think, I forget exactly, but about five different offers to choose from. It might be interesting to note that I never actually applied to Harvard for a job. I didn't have the courage. I didn't apply to MIT either. I didn't have the courage to apply to either Harvard or MIT. I actually wrote to Radcliffe, because I didn't realize the Radcliffe-Harvard relationship. I remember looking in the books of universities and J. C. Street was listed the head of the department at Radcliffe. Of course he was really the physics chairman in the physics department here at that time. And so I wrote to Radcliffe for a job and got a letter back from Curry Street saying well he didn't think there really was anything but maybe I should come in to talk to them. So I never applied to Harvard actually. And the job here was working with the bubble chamber group, and on first sight it seemed not a very good job. It was really not even a faculty appointment at that time. They, the bubble chamber group, had a large of group of scanning girls and the girl who was head of the group, who ran the scanners, (and this was an employee type job), was leaving and they wanted someone to replace her. So the offer, I remember the salary was five thousand a year. The offer was to be in charge of running the scanning group and they would let me do some physics along with it. The other offers I had around the Boston area didn't involve high-energy physics and this did. My husband thought I was absolutely stupid because I had offers of lectureships or assistant professors other places and I took this instead, because it wasn't even a real faculty appointment. But I don't regret it really. Very soon after I'd been here a few months one of the research fellows left and so I got a half-time research fellow appointment — half-time meaning [???] I'm sure you're used to half-time [???][???] work. And it came into a normal research appointment, research fellow appointment. It definitely wasn't on the teaching ladder, and at that time I think there have been a lot of changes. One's aspirations were not high. I mean, I didn't aspire to be on the teaching level at Harvard as a woman. I remember Curry Street telling me once that well if I was interested in teaching I could help teach a course, but of course I couldn't possibly be an assistant professor.
Sopka:I see. That's interesting.
Law:I don't know, I'm now talking '61, '62, '63. In those days, one kind of accepted this as a woman. I'm sure you know the feeling. And one didn't aspire for anything more. And now I think one of the big improvements happened in the last five years that women are aspiring to higher jobs; though I was here just as a research fellow running the scanning group for the bubble chamber, being very active in the research too. This position kind of grew and became more than administrative, in that it became a film analysis group for many different experiments which I was in charge of. When we talk about the history of the high energy movement I'll go into that in more detail. And I guess at some point there was, or still is maybe, an 8-year limit on a non-tenure appointment at Harvard. You can only be a research fellow or even an assistant professor for eight years. There's a limit. And as that time approached, about '68 — well, I came in '61, it must around '67-‘68 the department actually put me up for a senior research associate, as which there were very, still very few such people, even fewer then — It's a position where you are supposed to spend half your time doing some administrative duty that is useful to the department or the research group and half the time doing research. I was very pleased with that, because my half time was running the film analysis group and the department approved this and it was put forward. There were no women senior research associates in that day.
Sopka:Did that include tenure then?
Law:Its tenure is not academic tenure; it's tenure as long as the contract exists. You're still paid by your research contract. It's not an "on ladder" appointment. It's not a "term" appointment. It's called a permanent position, but the university really has no obligation to keep you on as a contractor.
Sopka:Oh, I see.
Law:But anyway, that got turned down by President Pusey and the committee that looks into this thing. And so this was a great shock at the time. The department was surprised I think. I am saying this because I think just to emphasize the change in Harvard's attitude. I was very surprised the chairman of the department at that point really didn't — I don't think he really knew the reason. One of the reasons he gave me, my husband had such a position at CEA, was that he thought maybe Pusey and the committee felt that we didn't need two such permanent positions in the same family, quote, you know, and which annoyed me a little bit in those days. I heard afterwards through a fairly reliable source that Pusey — let's say he was not very liberal from the point of view of women at Harvard, to put it politely. I heard later that there were a lot of other women in my situation who had been around as research fellows or research associates for a considerable length of time, and he felt that if they gave one woman the senior research associate position it would be opening the door for the rest of flooding. Anyway, it got turned down. And I should have left at that point, but I didn't, because I was very interested in what we were doing and it was a very convenient job. And my responsibility was still enlarged somewhat after that time. In around 1970 I took over running the computer that the high-energy group operates, the 707 computer, and then I forget even the dates exactly, around '71 Dick Wilson, who was the chairman of the high-energy committee, asked if I would like to help him out with some of the paperwork. And this has slowly developed into what I'm doing now, which is really being in charge of the administration for the high-energy physics contract and running the high-energy lab and very much, well most of my time really was spent on administration at that point. And somewhere in there without any prodding from me, I was very pleased — after Pusey had left and Bok had become president. There was a change in climate, and the department without my prodding put me up again for senior research associate and this time it went through, so now my official title is Senior Research Associate in Physics.
Sopka:Aren't you also designated a lecturer —?
Yes. I was going to just talk about the teaching side. I was sort of following through the track of the researcher, so that's where that ends at this point, where really the research science is losing out. I've been in the [???], you know, which
I'll talk about later, the bubble chamber group closed down all that end of '72 and my research [???] field that is becoming, that's the thing that actually is losing out. I really don't spend much time on research now, and the administration side has got to take up more than five percent of my time. When I was first here I did a little teaching in Master I term teaching. When I first came here the first ten years or so, I wasn't really interested in teaching at all; I was interested in research. Starting around '70 I became more interested in the whole problems of women scientists then. I hate using the term "consciousness raising," because I think it's a horrible phrase, and I can't think of anything else. And with the whole Woman's Movement, I guess my consciousness got raised around '70, '71. I hate that term. And I became very involved and very concerned of women in science, essentially. And I spent one summer editing a report that a group of local women scientists brought out about the status of women in science and what one could do to improve it and the whole thing that kept corning over and over again was role models, role models, we need more role models in schools and universities. And at this point I look at myself, should I keep writing this, I'm not a very good role model. Here I am in the department, I see the graduate students, and I’m very involved with teaching the graduate students informally. I have more contact with them actually than their supervisor. But I don't have any contact with the undergraduates. So without really wanting to teach as such I went to Paul Martin who was then Chairman and said "could I help teach one of the undergraduate courses, Physics I, which is one of the big introductory courses, just as a teaching fellow.” I think my reason for doing that was I felt that I wanted to make myself more obvious as a role model. And much to my surprise I thoroughly enjoyed teaching science. So the role model part has gone down, the teaching side has come up. That was five years ago. And for four years I was just more or less like a voluntary teaching fellow. I'd always got the title Lecturer but it was very much an off and on thing. If they needed an extra person they would get me. And then this year I guess they needed someone to teach, to be very responsible for the course, and I got asked if I would do it. So this year for the first time really it's my course. I feel responsible for it. How this will go I really don't know, because the Lecturer title is a one year title. As I'm going on teaching it just seems to be accepted that I'm going to teach now. The first two or three years it didn't matter really if we had money in the budget; we'll let you teach. Now I get asked what course would I like to teach next year? But I thoroughly enjoy the teaching side of it, especially this year being in charge of the course. I am supposed to be half time teaching, and I certainly find it takes the half-time, and my senior research associate is supposed to be half time research, half time administration, so what goes is the research. I'm really do very little of it. I'm involved in an experiment out at NAL in the Fermi Lab, proton accelerator, which is outside Chicago, where we had one run last June and we're supposed to have one this December, but it's slipping past January. The interval between runs is a lot of time. It's a big collaboration, and you really can't feel you're a vital part of it unless you're out there in Chicago a lot of the time. For personal reasons I don't really want to be away that much; anyway, for work reasons, it just would be incompatible to my responsibilities to the contract and running the lab. You can't run a lab if you're out in Chicago a month at a time because you find all sorts of things have gone wrong. So that way the research side has gone down. One of the big problems, too, you asked me about, the rewards and the dilemmas associated with a career in high energy physics. It has been very rewarding up to now. The dilemmas for me and for everyone in high energy physics right now, I think, are very large when you're associated with a university because of the cutback on research money and the way the accelerators are funded — now there are only about three major accelerators in the US. We used to have our own accelerator here that was an electronic accelerator; then life wasn't too difficult. You could run your experiment, you could be on a shift from 4 to midnight, and you could do a normal day's work to make sure things were operating during the day. But now you just have to be away from home a lot of the time, and I don't know quite where it's going to go. It's getting less viable to do high energy research from a university base. We spend so much money on travel. We spent $100,000 from the contract on travel one year. From personal lives point of view, it's just completely disruptive. People are flying out two days a week, they fly back to teach a course. It's getting very difficult. It's a very exciting field, particularly the last two years. It was sort of dull there for a period. Now it's become very exciting. The experiments are so large; the groups doing them are so large, you have to be away from home a lot. It's really, right now, difficult to do. I find it very difficult. I find that's the reason I'm kind of really dropping out from the research part. You say suggestions and hopes for the future. For me or for people in general? I'm not quite sure what you mean.
Sopka:For a life in science — for you or for those who will come after; the women particularly.
Law:Well, I think it's not easy in physics in general. It's not easy. But it's probably no harder for a woman to be a physicist than just to be a professional in many other fields. It may have been a little bit more difficult because she has lab work, which perhaps runs through odd hours. It's not quite like if you were to work in the library from 9 to 5 and then have things organized. So I think science in general, and maybe physics in particular, it might be a little bit more difficult. But it's certainly possible. There are a lot of women physicists, and very successful ones. And I think it's rewarding. It's worth the effort. Of course the number of women physicists is still very small percentage-wise. For bachelors it's actually about 6 or 7%. It's gone up recently from 6 to 7% now in '75. The PhDs are round 3% women now. It's been level at around 2 or 3% for the last 20 years. Actually, the 1920s were much better. Women were nearly 20% of the PhDs in the '19s to '20s sort of period were women. So it was very much a high percentage women. Then we just dropped down. That's a very small percentage. It's a significant number of women, though, when compared to the total. But there are about 6 or 7 hundred women PhDs in the country, and 2 or 3 thousand bachelors. We tend to lose track of the bachelors. It's hard to keep track of them. I would like, and, of course, a lot of us would like to see a much higher percentage of women, but I think it's going to come very, very slowly. If you think of that 3% of all practicing physicists, no. 3% per year PhDs are women. If you think of [???], a flow into all the practicing physicists, even if that 3% went up to 100%, which is obviously impractical, it still would take 20, 30 years before the total number in the country would get up into like 20% women. So I think that as far as one can see, in my lifetime at least, women are still going to be a very small minority in physics. I hope it will become a more accepted field. I do see signs that women in high school are more interested in the physical sciences. Unfortunately I think this whole sort of awareness of science as a field for women has unfortunately come along with a down time in the job market.
This should have happened 10 years earlier in the 60s. But now there are so few jobs it's very difficult to encourage women to be a physicist, especially to do a Ph.D. in physics, when they might now be able to get the job they want or really want at the end of that period. I hope that will change, of course. But I don't see a very large change in the very near future. I think women are still going to be the minority. I think it's still true that even with Affirmative Action and this kind of thing that a women still has to be a little bit better than a man to get the same job, for physics anyway. There are some outstanding women physicists. But, after all, we're most concerned usually with the sort of middle ones, the majority of people. And I just noticed this within our own group, anyway, I don't hear people talking about any woman as prospective assistant professors, and this kind of thing. It's not something that they think about, even though they're supposed to in Affirmative Action. I think it's still real difficult. You still have to be more outstanding as a woman. Is there anything else you would like me to say about that particular subject or me in general, or will I go on to the high energy group and that part of it?
Sopka:Well, I think going on to the high energy group would be appropriate.
Law:Well, I've been trying to think of the history of it. It really again boils down to really the history of my involvement here, more the history of the bubble chamber group. I should explain, though, that first the high energy group is a group that is funded all in the same contract, it used to be AEC contract, with a group of four or five full professors as principal investigators under the same contract. And the contract has run for nearly 20 years. I must admit, I don't quite know the start.
I was trying to think of what that was. I came in '61, the contract existed then. I think it must have started by 1960, plus or minus a year.
Sopka:We can get those records out of the files.
Law:Yes, and also some of the other people, like Pipkin,
Street. Again, when I first came I came to the bubble chamber group, which was a sub-group funded by the same contract, but we were very separate from the rest in that we lived up here in Lyman on the fourth floor. Dick Wilson had a group, and Frank
Pipkin, at least I think they were starting groups. They weren't doing any kind of experiment when I came in 1961. They always were centered more on the cyclotron, the old cyclotron in that building that is across the way near CEA. I suspect the contract started because of CEA, the electronic accelerator that was being built then. I don't know this, but you can find out. I suspect they got together saying we want to do high energy physics research on the accelerator, and that's how it got funded. When I came I believe the Bubble Chamber group was the only group actually doing any high energy physics research. The others had been working on the cyclotron. And we were very separate, and I didn't have anything to do with the budget and administration at that time, even within our own group. Which was, incidentally, under Professor Street and Professor Strauch at that time; they were sort of joint leaders of the Bubble Chamber group.
Sopka:How many members were in the group all told?
Well, there was Street and Strauch, Alan Brander [?] was an instructor. I think we were the only junior faculty member when I came in '61; one other had left recently. There were three graduate students. I came into this sort of funny intermediate position. And really I wasn't even aware of the rest of it. It wasn't called a high energy group in those days. It was a contract. Money was available, so everybody got as much money as they wanted. And it really wasn't a group as such. The cyclotron lab was a very viable thing in the '60s, and the machine shop and the electronics shop were all funded by the cyclotron contract. And the high energy people would use the cyclotron machine shop and pay for time. In fact, the high energy group as such didn't really evolve until the cyclotron contract got terminated in '67, and then we picked up all these people that were machine shop and electronics on a contract. So you could say it was started from that date. The contract and the group of full professors that ran it had existed from the beginning. Let me talk a bit about bubble chamber group, because I was very much involved in that. When I first came in '61 the group had been — well, we did for many years, collaborating with the similar group down at MIT, and then there was a subgroup that Brown [???] — somebody would graduate and move someplace else [???] They were looking at films from the heavy liquid chamber which had been built at MIT [???] chamber, which had operated [???] cosmotron at Brookhaven, making a beam of about 1.15 GEV pions, negative pions. So looking at pi minus P. And the reason for the experiment was to investigate the branching ratio of charge to neutral decays of the lambda zero, or K zero. K zero was then still called theta zero. There had been some discrepancies in this branching ratio. It was an East-West discrepancy. People on the East coast got one answer, and on the West coast —And this experiment was started and the chamber was built to investigate that. It was a heavy liquid chamber, it was propane mixed with methyl iodide. We used to call it soup. It smelled vile. And the reason this was to give a very short radiation length for gamma rays, so we would see the gamma rays from the neutral decay. It's when the pi zero decayed to two gammas, and we would see the electro positron phase of the gamma rays. So we were looking for the neutral decay directly, looking for the gammas pointing back to the origin where ideally you would see pi minus stopping it. The reaction was pi minus P, which goes to lambda zero plus K zero. Ideally you might see four or maybe fewer usually, because we didn't get all the gammas pointing back to the source. That was the experiment they were doing. They were taking the film and looking at it. Of course, every picture had to be scanned by [???] and then [???] had check events, and then they had to get measured on measuring machines and analyzed. And it was supposed to be a high statistics experiment, which is not a good thing to do in a bubble chamber. And I guess that occupied about two years. It turned out that film was very much more useful for other things, and in fact the thing that was done for it I think was the least exciting. We did get a good measurement of that particular branching ratio, but it wasn't particularly exciting by the time it was done. We also looked at charge exchange pi minus p going to a neutron plus pi zero. So a graduate student was looking at that as a sort of side line when I first came. And that became very useful in that around '62 or '63 the eta zero was discovered. This was in the period when suddenly people started finding a whole lot of new mesons the age of the [???] and new resonances [?]. And the eta was discovered and it wasn’t clear of what its spin was, it wasn't clear of how it decayed; it obviously decayed into neutral modes. And we were able to prove that it was spin zero because it decayed into two gamma rays. It was a very characteristic opening angle of distribution between the gamma rays if it decays to two gammas or if it goes to a gamma plus pi zero. So we were able to use that film to do something that it had never been intended for. Also, this led us into a whole set of experiments with visual spot chambers down in Brookhaven, looking at charge exchange. And this series of experiments were part of our occupation right through to about '67 or '68, I was first on the cosmotron in the AGS [?], and looking at charge exchange scattering of a range of I think about, I forget the highest one now. And I think those measurements are still perhaps the most definitive measurements that have been used. They're extremely useful looking at high P phase shifts, and I think probably they're still about the best ones. So it led us up to this. And then of course the group kind of enlarged and sort of half the group was doing the spot chamber thing. When I came, as I said, the Cambridge Electronic Accelerator was still being built and there were plans that the bubble chamber group would build a large liquid hydrogen chamber to operate with the accelerator. And I guess this was in the design stages even when I came in 1961 and I wasn't very aware of it. And this was being built through '62, '63, and ‘64. I forget exactly when the accelerator first ran. It must have been around — (this is something you can find out for the records) it must have been end of '62, beginning of '63. I'm not quite sure. Anyway, the chamber was being built mainly at MIT. Traditionally the MIT part of the group always built the chambers, were the sort of mechanical engineers of the group. And the Harvard half of the group was always the software specialists, the programming specialists, because the analysis programs were very complicated. And it's very interesting for myself looking back how computing and programming has changed in the time that I've been here, because when I first carne in '61 we had a very crude — well, just before I carne we had to do all the analysis by hand, the kinematics. The momentum was measured getting them into angles, and you would have to go back and check on momentum energy. And we did it by hand on the [???] graphs that used to exist, and still did exist up in the attic until about a year ago, where you would get a point and see how you fit on the graph. And just before I came we got a computer program that would do this for you. And the computer we used, I think it was still a 709, I believe 709, which the observatory at the Smithsonian had. It wasn't a Harvard computer. And the whole of Harvard University had two hours a night on that computer, and the bubble chamber group used to use almost all of that two hours. We were the only people in the whole university in computing. And we used to have to carry these cards over to someone, on Prescott Street who collected them. Up until that point I think they used a computer at New York where we had to set things up every week. Just about when I carne we'd started using this. But the whole of Harvard had two hours of computing and the bubble chamber group used to' use them all.
Sopka:Did you have some computer training at some point in your career, or have you just picked it up?
I've picked it up. I actually haven't really picked it up very much. I really haven't done much programming myself. I've suggested other people do it! So I'm an expert that isn't really an expert. But that has changed so much when Harvard got its own Computing Center. Now we have our own computer just for the contract. It was clear when CEA got going that the big bubble chamber we were building wasn't going to be ready in time to run the new machine first ramp. And so we got an old bubble chamber that had been I think by Shat [?] at Brookhaven, hydrogen bubble chamber, 12 inch diameter, and we brought that up from Brookhaven when it wasn't being used anymore because we [???], and we decided to put this in a photon beam from CEA just to see what would happen. No one had really used bubble chambers for photon work before. It wasn't clear it would very viable; because the problem is you get a lot of background with the photons converting in whatever window the beam has to pass through. So you get a mass of electron-positron pairs from the beam window, and if you are not careful they mask the events. And, of course, the cross sections of photons were probably an order of magnitude lower than were charged particles. So you don't get many events in the first place. So the plan was to just while we were waiting for the big chamber to get going to run this little chamber in the beam to just see if you could do an experiment. And it turned out to be really very successful; I think one of the best experiments that was ever done in CEA. We took about a million and a half pictures in the photon beam; various energies, from about 4 G all the way up to 6, which was the maximum energy from the accelerator. It was possible to do good physics even with the 12 inch diameter chamber you could get enough of a [???] measurement to get accurate determinations of events. We looked mostly at three constrained events, gamma plus Po, Po plus pi, plus or minus where you saw the [???] charge tracks. So we got some information from events where there was also a missing pi zero. And it was very much an exploratory experiment because no one knew, up until CEA was operational, the highest energy photon beam would be about one and a half G, [???] so no one really knew what happened in general after 1.5 GEV, and the bubble chamber experiment was about the only one; at least it was in those days. Overall people were doing specific experiments on electron scattering and things. But this was the first time anyone had looked at what happens — what is the interaction gamma plus B at high ranges up to 6 GEV; so it was really fun. I think it was one of the most exciting experiments
I've been involved in. And that was very good. We got one and a half million pictures in this little chamber, which there was an event on about every l00th picture. So they all had to be scanned, not just by the Harvard group, by MIT and Brown, and also by this time there was a [???] group [???] in the whole [???], and by this time we calling ourselves at the "Cambridge Bubble Chamber Group" because there were so many names you couldn't put all the names on the paper. This was really very exciting. We were able to find out that [???] production was diffraction production, and there was a lot of antisterile production. This still was supposedly preliminary to doing many bigger and better experiments with the large bubble chamber, which was a 400 liter chamber. I forget the dimensions; about 3 feet diameter as opposed to one foot. It wasn't a cylinder shape, but it was [???] The big bubble chamber which was being built, this 400 liter one, which actually then was the largest volume hydrogen bubble chamber that was going to be in existence, was tested, and unfortunately it exploded on its first test; a disastrous explosion. Has anyone else talked about that? I'd hate to repeat.
Law:Ok. To me and to the bubble chamber group it was a very big event. I mean, it still is. I think it affected CEA, it affected the bubble chamber group in that it exploded on its first test when it was first filled with hydrogen at quarter to four, July 5, I think it was '65. It was a horrible occasion. It destroyed the whole of the experimental core at CEA. The whole thing was on fire, the roof fell in. It was very lucky it happened at 4 o'clock in the morning; there were only seven people there on the floor. It could have happened in the middle of a working day; there could have been 30-odd people. One person was killed and one other very badly burned. It was just a horrible time. I wasn't there. One of the men from our group was there actually in charge at the time.
Sopka:Was the cause of this explosion established?
I suppose you could say it's a good point of a physicist not acting like a mechanical engineer. The beam window, because for a photon beam as I said, you have trouble with a lot of background in the beam, so you try to make the beam window as low Z material if you can, and it was made of beryllium. And it was designed primarily by the MIT people. Everyone was part of it. And they designed it as well as I thought from a structural point of view. What they didn't know, didn't realize until it became apparent afterwards in the months of investigation — this was slowly pinned back together what had happened — was that apparently when beryllium is worked, it develops little sort of surface cracks, which very much reduces its tensile strength. So what was calculated as being a perfectly strong over-designed window, because it had been formed in some way then wasn't, as soon as the liquid hydrogen presumably got up the level of the window there was differential contraction. The thing just broke. It was a kind of thing which after the fact people who were used to working with beryllium said "oh, of course, didn't you know about that?" It was also very stupid in that unfortunately this was a test— this was the inner window. The outer window of the vacuum thing I think just had a piece of board capped on it. I mean, after all, if this wasn't a beam it wouldn't have mattered.
We could have had a half inch steel plate on there in retrospect.
It wasn't. It was just a piece of board which shattered and the hydrogen just poured out and exploded. It would have poured out into the inner — well no, see, even the inner window the beryllium could have been covered up by something else. You don't have to mention all these things. But this was a big event in more ways than one, because I think for the bubble chamber group the decision was made after that time not to do any more bubble chamber physics at the electronic accelerator. It would have meant building a separate building. I mean, this was on the floor — we were very careless, in retrospect. It wasn't a separate building or anything like that as they are at Brookhaven or places like that. It wasn't feasible to build a separate building, so the decision was made not to rebuild it, not to go ahead with bubble chamber physics at the Cambridge Electronic Accelerator. I think it wasn't the whole accelerator. I think it was a very bad time because they were down for about a year with the building being rebuilt. And I think might have been a deciding factor. They lost out a year. It was just the period when the Hamburg accelerator at the same energy came into operation. The whole momentum of the place was lost, and I think it was just very bad. So after that the Cambridge bubble chamber group kind of somewhat — well, it didn't disintegrate because we'd lost our sort of main reason for staying together. And Harvard went ahead and proposed experiments at Brookhaven on the 8 inch chamber and looked at the pi minus P at high energies, 20 GEV. And later we looked at some low energy K minus P in the 30 inch chamber. But I think that was kind of like the peak of the bubble chamber group, and [???] in the peak of the Cambridge Electronic Accelerator, too, so the thing started going downhill. As regards to the high energy group, throughout this period up to the explosion Wilson and Pipkin had been running experiments at the CEA. Again, it wasn't a group as such. We were just getting our money from the same contract and using the cyclotron staff. They continued after that. But then in '67 the cyclotron closed. And this is also about the time when I started becoming a bit more aware of what was happening. Up to that time I'd just been a member of the bubble chamber group. We took on the machine shop and electronics shop, and it started to become more coherent; also money started to become tighter. So it started to matter more who had what money and there was a lot more discussion on that. Let me see. We got a computer. We got [???] computer in '68, which in those days was still is — a large size computer. It's a 32 bit machine. It's equivalent to something like a PDP 10. Of course, I would say now I'd go to the medium size computer. But it has handled all that batch processing; computing of course, from the day as to night. With money getting tighter and tighter, and also with Professor
Strauch going across to become director of CEA around 1970, I think at exactly when he became director of CEA really, the bubble chamber group, Professor Street was more or less of retiring age, and when Strauch became director of CEA the bubble chamber group really lost senior faculty member. There was myself and Al Brenner still is here. Al was a senior research associate, and I think I was still just about a research associate or research fellow. And we really didn't have very much support. Unfortunately the decision was made to terminate the bubble chamber group. Also, to be fair, bubble chamber physics I think had passed its prime, and to be competitive you need a very large automatic measurement facility. We either had to make the decision to go big or to drop out of it. And the decision was made to drop out and the bubble chamber group was terminated in 1972. Somewhere around that time Professor Rubbia [?] joined the group, and so we became this is when I start knowing about [???] the group as such — it started to be called the high energy group. I think I might have even started calling it that when I started getting involved in the administration. We were still centered very much at the cyclotron, because that's where the machine shop was and there was this very strange dichotomy what was a cyclotron. The cyclotron is still operating, sort of limping along under Andy Kohler. Everyone still refers to it as cyclotron lab; it's the high energy group. And the people were still concerned mainly in the late '60s, after the explosion with the experiment at CEA, except the then bubble chamber group was still doing these things at Brookhaven. Around February 1970 CEA got a cut of about 50% in their operating budget. They had been very interested in building storage rings, electron-positron storage rings. A proposal to build a storage ring had been turned down, but it was starting working on essentially converting the accelerator into a storage ring with a bypass which would bypass electrons and [???] store positrons, and they were meeting them [?] [???] by passed. They were sort of limping along on operations funds. They got a cut in 1970 to 50% and they had to make the decision then whether to continue in ordinary photon-electron physics or concentrate on the bypass, which collided beams. And they made the decision to concentrate on the bypass. Part of the high energy group was involved in the first experiment that would have been done on the bypass was [???] that was Prof. Wilson. Prof. Strauch then was director. For the others while the bubble chamber group was being phased out, the others really had to find someplace else to do their high energy physics, and Pipkin took the program. He had been working on it here at CEA to Cornell, which then by this time had an operating electron synchrotron. A little bit higher energy now, 12 [???] I think. So his program was continued mainly at Cornell. Prof. Rubbia was new to the group, and this was around 1970 the National Accelerator in Chicago was being built, the proton machine, originally scheduled to be 200 GEV, and moved up and up until it's 300, 400 regular now, and has run at 500. And so the group started proposing experiments, and we had three proposals and three accepted. And since that time, apart from Frank Pipkin's Cornell work, there was the bypass experiment which Wilson was involved in at CEA. The rest of the work has been mainly NAL. Right now we have a group, also a small group, working at Brookhaven, and Prof. Strauch is now involved in something at SLAC. And I guess Rubbia has always been involved with experiments on the CERN colliding proton beams. But we really aren't too much involved except through him. We don't really do very much there as a group.
Sopka:Is it true then, that here in Cambridge there are no operating machines at the moment?
Law:No operating accelerator. Well, the cyclotron still runs for medical physics, but there's no operating high energy accelerator. CEA of course concentrated on the bypass, did get an operating bypass without the luminosity that they'd hoped for. But we did — and I became after the [???] machine closed down, involved in that experiment. We did get the first measurements of hadron production, plus or minus 4 GEV, 4 and a half. And it was very frustrating because the machine was being closed down completely then. The machine was closed down in '73. It was frustrating because if you got these anomalous high hadron production cross-sections, which no one understood and didn't really believe I think. And this was just the forerunner of all this exciting [???] plus and [?] minus that has now come out a sphere with all these new particles, the resonances and things. We sat at two energies. We just missed one of these resonances. Had we found it I don't think we would have believed it because we had been sitting at one [???] but it was just the start of that and the machine had to close down because of the whole cutback in high energy research funds. Not so much a cutback in total funds, but the fact that the Fermi National Lab was being built up and taking more and more of the funds. I think the only thing that has happened since then is that the high energy group as such with closing down of the CEA and the accelerator actually just literally tour to pieces and scrapped, we were very cramped in the cyclotron building, and we have moved into what used to be the CEA buildings, and what was CEA is now called the High Energy Physics Lab but there are few people apt to forget and still call it CA. The machine shop and electronic shop and everything have moved into there. Now it's the High Energy physics lab. And all our experiments have to be outside Cambridge: A lot in Chicago. As I said, one small group at Brookhaven; people getting involved in SLAC and having that G [?] run there; and Pipkin's group at Cornell.
Sopka:Does that affect the attracting of people to do high energy physics experiments at Harvard? In other words, if you had a young person, graduate student or post-doctoral, they would tend not to come to the Harvard area now?
I don't think it helps. I don't know if it's quite as bad as that. I don't think that's quite such a — for graduate Law, students I don't think that's the main thing. I think the main thing for graduate students is they know there aren't very many jobs. The high energy population at universities is not expanding. So the only jobs for people with Ph.Ds. after postdocs have to be out of universities. It's very hard to stay in the high energy field unless you go to one of the national labs.
They aren't expanding all that much. So I think certainly we've seen a decrease in graduate students. I don't think they are hurt so much from just the accelerators isn't here they don't mind that. They just ship them out to where they are. It's just that they know there aren't very many jobs. I think for assistant professors and post-docs it has some effect. I think it's just more convenient living near the accelerator. But I think Harvard, because it has a better name, still wins out say over some of the local Chicago universities. SLAC, Stanford being near SLAC, Berkeley, having good names and having their own accelerator there. I think the problem is what happens after the assistant professor level, where do people go. And a large number of people unfortunately are dropping out of the field.
Sopka:I'd like to ask about the relationship between the experimental high energy people and the theoretical people. Is there much inter-communication locally?
Law:In my experience, no. I think if you ask some other people they might disagree. There was never very much communication between the bubble chamber group on the fourth floor and the theoretical group on the third floor. The only time we saw them is when they came up to the Christmas party. I think this has been one of the bad things. I think it's improved a little bit more recently with I know Rubbia's group is a more cooperative group. I think the theorists have been a bit more practically inclined. I mean, right now, because it's very exciting with Sheldon Glashow and the whole group here in The Charm business. But certainly, looking back in the last 15 years, it's something that struck me very much when I first came. There was no dialogue, at least at my level, at the research fellow level, assistant professor level, between the experimental groups and the theoretical groups. And that was very different from Birmingham where we'd all gotten together at tea time and were talking. Prof. Piles [?] who was the head of the department there I wouldn't mind asking him some question. Here I wouldn't even dare to go and ask Schwinger or anything. I think Schwinger only spoke to me twice in the whole 10 years here, that he and I were both in the same building. So I think it's better now. In a sense as the experimentalists, we have to go and ask them.
Sopka:I wondered how, as the future physics develops, whether there are some suggestions for specific lines of inquiry from the experimental point of view, do they have to be generated within the experimental group, or would the theoretical group come up with some inquiries that might prove fruitful and feasible?
I think in the past it's usually the theoreticians that-well, it works both ways. Most recently I think it's — now, thinking about it I'm thinking of examples. After the theorists would come up with a theory based initially on some initial experimental results, they will come up with a theory that then suggests other experiments to either confer or disprove the theory. Protect those new particles that came out [???] plus or minus. I mean, they were — well, if you like, they were already suggested by theory by Shelly Glashow when he first proposed charm many years ago. But people have sort of forgotten about this, and they came as a big surprise, and immediately the whole of the theorists jump onto this and come up with all sorts of other things that one can check out. So it's a sort of two way process. Sometimes I'm thinking things way past, and then the theorists have come up — like Fermi proposed the neutrino and new Yukawa meson. It was many years before experimenters found this particle.
Sopka:Certainly from history of physics there have been a number of places where there has been input from both sides alternately —
Law:I think it works both ways.
Sopka:I was wondering about the present situation as you saw it.
Law:It's working both ways now I think. This whole last two years have been a lot of unexpected things found in experiment work, some which seem to be fitting into what theorists several years ago were talking about. And then the theoreticians get onto that. I think right now maybe there's more experimental data; the experimental data is leading the theories at the moment. A few years before that there was a sort of doldrums, period of about five years where nothing much new was happening experimentally.
Sopka:Do you envision going ahead and building bigger, more energetic machines without a foreseeable limit other than financing?
Law:There's only the financing that stops it. Technically certainly it's possible to go out to 1000 GEV or higher, and of course this is proposed at Fermi Lab where they want to double the energy up to [?] GEV. It's the money that stops it. Well, it's strange. In the past — it's very hard to justify that high energy accelerator because you don't know until you've built it and until the experiment what it's going to do. In the past one has always justified higher energy by saying, "Well look, there must be something new happening in that energy region. And in the past it's surprising; people were worried about the NAL energy jumping up to 200, 300 GEV — maybe there isn't anything that exciting. Is it justifiable to spend a quarter of a billion dollars? And yet it has come out. These first particles came out from SLAC's electron-positron storage ring, but they've been confirmed in lots of new experiments. Lots of new things have come out of the unit proton machine at Fermi Lab. So once again, jumping to this higher energy, it's proven true. We've had a sudden influx of new things happening. So I don't know. I think we'll get up sometime to 1000. I don't know what happens beyond that. I think the next way in this is a way a lot of [???] to get the higher central [?] mass energies with colliding beams. Of course, CERN has the proton colliding beam. But they of course have the disadvantages in that you can't get secondary beams. You're tied in to looking at one reaction, proton plus proton, and maybe electrons and protons if you have an electronic storage ring, too. But it certainly — I mean, it's already slowed down the number of new facilities.
Sopka:Have you maintained your contacts with the British scientific communities since leaving?
Law:Not really, no. I mean, I know people I knew personally.
Some of them I still have contacts. I haven't in any other sense. English people, the British people now and in the past 10 years or so, they really are in a disadvantaged position because they don't have their own accelerator very much now. They operate largely from CERN and obviously have published some papers. But I haven't been in contact really. It's too long.
Sopka:Well, I thank you very much. It's very valuable to get your point of view.