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Oral History Transcript — Dr. Edwin McMillan

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Interview with Dr. Edwin McMillan
By Charles Weiner
At Dr. McMillanís Office, Lawrence Berkeley Laboratory, Berkeley, California
October 31, 1972

open tab View abstract

Edwin McMillan; October 31, 1972

ABSTRACT: Youth and early education; undergraduate years at Caltech, 1924-1929; influence of Arthur A. Noyes, Linus Pauling; graduate training and molecular beam work at Princeton University with Karl Compton, Edward U. Condon, Robert Van de Graaff, 1929-1932. National Research Council Fellow at University of California at Berkeley, 1932-1934; at Radiation Laboratory with Ernest O. Lawrence, J. Robert Oppenheimer; on Berkeley staff as teacher and working on cyclotrons, nuclear physics and radiochemistry, 1934-1940. War work at MIT, Underwater Sound Laboratory at San Diego, Los Alamos Scientific Laboratory, 19401945; Trinity Test. Postwar career at Berkeley working on accelerators; Nobel Prize, 1951. Also includes ďImpressions of Trinity Test,Ē 2 pp. Also prominently mentioned is: Jesse William Monroe DuMond.

Transcript

Session I | Session II | Session III | Session IV

Weiner:

Today is the 31st of October and we are resuming our discussion. We have taken it through the Los Alamos period and jumped in a little bit to the return to Berkeley and wanted to cover that immediate post-war period. Several things were involved here: your expectations of what life would be like after the war, your plans for your own work, the relation of those plans to the projects of others here and to the overall development of the laboratory. Secondly, how the atmosphere changed because of the war, the immediate openness of the laboratory, change because of security and visitors, the relationship to the entire University (it was a difficult period in a university generally) — these are the kinds of background things that we said we would get into.

But I would like to keep the central thread, the idea of your own work — what you did and how the synchrotron was developed, how the principle was applied in other ways, and to keep in mind the overall development of the field beyond Berkeley, a development which you played a part in through correspondence, through conferences, through the use of your ideas elsewhere, and through your learning from other peopleís ideas elsewhere. Thatís the general introduction to this section. Let me ask specifically about the arrival back here. When did you know the date of your leaving Los Alamos? Was it clear to you that the day the bomb was dropped was the day to start packing and go home?

McMillan:

No, there wasnít such a clearly defined arrangement as that. It was certainly my understanding that I was on leave from the University of California and would return when the war was over, and so that set a limit to the time I would return. The actual final date, I think, was determined more or less by how long it took to clear up my things and get the proper arrangements made. Whit was the actual date of the ending of the war?

Weiner:

The bomb was August 6th, and V-J Day was August 7th, 1945.

McMillan:

Whatever it was, when I left was around the middle of September, therefore a little less than a month after the end of the war. That period was not determined by any specific thing that I remember. It may have been determined by the academic year, as a matter of fact.

Weiner:

Had you had correspondence or discussions with Ernest Lawrence regarding the overall plans for the laboratory in the post-war period?

McMillan:

I am sure I had. I know that I had discussed with him the building of an electron synchrotron and he had discussed with Alvarez the building of a proton linear accelerator, and that he was hoping to get support for both of these. So these two projects were started when we both came back, which was about the same time. Alvarez, as I remember, back a little bit later, but not much. And Lawrence had talked to Gen. Groves who was the head of the Manhattan Project and had gotten some kind of promise of financial support for these, so both of these construction projects were started before the existence of the Atomic Energy Commission. Getting money to build equipment was a little different then from what it is now. Things could be arranged in a more personal way at the high levels, such as between General Groves and Professor Lawrence. That kind of thing could not be done that way today.

Weiner:

Was there in your own mind an expectation that funds would be a lot easier as soon as the war was over?

McMillan:

During the war the laboratory had grown enormously. After the war there was a diminishing phase in the size of the laboratory, but the scale of support had changed very radically — the difference between private support and government support was in an entirely different scale of magnitude.

Weiner:

Yes, but the government support was for a very specific project.

McMillan:

That is true, but the Manhattan District was very forward-looking. At the end of the war the leaders of the Manhattan District were aware of the necessity for maintaining nuclear science in the United States and were, in fact, very forward-looking. I might add that some time in there, the Navy, through the Office of Naval Research, started to support accelerator projects in the United States, and was very important in the early days of this field of high energy physics. Although this laboratory was being supported through the Amy initially, the Manhattan District, other laboratories were being supported through the Navy, through the Office of Naval Research, for building high energy accelerators.

Weiner:

Places like Rochester, for example I was thinking of the story about Alvarez wanting to salvage radar equipment and having that kind of thinking of using what was available. That indicates that he thought the scale of support would not be so great and that it still would be difficult. In other words, the prewar frame of mind regarding finance I was wondering whether people came back in that frame of mind and then it rapidly changed.

McMillan:

No, I donít think the use of salvaged equipment is inconsistent with more generous financing. One explores every avenue to get the equipment that is needed, and if it is available in an already fabricated form, so much the better.

Weiner:

Thatís a good point, because sometimes that kind of story is used to indicate that expectations of financing are low.

McMillan:

People still use salvaged equipment we still do.

Weiner:

And destroy much of historical interest in the process.

McMillan:

Exactly.

Weiner:

What duties did you pick up when you got back? Did you just walk into the lab and start as if...

McMillan:

More or less, As far as I know, I went right back to teaching duties. Of course, I started to get some designs ready for the synchrotron which I was planning to build, and got some people to help me in that. At the same time that Alvarez and I were working on our machines, the l84-inch cyclotron the magnet was here — there were people planning to complete that into a cyclotron. The chief person there would be J. Reginald Richardson, who had been here during the war with that project. And a number of other people whose names we can get. The new idea of phase stability was now there and the possibility of using this, applying this to the cyclotron, was very much in the air, and Lawrence wanted to have a check of this principle. To apply the phase stability principle to a cyclotron involves the modulation of the frequency with time, which was done by using a motoródriven rotary condenser. These experiments were carried out by this group and the principle was shown to work, and then the whole orientation of the design of the machine was turned toward a synchrocyclotron, a name which was originally proposed by Ernest Lawrence — the application of the synchrotron principle to the operation of a cyclotron. So that was a parallel development along with the other two things that I have mentioned.

Weiner:

How closely did you work with the synchrocyclotron group?

McMillan:

I was working both on the synchrotron and the synchrocyclotron.

Weiner:

Did that increase the cost — combining the synchronous principle in the cyclotron?

McMillan:

I think it actually reduced the cost, because the power required for the high frequency system was so enormously reduced below that needed by the brute force method. I would think the cost was actually reduced. I do remember that some of the power equipment which had been ordered back before the war, which mentioned earlier, was actually delivered. Some I think got used for other purposes and some, think, was simply either returned or abandoned the modified oscillator and oscillator power system used much less power so although I cant give you those figures, think the cost was less, and of course the energy was very much greater than would have been possible The initial energy of the l84-inch cyclotron what is it on your lists?

Weiner:

ďDeuteron and alpha particle beams of approximately 200 and 400 MeV, produced as of February 26, l947.Ē

McMillan:

That is more than twice the energy we would have had without the modification. Later the cyclotron was modified in several steps so that the energy is now 750 MeV, for protons.

Weiner:

So you worked with this group. I see the names on the paper regarding 9nitial Performance of the 184-inch Cyclotron of the University of California — Brobeck, Lawrence, MacKenzie, McMillan, Serber, Sewell, Simpson and Thornton. I assume that these were people who were involved in getting it to the point of having an initial performance and that is why their names are on the paper. Is that correct?

McMillan:

I notice that one of the names, Serber, being a pure theorist was not involved in the work, but he is unquestionably in there because of his theoretical work done in connection with the design.

Weiner:

I had a talk with him about that. I havenít looked at what he said recently. I had forgotten that that portion is covered in terms of the calculations.

McMillan:

Do you have an interview with Serber?

Weiner:

Yes, although he has never corrected it. It has been sitting on his desk for years.

McMillan:

Really, you gave him the transcript and he never sent it back to you. So you donít have it — you have a copy of it but you canít use it.

Weiner:

Thatís right.

McMillan:

Iíll have to get after him.

Weiner:

His was a little more difficult. The speech patterns were different and it was difficult to transcribe. But it takes work to do.

McMillan:

Of course it takes work to do. I might say, having seen the transcript of the first section of this, that my speech is more coherent than I ever thought it was.

Weiner:

There was no doctoring done. Sometimes when one gets something poorly transcribed, one thinks ďHow terrible,Ē but all it reflects is the transcriberís inability to get your speech patterns, or she puts in artificial punctuation or none at all. A good transcriber will reflect accurately what was said.

McMillan:

It is interesting that the patterns of ordinary spoken speech are so different from those of written speech. When I write, I try to write rather meticulously and structure everything rather carefully. When I speak, I find I break sentences in the middle and I say ďYou knowĒ in a meaningless way. It is an interesting fact that the methods of communication by speech and by writing are quite different things.

Weiner:

Did you ever try to have the illusion that by giving a talk somewhere you can present it for publication at the same time?

McMillan:

Definitely not.

Weiner:

So there was a well-defined group that was working on the 184-inch, a group with which you were involved, and at the same time your project was the design stage of the synchrotron. They were dealing with hardware already.

McMillan:

Thatís right. I would say that my part in the cyclotron work was really more advisory. I wasnít actually doing hardware but I was certainly in daily contact with that effort. My own direct effort was achieving the design for the electron synchrotron and, of course, going through the process of getting materials ordered and components built.

Weiner:

In this period you were a staff member of the Radiation Laboratory.

McMillan:

I was an associate professor and a staff member of the Laboratory.

Weiner:

The group for the electron synchrotron was just formed around you.

McMillan:

Thatís right.

Weiner:

And procedures were set up so that you could order things you needed. How were these decisions made? Was it just through an understanding between you and Lawrence, or by that time had any formal decision-making thing developed?

McMillan:

No, there was no formal organizational structure. Lawrence didnít like formal organizational structures. The groups were somewhat loosely organized.

Weiner:

Lets talk about the group on the electron synchrotron how many people, and Iím interested to know whether there were students involved, whether they were mostly technicians, if the group changed in its personnel?

McMillan:

The group did change in personnel. Iím not going to try to remember who the members were. It may be possible to get them from records. I could remember some names but it doesnít seem quite fair to give a spotty list and leave out someone who was equally important. There were some other faculty people with me; there were staff members; there were some engineers; there were some technicians. And then of course the Laboratory here was organized so that the engineers had their own group. (I should say this was the way it was organized during the war, which has persisted. Previous to the war there was really no organization at all.) So engineers would be assigned to work with me but actually belonged to their own group, and had some of those people assigned to me.

Weiner:

You mentioned faculty. I donít recall that you mentioned any students.

McMillan:

I donít think I had any graduate students actually involved in this work. Graduate students come to the lab to do research, and they get involved in experiments done with apparatus and sometimes in design and construction of apparatus that they can use directly in the experiments, but not so much in the design of a major accelerator.

Weiner:

Approximately what number of people are we talking about?

McMillan:

Iíd say about a dozen people involved in one way or another in this design effort.

Weiner:

And about how long did that effort last — until it reached the next stage?

McMillan:

When did the machine first operate 0 thatís a good fixed date because I put it down.

Weiner:

It is probably in your chapter.

McMillan:

It is in my chapter.

Weiner:

We were trying to fix a date for the end of the design period and the beginning of the operation. Do you have the feeling that from the start of the design, which we will assume was when you arrived back, until the actual operation would have been a period of a year or two years?

McMillan:

No, it was over two years. We had quite a lot of trouble with that machine. The initial design concept for the vacuum chamber didnít work out very well. I originally planned to use the actual pole tips of the magnet as the vacuum wall of the chamber and, since these are made of laminated iron, this involved getting a good vacuum seal between the segments out of which the poles were made. And the vacuum walls were made of a glass fiber filled plastic material. There were a lot of troubles with vacuum, a lot of trouble there. We had trouble with the shape of the magnetic field, which was pretty distorted by imperfections in the magnet iron. The high frequency accelerating system had a design which fitted in with this construction, and although it would oscillate all right, the whole system was not successful in that form, chiefly because you couldnít get a good enough vacuum in it.

So at a certain stage we had to completely revise the fundamental design of that part of the system and go back to a more conventional design, using a doughnut shaped chamber which was made out of fused quartz. So we had to go through the process of changing signals right in the middle of the game, to introduce the quartz doughnut. When that was done, and the problem of getting the magnetic field to a reasonable sort of uniformity was solved, which was done by a large number of correcting coils adjusted by a panel filled with little knobs on the control tables so one could make spot corrections around the magnet pole, then the beam was found reasonably quickly. Thereís an interesting story about it, written by Bob Wilson, contained in a book which was a commemorative volume for Professor Bethe, in which he wrote a chapter called An Anecdotal History of Accelerators at Cornell, in Perspectives in Modern Physics.

Weiner:

Edited by Marshak.

McMillan:

Thatís right, and in that book he gives a little account of what happened just around the time of turn-on there, and its given correctly; in my own chapter in Segreís volume III, I refer to that too, the fact that had been in communication with Wilson by telephone, and he told me that he had succeeded in finding a beam in his machine by starting with an extremely low magnetic field, and I tried that, and it worked here too. So that story has been told. I donít think I mentioned before that other synchrotrons were started about the same time I had started. The synchrotron idea was so simple and so clear that as soon as it was announced, various people started using the principle. The first synchrotron to operate was actually made in England by Goward and Barnes, by modifying an existing betatron, using the ceramic doughnut and applying the synchrotron accelerating electrodes to the outside of the doughnut, the electric field going through the ceramic. The first synchrotron to operate in the United States was at the General Electric Company, built by Pollock and Westendorp. The General Electric Co. had learned about this very early because Lawrence was a consultant to them, and I think they knew about it even before the publication.

Weiner:

Was this built in Schenectady?

McMillan:

In Schenectady, right. By the way, this is an interesting historical fact, Goward and Barnes, who made the first operating one, got the idea from my paper and not from Vekslerís. I asked one of them later, and they had not seen the Veksler paper at that time. As far as the western world was concerned, the genetic line of development was from my paper, rather than Vekslerís.

Weiner:

How did Wilson know about this? Had you discussed this with him at Los Alamos?

McMillan:

I had discussed it with him at Los Alamos.

Weiner:

Had he indicated then he was going to do something with it?

McMillan:

Somewhere along the line, I certainly knew he was going to. We were certainly in communication all throughout that. Then there was one built at Purdue and one at MIT, the earliest large synchrotrons.

Weiner:

These were all started at about the same time?

McMillan:

They were all started about the same time, yes. Once the thing became known, a number of groups started working on it.

Weiner:

At the same time, synchrocyclotrons were starting. In addition to the one here, UCLA had a synchro-cyclotron, and GE had a synchrotron. Bartol had a synchrotron, am I correct?

McMillan:

Bartol had a 60-inch cyclotron.

Weiner:

During the period of simultaneous building of synchrotrons, was there communication by letter, telephone, personal visits or meetings among the people all doing the same thing?

McMillan:

There were no meetings on the subject. I donít think anybody had an accelerator conference then. There were certainly communications, mostly by telephone probably. At least I donít seem to have much correspondence left on this subject know was in communication. Also visited people I know visited Wilson at Cornell, possibly after his was running. I know I saw the MIT machine. I know never visited the Purdue machine.

Weiner:

In the pre-war period when there were a number of cyclotrons being built simultaneously, there was a great deal of communication emanating from this laboratory at the time. There was a regular informal network established with Cooksey sending out technical memoranda and exchanging it among the various people. I wonder whether that had changed in this situation?

McMillan:

Well, there was nothing organized.

Weiner:

Was there more of a feeling of competition?

McMillan:

We were pretty cooperative. We were not withholding anything. We were of course competitive in the sense that each one would like to operate first. That is expected. But we were not trying to conceal anything from one another. I think the situation in the early days of the cyclotron was a little different, in that Berkeley was the recognized center with a sequence of operating cyclotrons, and it was natural that it would be a sort of father figure to the other laboratories. But when the synchrotron building started, because of the early publication, we got off to an even start. The interval between getting started was short compared to the time it takes to build a machine of that size, so with the exception of the Goward and Barnes machine, which was a modified betatron, and the Pollock machine, which was made from parts originally intended for a betatron, so that those two small machines had a head start, the three 300 MeV synchrotrons were all under construction at the same time. Dick Crane was also doing one at Michigan, using what he called the racetrack design, which was the prototype for the modern proton synchrotron.

Weiner:

Were you in touch with him?

McMillan:

Yes, I was in touch. I did visit him. I remember going out one time to see him, and, discussing the problems he was having with the laminated iron at the edge of the sections of the racetrack. The magnetic field crossing the laminations was producing field distortions which were making a lot of trouble, remember that. That was one of the problems that had to be solved before one could build a machine of that type, in which the magnet consists of several isolated segments with straight sections between, instead of being a continuous ring.

Weiner:

Iím thinking about the various places you mentioned building a synchrotron — they are all places that had cyclotrons in the pre-war period, Purdue, Michigan, MIT. This would have given them some expertise to start with, and then the application of the new principle becomes a motivating thing.

McMillan:

Thatís right.

Weiner:

They all seem to have that much in common, and youíre saying that they all were looking for a similar energy range.

McMillan:

That energy range was simply copied from mine.

Weiner:

The question is, did you have that energy range designated because it was technically feasible, or because it would allow you to do something with high energy?

McMillan:

It was based in a loose way on the estimated threshold for making mesons.

Weiner:

And this was based on what kind of theoretical understanding? Did this estimate come from work in the Ď30s starting with Anderson, Neddermeyer, Street and Stevenson?

McMillan:

Well, you ask where does the estimate come from — once you know the mass of a particle, then you know how much energy it takes to create it. The only information that would come out of the work youíre mentioning is the estimated mass of the particle. Once you know that, you can calculate how much energy it takes to create it. I was assuming at that time that they might have to be created in pairs. The energy was roughly the equivalent of 100 million volts, so it takes 200 to make a pair, then you give yourself some margin, so youíre at 300. That was as I say a very loose kind of argument which went into that figure. But the other builders who started at that time certainly took that energy right from my paper, my letter on the subject which suggested that energy.

Weiner:

During this period, the understanding of what a meson is and what it is not was undergoing great doubt.

McMillan:

Yes, and finally when the pion was discovered, the pi-meson, in Ď47, it was quite clear that you donít have to make these particles in pairs so that the estimation of the threshold could be set down, but of course the construction of the machines was already started by that time.

Weiner:

How closely did you follow those kinds of discussions? There were cosmic ray papers and so forth beginning to reveal lots of trouble...

McMillan:

I was deeply interested in this field. I was following the work very closely. I wasnít doing cosmic ray work but I was certainly awaiting with great eagerness any results that came out.

Weiner:

Were they discussed here in colloquia? It was the kind of thing that Oppenheimer had been interested in.

McMillan:

Oh yes. Right. A number of people here were interested in that. It was great subject of discussion.

Weiner:

In this case, you had set the energy, so that these results as they began to come out didnít affect your situation at all. It wasnít a case of just missing something. In this case you had more than you needed.

McMillan:

Certainly.

Weiner:

There were instances, werenít there, where people designed it too low?

McMillan:

There were some of the synchrocyclotrons which were designed with energies too low to reach the meson threshold, which was somewhat of a disappointment to those who built them. I almost left out that Oliphant was also building a synchrotron, and his development had started in a parallel line. He also had planned something of this kind during the war. This is mentioned in my chapter in the Segre book. His publication came out well after mine. He was caught up by the patent department in England. I talked to him about it. The patent department there did not want him to publish anything, so his was not published until later.

Weiner:

In 1950.

McMillan:

Whenever it was. Iíve never been able to learn exactly what his initial design was like, but it was in some report written during the war, and one time I asked him about it, and he was trying to see if he could find this report, but he never did find it. At least I donít have a copy of it. So I donít know exactly what his initial design was, but by the time he came to building it I think it became more like the design which I had.

Weiner:

During the approximately three year period of design and construction, before operation, you said there were communications up to a point and sharing technical knowledge with people in other institutions. Were there many visitors? This was a period right after the war when the laboratory was still readjusting.

McMillan:

Well, it was not only still readjusting, but the laboratory was a closed institution and work done there was automatically classified. Then there was a board set up for declassification, which had to decide on every single case. Nevertheless, in matters like accelerator construction, we did discuss things quite openly with other people.

Weiner:

But if this was work being done in a closed laboratory, then technically youíre only able to discuss it with people who have specific...

McMillan:

I suppose that would be so, but we didnít really carry it that far.

Weiner:

Would people like Wilson visit this laboratory during that period? Iím using him as an example of someone building a related machine.

McMillan:

Iím reasonably sure that he did.

Weiner:

I just learned yesterday that the meeting Iím going to be at in two weeks is one that he will be at also.

McMillan:

Oh, great, he may be able to fill in some of these things,

Weiner:

Now, when you say closed laboratory, perhaps someone like Wilson, who would have lots of reasons to come here—

McMillan:

Well, Wilson, having been at Los Alamos was Q-cleared like people here. Anyone who worked Manhattan District, when that became the AEC, got clearance system, so he would carry a pass with him and thereíd be no difficulty.

Weiner:

But a foreigner, for example—

McMillan:

A foreigner would need some special permission to get in.

Weiner:

Iíve seen letters of people, Chadwick and others during this period, complaining about the breakdown in the open communication system, thinking that the restrictions were somewhat severe.

McMillan:

I think that the restrictions were unnecessarily severe, but they slowly got reduced, and at a specified date which we can find out, the laboratory was opened. It was no longer necessary for clearance or special permission to come in. Even today we require some identification to come in, but that is for what you might call industrial security, not military. It is simply that in any place where thereís a large quantity of fairly hazardous and exposed equipment, you canít trust casual people wandering about. But that date we can find. I think it was around Ď56. [It was in Ď55]

Weiner:

That was a long period of time.

McMillan:

It was long period of time, yes.

Weiner:

I am curious how it affected accelerator development in particular since the pattern of development had been such an open exchange in the prewar period.

McMillan:

Right.

Weiner:

And youíre saying that certainly there was some exchange. I imagine it would be tremendously inhibited.

McMillan:

It wasnít inhibited as far as publication was concerned. Publications of design features and operations all had to be declassified, but they were declassified without any effort; they were obviously not secret information. But itís not the same as someone coming in and then going back to his own lab.

Weiner:

On related projects, we mentioned the two in which you were most deeply involved, the synchrotron and the synchrocyclotron.

McMillan:

Right. Then there was the Alvarez project, and since youíve interviewed him, heís probably told you about it.

Weiner:

Well, somewhat, but I want your comments on that and any others.

McMillan:

I was very interested in that of course, but I was not a participant in the linear accelerator project.

Weiner:

The way it was structured, that was a separate group?

McMillan:

That was a separate group, yes.

Weiner:

What were some of the other projects? Were there just the three? When did the Bevatron start?

McMillan:

The Bevatron, I believe the first concept of the Bevatron was in 1947, or maybe Ď46. I have a blueprint of the first conceptual drawing made by William Brobeck, dated either Ď46 or Ď47, I can get that. [It is dated Nov. 12, 1946]

Weiner:

How long after the concept was the decision taken to go ahead and build it?

McMillan:

Things moved reasonably fast on that. Brobeck made the original design. I know he talked with me extensively about it during the time he was making this design, the original design being for 10 billion volts, and scene cost estimates were made. Lawrence felt that these costs were too high and insisted that the energy be reduced below this 10 billion volt initial plan. I think the 10 billion volts was based simply on that being on being a round number. And when the proposal was made, with the discussion of reducing the energy, I calculated the threshold energy for producing anti-protons.

It was quite clear that if antiprotons could be made, theyíd have to be made in pairs, and there was a perfectly good formula for calculating the energy which would be needed to do this, and we were now talking about such high energies that the calculations had to be made relativistically, I made this calculation and found that the threshold would be something around six billion volts, and at the same time I was doing this, I learned that Panofsky, who was here, was making the same kind of calculation. And we both went to Lawrence and insisted that the energy not be reduced below the threshold for making anti-protons, in case they existed we wanted to be able to find them here.

This is the origin of the story often told that the Bevatron was designed for the purpose of discovering the anti-proton. That is not true. It was originally designed for a higher energy, and then a ceiling was put on, which was the threshold, so the actual energy was 6.2, which was enough above the threshold that once the experiment was tried, anti-protons were found. I recall a meeting with the General Advisory Committee to the Atomic Energy Commission, for which I went to Washington to testify on the importance of building these projects, and at that time, this energy assignment had already been suggested. The discussion was on that basis. If you can get access to AEC records, you can find out the exact date of that meeting.

Weiner:

It might be in the second volume of the official history.

McMillan:

It may be in there.

Weiner:

Iím curious about the kind of discussion that led to the Brookhaven decision, the mutual decision, to handle two similar machines in two different energy ranges. Did that decision take place here on Rabiís visit, or was it by subsequent correspondence?

McMillan:

I wasnít involved in those discussions.

Weiner:

What was advantage to Brookhaven to have a machine half, the size of yours, since yours was fixed at a level that would produce antióprotons?

McMillan:

Youíd have to ask them. Of course, 3 BeV is a high enough energy to do a lot of things. But youíd have to ask them. Iíve been told that there was not universal agreement in this decision and that some people were very unhappy about it. They felt that they should have built the higher energy one. Actually the way it worked out, the Cosmotron was finished before the Bevatron, so they got turned on first. Then when the next generation of machines, the strong focusing machines, was built, it was at Brookhaven. So in the end they came out fine.

Weiner:

I remember rightly, Ramsey has written a historical account of the origins of Brookhaven. It is perhaps in there that the point was made that they wanted to get something built and operating soon, because it was necessary in the overall plan of Brookhaven.

McMillan:

I believe the decision was made finally by Lee Haworth, who was then director. Iím not sure he was director. When did Haworth become director?

Weiner:

I donít know exactly. [1948]

McMillan:

Well, these things we can all look up. The interesting thing, though, about history, is that in the early history in which the records are very scant, in some ways it is easier to find out things than in the later history when the records become voluminous. In the early history, there are frustrating gaps in the documentary record, but whatís there seems to be fairly clean cut. Things get worn down by time, like a bunch of pebbles in a tumbler that get polished, and you get little gems of memory or thought which come from the past. In the present day things havenít been polished yet, and the facts you get come in a tangled mass. So now the record is all there, and all we have to do is go look, but we donít necessarily have everything sorted out as nicely.

Weiner:

Yes. There are official accounts and then there are unofficial accounts. Well, that was an answer to the question on the Bevatron. The point was to get a look at the various projects going on here simultaneously in those first post war years. You have an electron synchrotron, a synchro-cyclotron, a proton synchrotron, and a linear accelerator.

McMillan:

Right.

Weiner:

Was the other cyclotron still operating, the 60-inch?

McMillan:

The 60-inch was still operating. The magnet of the old 37-inch had been moved down to Los Angeles, to UCLA, and rebuilt there by Richardson. The 60-inch was running. It ran steadily throughout this whole period, and was used very extensively by biologists to make radioactive materials.

Weiner:

When did the reactor work start here?

McMillan:

There never was any reactor work here. No, there never was any here. There was a reactor later on at Livermore, but that was a purchased machine and was used for doing neutron work, but there was no reactor development then.

Weiner:

Ok, so far this period youíve characterized pretty well whatís going on.

McMillan:

This was an accelerator laboratory in Berkeley. Weíve never done reactor work.

Weiner:

What about the experimental programs? It seems to me that youíre beginning, with the large machines, to get into what we now call high energy.

McMillan:

Right.

Weiner:

Was there at any time a conscious feeling that this would be the thrust of the laboratory in terms of experimental work?

McMillan:

Yes, certainly so.

Weiner:

When would you date that?

McMillan:

I think it was a continuous process. I think that the laboratory always considered itself a high energy laboratory, but the definition of what was meant by high energy was simply changing. When we started, a million volts was considered high energy. Then it just moved up the scale, each stage, up, up, until the strong focusing machines came in. The laboratory was always at the highest energy, and one simply changed definitions. So there wasnít a revolution of orientation. It was a continuous transition from nuclear physics, the study of the structure of nuclei, on into particle physics, the study of the nature of the elementary particles. And of course when you have such a transition, always some of the old line persists. So there was always work here, continual work in nuclear physics, which was pursued in the chemistry division, We had a chemistry division which was doing what would now be called low energy nuclear physics, that is, the study of the structure and reactions of nuclei, while the physics division moved on into the study of the nature of the elementary particles.

Weiner:

A formal division?

McMillan:

I was using the word ďdivisionĒ in the sense of an organized part of the laboratory, like the physics and chemistry divisions. In the other sense of the word, the division between nuclear physics and particle physics is a scientific distinction. In nuclear physics one is interested in how the nuclei are made up out of the elementary particles. And of course, to understand that thoroughly, one has to understand the nature of the particles that are being assembled to make the nucleus, so there is a relation between particle physics and nuclear physics. But the orientation, the thought, and the techniques tend to be rather different.

Weiner:

I have a couple of questions about this transition. What about the tendency to attract different kinds of people to the laboratory or to the Berkeley physics department? With the increased attention to particles, did you find that more theorists were becoming interested and more theorists were working more closely with the laboratory?

McMillan:

I canít identify any sudden change there.

Weiner:

What about the ratio of time spent on developing machines to time spent on using machines for a specific experiment? It seems to me there was a tremendous design and construction period in the immediate postwar years. What about the total results coming out of it?

McMillan:

During that period, there was certainly a greater fraction of the time spent on developing and building machines than in the pre-war period, especially because there was this parallel development along four lines at the same time. So almost everyone in the laboratory was involved in some kind of a development project. But results were still coming out. Science was still being done.

Weiner:

What ratio of time did you spend on design and supervision of construction, as compared to actually doing research?

McMillan:

Most of it. I think that shows in the publication record.

Weiner:

Right. Did the relationship with industry develop significantly during that period? It seems to me you were developing much more sophisticated machines here, and that the Bay Area began to develop an electronics industry, not only because of this but maybe independently. Can you characterize any of the changes that took place in this period in terms of availability of components that were specially useful?

McMillan:

Yes, I certainly did notice that. The electronics industry had advanced enormously during the war, so things like high power vacuum tubes, which would have been specially built or a special order previously, were now off-the-shelf items. Special construction jobs were easier to get done. Perhaps I shouldnít say easier, but there were more places one could get special jobs done. And thatís been a continuous development since. Now if you look in scientific journals, youíll see pages of ads from companies who make scientific equipment, the kind of equipment that previously would have been built in each lab for itself. Thereís been a tremendous development in the scientific electronics industry, and the solid state industry is very important there too.

Electronics equipment which would have previously been rather bulky, large pieces of apparatus now come in little boxes full of circuit boards and integrated circuits. The advance in electronics is perhaps the most striking of all. This has made possible types of experiments that could hardly have been conceived before. If one had tried to set up the huge multiplicities of counters and the multiple recording of data which we now use, but with the vacuum tube amplifiers and primitive equipment then available, there would not have been space or money to accommodate them. So perhaps the most striking development is the coming in of the possibility of purchasing very sophisticated and highly miniaturized apparatus for doing things which now one has to do in particle physics, which would not have been possible without them. The computer is also a key item in this. The reduction of data which is needed for some kinds of experiments would have been simply preposterous even to contemplate without computers.

Weiner:

This was in the sixties.

McMillan:

It has not been a sudden development. Itís been a continuous development.

Weiner:

Do you see the roots in those postwar years, Ď47?

McMillan:

Yes. I think thereís been a very strong cross-fertilization. People like to talk about spinoff from science into industry, and many of these developments of sophisticated miniaturized circuits have come from developments made first in scientific laboratories, particularly in high energy physics where the nature of the experiments requires circuits that respond very rapidly, with very short time constants. You need high multiplicities of channels, and I think thereís been enormous cross-fertilization there — many techniques from the accelerator field, like high vacuum techniques for example, have diffused into industry, and now come back, in the availability of already fabricated components of the kind which you would have spent months building in your own shop, and at greater cost.

Weiner:

You say the ideas diffuse from one realm to the other. What about the people? Letís get back to the immediate postwar period. Did you find people who worked in the laboratory going over to industry?

McMillan:

Yes, quite a few did.

Weiner:

Let me get to another question now, your own university career. You became a full professor in Ď46. Iím not sure if it was spring or fall semester.

McMillan:

Well, that would certainly be for the start of the fall semester. Youíre promoted between academic years, normally.

Weiner:

For a person who spends as much time as you had to in design and construction work — and your publications reflect it, these were finished projects — what were you able to do in the teaching realm? What kinds of responsibilities did you have, what kinds of courses did you teach, and how often?

McMillan:

Letís see. I came back to my course in classical mechanics, which I carried for some years after that, and the course in quantum mechanics which I had started before the war. Somewhere along the line I started teaching a graduate course in nuclear physics and an undergraduate course in thermodynamics. At any given time, I donít believe I had more than two full regular courses going.

Weiner:

This involved how many hours a week?

McMillan:

That would involve three hours of lectures per week.

Weiner:

Each?

McMillan:

Yes. That would be six hours of lectures, plus the time spent preparing them.

Weiner:

Did you notice in these first years — after you resumed teaching in Ď45, in the period Ď45 to Ď49 or so — any change in the students, the type of student you were getting, their interest, background, where they went from there?

McMillan:

Well, thatís a hard question to answer. There has been a change in attitude, if you take students of today as against then, and so we have a sequence. We can plot a curve here, for which we have end points. If you ask me to remember just what kinks there were in that curve all the way in between, Iím not capable of doing that. Nowadays, students are much more sophisticated professionally. I notice that in my first session, I say physics has become an industry. It has, to some extent. Itís a recognized profession. When I was a student, there were physicists, but it wasnít a generally recognized profession.

If you were speaking to the lay public and you told them you were a physicist, more than half the time they would confuse that with physician. Physics was not a normally publicly recognized profession, in the same way that chemistry was, for example. Physics students, as I knew them then, tended to be a group of people selected by some special dedication to their subject, some special interest which they had acquired which motivated them to go into this field. Now I think students will choose this as simply one of the professions one may go into, like law, medicine, chemistry, or engineering, and so on. So there is, you might say, a little more of a sophistication in the approach, a little more awareness of what the future is going to be for them. They think more about job prospects.

That transition has occurred, and as I say, one could take two end points and try to fill in between. My best guess is that on this curve the biggest rate of change was post-war, and that itís flattened out a little bit now. The war, the success of the radar project, the atomic energy project and several others, where physicists had moved in and done things that were very valuable for the nation, this brought physics to the fore in a way that it never had been before. And that would be the period when physics as a widely-known profession became so recognized. One other question people ask is, what about the intellectual abilities of students? Of course, I havenít had students for a number of years now, since Iíve been director of the laboratory, but I see a lot of graduate students. Theyíre extremely able. When I speak of higher sophistication, that would apply to their professional knowledge too. Students have very high training now. I have the impression that theyíre considerably more advanced in the actual knowledge of techniques than I was at a corresponding age in some ways less than others. They seem to get somewhat less training in the practical arts.

The graduate students I see now are less experienced in working with their own hands, but more experienced in the intellectual aspects. And one thing which has been a real revolution is the use of computers. Almost all graduate students now are familiar with the use of computers and are able to write programs, which I have not learned to this day. I still donít know how to write a program for a computer, and I donít really plan to learn, as I feel no need for it. But of course if I were a graduate student now, I would most definitely be in there with the rest of them writing programs, and be fascinated with this aspect of science.

Weiner:

The comments about changes — your not having teaching responsibilities when you became director — leads me to something else, and that is, what role Ernest Lawrence played in the postwar period. Letís say from l945-50, what role did he play in the laboratory? What kind of presence did he have there and what proportion of his time was he there, as compared to other national involvements?

McMillan:

He was very closely involved with the laboratory. His presence was very strong.

Weiner:

Even in that period?

McMillan:

Oh yes. He had national involvements too, but Lawrence was a man of enormous vigor and he moved fast. He did a lot of things. There was no lack of his influence in the laboratory at all.

Weiner:

It seems to me you had a period then where there were four projects approximately going on simultaneously, each with a separate group. Then there were the other things like the 60-inch that were still going on, plus the teaching responsibilities that various people had.

McMillan:

Well, Lawrence was not teaching. Heíd stopped teaching before the war.

Weiner:

It would be hard for any individual in any group to keep up with what was going onÖ

McMillan:

Right.

Weiner:

So it would be even more difficult for the director to really be at the shop level in this period.

McMillan:

Right.

Weiner:

When you say his presence in the laboratory, I assume it was quite a bit different from the pre-war period where heíd be right at a machine—

McMillan:

Well, one thing that was different was, the laboratory was expanding in physical size, so it couldnít all be covered. Before the war there was the old Radiation Laboratory and the Crocker Laboratory and Donner Laboratory where his brother John had the medical physics work, but these were all very close together, the Crocker and the old Radiation Laboratory being across the street from each other. So it was very easy to be all places at all times, more or less. But with the laboratory on the hill, and with new buildings being added, the physical extent was increasing and it was no longer possible. He got the habit of going around the laboratory, dropping in and visiting people and seeing what was going on, and heíd always have some reaction. Particularly if there was any progress, heíd communicate a great deal of enthusiasm, and if there was lack of progress, heíd communicate the opposite. But the influence was very strong.

Weiner:

And the organizational structure was still such that you really had to go through him for major decisions?

McMillan:

Oh yes. It still was a one-man show, in the sense that Lawrence was the director. There was no elaborate administrative structure. Cooksey was the associate director and Brobeck was assistant director, and that was essentially the organization, until considerably later when we got associate directors and began to get more of a divisional organization.

Weiner:

That was in 1954, wasnít it, when the associate directors were created?

McMillan:

Thatís right.

Weiner:

Letís talk for a minute about some meetings that took place during the period. I hadnít thought of this when we were discussing how people communicated on accelerator development, besides the fact that the Laboratory was still closed. In July of 1946, the American Physical Society met at Berkeley. I looked at the program of it, and there was a special symposium. The meeting was July Ď46 and Oppenheimer talked on high energy particles, Lawrence talked on the experimental problem of accelerating charged particles, Alvarez on the design of a linear accelerator for protons, you on the synchrotron and Thornton on the 184-inch cyclotron. That seems to be a very open discussion. In September of the same year in New York, at the APS meeting, the three major topics were cosmic ray phenomena, theories of elementary particles, and the design and operation of accelerators for nuclear particles and electrons.

McMillan:

Who presented that?

Weiner:

You were on the program I think at the New York meeting. This was not a special symposium but there were invited papers and your paper was ďThe Resonance Acceleration of Charged Particles.Ē Dick Crane followed with a paper on the racetrack. You ended up, the abstract of your paper ended up, with a statement that ďThere will also be a discussion of future possibilities leading to the eventual attainment of the billion volt range.Ē Do you recall that particular meeting?

McMillan:

No. The July one I remember pretty well. At this meeting at Berkeley, I remember the talk which I gave, and I told about Veksler and about other people who had had ideas similar to phase stability. I remember telling about Veksler and some others who had thought of a similar thing to phase stability before, and I said, ďAll I can claim is that I am the last independent inventor of phase stability, because now it is published and widely known and nobody can have the pleasure of inventing it again.Ē I remember that statement made. And the meeting in New York, vaguely I remember, I think there were 40 minute papers, and remember there was a symposium at which questions were asked, but the exact content of what I said, thatís lost to me. Certainly, speaking of a billion volts does not mean the specific Bevatron design. It was some statement in general of what kind of problems one would have to solve to reach that energy.

Weiner:

In one sentence, you used these words Ė ďpossibilities leading to eventual.Ē It reads: There will also be discussion of future possibilities leading to the eventual attainment of the goal.

McMillan:

That was pre-Bevatron. If the Bevatron design had existed, if Iíd had in my hot little hand that blueprint of Brobeckís, I would not have said it that way.

Weiner:

Well, did you keep the notes or whatever you used for this paper? The only published record we have of it is the abstract submitted beforehand.

McMillan:

Iím afraid not. Iím not normally in the habit of writing down papers to present at meetings. Iíve been in the habit of making outlines, which would be perhaps one page, with little numbers in red circles indicating where the slides will go, and that would be all there would be, and few if any of those ever got preserved. It would be the kind of paper thatís gotten ready in time for the speech, and then gets discarded afterwards. The typical notes I would have for a talk of that kind would be one or maybe two pages, with one line indications of topics and little numbers in red circles, showing where the lantern slides go, and Iíd just run through this.

Weiner:

Were you at ease as a speaker?

McMillan:

Oh yes. I was quite at ease as a speaker. Still am. Some things I donít like. I donít like after dinner speeches. I donít like to be expected to give a polished presentation with the proper quantity of wry humor and so on which is expected of an after dinner speaker. But when it comes to presenting a technical subject, that is no problem at all. The only essential is to know what youíre talking about. If youíre trying to talk about something that you only half understand, that can be very awkward. But if I have a topic which I know reasonably well and I have my notes in order so that I will not skip some important point, then I have no problem at all.

Weiner:

What about time limits?

McMillan:

Yes, Iím pretty good at that. To one who has been a professor for many years and who is used to the academic 50 minutes, this is almost automatic.

Weiner:

Let us get back to that meeting at Berkeley in July, the symposium on the production and use of high energy particles. The report by Darrow says that there were 500 persons being crowded into a room seating 380, others could not even enter, and he describes it as ďan excellent symposium attracting by far the greatest attendance hitherto recorded at our meetings on the West Coast.Ē Apparently this was really the first postwar APS session at Berkeley. Do you have any particular recollections of the atmosphere of it and the kinds of discussions?

McMillan:

All I remember was, it was a very interesting and enthusiastic meeting, on topics that were new to most of the people there. I remember that Karl Darrow, after my talk, said that he did not like the tern ďphase stability.Ē He didnít think it had a very euphonious sound to it. I said something like, ďWell, how else would you say it?Ē He thought a while and said, ďI suppose thatís about the only way you could say it.Ē I remember, thatís an odd little thing, Darrow was always very conscious of the sound of words and how things were to be said.

Weiner:

Heís also very familiar with Greek, and is concerned with the roots of words.

McMillan:

Once somethingís been made into English, itís no sin to mix Latin and Greek roots.

Weiner:

I wanted to ask how the synchrotron was named.

McMillan:

Thatís all in the letter. I was thinking that my model of the stability of phase was very much like the way a synchronous motor works, and I thought of this analogy with the synchronous motor, and so I made this name. That was the way it came about. Of course, ďsynĒ is ďwithĒ and ďchronĒ is ďtimeĒ, so it means matching things in time. Itís a quite legitimate Greek-derived word, and the ending ďtronĒ, which was originally introduced at the General Electric Co. in Schenectady for a vacuum tube, comes from a Greek ending meaning a device or something that does something. I had thought of this in connection with the synchronous motor, which has the same property of locking into phase, and yet if you pull it too far out of phase limits, it slips out of synch, as we say, and this type of behavior I thought was an apt analogy.

Weiner:

Itís direct enough. This was something on your own, something you thought about or did you discuss it with others?

McMillan:

I didnít discuss it with anybody. Going back, I didnít discuss neptunium and plutonium with anybody either. Those were also my own.

Weiner:

On the initial performance of the 184-inch, was that marked by some kind of celebrations here?

McMillan:

I believe we had a celebration on that occasion. I think we must have.

Weiner:

At the same time, the field, as we indicated, was developing rapidly elsewhere, with other large machines being built. The conferences starting in Ď46 reflect the interest in it. Did you start getting involved nationally yourself more then you had previously, in other conferences, not necessarily accelerator conferences, so-called, but conferences on experimental physics? The Rochester ones didnít begin till Ď50, but prior to that.

McMillan:

Well, the first international conference held outside the United States that I ever attended (some meetings in this country were called international, and Iím not sure I would have recorded that fact) — was in 1949. It was a conference held at Basel in Switzerland and Como in Italy, a two part conference, in which the participants moved bodily from one site to the other in the middle of the conference. That was a really great conference. I gave a paper there on high energy accelerators.

Weiner:

What was the focus of the conference, was it specialized?

McMillan:

No, it was not specialized, but it was in physics and it was aiming towards the particle physics aspects. But one of my impressions of that conference was the fact that as a human event, as representing the getting back together of European physics after the devastation of the war, and the mingling of people from many countries, it was a very great event, and I remember many of the human aspects of that. Iím not going into anecdotes on this one.

Weiner:

It might be interesting.

McMillan:

You want this stuff?

Weiner:

Itís a subject Iím very much interested in: how people took up physics again in various places.

McMillan:

Well, remember certain general impressions as to how European physics was at that time. For instance, was very much impressed with what the Italians were doing. Of course the meeting was partly in Italy, but it was very noticeable that Italian physics was really building up in a very active and enthusiastic way. The Swiss themselves had had a steady pace of physics through the years without any very exciting ups and downs. It was like the general political level of Switzerland, they always keep to the average path. The English were building up. There was a little bit of a revival in Germany. The Germans at that meeting were a fairly depressed group, as remember them now. The French were keeping to themselves, the French being the most obviously nationalistic and parochial as remember, they were always together, always speaking French, and they were always reluctant to speak other languages. The Germans and the Italians were quite happy to try to speak in English. Most of them were pretty good at it, as a matter of fact.

Weiner:

Were there several official languages, or was it English?

McMillan:

I suspect English may have been the official language. English was what was mostly spoken. The talks were all in English, as I remember. It was a very interesting experience to go into a place which was just a few years out of a devastating war, and see how they were coming along, and particularly I remember being impressed by the Italians, and of course it did work out that way. Italian physics is now flourishing. Well, one anecdote.

Weiner:

At least.

McMillan:

I will tell one anecdote. When I was at Basel, I was talking to Professor Huber. He gave a dinner party. He was one of the leading physicists from Switzerland, from Basel where the first half of the meeting was. And at this dinner party he was saying, ďHere in Switzerland, we organize things very well. All the facilities are made available for the visitors and everything goes like clockwork, beautifully. When you get to Italy, youíll find things are less organized. Nothing is going to be arranged right. Yet the people will be so hospitable that youíll love it there.Ē He was a little sad about this fact, that the Swiss, for all of their careful efforts in organization, still ended up not making as good an impression as the Italians. So he told this little story, a little bit sad about it. Huber, by the way, was a very fine man. He always sent me a Christmas card every year and his signature is a perfect sine wave. It is the most illegible signature of anybody that I can think of right now, a perfect sine wave. He died last year. Well, so we went down to Como.

We went on a train, and we got there at dusk, and at the station there were a number of buses which were assigned to various groups of people to take them out to hotels which were scattered around the countryside. Since it was a fairly large conference, there wasnít enough hotel space in Como itself. I was with a group of about 20 people assigned to a hotel up on the west side of the lake, at a place called Menaggio. So we went up this little narrow road, along the lake shore, passing the place where Mussolini had been finally captured and hung by the heels. By the time it was pretty thoroughly dark we were at Menaggio, at this luxurious hotel set way back from the lake, with a huge yard in front. We walked up the front walk, got into the hotel, and we had one person who spoke Italian in the whole party, and that was Placzek. Placzek was a really remarkable man. He was one of the finest people I have known. He knew all languages, as far as I could find out, all necessary languages.

So he was delegated to go to the front office and introduce our party and get us moved in, which he did, and he found out that the arrangers of this situation had left out one essential thread. They had not notified the hotel we were coming! Well, there we were. And what happened then was that the hotel management made a great effort, and by moving people around and finding a few empty rooms, got us all shoe-horned in there for that night, not only furnishing us an interesting story to tell for the rest of our lives as Iím doing now, but also showing how good they were at improvising. It was the perfect example of just what Huber had been saying, and we did end up with a warn feeling toward the Italians. The next morning Placzek and said, ďLetís get out of here, its too far away anyhow.Ē

Weiner:

Itís a great distance from a conference at Como—

McMillan:

Oh yes, itís too far away for attending a conference. So we paid our bill for the night, got our bags out, and got on one of the lake steamers. One of the things they did at Como was that all public transport in the city was free to all participants in the meeting. We had a pass on everything. We got on this lake steamer, went down to Como, and wandered around the town, looking for a hotel. So we were improvising at that point.

Weiner:

The ride from Menaggio to Como is a great ride—

McMillan:

Did you drive up to Brunate? Thatís on the east side — its just east of town, up a hill, with a funicular. A hill on the east of town with a hotel on top. Thatís where I ended up. I spent one night in a hotel in town, which Placzek and I found, then the next day we found that Fermi and some other people were in Brunate and we stayed there for the rest of the time — you ride a funicular up and you get this marvelous view.

Weiner:

Let me get to another topic, which reminds me of the scrapbook we were looking at yesterday, the question of the Japanese cyclotrons in the postwar period. Briefly reviewing it, Sagane had been here in Ď37, Ď38 — and spent almost a year and had been, I guess, a working member of the laboratory—

McMillan:

Right—

Weiner:

— then went on a world tour of other cyclotron facilities, his letters to Ernest Lawrence are the best possible account one could want of what was going on. They are in the collection here.

McMillan:

Really? I havenít been through that Lawrence collection.

Weiner:

Then when he went back there was subsequent correspondence related to the construction of the cyclotrons in Japan. There are two things I want to raise — one is, what you knew of the story of the destruction of the Japanese cyclotrons by the military, thatís an established thing. Whether you were aware of the discussions taking place here with some sense of outrage that this was done. Lawrence apparently was disturbed by this.

McMillan:

We were all disturbed. I donít recall any specific occasion of discussion, but I know that I agreed with him — I wasnít in the direct line of communication there, Lawrence was. Earlier you mentioned Sagane. I think the important person for the cyclotron was Yasaki, who came later specifically to learn about building cyclotrons.

Weiner:

Well, letís talk about that. The clipping that we looked at before, although it is undated and we donít know when it appeared, is presumably early postwar and it relates to some photographs that are reproduced here, taken in 1940 in Berkeley. This is a photograph of the Japanese scientists who met with you and other Radiation Laboratory staff, and the story that theyíre trying to tell in this newspaper headline, ďNips Attempt to Learn Atomic SecretsĒ, is that you gave them misleading information. Letís get into that story. Do you recall the visit?

McMillan:

Of course I remember the visit. They gave us a fine party in a Japanese restaurant in San Francisco. We gave them prints of the cyclotron and told them how to build it. I didnít give them any misleading information. Thatís something the reporters put there! ďAttempted to ferret out American secrets in atomic research.Ē In 1940, there was the beginning of secrecy on the uranium work, and we certainly were careful not to discuss that. But as you know we had been publishing already, early in 1940. I even referred to some Japanese work in one of those publications.

Weiner:

You say you talked specifically about the cyclotron. There was one under construction at that time, according to Saganeís letters.

McMillan:

Thatís right, there was, and I think it was just to learn more.

Weiner:

It was a continuation of what was going on. Who was in the group?

McMillan:

Well, there was Iimori, Watanabe, Takamine, Lawrence, McMillan, Yasaki, and Van Voorhis. Yasaki is the one who had been here before.

Weiner:

Now, you started to point to the drawing on the board.

McMillan:

Oh yes, thatís the 60-inch.

Weiner:

As far as your recollection of this stimulated by the picture itself, this was a normal visit to learn about the cyclotron. No special security measures were taken?

McMillan:

I believe we were supposed to be careful not to talk about any of the uranium work, which was already becoming somewhat secret. But there was no restriction on talking about cyclotrons.

Weiner:

Maybe the newspapers garbled it.

McMillan:

Yes.

Weiner:

When in your experience did relationships with Japanese physicists in your field begin again after the war? When was the first contact you had?

McMillan:

I donít remember that. Iíve never been to Japan. Weíve had many Japanese visitors come to the Laboratory. They must have come fairly soon after the war was over. There was no rancor left from the war. As soon as it was over, it was over.

Weiner:

You mentioned that Sagane came postwar.

McMillan:

Yes.

Weiner:

Let me get to another question we havenít talked about yet. We were talking about your teaching role. The laboratory was still related to the university. This was the period in the postwar years of the loyalty oath controversy.

McMillan:

Yes.

Weiner:

The question is, whatís your recollection of that? How did it affect work in the laboratory and in the physics department of the university?

McMillan:

That was a very dismal period. It was a very unhappy period. There were a lot of high feelings among people, good friends barely spoke to each other. I tried to stay out of that controversy as far as possible. I never thought the oath was a good idea. I didnít myself object to signing it, but I never thought that was a valid way to make people loyal. So I stayed out of the arguments. I had good friends on both sides, who barely spoke to each other, on account of highly diverging and strong opinions on the subject.

Weiner:

Did people put pressure on you to take one side or the other?

McMillan:

I donít think so. I donít think anybody put pressure on me. I would always make it clear that I wasnít going to take sides.

Weiner:

That doesnít mean you wouldnít be a target.

McMillan:

I know, but no, there was no pressure that I remember, no strong pressure anyway.

Weiner:

What about the effect of this on work in the physics department and in the laboratory?

McMillan:

It had a very dampening effect and a number of people left on that account.

Weiner:

From what I understand of the period, the major problem was that a large number of theorists —

McMillan:

Theorists were most affected because theorists tend to be more liberal in their politics, liberal ranging on into radical, and so the conflict would be mostly between the theorists and some experimenters who were more on the political right. Lawrence himself was very much on the political right. He was a strong supporter of the oath.

Weiner:

Even if it would mean, as it subsequently did, that Berkeley became impoverished as far as theorists went?

McMillan:

I think he would say ďWe didnít need those people anyhow.Ē

Weiner:

Would he have believed that, or said it as a political statement?

McMillan:

Iím not going to put words in his mouth. My feeling is, as to what he would be thinking — that if somebody wasnít willing to declare his loyalty to the United States, he just didnít want to have him around.

Weiner:

He saw it in those very simple terms.

McMillan:

Thatís right. Lawrence thought in very simple terms, and was very straightforward.

Weiner:

With the exodus of the theorists, I saw a letter stating that the problem then of re-attracting theorists to Berkeley was difficult. I donít have a feeling of a date when the tide turned, but it must have been a long period of time.

McMillan:

Yes, it was a number of years.

Weiner:

Somewhere in the mid - 1950ís?

McMillan:

I would rather not try to guess at dates. Iíd have to look at the records.

Weiner:

Now, weíve tried to characterize this whole period. Weíve talked of accelerator development a little bit, not much about the scene outside the university. Just now weíve talked about the atmosphere at the university. Letís get back to you. Iím assuming that youíre spending about six hours a week teaching, in direct contact with students, and working on the design, construction and use of accelerators. Youíre playing a part in conferences. Was there anything else that you were doing? Did you have advisory or consulting positions?

McMillan:

Not in that period, as I remember. I donít think I was.

Weiner:

Not prior to 1950?

McMillan:

Well, I became a consultant with Lawrence when he started his color television business. Then in 1954 I became a member of the General Advisory Committee to the Atomic Energy Commission. Previous to those, I wasnít doing at least any organized consulting. I remember one thing I published then. Just to go back to a slightly earlier age, I told you that in 1940 I was working on the long life radioactivity of beryllium, and left this in the hands of Sam Ruben, who continued to follow the decay of these radioactive samples that I had made, until he was killed in an accident in the laboratory. When I returned in 1945, I got all these papers together, and prepared a paper on the discovery of the long life activity of beryllium-10. Thatís in the publication list.

Weiner:

That was published in 1946.

McMillan:

After this I made some measurements with some collaborators to determine the halfólife of this material, which was published in 1947, and the interesting point here is that in calculating the result, I made a rather stupid blunder. I left out a factor that should have been in that calculation. I just left it out by carelessness. So this went into the literature with a value of 2.5 million years for the half-life. And this sat there through all these years, up until the present. Apparently nobody ever noticed the mistake. It turned out that the half life of beryllium-10 is a rather important thing for cosmology, because beryllium-10 is formed in the cosmic rays out in space by collisions, and the decay of this material gives some sort of measurement of how old the cosmic rays are. So it became an important quantity, and other people got interested in it, and they re-measured it and found a value which disagreed. And just this year, when one of these articles appeared in the Physical Review Letters, it gave a value of 1.5 million instead of 2.5 million years. I looked at my old data and the paper I had written 25 years ago, and found this mistake, and by correcting that, my value comes down to 1.7 which, within the margin of error, is in good agreement with the new value of 1.5 million years. So I have now in press a correction of a mistake made 25 years ago. It may be the oldest piece of errata ever published. It will be in the Physical Review in December. [1972]

Weiner:

Nobody ever pointed it out?

McMillan:

Nobody. By looking at the paper, itís quite easy to see where the mistake is made. The data are there. Anybody could have discovered it. Nobody did. And I had to find it myself, when was presented with a disagreeing value. So Iíve sent around preprints, and this will appear in the December issue of the Physical Review, a correction of a mistake made 25 years ago. I suppose I should be terribly embarrassed about this, but nobody has tried to embarrass me about it. When I talk to people about it, they say, ďWell, anybody could make a mistake,Ē and then they say, ďThatís very nice of you to correct it.Ē Well, thereís nothing else I could do but correct it, you see. Itís not a matter of whether I want to or not. If youíve made a mistake, and if itís something important to know, youíre duty bound to publish the correction.

Weiner:

Looking through the list of your publications in this very busy period weíre talking about, there are a number of things youíve done in collaboration with other people, cross-section papers and a paper on the angular distribution of neutrons from targets bombarded by 190 MeV deuterons.

McMillan:

This was work on the 184-inch cyclotron. It was a sequence of somewhat related things. You might call it the primitive experiments one does with the new machine when itís first turned on, and I think the cross-sections we measured there were things which were important because they were going to be useful as monitors. The neutron measurements demonstrated what we call the stripping process by which a deuteron is split, separated into its components, one neutron and one proton, by an impact, and these particles then proceed more or less straight forward in the direction of the incident deuteron, That was an interesting thing theoretically. Serber was doing the theory for that. So there was a sequence of publications there. You say I was collaborating with other people; when working on large equipment one tends to have collaborators. Not many one-man experiments were done from now on in this field.

Weiner:

How much of your time was involved in this?

McMillan:

Oh, quite a lot of time. It takes quite a lot of time to make those measurements.

Weiner:

This was all in addition to the design and other work.

McMillan:

Right.

Weiner:

You have here a paper on the application of nuclear physics in biology and medicine. Iíd like a reprint of that study because it is not generally available. It was published in a thing called Oral Surgery, Oral Medicine, Oral Pathology. Was this an invited paper? [A reprint is attached]

McMillan:

Oh yes. I was invited to a special seminar. Thereís a group of dentists in the Bay Area that has annual seminars, usually in some highly scenic spot, and I was invited that year to attend the seminar and give a paper. Thatís the paper I gave there. Itís a general account of possibilities for the use of radioactive tracers. The meeting was at the Ahwahnee Hotel in Yosemite. It was a very pleasant, semi-social, but basically serious event. I even learned something about dentistry and the development of teeth there, because I stayed for the whole seminar. I gave my paper, but listened to the other papers too.

Weiner:

I notice that you reported on the initial performance of the synchrotron at the APS meeting in Berkeley held on February 3 to 5, 1949. The first full energy beam was obtained in January of that year [Jan. 17]. The first synchrotron beam was found in December of the preceding year [Dec. 14].

Weiner:

You started on it when you got back in the fall of Ď45, so its a three-year period?

McMillan:

Approximately three years was the period from the start of design to first operation.

Weiner:

Iíd like your comment on that sequence of papers, that is the production of mesons by X-rays.

McMillan:

That was the initial work with the synchrotron, the electron synchrotron.

Weiner:

I see, those were the first results from it.

McMillan:

Yes. One of the earliest things that was done was to observe the production of mesons.

Weiner:

These were the first machine-made ones?

McMillan:

No, the first machine-made masons were made on the 184-inch cyclotron. That would be in Ď48. That was done by Gardner and Lattes.

Weiner:

How did that lead you to the paper on the origin of cosmic rays, or did it?

McMillan:

Well, no, the origin of cosmic rays was something quite unrelated. That came out of conversations with Winfield Salisbury, who was around at that time. Salisbury had been at the laboratory before the war as a high frequency expert, and he was back for a while, and he had some ideas, and I worked these ideas up and made some calculations which people thought were interesting, and I published it. This was an example of something I mentioned to you previously, that I worked on various little problems from time to time, most of which were not published. This was one that was published because people seemed to be interested in it, but the mechanism which Salisbury had proposed and which I worked out was put forth merely as a hypothesis. Some of the calculations in it were quite valid and useful and had applications in other fields, but there was no experimental work done on that here.

Weiner:

I want to ask about one other thing, and that is relating to the series of events culminating in the Nobel Prize. We talked about the work that was done essentially around 1939-40. The prize was awarded in 1951.

McMillan:

Right.

Weiner:

Did you have any inkling along the way, in a personal sense, that that work youíd done was of Nobel Prize stature?

McMillan:

Well, naturally the thought would occur to one. Certainly at the time, in 1940, I was not thinking of that at all. But as it developed during the war, when nuclear energy became a very important thing and the whole field developed into a big field, then it would appear that the very beginning of it would be of that caliber. So somewhere along the line, I was certainly aware of that possibility. Of course I had nothing to do with the awarding of the prize. It is not done that way. One does not apply. This is done by people who make nominations, and who are not even supposed to tell the candidates that they have nominated them. Sometimes Iíve seen that done, but I consider that improper procedure. That raises peopleís hopes that may not be satisfied. Iíve nominated a number of people for the Nobel Prize.

Some have got it, some havenít, but Iíve never told those individuals. Anyhow, various of my friends would say, ďDonít you think you might be in line for the Nobel Prize?Ē, and usually Seaborg was counted too. There were inklings along there. There was one thing which might have led into possible thinking along that line, in connection with the Basel-Como meeting that spoke of. I was invited to come to Stockholm. I arranged to stop there on my way to Basel; I actually stopped at Copenhagen first and gave a seminar.

I also went to a number of other places. I had a little seminar, a little talk I was ready to give on the high energy accelerators and some of the new observations that were being made. This was about the time that the neutral pion was being discovered in the laboratory, that is, the process of formation of the neutral pion was being tied down by laboratory experiments, using the l84-inch cyclotron, and was prepared to tell about that work. It wasnít my own work — the chief persons associated with it were Bert Moyer and Herb York. So I stopped at Copenhagen. I had dinner at the Bohrís house in Copenhagen, and gave my seminar to perhaps the smallest audience that Iíve ever given a formal talk to Ė I think four — at the Bohr Institute. This was in September, it was vacation period, but Bohr himself and Jacobsen and perhaps two others were there.

Weiner:

Perhaps Rozental?

McMillan:

No use giving names because those didnít register. Then I went to Stockholm and gave a talk before quite a large audience there — the person I was with there was Manne Siegbahn — at the Nobel Institute. I had a good audience there. Then I went to Uppsala, where I met Svedberg, and gave a talk there. Siegbahn and Svedberg I knew from before. They had visited here. Before going to Scandinavia, I had been in England. Iíd visited several places there and had done the same thing there and had seen laboratories. But the fact that I had received a special invitation to come to Stockholm could be taken as an indication, because I know that the people of the Nobel Foundation like to have a personal contact with any individual before heís given the award.

They donít like to do it out of a completely blue sky. So I think perhaps this invitation indicated they were looking me over, to see whether I would do honor to the prize. There were little inklings like that. That was in Ď49, two years before the award. At the meeting at Basel and Como, some individuals had spoken to me in a way indicating that maybe there might be something cooking there. I suspect that a nomination had been made already. Then when the actual award came in Ď51, there were the usual strong rumors running up to a few weeks before. In fact, in that case I had a strong rumor in the September preceding the award, from a Swede who was visiting this country. So it didnít come completely out of the deep blue sky.

Weiner:

That would mean that from Ď49 on you had suspicions.

McMillan:

Yes. There was an individual at this meeting, and I even remember who it was, but Iím not going to put it down here — who said something to me indicating that I had at least been nominated. The rumor was personal rumor to me only. It wasnít a rumor that spread around. There was this man that spoke to me and said some thing to me which indicated that he thought might be getting it.

Weiner:

Thatís not a rumor, itís a tip.

McMillan:

Tip — itís a tip, right.

Weiner:

Came time of the announcement, how did it catch you? How did the news reach you?

McMillan:

A newsman that we knew called me up and tipped me off, a couple of days ahead of the official announcement. When the official announcement came, my wife and were somewhat primed for it. When somebody gives you a tip, he never says ďThis is certain,Ē he says, ďI have a strong reason to believe that this will happen,Ē or some such statement, so when it comes, youíre not taken completely by surprise. I prefer it that way myself. The total surprise that catches you in some awkward moment which the newsmen seem to love to write about, does not appeal to me. I was quite happy to be a little prepared for it when it came. When it came, that was the real thing and nothing ever matches it.

Weiner:

What was your response? Thinking back on it now.

McMillan:

Well, I was very happy. Thatís all I can remember. Of course I was very pleased with it.

Weiner:

The immediate reaction at the laboratory Iím sure was—

McMillan:

Oh yes, there was a tremendous reaction at the laboratory.

Weiner:

The next step on something like that, once the initial elation is over, is I imagine ďMy goodness what am I going to say?Ē Were you concerned about your Nobel address? The time difference is only six weeks or so.

McMillan:

No, the formal Nobel address, being a scientific presentation, is straightforward and a very simple thing to tell. Youíre also supposed to give a little talk at the banquet, and my talk at the banquet I actually wrote down the day before I gave it. It was very short and was a thing about the international aspects of science and how the Nobel Prize represents the cooperation between nations — something like that.

Weiner:

Who from here was at the ceremony?

McMillan:

My wife went and Ernest and his wife went. Ernest had not gone to Stockholm at the time of his award because that war was on and sailing across the ocean wasnít very safe, so he was given the actual presentation here in Berkeley. The Swedish consul at that time put on a little ceremony and gave him the medal and the documents and the money. So Lawrence went along. Then he delivered his Nobel lecture belatedly. It hadnít been given before.

Weiner:

Was it pretty much a festive occasion?

McMillan:

Oh, that was a very festive occasion, but Iím not going to give a description of it right now. If you come back I could do it another time. My wife has written it up in considerable detail, and I think sheíll let you have a copy of her account.

Weiner:

Would you like to go on?

McMillan:

I would prefer not to go on this afternoon. This session has opened up more gaps in my memory, and gaps that are easily filled. Weíre into the modern period of documentation where everything is down. You just have to find it. It is just as hard for me to remember dates in this period as the older dates, and the documents are more complete but harder to get hold of, harder to find.

Weiner:

I have done research on the earlier period, but only overall research on this later period — I will have to get in a little more detail on these things too. Letís stop here.

McMillan:

Letís stop here.

Session I | Session II | Session III | Session IV