NIELS BOHR LIBRARY & ARCHIVES / TRANSCRIPT
ONE PHYSICS ELLIPSE, COLLEGE PARK, MD 20740 • (301)-209-3177 • NBL@AIP.ORG
J. B. Taylor – Session I
February 3, 2007
Interviewed by: Kai-Henrik Barth
Location: Wallingford, United Kingdom
Transcript version date: December 18, 2024
DOI: https://doi.org/10.1063/nbla.joom.ryrg
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Abstract:
In this interview, J. Bryan Taylor discusses his career in plasma physics. Topics likely
discussed include: ZETA reactor; Atomic Weapons Establishment (United Kingdom);
Culham Laboratory; plasma physics; the Taylor state; ballooning transformation.
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Barth:
I would like to start out with a question about your early interest in science. Could you
tell us a little bit about your background and science training before you came to the
University of Birmingham?
Taylor:
For as long as I can remember I’ve always been interested in science, or at least in
technical things, such as they were when I was a boy. I grew up during the war, when
there was lots of technical excitement such as jet-aircraft, weapons, and radar eventually
— when we knew about that. Of course, initially it was secret. One of my earliest
memories is getting up one morning and finding little strips of metallic foil in my garden,
which I later found was what we called “window” and the Americans later called “chaff,”
which was designed to confuse enemy radar. At that age I couldn’t work out what it was,
[Laugh]. Of course, all my hobbies were technical: I had all the usual Meccano-Erector
sets, train sets, model aircraft and so on. I went to school during the war to Oldbury
Grammar School, (near Birmingham) which gave me a very good scientific background
for the time. I did rather well at school. I didn’t do so initially, but when I got to about
the fourth form (that would be an age of about fifteen), I suddenly blossomed and
became top of the school in sciences and got some of the best exam results in Maths and
Physics in the country. I was then encouraged to go to the university, something I had
not contemplated earlier. I was initially going to go to Cambridge and indeed did win a
very prestigious Exhibition, which is like an undergraduate fellowship, to Kings College.
There were only about four of those awarded in the whole country, so it was quite an
honor. But unfortunately I couldn’t take it up because, due to lack of foresight on the
part of me or my tutors, I had not studied Latin. And in those days Latin was a
requirement to go to Cambridge, as indeed it was to Oxford, and for many years
afterwards it was still a requirement. So, at a late stage, I switched and went to
Birmingham University, which was of course near my home, and so the question of
accommodation, which was very difficult at that time because of the post-war situation,
was solved. I could stay at home. I remember I cycled about ten miles to the university
everyday, [Laugh] sometimes feeling very cold. At Birmingham I studied under Professor
Rudolf Peierls. He was quite eminent then, and indeed was, with Frisch,[1] the originator
of the atomic bomb. It was quite an honor to work with him. He had a very small
department by modern standards. I think there were only about eight or nine students in
his Mathematical Physics department. Such was the prestige of his department; one had
to spend a year in another department before he would take you on. [Laugh] He was
very selective. So I spent my first year doing mathematics, rather than physics, with
Professor G.N. Watson, who was famous for his work, and for the standard textbook,
on Bessel Functions. He was, at that time, already quite an old man; he still wore an oldfashioned winged collar and he’d obviously given his lectures many times before. They
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were very stereotyped. I found that first year rather dull, partly because Watson was not a
very exciting figure, partly because many of the other mathematics lecturers had either
not returned from the war or had not yet reorganized their courses. Furthermore,
because of my studies to get into Cambridge, I’d done a lot of the first year syllabus as
preparation for the exhibition-cum-scholarship exam at Cambridge. So, I was very
pleased to move over to Peierls’ Mathematical Physics Department where things were
much more advanced and much more rigorous. He had reorganized his department and
had several eminent lecturers there. I very much enjoyed it, but I have to say that by the
end of the third year the work was getting rather difficult. [Laugh] Peierls was known to
set an exam in which nobody finished a single question, [Laugh] but he gave marks for
effort, as it were. Anyway, I graduated with first-class honors and all the rest of it. I was
top of my year and I got a prize. At that point I decided I would do my national service
and went into the Air Force, although I possibly could have put it off further.
Barth:
Was there a draft?
Taylor:
There was a draft, but if one was continuing studies the draft was deferred, and many of
my contemporaries did defer it. By the time they became eligible again the draft had
ended and they actually avoided it all together. But, for one reason or another I thought I
would do it. So I went into the Air Force for two years. I enjoyed much of my time in
the Air Force, mainly because I got seconded, as an Air Force officer, to a civilian
research unit at Bomber Command HQ. This was a small unit attached to Bomber
Command. The whole group was only about ten people and it would have been about
half military and half civilian. The leaders were civilian but they had under them people
like myself who were military, I think to make up the numbers. I presume they found
civilian recruitment difficult. One of our tasks was analyzing wartime bombing patterns.
We discovered, for example, a systematic error in raids that had been guided by Gee-H,
which was a ground-based radar system that measured distance. I at least attributed this
to the fact that the width of the channel wasn’t quite what one thought it was!
(Incidentally, I subsequently discovered that Freeman Dyson, who I later met at the
Institute for Advanced Study, had worked in this Operational Research Unit during the
war itself. In his autobiography he writes very bitterly about his time there.[2] He did not
enjoy it obviously. I have to say I did. Of course, my circumstances were very different
to his. The war was over and it was all rather fun). When I came out of the Air Force I
had to think what to do next, and after some uncertainty, I must admit, I went back to
Birmingham University to do a Ph.D.
Barth:
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What was the uncertainty about?
Taylor:
Whether I should return to University, or get a job! By that time I had decided that I was
going to do scientific research, but I could do that in industry. I would have liked
somewhere like Bell Telephone but such things didn’t exist in Britain. But, there were
places like Marconi, which has now completely disappeared, and the General Electric
Company (UK), and so on. These were companies doing research, in electronics mostly,
and I could have joined them. There were also government labs, which had a very high
reputation because of their work during the war. They included places like Radar
Research Establishment in Malvern, where I actually went as a summer vacation student,
and places like Farnborough that did aeronautical research, and so on. But in the end I
decided to return to University and take a Ph.D. This was mainly because I had the
impression that I needed a Ph.D. I don’t really know why, because two of the directors
that I later worked under at Culham (Adams and Pease) didn’t have a Ph.D. Anyway, I
decided to do my Ph.D. and I thought I’d go back to Birmingham because I knew it. But
by that time I was married and in those days there were no grants for married people.
Being married when you were a student then was severely discouraged by making sure
you didn’t have enough money. [Laugh] But I was able to get a grant from, of all places
the Navy, to do research at Birmingham. But it was not in theoretical physics. It was in
experimental solid-state physics, which was just beginning to be an important subject at
that time. I took this up and I did three years, doing mostly experimental work. But I did
as much on the theoretical side as possible, and seized the opportunity to go to the
Mathematical Physics Department whenever I could. But I was not technically enrolled
in that department. I was in what was called Electron Physics.
Barth:
How was it working with Professor Alfrey, your supervisor?
Taylor:
Working in the Electron Physics Department was a rather peculiar experience, to be
quite honest. The professor in charge was Professor Sayers. He was famous as one of the
trio of Randall, Sayers, and Boot, who had invented the cavity magnetron (at
Birmingham). There was a plaque on the wall with a quotation from an official American
war historian, describing the Magnetron as “the most valuable cargo ever brought to our
shores.” Sayers and the others received a government grant for their work; I think the
three of them shared 30,000 or something. It was a ridiculously small sum of money, but
in those days I suppose it was worth a lot more. Sayers was a bit of an eccentric; he was
very pleasant but he was almost a recluse. He said, “Good morning,” to me when I
arrived and he would say “Good morning,” to me in the corridor, but the only times I
formally had a discussion with him was when I arrived to discuss what I might do, and
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when I sat my final examination. In between, I hardly ever spoke to him. [Laugh] In any
case, he didn’t know a lot about solid-state physics. He was an electronics man, and I
was supervised by Graham Alfrey. And again, that was slightly peculiar. Professor Sayers
took us into a room, a lab, and said, “Well, here’s your lab.” It was totally empty except
for the standard equipment, like workbenches, and power points. He said, “You can
have 500 to buy equipment, best of luck,” and disappeared. [Laugh] Graham and I
worked on electroluminescence, all rather amateurish by modern standards. It certainly
wasn’t big physics, since the two of us were doing it [Laugh] in a lab on our own, for a
few hundred pounds. But it was quite enjoyable and I learned a lot. Eventually I got my
Ph.D. Now comes the great decision of where am I going to make my career, in
industry, government service, or the university? I decided against industry because I
knew I would be no good at commerce; and by then I had acquired a somewhat
jaundiced view of the university. Not because I didn’t enjoy it, I did, but I got the
impression that the university was a mixture of a few eminent people, like Peierls, and a
goodly number of rather mediocre people who were just, almost, filling in time. Some of
them were elderly and were indeed filling in time, but others seem to have gone into the
academic world mainly because it was an easy life. My supervisor, Graham, admitted this.
Once I asked, “Graham, why have you chosen to do this?” And he said, “Because I
don’t want [to work] anywhere where it’s stressful, and I can have a comfortable life in
university.” I thought, “Well, I don’t really think that I’m in this (near) Nobel Prize
winning category of Peierls and the others, [Laugh] but I certainly think I’m above the
level of these people who are just filling in time.” So, I settled on government research.
So, where do I go? I contemplated two or three of the research establishments: one was
in Malvern, the Radar Research Establishment, which I already mentioned and had some
experience of as a vacation student; but the main ones, which were very much in the
news at that time, were Harwell and Aldermaston, which were both parts of the United
Kingdom Atomic Energy Authority. (The UKAEA was the equivalent to the AEC, if
you like.) I was interviewed for all three. I forget why I didn’t choose Malvern, the radar
one. Possibly because the work wasn’t very theoretical. It was in electronics, and
electronics in those days was mostly a practical subject. (Incidentally, I had my first
experience of a computer there. It was made with vacuum tubes and filled an aircraft
hangar, and I’m afraid that put me off computers for life.) [Laugh] So, it came down to
Harwell or Aldermaston. My recollections are a bit dim, but I think Harwell said,
“You’ve been out of theoretical physics for three years, doing an experimental Ph.D.,
and it’ll take you time to get back in,” and so on. And when they offered me a job I got
the impression they weren’t all that desperate to have me, whereas Aldermaston was very
keen to have me from the outset and said, “We don’t hold it against you that you’ve
been out of theoretical research for two or three years. We’re delighted to have you back,
and it’s very exciting work.” They were so keen to have me that before I had got home
from the interview they had been around to my neighbors making security checks.
[Laugh] I’m afraid I’ve always been a bit of a sucker for that sort of thing. I like to say
that flattery will get you anywhere. To be more serious I think it’s a very good principle
to work for people who appreciate you.
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Barth:
You approached Aldermaston and the other labs yourself? It is not the other way around
that they actively recruited at the university level? They needed smart theoretical
physicists.
Taylor:
At that time many places wanted physicists and there was no shortage of jobs. Although
it wasn’t developed in the way it became later, there was the so-called “milk run” where
employers of all sorts, would come and see students. My approach to Harwell and
Aldermaston might have come through Peierls, who had contacts in both places.
Barth:
He suggested you might be looking there because they were looking for scientists with
your qualifications?
Taylor:
He probably did, but it was obvious anyway. It was just an obvious choice once I
decided I was going to take a job in a government laboratory.
Barth:
And Peierls would not say, “You’re so good in mathematical physics you should rather
make a university career out of this instead of working at a government laboratory”?
Taylor:
No, for two reasons. First of all, I was not actually registered as a student of his at that
time. I had been for my undergraduate degree, but not for my Ph.D. I was registered
with Sayers, who as a hermit-cum-eccentric was not the man I was going to go to for
advice about my career. I did, in fact, now that you mention it, discuss it with Peierls. He
expected people to be very good and said to me, “Look, if you want to do academic
research you have to be absolutely sure that you are very good at it. It’s no good doing it
at a lower level because you’ll be dissatisfied.” I have never had too much confidence, so
I suspect that may have put me off a University career as well. And it fits in with the
impression I mentioned earlier, that the university had a few very brilliant people who I
wasn’t sure I could compete with, and a lot of mediocre people I didn’t want to compete
with. With Aldermaston being very keen to have me, they not only started the necessary
checks before I’d even got back home, but they wrote to me immediately and made me
what was in those days a very good offer. It was actually less than 1,000 (or with today’s
exchange rate roughly $2,000) a year. But in those days that was a respectable salary.
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There was also the added incentive that Aldermaston would provide me with housing,
which was very much in short supply at that time. That clinched it and so I went to
Aldermaston in August 1955.
Barth:
Let me come back to this point. Was there any discussion with your peers in the Physics
Department about the advantages and disadvantages of working in a nuclear weapons
laboratory?
Taylor:
No. None whatsoever. At that time it was not the politically hot potato that it later
became. At the time I joined, Aldermaston was a fantastic place. Prior to the creation of
Aldermaston nuclear weapons research had been at various other scattered institutions,
particularly at Fort Halstead, which had originally been for conventional high explosives
research. William Penney had been appointed director of this new establishment at
Aldermaston and was expanding it at an enormous rate. I’ve never worked anywhere
where things changed so rapidly. We used to say that “If you dared to go on leave for a
couple of weeks, when you came back you wouldn’t be able to find your office, (because
so many other labs and buildings had been put up).” Later on this did almost literally
happen to me. I went away and came back and my office had been knocked down to
make a passageway through into yet another new building. I joined the Theoretical
Physics Division led by John Corner, an extremely competent theoretical physicist, who
had been in conventional weapons research and done a lot of very good work on shock
waves. He is almost unknown outside the classified field, because at that time, and even
later, Britain did not have the custom that existed in America, that people in the
universities would have one foot in the academic world, and another foot in the
classified weapons research. In Britain, people were either in one area or they were in the
other, and Corner spent his whole career in the classified area. Corner’s group, like
everything else, was growing rapidly. When I arrived it was like twenty people and then
six months later it was 120 people. People were being recruited so fast, that even with
the rapid building program I’ve referred to, I was initially put in a wooden hut [Laugh]
because there was nowhere else to put me. I quickly moved into the main building and
everything was fine.
Barth:
Did you work directly with William Penney, William Cook and Henry Hulme?
Taylor:
Not at first, later I did work with Henry Hulme. Initially I worked on neutron transport.
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That was supposed to be my area.
Barth:
Using variational methods?
Taylor:
Yes, but neutron transport seemed a bit of a dull subject. So, I took every opportunity to
see what else was going on. It was in that rather unofficial way that I got to know Keith
Roberts very well, and so got into the hydrogen bomb project. That is described in
Lorna Arnold’s book,[3] which she wrote many years later, on the development of the
British H-bomb. I hope it doesn’t sound conceited to say I did make important
contributions to the H-bomb project. But I have never regarded that as my main
contribution in the weapons field. I did other work, of which I’m much more proud, and
which was probably more important. Should I mention this?
Barth:
Absolutely, if you can talk about it?
Taylor:
Well, I can, I mean, obviously it’s a long time ago. Well...
Barth:
You worked on “initiation”?
Taylor:
That’s right. The most important work I did, by far, was on what we used to call
“predetonation,” although it would more properly be called “initiation.” Everyone
knows nowadays (it was classified then of course), that in a nuclear weapon you
compress the core to make it supercritical and then a chain reaction starts and everything
goes off. The crucial point is that you must start the nuclear reaction at exactly the right
moment. It must not start too soon or all that happens is that the imploding system just
gets pushed out again and you get something that would be very nasty to be standing
near, but it isn’t a nuclear explosion in the way that we normally think of it. On the other
hand, you don’t want the core to be compressed and then not be initiated, because it’ll
just bounce out again. Now, one thing that can cause the reaction to start too soon is a
spontaneous fission in plutonium-240, which is a contaminant of 239. That is really what
people mean when they talk about weapons-grade material: it means material that’s got
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sufficiently little 240 that it could be used...
Barth:
Below six percent, essentially.
Taylor:
I don’t know what the percentage is; I must have known then but I certainly don’t
remember now. But the amount of Pu-240 you can tolerate is a crucial factor. Now, the
amount of 240 in the plutonium depends on how long it’s been in the nuclear reactor
that produced it: if you want to have very little 240 you must extract your plutonium
after a very short time and this makes it very expensive. In order to decide how much
Pu-240 can be tolerated, the question is, “How do you calculate the probability of having
preignition?” (The other aspect of getting it to go off at the right instant is achieved by
something called an “initiator”).
Barth:
Polonium-beryllium spheres, and so on?
Taylor:
It was in those days. There were better methods developed afterwards. Let me put that
aside and concentrate on the problem of “How do you calculate the `initiation
probability’?” This turns out to be extremely difficult, because it’s a very involved
process. Spontaneous fission produces a neutron. This neutron might produce daughter
neutrons, but it might just escape. If it produces daughter neutrons they might have a
couple of fissions and then they escape. It’s not enough for the system to be
supercritical. We know it’s that. But, the chain reaction may not start. Or it may go for a
little while and then fizzle out. Only when you’ve built up a large number of neutrons
will it carry on and produce an explosion. To make things worse, whether a neutron
escapes or goes on to produce another fission depends on where it is. If it’s near the
edge it’s going to escape. If it’s near the middle it isn’t, or it might go out and be
scattered back in again. So, it’s a very complicated business. Feynman had made a simple
calculation of initiation at Los Alamos. But this ignored almost all the complications of a
realistic system and Penney, in particular, was very suspicious of the result. There was
therefore a tendency always to err very much on the side of caution and to demand
plutonium which had very little 240 in it, and therefore was outrageously expensive.
(Before I explain my contribution I’d like to make an aside to say that this was the best
subject I’ve ever worked on, because I don’t like reading a lot of literature. There were
only three pieces of literature that I could read on this subject. One was the Feynman
formula that I’ve just referred to. Another was a paper by the famous, or infamous I
[4]
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should say, spy Klaus Fuchs, who had made notes for the benefit of the Russians. I
was allowed, under very heavily controlled conditions, to see these notes from Fuchs.
And then there was a paper written by John Corner, who was my Division Head, which
essentially just summarized the previous two. So, there were three papers I had to read
and then I was an expert on predetonation. That I regard as the perfect subject to work
on.) To come back to this formula. The question was, “Could we do any better?” Well,
I’m very pleased to say that I did. I solved the problem completely and using neutron
transport codes adapted to my theory by a colleague Underhill, we could calculate the
initiation probability in a fully realistic situation very easily and quickly. This was also an
extremely attractive theory intellectually, because it involved time reversal and adjoint
functions, and some nice mathematics which I would be happy to discuss with you, but
isn’t suitable I think for this interview. I regard it as my best work, and it was also
important because it enabled us to go from having little faith in what the theory said
about the chance of predetonation, to really believing we had got it right. This allowed
the plutonium-240 level to be raised. And although everything was cloaked by security,
I’ve reason to believe that this saved the country a great deal of money, none of which
came to me I’m sorry to say. [Laugh] I even believe that it resulted in Britain being able
to sell some extra high-grade plutonium to the Americans in exchange for a rather larger
amount of lower grade that was good enough, so to speak. Whether that’s true or not, I
don’t know. Anyway, it was important work and it established my reputation in
Aldermaston. After that I was allowed to work on what I liked.
Barth:
You also worked on the electromagnetic pulse (EMP) for a while.
Taylor:
Yes, the other major work I did was on what we used to call “radio flash,” but has since
been renamed as the “electromagnetic pulse.” This was the electromagnetic signal
produced by a nuclear explosion. There was already a theory of this, by T.S. Popham,
but it clearly wasn’t right, because it gave a ridiculously large value. I produced a better
theory, which agreed well with the data from weapon tests. I also calculated another
phase of the signal. Popham’s theory, and my improvement on it, applied to the early
stages of the nuclear explosion when the strongest pulse was produced. This is important
because if you understand and can calculate it, it provides an important diagnostic. But,
later in the explosion, after the fireball is formed, there is further electromagnetic
radiation at a lower level and lower frequency, and that gives you information about the
overall yield of the weapon. I was able to calculate that phase as well. Later on, when
Britain exploded its first hydrogen bomb (to which I contributed, but that’s in Lorna’s
book), the Americans monitored the test including the electromagnetic pulse. It’s only
anecdotal, but rumor had it that there was a peculiar ionospheric effect at the time and
this mislead the U.S. somewhat. [Laugh]
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Barth:
On the hydrogen bomb, Lorna Arnold talks about this to a certain extent but she is a
little bit unclear to what extent your contribution has anything to do with radiation
pressure. Is there any connection you can talk about?
Taylor:
I don’t really know what I’m allowed to say. But more importantly, I don’t quite
understand what the problem is: can you tell me again what you felt Lorna didn’t really
explain?
Barth:
She mentioned basically in a couple of sentences that there are a number of possible
“fathers” of the hydrogen bomb. She talks about Roberts, you, and the organizers
Penney and Cook.
Taylor:
Penney and Cook were the organizers. Of that there’s no doubt, but Penney was not the
main driver of the hydrogen bomb. He had been, almost personally, responsible for the
atomic bomb. But the hydrogen bomb work was more driven by Cook, though he was
not a nuclear scientist.
Barth:
He was rather a manager?
Taylor:
He was a very good scientific manager, but he contributed scientifically as well. As to
who invented the principles, I find that sort of discussion very difficult. Katy Pyne, who
was Lorna Arnold’s associate, always asked, “When was the great revelation?” I keep
telling her that “There wasn’t a great revelation.” (Actually, in the case of predetonation,
there was a moment of revelation. I remember the evening that I realized that if you
reversed time and ran things backwards, you could solve the problem completely.) To
me, the key point in development of the H-Bomb was that people, including myself,
imagined that radiation always diffused through material. You learned that at school. It
was when Keith and I realized that radiation at a few kilovolts behaves differently that
we saw how everything should be done. At the few kilovolts level, radiation doesn’t
spread out gradually. It has a very sharp front. It isn’t quite a shock but it looks like a
shock. And there is, indeed, a definite point that the radiation reaches at any particular
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time. That’s quite different from diffusion where it just gradually spreads out and it gets
everywhere. When we realized that, and that we could compute how fast this front
moved; we had a “design tool.” We could ensure that the radiation gets where it ought to
be at the time we want it, and that it doesn’t get there before we want it. Once we
realized that, we knew it could be done, though there was a lot of work still to calculate
exactly how it could be done. So, the nearest thing to a Eureka moment is that, but even
that emerged somewhat gradually.
Barth:
Compared to the U.S. program, of course, the British scientists knew at this time that
there was a principle that made the hydrogen bomb work, but nobody quite understood
how the radiation pressure needed to work in order to compress the secondary?
Taylor:
By the time I got to Aldermaston there was no contact with the Americans. That contact
was cut off by the McMahon Act [1946, amended by the Atomic Energy Act of 1954],
which said that Americans could not give any information to anybody. Unlike the atomic
bomb, where we did get a lot of information from the Manhattan Project, we had no
information about the hydrogen bomb. We did, of course, know it could be done, which
makes things very much easier. But we didn’t actually get any technical advice or
information from them.
Barth:
You also worked on the yield calculation?
Taylor:
I did calculate the yield, yes. Unfortunately, even as recently as a few years ago,
Aldermaston wouldn’t let me look at my own calculations and I’ve forgotten what I did.
But I do claim that I wrote the first paper calculating the yield of the British hydrogen
bomb, which was called “Green Granite.” One aspect of the Green Granite tests, which
Lorna more or less says in her book, is that these tests and subsequent ones (which I did
not play any part in) were a factor in getting the McMahon Act repealed. Scientists from
Los Alamos and Livermore realized that we had got an important principle, but weren’t
sure whether it was exactly the same as the one they’d got. So they became quite
interested in collaboration. Anyway, the McMahon Act was repealed and collaboration
with the Americans was re-established shortly after the time I’m speaking of. When
collaboration was reopened it was reopened in a rather peculiar way; that the American
scientists were only allowed to tell us things which we had proved we already knew
about. [Laugh] The first order of the day was therefore to produce about ten or twelve
reports summarizing what we did know. Two of those reports were written by me, one
14
on initiation, and the other on EMP. That was when I first came to the notice of
American scientists in Los Alamos and Livermore.
Barth:
But you didn’t travel at this time?
Taylor:
I didn’t travel to the weapon collaboration meetings, because by then I was thinking of
other things. That was about the time that I started to think about fusion.
Barth:
Which we shall come to in a second. At Aldermaston you also worked on what is now
called the “fraternicide problem,” the problem of incoming warheads being ignited by
the explosion of the first nuclear warhead.
Taylor:
Yes, that was a very exciting day. It was literally one day. [Laugh] It came about from
two things really: the fact that I was collaborating with Keith Roberts on the design of
the hydrogen bomb and that I had done the work on predetonation. Keith and I
discussed these topics during the day and then we each went home in the evening and
came back next morning and said, “My god. I’ve thought of something — if we
exploded one nuclear weapon just before another, the second one would predetonate
and it would be a fizzle.” If the Russians were to fire a defensive missile just as we’re
sending ours over, the whole lot would be useless. (Neutrons from the first explosion
enter the core of the second incoming warhead and cause spontaneous fission as if the
core had been full of a large amount of 240 contaminant.) People had realized that
neutrons would upset the electronics and took appropriate precautions, but they hadn’t
realized this point about contamination. For a few days it became the hottest topic in the
lab, except that we weren’t allowed to talk about it. [Laugh] I think I literally had to put
my hand on the Bible and swear I would not tell anybody about this. I was not even
allowed to tell Corner, my division head.
Barth:
It seems you worked on so many exciting topics. Why then did you decide to leave
Aldermaston?
Taylor:
15
Mainly because of the classification issue. My feeling about that was then, and is now,
that in the short-term classification was an asset to the program, because it concentrated
people’s minds. Since you couldn’t publish, it was no good saying, “Well, I’m going to
write a paper on so and so.” You either did something useful for the project or you got
out. Of course, classification is detrimental because there isn’t so much free discussion.
But you must remember that the project was very large, even in Britain. There would be
6,000 people at Aldermaston at the time I’m speaking of. My work was probably read by
just as many people then as later on when I was writing unclassified papers. [Laugh] But
nevertheless, the fact that I couldn’t go to meetings slightly irked me, and I decided I
would like to get into something unclassified.
Barth:
Your decision was driven by the concern about publications, rather than by other
concerns you might have had?
Taylor:
You mean like moral concerns?
Barth:
When I talk to other scientists who have worked in the classified world, some got out to
publish in the open literature. Some got out because they felt they didn’t make a useful
contribution. They had different reasons.
Taylor:
There are obviously many reasons. When I first went to Aldermaston antagonism
towards nuclear weapons was not great and it wasn’t an issue. By the time we’ve now got
to (1957), it had become very much an issue. A test ban was about to be negotiated,
(which, by the way, was one of the pressures we had to work under; we knew it was
likely to come and we had to get every thing done before it did). By then there was
opposition, and CND (Campaign for Nuclear Disarmament) appeared. I went to the
first CND anti-nuclear rally. They held their first meeting near Aldermaston. Later on
they had more sense and held them in London. The first meeting was a bit like
Woodstock actually, in a field near the site. I went to it and saw these people and read
their literature and was completely unconvinced. I might rather have done something
else, but I felt it was the right thing for Britain to have nuclear weapons at that time. One
of the things people used to say is, “Why does Britain need nuclear weapons when
America’s got them?” I was very clear about the answer to that: I thought the great
danger was that the Russians would march into Germany or something like that, because
they (rightly or wrongly) had come to believe that the US would not respond to an attack
in Europe. Isolationism was not dead, and if I’d been an American I might well have felt,
16
“We’ve saved them twice. We’re not going to do it again.” To me this was the great
worry and, therefore it was very important that Britain had its own deterrent. One of the
other reasons I was looking around for something new was that I felt that to some
extent the excitement was over, technically. But most importantly of all, I hadn’t been to
an international scientific meeting and felt I would like to do so.
Barth:
Did you feel this draw to work with the international scientific community, to work with
Russian, Japanese, German scientists?
Taylor:
Yes, that’s what scientists do. This was a big draw. Yes.
Barth:
To go back to international conferences?
Taylor:
Yes. Well, not to go back because I hadn’t been to any, but to go to some, yes. I thought
I would like to get into a field, which would allow me to travel and talk, publish.
Publishing didn’t reign quite as much then as it does now, but the idea of just
collaborating and going to places and talking to different people was an attraction, but
perhaps I’d just decided it’s time I moved. I didn’t stay awake all night thinking, “My
god. I must get out. What can I do?” But it was in my mind that I would like to do
something different. And then, out of the blue, in Autumn 1957 the opportunity
suddenly arose. My supervisor, Corner, called me into his office one day and said,
“Bryan, you’ve done all this wonderful work on radio flash (EMP), so you know all
about Maxwell’s Equations, don’t you?” [Laugh] Well, would you tell your supervisor
that you don’t know about Maxwell’s Equations? So, I said, “Yes sir, of course I
understand all about Maxwell’s Equations.” (We called our Division heads “Sir” in those
days.) He said, “Oh good, because these people at Harwell,” which was the rival
establishment twenty miles away, “are going to announce that they’ve got nuclear fusion
in a machine called ZETA and it’s going to make power for everybody for next to
nothing — from seawater. It’s important that we get in on this project because if there’s
a test ban we might need some diversification. We’re well placed to do it, because it
involves neutron blankets, and we are experts on neutron scattering and interactions and
know more than anyone (in UK) about 14 MeV neutrons. [Laugh] We can do the work
on materials and blankets, but we must have somebody who understands the core of the
thing, which depends on magnetic fields. You and Keith (Roberts) can familiarize
yourselves with all that stuff and be the Theory Division advisors on this great new
17
world of magnetic fusion.”
Barth:
This conversation was essentially the beginning of your interest in plasma physics?
Taylor:
Absolutely. The day it all started was in Corner’s office, telling me that Harwell were
going to announce that they’d got nuclear fusion in this magnetic device called ZETA,
and Aldermaston needed people who understood it. (There had, in fact, been a certain
amount of experimental work at Aldermaston related to magnetic fusion. For what
reason, I can’t now recall, if I ever knew. But there was no work in Theory Division
prior to the moment I’ve just spoken about.) Corner also said “There’s going to be a big
meeting at Harwell, perhaps in two weeks time, when the Americans are coming over to
exchange information about these things. You and Keith can go.” Then at the last
minute Keith couldn’t go, so I went on my own. I went to Harwell and heard
presentations by all these great men whose names I’d just discovered, like Lyman Spitzer,
Edward Teller, James Tuck, Richard Post and the rest of them. They all gave
presentations on the American program. These presentations, from all the various
groups, were my initiation. When I came back to Aldermaston Keith said, “Well, what
did you discover?” And I said, “Well, most of it’s pretty straightforward stuff — except
for Spitzer, who talked about a weird machine called a Stellarator. Frankly, Keith, I didn’t
understand it. It seems magic to me. He says there’s a poloidal magnetic field without
there being toroidal current, and surely that’s against Maxwell’s Equations, isn’t it?”
[Laugh] I’m serious. I mean, you can’t imagine what a surprise the Stellarator was. I’ve
often said, “There’s only one really original idea in the whole of magnetic fusion and it’s
the Stellarator.” I support this by pointing out that before the subject was declassified at
Geneva in 1958, every country that had a program, invented all the other methods
independently, but only one place invented the Stellarator, and that was Princeton.
Barth:
Because it’s such a weird shape.
Taylor:
Because it’s such a weird device. Spitzer said that if you take an empty toroidal tube
containing a magnetic field, and bend it into a figure of eight, it acquires a poloidal field.
It was utterly mysterious and it really took me quite a time to understand the Stellarator.
Barth:
Since you were only coming to this in the late ‘50s you didn’t follow the Atoms for Peace
18
Conference in 1958 where nuclear fusion models were exhibited by the Americans and
the Russians?
Taylor:
No. Nor was I present when Kurchatov came to Harwell. The only early meeting I went
to is the one I’ve mentioned. I remember it vividly because Teller gave a very gung-ho
talk about “swords into ploughshares” on the Los Alamos Pinch work. Then Spitzer
came on and spoke modestly about this wonderful machine, the Stellarator [Laugh]. I
think Dick Post from Livermore described the mirror machines, but one can grasp them
in an hour or two. One can grasp the pinch in ten minutes, but the Stellarator took many
days, if not weeks. Exactly how this fitted in with Kurchatov coming I don’t know.
Barth:
Kurchatov visited Harwell earlier, in April 1956.
Taylor:
So anyway, now I’m into fusion, or at least I’m supposed to be into fusion and still
feeling a little aggrieved that I’d not been to a major conference. Keith Roberts, who was
to be my great friend and collaborator over many years at Aldermaston and at Culham,
had been abroad as a Commonwealth Fund Fellow. (The Commonwealth Fund was very
big in those days. Many eminent people were Commonwealth Fund Fellows, including
people like Alistair Cook and Harold Wilson, the British Prime Minister, and Freeman
Dyson, the famous physicist.) He said, “Why don’t you apply for this fellowship? It’s a
great thing. Lots of freedom and it’ll take you to America and you can go where you
like.” I was not very confident but I did apply, and I was lucky enough to get a
Fellowship. I wanted to go to Princeton because it was the place for fusion then,
especially on the theoretical side. But although I was by then known to some physicists
in the US weapons field, I wasn’t known at Princeton, who turned me down. (I
challenged Ed Frieman many years later to say, “Was it you who turned me down?”)
[Laughter] At rather short notice, therefore, I had to find somewhere else. My next
choice was Livermore, but there was a problem with Livermore because it was so highly
classified. And so an agreement was struck whereby I would go to Berkley, but would be
able, on an ad hoc basis, to visit Livermore from time to time. So that’s what I did. I
went to Berkeley on the understanding that I could go out to Livermore to see people
like Harold Furth, Stirling Colgate, and John Killeen. My visits to Livermore were rather
infrequent and became less so as time went on, and I found people to talk to in Berkeley,
like Allan Kaufman for example.
Barth:
19
How much time did you spend at Berkeley?
Taylor:
One academic year, from the late autumn to the late autumn as it were. One of the
features of the Commonwealth Fund is that it was designed to encourage people from
Britain to understand America. Therefore, it was a condition of taking the Fellowship
that you must spend three months visiting different regions of the States. So, during that
year I visited every one of the American fusion labs, Los Alamos, Princeton, Livermore,
Oak Ridge, and a few smaller places that were somewhere in Iowa, I think. My wife and
I drove all across America (with a two year old daughter) and stopped on the way at the
places I’ve mentioned. We also made individual visits to some of them, and to GA
[General Atomics, San Diego] and UCLA. By the end of the year I felt I had met
everybody in fusion.
Barth:
Which labs impressed you at this point?
Taylor:
I was very impressed with Princeton. It was the main center for theory. And with GA
which was just starting up and where Marshall Rosenbluth was leading the theory effort.
(The circular building at GA was architecturally very interesting. It is shaped like a
doughnut. I don’t think it’s got anything to do with fusion! Only a small sector was built
when I first went there.)
Barth:
Princeton probably appealed to you because this was the place to go for a theoretician?
Taylor:
Princeton appealed to me because it was the main center for theory, unquestionably, but
otherwise there was not a lot to choose between the Labs in those days. They all had
large experiments, but Princeton definitely had the edge when it came to theory.
Barth:
How did you see the relationship between the theoreticians and the experimental
scientists at this point? Was there much contact? Would you also go to the machine
people?
20
Taylor:
Oh yes. In those days, there was good collaboration between them. In fact, I can give
you an anecdote that illustrates that. During this same year, when I visited all the
American labs, I also attended the first unclassified Sherwood (Fusion Theory) meeting.
This was held in Gatlinburg in early 1959, where again I met all these theorists. But I also
went to the first American Physical Society Plasma Physics Division meeting, which was
held in November of 1959 at Monterey. The APS Plasma Physics meeting has now
become a gigantic week-long meeting with a thousand people, and it even got to the
point at one stage when it had thirteen parallel sessions (before Poster sessions came in).
The first meeting was only two and a half days, and on one of the days the organizers
said, “We’re going to split the meeting and have experimental papers in this room and
theory papers in that room,” and everybody was deeply aggrieved at the thought that the
theorists might not want to go to the experimental papers, or vice versa. So, in those
days there was close collaboration, and people like Harold Furth, for example, would
switch easily between theory and experiment. I’m afraid they’ve now, to some extent,
gone their separate ways. (I hope that someone will note that I was at these first two
seminal meetings, and if I last long enough perhaps I’ll go to the fiftieth anniversary.)
There were only about fifty people at the Monterey APS meeting, and I’m pretty sure
there were only about thirty people at Gatlinburg. Gatlinburg then was a tiny little town.
We had the meeting in a hotel, which was hard pressed to find us a slide projector. When
they did eventually find one it was one that projected the old-fashioned two and a half
inch square glass slides, and we then had to find an adapter for 35mm slides. [Laugh] So,
it was all great fun but very different from today. One other very important thing
happened while I was in Berkeley, which of course was a great accelerator center: John
Adams visited. John Adams was director of CERN for two separate periods. Exactly
what his position was in 1959 I can’t remember, but he was certainly a famous figure in
accelerator research. He informed me that the British government was going to set up a
new laboratory purely to do magnetic fusion, and that he was the director designate of
this lab. He asked whether I would be interested in joining him. I’m notorious for never
making quick decisions and possibly never making decisions at all, [Laugh] so I didn’t
immediately say “yes” or “no.” But I said, “Well, when I come back to England I’ll get in
touch with you and I’m sure I’ll be interested.” So, that’s how I met John Adams and
when I first heard about Culham Laboratory. Initially, it wasn’t going to be at Culham,
by the way. It was going to be at Winfrith on the South Coast, but there was great
opposition from people at Harwell to moving to Winfrith. So, it was eventually agreed
that it would be at Culham, because that wasn’t very far from Harwell. When I met
Adams, of course all that was in the future. When I came back from America in 1960 I
did decide to join Culham, though I didn’t actually transfer physically to Culham until
1962. I spent the period 1960-1962 with a foot in both camps. I was based at
Aldermaston, working mostly on fusion, but still consulting about weapons when people
asked me.
Barth:
21
But your heart was already going into plasma physics?
Taylor:
My heart was already in magnetic fusion, as it’s now called. (I think it used to be called
CTR for Controlled Thermonuclear Research.)
Barth:
What drew you most to magnetic fusion? The excitement of the field, the difficulties of
the questions, the collaboration with American scientists?
Taylor:
Well, it was all those factors. It seemed like a tremendously exciting field, yes, and I had
met everyone in the field. “Everyone,” is an exaggeration of course, but I had met many
people in the field. And there was going to be this exciting new lab. It was almost a nobrainer that I would go there. It’s just that I was reluctant to take the plunge for a time
and so I continued to be based at Aldermaston until 1962.
Barth:
Before we come to the 1962 move to Culham, I would like to come back to your work at
Aldermaston on fusion issues. You worked there on Bohm Diffusion and fluctuations.
Could you highlight your fusion work at Aldermaston?
Taylor:
Yes, as I mentioned earlier I started to work on fusion at Aldermaston as a result of
ZETA which, by the way, had not made thermonuclear neutrons. This was a most
unfortunate episode really, in which people made rash statements, which were later
shown to be wrong. But more importantly than that, is that right up until almost the
present moment, whenever there has been an announcement about fusion, you could be
absolutely sure the press would dig up the fact that, “There were all these claims
previously about ZETA.” [Laugh]
Barth:
Who was responsible for this ZETA problem?
Taylor:
Peter Thonemann and Sebastian Pease were the leaders of the ZETA project; I don’t
22
know whether they were responsible for the mistakes. The most unfortunate statement
was that attributed to the Harwell Director, Sir John Cockroft, who was asked, “How
certain are you that this is really what you say it is?” And he said, he was “90 percent
certain that it was okay.” But you were asking me about Bohm Diffusion. I think I
actually started the Bohm Diffusion work when I was at Berkeley. An interesting facet of
the time was how we were absolutely beginning from scratch. There was nowhere you
could go to study magnetic fusion. In fact, there was only one book on the library shelf
that was relevant and that was by Spitzer, Physics of Fully Ionized Gases,[5] which he
had written from the astrophysical point of view. It included estimates of the diffusion
rate of plasmas, but experiments never showed this rate of diffusion. They all showed a
very much higher diffusion, which was interpreted in terms of something called the
Bohm Formula. Bohm had invented this formula, out of a hat, I think, in connection
with magnetic separation in the Manhattan Project. It appeared to be no more than a
dimensionally correct formula. But experimenters said their experiments were much
more in conformity with Bohm than with Spitzer. And, of course, that would have been
death for the project because it was an unacceptably high rate of diffusion. So, Bohm
Diffusion was a very big topic in those days. People assumed that it was all due to
fluctuations but they couldn’t measure fluctuations in those days. The diagnostics were
too primitive. I came up with a couple of theories, which sort of helped to understand it,
but only later did anyone, including myself, realize what these theories were actually
saying. I also wrote papers on the Aldermaston pinch experiments. Because there was
then good collaboration between theorists and experimenters, I would go along and talk
to Hugh Bodin, for example, or Brian Niblett, who were in charge of these experiments,
and discuss it with them. These were fast-pinch experiments. The plasma was overcompressed and would bounce, so there were oscillations. I showed that you could use
these oscillations to obtain information about the density of the plasma and the profile. I
also invented and calculated something called “area shock,” which has never really been
a big thing but is rather fascinating actually. They had a long linear pinch, and noticed
that a disturbance came in from the ends. The photographs showed that a sort of
expansion wave comes in from the ends and moves towards the center. I called this an
“area shock” because it’s an increase in the area of the cross section. It turns out that
mathematically this is precisely the same as something called “water hammer.” Water
hammer is when water is flowing down a tube and you suddenly stop it and a
compression wave travels back up the pipe. In the case of a copper pipe it causes a very
small expansion of the pipe. You get the same thing in a plasma but there the expansion
is very large, because the resistance of the magnetic field is much less than the resistance
of a copper pipe. I’ve always thought that it was a rather neat idea, but nobody else takes
much notice of it. [Laugh] Now I think we’re at the point where I might be about to
move to the Culham site. At that time Aldermaston, Harwell, and Culham were all part
of the United Kingdom Atomic Energy Authority, so moving from one to the other was
no big deal administratively: I got paid the same amount in the same way. It wasn’t a big
deal except for the actual physical move, and that was [Laugh] a very hectic experience.
There was due to be a trip by Culham members to the Soviet Union, something
extremely rare in those days. I think it was only the second such visit that there had been.
23
I was not invited to go initially. My colleague, Bill Thompson, was going to go. But
about two weeks beforehand it was discovered that Bill Thompson couldn’t go and John
Adams insisted that I should go instead. I was still living at Aldermaston, and the
Foreign Office was not exactly thrilled when John told them that [Laugh] he was sending
J.B. Taylor, who lived and worked at Aldermaston, to go to the Soviet Union. I think
initially they vetoed it. But John was not a man to take a veto lightly and overcame it. I
obviously didn’t know what he did. The Foreign Office reluctantly agreed, but only on
the condition that I physically moved from Aldermaston to Culham, and that I had a
new passport and a new address. The Atomic Energy Authority found a house, the
Foreign Office arranged a new passport, scrubbed my identity, and I moved, all at a few
days notice. It would take twelve months now to get the [Laugh] relevant permissions.
This illustrates how important science, and fusion in particular, was considered at that
time. I think it was the middle of the week when we moved to our new house in
Abingdon, and the trip to Russia was the following weekend. When we got to Abingdon
we realized to our utter horror that none of the electrical appliances would fit, because at
that time Britain had two systems of power circuits: one known as the 13 amp system,
and an older system known as the 15 amp system that used totally different plugs. I
remember sitting down changing plugs. I asked my wife, “Which appliances are
essential? Because I haven’t got time to do them all” [Laugh] Then I disappeared off to
Russia. [Laugh]
Barth:
Did you meet scientists in Russia?
Taylor:
Yes. That was the main point of the visit.
Barth:
Whom did you meet?
Taylor:
We met Sagdeev, Leontovich, Kadomtsev, Artsimovich and many more. The whole
point of this trip was to contact these eminent Russian[6] scientists. We did something
similar to what I had done in my trips round the States, except we did it in two or three
weeks instead of a year, and visited all the Russian labs. We went to the Kurchatov in
Moscow, and the Joffe Institute in Leningrad; we also went to Kiev and Sokhumi on the
Black Sea, all of which was a very hectic and exciting experience for me and everybody
else.
24
Barth:
Did the Russians know that you had worked at Aldermaston?
Taylor:
Oh, I’m sure they did. It was all just for the form, I think. The Foreign Office briefed me
before I went and said I mustn’t go off with exotic women spies. [Laugh] But,
unfortunately, no exotic women approached me so the question didn’t arise. [Laugh]
Barth:
Maybe we can begin our conversation about your time at Culham by looking first at your
managerial work and then turn to your scientific work.
Taylor:
Culham at that time was just an airfield. It didn’t have any administrative or
accommodation buildings. It only had aircraft hangars and runways, and the aircraft
hangars were not part of what was to become the Culham scientific site. So, there was
nothing there for us except a couple of prefabricated wooden buildings. There were only
a few people in these huts; the majority of the staff were still working at Harwell or at
Aldermaston, as I had been up to that point. So the first order of the day was to get
Culham organized and turn it into a proper lab. John Adams was the director, and
Dennis Wilson was his deputy. I greatly admired John Adams. His first task was to bring
everything to the Culham lab from Harwell and Aldermaston. It was quite an
achievement that he did this so successfully, because there was a certain amount of
rivalry, bordering on antagonism, between Aldermaston and Culham.
Barth:
Just like between Los Alamos and Livermore?
Taylor:
Yes. Very similar. John overcame that problem completely, and set up Culham. Culham
was originally planned to be the home of a single very large experiment. Remember,
ZETA, while it hadn’t actually achieved fusion, was, by a large margin, the biggest
thermonuclear machine in the world, and the plan was to build an even bigger machine
based on a similar design. It was to be called ICSE [pron. ice], standing for Intermediate
Current Stability Experiment. A very large building was being erected at Culham to
house this machine. The intention was that Culham would be rather like CERN. There
would be a big central machine, just as there’s a central accelerator at CERN, and most
scientists would in some way be associated with it. By this time it was realized that the
25
ZETA field configuration wasn’t stable, and ICSE would have had a slightly different
configuration (involving a sharp plasma boundary) which was at first thought to be
stable. However, it was later realized that, even if this configuration could be set up, it
was not, in fact, stable. (Really, the basic understanding of plasma physics was not
enough at that time to justify such an ambitious machine.) Furthermore, cost estimates
had escalated, so after much discussion at the highest levels of the UKAEA (in which I
played no part) ICSE was cancelled. So the first big question was “What to do instead of
ICSE?” John Adams more or less abandoned the reversed field pinch (the ICSE/ZETA
line), and Culham went over to mirror machines, or adiabatic traps. So what I was first
involved in was the planning of these new experiments and developing the theory
behind them.
Barth:
Did you have much less time for theory because you became involved in the planning of
the experiment?
Taylor:
No. I wasn’t very much involved in management, though I was on the management
committee. There were four division heads, each of whom had his own experiment or
group of experiments, and it was those division heads that were really responsible for the
planning, and I was responsible for Theory. At first, Bill Thompson was head of Theory,
but he very soon left and I took over. I went to see John Adams and said, “It’s very nice
and I’m very proud and honored, but what the hell am I supposed to do?” [Laugh] I can
almost quote his reply: “It doesn’t matter much what you do, but you’ve got to make
Culham a center of excellence with an international reputation in plasma physics.” That
was my introduction to being a division head at Culham.
Barth:
How did you fulfill John Adams’ request? To what extent did you succeed making
Culham a center of excellence?
Taylor:
As the story goes on I hope I shall prove to you that I did succeed. But, that comes later,
of course. At this point I hadn’t done anything except be appointed [Laugh], and I had
to think what to do. As I have said, after the cancellation of ICSE the emphasis was on
mirror machines, and the first few years at Culham were devoted to the building of these
machines. At that time these machines were becoming larger and more complex. A year
or two earlier I had been familiar with the experiments and knew which bit was which.
But at Culham I once remarked “One large rack of electronics looks exactly like another
rack of electronics, no matter what it’s doing.” This was just a joke, but that was the
26
trend; experiment and theory were becoming more professional.
Barth:
Did you have a sense that theory was still driving the experiments, or was it more that
the experimentalists were driving theory?
Taylor:
At this time everything was still very much driven by theory, because none of the
experiments were anywhere near the regime that one wanted for fusion. Anything you
wanted to know about fusion plasmas you got from theory or you didn’t have it. I think
JET and its contemporaries were probably the first generation of experiments that really
got anywhere near fusion conditions and became free of plasma-wall interactions. So,
everything was theory driven. But this was especially true of the Mirror Machines
because, being low density and dominated by the vacuum field, they were especially
amenable to theoretical analysis. In fact this was a principal reason for studying them.
(However, it is true that Artsimovich is supposed to have said, probably referring to
Princeton, “The trouble is the program is hag-ridden with theorists.”) [Laugh]
[1] The Frisch-Peierls Memorandum March 1940
[2] Freeman Dyson, Disturbing the Universe (New York: Harper & Row, 1st ed, 1979)
[3] Lorna Arnold, Britain and the H-Bomb (New York: Palgrave, 2001)
[4] In accord with the custom of the time, “Russian” refers to anyone from the then
USSR. Many were in fact from other Republics
[5] Lyman Spitzer, Physics of Fully Ionized Gases (New York: Interscience Publishers,
1956)
[6] In accord with custom at the time, the term “Russian” covers anyone from the (then)
USSR. Many of those mentioned were actually from other republics
27