Giuseppe Occhialini - Session II

Weiner:

Today is April 6th and now we are in your apartment. We were talking about Cambridge. I have a few other questions before we get into some specifics on your own research. One thing is the nature of research groups, whether there were specifically designed groups. I know that Aston worked by himself, that C. T. R. Wilson worked by himself relatively, and yet that there were a few people with them. What I am trying to ask you to do is to see if you can distinguish certain major groups in the laboratory and then give me your impression of what was the major focus of that laboratory, what were they doing as a major thing, if it is possible to do that — that is, to talk of the components and then to give me an over-all impression of what that laboratory was really doing most of its time.

Occhialini:

All right, I will try to do it, provided that you will promise me you check it.

Weiner:

I will promise you and promise myself.

Occhialini:

This means that I am not committing myself to more than to say what I felt at this moment. Don’t forget I was very young and I was a barbarian coming from a very uncivilized country, Fascist Italy, and the surrounding had a tremendous influence on me. So I was really looking starry-eyed. Sometimes I was expressing appreciation of certain things, and Blackett would tell me that I was just commenting on things which were not worth appreciating. I’m not sure about my judgment in this epoch.

To introduce the judgment I will tell you that I had certain ideas about England. After being there twenty days I went out with a girl walking, coming back from the cinema in the street, I met L. H. Gray at night, and it was a bit of a crisis. I asked myself what will L. H. Gray be thinking of me. I should perhaps be working in my studio and here I am carousing with a girl. What will he conclude out of it? He’s a nice chap. I have lost his esteem now. Does this explain to you what a young man of 27 coming out from Fascist Italy could conclude completely out of every culture — I was a barbarian.

No. 1 — C. T. R. Wilson was a member of the Observatory and he was having his own group. He had two groups of research. One was a wonderful one on thunder storms, in which he was imitating thunder storms. I still know very well that the first physical theory of cosmic rays came from Wilson. Wilson invented that thunderstorms could be responsible for producing charged particles. It was the first example of cosmological effect which could produce particles. And then there was work going on in condensation with Dee. Here I feel that C. T. R. Wilson’s influence was wonderful inasmuch as would bring knowledge and specialization and so on. But in a go-getting world had I been working with Wilson and not with Blackett I would have left Cambridge with empty hands.

Weiner:

And you would have left after three months.

Occhialini:

I don’t know if I would. There was always this contained tremendous possibility in Pilson. For example, very few people know that the Bragg work is associated with the name of C. T. R. Wilson. Very few people, why, because they don’t read. That a crystal could be treated as a reflecting mirror and not like a (???) you find was suggested by C. T. R. Wilson. As I told you yesterday, my first work on rubidium, the so-called Libbey spectrum, is all Bruno Rossi.

And so there was the Dee group. Dee possibly knew about physics as much as any person in the Cavendish could. I had always tremendous respect for Dee. He was knowing about the Wilson chamber more than any man I think knew in the Cavendish, apart from maybe C. T. R. Wilson. This was one of the groups.

Then there was the group of Diamond, Oliphant, Massey. They were all working together on heavy ions. They were preparing unknowingly that the revolution should happen, should start two years afterwards when I came. They were the people who were supposed to play with deuterium 2, having gone in discharges, in high vacuum technique, in purity of gases — once when you start work with isotopes, then you find a new utility for the fact that you are investigating discharges and attaining high vacuum and sealing tubes. And to find a very important part of this, the moment after Cockcroft and Walton’s discovery was that to do all the work which is on hand you should have more of this apparatus and you should maybe try to go to 200,000 volts, rather than outbuild. I was telling you yesterday. (Interruption)

Weiner:

…that the decision to go to 200,000 volts instead of overbuilding apparatus.

Occhialini:

I am coming back to something that should have been said yesterday. Yesterday I was saying that the genius of Rutherford, Cockcroft, and very likely Gamow (passing by), was to go to 600,000 rather than to build the wonderful machine called the cyclotron which arrived too late for this special job. Now it was evident that you could get with deuteron beams, and even protons, you could get effects by tunneling even with lower voltage machines and this was the job of Oliphant. So Oliphant was pushed by Rutherford in the direction which was parallel to the direction of Cockcroft and Walton.

Weiner:

Did Rutherford seem to take more of an interest in the Oliphant work than in the Cockcroft-Walton? This is an impression I got that he identified more with that as his project rather than the Cockcroft-Walton which was a separate thing that they were doing. (Machine switched off)

Occhialini:

The best reply to your question is that I don’t know. No comment. I’m not perceptive enough. I’m not a detective… Certainly I have difficulty because I have hero-worship for Rutherford. I have no hero-worship for Anderson so I will not hesitate for one minute to say, without having any evidence at all, that I feel that Neddermeyer has been very unfairly treated.

Weiner:

Now, we were talking about groups, Cockcroft-Walton on one hand and Oliphant’s developing this other device with Rutherford’s encouragement…

Occhialini:

No, sorry, please try to understand… I was there three years, and in these years I have seen history moving. When I came there, Oliphant was a person who was doing very nice work with Massey, Moon, on ions. Then with the Cockcroft-Walton discovery, with the deuteron discovery, with the new projectile, then it was evident that you were needing for the job not only an escalation(?) in electrical engineering you needed also a specialist in discharges. The passage of the Farkas brothers, for example, which was a product of Hitlerism was extremely helpful in that. One of the Farkas brothers died (Bobby) — they were Jewish refugees and they came in 1934 at the moment that I was leaving. The same way that I met one of the most extraordinary personalities who went there — Goldhaber. Goldhaber arrived there when I was leaving —

Weiner:

He was there earlier. He took part of his degree there and he didn’t go back as far as I know.

Occhialini:

All right… you are paid to do your work so you know history better than I do. I was only there. Look, I left in 1934. I met Goldhaber.

Weiner:

I am certain he was there in 1934. He worked with Chadwick on the photo disintegration of the neutron.

Occhialini:

He did the photo disintegration for Chadwick.

Weiner:

I will discuss that with Goldhaber.

Occhialini:

As a check to what I say.

Weiner:

Yes.

Occhialini:

Did he ask you to see me?

Weiner:

I don’t reveal my sources.

Occhialini:

That’s all right. This is a guarantee for me.

You see, this will take some time. I don’t think you will extract it all this time. You will have to stay more days. It will be your loss and my gain.

Weiner:

That will be fine… We were talking about the attitude of Rutherford toward the newer developments in the Laboratory, the things which you characterized informally the other day as making the industrial revolution in physics. I was suggesting that perhaps Rutherford’s attitude could be understood in these same revolutionary terms, asking whether any ruling class or group has ever given up voluntarily or with graciousness its position?

Occhialini:

If you can point to me a ruling class composed of geniuses, then I can give you the reply.

Take for example J. J. I met J. J. He had one of the groups. He was practically isolated and everyone knew that there was a moment at which J. J. and Rutherford had parted. I never knew the particulars. I never asked for I never ask things which are painful to me.

Weiner:

I do.

Occhialini:

I know only a story about it which was about young Peter Fowler.

Weiner:

R. H. Fowler’s son?

Occhialini:

Yes. Going around the Cavendish Laboratory as a child with Rutherford and passing in front of the door of the people of J. J. Thomson, which was in a certain place. I could show you on the map but I don’t have the map and it is changing nowadays. “Grandaddy, Grandaddy, what are the people in this room doing?” “I wish I knew, Peter, I wish I knew.”

You see, sometimes, an anecdote, which might be true or not true, explains the situation.

Then there was the other field… (Interruption)

My impression is this: there were no cosmic rays in Cambridge at all. There were no cosmic rays in England apart from the interest of C. T. R. Wilson in them as produced by thunderstorms.

Blackett was at the end of a lot of investigation of alpha particles. They were a bit fed up, I think, about them.

Weiner:

Fed up because of lack of interest or lack of results or both?

Occhialini:

There is a parallel. When I met Powell and when I met Blackett both of them were at the end of a career… It’s a very fair way. Blackett has done wonderful things but it was on a field which was associated with alpha particles, limited. On some occasion, in one or two of his pages he says, “And then the life of the Blackett family was changed completely by the fact that Occhialini passed through Cambridge.” It was no merit of mine, simply I was there. I didn’t climb any mountain, I was there at that moment. I think I know what Blackett might have done but I don’t know if this would constitute a deviation about the kind of thing that interests you and in which I have very little knowledge, which is a bit disconnected this structure of the Cavendish. It was not a military lab. Everyone had their part.

What Blackett would have done, would have done this. When Cockcroft and Walton would have discovered the protons, then Blackett would have been asked to get all the possible evidence to transport it in the Wilson chamber so that all the work could start again statistically in the Wilson chamber.

Why do I say this? When we were travelling in France with Cockcroft by car, he was saying that “I wanted Blackett would undertake… do you think that he could spare some time out of this cosmic rays adventure which people are talking about?” I said, “I don’t know.” I relayed the question and Blackett was tempted by this. I remember he started — he had a little jeweler’s lathe in his room — and he started building a window. He had a beam coming in and then you had to put a glass in the Wilson chamber for the beam and you had to have a window through which the alpha particles would come out. He would tell me, “I’ve seen the photograph of this.” It had been taken by Dee of two alpha particles coming out. But the thing was like a pencil, a kind of tube, and so on. Then they thought better. I remember one day Blackett and Dee had a talk. I remember Blackett smiling at the end of the talk, opening the drawer, taking out this little tube, putting it in the hands of Dee. So the thing went out of my life. Dee, who had been working in condensation with Wilson, went into a field in which his knowledge could be put to use by the running stream of the laboratory. Dee had already done the first work on neutron ionization. I remember that when I went to Rome in ‘34 they said — people like Segrè and Majorana, whom I did not know that it had been reported then, they were saying, “What is this? Dee must be crazy trying to detect neutron ionization.” This was the typical Wilson influence. You are supposed to detect primary ionization of neutrons. I remember that he showed a group of photos and he said, “Here, in this two drops, I believe.” So out of all this work came out two drops, and this was unbelievable for the philistines in Rome. But for people used to telling one another, in a friendly way, “C. T. R. Wilson is always right,” it was not impossible that a pupil of C. T. R. might be right. Since Dee had the cleanest Wilson chamber that ever existed, then he had the apparatus by which the neutrons that were passing through metals — they were giving some kind of track — this was the apparatus by which they could be seen.

So do you understand the story? There was a group of Wilson chambers that were working; some on magnetic fields, some on rays. People like Alexander and Carew were working on gamma rays. People like Champion — Champion was a Blackett pupil — and a group of people, like Lea, whom I never met — all these people of Blackett’s were undergraduates… So it is not unbelievable that in a place with a group of people like Feather (very quick on the trigger, very capable, very very intelligent) and so at the moment when the neutron was discovered there was the possibility of switching people, asking the help of people on the Wilson chamber, getting on the ionization chamber individual track counting. They were ready for years to work. Before they were detecting protons which were coming out of gas bombarded by alpha particles. Now they were supposed to detect the secondary product, again of the same alpha particle. It was all ready. They were experienced. There was all the possibility of working with the Wilson chamber and so on. So the Cavendish Laboratory at this moment was a splendidly-geared machine for this type of work.

Having passed through Paris at this same time I did discover why the Parisiens and the French were not in the same situation. There was not a leader. They were divided and there was not the possibility of cutting Feather in. If they had not cut Feather in, they might have cut Champion in, or Alexander.

Weiner:

Also, they didn’t have the detection devices.

Occhialini:

They had a Wilson chamber but they never did any real work on the Wilson chamber. Auger, I had the impression, was rather isolated. He was older than Joliot. Whereas Chadwick was in a position of power. (Interruption)

What I was saying was that Auger was the Wilson chamber man. Auger was his own boss in the lab but with(?) one machine. Chadwick had a group of people working in the lab and had the authority of a grand old man in there. When there was something big, as in this case, they really acted as a family. While Aston worked practically alone, completely aloof. I talked with Aston about lambda. He was a splendid man with practically only one…

And there was Ellis, working in beta rays. And then there was Kapitza, and Cockcroft and Walton.

Weiner:

What was the relationship of Kapitza to the rest of the work in the lab and to Rutherford himself? He had a parallel position to Chadwick’s — in the new lab, the magnetic lab.

Occhialini:

No, Kapitza left when the magnetic lab was built. I have the impression, and please check, that Kapitza too was at the end of the career. He had done very very nice things; he was recognized as a mad genius. They were working on this lab for him. Parkinson was not yet existing but I had a Parkinsonian feeling about Kapitza, that Kapitza was a man of tremendous possibilities, but in this machine, he had fitted once and I was not sure that he could fit in the future. While Cockcroft who was in the same technical line, an electricity man, a specialist in magnets and so on, at this moment had been asked to help Walton, who was trying to work with a machine that was practically a betatron, but not. I remember in one or two phrases Cockcroft smiling about it, but since I don’t remember it perfectly, I will not report it because it might look cattish and really Cockcroft was one of the greatest men whom I met. His simplicity, his generosity, his self-sacrifice and also, completely unheard-of in this period, his absolute efficiency. I will give you an example of his efficiency. When I arrived there, they showed me what they were doing. I knew because I had read about the attempts of Lawrence, and I remember a slight sense of pity and sympathy which I had for this wonderful laboratory trying to build this small high-tension in a way which looked to me absolutely amateurish, knowing that in the United States they were inventing things like the Van de Graaff, that they were building things like the wonderful cyclotron. The people there seemed to me to be a bit off-key. I felt at this moment that these people are great and will go on being great but they were trying to get in there by a very gallant effort. But it was really the fight of a very very small David against a very very big Goliath, so you see how my judgment is incorrect. Was I right or was I wrong? I was wrong because of the fact that I did underestimate the tremendous capability of Cockcroft and Walton and also the Big Crocodile. I don’t know what would have happened but Rutherford didn’t want any nonsense. When the thing started working, he put the lithium in and said, “all right, get alpha particles. Two alpha particles coming out, all right, why not put two Wilson chambers to look, why not put two propulsion amplifiers?” Rutherford said, “Will you put please two old spin telescopes(?). They come at the same time, all right, let’s put two people, with my old telegraph tap when they come, the proton comes in, the lithium gets split in in two alpha particles — they come at the same time… (Interruption)

So that like the neutron work was the moment of hurry in Chadwick’s life in which he had to act and think, the moment in which Chadwick awoke from this kind of safe work of the Cavendish in which to publish a letter in Nature was considered a crime.

Weiner:

A letter because it was less than a full thought-out well-documented article?

Occhialini:

This was the tradition of the Cavendish that you don’t write letters to Nature. I remember when I was in Bristol I received a small note from Blackett, a small postcard, saying, “Dear Beppo, I have seen your letter in Nature. It is the third letter in Nature this year. It’s a little bit too much.” For history, it is a very important part of the tradition that the letter in Nature is your last bullet. I remember that when I got the spectrum of positive and negative electrons — no, not this, sorry, I had done something on the Wilson chamber, and I said this is all what I could do. The sources were very small. I got one photo every 30 (?), coming in the lab at 8 o’clock, eating near the Wilson chamber, getting back at 6 o’clock. Even during the night I cannot sleep because I am dreaming about the Wilson chamber. So here I got only so many examples. Cockcroft says, “Rutherford would tell you, young man, go back to the lab, spend three or four months getting more evidence, and on this I fundamentally agree with Lord Rutherford.” This was the spirit here. Letter-writing was a crime and publishing with not enough statistics was a crime.

Weiner:

This is borne out in Rutherford’s attitude toward other laboratories’ work because when they did publish something or when he saw a manuscript that he thought was less than complete or which presented either questionable evidence or stuff which he just knew was wrong, he would try to pre-referee and to write to the people and encourage them to work out the differences, to resolve the discrepancies between the things he knew were right and things that were in that paper before it was published. He used to use the phrase in his letters “before rushing into print.”

Occhialini:

We agree about that. So here now comes a rather important thing. I told you that it would have been an extremely beautiful thing for me in my life to go around telling that I was a pupil of Rutherford. I couldn’t do that. I hardly met him. It would have been wonderful to tell that I was a pupil of Fermi. I hardly met him.

But in a way there is a Rutherford geist. This was with the inner revolt of a man like Blackett to the society in Cambridge, which is privileged, and with the different political attitude. Blackett was a pupil of Rutherford.

Weiner:

In other words, you are saying: despite all of those differences…

Occhialini:

In spite of political differences and other differences, Blackett was a pupil of Rutherford anyway, and me too.

Weiner:

You were derived.

Occhialini:

In my career of paper-writing overall and paper-correcting. I had a bad moment in my life when I was in Brazil when I lost the sense of measure of myself. (Interruption)

What I was trying to say was this, that I brought from this Cavendish geist a tremendous desire for honesty, a tremendous desire for exactitude. I know about it because I had to correct a lot of papers from my young pupils. I corrected them three times. They laughed a lot about it. The first reading is wonderful; the second reading is criticism; the third reading I am practically in hate for the paper. The paper gets destroyed completely. I don’t say that the paper is rejected but the paper must be written again. In the same spirit, I shout one of my phrases “lake pirates.” They are not yet pirates of the high seas. (Discussion of what he says to his students not transcribed.)

I remember the first paper on mesons which I wrote with Powell. I supervised the apparatus(?) — Evidence for the Disintegration Produced from Particle of Intermediate Mass. This is one of my contributions to this paper. Powell too was a Cavendish man, yes. The paper was carrying six or seven photos. I received a postcard from Blackett, “Very nice article in Nature but I would not call them mesons as you do in Figure 3 if I were you.” Then I looked at the paper and I discovered that in one of the four figures the word “meson” that had been scribbled on had remained. And all the paper had been correct. I called on the damn negatives, mesons, for in science you have no proof of anything. But on one of the Figures it had remained. Blast it! The man comes and nails me on a cross for he does not know the trouble to which I went to respect his rules.

This is a rather important part of physics for physicists and scientists are divided in two groups: people who have fathers, and people who have not. What made European physics great, what made the Cavendish great, was the fundamental science of fear. Fear of what? Fear of the wrath of the old man, fear of being despised by the old man, fear of being despised by the son of the old man — so there was there a co-fraternity of people who had built together, which was part of the English tradition. Rutherford was a man who was playing a well-known tune on a very big organ but it was a part of the Faraday tradition, it was a part of the Darwin tradition. It was England. And this was not happening 100% in France at this moment. And this tremendous fear of looking foolish, of being asked a question that Rutherford was famous for. A man who was showing results that he got on discharges in gas. “I have got only one question to ask you: did you before applying the high tension and taking your measurements, put on the vacuum during 12 hours and bake with the Bunsen flame for two hours all the points, and so on, and so on.” “No.” “No more questions to ask.”

Weiner:

Chadwick had established a drill for counting particles, a specific routine which embodied all of these kinds of precautions.

Occhialini:

Chadwick and Rutherford had enlisted…(switch tape)

Weiner:

We were mentioning Chadwick’s drill for counting particles.

Occhialini:

Don’t forget that there were two groups. One was Chadwick and the other one was Rutherford with a group of two young men. For the side of Chadwick there was Duncanson and Miller; for the side of Rutherford there was Lewis and Wynn-Williams, and Mark Boden came afterwards (who gave me the first emotion when he laid on my table a paper by Lord Rutherford and him on actinium with a note: “We made these measurements with a counter personally by Dr. Occhialini.”)

So there was a routine which was established by this Rutherford way of counting, in which you applied the autostatic technique. With a group of young people it had come out. Counting with scintillation was now a thing of the past. Rutherford was a strategian. In Geiger he found the man who would give him the means for finding out. In Cockcroft he found the same. I think he found in Blackett a bit of the maverick. He did the most wonderful confirmation of the thing, but when he went into cosmic rays this was something which was out of the tradition. They came back after the Geiger disappearance counting single particles by electrical method. This was the state of the art when I arrived there, this is the photographic emulsion. Here it is, p. 49, “Detection of a single alpha particle.” (Rutherford, Chadwick & Ellis, Radiations from Radioactive Substances). Here you have the “Electrical method… In order to increase the electrical effect of a single alpha particle, Rutherford and Geiger in 1908.” This is evident, that this is not in alphabetical order, so this means very likely that Geiger has been put on it, with this policy. Geiger was (???) all of his life. There is Geiger and Rutherford, “by using a string electrometer instead of the ordinary quadrant electrometer.” (p. 51, op. cit.) Geiger and Rutherford. (Looking through the following text) Geiger, this is the research, similar use, Taylor, action of the counter, scintillation method. At the moment when this book was written, the revolution… was Wynn-Williams. If you want to get paradise, go and see Wynn-Williams. If you happen to go to the major protagonist of all the history of the Cavendish with Blackett, go and see also Wynn-Williams.

Weiner:

Where is he now?

Occhialini:

He’s an old Lecturer in Imperial College. You know what he did. We talked about it. He was fundamental in bringing electronics in nuclear physics. He allowed fast counting by applying the scale of two of the thyratrons. This is also a very important thing. At the moment at which I did arrive thyratrons were there. Thyratrons were arriving in the scientific world on the market. What did the thyratron mean? It meant that once you had a small electrical impulse you could unleash a tremendous energy in any direction either in the magnet of the Wilson chamber to release it quickly or on a circuit that would keep a magnet constant or taking the very quick time of the starting of the arc in the scale of two which would allow you to count with a mechanical counter which could count only a hundred impulses for a minute — you could multiply eight by 10,000 and soon get a real statistic. This was Wynn-Williams, the father of this, the man who would supervise the building of all of this.

Weiner:

Let me interrupt now. I think we are just at the point where I would like you to start on the train of events which we have set the stage for, which led you to your own research. I want to know all about it.

Occhialini:

Yes, but before I drop it — I might die before — I want to talk about Goldhaber. I will give you ten words, ten very long words about Goldhaber.

Weiner:

Let me introduce it for you because you were about to say — you had said that Chadwick had broken out of a pattern with the letter to Nature.

Occhialini:

No, he didn’t break out. The letter — had already been done. He did the neutron. He convinced me to send a letter to Nature on the positive electrons from polonium beryllium sources, a letter which very reluctantly I signed. He had a tendency to apply pressure. Since Blackett had been very busy and I had done the mechanical action of acting all the Wilson chamber, he had a tendency to squeeze out Blackett. This I wouldn’t have, so I cancelled my name and sent back the paper for Chadwick. The paper came out Chadwick, Blackett and Occhialini, something which the angels in Paradise will ask questions about. It was not right. Alphabetical order should have been used. After all, he did not put any ideas in it, not a single idea. He did not build the apparatus, he did not act the apparatus. He lent a bloody beryllium source which was 200 times inferior to the one which we could have had from Paris if they would have lent it. It was 600 times less than the one which we might have got two years afterwards.

Now about Goldhaber. Well, this is what I tell you that Goldhaber told me. Since I understand that you have seen Goldhaber and maybe you found him reticent, I am not going to be reticent about him. He said that he had the deuteron; he had the Bohr fission.

Weiner:

Which he didn’t know was fission at the time.

Occhialini:

I call it fission. This is the correct word.

Weiner:

It is one of those things people kick themselves for — for not recognizing at the time what it was.

Occhialini:

It didn’t have a name. You talked to Frisch, I understand.

Now we had a wonderful dinner in a Chinese-Indian restaurant. It was one of the friendliest I was passing by — yes, yes, I went in Cambridge to meet Gamow.

Weiner:

You’re saying by this time you were in London.

Occhialini:

No, I was not in London. I was in Italy. I had come back from Italy, I think. I’m not sure about it. It is possible that this conversation happened either in 1937 or at the end of 1934 — I don’t remember. There is a possibility that it happened in ‘37 for Goldhaber was telling me that “I feel Cambridge cannot remain the capital of physics, so if I must not stay in the capital of physics, I might go to America or some other place.”

Weiner:

He had taken a trip in ‘37 to the US to look around and had come back with a job offer. I think it was ‘37, maybe it was ‘38.

Occhialini:

Maybe what he was telling me was this — that I want to give you my recollection so that you will understand that you might not realize that this was 120 years ago. Then we were commenting on the work. During the night, we were talking about the letter to Nature, who went it, and so on. It was ‘34, maybe no. It was a wonderful evening. I never forgot the warmth with which Goldhaber said: “Well, we might say, you and I, that we pushed a bit for the Nobel Prize for Chadwick.” About this question of me letting him put an undeserved finger in the positive-electron. Don’t forget that there was another Wilson chamber in the magnetic field which was working at the same time. On this I will tell you that there is one part where there is a false shadow and on this you should not…

Weiner:

Thanks for teasing, By the way, the date of their paper on the first meaaurements of the deuteron binding energy, Chadwick and Goldhaber published in Nature in 1934. Then their work on the photodisintegration of the deuteron was published in 1935.

Occhialini:

‘34 is correct. Then it is quite right that it was ‘7 for in ‘34 Chadwick got in on the Prize.

Weiner:

No, in ‘35 he got the Prize.

Occhialini:

He got it in ‘35? This is a funny period you understand. In ‘34 it was the coming back to Italy. It was a very bad period for me. But I had a chance to come back once again to England in a meeting on nuclear physics in London.

Weiner:

I didn’t know you were there. This was the conference on nuclear physics which had people like Max Born, who gave the opening paper.

Occhialini:

Yes, Millikan was there.

Weiner:

Millikan was the chairman of one of the sessions.

Occhialini:

I was there, and I remember it was a rather upsetting period. They refused my passport. I had to do my military service. I rushed to Bologna; I rushed to Rome. I got my passport out with very strong political party intervention. So I arrived with my friends, Bernardini, Dali Buchinelli(?), Emil Capitilista(?) who went afterwards to work with Richardson in the States. We went by car. I was left in Florence. I was very unhappy. A good part of my life I was prevented from going. Then I succeeded in going. I remember it was a hard trip. I went there. I certainly went to Cambridge to visit Gamow. It was ‘38 for my next passport I got it in order to go to Brazil. When I got back from Brazil I succeeded in having a passport to England. Then I went to Manchester. Then I went to Cambridge. Then I went to the Cavendish. Then I met an Indian called Taylor and got interested in nuclear motion. My nuclear motion started from this trip. And I met O’Kelly(?), the discoverer of the K particles.

Weiner:

This was all in this last trip.

Occhialini:

‘37-‘38. On this occasion Goldhaber wanted to have a friendly talk with me and we went into this Indian restaurant near the Round Church at Cambridge. I wanted to tell the story of Goldhaber.

Weiner:

I think Goldhaber explained the story of the work that he did in detail — the relative proportion of the work — and he made it quite clear that he wrote the full paper.

Occhialini:

It is very funny. Chadwick and Blackett had a very great influence on me. They encouraged me on a line which I never betrayed — both of them, for opposite reasons — never to sign a paper which you have not done, even if your life depended on it. This is the lesson which I learned from Blackett and from Chadwick. I am very grateful for this. At least my young people are raised right.

For history this is very important about Blackett. Blackett in this was a grander person, Blackett was magnifico, more than most people. Not for the fact that he is a man who can use brains and hands, but from a certain attitude towards life which is with declamation. He is a very honest man and really my life has been this – what I wanted to say before about fear – I don’t like to think that I’ve done mistakes. The man who writes me a post card to point out one thing from four pages — this is what I call to be a father. So that now I divide people into two parts — the people who had a father, and the people who had no father. All the people who came out from the Cavendish had fathers.

What about the othera? Ask me questions on who had a father and who did not have, and then I will be able to let you see the difference. People who have no fathers are sometimes out of the direct thing; sometimes they are geniuses, like Einstein. But people like Heisenberg, Schrödinger or Pauli certainly had a father; they certainly were in a surrounding. There are people born out of nothingness and sometimes they are extremely clever, but they lack this temperating element, which is the fear of what their father might say, or even they hate — for their father, and so they react without asking suggestions from anyone.

Weiner:

This also fits with the other comment we were talking about before, about close relationships of individuals working together. There are brothers and there are fathers, and close relationships stem from having the same father. You were talking about brotherly love earlier.

Occhialini:

You are right. My association with Blackett — he always treated me like a younger brother, I always perceived him as a young father. I always admired him. The fact of having a parallel political attitude — I always found that my political attitude was very very naive in comparison with his mature political attitude.

With Powell again, it was the same situation. We had a political attitude which was in communal, coming from the same place, which was the Cavendish. This tie exists. Sometimes all one’s life one wears a college tie. It is invisible, but you wear it. I wear the Cavendish tie, very secretly. I wear the Manchester tie. They tell me: “You have never been in Manchester.” True, but I think I have a right to wear the Manchester tie. I wear very openly the Bristol tie.

Weiner:

The Manchester tie stemming from the Geiger-Rutherford tradition, or for what reason?

Occhialini:

They had two Fermi photographs. They published them. They were the proof that there existed unstable particles which were not mesons. They were heavier. During two years they went on taking photos and didn’t get anything. At this moment I was exposing plates in the new Pic du Midi. I think my wife wrote to Blackett telling him that at Easter I was going to go to Pic du Midi and, “It looks absolutely evident to me that either these particles don’t exist, or you should do something about them on a mountain. You should bring all the apparatus to a high mountain and take it away from Manchester where it has become a kind of museum instrument.”

Weiner:

What year was this?

Occhialini:

It was the year of the Como meeting. As you know, we physicists count years by meetings. There was a meeting in Como. The date was ten days before Easter. I said “I am going to Pic du Midi and if you have ideas, just follow this ideas." I posted the letter and said, all right, I have done my best. I had to say it. It doesn’t matter, I have no remorse.

When I arrived on Easter, the director was waiting for me at the station. It was snowing, and he was waiting with the car. He says to me, “Before you came, a letter arrived.” I looked — it was Manchester — and I said, “It’s not a letter for me, it’s a letter for you.” He opens it, in front of the station, and says, “Do you know what this letter contains?” “Yes, it is possible.” “What is possible?” “If we start now, we really can bring the magnet by the end of the year before the next snow starts.”

What happened was simply this. They sent the bloody apparatus. At the moment in which Anderson confirmed those particles they were themselves producing the evidence for the biggest of all of them, which is called the cascade particle. So it was done in the nick of time. This is Blackett. It looks very very simple — you receive a crazy letter from a lunatic who says to you that you must displace 4,000 material, and who tells you that I am going to be there in Easter, and please, if you are interested, write me. And just reply “yes” — that’s Blackett.

Weiner:

That explains the Manchester tie.

Occhialini:

Yes, that explains the Manchester tie. I can claim that Blackett and I pushed this magnet up. This was the Wilson chamber which was standing up there, with a 20-hour life. What they succeeded in doing really paid. Otherwise they would have been rubbed off by the ignorance of the American scientific public about whatever happens outside the States — the cheerful ignorance of the American people…

Weiner:

That relates to our conversation about politics.

Occhialini:

All right, now I’m ready for what you want to know.

Weiner:

Let me ask one clarifying question: when did you leave the Cavendish? Which is really to ask, when did Blackett leave?

Occhialini:

Blackett left the Cavendish practically soon after the paper of February 1933. He was made a Fellow of the Royal Society, which was long overdue. Blackett, believe it or not, was not a Fellow of the Royal Society when I met him, I think. You can check. No, I made a mistake.

He started building a chamber for measuring high precision. The English bug for high precision contaminated him, so he started building a new chamber with a big magnet which was a double-arc magnet and so on. He was still in Cambridge. I cannot place why he was doing it. So that I was left very much alone on this cleaning-up of the gamma rays.

Then there was the meeting in Zurich where the positive electric salts from aluminum bombarded by alpha particles was presented by Joliot. There I brought the photographic evidence and the first measurement of the difference of mass, relative, which was proving the difference of mass of particles.

Then I came back. I did not go to Italy. I had the depression of being jobless and very bitter from misunderstandings. Blackett asked me if I was going to Italy and I said I was not going back to this bloody country at all.

There was a very important thing happened. I got from Scherrer, I think, 100 Swiss francs to add to the money which helped me… In Zurich I did the mistake of my life. Due to a long time spent with Racah(?), who was trying to convince me that my situation was not so bad in Italy and also was trying to straighten the story from me, I could not meet a young Indian who wanted very badly to meet me. I was feeling bloody guilty. My refusal to meet him was looking weak, which I was simply under great stress. The young man was Babha.

Weiner:

He was in Zurich?

Occhialini:

He was in Zurich at this moment. I talked with him. He wanted to spend one evening with me but I had to say, no, no, I was engaged. Then I came back with Viki Weisskopf. Viki Weisskopf, as I tease him several times, lost the Nobel Prize in one night.

Weiner:

In what way?

Occhialini:

Viki Weisskopf was coming back from the meeting and we met on the train. We went to sleep in Brussels. There was no place so we had to sleep in the same room. I was terribly excited by this question of positive electrons coming out from alpha particles. He said it was simply gamma rays reconverted. I said, “Don’t kid yourself. I studied enough with L. H. Grey. Please let’s sit together tonight and try to think what it might bel.” I said “I cannot do it alone, I don’t know physics, but if only we sit down, you might find the thing.”

I teased him and when I reminded him of this he said that I was right, that if he had been chained and if a person obliged him to think he would have found it. It was induced by radioactivity. This night you gained your night’s sleep and it was lost.

Weiner:

This was coming back from what meeting?

Occhialini:

From Zurich.

Weiner:

He was in Zurich then because he was Pauli’s assistant.

Occhialini:

But he was going to London for some reason. He went to London not with me. I met him. I stopped near Paris in a French city to meet a friend and spent there 48 hours, then I came back and between Paris and London, I met Viki Weisskopf and we were forced. It became a legend that I prevented him from going to sleep. It was only a few months afterwards that I could rub it in him. You might check this. It is a nice story and I know it is true. On another occasion I made the same speech to another person who did not refuse to lose his time for tea and got something for his trouble.

Weiner:

I will see him [Weisskopf] this summer in Geneva.

Occhialini:

Then Blackett was halfway to Birkbeck.

Weiner:

He was offered a position there.

Occhialini:

He was offered a position and he said that if I wanted to go with him he would have been very happy.

Weiner:

Would that have meant, for the first time now, a properly paid position?

Occhialini:

No. It never occurred to me that he was saying what you are asking. This is what happened. When I arrived there, a few days afterwards I received a telegram calling me back. My mother was ill.

Weiner:

This was September of 1933?

Occhialini:

Yes, my mother was ill. When I arrived they told me it was a false alarm. Then I went to the Lab and Blackett told me he needed the distribution of positive and negative electrons. I mixed two sets of photoelectrons. I was petrified one of them was 700 gauss and the other was 600, so that the curvature existed in a different story(?)… I remember doing this measurement in the physics laboratory — my mother was in Genoa, my father was in Vienna — I was called by telephone that my mother was dying of — what was it people died of before penicillin and sulpha were invented?

Weiner:

Hepatitis?

Occhialini:

No, See now, Freudian, I forget the name. I came back and life was completely different. I came back to England in November.

Weiner:

Had you accepted the suggestion of Blackett to come with him by that time?

Occhialini:

Yes. It was a terrible period. A spring had broken inside — and Blackett — he was very cross in this period. He did not properly understand.

Weiner:

What was the strain in the relationship with Blackett at this time?

Occhialini:

I was putting the finishing touches to a paper on the positive electrons produced by radioactive —? I was spending a lot of my time in the Cavendish, so Blackett felt maybe my soul was in the Cavendish?

Weiner:

Why were you spending the time in Cambridge?

Occhialini:

I don’t remember. He did not understand that the loss of my mother had broken a spring. There was one person whom I wanted to see in Cambridge. This had nothing to do with physics. If I had told him this he would have accepted it, but I simply could not tell him for the simple reason that the situation was complicated.

Once we had a tempestuous scene, in which Blackett, very moody, was sitting in a corner, and his wife was standing near. My greatest friends, a typical anti-Lady Macbeth — if ever there was a man who got support in London from his wife. Greatness for men is very very simple. Any man could achieve greatness if his wife helps him. Very very seldom are they helped by their wives. Mrs. Blackett was telling me, “Look here, you don’t have a job. Chadwick would be very very happy to give you a job. He is very satisfied with you. Possibly you would love to work with Chadwick. It would be consistent… Why don’t you say so?” I said, “Look, this is the most ungenerous accusation people could do to me. I am not as young as I used to be. Something has happened that broke me.”

Weiner:

This clarified it, I assume, your conversation with her about Cambridge?

Occhialini:

No. If I had simply said, no, I certainly want to tell you that it is not a question of wages. The simple idea of me getting a cushy job in the Cavendish just — there was one point. I was supposed to have the Wilson chamber working again. I was working as hard as I could but sometimes I would drop, occasionally, in Cambridge. My job was to change this chamber. This is the Frisch period.

Weiner:

A whole group, a Spanish fellow was there, and a number of people.

Occhialini:

There was Ehrenburg, Frisch and myself.

Weiner:

Wasn’t there someone from Spain?

Occhialini:

There was a young man named Nahmias. I remember that Christmas of ‘34 — there was Herzog with his wife. (Herzog is now in Belgium, directing a very big laboratory of Shell or something of this type.) I remember that Christmas we went to dinner at a place in London. Before going to dinner, Frisch, Ehrenburg and I went to Woolworth and we bought each one a present for the other.