Giuseppe Occhialini - Session III

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ORAL HISTORIES
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Interviewed by
Charles Weiner
Interview date
Location
Professor Occhialini's apartment
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This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.

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In footnotes or endnotes please cite AIP interviews like this:

Interview of Giuseppe Occhialini by Charles Weiner on 1971 May 16, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/31789-3

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Topics discussed include: Bruno Rossi, Gilberto Bernardini, Ettore Majorana, radioactivity, Antonio Lo Surdo, Antonio Garbasso, Lise Meitner, Ernest Rutherford, C. T. R. Wilson, John Cockcroft, P. M. S. Blackett, Gleb Wataghin, Gian Carlo Wick, Franco Rasetti, Enrico Persico, Dirac's theory, nuclear physics, Emilio Segre, cosmic rays, James Chadwick, Cambridge University, Shimizu, George Gamow, Frederic Joliot, Cavendish laboratory, P. L. Kapitsa, Hans Geiger, Maurice Goldhaber, Victor Weisskopf, David Frisch, Ehrenburg, Carl Anderson, Guglielmo Marconi, Louis de Broglie, P. A. M. Dirac, fellowship from National Council of Research, Arthur Holly Compton, Surgio de Benedetti, Giulio Racah, Sergei Vavilov, University at Sao Paolo, William Bragg, Cecil Powell, sigma star, and pi-meson decay.

Transcript

Weiner:

This is cassette 3, Side 2. I’m resuming now after being away, coming back on May 16, 1971, in Professor Occhialini’s apartment.

When we left off five weeks ago, we had talked quite a bit about, more than your biography, but about Cambridge and the Cavendish you’re your impressions. We weaved in and out with your own story, and at the same time, the background of it was the Cavendish. I took you on a lot of excursions into your impressions of people, which was important and interesting as well. We had gotten to the point of the final period in England. This was, as you remember, a little complicated. There were lots of impressions that you were talking about. We were almost at the end of that.

A couple of things that were lacking to me in that were certain facts and dates. It would have been easier for me to understand it if I had asked you to give some dates. I would like to start with that and then fill in a few specific questions I have. Let me list them right now.

Occhialini:

Give me all the questions so I can avoid repetitions. Also, if there is something which requires a bit of concentration, then I will know.

Weiner:

First of all, you told me that you came back from Italy in November 1933. By that time you had accepted the position that Blackett had asked you to take, that is, to come with him to Birkbeck. You told something of the financial circumstances of it; you told something of the psychological difficulties you faced right after your mother’s death, and also the rather complicated thing of tension with Blackett in terms of your position. You went into it as much as you felt was necessary, I think.

Occhialini:

More than necessary.

Weiner:

Perhaps, I don’t know. That is just about the point we reached. Now I want to know the dates.

In November, does it mean that when you returned from Italy, that was your first time to report to Birkbeck? Secondly, when did you leave London for Italy where you definitely were coming back and all of that was over? Third, of course, the circumstances of the decision. Then getting back to the positron story, some specific stuff, I know the paper was published in March.

Occhialini:

18 March.

Weiner:

Yes, you have good reason to remember. All right, the paper was published on that date. We didn’t really talk about some of the straightforward facts, the step-by-step thing, about communication. If you did, I don’t remember whether you had been in communication with Anderson, how you first learned of his works. We know that you didn’t see the photographs because he didn’t publish them until six months after your photographs were published.

Occhialini:

Eleven days afterwards.

Weiner:

But they weren’t published until later, were they?

Occhialini:

They were published on the 1st of April, 1933. Actually, in print, they came out before photos, for I think that on March 19th in the morning the bloody English press made a lot of stink about it.

Weiner:

While we are on this, why did they make a stink about it? Your article appeared on the 18th.

Occhialini:

It was more than the article had appeared. It was brought to the National Academy of Sciences. If you publish it in another newspaper, you send it. When it appears, it appears. When you bring it to an Academy since it is published, the discussion of the paper, if people take notice of it then it starts existing on the day which it is brought to the Academy. In this case, people were rather interested. In the morning afterwards, on the 19th, my landlady, in a very despising way, woke me in the morning and threw on my bed a paper, saying, “You work and so on, but people who live here with you, they don’t know anything about you.” It already leaked out to the newspapers as many things at this time — whatever happened at the Royal Society was generally covered by the newspapers. These photos had been shown, the paper had been presented, and it came out in all of the newspapers. I still have it maybe some place. I remember I sent them to my mother and some way they sent them back to me.

[Interval where Occhialini looks for clippings.]

I forgot their existence until this moment. This is something which really goes back in time. It was recovered by my wife when my father died.

This was June 8, 1933.

Weiner:

Who is this to and from?

Occhialini:

This is Professor Peroka(?). This I never read. I guarantee you, it is the first time. I told you I don’t shave in front of the mirror and I have a lot of difficulty in looking behind at papers, it is a kind of phobia.

This is Professor Peroka(?) who was in Turin, and in a way marks the date, for it says: “And through my son I heard about the judgment of Blackett about your son, and also the project that Blackett would have of bringing with himself your son in London. If things are standing like this it should not be difficult to find for your son a new fellowship that Marconi (afterwards he said) should not refuse to him. What you said about your son surprises me very much for afterwards Marconi said no difficulty should have made bitter the staying of your son in Cambridge.” And so on, and then he says if I want to come back I can have a place in Turin.

When my father died, all of his things have been collected by my wife, and she brought them here all in boxes. I did not see them. She put them here. These are the clippings which my mother collected. This is something which I sent to my mother, 8 September, ‘32, New York Times [reads clipping on cosmic rays]

Weiner:

What is this one about the discovery of the positive electron? This is 5 March and the paper was the 18th or 19th?

Occhialini:

This is 23 February 1933. This was Italian, “Official Communication to the Royal Society of Britain. The Italian Occhialini declares now that the mathematicians shall have to create new theory.”

This was sent “With compliments” and so on, this was sent by the library to my father who was buying books there. This is February 18… [reads clipping]

Weiner:

Cambridge Daily News, February 18, 1933.

Occhialini:

“It was yesterday communicated to the Royal Society of Science.”

Weiner:

This was all in Italian papers as well. I would like very much to copy those.

Occhialini:

“Science section may change, Lord Rutherford, positive electron, Dr. Blackett flung at the crowded audience the proofs of the existence of the positive electron even though say there is no such a thing.” Then Cockcroft, “amazing photo”… “Lord Rutherford unable to be present.”

Weiner:

How come?

Occhialini:

He was unable to be present. He didn’t come.

Weiner:

Not important. (Laughter)

Occhialini:

This says who was there: Professor Haldane was there, Professor Milne, Dr. Cockcroft, Dr. Blackett… Neither Chadwick nor Rutherford were there.

Weiner:

It is interesting that accompanying the article is one photograph which is Rutherford’s. The date is February 17, 1933. Was it the London Times?

Occhialini:

It was the London Times. It says: “Last night” so possibly it was February 16, but this gives you the thing. I’m very sorry it came out so conveniently. I give you my word –

Weiner:

This is about Kapitza’s laboratory.

Occhialini:

“The Mond Laboratory joins union.” I asked to get whatever had the Rutherford name on it so I could send it, since Rutherford was here. This is an interview with Lord Rutherford for the Morning Post… (reads part of clipping)

Weiner:

I would really like copies of these because they are all together.

Occhialini:

This was the second part when Chadwick who had been a bit maybe out-of-date… “The Atom. Science’s third particle. Finds cosmic rays about particle. British science, they exist. Credits Dr. Anderson. Says America should not be robbed of the thing.” This was 17 of February.

Weiner:

Was this in reaction to the British papers which would tend to emphasize the British part of it.

Occhialini:

No. New York Times, 17 February.

Weiner:

It is the same date. It must be based on his talk then.

Occhialini:

The day afterwards when I received one telegram from Marconi saying, please, send me a letter and so on. So I sent him a letter. I also sent two photographs, and I was a bit upset when these two photographs came out in Ricerca Scientifica, the National Council of Research thing. There too, I said — I remember the last phrase for I posted it and wrote it practically at the station in order to send it out — “without any theoretical evidence we suggested that confirming the early —”

This is the kind of thing which I was thinking the other day, while I was talking about you, I was remembering that there was this and I said I suppose that this is the kind of information in which you might have been interested.

Weiner:

Yes indeed.

Occhialini:

This is the Crocodile Laboratory.

Weiner:

I have seen it.

Occhialini:

It gives a bit. “Lord Rutherford is obviously well known. He is big bluff, often brusque, with a shaggy moustache,” and so on. “The common man often thinks of him in connection with the brilliant kind of youngster whom he often attracted in Cambridge,” and so on.

Weiner:

This is from the New York Times Magazine, May 21, 1933, “A New Workshop for Atom Smashers,” but it is really about the Mond Laboratory, so there is nothing to be smashed at the Mond Laboratory.

Occhialini:

They sent this to me since I subscribed in ’33 asking them to send to my mother anything which was said about Blackett. This was a news service.

This is by Lord Rutherford, April 1933. He gave all the bag of tricks of what had been done.

Weiner:

In a public lecture you mean, or an article?

Occhialini:

He was so kind, he gave all the credit to Anderson… From my father’s file, this photo is from l948. My father included it, this photo is my daughter in 1951. So my father has thrown it together — it seems it has been a bit of a treasure thing.

Marconi… [Italian reading] This says that they gave me the money. This I did not know. This is the handwriting of my father. It is the first time that I lay my hands on it, for the reason which I explained to you, is to say that I’ll not go. March 8, 1933. I had my other fellowship and this came exactly at the right moment. I remember that I came one evening to a party and I was absolutely in despair — no money — and then I met one lady there and I decided that I could marry her if she could keep me.

This is “vittorio fasciste… Corbino.” I have never seen it. This is the speech of Corbino.

Weiner:

What is the date of this? What does the Fascist date translate to?

Occhialini:

Anno 12 — 1934.

Weiner:

This is the one where he talks about Element 93. I must have a copy of this.

Occhialini:

My father wrote my name on it.

Weiner:

What does the title of this say — “Vittorio fasciste”?

Occhialini:

Fascist Victory in the Field of Culture.

Weiner:

And then it says: “A great Italian scientific discovery which opens the path to the transformation of matter was announced and illustrated.”

Occhialini:

“This is the work of Fermi. The case of uranium is interesting. It seems that 93” and so on. “The creation of Element 93 is of great importance.” Then it speaks about the Congress of 1931 about which we were talking the other day. I want you to believe that I did not know that I had this, for otherwise I would have looked for it.

Weiner:

Let me get the name of the newspaper on tape.

Occhialini:

Journale? You can have a copy of this.

Weiner:

That is what I want.

Occhialini:

[Reads in Italian] “The study of the nucleus now starting, aims the ambitious design to give back on the earth the youth of the matter… After three years we can form now that this ambitious design.” This is 1934 for reasons which I will explain to you.

It says that “Artificial radioactivity discovered by Joliot and Curie and the manifestation of youth communicated by nuclear shock to the old matter stabilized: [reads in Italian]

Weiner:

What did you just say about the culmination of three years work?

Occhialini:

It had spoken about radioactivity and solar energy and so on at the Congress of Volta in 1931, and now, after three years, I have the pleasure to confirm it, and he is talking about the work of Fermi.

And here, the prime celle(?) was given to Dr. Occhialini.” The prime celle was given to a research assistant who had done well.

Weiner:

By whom?

Occhialini:

By the state. A prime cella means it had been instituted many many years before and every year they were given to an assistant professor. To a young man they were giving a prize. This was actually the first prize which I did receive which was 3,000 lire. Which, believe me, was something. It has been the best thing which I have ever received… To receive among a generation of research assistants this prize, I remember gave me more emotion than anything else which happened afterwards.

Weiner:

Let’s put this one aside. That’s really great. I have Corbino’s speech at the 1930 Rome meeting and I’m trying to translate it piece by piece.

This is Illustrated London News, 11 March 1933, again based on the Royal Society talk.

Occhialini:

This is the photo for which Blackett got — I don’t remember whether it was 50 pounds or 100 pounds — and half went to me.

Weiner:

Yes, for the newspaper. Now, when was the first photo published or was this the first?

Occhialini:

The first published photo was published in the Royal Society.

Weiner:

What was the date?

Occhialini:

16 February, 1933. This came out one month afterwards and maybe — “The existence of such a particle was first suggested by Dr. Anderson… Mr. Blackett says this photo shows about 23 tracks, mostly of very light(?) energy, many of them pass through left(?) plate.

Weiner:

Read slowly so I can understand.

Occhialini:

“On top of the photo two of the tracks are bent markedly to the right showing that they are due to the positive electron. The large white blob on the photo is elevated. The cause of these remarkable showers of particles is obscure but they are probably due to the disintegration of atomic nuclei brought about the same way, by the cosmic radiation.”

Weiner:

Let me ask you while you are doing this: one of the articles talked about no theoretical considerations involved. In Blackett’s Nobel Prize presentation to him, they said that the shower discussion and those ideas were based on the theoretical ideas of Dirac. I am trying to figure out where this is introduced in the game — that on the origin of the positrons, the collisions initiated by high energy cosmic rays — this was discussed in terms of Dirac’s holes, pair production and so on. This work was described in the paper which appeared in March 1933. Now where does Dirac come into it? I’m not redoing the Hansen thing. I just want your account in a straightforward way.

Occhialini:

That is all right, I will review the argument now.

In a group of photos like this, you find out that there is a divergency of particles — part of them are positive and part of them are negative. And that they always are positive; they cannot be protons — you don’t know this. This is something in the nature of particle cognizance for this moment: they are not existing.

Then you say a positive electron exists — number one. You can start from there and ask yourself how it matches with what you know in nature. You can take the Anderson and Rutherford way and say that this is a nuclear particle, and the existence of the neutron means that the proton can be a composite particle with a positive electron, and from this you start reasoning in a certain way. Or, you can take the attitude that Dirac is right. These particles are not existing in our laboratory here but they are created by something. They have a very short life then, and they disappear and so on.

So there are two steps in this reasoning. One is that you are forced — and I put it very nicely in the letter which I sent to Marconi. I said, “We have been forced independently from any theoretical argument to assume that there was a positive electron, confirming the paper of Dr. Anderson.” This was a private letter sent by me. I did not know that it was going to be published, and I am very happy that it was not slap-dash because it was private.

Now, this must be kept with the fact that no one believed very much in this theory of Dirac. If they had believed in this theory of Dirac they would have been looking for these particles.

Second, a few days after I had written this letter, prompted by a telegram — the telegram said, please send some news to Marconi of what you are doing. After all, I had been living on my own very much… for if you send it to Marconi you have some reasons for receiving another fellowship. Otherwise, you are living in this kind of super-isolation.

Weiner:

Who sent you this telegram?

Occhialini:

My father…

I repeat again, I received this Bohr postcard on matter, which was received maybe by Blackett, nearly certainly Blackett, which was ending with this phrase: “Still I must say that even if the positive electron exists, I don’t believe in the theory of Dirac.” Signed Niels Bohr. So Niels Bohr did not like the positive electron and so on.

When I write this private letter to Marconi and they tell me that this letter is for receiving a bit of money for living, if I am prompted by the idea that the most powerful people in the world say that the work which proves the existence of a particle maybe is not in order, at this moment I start. So I was preoccupied in my letter and also in my declaration which appeared in the newspaper to state that contrariwise to Professor Bohr that even if the theory of Dirac was not right this would show the existence of such a particle, which maybe had nothing to do and had not the characteristics of the Dirac particles. Do you get the idea?

Weiner:

You wanted to make it independent of Dirac.

Occhialini:

I wanted not to make it independent for this would not be fair, but I wanted to unhook it, which is not the same thing. In a way, if the theory falls, the particle falls, no. If I had seen a thing of this type, and when Anderson has seen it, he does not talk about Dirac. He did not know. You look at the short paper of Anderson you will find that he does not talk about Dirac. This is to say that they were absolutely not ready to.

The Dirac particle went into existence the 16 of February 1933, for it was in this moment that there was a group of people who stuck out their neck. I’m not so sure if Bohr had this attitude. I do remember that I was preoccupied for my real survival. I was owing a lot of money to a young lady. There was a moment in which I was contemplating marrying a woman who had money and telling her that I was marrying her, even though she was older than I was, so that I could pay my debts.

I was preoccupied, thinking that in Italy maybe all these people were connected with this kind of not-belief, these official people of the directorie, might destroy the work. They might say, all right, now we shall wait for more confirmation.

First, you see this. Then you say, this is a positive electron. If you are a cultured person, then you look at the literature and you find out that someone has already thought about it, and that they have given the properties. Then you go on deducing the properties. This, I feel, that Blackett and I have done very successfully, that is to say, our blind confidence in the directorie led us to go farther than Dirac himself had gone in his paper. Let me find something. [Interval] It is called the neutron existence. This is by Joliot and Curie.

Weiner:

Was that the paper they presented at the Solvay meeting?

Occhialini:

No, no. This is a collection of which was edited then. Then, in 1932, I had the privilege of meeting one day Cockcroft at the Laboratory. It was near Eastertime. Blackett had gone away for a few days, and the chamber was working. There were going to be holidays of some kind. Then Cockcroft tells me, “I am going to Paris by car with Webster. Why don’t you come with me?” So I took a decision to go there, and Cockcroft was going to give lectures about the disintegration of the atoms by protons.

This is extremely important for I arrived in Paris dressed as I was. I had a leather jacket, I was invited to lunch in the wake of Cockcroft’s reception. There I met Prince de Broglie, Duc de Broglie, all in striped trousers, and they consented to invite me. And then I met Joliot, Irène Joliot, I met Auger, I met Rosenblum, and so on. These three or four days that I passed there gave me a tremendous excitement in everything that was happening in French physics, for I did discover that these people really made problems. They were telling them to me. Then I did receive this present from Joliot. One of them was given to me and another one was given to Cockcroft…

Then the things of Cockcroft and mine were mixed. The thing in my hand passed Cockcroft. It remained on my table for a certain time, and a month afterwards, I started reading it again, for they had been asking me at Scienza to make a paper. And I had to talk about neutrons too. I wanted to be fair to the French people, then I started reading it. You see it says Occhialini and so it was mine. I started reading, reading it, and then — this is not my handwriting. This is the handwriting of Cockcroft.

Weiner:

I can tell — yes, it is.

Occhialini:

Then I go on reading. [Reads in French from text.] I think the signs were done by the same hand. So Cockcroft gave it to me. This remained as a kind of indication… I said to Blackett, “Look here, What is if here?”… “Hell,” he said, “This is the positive electron…” At the last minute, when the paper was being written, we decided that the situation was such that a kind of unusual step for Blackett should be taken. We should include in the paper this observation and we should also include that the anomalous absorption and scattering of gamma rays over 2 million volts was due to the creation of positive electrons.

There is another one which is by Joliot which I got afterwards, which is the positive electron — he did come out. But this is amusing, for Cockcroft had put this. Cockcroft had marked the point that there was the disintegration. These two people had on the same photo the neutrons and the positive electron. In this condition you should not be surprised that we knew that you could produce this thing in a laboratory. Having this information on hand it should not be surprising that at this moment I went into retirement, I did not send a letter to anyone. For taking into consideration all the gamma rays, I had the impression that in the one month that it took to write the paper for the Royal Society, anyone who had a gamma ray, if they did believe in it, they would have found them for I was absolutely sure.

There Chadwick did not follow completely. Chadwick was still stuck to the idea that these things are coming in a kind of funny way by a splitting of protons into two particles. If this was so, then it was necessary to have neutrons. Oh this basis I asked Chadwick for neutron sources, Chadwick was not — well, we entered a bit on this pigeon hole that he had found that this radiation has some funny properties. Thinking afterwards, I did discover what were the funny properties and the funny properties were the paraffin. He gave me the source but with the condition… that I should put paraffin. I wanted to put lead. So this see-saw went on up to the moment that one day I took it upon myself — I threw away the paraffin, and I bought, for the first time, the lead. Then I see the first.

Weiner:

Do you recall when this was? You don’t have a laboratory notebook do you?

Occhialini:

Everything has been destroyed.

Here it is: “The Council of the Royal Society recommends the following Cambridge man for election into the Society, Dr. Patrick Blackett, Kings and Mandarin College, Lecturer in Physics.” This is Cambridge Review, 10 March 1933. That is to say that Blackett was elected to the Royal Society twenty days after this. [Reads from clipping…] You see that Rutherford here has been always very very preoccupied in not hinting at the Dirac theory. Why? I cannot say why. But I can only say that maybe — “Mr. Blackett, who is well known for his great experimental skill and ingenuity, will be one of the youngest members of the Royal Society. He believes that this is his last year in Cambridge and that he intends to take up a research post in London University. Cosmic radiation.”

Weiner:

Let me ask this: when could you say that you heard of the Dirac theory in the context of Dirac’s own theoretical work?

Occhialini:

I heard it from Professor Persico who, when the paper came out, called Racah, Bernardini and me in his studio to explain to us, saying how amusing and how wonderful it was. Since then I have known about it. Dirac was in Cambridge, but this does not mean that he was extremely appreciated as a kind of genius. There was, I think, the same attitude about the Dirac magnetic thing that there was about the 137 of Eddington. They were considering that he was extremely gifted, but I don’t think that anyone amongst the people who mattered in England had confidence in this. The first one who had confidence was actually Blackett for he said to me one morning, “I called Dirac” and he explained to me, “I don’t understand, it makes sense.”

As of today it is difficult to believe that in a small collectivity like Cambridge there was inside the theory, and the big people did not. From the other side, while the paper was being prepared, Gray and Tarrant came to me and they heard about this. They said, well, we have a source… and we hear that you have some ideas about what to do with gamma rays. Then I say, all right, here we are, after all this work, all this suffering, I rush to Blackett and said that Tarrant and Gray put their source at your disposal. They brought their big source and I took one and one half days exposures — the chamber was completely white; the source was very very strong, so that the magnetic field — going in the wrong direction you didn’t see anything, and they were half serious about it. In fact, you find out in the last paper of Gray and Tarrant that they passed their source on the Wilson chamber on to see and that they did not see absolutely anything.

Weiner:

When was this that they came to you with the offer of a source?

Occhialini:

It was between January and February. It was a few days before the paper came out in the Royal Society. It took some time to find out the gamma creation of protons and electrons because of the fact that nature is done in such a way that everything which goes in this direction can come the other way. I was full of doubts, and it was only possible too to do it Anderson’s way, by putting a plate. I had a lot of trouble in making the chamber work.

This is April 1, 1933. “Further evidence for the positive electrons. In a letter today in Nature new evidence is given for the existence of the positive electrons. Earlier this year Blackett and Occhialini found the positive electron. They have now been joined by Dr. Chadwick who found the first experimental evidence in England of the neutron. From their joint experiments it appears these positive electrons are produced when neutrons —”

You see that Rutherford does not talk — “In the latest advance Dr. Chadwick has been bombarded with the neutron gamma rays and googlie electrons were produced. But what was responsible no one yet knows.” Well, it is eveident that there were. Incidentally, if you are interested in history, “I have no idea what this discovery will mean, Dr. Blackett admitted after his lecture, saying that he was anxious that Dr. Anderson should not be robbed of the credit of first having suggested the idea. If it does upset scientists’ theories then the theorists must revise them. Our job was to find the particle and we did.”

Weiner:

Now, in this, for example, does he mention anything about Dirac?

Occhialini:

If you will not stop me, then you will know.

Weiner:

OK.

Occhialini:

The second thing. “Fit Atomic Theory,” “[title] Incidentally, Dr. Blackett said his discoveries fit extraordinarily well with the atomic theory with which the young Cambridge scientist P. A. M. Dirac caused a sensation before the British Association for the Advancement of Science in 1930. Lord Rutherford, under whose guidance Dr. Blackett made his experiments, said there is no doubt that this new method for extending our knowledge… in general, there seems to be strong evidence for the existence of a light, but the whole phenomenon is extremely complex, and a great deal of work will have to be done on it.” This proves that Rutherford was not feeling on safe ground — this means that this jumping on the Dirac thing was dangerous.

Weiner:

You mentioned that when Blackett had a phone conversation with Dirac —

Occhialini:

No, I said that for this phone conversation I was not present and it is not my habit to recount. I said that I have seen the postcard on this paper and it has been for some time in my possession, in which Bohr was saying a phrase which I reported to you, “Even if I don’t believe.” Then, a few days afterwards, Professor Garbasso died. I went to Italy. Now it is clear, I had been silent for a long time. I was not any more an assistant at the university. I was very much preoccupied for my future. From the other side, I felt that the less that was said at this moment about this thing the better, and I was tied to the fact that this work belonged to Blackett. I did not feel that it was in order to send a private letter to anyone about it. My natural inclination not to write letters, my laziness, went together with this desire — if you don’t say anything, you’re not in this. I said to Blackett that I would send a report to Marconi as a private letter and I was very surprised when Marconi, without asking my permission, took out the first ten lines and then started by saying, while the complication of the phenomena connected by atomic rays was understood, how photography had revealed a tremendous complexity.

Weiner:

When was that publication of the Marconi excerpt from your letter? You don’t have it here?

Occhialini:

No, of course I don’t have it here. One year ago there was a thing of Bruno Rossi, and Bruno Rossi had had a kind of philosophy. He said that he had to give a lecture by radio, and he had to put my views in. He sent me a paper which had these views. The views were to me distorted, for he said that I left Florence so that I could put counters in this experiment, which was not true. In my letter to Marconi I said that when I arrived in Cambridge, Professor Blackett had proposed that I put together the technique which Professor Rossi had taught me — there was, I remember, an absolutely baroque phrase, but you cannot do any writing in Italian — and the technique which this undisclosed master used to produce cosmic rays. I did not want to leave anything. I found the paper, I made a Xerox copy, and sent it to Rossi. So I know that it exists somewhere. The source, I think, is called the Ricerca Scientifica which is the place where all the papers of Bruno Rossi were published and where the papers of Fermi were published. The date might be the 1st March.

Then I went to Florence when Garbasso died, while I left the first photos of this neutron stuff. I came back, more or less in ‘33 I pass in Rome, and I met Fermi and I met Segrè. I met Bernardini in Florence. Bernardini said to me that Bohr does not believe in it.

Weiner:

How did he know that?

Occhialini:

I think he knew out of the fact that Bohr should have communicated it either to Majorana or to Fermi. This was confirmed by Segrè. I went to Rome and I said, “Look here, boys. It matches with the thing. There is nothing against. I will tell you something more privately that neutron and gamma rays should give it. There is a paper at this moment.” I said that there was now the evident experiment to do. When you believe in the positive electrons and you know about the theory of that actually you can either take this evidence here — Let me see if I have something here; this has been sent to me by Picard.

Weiner:

When was that trip, by the way to Rome? It was after Garbasso’s death?

Occhialini:

It was after Garbasso’s death. It must have been the 5th of March 1933. I rushed there. It was absolutely useless to go there. I remember that I went away at night in less than an hour, and Chadwick brought me to the station. There would be my passport adviser. It was a very difficult thing to go to Italy. You needed always a series of advisers.

Weiner:

You say you talked to people in Rome.

Occhialini:

I went to Rome. I travelled by train and must have arrived on the 7th. I spent one day and one night in Florence, then I went to Rome, then I came back to Florence. I remember when I came back to Florence I came back during the night from Rome, I arrived very very tired. I had had lunch with Racah. Years afterwards I said — I had met Fermi and I had met Segrè — the only thing I could say when I came to the station was how good was the pies which I had eaten at Segrè’s house. I was completely conked out. I had been at the Cavendish during the night with Chadwick, who was lending the source, and all this time the situation of remorse about the people in Florence. The man was suffering from leukemia, which then was a kind of unknown thing.

Weiner:

Remorse about Garbasso?

Occhialini:

Yes, so I sent a letter to him and Bernardini told me that the letter had been the last joy of Professor Garbasso, and this cleaned the slate. Otherwise I would have felt that maybe they would not have accepted me any more in physics. Everyone of us was loving him very much. Garbasso learned about this work from the newspaper.

Weiner:

The newspaper account of the Marconi excerpt from your letter?

Occhialini:

No, for the Marconi one wasn’t for the newspaper. But I have shown you what happened in Italian newspapers the day afterwards which I did not anticipate. You understand I did not anticipate. Generally when you bring a paper to an Academy it is sometimes an act of good faith, for you bring it in open discussion. Sometimes it is a smart gesture. Sometimes you even borrow papers in an Academy. I would have expected that I could have brought it to the Academy, then the day afterwards I would have said, “Well, look here, boys, to the Academy it is now this, this and this.” Then, I did not expect that it would create any stink. I had been living during the past two months with this kind of secret and I didn’t expect that they would. So I was taken by surprise when I found out that the British press made such a stink out of it. The reaction was the reaction of my landlady — I was owing her 60 or 70 pounds — she might expect to be taken in some confidence. “You didn’t tell me anything.” She was very very cross. The comment of Bernardini was to the point, “You might feel you made Garbasso feel that he was an old man. You treated him as an old man.” It’s easy if I had been sending it to a review I would have packed the thing, sent it to a review, get proofs, and the moment I got proofs, then I would reveal it and so on. As I have said, this is a bit of the neurotic loyalty of the Italian people that we have been always in some way divided, I think I explained to you. It is our destiny to be divided always between two fidelities.

If, by any chance, someone had then produced at this moment, had taken this decision, of photographing gamma rays as anyone could have done who had a Wilson chamber. You will understand when Bohr says I do not believe in it — if you had announced it to Bohr before, then he would have gone to everyone that he didn’t believe for and he would have said, “I was very…” They explained to me, Bohr goes around, talking and expresses his worry. During one month, he is going around expressing it, everyone knows that Professor Bohr does not believe in it. So we say, “What about doing an experiment to please Professor Bohr and prove they don’t exist. Let’s try gamma rays.” Now, this thing of Joliot came rather late. It came when we had already this and already this.

Weiner:

That’s what I wanted to ask. When did you take this trip to Paris, this last minute trip with Cockcroft and Webster?

Occhialini:

March 1932.

Weiner:

1932? This is before?

Occhialini:

This is not about the positive electron. This is March or April, let us say, to be sure, to be safe, I don’t have my ticket.

Weiner:

This was already in print — the Joliot article on the neutron?

Occhialini:

This is a collection of papers which came out in Comptes Rendus.

Weiner:

Reissued by Hermann? It’s a series.

Occhialini:

If you look at the series you’ll see here Gerring’s paper in which the photos are shown. [Turns pages.] I don’t know if it is this or if it is this or what it is. But the idea was that neutrons, they were producing disintegration, and then gamma rays in the center of the mass and so on. But, as I said, this thing did not attract the attention of Blackett until the moment when everything was ready. And so, we say in the paper that it is possible to produce positrons by other agents which are not cosmic rays. One of the possible ways is by gamma rays impinging upon, and then, it should be Mr. Gray and Tarrant and Chou have discovered that when you bang gamma rays against deuterium(?) material, on the gamma rays you have scattered radiation which exhibits one spectrum which goes from half a million volts to one million volts. We might interpret this radiation by saying that this radiation is connected with the absorption of the gamma rays in the production of a pair — I’m quoting verbatim but I don’t have the paper — and by each successives it reappears as an aniculation. The first time really that aniculation has been spoken about is there.

First of all, you have to know that about this kind of gamma rays there was two schools. One was the school of Meitner and Grufeld. They were finding that there was a radiation of the same energy, so they had no place. While Gray, Tarrant, and Chou were finding soft radiation which was isotropic. How, in Cambridge there was a certain tendency to assume that this experiment of Gray and Tarrant’s should be taken with some salt for the fact that they were involving a lot of correction for absorption, reabsorption and so on. They were working with a pressure chamber and so some correction was necessary. While the work of Meitner and Grufeld was done with a Geiger counter, so it was very simple. People had a tendency to believe in this radiation, and in believing the evidence of Gray and Tarrant, and also Chou, who was a young man that in a short letter to Nature produced the evidence that there was a very strong absorption. The absorption was increasing with the energy, and that radiation going in this direction was detracted, and then if you look around and looked spectroscopically at what was coming around, it was found radiation which had the absorption coefficient which we might attribute to the gamma ray of half a million volts. We made a mistake, we thought this aniculation could have been done at many energies and then you should have a continuous spectrum… the negative proton has a tendency to aniculate when it is stopped and so it is captured and then it bangs out two gamma rays at 180, and it is a three-body. When it arrives and it meets another electron, the result is the composite neutron and you have the gamma ray with two electrons, they disappear. They got half a million each…

I want to make it clear that this thing there has absolutely nothing to do. It only proves that of the people who had been working radioactively, for example, the person who might have discovered it was Skolbetsyn. He had a Wilson chamber with a magnetic field. Feather had a Wilson chamber with a magnetic field.

So you do understand now what I was telling you about Feather telling to poor Hanson that this is complete nonsense. The people who might have discovered it were — if he had had a magnetic field, Auger, if he had been working in gamma rays; Skolbetsyn, who had started the measurement of gamma rays to the electrons; and most of all, Alexander of the Cavendish Laboratory. Another one was Champion who had a Wilson chamber with magnetic field of Blackett.

Weiner:

Now we have filled in some of the gaps. We didn’t have this last time.

Occhialini:

I did not have this last time just for the fact that I did not have this thing here.

Weiner:

The scrapbook?

Occhialini:

No, this thing here. And last time I had been noticing the absence of Lord Rutherford and of Chadwick, who had not had time to come but I was not sure. Now there is a newspaper where it says that they were not present and this might reply to a question which you had made, “What did Lord Rutherford say at the Royal Society?” My reply was, “He did not say anything for he could not come.” He had other engagements. And what did he say the day afterwards? The thing was important, but he did not refer to Dirac. So, you have been asking me, did Blackett say about Dirac? Yes, he said — first question. Second question — did Bohr believe? No, sir, he did not believe. How do you know? For I have seen. But everyone knew about it, now everyone has mercifully forgotten.

Weiner:

No, not historians, because the letters of Bohr and Dirac which are voluminous, say the same point.

Occhialini:

All right, excuse me, but I did not read the letters. I only read a letter to Blackett which was absolutely up to the point. Apparently I would not be surprised if Bohr had scared a bit Rutherford and Chadwick for — it is very very funny that in this paper there is everything, for there is also the mysterious nature of what was happening. In the story of cosmic rays, we must have looked through the photos, we should have. You must invent something which is a nonionizing link. The nonionizing link was the gamma ray, which was coming in the shower production by the bremmstrahlung that was producing by the gamma ray that was flying and then producing another shower.

Weiner:

Let me ask two questions about this. One, again about Dirac — was he at the Royal Society meeting — either you remember or you don’t?

Occhialini:

I don’t remember.

Weiner:

Do you recall any conversations with him personally, either directly with you or through Blackett during this period? You mentioned vaguely about one phone call, which I’m not sure how that fits in.

Occhialini:

I did not mention about it. If I said this, I don’t remember.

Weiner:

Then I must have misunderstood.

Occhialini:

I didn’t say a phone call. I remember the postcard and I took the postcard with me. I remember, for I will tell you, that I was very angry for I was feeling that this was like a persecution against Dirac. But it was not so. It was only the kind of ponderous way of Bohr to grind.

Weiner:

It also fit in with other problems and ideas he was working on. Don’t forget he was concerned with the whole structure of what had not yet emerged as quantum electrodynamics or relativistic quantum mechanics. He was in the midst of working out these ideas at the time.

Occhialini:

True, it is correct.

Weiner:

Let me get back to my question: do you recall any specific contact with Dirac at Cambridge during all of these months that we are talking about?

Occhialini:

No, I was too busy in knocking the (???) together. To handle the Wilson chamber was really an art — it was an earth-shattering jump for me. It could go only 2 minutes.

Weiner:

You said you were working night and day.

Occhialini:

I was not working night and day in this epoch. I was working afterwards when Chadwick had the key of the Cavendish and was coming in with me.

Weiner:

You couldn’t work at night without a special key?

Occhialini:

Nothing at all. No one. There was a standing rule by which at six o’clock the lab was closed, and at twelve o’clock on Saturday the lab was closed. Do you want to know one or two amusing stories about this?

Weiner:

About following him through the window?

Occhialini:

No, no, since this was the rule and he told me the rule, Blackett convinced me very very speedily that the time which people spent in the lab they could spend it at home doing homework. He was completely convinced that this was the right way. This was a kind of time-honored rule. I would not be surprised that in year and year, very few times someone worked there. But when was it? It was when Chadwick provided the source of neutrons, and he was employing it during the day. Then during the night it could come. Since he could have the key of the lab, he was accompanying me. It was the time the chamber was refusing to work. I remember that I was taking it down, which was not an easy job but it was a job that I could do alone. I should change the gas, I should clean… I would boil new gelatin to put in a certain position, and so on — all the kind of magic which you used to do with the Wilson chamber when it didn’t work. Then, I remember that last evening when I went to see Garbasso, Chadwick took me to the house of a girl student and I knocked at their door. She came down and gave me my passport for she had gone to get the passport from my adviser — then passed a proctor, and I got away.

The girl was a foreigner and she was asked by the authorities — they wanted to kick her out for she was living in this silly Cambridge status of licensed for the University and so she could not have the key of the house… she could not come out after ten o’clock and so on. So they said a lot about this girl, Miss Torrelli — I never met her anymore. She was rather gay, the good sport, maybe a bit of a loose girl, and she had gone to get my passport. When they made the report, to another very poor Italian girl, who was living there, very devoted, they gave the accusation. So there was a lot of stink about it, and they think it was a riot. But then they told me this, I said — I had come back fifteen days — by then, I know what happened. I went to see — “It was you?” “Yes,” I said. “Can you prove it?” “Yes,” I said, “I can prove it, from Dr. Chadwick’s company. Professor Chadwick was with me in the car.” They made all this scene that the car had gone, the girl had walked out. This was the story.

On the other side, Blackett was always against, and he gave us as a good proof that the theory was right that one should not work on Sunday, for in Manchester, a few years afterwards, people were allowed to come on Saturday. Saturday at 5 o’clock — they had a big neutron detector, a little pile to detect cosmic rays and neutrons — then, there was a moment in which this detector gets mad. They put it down, they work, and after ten hours succeed in having it work again. When they put it down, it was in order. It was only a few weeks afterwards that they knew there had been a great solar eruption on this Saturday. Out of taking it down they had cut the story of the phenomenon. So Blackett says: “You see what happens. If they had not been working on Sunday, the thing would have come on. They would have gotten the nice story of the maximum with all the rest, whereas the information was partly lost, of the biggest event of all of them.” From the other side, he was against doing work just for the fact that he was afraid.

Weiner:

What prompted this was my question about discussions that you might have had and so forth, and you pointed out how busy you were. And you made the point.

Occhialini:

I made the point, and I will make more the point that Dirac always terrorized me. My English was difficult to him; his English was difficult to me. I was meeting him in the house of Blackett and I was always finding him rather — even afterwards, years and years afterwards, I remember that he was wonderful — he could play. I remember when they played with scissors. He solved at once a kind of problem with scissors. When Mrs. Blackett asked him, “How did you do it?” “It is a simple theorem of topology. It was a string you should have got a certain way.”

So all the talk which convinced Blackett that Dirac was right was strictly done by Blackett. So I am not in the condition to testify. This phone call of Blackett you must have got it from some other part. Phone-calling now is quite free. Phone-calling between country and country was something which was not done. There was no money for this, so it would be very surprising.

Weiner:

Dirac was there, which is why my impression was completely wrong, because if Blackett is down the street from Dirac, why would he telephone? So it doesn’t make sense.

Occhialini:

Not only, but Blackett invited Dirac one evening to his house so that they could have — and then there was several talks. I will give you more.

Weiner:

This is what I was trying to get.

Occhialini:

If you would see the photos, you would find that in some of these photos that you understand. They come like this. In some of this conversation, Blackett told me, “You see these big blocks” — they called them blocks — “Dirac, now that we have proved that this positive electron exists, got appetite and he would like these blocks to be magnetic monopoles, but I’m not going to be stampeded by Dirac.” This was the amusing part. Then, in the paper which Blackett had done in the period in which I was in a very troubled, unstable state — after the death of my mother — then he examined the problem of these blocks and found then that they are completely in agreement with alpha particles, abetted by emanation and spread by diffusion in such a way they would look like caterpillars. This was the period. Since I haven’t it and wanted to say something for all this, I talked to my wife and she explained to me, something.

As I said, there was unpleasantness with Blackett —

Weiner:

After a break for refreshments —

Occhialini:

I shall have something today for you now. It was very simple.

Weiner:

We are talking now about the circumstances of leaving Birkbeck —

Occhialini:

We are talking now about Birkbeck and London and my stay. My passport when my mother died had expired. I was born in 1907 in Italy, you are supposed to do your military service at 18 years. If you are a university man you can do it up to the age of 26. 26 is the last date at which you can do it. In Italy, while you are under military service obligation, you could not go out during this period of military Fascism. In order to leave, after my mother died, I had to work 25 days, going to Rome and so on. They were saying, no, no, no.

I succeeded in getting out, because I received an invitation to go to a meeting in Leningrad. Then I brought the invitation to go to the meeting in Leningrad — out of this I obtained the passport, and since the passport was valid for Leningrad, it was also valid for some other part. The passport, however, arrived so late that I didn’t go to Leningrad.

Weiner:

What would have been there?

Occhialini:

It was a meeting about cosmic rays and Blackett had said that he did not want to go and he said that I could go myself. I would say that my life would have been different for, as I learned afterwards, if I had gone to Leningrad they would have asked me to remain there for they knew that I was in a difficult situation in Italy. And then, maybe, the person who wanted to have me will comment on me and some men who work on neutrinos will come.

Weiner:

Ivanenko.

Occhialini:

Not Ivanenko. The telegram was signed by Ivanenko, of course, by the boss. But I don’t remember.

Weiner:

Anyway, the passport came too late for you to go there.

Occhialini:

And then I came back to Blackett and I could start again, but the limiting date for my coming back to Italy was in May 1934, so then I could in November go to the military school. So I was obliged to leave Birkbeck, and this was one of the points.

The second point: if I would arrive in a certain epoch, then I would be reintegrated in my place in the university. Otherwise, if I was coming back and starting military service, I would have lost any seniority and they would have given my job to some other people.

Weiner:

Here you’d been in England since 1931, you had made a name for yourself, did it occur to you to scrap the whole thing in Italy which would have had the advantage of not having to do the military service but also meant giving up the security of a proper university position and perhaps finding one in England? Were there any prospects at all?

Occhialini:

Yes, I’m sure that there were prospects, but it did not occur to me out of the fact, which repeated itself again in my life, that being the son of a university professor I could not leave without exposing my family to a very difficult situation. After all, consider the weakness of my position. I had had a fellowship from the National Council of Research. They gave me afterwards a second one and a third one. Altogether I received 20,000 lire, which lasted two years and a half — nearly three years. So it is $3000 for three years… it was good going, as I told you I had been finding other money. There was a friend of mine who had money too which he sent me as a gift, and then years afterwards, I gave them back to him. But, like many Indians who come to the United States on a fellowship, I felt that only if it had been a situation — after this, if I skip my military service, I cannot come to Italy any more in my life. It is equivalent to saying that I cannot meet my family. This is the true explanation. If you want to rightfully analyze the thing and ask, will you tell me please was it for the fact that you were tied to a kind of world of honor, my reply is: “First, I could not give to my family this kind of situation.” Don’t forget that Fermi never denied Italy. In a very discrete way, he as an academician, went to Stockholm, he had the Nobel Prize, and then he went for a short period to the United States. There was no scandal. There was nothing.

Weiner:

He never resigned his professorship to this day.

Occhialini:

I don’t know. In my case it was different. Here I had the duty of military service; people had obtained a passport for me against the rules for I was not supposed to have it. I left in April, towards May, at the same time to arrive before the end of the scholastic year and start again to be at the university in time to be able to swear fidelity to the King, which I had not done before, for two years before it was not required.

It was for this that they kicked me out. This is the explanation. Now that you ask me this other question, now I understand better the meaning of your question, why should not Blackett find you and so on. Even when Blackett was telling me, “well, look here, in February, Chadwick would be extremely happy to have you with him,” it was on the meaning that Chadwick could be willing to have me there, then I could have stayed on this occasion at the Cavendish up to October had I wanted — but they knew that I was coming back. The coldness from the side of Blackett was really affection. I remember that one girl — a German girl who was working in the house of Blackett… having told me one evening. “He is fed up with you. Patrick is completely fed up with you. He cannot stand it that you are showing lack of loyalty to him.” As I said, he was right in a way. But it did not happen more than once in my life that I went against my duty and betrayed friendship just for a lady. It did not happen. I must say, the rest of my life, I just decided I had had my ration of this.

Weiner:

These months, from November, when you came back after your mother’s death —

Occhialini:

It was not November. Let me see one minute. It was 1934. My mother died in September. I did not want to leave my father, who was really prostrated. Finally I had all these trips to Rome — I was combatting this trap and they were asking “Where is your military service?” “All right, I don’t have it.” “What do you mean? Are you a university man?” “Yes.” If you follow a university course, then you can set it back to 26 years. After this, you are declared a deserter.

Weiner:

Let me straighten out the timing. You went there in September. You said earlier that you had come back around November.

Occhialini:

I would say that maybe it was November, maybe it was October.

Weiner:

OK, then you left before the end of May 1934. You mentioned that you came back again in September — for the cosmic ray meeting in October.

Occhialini:

Yes. How did I manage to come out?

Weiner:

Yes, I am curious. You were supposed to be in military service and here you are at another scientific meeting.

Occhialini:

It was to do with Racah. Everyone was going to this meeting and had invitations. So we decided to play it cool, to go, and ask for the passport without stating anything. I stood out of the police in a car with Bruno Portecorvo while Bernardini and Racah went in to get the visas for Bernardini, for Racah (who had driven my car), for myself, and another girl. When they came out — it was 20 minutes — Racah was furious and he started telling me, you have waited until the last minute. “Did they refuse me?” “Yes, of course, they refused.” I did not understand the reason of this clamorousness, and then Bernardini, in the car, told me solto voci how Racah came there, the service was very very sloppy. They had us waiting and then Racah pulled rank. The people at the police don’t know who I was and he brutalized them. Then they give him his, they give Bernardini one, and then they looked at him, “This one, has he done the military service?” They had not asked to know about the others. “Of course, he didn’t,” he said. “Out” — in this way, they took the advantage of him.

But we went the same evening to a banquet in Florence. At the banquet was present the Fascist Minister of War. The Minister of War was a mountain-climber – we were in the middle of this climbing, and we had explored the deepest cave in the world, and I was one of the group. When I was introduced to the Minister as one of this group of explorers of caves of which Racah was a member, Racah said to the Minister, “Look here, this is my friend Occhialini. Could it not be possible to have the passport. You are the Minister of War, so you are the person to appeal to. Would it be possible for Occhialini to accompany us to London? He has an invitation.” This was the end. The Minister called me and said, look here. He was “Podesta,” nominated by the government, the Lord Mayor nominated by the government of Bologna.

Weiner:

You explained it in connection with Garbasso.

Occhialini:

Yes, of Bologna. So he says, “Look here, you come to my Bureau in Bologna tomorrow night.” Tomorrow night Racah went away in the car to cross and to go up by car to England and they brought me. At six o’clock I was in Bologna. At 8, 9, 10, I went to see the Minister and he said, “I have already phoned for your visa, you go to Rome now, you sign I don’t know what, and go and talk to so-and-so and you will get your reply.” Then I took the train, I arrived in Florence —

To make a short story long, it took me two days, going from Rome, and then I succeeded in going away. Racah put in order by his intelligence what his arrogance had destroyed. This is a bit relevant to something about which I was talking this morning. I was extremely happy for myself as well as for Racah, for in his heart of hearts he knew that if he had been soft, smooth. He had been charged to smooth my cards but he had been taken by. So this is the reply of why I got permission for a week to go back to England for this meeting.

Weiner:

While we’re on it, let’s talk about the meeting. Was it worth it?

Occhialini:

I think the meeting was worth it. I remember a rather amusing thing. I don’t know whether it was a joke or not. Part of the meeting’s proofs were wrong: it was written “unclear physics.” I remember this about the meeting.

Weiner:

It was Max Born’s talk and the secretary transcribed it — well, you tell me, because you were there.

Occhialini:

No, you know about it.

Weiner:

And it was supposed to be “Some Remarks on Nuclear Physics,” but the secretary made a mistake and it came out “Some Remarks on Unclear Physics.”

Occhialini:

That’s all right.

Weiner:

I have heard the story a dozen times from different people, but I finally have a document of someone who was at the meeting who wrote a letter to someone else and said, “You should see what happened today,” and he tells the story exactly as it happened.

Occhialini:

I’m not sure that the story is correct.

Weiner:

Max Born’s paper, by the way, has nothing to do with nuclear physics the way it was printed on the sheet.

Occhialini:

Then the story is not correct. Do you want to hear my story?

Weiner:

Yes.

Occhialini:

All right. They give you a group of papers which are like unstuck proofs, which are the papers. And here, like in a newspaper, you had on each page for the start the title of the paper. So, at the bottom of the paper, it was written here, “Unclear Physics.” This I do remember.

Weiner:

Do you know whose paper it was?

Occhialini:

I have no idea. It was a general thing. I am extremely happy that you made this observation for two points. I am 100% sure that it had not to do with the Max Born thing. I’m 100% sure that what I have seen had not to do.

Weiner:

The first paper on the program was Born’s so it could very well have been associated in people’s minds with his paper since it was the cover sheet.

Occhialini:

True, but this was [the way] the paper [was]… Many of the other things were nuclear, but here was…

Weiner:

Running heads, it is called.

Occhialini:

Yes, it is called running heads. Well, I am extremely happy that it has been clear now, that once again we seem to have matched and separated what was possible and nice but maybe not true.

Weiner:

The interesting thing is that the man who reported this in the letter was commenting that it wasn’t clear to him either. He was a chemist, but one of Gilbert Lewis’s students and very close to nuclear physics. He later became a nuclear chemist.

Occhialini:

Who?

Weiner:

Frank Spedding.

Occhialini:

All right. I will say the things which I remember. I remember several of the contributions.

Weiner:

He wasn’t on the program. He happened to be in Europe at the time.

Occhialini:

I remember that Millikan was there, who made a pompous fool of himself. It was the last time I saw Millikan.

Weiner:

What about the subject matter itself? There was a paper on the program where Anderson was either author or co-author, but he wasn’t present. It’s so interesting — you can’t tell from the Proceediags that he wasn’t present, but I know that he wasn’t. I’m just curious if there was any substantial, formal or informal, discussions on any of the things that you were interested in.

Occhialini:

I don’t remember. I was preoccupied in straightening my affairs. I knew that this was the last time which I would go to England. Before leaving Rome, the man who gave me the thing said, “Look here, this is the last time you can go.” He said, “You will be lucky.” I said, “Why will I be lucky?” “Just for the fact that you will be an officer and they will not ask you in the first part to fight.”

I found it was so indiscrete what he said that I couldn’t believe it. He was telling me (???) the Minister of Foreign Affairs that we are going to war with Abyssinia. This was in September. And it was more or less the 10th of September when the crisis started with an incident called (???). So I knew that the doors of Italy were getting closed for me, and I was right, for since then I didn’t come out any more. Without going to Brazil I would have been trapped inside there, and maybe I might even have died as a Fascist hero.

Weiner:

I have my doubts, not about the hero, not about the death.

But about the Conference again for a minute, so under the circumstances you don’t really recall anything that came up?

Occhialini:

I remember a paper of C. D. Ellis. If I’m not wrong, it was the last contribution to science of Ellis. I remember this Millikan intervention that gamma rays.

Weiner:

Well, Millikan was chairman.

Occhialini:

I remember him. He was not chairman because he was in front of me on a chair. I was desperate. This man had been for such a long time my hero, and now, while he was talking, he was destroying himself. I could see this elegant mouth, which he was licking all the time. It was sad, and he was talking nonsense. He got very very cross at the moment I said something. I commented on something which he said behind him just in apt(?) voice, I never stood up. Then he turned himself and he said, “Just so. Yes, yes. Just so,” as if I said something which was in approval of what he was saying when he was completely… I was already destroyed(?), in this moment I was considering that I was out of physics, to do the military service and taking in consideration this kind of tense atmosphere which I found in Italy, and realizing that there was a dusk or an eclipse that was starting — considering this strange life, I was looking at something which I will not need any more. There was around me an atmosphere already finished. Also what had been told me by this highly competent person that we were going to be at war. I was scared stiff for I started asking myself the elementary question which I told you last time about Hell’s Angels. I think I told you that when I arrived in Cambridge, one of the first things that I said to Blackett was that I was anti-Fascist, but I felt this was an intellectual attitude, and that when a war would come, I would become Italian like all the others. It was as a comment to a film which troubled me very much. It was called Hell’s Angels. It was the first appearance of Jean Harlow, and was describing the story of a young man. It was partly an episode in which a young man who had been working in Oxford refuses to — he’s on a Zeppelin and he gives the wrong indicator for the dropping of bombs on London. This put me in a crisis. Having arrived in Cambridge for only a few weeks, I could not understand this kind of tribute to a culture. It was only when the Abyssinian business started that I did realize that I was not an Italian anymore. This helped me to understand all the others — people, like some of my friends, whose names have never been recorded for ever more, who had been good anti-Fascists. At this moment they took a chance to morally fight against the Abyssinian — so providing the kind of support that would have made the contribution to Spain possible had they given the impression to Mussolini that he had the Italian people with him at the moment when he went to take the (???). It was a very great surprise. It was out of this situation that I did understand what happens to a group of people — the so-called poor on the Road to Damascus phenomenon — what happens to Communists who, when Budapest happens, they decide… and I thought there was preparation for a long time, and there was not.

Let me look for one date for Racah sent me — this telegram was sent the 20th of February 1933 anonymously —

Weiner:

Physique in Romona.

Occhialini:

Do you know what ALALA means? Alala was the Apura of the Fascists, so this says: “For the explorer of the Dirac abyss Alala.” This was sent by Racah who in this epoch was rather sympathetic to Fascism. Since we were cave-explorers, the positrons were called the Dirac-holes so here there was a pun about the exploration of the Dirac-holes.

Weiner:

Read it in Italian while we’re at it. It is interesting.

Occhialini:

[Reads in Italian]

Weiner:

And the Alala was?

Occhialini:

Alala — A A A — was the Fascist shout which said… [Interval]

Weiner:

We were talking about the sensitivity to political change. What was the situation in England, for example — in London and Cambridge in terms of the political consciousness of people?

Occhialini:

Very much divided, rather, I think, starry-eyed, but I did not know that they were starry-eyed for they are much more politically mature than I was. They had a lot of political economical education, and their culture was the culture which they got from the fat of the land, that is to say, the progressive people which I knew were reading The New Statesman and the Nation. This was a kind of pink situation. The people in Cambridge who didn’t matter were Tories. Rutherford — New Zealand; Chadwick was a very good conservative. I think that Dee was either liberal or a Tory. I think Gray was a liberal, rather religious. Cockcroft taught me the word “pink” which I had never heard before, when I was asking him what he was, and he said, “I am pink.”

Blackett was of all the red. He was always the red. Then there were people around who were definitely red like — maybe C. P. Snow at this moment had sympathies — I can only gather from the people with whom I was. Feather was a good conservative, the religious type the people who were in charge, were a liberal or a religious type. Dirac, I feel was not political. C. T. R. Wilson was certainly a liberal. Ellis was certainly a Tory. As a matter of fact, he forsaked physics — he became the boss —

Weiner:

Of the industry board or something like that.

 

Occhialini:

Yes, but he was put by the conservative Parliament in the situation. So that I must say of this, the person was Blackett. With the other people it was really difficult to understand — I cannot say that there were many apart from Blackett and Champion. Champion was rather a liberal, that is to say, when there is someone where the pinkness is not coming out, I use the word liberal to give them the benefit of the doubt. Then there were a group of people that were more or less leftist but they did not belong to the physics department.

Weiner:

You mean chemistry and biology and so forth?

Occhialini:

Yes.

Weiner:

What I am really interested in is whether or not the politics of individuals were reflected in any way in policy or in attitudes towards people. For example, was Blackett an embarrassment to Rutherford or did not these things matter?

Occhialini:

No, I don’t think he was, no, he was not. I feel that Rutherford honestly loved him, and even more important, I have the impression that Rutherford respected him. Among the young people, there was a lot of adulation of Rutherford. I remember the coming of Millikan, and then Rutherford asked if there was anyone who wants to ask questions. It was evident to me that he was like the hunting-master, and then local people like Feather asking rather impertinent questions. Rutherford very very pleased… and Blackett, with his pipe at this angle, silent, and asking no questions at all. So that Blackett never took any part in the Anvil Chorus. He was obstinate in his mind and laughing only when he was feeling like it — never smiling for convenience. In the middle of a group of people he was still with a sour face, in the middle of a joke, in which everyone was happy — sometimes a public political joke — for example, when Ellis spoke about I don’t remember what and he said, “After all, this contradicts Miss Meitner,” who was also at this meeting, “Even a lady can drop a brick.”

The notable thing about the man Blackett is that he did not take any part in this kind of thing. I said later to him – I had forgotten the story — “This seems to me like a doghunt, absolutely ungenerous.” I did not like it. And then he burst — he said, “Look here, we did not call that Milikan race — he doesn’t come. When he’s here in the lab, he knows that you are building an apparatus. He did not try to see anything. He did not ask to be shown. He did not ask to discuss. He shows us the first photos — they were the first photos of cosmic rays — and starts by saying: “Since there are people here who want to get results in this direction, I am very happy to show you the results we already got.”

Weiner:

The height of arrogance.

Occhialini:

It is very funny because this was a man who was worshipped by everyone in America as a very religious man.

Weiner:

By the public, you mean, because of his writings perhaps. But there are stories more complex than that. He was in very bitter public disputes with people like Compton at the scientific meetings which broke into the newspapers. He was very much in disputes on scientific matters — and then his style was pretty well known by people in the scientific community. At the same time, don’t forget he was one of the American Nobel Prize winners and a public spokesman for science.

Occhialini:

He was a sanctimonious bastard, this is what I would call him. I had worshipped him for his work on the electron, for his work on the photo-electric effect.

Weiner:

He was in controversies here on the East-West effect and this whole business.

Occhialini:

The controversy was for the fact that there was really a fixation about them being gamma rays. There were meetings in Venice on violet rays, which came, I suppose, in 1934. I had the privilege to sit for a good part of the trip with Compton, and Compton was telling me that he had been practically force by public opinion to start working on cosmic rays. This does not confirm what you say, but this shows you that as a witness I am a bit unreliable, inasmuch as even if I know things, when this kind of thing can be nasty, then I will not talk about that. He said to me, “I could not have all America represented by Millikan so I was forced to choose this field because otherwise we would be left with the fixations, the obsessions of Robert which were making the American situation weak.

Weiner:

When was this — you think 1934?

Occhialini:

You can check it. It seems that a lot of things had been happening in 1934. Let me think one minute. Yes, it was in ‘34, for I explored this cave. I came out alone from this cave. I rushed down. I took a train, and I arrived practically with the mud of the cave on my face in Venice to take part in this meeting.

Weiner:

It was a cosmic ray meeting? I don’t recall a meeting in Venice.

Occhialini:

No, it was not — it was a meeting on bio-genetic rays which was promoted by an Italian who had a stock in it and invented the kind of subject which at this moment people believed, that there were bio-genetic rays influencing — it was biology and radiation, and there people came and said that they had pots with seeds and exposed them in altitude and the seeds germinated quick. Then they put them on the lake and they absorbed the cosmic rays and the seeds are not coming out in the same way, and so on. It was the anniversary of the death of my mother which must have been towards 2 September, and then I rushed down. I remember that I came down to the station all dressed in overalls, with mud everywhere. I had left a change in the station, then I went to my village — it was the first year — to participate there. I rushed away and I went to Venice, where they had already started this meeting, so it was September.

Weiner:

It was shortly after that that you went to the London meeting?

Occhialini:

For then we had a dinner commemorating this big cave, and that was where the Minister of War. It is correct. It checks.

Weiner:

Now, let me ask two other simple questions on the London period and then get into Italy in a continuous stream. A lot of people have mentioned that a feature of Blackett’s lab in London was the discussion groups that he would organize, or that he was involved in, anyway, in London — he was one of the principal figures — in physics seminar groups, where many people like Bethe, Heitler, Peierls who were refugees in various places, would come in along with other people. There were experimentalists and theorists together and some of the people from Cambridge and all over would come. Were you involved in this or was this a different period?

Occhialini:

No. This happened afterwards.

Weiner:

Had you heard about it? Did you know about it?

Occhialini:

Yes, I heard it afterwards in a kind of bitter phrase of Heitler who said, I think to Blackett… and so this particle which had been discussed so many times — when they came all the times, years afterwards, and he was coming to Birkbeck — he said, “There were heavier particles than electrons as I tried to push the idea several times.”

Weiner:

He was referring to those meetings.

Occhialini:

He was referring to the mesotron to the resistance of Blackett to — this was a tragedy of Marxian dialectics. If people believe that history repeats twice, the first is a tragedy, the second is a comedy — any chance of laying their hands on the positive electrons and then they feel that this would happen only once in their life, and next time they were to find something different. So this is the first thing, just the Marxian fear of repeating yourself and so to become comical. Number Two: the idea of particles which change their quality while their speed changes — they become completely different in their quality — is very much like Marxian point, a dialectical particle…

As a matter of fact, years afterward, I went to (???) and said — I was talking general things, where I was heading, around some wine — I was explaining that the Heitler step-by-step creation was a perfectly Jew way of considering how the showers were produced, while the Heisenberg way of the explosion was absolutely — I didn’t say Nazi — a typical Gotterdammerung, a typical Niebelungen, Wagernian view. Then I was referring to this… Patrick was there and said, “I’m afraid that I must give you this. I’m sure that if you’d been present you would have found too complicated and you would have risked.” There is some moment in an epoch, when you are incise, you cannot funk. Sometimes you must decide that it is no use having a reputation if you don’t throw it down the drain.

So he was saying that not knowing Marxian dialectic, it was true, showing always my immatureness in Marxian dialectics, if I’d been still there, you would have gone on — you would not have allowed the dismantling of the small chamber. The small chamber of 3,000 gauss was completely in order to detect what was happening at 150-200 milli-volts.

Weiner:

This was dismantled because of the move from Cambridge to London?

Occhialini:

No, don’t forget that it was taking a lot of current and the current was easily obtained from the Mond Laboratory line which Cockcroft in one night had set up. The coils had been removed for doing something — something very clever, but I don’t know what — and then the chamber was employed as a chamber. Then the chamber passed to the Kensington Museum.

Weiner:

The Science Museum, yes.

Occhialini:

Where a bomb destroyed it.

Weiner:

What was it doing in the Museum? Was it on exhibit or a loan or something?

Occhialini:

It was an exhibit of the first controlled Wilson chamber. It was the Wilson chamber which had confirmed the positive electron, detected the showers.

Weiner:

So this is the story.

Occhialini:

So this is the story. So there is no proof at all that —

Weiner:

By the way, on that chamber, somehow I have the figure that about 700 photographs were taken from the time you started on this positron business in the fall of ‘32 to the time the paper was published. Now, that is a hell of a lot. There was only one possible chamber in the world which could do that, right?

Occhialini:

I don’t think there were as many as that.

Weiner:

I think I got the figure from the Nobel Prize presentation of Blackett.

Occhialini:

Why don’t you use a Xerox? You are different from me, I see, you don’t use a Xerox.

Weiner:

I do, but you don’t know what a problem I had the night before I left. And so, instead of having the opportunity to Xerox the thing, I had to make quick notes.

Occhialini:

I love Xerox.

Weiner:

I will send this to you. It’s from a book, Nobel Prizes in Physics —

Occhialini:

I can find out, yes, I know that it exists. If Blackett says that it is 700, it is 700.

Weiner:

What I don’t know from my notes at this moment is whether it is from his address or from the presentation address. It says: “During late autumn Occhialini and Blackett took 700 photos, confirmed Anderson, etc., showed the showers.”

Occhialini:

It does not say “Occhialini and Blackett”; it says “Blackett and Occhialini.”

Weiner:

Yes, but I was making the notes. It showed the showers, the origins of the positron. Anyway, the interest here is the idea of that many photos. I think the number came from some real thing, and this is production line already.

Occhialini:

I want you to understand, even if you start at 9 o’clock in the morning and you got all the time for the setting and then a certain time for looking at what happens, you cannot take many photos a day — for I remember that when I was on chance(?) taking the gamma rays photos, I couldn’t do much more than take 35, 40 a day. Maybe I was a lazy fool, but we were very poor. Fundamentally, it is true. I hope you will not be shocked if I tell you that for all the cosmic ray photos the expansion was taken by foot-pump. There was not a recevoir, not a condenser, so I had an oil-monometer, and then I went and bought one of those small cars. Then you look at the monometer and you keep it, and you look at the temperature of the water, and there is a moment at which you take out the switch of the feed, otherwise everything, looking at the temperature, the water which is running on the coil, 300 amps was a lot. So really I am rather surprised that there were so many.

Weiner:

Well, look at it this way. If you got 20 a day and worked for 35 days over a period of several months, you got it.

Occhialini:

Yes, but there were Sundays; there were Saturdays; Saturday mornings; then there was the point at which for five days the film we wanted broke the counters. I do remember now the story that Blackett… “what can I do about it”… I said: “Do you want gold,” he said, “Maybe must be done in a noble matter…”

It was only after when the rush for the positron started then I bought for 2 pounds 10 the cylinder, a motorbike, I finally bought one… and then I bought an old car… it was really paradise… you need only to turn a switch. I remember when I left, Chadwick, very kindly, said that since I was going to London and the motor was belonging to the Cavendish, he wanted to know if I wanted to sell the pump, for they would find it extremely useful — but for what, it was a free gift.

Weiner:

I’ll send you a Xerox or send you a reference to it. It’s not an issue but it seemed like a big number and I wondered.

Occhialini:

No, I think, taking into consideration the fact that they had wanted procreation, then there was the fact that as Blackett very aptly said, at the moment at which this chamber was starting to get the best photos which we could, we stopped. We stopped for the neutron gamma ray rush and so on, and we stopped out of a strategical declaration of Blackett. The declaration was this, well, we seem to have taken so many photos. I think it is, at this moment, unlikely that something will turn up that demands to take — maybe what is wanted now — not only, but we beggared with it. I don’t know if you know this English word.

Weiner:

You didn’t say bargained.

Occhialini:

Buggared. There was one moment in which we had the idea that if we put the two counters between, then you admit only something which comes true, well maybe we should put it on top — then we lost the physics for you are losing all of them — they are coming bang, bang, bang in such a way that practically you are getting this. Then we beggared it; we spent time for we laid the — before the lead plate in — then there was very heavy contamination, then we had the tungsten. With tungsten we could not take good photos, then tungsten out, and then you find out the way, the cradle in which you put the tungsten… This photo which you see there was taken — it was one of the last. When this was taken, it did clinch it, and then we could start looking at all of them to see what it was. This was the moment at which I said to Blackett, “This is the moment at which you must stop the evidence which you have.” I said, “Now, we have got to get better cures(?),” and then he gets a big magnet, and then he starts building a big chamber for getting momentum, good measure of momentum, and so on. In my opinion, I was very bad tempered about it. At this moment, I did not know why I was bad-tempered. I was assuming that I was bad-tempered for the fact of being left out. No, no, now I have decided that I was deadly right. I did not want, out of the absence of Blackett, if something good was coming from this work, I should have to have a fight with Chadwick, as I had, as I had.

I might find the paper, Chadwick and Occhialini, in which there is a big line, put by me with an arrow, and then in the corner is written P. M. S. Blackett. Chadwick had already decided that, after all, Blackett had been so busy.

Weiner:

Was this a reflection of some hostility of Chadwick toward Blackett? Did this stem from anything that had gone on in the past?

Occhialini:

No. It was evident that they were different temperaments, but fundamentally there never was, at all, word, there never was things — there was someone who lambasted Chadwick, the one who was lambasted by Chadwick was me.

Weiner:

On this issue?

Occhialini:

Yes, on this issue, if you want, for the simple reason that with my respect for Chadwick, it took me some time. I could not call Blackett in at this moment. It took me some time to substitute lead to this so that while we went out first, the special relation became — everyone had been, Joliot and in Italy… and Chadwick was practically throwing the blame on me… The point is this: Chadwick did not believe that gamma rays could produce pairs.

One night when we had a discussion in the lab, then they said and explained a group of things, and then I’d seen him. We went to his house where I left my bicycle. He was prematurely old this night. He had understood that fundamentally it was this — he was the Chadwick, and I was only a poor country boy, just a small auxiliary who had had the chance to — we worked an experiment and so on, but he still was the Chadwick, and the man who knew how the world was made. It was only months afterwards that I could reveal the way this had been working. Even at the moment of writing the paper there was a fight. We had not arrived at a showdown — it was not a showdown — in this night I showed him — when we came out, he said to me in the car, “So, I could have discovered the damned particle three years ago.” I said to him, “My dear Chadwick, I have a lesson here which I shall leave to the young men of the future, you cannot discover anything if you do not see it in the apparatus and if you don’t look at the photographs yourself. You cannot ask anyone to do checks for you.” You cannot discover if you do deputize. “After all,” I said, “you have never laid your hands on the Wilson chamber so you could not.”

It was still used. In the first paper, there is one phrase I had it in the paper still, an alternate part of the paper. I then phoned Blackett and in some way I met Blackett. I went to meet him for he was — you know this kind of crazy thing of Deans and Students, at the moment they are asked, they are in some fields in some bungalow lent by a friend.

Weiner:

Or a lake in Scotland.

Occhialini:

I do remember a long drive by car and then I remember this thing in which I said, “Chadwick feels this and this.” I said, “On this I cannot agree. It will be surprising to you both to see this young man and so on.” Blackett said, “OK, there are gamma rays.” “Well,” I said, “if it exists the gamma rays, then there is this kind of evidence from neutron passage in the matter which is a part.” And then I said, “If you keep your bloody evidence” — this is the moment at which I got very cross, I didn’t say “bloody” to Chadwick — “If you take the evidence to yourself, then you cannot ask me to believe on your word, anyhow.” He asked what was the evidence. Then I explained to him the evidence. I heard myself say in a very cold way, “Well, you see, Chadwick, this evidence seems to show that the neutron is not a particle.” “Oh,” he says, “but it is.” “Yes,” I said, “but this means only that here is something which happens but it does not show that responsible for this is a thing called positive electron.” You see how it could happen. I then discussed how it could happen for I said, this is a mixture of gamma rays and so on. Up to now, I put the thing and I had the thing coming from lead, and then I got a little needle and put lead in the middle of it…

Then there was the Royal Society in which he said that this kind of thing was unknown… and I found the courage to get up and say that I put a source of gamma rays and I could see them coming. He said, “As far as I can see they come from every part of the chamber. They don’t only come from the source.” So this is sketchy evidence.

I derived it on the train, something which I developed for taking the photo I saw that it was curved the right way and it was losing energy in a plate of aluminum — very very thin — and he says: “It is true, but it is an old trick.” “Yes, it is an old trick.” “It is the start.” “No, it’s not the start.”

Weiner:

This was all in public before the Royal Society?

Occhialini:

This was all in public. It was very short. We said a couple of words…

So really it is the tragedy of people sometimes who know too much against the people who know not enough, I must say that I considered this as my greatest hour. The idea was that while thorium C — was maybe able to create positive electrons, maybe the energy was not enough to let them be seen as particle, their paths and so on. It was for this that knowing that there was a gamma ray of the other 5 million volts in borium — beryllium radiation that I got the source. Then I went in again on it. It is evident that when you have neutrons and you don’t know very much about what neutrons do in the matter, I suppose it is as intelligent to assume that they can produce gamma rays on this occasion as at the same time they produce pairs — also, if you believe in pairs. This is out — this conversation is out.

Weiner:

I’m sorry you didn’t tell me. I could have taken the microphone out. You will have a chance later — it can just fill in my background.

Occhialini:

That’s all right.

Weiner:

It seems to me that this is a Portecorvo kind of childhood experience for you.

Occhialini:

What is the Portecorvo?

Weiner:

You told me the story about in Pisa as little boys. When someone reacts to a fundamental question it brings out…

Occhialini:

Did I show you my postcard of Brazil or not?

Weiner:

I wonder. I’m not sure.

Occhialini:

Down from the mountain for I want to enlist. I was black for I’d been in the sun for a time. I have a pair of moustaches for I wanted not to be too different from Brazilians, I was black like this. Then I went to the Ambassador. I say, “I’m so-and-so.” “Do you want to apply?” “Yes.” “Which is your reference?” I say, “I have only one reference which is here and maybe you might use it. Here are the group of people, and let me translate for you this postcard.” Then I have the postcard. I translated for the person. And I gave it to him and there was also an English attaché. I said, “This is the document.”

Weiner:

So, Fermi, Bloch, Carelli, Bruno Pontecorvo.

Occhialini:

Gilbert Bernardini, Racah, de Benedetti, Gian-Carlo Wick, Bloch, Ugo Fano, Loria, Eduardo Amaldi, Leo Pinthila, Emilio Segrè. And I say look here, Fermi, Persico, Fermi, Bloch, Rasetti, Bruno Rossi, Benedetti and Segrè — they are in America — they write me here a postcard which is addressed in a jocular way “To the Rebel Exilated.” It only means that in their opinion I was not completely in agreement with the world as it was in Italy. So I beg you, take the names of these people to introduce me. He said, “Can I have the postcard?” I said, “No, you cannot have it for I might want to use it. I might want to use it with the French ambassador.” He wrote to these people and then told me the information that… the English ambassador said that it is evident that people like Chadwick, Blackett, and Cockcroft can testify about me but they cannot testify up to 1900(?) when I was there. But these are the people that can testify that I have value…

Weiner:

You can repeat the question.

Occhialini:

The question is the very simple question of my going to Rome.

Weiner:

While you were working on the positron —

Occhialini:

No, I went back to Italy in such a way that I could straighten up what had happened to me while I was in England and I could just explain the kind of political scientific situation in which I was and for this I needed time. [Break]

There is one accusation which is in the temperament of Italy. It is defined with the story you give yourself airs. Is it English?

Weiner:

It is an English expression.

Occhialini:

Very very seldom an Englishman would say about another Englishman that they give themselves airs, you see. The Italian very very easily when they don’t understand a certain situation will always attempt to exchange awkwardness, timidity, for “giving themselves airs.” For example, Pelui is a person who is extremely vivacious, very intelligent and very quick in repartee, and so I heard about him, “he is giving himself airs.” Another one who was giving himself airs was a splendid person called Bruno Touchette. Many of these people which are unknown and which in Italian culture cannot exactly absorb or make up, rather than to say we don’t understand it, they say “we don’t understand just what the facts are.”

My position was very delicate. The point is that I was bitter for this Fascism which was happening to me. But I decided to go, for I was under the impression that my friends would think that I was giving myself airs, that if I was going to get a job in England I was suffering from a swollen head. Then I came back and discussed it with Bernardini to whom I explained as much as I could. One of these newspapers because useful for it said “You did not say a single word about Florence, about our Florence, about Italy.” I said to him, “Look here, there is one of these papers in which it is said that I come from the place where… Please, have a heart, you must understand that I am not the type of man who will take to newspaper men, and so on. I didn’t talk at all.” Then he said, “You should have talked about Florence,” but I said, “I did not.” Then, when I was in Florence talking to Bernardini, I had the feeling that I had better go and see Fermi and all the others in Rome.

Weiner:

What is the month and the date on this one?

Occhialini:

The date is March of 1933.

Weiner:

Just when all the newspaper articles were —

Occhialini:

Afterwards. Garbasso died a few days afterwards. I wrote a letter to him and then I went to Florence when I could. But consider that I was taking all these bloody photos for gamma rays. Blackett was interested in another direction so I could — I left anyhow. I left the Wilson chamber in the hands of a young man there who was new, and I went away. I saw my friends in Florence, I tried to explain, and Racah was the most understanding. I found that Rossi was not there anymore. He had left for he had won a chair in — Racah was the most understanding of all for he was the less romantic and the coolest. I did then have the impression that I’d better go to see Fermi and the others. It seemed to me absolutely evident that a kind of situation — they didn’t know me — I had the impression that there was arrogance on my side, a swollen head, and this I was very much afraid of, for it was not true.

Then I went to see Fermi in the morning at 8:00. I said, “You don’t remember me.” Fermi said, “It’s all right,” and we went there and we were discussing these photos most of all with Segrè. Then Amaldi showed me what he was doing. Segrè invited me to lunch at his house, and then I took a train, came back, and went to dinner. Racah was waiting for me. Racah asked what took place. I said I phoned them. “Why did you phone them?” “That I was not changed,” I said. What did it matter? What the hell — Fermi had never met me and what should he care if I changed. You understand — there was this difficult situation which was made sharp by the death of Garbasso by the idea that I might have killed him.

I was not bitter with anyone of them for that. After all, Garbasso was in a very strong position and he might have stopped this decision of sending me out just for the fact that I did not ask for renewal of my salary. I have people here all the time and I know that there is a moment at which the university tells me, “Look here, you have people outside. What do you do?” That’s all right — what I do I say that they will be coming and so I take it on myself. So it is true that it was Fascism that has been more authority, but taking into consideration what had happened, I knew that a group of people who were living in an extension of the university had organized the thing in such a way as to remove this scandal of a person who was officially anti-Fascist, had a job, had not sworn fidelity, and was not belonging to the Party. For in the meantime had came the law which —

Weiner:

But as long as you were away you were not visible.

Occhialini:

Yes, but if they kick me out — as a matter of fact, then I came to the University and the rector called me and said, “Look here, we have found a way to help you.” I said, “You give me back my job?” “Yes — on the day you come back we give you back your job but we take the assumption that it happened on this day, and then, of course, you must do what in this time has happened — you must swear allegiance, and you must get the card.” “All right, I shall think about it.” This was in March 1933. When I came back in September when my mother died, I found among my papers, my card, my signature imitated, done in the village in which I was born. I don’t know through what corruption it was made, but after six months it was done. There was one date in which this was possible. It was evident that I was letting the date pass.

They said, “Come back,” and when I came back one year afterwards in March, May… It was a very difficult period. First of all, there were certain things which I wanted to do, and it was not a lab that was built for this. I got some money, but it was necessary to have — there was no staff.

Weiner:

Who was there?

Occhialini:

There was Bernardini.

Weiner:

He was the senior man by that time, which was regaining the position that he had before?

Occhialini:

No, he had always had this.

Weiner:

But then when Rossi came in –

Occhialini:

No, Rossi had got the job because Bernardini was bound to be in an optical place. So what I found there, Bernardini had already had a job from before when he was in the situation in charge of – not official. Then he had got the official thing and he had got the official thing the same day in which I had done it. He had had it.

There was Bernardini, there was Bucharelli, there was a young man called Lorenzo Emo, Count (???).

Weiner:

Lorenzo Emo went to Berkeley later?

Occhialini:

Lorenzo Emo worked for Richardson.

Weiner:

L. W. Richardson?

Occhialini:

No, he was a man who was looking very much like a Hollywood actor. How do you know about it? He worked on deuterium.

Weiner:

Because I know from the people at Berkeley. He was one of the Berkeley crowd. He was one of Lawrence’s friends and he brought his own salary with him. He had independent wealth.

Occhialini:

Yes, he was related by family to Lawrence.

Weiner:

That I didn’t know.

Occhialini:

I think that Emo and Richardson — you don’t know Richardson so I don’t need to describe him, to you.

Then I started this Wilson chamber building it up. I had this ‘34 which was a real paradise and there I was starting to dream. Then I started my military service which lasted 21 days.

Weiner:

That’s short, isn’t it?

Occhialini:

Yes, I was sent out for bad health.

Weiner:

Which meant what — were you sick, or ?

Occhialini:

I was not sick. I was anguished, I could not sleep. I would fall from the horse, and then they put me in an observation hospital and put people near me to — so I was reading, I was keeping the light lighted and people around me, “We know, anyhow, you can put on the light, we know you cannot sleep.” They put people to watch me and then sometimes by moving I would awake the soldier who was supposed to make a report, and in the end they decided I would not fit in this type of life.

Then they said to me, “Look here, you must renounce,” and they were telling me that I could not anymore be an officer. “This is the last Year. So, you will become — now it is December — in February you will be a soldier. But if you think that you can try still and you can stick, try to stick, for remember you got 27 years to become a soldier and not an officer. It is different when a man is 18. What do you choose?” I said I should be a soldier.

They tell me this afterwards. They said, “Look here, we looked at the law. If you are not taken now you cannot be taken. This is the last month. It must be now or nevermore. So we send you away and we declare you no — inadapted to military service — but we will say that you should be adapted in case of war for they will call you anyhow, and it has got to be sedentary things, you can do ambulance and so on.” This was the thing, so I came out after 21 days of military school.

I came out… after not sleeping for 15 days it was sort of hard, but I was so anguished that I couldn’t really sleep. At the moment I went out the war in Abyssinia was practically started. At this moment I really didn’t realize that if this thing had not been cleared up I would have had to do the Abyssinian War. Then maybe they would even have sent me to Spain. I would still maybe be — of course, not to Spain, they couldn’t, it was voluntary war — but there were people who started the Abyssinian War and then were not released.

Then started the Abyssinian period. People seemed to take it lightly, but I didn’t like it for the fact that the fundamental truth is that from one day to another I find myself alone. This I expect I already told you.

Weiner:

Not really, not in this context.

Occhialini:

Well, politics does not matter. If you have a family in which to gather, then you are not afraid of anything. You live your life and then you retire in your home. To a physicist his home is the laboratory. I was living there from eight o’clock, nine o’clock, up to the evening — sometimes even more — so the people around me, they are my friends, they are my brothers. The Abyssinian bug got them. It was not so evident — but there was this business of commenting on newspapers — so in the end, I attacked my professor, the director of the lab…

I had a very grievous taint — the one of being a man who was very anglicized and that had been a success in England — so that the suspect of being philo-English was against me. This ruined absolutely everything. There it was happening in the newspaper and so on. Then it went on and went on, and the war in Spain.

Weiner:

Did you take public positions? Did you take pubic stands politically?

Occhialini:

I didn’t take public stands, but everyone knew what I was feeling.

Weiner:

In conversation, you would speak your mind, and among friends?

Occhialini:

Yes, yes. I remember the day on which Portecorvo came. Bruno came to visit the lab with de Benedetti. I remember in this day it was like the old time, for here we were three people who could talk about it and talk not in a hard way. But practically, to live in a place which was subject all the time to prohibition and felt that whatever you said was as an unpaid member of the intelligence service. It amounts more or less to this… The people around the lab in the circles, the so-called clubs, they wanted always to have you. They would send you convocation and so I would never go. I never never never went.

Weiner:

These circles were?

Occhialini:

Fascist circles, for example… they would say we noticed you didn’t come… Then there was the last moment when Italy finished the war with Abyssinia. Everyone was called in all the places to hear Mussolini talking by radio. I remember that we had a seminar. When they announced that Italy had finished, and the sirens — the seminar was dropped. People went away rushing. I went to the seminar alone, and then I went to my room and I wrote my…

Weiner:

How about political action during the period? Was there any opportunity for some kind of organized political opposition?

Occhialini:

Not any more. I was very much afraid to go to meet some of the people who in the past had befriended me for they would have known about certain of my past activities. I was who I was. I was writing on the walls, painting on the walls, attacking leaflets — I had a motorbike and I went during the night on the motorbike to stick leaflets. I had one person who was still furnishing the leaflets that he was making for me. No one was attacking then. It was the only one.

Weiner:

Was this during this period or was this the earlier activity you are referring to?

Occhialini:

This is ‘35, ‘36.

Weiner:

But you were saying you weren’t doing anything the way you were in the earlier period. In the earlier period you were active politically.

Occhialini:

In the earlier period I was acting politically but I was acting clandestinely. You could not act politically but I was acting clandestinely.

Weiner:

But in this period you said you were also — this leaflet period is later in ‘35.

Occhialini:

This is ‘35, and in ‘35 I still go on. But before I had a group. Now I was alone, for the people in the university were making a hobby of befriending me, but fundamentally a lot of them — there was this phenomenon of people being anti-Fascist as far as internment policy was concerned, but being very nationalistic about the Abyssinian story.