Oral History

Frank Oppenheinler

When he died on February 3 of this year, Frank Oppenheimer was director of San Francisco's Exploratorium, which he also founded (in 1969) and which many have called the best sci­ ence museum in the world. For his achievements Oppenheimer received, among many other honors, Caltech's Distinguished Alumni Award in 1979. Oppenheimer was a graduate stu­ dent at Caltech for four years (in the early days of Kellogg Laboratory), earning his PhD in 1939. Before that he had graduated from fohns Hopkins and spent two years doing research at the Cavendish Laboratory in Cam­ bridge, England, and the Instituto di Arcetri in Florence, Italy. After receiv­ ing his PhD, he worked with E. O. Lawrence at UC Berkeley and in 1945 joined his brother Robert at Los Frank Oppenheimer: I met Charlie and the photoelectric effect to develop Alamos. In 1949 he was forced to [Charles C. Lauritsen] before I came to energy level systems for those heavy resign from the University of Min­ Caltech, because he used to come to nuclei, which was ridiculous and too nesota and banished from academic the place that my brother and my fam­ complicated. So I sort of knew what I physics as a result of harassment by ily rented in New Mexico, Perro wanted to go on with, which was a the House Un-American Activities Caliente. So, when I got to Caltech wonderful thing for a graduate student, Committee. He spent the next ten that fall [1935], he recognized me as I because most graduates just take years as a cattle rancher in Colorado. walked into the building. He hap­ courses, and then somewhere along the He was eventually drawn back into pened to be right at the door. And he way somebody tells them what to do teaching at Pagosa Springs High said, "Frank, do you want to smell a or they get interested in something. School and from there returned to vacuum?" [laughter] He had just So, almost immediately, I told Charlie mainstream academia at the Univer­ taken the x-ray tube apart. Of course, that I would like to make a beta ray sity of Colorado at Boulder, where he in those days, you used shellac to stop spectograph, since they didn't have directed research in high energy parti­ leaks, and that sort of decomposed. one. cle physics. And it had a real foul smell, even The late 1930s was an exciting though it was full of air at the time. fG: Had you made one? time in physics at Caltech. Politically this was also an interesting time, and fudith Goodstein: You knew when FO: No, but I'd used one. I used the it was Oppenheimer's political activity you came to Caltech that your subject one developed by [C.D.] Ellis. That in Pasadena that was to have such was going to be nuclear physics? seemed a good thing because it was a bitter consequences later on. Caltech hole in Charlie's nuclear physics Archivist fudith Goodstein talked to FO: Yes. I had worked in Cam­ facility. Oppenheimer last November about his bridge on beta and gamma ray spec­ years at Caltech. troscopy, using internal conversion fG: How long did it take to build it?

23 FO: Well, I didn't get it put together seminars took place - at his house? JG: Was it used for a long time after­ until about halfway through my wards? second year, I think. I had to build FO: There were other seminars, but the amplifiers and design the magnet. on Friday nights there was always a FO: I think for a while. I don't There was a local place where we discussion of the work that was being remember when it got to be disused. could get crescent-shaped magnets, done. They would talk about that, It probably wasn't used much during because they gave us a much better and then it would gradually develop the war. field. They were made in a forging into a party of some sort. They just JG: No, I think they essentially shut place down south of Pasadena. said what they were doing, or talked and argued about things. I remember down the lab. I noticed you told JG: Did you actually go into the one time, Jackie, my wife, listening to Charlie that you weren't really learning foundry? this, asked a question. It was a ques­ much about nuclei from the experi­ tion of something about nuclei, and mental approach at the Cavendish. FO: Yes. That's why I know it was everybody just stopped talking and What was different about it? in my second year, because my wife stared at her for a moment, and then and I went and watched him, and they without answering just went back to FO: Well, I think what I was doing had lots of ovens all along with a little talking. [laughter] They were just so was different, because [John D.] cart that went along, and a man with a astonished that some stranger would Cockcroft and [Ernest T.S.l Walton fork would go over and open the door interrupt them. In addition to this, I were learning a lot about deuterium and take out the forging as he would a saw them an awful lot - Willy Fowler and whatnot. But I had done a cake or something, look at it, and see and [Lewis A.] Delsasso also. It was a nuclear level system for radium C, and if it was ready. If not, he'd put it very nice group. Tom Bonner was it broke up, for some reason, into two back. [laughter] It was beautiful to see working mostly with neutrons, almost groups, each with about 12 levels, and that. The research I did was not terri­ exclusively with neutrons. And Char­ I couldn't give assigned quantum bly good. lie and Willy were looking at energy numbers to these levels from the tran­ levels of light nuclei. sition rates. But it was like looking at JG: Why do you say that? the iron atomic spectrum rather than JG: Did you ever find yourself at the hydrogen spectrum. FO: Well, because I thought I had licked the problem of scattered elec­ attracted to that? To going into work­ JG: So your comment was more trons in this by various veins. I was ing with the nuclei of the light ele­ about your own work. looking for a gamma ray from nitro­ ments? gen 13 that somebody had found, and FO: Well, in a way I was, but doing FO: Yes. We did learn - and corro­ didn't find it, but I found a peak in the it indirectly through the gamma rays. electron energy spectrum, which said borated by making the level system - that my apparatus was scattering elec­ JG: Do you remember any interest in that the radium C has two branches. trons. The spectra were good at the nuclear astrophysics on the part of the One is an alpha emitter and then goes higher energies. I looked at the shape Kellogg group before World War II? to radium D. And the other's a beta at higher energies, and it agreed with Bethe's paper would have come out in emitter, and then it goes with an alpha other people's conclusions that the '38 or '39. And, of course, then the emission. And so there's these two neutrino had very little mass. war intervened. But I was wondering ways around that end up with the if they made the connection. same product, and one has to find out JG: Did you have much contact with whether the energy emitted is equal for the other graduate students? I think FO: I think they did, and I think the both ways around. In one case some Charlie Lauritsen's son [Thomas] was groundwork was laid for saying, "We of the energy was emitted through a a graduate student at the same time ought to find out how to measure gamma ray, and the level system you were. some of these cross sections," but the showed that had to be so. technique for measuring the cross sec­ FO: He was an undergraduate, I tions - the sensitivity - wasn't there. JG: Where did you actually do your think, when I first started, and then experiments? was a graduate student after that. JG: That's why, apparently, they As I remember, you'd come into decided to build an electrostatic FO: In that office. Because they the building from an alleyway, and generator. would rush radioactive material, even then over here was the x-ray facility. if short-lived, over from Kellogg. But My office was the second one along FO: Well, the Van de Graaffwas also, at that time, I checked the there, looking out into that courtyard already built when I arrived. Then they apparatus because they had a radon just in front of the Kellogg Lab. So it [Fowler and Tommy Lauritsen] built a source which could put down radium was right where everybody else was. second one. [radium A] that just gave alpha parti­ Then, Charlie at that time, as I cles and decayed to radium C and C', remember, had his students over to his JG: When you left, what happened to so I could check the gamma rays from house every Friday evening, or maybe the apparatus that you built? those radioactive nuclei that I was every other. familar with, and they really gave nice FO: Well, another graduate student, curves, so I knew the thing was work­ JG: Is that really where most of the [E. p.J Tomlinson took it over. ing all right.

24 ENGINEERING & SCIENCE / MARCH 1985 JG: Who made the radioactive finally told us it wasn't doing any paign during my high school years. sources for you? good. We had to cook it to break Then when I went to Hopkins I knew down the vitamin B. [laughter] quite a few people who I didn't know Fa: Well, they had a little facility in whether they were party members at which you could go in yourself and JG: Did it work when you cooked all, but they were interested in left­ collect them on the little buttons you the wheat germ? wing politics, and I learned about it. were going to put in the apparatus. And then a little more on the fringe of Fa: No. JG: So it was a do-it-yourself opera­ it when I was in England, and then tion. Once you made it, you had to went to Italy, and there were people JG: Did you know Thomas Hunt there of varying degrees of leftness. rush right over and use it. Morgan? Occhialini was quite left. Fascism was Fa: Well, those had fairly long lives. Fa: Yes. I didn't know him well. in Italy when I was there - the year But the ones that were artificially But then, von Karman was there, and before the Abyssinia war. There was a made, Willy would make for me. The I knew one of his students, the Chinese brigade of soldiers just below the lab natural radionuclides were used mostly fellow [Hsue-shen] Tsien, very well. there who were always singing and to test the apparatus and the artificial Then there were other people. I knew cheering. ones to learn something new. Frank Malina very well and Sidney JG: Were they dressed in their black JG: Did you get involved at all in the Weinbaum. uniforms? cancer work? What happened with the Com­ munist Party was, I had been close to Fa: Yes. But they weren't threaten­ Fa: No. I knew about it, but I sort of slightly left-wing things starting ing like the people in Germany wasn't doing any of it. in high school. I remember once I somehow. I asked my colleagues went with some friends to hear a con­ about Italian fascism. And I think it JG: Someone like Willy, when he cert at Carnegie Hall that didn't have a was Bernardini who said that he didn't came, didn't receive any graduate conductor. It was kind of a "down think it was a dangerous thing, that it stipend in money. He received it in with the bosses" movement. [laughter] wouldn't have any serious effect on services. So he had to do some work I was also doing the Al Smith cam- repression of Italy. on the cancer therapy project. Then he received his room and board in the Athenaeum. Now you were different Frank Oppenheimer at Pagosa Springs High School in Colorado, 1959. from him in that sense.

Fa: Yes, because I didn't have to pay any tuition, but I used family money to live on. I finally made some money there. I made a huge, eight-channel coincidence analyzer. You could measure anything you wanted. You could put some in anti-coincidence and some in coincidence. You could use it in coincidence with the biology analyzer that belonged to [Henry] Bor­ sook [the biochemist]. He paid me for making it.

JG: What were your contacts with other people at Caltech?

Fa: Well, quite general in a way. Through my brother, probably in part. But I got to know the Tolmans very well. And Ruth [Tolman] and I played piano and flute over at Ruth Valentine's house almost every Friday. The first year Jackie and I were mar­ ried the Tolmans came to dinner at our house. I don't know how I got to know Borsook; he was a great vitamin B enthusiast at that time. My wife had stomach aches. He thought she should eat wheat germ. And we treated it as a cold cereal. And he JG: Did you feel threatened by fas­ ing whether to leave there or not, or to that time. We had meetings regularly cism at all? go to Caltech. I don't know, I think I and discussion groups. There were must have \-vritten them about my various organizations connected with FO: No. Although I had been close wanting to come there. And my the New Deal. One of them, the to this, I wasn't terribly knowledgeable brother probably did something. But I Worker's Alliance, was an organization about what was happening. I did don't remember any elaborate applica­ of the unemployed, and many of these when I was in Germany, very much. tions to go to Caltech. The same thing people were unemployed. The year before I had gone to see peo­ was true with going to Johns Hopkins. ple marching down the streets, and I had a friend who suggested I go JG: Did you have the feeling that really sort of lashed out at this there, and I probably wrote a letter there was a great deal of unemploy­ behavior in the bars, and the whole and got one back. And that had noth­ ment in Pasadena? society seemed corrupt. And then I ing to do with my brother or my FO: Among the black people there, had some relatives there who could tell friend either. me some of the terrible things. But in yes. They were so poor, but you Italy the soldiers didn't seem especially JG: So you came to Caltech. didn't see them, and it wasn't like New aggressive. I never saw any of them Characterizing discussions there with York, where you'd see them out in marching. The policemen weren't any graduate students and professors - bread lines. We tried to integrate the different, and were probably gentler, were they aware of what the political Pasadena city swimming pool, I than New York policemen. The town climate was like in Europe? Did they remember. And it's really hard to seemed very relaxed. care? imagine - they just allowed blacks in Wednesday afternoon and evening, JG: Did you ever see any of the FO: Yes, because of Spain. We were and then they drained the pool Thurs­ Rome physicists in Florence? all talking about Spain. Ruth Tolman day morning. and I even gave a benefit concert for FO: Not then, no. So I never met Spain. [laughter 1 I think they were JG: How successful were you? Fermi until many years later. One of aware. You see, my wife, when she the nice, interesting things was that was a student at Berkeley, had been FO: It wasn't successful. But then I Occhialini and I got to be very good exposed to radical influences and had was asked by the Party organization to friends. When I left, he gave me a been a member of the Young Com­ try and organize a Party group with farewell party in a cave. We walked munist League. And we saw an ad in people at Caltech. So Jackie stayed way back in and came to a huge room one of the newspapers, asking people with the street group for a while, and and had the party. But Bernardini to join, and we clipped it and sent it then later on she moved into the other said something to me in that time that in. And it was months before any­ group. was really surprising. He was 29 and I body came by. [laughter 1 I think we JG: So, how much success did you was 23. And he said, "You know, had to send a second one. So it was have organizing a group at Caltech? Frank, I thought I'd reached the age that kind of a casual thing. But then beyond which it was possible to make we became very active. FO: Well, I don't know. There were friends. Now I've learned differently." six, or eight, or ten people. It was really scary to think you might, JG: While you were still a graduate at 29, have reached that end. student? JG: All the people who were caught JG: Was there any choice of where FO: Yes, first in the city, in what was up in the McCarthy period, were they you might have gone after that? called a street unit, in which there all members of your group? I mean, were mostly inhabitants and a lot of Malina left JPL after the war. Wein­ FO: Yes, I had a terrible time decid- black people who lived in Pasadena at baum went to jail. Tsien left eventu-

The physics faculty in 1932 (shortly before Frank Oppenheimer's time) included (front row, from left) Robert Oppenheimer, Harry Bateman, Richard Chace Tolman, William Houston, Robert Millikan, Albert Einstein, Paul Epstein, Fritz Zwicky, and Earnest Watson. Charles Lauritsen stands directly behind Oppenheimer.

26 ENGINEERING & SCIENCE / MARCH 1985 ally. They're all gone. FO: No. I don't think he gave FO: I wonder why, because I speeches, but in private conversation remember talk of it. But 1 think that FO: And a few others. he was very interested in what was may have been something that Milli­ going on. One of the big issues then kan wasn't all that enthusiastic to do. fG: Was it secret? was support for the Spanish loyalists. fG: I was wondering, for example, FO: It depended on the person. And I don't remember exactly whether Jackie and I were quite open about it. he did or didn't support them, but it would Charlie Lauritsen have proposed And I would rent meeting places. would seem likely that he was somebody, and did you ever hear any­ Other people on campus were very interested. thing about it? secretive about it. A lot of people fG: Was that an issue that polarized FO: I have a vague recollection of would get into political discussions, the campus in any way? yes, that there were talks about it, that and some avoided anything political. whatever was talked about didn't hap­ So there were all kinds of things. But FO: I don't think so - not the peo­ pen. But I don't remember why or it was essentially a secret group. ple I knew. One of the things about who. my work in the Party is that I would fG: Did that bother you? go with my brother to New Mexico in JG: Was Lauritsen a good adviser? the summer, so I would be gone for FO: Well, it did me, but I wasn't FO: Yes, a very good adviser, and two months. Then, the three years that secret about it. you could talk with him when you I was at Caltech I was really quite wanted to. He didn't come in and ask JG: So, are you saying the secrecy active with the Party, so I didn't work you what you were doing very much. was imposed by most of the people nights as much as I did the first year. But, of course, he didn't have to, who belonged to it? With going away in the summer and because of the Friday meetings where without working nights, you really you told what you were doing or not FO: That's right. Because they were don't get enough done. Charlie didn't doing. 1 think I discussed what I was scared of jobs. object to that, never chastised me for doing more often with Willy than not being there. He made one of his fG: Would you often meet on the Charlie. campus? wonderful cracks one time when he came in and I had just gotten a JG: Do you have any sense of what FO: We would meet in people's cigarette holder - I smoked a lot then Charlie liked best about his work? Did houses. - and 1 was soldering away on the he like the physics as much as building amplifier. He remarked on the the equipment, making it work? JG: If you had to do it all over again, cigarette holder. And I said, "I had to would you have done the same thing? get it because smoke gets in my eyes." FO: Yes. He liked the logic of the And he said, "Well, if you really have physics. FO: I can't say. I know things now. a choice, I'd give up soldering." fG: Was he a good lecturer? Jackie and I finally left the Party [laughter] because they had something that they FO: I don't know. called "democratic centralism," in fG: He did work night and day? which, if there was a policy, the groups fG: Well, they used to have the were supposed to discuss it, to let the FO: Yes. I think I did, too, quite Thursday afternoon colloquium in leadership know - a back and forth often, but not as much as I could physics. thing. But it really wasn't; there was have. And I think all the other gradu­ "centralism," but no "democratic." ate students knew about Jackie's and FO: Yes, but I don't think Charlie So, we got fairly upset with that. And my radicalism, and we'd argue about ever gave one. Willy gave one, I gave also, certainly after the war, the atti­ it. But there was never any sense of one - mostly other physicists. I don't tude of the Party was not at all con­ "you don't belong here" with that think 1 ever heard Charlie give a lec­ cerned with nuclear weapons. And it community. I'm sure with [Robert] ture - maybe it's just a lack of was pretty much just a duplicate of the Millikan it didn't sit very well. memory. Willy was nice. I said, "Are Soviet policy. you going to give a colloquium?" and JG: After '33 in Germany, and after he said, "No, I'm writing it on the JG: When did you leave the Party? '38 in Italy, of course, there were board, and I'm going to point at it." many scientists who lost their jobs. FO: We actually left in the spring of Was there ever any discussion of JG: When you were there, do you '41 or the fall of '40 - I think it was bringing some of these people to remember anybody coming down the spring of '41. Caltech? from Berkeley, from the nuclear physi­ fG: When you were at Caltech, was cists? Did [Ernest 0.] Lawrence ever Linus Pauling already politically FO: Yes, though 1 can't remember come down and give a talk, or any of active? the details. his boys? FO: Yes. JG: When you look at the statistics, FO: Well, there was that group from not all that many emigre scientists my brother that would come down. 1 fG: Did he come to any of your really found jobs in the U.S. And there remember Lawrence coming to the groups? were none at Caltech. Cavendish and giving a talk, once,

27 when he was really confused about input. But I liked the subject, I liked JG: The story is that if you came to what was going on, when they first his teaching, and I liked his accent. campus any season, there would found the neutrons from deuterons, [William Ralph] Smythe, I thought, always be work going on here at but I don't remember his coming was a little more boring, for a really Kellogg. down to Pasadena and giving a talk. juicy subject [electricity and magne­ tism]. And he had a real prejudice Fa: Yes. And that's why I say it was JG: Did you ever hear Millikan against vectors. [laughter] You know, very strange to be away in the lecture? his book is all X, Y, and Z written summertime. out. Fa: Yes. Very dogmatic! Terribly JG: Well, in fact it doesn't seem to dogmatic! Pretty clear, but not always JG: Did you go to the course that have held you back. You seem to believable. [laughter] your brother taught? Carl Anderson have taken your PhD in about the took it. right amount of time. JG: I was going to ask you about some of the professors you had. What Fa: I listened to many of his lec­ Fa: Right. But I think I could have was [Fritz] Zwicky like? He's sort of tures, but I don't think I took anything done better work. At the Cavendish legendary around the campus. for credit. The course work at Caltech Lab they closed the place down at was nice because it came as not some­ night unless there was some kind of Fa: Well, I had a problem there. apparatus or experiment that had to be My first year in Hopkins, I took a thing you had to do before you could do any physics. I was really glad that looked after. Rutherford's law (at least sophomore or junior course in I'd been to the Cavendish. I never heard him say it differently) mechanics at the same time I was tak­ was that if you haven't done enough in ing calculus. And I think I must have JG: Of the three labs, which did you the day to think about it at night, it is found it sort of hard. I got good enjoy the most? not worth coming back at night. grades in it, but I didn't like the sub­ ject. And I tried to make up for that Fa: They were so different. Prob­ JG: Well, what do you think? Now, by always, whenever I went to Paris, ably the Cavendish in some ways there you have a study in contrasts, I'd take my mechanics work with me because there was so much going on because in Kellogg it's the opposite. and do it. [laughter] I must have really there, and it was all new to me. And hated it. But then Zwicky's course in they met every day for tea, and you Fa: Yes, it was just the opposite. In mechanics came at eight in the morn­ could listen and hint at what was going most places it was just the opposite. I ing. It was the first year I was mar­ on. [Petr L.] Kapitsa was there, [Ser­ think Rutherford's idea came from ried, and I didn't get there very often. gey P.] Karpoff, [James G.] Mauldon, doing somewhat more straightforward So he was going to give me an F. And [George] Gamow would come around. experiments with radioactivity. I I said, "Well, give me a test in it." It was a very exciting place. thought Rutherford was never really And he gave me a test in it, and I interested in theory. But when you JG: And you heard every day what passed the test and didn't get the F. read his works, he was always trying to everybody was doing. So I really didn't like Zwicky very think, "What does this mean?" much. [laughter] And I didn't like the Fa: That's right. I don't know why way he taught the course, the mechan­ JG: What about Lauritsen? Was he we don't stop and talk to each other ics, either. also interested in theory? more. JG: Was he dogmatic? Caltech was a lovely place to go to Fa: Not so much, I don't think. I get a degree, partly because of Charlie's think he wanted to think about what Fa: Well, I don't know. It wasn't so group, but partly because of the con­ was happening, but the theory had got­ much dogmatic. It was all in the for­ tacts with other people. ten - well, there was lousy theory in mulas and not in the meaning or util­ those days. And I think he knew it. ity of the subject, as I remember it. JG: Was the general level of the Insti­ tute one of excitement? [laughter] I wasn't much help. JG: Did Lauritsen ever instruct you in the details of nuclear physics right Fa: Yes. It was a small place, but JG: What did they do in Italy? Did there in the lab? Was he good at that? aeronautics was doing interesting they run late at night there? things, and I knew them through FO: Yes. He'd explain things. He Malina and Tsien. And Carl [Ander­ Fa: No, not especially. When we was very clear. That's what I meant son] and Seth [Neddermeyer]. And were fairly late, maybe six or seven - he really loved the logic of the then [Jesse] DuMond - I didn't have o'clock, a group of us would walk to subject. much contact, but enough to know some place where everybody had to go what he was up to. in different directions, and they'd stop JG: How was Epstein for thermo­ and sing for a while. dynamics? JG: So there must have been infor­ mal ways to know what everybody was JG: Were they traditional songs or Fa: I liked him, I really did. And I doing. were they political songs? liked the subject. It's a strange subject; it always seemed like sort of a swindle Fa: That's right. I don't know what Fa: They were traditional songs, I - sort of results without any physical they were exactly. think. 0

28 ENGINEERING & SCIENCE / MARCH 1985