The Manhattan Project

Roger Hildebrand's Interview

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Roger Hildebrand is an American physicist and the S.K. Allison Distinguished Service Professor, Emeritus, at the University of Chicago. His involvement with the Manhattan Project began with a tap on the shoulder by Ernest Lawrence, who convinced Hildebrand to shift from being a chemist to a physicist. He worked with cyclotrons and mass spectrometers at Berkeley before transferring to the Y-12 Plant in Oak Ridge. In this interview, Hildebrand shares his memories of Lawrence, Enrico Fermi, Samuel Allison, and other Manhattan Project scientists. He recalls his postwar work at the University of Chicago, and the pressure he felt after being asked to be a substitute in one of Fermi’s classes.
Date of Interview: 
November 16, 2016
Location of the Interview: 

Cindy Kelly: I’m Cindy Kelly, and it is November 16, 2016. I’m in Chicago, Illinois with Roger Hildebrand. My first question for him is tell me your name and spell it, please.

Roger Hildebrand: My name is Roger Hildebrand, R-o-g-e-r H-i-l-d-e-b-r-a-n-d.

Kelly: Tell us what is your birthday and where were you born?

Hildebrand: May 1, 1922, Berkeley, California.

Kelly: Tell us something about who were your parents.

Hildebrand: My father was Joel Hildebrand, a very distinguished chemist at the University of California. My mother’s name was Emily. She raised four kids and I was one of them, the last one. 

Kelly: What was it like to grow up in a house with a scientist as the head of household?

Hildebrand: Oh, wonderful. Dad encouraged us to ask questions and he always seemed to know the answer. 

Kelly: Did you go to school at Berkeley? 

Hildebrand: Yes. I went to school in Kensington. We were in a suburb of Berkeley called Kensington. Then I went to Berkeley High School, and that’s where I met my wife Jane. 

Kelly: What was she like? 

Hildebrand: She played the flute in the high school orchestra, and it was a very good orchestra. They were invited to give concerts all over Northern California.

Kelly: Oh, my. So you went to a lot of concerts? 

Hildebrand: Oh, yes. 

Kelly: Were you also a musician?

Hildebrand: No.

Kelly: Just a fan?

Hildebrand: I was nothing much of a musician. I made some attempts. I had a good friend, John Bogard, who had a beautiful tenor voice, and sometimes he and I sang together. I had a passable bass.

Kelly: Is that in high school? 

Hildebrand: Yes.

Kelly: Oh, fun. What were your interests in high school?

Hildebrand: My wife Jane – my future wife Jane – was a big interest. It wasn’t until I got to college that I was sure I was going to have scientific career. I thought I was going to be a chemist, and that changed when the war came along. Ernest Lawrence asked me—well, he recruited me, and he asked me what I knew about. I said I was a chemist. He said, “You’re going to have to learn physics in a hurry.”

Kelly: What year were you?

Hildebrand: Pearl Harbor was bombarded by the Japanese on December 7 [1941] as I recall, and I took my last exams that quarter on December 12. It was pretty hard to concentrate on my exams.

Kelly: You have a story about coming out of an exam and someone tapped you on your shoulder.

Hildebrand: Yes. How did you hear that?

Kelly: [Laughter] Tell us that story.

Hildebrand: Yes. I came out of my last final exam on December 12, and Ernest Lawrence tapped me on the shoulder and said, “Well, you want to help the war effort, don’t you?” And there was only one answer to that. I imagined that he was talking about what would happen at the beginning of the next quarter, but he meant now.

He took me over to the Crocker cyclotron and told me to stand behind the guy who was running it and learn how to do it. That was Fred Schmidt, later a professor at the University of Washington. I could see he was very busy, and finally, when he got things going, he said, “You, what’s your name? Sit down here.” I learned by rote how to run a cyclotron. My entire acquaintance with cyclotrons was one page in an undergraduate text.

Anyhow, he gave me instruction for about an hour and now he says, “Goodbye. I have to work across the alley in the lab there.” If I needed him, I should punch this button and he would come if he could.

So I didn’t have much idea what I was doing there. I later learned that I was making the first samples of neptunium and plutonium, which [Glenn] Seaborg brought here to the University of Chicago to measure their properties. Well, after I’d been running the cyclotron for just a few days and I’d barely got on to what I was doing, my boss brought in a student and told me to teach him how to run the cyclotron. So I did and I went across to the lab where they were building mass spectrometers. These were the prototypes for the mass spectrometers built at Oak Ridge. Pretty soon, I taught this guy how to run the cyclotron and he was no better at it than I was.

Anyhow, then I went across to the lab where the old cyclotron had been, and I tried to figure out what the heck was going on in this lab. Pretty soon I said, “We must be separating uranium isotopes.” And I don’t think I said the word uranium again until the war was over.

Our job was to make the apparatus to separate uranium isotopes. Very soon—oh only, I don’t know, less than a month—they brought in a whole bunch of young guys who were as young as we were. I had several other people going through what I was going through, and they were very good. They were young people trained in engineering, and they designed the apparatus at Oak Ridge. They were very, very good.

Let’s see, where was I? In a very short time, they not only designed this, but the work to build it—General [Leslie] Groves was in charge of building the plant to separate isotopes. Those of us who’d been at Berkeley were sent to Oak Ridge to train the local people how to run that, and that was quite an experience. These local people were not told what they were doing, so we had to train them how to run a mass spectrometer by rote. You know, if this needle goes this way, you turn this knob this way. 

Kelly: Was this at the calutrons, they called them, at Y-12 plant?

Hildebrand: Yeah. The instruments we designed, the mass spectrometers, they were called “calutrons.” I suppose Ernest Lawrence is the one who invented that word, because he got “Cal” in there.

It was quite an experience. I had to get some apparatus going, and it required storage batteries. I took a wagon and pulled it around Berkeley until I had as many batteries as I could pull. Pretty soon there were some somewhat older people, people who’d been assistant professors and associate professors. One of them, his name was Carl Helmholz, and when I finally came to the University of Chicago, his uncle was on the faculty here in the law school.

Kelly: So he was one of these older people that came to Berkeley to work?

Hildebrand: Oh, yeah. Carl Helmholz was an assistant professor.

Kelly: Of physics?

Hildebrand: Physics.

Kelly: What was Lawrence like as a person?

Hildebrand: Oh, he was a very domineering person. He was very successful in building cyclotrons. But later on I was able to meet Niels Bohr and Enrico Fermi, and these were much better scientists.

Kelly: Well, Lawrence is famous for being an experimentalist.

Hildebrand: Yeah.

Kelly: A great tinkerer, you know. An inventor.

Hildebrand: Yes. We used to say that there are three kinds of physicists. There are experimentalists, there are theorists, and there’s Enrico Fermi, who could do anything. It was a great part of my life that I was invited to come to Chicago when Enrico Fermi was here.

Kelly: When was that? We’ll back up to you. You’re in Berkeley. You’re working on the cyclotron and then the—?

Hildebrand: Mass spectrometer.

Kelly: Mass spectrometer. Then what did you do?

Hildebrand: Then I went to Oak Ridge, and then the war was over. I came back and I finished my undergraduate work at the university.

Kelly: At Berkeley.

Hildebrand: At Berkeley, yes.

Kelly: What field did you end up in?

Hildebrand: I ended up in physics.

Kelly: Was Oppenheimer around when you were at Berkeley?

Hildebrand: Yes.

Kelly: Tell us about him.

Hildebrand: I didn’t know him very well. He was strictly a theoretical physicist. He wasn’t like Fermi, who could do anything.

Kelly: Do you have any other memories of your undergraduate years at Berkeley? People that you knew there before we hop to Chicago?

Hildebrand: Well, I took chemistry from my father, and that was the hardest course I ever took, I think. He wanted to make sure that I understood everything he was teaching the class.

Kelly: Did he help you at home? Were you living at home?

Hildebrand: No, no. He’d written a book and told me I should sit down and read the book.

Kelly: How’d you do?

Hildebrand: I got an A. But it was hard work. My two brothers went through more or less the same experience. They are both older, and they both took his class. They both got A’s, and they worked very hard to succeed.

Kelly: Wow. Did they turn out to be chemists?

Hildebrand: No. My oldest brother became an engineer in the Standard Oil Company, and my next brother became a biologist, very distinguished. He wrote a textbook, which has been translated into six different languages, I think, on vertebrate anatomy.

Kelly: Tell us what happened when you graduated from Berkeley. Then what did you do?

Hildebrand: I was offered a job here, an academic job, so I came here. This was, at that time, without doubt – with no doubt whatever – it was the best chemistry department in the world. And I managed to do just well enough to stay.

Kelly: Do you say it’s the best chemistry department or do you mean physics? 

Hildebrand: No, the best physics department.

Kelly: The physics.

Hildebrand: It was very good in chemistry, too.

Kelly: And this is the University of Chicago you’re talking about?

Hildebrand: Yes. Now, my father went to Berkeley when that was the best chemistry department in the world. He had been an instructor at the University of Pennsylvania, and when he got to Berkeley, he said it was just like walking into something entirely new. In Pennsylvania, he got a job there as an instructor, and his job was to teach a current’s preparation and uses. When he got to Berkeley, he said it was just like being in a new world. Gilbert Lewis was probably the most distinguished chemist in the world at the time.

Kelly: So when you went to the University of Chicago, who were some of the luminaries? Who were some of the physicists?

Hildebrand: That’s the only kind they had. First of all, there was Enrico Fermi, who was just the best scientist I’ve ever known. There was Willard Libby, who used to date my sister, and he developed the technique for dating archeological samples. There was [Harold] Urey. He was able to figure out the history of the moon. 

Kelly: This is Harold Urey?

Hildebrand: This is Harold Urey.

Kelly: He figured out the history of the moon.

Hildebrand: Yes.

Kelly: How did he do that?

Hildebrand: Well, that’s a long story.  

Kelly: Did you have classes with Fermi? Were you ever a student of Enrico Fermi?

Hildebrand: Yes and no. He was a superb teacher. Besides being the brightest physicist in the world, he was a superb teacher. The custom here is, if you hire a new assistant professor, you don’t ask him to teach in the first quarter he’s here. Fermi knew that I was here and I was not responsible for teaching anything, so he asked me if I would teach his class. He had to go out of town one day. I sort of gulped, because I knew that I’d be compared to what I think was the best physics teacher in the world. So he told his class, he said, “Next Tuesday, Professor Hildebrand will give you a superb lecture on the deuteron.”

I wasn’t at all sure that the class would think so, so I asked him if I could discuss this with him. He said, “Oh, yes, just come to my office at 7:00 tomorrow morning.”

That’s when he normally came. He began asking me questions about the deuteron, easy questions, and it made me think sort of with one side of my brain, “Gee, I’m pretty smart.” The other side, I said, “Oh, no, it’s Fermi that’s making this seem simple.” I taught his class and somehow survived. 

Kelly: Do you remember working very hard to prepare?

Hildebrand: Oh, gosh, yes.

Kelly: Well, that was quite a compliment to you.

Hildebrand: I don’t know. I was the new associate professor, so I wasn’t teaching any other class. It was the natural thing for him to ask me to teach his class. Of course, he’d participated in all the discussions that ended up in my being offered a job here. But still, that was quite an experience.

Kelly: What do you remember about Fermi outside the classroom? What was he like?

Hildebrand: He seemed to be able to do anything better than anybody else. If we had a baseball game, he grabbed the bat and hit home runs.

Kelly: I think I heard he liked to go swimming.

Hildebrand: Anything you can mention, he could do.

Kelly: Was Leona Woods Marshall around when you were here?

Hildebrand: Yes. Leona Woods Marshall Libby.

Kelly: Right, right. Forgot the Libby.

Hildebrand: Yes. She was here.

Kelly: Did you have a course from her or did you—?

Hildebrand: No, no.

Kelly: No.

Hildebrand: No. She was not in a class with the other members of the department, in my estimation. I could’ve taught her class.

Kelly: Trying to think who—earlier we talked about Sam Allison, you remember him?

Hildebrand: Oh, yes.

Kelly: What can you tell us about him?

Hildebrand: Well, I owe to him that I am the Samuel K. Allison Distinguished Service Professor. He had a very good, dry sense of humor, very nice guy. He let me and my family take a vacation in his place at Three Lakes, Wisconsin. Other people were building cyclotrons and other accelerators at higher and higher energies. He kept building accelerators at lower and lower energy and making a good thing out of it. There’s at least one other distinguished physicist who was here before my time.

Kelly: We talked about Robert Wilson.

Hildebrand: No, I hired Robert Wilson. Of course, he was brought here to build an accelerator and, of course, that had to be cleared with all sorts of people, high-ranking people, and it just fell to me. I guess I was the Director of the Fermi Institute at the time, and he made it clear that he wouldn’t come if he was not a member of the faculty. I got to offer him his job.

Kelly: Seaborg came back here, right?

Hildebrand: Seaborg, yes.

Kelly: You had interactions with him?

Hildebrand: Glenn Seaborg? Well, very little. I knew him. Knew who he was and knew about his being recruited to come here. But if I thought about it, I could probably tell you some stories about him. But it would take some thought. 

Kelly: He was actually the one who weighed the first visible samples of plutonium, right?

Hildebrand: Yeah.

Kelly: In the George Jones laboratory.

Hildebrand: That’s right.

Kelly: Was that a big deal at the time? Were you here?

Hildebrand: Oh, I was here, yes. Just weighing it was part of what he did to understand. See, he had—Well, I can go back. When I was running the Crocker cyclotron in my first days at Berkeley Lab, I didn’t know what I was doing at the time, but I was making samples of neptunium and plutonium. Those were sent here to Chicago for him to measure their properties. So he had just tiny samples, and he worked out all the chemistry and physical properties of this neptunium and plutonium. I didn’t know that, that I had made those samples. But I found out about that when I came here.

Kelly: You yourself have had a very distinguished career.

Hildebrand: Well, I can’t mention anything I’ve done that puts me in a class with Fermi.

Kelly: You’re too modest.

Hildebrand: No, no, that’s just a fact.

Kelly: I see that you were the S.K. Allison Distinguished Service Professor.

Hildebrand: Yes.

Kelly: These names are with us today.

Hildebrand: Pardon?

Kelly: Allison is here and Fermi. No one has forgotten these famous scientists.

Hildebrand: They were. I was very fortunate to be able to come to the faculty that was here at the time. It was just the best in the world.

Kelly: Looking back, was your experience on the Manhattan Project sort of formative for you? It changed you from a chemist to a physicist.

Hildebrand: Oh, yes. I told you that Ernest Lawrence told me I had to learn physics in a hurry. I did and I liked it.

Kelly: When your father went to Berkeley, he said, “Oh, this is a whole new world.”

Hildebrand: That’s right.

Kelly: What did you think of going the other direction when you came from Berkeley to Chicago? How was it different from this world of Berkeley?

Hildebrand: Well, young people are supposed to leave where they went to college, and Berkeley was a very fine chemistry department.

Kelly: Wow. So you must’ve married your high school sweetheart sometime. You didn’t mention that.

Hildebrand: Yes. I went to Oak Ridge. See, the plant there to separate uranium isotopes was built very, very rapidly. It didn’t work, but it was workable. So Lawrence sent a bunch of us to Oak Ridge to start up that plant and get it really working. When it was working well enough, I decided it was time to go home and marry Jane.

Kelly: Had the war ended at that point, or were you able to just get transferred back?

Hildebrand: Let’s see.

Kelly: So you got married before you’d finished your undergraduate work.

Hildebrand: That’s right.

Kelly: Yeah. What did your wife do? She put you through school?

Hildebrand: Yes, and she had babies.

Kelly: Ah, there we go. How many children did you have?

Hildebrand: I have four.

Kelly: Four, that’s right. So, you were one of four and so you had four more. Good.

Hildebrand: That’s right.

Kelly: Are any of them interested in science? Have they pursued science as a career?

Hildebrand: Oh, yes, yes.

Kelly: Is there anything else that you can think we haven’t talked about? I’m sure there are hours of things you could tell us, but is there something—?

Hildebrand: Oh, yes, I think so. In the last couple of decades, I did work on the polarization of interstellar objects. Polarization of the radiation. In my recent years that’s the best thing I did.