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Lawrence Litz’s Interview (2012)

Manhattan Project Locations:

Lawrence Litz was a young physicist when he began working on radioactivity at the Metallurgical Laboratory at the University of Chicago. From there he was transferred to Los Alamos, where he worked on casting the plutonium hemispheres for the atomic bombs and became the first person to see metallic plutonium. He recalls the twenty-four hour shift he pulled to cast two more plutonium hemispheres in case a third atomic bomb was needed to force the Japanese to surrender and discusses his love of solving problems as a scientist.

Date of Interview:
December 28, 2012
Location of the Interview:


Alexandra Levy: All right, we’re here on December 28, 2012 with Lawrence Litz. First please say your name and spell it.

Lawrence Litz: L-A-W – it’s Lawrence Litz, L-A-W-R-E-N-C-E, L-I-T-Z.

Levy: So what was it like working in the war on the Manhattan Project?

Litz: It was very exciting and I felt that I was doing something worthwhile.

Levy: You went to the University of Chicago. What did you study?

Litz: I majored in chemistry and minored in mathematics. I also did a lot of physics.

Levy: When did you graduate? And did you get married soon afterwards?

Litz: I graduated on June 12, 1942 and got married the next day.

Levy: What did you do after you graduated?

Litz: I went to work in Florence, Alabama in an ammonia plant, which is—and the ammonia is used to make explosives for the war effort back then.

Levy: Did you go back to Chicago?

Litz: Yes, I wanted to look for another job and they were interested in me because I already had some industrial experience. I left because we had shifted the lab from twelve men and one woman to twelve women and one man, and the man was me. And I was studying the effect of nuclear radiation on materials having to do with the nuclear reactors, which were being built at Hanford, Washington. Then I went to Los Alamos.

Levy: Going from Chicago to Los Alamos, was that a strange experience because of the geography?

Litz: Very different, particularly because Los Alamos is at seven thousand feet elevation and Chicago was at sea level, so I learned to breathe properly.

Levy: So what kind of work did you do at Los Alamos?

Litz: I worked on technology involving plutonium and it was high vacuum technique such that we had put the plutonium metal—the plutonium chloride as a salt and reactor was magnesium metal to make magnesium chloride which then could be boiled off and left—and then we were left with a little button of plutonium metal about an eighth of an inch in diameter. This was our first creation of the plutonium metal in the world; so we were the first ones to see it.

Levy: So you were the first person to see metallic plutonium?

Litz: Yes.

Levy: Who was the second person?

Litz: My wife. My wife was working in an adjacent lab and I invited her into my lab to look through the telescope at the reactor which produced the plutonium metal.

Levy: And what is the crucible?

Litz: Well, the crucible is kind of a metal crucible, but it is actually cerium monosulfide, which allowed us to melt the plutonium without contaminating it and we—so we had a high vacuum system and I don’t know whether you can see this is one of the technical pieces for high vacuum system.

Levy: And sothat’s one of the pieces?

Litz: Yeah, used to create a high vacuum.

Levy: What is it made out of?

Litz: This is brass. The crucible is cerium monosulfide.

Levy: As more Plutonium was needed, did you have to find new methods?

Litz: Well yes, because plutonium as a solid exists in six different crystalline phases between room temperature and its melting point of about 800 degrees centigrade. And of course if you have something that’s changing crystal phase, it changes shape. And the problem—you can’t make a bomb out of something which is changing temperature—which is changing shape as it got hotter. So we learned that we could alloy it with a small amount of gadolinium and then that would stabilize a single phase and then we could cast it in different forms.

Levy: Was that well known or was that secret at the time?

Litz: It was not well known because plutonium was not known to exist even until we made it in our research lab.

Levy: So the gadolinium mixture, that was top secret?

Litz: Yes.

Levy: So what was the bomb that you helped develop?

Litz: Well, in order to make the bomb, we had to make the plutonium metal in a sphere. And in order to get a sphere we had to cast a—each half of the sphere, and then the sphere would be about eight inches diameter. We put something in the middle of this eight diameter sphere which would release neutrons and would cause the plutonium to undergo fission and release very large amounts of energy.

Levy: So did you help cast the plutonium sphere?

Litz: Yes. So this was all done in my vacuum to keep the things pure.

Levy: Was that dangerous work or was it fairly safe?

Litz: Well in a sense it was dangerous because we were working with something that was radioactive.

Levy: So did you know that it was for a bomb?

Litz: Yes, definitely we were aware. We knew what we were about to do and realized that it was something that was important to the military.

Levy: When did you find out that the bomb had been dropped on Japan? Did you find out from the newspaper?

Litz: No, actually we had correspondence from the people who actually dropped the bomb because we were—we had to be prepared to make more bombs as necessary.

Levy: How did you feel when you found out the bomb had been dropped?

Litz: Well we thought that we were going to make the war come to an end, which we did, and that was a very happy feeling.

Levy: So why was the bomb important?

Litz: Well, because it was a simple way to stop the fighting.

Levy: And was that important for you personally?

Litz: It was certainly important personally, but also from the scientific point of view, it was a new technology.

Levy: Did you have any other relatives in the Army?

Litz: My brother was in the Army.

Levy: And would he have been involved in the invasion of Japan had it happened?

Litz: Yes, I’m sure that had the war stopped—not stopped, then he would have been in the invasion.

Levy: And you mentioned that Oppenheimer had spoken to you the day before—or the day the bomb was being dropped or being shipped to Tinian. Do you remember what he said?

Litz: Yeah, Oppenheimer actually spoke to us for about two hours on the day before the bomb was shipped to Tinian Island near Japan where it was set to be launched, dropped on Hiroshima. And he stressed that hopefully it would end the war.   

Levy: Great. After the war, what—did you stay on with the Manhattan project?

Litz: Only for about another month, and then I went to graduate school at Ohio State.

Levy: How did you react to working in the war?

Litz: Well as a scientist, I was happy to do anything in which I had knowledge. And most of my science has to do with chemistry and water and types of solutions. I had very little training in metallurgy, but the fact that I can build high vacuums, I was the right guy to take on this project.

Levy: How old were you?

Litz: I was only 22 years old then.

Levy: Were you one of the younger people?

Litz: Yes, definitely.

Levy: So how did you get to Los Alamos? Or did you know—when you went did you know what was being done there?

Litz: Well, I actually didn’t know. The secrecy was so high we knew only that they were working on radioactive materials. We—I didn’t even know where Los Alamos was. And the people—when we had to go, they just bought the railroad tickets for myself and my wife and took our little puppy with us on the Sante Fe Chief.

Levy: So did you end up then going to Lamy, New Mexico?

Litz: Yeah.

Levy: Which is the closest stop.

Litz: Right, the train—the closest stop for the train was Lamy, New Mexico, and it’s about eighteen miles south of Sante Fe. We got off the train in Lamy and then we had to wait for the people to take us. And so we had to just sit and wait on the platform, my wife and I and our little puppy.

Levy: Was Lamy very big?

Litz: No, Lamy was small. It was sort of built around a train station. About half a block away there was a parking lot in which there were few military vehicles. After we’d been sitting there at the train stop for about half hour one of the men got out and asked if I had been at the Met Lab in Chicago because he recognized me. Then he asked me if I was going to the Hill. I didn’t know but said, “I guess so.” And they drove us to the center of Sante Fe and then we got into another car, which took us to Los Alamos.

When we got to Los Alamos they said, “You weren’t supposed to bring your wife with you,” but they should have known since the people in Chicago had bought a ticket for her as well as for me. But since they weren’t expecting a couple they only had a small apartment available for us, but they managed to get us a couple of beds and several lamps so we could at least have a place to sleep that night.

Levy: So what was your early work at Los Alamos like?

Litz: Well for about two months I worked on the water boiler, a nuclear reactor surrounded with water, which would deflect neutrons back into the material. Then they transferred me over to the Met Lab.

Levy: So as a young scientist, how did you feel about working at Los Alamos?

Litz: As a young scientist I was really interested in doing anything which would take advantage of my skills.

Levy: What did your superiors think about your work there?

Litz: They thought I could do almost anything.

Levy: So what was a typical day like at Los Alamos?

Litz: Well typically we would start working in the lab at about eight in the morning, take a break for lunch—and then Evelyne and I would break together and then go home and have lunch and then we would come back to the laboratory and work until about five.

Levy: Did you work every day, even on the weekends? If you don’t remember that’s fine.

Litz: I don’t.

Levy: Do you remember working on casting the plutonium for the third bomb?

Litz: The particular day that remains in my memory was the day that we cast the plutonium for the third bomb because we weren’t sure that the Japanese would surrender even after the second bomb was dropped. We had to cast the atmospheres for the third, and because time was short we had to cast the two hemispheres at the same time. But it was dangerous to cast them in the same laboratory at the same time so we set up two adjacent laboratories with the high vacuum apparatus, so we could cast one hemisphere in each one of the two labs.

Levy: How long did that take to cast?

Litz: About twenty-four hours, and we had to work straight through.

Levy: So what did you do when you didn’t need to use the plutonium for a third bomb?

Litz: Well after we found that we didn’t need to use the third bomb we decided to use the hemispheres for research. We designed an array, which took the neutrons that came out of the sphere back into the sphere and would keep the neutron radiation away from the scientist who is doing the work experiment. Now one of the men who was working on the experiment accidentally bumped the array, exposing himself to the radiation, and died two weeks later from the radiation.

Levy: Do you remember, was that man’s name Louis Slotin?

Litz: I don’t recall.

Levy: Okay. Were you ever worried about being exposed to toxic materials?

Litz: Well of course we were worried about it but that was the job to be done. We always tried to be safe. I worked with rubber gloves and a dry box but I also had to clean up the high vacuum system every three to four weeks, so by the end of the war I end up with what was termed at that time to be exposure to the maximum tolerable dose of radiation.

Levy: And how long does plutonium—how long is the half-life?

Litz: Plutonium half-life is five thousand years, so it will be around long after I’m gone.

Levy: So what was life like in Los Alamos? Did you make a lot of friends?

Litz: Yes, we made a lot of very good friends, one of whom I remember was [Richard] Feynman, was one of our neighbors.

Levy: Do you have any funny stories about Feynman, or do you remember any conversations you had with him?

Litz: Not particularly at this stage.

Levy: Okay. Did you keep in touch with any of the other scientists?

Litz: We were not allowed to correspond with other scientists at all. In late 1944 we got permission to visit our family in Chicago and I was told that I was not allowed to say anything about what I was working on and I knew that I was being followed by G-men to make sure I didn’t say anything.

Levy: Who were G-men?

Litz: These were, I guess, engineers who took care of the secrecy information.

Levy: So how much longer was the information on the bomb classified for?

Litz: Well it was partially declassified about four to five years after the bomb was dropped, but most—but the fine details were not declassified until about 2005.

Levy: What can you tell me about J. Robert Oppenheimer?

Litz: He was a very positive, encouraging man and very caring about our work. He made sure that we had a complete understanding of the importance of what we were doing. That undoubtedly it would kill many people but this loss of life would end up saving millions of lives.

Levy: So what did he tell you in the two hours on the day the bomb was dropped?

Litz: Well he told us exactly where the bomb was going to be in Japan, and even though we’re not pleased with the moral aspects of killing people that we need to understand how many lives it would save.

Levy: Did you keep in touch with Oppenheimer after the war?

Litz: No, I didn’t correspond with him after I left because much of my work, which was with silene and fuel cells, were not of common interest to what I—to what he was doing.

Levy: What did you think about during the Cold War when he was accused of being a Communist?

Litz: I was very disturbed when he was accused of being a Communist. There was never any indication during the war that he was anything but an extremely loyal American citizen. And as a consequence of those hearings that they had he was really destroyed emotionally. Anyone who knew him during the war had to be extremely disturbed.

Levy: So Oppenheimer was someone you admired, then?

Litz: Definitely.

Levy: So what kind of work did you do after the war?

Litz: I went—you have some—

Levy: Did you receive any awards after the war?

Litz: I was given an award as a pioneer in the semiconductor field.

Levy: Great. So are you proud of your work on the Manhattan Project?

Litz: Very definitely. Yes.

Levy: Great. Do you have any other stories you’d like to share with your work on the Manhattan Project or your work as a scientist?

Litz: Well, I was a very diffuse scientist. I worked with many, many different projects, different technical areas, and I actually have forty-two patents in the areas that I worked on.

Levy: Wow, that’s terrific. What kinds of patents are they for? Semiconductors?

Litz: Some were semiconductors. I don’t remember all the technicals.

Levy: That’s great. So you really enjoyed working as a scientist?

Litz: I definitely did.

Levy: What did you enjoy the most?

Litz: I guess accomplishing things, being able to solve problems.

Levy: Did you have a favorite project you worked on?

Litz: Not a particular one. I just enjoyed whatever I was doing.

Levy: Do you think your work on the Manhattan Project helped you after the war in terms of overcoming challenges and research and teaching you about many things?

Litz: Well the sense that working on any project helped—helps you broaden your capabilities, and I think in that context it was important.

Levy: Was the Manhattan Project one of the most difficult projects you worked on?

Litz: I think it was; yes.

Levy: Why do you think that?

Litz: Just sort of hazily recollecting one versus the other.

Levy: Do you have anything else you’d like to share?

Litz: No, I think that’s it.

Levy: Great. Well you were terrific, thank you so much.

Litz: My pleasure, thank you.

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