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Jim Sanborn’s Interview

Manhattan Project Locations:

Jim Sanborn is an American sculptor known for works such as “Kryptos” at the CIA Headquarters in McLean, VA. In this interview, Sanborn discusses his exhibit “Critical Assembly,” which is now on display at the National Museum of Nuclear Science and History in Albuquerque, NM. The installation recreates the Manhattan Project scientists’ experiments at Los Alamos to determine when plutonium would go “critical” in an atomic bomb. Sanborn explains why he decided to do the project, and how he carefully created each piece of the exhibit. He describes some of the artifacts in the exhibit, including the physics package of the Trinity device and an oscilloscope, and where he found some of the materials and artifacts he used. Sanborn also discusses the Slotin accident, the urchin initiator, and other key scientific and engineering devices from the Manhattan Project.

Date of Interview:
February 3, 2017
Location of the Interview:


Kelly: Today is Friday, February 3rd, 2017. I’m Cindy Kelly, Atomic Heritage Foundation, in Albuquerque, New Mexico. I’m here in an installation called “Atomic Time” with its creator, the sculptor and artist Jim Sanborn. My first question to Sanborn is to please say his name and spell it. 

Sanborn:  All right. I’m Jim Sanborn, S-A-N-B-O-R-N. I’m the maker of this installation that I began sometime in 1998 and concluded in 2004, although I added pieces over the years, added more stuff over the years.

Why did I build this piece? For decades before I built this piece, I was known fairly well in the art world for building art installations that had in some way exposed something that was hidden, whether it was secrets, whether it was the Coriolis force of the earth, or whether it was some other secret that I wanted to bring forward into view, because I thought it was important to do.

The first inkling that I had about doing this piece was, I went to White Sands National Monument, and they had a little tiny museum shop there. There was a small pamphlet, and when I got the pamphlet, there was a detector for blast waves. It was taped to a pole with what looked like duct tape. I really liked the informality of it. 

Then I drove up to Los Alamos, reconnoitered, then worked with several people, who I more or less collaborated with. One was John Coster-Mullen and the other was Chris [misspoke: Chuck] Hansen. Both of these people have voluminous notes full of those records, all kinds of things about the project, whether they were records produced by the former Soviet Union, who coopted some of these ideas, or whether they were FOIA [Freedom of Information Act] requests, visas.

I took all this information and tried to make it three-dimensional. These guys mostly dealt with two dimensions. Being a sculptor, I had the ability, the technology, etc., to build something from scratch if I couldn’t find it at Los Alamos.

In the beginning, I did as much as I possibly could to try pieces at Los Alamos by putting up little signs at retirement homes and coffee shops saying, “Manhattan-era pieces requested. If you have anything and you’re interested in having them shown in a museum, please give me a call.” Over time and over six years of doing this, slowly but surely, people walked up out of their basements with objects that they had saved for all these years.

Los Alamos on weekends had a sale of scrap metal, and a lot of the physicists who were originally at Los Alamos stayed in Los Alamos. They would go out looking around scrap metal yards on weekends. They brought home objects that they recognized as possibly belonging to the Manhattan Project per se, or related things, prototypes, original prototypes. Spheres, large, thick aluminum pusher spheres were being used as bird baths. Lots of other objects I brought back to Washington, D.C.

Then with the detailed records and voluminous material that John Coster-Mullen and also Howard Morland had, I started building what I thought was the closest replica to the original laboratory environment for the Manhattan Project. That laboratory environment consisted of a whole series of tabletop experiments. They tested blast wave design, they tested radioactivity, they tested health physics. They tested all kinds of things. I did everything I possibly could to recreate those things.

No, I couldn’t get plutonium and uranium and beryllium and all the other things that these pieces were really made out of. But I tried to use materials that were germane to the project. Where it called for beryllium, I used graphite. I was able to find a lot of the original graphite bars at the Black Hole [Atomic Surplus Store] in Los Alamos. I collected a lot of that graphite material there. Then I had graphite pieces made that matched the pieces that were used in the tabletop experiments that were originally beryllium. That’s how I started out building this piece.

I first went to Los Alamos in the summer of 1998, and that’s when I found that small pamphlet. The first exhibition of the piece, it was at the Corcoran Museum, was in 2004. The next year it went to the Gwangju Bakmulgwan in South Korea, quite an undertaking for something this scale. It showed there, and then it showed again at the Crawford Art Museum in Cork, Ireland. It had three venues before it went back to my studio and sat for many years, until it came here.

On this table, there’s a whole variety of interesting objects—at least, that I found were interesting. We have lead-lined gloves from Los Alamos. They have become quite stiffened with age. These are the gloves that people wore when they were picking up fissile material. They didn’t really do a whole lot, but they gave people some certain confidence that it was a little better than being directly radiated.

On this table, there are also blueprints from Los Alamos. Many blueprints, mostly of the electronics that were designed at Los Alamos and by companies that were contracted by Los Alamos to build the original electronics. I got this oak table, because it really replicated the kinds of tables and chairs that were used at Los Alamos for computation and these kinds of things. The lamps are period pieces.

Then there are these Marchant calculators. Now, before we had computers that were more or less electronic, we had Marchant calculators. Richard Feynman was the person in charge of these things. I found several of these. I found six or seven of these, again at the Black Hole. Knowing what importance they had, I collected them. Some of them actually still work if you plug them in. These were actually used to calculate the yield of the first atomic blast.

These tables were largely occupied by a group of women who did the calculations. So say one group of people did a calculation up to a certain decimal point. Then another person would take the calculation up to another decimal point, and so on until they were able to calculate these huge pressures and blast waves and radioactivity produced by the first bombs themselves.

These calculators were very finicky. Feynman was continually complaining about—they were down and being repaired more than actually they were being used. They’re notoriously finicky. I found only one place in the United States where somebody could actually repair them. But I tried to get ones that were actually working. So these guys are very historic objects.

Interestingly, there’s another piece over there on the other side, which is indicative of the kinds of things that I obtained for this project. This is an oscilloscope. This is a DuMont oscilloscope, and these oscilloscopes were used exclusively at the lab in the 1940s. These were originally designed in the 1930s, and they lasted quite a while.

This particular oscilloscope is in one of the photographs that I had got from Los Alamos from the lab, because it has property numbers on it that match the numbers that were in the photograph. I found this, again, also at the Black Hole, and then amazingly, it still operated and still works today. We don’t have it plugged in. But it’s these historic objects that I was very careful to try to choose in order to represent as accurately as possible.

Now, surrounding me here, there are some of these tabletop experiments. This is one tabletop experiment which was used for determining the critical mass of hydride cubes. Instead of hydride cubes, I used graphite again. This is a Geiger counter that would detect radiation given off by these cubes. These guys would—in a test they would take these small cubes and they would continually—these are radioactive uranium hydride. They would continue to build small assemblies, critical assemblies. They would continue adding these small blocks together until they achieved a great radioactive burst, which meant that they had gotten very close to criticality.

This hydride cube assemblage would be surrounded by lead blocks. Interestingly, the lead blocks seemed to only protect from the waist down, what was most important to some of the scientists at Los Alamos. Most of them are tabletop and most of them, their upper bodies were exposed, but their lower bodies weren’t exposed. That goes for pretty much all of the tabletop experiments. 

This would be a tabletop experiment about critical mass of a plutonium sphere, this sphere. I found actually this object and this object at Los Alamos, and this piece. It didn’t have the sphere in the center, but they were the original ones that were used to determine how much uranium-235 you needed to make a device. There was a hole in the top of it here through which would pass an initiator. Again, you had Geiger counters all the way around it to determine how close any of these things were to criticality.

There are Geiger counters everywhere. There are big electronic counters, there are small Geiger counters. The problem was, when these tabletop experiments were all in one room, if you moved one tabletop experiment close to another one, the radioactivity would shoot up. It would be here, the radioactivity rise, on these scalar machines.

This is what’s called a scalar. What happens basically is as radioactivity rises, it can rise very rapidly. Just from the single clicks on the Geiger counter, all the way up to just what sounds like a waterfall or an ocean. These machines were designed in such a way that they would go up to a certain level with just a few counts. Then they would shift. They’d go up to another higher level of radioactivity, then they’d go up to another higher level of radioactivity, in order to be able to detect how much radioactivity is being given off by any particular experiment, and how much is being given off by the room itself.

Again, this piece, which is grey, probably postdates the Manhattan Project, but the ones that are black like this one, this is definitely 1940s equipment that was used at Los Alamos. This piece is another piece, which was used to demonstrate how much fissile material or uranium-235 was needed to build a bomb. Basically, this was paraffin originally, and paraffin absorbs or moderates neutrons. Now, for neutrons to enter the core or the nucleus in an atomic structure, it has to be travelling at just the right speed. If it’s not traveling at the right speed, it bounces off or goes through it. They piled up this material around it to absorb the neutrons so that they could determine the exact speed at which a neutron would enter a nucleus and actually fission and create a doubling of the number of neutrons exiting the nucleus.

That’s sort of the principle here. The idea is that you have a nucleus and if it’s uranium in particular, if you hit the nucleus with one neutron, two pop out. At a very small scale, that’s not much. But an atomic scale of billions, that’s a whole lot of energy. All of these experiments were about that kind of thing, to try to determine exactly how much was needed for a device and to operate and actually to work, to operate and explode.

When I first went to Los Alamos, I did find some hemispheres that were very thick aluminum, and they are pusher spheres. This aluminum sphere I machined into the exact dimensions of the Trinity device. Then these are the interior parts. This is all assembled together, and this is called “the physics package” of the Trinity device.

What happens is, at the very center there is a very tiny ball. You can see it here, and it’s plated with polonium-210. Around it, there is what they called the urchin initiator. For the longest time, I couldn’t figure out how the urchin initiator was made. Finally, I took apart a sea urchin and looked on the inside, and determined that the grooves and the points on the inside of a sea urchin, and if this was designed the right way, that these little points would break the plating seal, and the beryllium ball on the inside would give off a burst of neutrons and cause fission.

All assembled, this piece goes against this piece. This would be uranium-238, this would be plutonium that’s silver-plated, and then the beryllium on the inside. They had get assembled into a solid ball. It gets surrounded by a moderator of plastic, and then encased. 

This piece, this hemi cylinder is inserted into that sphere and that piece over there, which is also uranium-238. Then the whole thing is sealed up and that’s surrounded by eighteen inches of high explosive that when detonated blows to the inside and sets off the nuclear explosion.

The tiny little initiator, which is referred to as the urchin in several documents obtained in a variety of ways, was a challenge to make and design. The Los Alamos group chose jewelers to make that. I found jewelers to make mine. The initiator itself consists basically of a small ball of beryllium. Then it is plated with polonium-210. Outside that is the urchin initiator, which has a very rough spiky surface. That was plated also with polonium-210.

When the explosives were detonated, the sphere that I showed you earlier, which is in its current state about eighteen inches in diameter, was reduced down to something maybe seven inches in diameter, eight inches in diameter. In that massive compression, the little urchin initiator that spikes in the interior part of the initiator broke through the polonium, broke through to the beryllium, and gave a burst of neutrons, which initiated the major nuclear explosion. That’s the way that worked.

Kelly: That’s amazing, that a tiny jeweled piece—

Sanborn: Yeah. They hired jewelers to do it, so did I.

Kelly: Exquisite.

Sanborn: The only way. Nobody ever conceived of, it’s the first time anybody figured it out. It took me a long time sitting around trying to figure out how to make those things. I think, from the people who have seen it, who came up after the thing, they said it was pretty close to the idea. The one in this exhibit is smaller on purpose.

Kelly: Not the right scale. Can you talk about the cables that are snaking through this exhibit?

Sanborn:  Well, interestingly, I had seen photographs—Los Alamos sent me a package of images. Some of them I was very surprised that they sent me, but they sent them to me anyway. You can divine a whole lot of things from photographs from the 1940s.

One of the things I noticed, that there were cables on the floor and everything was kind of chaotic. The cables in my installation sort of are reminiscent of Edvard Munch’s painting of “The Scream.”

That seemed to go along with the whole thing. I liked the serpentine form of the cables. Interestingly, after the first installation at the Corcoran, one of the scientists came up to me who had worked in the lab and said, “This is nothing. It was much more chaotic and much more crazy than this.” Anyway, that’s what the cables are about.

They also went into other rooms, and so you can see in this installation where the cables are going from this room that we see here, into other rooms and other detectors and other places around the lab. You can see where they go through the wall right over there.

Kelly: Great. How about talking about the chairs, these round stools? They look so artistic.

Sanborn:  The red wooden stools that were used extensively at the lab happened to be the favorites of all the physicists, because they look exactly like a nuclear explosion, with the ring cloud around the base. You put your foot on the ring cloud that occurs when the blast happens. Then the mushroom top is an obvious metaphor for all of that. So these were favorites. I was only able to find one original, I think, maybe one and a half. The others I had to make from scratch. There are three in this installation.

Kelly: Have you ever thought of selling them? It’s quite a piece.

Sanborn:  No. They’re very special and very, very hard to find. It took a long time to find them. I didn’t get them in Los Alamos. I found them in various places around the country.

Kelly: Interesting. Now, how about those things that people were using as bird baths, but they really were plungers?

Sanborn: Yeah. The pieces that are underneath the aluminum table, which were being used as bird baths when I found them at Los Alamos, are actually pusher spheres before they’d been machined. They have sticking out of the top of them an alignment tool that attaches them to a lathe. I recognized that for what it was and realized that, well, they’re perfect. They’re the right dimension, they are perfectly the right size, so that’s why I used them. Very possibly, they were from the original period in the 1940s when they were doing the machining for the project. I did sacrifice two of those and machined them into the device that you saw earlier.

Kelly: So the pushers were the eighteen-inch diameter—

Sanborn: Yeah. It’s called dural, it’s a dural aluminum pusher sphere. It evened out the lensed explosives, it evened out the explosive and made it so that it would compress the interior into a small sphere instead of being lopsided or bumpy. The aluminum acted as a moderator for deflection or anything in the explosive. It was sort of a failsafe design and it also did compress fairly easily, because it was aluminum.

Kelly: Interesting. Then you were pointing out the—they look like bowls over there, mixing bowls.

Sanborn:  Yeah. There were two bowls on top of the polyethylene critical assembly. Those two hemispheres, when I found them, the person who had collected them had passed away. The physicist’s wife carried them up out of their basement like a chalice. They are very much prized objects. These are actually original prototypes from nuclear devices, probably post-dating Manhattan Project, probably 1950s, by the size.

But what you can see from it is, that the large pusher spheres that are in my installation are vastly bigger than those small ones that are on top of the polyethylene. Polyethylene was also used as a moderator for neutrons as well. The two small hemispheres fit together very precisely. Then inside that is a representation of a levitated core, which was a later design than the design that I did using the large pusher spheres.

One of the most famous or infamous accidents that occurred at Los Alamos was the Slotin accident. Basically, these devices that were designed at Los Alamos were spherical in nature. They were like nesting spheres, like those little Russian eggs. Each time that you encased an internal radioactive piece with a shell, it concentrated the radiation.

Behind me here is a hemisphere that’s very similar to the Slotin hemisphere, it was this kind of polished sphere. Most of these experiments, which were called tickling the dragon’s tail because, for obvious reasons, because they’re very dangerous experiments. 

Basically, Louis Slotin had supported one of the hemispheres on a screwdriver, and it slipped off. When the hemisphere went down on top of the highly radioactive interior core, it created a burst of Cherenkov radiation and very deadly radiation that ultimately killed Louis Slotin. It’s kind of like the Challenger disaster for the space program, it was for Los Alamos. It was very difficult. But it made everybody even more aware of the problems and the dangers that they were dealing with.

In doing this installation, there were several reasons I did the installation the way that I did it and when I did it. Partly it was because pure science is very seductive. The pure science of nuclear science, it is a very powerful thing. When you realize just how great the power is, you can be drawn into it very easily. That’s why the title of my book, Atomic Time, is “Pure science and seduction.” Because very often there are sciences which, when the science moves from a pure science to a technology, for example—and that goes for many different technologies—sometimes one of the technologies isn’t necessarily great for everyone. The piece is really about that moment in time where the nuclear science moved from pure science to technology.

I want people to see on the one hand how beautiful these objects were, but at the same time, beauty and the beast, they were very deadly objects. I want people to be able to see exactly and experience exactly what it felt like being in the laboratory where they assembled the first atomic bomb.

Kelly: How old were the scientists who were working on this? How much do you suppose they thought about this?

Sanborn:  I know for a fact that quite a few of the scientists involved in the project didn’t necessarily know its outcome. It was compartmentalized. The work was compartmentalized in much the same that any intelligence institution operates in, so that one aspect—one element of the assembly project, one element of the explosives branch, one element of the materials branch—they didn’t necessarily know what all of their pieces were going to build, necessarily. Very few people did. Oppenheimer was one of those people, but quite a few others didn’t.

These were younger people who had—it was not something that had been done before. There was no precedent for it. If you have something that has no precedence, you don’t necessarily always understand the ramifications of it.

It ended up being tremendously conflicted within the science community. On the one hand, you had Edward Teller. On the other hand, you had Robert Oppenheimer, which were in some ways at the antipodes of thinking at the lab, but nonetheless all worked at the same place.

Kelly: Can you elaborate a little bit about Teller and his direction versus Oppenheimer?

Sanborn: Teller was much more of a hawk and became much more of a hawk, a hawk in what he perceived as the national interest. But he was also very much taken and seduced by the massive power that was involved in thermonuclear weapons.

Teller wanted to take what was basically analog, the old early analog Trinity device and make it into something entirely different and gigantic in scale. It could have incredible ramifications for global health and science and existence. Even until his death, Teller was feeling very strongly about the need for hydrogen bombs, as opposed to the standard atomic weapons that were now going to be used as triggers for hydrogen bombs only.

Kelly: How about Oppenheimer, since he’s the antipode?

Sanborn: Robert Oppenheimer was a man of the world and understood Indian philosophy. He understood Hinduism, Buddhism, Christianity, and all of the world’s religions. When he saw the detonation of the bomb, of the Trinity device, I believe it was he that says, “I have become death.” That brought in some of the world’s great religions into the whole discussion. He felt very strongly about that his whole life. 

You also might notice that underneath the critical assembly tables, there are these large cylindrical shiny objects. If you have ever gone into an automobile shop where they raise cars up with a hydraulic piston, the guys in the lab discerned that that was a great way to robotically—I mean, one of the first robotic things that they did at Los Alamos—raise and lower highly radioactive substances into and out of the criticality experiments.

On the table that has the top half of the Trinity device, you can see there’s a plug that was pushed up inside robotically, just probably with a handle like you have in an automobile shop. They had several of these around the lab, so I’ve tried to recreate that idea. But it was really a brilliant way of—and then they could lower them down below the surface of the ground and have the radioactivity be nil, and they could bring them back up when they needed it. Very useful.

This is deuterium gas, which is interestingly one of the major components of a hydrogen bomb. I just happened to find that cylinder, so I just thought it was germane. I brought it in here as a prop, more or less. It doesn’t necessarily go with this particular piece, but I thought it was interesting to have it there. Deuterium is used for a variety of things.

Soon after I did this installation, I did another project [“Terrestrial Physics”], another five or six-year project, in which I recreated the machine that did the first fission of uranium in the United States. It was done at the Carnegie Institution. I recreated that machine and fissioned uranium in my studio using that machine.

When I first went out to the Carnegie Institution, I went into the building where that particle accelerator still sits and, went down into the basement. When that experiment took place, many of the top scientists, [Enrico] Fermi and many others were in the basement to watch the event happen.

I went into that building in 2007, and there was a little wooden box on the wall and it had a door, a little door, you know. Everywhere I went I always took my Geiger counter. I noticed that when I went into the room, my Geiger counter spiked. I went over to that, and the closer I got to that little box on the wall, the higher the readings got. I opened the door.

Lo and behold, it was full of highly volatile, incredibly explosive radioactive chemicals, including a large box of—it said “polonium-210” on it. Now, polonium-210, it has a very short half-life, so at this point in time, many, fifty years later or sixty years later, it wouldn’t have any radioactivity. But the rest of it was highly volatile. I thought that was interesting. Nobody wanted to touch it since the 1940s. They put it up on the wall, and everybody forgot about it. It was interesting.

Kelly: Did you mention it to them?

Sanborn:  They brought people in with moon suits the next week, and they removed all of it. 

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