A Reluctant Division Leader

Robert R. Wilson, P-Division Leader (1944-1945)

No! No! No! I won’t do it!” I shouted at Oppenheimer, who had just offered me the job of heading the new Research (R) Division at Los Alamos.

The year was 1944, and the Laboratory was being reorganized because of the discovery of the high rate of spontaneous fission in plutonium. Bob Bacher headed the old Experimental Physics Division, which had been split into two new divisions in August of that year. One part became Gadget (G) Division, which was to develop a plutonium bomb based on Seth Neddermyer’s implosion ideas. The other part became R Division, which would consist of the remaining four groups from the Experimental Physics Division: the Cyclotron Group (R-1), headed by me; the Electrostatic Group (R-2), headed by John Williams; the D-D (Deuterium-Deuterium) Group (R-3), headed by John Manley; and the Radioactivity Group (R-4), headed by Emilo Segré.

“Look, Oppie. Just pick one of the other three Group Leaders. They’re all much more senior than I am, and each would hate working for a young fella like me,” I explained.

“Not as easy as you think,” responded Oppie. “I have already tried to pick, in turn, each one of them, but in each case, the other two threatened to quit. So you, Bob, are elected, faute de mieux.”

“No, not me! I did not come here to be an administrator. Why don’t you just bite-the-bullet, chose one, and let the chips fall where they may,” I responded.

“I thought I had done just that in selecting you,” Oppie said weakly.
“Well, bite a different bullet then, because I came here to do physics and not to become and administrator,” I replied, looking him straight in the eye at the implied criticism of him.

“Maybe we ought to think about it,” Oppie sighed as he ambled away as only Oppie could in his crazy, but characteristic, gait.

The next day, Enrico Fermi asked me to accompany him on a walk. He had been sent by Oppie to talk me into the R-Division job.
“You’re a fine friend,” I said after hearing him out, “for I have been following your example in turning it down. You would never do that sort of thing.”

Fermi’s eyes sparkled. “It’s something you have to earn, and you’re not Fermi yet!”

He then went on to instruct me on how to avoid administrative duties. Essentially, it came down to just saying no.

“Yeah, but how about all the technical work of the other groups. Wouldn’t I need to know about it in detail?” I asked.

I was, up to this point, doing a pretty good job of saying no to Fermi when suddenly he volunteered to help me with the technical work. I was astounded. I could hardly believe my ears. The idea of working with Fermi made it a whole new ball game. I had worked with him on the reactor project at Columbia University, so I knew what a valuable experience working and learning from Fermi could be—never mind all the delightful fun of just being with him.

Fermi promised that he would be available whenever a problem came up. To clinch our bargain, we agreed to meet together every Friday after lunch to discuss the physics being done in the Division and also the physics that should be done. I was ready at that point to sell my soul for this chance, but I still had a few conditions for Oppenheimer. One was that I could continue as Group Leader of the Cyclotron Group; another was that I not have a special office with a secretary. Finally, I insisted that each of the other Group Leaders ask me personally to take the job. Sure, I sold out—but then everyone has his price, and mine was a few moments each week with Fermi.

In any event, my life was little changed except for the delightful weekly meetings with Fermi. Usually in our discussions, a student-teacher relationship prevailed in which Fermi clarified the physics by simplifying it to a level I could understand—he was a master at that. Nor was it that I was completely unintelligent, for perhaps I knew more about accelerators and particle detectors than he did. We made a pretty good pair.

As Division Head, I gave the Group Leaders essentially free reign. Happily, I had never heard about people staying in channels because Oppie would usually go directly to the person concerned. On the other hand, I would get several calls every week from him about the practicality of experiments being considered for our Division, as well as an ordering of the priorities for the whole project. I always had the feeling of knowing too much rather than too little about what was going on at Los Alamos.

One of my duties as a Division Head was to attend the weekly meetings of the Administrative Board. We usually considered serious matters involving the project. But on the light side, I recall that Joe Kennedy and I had dedicated ourselves to making the life of the G-2 army security officer miserable. We would hit him both coming and going. His security measures either grossly interfered with the work of the project, or they seemed to us to be totally inadequate.

Once, I remember Kennedy giving this particular officer a hard time about not providing enough surveillance. The officer remarked, “Joe, how do you know that the little kid who followed you over here was not one of my agents?”
Kennedy looked at him coldly for a few moments and responded, “Yeah, if he’s your agent, he’s your best agent.”

Actually, the meetings were exciting for we were kept abreast of all sorts of important information about the project, such as when and how much 235U and plutonium would be made available to us.

Sometime in March 1945, the nature of R Division changed dramatically. We were given, in addition to what we were then doing, the responsibility for measuring the nuclear phenomena resulting from the test explosion of the first atomic bomb. This test was to be made in the Jornado del Muerto desert near Soccoro, New Mexico. Philip Moon of the British Mission had already done some preliminary design and construction. But time was running short and not much was getting done, so Oppie asked us to reconsider the whole problem about what experiments should be conducted for the Trinity Test. We pitched in with gusto to do what could be done in the three or four months remaining before the expected time of the test shot.

Fermi was particularly interested in this phase of the project. He and I used our regular discussions as one way of satisfying his interest. Of course, he had many other channels open to him, and I am sure he used them too.

As I recall, the members of our Division decided who would do what, not by general meetings, but by meetings between me and the individual Group Leaders. My procedure was simply to inform them of what had to be done and to ask them what they wanted to do. After they had discussions within their groups, they came back to me with a list of who would do what. I suppose there was a bit of pushing and pulling, but somehow we easily came up with plans that covered all the measurements that needed to be done, and then we made the equipment and installed it in the desert. Writing this now, it sounds authoritarian and perhaps it was. But I think not, for we were such a small Division (perhaps about 40 physicists) that we all interacted frequently enough so that no formality was necessary—or so I thought.

My continued meetings with Fermi were pure pleasure—well, with one exception. My usual function seemed to be to bring up problems that, to my great satisfaction and admiration, Fermi elegantly solved without much participation on my part. Only occasionally, would I argue with Fermi’s physics, and then with great trepidation—he was just terribly good. I did learn a lot because he worked out what he was doing in a very clear manner that I could easily follow. Yet being human, I wanted to participate more in the physics process.

I do remember once, though, when, to my great satisfaction, I caught him in an egregious error. Then without remorse, I made him suffer for being right so much of the time. This joyous occasion occurred when I had invented a device for measuring the rate of increase of neutrons (the e-folding time) during the explosion of the bomb. An electron-multiplier tube was to be used to measure the radiation as it emerged from the detonation of the bomb. Fermi thought about this for a few seconds, went through his calculations, and then informed me that it would not work.

“Too slow,” he said with his usual confidence, “by a factor of hundreds compared with the 10-8 second resolution you expect.” I informed him that that must be wrong. Again Fermi went through his calculations, this time out loud and slowly for my benefit. “My dear Enrico, you are losing your grip. Perhaps its too elementary,” I said with an assurance that worried Fermi slightly. He made more calculations, this time on a piece of paper, again with the wrong result. He had made an error that I knew he was not likely to find. That put me for once in the “catbird seat.”

Fermi’s error was due to our custom at Los Alamos of finding a particle’s speed at some energy by simply scaling up that of a thermal neutron. Fermi had been doing this automatically over the past years, and he was not likely to break out of this ingrained habit. I let him wallow in his misconception while I privately delighted at his discomfort. Eventually, I asked him, to his embarrassment, if he had ever heard that electrons were 1,800 times less massive than neutrons.

We tended at first to be somewhat casual about the Trinity Test. One day, John Dewire and I were discussing possible electrical pick-up signals in the various detectors being built. We knew that the next day there would be a test explosion of 100 tons of TNT at the site of the future test. We asked ourselves whether or not we could find out anything from the explosion. Well, no, we decided. But just seeing it might be a valuable experience for us—or at least some fun. So on a whim, we called Oppie’s office to tell the guards at Trinity site that we were on our way. Then we put a portable electrical generator, a long coil of electric cable, and an oscilloscope into a pick-up truck; stopped to tell our wives (we did not have telephones in our private homes); and headed for Trinity Site some 200 miles to the south. It was dark when we got there, and we had to talk our way into the site past the guards. We were able to spend the night in the crude barracks at the base camp. The next morning, we drove over to where about a dozen people were stacking a huge pile of boxes of TNT. We joined in and helped stack boxes for awhile—strangely, no one else seemed worried about dropping a box because, I gathered, a detonator was required to start an explosion. But I was worried!

Soon, I had an idea for our experiment—simply to put the shorted end of our cable deep into the pile and then run the cable several hundred feet away from the pile to our oscilloscope and gasoline-powered generator. Not much of an experiment, I must say, but it was better than stacking boxes of TNT! Of course we expected no signal. That night, we found the explosion impressive. It even had a quality of beauty. The next morning, we developed the photograph, which had automatically been made of the scope trace. To our surprise, there were huge signals. We had to understand the source of those signals, how much worse they would be in the ambiance of an exploding atomic bomb a hundred times more powerful, and how we should shield against them. This unexpected finding was a good example of the value of laziness and fear.

Back at Los Alamos, significantly large amounts of separated 235U began to arrive from Tennessee. One experiment that I can recall was to measure the multiplication of neutrons in a sphere of this material about 1 in. in diameter. Oppie insisted that the material be guarded all the time. For some reason, Fermi’s personal guard, John Baudino, was assigned to us. In fact, there were two identical spheres, one of 235U and the other of normal uranium. We were to make a comparison of the two. I liked to amuse myself by switching the spheres around rapidly and then asking Baudino which sphere was the one he was guarding. He would confess that he did not know and would ask which one should he be guarding. I could tell because the 235U was warmer because of its greater radioactivity.

We wanted the measurements to go on all night, but we had to stop so that Baudino could sleep. I had the idea that were I to be issued a pistol, then I could do all the guarding myself—after all, I came from Wyoming where every red-blooded boy learned to shoot before he could walk. Oppie agreed and asked security to issue a pistol to me. My friend, Pier de Silva, agreed to do so, but he reasonably insisted that I be checked out first on whether in fact I could safely use a pistol. This he did by taking me to the firing range, pulling out a .38 Colt police revolver, and giving me a lecture on its use.

“This little lever is the trigger. These little gadgets are cartridges and should be put in these holes that spin around here. You line up the front of the gun with this v-shaped hickey in back and with what you are shooting at. Here, I’ll show you,” de Silva said. With that, he carefully fired six shots at a target.

“Now you do it,” he said, loading the gun. I had learned in Wyoming to “roll” a pistol in order to get a lot of shots off accurately and rapidly. That’s just what I did. Most of my shots were closer to the bull’s eye than were his.
None of this fazed de Silva in the slightest. He repeated his earlier lecture in its entirety, together with his demonstration. He finally wrote out a beginner’s certification and issued the revolver to me for the duration of the experiment. He had put on a terrific show; not once did he crack a smile!

I took full advantage of the pistol to impress my friends with what a macho type I was. I carried it, ostentatiously tucked into my belt, everywhere in the technical area and spent no little time at all explaining to the military police why I had the gun; eventually I had to show them de Silva’s authorization. When the experiment was completed a week or so later, I was most reluctant to give it back. I am proud to this day that the uranium spheres had not been stolen on my watch!

I became involved in a dispute with G Division that did not end well. As more and more 235U and plutonium was delivered to us toward the end of 1944, measurements of assemblies close to criticality were started by the Critical Assemblies Group of G Division. At first, these measurements involved small cubes of uranium hydrides (such as UH10), which were stacked up into larger cubes until criticality was approached. Later, less hydrogen was used, and the procedure became more serious—more dangerous. The Critical Assemblies Group decided not to have the elaborate safety devices that were used, for example, with cyclotrons. Instead, they decided to depend on their wits alone. These physicists were the best and the brightest of the project. So although I did not like their arguments, I could see that there were good reasons for going ahead as they had decided. For instance, each assembly might be quite different. After expressing my views forcibly, I subsided. After all, they were not in my Division, and indeed it was none of my business—well, in a fashion.

A few months later, I became more involved because they wanted to use the fast modulation of the cyclotron (neutron pulses of less than a tenth of a microsecond), which was okay of course. I was the crew member whose turn it was to help the single physicist who showed up. His equipment consisted of a small wooden table, a single neutron counter, and boxes containing the small cubes of enriched uranium hydride. I was impressed by the simplicity of the equipment, as advertised, “So simple nothing could go wrong.” Not quite. The physicist began stacking the uranium cubes as I stood next to him and watched with considerable interest. It was my first experience with a prompt neutron reactor approaching criticality, and I was thrilled in expectation.

After a while, as the stack got quite large, I asked why the neutron counter was not counting. I was assured that this was regular and that it would not start counting until we were closer to the critical point. Uncomfortably, I gave the neutron counter a hard going over and asked if the signal light on the high-voltage supply was operative or it if was burned out—as was often the case. The voltage was indeed turned off, so the neutron counter was not working. When the voltage was turned on, the counter to my horror started blazing away. A few more cubes, and the stack would have exceeded criticality and could well have become lethal.

I was outraged. This incident was my closest brush with death. The reason given was that a wooden table instead of a metal table was being used for the first time, so thermal neutrons were reducing the critical point. After chewing out the physicist for his carelessness, I went to his Group Leader. Not satisfied, I complained to the Division Leader. Still not satisfied, I flew into a fit of anger over the incident with Oppenheimer. At the time, we were all hysterically busy. I was due back at Trinity the next day. And I went there. Of course, I should have stayed at Los Alamos to pursue the incident further—for if I had, I might have saved the lives of two people. To this day, the incident is on my conscience.

The Trinity Test was soon upon us. R Division had occupied the North Bunker at 10,000 yards from the bomb locality and had acquitted themselves well, not that any credit was due to me, but I still take great pride in them—however, Trinity is a separate story.

Once we had seen the explosion in all its grandeur and implied horror, we did not need any of our measurements to know it was a success—they would have been more meaningful had it failed. I exulted with my colleagues in the gratification we felt in a job that had taken five long years of dedicated hard work. It was an epiphany for all of us. For what had been theoretical before had now become all too real—but in a different way for each one of us.

For me, the project was over. I could hardly wait for John Manley to take over the Division and to reorganize it into the Physics Division that now bears little resemblance to the tiny group we were then.

Do I regret my fall from grace—from being a pure physicist to becoming an administrator of sorts? No. If Paris were worth a mass as Henry IV had said, then surely Fermi was worth my fall from grace.

LA-12501-PR

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