Salisbury Visits Los Alamos

During the first part of March, 1945, I was still in London with the war in Europe essentially over and my work there completed. Dr. Robertson, a Theoretical Physics Professor from Cal Tech, was in charge of the London O.S.R.D. office.  He was a well known expert in "General Relativity Theory". I was having interesting discussions with him regarding the apparent difference in the effect of a kinematic acceleration and a gravitational acceleration on a light beam crossing a laboratory room. The factor of two difference in these two cases seemed to me to be contrary to Einstein's dictum that all accelerations should be equivalent when geometrical factors were properly accounted for. I was being told that in General Relativity E was not always equal to Mc² and that I was a bit too stupid to understand the real workings of the theory.  I was finding it difficult to accept these dicta and wondering how to readjust the theory to rid it of this and other contradictions.  Meanwhile, I was trying to arrange transportation home to the U.S.A.  The British felt I had done my job and they had no real urgent. reason to upset air priorities for my personal convenience.  Our London Embassy was taking essentially the same attitude. 

A break came in the form of a cablegram addressed to me at the O.S.R.D. Office. It was brief but had approval of the Manhattan Project. The cable read "come at once, you know where, signed Louis!"

I was not officially supposed to know about the Manhattan Project, but most U. S. Physicists knew much more about it than General Groves would have approved. Especially those of us connected with the O.S.R.D.  The general never seemed to catch on that his secrecy system worked rather well by courtesy and patriotism of the American physical society. In fact, the leaks which finally occurred were due to official inadequacy and official scorn of Physicist suggestions about personnel.

'Louis' was Dr. Louis Alvarez, my long time friend from Cyclotron times in the Lawrence Lab at Berkeley. 'You know where' was the lab at Los Alamos, New Mexico.

Armed with this I was able to get space on a Pan Am flying boat which was going the long way to avoid head winds with a load of War Brides.

It took me seven days to reach New York, and another day to get priority back to Boston.  In Cambridge at the Harvard Radio Research Lab, I found that although I had already agreed to go the Collins Radio Company ad Director of Research after my war duties were complete.

Dr. Sam Goudsmidt was offering me a position on his project A.L.S.O.S. to retrieve German War science for the U.S.A. I turned this down on the basis that I had no real knowledge of the German language.  I probably missed a great adventure and a very different career.

The officials of Harvard Radio Research Lab agreed to keep paying my salary and I went as rapidly as I could to Santa Fe, New Mexico.

There, Louis Alvarez and Ed McMillan met me and shepherded me through the security requirements and up to the Los Alamos laboratory.

There I found many old friends and acquaintances. Louis proudly showed me all the facilities just as he had at my first arrival at M.I.T. for the radar development.  At M.I.T. he explained the "new to me" principles of Radar and quickly exposed me to all the new problems requiring solution.

My tour of Los Alamos lab facilities was a nostalgic repeat of M.l.T.  One of the first things at Los Alamos was Louis showing me the huge walk-in safe, to which he had the combination.  This was important because I saw materials in size and form entirely new to me.

The safe contained spheres of precious metals in extremely pure form available for neutron cross section work. (Alvarez, with my friend and associate at Harvard Radio Research Lab, Prof. Felix Block, had been a pioneer in the study of spin polarized neutron beams.  In the Lawrence Lab in Berkeley, I often was in charge of running the cyclotron to produce neutrons for their experiments.)

So, I held in my hand at that Los Alamos safe a 7 cm. sphere of solid gold and a similar one of Platinum, a small one of Iridium, also one of Silver and one of U²³⁸.  But most impressive, I held a hemisphere (about a half critical mass) of Plutonium (worth at that time at least 1 billion dollars).

The Plutonium was silver plated for handling since plutonium is a strong poison as well as being appreciably radioactive. In fact,. while the other spheres had the usual cold feel of room temperature metals, the plutonium was evolving enough energy from continued radioactive decay to feel quite warm to the touch, a considerable contrast to the other spheres.

This was an exciting show for me that I will never forget. Alvarez had insisted that Robert Oppenheimer  have me there as "the" expert on electronic warfare to assess the vulnerability of the tail warning radars that had been assembled to trigger the bombs to be dropped on Japan.  These were arranged to give an exact height above ground for the explosion.  Redundancy was built in a very wise precaution.

Housing was tight and I was assigned to share a room with Robert's brother, Frank Oppenheimer, whom I knew casually from the time at the Lawrence Cyclotron Lab.

I rapidly found several weak points about the proposed system including poorly shielded I.F. amplifiers and a weakness for Chaff interference.  We worked these problems out of the system rapidly and Robert Oppenheimer seemed pleased that I had come.

Several interesting incidents occurred during the short time I was there before going to my new job at Collins Radio Co.

A series of experiments were under way to determine the critical mass for U²³⁸ and for Plutonium. This represents a very small energy release of about 0.164 ergs per second or 1417 ergs per day.  This is insignificant as heat energy but because of the high initial particle energy may represent the destruction of a significant number of protein molecules or DNA-RNA gene chains per day. (Some arguments have been proposed that this is the primary cause of human aging.)

This is a body dosage [Ref. (2) ] of 0.0002 rad. per day. Admittedly a small dosage (0.07 rad. per year). In other terms about 10^-4 microcuries of radioactivity in an average human body.

(3) Nevertheless, it is about half the dosage observed outside the Three Mile Island disaster, and is a fact of life for everyone. 

There is a minimum radioactivity dosage we all must live with. Human biology is so variable, however, that a sensible accounting of threshold effects appears unlikely.

During my short stay of a few weeks at Los Alamos, there were a number of interesting events.  My old friend from Lawrence Lab, Robert Cornoy, was there and later was credited as inventor on one of the patents of one type of fission bomb. I had last seen him at Princeton University where he had been working with Robert Wilson on the Wilson method Uranium isotope separation. Robert was a great athlete. He lived back of the cyclone fenced compound where the Los Alamos research was centered. He decided it was unnecessarily far from his house at Los Alamos to the front gate of the compound where everyone presented credentials and picture badges to get in to work. So, Bob found somewhere a vaulting pole and vaulted over the fence at the back each morning on the way to work. Since he had no pole in the compound he was forced to go home by going through the gate. After about three months of this, he was caught and reprimanded because some one finally noticed a discrepancy between the number of people going in and out of the gate.  Strangely, years later in a McCarthy probe, the F.B.I. said this pole vaulting episode proved Robert was a "red".