Louis Slotin started working on the Manhattan Project in Chicago in 1942 and came to Los Alamos in 1944. Slotin assembled the core of the Gadget at Trinity—if you have seen photos from the Trinity Test, you have probably seen him in them.On May 21st, 1946 Louis Slotin was killed in a nuclear criticality accident. Slotin worked on a team involved with experiments meant to study nuclear materials at the edge of a nuclear chain reaction, without fully bringing the fissile materials to criticality.
#InsideTheArchives is Burt Sauer’s written narrative of the incident, “Louis Slotin’s Last Experiment.” Sauer brings the event into vivid clarity. He writes:
“As to what actually happened I must rely on the firsthand account of Patrick J. Cleary…According to Cleary, Slotin simply used a screwdriver to pry apart the hemispheres [of beryllium] to remove the spacers around the interface. As Slotin was removing a spacer the screwdriver slipped, the bottom hemisphere tilted in its cradle, and all the spacers fell out. The two hemispheres crashed together.
“Cleary later said that at the instant the hemispheres fell together he saw a ‘blue light’ and felt a wave of intense heat. Slotin, with hardly an instant’s hesitation, scattered the hemispheres with his hands, halting the chain reaction. The men then hurried to the gate and drove off to the infirmary in the escape cars.
“Dr. Slotin, who had been hunched over the assembly, received the highest dosage, but Cleary and Young also received heavy doses of hard radiation.”
The Slotin accident was the second fatal criticality accident. Harry K. Daghlian Jr. died in 1945 after a criticality accident on August 21, 1945.
Learn more about the Slotin accident from the American Physical Society: https://www.aps.org/publications/apsnews/201405/physicshistory.cfm
The Slotin building is one of the Los Alamos National Laboratory buildings included in the Manhattan Project National Historical Park: https://www.nps.gov/places/000/slotin-building.htm
Phil Morrison wrote an official letter reporting on the Slotin accident. In the archives we have the copy of the letter sent to Bernie Feld.
Below are scans of the original letter; a transcript is below the scans.
Gift of Peter Deutsch. Los Alamos Historical Society Photo Archives.
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P. O. Box 1663
Santa Fe, New Mexico
4 June, 1946
Dear Bernie,
The letter accompanying ends the whole affair. We are trying hard to understand the yield, and the doctors are filled with new data.
The usual hasty and not-much planned experiment was complete by the usual slip of the hands, the blue glow was seen ––– Louis was immersed in it ––– and you can read what happened.
There were a few pieces of incredible irony: the accident was on Tuesday, the 21st of May, while Harry’s was on the previous Tuesday the 21st, in August. By an error Louis was put in Harry’s room in the hospital; they died in the same bed.
There are a good many people around who appreciated Louis: he was a tough-minded but wholly sweet guy. I have never heard of anyone his enemy.
The Chicago people are planning a scholarship for him, I hear; I hope it is successful. I shall write a notice for RSI and Science.
I wish there were better news.
Yours,
(signed) Phil
Regards to Viki, Dave, Bill, etc.”
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P.O. Box 1663
Santa Fe, New Mexico
June 3, 1946
Dr. B. T. Feld
Dept. of Physics
M. I. T.
Cambridge, Mass.
Copies to C. P. Baker, E. C. Creutz, H. Newson, A. Novick, R. R. Wilson, and R. Zirkle
Dear Bernie:
This is the second and the last of the bulletins which I promised to send you on the accident here. I am again taking the liberty of sending copies of this letter to the various laboratories where I know some of Louis’ friends.
Louis died quietly, 11 a.m. the 30th of May, in the hospital here. For about twenty-four hours he had been in the last stages of high fever accompanied by irrationality and difficulty of breathing, with slight cyanosis. He was maintained in an oxygen tent for a similar period. In the early morning hours both respiration and pulse began to fail and almost imperceptibly passed over to death. Dr. Hageman was in attendance and pronounced death mostly from stethoscope signs.
The course of Louis’ illness was about like this—. For the first few days his hands bothered him, and he experienced one or two attacks of nausea. We were all, however, as cheerful as we could be, and I think that only the striking parallel between his condition and Daglian’s was a cause of great worry to him. On about the fourth day his rather good clinical condition–temperature and pulse normal, hands in slight pain–began to worsen. He had a very severe involvement of stomach and intestines which amounted to a complete stopping of their functions and resulted in severe discomfort from swelling and gas pains. At this time, also, he began to show a fever, which remained above 103 from about the fifth day. A graet deal of relief was gained by the insertion of a nasal stomach drain, which kept drawing up large quantities of liquid and which greatly reduced the pain. The fifth and sixth days were evidently very hard ones, and we began to worry a good deal about the outcome. I think, however, that Louis, while greatly concerned, retained the hope that all of us had here, until he began to enter the fever delirium at noon of the eighth day.
The hematological picture was acutely bad. Annamae Dickey came every day, or sometimes twice, to take samples, and she had a hard time concealing her distress when Louis pressed her for the results of her count. On the first two or three days the total white blood count soared but was accompanied by a sharp dop and eventual disappearance of the lymphocytes. Between the fourth and fifth days there was a precipitant drop in the total white blood count, which by the sixth day was down to 200 or 300 cells per mm3. All the experts assumed this to be a hopeless condition, but the clinical people kept on and by administration of penicillin and asceptic precautions in the room hoped to prevent infection. The worst feature of the blood picture for me, was the very sharp drop in platelet count which came on the seventh day. This was a sure sign of the hemorrhagic phase, of which we saw a good deal in Japan. Both Louis and I knew enough about”
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This to be unhappy about its coming. It is likely the next four or five days would have been very unpleasant. Allen and Nickson, from Chicago, who were here from the third day, felt that they had a specific therapy for this last phase; otherwise, there can be no regrets that the situation never came to this point.
On the day of death, autopsy was performed by a pathologist from Chicago. The findings explained the clinical picture. Immediate cause of death was probably the aspiration of fluids from the stomach into the lungs following failure of reflexes and general weakness. The organs of the abdomen were terribly swollen and otherwise heavily damaged by radiation. It is no wonder their functions had stopped. There was no sign of infection of other complications. It was a pure and simple case of death from radiation. Under the bronze erythema which covered the body, there were seen the early signs of hemorrhage, just as the platelet count had led us to believe.
We have several different approaches to the physical measurement of dose. Most satisfactory is the absolute count on sodium activation in the blood plasma by thermal neutrons slowed down by collisions in the body from the incident flux. We have in addition delayed gamma ray measurements, which allows us to compute the prompt gamma rays and make estimates on the incident fast neutron flux. Taking all this into account and using the factor of five for increased effect of the columnar ionization produced by fast neutrons and by thermal captures in nitrogen, we get an average dose of 800 ± 200 equivalent biological Roentgen. There is a great deal of chance for error in these measurements because we do not know the incident spectrum of neutrons very well. This is the dose average over the body. If you will remember that the region of the abdomen was exposed to two or three times as much flux from the geometry of the accident, the picture is consistent with the clinical finding.
Some of the physics of the event are not well understood at present. A closer discussion of this cannot be made except in a classified document. It is possible to say only that we are not quite sure what stopped the reaction.
All the other people who were present are doing extremely well indeed. Graves, whose dose is around 200 equivalent Roentgens, showed the worst symptoms, which were a moderate drop in white blood count to about 3000, and a day or two of fever–which may have been incidental infection. His count is now back nearly to normal and he shows no symptoms whatever. None of the others exhibit any clinical symptoms, and none received a dose larger than about 100 equivalent Roentgens. By tomorrow it is expected that all of the people involved will have been discharged.
Louis’ mother and father were here from the third day. They were helpful, and it was certainly good for them that they were here while Louis still was in relatively good spirits.
There are two rather moving stories that it is worthwhile to tell. When Mr. Slotin was being driven up here from Albuquerque after arriving by air, he explained why he had felt it necessary to come and why he was so much concerned. ‘Louis was my oldest son,’ he said, ‘and every father loves his son. But there was more than that—there was respect for Louis, for a learned man.” —— On the morning after Louis died, Hageman and I explained to Mr. Slotin about the need for an”
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Autopsy. He told us that it was against the traditions of the family and that he would be criticized for it when he returned to Winnipeg; but he gave permission for it now. He said that Louis had been a scientist all his life, and that when it could do him no harm, it would be wrong to prevent him from adding to knowledge.
We are anxious to give Louis’ books to some place where they will be of use to students. We think that the University of Chicago can find some place for them. Louis was intending to go there, as you know, upon his return from Bikini.
This has not been an easy letter to write, but it is the kind of letter that Louis would have written had he been able to.
Yours sincerely,
P. Morrison
PM: bjd
Copies as indicated at beginning.”
