Louis Alexander Slotin (1 December 1910 – 30 May 1946) was a Canadian

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

and

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...

who took part in the

Manhattan Project The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project w ...

. Born and raised in the North End of

Winnipeg Winnipeg () is the capital and largest city of the province of Manitoba in Canada. It is centred on the confluence of the Red and Assiniboine rivers, near the longitudinal centre of North America. , Winnipeg had a city population of 749 ...

, Manitoba, Slotin earned both his Bachelor of Science and Master of Science degrees from the

University of Manitoba The University of Manitoba (U of M, UManitoba, or UM) is a Canadian public research university in the province of Manitoba.King's College London King's College London (informally King's or KCL) is a public research university located in London, England. King's was established by royal charter in 1829 under the patronage of King George IV and the Duke of Wellington. In 1836, King's ...

in 1936. Afterwards, he joined the

University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...

as a research associate to help design a

cyclotron A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Jan ...

. In 1942, Slotin was invited to participate in the Manhattan Project, and subsequently performed experiments with

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

and

plutonium Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exh ...

cores to determine their

critical mass In nuclear engineering, a critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties (specifically, its nuclear fi ...

values. After

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

he continued his research at

Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

. On 21 May 1946, he accidentally began a fission reaction which released a burst of hard radiation. He was rushed to the hospital and died nine days later on 30 May. Slotin had become the victim of the second criticality accident in history following Harry Daghlian, who had been fatally exposed to radiation by the same " demon core" that killed Slotin. Slotin was hailed as a hero by the United States government for reacting quickly enough to prevent the deaths of his colleagues. However, some physicists argue that Slotin's behavior preceding the accident was reckless and that his death was preventable. The accident and its aftermath have been dramatized in several fictional and non-fiction accounts.

Early life

Louis Slotin was the first of three children born to Israel and Sonia Slotin,

Yiddish Yiddish (, or , ''yidish'' or ''idish'', , ; , ''Yidish-Taytsh'', ) is a West Germanic language historically spoken by Ashkenazi Jews. It originated during the 9th century in Central Europe, providing the nascent Ashkenazi community with a ve ...

-speaking

Jewish Jews ( he, יְהוּדִים, , ) or Jewish people are an ethnoreligious group and nation originating from the Israelites Israelite origins and kingdom: "The first act in the long drama of Jewish history is the age of the Israelites""The ...

refugees who had fled the pogroms of Russia to

Manitoba Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...

. He grew up in the North End neighborhood of Winnipeg, an area with a large concentration of Eastern European immigrants. From his early days at Machray Elementary School through his teenage years at St. John's High School, Slotin was academically exceptional. His younger brother, Sam, later remarked that his brother "had an extreme intensity that enabled him to study long hours." At age 16, Slotin entered the

University of Manitoba The University of Manitoba (U of M, UManitoba, or UM) is a Canadian public research university in the province of Manitoba.B.Sc. degree in geology from the university in 1932 and a M.Sc. degree in 1933. With the assistance of one of his mentors, he obtained a fellowship to study at

King's College London King's College London (informally King's or KCL) is a public research university located in London, England. King's was established by royal charter in 1829 under the patronage of King George IV and the Duke of Wellington. In 1836, King's ...

under the supervision of Arthur John Allmand, the chair of the chemistry department, who specialized in the field of applied

electrochemistry Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an out ...

and

photochemistry Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet ( wavelength from 100 to 400 nm), visible light (400� ...

King's College London

While at King's College London, Slotin distinguished himself as an

amateur boxer Amateur boxing is a variant of boxing practiced at the collegiate level, at the Olympic Games, Pan American Games and Commonwealth Games, as well as many associations. Amateur boxing bouts are short in duration, comprising three rounds of three ...

by winning the college's amateur bantamweight boxing championship. Later, he gave the impression that he had fought for the Spanish Republic and trained to fly a fighter with the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

. Author Robert Jungk recounted in his book '' Brighter than a Thousand Suns: A Personal History of the Atomic Scientists'', the first published account of the

, that Slotin "had volunteered for service in the

Spanish Civil War The Spanish Civil War ( es, Guerra Civil Española)) or The Revolution ( es, La Revolución, link=no) among Nationalists, the Fourth Carlist War ( es, Cuarta Guerra Carlista, link=no) among Carlism, Carlists, and The Rebellion ( es, La Rebeli ...

, more for the sake of the thrill of it than on political grounds. He had often been in extreme danger as an anti-aircraft gunner." During an interview years later, Sam stated that his brother had gone "on a walking tour in Spain" and he "did not take part in the war" as previously thought. Slotin earned a Ph.D. degree in

physical chemistry Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistica ...

from King's College London in 1936. He won a prize for his thesis entitled "An Investigation into the Intermediate Formation of Unstable Molecules During some Chemical Reactions." Afterwards, he spent six months working as a special investigator for

Dublin Dublin (; , or ) is the capital and largest city of Ireland. On a bay at the mouth of the River Liffey, it is in the province of Leinster, bordered on the south by the Dublin Mountains, a part of the Wicklow Mountains range. At the 2016 ...

Great Southern Railways The Great Southern Railways Company (often Great Southern Railways, or GSR) was an Irish company that from 1925 until 1945 owned and operated all railways that lay wholly within the Irish Free State (the present-day Republic of Ireland). The ...

, testing the Drumm nickel-zinc rechargeable batteries used on the Dublin–Bray line.

Career

University of Chicago

In 1937, after he unsuccessfully applied for a job with Canada's National Research Council, the

accepted Slotin as a research associate. There, he gained his first experience with nuclear chemistry, helping to build the first

in the midwestern United States. The job paid poorly and Slotin's father had to support him for two years. From 1939 to 1940, Slotin collaborated with Earl Evans, the head of the university's biochemistry department, to produce radiocarbon (

carbon-14 Carbon-14, C-14, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and co ...

and

carbon-11 Carbon (6C) has 15 known isotopes, from to , of which and are stable. The longest-lived radioisotope is , with a half-life of years. This is also the only carbon radioisotope found in nature—trace quantities are formed cosmogenically by ...

) from the cyclotron. While working together, the two men also used carbon11 to demonstrate that

plant cell Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capab ...

s had the capacity to use

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

for

carbohydrate synthesis Carbohydrate synthesis is a sub-field of organic chemistry concerned specifically with the generation of natural and unnatural carbohydrate structures. This can include the synthesis of monosaccharide residues or structures containing more than on ...

, through

carbon fixation Biological carbon fixation or сarbon assimilation is the process by which inorganic carbon (particularly in the form of carbon dioxide) is converted to organic compounds by living organisms. The compounds are then used to store energy and as ...

. Slotin might have been present at the start-up of

Enrico Fermi Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" an ...

's "

Chicago Pile-1 Chicago Pile-1 (CP-1) was the world's first artificial nuclear reactor. On 2 December 1942, the first human-made self-sustaining nuclear chain reaction was initiated in CP-1, during an experiment led by Enrico Fermi. The secret development of ...

", the first

nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat fr ...

, on 2 December 1942; the accounts of the event do not agree on this point.A 1962 University of Chicago document says that Slotin "was present on 2 December 1942, when the group of 'Met Lab' etallurgical Laboratoryscientists working under the late Enrico Fermi achieved man's first self-sustaining nuclear chain reaction in a pile of

graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on la ...

and uranium under the West Stands of

Stagg Field Amos Alonzo Stagg Field is the name of two successive football fields for the University of Chicago. Beyond sports, the first Stagg Field (1893–1957) is remembered for its role in a landmark scientific achievement of Enrico Fermi and the Metall ...

." Slotin's colleague, Henry W. Newson, recollected that he and Slotin were not present during the scientists' experimentation. During this time, he also contributed to several papers in the field of

radiobiology Radiobiology (also known as radiation biology, and uncommonly as actinobiology) is a field of clinical and basic medical sciences that involves the study of the action of ionizing radiation on living things, especially health effects of radiation. ...

. His expertise on the subject garnered the attention of the United States government, and as a result he was invited to join the Manhattan Project, an effort to develop an

atomic bomb A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bomb ...

. Slotin worked on the production of

under future

Nobel laureate The Nobel Prizes ( sv, Nobelpriset, no, Nobelprisen) are awarded annually by the Royal Swedish Academy of Sciences, the Swedish Academy, the Karolinska Institutet, and the Norwegian Nobel Committee to individuals and organizations who make o ...

Eugene Wigner Eugene Paul "E. P." Wigner ( hu, Wigner Jenő Pál, ; November 17, 1902 – January 1, 1995) was a Hungarian-American theoretical physicist who also contributed to mathematical physics. He received the Nobel Prize in Physics in 1963 "for his co ...

at the university and later at the

Oak Ridge National Laboratory Oak Ridge National Laboratory (ORNL) is a U.S. multiprogram science and technology national laboratory sponsored by the U.S. Department of Energy (DOE) and administered, managed, and operated by UT–Battelle as a federally funded research an ...

in Oak Ridge,

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. Tennessee is the List of U.S. states and territories by area, 36th-largest by ...

. He moved to the

in December 1944 to work in the bomb physics group of

Robert Bacher Robert Fox Bacher (August 31, 1905November 18, 2004) was an American nuclear physicist and one of the leaders of the Manhattan Project. Born in Loudonville, Ohio, Bacher obtained his undergraduate degree and doctorate from the University of Mic ...

Work at Los Alamos

At Los Alamos, Slotin's duties consisted of dangerous criticality testing, first with

Otto Robert Frisch Otto Robert Frisch FRS (1 October 1904 – 22 September 1979) was an Austrian-born British physicist who worked on nuclear physics. With Lise Meitner he advanced the first theoretical explanation of nuclear fission (coining the term) and first ...

's experiments, and later with plutonium cores. Criticality testing involved bringing masses of

fissile In nuclear engineering, fissile material is material capable of sustaining a nuclear fission chain reaction. By definition, fissile material can sustain a chain reaction with neutrons of thermal energy. The predominant neutron energy may be t ...

materials to near-critical levels to establish their

values. Scientists referred to this flirting with the possibility of a

nuclear chain reaction In nuclear physics, a nuclear chain reaction occurs when one single nuclear reaction causes an average of one or more subsequent nuclear reactions, thus leading to the possibility of a self-propagating series of these reactions. The specific nu ...

as "tickling the dragon's tail", based on a remark by physicist

Richard Feynman Richard Phillips Feynman (; May 11, 1918 – February 15, 1988) was an American theoretical physicist, known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, the physics of the superfl ...

, who compared the experiments to "tickling the tail of a sleeping dragon". On 16 July 1945, Slotin assembled the core for

Trinity The Christian doctrine of the Trinity (, from 'threefold') is the central dogma concerning the nature of God in most Christian churches, which defines one God existing in three coequal, coeternal, consubstantial divine persons: God th ...

, the first detonated atomic device, and became known as the "chief armorer of the United States" for his expertise in assembling nuclear weapons. Slotin received two small circular lead and silver commemorative pins for his work on the project. Louis Slotin and the Gadget Bomb

In the winter of 1945–1946, Slotin shocked some of his colleagues with a bold action by repairing an instrument under water inside the Clinton Pile while it was operating, rather than wait an extra day for the reactor to be shut down. He did not wear his

dosimetry Radiation dosimetry in the fields of health physics and radiation protection is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both internally, due to ingested ...

badge, but his dose was estimated to be at least 100 roentgen. A dose of 1 Gy (~100 roentgen) can cause nausea and vomiting in 10% of cases, but is generally survivable.

Harry Daghlian's death

On 21 August 1945, laboratory assistant Harry Daghlian, one of Slotin's close colleagues, was performing a criticality experiment when he accidentally dropped a heavy

tungsten carbide Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms. In its most basic form, tungsten carbide is a fine gray powder, but it can be pressed and formed into ...

brick onto a plutonium–gallium alloy bomb core. The 24-year-old Daghlian was irradiated with a large dose of

neutron radiation Neutron radiation is a form of ionizing radiation that presents as free neutrons. Typical phenomena are nuclear fission or nuclear fusion causing the release of free neutrons, which then react with nuclei of other atoms to form new isotopes— ...

. Later estimates suggested that this dose might not have been fatal on its own, but he then received additional delayed

gamma radiation A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically s ...

and beta burns while disassembling his experiment. He quickly collapsed with acute radiation poisoning and died 25 days later in the Los Alamos base hospital.

Planned return to teaching

After

, Slotin expressed growing disdain for his personal involvement in the project. He remarked, "I have become involved in the

Navy A navy, naval force, or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or ocean-borne combat operations and related functions. It in ...

tests, much to my disgust." Unfortunately for Slotin, his participation at Los Alamos was still required because, as he said, "I am one of the few people left here who are experienced bomb putter-togetherers." He looked forward to resuming teaching and research into

biophysics Biophysics is an interdisciplinary science that applies approaches and methods traditionally used in physics to study biological phenomena. Biophysics covers all scales of biological organization, from molecular to organismic and populations. ...

and radiobiology at the University of Chicago. He began training a replacement, Alvin C. Graves, to take over his role at Los Alamos.

Criticality accident

On 21 May 1946, with seven colleagues watching, Slotin performed an experiment that involved the creation of one of the first steps of a fission reaction by placing two half-spheres of

beryllium Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to for ...

(a neutron reflector) around a plutonium core. The experiment used the same plutonium core that had irradiated Daghlian, later called the " demon core" for its role in the two accidents. Slotin grasped the upper 228.6 mm (9-inch) beryllium hemisphere with his left hand through a thumb hole at the top while he maintained the separation of the half-spheres using the blade of a screwdriver with his right hand, having removed the shims normally used. Using a screwdriver was not a normal part of the experimental protocol. At 3:20 p.m., the screwdriver slipped and the upper beryllium hemisphere fell, causing a "

prompt critical In nuclear engineering, prompt criticality describes a nuclear fission event in which criticality (the threshold for an exponentially growing nuclear fission chain reaction) is achieved with prompt neutrons alone (neutrons that are released immed ...

" reaction and a burst of hard radiation. At the time, the scientists in the room observed the blue glow of air ionization and felt a heat wave. Slotin experienced a sour taste in his mouth and an intense burning sensation in his left hand. He jerked his left hand upward, lifting the upper beryllium hemisphere, and dropped it to the floor, ending the reaction. He had already been exposed to a lethal dose of neutron radiation. At the time of the accident, dosimetry badges were in a locked box about from where the reaction occurred. Realizing that no one in the room had their film badges on, "immediately after the accident Dr. Slotin asked Dr. Raemer E. Schreiber to have the badges taken from the lead box and placed on the critical assembly". This peculiar response was of no value for determining the actual doses received by the men in the room and put Schreiber at "great personal risk" of additional exposure. A report later concluded that a heavy dose of radiation may produce

vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...

and can leave a person "in no condition for rational behavior." As soon as Slotin left the building he vomited, a common reaction from exposure to extremely intense

ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...

. Slotin's colleagues rushed him to the hospital, but the radiation damage was irreversible. The seven other men present at the time of the reaction included Alvin Cushman Graves, Samuel Allan Kline, Marion Edward Cieslicki, Dwight Smith Young, Theodore P. Perlman, and

Pvt. A private is a soldier, usually with the lowest rank in many armies. Soldiers with the rank of Private may be conscripts or they may be professional (career) soldiers. The term derives from the medieval term "private soldiers" (a term still us ...

Patrick J. Cleary. There have been five studies done of the amount of radiation each person involved received in the accident; these are the latest, dated 1978, from a table in this reference. By 25 May 1946, four of these seven men had been discharged from hospital. The

United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, ...

physician responsible for the Los Alamos base hospital,

Captain Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police department, election precinct, e ...

Paul Hageman, said that Slotin's, Graves', Kline's and Young's "immediate condition is satisfactory."

Slotin's death

Despite intensive medical care and offers from numerous volunteers to donate blood for transfusions, Slotin's condition was incurable. He called his parents and they were flown at Army expense from Winnipeg to be with him. They arrived on the fourth day after the incident, and by the fifth day his condition started to deteriorate rapidly. Over the next four days, Slotin suffered an "agonizing sequence of radiation-induced traumas", including severe

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin w ...

, reduced urine output, swollen hands,

erythema Erythema (from the Greek , meaning red) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not asso ...

, "massive

blister A blister is a small pocket of body fluid ( lymph, serum, plasma, blood, or pus) within the upper layers of the skin, usually caused by forceful rubbing ( friction), burning, freezing, chemical exposure or infection. Most blisters are filled ...

s on his hands and forearms", intestinal paralysis and

gangrene Gangrene is a type of tissue death caused by a lack of blood supply. Symptoms may include a change in skin color to red or black, numbness, swelling, pain, skin breakdown, and coolness. The feet and hands are most commonly affected. If the gan ...

. He had internal

radiation burns A radiation burn is a damage to the skin or other biological tissue and organs as an effect of radiation. The radiation types of greatest concern are thermal radiation, radio frequency energy, ultraviolet light and ionizing radiation. The mos ...

throughout his body, which one medical expert described as a "three-dimensional sunburn." By the seventh day, he was experiencing periods of "mental confusion." His lips turned blue and he was put in an oxygen tent. He ultimately experienced "a total disintegration of bodily functions" and slipped into a

coma A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...

. Slotin died at 11 a.m. on 30 May, in the presence of his parents. He was buried in the Shaarey Zedek Cemetery in Winnipeg on 2 June 1946.

Other injuries and death

Graves, Kline and Young remained hospitalized after Slotin's death. Graves, who was standing the closest to Slotin, also developed acute radiation sickness and was hospitalized for several weeks. He survived, although he lived with chronic neurological and vision problems. Young also suffered from acute radiation syndrome, but recovered. By 28 January 1948 Graves, Kline and Perlman sought compensation for damages suffered during the incident. Graves settled his claim for $3,500. Three of the observers eventually died of conditions that are known to be promoted by radiation: Graves of a

heart attack A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which ma ...

twenty years later at age 55; Cieslicki of

acute myeloid leukemia Acute myeloid leukemia (AML) is a cancer of the myeloid line of blood cells, characterized by the rapid growth of abnormal cells that build up in the bone marrow and blood and interfere with normal blood cell production. Symptoms may inclu ...

nineteen years later at age 42; and Young of

aplastic anemia Aplastic anemia is a cancer in which the body fails to make blood cells in sufficient numbers. Blood cells are produced in the bone marrow by stem cells that reside there. Aplastic anemia causes a deficiency of all blood cell types: red bloo ...

and bacterial infection of the heart lining twenty-nine years later at age 83. Some of the deaths may have been a consequence of the incident. However, it is not possible to establish a causal relation between the incident and the specifics of the death from such a small sample.

Disposal of core

The core involved was intended to be used in the Able detonation, during the

Crossroads Crossroads, crossroad, cross road or similar may refer to: * Crossroads (junction), where four roads meet Film and television Films * ''Crossroads'' (1928 film), a 1928 Japanese film by Teinosuke Kinugasa * ''Cross Roads'' (film), a 1930 Brit ...

series of nuclear weapons testing. Slotin's experiment was said to be the last conducted before the core's detonation and was intended to be the final demonstration of its ability to go critical. After the accident it needed time to cool. It was therefore rescheduled for the third test of the series, provisionally named ''Charlie'', but this was cancelled due to the unexpected level of radioactivity after the underwater ''Baker'' test and the inability to decontaminate the target warships. The core was eventually melted down and reused in a later core.

Radiation dosage

The radiation doses received in these two accidents are not known with any accuracy. A large part of the dose was due to neutron radiation, which could not be measured by dosimetry equipment of the day. The available film badges were not worn by personnel during the accident, and badges that were supposed to be planted under tables in case of disasters like these were not found. Disaster badges hung on the walls provided some useful data about gamma radiation. A "tentative" estimate of the doses involved was made in 1948, based on dozens of assumptions, some of which are now known to be incorrect. In the absence of personal dosimetry badges, the study authors relied on measurements of

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...

activation in the victims' blood and urine samples as their primary source of data. This activation would have been caused by neutron radiation, but they converted all doses to

equivalent dose Equivalent dose is a dose quantity '' H '' representing the stochastic health effects of low levels of ionizing radiation on the human body which represents the probability of radiation-induced cancer and genetic damage. It is derived from the p ...

s of gamma or X-ray radiation. They concluded that Daghlian and Slotin had probably received doses equivalent to 290 and 880

rem Rem or REM may refer to: Music * R.E.M., an American rock band * ''R.E.M.'' (EP), by Green * "R.E.M." (song), by Ariana Grande Organizations * La République En Marche!, a French centrist political party * Reichserziehungsministerium, in Nazi ...

, respectively, of gamma rays. Minimum and maximum estimates varied from about 50% to 200% of these values. The authors also calculated doses equivalent to a mix of soft 80 keV X-rays and gamma rays, which they believed gave a more realistic picture of the exposure than the gamma equivalent. In this model, the equivalent X-ray doses were much higher, but would be concentrated in the tissues facing the source, whereas the gamma component penetrated the whole body. Slotin's equivalent dose was estimated to be 1930 R (roentgen) of X-ray with 114 R of gamma, while Daghlian's equivalent dose was estimated to be 480 R of X-ray with 110 R of gamma. Five hundred

roentgen equivalent man The roentgen equivalent man (rem) is a CGS unit of equivalent dose, effective dose, and committed dose, which are dose measures used to estimate potential health effects of low levels of ionizing radiation on the human body. Quantities measu ...

(rem) is usually a fatal exposure for humans. In modern times dosimetry is done very differently. Equivalent doses would not be reported in roentgen; they would be calculated with different weighting factors, and they are not considered as relevant to acute radiation syndrome as

absorbed dose Absorbed dose is a dose quantity which is the measure of the energy deposited in matter by ionizing radiation per unit mass. Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protection (reduction of har ...

s. Recent documents have made various interpretations of Slotin's dose, ranging from to . Based on citations and supporting reasoning, the most reliable estimate may be a 1978 Los Alamos memo which suggested 10 Gy(n) + 1.14 Gy(γ) for Slotin and 2 Gy(n) + 1.1 Gy(γ) for Daghlian. These doses are consistent with the symptoms they experienced.

Legacy

After the accident, Los Alamos ended all hands-on critical assembly work. Subsequent criticality testing of fissile cores was done with remotely controlled machines, such as the "

Godiva Lady Godiva (; died between 1066 and 1086), in Old English , was a late Anglo-Saxon noblewoman who is relatively well documented as the wife of Leofric, Earl of Mercia, and a patron of various churches and monasteries. Today, she is mainly reme ...

" series, with the operator located a safe distance away to prevent harm in case of accidents. On 14 June 1946, the associate editor of the ''Los Alamos Times'', Thomas P. Ashlock, penned a poem entitled "Slotin – A Tribute": The official story released at the time was that Slotin, by quickly removing the upper hemisphere, was a hero for ending the reaction and protecting seven other observers in the room: "Dr. Slotin's quick reaction at the immediate risk of his own life prevented a more serious development of the experiment which would certainly have resulted in the death of the seven men working with him, as well as serious injury to others in the general vicinity." This interpretation of events was endorsed at the time by Graves, who stood closest to Slotin when the accident occurred. Graves, like Slotin, had previously displayed a low concern for nuclear safety and later alleged that

fallout Nuclear fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly refers to the radioac ...

risks were "concocted in the minds of weak malingerers." Schreiber, another witness to the accident, spoke out publicly decades later, arguing that Slotin was using improper and unsafe procedures, endangering the others in the lab along with himself. Robert B. Brode had reported hearsay to that effect back in 1946. Slotin's accident is echoed in the 1947 film '' The Beginning or the End'', in which a scientist assembling the bomb destined for Hiroshima dies after coming into contact with radioactive material. It was recounted in Dexter Masters' 1955 novel ''The Accident'', a fictional account of the last few days of the life of a nuclear scientist suffering from radiation poisoning. Depictions of the criticality incident include the 1989 film '' Fat Man and Little Boy'', in which John Cusack plays a fictional character named Michael Merriman based on Slotin, and the ''Louis Slotin Sonata'', a 2001 off-Broadway play directed by David P. Moore. In 1948, Slotin's colleagues at Los Alamos and the University of Chicago initiated the ''Louis A. Slotin Memorial Fund'' for lectures on physics given by distinguished scientists such as Robert Oppenheimer, Luis Walter Alvarez,

Hans Bethe Hans Albrecht Bethe (; July 2, 1906 – March 6, 2005) was a German-American theoretical physicist who made major contributions to nuclear physics, astrophysics, quantum electrodynamics, and solid-state physics, and who won the 1967 Nobel ...

. The memorial fund lasted until 1962. In 2002, an

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

discovered in 1995 was named 12423 Slotin in his honour.

Dollar unit of reactivity

According to Weinberg and Wigner, Slotin was the first to propose the name

dollar Dollar is the name of more than 20 currencies. They include the Australian dollar, Brunei dollar, Canadian dollar, Hong Kong dollar, Jamaican dollar, Liberian dollar, Namibian dollar, New Taiwan dollar, New Zealand dollar, Singapore dollar, ...

for the interval of reactivity between delayed and

ity; 0 is the point of self-sustaining chain reaction, a dollar is the point at which slowly released, delayed neutrons are no longer required to support chain reaction, and enters the domain called "prompt critical". Stable nuclear reactors operate between 0 and a dollar; excursions and nuclear explosives operate above a dollar. The hundredth part of a dollar is called a

cent Cent may refer to: Currency * Cent (currency), a one-hundredth subdivision of several units of currency * Penny (Canadian coin), a Canadian coin removed from circulation in 2013 * 1 cent (Dutch coin), a Dutch coin minted between 1941 and 1944 * ...

. When speaking of purely prompt critical events, some users refer to cents "over critical" as a relative unit.

Notes

References

External links

Louis P. Slotin
– The Manhattan Project Heritage Preservation Association
Louis Slotin, profile
– GCS Research Society

– Canadian Nuclear Society *
Guide to the Louis Slotin Memorial Fund Records 1946–1962
at th
University of Chicago Special Collections Research Center
{{DEFAULTSORT:Slotin, Louis 1910 births 1946 deaths Accidental deaths in New Mexico Alumni of King's College London Jewish Canadian scientists Canadian nuclear physicists Canadian people of Russian-Jewish descent Deaths from laboratory accidents Jewish physicists Manhattan Project people People from Los Alamos, New Mexico People from Winnipeg University of Chicago staff University of Manitoba alumni Victims of radiological poisoning Canadian physical chemists Inventors killed by their own invention North End, Winnipeg Scientists from Manitoba