Louis Slotin
Encyclopedia
Louis Alexander Slotin was a Canadian physicist
and chemist
who took part in the Manhattan Project
, the secret US program during World War II
that developed the atomic bomb.
As part of the Manhattan Project, Slotin performed experiments with uranium
and plutonium
cores to determine their critical mass
values. After World War II, Slotin continued his research at Los Alamos National Laboratory
. On May 21, 1946, Slotin accidentally began a fission reaction, which released a burst of hard radiation
. He was rushed to a hospital, and died of radiation sickness
nine days later on May 30, the second victim of a criticality accident
in history.
Slotin was hailed as a hero by the United States government for reacting quickly enough to prevent the deaths of his colleagues due to the accident he caused. The accident and its aftermath have been dramatized in fictional accounts.
-speaking refugees who had fled the pogrom
s of Russia
to Winnipeg
, Manitoba
. He grew up in the North End neighborhood of Winnipeg, an area with a large concentration of Eastern Europe
an 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 the age of 16, Slotin entered the University of Manitoba
, to pursue a degree in science. During his undergraduate years, he received a University Gold Medal in both physics and chemistry. Slotin received a Bachelor of Science
degree in geology
from the university in 1932 and a Master of Science
degree in 1933. With the assistance of one of his mentors, he obtained a fellowship to study at King's College London
, under the supervision of Arthur John Allmand, the chair of the chemistry department, who specialized in the field of applied electrochemistry
and photochemistry
.
by winning the college's amateur bantamweight boxing championship. Later, he gave the impression that he had fought for the Spanish Republic
and flown experimental fighter jets with the Royal Air Force
. Author Robert Jungk
recounts in his book Brighter than a Thousand Suns: A Personal History of the Atomic Scientists, the first published account of the Manhattan Project
, that Slotin "had volunteered for service in the Spanish Civil War, more for the sake of the thrill of it than on political grounds." 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 doctorate
in physical chemistry
from the university 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's Great Southern Railways
, testing the Drumm nickel-zinc rechargeable batteries
used on the Dublin-Bray line.
, the University of Chicago
accepted him as a research associate. There, Slotin gained his first experience with nuclear chemistry, helping to build the first cyclotron
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
and carbon-11) from the cyclotron. While working together, the two men also used carbon-11 to demonstrate that animal cells had the capacity to use carbon dioxide
for carbohydrate synthesis
, through carbon fixation
.
Slotin may have been present at the start-up of Enrico Fermi
's "Chicago Pile-1
", the first nuclear reactor
, on December 2, 1942; however, the accounts of the event do not agree on this point. During this time, Slotin also contributed to a number of papers in the field of radiobiology
. 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
, the United States' effort to develop a nuclear bomb. Slotin worked on the production of plutonium under future Nobel laureate Eugene Wigner at the university and later at the Oak Ridge National Laboratory
in Oak Ridge
, Tennessee
. He moved to the Los Alamos National Laboratory
in New Mexico
in December 1944 to work in the bomb physics group of Robert Bacher
.
testing, first with uranium
in Otto Robert Frisch's
experiments, and later with plutonium cores. Criticality testing involved bringing masses of fissile
materials to near-critical levels in order to establish their critical mass
values. Scientists referred to this flirting with the possibility of a nuclear chain reaction
as "tickling the dragon's tail," based on a remark by physicist Richard Feynman
who compared the experiments to "tickling the tail of a sleeping dragon". On July 16, 1945, Slotin assembled the core for Trinity
, the first detonated atomic device. He became known as the "chief armourer of the United States" for his expertise in assembling nuclear weapons.
On August 21, 1945, Harry K. Daghlian
, one of Slotin's close colleagues and a laboratory assistant, was performing a critical mass experiment when he accidentally dropped a heavy tungsten carbide
brick onto a 6.2 kg delta phase plutonium
bomb core. The 24-year old Daghlian was irradiated with 510 rems
(5.1 Sv
) of neutron radiation
. As the young man spent the next 25 days in the hospital, slowly succumbing to radiation poisoning
, Slotin spent many hours with him.
After the war, Slotin expressed growing disdain for his personal involvement in the project. He remarked, "I have become involved in the Navy 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 his research into biophysics
and radiobiology at the University of Chicago and was training a replacement, Alvin C. Graves
, to take over his work once he resumed his peacetime job.
On May 21, 1946, with seven other 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
(a neutron reflector
) around a plutonium core. The experiment used the same 6.2 kilograms (13.7 lb) plutonium core that had irradiated Harry K. Daghlian, Jr.
, later called the "Demon core
" for its role in the two accidents. Slotin grasped the upper 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
" 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". In addition, Slotin experienced a sour taste in his mouth and an intense burning sensation in his left hand. Slotin instinctively jerked his left hand upward, lifting the upper beryllium hemisphere and dropping it to the floor, ending the reaction. However, he had already been exposed to a lethal dose (around 2100 rems, or 21 Sv) of neutron
and gamma radiation. Slotin's radiation dose was about four times the lethal dose, equivalent to the amount that he would have been exposed to by being 1500 m (4800 ft) away from the detonation of an atomic bomb.
As soon as Slotin left the building, he vomited
, a common reaction from exposure to extremely intense ionizing radiation
. Slotin's colleagues rushed him to the hospital, but irreversible damage had already been done. His parents were informed of their son's inevitable death and a number of volunteers donated blood for transfusions
, but the efforts proved futile. Louis Slotin died nine days later on May 30, in the presence of his parents. He was buried in Winnipeg on June 2, 1946.
At first, the incident was classified and not made known even within the laboratory; Robert Oppenheimer
and other colleagues later reported severe emotional distress
at having to carry on with normal work and social activities while they secretly knew that their colleague lay dying.
The core involved was subject to a number of experiments shortly after the end of the war and was used in the ABLE detonation, during the Crossroads
series of nuclear weapon testing. Slotin's experiment was set to be the last conducted before the core's detonation and was intended to be the final demonstration of its ability to go critical.
The accident ended all hands-on critical assembly work at Los Alamos. Future criticality testing of fissile cores was done with special remotely controlled machines, such as the "Godiva
" series, with the operator located a safe distance away in case of accidents.
ity. The hundredth part of a dollar is called a “cent”.
On June 14, 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 critical 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." However, Robert B. Brode, a top physicist who worked on the project, argued that the accident was avoidable and that Slotin was not using proper procedures, endangering the others in the lab along with himself. 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 and Nobel laureates Luis Walter Alvarez and Hans Bethe
. The memorial fund lasted until 1962.
The incident 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
. Joseph Kanon's 1997 novel Los Alamos—which includes many historical personages such as Robert Oppenheimer, General Leslie Groves and Edward Teller—includes a fictional character Friedrich Eisler, who dies in an accident similar to Slotin's (however, this fatal incident also occurs prior to the Trinity test in 1945, suggesting it was a depiction of a similar incident that killed physicist Harry Daghlian and in the novel is a deliberate effort by Eisler to become a human guinea pig in studying the effects of radiation). Slotin also appears as a character in the 1987 TV mini-series Race for the Bomb
. Author Paul Mullin wrote the play Louis Slotin Sonata, a dramatic recreation of the events that unfolded on May 21, 1946. The incident is also mentioned in the 1972 novel The Jesus Factor
by Edwin Corley
. In 1947 an MGM film, The Beginning or the End
, depicted a similar 'criticality' accident.
In 2002, an asteroid
discovered in 1995 was named 12423 Slotin
in his honor. The incident was included in the 1989 film Fat Man and Little Boy
, a dramatization of the Manhattan Project starring Paul Newman. John Cusack plays a fictional character named Michael Merriman who recreates Slotin's criticality accident at the same time the first atomic bomb is being tested. Scenes of Merriman dying of radiation sickness are intercut with scenes of the bomb test as a dramatic technique to show the horrible consequences associated with nuclear bombs.
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
and chemist
Chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...
who took part in the Manhattan Project
Manhattan Project
The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...
, the secret US program during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
that developed the atomic bomb.
As part of the Manhattan Project, Slotin performed experiments with uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
and plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
cores to determine their critical mass
Critical mass
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 A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The...
values. After World War II, Slotin continued his research at Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
. On May 21, 1946, Slotin accidentally began a fission reaction, which released a burst of hard radiation
Hard radiation
Hard radiation is a term used to describe high-energy electromagnetic radiation, typically high energy X-rays or gamma rays. The term refers to the ability of the rays to penetrate a given thickness of material, typically a lead shield....
. He was rushed to a hospital, and died of radiation sickness
Radiation Sickness
Radiation Sickness is a VHS by the thrash metal band Nuclear Assault. The video is a recording of a concert at the Hammersmith Odeon, London in 1988. It was released in 1991...
nine days later on May 30, the second victim of a criticality accident
Criticality accident
A criticality accident, sometimes referred to as an excursion or a power excursion, is an accidental increase of nuclear chain reactions in a fissile material, such as enriched uranium or plutonium...
in history.
Slotin was hailed as a hero by the United States government for reacting quickly enough to prevent the deaths of his colleagues due to the accident he caused. The accident and its aftermath have been dramatized in fictional accounts.
Early life
Slotin was the first of three children born to Israel and Sonia Slotin, YiddishYiddish language
Yiddish is a High German language of Ashkenazi Jewish origin, spoken throughout the world. It developed as a fusion of German dialects with Hebrew, Aramaic, Slavic languages and traces of Romance languages...
-speaking refugees who had fled the pogrom
Pogrom
A pogrom is a form of violent riot, a mob attack directed against a minority group, and characterized by killings and destruction of their homes and properties, businesses, and religious centres...
s of Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
to Winnipeg
Winnipeg
Winnipeg is the capital and largest city of Manitoba, Canada, and is the primary municipality of the Winnipeg Capital Region, with more than half of Manitoba's population. It is located near the longitudinal centre of North America, at the confluence of the Red and Assiniboine Rivers .The name...
, Manitoba
Manitoba
Manitoba is a Canadian prairie province with an area of . The province has over 110,000 lakes and has a largely continental climate because of its flat topography. Agriculture, mostly concentrated in the fertile southern and western parts of the province, is vital to the province's economy; other...
. He grew up in the North End neighborhood of Winnipeg, an area with a large concentration of Eastern Europe
Eastern Europe
Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...
an immigrants. From his early days at Machray Elementary School through his teenage years at St. John's High School
St. John's High School (Winnipeg)
St. John's High School in Winnipeg, Canada, is part of North City Schools in the Winnipeg School Division. The school was founded in 1899.To celebrate the school's hundredth anniversary in 2009-2010, the 100th Reunion Committee will be leaving a legacy to honour the past, present and future alumni...
, 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 the age of 16, Slotin entered the University of Manitoba
University of Manitoba
The University of Manitoba , in Winnipeg, Manitoba, Canada, is the largest university in the province of Manitoba. It is Manitoba's most comprehensive and only research-intensive post-secondary educational institution. It was founded in 1877, making it Western Canada’s first university. It placed...
, to pursue a degree in science. During his undergraduate years, he received a University Gold Medal in both physics and chemistry. Slotin received a Bachelor of Science
Bachelor of Science
A Bachelor of Science is an undergraduate academic degree awarded for completed courses that generally last three to five years .-Australia:In Australia, the BSc is a 3 year degree, offered from 1st year on...
degree in geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
from the university in 1932 and a Master of Science
Master of Science
A Master of Science is a postgraduate academic master's degree awarded by universities in many countries. The degree is typically studied for in the sciences including the social sciences.-Brazil, Argentina and Uruguay:...
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
King's College London is a public research university located in London, United Kingdom and a constituent college of the federal University of London. King's has a claim to being the third oldest university in England, having been founded by King George IV and the Duke of Wellington in 1829, and...
, under the supervision of Arthur John Allmand, the chair of the chemistry department, who specialized in the field of applied electrochemistry
Electrochemistry
Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor and an ionic conductor , and which involve electron transfer between the electrode and the electrolyte or species in solution.If a chemical reaction is...
and photochemistry
Photochemistry
Photochemistry, a sub-discipline of chemistry, is the study of chemical reactions that proceed with the absorption of light by atoms or molecules.. Everyday examples include photosynthesis, the degradation of plastics and the formation of vitamin D with sunlight.-Principles:Light is a type of...
.
King's College
While at King's College, Slotin distinguished himself as an amateur boxerAmateur boxing
Amateur boxing is practised at the collegiate level, at the Olympic Games and Commonwealth Games, and in many other venues sponsored by amateur boxing associations. Amateur boxing bouts are short in duration and fighters wear head protection, so this type of competition prizes point-scoring rather...
by winning the college's amateur bantamweight boxing championship. Later, he gave the impression that he had fought for the Spanish Republic
Second Spanish Republic
The Second Spanish Republic was the government of Spain between April 14 1931, and its destruction by a military rebellion, led by General Francisco Franco....
and flown experimental fighter jets with the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
. Author Robert Jungk
Robert Jungk
Robert Jungk , also known as Robert Baum and Robert Baum-Jungk, was an Austrian writer and journalist who wrote mostly on issues relating to nuclear weapons....
recounts in his book Brighter than a Thousand Suns: A Personal History of the Atomic Scientists, the first published account of the Manhattan Project
Manhattan Project
The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...
, that Slotin "had volunteered for service in the Spanish Civil War, more for the sake of the thrill of it than on political grounds." 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 doctorate
Doctorate
A doctorate is an academic degree or professional degree that in most countries refers to a class of degrees which qualify the holder to teach in a specific field, A doctorate is an academic degree or professional degree that in most countries refers to a class of degrees which qualify the holder...
in physical chemistry
Physical chemistry
Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts...
from the university 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's Great Southern Railways
Great Southern Railways
The Great Southern Railways Company was an Irish company that from 1925 until 1945 owned and operated all railways that lay wholly within the Irish Free State .-Formation:...
, testing the Drumm nickel-zinc rechargeable batteries
Nickel-zinc battery
The nickel–zinc battery is a type of rechargeable battery that may be used in cordless power tools, cordless telephones, digital cameras, battery operated lawn and garden tools, professional photography, flashlights, electric bikes, and light electric vehicle sectors.Larger nickel–zinc battery...
used on the Dublin-Bray line.
University of Chicago
In 1937, after he unsuccessfully applied for a job with Canada's National Research CouncilNational Research Council of Canada
The National Research Council is an agency of the Government of Canada which conducts scientific research and development.- History :...
, the University of Chicago
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
accepted him as a research associate. There, Slotin gained his first experience with nuclear chemistry, helping to build the first cyclotron
Cyclotron
In technology, a cyclotron is a type of particle accelerator. In physics, the cyclotron frequency or gyrofrequency is the frequency of a charged particle moving perpendicularly to the direction of a uniform magnetic field, i.e. a magnetic field of constant magnitude and direction...
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
Earl Evans (scientist)
Earl Alison Evans was the chairman of the biochemistry department at the University of Chicago for 30 years, during which time he pioneered several techniques whose use is now widespread....
, the head of the university's biochemistry department, to produce radiocarbon (carbon-14
Carbon-14
Carbon-14, 14C, or radiocarbon, is a radioactive isotope of carbon with a 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 colleagues , to date archaeological, geological, and hydrogeological...
and carbon-11) from the cyclotron. While working together, the two men also used carbon-11 to demonstrate that animal cells had the capacity to use carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
for carbohydrate synthesis
Carbohydrate metabolism
Carbohydrate metabolism denotes the various biochemical processes responsible for the formation, breakdown and interconversion of carbohydrates in living organisms....
, through carbon fixation
Carbon fixation
In biology, carbon fixation is the reduction of carbon dioxide to organic compounds by living organisms. The obvious example is photosynthesis. Carbon fixation requires both a source of energy such as sunlight, and an electron donor such as water. All life depends on fixed carbon. Organisms that...
.
Slotin may have been present at the start-up of Enrico Fermi
Enrico Fermi
Enrico Fermi was an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics...
's "Chicago Pile-1
Chicago Pile-1
Chicago Pile-1 was the world's first man-made nuclear reactor. CP-1 was built on a rackets court, under the abandoned west stands of the original Alonzo Stagg Field stadium, at the University of Chicago. The first self-sustaining nuclear chain reaction was initiated in CP-1 on December 2, 1942...
", the first nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...
, on December 2, 1942; however, the accounts of the event do not agree on this point. During this time, Slotin also contributed to a number of papers in the field of radiobiology
Radiobiology
Radiobiology , as a field of clinical and basic medical sciences, originated from Leopold Freund's 1896 demonstration of the therapeutic treatment of a hairy mole using a new type of electromagnetic radiation called x-rays, which was discovered 1 year previously by the German physicist, Wilhelm...
. 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
Manhattan Project
The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...
, the United States' effort to develop a nuclear bomb. Slotin worked on the production of plutonium under future Nobel laureate Eugene Wigner at the university and later at the Oak Ridge National Laboratory
Oak Ridge National Laboratory
Oak Ridge National Laboratory is a multiprogram science and technology national laboratory managed for the United States Department of Energy by UT-Battelle. ORNL is the DOE's largest science and energy laboratory. ORNL is located in Oak Ridge, Tennessee, near Knoxville...
in Oak Ridge
Oak Ridge, Tennessee
Oak Ridge is a city in Anderson and Roane counties in the eastern part of the U.S. state of Tennessee, about west of Knoxville. Oak Ridge's population was 27,387 at the 2000 census...
, Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
. He moved to the Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
in New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
in December 1944 to work in the bomb physics group of Robert Bacher
Robert Bacher
Robert Fox Bacher was an American nuclear physicist and one of the leaders of the Manhattan Project.-Early life and career:...
.
Los Alamos
At Los Alamos, Slotin's duties consisted of dangerous criticalityCritical mass
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 A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The...
testing, first with uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
in Otto Robert Frisch's
Otto Robert Frisch
Otto Robert Frisch , Austrian-British physicist. With his collaborator Rudolf Peierls he designed the first theoretical mechanism for the detonation of an atomic bomb in 1940.- Overview :...
experiments, and later with plutonium cores. Criticality testing involved bringing masses of fissile
Fissile
In nuclear engineering, a fissile material is one that is capable of sustaining a chain reaction of nuclear fission. By definition, fissile materials can sustain a chain reaction with neutrons of any energy. The predominant neutron energy may be typified by either slow neutrons or fast neutrons...
materials to near-critical levels in order to establish their critical mass
Critical mass
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 A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The...
values. Scientists referred to this flirting with the possibility of a nuclear chain reaction
Nuclear chain reaction
A nuclear chain reaction occurs when one nuclear reaction causes an average of one or more nuclear reactions, thus leading to a self-propagating number of these reactions. The specific nuclear reaction may be the fission of heavy isotopes or the fusion of light isotopes...
as "tickling the dragon's tail," based on a remark by physicist Richard Feynman
Richard Feynman
Richard Phillips Feynman was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics...
who compared the experiments to "tickling the tail of a sleeping dragon". On July 16, 1945, Slotin assembled the core for Trinity
Trinity test
Trinity was the code name of the first test of a nuclear weapon. This test was conducted by the United States Army on July 16, 1945, in the Jornada del Muerto desert about 35 miles southeast of Socorro, New Mexico, at the new White Sands Proving Ground, which incorporated the Alamogordo Bombing...
, the first detonated atomic device. He became known as the "chief armourer of the United States" for his expertise in assembling nuclear weapons.
On August 21, 1945, Harry K. Daghlian
Harry K. Daghlian, Jr.
Haroutune Krikor Daghlian, Jr. was an Armenian-American physicist with the Manhattan Project who accidentally irradiated himself on August 21, 1945, during a critical mass experiment at the remote Omega Site facility at Los Alamos National Laboratory in New Mexico, resulting in his death 25 days...
, one of Slotin's close colleagues and a laboratory assistant, was performing a critical mass experiment when he accidentally dropped a heavy tungsten carbide
Tungsten carbide
Tungsten carbide is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...
brick onto a 6.2 kg delta phase plutonium
Plutonium-gallium alloy
Plutonium-gallium alloy is an alloy of plutonium and gallium, used in nuclear weapon pits – the component of a nuclear weapon where the fission chain reaction is started....
bomb core. The 24-year old Daghlian was irradiated with 510 rems
Röntgen equivalent man
Named after Wilhelm Röntgen , the roentgen equivalent in man or rem is a unit of radiation dose equivalent...
(5.1 Sv
Sievert
The sievert is the International System of Units SI derived unit of dose equivalent radiation. It attempts to quantitatively evaluate the biological effects of ionizing radiation as opposed to just the absorbed dose of radiation energy, which is measured in gray...
) of neutron radiation
Neutron radiation
Neutron radiation is a kind of ionizing radiation which consists of free neutrons. A result of nuclear fission or nuclear fusion, it consists of the release of free neutrons from atoms, and these free neutrons react with nuclei of other atoms to form new isotopes, which, in turn, may produce...
. As the young man spent the next 25 days in the hospital, slowly succumbing to radiation poisoning
Radiation poisoning
Acute radiation syndrome also known as radiation poisoning, radiation sickness or radiation toxicity, is a constellation of health effects which occur within several months of exposure to high amounts of ionizing radiation...
, Slotin spent many hours with him.
After the war, Slotin expressed growing disdain for his personal involvement in the project. He remarked, "I have become involved in the Navy 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 his research into biophysics
Biophysics
Biophysics is an interdisciplinary science that uses the methods of physical science to study biological systems. Studies included under the branches of biophysics span all levels of biological organization, from the molecular scale to whole organisms and ecosystems...
and radiobiology at the University of Chicago and was training a replacement, Alvin C. Graves
Alvin C. Graves
Alvin C. Graves was an atomic physicist and director of U.S. nuclear weapons testing for many years.Graves was born in 1909 in Washington, DC, the youngest of six children. He graduated at the top of his class from the University of Virginia in 1931 with a bachelors degree in electrical...
, to take over his work once he resumed his peacetime job.
The criticality accident
Beryllium
Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...
(a neutron reflector
Neutron reflector
A neutron reflector is any material that reflects neutrons. This refers to elastic scattering rather than to a specular reflection. The material may be graphite, beryllium, steel, and tungsten carbide, or other materials...
) around a plutonium core. The experiment used the same 6.2 kilograms (13.7 lb) plutonium core that had irradiated Harry K. Daghlian, Jr.
Harry K. Daghlian, Jr.
Haroutune Krikor Daghlian, Jr. was an Armenian-American physicist with the Manhattan Project who accidentally irradiated himself on August 21, 1945, during a critical mass experiment at the remote Omega Site facility at Los Alamos National Laboratory in New Mexico, resulting in his death 25 days...
, later called the "Demon core
Demon core
The Demon core was the nickname given to a subcritical mass of plutonium that accidentally went briefly critical in two separate accidents at the Los Alamos laboratory in 1945 and 1946. Each incident resulted in the acute radiation poisoning and subsequent death of a scientist...
" for its role in the two accidents. Slotin grasped the upper 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
Prompt critical
In nuclear engineering, an assembly is prompt critical if for each nuclear fission event, one or more of the immediate or prompt neutrons released causes an additional fission event. This causes a rapid, exponential increase in the number of fission events...
" reaction and a burst of hard radiation
Hard radiation
Hard radiation is a term used to describe high-energy electromagnetic radiation, typically high energy X-rays or gamma rays. The term refers to the ability of the rays to penetrate a given thickness of material, typically a lead shield....
. At the time, the scientists in the room observed the "blue glow" of air ionization
Ionized air glow
The ionized-air glow is the emission of characteristic blue–purple–violet light, of color called electric blue, by air subjected to an energy flux. -Processes:...
and felt a "heat wave". In addition, Slotin experienced a sour taste in his mouth and an intense burning sensation in his left hand. Slotin instinctively jerked his left hand upward, lifting the upper beryllium hemisphere and dropping it to the floor, ending the reaction. However, he had already been exposed to a lethal dose (around 2100 rems, or 21 Sv) of neutron
Neutron radiation
Neutron radiation is a kind of ionizing radiation which consists of free neutrons. A result of nuclear fission or nuclear fusion, it consists of the release of free neutrons from atoms, and these free neutrons react with nuclei of other atoms to form new isotopes, which, in turn, may produce...
and gamma radiation. Slotin's radiation dose was about four times the lethal dose, equivalent to the amount that he would have been exposed to by being 1500 m (4800 ft) away from the detonation of an atomic bomb.
As soon as Slotin left the building, he vomited
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
, a common reaction from exposure to extremely intense ionizing radiation
Ionizing radiation
Ionizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...
. Slotin's colleagues rushed him to the hospital, but irreversible damage had already been done. His parents were informed of their son's inevitable death and a number of volunteers donated blood for transfusions
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...
, but the efforts proved futile. Louis Slotin died nine days later on May 30, in the presence of his parents. He was buried in Winnipeg on June 2, 1946.
At first, the incident was classified and not made known even within the laboratory; Robert Oppenheimer
Robert Oppenheimer
Julius Robert Oppenheimer was an American theoretical physicist and professor of physics at the University of California, Berkeley. Along with Enrico Fermi, he is often called the "father of the atomic bomb" for his role in the Manhattan Project, the World War II project that developed the first...
and other colleagues later reported severe emotional distress
Stress (medicine)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
at having to carry on with normal work and social activities while they secretly knew that their colleague lay dying.
The core involved was subject to a number of experiments shortly after the end of the war and was used in the ABLE detonation, during the Crossroads
Operation Crossroads
Operation Crossroads was a series of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. It was the first test of a nuclear weapon after the Trinity nuclear test in July 1945...
series of nuclear weapon testing. Slotin's experiment was set to be the last conducted before the core's detonation and was intended to be the final demonstration of its ability to go critical.
The accident ended all hands-on critical assembly work at Los Alamos. Future criticality testing of fissile cores was done with special remotely controlled machines, such as the "Godiva
Godiva device
The Lady Godiva device was an unshielded, pulsed nuclear reactor originally situated at the Los Alamos National Laboratory , New Mexico, U.S. It was one of a number of criticality devices within Technical Area 18 . Specifically, it was used to produce bursts of neutrons and gamma rays for...
" series, with the operator located a safe distance away in case of accidents.
The Dollar unit of reactivity
According to Weinberg and Wigner, Slotin was the first to propose the name “dollar” for the interval of reactivity between delayed and prompt criticalPrompt critical
In nuclear engineering, an assembly is prompt critical if for each nuclear fission event, one or more of the immediate or prompt neutrons released causes an additional fission event. This causes a rapid, exponential increase in the number of fission events...
ity. The hundredth part of a dollar is called a “cent”.
Legacy
May God receive you, great-souled scientist!
While you were with us, even strangers knew
The breadth and lofty stature of your mind
Twas only in the crucible of death
We saw at last your noble heart revealed.
The official story released at the time was that Slotin, by quickly removing the upper hemisphere, was a hero for ending the critical 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." However, Robert B. Brode, a top physicist who worked on the project, argued that the accident was avoidable and that Slotin was not using proper procedures, endangering the others in the lab along with himself. 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 and Nobel laureates Luis Walter Alvarez and Hans Bethe
Hans Bethe
Hans Albrecht Bethe was a German-American nuclear physicist, and Nobel laureate in physics for his work on the theory of stellar nucleosynthesis. A versatile theoretical physicist, Bethe also made important contributions to quantum electrodynamics, nuclear physics, solid-state physics and...
. The memorial fund lasted until 1962.
The incident was recounted in Dexter Masters
Dexter Masters
Dexter Wright Masters , was an American editor and novelist who wrote extensively about the dangers of the atomic bomb.-Early life:...
' 1955 novel The Accident, a fictional account of the last few days of the life of a nuclear scientist suffering from radiation poisoning
Radiation poisoning
Acute radiation syndrome also known as radiation poisoning, radiation sickness or radiation toxicity, is a constellation of health effects which occur within several months of exposure to high amounts of ionizing radiation...
. Joseph Kanon's 1997 novel Los Alamos—which includes many historical personages such as Robert Oppenheimer, General Leslie Groves and Edward Teller—includes a fictional character Friedrich Eisler, who dies in an accident similar to Slotin's (however, this fatal incident also occurs prior to the Trinity test in 1945, suggesting it was a depiction of a similar incident that killed physicist Harry Daghlian and in the novel is a deliberate effort by Eisler to become a human guinea pig in studying the effects of radiation). Slotin also appears as a character in the 1987 TV mini-series Race for the Bomb
Race for the Bomb
Dramatized documentary about the Manhattan Project, starting from the initial stages of scientific discovery that led to the creation of the atomic bomb, and ending with the beginning of the arms race....
. Author Paul Mullin wrote the play Louis Slotin Sonata, a dramatic recreation of the events that unfolded on May 21, 1946. The incident is also mentioned in the 1972 novel The Jesus Factor
The Jesus Factor (novel)
The Jesus Factor is a 1970 conspiracy theory thriller novel by Edwin Corley based on the Manhattan Project of World War 2 and the bombing of Hiroshima and Nagasaki...
by Edwin Corley
Edwin Corley
Edwin Raymond Corley was a United States novelist most famous for his thrillers Sargasso and Air Force One. He used the pseudonyms "David Harper", "William Judson" and worked with novelist Jack Murphy, using the pseudonym "Patrick Buchanan" .As "Patrick Buchanan", Corley and Murphy wrote a series of...
. In 1947 an MGM film, The Beginning or the End
The Beginning or the End
The Beginning or the End is a 1947 film about the development of the atomic bomb in World War II.It was directed by Norman Taurog and starred Brian Donlevy and Hume Cronyn...
, depicted a similar 'criticality' accident.
In 2002, an asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
discovered in 1995 was named 12423 Slotin
12423 Slotin
12423 Slotin is a main belt asteroid, discovered on October 17, 1995 by Spacewatch. It is named after Louis Slotin, a Canadian-American physicist who died of radiation poisoning after a criticality accident in 1946....
in his honor. The incident was included in the 1989 film Fat Man and Little Boy
Fat Man and Little Boy
Fat Man and Little Boy is a 1989 film that reenacts the Manhattan Project, the secret Allied endeavor to develop the first nuclear weapons during World War II. The film is named after the nuclear weapons known by the code names "Fat Man" and "Little Boy". The code names can be taken for joking...
, a dramatization of the Manhattan Project starring Paul Newman. John Cusack plays a fictional character named Michael Merriman who recreates Slotin's criticality accident at the same time the first atomic bomb is being tested. Scenes of Merriman dying of radiation sickness are intercut with scenes of the bomb test as a dramatic technique to show the horrible consequences associated with nuclear bombs.
External links
- Louis P. Slotin - The Manhattan Project Heritage Preservation Association
- Louis Slotin, profile - GCS Research Society
- The Secret Life of Louis Slotin - Canadian Nuclear Society