Los Alamos Primer
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''The Los Alamos Primer'' is a printed version of the first five lectures on the principles of
nuclear weapon A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear exp ...
s given to new arrivals at the top-secret
Los Alamos laboratory The Los Alamos Laboratory, also known as Project Y, was a secret scientific laboratory established by the Manhattan Project and overseen by the University of California during World War II. It was operated in partnership with the United State ...
during the
Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...
. The five lectures were given by physicist
Robert Serber Robert Serber (March 14, 1909 – June 1, 1997) was an American physicist who participated in the Manhattan Project. Serber's lectures explaining the basic principles and goals of the project were printed and supplied to all incoming scientific st ...
in April 1943. The notes from the lectures which became the ''Primer'' were written by
Edward Condon Edward Uhler Condon (March 2, 1902 – March 26, 1974) was an American nuclear physicist, a pioneer in quantum mechanics, and a participant during World War II in the development of radar and, very briefly, of nuclear weapons as part of the Ma ...
.


History

''The Los Alamos Primer'' was composed from five lectures given by the physicist
Robert Serber Robert Serber (March 14, 1909 – June 1, 1997) was an American physicist who participated in the Manhattan Project. Serber's lectures explaining the basic principles and goals of the project were printed and supplied to all incoming scientific st ...
to the newcomers at the
Los Alamos Laboratory The Los Alamos Laboratory, also known as Project Y, was a secret scientific laboratory established by the Manhattan Project and overseen by the University of California during World War II. It was operated in partnership with the United State ...
in April 1943, at the start of the
Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...
. The aim of the project was to build the first
nuclear bomb A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear exp ...
, and these lectures were a very concise introduction into the principles of nuclear weapon design. Serber was a postdoctoral student of
J. Robert Oppenheimer J. Robert Oppenheimer (born Julius Robert Oppenheimer ; April 22, 1904 – February 18, 1967) was an American theoretical physics, theoretical physicist who served as the director of the Manhattan Project's Los Alamos Laboratory during World ...
, the leader of the Los Alamos Laboratory, and worked with him on the project from the very start. The five lectures were conducted at April 5, 7, 9, 12, and 14, 1943; according to Serber, between 30 and 50 people attended them. Notes were taken by
Edward Condon Edward Uhler Condon (March 2, 1902 – March 26, 1974) was an American nuclear physicist, a pioneer in quantum mechanics, and a participant during World War II in the development of radar and, very briefly, of nuclear weapons as part of the Ma ...
; the ''Primer'' is just 24-pages-long. Only 36 copies were printed at the time. Serber later described the lectures:
Previously the people working at the separate universities had no idea of the whole story. They only knew what part they were working on. So somebody had to give them the picture of what it was all about and what the bomb was like, what was known about the theory, and some idea why they needed the various experimental numbers.
In July 1942, Oppenheimer had held a "conference" at his office at Berkeley. No records were preserved, but the ''Primer'' arose from all the aspects of bomb design discussed there.


Content

The ''Primer'', though only 24 pages long, consists of 22 sections, divided into chapters: # Preliminaries # Neutrons and the fission process # Critical mass and efficiency # Detonation, pre-detonation, and fizzles # Conclusion The first paragraph states the intention of the Los Alamos Laboratory during
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
: :The object of the project is to produce a practical military weapon in the form of a bomb in which the energy is released by a fast neutron chain reaction in one or more of the materials known to show nuclear fission. The ''Primer'' contained the basic physical principles of
nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...
, as they were known at the time, and their implications for
nuclear weapon design Nuclear weapons design are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types: # Pure fission weapons are the simplest, least technically de ...
. It suggested possible ways to assemble a
critical mass In nuclear engineering, critical mass is the minimum mass of the fissile material needed for a sustained nuclear chain reaction in a particular setup. The critical mass of a fissionable material depends upon its nuclear properties (specific ...
of
uranium-235 Uranium-235 ( or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nat ...
or
plutonium Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four ...
, the simplest being the shooting of a "cylindrical plug" into a sphere of "active material" with a "tamper"—dense material which would reflect neutrons inward and keep the reacting mass together to increase its efficiency (this model, the ''Primer'' said, "avoids fancy shapes"). They also explored designs involving
spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface (mathematics), surface obtained by Surface of revolution, rotating an ellipse about one of its principal axes; in other words, an ellipsoid with t ...
s, a primitive form of "implosion" (suggested by
Richard C. Tolman Richard Chace Tolman (March 4, 1881 – September 5, 1948) was an American mathematical physicist and physical chemist who made many contributions to statistical mechanics and theoretical cosmology. He was a professor at the California Ins ...
), and explored the speculative possibility of "autocatalytic methods" which would increase the efficiency of the bomb as it exploded. According to Rhodes,
Serber discussed fission cross sections, the
energy spectrum In the physical sciences, the term ''spectrum'' was introduced first into optics by Isaac Newton in the 17th century, referring to the range of colors observed when white light was dispersed through a prism. Soon the term referred to a plot o ...
of secondary neutrons, the average number of secondary neutrons per fission (measured by then to be about 2.2), the
neutron capture Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, wh ...
process in U238 that led to
plutonium Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four ...
and why ordinary uranium is safe (it would have to be enriched to at least 7 percent U235, the young theoretician pointed out, 'to make an explosive reaction possible'). The calculations Serber reported indicated a
critical mass In nuclear engineering, critical mass is the minimum mass of the fissile material needed for a sustained nuclear chain reaction in a particular setup. The critical mass of a fissionable material depends upon its nuclear properties (specific ...
of metallic U235 tamped with a thick shell of ordinary uranium of 15 kilograms: 33 pounds. For plutonium similarly tamped the critical mass might be 5 kilograms: 11 pounds. Tamper always increased efficiency: it reflected neutrons back into the core and its inertia...slowed the core's expansion and helped keep the core surface from blowing away. So there might be a third basic component to their atomic bomb besides nuclear core and confining tamper: an initiator - a Ra + Be source or, better, a Po + Be source, with the radium or polonium attached perhaps to one piece of the core and the beryllium to the other, to smash together and spray neutrons when the parts mated to start the chain reaction. The immediate work of experiment, Serber concluded, would be measuring the neutron properties of various materials and mastering the ordnance problem - the problem, that is, of assembling a critical mass and firing the bomb.
The ''Primer'' became designated as the first official Los Alamos technical report (LA-1), and though its information about the physics of fission and weapon design was soon rendered obsolete, it is still considered a fundamental historical document in the
history of nuclear weapons Building on major scientific breakthroughs made during the 1930s, the United Kingdom began the world's first nuclear weapons research project, codenamed Tube Alloys, in 1941, during World War II. The United States, in collaboration with the Uni ...
. Its contents would be of little use today to someone attempting to build a nuclear weapon, a fact acknowledged by its complete declassification in 1965. In 1992, an edited version of the ''Primer'' with many annotations and explanations by Serber was published with an introduction by
Richard Rhodes Richard Lee Rhodes (born July 4, 1937) is an American historian, journalist, and author of both fiction and nonfiction, including the Pulitzer Prize-winning '' The Making of the Atomic Bomb'' (1986), and most recently, ''Energy: A Human History ...
, who previously published ''
The Making of the Atomic Bomb ''The Making of the Atomic Bomb'' is a history book written by the American journalist and historian Richard Rhodes, first published by Simon & Schuster in 1987. The book won multiple awards, including the Pulitzer Prize for General Nonfiction. ...
''. The 1992 edition also contains the
Frisch–Peierls memorandum The Frisch–Peierls memorandum was the first technical exposition of a practical nuclear weapon. It was written by expatriate German-Jewish physicists Otto Frisch and Rudolf Peierls in March 1940 while they were both working for Mark Oliphant a ...
, written in 1940 in England.


Reception

The physicist
Freeman Dyson Freeman John Dyson (15 December 1923 – 28 February 2020) was a British-American theoretical physics, theoretical physicist and mathematician known for his works in quantum field theory, astrophysics, random matrix, random matrices, math ...
, who knew Serber, Oppenheimer, and other participants of the Manhattan Project, called the ''Primer'' a "legendary document in the literature of nuclear weapons". He praised "Serber's clear thinking", but harshly criticized the ''Primer''s publication, writing "I still wish that it had been allowed to languish in obscurity for another century or two." Acknowledging that it was unclassified in 1965, and that it can't be useful to any bomb designer from 1950, Dyson still thinks that such publication can be dangerous:
There is nothing here that would have been technically useful to a Russian bomb designer in 1950 or to an Iraqi bomb designer in 1990. But the primer contains much more than technical information. It conveys a powerful message that bomb designing is fun. The primer succeeds all too well in recreating the Los Alamos mystique, the picture of this brilliant group of city slickers suddenly dumped into the remotest corner of the Wild West and having the best time of their lives building bombs. It helps to perpetuate the myth. ... This is what I mean by seduction-the myth, unfortunately containing an element of truth, that building bombs is a wild, consciousness-raising adventure.
Dyson compared bomb-building with
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
synthesis: "Nuclear weapons and LSD are both highly addictive. Both have been manufactured extensively by bright young people seduced by a myth and searching for adventure. Both have destroyed many lives and are likely to destroy many more if the myths are not dispelled. ... Books that present either LSD or nuclear bombs as a romantic adventure can be a danger to public health and safety." His article, titled "Dragon's Teeth", reflects another analogy he uses in his criticisms:
We are here confronting an ethical dilemma that is at least 350 years old, the same dilemma that
John Milton John Milton (9 December 1608 – 8 November 1674) was an English poet, polemicist, and civil servant. His 1667 epic poem ''Paradise Lost'' was written in blank verse and included 12 books, written in a time of immense religious flux and politic ...
confronted in his historic battle for the freedom of the press in 17th-century England. Milton in his famous appeal with the title "
Areopagitica ''Areopagitica; A speech of Mr. John Milton for the Liberty of Unlicenc'd Printing, to the Parlament of England'' is a 1644 prose polemic by the English poet, scholar, and polemical author John Milton opposing licensing. ''Areopagitica'' is ...
", addressed to the English parliament in 1644, conceded to his enemies the point that books "are as lively and as vigorously productive as those fabulous dragon's teeth, and being sown up and down, may chance to spring up armed men." He conceded that the risks of letting books go free into the world could be lethal as well as irreversible. He argued that the risks must still be accepted, because the censorship of books was the greater evil. He lost the argument, and in his day the censors prevailed. In our day, the censors have lost their grip, but the ethical dilemma remains. Books have not lost their power to spring up armed men, to seduce and to destroy. The fact that this primer was declassified 26 years ago does not mean that we can spread it over the world without some responsibility for the consequences.
Dyson concludes his review writing: "With luck, this charming little book will be read only by elderly physicists and historians, people who can appreciate its elegance without being seduced by its magic." Other reviews, however, were more favorable. John F. Ahearne writes that the book "remains mathematical", and that it can be useful to young scientists: "the insight to be gained from reading Serber's lucid descriptions of how to analyze complex events by using first approximations. Serber was speaking in many cases to a group of experimentalists who, as one of the experimental group leaders is noted as saying, found "a qualitative argument was more convincing than any amount of fancy theory." A good physicist should be able to get an approximate answer to any complex question using what he or she carries around in the head, the well known "back of the envelope" calculation." Paul W. Henriksen praised the book, writing that "one will be even more impressed with the magnitude of the effort to build an atomic bomb to try to end World War II". He notes that the "annotated version is fascinating in several respects. It is a rare instance in which one of the contributors to a historical event has gone back and explained his work, its importance, and the mistakes that were made at the same time." He also notes that the book is "one of the few books to deal at all with the technical side of the bomb project." Matthew Hersch writes that the book has "power to amaze", and that "The Los Alamos Primer is a work bound to be read differently by different generations ... tis a rich text that peers into a moment of innovation that had global consequences." Frank A. Settle also finds the primer to be unique in style and context, and sees it as "a significant contribution to the technical and scientific history of this important period."


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References


External links

* {{Authority control Manhattan Project Books about the Manhattan Project 1943 non-fiction books Books of lectures History of physics