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136-561: The test device, codenamed Hamlet , was detonated atop a 300-foot (91 m) tower, the device produced a yield of 32 kilotonnes. The device had a diameter of 56 inches (1,400 mm) and a length of 66 inches (1,700 mm). Its weight was 4 short tons (3.6 t). The device was designed by Ted Taylor at the Los Alamos National Laboratory of the United States of America, and is distinguished from all others because it

272-525: A 300-mile radius of the test site, of the period 1951 to 1959, the Upshot–Knothole tests was found to have produced 50% ( rounded figure) of exposure rate within the population. Of the 50%, 75% ( rounded figure) was due to the test-shot Harry . Ted Taylor (physicist) Theodore Brewster "Ted" Taylor (July 11, 1925 – October 28, 2004) was an American theoretical physicist , specifically concerning nuclear energy . His higher education included

408-572: A PhD from Cornell University in theoretical physics. His most noteworthy contributions to the field of nuclear weaponry were his small bomb developments at the Los Alamos Laboratory in New Mexico. Although not widely known to the general public, Taylor is credited with numerous landmarks in fission nuclear weaponry development, including having designed and developed the smallest, most powerful, and most efficient fission weapons ever tested by

544-651: A PhD in Mexican literature from the Universidad Nacional Autónoma de México , and his father, Walter Clyde Taylor, was the director of a YMCA in Mexico City. Before marrying in 1922, his father had been a widower with three sons and his mother a widow with a son of her own. Both of his maternal grandparents were Congregationalist missionaries in Guadalajara . Taylor grew up in a house without electricity in

680-445: A capacity of 398 GWE , with about 85% being light-water cooled reactors such as pressurized water reactors or boiling water reactors . Energy from fission is transmitted through conduction or convection to the nuclear reactor coolant , then to a heat exchanger , and the resultant generated steam is used to drive a turbine or generator. The objective of an atomic bomb is to produce a device, according to Serber, "...in which energy

816-401: A deformed nucleus relative to a spherical form for the surface and Coulomb terms. Additional terms can be included such as symmetry, pairing, the finite range of the nuclear force, and charge distribution within the nuclei to improve the estimate. Normally binding energy is referred to and plotted as average binding energy per nucleon. According to Lilley, "The binding energy of a nucleus B

952-448: A fast neutron. This energy release profile holds for thorium and the various minor actinides as well. When a uranium nucleus fissions into two daughter nuclei fragments, about 0.1 percent of the mass of the uranium nucleus appears as the fission energy of ~200 MeV. For uranium-235 (total mean fission energy 202.79 MeV ), typically ~169 MeV appears as the kinetic energy of the daughter nuclei, which fly apart at about 3% of

1088-480: A fission bomb where growth is at an explosive rate. If k is exactly unity, the reactions proceed at a steady rate and the reactor is said to be critical. It is possible to achieve criticality in a reactor using natural uranium as fuel, provided that the neutrons have been efficiently moderated to thermal energies." Moderators include light water, heavy water , and graphite . According to John C. Lee, "For all nuclear reactors in operation and those under development,

1224-432: A fission reaction is produced by its fission products , though a large majority of it, about 85 percent, is found in fragment kinetic energy , while about 6 percent each comes from initial neutrons and gamma rays and those emitted after beta decay , plus about 3 percent from neutrinos as the product of such decay. Nuclear fission can occur without neutron bombardment as a type of radioactive decay. This type of fission

1360-608: A liberal arts university in Claremont, California , and Taylor would visit her whenever he could. Both Arnim and Taylor were very shy people, and unsure of what the future held. When they first met they both believed that Taylor would end up as a college professor in a sleepy town, and that Caro would be a librarian. After 44 years of marriage the couple divorced in 1992. Taylor died on October 28, 2004, of coronary artery disease. Prior to Taylor's work at Los Alamos, he had firmly declared himself an opponent of nuclear weapons. While at

1496-413: A limitation associated with the energy of his alpha particle source. Eventually, in 1932, a fully artificial nuclear reaction and nuclear transmutation was achieved by Rutherford's colleagues Ernest Walton and John Cockcroft , who used artificially accelerated protons against lithium-7, to split this nucleus into two alpha particles. The feat was popularly known as "splitting the atom", and would win them

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1632-445: A low-atomic-number element like beryllium did not "bounce" neutrons back into the fissile core as efficiently as heavy tungsten, its propensity for neutron spallation (in nuclear physics the so-called "(n,2n)" reaction) more than compensated in overall reflector performance. After these breakthroughs, Taylor became more of an important figure at Los Alamos. He was included in high priority situations reserved for important personnel, and

1768-408: A major gamma ray emitter. All actinides are fertile or fissile and fast breeder reactors can fission them all albeit only in certain configurations. Nuclear reprocessing aims to recover usable material from spent nuclear fuel to both enable uranium (and thorium) supplies to last longer and to reduce the amount of "waste". The industry term for a process that fissions all or nearly all actinides

1904-463: A mass ratio of products of about 3 to 2, for common fissile isotopes . Most fissions are binary fissions (producing two charged fragments), but occasionally (2 to 4 times per 1000 events), three positively charged fragments are produced, in a ternary fission . The smallest of these fragments in ternary processes ranges in size from a proton to an argon nucleus. Apart from fission induced by an exogenous neutron, harnessed and exploited by humans,

2040-459: A natural form of spontaneous radioactive decay (not requiring an exogenous neutron, because the nucleus already has an overabundance of neutrons) is also referred to as fission, and occurs especially in very high-mass-number isotopes. Spontaneous fission was discovered in 1940 by Flyorov , Petrzhak , and Kurchatov in Moscow, in an experiment intended to confirm that, without bombardment by neutrons,

2176-469: A neutron-driven chain reaction using beryllium. Szilard stated, "...if we could find an element which is split by neutrons and which would emit two neutrons when it absorbs one neutron, such an element, if assembled in sufficiently large mass, could sustain a nuclear chain reaction." On 25 January 1939, after learning of Hahn's discovery from Eugene Wigner , Szilard noted, "...if enough neutrons are emitted...then it should be, of course, possible to sustain

2312-659: A new, heavier element 93, that "it is conceivable that the nucleus breaks up into several large fragments." However, the quoted objection comes some distance down, and was but one of several gaps she noted in Fermi's claim. Although Noddack was a renowned analytical chemist, she lacked the background in physics to appreciate the enormity of what she was proposing. After the Fermi publication, Otto Hahn , Lise Meitner , and Fritz Strassmann began performing similar experiments in Berlin . Meitner, an Austrian Jew, lost her Austrian citizenship with

2448-629: A not-for-profit organization in Montgomery County, Maryland called Damascus Energy, which focuses on energy efficiency within the home. Theodore Taylor also served on the President of the United States' commission concerning the Three Mile Island Accident , working to mitigate the issues associated with the reactor meltdown. Theodore Taylor was involved in many important projects and made numerous contributions to nuclear development for

2584-521: A nuclear bomb so small that it weighed only 20 pounds, but it was never developed and tested. Taylor designed the Super Oralloy Bomb , also known as the "SOB". It still holds the record for the largest fission explosion ever tested (as the Ivy King device tested during Operation Ivy), producing over 500 kilotons of TNT equivalent . Taylor was credited with developing multiple techniques that improved

2720-476: A nuclear reaction was relatively high. The patent concerning the prompt negative temperature coefficient was groundbreaking because it provided a markedly safer reactor even in the event of misuse. With the negative temperature coefficient, the reactor can mitigate sudden surges of reactivity propelled into the system. These patented realizations would later become vital components in the future of nuclear technology. The Curve of Binding Energy , by John McPhee ,

2856-416: A nuclear reaction. Cross sections are a function of incident neutron energy, and those for U and Pu are a million times higher than U at lower neutron energy levels. Absorption of any neutron makes available to the nucleus binding energy of about 5.3 MeV. U needs a fast neutron to supply the additional 1 MeV needed to cross the critical energy barrier for fission. In

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2992-404: A nuclear reactor or nuclear weapon, the overwhelming majority of fission events are induced by bombardment with another particle, a neutron, which is itself produced by prior fission events. Fissionable isotopes such as uranium-238 require additional energy provided by fast neutrons (such as those produced by nuclear fusion in thermonuclear weapons ). While some of the neutrons released from

3128-622: A nuclear reactor, ternary fission can produce three positively charged fragments (plus neutrons) and the smallest of these may range from so small a charge and mass as a proton ( Z  = 1), to as large a fragment as argon ( Z  = 18). The most common small fragments, however, are composed of 90% helium-4 nuclei with more energy than alpha particles from alpha decay (so-called "long range alphas" at ~16 megaelectronvolts (MeV)), plus helium-6 nuclei, and tritons (the nuclei of tritium ). Though less common than binary fission, it still produces significant helium-4 and tritium gas buildup in

3264-418: A patent protecting their discovery of an efficient method of producing isotopes from thermonuclear explosions. The patent concerning the production of isotopes from thermonuclear explosions was groundbreaking because of its efficiency and cost effectiveness. It also provides a means for attaining necessary elements that otherwise are difficult to find in nature. Prior to this discovery, the cost per neutron in

3400-598: A physicist. Apart from education, he also developed an interest in throwing discus at Exeter. This interest continued into his college career, as he continued to throw discus at Caltech. He enrolled at the California Institute of Technology in 1942 and then spent his second and third years in the Navy V-12 program . This accelerated his schooling and he graduated with a bachelor's degree in physics from Caltech in 1945 at age nineteen. After graduation, he attended

3536-655: A plausible nuclear weapon using declassified and public information. According to Freitas and Merkle, the only known extant source on Taylor's concept of the " Santa Claus machine " is found in Nigel Calder's Spaceships of the Mind . The concept would use a large mass spectrometer to separate an ion beam into atomic elements for later use in making products. Taylor was a member of the Pugwash Conferences on Science and World Affairs and attended several of its meetings during

3672-450: A position that sought to develop small yield nuclear weapons that could target specific areas and minimize collateral damage. Taylor was not only involved in the publication of the aforementioned books, but he, along with a few of his colleagues, was also responsible for a number of patents involving nuclear physics. Taylor is credited with patenting a nuclear reactor with a prompt negative temperature coefficient and fuel element, along with

3808-510: A position. Taylor was unsure of the details of his new job at Los Alamos prior to his arrival. He had only been briefed that his first assignment related to investigations of Neutron Diffusion Theory , a theoretical analysis of neutron movement within a nuclear core . While at Los Alamos, Taylor's strictly anti-nuclear development beliefs changed. His theory on preventing nuclear war turned to developing bombs of unprecedented power in an attempt to make people, including governments, so afraid of

3944-561: A project in bomb efficiency; it ended up being the most efficient fission bomb ever exploded in the kiloton range. Apart from bombs, Taylor also explored concepts of producing large amounts of nuclear fuel in an expedited manner. His plans, known as MICE (Megaton Ice Contained Explosions), essentially sought to plant a thermonuclear weapon deep in the ice and detonate it, resulting in a giant underground pool of radioactive materials that could then be retrieved. While his idea had merit, Taylor ultimately received little support for this concept and

4080-476: A reactor that produced isotopes used in the medical field. In 1958, Taylor began working on Project Orion , which sought to develop space travel that relied on nuclear energy as the fuel source. The proposed spacecraft would use a series of nuclear fission reactions as its propellant, thus accelerating space travel while eliminating the Earth's source of fuel for nuclear weaponry. In collaboration with Dyson, Taylor led

4216-512: A recoilless rifle either erected and fixed on as freestanding tripod or mounted on the frame of a light utility vehicle, such as the Jeep, the former functioned similarly to other modern rocket propelled rounds (see RPG-7 ). It was a mounted weapons system, which means that it would be set up, aimed, and fired as a crew-served weapon . Taylor also designed fission bombs smaller than Davy Crockett, which were developed after he left Los Alamos. He designed

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4352-583: A small fraction of fission products. Neutron absorption which does not lead to fission produces plutonium (from U ) and minor actinides (from both U and U ) whose radiotoxicity is far higher than that of the long lived fission products. Concerns over nuclear waste accumulation and the destructive potential of nuclear weapons are a counterbalance to the peaceful desire to use fission as an energy source . The thorium fuel cycle produces virtually no plutonium and much less minor actinides, but U - or rather its decay products - are

4488-601: A supercritical chain-reaction (one in which each fission cycle yields more neutrons than it absorbs). Without their existence, the nuclear chain-reaction would be prompt critical and increase in size faster than it could be controlled by human intervention. In this case, the first experimental atomic reactors would have run away to a dangerous and messy "prompt critical reaction" before their operators could have manually shut them down (for this reason, designer Enrico Fermi included radiation-counter-triggered control rods, suspended by electromagnets, which could automatically drop into

4624-631: A superior breeding potential for fast reactors." Critical fission reactors are the most common type of nuclear reactor. In a critical fission reactor, neutrons produced by fission of fuel atoms are used to induce yet more fissions, to sustain a controllable amount of energy release. Devices that produce engineered but non-self-sustaining fission reactions are subcritical fission reactors . Such devices use radioactive decay or particle accelerators to trigger fissions. Critical fission reactors are built for three primary purposes, which typically involve different engineering trade-offs to take advantage of either

4760-411: A third particle is emitted. This third particle is commonly an α particle . Since in nuclear fission, the nucleus emits more neutrons than the one it absorbs, a chain reaction is possible. Binary fission may produce any of the fission products, at 95±15 and 135±15 daltons . However, the binary process happens merely because it is the most probable. In anywhere from two to four fissions per 1000 in

4896-454: A very large amount of energy even by the energetic standards of radioactive decay . Nuclear fission was discovered by chemists Otto Hahn and Fritz Strassmann and physicists Lise Meitner and Otto Robert Frisch . Hahn and Strassmann proved that a fission reaction had taken place on 19 December 1938, and Meitner and her nephew Frisch explained it theoretically in January 1939. Frisch named

5032-496: Is a " closed fuel cycle ". Younes and Loveland define fission as, "...a collective motion of the protons and neutrons that make up the nucleus, and as such it is distinguishable from other phenomena that break up the nucleus. Nuclear fission is an extreme example of large- amplitude collective motion that results in the division of a parent nucleus into two or more fragment nuclei. The fission process can occur spontaneously, or it can be induced by an incident particle." The energy from

5168-503: Is by definition a reactor that produces more fissile material than it consumes and needs a minimum of two neutrons produced for each neutron absorbed in a fissile nucleus. Thus, in general, the conversion ratio (CR) is defined as the ratio of fissile material produced to that destroyed ...when the CR is greater than 1.0, it is called the breeding ratio (BR)... U offers a superior breeding potential for both thermal and fast reactors, while Pu offers

5304-427: Is called spontaneous fission , and was first observed in 1940. During induced fission, a compound system is formed after an incident particle fuses with a target. The resultant excitation energy may be sufficient to emit neutrons, or gamma-rays, and nuclear scission. Fission into two fragments is called binary fission, and is the most common nuclear reaction . Occurring least frequently is ternary fission , in which

5440-438: Is called the odd–even effect on the fragments' charge distribution. This can be seen in the empirical fragment yield data for each fission product, as products with even Z have higher yield values. However, no odd–even effect is observed on fragment distribution based on their A . This result is attributed to nucleon pair breaking . In nuclear fission events the nuclei may break into any combination of lighter nuclei, but

5576-413: Is characterized by the neutron multiplication factor k , which is defined as the ratio of the number of neutrons in one generation to the number in the preceding generation. If, in a reactor, k is less than unity, the reactor is subcritical, the number of neutrons decreases and the chain reaction dies out. If k > 1, the reactor is supercritical and the chain reaction diverges. This is the situation in

Upshot-Knothole Harry - Misplaced Pages Continue

5712-407: Is much less than the prompt energy, but it is a significant amount and is why reactors must continue to be cooled after they have been shut down and why the waste products must be handled with great care and stored safely." John Lilley states, "...neutron-induced fission generates extra neutrons which can induce further fissions in the next generation and so on in a chain reaction. The chain reaction

5848-417: Is recoverable, Prompt fission fragments amount to 168 MeV, which are easily stopped with a fraction of a millimeter. Prompt neutrons total 5 MeV, and this energy is recovered as heat via scattering in the reactor. However, many fission fragments are neutron-rich and decay via β emissions. According to Lilley, "The radioactive decay energy from the fission chains is the second release of energy due to fission. It

5984-438: Is relatively low compared to how it should be, and that if one were to create a nuclear reactor with the capability of cooling down—without the initiation of a fission reaction—then efforts at harvesting nuclear energy would be more incentivized and exponentially safer. Taylor also wrote the book Nuclear Proliferation: Motivations, Capabilities and Strategies for Control with Harold Feiveson and Ted Greenwood. The book explains

6120-402: Is released by a fast neutron chain reaction in one or more of the materials known to show nuclear fission." According to Rhodes, "Untamped, a bomb core even as large as twice the critical mass would completely fission less than 1 percent of its nuclear material before it expanded enough to stop the chain reaction from proceeding. Tamper always increased efficiency: it reflected neutrons back into

6256-423: Is the atomic mass of a hydrogen atom, m n is the mass of a neutron, and c is the speed of light . Thus, the mass of an atom is less than the mass of its constituent protons and neutrons, assuming the average binding energy of its electrons is negligible. The binding energy B is expressed in energy units, using Einstein's mass-energy equivalence relationship. The binding energy also provides an estimate of

6392-418: Is the energy required to separate it into its constituent neutrons and protons." m ( A , Z ) = Z m H + N m n − B / c 2 {\displaystyle m(\mathbf {A} ,\mathbf {Z} )=\mathbf {Z} m_{H}+\mathbf {N} m_{n}-\mathbf {B} /c^{2}} where A is mass number , Z is atomic number , m H

6528-466: Is written primarily about the life of Theodore Taylor, as he and McPhee traveled together quite often—spending a great deal of time with one another. It is evident that during their time together, McPhee was very inclined to learn from Taylor. Many of Taylor's personal opinions regarding nuclear energy and safety are mentioned throughout McPhee's writing. McPhee voices one of Taylor's bigger concerns in particular—that plutonium can be devastating if left in

6664-646: The Anschluss , the union of Austria with Germany in March 1938, but she fled in July 1938 to Sweden and started a correspondence by mail with Hahn in Berlin. By coincidence, her nephew Otto Robert Frisch , also a refugee, was also in Sweden when Meitner received a letter from Hahn dated 19 December describing his chemical proof that some of the product of the bombardment of uranium with neutrons

6800-684: The Kaiser Wilhelm Society for Chemistry, today part of the Free University of Berlin , following over four decades of work on the science of radioactivity and the elaboration of new nuclear physics that described the components of atoms. In 1911, Ernest Rutherford proposed a model of the atom in which a very small, dense and positively charged nucleus of protons was surrounded by orbiting, negatively charged electrons (the Rutherford model ). Niels Bohr improved upon this in 1913 by reconciling

6936-560: The University of California, Santa Cruz and Princeton University . His focus eventually turned to renewable energy , and In 1980 Taylor started a company called Nova Incorporated, which focused on nuclear energy alternatives as a means of supplementing the energy requirements of the earth. He studied energy capture from sources like cooling ice ponds and heating solar ponds , and eventually turned to energy conservation within buildings. Concerning this work in energy conservation, he founded

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7072-486: The cyclotron and a beta-ray spectrograph. After failing an oral preliminary examination on mechanics and heat, and a second prelim in modern physics in 1949, Taylor was disqualified from the graduate program. Taylor married Caro Arnim in 1948 and had five children in the following years: Clare Hastings, Katherine Robertson, Christopher Taylor, Robert Taylor, and Jeffrey Taylor. Arnim was majoring in Greek at Scripps College ,

7208-523: The midshipman school at Throgs Neck , in the Bronx, New York, for one year to fulfill his naval active duty requirement. He was discharged in mid-1946, by which time he had been promoted to the rank of lieutenant . He then enrolled in a graduate program in theoretical physics at the University of California at Berkeley , while also working part-time at the Berkeley Radiation laboratory , mainly on

7344-421: The nuclear fuel cycle is based on one of three fissile materials, U, U, and Pu, and the associated isotopic chains. For the current generation of LWRs , the enriched U contains 2.5~4.5 wt% of U, which is fabricated into UO 2 fuel rods and loaded into fuel assemblies." Lee states, "One important comparison for the three major fissile nuclides, U, U, and Pu, is their breeding potential. A breeder

7480-621: The nuclear shell model for the nucleus. The nuclides that can sustain a fission chain reaction are suitable for use as nuclear fuels . The most common nuclear fuels are U (the isotope of uranium with mass number 235 and of use in nuclear reactors) and Pu (the isotope of plutonium with mass number 239). These fuels break apart into a bimodal range of chemical elements with atomic masses centering near 95 and 135 daltons ( fission products ). Most nuclear fuels undergo spontaneous fission only very slowly, decaying instead mainly via an alpha - beta decay chain over periods of millennia to eons . In

7616-543: The 1951 Nobel Prize in Physics for "Transmutation of atomic nuclei by artificially accelerated atomic particles" , although it was not the nuclear fission reaction later discovered in heavy elements. English physicist James Chadwick discovered the neutron in 1932. Chadwick used an ionization chamber to observe protons knocked out of several elements by beryllium radiation, following up on earlier observations made by Joliot-Curies . In Chadwick's words, "...In order to explain

7752-496: The 1980s. After his retirement he lived in Wellsville, New York . Freeman Dyson said of Taylor, "Very few people have Ted's imagination. ... I think he is perhaps the greatest man that I ever knew well. And he is completely unknown." 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

7888-479: The Atlixo 13 neighborhood of Cuernavaca . His upbringing was quiet and religious, and his home filled with books, mainly atlases and geographies, which he would read by candlelight. This interest followed him into adulthood. Taylor showed an early interest in chemistry, specifically pyrotechnics , when he received a chemistry set at the age of ten. This fascination was enhanced when a small and exclusive university in

8024-600: The US. Though not considered a brilliant physicist from a calculative viewpoint, his vision and creativity allowed him to thrive in the field. The later part of Taylor's career was focused on nuclear energy instead of weaponry, and included his work on Project Orion , nuclear reactor developments, and anti- nuclear proliferation . Ted Taylor was born in Mexico City , Mexico, on July 11, 1925. His mother and father were both Americans. His mother, Barbara Southworth Howland Taylor, held

8160-549: The United States. During his time at Los Alamos, he was responsible for designing the smallest fission bomb of the era, named Davy Crockett , which weighed only 50 pounds, measured approximately 12 inches across, and could produce between 10 and 20 tons of TNT equivalent . This device was formerly known as the M28 Weapons System. The Davy Crockett itself was the M388 Atomic Round fired from the weapons system, featuring

8296-560: The age of 15. Not yet meeting the age requirements for American universities, he then attended the Exeter Academy in New Hampshire for one year, where he took Modern Physics from Elbert P. Little. This developed his interest in physics, though he displayed poor academic performance in the course: Little gave Taylor a grade D on his final winter term examination. He quickly brushed this failure off, and soon confirmed that he wanted to be

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8432-549: The area built a chemistry laboratory in his neighborhood, after which Taylor had access to items from local druggists that otherwise would not have been readily available, including corrosive and explosive chemicals, as well as nitric and sulfuric acids. These allowed him to conduct his own experiments. He also often read through the 1913 New International Encyclopedia , which contained extensive chemistry, for new concoctions to make. These included sleeping drugs, small explosives, guncotton , precipitates , and many more. His mother

8568-698: The binding energy as the sum of five terms, which are the volume energy, a surface correction, Coulomb energy, a symmetry term, and a pairing term: B = a v A − a s A 2 / 3 − a c Z 2 A 1 / 3 − a a ( N − Z ) 2 A ± Δ {\displaystyle B=a_{v}\mathbf {A} -a_{s}\mathbf {A} ^{2/3}-a_{c}{\frac {\mathbf {Z} ^{2}}{\mathbf {A} ^{1/3}}}-a_{a}{\frac {(\mathbf {N} -\mathbf {Z} )^{2}}{\mathbf {A} }}\pm \Delta } where

8704-456: The book focused on techniques to enhance sustainability and expanded on different sources of energy that could be used alternatively to meet the power needs of the earth. This book was also a culmination of his focus on nuclear security and the ramifications of the use of nuclear weaponry. In it he addressed the potential effects of nuclear fallout on the environment. This 1973 hardcover discussed potential sources of energy in 2000, along with

8840-456: The case of U however, that extra energy is provided when U adjusts from an odd to an even mass. In the words of Younes and Lovelace, "...the neutron absorption on a U target forms a U nucleus with excitation energy greater than the critical fission energy, whereas in the case of n + U , the resulting U nucleus has an excitation energy below the critical fission energy." About 6 MeV of

8976-446: The center of Chicago Pile-1 ). If these delayed neutrons are captured without producing fissions, they produce heat as well. The binding energy of the nucleus is the difference between the rest-mass energy of the nucleus and the rest-mass energy of the neutron and proton nucleons. The binding energy formula includes volume, surface and Coulomb energy terms that include empirically derived coefficients for all three, plus energy ratios of

9112-516: The classical music piped into their rooms, their experimentalist counterparts would uniformly shut the system off. Taylor attended the American School in Mexico City from elementary school through high school. A gifted student, he finished the fourth through sixth grades in one year. Being an accelerated student, Taylor found himself three years younger than his friends as he entered his teens. Taylor graduated early from high school in 1941 at

9248-425: The conceptualization of safer alternatives to the methods of acquiring nuclear energy that were available at the time. In fact, Taylor indirectly referenced a concept for a nuclear reactor which is inherently similar to a reactor that he patented in 1964. Taylor spent much of his time studying the risk potential of the nuclear power fuel cycle after learning about the detrimental effects that his nuclear weapons had on

9384-415: The consequences of nuclear warfare that they would not dare engage in this sort of altercation. He continued in his junior position at Los Alamos until 1953, when he took a temporary leave of absence to obtain his PhD from Cornell . Finishing his PhD in 1954, he returned to Los Alamos, and by 1956 he was famous for his work in small-bomb development. Freeman Dyson is quoted as saying, "A great part of

9520-425: The continental U.S.), much of which later accumulated in the vicinity of St. George, Utah. Because of this, the shot would become known as "Dirty Harry" in the press when details were released publicly. It would be among the most controversial of the U.S. nuclear weapon tests . Two years after the blast, Howard Hughes filmed the motion picture The Conqueror near St. George. The cast and crew totaled 220 people. By

9656-419: The core and its inertia...slowed the core's expansion and helped keep the core surface from blowing away." Rearrangement of the core material's subcritical components would need to proceed as fast as possible to ensure effective detonation. Additionally, a third basic component was necessary, "...an initiator—a Ra + Be source or, better, a Po + Be source, with the radium or polonium attached perhaps to one piece of

9792-405: The core and the beryllium to the other, to smash together and spray neutrons when the parts mated to start the chain reaction." However, any bomb would "necessitate locating, mining and processing hundreds of tons of uranium ore...", while U-235 separation or the production of Pu-239 would require additional industrial capacity. The discovery of nuclear fission occurred in 1938 in the buildings of

9928-414: The curve of binding energy, where the fission products cluster, it is easily observed that the binding energy of the fission products tends to center around 8.5 MeV per nucleon. Thus, in any fission event of an isotope in the actinide mass range, roughly 0.9 MeV are released per nucleon of the starting element. The fission of U by a slow neutron yields nearly identical energy to the fission of U by

10064-651: The deputy director of the Defense Atomic Support Agency (a branch within the Department of Defense), where he managed the U.S. nuclear weapons inventory. Then, in 1966 he created a consulting firm called the International Research and Technology Corporation, located in Vienna , Austria, which sought to prevent the development of more nuclear weapons programs. Taylor also worked as a visiting professor at

10200-416: The element thorium was slowly and spontaneously transmuting itself into argon gas!" In 1919, following up on an earlier anomaly Ernest Marsden noted in 1915, Rutherford attempted to "break up the atom." Rutherford was able to accomplish the first artificial transmutation of nitrogen into oxygen, using alpha particles directed at nitrogen N + α → O + p.  Rutherford stated, "...we must conclude that

10336-485: The end of 1980, as ascertained by People magazine , 91 of them had developed some form of cancer and 46 had died of the disease, including the main stars John Wayne and Susan Hayward . Hicks (1981) evaluated the gamma-exposure rates and levels of radionuclides. Within the report by Hicks he was required to omit data of U-233, U-235, U-238 & Pu-239, and Pu-240 in order to make the report unclassified. In measurement of cumulative exposures rates of populations within

10472-406: The energy spectrum for fast fission is similar. ) Among the heavy actinide elements, however, those isotopes that have an odd number of neutrons (such as U with 143 neutrons) bind an extra neutron with an additional 1 to 2 MeV of energy over an isotope of the same element with an even number of neutrons (such as U with 146 neutrons). This extra binding energy is made available as a result of

10608-661: The energy thus released. The results confirmed that fission was occurring and hinted strongly that it was the isotope uranium 235 in particular that was fissioning. The next day, the Fifth Washington Conference on Theoretical Physics began in Washington, D.C. under the joint auspices of the George Washington University and the Carnegie Institution of Washington . There, the news on nuclear fission

10744-446: The energy waste and necessity for precision of the original reaction mechanism. This technique is still found in all U.S. fission nuclear weapons today. He also developed a technique that greatly reduced the size of atomic bombs. First tested in a bomb called "Scorpion", it used a reflector made of beryllium , which was drastically lighter than the materials previously used, such as tungsten carbide (WC). Taylor recognized that although

10880-412: The environment, so he sought to explore new opportunities for safer use of nuclear power. In his writing, Taylor argued that the most dangerous and devastating events that could possibly occur during nuclear research would most likely happen at reactors that are incapable of running efficiently and maintaining a safe temperature. Taylor went on to state that the prioritization of safety in nuclear reactors

11016-450: The equivalent of roughly >2 trillion kelvin, for each fission event. The exact isotope which is fissioned, and whether or not it is fissionable or fissile, has only a small impact on the amount of energy released. This can be easily seen by examining the curve of binding energy (image below), and noting that the average binding energy of the actinide nuclides beginning with uranium is around 7.6 MeV per nucleon. Looking further left on

11152-449: The excitation energy is sufficient, the nucleus breaks into fragments. This is called scission, and occurs at about 10 seconds. The fragments can emit prompt neutrons at between 10 and 10 seconds. At about 10 seconds, the fragments can emit gamma rays. At 10 seconds β decay, β- delayed neutrons , and gamma rays are emitted from the decay products . Typical fission events release about two hundred million eV (200 MeV) of energy,

11288-432: The explosion of nuclear weapons . Both uses are possible because certain substances called nuclear fuels undergo fission when struck by fission neutrons, and in turn emit neutrons when they break apart. This makes a self-sustaining nuclear chain reaction possible, releasing energy at a controlled rate in a nuclear reactor or at a very rapid, uncontrolled rate in a nuclear weapon. The amount of free energy released in

11424-424: The fact that effective forces in the nucleus are stronger for unlike neutron-proton pairs, rather than like neutron–neutron or proton–proton pairs. The pairing term arises from the fact that like nucleons form spin-zero pairs in the same spatial state. The pairing is positive if N and Z are both even, adding to the binding energy. In fission there is a preference for fission fragments with even Z , which

11560-426: The fast neutrons are supplied by nuclear fusion). However, this process cannot happen to a great extent in a nuclear reactor, as too small a fraction of the fission neutrons produced by any type of fission have enough energy to efficiently fission U . (For example, neutrons from thermal fission of U have a mean energy of 2 MeV, a median energy of 1.6 MeV, and a mode of 0.75 MeV, and

11696-461: The fission bomb. For example, he was largely responsible for the development of fusion boosting , which is a technique that improves the reaction yield and efficiency of a nuclear reaction. This technique was a re-invention of the implosion mechanism used in the bomb detonated at Nagasaki. He theorized a series of nuclear reactions within the implosion mechanism that, in combination, trigger the large chain reaction to detonate. This eliminated much of

11832-409: The fission of U are fast enough to induce another fission in U , most are not, meaning it can never achieve criticality. While there is a very small (albeit nonzero) chance of a thermal neutron inducing fission in U , neutron absorption is orders of magnitude more likely. Fission cross sections are a measurable property related to the probability that fission will occur in

11968-450: The fission of an equivalent amount of U is a million times more than that released in the combustion of methane or from hydrogen fuel cells . The products of nuclear fission, however, are on average far more radioactive than the heavy elements which are normally fissioned as fuel, and remain so for significant amounts of time, giving rise to a nuclear waste problem. However, the seven long-lived fission products make up only

12104-443: The fission rate of uranium was negligible, as predicted by Niels Bohr ; it was not negligible. The unpredictable composition of the products (which vary in a broad probabilistic and somewhat chaotic manner) distinguishes fission from purely quantum tunneling processes such as proton emission , alpha decay , and cluster decay , which give the same products each time. Nuclear fission produces energy for nuclear power and drives

12240-431: The fission-input energy is supplied by the simple binding of an extra neutron to the heavy nucleus via the strong force; however, in many fissionable isotopes, this amount of energy is not enough for fission. Uranium-238, for example, has a near-zero fission cross section for neutrons of less than 1 MeV energy. If no additional energy is supplied by any other mechanism, the nucleus will not fission, but will merely absorb

12376-491: The fragments ( heating the bulk material where fission takes place). Like nuclear fusion , for fission to produce energy, the total binding energy of the resulting elements must be greater than that of the starting element. Fission is a form of nuclear transmutation because the resulting fragments (or daughter atoms) are not the same element as the original parent atom. The two (or more) nuclei produced are most often of comparable but slightly different sizes, typically with

12512-410: The fuel rods of modern nuclear reactors. Bohr and Wheeler used their liquid drop model , the packing fraction curve of Arthur Jeffrey Dempster , and Eugene Feenberg's estimates of nucleus radius and surface tension, to estimate the mass differences of parent and daughters in fission. They then equated this mass difference to energy using Einstein's mass-energy equivalence formula. The stimulation of

12648-405: The great penetrating power of the radiation we must further assume that the particle has no net charge..." The existence of the neutron was first postulated by Rutherford in 1920, and in the words of Chadwick, "...how on earth were you going to build up a big nucleus with a large positive charge? And the answer was a neutral particle." Subsequently, he communicated his findings in more detail. In

12784-435: The group dubbed ausenium and hesperium . However, not all were convinced by Fermi's analysis of his results, though he would win the 1938 Nobel Prize in Physics for his "demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons". The German chemist Ida Noddack notably suggested in 1934 that instead of creating

12920-487: The heat or the neutrons produced by the fission chain reaction: While, in principle, all fission reactors can act in all three capacities, in practice the tasks lead to conflicting engineering goals and most reactors have been built with only one of the above tasks in mind. (There are several early counter-examples, such as the Hanford N reactor , now decommissioned). As of 2019, the 448 nuclear power plants worldwide provided

13056-500: The interacting balls on the table and their elastic collisions within the confining framework of the reflector cushions helped him to conceptualize the difficult abstractions of cross sections, neutron scattering, and fission chain reactions. As a child, he developed a passion for music, and would quietly sit for an hour and listen to his favorite songs in the mornings before school. Later, while completing his PhD at Cornell, he noted that while his theoretical physicist peers embraced

13192-412: The latter are used in fast-neutron reactors , and in weapons). According to Younes and Loveland, "Actinides like U that fission easily following the absorption of a thermal (0.25 meV) neutron are called fissile , whereas those like U that do not easily fission when they absorb a thermal neutron are called fissionable ." After an incident particle has fused with a parent nucleus, if

13328-427: The line has the slope N = Z , while the heavier nuclei require additional neutrons to remain stable. Nuclei that are neutron- or proton-rich have excessive binding energy for stability, and the excess energy may convert a neutron to a proton or a proton to a neutron via the weak nuclear force, a process known as beta decay . Neutron-induced fission of U-235 emits a total energy of 207 MeV, of which about 200 MeV

13464-474: The mechanism of neutron pairing effects , which itself is caused by the Pauli exclusion principle , allowing an extra neutron to occupy the same nuclear orbital as the last neutron in the nucleus. In such isotopes, therefore, no neutron kinetic energy is needed, for all the necessary energy is supplied by absorption of any neutron, either of the slow or fast variety (the former are used in moderated nuclear reactors, and

13600-413: The midshipmen school, he received news of the atomic bombing of Hiroshima by the United States. He immediately wrote a letter home discussing the perils of nuclear proliferation and his fears that it would lead to the end of mankind in the event of another war. He showed some optimism, however, as he felt with proper leadership the nuclear bomb could result in the end of wars altogether. Either way, he

13736-465: The most common event is not fission to equal mass nuclei of about mass 120; the most common event (depending on isotope and process) is a slightly unequal fission in which one daughter nucleus has a mass of about 90 to 100 daltons and the other the remaining 130 to 140 daltons. Stable nuclei, and unstable nuclei with very long half-lives , follow a trend of stability evident when Z is plotted against N . For lighter nuclei less than N = 20,

13872-523: The neutron, as happens when U absorbs slow and even some fraction of fast neutrons, to become U . The remaining energy to initiate fission can be supplied by two other mechanisms: one of these is more kinetic energy of the incoming neutron, which is increasingly able to fission a fissionable heavy nucleus as it exceeds a kinetic energy of 1 MeV or more (so-called fast neutrons). Such high energy neutrons are able to fission U directly (see thermonuclear weapon for application, where

14008-399: The news and carried it back to Columbia. Rabi said he told Enrico Fermi; Fermi gave credit to Lamb. Bohr soon thereafter went from Princeton to Columbia to see Fermi. Not finding Fermi in his office, Bohr went down to the cyclotron area and found Herbert L. Anderson . Bohr grabbed him by the shoulder and said: "Young man, let me explain to you about something new and exciting in physics." It

14144-433: The nitrogen atom is disintegrated," while the newspapers stated he had split the atom . This was the first observation of a nuclear reaction, that is, a reaction in which particles from one decay are used to transform another atomic nucleus. It also offered a new way to study the nucleus. Rutherford and James Chadwick then used alpha particles to "disintegrate" boron, fluorine, sodium, aluminum, and phosphorus before reaching

14280-441: The nuclear binding energy is proportional to the nuclear volume, while nucleons near the surface interact with fewer nucleons, reducing the effect of the volume term. According to Lilley, "For all naturally occurring nuclei, the surface-energy term dominates and the nucleus exists in a state of equilibrium." The negative contribution of Coulomb energy arises from the repulsive electric force of the protons. The symmetry term arises from

14416-452: The nuclear force approaches a constant value for large A , while the Coulomb acts over a larger distance so that electrical potential energy per proton grows as Z increases. Fission energy is released when a A is larger than 120 nucleus fragments. Fusion energy is released when lighter nuclei combine. Carl Friedrich von Weizsäcker's semi-empirical mass formula may be used to express

14552-465: The nucleus after neutron bombardment was analogous to the vibrations of a liquid drop, with surface tension and the Coulomb force in opposition. Plotting the sum of these two energies as a function of elongated shape, they determined the resultant energy surface had a saddle shape. The saddle provided an energy barrier called the critical energy barrier. Energy of about 6 MeV provided by the incident neutron

14688-430: The plutonium-239 is later fissioned. On the other hand, so-called delayed neutrons emitted as radioactive decay products with half-lives up to several minutes, from fission-daughters, are very important to reactor control , because they give a characteristic "reaction" time for the total nuclear reaction to double in size, if the reaction is run in a " delayed-critical " zone which deliberately relies on these neutrons for

14824-410: The possibility of a nuclear chain reaction. The 11 February 1939 paper by Meitner and Frisch compared the process to the division of a liquid drop and estimated the energy released at 200 MeV. The 1 September 1939 paper by Bohr and Wheeler used this liquid drop model to quantify fission details, including the energy released, estimated the cross section for neutron-induced fission, and deduced U

14960-521: The process "fission" by analogy with biological fission of living cells. In their second publication on nuclear fission in February 1939, Hahn and Strassmann predicted the existence and liberation of additional neutrons during the fission process, opening up the possibility of a nuclear chain reaction . For heavy nuclides , it is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of

15096-427: The project development team for six years until the 1963 Nuclear Test Ban Treaty was instituted. After this, they could not test their developments and the project became unviable. Theodore Taylor's career shifted again after project Orion. He developed an even greater fear of the potential ramifications of his entire life's work, and began taking precautionary measures to mitigate those concerns. In 1964 he served as

15232-414: The project never came to fruition. Ted Taylor was an accomplished author in the latter part of his career. He worked in cooperation with many specialists in other fields to publish his work on anti-nuclear proliferation and sustainable nuclear energy. Perhaps the greatest fear that propelled Taylor to work so fervently in these areas was the realization that the consequences of nuclear material ending up in

15368-514: The quantum behavior of electrons (the Bohr model ). In 1928, George Gamow proposed the Liquid drop model , which became essential to understanding the physics of fission. In 1896, Henri Becquerel had found, and Marie Curie named, radioactivity. In 1900, Rutherford and Frederick Soddy , investigating the radioactive gas emanating from thorium , "conveyed the tremendous and inevitable conclusion that

15504-406: The rest as kinetic energy of fission fragments (this appears almost immediately when the fragments impact surrounding matter, as simple heat). Some processes involving neutrons are notable for absorbing or finally yielding energy — for example neutron kinetic energy does not yield heat immediately if the neutron is captured by a uranium-238 atom to breed plutonium-239, but this energy is emitted if

15640-616: The small-bomb development of the last five years [at Los Alamos] was directly due to Ted." Although the majority of the brilliant minds at Los Alamos were focused on developing the fusion bomb , Taylor remained hard at work on improving fission bombs . His innovations in this area of study were so important that he was eventually given the freedom to choose whatever he wanted to study. Eventually, Taylor's stance on nuclear warfare and weapon development changed, altering his career path. In 1956, Taylor left his position at Los Alamos and went to work for General Atomics . Here, he developed TRIGA ,

15776-492: The so-called Harry test deposited the 3rd highest amount of Caesium-137 , Niobium-95 , Strontium-90 , Zirconium-95 , the fourth highest deposit for Niobium-95m , Praseodymium-144 , fifth for Uranium-240 , Ruthenium-106 , sixth for Iodine-131 , Tellurium-127m , eighth for deposition of Cobalt-60 , tenth for deposition of Europium-155 , thirteenth for Strontium-89 , Yttrium-90 , and sixteenth for Beryllium-7 , (the source lists Sr-90 twice, at 3rd and thirteenth, thirteenth

15912-475: The speed of light, due to Coulomb repulsion . Also, an average of 2.5 neutrons are emitted, with a mean kinetic energy per neutron of ~2 MeV (total of 4.8 MeV). The fission reaction also releases ~7 MeV in prompt gamma ray photons . The latter figure means that a nuclear fission explosion or criticality accident emits about 3.5% of its energy as gamma rays, less than 2.5% of its energy as fast neutrons (total of both types of radiation ~6%), and

16048-403: The techniques were well-known. Meitner and Frisch then correctly interpreted Hahn's results to mean that the nucleus of uranium had split roughly in half. Frisch suggested the process be named "nuclear fission", by analogy to the process of living cell division into two cells, which was then called binary fission . Just as the term nuclear "chain reaction" would later be borrowed from chemistry, so

16184-536: The term "fission" was borrowed from biology. News spread quickly of the new discovery, which was correctly seen as an entirely novel physical effect with great scientific—and potentially practical—possibilities. Meitner's and Frisch's interpretation of the discovery of Hahn and Strassmann crossed the Atlantic Ocean with Niels Bohr, who was to lecture at Princeton University . I.I. Rabi and Willis Lamb , two Columbia University physicists working at Princeton, heard

16320-414: The total energy released from fission. The curve of binding energy is characterized by a broad maximum near mass number 60 at 8.6 MeV, then gradually decreases to 7.6 MeV at the highest mass numbers. Mass numbers higher than 238 are rare. At the lighter end of the scale, peaks are noted for helium-4, and the multiples such as beryllium-8, carbon-12, oxygen-16, neon-20 and magnesium-24. Binding energy due to

16456-614: The two most dangerous mechanisms by which nuclear proliferation could be devastating for the world, as well as how to disincentivize nuclear proliferation within destabilizing political systems. Taylor further collaborated with George Gamow on a study called, "What the World Needs Is a Good Two-Kiloton Bomb", which investigated the concept of small nuclear artillery weapons. This paper reflected another shift in Taylor's beliefs about nuclear weapons. He had changed from his deterrent position to

16592-584: The vicinity of the nucleus, and that gave it more time to be captured." Fermi's team, studying radiative capture which is the emission of gamma radiation after the nucleus captures a neutron, studied sixty elements, inducing radioactivity in forty. In the process, they discovered the ability of hydrogen to slow down the neutrons. Enrico Fermi and his colleagues in Rome studied the results of bombarding uranium with neutrons in 1934. Fermi concluded that his experiments had created new elements with 93 and 94 protons, which

16728-428: The words of Richard Rhodes , referring to the neutron, "It would therefore serve as a new nuclear probe of surpassing power of penetration." Philip Morrison stated, "A beam of thermal neutrons moving at about the speed of sound...produces nuclear reactions in many materials much more easily than a beam of protons...traveling thousands of times faster." According to Rhodes, "Slowing down a neutron gave it more time in

16864-467: The wrong hands could be severe. Nuclear Theft: Risks and Safeguards is a book Taylor wrote in collaboration with Mason Willrich in the 1970s. According to reviews, the book predicted a future where nuclear energy was the primary energy source in the United States, and therefore needed enhanced protective measures to protect the public. In the book, Taylor and Willrich provide multiple recommendations on ways to prevent nuclear material from ending up in

17000-455: The wrong hands, as they anticipated that there would be multiple more sources of nuclear byproducts and therefore more opportunity for nuclear theft. This book likely was a culmination of much of Ted's work in the field, as he often toured nuclear reactor sites and provided insight on potential weak points in their security measures. Taylor also co-authored the book The Restoration of the Earth with Charles C. Humpstone . According to reviews,

17136-578: The wrong hands. According to McPhee, Taylor suspected that if plutonium were to be acquired by someone with ill-intentions and handled improperly, the aftermath could be catastrophic—as plutonium is a rather volatile element and can be lethal for anyone within hundreds of miles. This clearly can be avoided, Taylor suggests, if nuclear reactors are protected and all sources of nuclear fuel elements are heavily guarded. The book would inspire Princeton student John Aristotle Phillips , and several other imitators, to prove Taylor's contention that "anyone" could design

17272-438: Was barium . Hahn suggested a bursting of the nucleus, but he was unsure of what the physical basis for the results were. Barium had an atomic mass 40% less than uranium, and no previously known methods of radioactive decay could account for such a large difference in the mass of the nucleus. Frisch was skeptical, but Meitner trusted Hahn's ability as a chemist. Marie Curie had been separating barium from radium for many years, and

17408-496: Was clear to a number of scientists at Columbia that they should try to detect the energy released in the nuclear fission of uranium from neutron bombardment. On 25 January 1939, a Columbia University team conducted the first nuclear fission experiment in the United States, which was done in the basement of Pupin Hall . The experiment involved placing uranium oxide inside of an ionization chamber and irradiating it with neutrons, and measuring

17544-589: Was even taken to The Pentagon as a consultant on strategies and the potential outcomes of a nuclear war with Russia. In total, Taylor was responsible for the development of eight bombs: the Super Oralloy Bomb, Davey Crockett, Scorpion, Hamlet, Bee, Hornet, Viper, and the Puny Plutonium bomb. The latter was the first-ever dud in the history of U.S. nuclear tests. He produced the bomb called Hamlet after receiving direct orders from military officials to pursue

17680-408: Was extremely tolerant of his experimentation but prohibited any experiments that involved nitroglycerin . Growing up, Taylor also showed an interest in billiards . In the afternoons after school he played billiards for almost ten hours a week. He would recall this early interest as his introduction to the mechanics of collisions, relating it to his later work in particle physics . The behavior of

17816-494: Was necessary to overcome this barrier and cause the nucleus to fission. According to John Lilley, "The energy required to overcome the barrier to fission is called the activation energy or fission barrier and is about 6 MeV for A  ≈ 240. It is found that the activation energy decreases as A increases. Eventually, a point is reached where activation energy disappears altogether...it would undergo very rapid spontaneous fission." Maria Goeppert Mayer later proposed

17952-482: Was omitted here). The deposition pattern was most similar to test name CLIMAX. Monitoring personnel including United States of America Atomic Energy Commission personnel monitored the resultant radioactive fallout in areas including St.George , Utah . Fallout from the test fell on 3046 counties of the United States. Due to a miscalculation and change in wind-direction, this Upshot–Knothole test released an unusually large amount of fallout (the highest of any test in

18088-415: Was spread even further, which fostered many more experimental demonstrations. The 6 January 1939 Hahn and Strassman paper announced the discover of fission. In their second publication on nuclear fission in February 1939, Hahn and Strassmann used the term Uranspaltung (uranium fission) for the first time, and predicted the existence and liberation of additional neutrons during the fission process, opening up

18224-534: Was still very curious about the field of nuclear physics after his time as an undergraduate. Taylor began his work in nuclear physics in 1949 when he was hired to a junior position at Los Alamos National Laboratory in the Theoretical Physics Division. He received this job after failing out of the PhD program at Berkeley; J. Carson Mark connected Taylor with a leader at Los Alamos and recommended him for

18360-511: Was the major contributor to that cross section and slow-neutron fission. During this period the Hungarian physicist Leó Szilárd realized that the neutron-driven fission of heavy atoms could be used to create a nuclear chain reaction. Such a reaction using neutrons was an idea he had first formulated in 1933, upon reading Rutherford's disparaging remarks about generating power from neutron collisions. However, Szilárd had not been able to achieve

18496-449: Was the most efficient pure fission design with a yield below 100 kt ever tested. The design utilized a new hollow core concept. The concept was termed as "radical implosion system" aiming towards reducing the amount of fissionable materials present in the weapon's core while generating moderately high yield. The device was detonated in Area 3 of the test site. Of the 11 Upshot–Knothole tests,

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