* 1978 – Development of the neutron bomb is canceled by President Jimmy Carter.

In nuclear physics, a single stray neutron can result in an prompt critical event, which may be finally be energetic enough for a nuclear reactor meltdown or ( in a bomb ) a nuclear explosion.

* Samuel T. Cohen, on the DVD, actual inventor of the neutron bomb

* April 7 – U. S. President Jimmy Carter decides to postpone production of the neutron bomb – a weapon which kills people with radiation but leaves buildings relatively intact.

In the past the neutron trigger for an atomic bomb tended to be beryllium and a high activity alpha emitter such as polonium ; an alternative to polonium is Pu-238.

# REDIRECT neutron bomb

A neutron bomb or enhanced radiation weapon ( ERW ) or weapon of reinforced radiation is a type of thermonuclear weapon designed specifically to release a large portion of its energy as energetic neutron radiation ( fast neutrons ) rather than explosive energy.

A neutron bomb is a fission-fusion thermonuclear weapon ( hydrogen bomb ) in which the burst of neutrons generated by a fusion reaction is intentionally allowed to escape the weapon, rather than being absorbed by its other components.

Compared to a fission bomb with the identical explosive yield, a neutron bomb would emit about ten times the amount of neutron radiation.

In a fission bomb, the radiation pulse energy is approximately 5 % of the entire energy released ; in the neutron bomb it would be closer to 50 %.

A neutron bomb releases a much greater number of neutrons than a fission bomb of the same explosive yield.

Conception of the neutron bomb is generally credited to Samuel T. Cohen of the Lawrence Livermore National Laboratory, who developed the concept in 1958.

Besides the United States and Soviet Union, France and China are understood to have tested neutron or enhanced radiation bombs in the past, with France apparently leading the field with an early test of the technology in 1967 and an " actual " neutron bomb in 1980.

Lawrence Livermore National Laboratory director Harold Brown and Soviet General Secretary Leonid Brezhnev both described the neutron bomb as a " capitalist bomb ", because it was designed to destroy people while preserving property.

Since neutrons are absorbed by air, even a high-yield neutron bomb is not able to radiate neutrons beyond its blast range and so would theoretically have no destructive advantage over a normal hydrogen bomb.

Americium-241 was directly obtained from plutonium upon absorption of one neutron.

The second isotope < sup > 242 </ sup > Am was produced upon neutron bombardment of the already-created < sup > 241 </ sup > Am.

But in 1939, Robert Oppenheimer and others predicted that neutron stars above approximately three solar masses ( the Tolman – Oppenheimer – Volkoff limit ) would collapse into black holes for the reasons presented by Chandrasekhar, and concluded that no law of physics was likely to intervene and stop at least some stars from collapsing to black holes.

This process was helped by the discovery of pulsars in 1967, which, by 1969, were shown to be rapidly rotating neutron stars.

A nuclear chain reaction was proposed by Leó Szilárd in 1933, shortly after the neutron was discovered, but more than five years before nuclear fission was discovered.

In this reaction, a neutron plus a fissionable atom causes a fission resulting in a larger number of neutrons than the single one that was consumed in the initial reaction.

At the time, the multiple neutron absorption was thought to be an extremely rare process, but the identification of indicated that still more neutrons could have been captured by the uranium nuclei, thereby producing new elements heavier than californium.

Such multiple neutron absorption was made possible by the high neutron flux density during the detonation, so that newly generated heavy isotopes had plenty of available neutrons to absorb before they could disintegrate into lighter elements.

While people expected elements with higher atomic number to form from neutron bombardment of lighter elements, nobody expected neutrons to have enough energy to actually split a heavier atom into two light element fragments, and it was thought still more unlikely that slow neutrons could accomplish such a task.

Bohr grabbed him by the shoulder and said: “ Young man, let me explain to you about something new and exciting in physics .” It 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.

That was the " inner radiation belt " of protons with energies in the range 10-100 MeV ( megaelectronvolts ), attributed later to " albedo neutron decay ," a secondary effect of the interaction of cosmic radiation with the upper atmosphere.

The discovery, beginning with Rutherford's analysis of the data in 1911, eventually led to the Rutherford model of the atom, in which the atom has a very small, very dense nucleus containing most of its mass, and consisting of heavy positively charged particles with embedded electrons in order to balance out the charge ( since the neutron was unknown ).

In 1932 Chadwick realized that radiation that had been observed by Walther Bothe, Herbert L. Becker, Irène and Frédéric Joliot-Curie was actually due to a neutral particle of about the same mass as the proton, that he called the neutron ( following a suggestion about the need for such a particle, by Rutherford ).

The compact object that was created after the explosion lies in the center of the Crab Nebula and is a neutron star.

The word was coined by scientist Andreas von Antropoff in 1926 ( before the discovery of the neutron itself ) for the conjectured " element of atomic number zero " that he placed at the head of the periodic table.

After nuclear fission was discovered by others in 1938, Szilárd and Enrico Fermi in 1939 searched for, and discovered, neutron multiplication in uranium, proving that a nuclear chain reaction by this mechanism was indeed possible.

It is an effective neutron moderator and was used in James Chadwick's 1932 experiments to identify the neutron.

Neutron radiation was discovered with the neutron by Chadwick, in 1932.

The neutron initiator was of polonium-beryllium type and code-named Flower.

Because the core was surrounded by a good neutron reflector, at explosion it comprised almost 2. 5 critical masses.

Statistically, the probability of a neutron star being a quark star is low, so in the Milky Way Galaxy there will only be a small population of quark stars ( but, if it is correct that overdense neutron stars turn into quark stars, that makes the possible number of quark stars higher than was originally thought, as we would be looking for the wrong type of star ).

The Integral fast reactor ( IFR, originally Advanced Liquid-Metal Reactor ) is a design for a nuclear reactor using fast neutrons and no neutron moderator ( a " fast " reactor ).

Also at the high flux reactor, one of the neutron beam channels, which was originally installed for performing fundamental research, has been specially modified for the direct irradiation of patients.

Trainor had no choice but to provide his instrument, originally designed to study cosmic ray neutron albedo, to the U. S. government along with all its data bus specifications and complete documentation.

In 1933 he conceived the idea of neutron chain reaction, and filed for patents on it in 1934.

In the subsurface environment, it is also produced through neutron capture by or alpha emission by calcium.

Instead, the element is prepared, in milligram amounts, by the neutron irradiation of < sup > 226 </ sup > in a nuclear reactor.

The explanation for these different isotopes awaited the discovery of the neutron, a neutral-charged particle with a mass similar to the proton, by the physicist James Chadwick in 1932.

The same phenomenon results in extremely fast spin of compact stars ( like white dwarfs, neutron stars and black holes ) when they are formed out of much larger and slower rotating stars ( indeed, decreasing the size of object 10 < sup > 4 </ sup > times results in increase of its angular velocity by the factor 10 < sup > 8 </ sup >).

Thus, natural beryllium bombarded either by alphas or gammas from a suitable radioisotope is a key component of most radioisotope-powered nuclear reaction neutron sources for the laboratory production of free neutrons.

Until that time, neutron stars, like black holes, were regarded as just theoretical curiosities ; but the discovery of pulsars showed their physical relevance and spurred a further interest in all types of compact objects that might be formed by gravitational collapse.

Unlike cosmogenic isotopes that are produced in the atmosphere, < sup > 41 </ sup > Ca is produced by neutron activation of < sup > 40 </ sup > Ca.

Like white dwarfs these objects are extremely compact and are supported by degeneracy pressure, but a neutron star is so massive and compressed that electrons and protons have combined to form neutrons, and the star is thus supported by neutron degeneracy pressure instead of electron degeneracy pressure.

This property has been experimentally verified by showing that the charge of one helium nucleus ( two protons and two neutrons bound together in a nucleus and moving around at high speeds ) is the same as two deuterium nuclei ( one proton and one neutron bound together, but moving much more slowly than they would if they were in a helium nucleus ).

In 1938, Fermi received the Nobel Prize in Physics at the age of 37 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 FERMIAC, an analog device invented by Enrico Fermi to implement studies of neutron transport.