Trinity (nuclear test) in the context of "Plutonium"

The neutron is a subatomic particle, symbol n or n
, that has no electric charge, and a mass slightly greater than that of a proton. The neutron was discovered by James Chadwick in 1932, leading to the discovery of nuclear fission in 1938, the first self-sustaining nuclear reactor (Chicago Pile-1, 1942), and the first nuclear weapon (Trinity, 1945).

Neutrons are found, together with a similar number of protons in the nuclei of atoms. Atoms of a chemical element that differ only in neutron number are called isotopes. Free neutrons are produced copiously in nuclear fission and fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes. Neutron stars, formed from massive collapsing stars, consist of neutrons at the density of atomic nuclei but a total mass more than the Sun.

The Potsdam Conference (German: Potsdamer Konferenz) was held at Potsdam in the Soviet occupation zone from 17 July to 2 August 1945, to allow the three leading Allies to plan the postwar peace, while avoiding the mistakes of the Paris Peace Conference of 1919. The participants were the Soviet Union, the United Kingdom, and the United States. They were represented respectively by General Secretary Joseph Stalin, prime ministers Winston Churchill and Clement Attlee, and President Harry S. Truman. They gathered to decide how to administer Germany, which had agreed to an unconditional surrender nine weeks earlier. The goals of the conference also included establishing the postwar order, solving issues on the peace treaty, and countering the effects of the war.

The foreign ministers and aides played key roles: Vyacheslav Molotov, Anthony Eden and Ernest Bevin, and James F. Byrnes. From 17 July to 25 July, nine meetings were held, when the Conference was interrupted for two days, as the results of the British general election were announced. By 28 July, Attlee had defeated Churchill and replaced him as Britain's representative, with Britain's new Secretary of State for Foreign Affairs, Ernest Bevin, replacing Anthony Eden. Four days of further discussion followed. During the conference, there were meetings of the three heads of government with their foreign secretaries, as well as meetings of only the foreign secretaries. Committees that were appointed by the latter for precursory consideration of questions before the conference also met daily. During the Conference, Truman was secretly informed that the Trinity test of the first atomic bomb on 16 July had been successful. He hinted to Stalin that the U.S. was about to use a new kind of weapon against the Japanese. Though this was the first time the Soviets had been officially given information about the atomic bomb, Stalin was already aware of the bomb project, having learned about it through espionage long before.

The Atomic Age, also known as the Atomic Era, is the period of history following the detonation of the first nuclear weapon, The Gadget at the Trinity test in New Mexico on 16 July 1945 during World War II. Although nuclear chain reactions had been hypothesized in 1933 and the first artificial self-sustaining nuclear chain reaction (Chicago Pile-1) had taken place in December 1942, the Trinity test and the ensuing bombings of Hiroshima and Nagasaki that ended World War II represented the first large-scale use of nuclear technology and ushered in profound changes in sociopolitical thinking and the course of technological development.

While atomic power was promoted for a time as the epitome of progress and modernity, entering into the nuclear power era also entailed frightful implications of nuclear warfare, the Cold War, mutual assured destruction, nuclear proliferation, the risk of nuclear disaster (potentially as extreme as anthropogenic global nuclear winter), as well as beneficial civilian applications in nuclear medicine. It is no easy matter to fully segregate peaceful uses of nuclear technology from military or terrorist uses (such as the fabrication of dirty bombs from radioactive waste), which complicated the development of a global nuclear-power export industry right from the outset.

A neutron is a subatomic particle, symbol n or n
, that has no electric charge, and a mass slightly greater than that of a proton. The neutron was discovered by James Chadwick in 1932, leading to the discovery of nuclear fission in 1938, the first self-sustaining nuclear reactor (Chicago Pile-1, 1942), and the first nuclear weapon (Trinity, 1945).

Neutrons are found, together with a similar number of protons in the nuclei of atoms. Atoms of a chemical element that differ only in neutron number are called isotopes. Free neutrons are produced copiously in nuclear fission and fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes. Neutron stars, formed from massive collapsing stars, consist of neutrons at the density of atomic nuclei but a total mass more than the Sun.

Nuclear weapons design means the physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types:

1. Pure fission weapons are the simplest, least technically demanding, were the first nuclear weapons built, and so far the only type ever used in warfare, by the United States on Japan in World War II.
2. Boosted fission weapons are fission weapons that use nuclear fusion reactions to generate high-energy neutrons that accelerate the fission chain reaction and increase its efficiency. Boosting can more than double the weapon's fission energy yield.
3. Staged thermonuclear weapons are arrangements of two or more "stages", most usually two, where the weapon derives a significant fraction of its energy from nuclear fusion (as well as, usually, nuclear fission). The first stage is typically a boosted fission weapon (except for the earliest thermonuclear weapons, which used a pure fission weapon). Its detonation causes it to shine intensely with X-rays, which illuminate and implode the second stage filled with fusion fuel. This initiates a sequence of events which results in a thermonuclear, or fusion, burn. This process affords potential yields hundreds or thousands of times greater than those of fission weapons.

Pure fission weapons have been the first type to be built by new nuclear powers. Large industrial states with well-developed nuclear arsenals have two-stage thermonuclear weapons, which are the most compact, scalable, and cost effective option, once the necessary technical base and industrial infrastructure are built.

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 United Kingdom, initiated the Manhattan Project the following year to build a weapon using nuclear fission. The project also involved Canada. In August 1945, the atomic bombings of Hiroshima and Nagasaki were conducted by the United States, with British consent, against Japan at the close of that war, standing to date as the only use of nuclear weapons in hostilities.

The Soviet Union started development shortly after with their own atomic bomb project, and not long after, both countries were developing even more powerful fusion weapons known as hydrogen bombs. Britain and France built their own systems in the 1950s, and the number of states with nuclear capabilities has gradually grown larger in the decades since.

The Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT, is an international treaty, the objective of which is to prevent the spread of nuclear weapons and weapons technology, to promote cooperation in the peaceful uses of nuclear energy, and to further the goal of achieving nuclear disarmament and general and complete disarmament. Between 1965 and 1968, the treaty was negotiated by the Eighteen Nation Committee on Disarmament, a United Nations-sponsored organization based in Geneva, Switzerland.

Opened for signature in 1968, the treaty entered into force in 1970. As required by the text, after twenty-five years, NPT parties met in May 1995 and agreed to extend the treaty indefinitely. The treaty defines nuclear-weapon states as those that have built and tested a nuclear explosive device before 1967; these are the United States (1945), Russia (1949), the United Kingdom (1952), France (1960), and China (1964).