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A neutron bomb, officially known as one type of Enhanced Radiation Weapon (ERW), is a low yield thermonuclear weapon 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. The neutron bomb was to be used as a tactical nuclear weapon intended for use against armored forces. Originally conceived by the U.S. military, their design goals were to stop massed Soviet armored divisions from overrunning allied nations without destroying the infrastructure of the allied nation. However, it was later found that they achieved poor results in both categories. The weapon's radiation case, usually made from relatively thick uranium, lead or steel in a standard bomb, is, instead, made of as thin a material as possible, to facilitate the greatest escape of fusion-produced neutrons. The "usual" nuclear weapon yield—expressed as kilotons of TNT equivalent—is not a measure of a neutron weapon's destructive power. It refers only to the energy released (mostly heat and blast), and does not express the lethal effect of neutron radiation on living organisms. Compared to a pure fission bomb with an identical explosive yield, a neutron bomb would emit about ten times the amount of neutron radiation. In a fission bomb, at sea level, the total radiation pulse energy which is composed of both gamma rays and neutrons is approximately 5% of the entire energy released; in the neutron bomb it would be closer to 40%. Furthermore, the neutrons emitted by a neutron bomb have a much higher average energy level (close to 14 MeV) than those released during a fission reaction (1–2 MeV). Technically speaking, all low yield nuclear weapons are radiation weapons, including non-enhanced variants. Up to about 10 kilotons in yield, all nuclear weapons have prompt neutron radiation as their furthest-reaching lethal component, after which point the lethal blast and thermal effects radius begins to out-range the lethal ionizing radiation radius.〔(【引用サイトリンク】title=Mock up )〕〔(【引用サイトリンク】title=Range of weapons effects )〕〔(【引用サイトリンク】title=Weapon designer Robert Christy discussing scaling laws, that is, how injuries from ionizing radiation do not linearly scale in lock step with the range of thermal flash injuries, especially as higher and higher yield nuclear weapons are used )〕 Enhanced radiation weapons also fall into this same yield range and simply enhance the intensity and range of the neutron dose for a given yield. ==History and deployment to present== Conception of the neutron bomb is generally credited to Samuel T. Cohen of the Lawrence Livermore National Laboratory, who developed the concept in 1958. Initial development was carried out as part of projects DOVE and STARLING, and an early device was tested underground in early 1962. Designs of a "weaponized" version were carried out in 1963.〔〔"(About: Chemistry article )", by Anne Marie Helmenstine, Ph. D〕 Development of two production designs for the Army's MGM-52 Lance short-range missile began in July 1964, the W63 at Livermore and the W64 at Los Alamos. Both entered Phase 3 testing in July 1964, and the W64 was cancelled in favor of the W63 in September 1964. The W63 was in turn cancelled in November 1965 in favor of the W70 (Mod 0), a conventional design. By this time, the same concepts were being used to develop warheads for the Sprint missile, an anti-ballistic missile (ABM), with Livermore designing the W65 and Los Alamos the W66. Both entered Phase 3 testing in October 1965, but the W65 was cancelled in favor of the W66 in November 1968. Testing of the W66 was carried out in the late 1960s, and entered production in June 1974,〔 the first neutron bomb to do so. Approximately 120 were built, with about 70 of these being on active duty during 1975 and 1976 as part of the Safeguard Program. When that program was shut down they were placed in storage, and eventually decommissioned in the early 1980s.〔 Development of ER warheads for Lance continued, but in the early 1970s attention had turned to using modified versions of the W70, the W70 Mod 3.〔 Development was subsequently postponed by President Jimmy Carter in 1978 following protests against his administration's plans to deploy neutron warheads to ground forces in Europe. On November 17, 1978, in a test the USSR detonated its first similar-type bomb. President Ronald Reagan restarted production in 1981.〔 The Soviet Union began a propaganda campaign against the US's neutron bomb in 1981 following Reagan's announcement. In 1983 Reagan then announced the Strategic Defense Initiative, which surpassed neutron bomb production in ambition and vision and with that the neutron bomb quickly faded from the center of the public's attention.〔 Three types of enhanced radiation weapons (ERW) were built by the United States. The W66 warhead, for the anti-ICBM Sprint missile system, was deployed in 1975 and retired the next year, along with the missile system. The W70 Mod 3 warhead was developed for the short-range, tactical Lance missile, and the W79 Mod 0 was developed for artillery shells. The latter two types were retired by President George H. W. Bush in 1992, following the end of the Cold War. The last W70 Mod 3 warhead was dismantled in 1996, and the last W79 Mod 0 was dismantled by 2003, when the dismantling of all W79 variants was completed. According to the Cox Report, as of 1999 the United States had never deployed a neutron weapon. The nature of this statement is not clear; it reads "The stolen information also includes classified design information for an enhanced radiation weapon (commonly known as the "neutron bomb"), which neither the United States, nor any other nation, has ever deployed." However, the fact that neutron bombs had been produced by the US was well known at this time and part of the public record. Sam Cohen suggests the report is playing with the definitions; the US bombs were never deployed ''to Europe'', they remained stockpiled in the US. In addition to the two superpowers, France and China are known to have tested neutron or enhanced radiation bombs. France conducted an early test of the technology in 1967 and tested an "actual" neutron bomb in 1980.〔UK parliamentary question on whether condemnation was considered by Thatcher government ()〕 China conducted a successful test of neutron bomb principles in 1984 and a successful test of a neutron bomb in 1988. However, neither of those countries chose to deploy the neutron bomb. Chinese nuclear scientists stated prior to the 1988 test that China had no need for the neutron bomb, but it was developed to serve as a "technology reserve," in case the need arose in the future. Although no country is currently known to deploy them in an offensive manner, all thermonuclear dial-a-yield warheads that have about 10 kiloton and lower as one dial option, with a considerable fraction of that yield derived from fusion reactions, can be considered capable of being neutron bombs in actuality if not in name. The only country definitively known to deploy dedicated (that is, not dial-a-yield) neutron warheads for any length of time is Russia, which inherited the USSR's neutron warhead equipped ABM-3 Gazelle missile program. This anti-ballistic missile (ABM) system contains at least 68 neutron warheads with a 10 kiloton yield each and it has been in service since 1995, with inert missile testing approximately every other year since then (2014). The system is designed to destroy incoming "endo-atmospheric" level nuclear warheads aimed at Moscow and other targets and is the lower-tier/last umbrella of the A-135 anti-ballistic missile system (NATO reporting name: ABM-3).〔http://www.globalsecurity.org/wmd/world/russia/gazelle.htm〕 By 1984, according to Mordechai Vanunu, Israel was mass-producing neutron bombs.〔''The Nuclear Express: A Political History of the Bomb and Its Proliferation'', By Thomas C. Reed, Danny B. Stillman (2010), page 181〕 A number of analysts believe that the Vela incident was an Israeli neutron bomb experiment.〔''The Nuclear Express: A Political History of the Bomb and Its Proliferation'', By Thomas C. Reed, Danny B. Stillman (2010), page 177〕 Considerable controversy arose in the U.S. and Western Europe following a June 1977 ''Washington Post'' exposé describing U.S. government plans to purchase the bomb. The article focused on the fact that it was the first weapon specifically intended to kill humans with radiation. 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.〔(National security for a new era: globalization and geopolitics after Iraq ), Donald Snow〕 Science fiction author Isaac Asimov also stated that "Such a neutron bomb or N bomb seems desirable to those who worry about property and hold life cheap."〔Asimov, Isaac. The New Intelligent Man's Guide to Science. Basic Books, New York, 1965. Page 410.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「neutron bomb」の詳細全文を読む スポンサード リンク
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