|Blast||50%||40% or as low as 30%|
|Thermal energy||35%||25% or as low as 20%|
|Instant radiation||5%||30% - 45%.|
A neutron bomb or officially known as one type of Enhanced Radiation Weapon is a low yield 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. The weapon's radiation case, usually made from relatively thick uranium, lead or steel in a standard bomb, are 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, closer to (14 MeV) than those released during a fission reaction (1–2 MeV). Technically speaking, all low yield nuclear weapons are radiation weapons, that is including the non-enhanced variant, from 0 up to about 10 kilotons in yield, all have prompt neutron radiation, as their most far reaching lethal component, after which point the lethal blast and thermal effects radius begins to out-range the lethal ionizing radiation radius. 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.
Conception of the neutron bomb is generally credited to Samuel T. Cohen of the Lawrence Livermore National Laboratory, who developed the concept in 1958. Testing was authorized and carried out in 1963 at an underground Nevada test facility. Development was subsequently postponed by President Jimmy Carter in 1978 following protests against his administration's plans to deploy neutron warheads to ground forces Europe. On November 17, 1978, the USSR detonated its first neutron 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, a campaign which gained immense popularity, with the new threat from the ”American capitalist machine”. 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.
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. The 1999 Cox Report indicates that China is able to produce neutron bombs, although no country is currently known to deploy them, 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 neutron bombs in actuality if not in name.
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. 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." However for those who truly "hold life cheap", chemical and biological weapons are far more effective at leaving property/"capital" undamaged and people dead, indeed although the US officially disbanded their BW program in 1972, the Soviet Union, despite also signing the Biological Weapons Convention in 1972, clandestinely continued the Soviet biological weapons program by reclassifying it as the civilian "Biopreparat", with offensive weaponization of pathogens continuing in that facility right up until the dissolution of the state in 1991.
Use of neutron bomb
Neutron bombs are purposely designed with explosive yields lower than other nuclear weapons. Since neutrons are absorbed by air, neutron radiation effects drop off very rapidly with distance in air, there is a sharper distinction, as opposed to thermal effects, between areas of high lethality and areas with minimal radiation doses. All high yield (more than ~10 kiloton) "neutron bombs", such as the extreme example of the 50 megaton Tsar Bomba, are not able to radiate sufficient neutrons beyond their lethal blast range when detonated as a surface burst or low altitude airburst and so are no longer classified as neutron bombs. As it is the intense pulse of high-energy neutrons that are generated by a neutron bomb that are intended as the principal killing mechanism, not the fallout, heat or blast.
- the W-70 ... is not even remotely a "neutron bomb." Instead of being the type of weapon that, in the popular mind, "kills people and spares buildings" it is one that both kills and physically destroys on a massive scale. The W-70 is not a discriminate weapon, like the neutron bomb — which, incidentally, should be considered a weapon that "kills enemy personnel while sparing the physical fabric of the attacked populace, and even the populace too."
Although neutron bombs are commonly believed to "leave the infrastructure intact", with current designs that have explosive yields in the low kiloton range, the detonation of which, in a built up area, would still cause considerable, although not total, destruction through blast and heat effects.
Neutron bombs could be used as strategic anti-ballistic missile weapons or as tactical weapons intended for use against armored forces. The neutron bomb was originally conceived by the U.S. military as a weapon that could stop massed Soviet armored divisions from overrunning allied nations without destroying the infrastructure of the allied nation. As the Warsaw Pact tank strength was over twice that of NATO, and Soviet Deep Battle doctrine was likely to be to use this numerical advantage to rapidly sweep across continental Europe if the Cold War ever turned hot, any weapon that could break up their intended mass tank formation deployments and force them to deploy their tanks in a thinner, more easily dividable manner, would aid ground forces in the task of hunting down solitary tanks and firing anti-tank missiles upon them, such as the contemporary M47 Dragon and BGM-71 TOW missiles.
Effects of a neutron bomb detonation
Upon detonation, a 1 kiloton neutron bomb would produce a large blast wave, and a powerful pulse of both thermal radiation and ionizing radiation, mostly in the form of fast (14.1 MeV) neutrons. The thermal pulse would cause third degree burns to unprotected skin out to approximately 500 meters. The blast would create at least 4.6 PSI out to a radius of 600 meters, which would severely damage all non-reinforced concrete structures. At this distance the blast would cause very few direct casualties as the human body is resistant to sheer overpressure, however, the powerful winds produced by this overpressure are capable of throwing human bodies into objects or throwing objects at high velocity, both with lethal results, rendering casualties highly dependent on surroundings. The pulse of neutron radiation would cause immediate and permanent incapacitation to unprotected humans in the open out to 900 meters, with death occurring in one or two days. The lethal dose would extend out past 1400 meters for those in the open, where approximately half of those exposed would die of radiation sickness after several weeks. However with humans residing within the aforementioned concrete buildings with walls thicker than 12 inches, or 24 inches of damp earth, the neutron radiation exposure would be reduced by a factor of 10.
Questionable effectiveness in modern anti-tank role
The questionable effectiveness of ER weapons against modern tanks is cited as one of the main reasons that these weapons are no longer fielded or stockpiled. With the increase in average tank armor thickness since the first ER weapons were fielded, tank armor protection approaches the level where tank crews are now almost completely protected from radiation effects. Therefore for an ER weapon to incapacitate a modern tank crew through irradiation, the weapon must now be detonated at such a close proximity to the tank that the nuclear explosion's blast would now be equally effective at incapacitating it and its crew. However this assertion was regarded as dubious in a reply in 1986  by a member of the Royal Military College of Science as neutron radiation from a 1 kiloton neutron bomb would incapacitate the crew of a tank with a Protection Factor of 35 out to a range of 280 meters, but the incapacitating blast range, depending on the exact weight of the tank, is much less, from 70 to 130 meters. However although the author did note that effective neutron absorbers and neutron poisons such as Boron carbide can be incorporated into conventional armor and strap on neutron moderating hydrogenous material (hydrogen atom containing substances), such as Explosive Reactive Armor can both increase the protection factor, the author holds that in practice the actual average total tank area protection factor is rarely higher than 15.5 to 35.
A composite high density concrete, or alternatively, a laminated Graded Z shield, 24 units thick of which 16 units are iron and 8 units are polyethylene containing boron (BPE) and additional mass behind it to attenuate neutron capture gamma rays is more effective than just 24 units of pure iron or BPE alone, due to the advantages of both iron and BPE in combination. Iron is effective in slowing down/scattering high-energy neutrons in the 14-MeV energy range and attenuating gamma rays, while the hydrogen in polyethylene is effective in slowing down these now slower fast neutrons in the few MeV range, and boron 10 has a high absorption cross section for thermal neutrons and a low production yield of gamma rays when it absorbs a neutron. The Soviet T72 tank, in response to the neutron bomb threat, is cited as having fitted a boronated, polyethylene liner.
The bombs require considerable maintenance for their capabilities, requiring some tritium for fusion boosting and tritium in the secondary stage (yielding more neutrons), in amounts on the order of a few tens of grams (10–30 grams estimated). Because tritium has a relatively short half-life of 12.32 years (after that time, half the tritium has decayed), it is necessary to replenish it periodically in order to keep the bomb effective. (For instance: to maintain a constant level of 24 grams of tritium in a warhead, about 1 gram per bomb per year must be supplied.) Moreover, tritium decays into helium-3, which absorbs neutrons and will thus further reduce the bomb's neutron yield.
Use against ballistic missiles
As an anti-ballistic missile weapon, the first fielded ER warhead, the W66, was developed for the Sprint missile system as part of the Safeguard Program to protect United States cities and missile silos from incoming Soviet warheads by damaging their electronic components with the intense neutron flux.
Use as an area denial weapon
In November 2012, a former British Labour defence minister (Lord Gilbert), suggested that enhanced radiation reduced blast (ERRB) warheads could be detonated in the mountain region of the Afghanistan/Pakistan border to prevent infiltration. He proposed to warn the inhabitants to evacuate, then irradiate the area, making it unusable and impassible. Used in this manner, the neutron bomb(s), regardless of burst height, would release neutron activated casing materials used in the bomb, and depending on burst height, create radioactive soil activation products.
In much the same fashion as the area denial effect resulting from fission product (the substances that make up the majority of fallout) contamination in an area following a conventional surface burst nuclear explosion, as advocated in the Korean War by Douglas MacArthur, it would thus be a form of Radiological warfare. With the difference with that of neutron bombs producing 1/2, or less, of the quantity of fission products when compared to the same yield pure fission bomb. Radiological warfare with neutron bombs that rely on fission primaries would therefore still produce fission fallout, albeit a comparatively "cleaner" and shorter lasting version of it in the area if airbursts were utilized, as little to no fission products would be deposited on the direct immediate area, instead becoming diluted global fallout.
However the most effective use of a neutron bomb with respect to area denial would be to encase it in a thick shell of material that could be neutron activated, and use a surface burst. In this manner the neutron bomb would be turned into a "salted bomb", a case of Zinc-64 for example would probably be the most attractive from a military point of view, as when activated the Zinc-65 that is created is a gamma emitter, with a half life of 244 days.
- Neutron activation
- Neutron transport
- Nuclear fallout
- Nuclear strategy
- Nuclear warfare
- Nuclear weapon design
- "CHAPTER 2 CONVENTIONAL AND NUCLEAR WEAPONS - ENERGY PRODUCTION AND ATOMIC PHYSICS SECTION I - GENERAL. Figure 2-IX".
- "The Neutron Bomb".
- Kistiakovsky, George (Sep 1978). "The folly of the neutron bomb". Bulletin of the Atomic Scientists 34: 27. Retrieved 11 February 2011.
- Hafemeister, David W. (2007). Physics of societal issues: calculations on national security, environment, and energy. Springer. p. 18. ISBN 978-0-387-95560-5.
- "CHAPTER 2 CONVENTIONAL AND NUCLEAR WEAPONS - ENERGY PRODUCTION AND ATOMIC PHYSICS SECTION I - GENERAL. Table 2-III".
- "Mock up". Remm.nlm.gov. Retrieved 2013-11-30.
- "Range of weapons effects". Johnstonsarchive.net. Retrieved 2013-11-30.
- "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". Webofstories.com. Retrieved 2013-11-30.
- Robert D. McFadden (December 1, 2010). "Samuel T. Cohen, Neutron Bomb Inventor, Dies at 89". The New York Times. Retrieved 2010-12-02. "After the war, he joined the RAND Corporation and in 1958 designed the neutron bomb as a way to strike a cluster of enemy forces while sparing infrastructure and distant civilian populations."
- "About: Chemistry article", by Anne Marie Helmenstine, Ph. D
- "On this Day: 7 April". BBC. 1978-04-07. Retrieved 2010-07-02. "Jimmy Carter's successor, Ronald Reagan, changed US policy and gave the order for the production of neutron warheads to start in 1981. ..."
- "The Soviet neutron bomb at 30. March 07 2010. RT".
- "Nuclear Weapon News and Background". Archived from the original on 2007-09-29. Retrieved 2012-10-11.
- Christopher Ruddy (June 15, 1997). "Bomb inventor says U.S. defenses suffer because of politics". Tribune-Review. Retrieved 2010-07-03. "With the fall of the Berlin Wall and the end of communism as we knew it, the Bush administration moved to dismantle all of our tactical nuclear weapons, including the Reagan stockpile of neutron bombs. In Cohen's mind, America was brought back to Square One. Without tactical weapons like the neutron bomb, America would be left with two choices if an enemy was winning a conventional war: surrender, or unleash the holocaust of strategic nuclear weapons."
- "Types of Nuclear Weapons". Nuclearweaponarchive.org. Retrieved 2012-10-12.
- John Pike. "March 13, 1996". Globalsecurity.org. Retrieved 2012-10-12.
- "National Nuclear Security Administration - Homepage". Nnsa.doe.gov. Retrieved 2012-10-12.
- "Neutron bomb: Why 'clean' is deadly". BBC News. 1999-07-15. Retrieved 2012-10-12.
- UK parliamentary question on whether condemnation was considered by Thatcher government 
- U.S. National Security and Military/Commercial Concerns with the People's Republic of China 
- The Nuclear Express: A Political History of the Bomb and Its Proliferation, By Thomas C. Reed, Danny B. Stillman (2010), page 181
- The Nuclear Express: A Political History of the Bomb and Its Proliferation, By Thomas C. Reed, Danny B. Stillman (2010), page 177
- Wittner, Lawrence S. (2009). Confronting the bomb: a short history of the world nuclear disarmament movement. Stanford University Press. pp. 132–133. ISBN 978-0-8047-5632-7.
- Auten, Brian J. (2008). Carter's conversion: the hardening of American defense policy. University of Missouri Press. p. 134. ISBN 978-0-8262-1816-2.
- National security for a new era: globalization and geopolitics after Iraq, Donald Snow
- Herken, Greff (2003). Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller. Macmillan. p. 332. ISBN 978-0-8050-6589-3.
- Asimov, Isaac. The New Intelligent Man's Guide to Science. Basic Books, New York, 1965. Page 410.
- Alibek,K. and S. Handelman. Biohazard: The Chilling True Story of the Largest Covert Biological Weapons Program in the World - Told from Inside by the Man Who Ran it. 1999. Delta (2000) ISBN 0-385-33496-6
- "List of All U.S. Nuclear Weapons". Nuclearweaponarchive.org. 2006-10-14. Retrieved 2012-10-12.
- Muller, Richard A. (2009). Physics for Future Presidents: The Science Behind the Headlines. W.W. Norton & Company. p. 148. ISBN 978-0-393-33711-2.
- "what is a neutron bomb "In strategic terms, the neutron bomb has a theoretical deterrent effect: discouraging an armoured ground assault by arousing the fear of neutron bomb counterattack"".
- Calculated from http://nuclearweaponarchive.org/Nwfaq/Nfaq5.html assuming 0.5 kt combined blast and thermal
- "1) Effects of blast pressure on the human body" (PDF). Retrieved 2012-10-12.
- "Field manual 3-4 chapter 4".
- "Applications of the Monte Carlo Adjoint Shielding Methodology - MIT".
- New Scientist March 13, 1986 pg 45. Books.google.com. 1986-03-13. Retrieved 2012-10-12.
- New Scientist June 12, 1986 pg 62.
- http://web.ead.anl.gov/uranium/pdf/ducretecosteffec.pdf Paper Summary Submitted to Spectrum 2000, Sept 24-28, 2000, Chattanooga, TN DUCRETE: A Cost Effective Radiation Shielding Material. Quote- "The Ducrete/DUAGG replaces the conventional aggregate in concrete producing concrete with a density of 5.6 to 6.4 g/cm3 (compared to 2.3 g/cm3 for conventional concrete). This shielding material has the unique feature of having both high Z and low Z elements in a single matrix. Consequently, it is very effective for the attenuation of gamma and neutron radiation..."}}
- M. J. Haire and S. Y. Lobach, "Cask size and weight reduction through the use of depleted uranium dioxide (DUO2)-concrete material", Waste Management 2006 Conference,Tucson, Arizona, February 26–March 2, 2006.
- "Monte Carlo Calculations Using MCNP4B for an Optimal Shielding Design of a 14-MeV Neutron Source, Submitted to the Journal of Radiation Protection Dosimetry 1998".
- "Neutron Interactions – Part 2 George Starkschall, Ph.D. Department of Radiation Physics.".
- "22.55 "Principles of Radiation Interactions"".
- "THE PREPARATION OF POLYETHYLENE AND MINERAL MATERIAL COMPOSITES, AND EXPERIMENTAL AND THEORETICAL (USING MCNP CODE) VERIFICATION OF THEIR CHARACTERISTICS FOR NEUTRON BEAM ATTENUATION".
- "What is a neutron bomb".
- Terror Reigns Again By Ronan Strobing. pg 418.
- Kalinowski, Martin (2004). International control of tritium for nuclear nonproliferation and disarmament. CRC Press. p. 10. ISBN 978-0-415-31615-6.
- Zerriffi, Hisham (January 1996). "Tritium: The environmental, health, budgetary, and strategic effects of the Department of Energy's decision to produce tritium". Institute for Energy and Environmental Research.
- After 12.32 years, half the 24g has decayed and thus about 12g is missing: to replenish these 12g during the 12 years they decayed, adding about 1g per year is needed.
- When absorbing neutrons, helium-3 produces back some tritium, but it comes too late in the reaction for fusion boosting and doesn't compensate for the decayed tritium missing at the start of the reaction.
- "Huffington Post". Retrieved 2012-11-27.
- "Lord Gilbert obituary, by Andrew Roth, 3 June 2013. "Nobody lives up in the mountains on the border between Afghanistan and Pakistan except for a few goats and a handful of people herding them," he observed. "If you told them that some ... warheads were going to be dropped there and that it would be a very unpleasant place to go, they would not go there."".
- "1.6 Cobalt Bombs and other Salted Bombs, Nuclear Weapons Archive, Carey Sublette.".
- Cohen, Sam, The Truth About the Neutron Bomb: The Inventor of the Bomb Speaks Out, William Morrow & Co., 1983, ISBN 0-688-01646-4
- Cohen, Sam, F*** You! Mr. President: Confessions of the Father of the Neutron Bomb, Xlibris Corporation, 2000
- Strategic Implications of Enhanced Radiation Weapons
- Nuclear Files.org Definition and history of the neutron bomb
- Creator of Neutron Bomb Leaves an Explosive Legacy