Editing Neutron bomb (section)

===Effectiveness in modern anti-tank role===
{{see also|Centurion Tank#Nuclear tests|Object 279|Signs and symptoms of radiation poisoning#"Walking Ghost phase"}}
[[File:Neutroncrosssectionboron.png|thumb|The [[neutron cross section]] and absorption probability in [[Barn (unit)|barns]] of the two natural [[boron]] isotopes found in nature (top curve is for 10&nbsp;B and bottom curve for 11&nbsp;B. As neutron energy increases to 14&nbsp;MeV, the absorption effectiveness, in general, decreases. Thus, for boron-containing armor to be effective, fast neutrons must first be slowed by another element by [[neutron scattering]].]]

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 [[Nuclear stockpile|stockpiled]]. With the increase in average tank armor thickness since the first ER weapons were fielded, it was argued in the March 13, 1986, ''New Scientist'' magazine that tank armor protection was approaching the level where tank crews would be almost fully protected from radiation effects. Thus, for an ER weapon to incapacitate a modern tank crew through irradiation, the weapon must be detonated at such proximity to the tank that the [[nuclear explosion]]'s blast would now be equally effective at incapacitating it and its crew.<ref>{{cite book |url=https://books.google.com/books?id=mYVNkaEJpz4C&q=%22main+battle+tank%22&pg=PA47 |title=New Scientist March 13, 1986 pg 45 |date=1986-03-13 |access-date=2012-10-12 |last1=Information |first1=Reed Business }}{{Dead link|date=November 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

However, although the author did note that effective [[Neutron radiation#Health hazards and protection|neutron absorbers]] and [[neutron poison]]s such as [[boron carbide]] can be incorporated into conventional armor and strap-on [[neutron moderator|neutron moderating]] hydrogenous material (substances containing hydrogen atoms), such as explosive [[reactive armor]], increasing the protection factor, the author holds that in practice, combined with [[neutron scattering]], the actual average total tank area protection factor is rarely higher than 15.5 to 35.<ref>{{cite book|url=https://books.google.com/books?id=RYH7o-4ykmMC&pg=PA62|title=New Scientist June 12, 1986 pg 62|last1=Information|first1=Reed Business|date=1986-06-12}}{{Dead link|date=November 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> According to the [[Federation of American Scientists]], the neutron protection factor of a "tank" can be as low as 2,<ref name="fas.org" /> without qualifying whether the statement implies a [[light tank]], [[medium tank]], or [[main battle tank]].

A composite [[Types of concrete#High-performance concrete|high-density concrete]], or alternatively, a laminated [[Radiation protection#Radiation protection|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. During [[neutron transport]], 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.<ref>{{cite web |url=https://www.slac.stanford.edu/pubs/slacpubs/7750/slac-pub-7785.pdf |title=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 |url-status=live |archive-url=https://web.archive.org/web/20160305193733/https://www.slac.stanford.edu/pubs/slacpubs/7750/slac-pub-7785.pdf |archive-date=2016-03-05 }}</ref><ref>{{cite web |url=http://www.uthgsbsmedphys.org/gs02-0093/3.3b-neutroninteractions.pdf |title=Neutron Interactions – Part 2 George Starkschall, Ph.D. Department of Radiation Physics |url-status=dead |archive-url=https://web.archive.org/web/20150717162239/http://www.uthgsbsmedphys.org/gs02-0093/3.3b-neutroninteractions.pdf |archive-date=2015-07-17 |access-date=2014-03-02 }}</ref><ref>{{cite web |url=http://ocw.mit.edu/courses/nuclear-engineering/22-55j-principles-of-radiation-interactions-fall-2004/lecture-notes/ener_depo_neutro.pdf |title=22.55 "Principles of Radiation Interactions" |url-status=live |archive-url=https://web.archive.org/web/20150717104916/http://ocw.mit.edu/courses/nuclear-engineering/22-55j-principles-of-radiation-interactions-fall-2004/lecture-notes/ener_depo_neutro.pdf |archive-date=2015-07-17 }}</ref> The Soviet [[T-72]] tank, in response to the neutron bomb threat, is cited as having fitted a boronated<ref>{{cite web |url=http://www.manuelsweb.com/neutronbomb.htm |title=What is a neutron bomb |url-status=dead |archive-url=https://web.archive.org/web/20060113000504/http://www.manuelsweb.com/neutronbomb.htm |archive-date=2006-01-13 |access-date=2005-12-21 }}</ref> polyethylene liner, which has had its neutron shielding properties simulated.<ref name="web.mit.edu"/><ref>{{cite book |url=https://books.google.com/books?id=bGWYl-ugjPgC&q=t72+tank+boron+neutron&pg=PA418 |title=Terror Reigns Again By Ronan Strobing. pg 418|isbn=9780955855771|last1=Strobing|first1=Ronan|date=Jul 2009|publisher=ShieldCrest }}</ref>

[[File:Neutron radiation weighting factor as a function of kinetic energy.gif|thumb|upright=1.35|The [[Relative biological effectiveness|radiation weighting factor]] for neutrons of various energy has been revised over time and certain agencies have different weighting factors; however, despite the variation amongst the agencies, from the graph, for a given energy, a [[fusion neutron]] (14.1&nbsp;MeV) although more energetic, is less biologically harmful as rated in [[Sievert]]s, than a fission-generated thermal neutron or a fusion neutron slowed to that energy, c.&nbsp;0.8&nbsp;MeV.]]
However, some tank armor material contains [[depleted uranium]] (DU), common in the US's [[M1A1 Abrams]] tank, which incorporates steel-encased depleted uranium armor,<ref>{{cite web |url=http://www.army-technology.com/projects/abrams |title=M1A1/2 Abrams Main Battle Tank, United States of America |url-status=live |archive-url=https://web.archive.org/web/20140810045337/http://www.army-technology.com/projects/abrams |archive-date=2014-08-10 }}</ref> a substance that will fast fission when it [[neutron capture|captures]] a fast, fusion-generated neutron, and thus on fissioning will produce [[thermal neutrons|fission neutrons]] and [[fission product]]s embedded within the armor, products which emit, among other things, penetrating gamma rays. Although the neutrons emitted by the neutron bomb may not penetrate to the tank crew in lethal quantities, the fast fission of DU within the armor could still ensure a lethal environment for the crew and maintenance personnel by fission neutron and gamma ray exposure{{dubious|date=April 2017}},<ref>{{cite web|url=http://chemistry.about.com/od/chemistryfaqs/f/neutronbomb.htm|title=For example, M-1 tank armor includes depleted uranium, which can undergo fast fission and can be made to be radioactive when bombarded with neutrons|url-status=dead|archive-url=https://web.archive.org/web/20110105165334/http://chemistry.about.com/od/chemistryfaqs/f/neutronbomb.htm|archive-date=2011-01-05|access-date=2007-04-20}}</ref>{{Unreliable source?|date=April 2017}} largely depending on the exact thickness and elemental composition of the armor—information usually hard to attain. Despite this, [[Ducrete]]—which has an elemental composition similar (but not identical) to the ceramic [[Chobham Armour#Heavy metal modules|second-generation heavy metal Chobham armor]] of the Abrams tank—is an effective radiation shield, to both ''fission'' neutrons and gamma rays due to it being a graded-Z material.<ref>{{cite web |url=http://web.ead.anl.gov/uranium/pdf/ducretecosteffec.pdf |title=Archived copy |access-date=2011-11-29 |url-status=dead |archive-url=https://web.archive.org/web/20111019052835/http://web.ead.anl.gov/uranium/pdf/ducretecosteffec.pdf |archive-date=2011-10-19 }} 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&nbsp;g/cm3 (compared to 2.3&nbsp;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&nbsp;..."</ref><ref>M. J. Haire and S. Y. Lobach, [http://www.ornl.gov/~webworks/cppr/y2001/pres/124687.pdf "Cask size and weight reduction through the use of depleted uranium dioxide (DUO<sub>2</sub>)-concrete material"] {{webarchive|url=https://web.archive.org/web/20120926214404/http://www.ornl.gov/~webworks/cppr/y2001/pres/124687.pdf |date=2012-09-26 }}, Waste Management 2006 Conference, Tucson, Arizona, February 26–March 2, 2006.</ref> Uranium, being about twice as dense as lead, is thus nearly twice as effective at shielding gamma ray radiation per unit thickness.<ref>{{cite web |url=https://www.nde-ed.org/EducationResources/CommunityCollege/RadiationSafety/safe_use/shielding.htm |title=Half-Value Layer (Shielding) |url-status=dead |archive-url=https://web.archive.org/web/20140811021451/https://www.nde-ed.org/EducationResources/CommunityCollege/RadiationSafety/safe_use/shielding.htm |archive-date=2014-08-11 |access-date=2014-08-09 }}</ref>