Samuel T. Cohen

For the composer, see Samuel Cohen (composer).

Samuel T. Cohen is a physicist who is known for inventing the W70 warhead, the "enhanced neutron weapon" or neutron bomb, the blueprints of which were allegedly stolen by the Chinese [1]. He got his physics PhD from UCLA. In 1944 he worked on the Manhattan project with calculating how neutrons behaved in Fat Man. At RAND Corporation in 1950, his calculations of the intensity of radiation from fallout were included as a special appendix in Samuel Glasstone's book The Effects of Atomic Weapons. In the Vietnam War, Cohen argued that using small neutron bombs would end the war quickly and save many American lives, but politicians were not amenable to his ideas. He was a member of the Los Alamos Tactical Nuclear Weapons Panel in the early 1970s. President Carter delayed the neutron bomb in 1978 [2], but during Reagan's presidency, Cohen claims to have convinced Reagan to make 700 neutron bombs, 350 shells to go into the 8 inch (200-millimetre) howitzer and 350 W70 warheads for the Lance missile [3]. Cohen's backing of investigations into these controversial ideas won him some media attention after many years of being ignored [4]. In 1992 he was featured on the award-winning BBC TV series Pandora's Box episode, To the Brink of Eternity, discussing his battles with officialdom and colleagues at the RAND Corporation.

'Clean' nuclear tests and Cohen's revolutionary invention

In 1956, President Eisenhower announced the testing of a 95% 'clean' (2-stage) fusion weapon, later identified to have been the 11 July Navajo test at Bikini Atoll during Operation Redwing. This weapon had a 4.5 megatons yield. Previous 'dirty' weapons had fission proportions of 50-77%, due to the use of uranium-238 as a 'pusher' around the lithium deuteride (secondary) stage. (The fusion neutrons have energies of up to 14.1 MeV, well exceeding the 1.1 MeV 'fission threshold' for U-238.) The 1956 'clean' tests used a lead pusher, while in 1958 a tungsten carbide pusher was employed. Hans A. Bethe supported clean nuclear weapons in 1958 as Chairman of a Presidential science advisory group on nuclear testing [5]:

"... certain hard targets require ground bursts, such as airfield runways if it is desired to make a crater, railroad yards if severe destruction of tracks is to be accomplished... The use of clean weapons in strategic situations may be indicated in order to protect the local population." (Dr Hans Bethe, 27 March 1958 Top Secret - Restricted Data Report to the NSC Ad Hoc Working Group on the Technical Feasibility of a Cessation of Nuclear Testing (Bethe was the Working Group Chairman, page 9).

In consequence of Bethe's recommendations, on 12 July 1958, the Hardtack-Poplar shot on a barge in the lagoon yielded 9.3 megatons, of which only 4.8% was fission. It was 95.2% clean. It was the clean Mk-41C warhead.

Cohen in 1958 investigated a low-yield 'clean' nuclear weapon and discovered that the 'clean' bomb case thickness scales as the cube-root of yield. So a larger percentage of neutrons escapes from a small detonation, due to the thinner case required to reflect back X-rays during the secondard stage (fusion) ignition. For example, a 1-kiloton bomb would need to have a case only 1/10th the thickness of that for 1-megaton [6].

This means that although most of the neutrons are absorbed by the outer casing in a 1-megaton bomb, in a 1-kiloton bomb they would mostly escape. A neutron bomb is only feasible if the yield is sufficiently high that efficient fusion stage ignition is possible, and if the yield is low enough that the case thickness will not absorb too many neutrons. This means that neutron bombs have a yield range of 1-10 kilotons, with fission proportion varying from 50% at 1-kiloton to 25% at 10-kilotons (all of which comes from the primary stage). The neutron output per kiloton is then approximately 10-15 times greater than for a pure fission implosion weapon or a standard (high yield) strategic warhead like a W87 or W88 [7].

Official U.S. Department of Defense manual on the neutron bomb

Cohen's neutron bomb is not mentioned in the unclassified manual by Glasstone and Dolan, The Effects of Nuclear Weapons 1957-77, but is included as an 'enhanced neutron weapon' in chapter 5 of the declassified (formerly secret) manual edited by Philip J. Dolan, Capabilities of Nuclear Weapons, U.S. Department of Defence, effects manual DNA-EM-1, updated 1981 (U.S. Freedom of Information Act).

Provided that the weapon was not used in a thunderstorm, no fallout effects would occur from the use of a neutron bomb according to that manual, as the combination of 500 m burst altitude and low yield prevents fallout in addition to significant thermal and blast effects. The reduction in damage outside the target area is a major advantage of such a weapon to deter massed tank invasions. An aggressor would thus be forced to disperse tanks, which would make them easier to destroy by simple hand-held anti-tank missile launchers.

Christians supported low yield clean anti-tank bombs while Soviet propaganda complained

Cohen stated that he "worked in France on low-yield, highly discriminate tactical nuclear weapons in 1979-1980". While in Europe, he was greated with great respect for his views.

"In 1979, Pope John Paul II conferred on one of the authors (Sam Cohen) a peace medal for his invention, the neutron bomb. This was a small nuclear weapon designed to do its work, killing enemy military forces, without destroying a country’s infrastructure." (Cohen, March 11, 2003)

Cohen was the victim of the Moscow controlled 'World Peace Council' which funded pro-communist nuclear information attempting to discredit American innovations which checked Soviet aggression in Europe. The Pope, John Paul II, was from Poland and knew that communist forces had a massive tank superiority in Europe and that a deterrent which was designed to minimise civilian casualties was a step away from indiscriminate warfare. The neutron bomb no more kills by long-term radiation effects than bullets kill by lead poisoning.

In 1981, the Christian Science Monitor reported that there "are 19,500 tanks in the Soviet-controlled forces of the Warsaw Pact aimed at Western Europe. Of these, 12,500 are Soviet tanks in Soviet units. NATO has 7,000 tanks on its side facing the 19,500." (Joseph C. Harsch, "Neutron Bomb: Why It Worries The Russians," Christian Science Monitor, August 14, 1981, p. 1.) [8]

References

• Hans A. Bethe, Working Group Chairman, originally Top Secret - Restricted Data Report of the the President's Science Advisory Committee, 28 March 1958, defending on pages 8-9 'clean nuclear weapons tests', online
• Terry Triffet and Philip LaRiviere, Characterization of Fallout, Operation Redwing fallout studies, directly comparing contamination from two 'dirty' tests (Tewa and Flathead) to two 'clean' tests (Navajo and Zuni), online
• Charles Platt, "Profits of Fear", August 16, 2005 online;
• Sam Cohen and Joseph D. Douglass, Jr, "The Nuclear Threat That Doesn't Exist – or Does It?", March 11, 2003, online; Red mercury, fusion-only neutron bombs, Russia, Iraq, etc
• ---- "North Korea's Nuclear Initiative", April 28 2004 online
• ---- "Development of New Low-Yield Nuclear Weapons", March 9, 2003, online
• ---- "The Rogue Nuclear Threat", April 26, 2002, online
• Joe Douglass, The Conflict Over Tactical Nuclear Weapons Policy in Europe (1968)
• William R. Van Cleave, S. T. Cohen, Nuclear Weapons, Policies, and the Test Ban Issue, 1987, ISBN 0275923126
• Samuel T. Cohen, We Can Prevent World War III, 1985, 2001, ISBN 0915463105
• ---- The Truth About the Neutron Bomb: The Inventor of the Bomb Speaks Out, William Morrow & Co., 1983, ISBN 0688016464
• ---- Shame: Confessions of the Father of the Neutron Bomb (2000), ISBN 0738822302, memoir
• Review of Shame published on Amazon: [9]

See also

• Ballotechnics, Nuclear isomer, Red mercury