Shame

Rating:
Summary: Excellence
Review: Dr Samuel Cohen spent his life trying to blunt the forces of disaster, and to turn nuclear weapons into a means of ending all war for once and for all.

Unlike Dr Oppenheimer and Dr Teller, Cohen never acquired the influence to publicise his innovations widely or forcefully enough to reach success.

Motivated by childhood problems and shame, he was able to endure the ridicule and dismissals which were the hallmark of being the inventor of the neutron bomb.

On 11 July 1956, on a barge in the lagoon of Bikini Atoll, a nuclear test codenamed Redwing-Navajo was conducted. The bomb had a total yield of 4.5 megatons, but the surprising thing was that only 5% came from fission. It was 95% clean.

Dr Hans Bethe two years later wrote, in the 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:

"... 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."

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.

Dr Cohen, at the RAND Corporation, visited the weapons laboratories and worked on a very low yield clean weapon. Because the case thickness needed in a hydrogen bomb is proportional to the cube root of the total yield, the thickness is minimal for very low yields.

For a 1 kt clean bomb, the case thickness needed is so small that a large fraction of the neutrons - which from fusion have a high energy (14 mega electron volts) escape.

Hence, Cohen had just invented the neutron bomb. Various ways of getting it to work were tried and tested. The problem was igniting fusion with a sub-kiloton yield. Instead of lithium deuteride for fusion, some designs required the very expensive lithium tritide, or a mixture of the two.

However, it is known that a compromise is possible. The small total yield in any case minimises the size of the fusion charge needed, and keeps the cost reasonable.

The major propaganda against the neutron bomb has sought to falsely assert that it creates "radiation" in the sense of fallout. By being air burst and by having a low fission yield, it averts any significant fallout. For air bursts, the fission products decay and diffuse to background radiation level before they enter the lower air layer and are deposited by rain months later. By comparison to today's stockpiled 475 kt nuclear warheads, the neutron bomb is both safe and peaceful.

We have to have nuclear weapons to counter the possible threats from proliferation states, enemies, and terrorists. But we don't have to go throwing high-fallout 475 kt warheads about. Until the next Cold War, we should take up Dr Cohen's idea and replace all the nuclear weapons in the stockpile with credible deterrence: neutron warheads.

People who attack Dr Cohen's neutron bomb in ignorance should be ashamed of themselves. We like in an age of ready sycophants, of fools. The 1 kt neutron bomb kills but doesn't create severe fallout. A 475 kt warhead blasts window glass into children's eyes, melts their faces and contaminates their playgrounds.

Will the world be a better place with 1 kt neutron bombs replacing high-yield stockpile warheads? Yes, it will.

Detonated at 500 m altitude, any 1 kt nuclear bomb produces a peak overpressure at ground zero of less than 6 psi, and at 2 km the blast is just 1 psi. The neutron bomb reduces both of these figures, and avoids severe thermal burns. What it does do is to produce 15 times the prompt neutron doses of a normal fission weapon, deterring terrorists, deterring massed tank invasions, etc. Detonated underground in an earth-penetrator warhead case, the neutron bomb has the energy to pack a punch at a hardened target without producing a significant fallout danger.

No weapon is perfect. But the neutron bomb is as near as makes no difference. Dr Cohen should be taken very seriously indeed.