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Nuclear isomers are back. The controversial field of exploiting excited nuclei, to release atomic energy on demand, was brought low a years back, after some controversial experiments – and some loose talk of creating an "nuclear hand grenade." Now, the field is beginning to thrive once again, as I report in the Guardian. But mindful of earlier controversies, the researchers are keeping a low profile.
It's hard to overstate just how divisive the topic is. Critics have consistently poured scorn on Carl Collins' claims that he had successfully got a sample of the Hafnium 178m2 isomer to release an enormous amount of gamma radiation -- despite only putting a relative small bit of energy in. Skeptics say his work lacks a sound theoretical basis, and only groups associated with Collins have replicated his results, not indepedent researchers. As a result, research in this area has faced some very determined and organized opposition, which forced the cancellation of Darpa's original program. *New Scientist *rated the Hafnium Bomb as Darpa's #1 failure (ahead of psychic spying and the Orion nuclear-bomb-powered spacecraft). In fellow DANGER ROOM blogger Sharon's book, Imaginary Weapons, isomer research became the poster child for bad military science. [Many Pentagon bigwigs keep a copy of the book on their desks, as a reference for what to avoid when backing a new research program -- ed.]
The issue turns on metastable nuclear isomers. In the nucleus of a normal atom, the particles are in the lowest energy state. In a metastable isomer they have absorbed energy and are in an excited state. Normally (as with other nuclear decay), the atoms will release the energy randomly after a period of time; the question is whether, given the correct stimulation (from an x-ray, say), they can be prompted to release their energy on demand. The process is known as "triggering." Collins says he showed it could be done, and that his colleagues pulled it off, too. Critics demanded that the triggering experiments be replicated independently -- a bedrock principle of the scientific method. Collins never could. And, for a while, it appeared as if the American government might get out of the isomer-triggering game.
To this day, researchers working on isomers remain skittish about talking to the press; nobody wants to be the next bad science poster boy. However, it turns out that there are quite a few military isomer programs going on at present; the US Army, Navy and DTRAall have their own. There has been work at the Atomic Weapons Research Establishment here in Britain. Scientists at Lawrence Livermore National Laboratory are continuing their long-standing work in this field; not long ago, they were among the loudest critics of Collins' claims.
Most researchers are careful to distance themselves from the earlier research. Specifically, they're either looking at different materials or different transitions. The idea now is very much geared towards eventually, someday using nuclear isomers as super-batteries -- rather than as bombs. This is new isomer triggering, and nothing like the old isomer triggering. The concern is that attitudes to their work will be tainted by the similarities.
“One should differentiate between an ‘isomer program’ and what might be called the ‘hafnium program’” warns James Carroll, a Pentagon-funded researcher at Youngstown State University.
The Army research program, known as On-Demand High Energy Density Materials, seeks to develop a nuclear battery that can be turned on an off at will. That opens up the prospect of being able to store a hundred thousand times as much energy as conventional batteries in a
"deployable micro-reactor," or as long-lasting power sources for remote sensors:
However, the Army team have also done some work on the economics involved.
By their estimate, isomer power is going to be expensive and only suitable for low-energy applications. Electric cars with isomer power sources are not going to be filling the roads any time soon. They mights, however, increase the endurance of dragonfly-sized micro air vehicles from minutes to days.
Even Collins' critics at Lawrence Livermore are pushing ahead with their ongoing isomer research. Back in 2001, they announced "new results that strongly contradict recent reports claiming an accelerated emission of gamma rays from the nuclear isomer 31-yr Hafnium." By last year, they were declaring that they were ready to demonstrate isomer triggeringin Thorium-229.
But this is not a road-to-Damascus conversion. Researchers at
Livermore have been working on isomer triggering for years. They have never said that isomer triggering was impossible, just that they did not believe Collins' claims. One of the lead researchers is John
Becker, who was part of the team that critiqued the 1999 results.
Speaking of their own work, one scientist says:
“This would then be the first time human control would be exerted over nuclear levels,” said Peter Beiersdorfer, an LLNL physicist and co-author of a paper that appears in the April 6 issue of Physical Review Letters.
Looks like Lawrence Livermore is intent on claiming this world first for themselves. However, not everyone dismisses the earlier results or the possibility of an isomer bomb, as we will see in Part 2.
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