New Scientist reports on a development that's got to make you stop and think.
AN EXOTIC kind of nuclear explosive being developed by the US Department of Defense could blur the critical distinction between conventional and nuclear weapons. The work has also raised fears that weapons based on this technology could trigger the next arms race.
Scientists have known for many years that the nuclei of some elements, such as hafnium, can exist in a high-energy state, or nuclear isomer, that slowly decays to a low-energy state by emitting gamma rays. For example, hafnium178m2, the excited, isomeric form of hafnium-178, has a half-life of 31 years.
The hafnium explosive could be extremely powerful. One gram of fully charged hafnium isomer could store more energy than 50 kilograms of TNT. Miniature missiles could be made with warheads that are far more powerful than existing conventional weapons, giving massively enhanced firepower to the armed forces using them.
The effect of a nuclear-isomer explosion would be to release high-energy gamma rays capable of killing any living thing in the immediate area. It would cause little fallout compared to a fission explosion, but any undetonated isomer would be dispersed as small radioactive particles, making it a somewhat "dirty" bomb. This material could cause long-term health problems for anybody who breathed it in.
So it isn't really a ray-gun, it's a gamma-ray bomb. Sounds pretty nasty. Well, better we have it than they, I suppose.
Interesting devices. Too bad most of the energy appears to be gamma rays. Would be interesting (or perhaps nightmarish) to have a high explosive material (with that kind of energy density) where most of the energy can be converted to physical motion of mass. You could move a lot of material (eg, dig big holes) with something like that. It would also be much more likely to have peaceful uses.
Posted by: Karl Hallowell at August 14, 2003 04:15 PMThis uses the "hafnium trick", which so far other labs have failed to duplicate. Looks like cold fusion to me.
http://www.llnl.gov/llnl/06news/NewsReleases/2001/NR-01-08-05.html
Posted by: Nyrath the nearly wise at August 15, 2003 06:46 AMFirst, IIRC, gamma rays at these relatively low energies (low for nuclear, that is) are absorbed pretty quickly by air, so I *think* you'd get a fireball, not a gamma ray burst.
Second, the only thing that wasn't duplicated was the particular energy release mechanism. However, any mechanism capable of providing a few keV to the metastable nucleus should work. As inner shell electrons have some probability of being in the nucleus, stimulation via UV laser may work. Or direct photonuclear triggering using a femtosecond laser. Or... So, if the dental X-ray trigger turns out not to work that doesn't render the entire thing to the status of 'cold fusion'. There's an absolutely known energy storage state here for which we can do a fair job of understanding the physics.
Lastly, it's not at all clear this would be a runaway process (as an explosion implies). However, if it can be arranged at least on milligram scales, this may be just the thing to provide useful Earth-to-orbit propulsion.
Posted by: Eric S. at August 15, 2003 08:17 AMWhat are the rules on the notation system for nuclear isomers? Hafnium 178 is clear enough, the "m" stand for metastable, but what does the "2" stand for?
Is it that there are two nucleons in an exited state?
Something else : is it conceivable to have the nucleair isomers in a "population inversion and trick them into a kind of lasing effect ?
Posted by: michael at August 21, 2003 02:33 AM"2" means the second isomeric state of 178Hf. The first one (178mHf) has a much shorter life-time (4 seconds) and much lower energy (1.2MeV), comparing with the second isomeric state (31-years life-time and 2.5MeV energy)
Posted by: eu at October 22, 2003 09:45 PM1257 Get your online poker fix at http://www.onlinepoker-dot.com
Posted by: online poker at August 15, 2004 07:17 PM