With respect to gamma ray lasers:
Pumping has been one of the rocks on which previous efforts foundered. The first pumping schemes proposed would have put a great deal of energy into the lasing material very quickly (bomb-pumped lasers (Star Wars)) — in microseconds or even picoseconds — in the hope of getting some into short-lived lasing states. This threatened to melt the material. A suggested alternative was to use an energy state that lasts a long time, perhaps 270 years, so that energy could be built up slowly, and then trigger the stimulated emission. But in the long time period, there are effects that degrade the sharpness of the wavelength, one of the qualities necessary for a good laser.
“This straightforward, brute-force pumping won’t work,” Collins concludes. What will work, he says, is a double process in which energy is first stored in a long-lived “isomeric” state — a state that naturally lasts about a year before it radiates. In this way energy can be introduced slowly to avoid overheating. Then another injection of energy pumps the nucleus to a nearby state that lasts only a second, and from this state the actual lasing occurs. This “upconversion” process is done with X-rays.
Once the nucleus is pumped, will it emit gamma rays? To counter the enthusiasm of the gamma ray workers, the organizers of the meeting invited Harry J. Lipkin of Argonne (Ill.) National Laboratory and the Weizmann Institute of Science in Rehovot, Israel, as devil’s advocates for nuclear physics. He reminded the group that the nucleus would most likely get rid of its energy by a process that emits an electron rather than a gamma ray. The laser people responded that they intend to embed the lasing nuclei in a crystal; then a property of the crystal known as Borrmann effect would alter the energy balance so as to make gamma ray emission more likely.
http://findarticles.com/p/articles/mi_m1200/is_v130/ai_4539152
Research continues.
Have you heard about the halfnium bomb?
http://www.washingtonpost.com/ac2/wp-dyn?pagename=article&contentId=A22099-2004Mar24
