Demonstration of the first visible wavelength direct nuclear pumped laser

The first direct nuclear pumped laser to operate on a visible wavelength is described, whereas previous nuclear lasers have operated in the infrared. The Sandia Pulsed Reactor II was used as a high flux source of neutrons that pumped a helium-mercury gas laser via the high energy products of the B-10(n,alpha)Li-7 nuclear reaction. No other source of energy was utilized. Lasing was observed at 6,150 A. The thermal neutron flux threshold for lasing was approximately 1 x 10 to the 16th power n/sq cm/sec, and the laser output was continuous over the 400 micro sec operating time of the nuclear reactor. The laser signal appeared to increase linearly with thermal neutron flux.