The Gamma-Ray Laser Project: Proof of the Feasibility of Coherent and Incoherent Schemes for Pumping a Gamma-Ray Laser.

Recent approaches to the problem of the gamma-ray laser have focused upon upconversion techniques in which metastable nuclei are pumped with long wavelength radiation. At the nuclear level the storage of energy can approach tera-Joules 10 to the 12th power J per liter for thousands of years. However, any plan to use such a resource for a gamma-ray laser poses problems of a broad interdisciplinary nature requiring the fusion of concepts taken from relatively unrelated fields of physics. Since 1978 we have pursued an approach for the upconversion of longer wavelength radiation incident upon isomeric nuclear populations that can avoid many of the difficulties encountered with traditional concepts of single photon pumping. Recent experiments have confirmed the general feasibility and have indicated that a gamma-ray laser is feasible if the right combination of energy levels and branching ratios exists in some real material. Resolution of the question of the feasibility of a gamma-ray laser now rests upon the determination of 1 the identity of the best candidate, 2 the threshold level of laser output, and 3 the upconversion driver for that material.