The coherent and incoherent pumping of a gamma ray laser with intense optical radiation

Abstract

Both the coherent and incoherent pumping with intense optical radiation of electromagnetic transitions in nuclei were modeled in this work. In the first case the anti-Stokes upconversion of conventional laser radiation was shown to be a potentially viable means for pumping a γ-ray laser. With the most favorable possible arrangement of nuclear energy levels, the threshold for stimulated output at 10 keV might be reached at a few tens of Joules for isomeric media with lifetimes of the order of tens of years. Whether such an arrangement of excited states actually exists will require additional experimentation. In the case of the incoherent pumping of nuclear material, the resonant excitation of energetic states of nuclei by x radiation from laser plasmas or exploding wires was modeled with results similar to those for the case of coherent pumping. Thresholds for stimulated output could be as low as a few hundred Joules into the primary laser pulse producing the x-ray flash. Again the possibilities were found to be critically dependent upon unknown parameters, particularly upon the efficiency for the conversion of input energy into x rays. The overall possibilities for the excitation of a γ-ray laser with optical pumping were concluded to be reasonably encouraging and the need for additional spectroscopic data was clearly defined.