Photon cross sections for resonant de-excitation of nuclear isomers as a precursor to a gamma-ray laser

摘要

Integrated cross sections (ICS) for triggered decay of nuclear isomers have recently become accessible in experimental studies that were motivated both by general physical interest and by applications, such as a possible gamma-ray laser. Theoretical predictions for ICS are reviewed here and an equation is derived based on the Blatt-Weisskopf probability for an electromagnetic transition between two nuclear levels. This formula is effectively equivalent to the recognized Breit-Wigner expression despite their development from essentially different approaches. The results of a recent high-sensitivity experiment on the Ta-180(m) isomer de-excitation induced by bremsstrahlung are analyzed in this context. An important parameter of the de-excitation branch probability is determined now over a wide energy range from 1 to 10 MeV, including previously reported results. [References: 7]