Radioactive emission of Tin-119 isomers and Mossbauer backscattering

Within the framework of investigations devoted to the generation of coherent gamma-ray beams (gamma-ray lasers), conditions that allow a considerable change in the radioactive-decay constant lambda up to Delta lambda/lambda = -(0.114+/-0.027) have been experimentally determined for the first time (the 89.53-keV isomeric level of Sn-119m, T-1/2 = 293 days). This effect becomes possible due to coherent Mossbauer (23.87-keV) backscattering from a close resonant screen. The observed effect is interpreted in terms of dynamic synchronization of "nuclear level-standing wave of Mossbauer radiation" oscillations.