Search for induced emission from the178Hfm2isomer by low-energy x rays

Abstract

Whether or not the ${}^{178}$Hf${}^{m2}$ isomer has the characteristic of induced \ensuremath{\gamma} emission by low-energy x rays has been a focus of attention for many scientists and researchers in recent decades. In this paper, an experiment regarding triggering ${}^{178}$Hf${}^{m2}$ emission decay is conducted at Shanghai Synchrotron Radiation Facility. An x-ray beam with 20.825-keV energy irradiates a rectangular sample containing about 10${}^{11178}$Hf${}^{m}$${}^{2}$ nuclides. By comparing the net gamma count rates during the irradiation with those after the irradiation, the data show that at the 426-, 495-, and 574-keV gamma lines, there is no significant enhancement, indicating that the induced \ensuremath{\gamma} decay of ${}^{178}$Hf${}^{m2}$ has not been observed.