Search for X-Ray Induced Acceleration of the Decay of the 31-Yr Isomer of 178Hf Using Synchrotron Radiation

Enhanced decay of the 31-yr isomer of 178Hf induced by x-ray irradiation has been reported previously. Here we describe an attempt to reproduce this result with an intense "white" x-ray beam from the Advanced Photon Source. No induced decay was observed. The upper limits for the energy-integrated cross sections for such a process, over the range of energies of 20–60 keV x rays, are less than 2×10^-27cm^2 keV, below the previously reported values by more than 5 orders of magnitude; at 8 keV the limit is 5×10^-26 cm^2 keV.