Search for x-ray induced acceleration of the decay of the 31-yr isomer of (178)Hf using synchrotron radiation.

Enhanced decay of the 31-yr isomer of (178)Hf 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 x 10(-27) cm(2) keV, below the previously reported values by more than 5 orders of magnitude; at 8 keV the limit is 5 x 10(-26) cm(2) keV.