Point defect production byX-rays above and below the bromineK-edge inKBr

F-center formation by monochromatic X-rays has been studied above and below the bromineK-edge in single crystals of KBr at 77 K. A concentrated beam from an undulator at the Advanced Photon Source was used to produce these point defects, which were detected by a sensitive laser-induced luminescence method. Experiments were carried out over an especially wide range of monochromatic X-ray intensity. Contrary to our previous reports, a large increase inF-center formation efficiency was not found upon crossing the bromineK-edge, which suggests that additional Auger-cascade mechanisms do not compete strongly with the usual multiple ionization electron-hole recombination processes known to generate point defects.