Testing for the Continuous Spectrum of X-Rays Predicted to Accompany the Photoejection of an Atomic Inner Shell Electron*

For decades, experimental evidence for an elegant prediction of quantum electrodynamics has been sought: the detection of a broad spectrum of X-rays at low energies expected upon sudden ejection of an inner shell electron following absorption of an incident high energy photon. We report here on a recent attempt that provides a significantly reduced upper limit on the process that is consistent with contemporary theory and contradicts earlier observations. The Cornell High Energy Synchrotron Radiation Source (CHESS) was employed to deliver a 46 keV incident beam on solid copper film targets. To suppress extraneous events detection of scattered photons was performed in coincidence with the fluorescent decay of the K shell hole produced by photoejection. Through variable thickness targets we assessed secondary processes.