Testing for the continuous spectrum of x rays predicted to accompany the photoejection of an atomic inner-shell electron

Echoing classical physics, quantum electrodynamics predicts the release of a spectral continuum electromagnetic radiation upon sudden acceleration charged particles in matter. Despite apparent theoretical success describing sister nuclear processes, known as internal bremsstrahlung, following beta decay and $K$ capture, situation photoejection an electron from inner shell atom, intra-atomic bremsstrahlung (IAB), is far settled. In this paper we present fresh measurements which rely on contemporary signal processing well high flux available synchrotron source to revisit problem by photoejecting electrons innermost copper. We have sufficient sample statistics measure expected spectra at level theory. Furthermore, employ sufficiently thin targets overcome secondary scattering artifacts. Our approach applies fluorescence coincidence method guard against extraneous multiple incident photon processes. observations set severe upper limit rate for IAB: conclude that current theory overpredicts, least 5 sigma, measured $K$-shell IAB copper range detected energies below energy.