PERFORMANCE OF THE INVERSE-PHOTOEMISSION SPECTROMETER WITH A NEW BANDPASS PHOTON DETECTOR OF NARROW BANDWIDTH AND HIGH-SENSITIVITY

A combination of a SrF2 entrance window and a photomultiplier with the Cu-BeO first dynode coated with KCl film realizes the bandpass photon detector with the FWHM of 0.47 eV centered at 9.43 eV and the sensitivity improved by about one order of magnitude in comparison with the detector without the KCl film. The overall energy resolution of the inverse photoemission spectrometer consisting of an electron gun with a BaO cathode and the new detector has been estimated to be 0.56 eV using polycrystalline Au. Typical counting rate is 10(2)-10(3) counts/(muA s) for unoccupied states near the Fermi level of the Au at an acceptance angle of about 0.8pi sr with an Al collecting mirror.