X-ray transmission calibration of the gate valve for the x-ray astronomy satellite XRISM

Resolve onboard the x-ray satellite X-Ray Imaging and Spectroscopy Mission (XRISM) is a cryogenic instrument with an microcalorimeter in Dewar. A lid partially transparent to x-rays (called gate valve or GV) installed at top of Dewar along optical axis. Because observations will be made through GV for first few months, transmission calibration crucial initial scientific outcomes. We present results our ground campaign GV, which composed Be window stainless steel mesh. For mesh, we measured its using beamline ISAS. window, used synchrotron facilities measure modeled data (i) photoelectric absorption incoherent scattering Be, (ii) contaminants, (iii) coherent changing specific energies. discuss physical interpretation discontinuity caused by Bragg diffraction polycrystal incorporated into phenomenological model. measurement on sample support interpretation. The measurements constructed model meet requirements GV. also performed spectral fitting Crab nebula observed Hitomi SXS confirmed improvements parameters.