From Richard Schwartz:
Four routines have been changed to support better precision in the detector response around the instrumental K-edges for germanium, molybdenum (Grid 1 only), and tungsten. They are hsi_srm__define.pro hsi_srm_control.pro hsi_srm_control__define.pro hsi_drm_mod__define.pro There is a new control parameter for the 'hsi_srm' object, INSERT_KEDGE. For the time prior to the SPD meeting its default will be 0 so it will have no effect. We'll change the default to 1 after the SPD meeting June 10-15, 2012. With INSERT_KEDGE set(1), energy edges are introduced into the SRM (detector response matrix) at the edges where the cross-sections for x-ray photoelectric absorption has a jump. Those jumps have been in the response tools for the SRM and grids but the calling routines have been using the default channel edges for photon energy edges. That compromises the computation of the response at those energies. The best solution is to insert edges at those energies and hence have the response computed more exactly. While testing the change to the SRM generator we noticed an issue with hsi_drm_mod__define (used in OSPEX) where the code was assuming that in the low energy range the channel and photon edges were identical. Not the case with this change, so hsi_drm_mod__define was also changed to support this. It shouldn't change the results for any previous SRM fits files. However, to take advantage of the INSERT_KEDGE code you'll have to regenerate your SRM fits files with INSERT_KEDGE set.