Authors: F S Porter M P Chiao M E Eckart R Fujimoto Y Ishisaki R L Kelley C A Kilbourne M A Leutenegger D McCammon K Mitsuda M Sawada A E Szymkowiak Y Takei M Tashiro M Tsujimoto T Watanabe S Yamada
Publish Date: 2016/01/27
Volume: 184, Issue: 1-2, Pages: 498-504
Abstract
Calorimetric Xray detectors are very sensitive to their environment The boundary conditions can have a profound effect on the gain including heat sink temperature the local radiation temperature bias and the temperature of the readout electronics Any variation in the boundary conditions can cause temporal variations in the gain of the detector and compromise both the energy scale and the resolving power of the spectrometer Most production Xray calorimeter spectrometers both on the ground and in space have some means of tracking the gain as a function of time often using a calibration spectral line For small gain changes a linear stretch correction is often sufficient However the detectors are intrinsically nonlinear and often the event analysis ie shaping optimal filters etc add additional nonlinearity Thus for large gain variations or when the best possible precision is required a linear stretch correction is not sufficient Here we discuss a new correction technique based on nonlinear interpolation of the energyscale functions Using AstroH/SXS calibration data we demonstrate that the correction can recover the Xray energy to better than 1 part in 104 over the entire spectral band to above 12 keV even for largescale gain variations This method will be used to correct any temporal drift of the onorbit perpixel gain using onboard calibration sources for the SXS instrument on the AstroH observatory
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