Development of the filter wheel for calorimeters on board ASTRO-E Original Research Article

X-ray spectrometer (XRS) is the main instrument for the ASTRO-E, scheduled for launch in February 2000. In order to maintain its superior energy resolution (FWHM ∼12 eV), we control the incident flux for the XRS to be less than several c/s/pixel using various filters. The filter wheel (FW) is placed above the XRS dewar, carrying 5 different filters which are selected by a stepping motor. The installed filters are 2 low-energy cut filters made of thin Be plates and 3 neutral density filters which are Mo plates with about 1800 pinholes each. The filter properties are measured with X-ray beams at various energies. Reliability of the FW system has been established by extensive tests on the prototype model. The flight-model FW has been already assembled, and qualified through a number of tests. Simulations of the XRS combined with the X-ray telescope are performed to study the on-board performances of filters for various X-ray sources.