Novel Dual Aperture Design for Soft X-Ray Solar Spectrometer: Design and Calibrations

New solar soft X-ray (SXR) spectra were obtained on a June 2018 NASA sounding rocket flight using a novel dual aperture design to enhance spectral coverage using a single X-ray spectrometer. The X-ray spectrometer is the Amptek X123 Fast SDD with Si-PIN detector and beryllium filter to provide SXR measurements from 0.5-30keV with better than 0.15keV energy resolution. The dual aperture design features a large aperture with a thin Kapton filter and with a small pin-hole centered in the Kapton filter to provide as a second aperture. The lower energy photons (0.5-2keV) are attenuated by the Kapton, whereas higher energy photons (2-30keV) still penetrate through both the beryllium and Kapton. The X123 spectrometer itself has been flight proven on the Miniature X-ray Solar Spectrometer CubeSat (MinXSS-1) and will be flown again on MinXSS-2 in late 2018. Compared to the single aperture on the MinXSS satellites, the Dual Aperture X-ray Solar Spectrometer (DAXSS) allows for greater counts at higher energies without saturating those at lower energies which results in spectral resolution across a wider energy range while still using the same detector. This instrument was calibrated at the NIST Synchrotron Ultraviolet Radiation Facility (SURF) in Gaithersburg, Maryland prior to the rocket launch. The design and calibration of this instrument along with the modeling required to fit spectral measurements from the June rocket flight will be discussed.