Calibration Of The Magixs Experiment. I. Calibration Of The X-Ray Source At The X-Ray And Cryogenic Facility

The Marshall Grazing Incidence Spectrometer (MaGIXS) is a sounding rocket experiment that will observe the soft X-ray spectrum of the Sun from 24 to 6.0 A (0.5-2.0 keV) and is scheduled for launch in 2021. Component- and instrument-level calibrations for the MaGIXS instrument are carried out using the X-ray and Cryogenic Facility (XRCF) at NASA Marshall Space Flight Center. In this paper, we present the calibration of the incident X-ray flux from the electron impact source with different targets at the XRCF using a CCD camera; the photon flux at the CCD was low enough to enable its use as a "photon counter," i.e., the ability to identify individual photon hits and calculate their energy. The goal of this paper is two-fold: (1) to confirm that the flux measured by the XRCF beam normalization detectors is consistent with the values reported in the literature and therefore reliable for MaGIXS calibration and (2) to develop a method of counting photons in CCD images that best captures their number and energy.