Abstract
X-ray spectrometer onboard HAYABUSA spacecraft has a standard sample to perform comparative analysis. Comparing with the X-rays from the standard sample and asteroid surface, the dependency of induced X-ray, solar X-rays, is reduced [1].
It takes more than 2 years to reach the Asteroid, and the temporal variance of the XRS performance is investigated periodically by the observation of the X-rays from Cosmic X-ray Backgrounds, astronomical X-ray bodies, and the standard sample.
From 28 May 2003 to 30 May 2003, just after the launch of HAYABUSA, XRS observed an X-ray source: SCO-X1 [2]. The observation continued two days due to the initial checkout. Fortunately, an X.1 class solar flare happened during this term. The spectra from the standard sample were composed of Ca and Si line spectra together with Mg, Al, and Si line spectra. These data is available for the XRS in-flight calibration: energy gain and intensities. In addition, model parameter is determined by this data.
Yamamoto et al reported that the energy calibration, comparison of the energy flux between GOED 10 and XRS, and the comparison of the observation and calculation using thess data [3]. The energy calibration of the line spectra: Mg, Al, Si, Ca, and Fe, was determined within 1% accuracy comparing with 55Fe calibration data before launch. Temporal variation of energy flux obtained by XRS showed the consistency with that obtained by GOES 10 satellite. Moreover, the model calculation was performed and compared with the observation. The comparison showed the background noise in the energy range 0.5-3keV clearly existed. This noise was serious problem to determine the intensities of Mg, Al, and Si X-ray fluorescence spectra.Therefore, we report here the method to remove this background noise, and the effect of the method.
[1] Okada, T., Fujiwara, A., Tsunemi, H., and Kitamoto, S. 2000. X-ray fluorescence spectrometer onboard MUSES-C, Adv. Space Res. 25, 345-348.
[2] Arai et al, 2003. Proc. ISAS Lunar Planet. Symp.
[3] Yamamoto et al, 2003. Proc. ISAS Lunar Planet. Symp.
