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Published November 25, 2011 | public
Journal Article

Improvements in Calibration of GSO Scintillators in the Suzaku Hard X-Ray Detector

Abstract

Improvements of the in-orbit calibration of GSO scintillators in the Hard X-ray Detector aboard Suzaku are reported. To resolve an apparent change in the energy scale of GSO, which appeared across the launch for unknown reasons, consistent and thorough re-analyses of both pre-launch and in-orbit data have been performed. With laboratory experiments using spare hardware, the pulse-height offset, corresponding to zero energy input, was found to change by ~0.5% of the full analog voltage scale, depending on the power supply. Furthermore, by carefully calculating all of the light outputs of secondaries from activation lines used in the in-orbit gain determination, their energy deposits in GSO were found to be effectively lower, by several percent, than their nominal energies. Taking both of these effects into account, the in-orbit data agree with the on-ground measurements within ~5%, without employing the artificial correction introduced in previous work (Kokubun et al. 2007, PASJ, 59, S53). With this knowledge, we updated the data processing, the response, and the auxiliary files of GSO, and reproduced the HXD-PIN and HXD-GSO spectra of the Crab Nebula over 12–300 keV by a broken power-law with a break energy of ~110 keV.

Additional Information

© 2011 Astronomical Society of Japan. Received 2010 November 14; accepted 2011 May 22. The authors would like to express their thanks to all who have contributed to the design, development, operation, and the calibration of the HXD experiment, and all Suzaku supporters. The present work was supported by Grant-in-Aid for JSPS Fellows.

Additional details

Created:
August 19, 2023
Modified:
October 24, 2023