Long-term trends in radiation damage of Chandra X-ray CCDs

Abstract

Soon after launch, the Advanced CCD Imaging Spectrometer (ACIS), one of the focal plane instruments on the Chandra X-ray Observatory, suffered radiation damage from exposure to soft protons during passages through the Earth's radiation belts. Current operations require ACIS to be protected during radiation belt passages to prevent this type of damage, but there remains a much slower and more gradual increase. We present the history of ACIS charge transfer inefficiency (CTI), and other measures of radiation damage, from January 2000 through June 2005. The rate of CTI increase is low, of order 1e-6 per year, with no indication of step-function increases due to specific solar events. Based on the time history and CCD location of the CTI increase, we speculate on the nature of the damaging particles.

arXiv comment10 pages, 14 figures to appear in Proc. SPIE vol. 5898 "UV, X-ray, and Gamma-Ray Space Instrumentation for Astronomy XIV"

References in corpus (4)

• An Overview of the Performance and Scientific Results from the Chandra X-Ray Observatory (CXO)
• A charge transfer inefficiency correction model for the Chandra Advanced CCD Imaging Spectrometer
• Sacrificial charge and the spectral resolution performance of the Chandra Advanced CCD Imaging Spectrometer
• The temporal characteristics of the Chandra X-ray Observatory high energy particle background

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• The Speedster-EXD- A New Event-Driven Hybrid CMOS X-ray Detector
• Temperature dependence of charge transfer inefficiency in Chandra X-ray CCDs
• Fifteen years of the Advanced CCD Imaging Spectrometer
• Using ACIS on the Chandra X-ray Observatory as a particle radiation monitor