Calibration of the hard x-ray detectors for the FOXSI solar sounding rocket

P. S. Athiray, Juan Camilo Buitrago-Casas, Kendra Bergstedt, Juliana Vievering, Sophie Musset, Shin Nosuke Ishikawa, Lindsay Glesener, Tadayuki Takahashi, Shin Watanabe, Sasha Courtade, Steven Christe, Säm Krucker, Keith Goetz, Steven Monson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Scopus citations


The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment conducts direct imaging and spectral observation of the Sun in hard X-rays, in the energy range 4 to 20 keV. These high-sensitivity observations are used to study particle acceleration and coronal heating. FOXSI is designed with seven grazing incidence optics modules that focus X-rays onto seven focal plane detectors kept at a 2m distance. FOXSI-1 was flown with seven Double-sided Si Strip Detectors (DSSD), and two of them were replaced with CdTe detectors for FOXSI-2. The upcoming FOXSI-3 flight will carry DSSD and CdTe detectors with upgraded optics for enhanced sensitivity. The detectors are calibrated using various radioactive sources. The detector's spectral response matrix was constructed with diagonal elements using a Gaussian approximation with a spread (sigma) that accounts for the energy resolution of the detector. Spectroscopic studies of past FOXSI flight data suggest that the inclusion of lower energy X-rays could better constrain the spectral modeling to yield a more precise temperature estimation of the hot plasma. This motivates us to carry out an improved calibration to better understand the finer-order effects on the spectral response, especially at lower energies. Here we report our improved calibration of FOXSI detectors using experiments and Monte-Carlo simulations.

Original languageEnglish (US)
Title of host publicationUV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX
EditorsOswald H. Siegmund
ISBN (Electronic)9781510612518
StatePublished - 2017
EventUV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX 2017 - San Diego, United States
Duration: Aug 6 2017Aug 8 2017

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceUV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX 2017
Country/TerritoryUnited States
CitySan Diego

Bibliographical note

Funding Information:
The FOXSI rocket team gratefully acknowledges NASAs LCAS program for funding the experiment, specifically NASA grants NNX08AH42G and NNX11AB75G. The UMN team members thank the NSF for its support of space physics at UMN through grant AGS-1429512. The team is grateful to JAXA/ISAS for the donation of detectors, ASICs, and abundant expertise. The authors thank Elza Thayer for her valuable comments which helped in the preparation of this manuscript.

Publisher Copyright:
© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.


  • DSSD
  • Hard X-ray
  • The Sun


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