CCD driving technique to suppress anomalous charge intrusion from outside the imaging area for soft X-ray imager of Xtend onboard XRISM

The Soft X-ray Imager (SXI) is an X-ray charge-coupled device (CCD) camera of the Xtend system onboard the X-Ray Imaging and Spectroscopy Mission (XRISM), which was successfully launched on September 7, 2023 (JST). During ground cooling tests of the CCDs in 2020/2021, using the flight-model detector housing, electronic boards, and a mechanical cooler, we encountered an unexpected issue. Anomalous charges appeared outside the imaging area of the CCDs and intruded into the imaging area, causing pulse heights to stick to the maximum value over a wide region. Although this issue has not occurred in subsequent tests or in orbit so far, it could seriously affect the imaging and spectroscopic performance of the SXI if it were to happen in the future. Through experiments with non-flight-model detector components, we successfully reproduced the issue and identified that the anomalous charges intrude via the potential structure created by the charge injection (CI) electrode at the top of the imaging area. To prevent anomalous charge intrusion and maintain imaging and spectroscopic performance that satisfies the requirements, even if this issue occurs in orbit, we developed a new CCD driving technique. This technique is different from the normal operation in terms of potential structure and its changes during imaging and CI. We report an overview of the anomalous charge issue, the related potential structures, the development of the new CCD driving technique to prevent the issue, the imaging and spectroscopic performance of the new technique, and the results of experiments to investigate the cause of anomalous charges.

Authors

Institutions

Publication Details

Journal
Journal of Astronomical Telescopes Instruments and Systems
Published
2025-03-29
DOI
https://doi.org/10.1117/1.jatis.11.4.042006
Primary Topic
Advanced X-ray Imaging Techniques
Type
article
Field-Weighted Citation Impact
0.00

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

CCD driving technique to suppress anomalous charge intrusion from outside the imaging area for soft X-ray imager of Xtend onboard XRISM

Hiroshi Nakajima, Kouichi Hagino, Hideki Uchiyama, Koji Mori et al.
Journal of Astronomical Telescopes Instruments and Systems
Advanced X-ray Imaging Techniques
article

CCD driving technique to suppress anomalous charge intrusion from outside the imaging area for soft X-ray imager of Xtend onboard XRISM

Hiroshi Nakajima, Kouichi Hagino, Hideki Uchiyama, Koji Mori, Hirofumi Noda, Yoshiaki Kanemaru, Keitaro Miyazaki, Kohei K. Shima, Hironori Matsumoto, Hiromasa Suzuki, Marina Yoshimoto, Hiroyuki Uchida, Shōgo Kobayashi, Yuma Aoki, Kohei Kusunoki, Takaaki Tanaka, Takeshi Go Tsuru, Hiroshi Murakami, Kumiko Nobukawa, Masayoshi Nobukawa, T. Yoneyama, Hiroshi Tomida, Kazunori Asakura, Kiyoshi Hayashida, Mio Aoyagi
article en

Abstract

The Soft X-ray Imager (SXI) is an X-ray charge-coupled device (CCD) camera of the Xtend system onboard the X-Ray Imaging and Spectroscopy Mission (XRISM), which was successfully launched on September 7, 2023 (JST). During ground cooling tests of the CCDs in 2020/2021, using the flight-model detector housing, electronic boards, and a mechanical cooler, we encountered an unexpected issue. Anomalous charges appeared outside the imaging area of the CCDs and intruded into the imaging area, causing pulse heights to stick to the maximum value over a wide region. Although this issue has not occurred in subsequent tests or in orbit so far, it could seriously affect the imaging and spectroscopic performance of the SXI if it were to happen in the future. Through experiments with non-flight-model detector components, we successfully reproduced the issue and identified that the anomalous charges intrude via the potential structure created by the charge injection (CI) electrode at the top of the imaging area. To prevent anomalous charge intrusion and maintain imaging and spectroscopic performance that satisfies the requirements, even if this issue occurs in orbit, we developed a new CCD driving technique. This technique is different from the normal operation in terms of potential structure and its changes during imaging and CI. We report an overview of the anomalous charge issue, the related potential structures, the development of the new CCD driving technique to prevent the issue, the imaging and spectroscopic performance of the new technique, and the results of experiments to investigate the cause of anomalous charges.

Journal of Astronomical Telescopes Instruments and SystemsVol. 11(04)
University of Miyazaki (JP), Shizuoka University (JP), Nara University of Education (JP), Konan University (JP), Tokyo University of Science (JP), Tohoku University (JP), Kanto Gakuin University (JP), Kyoto University (JP), Japan Aerospace Exploration Agency (JP), Tohoku Gakuin University (JP), Osaka Health Science University (JP), Institute of Space and Astronautical Science (JP), The University of Tokyo (JP), Kindai University (JP), Chuo University (JP), The University of Osaka (JP)
Japan Society for the Promotion of Science
Climate action
Openalex Percentile: Top 92%
Advanced X-ray Imaging Techniques
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.