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

Hirofumi Noda; Mio Aoyagi; Koji Mori; Hiroshi Tomida; Hiroshi Nakajima; Takaaki Tanaka; Hiromasa Suzuki; Hiroshi Murakami; Hiroyuki Uchida; Takeshi G. Tsuru; Keitaro Miyazaki; Kohei Kusunoki; Yoshiaki Kanemaru; Yuma Aoki; Kumiko K. Nobukawa; Masayoshi Nobukawa; Kohei Shima; Marina Yoshimoto; Kazunori Asakura; Hironori Matsumoto; Tomokage Yoneyama; Shogo B. Kobayashi; Koichi Hagino; Hideki Uchiyama; Kiyoshi Hayashida

doi:10.1117/12.3017877

21 August 2024 New CCD driving technique to suppress anomalous charge intrusion from outside the imaging area for soft x-ray imager of Xtend onboard XRISM

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

Author Affiliations +

Proceedings Volume 13093, Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray; 130935X (2024) https://doi.org/10.1117/12.3017877
Event: SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, Japan

Conference Poster

Abstract

The Soft X-ray Imager (SXI) is an X-ray 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 electrode at the top of the imaging area. To prevent anomalous charge intrusion and maintain 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 charge injection. In this paper, 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 investigation experiments to identify the source of the anomalous charges.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

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Hirofumi Noda, Mio Aoyagi, Koji Mori, Hiroshi Tomida, Hiroshi Nakajima, Takaaki Tanaka, Hiromasa Suzuki, Hiroshi Murakami, Hiroyuki Uchida, Takeshi G. Tsuru, Keitaro Miyazaki, Kohei Kusunoki, Yoshiaki Kanemaru, Yuma Aoki, Kumiko K. Nobukawa, Masayoshi Nobukawa, Kohei Shima, Marina Yoshimoto, Kazunori Asakura, Hironori Matsumoto, Tomokage Yoneyama, Shogo B. Kobayashi, Koichi Hagino, Hideki Uchiyama, and Kiyoshi Hayashida "New CCD driving technique to suppress anomalous charge intrusion from outside the imaging area for soft x-ray imager of Xtend onboard XRISM", Proc. SPIE 13093, Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 130935X (21 August 2024); https://doi.org/10.1117/12.3017877

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