First overnight balloon flight of the GRAINE 2023 emulsion gamma-ray telescope enabled by a large-scale pressure-vessel gondola

@misc{rokujo2026first,
  title = {{First overnight balloon flight of the GRAINE 2023 emulsion gamma-ray telescope enabled by a large-scale pressure-vessel gondola}},
  author = {Hiroki Rokujo and Shigeki Aoki and Takashi Azuma and Hirotaka Hayashi and Yudai Isayama and Atsushi Iyono and Takumi Kato and Tsuyoshi Kawahara and Koichi Kodama and Ryosuke Komatani and Masahiro Komatsu and Masahiro Komiyama and Hideyuki Minami and Kunihiro Morishima and Fumiya Murakami and Shogo Nagahara and Naotaka Naganawa and Mitsuhiro Nakamura and Tomoaki Nakamura and Yuya Nakamura and Noboru Nakano and Toshiyuki Nakano and Kazuma Nakazawa and Miyuki Oda and Kazuhiro Okamoto and Osamu Sato and Kai Shimizu and Amon Suganami and Yuki Sugi and Kou Sugimura and Satoru Takahashi and Ikuya Usuda and Saya Yamamoto and Jun Yamashita and Mayu Yamashita and Shoma Yoneno and Masahiro Yoshimoto},
  howpublished = {arXiv},
  year = {2026},
  month = aug,
  doi = {10.48550/arxiv.2608.29050},
  eprint = {2608.29050},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2608.29050},
}

TY  - UNPB
TI  - First overnight balloon flight of the GRAINE 2023 emulsion gamma-ray telescope enabled by a large-scale pressure-vessel gondola
AU  - Hiroki Rokujo
AU  - Shigeki Aoki
AU  - Takashi Azuma
AU  - Hirotaka Hayashi
AU  - Yudai Isayama
AU  - Atsushi Iyono
AU  - Takumi Kato
AU  - Tsuyoshi Kawahara
AU  - Koichi Kodama
AU  - Ryosuke Komatani
AU  - Masahiro Komatsu
AU  - Masahiro Komiyama
AU  - Hideyuki Minami
AU  - Kunihiro Morishima
AU  - Fumiya Murakami
AU  - Shogo Nagahara
AU  - Naotaka Naganawa
AU  - Mitsuhiro Nakamura
AU  - Tomoaki Nakamura
AU  - Yuya Nakamura
AU  - Noboru Nakano
AU  - Toshiyuki Nakano
AU  - Kazuma Nakazawa
AU  - Miyuki Oda
AU  - Kazuhiro Okamoto
AU  - Osamu Sato
AU  - Kai Shimizu
AU  - Amon Suganami
AU  - Yuki Sugi
AU  - Kou Sugimura
AU  - Satoru Takahashi
AU  - Ikuya Usuda
AU  - Saya Yamamoto
AU  - Jun Yamashita
AU  - Mayu Yamashita
AU  - Shoma Yoneno
AU  - Masahiro Yoshimoto
PY  - 2026
DA  - 2026/08/29
PB  - arXiv
DO  - 10.48550/arxiv.2608.29050
UR  - https://arxiv.org/abs/2608.29050
AB  - The Gamma-Ray Astro Imager with Nuclear Emulsion (GRAINE) project conducts precision observations of sub-GeV--GeV cosmic gamma rays using a balloon-borne nuclear-emulsion telescope with high angular resolution. In GRAINE 2023, a 2.5-m^2 telescope was flown in the project's first overnight balloon flight, including observation periods for the Vela pulsar and Galactic center region. To operate the telescope under the low-pressure and low-temperature stratospheric environment, the balloon-style pressure-vessel concept was scaled up to a lightweight gondola with an internal length of 4.9 m. A new aluminum-alloy ring structure and a lightweight membranous-shell material, SHL-300MDL, were developed. While the telescope aperture was increased by a factor of 6.6 over GRAINE 2018, the pressure-vessel gondola mass was limited to 179 kg. Ground tests of the completed flight assembly demonstrated a differential pressure above 100 hPa at room temperature and at a mean temperature of −66.0^∘C. The payload was launched from Alice Springs, Australia, in April 2023 and achieved a total flight duration of approximately 27 h, including 24.3 h of level flight. Although the upper membranous shell reached approximately −60^∘C at night, the vessel internal pressure remained above the required 100 hPa throughout level flight. These results demonstrate that the developed gondola can accommodate a 2.5-m^2 emulsion gamma-ray telescope and maintain the required pressure during overnight stratospheric flight. Scientific analyses of astrophysical and atmospheric gamma rays, including dedicated analysis of the Galactic center region, are ongoing using the recovered emulsion data. This development provides a technical basis for repeated observations with future large-area GRAINE telescopes.
ER  -