Nuclear emulsion detector for large-area, high-angular-resolution gamma-ray telescope

H. Rokujo, S. Akita, Y. Isayama, A. Iyono, M. Komatsu, T. Nakano, T. Nakamura, M. Nakamura, Y. Nakamura, H. Minami, O. Sato, K. Sugimura, I. Usuda and S. Yamamoto

The Fermi Gamma-ray Space Telescope has surveyed the sub-GeV/GeV gamma-ray sky and provided a large amount of data. However, observation remains difficult owing to the lack of angular resolution, and new issues have arisen. We started up a precise gamma-ray observation project, Gamma-Ray Astro-Imager with Nuclear Emulsion (GRAINE), using balloon-borne emulsion gamma-ray telescopes to enable high angular resolution (0.1 degrees at 1 GeV), polarizationsensitive, and large-aperture observations (10 m2 ) in the 0.01–100 GeV energy region. In the last balloon experiment, which was performed in 2018, we succeeded in the first detection of a celestial gamma-ray object, Vela pulsar, via the balloon-borne emulsion telescope, and the world’s highest angular resolution was demonstrated. We start the scientific observation phase by enlarging the aperture area, extending the flight duration, and repeating balloon flights. The GRAINE 2023 balloon experiment was conducted in April 2023. The experiment aims at the observation of Vela pulsar, the Galactic center, etc. in the GeV energy region, and the survey of transient phenomena by the largest aperture area telescope. In preparation for GRAINE 2023, the new facility constructed at Nagoya University was used to produce nuclear emulsion, completing a 750 m2 emulsion films, the largest area of all the experiments using Nagoya-made emulsion. In this presentation, we report on the emulsion detector for gamma-ray measurement and its technology, as well as the latest status of GRAINE 2023.

Proceedings of Science

POS

444

933

1

8

DOI: https://doi.org/10.22323/1.444.0933

https://pos.sissa.it/444/933/pdf