GRAINE project and first results on 2018 balloon-borne experiment

Abstract

We are developing GRAINE project, 10 MeV-100 GeV cosmic γ-ray observations with a precise (0.08 degree @ 1-2 GeV) and polarization sensitive large-aperture-area (∼10 m 2) emulsion telescope by repeating long duration balloon flights. In April 2018, we performed a balloonborne experiment with various developments, improvements and preparations, and with a 0.38 m 2 aperture and 17.4 hour flight duration in Australia to demonstrate overall performance of the telescope with a detection and imaging of a known γ-ray source, Vela pulsar. In 2021 or later, with a 10 m 2 and >∼24 hour flight duration, we aim to start scientific observations.