[formula omitted]: Challenge of 50 kg-class satellite to open up MeV gamma-ray astronomy.

Waseda University and Tokyo Tech are developing a 50 kg-class small satellite, tentatively named INnovative Space Probe for Imaging R-process Emission (I N S P I R E), which is scheduled for launch in 2027. The primary detector of the satellite is a BOX-type Compton Camera (CC-Box) that enables to observe low energy gamma rays (30 keV − 200 keV) in pinhole mode and high energy gamma rays (150 keV − 3 MeV) in Compton mode. The CC-Box consists of a pixelized Ce:GAGG scintillator array using a depth-of-interaction (DOI) structure, which is optically coupled to an MPPC array. The Ce:GAGG arrays are also positioned on the side of detector to enhance its sensitivity. Herein, we describe the detailed design of the CC-Box, its data processing flow, and its weight and power specifications. We then assess the anticipated performance of the detector in terms of continuum and line sensitivities, together with a simulation of the Crab nebula observation. Finally, a brief review of the experimental results is performed using hands-on devices already implemented in nuclear medicine and atmospheric observations, such as gamma-ray imaging of thunderclouds. [ABSTRACT FROM AUTHOR]