Possibility of Systematic Study of Supernova Explosions by Nuclear Imaging Spectroscopy

Abstract

An all-sky monitor with nuclear imaging spectroscopy is a promising tool for the systematic study of supernova explosions. In particular, progenitor scenarios of type-Ia supernovae, which are not yet well understood, can be resolved using light curves in the nuclear gamma-ray band. Here we report an expected result of an all-sky monitor with imaging spectroscopy using electron-tracking Compton camera, which will enable us to observe nuclear gamma-ray lines from type-Ia supernovae.

Time projection chambers for gamma-ray astronomy

“…The present Section addresses the extreme case for which the tracking of the electron is so precise that the analyst can use a bijection between the measured observables for a given Compton scatter event and the direction of the incoming photon (one-to-one mapping, Fig. 1 right), in a scheme that is named ETCC (electrontracking Compton camera) [Tanimori et al, 2004[Tanimori et al, , 2015[Tanimori et al, , 2017. We will see that a low-density high-precision active target, such as a gas TPC, is well suited for that purpose.…”

“…In the reconstruction method in particle physics, additional physical parameters that are not used to solve the kinematics are usually needed to suppress such a background. In MeV gamma-ray telescopes using the reconstruction of Compton scattering, residual physical parameters are considered necessary [Tanimori et al, 2017]. We have good examples.…”

“…Molecular carbonic gas is a good choice for the scatterer. CF 4 has 42 electrons in one molecule, which is nearly three times that of Si, and its low atomic number significantly suppresses the photo absorption of gamma rays in the scatterer, which is the main reason for the accidental background [Tanimori et al, 2015[Tanimori et al, , 2017. Fig.…”

“…The PSF is indicated by a black thick line; assuming a point source, the PSF is improved by weighting the SPD, as indicated by the thick green line. Adapted from [Mizumura et al, 2017]. volume using only one 2D MPGD.…”

“…For the use of gas as a scatterer, there is one serious problem: a recoil electron with an energy higher than several hundreds of keV penetrates the TPC and significantly reduces the effective area for gamma-rays above a few MeV. To overcome this problem, all absorbers were moved inside the TPC in the SMILE-2+ experiment [Mizumura et al, 2017;Takada et al, 2022], as shown in Fig. 13.…”