MeV Astrophysical Spectroscopic Surveyor (MASS): A Compton Telescope Mission Concept

TL;DR

The MASS mission concept proposes a large-area Compton telescope with CZT detectors for MeV gamma-ray spectroscopy, aiming to study nucleosynthesis and high-energy astrophysics with high sensitivity and potential for mini-satellite deployment.

Contribution

It introduces a novel large-area Compton telescope design using 3D CZT detectors optimized for emission line detection, including a pathfinder mission for testing.

Findings

Achieves 0.6% energy resolution at 0.662 MeV

Line sensitivity of about 10^-5 photons cm^-2 s^-1 with 1 Ms observation

Potential for micro- or mini-satellite deployment

Abstract

We propose a future mission concept, the MeV Astrophysical Spectroscopic Surveyor (MASS), which is a large area Compton telescope using 3D position sensitive cadmium zinc telluride (CZT) detectors optimized for emission line detection. The payload consists of two layers of CZT detectors in a misaligned chessboard layout, with a total geometric area of 4096 cm$^2$ for on-axis observations. The detectors can be operated at room-temperature with an energy resolution of 0.6\% at 0.662 MeV. The in-orbit background is estimated with a mass model. At energies around 1 MeV, a line sensitivity of about $10^{-5}$ photons cm$^{-2}$ s$^{-1}$ can be obtained with a 1 Ms observation. The main science objectives of MASS include nucleosynthesis in astrophysics and high energy astrophysics related to compact objects and transient sources. The payload CZT detectors weigh roughly 40 kg, suggesting that it can be integrated into a micro- or mini-satellite. We have constructed a pathfinder, named as MASS-Cube, to have a direct test of the technique with 4 detector units in space in the near future.