Particle and Astroparticle Physics Seminar

The All Sky Medium Energy Gamma-ray Observatory (AMEGO):
A Powerful Tool for Unlocking the MeV Sky

Sean Griffin

Goddard Space Flight Center
NASA

The region of the electromagnetic spectrum between a few hundred keV and 100 MeV has had limited astrophysical observations due to the challenging nature of detecting gamma rays. One such challenge is that across this energy band there are two competing physical processes: Compton scattering at lower energies and pair-production at higher energies, with a crossover at a few MeV. This regime, known as the MeV gap, has been largely unexplored since the pioneering measurements made by COMPTEL aboard CGRO (1991-2000). The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a wide-field gamma-ray telescope with sensitivity from ~200 keV to above 10 GeV. AMEGO will provide an order-of-magnitude increase in sensitivity over previous measurements made in the MeV band, be sensitive to polarization, and have sufficiently high energy resolution for spectroscopic measurements of nuclear emission lines. AMEGO comprises four subsystems: a plastic anticoincidence detector for vetoing cosmic ray events, a double-sided silicon tracker for measuring particle tracks, a segmented cadmium-zinc-telluride (CZT) calorimeter for measuring the direction and energy of Compton scattered photons, and a hodoscopic CsI calorimeter for measuring the position and energy of pair-production events. In this presentation I will provide an overview of the AMEGO mission concept, discuss several of the science topics addressable by AMEGO, and provide details on a prototype instrument currently under development.