# Development of a Silicon Tracker for the All-sky Medium Energy Gamma-ray Observatory Prototype

## TL;DR

This paper discusses the development of a silicon tracker subsystem for the ComPair prototype, part of the AMEGO mission, aimed at advancing gamma-ray detection in the 200 keV to 10 GeV range.

## Contribution

It introduces the design and development details of the silicon tracker for the ComPair prototype, enhancing gamma-ray detection capabilities across a broad energy spectrum.

## Key findings

- Successful development of the silicon tracker prototype.
- Improved tracking of pair-production events.
- Enhanced measurement of Compton-scattered electrons.

## Abstract

The gamma-ray sky from several hundred keV to $\sim$ a hundred MeV has remained largely unexplored due to the challenging nature of detecting gamma rays in this regime. At lower energies, Compton scattering is the dominant interaction process whereas at higher energies pair production dominates, with a crossover at a few MeV. Thus, an instrument designed to work in this energy range must be optimized for both Compton and pair-production events. AMEGO, the All-sky Medium Energy Gamma-ray Observatory, a Probe-class mission in consideration for the 2020 decadal survey, is designed to operate at energies from $\sim$ 200 keV to $>$ 10 GeV with over an order of magnitude increase in sensitivity and with superior angular and energy resolution compared to previous instruments. AMEGO comprises four major subsystems: a plastic anti-coincidence detector for rejecting cosmic-ray events, a silicon tracker for tracking pair-production products and tracking and measuring the energies of Compton-scattered electrons, a cadmium-zinc-telluride (CZT) calorimeter for measuring the energy and location of Compton scattered photons, and a CsI calorimeter for measuring the energy of the pair-production products at high energies. A prototype instrument, known as ComPair, is under development at NASA's Goddard Space Flight Center and the US Naval Research Laboratory. In this contribution, we provide details on the development of the silicon tracker subsystem.