A high-energy Compton polarimeter for the POET SMEX mission

Abstract

The primary science goal of the Polarimeters for Energetic Transients (POET) mission is to measure the polarization of gamma-ray bursts over a wide energy range, from X rays to soft gamma rays. The higher-energy portion of this band (50 -500 keV) will be covered by the High Energy Polarimeter (HEP) instrument, a non-imaging, wide field of view Compton polarimeter. Incident high-energy photons will Compton scatter in low-Z, plastic scintillator detector elements and be subsequently absorbed in high-Z, CsI(Tl) scintillator elements; polarization is detected by measuring an asymmetry in the azimuthal scatter angle distribution. The HEP design is based on our considerable experience with the development and flight of the Gamma-Ray Polarimeter Experiment (GRAPE) balloon payload. We present the design of the POET HEP instrument, which incorporates lessons learned from the GRAPE balloon design and previous work on Explorer proposal efforts, and its expected performance on a two-year SMEX mission.

High energy polarimetry of prompt GRB emission

“…This project has provided the basis for several space-borne GRB polarimeter concepts. POET (POlarimeters for Energetic Transients) was proposed in both 2008 (Hill et al, 2007;McConnell et al, 2009) and 2014 (Bloser et al, 2014;McConnell et al, 2014a) as a NASA Small Explorer (SMEX) mission. In both cases, the payload consisted of a high energy (50-500 keV) Compton scatter polarimeter and a low energy (2-15 keV) photoelectric polarimeter.…”