Presentation #206.06 in the session New Mission Concepts — iPoster Session.
The LargE Area Polarimeter, or LEAP, is a proposed mission concept that would deploy a Compton scatter polarimeter as an external payload on the ISS in 2027. LEAP is designed to make the most sensitive polarization measurements to date of the prompt gamma-ray emission from a large sample of Gamma-Ray Bursts (GRBs). LEAP consists of a single science instrument—a wide Field-of-View (FOV) polarimeter that measures GRB polarization over the energy range from 50–500 keV and simultaneously performs spectroscopy from 20 keV to 5 MeV. LEAP’s large FOV of ±75° (1.5π sr) allows it to continuously monitor the sky for GRBs, ensuring that a significant number of GRBs are observed over the 3-year mission lifetime. The GRB location on the sky can be determined based on the relative response of the 420 independent CsI(Tl) scintillator elements, that, along with 588 plastic scintillator elements, make up the polarimeter. Detailed simulations using GEANT4 have been developed to determine both the spectral and polarization response of the instrument design. Background simulations incorporate the various components of the natural radiation environment and the presence of Soyuz spacecraft, each of which carries an intense gamma-ray source that is part of an altimeter system used during its return to Earth. A summary of these simulations and the response characteristics of LEAP will be presented.