Poster Presentation

The Polarimetric Performance of the COmpton Spectrometer and Imager(COSI)

Chien-Ying Yang (NTHU), Hsiung-Kuang Chang (NTHU), Steven E. Boggs (UC Berkeley)

The COmpton Spectrometer and Imager (COSI), known as the Nuclear Compton Telescope (NCT) before, is a balloon-borne soft gamma-ray (0.2-5 MeV) telescope. COSI consists of twelve germanium strip detectors that are 3D position-sensitive. NCT had a successful balloon flight in 2009, and the upgraded instrument as COSI will be launched for an ultra-long duration balloon (ULDB) flight (60-100 days) in Antarctica in December, 2014.

In the 2014 ULDB flight, our main targets are Gamma-ray bursts (GRB), which are expected to be observed more than once in our observation depending on its fluence and the flight duration. As a Compton telescope, COSI is intrinsically sensitive to polarization. To assess COSI’s polarization performance, we calibrated the polarization detection by comparing the data in the laboratory and the Monte-Carlo simulations.