Expected performance of a hard X-ray polarimeter (POLAR) by Monte Carlo Simulation

TL;DR

This paper evaluates the expected performance of the POLAR X-ray polarimeter for gamma-ray burst polarization measurements using Monte Carlo simulations, focusing on optimizing detector design and detection capabilities.

Contribution

It provides a detailed simulation-based assessment of POLAR's performance, including key parameters like modulation factor, efficiency, and minimum detectable polarization.

Findings

POLAR can detect about 9 GRBs per year with MDP < 10%.

Optimized detector configuration meets weight constraints and science goals.

Simulation results guide the design and expected scientific output of POLAR.

Abstract

Polarization measurements of the prompt emission in Gamma-ray Bursts (GRBs) can provide diagnostic information for understanding the nature of the central engine. POLAR is a compact polarimeter dedicated to the polarization measurement of GRBs between 50-300 keV and is scheduled to be launched aboard the Chinese Space Laboratory about year 2012. A preliminary Monte Carlo simulation has been accomplished to attain the expected performance of POLAR, while a prototype of POLAR is being constructed at the Institute of High Energy Physics, Chinese Academy of Sciences. The modulation factor, efficiency and effective area, background rates and Minimum Detectable Polarization (MDP) were calculated for different detector configurations and trigger strategies. With the optimized detector configuration and trigger strategy and the constraint of total weight less than 30 kg, the primary science goal to determine whether most GRBs are strongly polarized can be achieved, and about 9 GRBs/yr can be detected with MDP < 10% for the conservative detector configuration