Abstract
Abstract
POLAR-2 is a dedicated gamma-ray polarimeter currently
foreseen to be launched towards the China Space Station around
2027. The design of the detector is based on the legacy of its
predecessor mission POLAR which was launched in 2016. POLAR-2 aims
to measure the polarization of the Gamma-ray Burst prompt emission
within the 30–800 keV energy range. Thanks to
its high sensitivity to gamma-ray polarization, as well as its large
effective area, POLAR-2 will provide the most precise measurements
of this type to date. Such measurements are key to improve our
understanding of the astrophysical processes responsible for
Gamma-Ray Bursts. The detector consists of a segmented array of
plastic scintillator bars, each one of which is read out by a
Silicon PhotoMultiplier channel. The flight model of POLAR-2 will
contain a total of 6400 scintillators. These are divided into 100
groups of 64 bars each, in so-called polarimeter modules. In recent
years, the collaboration has designed and produced the first
prototypes of these polarimeter modules and subjected these to space
qualification tests. In addition, in April 2023, the first of these
modules were calibrated using fully polarized gamma-ray beams at the
European Synchrotron Radiation Facility (ESRF) in France. In this
work, we will present the results of this calibration campaign and
compare these to the simulated performance of the POLAR-2
modules. Potential improvements to the design are also
discussed. Finally, the measurements are used, in combination with
the verified simulation framework, to estimate the scientific
performance of the full POLAR-2 detector and compare it to its
predecessor.