HARPO: beam characterization of a TPC for gamma-ray polarimetry and high angular-resolution astronomy in the MeV-GeV range

TL;DR

HARPO demonstrates that a time projection chamber can effectively measure gamma-ray polarization with high angular resolution and sensitivity in the MeV-GeV range, confirmed through recent beam tests.

Contribution

This paper introduces the HARPO TPC prototype and validates its performance for gamma-ray polarimetry in the MeV-GeV range through experimental beam tests.

Findings

HARPO achieved excellent angular resolution in gamma-ray measurements.

The TPC demonstrated high sensitivity to gamma-ray polarization.

Beam tests confirmed the prototype's suitability for high-precision gamma-ray astronomy.

Abstract

A time projection chamber (TPC) can be used to measure the polarization of gamma rays with excellent angular precision and sensitivity in the MeV-GeV energy range through the conversion of photons to e+e- pairs. The Hermetic ARgon POlarimeter (HARPO) prototype was built to demonstrate this concept. It was recently tested in the polarized photon beam at the NewSUBARU facility in Japan. We present this data-taking run, which demonstrated the excellent performance of the HARPO TPC.