Development of a Hard X-Ray Polarimeter for Gamma-Ray Bursts

. We describe recent work on the development of a Compton scatter polarimeter for measuring the polarization of hard X-rays (100--300 keV) from astrophysical sources. Results from measurements with a laboratory prototype are summarized, along with comparisons to Monte Carlo simulations. We also present a new design concept that envisions a complete polarimeter module on the front end of a 5-inch position-sensitive PMT. Although the emphasis of our effort is measuring hard X-ray polarization in solar flares, our design has the advantage that it is sensitive over a rather large FoV (? 1 sr), a feature that makes the design especially attractive for fl-ray burst studies. INTRODUCTION The measurement of hard X-ray polarization in fl-ray bursts would add yet another piece of information in our effort to resolve the true nature of these enigmatic objects. Here we report on the development of a hard X-ray polarimeter for solar flares that, because of its relatively large FoV, may be useful i..