Development of a hard X-ray polarimeter for astrophysics

We have been developing a Compton scatter polarimeter for measuring the lin ear polarization of hard X-rays (100-300 keV) from astrophysical sources. A laboratory prototype polarimeter has been used to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. Our design concep t places a self-contained polarimeter module on the front-end of a a 5-inch position-sensitive PMT (PSPMT), We are currently working on the fabricatio n of a science model based on this PSPMT concept. Although the emphasis of our development effort is towards measuring hard X-rays from solar flares, our design has the advantage that it is sensitive over a rather large field -of-view (> 1 steradian), a feature that makes it especially attractive for gamma-ray burst studies.