* Astronomy

Title: HX-POL - A Balloon-Borne Hard X-Ray Polarimeter
Authors: H. Krawczynski (1), A. Garson III (1), Q. Li (1), M. Beilicke (1), P. Dowkontt (1), E. Wulf (2), J. Kurfess (2), E. Novikova (2), G. De Geronimo (3), M. G. Baring (4), A. K. Harding (5), J. Grindlay (6), J. S. Hong (6) ((1) Washington University in St. Louis and McDonnel Centre for the Space Sciences, St. Louis, MO, (2) High-Energy Space Environment Branch, Naval Research Laboratory, Washington, DC, USA, (3) Instrumentation Division, Brookhaven National Laboratory, Upton, NY, USA, (4) Department of Physics & Astronomy, Rice University, Houston, TX, USA, (5) Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA, (6) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA)
(Version v2)

We report on the design and estimated performance of a balloon-borne hard X-ray polarimeter called HX-POL. The experiment uses a combination of Si and Cadmium Zinc Telluride detectors to measure the polarization of 50 keV-400 keV X-rays from cosmic sources through the dependence of the angular distribution of Compton scattered photons on the polarization direction. On a one-day balloon flight, HX-POL would allow us to measure the polarization of bright Crab-like sources for polarization degrees well below 10%. On a longer (15-30 day) flight from Australia or Antarctica, HX-POL would be be able to measure the polarization of bright galactic X-ray sources down to polarization degrees of a few percent. Hard X-ray polarisation measurements provide unique venues for the study of particle acceleration processes by compact objects and relativistic outflows. In this paper, we discuss the overall instrument design and performance. Furthermore, we present results from laboratory tests of the Si and CZT detectors.

Read more (1758kb, PDF)