A Balloon‐Borne Gamma‐Ray Polarimeter for Gamma‐Ray Bursts
We have developed a design for a hard X‐ray polarimeter operating in the energy range from 50 to 500 keV. This modular design, known as GRAPE (Gamma‐Ray Polarimeter Experiment), was successfully demonstrated with partially polarized gamma‐ray sources in the lab and fully polarized photon beams at Argonne National Laboratory. In June of 2007, a GRAPE engineering model flew on a high altitude balloon flight which demonstrated the design and collected background data. A much larger payload is currently under development that will provide a significant level of sensitivity for gamma‐ray bursts on a long‐duration balloon flight. The first balloon flight of the full GRAPE instrument is currently scheduled to take place in the Fall of 2011 from Ft. Sumner, NM.