Gamma-ray polarimetry

Gamma-ray Polarimetry *

An astrophysics application of a low noise Double-sided Silicon Strip Detector (DSSD) is described. A Semiconductor Multiple-Compton Telescope (SMCT) is being developed to explore the gamma-ray universe in the 0.1– 20 MeV energy band. Excellent energy resolution and polarization sensitivity are key features of the SMCT. We have developed prototype modules for a low noise DSSD system, which reac...

X-ray and Gamma-ray Polarimetry

Gamma-Ray Instrument for Polarimetry, Spectroscopy

We present an instrument concept called GIPSI that uses germanium strip detectors in an imaging system to provide narrow line sensitivity < 8:0 10 6 cm 2 s 1 at 100 keV in a 2 week exposure (3 ), and which has a point spread function (spatial resolution) of approximately 20 arc minutes rms. The germanium strip detectors also make an excellent polarimeter by capitalizing on the angular dependenc...

Open issues in gamma - ray bursts : polarimetry and dark GRBs

— We review some open problems in the physics of afterglows, namely their polarization properties and the existence of dark/faint bursts. Polarization studies yield precious insights in the physical structure and dynamical evolution of GRB jets, revealing their magnetization properties and their energy profile. Polari-metric observations of GRB 020813 already allowed to exclude a homogeneous je...

Gamma-Ray Polarimetry of Two X-Class Solar Flares

We have performed the first polarimetry of solar flare emission at γ-ray energies (0.2–1MeV). These observations were performed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) for two large flares: the GOES X4.8-class solar flare of 2002 July 23, and the X17-class flare of 2003 October 28. We have marginal polarization detections in both flares, at levels of 21 ± 9% and -...