Paper 13093-300
Prototype fine-imaging narrow field of view semiconductor Compton telescope with shielded coded-mask, mini-SGI
Abstract
Semiconductor Compton telescope (SCT) is one of the promising technologies in cosmic MeV gamma-ray observation, because of good angular resolution measure thanks to its high energy and positional resolutions. However, it cannot be better than a few degrees because of quantum limitation, known as doppler broadening. With improving sensitivity in MeV astronomy, realization of 10-arcmin-level of angular resolution is becoming more important. Combining a coded-aperture mask imaging to SCT is the simplest measure to obtain this level of angular resolution in MeV astronomy. Since the mask made of heavy metal is a BGD source and contribution from bright sources and CXB limits the statistical significance of the mask decoding, we propose the concept of attaching a coded mask to a narrow-field Si/CdTe SCT such as the SGD on the ASTRO-H mission. We developed a concept verification system, mini-SGI, adopting 0.5 mm thick DSSDs and 2 mm thick CdTe-DSD, covered with BGO active shield. By irradiating a 133Ba source, we succeeded to obtain 1° resolution coded-mask imaging applied to Compton reconstructed image with ARM resolution of 9.8 degree and 3.0 degree to 81 keV and 356 keV lines, respectively.
Presenter
Keigo Okuma
Nagoya Univ. (Japan)
Keigo Okuma is a Ph.D. student at Nagoya University. His work focuses on the development and evaluation of MeV gamma-ray detectors for high-energy astrophysics, and observational study of on-ground thunderstorm gamma-ray observations. He uses CdTe double-sided strip detectors and DSSDs, as well as scintillation detectors. He is also a COSI team member.