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X-Ray Polarimetry Workshop SLAC, Stanford, California 9-11 February 2004 |
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Development of Gamma-ray Polarimeters in Japan and the Soft Gamma-ray Detector (SGD) for the NeXT mission
Tadayuki
Takahashi
ISAS/JAXA
takahasi@astro.isas.jaxa.jp
Tadayuki Takahashi, Yasushi Fukazawa, Tuneyoshi Kamae, Jun Kataoka, Kazuo Makishima, Kazuhiro Nakazawa, Masaharu Nomachi, Hiroyasu Tajima, Makoto Tashiro, Yukikatsu Terada, and the SGD team
In the energy range above hundred keV (sub MeV region), shielding against background photons becomes important yet difficult. In order to achieve unprecedented sensitivity in this energy range, we have proposed a new detector called the Soft Gamma-ray Detector (SGD) for the NeXT mission, which utilizes the idea of a narrow FOV Compton telescope. In the SGD, we combine a stack of Si strip detectors and CdTe pixel detectors, to form a Compton telescope, which is mounted inside the bottom of the well-type active shield. By having a narrow FOV, and by requiring the Compton ring of a valid aperture gamma-ray event to intersect with the FOV, we can reject most of the background events, including the background from radio-activation of the detector materials. One important feature of the SGD is the capability of measuring polarization of incident gamma-rays from the azimuthal distribution of Compton scattered photons. In this presentation, we report the concept and expected performance of the SGD together with the results obtained with the prototype Si/CdTe Compton telescope. The recent activities of the development of gamma-ray polarimeters in Japan will also be discussed.
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For more information, contact
Jennifer Formichelli |
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