A gamma-ray burst monitor fot the CALorimetric Electron Telescope (CALET) is under development. The aim of the CALET GRB Monitor (CALET-GBM) is to obtain a wide-band energy spectrum of GRB over an unprecedented nine decades in energy (from several keV to a few TeV) together with the CALET Imaging Calorimeter (IMC) and the Total Absorption Calorimeter (TASC). The GBM is under designing so as to have a sensitivity from several keV to 20 MeV. Furthermore our undergoing plan is to use six LaBr3(Ce) crystals from several keV to about 1 MeV measurement (one BGO for higher energy), in which light yield is about twice as large as that of NaI(Tl). LaBr3(Ce) is very attractive material, but this crystal has not been used yet as a detector for long exposure in space. Therefore its radiation hardness and proton induced background due to incoming protons are not fully understood. To evaluate its performance in high radiation environment of ISS orbit, we carried out proton beam irradiation tests. Proton- induced radioactive gamma-rays were measured from a few minutes after the irradiation to a period longer than two months by a Germanium detector, and most of radioactive nuclei induced by protons are identified. We have manufactured a proto-type model of LaBr3(Ce) that is of 3 inch diameter and half inch thick with 220 μm beryllium entrance window. In preliminary measurements, 6.4 keV Fe Kα fluorescence line is clearly detected. We expect that the lower energy threshold is around 4 ke V or even lower.
|Number of pages||4|
|Journal||Journal of the Physical Society of Japan|
|Issue number||SUPPL. A|
|Publication status||Published - 2009|
ASJC Scopus subject areas
- Physics and Astronomy(all)