Array of X and gamma ray scintillator detector for space gamma ray telescope application

摘要

The instruments on board the latest gamma observatories (INTEGRAL, AGILE, GLAST) combines technologies based either on solid state or on scintillator detector, the first one being favorite when a low energy threshold and a good energy resolution is required, the latter being more convenient for large volume when worse performance are still acceptable. With the development of new scintillator materials and even more with new low-noise ligth readout devices the differences between the two techniques are narrowing and for some application the cheaper scintillator detector can compete with solid state devices. Furthermore both these detector concepts can be combined in a single compact device by means of the Pulse Shape Discrimination (PSD) technique that allows to discriminate direct interactions in silicon from scintillation events. Combined in arrays they can be the base for position senstive planes to be combined with coded mask in imaging instruments or the component of new generation Compton based telescopes. For this purpose two prototype systems have been designed and realized, both based on a 20 channels Silicon Drift Detectors (SDD) monolithic array coupled to individual 1 cm thick CsI(Tl) scintillator crystals. In the first system the detector readout is implemented with ASICs tailored specifically to the SDD readout, while in the second system the PSD readout of the array is implemented. The performance of these kind of detectors tested in the various prototypes as well as their applications in new generation space telescopes are discussed.