Methods for optimizing the performances of position-sensitive CsI(Tl) scintillation bars with photodiode readout
The technique of using position-sensitive scintillating bar detectors for gamma-ray telescopes operating in the range 0.3-20 MeV can take advantage of recent progress in the technology of photodiodes and their related electronics. By assembling together several bars it is possible to realize a 3D position-sensitive detector with good background rejection capability, and consequently to improve the telescope sensitivity. The reconstructed energy and spatial resolution of the interacting gamma photon as well as the operational energy threshold are dependent upon the signal to noise ratio of the overall photodiode-electronic chain and change along the bar. Optimization of spatial and energy resolutions with respect to scintillation light attenuation characteristics and length of the bar are discussed. Furthermore, in order to extend the operational range to low energies, (under 300 keV) different methods to lower the signal acceptance threshold are examined and compared with data from experimental tests.