Silicon drift photodiode array detectors

Silicon drift photodiodes have been constructed in a two-dimensional array format for the purpose of position sensitive detection. The arrays are dimensioned 4 x 4, with pixel size 3 mm x 3 mm, and are intended to be used with discrete-channel readout electronics. This aspect of the design limits the overall array dimension in future prototype versions to approximately 10 x 10, but allows for higher total count rates than multiplexed or serial-read arrays. The photodiode arrays use the floating cathode ring design described by others. The design reported here, however, differs in that these devices have been specifically processed to maximize the detection efficiency of visible light. This feature makes these detectors attractive for use in position-sensitive scintillator readout. Measurements are presented using these photodiodes coupled to common scintillator crystals to detect gamma-rays. Measurements are also shown using these photodiodes to directly detect low energy X-rays. Typical room temperature noise (ENC) measured in the prototype arrays is 60 electrons rms.