Search

We have tested the radiation detection performance of silicon carbide (SiC) pin diodes originally developed as high power diodes. These devices consist of 100 micron thick 4H-SiC grown epitaxially on SiC substrates. We measured the absolute charge generated by X-rays per keV in SiC by comparing the charge generation with similar silicon devices and determined the energy required per electron hole pair in SiC to be 7.6 eV. Small devices with a diameter of 1 mm were tested and produced spectra with a room temperature energy resolution of-550 eV at 60 keV, which is consistent with the electronics limit for the capacitance of the device. This allowed us to put an upper limit to the Fano factor of 0.04. We also performed radiation damage tests on these devices and found no significant loss in charge collection up to a photon dose of 100 MRad. Applications for these devices can be found in the fields of particle physics, nuclear physics, nuclear medicine, X-ray fluorescence, X-ray astronomy and X-ray navigation

A new version of the front-end application specific integrated circuit (ASIC) for coplanar-grid sensors is presented. Compared to the first version the ASIC is optimized for signal/noise performance, modified in peaking time, and it implements timing signals to measure the depth of interaction using the grids signals only. Experimental results using state-of-the-art CPG sensors and different approaches for reducing the error due to electron trapping are reported. A new technique that makes use of the sum and difference of the grids signals is also presented

A compact time projection chamber (TPC) has been constructed for the LEGS (Laser Electron Gamma Source) experiment at BNL. The TPC uses double GEMs as the amplification stage. Position encoding is achieved through charge division using zigzag shaped anode pads. The TPC has a 35 cm diameter active area and a 50 cm long drift depth. It has more than 7000 channels of readout electronics in the form of custom designed ASICs. A novel peak sensing circuit is used to measure simultaneously the amplitude and timing of the signal peak from an anode pad. Test results from a shorter prototype version of the TPC as well as the construction of the final detector are discussed.

The peak detector derandomizer ASIC provides threshold discrimination, arbitration, peak and timing detection with analog memory, sparsification, and multiplexing for 32 input channels of analog pulse data. In this work the ASIC is characterized for high-rate operation. A new version of the ASIC, can process multiple events occurring at the same time and provides time-over-threshold measurement for pile up rejection.