Spiral silicon drift detectors

An advanced large-area silicon photodiode and X-ray detector, called the spiral drift detector, was designed, produced, and tested. The detector has a very small capacitance of about 0.1 pF and a leakage current under 1 nA at room temperature. All electrons generated at the silicon-silicon oxide interface are collected on a guard rather than contributing to the detector leakage current. The decrease of the leakage current reduces the parallel noise of the detector. This decrease and the very small capacitance of the detector anode with a capacitively matched preamplifier may improve the energy resolution of spiral drift detectors operating at room temperature to about 50 electrons RMS. This resolution is in the range attainable at present only by cooled semiconductor detectors