Technology Commercialization and Partnerships | BSA 05-11: Integrated Circuit and Grid Design for High-Resolution Detection of Radiation Events

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Category: electronics & instrumentation

BSA 05-11: Integrated Circuit and Grid Design for High-Resolution Detection of Radiation Events

BNL Reference Number: BSA 05-11

Patent Status: U.S. Patent Number 7,271,395 was issued on September 18, 2007

Summary

Block diagram of the ASIC, including three front-end channels, two for amplification of the two grid signals (collecting and non-collecting) and one for amplification and processing of the cathode signal.

his invention offers an efficient high spectral resolution co-planar grid (CPG) sensor for use in detecting ionizing radiation, measuring depth of interaction of an ionizing event, and improving resolution"all at room temperature and without complex and bulky electronics.

Description

This Application Specific Integrated Circuit (ASIC) measures the depth of interaction in CPG sensors by obtaining the differences in time between ionizing events and detection of charge. Event time-of-occurrence is measured with a comparator to time the leading edge of the event pulse at each electrode. A processor calculates a timing difference between comparator outputs for each electrode, corresponding to the depth of interaction and improving CPG sensor spectral resolution. The device includes channels for grid inputs, and may be integrated into an ASIC and the combination of the device and sensor is included. An improved high-resolution CPG "a cadmium zinc telluride CPG gamma-ray sensor operating at room temperature "has already demonstrated the efficacy of the invention.

Benefits

The charges generated by ionizing gamma radiation are subject to substantial trapping effects, and the related signals depend heavily on accounting for the depth of ionizing interactions. By configuring the electrodes to create device sensitivity to electrons only, the spectral resolution of the device can become independent of the depth of the interaction. Although the relative gain compensation technique for CPG sensors does not require complex electronics, it provides only a roughly linear, first order compensation of the trapping effects. A second, impractical disadvantage includes the need to replace hardware if the relative gain needs to be modified. The cathode amplitude signal technique can achieve better spectral resolution by implementing a higher-order compensation, but more complex electronics are required, including an additional cathode signal front-end channel and large, bulky high voltage capacitors. This high spectral resolution CPG sensor enables an efficient method f

Applications and Industries

Semiconductor radiation detectors are now used in a large variety of fields, including nuclear physics, X-ray and gamma ray astronomy, and nuclear medicine. Their imaging capabilities, good energy resolution, and the ability to fabricate compact systems are especially advantageous when compared to other types of detectors, such as gas detectors and scintillators. Further applications include medical imaging, nuclear nonproliferation, non-destructive detection, radiation imaging, and homeland security.