Coplanar-grid CdZnTe detectors for gamma-ray spectroscopy and imaging
- Lawrence Berkeley National Lab., CA (United States)
CdZnTe is a relatively new semiconductor that is being developed for use as a nuclear radiation detector. Its highly atomic numbers provide good detection efficiency for gamma rays, while its wide bandgap allows operation at room temperature. The biggest drawback of this material is its poor charge transport characteristics, especially for the holes. The coplanar-grid charge-sensing technique has been developed over the past several years as a method to circumvent this problem so that detectors with good energy resolution can be realized. The technique is based on the use of two coplanar, interdigitated anodes (grids) to sense the collection of carriers in a detector. During detector operation, a voltage is applied between the two grids so that electrons are collected only to one of the grids. The signals induced on the collecting and noncollecting grids as a result of charge collection are subtracted to give a net output signal. By adjusting the relative gain of the two signals before subtraction, the output signal can be made insensitive to the effects of both hole trapping and electron trapping. The coplanar-grid technique has been successfully applied to CdZnTe detectors, and good energy resolution ({approximately}2% full-width at half-maximum for 662-keV gamma rays) combined with high efficiency has been obtained for detectors with volumes up to 2.2 cm{sup 3}. A single-electrode readout method has also been developed in which only the collecting anode signal is processed and signal subtraction is not used. In this case, the optimization of detector response is accomplished by adjusting the relative areas of the two anodes. An attractive feature of the coplanar-grid technique, whether employing signal subtraction or single-electrode readout, is that only simple readout electronics is needed. This enables the fabrication of small, low-power detector systems that are particularly well suited for field use. The authors are currently developing coplanar-grid CdZnTe gamma-ray detectors for use in environmental remediation and nuclear safe-guards applications.
- OSTI ID:
- 298287
- Report Number(s):
- CONF-981106--
- Journal Information:
- Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 79; ISSN 0003-018X; ISSN TANSAO
- Country of Publication:
- United States
- Language:
- English
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