The material requirements for a room temperature operated high resolution semiconductor gamma ray spectrometer include large free charge carrier mobilities, or alternatively, high achievable free charge carrier velocities, long mean free drift times, a relatively large energy band gap, high representative values of atomic number, and availability of large volumes. Presently, no semiconductor has all of the listed ideal material properties desired for the “perfect” room temperature operated semiconductor radiation spectrometer. One difficult problem to resolve with these materials is gamma ray energy resolution degradation from charge carrier trapping losses. Due to problems with scattered gamma rays blurring the images, heavy metal collimators are often used in conjunction with an imaging detector. The collimator significantly reduces the detection of gamma rays that originate or scatter from locations that are not directly aligned with the collimator, and requires to be attached to the detector array after the device array has been constructed.
Researchers at the University of Michigan have developed a collimated gamma ray detector assembly, an array of collimated radiation detectors and a collimated radiation detector module, which achieve high gamma ray energy resolution and collimation for imaging capability. A conductive metal structure acts as an electromagnetic shield to produce the Frisch grid effect in a solid-state detector crystal or substrate of a detector. The structure may be a single structure or can be stacked to produce a gamma ray imaging array. The structure improves the gamma ray energy resolution response while at the same time serving as a gamma ray directional collimator. The assemblies, arrays and module can be manufactured from a variety of materials, including common semiconductors such as silicon, germanium, and cadmium-zinc-telluride.
Applications and Advantages
- Collimated radiation detection.
- Improved gamma ray energy resolution response.
- May be manufactured from a variety of materials, including common semiconductors.