Photon-Counting detectors

Inductive Direct-Conversion Radiation Detectors

The inductive conversion method is based on the detection of the inductive load on the coil by the charge carriers produced in the semiconductor by the high energy radiation (X-ray, Gamma-ray) rather than collection of these charges at the electrodes by applying electrical field. This load is associated with the energy losses due to absorption of RF radiation by the radiation produced charge carriers reducing quality factor (Q) of a coil-capacitance resonant circuit.

Absorption of the radiation by the free charge carriers relates to any electromagnetic radiation, the visible light, the infrared and longer wavelengths radiation such as RF. The longer the wavelength of the electromagnetic radiation the larger contribution of the free carriers to the absorption. This contribution is approximately proportional to the square of the radiation wavelength. Therefore, while measurable free carrier contribution to the absorption of the infrared radiation requires high density of carriers (high doping), free carrier absorption of the RF radiation allows to detect number of charge carriers equivalent to that produced by a single high-energy photon.

Unlike detectors based on the photoconductive principle, inductive radiation sensing technology detects radiation generated charge carriers at the location where they are created and does not require high carrier mobility, low defect density materials and does not require high voltage biasing. Performance of inductive detectors even improves with increasing density of the defects. Therefore the use of polycrystalline materials results in a substantial increase of the readout sensitivity and energy resolution as compared to detectors based on low defect density monocrystalline materials such as high resistivity CdZnTe (CZT).

E. Kamieniecki, http://dx.doi.org/10.13140/RG.2.2.28670.23369, Patents: US 10,018,738 B2, U.S. 10,338,237 B2.