Spectroscopic properties of large-volume virtual Frisch-grid CdMnTe detectors

CdMnTe(CMT) is a promising alternative material for use as a room-temperature radiation detector. Frisch-grid detectors have a simple configuration and outstanding spectral performance compared with other single-carrier collection techniques. The energy resolution of large-volume virtual Frisch-grid CMT detectors was tested by using several isotopes such as ⁵⁷Co, ²² Na, ¹³³Ba, and ¹³⁷Cs together or separately. Energy resolutions of 6.7% and 2.1% were obtained for 122-keV ⁵⁷Co and 662-keV ¹³⁷Cs gamma rays, respectively, without using any additional signal processing techniques. Also, a 12-mm-thick CMT detector detected the 511-keV and 1.277-MeV gamma peaks of ²²Na with values of the full width at half maximum (FWHM) of 2.7% and 1.5%, respectively. In addition, multiple low- and high-energy gamma peaks of ¹³³Ba were well separated. The mobilitylifetime product calculated from the shift of the 662-keV photo-peak vs. bias by using Hecht’s equation was 7 × 10 ⁻³ cm²/V. These results show the possibility of using CMT detectors in response to various requirements for gamma-ray detection at room-temperature.