Orbit-Like Proton Radiation Sensitivity of CdTe Detectors: Evaluation of Mobility-Lifetime Products and Spectroscopic Properties

This article reports the proton radiation sensitivity of two 1.0-mm-thick EURORAD ohmic CdTe detectors, irradiated with a low energy proton beam generated in a positron emission tomography (PET) cyclotron facility. The CdTe crystals were exposed to a proton radiation field composed of energies of approximate to 13.8, approximate to 9.7, approximate to 5.7, and approximate to 3.3 MeV, at an average flux of similar to 10(8) protons cm(-2)s(-1), a total fluence from approximate to 2.1x10(9) up to approximate to 4.5x10(10) protons cm(-2), and an average dose from approximate to 5.9 up to approximate to 130 Gy, equivalent to the proton fluence accumulated in similar to 1 up to similar to 20 years in a low earth orbit (LEO). The impact of the proton radiation field was analyzed through its charge transport properties-the mobility-lifetime product for electrons, (mu tau) e, and holes, (mu tau)(h),-and spectroscopic properties-the energy resolution and the peak-to-valley ratio, for gamma-ray lines within 60-662 keV. The tested CdTe detectors, with (mu tau)(e) similar to 5 x 10(-4) cm(2)V(-1) and (mu tau)(h) similar to 3x 10(-5) cm(2) V-1, showed good radiation hardness, with the measured upper-limit of (mu tau)(e) and (mu tau)(h) proton fluence (average dose) sensitivity of similar to 2 x 10(-15) cm(2)V (1/)protons cm(-2) (similar to 7x10(-7) cm(2) V-1/Gy) and similar to 3x10(-16) cm(2) V-1/protons cm(-2) (similar to 1x10(-7) cm(2) V-1/Gy), respectively. Up to approximate to 130 Gy, no significant degradation of the energy resolution and the peak-to-valley ratio was observed.