Diamond, as a wide band-gap semiconductor material, has the potential to be exploited under a wide range of extreme operating conditions, including those used for radiation detectors. The radiation tolerance of a single-crystal chemical vapor deposition (scCVD) diamond detector was therefore investigated while heating the device to elevated temperatures. In this way, operation under both high-temperature and high-radiation conditions could be tested simultaneously. To selectively introduce damage in small areas of the detector material, a 5 MeV scanning proton microbeam was used as damaging radiation. The charge collection efficiency (CCE) in the damaged areas was monitored using 2 MeV protons and the ion beam induced charge (IBIC) technique, indicating that the CCE decreases with increasing temperature. This decreasing trend saturates in the temperature range of approximately 660 K, after which CCE recovery is observed. These results suggest that the radiation hardness of diamond detectors deteriorates at elevated temperatures, despite the annealing effects that are also observed. It should be noted that the diamond detector investigated herein retained its very good spectroscopic properties even at an operation temperature of 725 K (≈2% for 2 MeV protons).

We report on the systematic characterization of the optical properties of diamond color centers based on Pb impurities. An ensemble photoluminescence analysis of their spectral emission was performed at different excitation wavelengths in the 405–520 nm range and at different temperatures in the 4–300 K range. The series of observed spectral features consist of different emission lines associated with Pb-related defects. Finally, a room-temperature investigation of single-photon emitters under 490.5 nm laser excitation is reported, revealing different spectral signatures with respect to those already reported under 514 nm excitation. This work represents a substantial progress with respect to previous studies on Pb-related color centers, both in the attribution of an articulated series of spectral features and in the understanding of the formation process of this type of defect, thus clarifying the potential of this system for high-impact applications in quantum technologies.

The response of a single crystal Chemical Vapor Deposition (scCVD) diamond detector was studied with 14.1 MeV neutron and 440 keV γ-rays from room temperature down to 46 K. Induced charge in the detector was acquired using both a charge and current sensitive preamplifier to analyze the charge collection efficiency (CCE) and transient current (TCT) profiles. A similar decreasing trend of the detector CCE was observed for all types of radiation, however, with different critical temperatures and magnitudes. The detector CCE for 440 keV γ-rays decreased to 86.2 ± 0.5 % while at 70 K, the CCE for neutrons was at 50 %. The final magnitude of the detector CCE decrease for neutron radiation could not be calculated since the signal was indistinguishable from the background below 70 K. The pulse shapes of the transient currents were also investigated for both neutron and γ-rays. Pulse shapes along with discrimination techniques were benchmarked with datasets acquired at 120 K and at 55 K. Discrimination between neutron and γ-ray TCT pulse shapes was achieved at 120 K, however due to the low signal to noise ratio of pulses at 55 K, discrimination was not possible. The drop in the CCE at low temperatures decreases the signal to noise ratio which increases the impact of noise on the shape of the signal and consequently, sets a lower limit to the detectable neutron energy.