Speaker
Description
Hybrid pixel semiconductor detectors of the Timepix family have foundpractical applications in basic and applied research such as nuclear and high-energy physics, biomedical imaging, material analysis and space weather monitoring. The detectors are fabricated with several types of semiconductor sensors according to varying requirements. Usually, Si is used for detector fabrication, followed by the high-density materials CdTe and GaAs suitable for gamma-ray detection. The latest new sensor material is SiC which provides high radiation hardness and wide temperature operation. In 2022, we prepared the first Timepix type detector equipped with SiC sensor [1]. The 80 µm thick epitaxial layer on 350 µm thick substrate made of 4H- (four-hexagonal polytype) SiC was used for pixel structure fabrication. This material exhibits excellent physical and chemical stability, high breakdown voltage (4 MVcm-1), high carrier saturation velocity (2 x10e7 cm.s-1), high atomic displacement energy (20-35 eV) leading to high radiation hardness and a wide bandgap (3.27 eV at 300 K) ensuring low leakage current and enabling high temperature operation [2].
The Timepix3 detector with a 4H-SiC sensor can find applications in fast neutron detection. The pixelated structure of detector enabling the particle track recognition might be useful for filtering the neutron response events in mixed radiation field around neutron sources, The content of carbon in sensor structure brings new reaction for neutron interaction with thresholds different from interaction on silicon, which can be helpful in neutron energy range determination The high temperature stability of the sensor is also advantage.
We tested the 4H-SiC (65 µm thick radiation sensitive volume) Timepix3 detectors to monoenergetic 14 MeV neutrons at well-defined referential neutron facilities, the Van de Graaff (VdG) accelerator at the IEAP CTU in Prague and a neutron generator at the DANAIDE facility at IRESNE of CEA in Cadarache. The neutrons were produced via D-T reaction. The 4H-SiC Timepix3 detector was placed next to a Timepix2 detector with a 500 µm thick Si sensor facing the target so that both were hit by neutrons with equal flux and the same energy of 14 MeV at DANAIDE and 14.5MeV at VdG facility. The Data Processing Engine [3] was used for particle track characterization and data analysis. The parameters for track filtration were designed based on expected neutron interactions in the sensor materials. The measured neutron response events were compared between the 4H-SiC and the Si sensors and their ratio correlates with the theoretical value resulting from the sensor parameters and cross sections for interactions of neutrons of given energy. The 4H-SiC Timepix3 detector registered 0.25 filtered events/cm2s and the Si Timepix2 detector registered 136 filtered events/cm2s but with 7.7 times thicker sensor of different atomic composition influencing the interaction probability.
[1] B. Zat'ko et al JINST 17 (2022) C12005
[2] N. Gal et al Applied Surface Science 635 (2023) 157708
[3] M. Lukas et al JINST 19 (2024) C04026
Acknowledgement: This work was partially supported by grants of the Slovak Research and Development Agency APVV-22-0382 and DS-FR-22-0012. We acknowledge the Van-de-Graaff accelerator facility of CTU in Prague and the DANAIDE facility of the CEA/IRESNE in Cadarache for enabling the experiments.
| Workshop topics | Sensor materials, device processing & technologies |
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