Orateur
Description
In the world of semiconductors, diamond is renowned for its advantageous properties for particle detection. It is then used as a solid-state ionization chamber1. Its high displacement energy and high charge carrier mobilities allow it to be a technological solution to satisfy very high flux applications, thus accumulating large fluences.
At the Laboratory of Subatomic Physics and Cosmology (LPSC) in Grenoble (France), commercially available diamonds (sCVD electronic grade and pCVD) are converted into particle detectors read-out by dedicated electronics (developed at LPSC). As part of the ANR-DIAMMONI (20-CE42-0004) and the master Project DIAMOND at IN2P3, the response of diamond detectors, under ~70 MeV light ion beams radiation, was scrupulously studied as a function of two factors: the particle flux and the induced cumulative fluence. These studies led to the development of an ion beam monitor: the DIAMMONI detector, which is able to operate on a large dynamic range: from few tens of particles up to 1014 p/cm², that is now installed at the ARRONAX cyclotron2 in Nantes (France).
During reported experiments, single-crystal and polycrystalline diamonds were irradiated with 68 MeV protons and 64 MeV alpha particles in ARRONAX. At first, their responses with the flux are linear over a very wide range of fluxes before a saturation phenomenon appears (sCVD mainly concerned). Then, several diamond samples were irradiated using very high particle fluxes (up to 1015 p/cm2) to quantify the evolution of charge collection efficiency (CCE) as a function of the induced cumulative fluence. The measurement of this CCE was carried out simultaneously with the irradiation thanks to the pulsed beam delivery mode available from the ARRONAX cyclotron. It has been observed that, after an accumulation of 1013 p/cm², the loss of CCE is less than 10%. Beyond that, the CCE drops following an empirical law as already reported in the literature3. Finally, it was shown that the diamond had lost 90% of its CCE after being exposed to 3 1015 p/cm². However, even after being thus damaged, it has been demonstrated that diamond is still able to detect the beam pulses.
Irradiations by light ions cause atomic displacements, and thus the creation of defects in the diamonds bulk. These defects affect the CCE. To quantify with accuracy the induced damage, for the first time, a cross characterization of the irradiated samples was carried out i) at LPSC using alpha particles sources, ii) at DIAMFAB (Grenoble, France) using Raman spectroscopy, and iii) at the BM05 beam line at ESRF (Grenoble, France) using a XBIC method4. These methods highlighted the creation of Frenkel defects in the substrate.
At the last stage of the reported study, in order to investigate the possibility of regenerate the crystalline structure of the irradiated diamond, the exposed samples have undergone annealing. We concluded that this technique allowed for a high charge collection efficiency to be regained, as long as the fluence accumulated is not too high (<1014 p/cm²). Moreover, we were able to observe that Frenkel defects have been converted into NV centers which seem to have a less impact on the CCE.
In conclusion of this entire analysis, our efforts are currently focused on additional studies that time to explore the possibility of repeating the irradiation-annealing operation multiple times in order to extend the detector's lifespan. This is a key element in demonstrating that diamond is the material suitable for detecting particles in a highly radiative environment what is the objective of our entire research work and what we seek to demonstrate.
References:
1. Curtoni, et al. (2021).. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1015, 165757.
2. Poirier, et al (2021, May). In Proceedings 12th International Particle Accelerator Conference (IPAC’21) (pp. 877-880).
3. Bäni, et al, RD42 Collaboration. (2019). Journal of Physics D: Applied Physics, 52(46), 465103.
4. Lafont, F et al. (2023). Diamond and Related Materials, 140, 110454.
| Title | Diamond a suitable material for detecting particles in a highly radiative environment |
|---|---|
| Topic | Solid state sensors |
