A detailed characterization under 90 Sr β-particles and 4.5 MeV protons micro-beam of a singlecrystal CVD diamond-based three-dimensional detector with surface and buried graphite electrodes is presented. Pillar contacts, 300 µm long and 30 µm diameter, were fabricated by using a femtosecond laser operating at 1030 nm wavelength and 400 fs pulse duration. Charge collected under 90 Sr β-particles was measured in front and back irradiation conditions, pointing out that the pillars contribute to the charge collection. Charge collection efficiency (CCE) was measured to be up to 94% under proton beam irradiation. Results of a comprehensive study, including crossedpolarizers imaging, numerical simulation of the electric field distribution, and proton mapping, show that CCE is not affected from the stress induced by the pillar fabrication, and that the electric field strength is high enough to partially compensate for carrier recombination in the defected regions surrounding the pillars.
A detector from single crystal synthetic diamond with conducting wires has been prepared with an improved femto-second laser process. The detector was characterised with a 4.5 MeV proton micro-beam (Ruder Bosković Institute, Zagreb). The charge collection efficiency and the transient current response have been investigated with high spatial resolution. A hexagonal and square cell geometry is investigated. Both cell geometries show full charge collection at 40V bias voltage, and little charge sharing between neighbouring cells. The experimental data is compared to a simulation and qualitative agreement is observed.
Using the advantage of the high spatial resolution of the Ruđer Bošković Institute (RBI) ion microprobe, small areas of a thin membrane single crystal chemical vapor deposition (scCVD) diamond detector were intentionally damaged with a high-intensity 26-MeV oxygen ion beam at various fluences, producing up to ∼1018 vacancies/cm3. The response of the detector was tested with the ion beam-induced charge technique (IBIC) using a 2-MeV proton beam as a probe. The signal amplitudes decreased down to approximately 50% of the original value at low electric fields (<10 V/μm) inside the detector. However, the increase of electric field to values of ∼100 V/μm completely recovers the signal amplitude. The results presented herein can facilitate the development of true radiation hard particle detectors.
We report herein the enhanced sensitivity for the detection of charged particles in single crystal chemical vapour deposition (scCVD) diamond radiation detectors. The experimental results demonstrate charge multiplication in thin planar diamond membrane detectors, upon impact of 18 MeV O ions, under high electric field conditions. Avalanche multiplication is widely exploited in devices such as avalanche photo diodes, but has never before been reproducibly observed in intrinsic CVD diamond. Because enhanced sensitivity for charged particle detection is obtained for short charge drift lengths without dark counts, this effect could be further exploited in the development of sensors based on avalanche multiplication and radiation detector with extreme radiation hardness
One of the possible ways to maintain the micrometer spatial resolution while performing ion beam analysis in the air is to increase the energy of ions. In order to explore capabilities and limitations of this approach, we have tested a range of proton beam energies (2 -6 MeV) using in-air STIM (Scanning Ion Transmission Microscopy) setup. Measurements of the spatial resolution dependence on proton energy have been compared with SRIM simulation and modelling of proton multiple scattering by different approaches. Results were used to select experimental conditions in which 1 micrometer spatial resolution could be obtained.High resolution in-air microbeam could be applied for IBIC (Ion Beam Induced Charge) tests of large detectors used in nuclear and high energy physics that otherwise can not be tested in relatively small microbeam vacuum chambers.
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