by
Michal Pomorski, Laboratoire Capteurs Diamant, CEA Saclay
→
Europe/Berlin
AER19, room 3.11
AER19, room 3.11
Description
Chemical vapour deposition (CVD) of diamond with very reduced atomic impurities and structural defects has been made possible over the last few years. Recent studies have shown that simple single crystal CVD (scCVD) diamond detectors with parallel-plate geometry are almost matching commercial silicon-diode detector performances with respect to energy resolution, although diamond exhibits superior timing properties. In this work, we further explore such capabilities of scCVD as a detector material by developing a new route for position sensitive detection (PSD). Most of the few available papers to date deal with diamond PSDs made of polycrystalline CVD (pcCVD) thin films and metallic resistive-sensing electrodes. Due to the presence of grain boundaries in pcCVD diamond such detectors fail in terms of position measurement, when micro-beams are used or when single particle detection mode is involved. Furthermore, due to the inhomogeneous charge traps distribution, the charge collection varies significantly with the interaction position in these detectors, thus energy loss spectroscopy cannot be performed. Here, for the first time, we propose to use the scCVD diamond as a detector consisting of bulk scCVD material with robust diamond-like carbon (DLC) thin film for the fabrication of the resistive-sensing electrodes. Using charge-sensitive and broad-band electronics we demonstrate the feasibility of counting mode operation of the scCVD-PSD, where precise measurement of the single 4.8 MeV α-particle hit position, energy loss and timing within 100ns integration time is made possible. The feasibility of the scCVD-PSD prototype for on-line beam monitoring has been evaluated in direct 9 keV x-ray beams at Soleil, and ESRF synchrotrons. For signal-to-noise ratio of 10^3 the measured position resolution was ~250 nm (FWHM) with the reconstructed position pattern linearity reaching 99.9%. The scCVD-PSD x-ray beam induced current followed exactly response of the reference detector (Si photodiode) over three decades, demonstrating the capability of the diamond PSD for the beam intensity monitoring, as well. No radiation damage signs in scCVD-PSD have been observed for the total absorbed dose of 0.3 GGy. Bearing in mind the extraordinary physical properties of diamond including its radiation hardness, high electrical resistivity, extraordinary thermal conductivity and low atomic mass scCVD-PSDs can offer a durable solution for low energy pulse resolved X-ray beam monitoring in extreme conditions.
