The use of CVD-diamond for heavy-ion detection

The suitability of CVD-diamond detectors is investigated for applications in heavy-ion accelerator facilities with high intensity beams. Various diamond films of 'optical' and 'electronic grade' used and unpolished (as grown) are tested with different ions from alpha -particles (Am-241-source) up to the heaviest ions like Pb-208 and U-238. The diamond signals are processed in a single-particle mode with current sensitive low-noise broadband electronics. An intrinsic time resolution of sigma (i)(DeltaT) = 29 ps is achieved using detectors of 'optical grade' with a thickness of 100 Lm. The time resolution improves for thicker samples and for higher electric field applied to the detector. Determined by the strip capacitance and the electronics used, a single-particle counting rate capability > 10(8) ions/s is obtained. The charge collected from different particles increases linearly with the energy loss of the particle and non-linearly with the detector thickness. The pulse-height resolution depends strongly on the material texture and on the irradiation state of the sample and weakly on the ionisation density produced by the particle. 'Priming' is observed up to a fluence of 10(10) ions/cm(2). The homogeneity over the detector area increases significantly. The charge-collection efficiency improves by a factor of 2 and the pulse-height resolution significantly by a factor of 5. The bandwidth of available electronics limits the results obtained at present. Nevertheless, the selection of data presented demonstrates an excellent suitability of CVD diamond for a variety of heavy-ion applications. (C) 2001 Elsevier Science B.V. All rights reserved.