Comparative timing performances of S-CVD diamond detectors with different particle beams and readout electronics

Abstract

One of the particular characteristics of diamond detectors is their fast charge collection time. This feature makes these detectors very attractive for timing measurements in both nuclear and particle physics experiments. The charge collection time in these detectors is of the order of a few hundred ps, therefore the timing performance depends greatly on the electronics readout of the detector. In this work we present comparative measurements made using a single crystal diamond detector and two different electronic readout chains. In particular, we used a charge sensitive amplifier (CSA) with a 100 MHz bandwidth and a voltage amplifier with a 2 GHz bandwidth. In order to evaluate the performance of the detector for charge signals generated by particles with energies below minimum ionizing, measurements were taken using 62 MeV proton beam at the INFN - Laboratori Nazionali del Sud. Another set of measurements was made with a 120 GeV proton beam at FNAL in order to evaluate the performance with MIP. The timing performance depends on the rise time of the signal and the Signal to Noise ratio. Both these characteristics are inversely related to the electronic readout bandwidth. The charge collection with the 62 MeV proton beam was about 130 Ke <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> . A SIN ratio of about 80 was obtained with the CSA, while the SIN ratio was approximately 4 with the 2 GHz broad-band amplifier. This resulted in a comparable time distribution value of around 70 ps RMS in both cases. However, charge collection is much smaller with minimum ionizing particles, and while it was possible to perform measurements with the CSA, with the broadband amplifier it was not possible to separate signals from the background noise. In this work we present and discuss the set-up used and the complete set of measurements, with final considerations regarding range of use to which these detector can be utilized.