Study of the effect of detector to front-end electronics distance on the spectrometric performances of solid-state detectors

Abstract

Solid-state detectors are used for charge particles detection and spectrometry with front-end electronics located, usually, next to the detectors. Therefore, in some applications, due to high-level radiation, high temperature and/or electro-magnetic noises (e.g. in nuclear fusion energy experiments, high energy accelerators, etc.) there could be the need to locate the front-end electronics far away from the detector. To solve the problem a matching sensitive charge amplifier (MSCA) with AC coupled input was designed by Roberto Cardarelli (former INFN scientist) for measurements at the fusion JET tokamak (U.K.). The prototype, composed of two amplification stages, was “ad hoc” designed for use with Diamond detectors and resulted very reliable. A commercial version of the MSCA was then developed and is now available on the market. Its novelty and main advantage, with respect to the former version, is to be used also with other fast detectors e.g. Resistive Plate Chamber (RPC) with high counting speed and Silicon detectors. The commercial MSCA features input impedance very close to 50 Ohm, which can be matched to a 50-Ohm transmission line. This allows locating the amplifier at variable distances from the detector and up to 100 m. These claimed performances result very interesting for solid state detectors, therefore, up to now a few applications of MSCA are reported in the literature and a systematic study of its performances is missing. In this work, an analysis of the spectrometric performances of Diamond and Silicon detectors coupled to MSCA located at various distances (up to 48 m) from the detectors is reported. Pulse height spectra of a multi-peaks alpha source were measured using MSCA amplifier and compared with those obtained using a standard charge sensitive preamplifier (CA). Then, the effect of the distance between detectors and amplifiers was investigated using standard RG58 and double shielded RG214 coaxial cables. The results are presented and discussed.