Performance Study of Plastic Scintillators Coupled to SiPM for Fast-Timing Measurements

Plastic scintillators are widely used as beta-particle detectors in nuclear physics. Thin plastics, with thicknesses of few mm, coupled to fast photomultiplier tubes (PMT) are employed for timing measurements. This configuration provides excellent time resolution and homogeneous energy response for a wide range of incident beta particle energies.On the other hand, silicon photomultipliers (SiPMs) keep gaining relevance due to their compact size, insensitivity to magnetic fields and no need for high voltage supply. Their small size is very attractive for nuclear physics experiments. In the case of plastic fast-timing beta detectors in particular, where most of the space is occupied by the PMT, SiPMs would make it possible to build very compact detectors, provided that they exhibit similar time resolutions. In addition, this would allow to increase the number of detectors, and thus the overall efficiency, while releasing space iin complex setups.The increased efficiency and flexibility for extended configurations are important points for future measurements at the ISOLDE Decay Station (IDS), where coincidence-delayed βγγ(t) fast-timing experiments are performed. For this purpose, we have tested the performance of two EJ-232Q scintillator plastics coupled to three different SIPM. Processing the fast signal output of this SiPM we have obtained an optimal time resolution of (154 ps CRT FWHM) against a reference detector. This value is comparable with the one obtained with the same plastic coupled to a fast PMT, which makes this configuration very promising for future experiments.