Beam test results of a 16 ps timing system based on ultra-fast silicon detectors

摘要

In this paper we report on the timing resolution of the first production of50 micro-meter thick Ultra-Fast Silicon Detectors (UFSD) as obtained in a beamtest with pions of 180 GeV/c momentum. UFSD are based on the Low-Gain AvalancheDetectors (LGAD) design, employing n-on-p silicon sensors with internal chargemultiplication due to the presence of a thin, low-resistivity diffusion layerbelow the junction. The UFSD used in this test belongs to the first productionof thin (50 {\mu}m) sensors, with an pad area of 1.4 mm2. The gain was measuredto vary between 5 and 70 depending on the bias voltage. The experimental setupincluded three UFSD and a fast trigger consisting of a quartz bar readout by aSiPM. The timing resolution, determined comparing the time of arrival of theparticle in one or more UFSD and the trigger counter, for single UFSD wasmeasured to be 35 ps for a bias voltage of 200 V, and 26 ps for a bias voltageof 240 V, and for the combination of 3 UFSD to be 20 ps for a bias voltage of200 V, and 15 ps for a bias voltage of 240 V.