The downstream Muon detector of the SHiP experiment

SHiP is a new proposed beam dump experiment at the SPS to Search for Hidden Particles beyond the Standard Model. It is composed of several subdetectors, of which the most downstream is dedicated to the identification of muons. The muon detector will cover an area of 6×12 m and will be equipped with 3 planes of scintillator interposed with iron absorbers. In the SHiP experiment, one of the main contributions to the generally very small background is the caused by combinatorial muon tracks accidentally mimicking a signal signature by forming a fake vertex in the fiducial volume. This background can be reduced by requiring the tracks that form a vertex to be within a very short time window. This drives the requirement of the detector time resolution, while its spatial resolution is not as critical. In order to cover such a large area with a fast and robust detector, a system based on 200 cm$^2$ scintillator tiles, read out at the corners by SiPMs, has been developed, which improves over the baseline described in the SHiP Technical Proposal. Measurements indicate that the timing resolution can be pushed below 300 ps; this contribution will present optimization studies aimed at maximizing performance, as well as test beam results on the first prototypes.