A multi-purposed detector with silicon photomultiplier readout of scintillating fibers

摘要

Today, high position and timing resolutions can be simultaneously achieved using scintillating fibers coupled to silicon photomultipliers. In the framework of the MEGII experiment (MEG upgrade) which searches for the μ~+ →e~+γ decay we are developing an active muon stopping target of 250 μm square scintillating fibers coupled to silicon photomultipliers. This tool should provide an unique way to continuously monitor the beam (detecting the stopped muons) at the highest muon beam intensities in the world, and to measure the muon decay vertex (detecting the outgoing positron). A similar technology will also be applicable to the Mu3e experiment which searches for the μ~+ →e~+e~-e~+ decay. In this experiment a timing hodoscope, which complements the silicon tracker, will be made by few layers of 250 μm square or round scintillating fibers, providing timing measurements with a resolution ＜ 1 ns. In this work we report the results obtained with the current prototypes showing that spatial resolutions at a level of 70 μm and timing resolutions of the order of 350 ps can be reached with a detection efficiency ≥ 90%.