UCHIYAMA , Y.

The MEG detector is designed to test Lepton Flavor Violation in the μ+→e+γ decay down to a Branching Ratio of a few 10-13. The decay topology consists in the coincident emission of a monochromatic photon in direction opposite to a monochromatic positron. A precise measurement of the relative time te+γ is crucial to suppress the background. The...

A new timing detector measuring ∼50MeV/c positrons is under development for the MEG II experiment, aiming at a time resolution σt∼30ps. The resolution is expected to be achieved by measuring each positron time with multiple counters made of plastic scintillator readout by silicon photomultipliers (SiPMs). The purpose of this work is to...

The MEG II experiment (Baldini et al., 2018) [1] is designed to improve the sensitivity to the μ +→e + γ decay. A crucial component is the Pixelated Timing Counter (pTC), dedicated to the measurement of the positron time to reduce the combinatorial background (Cattaneo et al., 2014; Nishimura et al., 2016) [3,4]. The detector consists of 512...

We studied the impact of radiation damage on scintillation counters read out by six SiPMs connected in series focusing on their time resolution. Six SiPMs from AdvanSiD were irradiated step by step with a 37 MBq 90Sr source. At the integrated dose expected at the end of the MEG II experiment, the time resolution at 30 °C was measured to be...

The MEG experiment is now being upgraded to search for the charged lepton flavor violating decay μ+ → e+γ with an improved branching ratio sensitivity, 5 × 10-14. We are developing a new Timing Counter to precisely measure the timing of the decay positrons under the high rate environment. The Timing Counter consists of 512 counters and each...

A new timing detector has been developed to measure ∼50 MeV/c positrons with a time resolution of σt≃30ps in the MEG II experiment. The detector are segmented into 512 scintillation counters, each of which consists of 120×(40or50)×5mm3 size BC-422 and two arrays of six AdvanSiD silicon photomultipliers. The single-counter resolutions are...

The development of a Timing Counter detector with a resolution in the range of ≈ 30 ps will be presented. The detector was designed for the upgrade of the MEG II experiment looking for the μ+→ e+γ decay with an improved sensitivity of one order of magnitude with respect to the previous MEG setup. In this paper the design of the TC single pixel...

The development of a Timing Counter detector designed for the MEGII upgrade of the MEG experiment, which strives to improve the sensitivity on theμ+→e+γ decay of an order of magnitude, is presented. It is based on two sets of counters (sectors) arranged on a semi-cylindrical structure; each sector consists of 256 counters. Each counter consists...

The MEGII Timing Counter will measure the positron time of arrival with a resolution of ~ 30 ps relying on two arrays of scintillator pixels read out by 6144 Silicon Photomultipliers (SiPMs) from AdvanSiD. They are characterised, measuring their breakdown voltage, to assure that the gains of the SiPMs of each pixel are as uniform as possible,...

The MEG II experiment at Paul Scherrer Institut in Switzerland will search for the lepton flavour violating muon decay, μ+→ e+\gamma, with a sensitivity of 4× 10-14improving the existing limit of an order of magnitude. In 2016, we finished the construction of the MEG II Timing Counter, the subdetector dedicated to the measurement of the...