The "Golden” cLFV channels μ → eγ and μ → eee — the high-intensity frontier

The muon as a laboratory for studying charged lepton-flavour violation (cLFV) has proven to be one of the most sensitive areas to probe for "New Physics”, due to the muon's copious production rate and relatively long lifetime. The search at the intensity frontier with precision-type experiments is complementary to the search for new particles at the high-energy frontier of TeV colliders. Of the three "golden” muon channels: μ → eγ, μ → 3e and μ → e conversion, an overview of the status of the coincidence experiments MEG, together with the latest results, which constitute the most stringent limit to date on this decay and the recently initiated Mu3e experiment, will be give

Beam monitoring detectors for High Intensity Muon Beams

We present two novel beam monitors designed for use in current PSI muon beams and upgradable for the High Intensity Muon Beam (HIMB) project beamlines: the scintillating fibre (SciFi) detector, a grid of scintillating fibres coupled to SiPMs, and the MatriX detector, a matrix of plastic scintillators coupled to silicon photomultipliers (SiPMs), both detectors having particle ID capability. The advantage of these highly segmented detectors is the capability to withstand the high beam rate and to perform total beam rate measurements. Furthermore, the use of the SiPM as a photosensor enables operation of these detectors in high magnetic field environments (up to 1.25T). Both detectors have been tested in the beam at PSI and with continuous beam rates up to 108μ+/s. The performance of these detectors as measured on the beamlines are presented.ISSN:0168-9002ISSN:1872-957

Future facilities at PSI, the High-Intensity Muon Beams (HIMB) project

Currently, PSI delivers the most intense continuous muon beam in the world with up to a few 108 µ+/s. The High-Intensity Muon Beams (HIMB) project is developing a new target station and muon beamlines able to deliver 1010 µ+/s, with a huge impact for low-energy, high-precision muon experiments. While the next generation of proton drivers with beam powers in excess of the currently achieved 1.4 MW still require significant research and development, the focus of HIMB is to improve the surface muon yield with a new target geometry and to increase capture and transmission with a solenoid-based beamline in order to reach a total efficiency of approximately 10 %. We present the current status of the HIMB project.ISSN:2100-014XISSN:2101-627

The search for \ub5+ \u2192 e+\u3b3 with 10 1214 sensitivity: The upgrade of the meg experiment

The MEG experiment took data at the Paul Scherrer Institute in the years 2009\u20132013 to test the violation of the lepton flavor conservation law, which originates from an accidental symmetry that the Standard Model of elementary particle physics has, and published the most stringent limit on the charged lepton flavor violating decay \ub5+ \u2192 e+\u3b3: BR(\ub5+ \u2192 e+\u3b3) < 4.2 7 10 1213 at 90% confidence level. The MEG detector has been upgraded in order to reach a sensitivity of 6 7 10 1214 . The basic principle of MEG II is to achieve the highest possible sensitivity using the full muon beam intensity at the Paul Scherrer Institute (7 7 107 muons/s) with an upgraded detector. The main improvements are better rate capability of all sub-detectors and improved resolutions while keeping the same detector concept. In this paper, we present the current status of the preparation, integration and commissioning of the MEG II detector in the recent engineering runs