Mu3e

Mu3e is a planned particle physics experiment at the Paul Scherrer Institute , which looks for the decay of an anti - muon ( Mu ) into an electron and two positrons ( 3e ). This decay is extremely unlikely in the Standard Model of particle physics because the number of leptons is changed. This is only possible in a higher-order loop process and with neutrino oscillation within the loop. In several theories for physics beyond the Standard Model , especially with supersymmetry , this decay is significantly more common. The search for decay enables some of these theories to be tested, even if they are not directly accessible to direct observations (e.g. at the LHC ).

Mu3e is to take place at the Paul Scherrer Institute in order to use the most intense muon beam in the world planned there. The plan is to be able to analyze up to two billion decays per second. Only this high rate makes it possible to observe more than 10 ¹⁶ decays. The decays and are important as the subsurface . In order to distinguish these decays from the signal sought, the detector needs a spatial resolution better than 200  µm , a time resolution better than 100  ps and an energy resolution better than 0.5  MeV . In addition, the detector has to be very light inside in order to keep effects from scattering low. These requirements are met by a combination of semiconductor detectors for position measurement and scintillation detectors for time resolution. The entire experiment is in a magnetic field of 1  Tesla in order to be able to determine energy from the curvature of the electron or positron orbits. ${\displaystyle \mu ^{+}\to e^{+}e^{-}e^{+}{\bar {\nu _{\mu }}}\nu _{e}}$ ${\displaystyle \mu ^{+}\to e^{+}{\bar {\nu _{\mu }}}\nu _{e}}$

It is planned (as of February 2019) to investigate the first muon decays from 2021, the full rate of up to two billion decays per second is to be achieved from 2026. The experiment should either find the decay or determine an upper limit of 10 ⁻¹⁶ for the decay probability, a factor of 10,000 better than the previous upper limit of 10 ⁻¹² .

See also

MEG experiment

Web links

• Description of the experiment on psi.ch
• (Accepted) "Research Proposal" (PDF) with further information

Individual evidence

1. ^ A. Blondel et al .: Research Proposal for an Experiment to Search for the Decay μ → eee . January 25, 2013, arxiv : 1301.6113 (English).
2. ↑ Niklaus Berger et al. In: Nucl. Instr. Meth. , A 732, 2013, pp. 61-65, arxiv : 1309.7896 .
3. ↑ ^{a b} The Mu3e Experiment. Retrieved July 19, 2015 . 
4. ↑ Search for the Decay mu + ---> e + e + e- SINDRUM collaboration