Muon polarization in the MEG experiment: predictions and measurements
The MEG experiment makes use of one of the world’s most intense low energy muon beams, in order to search for the lepton flavour violating process μ+→e+γ. We determined the residual beam polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be Pμ=-1 by the Standard Model (SM) with massless neutrinos. We estimated our residual muon polarization to be Pμ= -0.86 ± 0.02 (stat) $$+0.05\atop{-0.06}$$ (syst) at the stopping target, which is consistent with the SM predictions when the depolarizing effects occurring during the muon production, propagation and moderation in the target are taken into account. The knowledge of beam polarization is of fundamental importance in order to model the background of our μ+→e+γ search induced by the muon radiative decay: μ+→e+$$\bar{v}$$μνeγ.
- Research Organization:
- Univ. of California, Irvine, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Contributing Organization:
- The MEG Collaboration
- Grant/Contract Number:
- FG02-91ER40679; 200021_137738; RBFR08XWGN; RFBR 14-22-03071
- OSTI ID:
- 1361495
- Journal Information:
- European Physical Journal. C, Particles and Fields, Vol. 76, Issue 4; ISSN 1434-6044
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Search for the lepton flavour violating decay $$\mu ^+ \rightarrow \mathrm {e}^+ \gamma $$ μ + → e + γ with the full dataset of the MEG experiment: MEG Collaboration
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journal | August 2016 |
The design of the MEG II experiment: MEG II Collaboration
|
journal | May 2018 |
The design of the MEG II experiment
|
text | January 2018 |
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