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Adam J, Bai X, Baldini AM, Baracchini E, Bemporad C, Boca G, Cattaneo PW, Cavoto G, Cei F, Cerri C, de Bari A, De Gerone M, Doke T, Dussoni S, Egger J, Fujii Y, Galli L, Gatti F, Golden B, Grassi M, Graziosi A, Grigoriev DN, Haruyama T, Hildebrandt M, Hisamatsu Y, Ignatov F, Iwamoto T, Kaneko D, Kettle PR, Khazin BI, Khomotov N, Kiselev O, Korenchenko A, Kravchuk N, Lim G, Maki A, Mihara S, Molzon W, Mori T, Mzavia D, Nardò R, Natori H, Nicolò D, Nishiguchi H, Nishimura Y, Ootani W, Panareo M, Papa A, Piredda G, Popov A, Renga F, Ripiccini E, Ritt S, Rossella M, Sawada R, Sergiampietri F, Signorelli G, Suzuki S, Tenchini F, Topchyan C, Uchiyama Y, Voena C, Xiao F, Yamada S, Yamamoto A, Yamashita S, You Z, Yudin YV, Zanello D. New constraint on the existence of the μ+ → e+ γ decay. PHYSICAL REVIEW LETTERS 2013; 110:201801. [PMID: 25167396 DOI: 10.1103/physrevlett.110.201801] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Indexed: 06/03/2023]
Abstract
The analysis of a combined data set, totaling 3.6 × 10(14) stopped muons on target, in the search for the lepton flavor violating decay μ(+) → e(+)γ is presented. The data collected by the MEG experiment at the Paul Scherrer Institut show no excess of events compared to background expectations and yield a new upper limit on the branching ratio of this decay of 5.7 × 10(-13) (90% confidence level). This represents a four times more stringent limit than the previous world best limit set by MEG.
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Adam J, Bai X, Baldini AM, Baracchini E, Bemporad C, Boca G, Cattaneo PW, Cavoto G, Cei F, Cerri C, de Bari A, De Gerone M, Doke T, Dussoni S, Egger J, Fratini K, Fujii Y, Galli L, Gallucci G, Gatti F, Golden B, Grassi M, Grigoriev DN, Haruyama T, Hildebrandt M, Hisamatsu Y, Ignatov F, Iwamoto T, Kettle PR, Khazin BI, Kiselev O, Korenchenko A, Kravchuk N, Maki A, Mihara S, Molzon W, Mori T, Mzavia D, Natori H, Nicolò D, Nishiguchi H, Nishimura Y, Ootani W, Panareo M, Papa A, Pazzi R, Piredda G, Popov A, Renga F, Ritt S, Rossella M, Sawada R, Sergiampietri F, Signorelli G, Suzuki S, Tenchini F, Topchyan C, Uchiyama Y, Valle R, Voena C, Xiao F, Yamada S, Yamamoto A, Yamashita S, Yudin YV, Zanello D. New limit on the lepton-flavor-violating decay μ+→e+γ. PHYSICAL REVIEW LETTERS 2011; 107:171801. [PMID: 22107507 DOI: 10.1103/physrevlett.107.171801] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Indexed: 05/31/2023]
Abstract
We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay μ(+)e(+)γ. The likelihood analysis of the combined data sample, which corresponds to a total of 1.8×10(14) muon decays, gives a 90% C.L. upper limit of 2.4×10(-12) on the branching ratio of the μ(+)→e(+)γ decay, constituting the most stringent limit on the existence of this decay to date.
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Shekhtman L, Ignatov F, Tayursky V. Simulation of physics background in Super c-tau factory detector. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201921201009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Simulation of background particle fluxes generated by colliding beams is performed with FLUKA package for the Super C-Tau factory Detector (SCTD). Two processes are considered as main sources of luminosity generated background: two-photon production of electron-positron pairs and Bha-Bha scattering with bremsstrahlung photon emission (radiative Bha-Bha). The SCTD geometry is described corresponding to the last version of the Conceptual Design Report. The magnetic field based on the calculation in ANSYS is introduced in the model. Main results of the simulation for beam energy of 3 GeV, luminosity of 1035 cm−2s−1 and 1.5 T magnetic field are the following: charged particle fluence in the region of the Inner Tracker (radius 5cm -20 cm, Z between -30cm and 30 cm) is between 105 particles/(cm2s) and ∼103 particles/(cm2s); 1-MeV neutron equivalent fluence for Si in the regions corresponding to electronics of the Inner Tracker and the Drift Chamber is below 1011 n/(cm2y) and absorbed dose is below 100 Gy/y in the hottest regions of the detector.
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