Commissioning of a new low energy π-μ at triumf

Oram, C. J.; Warren, J. B.; Marshall, G. M.; Doornbos, J.

doi:10.1016/0029-554x(81)91166-6

Cited by 51 publications

(18 citation statements)

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“…In the present experiment, highly polarized surface muons [4] were delivered, in vacuum, to the TWIST spectrometer [13] by the M13 channel at TRIUMF [14]. The properties of the surface muon beam are a typical rate of 2.5 kHz, a momentum of 29.6 MeV/c, and a momentum bite, ∆p/p ≈ 1.0% FWHM.…”

Section: Methodsmentioning

confidence: 99%

Measurement ofPμξin polarized muon decay

Jamieson¹,

Bayes²,

Davydov³

et al. 2006

Phys. Rev. D

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The quantity P π µ ξ, where ξ is one of the muon decay parameters and P π µ is the degree of muon polarization in pion decay, has been measured. The value P π µ ξ = 1.0003±0.0006 (stat.)±0.0038 (syst.) was obtained. This result agrees with previous measurements but is over a factor of two more precise. It also agrees with the Standard Model prediction for P π µ ξ and thus leads to restrictions on left-right symmetric models.

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Section: Methodsmentioning

confidence: 99%

Measurement ofPμξin polarized muon decay

Jamieson¹,

Bayes²,

Davydov³

et al. 2006

Phys. Rev. D

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“…The M13 beam line [11] selected positive muons with a momentum of 29:6 MeV=c, with a momentum bite of Áp=p % 1% FWHM, and delivered these in vacuum to the TWIST spectrometer [12] at a typical rate of 2:5 Â 10 3 per second. The beam had a contamination of positrons, at the same momentum, with a typical rate of 22 kHz, as well as a small fraction of pions.…”

Section: Experimental Procedures a Experimental Setupmentioning

confidence: 99%

Precision measurement of the muon decay parametersρandδ

MacDonald¹,

Bayes²,

Bueno³

et al. 2008

Phys. Rev. D

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The TWIST Collaboration has performed new measurements of two of the parameters that describe muon decay: , which governs the shape of the overall momentum spectrum, and , which governs the momentum dependence of the parity-violating decay asymmetry. This analysis gives the results ¼ 0:750 14 AE 0:000 17ðstatÞ AE 0:000 44ðsystÞ AE 0:000 11ðÞ, where the last uncertainty arises from the correlation between and the decay parameter , and ¼ 0:750 67 AE 0:000 30ðstatÞ AE 0:000 67ðsystÞ. These are consistent with the value of 3=4 given for both parameters in the standard model of particle physics, and are a factor of two more precise than the measurements previously published by TWIST. A new global analysis of all available muon decay data incorporating these results is presented. Improved lower and upper limits on the decay parameter P of 0:995 24 < P < 1:000 91 at 90% confidence are determined, where P is the polarization of the muon when it is created during pion decay, and governs the muon decay asymmetry. These results set new model-independent constraints on the possible weak interactions of right-handed particles. Specific implications for left-right symmetric models are discussed.

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“…Positrons in the beam (1/4 of the rate of pions) severely increase detector rates, trigger rates and background in the π + → e + ν spectrum. The TRIUMF M13 channel [4] has therefore been upgraded to suppress the positron contamination in the pion beam.…”

Section: Motivationmentioning

confidence: 99%

“…The layout of the existing M13 channel [4] together with the new beam line extension is shown in Fig.1. The beam line takes off from the primary proton beam line (BL1A) at an angle of 135 • from a 1-cm thick Be production target (T1).…”

Section: Existing M13 Channelmentioning

confidence: 99%

High purity pion beam at TRIUMF

Aguilar-Arevalo

Blecher

Bryman

et al. 2009

Nuclear Instruments and Methods in Physics Research Section A:

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An extension of the TRIUMF M13 low-energy pion channel designed to suppress positrons based on an energy-loss technique is described. A source of beam channel momentum calibration from the decay π + → e + ν is also described.Key words: Beam channel, Particle separation, Pion Decay PACS: 41.85.Ja, 13.20.Cz, 29.27.Eg MotivationThe branching ratio of pion decays [1, 2], R=Γ(π → eν + eνγ)/Γ(π → µν + µνγ), has provided the best test of the hypothesis of electron-muon universality in weak interactions. The new TRIUMF PIENU experiment [3] aiming to improve the precision of the branching ratio measurement by a factor of five or more measures positrons from the π + → e + ν decay (E e + = 69.8 MeV) and the π + → µ + → e + decay chain (π + → µ + ν decay followed by µ + → e + νν decay, E e + < 52.8 MeV). In order to obtain maximum acceptance with minimum uncertainties arising from positron energy-dependent cross sections, the detector system involving a large NaI crystal is placed on the beam axis. Positrons in the beam (1/4 of the rate of pions) severely increase detector rates, trigger rates and background in the π + → e + ν spectrum. The TRIUMF M13 channel [4] has therefore been upgraded to suppress the positron contamination in the pion beam.

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Commissioning of a new low energy π-μ at triumf

Cited by 51 publications

References 0 publications

Measurement ofPμξin polarized muon decay

Measurement ofPμξin polarized muon decay

Precision measurement of the muon decay parametersρandδ

High purity pion beam at TRIUMF

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