排序方式: 共有10条查询结果,搜索用时 31 毫秒
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Andreev VA Banks TI Case TA Chitwood DB Clayton SM Crowe KM Deutsch J Egger J Freedman SJ Ganzha VA Gorringe T Gray FE Hertzog DW Hildebrandt M Kammel P Kiburg B Knaack S Kravtsov PA Krivshich AG Lauss B Lynch KL Maev EM Maev OE Mulhauser F Ozben CS Petitjean C Petrov GE Prieels R Schapkin GN Semenchuk GG Soroka MA Tishchenko V Vasilyev AA Vorobyov AA Vznuzdaev ME Winter P;MuCap Collaboration 《Physical review letters》2007,99(3):032002
The rate of nuclear muon capture by the proton has been measured using a new technique based on a time projection chamber operating in ultraclean, deuterium-depleted hydrogen gas, which is key to avoiding uncertainties from muonic molecule formation. The capture rate from the hyperfine singlet ground state of the microp atom was obtained from the difference between the micro(-) disappearance rate in hydrogen and the world average for the micro(+) decay rate, yielding Lambda(S)=725.0+/-17.4 s(-1), from which the induced pseudoscalar coupling of the nucleon, g(P)(q(2)=-0.88m(2)(micro))=7.3+/-1.1, is extracted. 相似文献
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Tripathi S Armstrong DS Christy ME Clark JH Gorringe TP Hasinoff MD Kovash MA Wright DH Zołnierczuk PA 《Physical review letters》2002,89(25):252501
We report the first observation of double radiative capture on pionic hydrogen. The experiment was conducted at the TRIUMF cyclotron using the RMC spectrometer and detected gamma-ray coincidences following pi(-) stops in liquid hydrogen. We found the branching ratio for double radiative capture to be [3.05+/-0.27(stat)+/-0.31(syst)]x10(-5). The measured branching ratio and angle-energy distributions support the theoretical prediction of a dominant contribution from the pipi-->gammagamma annihilation mechanism. 相似文献
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Webber DM Tishchenko V Peng Q Battu S Carey RM Chitwood DB Crnkovic J Debevec PT Dhamija S Earle W Gafarov A Giovanetti K Gorringe TP Gray FE Hartwig Z Hertzog DW Johnson B Kammel P Kiburg B Kizilgul S Kunkle J Lauss B Logashenko I Lynch KR McNabb R Miller JP Mulhauser F Onderwater CJ Phillips J Rath S Roberts BL Winter P Wolfe B;MuLan Collaboration 《Physical review letters》2011,106(4):041803
We report a measurement of the positive muon lifetime to a precision of 1.0 ppm; it is the most precise particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2×10(12) decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give τ(μ(+)) (MuLan)=2?196?980.3(2.2) ps, more than 15 times as precise as any previous experiment. The muon lifetime gives the most precise value for the Fermi constant: G(F) (MuLan)=1.166?378?8(7)×10(-5) GeV(-2) (0.6 ppm). It is also used to extract the μ(-)p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling g(P). 相似文献
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W. Bertl S. Ahmad D. S. Armstrong G. Azuelos M. Blecher C. Q. Chen P. Depommier P. Gumplinger T. P. Gorringe M. D. Hasinoff et al. 《Zeitschrift fur Physik C Particles and Fields》1992,56(Z1):S150-S155
The radiative capture of negative muons by protons can be used to measure the weak induced pseudoscalar form factor. Brief
arguments why this method is preferable to ordinary muon capture are given followed by a discussion of the experimental difficulties.
The solution to these problems as attempted by experiment #452 at TRIUMF is presented together with preliminary results from
the first run in August 1990. An outlook on the expected final precision and the experimental schedule is also given.
Talk presented by W. Bertl at the Symposium “The Future of Muon Physics” in Heidelberg, Germany, May 7–9, 1991 相似文献
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Jia Y Gorringe TP Hasinoff MD Kovash MA Ojha M Pavan MM Tripathi S Zołnierczuk PA 《Physical review letters》2008,101(10):102301
We report measurements of the pi;{-}p-->pi;{0}n differential cross sections at six momenta (104-143 MeV/c) and four angles (0 degrees -40 degrees ) by detection of gamma-ray pairs from pi;{0}-->gammagamma decays using a photon-pair spectrometer at TRIUMF. This kinematic region exhibits a vanishing zero-degree cross section from destructive interference between s and p waves, thus yielding special sensitivity to pion-nucleon dynamics. Our data and previous data do not agree, with important implications for earlier claims of large isospin-violating effects. 相似文献
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Clark JH Armstrong DS Gorringe TP Hasinoff MD King PM Stocki TJ Tripathi S Wright DH Zolnierczuk PA 《Physical review letters》2006,96(7):073401
We report a measurement of the ortho-para transition rate in the p mu p molecule. The experiment was conducted at TRIUMF via the measurement of the time dependence of the 5.2 MeV neutrons from muon capture in liquid hydrogen. The measurement yielded an ortho-para rate Lambda op = (11.1 +/- 1.7 +/-(0.9)(0.6)) x 10(4) s(-1), which is substantially larger than the earlier result of Bardin et al. The result has striking implications for the proton's induced pseudoscalar coupling g(p), changing the value of g(p) obtained from the most precise ordinary muon capture measurement from 10.6 +/- 2.7 to 0.8 +/- 2.8, and from the sole radiative muon capture measurement from 12.2 +/- 1.1 to 10.6 +/- 1.2, bringing the latter result closer to theoretical predictions. 相似文献
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Chitwood DB Banks TI Barnes MJ Battu S Carey RM Cheekatmalla S Clayton SM Crnkovic J Crowe KM Debevec PT Dhamija S Earle W Gafarov A Giovanetti K Gorringe TP Gray FE Hance M Hertzog DW Hare MF Kammel P Kiburg B Kunkle J Lauss B Logashenko I Lynch KR McNabb R Miller JP Mulhauser F Onderwater CJ Ozben CS Peng Q Polly CC Rath S Roberts BL Tishchenko V Wait GD Wasserman J Webber DM Winter P Zołnierczuk PA;MuLan Collaboration 《Physical review letters》2007,99(3):032001
The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, tau(micro)=2.197 013(24) micros, is in excellent agreement with the previous world average. The new world average tau(micro)=2.197 019(21) micros determines the Fermi constant G(F)=1.166 371(6)x10(-5) GeV-2 (5 ppm). Additionally, the precision measurement of the positive-muon lifetime is needed to determine the nucleon pseudoscalar coupling g(P). 相似文献
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Jonkmans G Ahmad S Armstrong DS Azuelos G Bertl W Blecher M Chen CQ Depommier P Doyle BC von Egidy T Gorringe TP Gumplinger P Hasinoff MD Healey D Larabee AJ Macdonald JA McDonald SC Munro M Poutissou J Poutissou R Robertson BC Sample DG Saettler E Sigler CM Taylor GN Wright DH Zhang NS 《Physical review letters》1996,77(22):4512-4515
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