排序方式: 共有21条查询结果,搜索用时 31 毫秒
1.
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
2.
C.J. Martoff L. Van Elmbt M. Lebrun M. Schaad U. Straumann P. Truöl K.M. Crowe C. Joseph J.P. Perroud D. Ruegger M.T. Tran J. Deutsch G. Grégoire R. Prieels W. Dahme 《Nuclear Physics A》1984,430(3):557-572
The cross section and angular distribution for the reaction 13C(π+, γ)13N(g.s.) have been measured from 37 to 85° in the laboratory, at a pion energy of 115.5 MeV. The observed cross section ranges from 320 to 660 . These results do not show the large magnitude and wide-angle peaking expected if pre-critical effects due to nascent pion condensation were present. In addition, the observed cross section is less than one-half of the predictions of available theoretical calculations which do not include the pre-critical effect. Data on the reaction 1H(π?, γ)n at Tπ = 116.6 MeV were also obtained for calibration purposes. These data agree with expectations based on knowledge of the inverse reaction and previous measurements. 相似文献
3.
P. Knowles J. Deutsch J. Egger W. Fetscher F. Foroughi J. Govaerts M. Hadri K. Kirch S. Kistryn J. Lang X. Morelle O. Naviliat A. Ninane R. Prieels N. Severijns L. Simons J. Sromicki S. Vandormael P. Van Hove 《Hyperfine Interactions》1999,118(1-4):73-76
Unlike the majority of Michel parameters which are consistent with the Standard Model V-A interaction, the experimental value of ξ″(=0.65±0.36) [1] is poorly known. Our experiment will measure the longitudinal polarization,
P
L
, of positrons emitted from the decay of polarized muons. The value of P
L
, equal to unity in the Standard Model, will decrease for high energy positrons emitted antiparallel to the muon spin if the
combination of Michel parameters ξ″/ξξ′ − 1 deviates from the Standard Model value of zero.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Vorobyov A. A. Balin D. V. Baturin V. N. Grigoriev Yu. S. Maev E. M. Petrov G. E. Semenchuk G. G. Smirenin Yu. V. Voropaev N. I. Deutsch J. Govaerts J. Prieels R. Ackerbauer P. Breunlich W. H. Kammel P. Lauss B. Marton J. Prymas W. Egger J. Petitjean C. Petitjean Th. van den Brandt B. Daniel H. Hartmann F. J. Mühlbauer M. Schott W. von Egidy T. Wojciechowski P. Case T. Crowe K. M. Markushin V. E. Beer G. A. 《Hyperfine Interactions》1996,101(1):413-421
In this article we report the results of an experiment performed in 1993 at PSI. The goal was to determine the absolute rate of nuclear muon capture by3He. In the experiment we used a new technique recently developed at Gatchina. As a preliminary result from this experiment we obtained
c=(1496±3(stat)-3(syst)) s–1. 相似文献
5.
6.
7.
8.
Yu. Shitov V. Egorov V. Brudanin I. Yutlandov Ts. Vylov Ch. Briançon J. Deutsch R. Prieels C. Petitjean J. Suhonen 《Czechoslovak Journal of Physics》2002,52(4):459-466
The angular correlations were investigated measuring with high-precision HPGe detectors -lines following the ordinary muon capture (OMC) on 28Si and 16O. The Doppler-broadened shapes of these lines are sensitive to the weak couplings as well as to the nuclear matrix elements (NME) of OMC transitions.A considerable quenching of the induced pseudoscalar form-factor g
P and a nonzero value of sum of scalar couplings C
S+g
S are reported contradictory to the postulates of the Standard Model. However, the questions of reliability of the NME used to extract the weak couplings from the experimentally measured correlation parameters are still open. Future steps in order to solve this problem are discussed. 相似文献
9.
P. Kammel V. A. Andreev D. V. Balin R. M. Carey T. Case D. B. Chitwood S. M. Clayton K. M. Crowe J. Deutsch P. T. Debevec P. U. Dick A. Dijksman J. Egger D. Fahrni A. A. Fetisov S. J. Freedman V. A. Ganzha B. Gartner J. Govaerts F. E. Gray F. J. Hartmann W. D. Herold D. W. Hertzog V. I. Jatsoura A. G. Krivshich B. Lauss E. M. Maev O. E. Maev V. E. Markushin C. J. G. Onderwater C. Petitjean G. E. Petrov C. C. Polly R. Prieels S. M. Sadetsky G. N. Schapkin R. Schmidt G. G. Semenchuk M. Soroka A. A. Vorobyov N. I. Voropaev 《Hyperfine Interactions》2001,138(1-4):435-443
The aim of the μCap experiment is a 1% measurement of the singlet capture rate Λ
S
for the basic electro-weak reaction μ + p → n + νμ. This observable is sensitive to the weak form-factors of the nucleon, in particular to the induced pseudoscalar coupling
constant g
P
. It will provide a rigorous test of theoretical predictions based on the Standard Model and effective theories of QCD. The
present method is based on high precision lifetime measurements of μ− in hydrogen gas and the comparison with the free μ+ lifetime. The μ− experiment will be performed in ultra-clean, deuterium-depleted H2 gas at 10 bar. Low density compared to liquid H2 is chosen to avoid uncertainties due to ppμ formation. A time projection chamber acts as a pure hydrogen active target. It defines the muon stop position in 3D and
detects rare background reactions. Decay electrons are tracked in cylindrical wire-chambers and a scintillator array covering
75% of 4π.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
N. Severijns J. Deutsch D. Beck M. Beck B. Delauré T. Phalet R. Prieels P. Schuurmans B. Vereecke S. Versyck 《Hyperfine Interactions》2000,129(1-4):223-236
Two experiments to search for new physics beyond the standard model for electroweak interactions by measuring correlations
between different spin and momentum vectors in nuclear β-decay are discussed. In the first experiment the correlation between
the emission asymmetry and the longitudinal polarisation of positrons emitted by polarised nuclei is determined. This type
of measurement is sensitive to the presence of right-handed currents but also to possible scalar and tensor-type currents
in the weak interaction. The aim of the second experiment is to determine the βν-correlation in β-decay by measuring the energy
spectrum of the recoil ions, using a Penning trap and a retardation spectrometer. In this case the focus is on the search
for scalar currents in the weak interaction. The results of the experiments presented here are complementary to results from
experiments in muon decay and at high-energy colliders.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献