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991.
Mahmood AH Csorna SE Danko I McLean KW Márka S Xu Z Godang R Kinoshita K Lai IC Schrenk S Bonvicini G Cinabro D McGee S Perera LP Zhou GJ Lipeles E Pappas SP Schmidtler M Shapiro A Sun WM Weinstein AJ Würthwein F Jaffe DE Masek G Paar HP Potter EM Prell S Sharma V Asner DM Eppich A Hill TS Morrison RJ Nelson HN Briere RA Chen GP Behrens BH Ford WT Gritsan A Roy J Smith JG Alexander JP Baker R Bebek C Berger BE Berkelman K Blanc F Boisvert V Cassel DG Dickson M Drell PS Ecklund KM Ehrlich R 《Physical review letters》2001,86(11):2232-2236
The Lambda+c lifetime is measured using 9.0 fb(-1) of e+e- annihilation data collected on or just below the Upsilon(4S) resonance with the CLEO II.V detector at CESR. Using an unbinned maximum likelihood fit, the Lambda+c lifetime is measured to be 179.6+/-6.9(stat)+/-4.4(syst) fs. The precision of this colliding beam measurement is comparable to other measurements, which are based on fixed-target experiments, with different systematic uncertainties. 相似文献
992.
Csorna SE Danko I McLean KW Xu Z Godang R Bonvicini G Cinabro D Dubrovin M McGee S Zhou GJ Bornheim A Lipeles E Pappas SP Schmidtler M Shapiro A Sun WM Weinstein AJ Jaffe DE Masek G Paar HP Asner DM Eppich A Hill TS Morrison RJ Briere RA Chen GP Ferguson T Vogel H Gritsan A Alexander JP Baker R Bebek C Berger BE Berkelman K Blanc F Boisvert V Cassel DG Drell PS Duboscq JE Ecklund KM Ehrlich R Foland AD Gaidarev P Galik RS Gibbons L Gittelman B Gray SW Hartill DL Heltsley BK Hopman PI Hsu L 《Physical review letters》2001,86(19):4243-4246
Using 13.7 fb(-1) of data recorded by the CLEO detector at Cornell Electron Storage Ring, we report evidence of two new charmed baryons: one decaying into Xi(0')(c)pi(+) with the subsequent decay Xi(0')(c)-->Xi(0)(c)gamma, and its isospin partner decaying into Xi(+')(c)pi(-) followed by Xi(+')(c)-->Xi(+)(c)gamma. We measure the following mass differences for the two states: M(Xi(0)(c)gammapi(+))-M(Xi(0)(c)) = 318.2+/-1.3+/-2.9 MeV and M(Xi(+)(c)gammapi(-))-M(Xi(+)(c)) = 324.0+/-1.3+/-3.0 MeV. We interpret these new states as the J(P) = 1 / 2(-) Xi(c1) particles, the charmed-strange analogs of the Lambda(+)(c1)(2593). 相似文献
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994.
S. F. Biagi M. Bourquin A. J. Britten R. M. Brown H. Burckhart A. A. Carter J. R. Carter Ch. Doré P. Extermann M. Gailloud C. N. P. Gee W. M. Gibson J. C. Gordon R. J. Gray P. IgoKemenes W. C. Louis T. Modis P. Muhlemann J. Perrier Ph. Rosselet B. J. Saunders P. Schirato H. W. Siebert V. J. Smith D. P. Stickland K. -P. Streit J. J. Thresher R. Weill 《Zeitschrift fur Physik C Particles and Fields》1983,17(2):113-119
TheΞ - p differential elastic cross section has been measured in the SPS hyperon beam at 102 and 135 GeV/c. In the range 0.01<0.42(GeV/c)2, thet distributions are found to be compatible with the formA exp(Bt) whereB is 7.7±0.4(GeV/c)?2 at 102 GeV/c and 8.2 ±0.5(GeV/c)?2 at 135 GeV/c. The corresponding total elastic cross sections areσ el=4.9±0.7 mb andσ el=5.6±0.9 mb, respectively. These results are compared with the predictions of phenomenological models. 相似文献
995.
Spectra at θlab = 8° have been measured for the 92, 94, 96, 98, 100Mo(6Li, 8B)90, 92, 94, 96, 98Zr and 90, 92, 94Zr(6Li, 8B)88, 90, 92Sr two-proton pickup reactions at 90 MeV. The strongest transitions to levels in the Zr isotopes are the 0+ → 0+ transitions to the g.s. and first excited 0+ states. The salient feature of the five Zr spectra is the large increase in 0+2 transition strength relative to that of the g.s. which is observed in the two heaviest isotopes, 96, 98Zr. In 90Zr, the 0+2 transition is weak whereas it is the dominant transition in 98Zr with twice the g.s. strength. These large variations in relative cross section, which are reproduced by DWBA calculations, are attributed to changing g.s. proton configurations in Zr. In the Sr spectra, which are distinctly different from the Zrspectra, the strongest transitions to excited states are to 2+ rather than 0+ states. The (6Li, 8B) reaction seems to be adequately described as a one-step cluster transfer of a T = 1, S = 0 proton pair. The suitability of this reaction for measurements of two-proton pickup is discussed. 相似文献
996.
Chemically prepared δ-MnO2 (sample A) was characterised by chemical and size analyses and by t.g.a. and d.t.a. Sample B was the well-characterised International Common Sample ICS 5, which is a chemical λ-MnO2. Potentiometric acid/base titration of sample A gave a point of zero charge, p.z.c., at pH 3.3±0.5, which is close to the isoelectric point obtained from sedimentation-coagulation results. Fast acid/base titration of sample B gave a p.z.c. at pH 5.9±0.3, which is close to the isoelectric point estimated from electrophoretic measurements. Temperature in the range 298–346 K (25°–73°C) had a minor effect on the titration results. 相似文献
997.
998.
999.
1000.
K.E. Gray 《Solid State Communications》1978,26(10):633-635
Increases of the superconducting energy gap Δ have been measured using an entirely new mechanism of enhancement. Instead of microwave or phonon irradiation, the new mechanism uses quasiparticle tunneling between two identical superconductors at voltages less than 2Δ. A decrease in the quasiparticle density accompanies the increase in Δ. This mechanism has important advantages in making quantitative comparisons with theory. 相似文献