排序方式: 共有190条查询结果,搜索用时 15 毫秒
31.
Abulencia A Acosta D Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Bachacou H Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Ben-Haim E Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Bishai M 《Physical review letters》2006,96(1):011802
We present a search for neutral supersymmetric Higgs bosons decaying to tau pairs produced in pp collisions at square root of s = 1.96 TeV. The data, corresponding to 310 pb(-1) integrated luminosity, were collected with the Collider Detector at Fermilab in run II of the Tevatron. No significant excess above the standard model backgrounds is observed. We set exclusion limits on the production cross section times branching fraction to tau pairs for Higgs boson masses in the range from 90 to 250 GeV/c2. 相似文献
32.
Bergeal N Dubost V Noat Y Sacks W Roditchev D Emery N Hérold C Marêché JF Lagrange P Loupias G 《Physical review letters》2006,97(7):077003
We present scanning tunneling microscopy and spectroscopy of the newly discovered superconductor CaC6. The tunneling conductance spectra, measured between 3 and 15 K, show a clear superconducting gap in the quasiparticle density of states. The gap function extracted from the spectra is in good agreement with the conventional BCS theory with Delta0=1.6+/-0.2 meV. The possibility of gap anisotropy and two-gap superconductivity is also discussed. In a magnetic field, direct imaging of the vortices allows us to deduce a coherence length in the ab plane xiab approximately 33 nm. 相似文献
33.
Abulencia A Acosta D Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Bachacou H Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Ben Haim E Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Blair RE 《Physical review letters》2006,97(6):062003
We present the first precise measurement of the Bs0-Bs0 oscillation frequency Deltams. We use 1 fb-1 of data from pp collisions at sqrts=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. The sample contains signals of 3600 fully reconstructed hadronic Bs decays and 37,000 partially reconstructed semileptonic Bs decays. We measure the probability as a function of proper decay time that the Bs decays with the same, or opposite, flavor as the flavor at production, and we find a signal consistent with Bs0-Bs0 oscillations. The probability that random fluctuations could produce a comparable signal is 0.2%. Under the hypothesis that the signal is due to Bs0-Bs0 oscillations, we measure Deltams=17.31(-0.18)+0.33(stat)+/-0.07(syst) ps-1 and determine |Vtd/Vts|=0.208(-0.002)+0.001(expt)-0.006(+0.008)(theor). 相似文献
34.
Abulencia A Acosta D Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Bachacou H Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Haim EB Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Blair RE 《Physical review letters》2006,96(23):231801
We report the first observation of B(0)(s)-->Psi(2S)Phi decay in p(p_) collisions at square root of 8=1.96 TeV using 360 pb(-1) of data collected by the CDF II detector at the Fermilab Tevatron. We observe 20.2 +/- 5.0 and 12.3 +/- 4.1 B(0)(s)-->Psi(2S)Phi candidates, in Psi(2S)-->mu(+)mu(-) and Phi(2S)-->J/Phipi(+)pi(-) decay modes, respectively. We present a measurement of the relative branching fraction Beta(B(0)(s)-->Psi(2S)Phi)/Beta(B(0)(s)-->J/PsiPhi)=0.52 +/- 0.13(stat) +/- 0.04(syst) +/- 0.06(BR) using the Psi(2S)-->mu(+)mu(-) decay mode. 相似文献
35.
Abulencia A Acosta D Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Bachacou H Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Haim EB Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Blair RE 《Physical review letters》2006,96(21):211802
We describe a general search for resonances decaying to a neutral emu final state in pp collisions at a center-of-mass energy of 1.96 TeV. Using a data sample representing 344 pb(-1) of integrated luminosity recorded by the Collider Detector at Fermilab II experiment, we compare standard model predictions with the number of observed events for invariant masses between 50 and 800 GeV/c2. Finding no significant excess (5 events observed vs 7.7 +/- 0.8 expected for M(emu) > 100 GeV/c2 ), we set limits on sneutrino and Z' masses as functions of lepton family number violating couplings. 相似文献
36.
Baumberg JJ Kavokin AV Christopoulos S Grundy AJ Butté R Christmann G Solnyshkov DD Malpuech G von Högersthal GB Feltin E Carlin JF Grandjean N 《Physical review letters》2008,101(13):136409
We observe the buildup of strong (approximately 50%) spontaneous vector polarization in emission from a GaN-based polariton laser excited by short optical pulses at room temperature. The Stokes vector of emitted light changes its orientation randomly from one excitation pulse to another, so that the time-integrated polarization remains zero. This behavior is completely different from any previous laser. We interpret this observation in terms of the spontaneous symmetry breaking in a Bose-Einstein condensate of exciton polaritons. 相似文献
37.
Kuo HT Bagkar NC Liu RS Shen CH Shy DS Xing XK Lee JF Chen JM 《The journal of physical chemistry. B》2008,112(36):11250-11257
In the present investigation, we report the transformation of alpha-LiVOPO 4 to alpha-Li 3V 2(PO 4) 3, leading to an enhancement of capacity. The alpha-LiVOPO 4 sample was synthesized by a sol-gel method, followed by sintering at 550-650 degrees C in a flow of 5% H 2/Ar. The structural transformation of a triclinic alpha-LiVOPO 4 structure to a monoclinic alpha-Li 3V 2(PO 4) 3 structure was observed at higher sintering temperatures (700-800 degrees C in a flow of 5% H 2/Ar). The alpha-Li 3V 2(PO 4) 3 phase was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis, and X-ray absorption near edge spectrum (XANES) techniques. The valence shift of vanadium ions from +4 to +3 states was observed using in situ XANES experiments at V K-edge. The structural transformation is ascertained by the shape changes in pre-edge and near edge area of X-ray absorption spectrum. It was observed that the capacity was enhanced from 140 mAh/g to 164 mAh/g via structural transformation process of LiVOPO 4 to Li 3V 2(PO 4) 3. 相似文献
38.
Hennet L Pozdnyakova I Bytchkov A Price DL Greaves GN Wilding M Fearn S Martin CM Thiaudière D Bérar JF Boudet N Saboungi ML 《The Journal of chemical physics》2007,126(7):074906
The authors have studied the structural evolution of the fragile glass-forming liquid CaAl2O4 during supercooling from the stable liquid phase to the cold glass below Tg. The evolution is characterized by a sharpening of the first diffraction peak and a shortening of the average nearest-neighbor bond length around 1.25Tg, indicating an increase in the degree of both intermediate-range and short-range orders occurring close to the dynamical crossover temperature. The cooling curve developed a kink at this temperature, indicating a simultaneous change in thermodynamic properties. 相似文献
39.
Chan TS Liu RS Yang CC Li WH Lien YH Huang CY Lee JF 《The journal of physical chemistry. B》2007,111(9):2262-2267
The effect of isovalent chemical substitution of Eu3+ into the Tb3+ sites on the magnetic and electrical properties of (Tb1-xEux)MnO3 (0 = x = 1.0) system has been investigated. The orthorhombic structure with space group Pbnm is observed in this series of materials. An increase in Mn-O bond distance with increasing Eu content leads to improvement in the overlap between the Mn 3d and O 2p orbital thereby causing a decrease in activation energy and resistivity. Moreover, as the Eu content increases, the effective moments (mueff) are reduced linearly and an exchange coupling is observed in Tb-Tb, Tb-Eu, and Eu-Eu complexes for x = 0.1 and 0.3 samples. Both these features can be related to the substitution of bigger Eu3+ ions replacing the original Tb-Tb coupling. 相似文献
40.
Measurement techniques for unsteady flows in turbomachines 总被引:4,自引:0,他引:4
The growing interest for unsteady flows in turbomachines over the last two decades has led to an intensive development of
fast response measurement techniques, capable of resolving with high frequency phenomena related to inlet distortion, rotating
stall and blade row interference effects with blade passing frequencies ranging from 3 to 30 kHz. This development was favoured
by major advances in sensor technology and data acquisition systems. The paper reviews the progress in fast response measurement
techniques for high speed turbomachinery and application with emphasis on fast response pressure and temperature probes and
blade surface sensors including pressure, heat transfer and shear stress determination.
Received: 9 November 1998/Accepted: 21 September 1999 相似文献