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21.
L.R. Cormell M.W. Arenton H.F. Chen M. Corcoran W.R. Ditzler M. Dris A.R. Erwin T. Fields J. Fleischman E. Gardella M. Harrison M.A. Hasan K. Johns A. Kanofsky W. Kononenko C.E. Kuehn H.E. Miettinen B.T. Yost 《Physics letters. [Part B]》1985,150(4):322-326
In an experiment performed at Fermilab we have studied the production of high pt hadron jets from 400 GeV/c pp interactions. A large solid-angle, towered calorimeter was used to trigger and reconstruct the jet events. We report results for inclusive single-jet production and compare those results with QCD predictions and results obtained at the ISR and the SPS Collider. 相似文献
22.
Evidence is presented for the secondary nucleation of beta-L-glutamic acid on the surface of the alpha-polymorph, using a combination of Scanning Electron Microscopy and Raman spectroscopy. 相似文献
23.
Abstract— The picosecond fluorescence kinetics of tryptophan residues in bacteriorhodopsin and some perturbed analogs are measured to study the different tryptophan environments and their changes upon metal cation removal, retinal removal, and M412 trapping. In bacteriorhodopsin, the emission shows four decay components designated Or, C2r, C3r, and C4r in order of increasing lifetimes. The emission wavelength of C3r and C4r is near that found in aqueous solution, while that of C1r is the shortest. The removal of retinal triples the total emission intensity and reduces the number of components to two, suggesting that the observed variation of the lifetimes in bacteriorhodopsin results from the variation of the energy transfer efficiency between different tryptophans and retinal. We conclude that the Or and C2r emission is from the closest tryptophans to the retinal. The quenching of the C3r emission by all metal cations, including those that cannot act as energy acceptors, e.g. Ca2+ , is attributed to protein conformation changes caused by metal cation binding which leads to a stronger energy transfer coupling between tryptophans and retinal. The additional quenching of the C2r emission in Eu3+ bound bacterioopsin is proposed to result from direct energy transfer between tryptophans and Eu3+ . 相似文献
24.
Abouzaid E Arenton M Barker AR Bellantoni L Blucher E Bock GJ Cheu E Coleman R Corcoran MD Cox B Erwin AR Escobar CO Glazov A Golossanov A Gomes RA Gouffon P Hsiung YB Jensen DA Kessler R Kotera K Ledovskoy A McBride PL Monnier E Nguyen H Niclasen R Phillips DG Ping H Ramberg EJ Ray RE Ronquest M Santos E Slater W Smith D Solomey N Swallow EC Toale PA Tschirhart R Velissaris C Wah YW Wang J White HB Whitmore J Wilking MJ Winston R Worcester ET Worcester M Yamanaka T Zimmerman ED 《Physical review letters》2011,107(20):201803
The KTeV E799 experiment has conducted a search for the rare decays, K(L)→π(0)π(0)μ(+)μ(-) and K(L)→π(0)π(0)X(0)→π(0)π(0)μ(+)μ(-), where the X(0) is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 ± 0.5) MeV/c(2). We find no evidence for either decay. We obtain upper limits of Br(K(L)→π(0)π(0)X(0)→π(0)π(0)μ(+)μ(-)) < 1.0 × 10(-10) and Br(K(L)→π(0)π(0)μ(+)μ(-)) < 9.2 × 10(-11) at the 90% confidence level. This result rules out the pseudoscalar X(0) as an explanation of the HyperCP result under the scenario that the dsX(0) coupling is completely real. 相似文献
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27.
Vincent J. Corcoran 《应用光谱学评论》2013,48(2):215-282
Abstract Until recently, infrared spectroscopy has been performed with spectrometers utilizing filtered broadband sources and gratings or prisms to spatially spread the energy spectrum of the source. These wavelength measuring spectrometers characteristically have large spectral tuning ranges with resolutions typically limited to 0.1–1 cm?1: In the far-infrared region where only small amounts of energy are available from broadband sources, two-beam interferometric techniques have been employed with computing techniques to perform Fourier transform spectroscopy. In this technique the entire spectrum to be analyzed is incident upon the detector from the two interfering beams to take advantage of all of the energy available and then computations are made to display the entire spectrum. 相似文献
28.
The stannylation of indole derivatives proceeds in good yields under palladium catalysis (5 mol %) without protection of the indolic nitrogen. The general utility of both PdCl(2)(PhCN)(2)/PCy(3) and Pd(2)dba(3)/PCy(3) as catalytic systems for the stannylation of three indole derivatives, with varying degrees of electron density, is presented. 相似文献
29.
Abouzaid E Arenton M Barker AR Bellantoni L Bellavance A Blucher E Bock GJ Cheu E Coleman R Corcoran MD Corti G Cox B Erwin AR Escobar CO Glazov A Golossanov A Gomes RA Gouffon P Hanagaki K Hsiung YB Huang H Jensen DA Kessler R Kotera K Ledovskoy A McBride PL Monnier E Nelson KS Nguyen H Niclasen R Ping H Qi XR Ramberg EJ Ray RE Ronquest M Santos E Shields J Slater W Smith D Solomey N Swallow EC Toale PA Tschirhart R Velissaris C Wah YW Wang J White HB Whitmore J Wilking M Winstein B Winston R 《Physical review letters》2006,96(10):101801
Using the complete KTeV data set of 5,241 candidate K(L)--> pi(+) pi(-) e(+) e(-) decays (including an estimated background of 204 +/- 14 events), we have measured the coupling g(CR)= 0.163 +/- 0.0149(stat) +/- 0.023(syst) of the CP conserving charge radius process and from it determined a K(0) charge radius of = [-0.077 +/- 0.007(stat) +/- 0.011(syst)]fm(2). We have determined a first experimental upper limit of 0.04 (90% C.L.) /g(e1)/ / /g(M1)/ of the couplings for the E1 and M1 direct photon emission processes. We also report the measurement of /g(M1)/ including a vector form factor /g(M1)/(1 + (a(1)/a(2))/((M(2)(p)-(M(2)(k))= 2M(K)E(gamma*)), where vector /g(M1)/= 1.11+/- 0.12(stat) +/- 0.08(syst) and a(1)/a(2) = [-0.744 +/- 0.027(stat) +/- 0.032(syst)] GeV(2)/c(2). Finally, a CP-violating asymmetry of [13.6 +/- 1.4(stat) +/- 1.5(syst)]% in the CP and T odd angle phi between the decay planes of the e(+) e(-) and pi(+) pi(-) pairs in the K(L) center of mass is reported. 相似文献
30.
Abouzaid E Arenton M Barker AR Bellantoni L Blucher E Bock GJ Cheu E Coleman R Corcoran MD Cox B Erwin AR Escobar CO Glazov A Golossanov A Gomes RA Gouffon P Hsiung YB Jensen DA Kessler R Kotera K Ledovskoy A McBride PL Monnier E Nguyen H Niclasen R Phillips DG Ramberg EJ Ray RE Ronquest M Santos E Slater W Smith D Solomey N Swallow EC Toale PA Tschirhart R Wah YW Wang J White HB Whitmore J Wilking MJ Winstein B Winston R Worcester ET Yamanaka T Zimmerman ED Zukanovich RF;KTeV Collaboration 《Physical review letters》2008,100(18):182001
We present a new determination of the parity of the neutral pion via the double Dalitz decay pi0-->e+e-e+e-. Our sample, which consists of 30,511 candidate decays, was collected from KL-->pi0pi0pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi0 parity and place a limit on scalar contributions to the pi0-->e+e-e+e- decay amplitude of less than 3.3% assuming CPT conservation. The pi0gamma*gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase-space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi0-->e+e-e+e-)=(3.26+/-0.18)x10(-5). 相似文献