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71.
Dugger M Ball JP Collins P Pasyuk E Ritchie BG Adams G Ambrozewicz P Anciant E Anghinolfi M Asavapibhop B Asryan G Audit G Avakian H Bagdasaryan H Baillie N Baltzell NA Barrow S Batourine V Battaglieri M Beard K Bedlinskiy I Bektasoglu M Bellis M Benmouna N Berman BL Bianchi N Biselli AS Bonner BE Bouchigny S Boiarinov S Bradford R Branford D Briscoe WJ Brooks WK Bültmann S Burkert VD Butuceanu C Calarco JR Careccia SL Carman DS Carnahan B Chen S Cole PL Coleman A Coltharp P Cords D 《Physical review letters》2006,96(6):062001
Differential cross sections for the reaction gamma p --> eta' p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the eta'N channel to both the S11(1535) and P11(1710) resonances, known to couple strongly to the etaN channel in photoproduction on the proton, and the importance of J = 3/2 resonances in the process. 相似文献
72.
S. Schumann B. Boillat E. J. Downie P. Aguar-Bartolomé J. Ahrens J. R. M. Annand H. J. Arends R. Beck V. Bekrenev A. Braghieri D. Branford W. J. Briscoe J. W. Brudvik S. Cherepnya R. Codling P. Drexler L. V. Fil’kov D. I. Glazier R. Gregor E. Heid D. Hornidge O. Jahn V. L. Kashevarov R. Kondratiev M. Korolija M. Kotulla D. Krambrich B. Krusche M. Lang V. Lisin K. Livingston S. Lugert I. J. D. MacGregor D. M. Manley M. Martinez-Fabregate J. C. McGeorge D. Mekterovic V. Metag B. M. K. Nefkens A. Nikolaev R. Novotny M. Ostrick R. O. Owens P. Pedroni A. Polonski S. N. Prakhov J. W. Price G. Rosner M. Rost T. Rostomyan D. Sober A. Starostin I. Supek C. M. Tarbert A. Thomas M. Unverzagt Th. Walcher D. P. Watts F. Zehr 《The European Physical Journal A - Hadrons and Nuclei》2010,43(3):269-282
The reaction γp → pπ 0γ′ has been measured with the Crystal Ball/TAPS detectors using the energy-tagged photon beam at the electron accelerator facility MAMI-B. Energy and angular differential cross-sections for the emitted photon γ′ and angular differential cross-sections for the π0 have been determined with high statistics in the energy range of the Δ+ (1232)-resonance. Cross-sections and the ratio of the cross-section to the nonradiative process γp → pπ 0 are compared to theoretical reaction models, having the anomalous magnetic moment κ Δ as free parameter. As the shape of the experimental distributions is not reproduced in detail by the model calculations, currently no extraction of κ Δ is feasible. 相似文献
73.
Baghdasaryan H Weinstein LB Laget JM Adhikari KP Aghasyan M Amarian M Anghinolfi M Avakian H Ball J Battaglieri M Bedlinskiy I Bennett RP Berman BL Biselli AS Bookwalter C Briscoe WJ Brooks WK Bültmann S Burkert VD Carman DS Crede V D'Angelo A Daniel A Dashyan N De Vita R De Sanctis E Deur A Dey B Dickson R Djalali C Dodge GE Doughty D Dupre R Egiyan H El Alaoui A El Fassi L Eugenio P Fegan S Gabrielyan MY Gilfoyle GP Giovanetti KL Gohn W Gothe RW Griffioen KA Guidal M Guo L Gyurjyan V 《Physical review letters》2010,105(22):222501
We have measured the 3He(e,e' pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs by using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum p(tot). For pair relative momenta between 0.3 and 0.5 GeV/c, the ratio is very small at low p(tot) and rises to approximately 0.5 at large p(tot). This shows the dominance of tensor over central correlations at this relative momentum. 相似文献
74.
Avakian H Bosted P Burkert VD Elouadrhiri L Adhikari KP Aghasyan M Amaryan M Anghinolfi M Baghdasaryan H Ball J Battaglieri M Bedlinskiy I Biselli AS Branford D Briscoe WJ Brooks W Carman DS Casey L Cole PL Collins P Crabb D Crede V D'Angelo A Daniel A Dashyan N De Vita R De Sanctis E Deur A Dey B Dhamija S Dickson R Djalali C Dodge G Doughty D Dupre R El Alaoui A Eugenio P Fegan S Fersch R Forest TA Fradi A Gabrielyan MY Gavalian G Gevorgyan N Gilfoyle GP Giovanetti KL Girod FX Gohn W Gothe RW 《Physical review letters》2010,105(26):262002
We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes ? have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q2. A significant nonzero sin2? single spin asymmetry was observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton. 相似文献
75.
76.
W.J.Briscoe Jason Brudvik K.G.Fissum K.Hansen L.Isaksson M.Lundin B.Nilsson B.Schroder 《中国物理C(英文版)》2009,33(12)
The upgrade of the MAX-lab injector and the construction of MAX Ⅲ, provided the opportunity for upgrading the tagged-photon facility and thus lead to the possibility of more extensive program in nuclear physics research. This upgrade increased the injected electron energy to an eventual maximum of 250 MeV and allows for the extraction of electrons from the MAX Ⅰ ring operated in the stretcher mode. The first stretched beam was delivered in September 2005. The tagged-photon facility was commissioned in parallel with the commissioning of new experimental equipment. The PAC approved experimental program is current in progress, including measurements of pion photoproduction below the △(1232). The efforts at the tagged photon-facility are pursued within an international collaboration with around fifty members. 相似文献
77.
In elastomers the crosslink density, the presence of filler particles, and the volumetric confinement toward sorptive dilation can influence the extent of gas mass uptake. In this study the effects of filler particles on the high-pressure gas mass sorption and the volumetric dilation of a silicone elastomer matrix has been investigated. Glass beads, ca. 30 μm radii, with different surface treatments were incorporated as inclusions in various specimens at relatively low concentrations of ca. 10% by volume. The high-pressure gases used were N2 and CO2 up to a maximum ambient pressure of ca. 25 MPa at ca. 20°C and 42°C, respectively. The gas mass sorption was determined by a vibrating reed technique. The sorptive dilation was measured by an ultrasonic transducer operating as a displacement probe. In certain systems the absorbed CO2 gas was able to disrupt the internal interfaces. This led to an increased gas mass uptake in the corrupted specimen. The N2 gas did not affect the interfacial bonds. The amount of penetrant uptake was found generally to be reduced when the internal interfaces were not disrupted. The presence of various internal interfaces restrained the sorptive dilation of the elastomeric matrix. These hindrances to the natural sorptive dilation of the elastomer network suppressed the extent of the gas sorption process. This effect has also been investigated separately in detail using model ‘poker chip’ type of specimens of various aspect ratios. The sorptive dilational characteristics have been correlated with the mechanical properties of similar specimens. The influence of an almost complete volumetric confinement on the gas sorption capacity of the silicone elastomer specimen has also been studied. © 1992 John Wiley & Sons, Inc. 相似文献
78.
REMEDIOS GONZÁLEZ-LUQUE MANUELA MERCHÁN MERCEDES RUBIO LUIS SERRANO-ANDRÉS BJÖRN O. ROOS MIGUEL-ÁNGEL MIRANDA 《Molecular physics》2013,111(13):1977-1982
The lower excited states of 2-benzoylthiophene have been studied using ab initio quantum chemical methods based on multiconfigurational wave functions. Six singlet and six triplet excited states have been characterized. The geometry has been optimized for the two lowest triplet states, which are responsible for the photoreactivity of the chromophore in the photosensitizing drug tiaprofenic acid. The T1(π → π?) and T2(n → π?) states have been found to be close in energy with the π → π? state slightly lower. The excited states have been characterized using density difference and spin density plots. The different photochemical behaviour of the two triplet states can be rationalized from the theoretical data. 相似文献
79.
BJÖRN O. ROOS 《Molecular physics》2013,111(1-2):87-91
Results are presented from a theoretical study of the × 6Σ+, A 6Σ+ and 6Δ electronic states of CrH using multiconfiguration second-order perturbation theory in the multi-state formalism (MS-CASPT2). It is shown that the results for the spectroscopic constants and radiative lifetimes for the A state are in agreement with experiment and an earlier multireference configuration interaction study only if the two close lying × and A states are allowed to interact at a level of approximation that includes dynamic correlation. 相似文献
80.
M. Unverzagt P. Aguar-Bartolomé J. Ahrens J. R. M. Annand H. J. Arends R. Beck V. Bekrenev B. Boillat A. Braghieri D. Branford W. J. Briscoe J. W. Brudvik S. Cherepnya R. Codling E. J. Downie L. V. Fil’kov D. I. Glazier R. Gregor E. Heid D. Hornidge O. Jahn V. L. Kashevarov R. Kondratiev M. Korolija M. Kotulla D. Krambrich B. Krusche M. Lang V. Lisin K. Livingston S. Lugert I. J. D. MacGregor D. M. Manley M. Martinez-Fabregate J. C. McGeorge D. Mekterovic V. Metag B. M. K. Nefkens A. Nikolaev R. Novotny R. O. Owens P. Pedroni A. Polonski S. N. Prakhov J. W. Price G. Rosner M. Rost T. Rostomyan S. Schumann D. Sober A. Starostin I. Supek C. M. Tarbert A. Thomas Th. Walcher D. P. Watts F. Zehr 《The European Physical Journal A - Hadrons and Nuclei》2009,39(2):169-177
A precise measurement of the Dalitz plot parameter, $ \alpha$ , for the $ \eta$ → 3 $ \pi^{0}_{}$ decay is presented. The experiment was performed with the Crystal Ball and TAPS large-acceptance photon detectors at the tagged photon beam facility of the MAMI-B electron accelerator in Mainz. High statistics of 1.8 · 106 $ \eta$ → 3 $ \pi^{0}_{}$ events were obtained, giving the result $ \alpha$ = - 0.032±0.002stat±0.002syst . 相似文献