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41.
Chen S Avakian H Burkert VD Eugenio P Adams G Amarian M Ambrozewicz P Anghinolfi M Asryan G Bagdasaryan H Baillie N Ball JP Baltzell NA Barrow S Batourine V Battaglieri M Beard K Bedlinskiy I Bektasoglu M Bellis M Benmouna N Berman BL Biselli AS Bonner BE Bouchigny S Boiarinov S Bosted P Bradford R Branford D Briscoe WJ Brooks WK Bültmann S Butuceanu C Calarco JR Careccia SL Carman DS Carnahan B Cazes A Cole PL Collins P Coltharp P Cords D Corvisiero P Crabb D Crannell H Crede V Cummings JP 《Physical review letters》2006,97(7):072002
The longitudinal target-spin asymmetry AUL for the exclusive electroproduction of high-energy photons was measured for the first time in ep-->e;'pgamma. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinvarphi moment is 0.252+/-0.042stat+/-0.020sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H. 相似文献
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The principles employed for calculating relaxation effects by numerical analysis with a computer are outlined. Results are expressed as tables of ratios which can be incorporated into a general computer program for application to experimental conductivity measurements. As an example of such applications, data for aqueous solutions of MgSO4 have been analyzed. 相似文献
44.
Beulen MW Bugler J de Jong MR Lammerink B Huskens J Schonherr H Vancso GJ Boukamp BA Wieder H Offenhauser A Knoll W van Veggel FC Reinhoudt DN 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(7):1176-1183
We have developed synthesis routes for the introduction of short and long dialkylsulfides onto the primary side of alpha-, beta-, and gamma-cyclodextrins. Monolayers of these cyclodextrin adsorbates were characterized by electrochemistry, wettability studies, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and atomic force microscopy (AFM). The differences in thickness and polarity of the outerface of the monolayers were measured by electro-chemistry and wettability studies. On average about 70% of the sulfide moieties were used for binding to the gold, as measured by XPS. Tof-SIMS measurements showed that the cyclodextrin adsorbates adsorb without any bond breakage. AFM measurements revealed for beta-cyclodextrin monolayers a quasi-hexagonal lattice with a lattice constant of 20.6 A, which matches the geometrical size of the adsorbate. The alpha-cyclodextrin and gamma-cyclodextrin monolayers are less ordered. Interactions of the anionic guests 1-anilinonaphthalene-8-sulfonic acid (1,8-ANS) and 2-(p-toluidinyl)naphthalene-6-sulfonic acid (2,6-TNS) and the highly ordered monolayers of heptapodant beta-cyclodextrin adsorbates were studied by surface plasmon resonance (SPR) and electrochemical impedance spectroscopy. The SPR measurements clearly showed interactions between a beta-cyclodextrin monolayer and 1,8-ANS. Electrochemical impedance spectroscopy measurements gave high responses even at low guest concentrations (< or = 5 microM). The association constant for the binding of 1,8-ANS (K = 289,000 +/- 13,000M-1) is considerably higher than the corresponding value in solution. (Partial) methylation of the secondary side of the beta-cyclodextrin strongly decreases the binding. 相似文献
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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
47.
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
48.
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
49.
Scott D. Harvey Martin Liezers Kathryn C. Antolick Ben J. Garcia Luke E. Sweet April J. Carman Gregory C. Eiden 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1885-1898
Several porous chromatographic materials were investigated as synthetic substrates for preparing surrogate nuclear explosion debris particles. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110 °C) to drive off water, and then treating them at high temperatures (up to 800 °C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-point metals were loaded on core–shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies characterized material balance and the formation of recalcitrant species. Metal loading was 1.5–3 times higher than expected from the pore volume alone, a result attributed to surface coating. Most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating selective loading. High-temperature treatments caused reduced solubility of several metals, and the loss of some volatile species (rhenium and tellurium). Sample preparation reproducibility was high (the inter- and intra-batch relative standard deviations were 7.8 and 0.84 %, respectively) indicating suitability for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in radioanalytical methods development and/or serve as a starting material for the synthesis of more complex nuclear explosion debris forms (e.g., Trinitite). 相似文献
50.
Battaglieri M De Vita R Kubarovsky V Guo L Mutchler GS Stoler P Weygand DP Ambrozewicz P Anghinolfi M Asryan G Avakian H Bagdasaryan H Baillie N Ball JP Baltzell NA Batourine V Bedlinskiy I Bellis M Benmouna N Berman BL Biselli AS Bouchigny S Boiarinov S Bradford R Branford D Briscoe WJ Brooks WK Bültmann S Burkert VD Butuceanu C Calarco JR Careccia SL Carman DS Chen S Clinton E Cole PL Coltharp P Crabb D Crannell H Cummings JP Dale D De Sanctis E Degtyarenko PV Deur A Dharmawardane KV 《Physical review letters》2006,96(4):042001
The exclusive reaction gammap-->K0K+n was studied in the photon energy range between 1.6 and 3.8 GeV searching for evidence of the exotic baryon Theta+ (1540)-->nK+. The decay to nK+requires the assignment of strangeness S=+1 to any observed resonance. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility corresponding to an integrated luminosity of 70 pb-1. No evidence for the Theta+ pentaquark was found. Upper limits were set on the production cross section as function of center-of-mass angle and nK+ mass. The 95% C.L. upper limit on the total cross section for a narrow resonance at 1540 MeV was found to be 0.8 nb. 相似文献