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Search Results: 1 - 10 of 191394 matches for " D. Meekins "
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Purple Urine Bag Syndrome
Pauline E Meekins
Western Journal of Emergency Medicine : Integrating Emergency Care with Population Health , 2012,
Abstract: n/a images in emergency medicine
The Jefferson Lab Frozen Spin Target
C. D. Keith,J. Brock,C. Carlin,S. A. Comer,D. Kashy,J. McAndrew,D. G. Meekins,E. Pasyuk,J. J Pierce,M. L. Seely
Physics , 2012, DOI: 10.1016/j.nima.2012.04.067
Abstract: A frozen spin polarized target, constructed at Jefferson Lab for use inside a large acceptance spectrometer, is described. The target has been utilized for photoproduction measurements with polarized tagged photons of both longitudinal and circular polarization. Protons in TEMPO-doped butanol were dynamically polarized to approximately 90% outside the spectrometer at 5 T and 200--300 mK. Photoproduction data were acquired with the target inside the spectrometer at a frozen-spin temperature of approximately 30 mK with the polarization maintained by a thin, superconducting coil installed inside the target cryostat. A 0.56 T solenoid was used for longitudinal target polarization and a 0.50 T dipole for transverse polarization. Spin-lattice relaxation times as high as 4000 hours were observed. We also report polarization results for deuterated propanediol doped with the trityl radical OX063.
Search for Sub-threshold Photoproduction of J/Psi Mesons
P. Bosted,J. Dunne,C. A. Lee,P. Junnarkar,J. Arrington,R. Asaturyan,F. Benmokhtar,M. E. Christy,E. Chudakov,B. Clasie,S. H. Connell,M. M. Dalton,A. Daniel,D. Day,D. Dutta,R. Ent,N. Fomin,D. Gaskell,T. Horn,N. Kalantarians,C. E. Keppel,D. G. Meekins,H. Mkrtchyan,T. Navasardyan,J. Roche,V. M. Rodriguez,D. Kiselev,J. Seely,K. Slifer,M. Strikman,S. Tajima,G. Testa,Roman Trojer,F. R. Wesselmann,S. A. Wood,X. C. Zheng
Physics , 2008, DOI: 10.1103/PhysRevC.79.015209
Abstract: A search was made for sub-threshold $J/\psi$ production from a carbon target using a mixed real and quasi-real Bremsstrahlung photon beam with an endpoint energy of 5.76 GeV. No events were observed, which is consistent with predictions assuming quasi-free production. The results place limits on exotic mechanisms that strongly enhance quasi-free production.
The quasielastic 2H(e,e'p)n reaction at high recoil momenta
P. E. Ulmer,K. A. Aniol,H. Arenhoevel,J. -P. Chen,E. Chudakov,D. Crovelli,J. M. Finn,K. G. Fissum,O. Gayou,J. Gomez,J. -O. Hansen,C. W. de Jager,S. Jeschonnek,M. K. Jones,M. Kuss,J. J. LeRose,M. Liang,R. A. Lindgren,S. Malov,D. Meekins,R. Michaels,J. Mitchell,C. F. Perdrisat,V. Punjabi,R. Roche,F. Sabatie,A. Saha,R. Suleiman,L. Todor,B. B. Wojtsekhowski
Physics , 2001, DOI: 10.1103/PhysRevLett.89.062301
Abstract: The 2H(e,e'p)n cross section was measured in Hall A of the Thomas Jefferson National Accelerator Facility (JLab) in quasielastic kinematics (x=0.96) at a four-momentum transfer squared, Q^2=0.67 (GeV/c)^2. The experiment was performed in fixed electron kinematics for recoil momenta from zero to 550 MeV/c. Though the measured cross section deviates by 1-2 sigma from a state-of-the-art calculation at low recoil momenta, it agrees at high recoil momenta where final state interactions (FSI) are predicted to be large.
The Proton Radius from Electron Scattering Data
Douglas W. Higinbotham,Al Amin Kabir,Vincent Lin,David Meekins,Blaine Norum,Brad Sawatzky
Physics , 2015,
Abstract: In an attempt to understand the discrepancy between the proton radius determined the muonic hydrogen Lamb shift and elastic electron-proton scattering measurements, we carefully review two classic, high precision electron scattering charge form factor, ${G_E}$, results. Upon examination, it was noted that the covariance matrices of common three parameter fits show large parameter correlations. Thus, we reanalyzed the classic data guided by statistical constraints and found low $q^2$, two-parameter fits were actually consistent with muonic hydrogen results. By subsequently including the highest measured values of ${G_E}(q^2)$ in the fits, we found that a dipole function, $G_E(q^2) = ( 1 + q^2/0.66[\rm{GeV}^2])^{-2}$, with the muonic hydrogen radius, 0.84087(39) fm, not only describes the low $q^2$ electron scattering data, but also describes the highest measured $q^2$ $G_E$ values.
x- and xi-scaling of the Nuclear Structure Function at Large x
J. Arrington,C. S. Armstrong,T. Averett,O. K. Baker,L. de Bever,C. W. Bochna,W. Boeglin,B. Bray,R. D. Carlini,G. Collins,C. Cothran,D. Crabb,D. Day,J. A. Dunne,D. Dutta,R. Ent,B. W. Filippone,A. Honegger,E. W. Hughes,J. Jensen,J. Jourdan,C. E. Keppel,D. M. Koltenuk,R. Lindgren,A. Lung,D. J Mack,J. McCarthy,R. D. McKeown,D. Meekins,J. H. Mitchell,H. G. Mkrtchyan,G. Niculescu,I. Niculescu,T. Petitjean,O. Rondon,I. Sick,C. Smith,B. Terburg,W. F. Vulcan,S. A. Wood,C. Yan,J. Zhao,B. Zihlmann
Physics , 2001, DOI: 10.1103/PhysRevC.64.014602
Abstract: Inclusive electron scattering data are presented for ^2H and Fe targets at an incident electron energy of 4.045 GeV for a range of momentum transfers from Q^2 = 1 to 7 (GeV/c)^2. Data were taken at Jefferson Laboratory for low values of energy loss, corresponding to values of Bjorken x greater than or near 1. The structure functions do not show scaling in x in this range, where inelastic scattering is not expected to dominate the cross section. The data do show scaling, however, in the Nachtmann variable \xi. This scaling may be the result of Bloom Gilman duality in the nucleon structure function combined with the Fermi motion of the nucleons in the nucleus. The resulting extension of scaling to larger values of \xi opens up the possibility of accessing nuclear structure functions in the high-x region at lower values of Q^2 than previously believed.
Hard Photodisintegration of a Proton Pair
I. Pomerantz,N. Bubis,K. Allada,A. Beck,S. Beck,B. L. Berman,W. Boeglin,A. Camsonne,M. Canan,K. Chirapatpimol,E. Cisbani,F. Cusanno,C. W. de Jager,C. Dutta,F. Garibaldi,O. Geagla,R. Gilman,J. Glister,D. W. Higinbotham,X. Jiang,A. T. Katramatou,E. Khrosinkova,B. Lee,J. J. LeRose,R. Lindgren,E. McCullough,D. Meekins,R. Michaels,B. Moffit,G. G. Petratos,E. Piasetzky,X. Qian,Y. Qiang,I. Rodriguez,G. Ron,A. Saha,A. J. Sarty,B. Sawatzky,E. Schulte,R. Shneor,N. Sparveris,R. Subedi,S. Strauch,V. Sulkosky,Y. Wang,B. Wojtsekhowski,X. Yan,H. Yao,X. Zhan,X. Zheng
Physics , 2009, DOI: 10.1016/j.physletb.2009.12.050
Abstract: We present a study of high energy photodisintegration of proton-pairs through the gamma + 3He -> p+p+n channel. Photon energies from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. The s-11 scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photodisintegration. For photon energies below the scaling region, the scaled cross section was found to present a strong energy-dependent structure not observed in deuteron photodisintegration.
Determination of the pion charge form factor for Q^2=0.60-1.60 GeV^2
The Fpi-1 collaboration,:,V. Tadevosyan,H. P. Blok,G. M. Huber,D. Abbott,H. Anklin,C. Armstrong,J. Arrington,K. Assamagan,S. Avery,O. K. Baker,C. Bochna,E. J. Brash,H. Breuer,N. Chant,J. Dunne,T. Eden,R. Ent,D. Gaskell,R. Gilman,K. Gustafsson,W. Hinton,H. Jackson,M. K. Jones,C. Keppel,P. H. Kim,W. Kim,A. Klein,D. Koltenuk,M. Liang,G. J. Lolos,A. Lung,D. J. Mack,D. McKee,D. Meekins,J. Mitchell,H. Mkrtchyan,B. Mueller,G. Niculescu I. Niculescu,D. Pitz,D. Potterveld,L. M. Qin,J. Reinhold,I. K. Shin,S. Stepanyan,L. G. Tang,R. L. J. van der Meer,K. Vansyoc,D. Van Westrum,J. Volmer,W. Vulcan,S. Wood,C. Yan,W. -X. Zhao,B. Zihlmann
Physics , 2006, DOI: 10.1103/PhysRevC.75.055205
Abstract: The data analysis for the reaction H(e,e' pi^+)n, which was used to determine values for the charged pion form factor Fpi for values of Q^2=0.6-1.6 GeV^2, has been repeated with careful inspection of all steps and special attention to systematic uncertainties. Also the method used to extract Fpi from the measured longitudinal cross section was critically reconsidered. Final values for the separated longitudinal and transverse cross sections and the extracted values of Fpi are presented.
Probing Quark-Gluon Interactions with Transverse Polarized Scattering
K. Slifer,O. A. Rondon,A. Aghalaryan,A. Ahmidouch,R. Asaturyan,F. Bloch,W. Boeglin,P. Bosted,C. Carasco,R. Carlini,J. Cha,J. P. Chen,M. E. Christy,L. Cole,L. Coman,D. Crabb,S. Danagoulian,D. Day,J. Dunne,M. Elaasar,R. Ent,H. Fenker,E. Frlez,D. Gaskell,L. Gan,J. Gomez,B. Hu,J. Jourdan,M. K. Jones,C. Keith,C. E. Keppel,M. Khandaker,A. Klein,L. Kramer,Y. Liang,J. Lichtenstadt,R. Lindgren,D. Mack,P. McKee,D. McNulty,D. Meekins,H. Mkrtchyan,R. Nasseripour,I. Niculescu,K. Normand,B. Norum,D. Pocanic,Y. Prok,B. Raue,J. Reinhold,J. Roche,D. Kiselev,N. Savvinov,B. Sawatzky,M. Seely,I. Sick,C. Smith,G. Smith,S. Stepanyan,L. Tang,S. Tajima,G. Testa,W. Vulcan,K. Wang,G. Warren,F. R. Wesselmann,S. Wood,C. Yan,L. Yuan,J. Yun,M. Zeier,H. Zhu
Physics , 2008, DOI: 10.1103/PhysRevLett.105.101601
Abstract: We have extracted QCD matrix elements from our data on double polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element \tilde{d_2}, which arises strictly from quark- gluon interactions, to be unambiguously non zero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham Sum rule is valid. The fundamental Bjorken sum rule obtained from the a0 matrix element is satisfied at our low momentum transfer.
Proton Spin Structure in the Resonance Region
RSS Collaboration,F. R. Wesselmann,K. Slifer,S. Tajima,A. Aghalaryan,A. Ahmidouch,R. Asaturyan,F. Bloch,W. Boeglin,P. Bosted,C. Carasco,R. Carlini,J. Cha,J. P. Chen,M. E. Christy,L. Cole,L. Coman,D. Crabb,S. Danagoulian,D. Day,J. Dunne,M. Elaasar,R. Ent,H. Fenker,E. Frlez,L. Gan,D. Gaskell,J. Gomez,B. Hu,M. K. Jones,J. Jourdan,C. Keith,C. E. Keppel,M. Khandaker,A. Klein,L. Kramer,Y. Liang,J. Lichtenstadt,R. Lindgren,D. Mack,P. McKee,D. McNulty,D. Meekins,H. Mkrtchyan,R. Nasseripour,I. Niculescu,K. Normand,B. Norum,D. Pocanic,Y. Prok,B. Raue,J. Reinhold,J. Roche,D. Rohe,O. A. Rondon,N. Savvinov,B. Sawatzky,M. Seely,I. Sick,C. Smith,G. Smith,S. Stepanyan,L. Tang,G. Testa,W. Vulcan,K. Wang,G. Warren,S. Wood,C. Yan,L. Yuan,J. Yun,M. Zeier,H. Zhu
Physics , 2006, DOI: 10.1103/PhysRevLett.98.132003
Abstract: We have examined the spin structure of the proton in the region of the nucleon resonances (1.085 GeV < W < 1.910 GeV) at an average four momentum transfer of Q^2 = 1.3 GeV^2. Using the Jefferson Lab polarized electron beam, a spectrometer, and a polarized solid target, we measured the asymmetries A_parallel and A_perp to high precision, and extracted the asymmetries A_1 and A_2, and the spin structure functions g_1 and g_2. We found a notably non-zero A_perp, significant contributions from higher-twist effects, and only weak support for polarized quark--hadron duality.
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