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Search Results: 1 - 10 of 297433 matches for " J. Grames "
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A polarized positron source for CEBAF
J. Dumas,J. Grames,E. Voutier
Physics , 2009, DOI: 10.1063/1.3232018
Abstract: A compact polarized positron source for Jefferson Lab is discussed. This scheme relies upon a high polarization (85%), high current (1 mA), low-energy (<100 MeV) electron beam to generate polarized positrons in a conversion target via polarized bremsstrahlung and pair creation. GEANT4 is used to simulate source distributions suitable for a CEBAF-like injector with positron polarization ~60% and nano-Ampere intensity. An experiment to test this scheme is outlined.
Polarized Positrons at Jefferson Lab
J. Dumas,J. Grames,E. Voutier
Physics , 2009, DOI: 10.1063/1.3215617
Abstract: A novel concept for producing polarized positrons at Jefferson Lab using the CEBAF polarized electron photo-injector is presented. This approach relies on the polarization transfer from low energy highly polarized electrons to positrons via bremsstrahlung followed by pair production in a conversion target. An experiment to test this concept is discussed on the basis of GEANT4 simulations. It is shown that this low energy approach, which benefits from recent advances in high current high polarization electron sources, can yield positron longitudinal polarization up to 40%.
Ischemic Colitis in an Endurance Runner
Chase Grames,Cristóbal S. Berry-Cabán
Case Reports in Gastrointestinal Medicine , 2012, DOI: 10.1155/2012/356895
Abstract: A 20-year-old female running the Marine Corps Marathon developed diarrhea at mile 12. After finishing the race she noted that she was covered in bloody stool. A local emergency department suspected ischemic colitis. After discharge, her primary care physician instructed her to discontinue the use of all nonsteroidal anti-inflammatory drugs. Her symptoms resolved and she returned to running without any complications. This paper describes the pathophysiology, diagnostic approach, and management options.
Ischemic Colitis in an Endurance Runner
Chase Grames,Cristóbal S. Berry-Cabán
Case Reports in Gastrointestinal Medicine , 2012, DOI: 10.1155/2012/356895
Abstract: A 20-year-old female running the Marine Corps Marathon developed diarrhea at mile 12. After finishing the race she noted that she was covered in bloody stool. A local emergency department suspected ischemic colitis. After discharge, her primary care physician instructed her to discontinue the use of all nonsteroidal anti-inflammatory drugs. Her symptoms resolved and she returned to running without any complications. This paper describes the pathophysiology, diagnostic approach, and management options. 1. Introduction Endurance competitions have become increasingly popular among the general population. From 1980 to 2008 there has been a 197% increase in the number of marathon finishers [1]. The increasing number of amateur athletes participating in endurance events provides physicians with a new set of challenges from managing chronic pain to dealing with race-day injuries. There have been more and more reports of ischemic colitis presenting in young endurance athletes. This case report examines ischemic colitis in a young female who developed bloody diarrhea during the 2010 Marine Corps Marathon. Endurance athletes suffer a myriad of gastrointestinal symptoms during competition and training to include bloating, abdominal cramps, diarrhea, fecal incontinence, heart burn, nausea, vomiting, chest pain, urge to defecate, and bloody stools [2–4]. Gastrointestinal symptoms are reported in 20–50% of endurance athletes, more commonly in females, and more often in runners [5]. Symptoms appear to be more debilitating with longer distances or with greater intensity [6]. 2. Case Presentation A 20-year-old white female student running a marathon in Washington presented to the first aid station at the finish line with dark red bloody diarrhea. Within the first 10 miles she developed an urge and she had multiple small bowel movements between miles 12 and 14. She finished without further incident, but noted bloody stools. Prior to the marathon she had no gastrointestinal complaints. She had a photorefractive keratectomy 3 weeks prior to the race for which she was prescribed ibuprofen (800?mg 3X/D) which she continued during her training period. She denied any recent tobacco, alcohol, or illicit drug use and her family history was noncontributory. Her physical exam was normal; vital signs were stable with the exception of an increased heart rate and evidence of bloody stools on her clothing. Transported to a local hospital she was intravenously rehydrated and discharged without any further work out. The following day she consulted her primary care physician for
MEIC Design Summary
S. Abeyratne,D. Barber,A. Bogacz,P. Brindza,Y. Cai,A. Camsonne,A. Castilla,P. Chevtsov,E. Daly,Y. S. Derbenev,D. Douglas,V. Dudnikov,R. Ent,B. Erdelyi,Y. Filatov,D. Gaskell,J. Grames,J. Guo,L. Harwood,A. Hutton,C. Hyde,K. Jordan,A. Kimber,G. A. Krafft,A. Kondratenko,M. Kondratenko,R. Li,F. Lin,T. Mann,P. McIntyre,T. Michalski,V. S. Morozov,P. Nadel-Turonski,Y. M. Nosochkov,P. N. Ostroumov,K. Park,F. Pilat,M. Poelker,N. J. Pogue,R. Rimmer,Y. Roblin,T. Satogata,A. Sattarov,M. Spata,R. Suleiman,M. Sullivan,A. Sy,C. Tennant,H. Wang,M-H Wang,S. Wang,U. Wienands,H. Zhang,Y. Zhang,Z. Zhao
Physics , 2015,
Abstract: This document summarizes the design of Jefferson Lab's electron-ion collider, MEIC, as of January 20, 2015, and describes the facility whose cost was estimated for the United States Department of Energy Nuclear Sciences Advisory Committee EIC cost review of January 26-28, 2015. In particular, each of the main technical systems within the collider is presented to the level of the best current information.
Early Results from the Qweak Experiment
D. Androic,D. S. Armstrong,A. Asaturyan,T. Averett,J. Balewski,J. Beaufait,R. S. Beminiwattha,J. Benesch,F. Benmokhtar,J. Birchall,R. D. Carlini,G. D. Cates,J. C. Cornejo,S. Covrig,M. M. Dalton,C. A. Davis,W. Deconinck,J. Diefenbach,J. F. Dowd,J. A. Dunne,D. Dutta,W. S. Duvall,M. Elaasar,W. R. Falk,J. M. Finn,T. Forest,D. Gaskel,M. T. W. Gericke,J. Grames,V. M. Gray,K. Grimm,F. Guo,J. R. Hoskins,K. Johnston,D. Jones,M. Jones,R. Jones,M. Kargiantoulakis,P. M. King,E. Korkmaz,S. Kowalski,J. Leacock,J. Leckey,A. R. Lee,J. H. Lee,L. Lee,S. MacEwan,D. Mack,J. A. Magee,R. Mahurin,J. Mammei,J. Martin,M. J. McHugh,D. Meekins,J. Mei,R. Michaels,A. Micherdzinska,A. Mkrtchyan,H. Mkrtchyan,N. Morgan,K. E. Myers,A. Narayan,L. Z. Ndukum,V. Nelyubin,Nuruzzaman,W. T. H van Oers,A. K. Opper,S. A. Page,J. Pan,K. Paschke,S. K. Phillips,M. L. Pitt,M. Poelker,J. F. Rajotte,W. D. Ramsay,J. Roche,B. Sawatzky,T. Seva,M. H. Shabestari,R. Silwal,N. Simicevic,G. R. Smith,P. Solvignon,D. T. Spayde,A. Subedi,R. Subedi,R. Suleiman,V. Tadevosyan,W. A. Tobias,V. Tvaskis,B. Waidyawansa,P. Wang,S. P. Wells,S. A. Wood,S. Yang,R. D. Young,S. Zhamkochyan
Physics , 2013, DOI: 10.1051/epjconf/20146605002
Abstract: A subset of results from the recently completed Jefferson Lab Qweak experiment are reported. This experiment, sensitive to physics beyond the Standard Model, exploits the small parity-violating asymmetry in elastic ep scattering to provide the first determination of the protons weak charge Qweak(p). The experiment employed a 180 uA longitudinally polarized 1.16 GeV electron beam on a 35 cm long liquid hydrogen target. Scattered electrons corresponding to Q2 of 0.025 GeV2 were detected in eight Cerenkov detectors arrayed symmetrically around the beam axis. The goals of the experiment were to provide a measure of Qweak(p) to 4.2 percent (combined statistical and systematic error), which implies a measure of sin2(thetaw) at the level of 0.3 percent, and to help constrain the vector weak quark charges C1u and C1d. The experimental method is described, with particular focus on the challenges associated with the worlds highest power LH2 target. The new constraints on C1u and C1d provided by the subset of the experiments data analyzed to date will also be shown, together with the extracted weak charge of the neutron.
First Determination of the Weak Charge of the Proton
Qweak Collaboration,D. Androic,D. S. Armstrong,A. Asaturyan,T. Averett,J. Balewski,J. Beaufait,R. S. Beminiwattha,J. Benesch,F. Benmokhtar,J. Birchall,R. D. Carlini,G. D. Cates,J. C. Cornejo,S. Covrig,M. M. Dalton,C. A. Davis,W. Deconinck,J. Diefenbach,J. F. Dowd,J. A. Dunne,D. Dutta,W. S. Duvall,M. Elaasar,W. R. Falk,J. M. Finn,T. Forest,D. Gaskell,M. T. W. Gericke,J. Grames,V. M. Gray,K. Grimm,F. Guo,J. R. Hoskins,K. Johnston,D. Jones,M. Jones,R. Jones,M. Kargiantoulakis,P. M. King,E. Korkmaz,S. Kowalski,J. Leacock,J. Leckey,A. R. Lee,J. H. Lee,L. Lee,S. MacEwan,D. Mack,J. A. Magee,R. Mahurin,J. Mammei,J. W. Martin,M. J. McHugh,D. Meekins,J. Mei,R. Michaels,A. Micherdzinska,A. Mkrtchyan,H. Mkrtchyan,N. Morgan,K. E. Myers,A. Narayan,L. Z. Ndukum,V. Nelyubin,Nuruzzaman,W. T. H van Oers,A. K. Opper,S. A. Page,J. Pan,K. D. Paschke,S. K. Phillips,M. L. Pitt,M. Poelker,J. F. Rajotte,W. D. Ramsay,J. Roche,B. Sawatzky,T. Seva,M. H. Shabestari,R. Silwal,N. Simicevic,G. R. Smith,P. Solvignon,D. T. Spayde,A. Subedi,R. Subedi,R. Suleiman,V. Tadevosyan,W. A. Tobias,V. Tvaskis,B. Waidyawansa,P. Wang,S. P. Wells,S. A. Wood,S. Yang,R. D. Young,S. Zhamkochyan
Physics , 2013, DOI: 10.1103/PhysRevLett.111.141803
Abstract: The Qweak experiment has measured the parity-violating asymmetry in polarized e-p elastic scattering at Q^2 = 0.025(GeV/c)^2, employing 145 microamps of 89% longitudinally polarized electrons on a 34.4cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run are reported here, constituting approximately 4% of the data collected in the experiment. From these initial results the measured asymmetry is Aep = -279 +- 35 (statistics) +- 31 (systematics) ppb, which is the smallest and most precise asymmetry ever measured in polarized e-p scattering. The small Q^2 of this experiment has made possible the first determination of the weak charge of the proton, QpW, by incorporating earlier parity-violating electron scattering (PVES) data at higher Q^2 to constrain hadronic corrections. The value of QpW obtained in this way is QpW(PVES) = 0.064 +- 0.012, in good agreement with the Standard Model prediction of QpW(SM) = 0.0710 +- 0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be QnW(PVES+APV) = -0.975 +- 0.010.
The Qweak Experiment: A Search for New Physics at the TeV Scale via a Measurement of the Proton's Weak Charge
R. D. Carlini,J. M. Finn,S. Kowalski,S. A. Page,D. S. Armstrong,A. Asaturyan,T. Averett,J. Benesch,J. Birchall,P. Bosted,A. Bruell,C. L. Capuano,G. Cates,C. Carrigee,S. Chattopadhyay,S. Covrig,C. A. Davis,K. Dow,J. Dunne,D. Dutta,R. Ent,J. Erler,W. Falk,H. Fenker,T. A. Forest,W. Franklin,D. Gaskell,M. Gericke,J. Grames,K. Grimm,F. W. Hersman,D. Higinbotham,M. Holtrop,J. R. Hoskins,K. Johnston,E. Ihloff,M. Jones,R. Jones,K. Joo,J. Kelsey,C. Keppel,M. Khol,P. King,E. Korkmaz,J. Leacock,J. P. Leckey,L. Lee,A. Lung,D. Mack,S. Majewski,J. Mammei,J. Martin,D. Meekins,A. Micherdzinska,A. Mkrtchyan,H. Mkrtchyan,N. Morgan,K. E. Myers,A. Narayan,A. K. Opper,J. Pan,K. Paschke,M. Pitt,M. Poelker,Y. Prok,W. D. Ramsay,M. Ramsey-Musolf,J. Roche,N. Simicevic,G. Smith,T. Smith,P. Souder,D. Spayde,B. E. Stokes,R. Suleiman,V. Tadevosyan,E. Tsentalovich,W. T. H. van Oers,W. Vulcan,P. Wang,S. Wells,S. A. Wood,S. Yang,R. Young,H. Zhu,C. Zorn
Physics , 2012,
Abstract: We propose a new precision measurement of parity-violating electron scattering on the proton at very low Q^2 and forward angles to challenge predictions of the Standard Model and search for new physics. A unique opportunity exists to carry out the first precision measurement of the proton's weak charge, $Q_W =1 - 4\sin^2\theta_W$. A 2200 hour measurement of the parity violating asymmetry in elastic ep scattering at Q^2=0.03 (GeV/c)^2 employing 180 $\mu$A of 85% polarized beam on a 35 cm liquid Hydrogen target will determine the proton's weak charge with approximately 4% combined statistical and systematic errors. The Standard Model makes a firm prediction of $Q_W$, based on the running of the weak mixing angle from the Z0 pole down to low energies, corresponding to a 10 sigma effect in this experiment.
Transverse Beam Spin Asymmetries at Backward Angles in Elastic Electron-Proton and Quasi-elastic Electron-Deuteron Scattering
The G0 Collaboration,D. Androi?,D. S. Armstrong,J. Arvieux,S. L. Bailey,D. H. Beck,E. J. Beise,J. Benesch,F. Benmokhtar,L. Bimbot,J. Birchall,P. Bosted,H. Breuer,C. L. Capuano,Y. -C. Chao,A. Coppens,C. A. Davis,C. Ellis,G. Flores,G. Franklin,C. Furget,D. Gaskell,M. T. W. Gericke,J. Grames,G. Guillard,J. Hansknecht,T. Horn,M. K. Jones,P. M. King,W. Korsch,S. Kox,L. Lee,J. Liu,A. Lung,J. Mammei,J. W. Martin,R. D. McKeown,A. Micherdzinska,M. Mihovilovic,H. Mkrtchyan,M. Muether,S. A. Page,V. Papavassiliou,S. F. Pate,10 S. K. Phillips,P. Pillot,M. L. Pitt,M. Poelker,B. Quinn,W. D. Ramsay,J. -S. Real,J. Roche,P. Roos,J. Schaub,T. Seva,N. Simicevic,G. R. Smith,D. T. Spayde,M. Stutzman,R. Suleiman,V. Tadevosyan,W. T. H. van Oers,M. Versteegen,E. Voutier,W. Vulcan,S. P. Wells,S. E. Williamson,S. A. Wood,B. Pasquini,M. Vanderhaeghen
Physics , 2011, DOI: 10.1103/PhysRevLett.107.022501
Abstract: We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasi-elastic scattering on the deuteron, at backward angles (lab scattering angle of 108 degrees) for Q2 = 0.22 GeV^2/c^2 and 0.63 GeV^2/c^2 at beam energies of 362 MeV and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (piN) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasi-static deuterium approximation, and is also in agreement with theory.
First Measurement of the Neutral Current Excitation of the Delta Resonance on a Proton Target
G0 Collaboration,D. Androic,D. S. Armstrong,J. Arvieux,S. L. Bailey,D. H. Beck,E. J. Beise,J. Benesch,F. Benmokhtar,L. Bimbot,J. Birchall,P. Bosted,H. Breuer,C. L. Capuano,Y. -C. Chao,A. Coppens,C. A. Davis,C. Ellis,G. Flores,G. Franklin,C. Furget,D. Gaskell,J. Grames,M. T. W. Gericke,G. Guillard,J. Hansknecht,T. Horn,M. K. Jones,P. M. King,W. Korsch,S. Kox,L. Lee,J. Liu,A. Lung,J. Mammei,J. W. Martin,R. D. McKeown,A. Micherdzinska,M. Mihovilovic,H. Mkrtchyan,M. Muether,S. A. Page,V. Papavassiliou,S. F. Pate,S. K. Phillips,P. Pillot,M. L. Pitt,M. Poelker,B. Quinn,W. D. Ramsay,J. -S. Real,J. Roche,P. Roos,J. Schaub,T. Seva,N. Simicevic,G. R. Smith,D. T. Spayde,M. Stutzman,R. Suleiman,V. Tadevosyan,W. T. H. van Oers,M. Versteegen,E. Voutier,W. Vulcan,S. P. Wells,S. E. Williamson,S. A. Wood
Physics , 2012,
Abstract: The parity-violating asymmetry arising from inelastic electron-nucleon scattering at backward angle (~95 degrees) near the Delta(1232) resonance has been measured using a hydrogen target. From this asymmetry, we extracted the axial transition form factor G^A_{N\Delta}, a function of the axial Adler form factors C^A_i. Though G^A_{N\Delta} has been previously studied using charged current reactions, this is the first measurement of the weak neutral current excitation of the Delta using a proton target. For Q^2 = 0.34 (GeV/c)^2 and W = 1.18 GeV, the asymmetry was measured to be -33.4 \pm (5.3)_{stat} \pm (5.1)_{sys} ppm. The value of G^A_{N\Delta} determined from the hydrogen asymmetry was -0.05 \pm (0.35)_{stat} \pm (0.34)_{sys} \pm (0.06)_{theory}. These findings agree within errors with theoretical predictions for both the total asymmetry and the form factor. In addition to the hydrogen measurement, the asymmetry was measured at the same kinematics using a deuterium target. The asymmetry for deuterium was determined to be -43.6 \pm (14.6)_{stat} \pm (6.2)_{sys} ppm.
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