R.D McKeown

Publications (3)0 Total impact

• Source

  Available from: arxiv.org

  Article: The strange quark contribution to the proton's magnetic moment

  D.T Spayde, D.H Beck, R Hasty, T Averett, D Barkhuff, G Dodson, K Dow, M Farkhondeh, W Franklin, E Tsentalovich, [......], B.W Filippone, T.M Ito, R.D McKeown, W Korsch, S Kowalski, B Mueller, M.L Pitt, M.J Ramsey-Musolf, J Ritter, S.P Wells
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  ABSTRACT: We report a new determination of the strange quark contribution to the proton's magnetic form factor at a four-momentum transfer Q2=0.1 (GeV/c)2 from parity-violating e–p elastic scattering. The result uses a revised analysis of data from the SAMPLE experiment which was carried out at the MIT-Bates Laboratory. The data are combined with a calculation of the proton's axial form factor GeA to determine the strange form factor GsM(Q2=0.1)=0.37±0.20±0.26±0.07. The extrapolation of GsM to its Q2=0 limit and comparison with calculations is also discussed.
  Physics Letters B.
• Source

  Available from: Vahagn Gharibyan

  Article: Nuclear effects on R=σL/σT in deep-inelastic scattering

  K Ackerstaff, A Airapetian, N Akopov, I Akushevich, M Amarian, E.C Aschenauer, H Avakian, R Avakian, A Avetissian, B Bains, [......], M.G Vincter, J Visser, E Volk, W Wander, J Wendland, S.E Williamson, T Wise, K Woller, S Yoneyama, H Zohrabian
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  ABSTRACT: Cross section ratios for deep-inelastic scattering from 14N and 3He with respect to 2H have been measured by the HERMES experiment at DESY using a 27.5 GeV positron beam. The data cover a range in the Bjorken scaling variable x between 0.013 and 0.65, while the negative squared four-momentum transfer Q2 varies from 0.5 to 15 GeV2. The data are compared to measurements performed by NMC, E665, and SLAC on 4He and 12C, and are found to be different for x<0.06 and Q2<1.5 GeV2. The observed difference is attributed to an A-dependence of the ratio R=σL/σT of longitudinal to transverse deep-inelastic scattering cross sections at low x and low Q2.
  Physics Letters B.
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  Available from: www-spires.slac.stanford.edu

  Article: A high power liquid hydrogen target for parity violation experiments

  E.J Beise, D.H Beck, E Candell, R Carr, F Duncan, T Forest, W Korsch, J.W Mark, R.D McKeown, B.A Mueller, M Pitt, S Wells
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  ABSTRACT: Parity-violating electron scattering measurements on hydrogen and deuterium, such as those underway at the Bates and CEBAF laboratories, require luminosities exceeding 1038 cm−2s−1, resulting in large beam power deposition into cryogenic liquid. Such targets must be able to absorb 500 W or more with minimal change in target density. A 40 cm long liquid hydrogen target, designed to absorb 500 W of beam power without boiling, has been developed for the SAMPLE experiment at Bates. In recent tests with 40 μA of incident beam, no evidence was seen for density fluctuations in the target, at a sensitivity level of better than 1%. A summary of the target design and operational experience will be presented.
  Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.