DRUM :: Browsing by Author "Beise, E.J."

Browsing by Author "Beise, E.J."

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Charged pion form factor between Q2=0.60 and 2.45 GeV2. II. Determination of, and results for, the pion form factor
(2008-10) Huber, G.M.; Blok, H.P.; Horn, T.; Beise, E.J.; Gaskell, D.; Mack, D.J.; Tadevosyan, V.; Volmer, J.; Abbott, D.; Aniol, K.; Anklin, H.; Armstrong, C.; Arrington, J.; Assamagan, K.; Avery, S.; Baker, O.K.; Barrett, B.; Bochna, C.; Boeglin, W.; Brash, E.J.; Breuer, H.; Chang, C.C.; Chant, N.; Christy, M.E.; Dunne, J.; Eden, T.; Ent, R.; Fenker, H.; Gibson, E.F.; Gilman, R.; Gustafsson, K.; Hinton, W.; Holt, J.; Jackson, H.; Jin, S.; Jones, M.K.; Keppel, C.E.; Kim, P.H.; Kim, W.; King, P.M.; Klein, A.; Koltenuk, D.; Kovaltchouk, V.; Liang, M.; Liu, J.; Lolos, G.J.; Lung, A.; Margaziotis, D.J.; Markowitz, P.; Matsumura, A.; McKee, D.; Meekins, D.; Mitchell, J.; Miyoshi, T.; Mkrtchyan, H.; Mueller, B.; Niculescu, G.; Niculescu, I.; Okayasu, Y.; Pentchev, L.; Perdrisat, C.; Pitz, D.; Potterveld, D.; Punjabi, V.; Qin, L.M.; Reimer, P.E.; Reinhold, J.; Roche, J.; Roos, P.G.; Sarty, A.; Shin, I.K.; Smith, G.R.; Stepanyan, S.; Tang, L.G.; Tvaskis, V.; van der Meer, R.L.J.; Vansyoc, K.; VanWestrum, D.; Vidakovic, S.; Vulcan, W.; Warren, G.; Wood, S.A.; Xu, C.; Yan, C.; Zhao, W.-X.; Zheng, X.; Zihlmann, B.; The Jefferson Lab Fπ Collaboration
The charged pion form factor, Fπ(Q2), is an important quantity that can be used to advance our knowledge of hadronic structure. However, the extraction of Fπ from data requires a model of the 1H(e,e'π+)n reaction and thus is inherently model dependent. Therefore, a detailed description of the extraction of the charged pion form factor from electroproduction data obtained recently at Jefferson Lab is presented, with particular focus given to the dominant uncertainties in this procedure. Results for Fπ are presented for Q2=0.60-2.45 GeV2. Above Q2=1.5 GeV2, the Fπ values are systematically below the monopole parametrization that describes the low Q2 data used to determine the pion charge radius. The pion form factor can be calculated in a wide variety of theoretical approaches, and the experimental results are compared to a number of calculations. This comparison is helpful in understanding the role of soft versus hard contributions to hadronic structure in the intermediate Q2 regime.
Coherent π0 photoproduction on the deuteron up to 4 GeV
(1999-09) Meekins, D.G.; Abbott, D.J.; Ahmidouch, A.; Armstrong, C.S.; Arrington, J.; Assamagan, K.A.; Baker, O.K.; Barrow, S.P.; Beatty, D.P.; Beck, D.H.; Beedoe, S.Y.; Beise, E.J.; Belz, J.E.; Bochna, C.; Bosted, P.E.; Brash, E.J.; Breuer, H.; Cadman, R.V.; Cardman, L.; Carlini, R.D.; Cha, J.; Chant, N.S.; Collins, G.; Cothran, C.; Cummings, W.J.; Danagoulian, S.; Duncan, F.A.; Dunne, J.A.; Dutta, D.; Eden, T.; Ent, R.; Filippone, B.W.; Forest, T.A.; Fortune, H.T.; Frolov, V.V.; Gao, H.; Geesaman, D.F.; Gilman, R.; Gueye, P.L.J.; Gustafsson, K.K.; Hansen, J.-O.; Harvey, M.; Hinton, W.; Holt, R.J.; Jackson, H.E.; Keppel, C.E.; Khandaker, M.A.; Kinney, E.R.; Klein, A.; Koltenuk, D.M.; Kumbartzki, G.; Lung, A.F.; Mack, D.J.; Madey, R.; Markowitz, P.; McFarlane, K.W.; McKeown, R.D.; Meziani, Z.-E.; Miller, M.A.; Mitchell, J.H.; Mkrtchyan, H.G.; Mohring, R.M.; Napolitano, J.; Nathan, A.M.; Niculescu, G.; Niculescu, I.; O'Neill, T.G.; Owen, B.R.; Pate, S.F.; Potterveld, D.H.; Price, J.W.; Rakness, G.L.; Ransome, D.; Reinhold, J.; Rutt, P.M; Salgado, C.W.; Savage, G.; Segel, R.E.; Simicevic, N.; Stoler, P.; Suleiman, R.; Tang, L.; Terburg, B.P.; van Westrum, D.; Vulcan, W.F.; Williamson, S.E.; Witkowski, M.T.; Wood, S.A.; Yan, C.; Zeidman, B.
The differential cross section for 2H(γ,d)π0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions.
Determination of the Charged Pion Form Factor at Q2=1.60 and 2.45 (GeV/c)2
(2006-11) Horn, T.; Aniol, K.; Arrington, J.; Barrett, B.; Beise, E.J.; Blok, H.P.; Boeglin, W.; Brash, E.J.; Breuer, H.; Chang, C.C.; Christy, M.E.; Ent, R.; Gaskell, D.; Gibson, E.; Holt, R.J.; Huber, G.M.; Jin, S.; Jones, M.K.; Keppel, C.E.; Kim, W.; King, P.M.; Kovaltchouk, V.; Liu, J.; Lolos, G.J.; Mack, D.J.; Margaziotis, D.J.; Markowitz, P.; Matsumura, A.; Meekins, D.; Miyoshi, T.; Mkrtchyan, H.; Niculescu, I.; Okayasu, Y.; Pentchev, L.; Perdrisat, C.; Potterveld, D.; Punjabi, V.; Reimer, P.; Reinhold, J.; Roche, J.; Roos, P.G.; Sarty, A.; Smith, G.R.; Tadevosyan, V.; Tang, L.G.; Tvaskis, V.; Vidakovic, S.; Volmer, J.; Vulcan, W.; Warren, G.; Wood, S.A.; Xu, C.; Zheng, X.; The Jefferson Lab Fπ-2 Collaboration
The 1H(e,e′π+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W =2.22 GeV. The charged pion form factor (Fπ) was extracted from the data by comparing the separated longitudinal pion electropro- duction cross section to a Regge model prediction in which Fπ is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative Quantum Chromo-Dynamics prediction.
Determination of the neutron electric form factor in quasielastic scattering of polarized electrons from polarized 3He
(1991-08) Jones-Woodward, C.E.; Beise, E.J.; Belz, J.E.; Carr, R.W.; Filippone, B.W.; Lorenzon, W.; McKeown, R.D.; Mueller, B.A.; O'Neill, T.G.; Dodson, G.; Dow, K.; Farkhondeh, M.; Kowalski, S.; Lee, K.; Makins, N.; Milner, R.; Thompson, A.; Teiger, D.; van den Brand, J.F.L.; Young, A.; Yu, X.; Zumbro, J.D.
We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized 3He gas target. The asymmetry is measured at kinematics sensitive to the transverse-longitudinal response function RTL(Q2,ω). The value of the neutron electric form factor GEn(Q2=0.16 (GeV/c2))=+0.070±0.100±0.035 is extracted from the asymmetry using a Faddeev calculation of the 3He wave function.
Determination of the Pion Charge Form Factor at Q2=1.60 and 2.45 (GeV/c)2
(American Physical Society, 2006-11-10) Horn, D.T.; Aniol, K.; Arrington, J.; Barret, B.; Beise, E.J.; Blok, H.P.; Boeglin, W.; Brash, E.J.; Breuer, H.; Chang, C.C.; Christy, M.E.; Ent, R.; Gaskell, D.; Gibson, E.; Holt, R.J.; Huber, G.M.; Jin, S.; Jones, M.K.; Keppel, C.E.; Kim, W.; King, P.M.; Kovaltchouk, V.; Liu, J.; Lolos, G.J.; Mack, D.J.; Margaziotis, D.J.; Markowitz, P.; Matsumura, A.; Meekins, D.; Miyoshi, T.; Mkrtchyan, H.; Niculescu, I.; Okayasu, Y.; Pentchev, L.; Perdrisat, C.; Potterveld, D.; Punjabi, V.; Reimer, P.; Reinhold, J.; Roche, J.; Roos, P.G.; Sarty, A.; Smith, G.R.; Tadevosyan, V.; Tang, L.G.; Tvaskis, V.; Vidakovic, S.; Volmer, J.; Vulcan, W.; Warren, G.; Wood, S.A.; Xu, C.; X. Zheng, X.; Jefferson Lab F_{π} Collaboration
The 1H(e,e′π+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (Fπ) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which Fπ is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.
Evidence for virtual Compton scattering from the proton
(1995-11) van der Brand, J.F.J.; Ent, R.; Anthony, P.L.; Arnold, R.G.; Arrington, J.; Beise, E.J.; Belz, J.E.; Bosted, P.E.; Bulten, H.-J.; Chapman, M.S.; Coulter, K.P.; Dietrich, F.S.; Epstein, M.; Filippone, B.W.; Gao, H.; Gearheat, R.A.; Geesaman, D.F.; Hansen, J.-O.; Holt, R.J.; Jackson, H.E.; Jones, C.E.; Margaziotis, D.J.; McKeown, R.D.; Milner, R.G.; Mueller, B.; Napolitano, J.; Nelson, J.; Keppel, C.E.; Kinney, R.D.; Kuhn, S.; Lee, K.; Lorenzon, W.; Lung, A.; Makins, N.C.R.; O'Neill, T.G.; Papavassiliou, V.; Petratos, G.; Potterveld, D.H.; Rock, S.E.; Spengos, M.; Szalata, Z.M.; Tao, L.H.; van Bibber, K.; Wasson, D.A.; White, J.L.; Zeidman, B.
In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation.
Exclusive 16O(γ,π-p) reaction in the Δ resonance region
(1992-08) Pham, L.D.; Høibråten, S.; Redwine, R.P.; Tieger, D.R.; van der Steenhoven, G.; Wilson, K.E.; Yuly, M.E.; Federspiel, F.J.; Eisenstein, R.A.; Nathan, A.M.; Wood, S.A.; Beise, E.J.
We report the first exclusive (γ,π-p) measurements on a complex nucleus. The 16O(γ,π-p) reaction was measured at pion laboratory angles of 64° and 120°. Coincident protons were detected over the quasifree angular correlation range using a vertical array of seven plastic scintillator detectors spanning ±33° about the scattering plane. The cross sections are compared to factorized distorted-wave impulse approximation calculations; these provide a good description of the backward angle data, but are in serious disagreement with the forward angle data.
Exclusive Electron Scattering from Deuterium at High Momentum Transfer
(American Physical Society, 1995-06-12) Bulten, H.J.; Anthony, P.L.; Arnold, R.G.; Arrington, J.; Beise, E.J.; Belz, E.; van Bibber, K.; Bosted, P.E.; van den Brand, J.F.J.; Chapman, M.S.; Coulter, K.P.; Dietrich, F.S.; Ent, R.; Epstein, M.; Filippone, B.W.; Gao, H.; Gearhart, R.A.; Geesaman, D.F.; Holt, R.J.; Jackson, H.E.; Jones, C.E.; Keppel, C.E.; Kinney, E.; Kuhn, S.E.; Lee, K.; Lorenzon, W.; Lung, A.; Makins, N.C.R.; Margaziotis, D.J.; McKeown, R.D.; Milner, R.G.; Mueller, B.; Napolitano, J.; Nelson, J.; O'Neill, T.G.; Papavassiliou, V.; Petratos, G.G.; Rock, S.E.; Spengos, M.; Szalata, Z.M.; Tao, L.H.; White, J.L.; Zeidman, B.
Cross sections are presented for the reaction 2H(e,e′p)n for momentum transfers in the range 1.2≤Q2≤6.8(GeV/c)2 and for missing momenta from 0 to 250 MeV/c. The longitudinal-transverse interference structure function has been separated at Q2 = 1.2(GeV/c)2. The observables are compared to calculations performed in nonrelativistic and relativistic frameworks. The data are best described by a fully relativistic calculation.
He→3(e→e′) quasielastic asymmetry
(1993-01) Jones, C.E.; Beise, E.J.; Belz, J.E.; Carr, R.W.; Filippone, B.W.; Lorenzon, W.; McKeown, R.D.; Mueller, B.A.; O'Neill, T.G.; Dodson, G.W.; Dow, K.; Farkhondeh, M.; Kowalski, S.; Lee, K.; Makins, N.; Milner, R.; Thompson, A.; Teiger, D.; van den Brand, J.F.L.; Young, A.; Yu, X.; Zumbro, J.D.
Measurements of the spin-dependent asymmetry in scattering longitudinally polarized electrons from polarized He3 at quasielastic kinematics are reported. The measurements were made at two kinematics and spin angles, one sensitive to the helicity-dependent transverse-longitudinal interference response function, RTL′, and the other to the helicity-dependent transverse response function, RT′. For the experiment a metastability exchange optically pumped polarized He3 target was used; a general discussion of the technique used to polarized the He3, along with the details of the design and operation of the target system, are presented here. A comparison is made of the world’s data on the He→3(e→,e′) quasielastic asymmetry with several theoretical predictions, including calculations that use the plane wave impulse approximation and a fully spin-dependent spectral function. There is good agreement between data and theory at the current level of experimental precision.
Inclusive electron scattering from nuclei at x≃1
(1996-05) Arrington, J.; Anthony, P.; Arnold, R.G.; Beise, E.J.; Belz, J.E.; Bosted, P.E.; Bulten, H.-J.; Chapman, M.S.; Coulter, K.P.; Dietrich, F.; Ent, R.; Epstein, M.; Filippone, B.W.; Gao, H.; Gearhart, R.A.; Geesaman, D.F.; Hansen, J.-O.; Holt, R.J.; Jackson, H.E.; Jones, C.E.; Keppel, C.E.; Kinney, E.R.; Kuhn, S.; Lee, K.; Lorenzon, W.; Lung, A.; Makins, N.C.R.; Margaziotis, D.J.; McKeown, R.D.; Milner, R.G.; Mueller, B.; Napolitano, J.; Nelson, J.; O'Neill, T.G.; Papavassiliou, V.; Petratos, G.G.; Potterveld, D.H.; Rock, S.E.; Spengos, M.; Szalata, Z.M.; Tao, L.H.; van Bibber, K.; van den Brand, J.F.J.; White, J.L.; Winter, D.; Zeidman, B.
The inclusive A(e,e′) cross section for x≃1 was measured on 2H, C, Fe, and Au for momentum transfers Q2 from 1 to 6.8 (GeV/c)2. The scaling behavior of the data was examined in the region of transition from y scaling to x scaling. Throughout this transitional region, the data exhibit ξ scaling, reminiscent of the Bloom-Gilman duality seen in free nucleon scattering.
Measurement of 16O(γ,n)15O at medium energies
(1989-05) Beise, E.J.; Dodson, G.; Garçon, M.; Høibråten, S.; Maher, C.; Pham, L.D.; Redwine, R.P.; Sapp, W.; Wilson, K.E.; Wood, S.A.; Deady, M.
Exclusive differential cross sections for the 16O(γ,n)15O process have been measured for Eγ=150, 200, and 250 MeV and θL=49°, 59°, and 88°. This measurement is the first of its type to be reported for the energy region above the pion production threshold. An uncollimated bremsstrahlung beam was incident on an H2O target, and neutrons were measured with a recoil proton spectrometer with resolution sufficient to identify the residual 15O ground state. The results are compared to (γ,p) data and to calculations including effects from meson exchange currents.
Measurement of inclusive quasielastic scattering of polarized electrons from polarized 3He
(1990-08) Woodward, C.E.; Beise, E.J.; Belz, J.E.; Carr, R.W.; Filippone, B.W.; Lorenzon, W.B.; McKeown, R.D.; Mueller, B.; O'Neill, T.G.; Dodson, G.; Dow, K.; Farkhondeh, M.; Kowalski, S.; Lee, K.; Makins, N.; Milner, R.; Thompson, A.; Tieger, D.; van den Brand, J.; Young, A.; Yu, X.; Zumbro, J.
We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized 3He gas target. This measurement represents the first demonstration of a new method for studying electromagnetic nuclear structure: the scattering of polarized electrons from a polarized nuclear target. The measured asymmetry is in good agreement with a Faddeev calculation and supports the picture of spin-dependent quasielastic scattering from polarized 3He as predominantly scattering from a polarized neutron.
Measurement of Tensor Polarization in Elastic Electron-Deuteron Scattering at Large Momentum Transfer
(American Physical Society, 2000-05-29) Abbott, D.; Ahmidouch, A.; Anklin, H.; Arvieux, J.; Ball, J.; Beedoe, S.; Beise, E.J.; Bimbot, L.; Boeglin, W.; Breuer, H.; Brindza, P.; Carlini, R.; Chant, N.S.; Danagoulian, S.; Dow, K.; Ducret, J.-E.; Dunne, J.; Ewell, L.; Eyraud, L.; Furget, C.; Garcon, M.; Gilman, R.; Glashausser, C.; Gueye, P.; Gustafsson, K.; Hafidi, K.; Honegger, A.; Jourdan, J.; Kox, S.; Kumbartzki, G.; Lu, L.; Mack, D.; Markowitz, P.; McIntyre, J.; Meekins, D.; Merchez, F.; Mitchell, J.; Mohring, R.; Mtingwa, S.; Mrktchyan, H.; Pitz, D.; Qin, L.; Ransome, R.D.; Real, J.-S.; Roos, P.G.; Rutt, P.; Sawafta, R.; Stepanyan, S.; Tieulent, R.; Tomasi-Gustafsson, E.; Turchinetz, W.; Vansyoc, K.; Volmer, J.; Voutier, E.; Vulcan, W.; Williamson, C.; Wood, S.A.; Yan, C.; Zhao, J.; Zhao, W.; Lung, A.; Jefferson Lab t20 Collaboration
Tensor polarization observables ( t20, t21, and t22) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7(GeV/c)2. The experiment was performed at the Jefferson Laboratory in Hall C using the electron High Momentum Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q2 the deuteron charge form factors GC and GQ. They are in good agreement with relativistic calculations and disagree with perturbative QCD predictions.
Measurement of tensor polarization in elastic electron-deuteron scattering in the momentum-transfer range 3.8≤q≤4.6 fm-1
(1991-07) The, I.; Arvieux, J.; Beck, D.H.; Beise, E.J.; Boudard, A.; Cairns, E.B.; Cameron, J.M.; Dodson, G.W.; Dow, K.A.; Farkhondeh, M.; Fielding, H.W.; Flanz, J.B.; Garcon, M.; Goloskie, R.; Hoibraten, S.; Jourdan, J.; Kowalski, S.; Lapointe, C.; McDonald, W.J.; Ni, B.; Pham, L.D.; Redwine, R.P.; Rodning, N.L.; Roy, G.; Schulze, M.E.; Souder, P.A.; Soukup, J.; Turchinetz, W.E.; Williamson, C.F.; Wilson, K.E.; Wood, S.A.; Zeigler, W.
The tensor polarization t20 of the recoil deuteron in elastic e-d scattering has been measured for three values of four-momentum transfer, q=3.78, 4.22, and 4.62 fm-1. The data have been used to locate the first node in the charge monopole form factor of the deuteron at q=4.39±0.16 fm-1. The results for t20 are in reasonable agreement with expectations based on the nucleon-meson description of nuclear dynamics
Measurement of the analyzing power Ay0 for the reaction H(p⃗,d)π+ between 1000 and 1300 MeV
(1998-01) Goy, J.; Furget, C.; Kox, S.; Pastor, A.; Real, J.S.; Arvieux, J.; Beise, E.J.; Bimbot, L.; Brash, E.; Breuer, H.; Collins, G.; Duncan, F.; Ducret, J.E.; Garçon, M.; Gilmas, R.; Glashausser, C.; Ladygine, V.P.; Morlet, M.; Merchez, F.; Rutt, P.; Tomasi-Gustaffson, E.; Voutier, E.
The analyzing power Ay0 of the reaction H(p⃗,d)π+ has been measured at a fixed value of the Mandelstam variable ud=-0.17GeV2 for nine proton energies between 1000 and 1300 MeV. The experiment was performed at SATURNE with the SPES1 spectrometer. The data exhibit structure around √s≃2.37GeV. The origin of this structure could be related to a resonancelike behavior of the 1S0P or 1G4F partial amplitudes.
Measurement of the neutron magnetic form factor from inclusive quasielastic scattering of polarized electrons from polarized 3He
(1994-08) Gao, A.; Arrington, J.; Beise, E.J.; Bray, B.; Carr, R.W.; Filippone, B.W.; Lung, A.; McKeown, R.D.; Mueller, B.; Pitt, M.L.; Jones, C.E.; DeSchepper, D.; Dodson, G.; Dow, K.; Ent, R.; Farkhondeh, M.; Hansen, J.-O.; Korsch, W.; Kramer, L.H.; Lee, K.; Makins, N.; Milner, R.G.; Teiger, D.R.; Welch, T.P.; Candell, E.; Napolitano, J.; Wojtsekhowski, B.B.; Tripp, C.; Lorenzon, W.
We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized 3He target. The neutron magnetic form factor GMn has been extracted from the measured asymmetry based on recent PWIA calculations using spin-dependent spectral functions. Our determination of GMn at Q2=0.19 (GeV/c)2 agrees with the dipole parametrization. This experiment represents the first measurement of the neutron magnetic form factor using spin-dependent electron scattering.
Measurement of the Proton's Neutral Weak Magnetic Form Factor
(American Physical Society, 1997-05-19) Mueller, B.; Beck, D.H.; Beise, E.J.; Candell, E.; Cardman, L.; Carr, R.; DiBari, R.C.; Dodson, G.; Dow, K.; Duncan, F.; Farkhondeh, M.; Filippone, B.W.; Forest, T.; Gao, H.; Korsch, W.; Kowalski, S.; Lung, A.; McKeown, R.D.; Mohring, R.; Napolitano, J.; Nilsson, D.; Pitt, M.; Simicevic, N.; Terburg, B.; Wells, S.P.; SAMPLE Collaboration
We report the first measurement of the parity-violating asymmetry in elastic electron scattering from the proton. The asymmetry depends on the neutral weak magnetic form factor of the proton which contains new information on the contribution of strange quark-antiquark pairs to the magnetic moment of the proton. We obtain the value GMZ = 0.34±0.09±0.04±0.05n.m. at Q2 = 0.1 (GeV/c)2.
Measurement of the spin-dependent asymmetry in 3→(e→,e′) inelastic scattering at low energy transfer
(1995-09) Arrington, J.; Beise, E.J.; Bray, B.; Carr, R.W.; Filippone, B.W.; Gao, H.; Lung, A.; McKeown, R.D.; Mueller, B.; Pitt, M.L.; DeSchepper, D.; Dodson, G.; Dow, K.; Ent, R.; Farkhondeh, M.; Hansen, J.-O.; Korsch, W.; Kramer, L.H.; Lee, K.; Makins, N.C.R.; Milner, R.G.; Teiger, D.R.; Welch, T.P.; Candell, E.; Napolitano, J.; Tripp, C.; Wojtsekhowski, B.B.
We present the results of a measurement of the spin-dependent asymmetry in 3→(e→,e′) inelastic scattering at kinematics on the low-energy transfer side of the quasielastic peak, including the region near the breakup threshold. Comparison with existing calculations based upon the plane wave impulse approximation shows significant deviation between the data and the model near the breakup threshold. Good agreement between data and theory is seen at higher energy transfer.
Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of double photon exchange amplitudes
(2001-05) Wells, S.P.; Averett, T.; Barkhuff, D.; Beck, D.H.; Beise, E.J.; Benson, C.; Breuer, H.; Carr, R.; Covrig, S.; DelCorso, J.; Dodson, G.; Eppstein, C.; Farkhondeh, M.; Filippone, B.W.; Forest, T.; Frasier, P.; Hasty, R.; Ito, T.M.; Jones, C.; Korsch, W.; Kowalski, S.; Lee, P.; Maneva, E.; McCarty, K.; McKeown, R.D.; Mikell, J.; Mueller, B.; Naik, P.; Pitt, M.L; Ritter, J.; Savu, V.; Spayde, D.T.; Sullivan, M.; Tieulent, R.; Tsentalovich, E.; Yang, B.; Zwart, T.; SAMPLE Collaboration
We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q2 = 0.1 (GeV/c)2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, plane wave impulse approximation for this reaction, and can therefore provide information on double photon exchange amplitudes for electro- magnetic interactions with hadronic systems. We find a non-zero value of A=-15.4±5.4 ppm. No calculations of this observable for nuclei other than spin 0 have been carried out in these kinematics, and the calculation using the spin orbit interaction from a charged point nucleus of spin 0 cannot describe these data.
Measurements of Deuteron Photodisintegration up to 4.0 GeV
(American Physical Society, 1998-11-23) Bochna, C.; Terburg, B.P.; Abbott, D.J.; Ahmidouch, A.; Armstrong, C.S.; Arrington, J.; Assamagan, K.A.; Baker, O.K.; Barrow, S.P.; Beatty, D.P.; Beck, D.H.; Beedoe, S.Y.; Beise, E.J.; Belz, J.E.; Bosted, P.E.; Brash, E.J.; Breuer, H.; Cadman, R.V.; Cardman, L.; Carlini, R.D.; Cha, J.; Chant, N.S.; Collins, G.; Cothran, C.; Cummings, W.J.; Danagoulian, S.; Duncan, F.A.; Dunne, J.A.; Dutta, D.; Eden, T.; Ent, R.; Filippone, B.W.; Forest, T.A.; Fortune, H.T.; Frolov, V.V.; Gao, H.; Geesaman, D.F.; Gilman, R.; Gueye, P.L.J.; Gustafsson, K.K.; Hansen, J.-O.; Harvey, M.; Hinton, W.; Holt, R.J.; Jackson, H.E.; Keppel, C.E.; Khandaker, M.A.; Kinney, E.R.; Klein, A.; Koltenuk, D.M.; Kumbartzki, G.; Lung, A.F.; Mack, D.J.; Madey, R.; Markwoitz, P.; McFarlane, K.W.; McKeown, R.D.; Meekins, D.G.; Meziani, Z.-E.; Miller, M.A.; Mitchell, J.H.; Mkrtchyan, H.G.; Mohring, R.M.; Napolitano, J.; Nathan, A.M.; Niculescu, G.; Niculescu, I.; O'Neill, T.G.; Owen, B.R.; Pate, S.F.; Potterveld, D.H.; Price, J.W.; Rakness, G.L.; Ransome, R.; Reinhold, J.; Rutt, P.M.; Salgado, C.W.; Savage, G.; Segel, R.; Simicevic, N.; Stoler, P.; Suleiman, R.; Tang, L.; van Westrum, D.; Vulcan, W.F.; Williamson, S.; Witkowski, M.T.; Wood, S.A.; Yan, C.; Zeidman, B.
The first measurements of the differential cross section for the d(γ,p)n reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36°, 52°, 69°, and 89°. These results are in reasonable agreement with previous measurements at lower energy. The 89° and 69° data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52° and 36° data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.