G. Warren - University of Basel

G. Warren
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G. Warren
University of Basel

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Nuclear Experiment (28)
Physics - Instrumentation and Detectors (3)
High Energy Physics - Experiment (3)
High Energy Physics - Phenomenology (2)
Astrophysics (1)
Physics - Accelerator Physics (1)

Publications Authored By G. Warren

Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the quark dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available for the longitudinal structure function in particular. Here we present separated structure functions for hydrogen and deuterium at low four--momentum transfer squared, Q^2< 1 GeV^2, and compare these with parton distribution parameterizations and a k_T factorization approach. Read More

Pacific Northwest National Laboratory has recently opened a shallow underground laboratory intended for measurement of low-concentration levels of radioactive isotopes in samples collected from the environment. The development of a low-background liquid scintillation counter is currently underway to further augment the measurement capabilities within this underground laboratory. Liquid scintillation counting is especially useful for measuring charged particle (e. Read More

Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, $Q^2$, and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon degrees of freedom at long distances to quark-gluon degrees of freedom at short scales. Ratios of separated response functions in $\pi^-$ and $\pi^+$ electroproduction are particularly informative. The ratio for transverse photons may allow this transition to be more easily observed, while the ratio for longitudinal photons provides a crucial verification of the assumed pole dominance, needed for reliable extraction of the pion form factor from electroproduction data. Read More

Affiliations: 1The Jefferson Lab Fpi Collaboration, 2The Jefferson Lab Fpi Collaboration, 3The Jefferson Lab Fpi Collaboration, 4The Jefferson Lab Fpi Collaboration, 5The Jefferson Lab Fpi Collaboration, 6The Jefferson Lab Fpi Collaboration, 7The Jefferson Lab Fpi Collaboration, 8The Jefferson Lab Fpi Collaboration, 9The Jefferson Lab Fpi Collaboration, 10The Jefferson Lab Fpi Collaboration, 11The Jefferson Lab Fpi Collaboration, 12The Jefferson Lab Fpi Collaboration, 13The Jefferson Lab Fpi Collaboration, 14The Jefferson Lab Fpi Collaboration, 15The Jefferson Lab Fpi Collaboration, 16The Jefferson Lab Fpi Collaboration, 17The Jefferson Lab Fpi Collaboration, 18The Jefferson Lab Fpi Collaboration, 19The Jefferson Lab Fpi Collaboration, 20The Jefferson Lab Fpi Collaboration, 21The Jefferson Lab Fpi Collaboration, 22The Jefferson Lab Fpi Collaboration, 23The Jefferson Lab Fpi Collaboration, 24The Jefferson Lab Fpi Collaboration, 25The Jefferson Lab Fpi Collaboration, 26The Jefferson Lab Fpi Collaboration, 27The Jefferson Lab Fpi Collaboration, 28The Jefferson Lab Fpi Collaboration, 29The Jefferson Lab Fpi Collaboration, 30The Jefferson Lab Fpi Collaboration, 31The Jefferson Lab Fpi Collaboration, 32The Jefferson Lab Fpi Collaboration, 33The Jefferson Lab Fpi Collaboration, 34The Jefferson Lab Fpi Collaboration, 35The Jefferson Lab Fpi Collaboration, 36The Jefferson Lab Fpi Collaboration, 37The Jefferson Lab Fpi Collaboration, 38The Jefferson Lab Fpi Collaboration, 39The Jefferson Lab Fpi Collaboration, 40The Jefferson Lab Fpi Collaboration, 41The Jefferson Lab Fpi Collaboration, 42The Jefferson Lab Fpi Collaboration, 43The Jefferson Lab Fpi Collaboration, 44The Jefferson Lab Fpi Collaboration, 45The Jefferson Lab Fpi Collaboration, 46The Jefferson Lab Fpi Collaboration, 47The Jefferson Lab Fpi Collaboration, 48The Jefferson Lab Fpi Collaboration, 49The Jefferson Lab Fpi Collaboration, 50The Jefferson Lab Fpi Collaboration, 51The Jefferson Lab Fpi Collaboration, 52The Jefferson Lab Fpi Collaboration, 53The Jefferson Lab Fpi Collaboration, 54The Jefferson Lab Fpi Collaboration, 55The Jefferson Lab Fpi Collaboration, 56The Jefferson Lab Fpi Collaboration, 57The Jefferson Lab Fpi Collaboration, 58The Jefferson Lab Fpi Collaboration, 59The Jefferson Lab Fpi Collaboration, 60The Jefferson Lab Fpi Collaboration, 61The Jefferson Lab Fpi Collaboration, 62The Jefferson Lab Fpi Collaboration, 63The Jefferson Lab Fpi Collaboration, 64The Jefferson Lab Fpi Collaboration, 65The Jefferson Lab Fpi Collaboration, 66The Jefferson Lab Fpi Collaboration, 67The Jefferson Lab Fpi Collaboration, 68The Jefferson Lab Fpi Collaboration, 69The Jefferson Lab Fpi Collaboration, 70The Jefferson Lab Fpi Collaboration, 71The Jefferson Lab Fpi Collaboration, 72The Jefferson Lab Fpi Collaboration, 73The Jefferson Lab Fpi Collaboration, 74The Jefferson Lab Fpi Collaboration, 75The Jefferson Lab Fpi Collaboration, 76The Jefferson Lab Fpi Collaboration, 77The Jefferson Lab Fpi Collaboration, 78The Jefferson Lab Fpi Collaboration, 79The Jefferson Lab Fpi Collaboration, 80The Jefferson Lab Fpi Collaboration, 81The Jefferson Lab Fpi Collaboration, 82The Jefferson Lab Fpi Collaboration, 83The Jefferson Lab Fpi Collaboration, 84The Jefferson Lab Fpi Collaboration, 85The Jefferson Lab Fpi Collaboration, 86The Jefferson Lab Fpi Collaboration, 87The Jefferson Lab Fpi Collaboration, 88The Jefferson Lab Fpi Collaboration

The study of exclusive $\pi^{\pm}$ electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio $R_L=\sigma_L^{\pi^-}/\sigma_L^{\pi^+}$ is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of $R_T=\sigma_T^{\pi^-}/\sigma_T^{\pi^+}$ from unity at small $-t$, to 1/4 at large $-t$, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Read More

Authors: The Mu2e Project, Collaboration, :, R. J. Abrams, D. Alezander, G. Ambrosio, N. Andreev, C. M. Ankenbrandt, D. M. Asner, D. Arnold, A. Artikov, E. Barnes, L. Bartoszek, R. H. Bernstein, K. Biery, V. Biliyar, R. Bonicalzi, R. Bossert, M. Bowden, J. Brandt, D. N. Brown, J. Budagov, M. Buehler, A. Burov, R. Carcagno, R. M. Carey, R. Carosi, M. Cascella, D. Cauz, F. Cervelli, A. Chandra, J. K. Chang, C. Cheng, P. Ciambrone, R. N. Coleman, M. Cooper, M. C. Corcoran, M. Cordelli, Y. Davydov, A. L. de Gouvea, L. De Lorenzis, P. T. Debevec, F. DeJongh, C. Densham, G. Deuerling, J. Dey, S. Di Falco, S. Dixon, R. Djilkibaev, B. Drendel, E. C. Dukes, A. Dychkant, B. Echenard, R. Ehrlich, N. Evans, D. Evbota, I. Fang, J. E. Fast, S. Feher, M. Fischler, M. Frank, E. Frlez, S. S. Fung, G. Gallo, G. Galucci, A. Gaponenko, K. Genser, S. Giovannella, V. Glagolev, D. Glenzinski, D. Gnani, S. Goadhouse, G. D. Gollin, C. Grace, F. Grancagnolo, C. Group, J. Hanson, S. Hanson, F. Happacher, E. Heckmaier, D. Hedin, D. W. Hertzog, R. Hirosky, D. G. Hitlin, E. Ho, X. Huang, E. Huedem, P. Q. Hung, E. V. Hungerford, T. Ito, W. Jaskierny, R. Jedziniak, R. P. Johnson, C. Johnstone, J. A. Johnstone, S. A. Kahn, P. Kammel, T. I. Kang, V. S. Kashikhin, V. V. Kashikhin, P. Kasper, D. M. Kawall, V. Khalatian, M. Kim, A. Klebaner, D. Kocen, Y. Kolomensky, I. Kourbanis, J. Kowalkowski, J. Kozminski, K. Krempetz, K. S. Kumar, R. K. Kutschke, R. Kwarciany, T. Lackowski, M. Lamm, M. Larwill, K. Lau, M. J. Lee, A. L'Erario, T. Leveling, G. Lim, C. Lindenmeyer, V. Logashenko, T. Lontadze, M. Lopes, A. Luca, K. R. Lynch, T. Ma, A. Maffezzoli, W. J. Marciano, M. Martini, W. Masayoshi, V. Matushko, M. McAteer, R. McCrady, A. Moccoli, L. Michelotti, J. P. Miller, S. Miscetti, W. Molzon, J. Morgan, A. Mukherjee, S. Nagaitsev, V. Nagaslaev, J. Niehoff, D. V. Neuffer, T. Nicol, A. J. Norman, B. Norris, J. Odell, S. Oh, Y. Oksuzian, G. Onorato, J. Orduna, D. Orris, R. Ostojic, T. Page, K. D. Paschke, G. Pauletta, T. Peterson, G. M. Piacentino, G. Pileggi, A. Pla-Dalmau, D. Pocanic, C. C. Polly, V. Polychronakos, B. Ponzio, M. Popovic, J. L. Popp, F. Porter, E. Presbys, P. Prieto, V. Pronskikh, F. Puccinelli, R. Rabehl, J. Ramsey, R. E. Ray, R. Rechenmacher, S. Rella, L. Ristori, R. Rivera, B. L. Roberts, T. J. Roberts, P. Rubinov, V. L. Rusu, A. Saputi, I. Sarra, Y. Smertzidis, P. Shanahan, A. Simonenko, J. Steward, I. Suslov, C. Sylvester, Z. Tang, M. Tartaglia, G. Tassielli, V. Tereshchenko, J. Theilacker, J. Tompkins, R. Tschirhart, G. Van Zandbergen, C. Vannini, G. Venanzoni, H. von der Lippe, R. Wagner, J. P. Walder, R. Walton, S. Wands, S. Wang, G. Warren, S. Werkema, H. B. White Jr, R. Wielgos, L. S. Wood, M. Woodward, J. Wu, M. Xiao, R. Yamada, P. Yamin, K. Yarritu, K. Yonehara, C. Yoshikawa, Z. You, G. Yu, A. Yurkewicz, G. Zavarise, R. Y. Zhu

Mu2e at Fermilab will search for charged lepton flavor violation via the coherent conversion process mu- N --> e- N with a sensitivity approximately four orders of magnitude better than the current world's best limits for this process. The experiment's sensitivity offers discovery potential over a wide array of new physics models and probes mass scales well beyond the reach of the LHC. We describe herein the conceptual design of the proposed Mu2e experiment. Read More

A large set of cross sections for semi-inclusive electroproduction of charged pions ($\pi^\pm$) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared $W^2$ > 4 GeV$^2$ and range in four-momentum transfer squared $2 < Q^2 < 4$ (GeV/c)$^2$, and cover a range in the Bjorken scaling variable 0.2 < x < 0. Read More

Authors: G0 Collaboration, D. Androic, D. S. Armstrong, J. Arvieux, R. Asaturyan, T. D. Averett, S. L. Bailey, G. Batigne, D. H. Beck, E. J. Beise, J. Benesch, F. Benmokhtar, L. Bimbot, J. Birchall, A. Biselli, P. Bosted, H. Breuer, P. Brindza, C. L. Capuano, R. D. Carlini, R. Carr, N. Chant, Y. -C. Chao, R. Clark, A. Coppens, S. D. Covrig, A. Cowley, D. Dale, C. A. Davis, C. Ellis, W. R. Falk, H. Fenker, J. M. Finn, T. Forest, G. Franklin, R. Frascaria, C. Furget, D. Gaskell, M. T. W. Gericke, J. Grames, K. A. Griffioen, K. Grimm, G. Guillard, B. Guillon, H. Guler, K. Gustafsson, L. Hannelius, J. Hansknecht, R. D. Hasty, A. M. Hawthorne Allen, T. Horn, T. M. Ito, K. Johnston, M. Jones, P. Kammel, R. Kazimi, P. M. King, A. Kolarkar, E. Korkmaz, W. Korsch, S. Kox, J. Kuhn, J. Lachniet, R. Laszewski, L. Lee, J. Lenoble, E. Liatard, J. Liu, A. Lung, G. A. MacLachlan, J. Mammei, D. Marchand, J. W. Martin, D. J. Mack, K. W. McFarlane, D. W. McKee, R. D. McKeown, F. Merchez, M. Mihovilovic, A. Micherdzinska, H. Mkrtchyan, B. Moffit, M. Morlet, M. Muether, J. Musson, K. Nakahara, R. Neveling, S. Niccolai, D. Nilsson, S. Ong, S. A. Page, V. Papavassiliou, S. F. Pate, S. K. Phillips, P. Pillot, M. L. Pitt, M. Poelker, T. A. Porcelli, G. Quemener, B. P. Quinn, W. D. Ramsay, A. W. Rauf, J. -S. Real, T. Ries, J. Roche P. Roos, G. A. Rutledge, J. Schaub, J. Secrest, T. Seva, N. Simicevic, G. R. Smith, D. T. Spayde, S. Stepanyan, M. Stutzman, R. Suleiman, V. Tadevosyan, R. Tieulent, J. van de Wiele, W. T. H. van Oers, M. Versteegen, E. Voutier, W. F. Vulcan, S. P. Wells, G. Warren, S. E. Williamson, R. J. Woo, S. A. Wood, C. Yan, J. Yun, V. Zeps

In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. Read More

Affiliations: 1nee Rohe, 2nee Rohe, 3nee Rohe, 4nee Rohe, 5nee Rohe, 6nee Rohe, 7nee Rohe, 8nee Rohe, 9nee Rohe, 10nee Rohe, 11nee Rohe, 12nee Rohe, 13nee Rohe, 14nee Rohe, 15nee Rohe, 16nee Rohe, 17nee Rohe, 18nee Rohe, 19nee Rohe, 20nee Rohe, 21nee Rohe, 22nee Rohe, 23nee Rohe, 24nee Rohe, 25nee Rohe, 26nee Rohe, 27nee Rohe, 28nee Rohe, 29nee Rohe, 30nee Rohe, 31nee Rohe, 32nee Rohe, 33nee Rohe, 34nee Rohe, 35nee Rohe, 36nee Rohe, 37nee Rohe, 38nee Rohe, 39nee Rohe, 40nee Rohe, 41nee Rohe, 42nee Rohe, 43nee Rohe, 44nee Rohe, 45nee Rohe, 46nee Rohe, 47nee Rohe, 48nee Rohe, 49nee Rohe, 50nee Rohe, 51nee Rohe, 52nee Rohe

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. Read More

Cross sections for the reaction ${^1}$H($e,e'\pi^+$)$n$ were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the CEBAF high-intensity, continous electron beam in order to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from $Q^2$=0.60 to 2. Read More

The charged pion form factor, Fpi(Q^2), is an important quantity which can be used to advance our knowledge of hadronic structure. However, the extraction of Fpi from data requires a model of the 1H(e,e'pi+)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. Read More

Precise measurements of the deuteron vector analyzing power Ayd and the tensor analyzing power Ayy of the H(d,gamma)He-3 capture reaction have been performed at deuteron energies of 29MeV and 45MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction. Read More

We have carried out an (e,e'p) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment confirms by direct measurement the correlated strength predicted by theory. Read More

Affiliations: 1for the Jefferson Lab E93-026 Collaboration, 2for the Jefferson Lab E93-026 Collaboration, 3for the Jefferson Lab E93-026 Collaboration, 4for the Jefferson Lab E93-026 Collaboration, 5for the Jefferson Lab E93-026 Collaboration, 6for the Jefferson Lab E93-026 Collaboration, 7for the Jefferson Lab E93-026 Collaboration

The electric form factor of the neutron was determined from measurements of the \vec{d}(\vec{e},e' n)p reaction for quasielastic kinematics. Polarized electrons were scattered off a polarized deuterated ammonia target in which the deuteron polarization was perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle detector. Read More

Asymmetries in quasi-elastic pol 3He(pol e,e'p) have been measured at a momentum transfer of 0.67 (GeV/c)^2 and are compared to a calculation which takes into account relativistic kinematics in the final state and a relativistic one-body current operator. With an exact solution of the Faddeev equation for the 3He-ground state and an approximate treatment of final state interactions in the continuum good agreement is found with the experimental data. Read More

Affiliations: 1OOPS Collaboration, 2OOPS Collaboration, 3OOPS Collaboration, 4OOPS Collaboration, 5OOPS Collaboration, 6OOPS Collaboration, 7OOPS Collaboration, 8OOPS Collaboration, 9OOPS Collaboration, 10OOPS Collaboration, 11OOPS Collaboration, 12OOPS Collaboration, 13OOPS Collaboration, 14OOPS Collaboration, 15OOPS Collaboration, 16OOPS Collaboration, 17OOPS Collaboration, 18OOPS Collaboration, 19OOPS Collaboration, 20OOPS Collaboration, 21OOPS Collaboration, 22OOPS Collaboration, 23OOPS Collaboration, 24OOPS Collaboration, 25OOPS Collaboration, 26OOPS Collaboration, 27OOPS Collaboration, 28OOPS Collaboration, 29OOPS Collaboration, 30OOPS Collaboration, 31OOPS Collaboration, 32OOPS Collaboration, 33OOPS Collaboration, 34OOPS Collaboration, 35OOPS Collaboration, 36OOPS Collaboration, 37OOPS Collaboration, 38OOPS Collaboration, 39OOPS Collaboration, 40OOPS Collaboration, 41OOPS Collaboration, 42OOPS Collaboration, 43OOPS Collaboration, 44OOPS Collaboration, 45OOPS Collaboration, 46OOPS Collaboration, 47OOPS Collaboration

Quadrupole amplitudes in the $\gamma^{*}N\to\Delta$ transition are associated with the issue of nucleon deformation. A search for these small amplitudes has been the focus of a series of measurements undertaken at Bates/MIT by the OOPS collaboration. We report on results from H$(e,e^\prime p)\pi^0$ data obtained at $Q^2= 0. Read More

Polarization transfer in the 4He(e,e'p)3H reaction at a Q^2 of 0.4 (GeV/c)^2 was measured at the Mainz Microtron MAMI. The ratio of the transverse to the longitudinal polarization components of the ejected protons was compared with the same ratio for elastic ep scattering. Read More

For experiments of the type A(\vec e,e'\vec p) the 3-spectrometer setup of the A1 collaboration at MAMI has been supplemented by a focal plane proton-polarimeter. To this end, a carbon analyzer of variable thickness and two double-planes of horizontal drift chambers have been added to the standard detector system of Spectrometer A. Due to the spin precession in the spectrometer magnets, all three polarization components at the target can be measured simultaneously. Read More

Lorentz time is replaced by three parameters: a global time, a local rate of aging, and a new spatial coordinate. This enables successful reconstruction of relativity's observables in a four dimensional Euclidean hyperspace. The new formulation predicts that the age of the universe, as inferred from the Hubble Constant, is less than the observed evolutionary age of astronomical configurations, as has been repeatedly measured. Read More

Affiliations: 1University of Basel, 2University of Basel, 3University of Basel, 4University of Basel, 5University of Basel, 6University of Basel, 7University of Basel, 8University of Basel, 9University of Basel, 10University of Basel, 11Jefferson Lab, 12Jefferson Lab, 13University of Virginia, 14University of Virginia, 15University of Virginia, 16University of Virginia

We have built a polarimeter in order to measure the electron beam polarization in hall C at JLAB. Using a superconducting solenoid to drive the pure-iron target foil into saturation, and a symmetrical setup to detect the Moller electrons in coincidence, we achieve an accuracy of <1%. This sets a new standard for Moller polarimeters. Read More

We present the first measurement of the induced proton polarization P_n in pi^0 electroproduction on the proton around the Delta resonance. The measurement was made at a central invariant mass and a squared four-momentum transfer of W=1231 MeV and Q^2 = 0.126 (GeV/c)^2, respectively. Read More

The first measurements of the induced proton polarization, P_n, for the 12C (e,e'\vec{p}) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (\omega,q) \approx (294 MeV, 756 MeV/c) and sampled a recoil momentum range of 0-250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. Read More

The coincidence cross-section and the interference structure function, R_LT, were measured for the 12C(e,e'p) 11B reaction at quasielastic kinematics and central momentum transfer of q=400 MeV/c. The measurement was at an opening angle of theta_pq=11 degrees, covering a range in missing energy of E_m = 0 to 65 MeV. The R_LT structure function is found to be consistent with zero for E_m > 50 MeV, confirming an earlier study which indicated that R_L vanishes in this region. Read More