A device has been developed with moveable liquid nitrogen and liquid helium volumes that is capable of reaching over 2 m into the coldest regions of a cryostat or dilution refrigerator and reliably extracting or installing a target of solid, polarized hydrogen deuteride (HD). This Transfer Cryostat incorporates a cylindrical neodymium rare-earth magnet that is configured as a Halbach dipole, which is maintained at 77 K and produces a 0.1 T field around the HD target. Multiple layers provide a hermetic 77 K-shield as the device is used to maintain a target at 2 K during a transfer between cryostats. Tests with frozen-spin HD show very little polarization loss for either H (−1±2%, relative) or D (0±3%, relative) over typical transfer periods. Multiple target transfers with this apparatus have shown an overall reliability of about 95% per transfer, which is a significant improvement over earlier versions of the device.

Compton backscattering gamma ray beams are characterized by a high degree of linear and circular polarization with low unpolarized backgrounds and have proven to provide very precise measurements of polarization observables. Latest results from LEGS and GRAAL experiments on proton and deuteron targets are presented. The Σ beam asymmetry for ω photoproduction has been measured by the GRAAL collaboration for both the ω→π0γ and the ω→π+π−π0 decay channels on the proton target; single and double polarization asymmetries have been provided also for the K photoproduction channel. E and G double polarization asymmetries for single pion photoproduction on the proton and deuteron have been measured at LEGS using a frozen spin HD target.

The extraction of resonance parameters from meson photo-reaction data is a challenging effort, that would greatly benefit from the availability of several polarization observables, measured for each reaction channel on both proton and neutron targets. In the aim of obtaining such complete experiments, polarized photon beams and targets have been developed at facilities, worldwide. We report on the latest results from the LEGS and GRAAL collaborations, providing single and double polarization measurements on pseudo-scalar meson photo-production from the nucleon.

We report new measurements of inclusive pi production from frozen-spin HD for polarized photon beams covering the Delta(1232) resonance. These provide data simultaneously on both H and D with nearly complete angular distributions of the spin-difference cross sections entering the Gerasimov-Drell-Hearn (GDH) sum rule. Recent results from Mainz and Bonn exceed the GDH prediction for the proton by 22 microb, suggesting as yet unmeasured high-energy components. Our pi0 data reveal a different angular dependence than assumed in Mainz analyses and integrate to a value that is 18 microb lower, suggesting a more rapid convergence. Our results for deuterium are somewhat lower than published data, considerably more precise, and generally lower than available calculations.

The exclusive electroproduction process (cid:2) ep → e (cid:4) nπ + was measured in the range of the photon virtuality Q 2 = 1 . 7–4 . 5 GeV 2 , and the invariant mass range for the nπ + system of W = 1 . 15–1 . 7 GeV using the CEBAF Large Acceptance Spectrometer. For the first time, these kinematics are probed in exclusive π + production from protons with nearly full coverage in the azimuthal and polar angles of the nπ + center-of-mass system. The nπ + channel has particular sensitivity to the isospin 12 excited nucleon states, and together with the pπ 0 final state will serve to determine the transition form factors of a large number of resonances. The largest discrepancy between these results and present modes was seen in the σ LT (cid:4) structure function. In this experiment, 31,295 cross section and 4,184 asymmetry data points were measured. Because of the large volume of data, only a reduced set of structure functions and Legendre polynomial moments can be presented that are obtained in model-independent fits to the differential cross sections.

The polarized and tagged Graal gamma‐ray beam is obtained by backward Compton scattering of laser light on the high‐energy electrons circulating in the ESRF storage ring. This technique, first developed for the Ladon beam on the storage ring Adone at LNF [1], provides gamma‐ray beams with linear or circular polarizations close to one and well known. The Graal beam covers the energy region between 600 and 1500 MeV thus allowing the study of baryon resonances up to an energy of 1916 MeV, in large part by precision measurements of beam polarization asymmetries in meson photoproduction on the nucleons.

P. E. Bosted,35,* R. Fersch,39 G. Adams,31 M. Amarian,29 S. Anefalos,17 M. Anghinolfi,18 G. Asryan,40 H. Avakian,17,35 H. Bagdasaryan,29,40 N. Baillie,39 J. P. Ball,2 N. A. Baltzell,34 S. Barrow,13 V. Batourine,35 M. Battaglieri,18 K. Beard,21 I. Bedlinskiy,20 M. Bektasoglu,29 M. Bellis,5,31 N. Benmouna,14 A. S. Biselli,11 B. E. Bonner,32 S. Bouchigny,19,35 S. Boiarinov,20,35 R. Bradford,5 D. Branford,10 W. K. Brooks,35 S. Bültmann,29 V. D. Burkert,35 C. Butuceanu,39 J. R. Calarco,26 S. L. Careccia,29 D. S. Carman,35 B. Carnahan,6 A. Cazes,34 S. Chen,13 P. L. Cole,16,35 P. Collins,2 P. Coltharp,13 D. Cords,35,† P. Corvisiero,18 D. Crabb,38 H. Crannell,6 V. Crede,13 J. P. Cummings,31 R. De Masi,7 R. De Vita,18 E. De Sanctis,17 P. V. Degtyarenko,35 H. Denizli,30 L. Dennis,13 A. Deur,35 C. Djalali,34 G. E. Dodge,29 J. Donnelly,15 D. Doughty,8,35 P. Dragovitsch,13 M. Dugger,2 K. V. Dharmawardane,29,‡ S. Dytman,30 O. P. Dzyubak,34 H. Egiyan,35,39,§ K. S. Egiyan,40,† L. Elouadrhiri,8,35 P. Eugenio,13 R. Fatemi,38 G. Fedotov,25 R. J. Feuerbach,5 T. A. Forest,29 A. Fradi,19 H. Funsten,39 M. Garçon,7 G. Gavalian,26,29 G. P. Gilfoyle,33 K. L. Giovanetti,21 F. X. Girod,7 J. T. Goetz,3 E. Golovatch,18,‖ R. W. Gothe,34 K. A. Griffioen,39 M. Guidal,19 M. Guillo,34 N. Guler,29 L. Guo,35 V. Gyurjyan,35 C. Hadjidakis,19 K. Hafidi,1 R. S. Hakobyan,6 J. Hardie,8,35 D. Heddle,8,35 F. W. Hersman,26 K. Hicks,28 I. Hleiqawi,28 M. Holtrop,26 M. Huertas,34 C. E. Hyde-Wright,29 Y. Ilieva,14 D. G. Ireland,15 B. S. Ishkhanov,25 E. L. Isupov,25 M. M. Ito,35 D. Jenkins,37 H. S. Jo,19 K. Joo,9 H. G. Juengst,29 N. Kalantarians,29 C. Keith,35 J. D. Kellie,15 M. Khandaker,27 K. Y. Kim,30 K. Kim,22 W. Kim,22 A. Klein,29,¶ F. J. Klein,6,12 M. Klusman,31 M. Kossov,20 L. H. Kramer,12,35 V. Kubarovsky,31,35 J. Kuhn,5,31 S. E. Kuhn,29 S. V. Kuleshov,20 J. Lachniet,5,29 J. M. Laget,7,35 J. Langheinrich,34 D. Lawrence,24 Ji Li ,31 A. C. S. Lima,14 K. Livingston,15 H. Lu,34 K. Lukashin,6 M. MacCormick,19 N. Markov,9 S. McAleer,13 B. McKinnon,15 J. W. C. McNabb,5 B. A. Mecking,35 M. D. Mestayer,35 C. A. Meyer,5 T. Mibe,28 K. Mikhailov,20 R. Minehart,38 M. Mirazita,17 R. Miskimen,24 V. Mokeev,25 L. Morand,7 S. A. Morrow,7,19 M. Moteabbed,12 J. Mueller,30 G. S. Mutchler,32 P. Nadel-Turonski,14 R. Nasseripour,12,34 S. Niccolai,14,19 G. Niculescu,21 I. Niculescu,14,21 B. B. Niczyporuk,35 M. R. Niroula,29 R. A. Niyazov,29,35 M. Nozar,35 G. V. O’Rielly,14 M. Osipenko,18,25 A. I. Ostrovidov,13 K. Park,22 E. Pasyuk,2 C. Paterson,15 S. A. Philips,14 J. Pierce,38 N. Pivnyuk,20 D. Pocanic,38 O. Pogorelko,20 E. Polli,17 S. Pozdniakov,20 B. M. Preedom,34 J. W. Price,4 Y. Prok,38,** D. Protopopescu,15,26 L. M. Qin,29 B. A. Raue,12,35 G. Riccardi,13 G. Ricco,18 M. Ripani,18 G. Rosner,15 P. Rossi,17 D. Rowntree,23 P. D. Rubin,33 F. Sabatié,7,29 C. Salgado,27 J. P. Santoro,35,37,†† V. Sapunenko,18,35 R. A. Schumacher,5 V. S. Serov,20 Y. G. Sharabian,35 J. Shaw,24 N. V. Shvedunov,25 A. V. Skabelin,23 E. S. Smith,35 L. C. Smith,38 D. I. Sober,6 A. Stavinsky,20 S. S. Stepanyan,22 S. Stepanyan,8,35,40 B. E. Stokes,13 P. Stoler,31 S. Strauch,34 R. Suleiman,23 M. Taiuti,18 S. Taylor,32 D. J. Tedeschi,34 U. Thoma,35,‡‡ A. Tkabladze,14 S. Tkachenko,29 L. Todor,5 M. Ungaro,9 M. F. Vineyard,33,36 A. V. Vlassov,20 L. B. Weinstein,29 D. P. Weygand,35 M. Williams,5 E. Wolin,35 M. H. Wood,34,§§ A. Yegneswaran,35 J. Yun,29 L. Zana,26 J. Zhang,29 B. Zhao,9 and Z. Zhao34 (CLAS Collaboration) 1Argonne National Laboratory, Argonne, Illinois 60439, USA 2Arizona State University, Tempe, Arizona 85287-1504, USA 3University of California at Los Angeles, Los Angeles, California 90095-1547, USA 4California State University, Dominguez Hills, Carson, California 90747, USA 5Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA 6Catholic University of America, Washington, D.C. 20064, USA 7CEA-Saclay, Service de Physique Nucléaire, F-91191 Gif-sur-Yvette, France 8Christopher Newport University, Newport News, Virginia 23606, USA 9University of Connecticut, Storrs, Connecticut 06269, USA 10Edinburgh University, Edinburgh EH9 3JZ, United Kingdom 11Fairfield University, Fairfield, Connecticut 06824, USA 12Florida International University, Miami, Florida 33199, USA 13Florida State University, Tallahassee, Florida 32306, USA 14George Washington University, Washington, D.C. 20052, USA 15University of Glasgow, Glasgow G12 8QQ, United Kingdom 16Idaho State University, Pocatello, Idaho 83209, USA 17INFN, Laboratori Nazionali di Frascati, I-00044 Frascati, Italy 18INFN, Sezione di Genova, I-16146 Genova, Italy 19Institut de Physique Nucleaire ORSAY, Orsay, France 20Institute of Theoretical and Experimental Physics, RU-117259 Moscow, Russia 21James Madison University, Harrisonburg, Virginia 22807, USA 22Kyungpook National University, Daegu 702-701, South Korea 23Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA 24University of Massachusetts, Amherst, Massachusetts 01003, USA 25Moscow State University, General Nuclear Physics Institute, RU-119899 Moscow, Russia

New high-precision measurements of p(y', r) and p(7, y) cross sections and beam aaymmetries have been combined with other polabation ratios in a simultaneous analysis of both reactions. The E2/M1 m k h g ratio for the N --+ A transition extracted from this analysis ia EMR = -3.0% f 0.3 (stat+sys) f 0.2 (model). The well-isolated N + A resonance serves as a sensitive test for models of nucleon structure [1-4]. To lowest order, N -+ A is a simple M1 quark spin-flip transition. Small L=2 components in the N and A wavefunctions allow this excitation to proceed via an electric quadrupole transition. The most sensitive observable to E2 strength is the beam asymmetry in p(q,.rro) [5]. In a recent Mainz measurement of p(q,.rr) an EMR of -2.5% was extracted using the 7ro channel alone [6]. As will be shown, this value is artificifially inflated by a factor of 2 due to multipole ambiguities. W e report an improved value for the EMR that is constrained by new measurements and two new observables. At any energy, a minimum of 8 independent observables are required to specify the photo-pion amplitude [7]. Such complete information has never been available and previous analyses have relied on at most four observables, usually measured separately with independent systematic errors. Although the r = 3/2 M1 and E2 components can extracted from a multipole fit, many observables are needed to avoid multipole ambiguities [8]. In the present work, p(y, TO), p(yy w+) and p(7,7) cross sections and beam asymmetries were all measured simultaneously to provide new constraints on the photo-pion multipoles. At LEGS, polarized tagged 7-ray beams between 209 and 333 MeV were produced by backscattering laser light from 2.6 GeV electrons at the National Synchrotron Light Source. Beams, with linear polarizations greater than 80% and known to fl%, were flipped between orthogonal states at random intervals between 150 and 450 seconds. One goal of this experiment was the first complete separation of Compton scattering and w"-production. The two reactions were distinguished by comparing their 7-ray and proton-recoil energies. High energy 7-rays were detected in a large NaI(T1) crystal, while recoil protons were tracked through wire chambers and stopped in an array of plastic scintillators. A schematic of this arrangement and a spectrum showing the separation of the two channels is given in [SI. All detector efficiencies were determined directly from the data itself, an important advantage. Charged pions were detected in 6 NaI detectors, including the large crystal used for the Compton and w" channels. The high resolution of the NaI detectors was essential in determining 7r+ efficiencies, which were simulated with GEANT [lo] using GCALOR to model hadronic interactions [ll]. Systematic effects were combined in quadrature with statistical errors (1%) for a net measurement error. In the vicinity of the A peak, the spin-averaged w", w+, and Compton cross sections determined in this experiment are all consistently higher than earlier measurements from Bonn [12-151 while for energies lower than -270 MeV substantial agreement is observed. Of the previous ?r+ cross section measurements, those from Tokyo [16] are in closest agreement to the present work. The present work is also in very good agreement with two recent Compton measurements from Mainz at 90" and 75" [17,18]. All LEGS cross sections are locked together with a common systematic scale uncertainty, due to possible flux and target thickness variations, of 2%. To obtain a consistent description of these results we have performed an energy-dependent analysis, expanding the .Ir-production amplitude into electric and magnetic partial waves, EL7f and Mlk , with relative wN angular momentum C, and intermediate-state spin j = Cf f and isospin r = !j or %. In order to reproduce our angular distributions in the region of the Ay we must vary the D wave contributions. To reduce ambiguities [8], we truncate our fit at F waves, while keeping the Born terms up to order C = 19. The (7, w ) multipoles were parameterized with a K-matrix-like unitarizau'

Citation for published version: Nasseripour, R, Raue, BA, Carman, DS, Ambrozewicz, P, Amaryan, MJ, Anciant, E, Anghinolfi, M, Asavapibhop, B, Asryan, G, Audit, G, Auger, T, Avakian, H, Bagdasaryan, H, Baillie, N, Ball, JP, Baltzell, NA, Barrow, S, Battaglieri, M, Beard, K, Bedlinskiy, I, Bektasoglu, M, Bellis, M, Benmouna, N, Berman, BL, Biselli, AS, Blaszczyk, L, Bonner, BE, Bouchigny, S, Boiarinov, S, Bradford, R, Branford, D, Briscoe, WJ, Brooks, WK, Burkert, VD, Butuceanu, C, Calarco, JR, Careccia, SL, Casey, L, Cetina, C, Chen, S, Cheng, L, Cole, PL, Collins, P, Coltharp, P, Cords, D, Corvisiero, P, Crabb, D, Crede, V, Thompson, R, Watts, DP & CLAS Collaboration 2008, 'Polarized structure function sigma(')(LT) for H-1((e)over-rightarrow,e(')K(+))Lambda in the nucleon resonance region', Physical Review C, vol. 77, no. 6, 065208, pp. -. https://doi.org/10.1103/PhysRevC.77.065208

Differential cross sections for the reaction gamma p -> K-*0 Sigma(+) are presented in the photon energy range of 1.7 to 3.0 GeV. The K-*0 was detected by its decay products, K+pi(-), in the Continuous Electron Beam Accelerator Facility's large acceptance spectrometer (CLAS) detector at the Thomas Jefferson National Accelerator Facility. These data are the first K-*0 photoproduction cross sections ever published over a broad range of angles. Comparison with a theoretical model based on the vector and tensor K-*-quark couplings shows good agreement with the data, except at forward angles, suggesting that the role of scalar kappa meson exchange should be investigated.

Differential cross sections for the reaction γp→K*0Σ+ are presented in the photon energy range of 1.7 to 3.0 GeV. The K*0 was detected by its decay products, K+π−, in the Continuous Electron Beam Accelerator Facility's large acceptance spectrometer (CLAS) detector at the Thomas Jefferson National Accelerator Facility. These data are the first K*0 photoproduction cross sections ever published over a broad range of angles. Comparison with a theoretical model based on the vector and tensor K∗-quark couplings shows good agreement with the data, except at forward angles, suggesting that the role of scalar κ meson exchange should be investigated.

New cross sections for the reaction ep → e'ηp are reported for total center-of-mass energy W = 1.5-2.3 GeV and invariant squared momentum transfer Q 2 = 0.13-3.3 GeV 2 . This large kinematic range allows the extraction of new information about response functions, photocouplings, and η)N coupling strengths of baryon resonances. A sharp structure is seen at W ∼ 1.7 GeV. The shape of the differential cross section is indicative of the presence of a P-wave resonance that persists to high Q 2 . Improved values are derived for the photocoupling amplitude for the S 11 (1535) resonance. The new data greatly expand the Q 2 range covered, and an interpretation of all data with a consistent parametrization is provided.

R. Bradford,1,∗ R. A. Schumacher,1 J. W. C. McNabb,1 L. Todor,1 G. Adams,29 P. Ambrozewicz,10 E. Anciant,5 M. Anghinolfi,16 B. Asavapibhop,22 G. Asryan,38 G. Audit,5 H. Avakian,15,33 H. Bagdasaryan,27 N. Baillie,37 J. P. Ball,2 N. A. Baltzell,32 S. Barrow,11 V. Batourine,20 M. Battaglieri,16 K. Beard,19 I. Bedlinskiy,18 M. Bektasoglu,27,† M. Bellis,1 N. Benmouna,12 B. L. Berman,12 N. Bianchi,15 A. S. Biselli,1,29 B. E. Bonner,30 S. Bouchigny,17,33 S. Boiarinov,18,33 D. Branford,9 W. J. Briscoe,12 W. K. Brooks,33 S. Bültmann,27 V. D. Burkert,33 C. Butuceanu,37 J. R. Calarco,24 S. L. Careccia,27 D. S. Carman,26 B. Carnahan,4 S. Chen,11 P. L. Cole,14,33 A. Coleman,37 P. Coltharp,11 P. Corvisiero,16 D. Crabb,36 H. Crannell,4 J. P. Cummings,29 R. DeVita,16 E. De Sanctis,15 P. V. Degtyarenko,33 H. Denizli,28 L. Dennis,11 A. Deur,33 K. V. Dharmawardane,27 K. S. Dhuga,12 C. Djalali,32 G. E. Dodge,27 J. Donnelly,13 D. Doughty,6,33 P. Dragovitsch,11 M. Dugger,2 S. Dytman,28 O. P. Dzyubak,32 H. Egiyan,33,37 K. S. Egiyan,38 L. Elouadrhiri,6,33 A. Empl,29 P. Eugenio,11 R. Fatemi,36 G. Fedotov,23 G. Feldman,12 R. J. Feuerbach,1 T. A. Forest,27 H. Funsten,37 M. Garçon,5 G. Gavalian,27,38 G. P. Gilfoyle,31 K. L. Giovanetti,19 F. X. Girod,5 J. T. Goetz,3 E. Golovatch,16 A. Gonenc,10 R. W. Gothe,32 K. A. Griffioen,37 M. Guidal,17 M. Guillo,32 N. Guler,27 L. Guo,33 V. Gyurjyan,33 C. Hadjidakis,17 R. S. Hakobyan,4 J. Hardie,6,33 D. Heddle,6,33 F. W. Hersman,24 K. Hicks,26 I. Hleiqawi,26 M. Holtrop,24 J. Hu,29 M. Huertas,32 C. E. Hyde-Wright,27 Y. Ilieva,12 D. G. Ireland,13 B. S. Ishkhanov,23 M. M. Ito,33 D. Jenkins,35 H. S. Jo,17 K. Joo,7,36 H. G. Juengst,27 J. D. Kellie,13 M. Khandaker,25 K. Y. Kim,28 K. Kim,20 W. Kim,20 A. Klein,27 F. J. Klein,4,33 A. V. Klimenko,27 M. Klusman,29 M. Kossov,18 L. H. Kramer,10,33 V. Kubarovsky,29 J. Kuhn,1 S. E. Kuhn,27 S. V. Kuleshov,18 J. Lachniet,1 J. M. Laget,5,33 J. Langheinrich,32 D. Lawrence,22 A. C. S. Lima,12 K. Livingston,13 K. Lukashin,33 J. J. Manak,33 C. Marchand,5 S. McAleer,11 B. McKinnon,13 B. A. Mecking,33 M. D. Mestayer,33 C. A. Meyer,1 T. Mibe,26 K. Mikhailov,18 R. Minehart,36 M. Mirazita,15 R. Miskimen,22 V. Mokeev,23 S. A. Morrow,5,17 V. Muccifora,15 J. Mueller,28 G. S. Mutchler,30 P. Nadel-Turonski,12 J. Napolitano,29 R. Nasseripour,32 S. Niccolai,12,17 G. Niculescu,19,26 I. Niculescu,12,19 B. B. Niczyporuk,33 R. A. Niyazov,27,33 M. Nozar,33 G. V. O’Rielly,12 M. Osipenko,16,23 A. I. Ostrovidov,11 K. Park,20 E. Pasyuk,2 C. Paterson,13 S. A. Philips,12 J. Pierce,36 N. Pivnyuk,18 D. Pocanic,36 O. Pogorelko,18 E. Polli,15 I. Popa,12 S. Pozdniakov,18 B. M. Preedom,32 J. W. Price,3 Y. Prok,36 D. Protopopescu,13 L. M. Qin,27 B. P. Quinn,1 B. A. Raue,10,33 G. Riccardi,11 G. Ricco,16 M. Ripani,16 B. G. Ritchie,2 F. Ronchetti,15 G. Rosner,13 P. Rossi,15 D. Rowntree,21 P. D. Rubin,31 F. Sabatié,5,27 C. Salgado,25 J. P. Santoro,33,35 V. Sapunenko,16,33 V. S. Serov,18 A. Shafi,12 Y. G. Sharabian,33,38 J. Shaw,22 S. Simionatto,12 A. V. Skabelin,21 E. S. Smith,33 L. C. Smith,36 D. I. Sober,4 M. Spraker,8 A. Stavinsky,18 S. S. Stepanyan,20 S. Stepanyan,33,38 B. E. Stokes,11 P. Stoler,29 I. I. Strakovsky,12 S. Strauch,12 R. Suleiman,21 M. Taiuti,16 S. Taylor,30 D. J. Tedeschi,32 U. Thoma,33 R. Thompson,28 A. Tkabladze,26 S. Tkachenko,27 C. Tur,32 M. Ungaro,7,29 M. F. Vineyard,31,34 A. V. Vlassov,18 K. Wang,36 L. B. Weinstein,27 H. Weller,8 D. P. Weygand,33 M. Williams,1 E. Wolin,33 M. H. Wood,32 A. Yegneswaran,33 J. Yun,27 L. Zana,24 J. Zhang,27 and B. Zhao7 (CLAS Collaboration) 1Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA 2Arizona State University, Tempe, Arizona 85287-1504, USA 3University of California at Los Angeles, Los Angeles, California 90095-1547, USA 4Catholic University of America, Washington, DC 20064, USA 5CEA-Saclay, Service de Physique Nucléaire, F-91191 Gif-sur-Yvette, Cedex, France 6Christopher Newport University, Newport News, Virginia 23606, USA 7University of Connecticut, Storrs, Connecticut 06269, USA 8Duke University, Durham, North Carolina 27708-0305, USA 9Edinburgh University, Edinburgh EH9 3JZ, United Kingdom 10Florida International University, Miami, Florida 33199, USA 11Florida State University, Tallahassee, Florida 32306, USA 12The George Washington University, Washington, DC 20052, USA 13University of Glasgow, Glasgow G12 8QQ, United Kingdom 14Idaho State University, Pocatello, Idaho 83209, USA 15INFN, Laboratori Nazionali di Frascati, Frascati, Italy 16INFN, Sezione di Genova, I-16146 Genova, Italy 17Institut de Physique Nucleaire ORSAY, Orsay, France 18Institute of Theoretical and Experimental Physics, Moscow, RU-117259, Russia 19James Madison University, Harrisonburg, Virginia 22807, USA 20Kyungpook National University, Daegu 702-701, South Korea 21Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA 22University of Massachusetts, Amherst, Massachusetts 01003, USA 23Moscow State University, General Nuclear Physics Institute, RU-119899 Moscow, Russia 24University of New Hampshire, Durham, New Hampshire 03824-3568, USA 25Norfolk State University, Norfolk, Virginia 23504, USA

D. Protopopescu,24, ∗ F. W. Hersman,24 M. Holtrop,24 G. Adams,31 P. Ambrozewicz,10 E. Anciant,2 M. Anghinolfi,17 B. Asavapibhop,23 G. Asryan,40 G. Audit,2 T. Auger,2 H. Avakian,35, 16 H. Bagdasaryan,27 J.P. Ball,1 S. Barrow,11 M. Battaglieri,17 K. Beard,20 M. Bektasoglu,27, † M. Bellis,31 N. Benmouna,14 B.L. Berman,14 W. Bertozzi,22 N. Bianchi,16 A.S. Biselli,4 S. Boiarinov,19, ‡ B.E. Bonner,32 S. Bouchigny,18, 35 R. Bradford,4 D. Branford,9 W.J. Briscoe,14 W.K. Brooks,35 V.D. Burkert,35 C. Butuceanu,39 J.R. Calarco,24 D.S. Carman,26 B. Carnahan,5 C. Cetina,14 S. Chen,11 P.L. Cole,35, § A. Coleman,39, ¶ D. Cords,35, ∗∗ P. Corvisiero,17 D. Crabb,38 H. Crannell,5 J.P. Cummings,31 D. Debruyne,12 E. De Sanctis,16 R. DeVita,17 P.V. Degtyarenko,35 L. Dennis,11 K.V. Dharmawardane,27 K.S. Dhuga,14 C. Djalali,34 G.E. Dodge,27 D. Doughty,6, 35 P. Dragovitsch,11 M. Dugger,1 S. Dytman,29 O.P. Dzyubak,34 H. Egiyan,35, 39 K.S. Egiyan,40 L. Elouadrhiri,6, 35 A. Empl,31 P. Eugenio,11 R. Fatemi,38 R.J. Feuerbach,35 T.A. Forest,27 H. Funsten,39 G. Gavalian,24, 40 S. Gilad,22 G.P. Gilfoyle,33 K.L. Giovanetti,20 P. Girard,34 C.I.O. Gordon,15 R.W. Gothe,34 K.A. Griffioen,39 M. Guidal,18 M. Guillo,34 N. Guler,27 L. Guo,35 V. Gyurjyan,35 C. Hadjidakis,18 R.S. Hakobyan,5 J. Hardie,6, 35 D. Heddle,6, 35 K. Hicks,26 I. Hleiqawi,26 J. Hu,31 C.E. Hyde-Wright,27 W. Ingram,15 D. Ireland,15 M.M. Ito,35 D. Jenkins,37 K. Joo,7, 38 H.G. Juengst,14 J.H. Kelley,8 J.D. Kellie,15 M. Khandaker,25 K.Y. Kim,29 K. Kim,21 W. Kim,21 A. Klein,27 F.J. Klein,35, § A.V. Klimenko,27 M. Klusman,31 M. Kossov,19 L.H. Kramer,10, 35 S.E. Kuhn,27 J. Kuhn,4 J. Lachniet,4 J.M. Laget,2 J. Langheinrich,34 D. Lawrence,23 T. Lee,24 Ji Li,31 K. Livingston,15 K. Lukashin,35, § J.J. Manak,35 C. Marchand,2 S. McAleer,11 S. T. McLauchlan,15 J.W.C. McNabb,28 B.A. Mecking,35 J.J. Melone,15 M.D. Mestayer,35 C.A. Meyer,4 K. Mikhailov,19 R. Minehart,38 M. Mirazita,16 R. Miskimen,23 L. Morand,2 S.A. Morrow,2, 18 V. Muccifora,16 J. Mueller,29 G.S. Mutchler,32 J. Napolitano,31 R. Nasseripour,10 S.O. Nelson,8 S. Niccolai,18 G. Niculescu,20, 26 I. Niculescu,20, 14 B.B. Niczyporuk,35 R.A. Niyazov,35, 27 M. Nozar,35 G.V. O’Rielly,14 M. Osipenko,17 A. Ostrovidov,11 K. Park,21 E. Pasyuk,1 G. Peterson,23 S.A. Philips,14 N. Pivnyuk,19 D. Pocanic,38 O. Pogorelko,19 E. Polli,16 S. Pozdniakov,19 B.M. Preedom,34 J.W. Price,3 Y. Prok,38 L.M. Qin,27 B.A. Raue,10, 35 G. Riccardi,11 G. Ricco,17 M. Ripani,17 B.G. Ritchie,1 F. Ronchetti,16, 30 G. Rosner,15 P. Rossi,16 D. Rowntree,22 P.D. Rubin,33 J. Ryckebusch,12 F. Sabatié,2, 27 K. Sabourov,8 C. Salgado,25 J.P. Santoro,37, 35 V. Sapunenko,17, ‡ R.A. Schumacher,4 V.S. Serov,19 Y.G. Sharabian,40, ‡ J. Shaw,23 S. Simionatto,14 A.V. Skabelin,22 E.S. Smith,35 L.C. Smith,38 D.I. Sober,5 M. Spraker,8 A. Stavinsky,19 S. Stepanyan,40, †† B. E. Stokes,11 P. Stoler,31 S. Strauch,14 M. Taiuti,17 S. Taylor,32 D.J. Tedeschi,34 U. Thoma,13, 35 R. Thompson,29 A. Tkabladze,26 L. Todor,33 C. Tur,34 M. Ungaro,31 M.F. Vineyard,36, 33 A.V. Vlassov,19 K. Wang,38 L.B. Weinstein,27 H. Weller,8 D.P. Weygand,35 C.S. Whisnant,34, ‡‡ M. Williams,4 E. Wolin,35 M.H. Wood,34 A. Yegneswaran,35 J. Yun,27 L. Zana,24 and B. Zhang22

The polarized longitudinal-transverse structure function sigma(LT') has been measured in the Delta(1232) resonance region at Q(2)=0.40 and 0.65 GeV2. Data for the p((e) over right arrow ,e'p)pi(0) reaction were taken at Jefferson Lab with the CEBAF large acceptance spectrometer (CLAS) using longitudinally polarized electrons at an energy of 1.515 GeV. For the first time a complete angular distribution was measured, permitting the separation of different nonresonant amplitudes using a partial wave analysis. Comparison with previous beam asymmetry measurements at MAMI indicate a deviation from the predicted Q(2) dependence of sigma(LT ') using recent phenomenological models.