Experimental techniques and performance of $\Lambda$-hypernuclear spectroscopy with the $(e,e^{\prime}K^{+})$ reaction (1709.05682)
T. Gogami, C. Chen, Y. Fujii, O. Hashimoto, M. Kaneta, D. Kawama, T. Maruta, A. Matsumura, S. Nagao, S. N. Nakamura, Y. Okayasu, J. Reinhold, L. Tang, K. Tsukada, S. A. Wood, L. Yuan
Jan. 29, 2018 nucl-ex, physics.ins-det
The missing-mass spectroscopy of $\Lambda$ hypernuclei via the $(e,e^{\prime}K^{+})$ reaction has been developed through experiments at JLab Halls A and C in the last two decades. For the latest experiment, E05-115 in Hall C, we developed a new spectrometer system consisting of the HKS and HES; resulting in the best energy resolution ($E_{\Lambda} \simeq0.5$-MeV FWHM) and $B_{\Lambda}$ accuracy ($B_{\Lambda}\leq0.2$ MeV) in $\Lambda$-hypernuclear reaction spectroscopy. This paper describes the characteristics of the $(e,e^{\prime}K^{+})$ reaction compared to other reactions and experimental methods. In addition, the experimental apparatus, some of the important analyses such as the semi-automated calibration of absolute energy scale, and the performance achieved in E05-115 are presented.
Momentum sharing in imbalanced Fermi systems (1412.0138)
O. Hen, M. Sargsian, L.B. Weinstein, E. Piasetzky, H. Hakobyan, D. W. Higinbotham, M. Braverman, W.K. Brooks, S. Gilad, K. P. Adhikari, J. Arrington, G. Asryan, H. Avakian, J. Ball, N. A. Baltzell, M. Battaglieri, A. Beck, S. May-Tal Beck, I. Bedlinskiy, W. Bertozzi, A. Biselli, V. D. Burkert, T. Cao, D. S. Carman, A. Celentano, S. Chandavar, L. Colaneri, P. L. Cole, V. Crede, A. DAngelo, R. De Vita, A. Deur, C. Djalali, D. Doughty, M. Dugger, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, G. Fedotov, S. Fegan, T. Forest, B. Garillon, M. Garcon, N. Gevorgyan, Y. Ghandilyan, G. P. Gilfoyle, F. X. Girod, J. T. Goetz, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, C. Hanretty, M. Hattawy, K. Hicks, M. Holtrop, C. E. Hyde, Y. Ilieva, D. G. Ireland, B.I. Ishkanov, E. L. Isupov, H. Jiang, H. S. Jo, K. Joo, D. Keller, M. Khandaker, A. Kim, W. Kim, F. J. Klein, S. Koirala, I. Korover, S. E. Kuhn, V. Kubarovsky, P. Lenisa, W. I. Levine, K. Livingston, M. Lowry, H. Y. Lu, I. J. D. MacGregor, N. Markov, M. Mayer, B. McKinnon, T. Mineeva, V. Mokeev, A. Movsisyan, C. Munoz Camacho, B. Mustapha, P. Nadel-Turonski, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, L. L. Pappalardo, R. Paremuzyan, K. Park, E. Pasyuk, W. Phelps, S. Pisano, O. Pogorelko, J. W. Price, S. Procureur, Y. Prok, D. Protopopescu, A. J. R. Puckett, D. Rimal, M. Ripani, B. G. Ritchie, A. Rizzo, G. Rosner, P. Rossi, P. Roy, F. Sabatie, D. Schott, R. A. Schumacher, Y. G. Sharabian, G. D. Smith, R. Shneor, D. Sokhan, S. S. Stepanyan, S. Stepanyan, P. Stoler, S. Strauch, V. Sytnik, M. Taiuti, S. Tkachenko, M. Ungaro, A. V. Vlassov, E. Voutier, D. Watts, N. K. Walford, X. Wei, M. H. Wood, S. A. Wood, N. Zachariou, L. Zana, Z. W. Zhao, X. Zheng, I. Zonta
Nov. 29, 2014 nucl-ex, nucl-th, cond-mat.quant-gas
The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few body systems to neutron stars and may also be observable experimentally in two-spin state, ultra-cold atomic gas systems.
In Medium Nucleon Structure Functions, SRC, and the EMC effect (1409.1717)
O. Hen, L.B. Weinstein, S. Gilad, S. A. Wood
Sept. 5, 2014 nucl-ex, nucl-th
A proposal approved by the Jefferson Lab PAC to study semi-inclusive deep inelastic scattering (DIS) off the deuteron, tagged with high momentum recoiling protons or neutrons emitted at large angle relative to the momentum transfer. This experiment aims at studying the virtuality dependence of the bound nucleon structure function as a possible cause to the EMC effect and the EMC-SRC correlations. The experiment was approved in 2011 for a total run time of 40 days.
The experiments with the High Resolution Kaon Spectrometer at JLab Hall C and the new spectroscopy of ${}^{12}_{\Lambda}\text{B}$ hypernuclei (1406.2353)
L. Tang, C. Chen, T. Gogami, D. Kawama, Y. Han, L. Yuan, A. Matsumura, Y. Okayasu, T. Seva, V. M. Rodriguez, P. Baturin, A. Acha, P. Achenbach, A. Ahmidouch, I. Albayrak, D. Androic, A. Asaturyan, R. Asaturyan, O. Ates, R. Badui, O. K. Baker, F. Benmokhtar, W. Boeglin, J. Bono, P. Bosted, E. Brash, P. Carter, R. Carlini, A. Chiba, M. E. Christy, L. Cole, M. M. Dalton, S. Danagoulian, A. Daniel, R. De Leo, V. Dharmawardane, D. Doi, K. Egiyan, M. Elaasar, R. Ent, H. Fenker, Y. Fujii, M. Furic, M. Gabrielyan, L. Gan, F. Garibaldi, D. Gaskell, A. Gasparian, E. F. Gibson, P. Gueye, O. Hashimoto, D. Honda, T. Horn, B. Hu, Ed V. Hungerford, C. Jayalath, M. Jones, K. Johnston, N. Kalantarians, H. Kanda, M. Kaneta, F. Kato, S. Kato, M. Kawai, C. Keppel, H. Khanal, M. Kohl, L. Kramer, K. J. Lan, Y. Li, A. Liyanage, W. Luo, D. Mack, K. Maeda, S. Malace, A. Margaryan, G. Marikyan, P. Markowitz, T. Maruta, N. Maruyama, V. Maxwell, D.J. Millener, T. Miyoshi, A. Mkrtchyan, H. Mkrtchyan, T. Motoba, S. Nagao, S. N. Nakamura, A. Narayan, C. Neville, G. Niculescu, M. I. Niculescu, A. Nunez, Nuruzzaman, H. Nomura, K. Nonaka, A. Ohtani, M. Oyamada, N. Perez, T. Petkovic, J. Pochodzalla, X. Qiu, S. Randeniya, B. Raue, J. Reinhold, R. Rivera, J. Roche, C. Samanta, Y. Sato, B. Sawatzky, E. K. Segbefia, D. Schott, A. Shichijo, N. Simicevic, G. Smith, Y. Song, M. Sumihama, V. Tadevosyan, T. Takahashi, N. Taniya, K. Tsukada, V. Tvaskis, M. Veilleux, W. Vulcan, S. Wells, F. R. Wesselmann, S. A. Wood, T. Yamamoto, C. Yan, Z. Ye, K. Yokota, S. Zhamkochyan, L. Zhu (HKS - JLab E05-115, E01-001 - Collaborations)
Aug. 13, 2014 nucl-ex
Since the pioneering experiment, E89-009 studying hypernuclear spectroscopy using the $(e,e^{\prime}K^+)$ reaction was completed, two additional experiments, E01-011 and E05-115, were performed at Jefferson Lab. These later experiments used a modified experimental design, the "tilt method", to dramatically suppress the large electromagnetic background, and allowed for a substantial increase in luminosity. Additionally, a new kaon spectrometer, HKS (E01-011), a new electron spectrometer, HES, and a new splitting magnet were added to produce precision, high-resolution hypernuclear spectroscopy. These two experiments, E01-011 and E05-115, resulted in two new data sets, producing sub-MeV energy resolution in the spectra of ${}^{7}_{\Lambda}\text{He}$, ${}^{12}_{\Lambda}\text{B}$ and ${}^{28}_{\Lambda}\text{Al}$ and ${}^{7}_{\Lambda}\text{He}$, ${}^{10}_{\Lambda}\text{Be}$, ${}^{12}_{\Lambda}\text{B}$ and ${}^{52}_{\Lambda}\text{V}$. All three experiments obtained a ${}^{12}_{\Lambda}\text{B}$, spectrum, which is the most characteristic $p$-shell hypernucleus and is commonly used for calibration. Independent analyses of these different experiments demonstrate excellent consistency and provide the clearest level structure to date of this hypernucleus as produced by the $(e,e^{\prime}K^+)$ reaction. This paper presents details of these experiments, and the extraction and analysis of the observed ${}^{12}_{\Lambda}\text{B}$ spectrum.
First Determination of the Weak Charge of the Proton (1307.5275)
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
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.
Bucking Coil Implementation on PMT for Active Cancelling of Magnetic Field (1307.0896)
T. Gogami, A. Asaturyan, J.Bono, P.Baturin, C. Chen, A. Chiba, N. Chiga, Y. Fujii, O. Hashimoto, D. Kawama, T. Maruta, V.Maxwell, A. Mkrtchyan, S. Nagao, S. N. Nakamura, J. Reinhold, A. Shichijo, L. Tang, N. Taniya, S. A. Wood, Z. Ye
July 3, 2013 physics.ins-det
Aerogel and water Cerenkov detectors were employed to tag kaons for a lambda hypernuclear spectroscopic experiment which used the (e,e'K+) reaction in experimental Hall C at Jefferson Lab (JLab E05-115). Fringe fields from the kaon spectrometer magnet yielded ~5 Gauss at the photomultiplier tubes (PMT) for these detectors which could not be easily shielded. As this field results in a lowered kaon detection efficiency, we implemented a bucking coil on each photomultiplier tubes to actively cancel this magnetic field, thus maximizing kaon detection efficiency.
Direct Measurements of the Lifetime of Heavy Hypernuclei (1212.1133)
X. Qiu, L. Tang, A. Margaryan, P. Achenbach, A. Ahmidouch, I. Albayrak, D. Androic, A. Asaturyan, R. Asaturyan, O. Ates, R. Badui, P. Baturin, W. Boeglin, J. Bono, E. Brash, P. Carter, C. Chen, X. Chen, A. Chiba, E. Christy, M. M. Dalton, S. Danagoulian, R. De Leo, D. Doi, M. Elaasar, R. Ent, H. Fenker, Y. Fujii, M. Furic, M. Gabrielyan, L. Gan, F. Garibaldi, D. Gaskell, A. Gasparian, T. Gogami, O. Hashimoto, T. Horn, B. Hu, E. V. Hungerford, M. Jones, H. Kanda, M. Kaneta, M. Kawai, D. Kawama, H. Khanal, M. Kohl, A. Liyanage, W. Luo, K. Maeda, P. Markowitz, T. Maruta, A. Matsumura, V. Maxwell, A. Mkrtchyan, H. Mkrtchyan, S. Nagao, S. N. Nakamura, A. Narayan, C. Neville, G. Niculescu, M. I. Niculescu, A. Nunez, Nuruzzaman, Y. Okayasu, T. Petkovic, J. Pochodzalla, J. Reinhold, V. M. Rodriguez, C. Samanta, B. Sawatzky, T. Seva, A. Shichijo, V. Tadevosyan, N. Taniya, K. Tsukada, M. Veilleux, W. Vulcan, F. R. Wesselmann, S. A. Wood, L. Ya, T. Yamamoto, Z. Ye, K. Yokota, L. Yuan, S. Zhamkochyan, L. Zhu
The lifetime of a Lambda particle embedded in a nucleus (hypernucleus) decreases from that of free Lambda decay due to the opening of the Lambda N to NN weak decay channel. However, it is generally believed that the lifetime of a hypernucleus attains a constant value (saturation) for medium to heavy hypernuclear masses, yet this hypothesis has been difficult to verify. The present paper reports a direct measurement of the lifetime of medium-heavy hypernuclei produced with a photon-beam from Fe, Cu, Ag, and Bi targets. The recoiling hypernuclei were detected by a fission fragment detector using low-pressure multi-wire proportional chambers. The experiment agrees remarkably well with the only previously-measured single-species heavy-hypernucleus lifetime, that of Fe56_Lambda at KEK, and has significantly higher precision. The experiment disagrees with the measured lifetime of an unknown combination of heavy hypernuclei with 180<A<225 and, with a small statistical and systematic uncertainty, strongly favors the expected saturation of the lifetime decrease.
Measurement of R = sigma_L / sigma_T and the Separated Longitudinal and Transverse Structure Functions in the Nucleon Resonance Region (nucl-ex/0410027)
The Jefferson Lab Hall C E94-110 Collaboration: Y. Liang, V. Tvaskis, M.E. Christy, A. Ahmidouch, C. S. Armstrong, J. Arrington, R. Asaturyan, S. Avery, O. K. Baker, D. H. Beck, H. P. Blok, C. W. Bochna, W. Boeglin, P. Bosted, M. Bouwhuis, H. Breuer, D. S. Brown, A. Bruell, R. D. Carlini, J. Cha, N. S. Chant, A. Cochran, L. Cole, S. Danagoulian, D. B. Day, J. Dunne, D. Dutta, R. Ent, H. C. Fenker, B. Fox, L. Gan, H. Gao, K. Garrow, D. Gaskell, A. Gasparian, D. F. Geesaman, R. Gilman, P. L. J. Gu`eye, M. Harvey, R. J. Holt, X. Jiang, M. Jones, C. E. Keppel, E. Kinney, W. Lorenzon, A. Lung, D. J. Mack, P. Markowitz, J. W. Martin, K. McIlhany, D. McKee, D. Meekins, M. A. Miller, R. G. Milner, J. H. Mitchell, H. Mkrtchyan, B. A. Mueller, A. Nathan, G. Niculescu, I. Niculescu, T. G. O'Neill, V. Papavassiliou, S.F. Pate, R. B. Piercey, D. Potterveld, R. D. Ransome, J. Reinhold, E. Rollinde, O. Rondon, P. Roos, A. J. Sarty, R. Sawafta, E. C. Schulte, E. Segbefia, C. Smith, S. Stepanyan, S. Strauch, V. Tadevosyan, L. Tang, R. Tieulent, A. Uzzle, W. F. Vulcan, S. A. Wood, F. Xiong, L. Yuan, M. Zeier, B. Zihlmann, V. Ziskin
Jan. 8, 2013 nucl-ex
We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q^2 < 5.5 GeV^2. The data have been used to accurately perform 167 Rosenbluth-type longitudinal / transverse separations. The precision R = sigma_L / sigma_T data are presented here, along with the first separate values of the inelastic structure functions F_1 and F_L in this regime. The resonance longitudinal component is found to be significant, both in magnitude and in the existence of defined mass peaks. Additionally, quark-hadron duality is here observed above Q^2 = 1 GeV^2 in the separated structure functions independently.
First Measurement of the Neutral Current Excitation of the Delta Resonance on a Proton Target (1212.1637)
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
Dec. 7, 2012 nucl-ex
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.
Observation of the Helium 7 Lambda hypernucleus by the (e,e'K+) reaction (1207.0571)
S. N. Nakamura, A. Matsumura, Y. Okayasu, T. Seva, V. M. Rodriguez, P. Baturin, L. Yuan, A. Acha, A. Ahmidouch, D. Androic, A. Asaturyan, R. Asaturyan, O. K. Baker, F. Benmokhtar, P. Bosted, R. Carlini, C. Chen, M. Christy, L. Cole, S. Danagoulian, A. Daniel, V. Dharmawardane, K. Egiyan, M. Elaasar, R. Ent, H. Fenker, Y. Fujii, M. Furic, L. Gan, D. Gaskell, A. Gasparian, E. F. Gibson, T. Gogami, P. Gueye, Y. Han, O. Hashimoto, E. Hiyama, D. Honda, T. Horn, B. Hu, Ed V. Hungerford, C. Jayalath, M. Jones, K. Johnston, N. Kalantarians, H. Kanda, M. Kaneta, F. Kato, S. Kato, D. Kawama, C. Keppel, K. J. Lan, W. Luo, D. Mack, K. Maeda, S. Malace, A. Margaryan, G. Marikyan, P. Markowitz, T. Maruta, N. Maruyama, T. Miyoshi, A. Mkrtchyan, H. Mkrtchyan, S. Nagao, T. Navasardyan, G. Niculescu, M.-I. Niculescu, H. Nomura, K. Nonaka, A. Ohtani, M. Oyamada, N. Perez, T. Petkovic, S. Randeniya, J. Reinhold, J. Roche, Y. Sato, E. K. Segbefia, N. Simicevic, G. Smith, Y. Song, M. Sumihama, V. Tadevosyan, T. Takahashi, L. Tang, K. Tsukada, V. Tvaskis, W. Vulcan, S. Wells, S. A. Wood, C. Yan, S. Zhamkochyan
Nov. 19, 2012 nucl-ex
An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich hypernucleus, He 7 Lambda, was observed for the first time with the (e,e'K+) reaction with an energy resolution of ~0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The he 7 Lambda binding energy supplies the last missing information of the A=7, T=1 hypernuclear iso-triplet, providing a new input for the charge symmetry breaking (CSB) effect of \Lambda N potential.
The lead-glass electromagnetic calorimeters for the magnetic spectrometers in Hall C at Jefferson Lab (1204.6413)
H. Mkrtchyan, R. Carlini, V. Tadevosyan, J. Arrington, A. Asaturyan, M. E. Christy, D. Dutta, R. Ent, H. C. Fenker, D. Gaskell, T. Horn, M. K. Jones, C. E. Keppel, D. J. Mack, S. P. Malace, A. Mkrtchyan, M. I. Niculescu, J. Seely, V. Tvaskis, S. A. Wood, S. Zhamkochyan
April 28, 2012 nucl-ex, physics.ins-det
The electromagnetic calorimeters of the various magnetic spectrometers in Hall C at Jefferson Lab are presented. For the existing HMS and SOS spectrometers design considerations, relevant construction information, and comparisons of simulated and experimental results are included. The energy resolution of the HMS and SOS calorimeters is better than $\sigma/E \sim 6%/\sqrt E $, and pion/electron ($\pi/e$) separation of about 100:1 has been achieved in energy range 1 -- 5 GeV. Good agreement has been observed between the experimental and simulated energy resolutions, but simulations systematically exceed experimentally determined $\pi^-$ suppression factors by close to a factor of two. For the SHMS spectrometer presently under construction details on the design and accompanying GEANT4 simulation efforts are given. The anticipated performance of the new calorimeter is predicted over the full momentum range of the SHMS. Good electron/hadron separation is anticipated by combining the energy deposited in an initial (preshower) calorimeter layer with the total energy deposited in the calorimeter.
The Qweak Experiment: A Search for New Physics at the TeV Scale via a Measurement of the Proton's Weak Charge (1202.1255)
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
Feb. 7, 2012 nucl-ex, physics.ins-det
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.
Measurement of the parity-violating asymmetry in inclusive electroproduction of $\pi^-$ near the $\Delta^0$ resonance (1112.1720)
G0 Collaboration: D. Androić, 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, 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
Feb. 2, 2012 nucl-ex
The parity-violating (PV) asymmetry of inclusive $\pi^-$ production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasi-free photoproduction off the neutron via the $\Delta^0$ resonance. In the context of heavy-baryon chiral perturbation theory (HB$\chi$PT), this asymmetry is related to a low energy constant $d_\Delta^-$ that characterizes the parity-violating $\gamma$N$\Delta$ coupling. Zhu et al. calculated $d_\Delta^-$ in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from $A_\gamma^-=-5.2$ to $+5.2$ ppm. The measurement performed in this work leads to $A_\gamma^-=-0.36\pm 1.06\pm 0.37\pm 0.03$ ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to $V_{ud}/V_{us}$. The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the $N-\Delta$ axial transition form-factors using PV electron scattering.
New measurements of high-momentum nucleons and short-range structures in nuclei (1107.3583)
N. Fomin, J. Arrington, R. Asaturyan, F. Benmokhtar, W. Boeglin, P. Bosted, A. Bruell, M. H. S. Bukhari, E. Chudakov, B. Clasie, S. H. Connell, M. M. Dalton, A. Daniel, D. B. Day, D. Dutta, R. Ent, L. El Fassi, H. Fenker, B. W. Filippone, K. Garrow, D. Gaskell, C. Hill, R. J. Holt, T. Horn, M. K. Jones, J. Jourdan, N. Kalantarians, C. E. Keppel, D. Kiselev, M. Kotulla, R. Lindgren, A. F. Lung, S. Malace, P. Markowitz, P. McKee, D. G. Meekins, H. Mkrtchyan, T. Navasardyan, G. Niculescu, A. K. Opper, C. Perdrisat, D. H. Potterveld, V. Punjabi, X. Qian, P. E. Reimer, J. Roche, V.M. Rodriguez, O. Rondon, E. Schulte, J. Seely, E. Segbefia, K. Slifer, G. R. Smith, P. Solvignon, V. Tadevosyan, S. Tajima, L. Tang, G. Testa, R. Trojer, V. Tvaskis, W. F. Vulcan, C. Wasko, F. R. Wesselmann, S. A. Wood, J. Wright, X. Zheng
We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.
Semi-Inclusive Charged-Pion Electroproduction off Protons and Deuterons: Cross Sections, Ratios and Access to the Quark-Parton Model at Low Energies (1103.1649)
R. Asaturyan, R. Ent, H. Mkrtchyan, T. Navasardyan, V. Tadevosyan, G. S. Adams, A. Ahmidouch, T. Angelescu, J. Arrington, A. Asaturyan, O. K. Baker, N. Benmouna, C. Bertoncini, H. P. Blok, W. U. Boeglin, P. E. Bosted, H. Breuer, M. E. Christy, S. H. Connell, Y. Cui, M. M. Dalton, S. Danagoulian, D. Day, J. A. Dunne, D. Dutta, N. El Khayari, H. C. Fenker, V. V. Frolov, L. Gan, D. Gaskell, K. Hafidi, W. Hinton, R. J. Holt, T. Horn, G. M. Huber, E. Hungerford, X. Jiang, M. Jones, K. Joo, N. Kalantarians, J. J. Kelly, C. E. Keppel, V. Kubarovsky, Y. Li, Y. Liang, D. Mack, S. P. Malace, P. Markowitz, E. McGrath, P. McKee, D. G. Meekins, A. Mkrtchyan, B. Moziak, G. Niculescu, I. Niculescu, A. K. Opper, T. Ostapenko, P. E. Reimer, J. Reinhold, J. Roche, S. E. Rock, E. Schulte, E. Segbefia, C. Smith, G. R. Smith, P. Stoler, L. Tang, M. Ungaro, A. Uzzle, S. Vidakovic, A. Villano, W. F. Vulcan, M. Wang, G. Warren, F. R. Wesselmann, B. Wojtsekhowski, S. A. Wood, C. Xu, L. Yuan, X. Zheng
Dec. 15, 2011 nucl-ex
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 < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, $P_t^2 < 0.2$ (GeV/c)$^2$. The invariant mass that goes undetected, $M_x$ or W', is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark --> pion production mechanisms. The x, z and $P_t^2$ dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for $\pi^+$ and $\pi^-$) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of $d$ quarks are found to be slightly smaller than for $u$ quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.
Nuclear transparency and effective kaon-nucleon cross section from the A(e, e'K+) reaction (1103.4120)
Nuruzzaman, D. Dutta, J. Arrington, R. Asaturyan, F. Benmokhtar, W. Boeglin, P. Bosted, A. Bruell, B. Clasie, M. E. Christy, E. Chudakov, M. M. Dalton, A. Daniel, D. Day, L. El Fassi, R. Ent, H. C. Fenker, J. Ferrer, N. Fomin, H. Gao, K. Garrow, D. Gaskel, C. Gray, T. Horn, G. M. Huber, M. K. Jones, N. Kalantarians, C. E. Keppel, K. Kramer, Y. Li, Y. Liang, A. F. Lung, S. Malace, P. Markowitz, A. Matsumura, D. G. Meekins, T. Mertens, T. Miyoshi, H. Mkrtchyan, R. Monson, T. Navasardyan, G. Niculescu, I. Niculescu, Y. Okayasu, A. K. Opper, C. Perdrisat, V. Punjabi, X. Qian, A. W. Rauf, V. M. Rodriquez, D. Rohe, J. Seely, E. Segbefia, G. R. Smith, M. Sumihama, V. Tadevosyan, L. Tang, V. Tvaskis, W. F. Vulcan, F. R. Wesselmann, S. A. Wood, L. Yuan, X. C. Zheng
Aug. 2, 2011 nucl-ex, nucl-th
We have determined the transparency of the nuclear medium to kaons from $A(e,e^{'} K^{+})$ measurements on $^{12}$C, $^{63}$Cu, and $^{197}$Au targets. The measurements were performed at the Jefferson Laboratory and span a range in four-momentum-transfer squared Q$^2$=1.1 -- 3.0 GeV$^2$. The nuclear transparency was defined as the ratio of measured kaon electroproduction cross sections with respect to deuterium, ($\sigma^{A}/\sigma^{D}$). We further extracted the atomic number ($A$) dependence of the transparency as parametrized by $T= (A/2)^{\alpha-1}$ and, within a simple model assumption, the in-medium effective kaon-nucleon cross sections. The effective cross sections extracted from the electroproduction data are found to be smaller than the free cross sections determined from kaon-nucleon scattering experiments, and the parameter $\alpha$ was found to be significantly larger than those obtained from kaon-nucleus scattering. We have included similar comparisons between pion- and proton-nucleon effective cross sections as determined from electron scattering experiments, and pion-nucleus and proton-nucleus scattering data.
Transverse Beam Spin Asymmetries at Backward Angles in Elastic Electron-Proton and Quasi-elastic Electron-Deuteron Scattering (1103.3667)
The G0 Collaboration, D. Androić, 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
June 16, 2011 hep-ph, nucl-ex, nucl-th
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.
The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles (1103.0761)
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
March 3, 2011 nucl-ex, physics.ins-det
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. The overall design and performance of this experimental system is discussed.
Scaling of the F_2 structure function in nuclei and quark distributions at x>1 (1008.2713)
N. Fomin, J. Arrington, D. B. Day, D. Gaskell, A. Daniel, J. Seely, R. Asaturyan, F. Benmokhtar, W. Boeglin, B. Boillat, P. Bosted, A. Bruell, M. H. S. Bukhari, M. E. Christy, E. Chudakov, B. Clasie, S. H. Connell, M. M. Dalton, D. Dutta, R. Ent, L. El Fassi, H. Fenker, B. W. Filippone, K. Garrow, C. Hill, R. J. Holt, T. Horn, M. K. Jones, J. Jourdan, N. Kalantarians, C. E. Keppel, D. Kiselev, M. Kotulla, R. Lindgren, A. F. Lung, S. Malace, P. Markowitz, P. McKee, D. G. Meekins, T. Miyoshi, H. Mkrtchyan, T. Navasardyan, G. Niculescu, Y. Okayasu, A. K. Opper, C. Perdrisat, D. H. Potterveld, V. Punjabi, X. Qian, P. E. Reimer, J. Roche, V.M. Rodriguez, O. Rondon, E. Schulte, E. Segbefia, K. Slifer, G. R. Smith, P. Solvignon, V. Tadevosyan, S. Tajima, L. Tang, G. Testa, R. Trojer, V. Tvaskis, W. F. Vulcan, C. Wasko, F. R. Wesselmann, S. A. Wood, J. Wright, X. Zheng
We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for $x>1$, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in ^2H and ^3He, but nearly identical for all heavier nuclei.
Short-Distance Structure of Nuclei (0908.0062)
D. W. Higinbotham, E. Piasetzky, S. A. Wood
Aug. 2, 2009 nucl-ex
One of Jefferson Lab's original missions was to further our understanding of the short-distance structure of nuclei. In particular, to understand what happens when two or more nucleons within a nucleus have strongly overlapping wave-functions; a phenomena commonly referred to as short-range correlations. Herein, we review the results of the (e,e'), (e,e'p) and (e,e'pN) reactions that have been used at Jefferson Lab to probe this short-distance structure as well as provide an outlook for future experiments.
Electroproduction of Eta Mesons in the S11(1535) Resonance Region at High Momentum Transfer (0804.3509)
M. M. Dalton, G. S. Adams, A. Ahmidouch, T. Angelescu, J. Arrington, R. Asaturyan, O. K. Baker, N. Benmouna, C. Bertoncini, W. U. Boeglin, P. E. Bosted, H. Breuer, M. E. Christy, S. H. Connell, Y. Cui, S. Danagoulian, D. Day, T. Dodario, J. A. Dunne, D. Dutta, N. El Khayari, R. Ent, H. C. Fenker, V. V. Frolov, L. Gan, D. Gaskell, K. Hafidi, W. Hinton, R. J. Holt, T. Horn, G. M. Huber, E. Hungerford, X. Jiang, M. K. Jones, K. Joo, N. Kalantarians, J. J. Kelly, C. E. Keppel, V. Kubarovsky, Y. Li, Y. Liang, S. Malace, P. Markowitz, P. McKee, D. G. Meekins, H. Mkrtchyan, B. Moziak, T. Navasardyan, G. Niculescu, I. Niculescu, A. K. Opper, T. Ostapenko, P. E. Reimer, J. Reinhold, J. Roche, S. E. Rock, E. Schulte, E. Segbefia, C. Smith, G. R. Smith, P. Stoler, V. Tadevosyan, L. Tang, V. Tvaskis, M. Ungaro, A. Uzzle, S. Vidakovic, A. Villano, W. F. Vulcan, M. Wang, G. Warren, F. R. Wesselmann, B. Wojtsekhowski, S. A. Wood, C. Xu, L. Yuan, X. Zheng, H. Zhu
June 7, 2009 hep-ex
The differential cross-section for the process p(e,e'p)eta has been measured at Q2 ~ 5.7 and 7.0 (GeV/c)2 for centre-of-mass energies from threshold to 1.8 GeV, encompassing the S11(1535) resonance, which dominates the channel. This is the highest momentum transfer measurement of this exclusive process to date. The helicity-conserving transition amplitude A_1/2, for the production of the S11(1535) resonance, is extracted from the data. Within the limited Q2 now measured, this quantity appears to begin scaling as 1/Q3 - a predicted, but not definitive, signal of the dominance of perturbative QCD, at Q2 ~ 5 (GeV/c)2.
x- and xi-scaling of the Nuclear Structure Function at Large x (nucl-ex/0102004)
J. Arrington, C. S. Armstrong, T. Averett, O. K. Baker, L. de Bever, C. W. Bochna, W. Boeglin, B. Bray, R. D. Carlini, G. Collins, C. Cothran, D. Crabb, D. Day, J. A. Dunne, D. Dutta, R. Ent, B. W. Filippone, A. Honegger, E. W. Hughes, J. Jensen, J. Jourdan, C. E. Keppel, D. M. Koltenuk, R. Lindgren, A. Lung, D. J Mack, J. McCarthy, R. D. McKeown, D. Meekins, J. H. Mitchell, H. G. Mkrtchyan, G. Niculescu, I. Niculescu, T. Petitjean, O. Rondon, I. Sick, C. Smith, B. Terburg, W. F. Vulcan, S. A. Wood, C. Yan, J. Zhao, B. Zihlmann
Inclusive electron scattering data are presented for ^2H and Fe targets at an incident electron energy of 4.045 GeV for a range of momentum transfers from Q^2 = 1 to 7 (GeV/c)^2. Data were taken at Jefferson Laboratory for low values of energy loss, corresponding to values of Bjorken x greater than or near 1. The structure functions do not show scaling in x in this range, where inelastic scattering is not expected to dominate the cross section. The data do show scaling, however, in the Nachtmann variable \xi. This scaling may be the result of Bloom Gilman duality in the nucleon structure function combined with the Fermi motion of the nucleons in the nucleus. The resulting extension of scaling to larger values of \xi opens up the possibility of accessing nuclear structure functions in the high-x region at lower values of Q^2 than previously believed.