C. W. de Jager

Nuclear charge-density-distribution parameters from elastic electron scattering

Abstract A compilation of nuclear charge-density-distribution parameters, obtained from elastic electron scattering, is presented in five separate tables. Data on charge distributions obtained on the basis of a phenomenological model—parameters of nuclei and differences therein between isotopes and between other neighboring nuclei like isotones—are given in Tables I, II, and III. Parameters obtained by a model-independent analysis are given in two additional tables: Table IV gives the coefficients of a Fourier-Bessel series expansion, and Table V gives the positions and amplitudes for the expansion in a sum of gaussians. References through February 1986 have been covered.

Nuclear charge and magnetization density distribution parameters from elastic electron scattering

A compilation of nuclear charge- and magnetization-density-distribution parameters, found from elastic electron scattering, is presented. The data on charge distributions, obtained on the basis of a phenomenological model, are given in three separate tables: parameters of nuclei, differences therein between isotopes and between other neighbouring nuclei such as isotones. A fourth table is devoted to charge distributions obtained by model-independent analyses. In the final table the available data on magnetization-density distributions are listed. References through April 1974 have been covered.

Search for a New Gauge Boson in Electron-Nucleus Fixed-Target Scattering by the APEX Experiment

S. Abrahamyan,1 Z. Ahmed,2 K. Allada,3 D. Anez,4 T. Averett,5 A. Barbieri,6 K. Bartlett,7 J. Beacham,8 J. Bono,9 J.R. Boyce,10 P. Brindza,10 A. Camsonne,10 K. Cranmer,8 M.M. Dalton,6 C.W. de Jager,10, 6 J. Donaghy,7 R. Essig,11, ∗ C. Field,11 E. Folts,10 A. Gasparian,12 N. Goeckner-Wald,13 J. Gomez,10 M. Graham,11 J.-O. Hansen,10 D.W. Higinbotham,10 T. Holmstrom,14 J. Huang,15 S. Iqbal,16 J. Jaros,11 E. Jensen,5 A. Kelleher,15 M. Khandaker,17, 10 J.J. LeRose,10 R. Lindgren,6 N. Liyanage,6 E. Long,18 J. Mammei,19 P. Markowitz,9 T. Maruyama,11 V. Maxwell,9 S. Mayilyan,1 J. McDonald,11 R. Michaels,10 K. Moffeit,11 V. Nelyubin,6 A. Odian,11 M. Oriunno,11 R. Partridge,11 M. Paolone,20 E. Piasetzky,21 I. Pomerantz,21 Y. Qiang,10 S. Riordan,19 Y. Roblin,10 B. Sawatzky,10 P. Schuster,11, 22, † J. Segal,10 L. Selvy,18 A. Shahinyan,1 R. Subedi,23 V. Sulkosky,15 S. Stepanyan,10 N. Toro,24, 22, ‡ D. Walz,11 B. Wojtsekhowski,10, § and J. Zhang10 Yerevan Physics Institute, Yerevan 375036, Armenia Syracuse University, Syracuse, New York 13244 University of Kentucky, Lexington, Kentucky 40506 Saint Mary’s University, Halifax, NS B3H 3C3, Canada College of William and Mary, Williamsburg, Virginia 23187 University of Virginia, Charlottesville, Virginia 22903 University of New Hampshire, Durham, New Hampshire 03824 New York University, New York, New York 10012 Florida International University, Miami, Florida 33199 Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 SLAC National Accelerator Laboratory, Menlo Park, California 94025 North Carolina Agricultural and Technical State University, Greensboro, North Carolina 27411 Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 Longwood University, Farmville, Virginia 23909 Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 California State University at Los Angeles, Los Angeles, California 90032 Norfolk State University, Norfolk, Virginia 23504 Kent State University, Kent, Ohio 44242 University of Massachusetts, Amherst, Massachusetts 01003 University of South Carolina, Columbia, South Carolina 29225 Tel Aviv University, Tel Aviv, 69978 Israel Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5, Canada George Washington University, Washington DC 20052 Stanford University, Menlo Park, California 94025 (Dated: February 1, 2013)

Probing Cold Dense Nuclear Matter

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

Parity-violating electron scattering from 4He and the strange electric form factor of the nucleon.

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from ^4He at an average scattering angle= 5.7 degrees and a four-momentum transfer Q^2 = 0.091 GeV^2. From these data, for the first time, the strange electric form factor of the nucleon G^s_E can be isolated. The measured asymmetry of A_PV = (6.72 +/- 0.84 (stat) +/- 0.21 (syst) parts per million yields a value of G^s_E = -0.038 +/- 0.042 (stat) +/- 0.010 (syst), consistent with zero.

Measurement of the Neutral Weak Form Factors of the Proton

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The kinematic point [{l_angle}{theta}{sub lab }{r_angle}=12.3{degree} and {l_angle}Q{sup 2}{r_angle}=0.48 (GeV /c){sup 2} ] is chosen to provide sensitivity, at a level that is of theoretical interest, to the strange electric form factor G{sup s}{sub E} . The result, A={minus}14.5{plus_minus}2.2 ppm , is consistent with the electroweak standard model and no additional contributions from strange quarks. In particular, the measurement implies G{sup s}{sub E}+0.39G{sup s}{sub M}=0.023 {plus_minus}0.034(stat){plus_minus}0.022( syst){plus_minus}0.026({delta}G{sup n}{sub E}) , where the last uncertainty arises from the estimated uncertainty in the neutron electric form factor. {copyright} {ital 1999} {ital The American Physical Society}

Precision Measurements of the Nucleon Strange Form Factors at Q**2 ~ 0.1-GeV**2

We report new measurements of the parity-violating asymmetry A_PV in elastic scattering of 3 GeV electrons off hydrogen and 4He targets with~6.0 degrees. The 4He result is A_PV = (+6.40 +/- 0.23 (stat) +/- 0.12 (syst)) x10^-6. The hydrogen result is A_PV = (-1.58 +/- 0.12 (stat) +/- 0.04 (syst)) x10^-6. These results significantly improve constraints on the electric and magnetic strange form factors G_E^s and G_M^s. We extract G_E^s = 0.002 +/- 0.014 +/- 0.007 at= 0.077 GeV^2, and G_E^s + 0.09 G_M^s = 0.007 +/- 0.011 +/- 0.006 at= 0.109 GeV^2, providing new limits on the role of strange quarks in the nucleon charge and magnetization distributions.

The 500 MeV electron-scattering facility at NIKHEF-K

The 500 MeV electron-scattering facility, designed and built in conjunction with the 500 MeV, 2.5% duty factor electron linear accelerator (MEA), has been completed. It allows high-resolution (1 × 10−4) single-arm (e,e′) experiments with a QDD spectrometer and single-arm hadron detection [(γ, π) and (γ,p) reactions] with a large solid angle (17 msr) QDQ spectrometer. With both specrometers coincidence experiments (e,e′x) can be performed with a 225 keV missing energy resolution and a 1 ns timing resolution. A comprehensive description is given of the beam-handling system, spectrometers, detection system, data handling techniques and other instrumentation. Finally, test results obtained at energies ranging from 70 to 460 MeV are presented.

Constraints on the nucleon strange form factors at Q2∼0.1 GeV2

We report the most precise measurement to date of a parity-violating asymmetry in elastic electron-proton scattering. The measurement was carried out with a beam energy of 3.03 GeV and a scattering angle=6 degrees, with the result A_PV = -1.14 +/- 0.24 (stat) +/- 0.06 (syst) parts per million. From this we extract, at Q^2 = 0.099 GeV^2, the strange form factor combination G_E^s + 0.080 G_M^s = 0.030 +/- 0.025 (stat) +/- 0.006 (syst) +/- 0.012 (FF) where the first two errors are experimental and the last error is due to the uncertainty in the neutron electromagnetic form factor. This result significantly improves current knowledge of G_E^s and G_M^s at Q^2 ~0.1 GeV^2. A consistent picture emerges when several measurements at about the same Q^2 value are combined: G_E^s is consistent with zero while G_M^s prefers positive values though G_E^s=G_M^s=0 is compatible with the data at 95% C.L.

Precision Measurement of the Neutron Spin Asymmetries and Spin-dependent Structure Functions in the Valence Quark Region

We report on measurements of the neutron spin asymmetries