Search

We propose a new measurement of the ratio of positron-proton to electron-proton, elastic scattering at DESY to determine the contributions beyond single-photon exchange, which are essential to the QED description of the most fundamental process in hadronic physics. A 20~cm long liquid hydrogen target together with the extracted beam from the DESY synchrotron would yield an average luminosity of $2.12\times10^{35}$~cm$^{-2}\cdot$s$^{-1}\cdot$sr$^{-1}$ ($\sim200$ times the luminosity achieved by OLYMPUS). A commissioning run at 2 GeV followed by measurements at 3 GeV would provide new data up to $Q^2=4.6$~(GeV/$c$)$^2$ (twice the range of current measurements). Lead tungstate calorimeters would be used to detect the scattered leptons at polar angles of $30^\circ$, $50^\circ$, $70^\circ$, $90^\circ$, and $110^\circ$. The measurements could be scheduled to not interfere with the operation of PETRA. We present rate estimates and simulations for the planned measurements including background considerations. Initial measurements at the DESY test beam facility using prototype lead tungstate calorimeters in 2019, 2021, and 2022 were made to check the Monte Carlo simulations and the performance of the calorimeters. These tests also investigated different readout schemes (triggered and streaming). Various upgrades are possible to shorten the running time and to make higher beam energies and thus greater $Q^2$ ranges accessible., 45 pages, 43 figures, submitted to the DESY PRC

We report a measurement of two energy-weighted gamma cascade angular distributions from polarized slow neutron capture on the ${}^{35}$Cl nucleus, one parity-odd correlation proportional to $\vec{s_{n}} \cdot \vec{k_{\gamma}}$ and one parity-even correlation proportional to $\vec{s_{n}} \cdot \vec{k_{n}} \times \vec{k_{\gamma}}$. A parity violating asymmetry can appear in this reaction due to the weak nucleon-nucleon (NN) interaction which mixes opposite parity S and P-wave levels in the excited compound $^{36}$Cl nucleus formed upon slow neutron capture. If parity-violating (PV) and parity-conserving (PC) terms both exist, the measured differential cross section can be related to them via $\frac{d\sigma}{d\Omega}\propto1+A_{\gamma, PV}\cos\theta+A_{\gamma,PC}\sin\theta$. The PV and PC asymmetries for energy-weighted gamma cascade angular distributions for polarized slow neutron capture on $^{35}$Cl averaged over the neutron energies from 2.27~meV to 9.53~meV were measured to be $A_{\gamma,PV}=(-23.9\pm0.7)\times 10^{-6}$ and $A_{\gamma,PC}=(0.1\pm0.7)\times 10^{-6}$. These results are consistent with previous experimental results. Systematic errors were quantified and shown to be small compared to the statistical error. These asymmetries in the angular distributions of the gamma rays emitted from the capture of polarized neutrons in $^{35}$Cl were used to verify the operation and data analysis procedures for the NPDGamma experiment which measured the parity-odd asymmetry in the angular distribution of gammas from polarized slow neutron capture on protons.

The search for a dark photon holds considerable interest in the physics community. Such a force carrier would begin to illuminate the dark sector. Many experiments have searched for such a particle, but so far it has proven elusive. In recent years the concept of a low mass dark photon has gained popularity in the physics community. Of particular recent interest is the $^8$Be and $^4$He anomaly, which could be explained by a new fifth force carrier with a mass of 17 MeV/$c^2$. The proposed DarkLight experiment would search for this potential low mass force carrier at ARIEL in the 10-20 MeV e$^+$e$^-$ invariant mass range. This proceeding will focus on the experimental design and physics case of the DarkLight experiment., Comment: 7 pages, 4 figures, to be submitted as part of the proceedings on "New Scientific Opportunities with the TRIUMF ARIEL e-linac"

The COmpact detectoR for the Eic (CORE) Proposal was submitted to the EIC "Call for Collaboration Proposals for Detectors". CORE comprehensively covers the physics scope of the EIC Community White Paper and the National Academies of Science 2018 report. The design exploits advances in detector precision and granularity to minimize size. The central detector includes a 3Tesla, 2.5m solenoid. Tracking is primarily silicon. Electromagnetic calorimetry is based on the high performance crystals. Ring-imaging Cherenkov detectors provide hadronic particle identification., Comment: Contact authors: C.E. Hyde, chyde@odu.edu and P. Nadel-Turonski, turonski@jlab.org

Physical review letters 126(16), 162501 (1-6) (2021). doi:10.1103/PhysRevLett.126.162501, We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading effects of hard two-photon exchange, giving more robust access to the proton’s electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of Møller, Bhabha, and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits, Published by APS, College Park, Md.

We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading effects of hard two-photon exchange, giving more robust access to the proton's electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of M{\o}ller, Bhabha and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits.

We report the first observation of the parity-violating 2.2 MeV gamma-ray asymmetry $A^{np}_\gamma$ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. $A^{np}_\gamma$ isolates the $\Delta I=1$, \mbox{$^{3}S_{1}\rightarrow {^{3}P_{1}}$} component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless EFT. We measured $A^{np}_\gamma = [-3.0 \pm 1.4 (stat) \pm 0.2 (sys)]\times 10^{-8}$, which implies a DDH weak $\pi NN$ coupling of $h_{\pi}^{1} = [2.6 \pm 1.2(stat) \pm 0.2(sys)] \times 10^{-7}$ and a pionless EFT constant of $C^{^{3}S_{1}\rightarrow ^{3}P_{1}}/C_{0}=[-7.4 \pm 3.5 (stat) \pm 0.5 (sys)] \times 10^{-11}$ MeV$^{-1}$. We describe the experiment, data analysis, systematic uncertainties, and the implications of the result., Comment: 6 pages, 5 figures

New highly transparent, hydrophobic silica aerogels with refractive indices of 1.01 to 1.07 have been produced by Aspen Aerogels, Inc., and select tiles have been tested using an electron beam at the DESY, Hamburg facility. A diffusively-reflective threshold Cerenkov counter was designed and constructed for the purpose of evaluating the aerogels, and can accommodate aerogel tile areas of up to 20 cm by 20 cm. Measurements of the performance of the counter using the new aerogels as Cerenkov radiators are given in terms of photoelectron yields and a figure of merit.

We report the first observation of the parity-violating 2.2 MeV gamma-ray asymmetry $A^{np}_��$ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. $A^{np}_��$ isolates the $��I=1$, \mbox{$^{3}S_{1}\rightarrow {^{3}P_{1}}$} component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless EFT. We measured $A^{np}_��= [-3.0 \pm 1.4 (stat) \pm 0.2 (sys)]\times 10^{-8}$, which implies a DDH weak $��NN$ coupling of $h_��^{1} = [2.6 \pm 1.2(stat) \pm 0.2(sys)] \times 10^{-7}$ and a pionless EFT constant of $C^{^{3}S_{1}\rightarrow ^{3}P_{1}}/C_{0}=[-7.4 \pm 3.5 (stat) \pm 0.5 (sys)] \times 10^{-11}$ MeV$^{-1}$. We describe the experiment, data analysis, systematic uncertainties, and the implications of the result., 6 pages, 5 figures

We report the measurement of the beam-vector and tensor asymmetries $A^V_{ed}$ and $A^T_d$ in quasielastic $(\vec{e}, e^{\prime}p)$ electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator Center up to missing momentum of 500~MeV/c. Data were collected simultaneously over a momentum transfer range $0.1< Q^2, 5 pages, 3 figures

GSI Scientific Report 2014 - GSI Report 2015-1

New results on laser cooling of stored, bunched, relativistic ion beams are presented. For the first time it has been possible to cool an ion beam with large momentum spread without initial electron cooling or scanning of the bunching frequency by using a single cw laser system.

With new, all solid-state cw laser sources cooling of relativistic ion beams with a large momentum spread has become possible. We present results on laser cooling of relativistic C3+ ion beams at the Experimental Storage Ring at GSI. In the experiment we used a frequency-quadrupled external-cavity diode laser for scanning over a relative ion momentum spread of dp/p ~ 10-5. We could show that laser cooling with such a system is almost independent of beam current and that the momentum spread reached for various bunching harmonics, bucket depths and beam currents always was found to be comparable to the resolution of the resonant Schottky pickup at ESR. We further found a decrease in Schottky power with decreasing momentum spread and that cooling times were only limited by the scanning time of the laser. The laser cooling technique presented here is of great interest for future heavy ion storage rings as it allows to address ion beams with an initially large momentum spread, thus not requiring initial electron cooling.

We describe the current status of the DarkLight experiment at Jefferson Laboratory. DarkLight is motivated by the possibility that a dark photon in the mass range 10 to 100 MeV/c$^2$ could couple the dark sector to the Standard Model. DarkLight will precisely measure electron proton scattering using the 100 MeV electron beam of intensity 5 mA at the Jefferson Laboratory energy recovering linac incident on a windowless gas target of molecular hydrogen. The complete final state including scattered electron, recoil proton, and e+e- pair will be detected. A phase-I experiment has been funded and is expected to take data in the next eighteen months. The complete phase-II experiment is under final design and could run within two years after phase-I is completed. The DarkLight experiment drives development of new technology for beam, target, and detector and provides a new means to carry out electron scattering experiments at low momentum transfers., Comment: Whitepaper submitted to Town Meeting on Fundamental and Symmetries and Neutrinos, O'Hare airport, Chicago, IL

We give a short overview of the DarkLight detector concept which is designed to search for a heavy photon A' with a mass in the range 10 MeV/c^2 < m(A') < 90 MeV/c^2 and which decays to lepton pairs. We describe the intended operating environment, the Jefferson Laboratory free electon laser, and a way to extend DarkLight's reach using A' --> invisible decays., 8 pages, 4 figures, contributed to the Community Summer Study 2013 "Snowmass on the Mississippi" in the New, Light, Weakly Coupled Particles (NLWCP) subgroup of the Intensity Frontier

It is difficult to estimate how much distributed generation (DG) capacity will be connected to distribution systems in the coming years, however, it is certain that increasing penetration levels require robust tools that help assess the capabilities and requirements of the networks in order to produce the best planning and control strategies. The work of this Task Force is focused on the numerous strategies and methods that have been developed in recent years to address DG integration and planning. This paper contains a critical review of the work in this field. Although there have been numerous publications in this area, widespread implementation of the methods has not taken place. The barriers to implementation of the advanced techniques are outlined, highlighting why network operators have been slow to pick up on the research to date. Furthermore, key challenges ahead which remain to be tackled are also described, many of which have come into clear focus with the current drive towards smarter distribution networks.

We present new results on laser cooling of relativistic C3+ ion beams at the Experimental Storage Ring at GSI. For the first time we could show laser cooling of bunched relativistic ion beams using fast scanning of the frequency of the cooling laser over a range larger than the momentum acceptance of the bucket. Unlike previously employed cooling schemes where the bucket frequency was scanned relatively to a fixed laser frequency, scanning of the laser frequency can be readily applied to future high energy storage rings such as HESR or SIS 100 at FAIR.

Cooling of ion beams is essential for precision experiments at future storage rings. Laser cooling is one of the most promising techniques to reach high phase space densities at relativistic ion energies for all ion species which provide suitable atomic cooling transitions. Establishing laser cooling as a standard technique at future storage rings requires laser sources that can address ion beams with large initial velocity spreads. Without optical diagnostics however, the dynamics of ions at very low temperatures cannot be resolved, as conventional beam diagnostics reach their resolution limits. We discuss concepts and techniques that pave the way for making laser cooling a reliable tool at future storage rings, some of which can already be tested at the ESR at GSI.

We report precision 1H(e,e′π+)n measurements in the Δ(1232) resonance at Q2=0.127(GeV/c)2 obtained at the MIT-Bates out-of-plane scattering facility. These are the lowest, but nonzero, Q2 measurements in the π+ channel. The data offer tests of the theoretical calculations, particularly of the background amplitude contributions. The chiral effective field theory and Sato-Lee model calculations are not in agreement with this experiment. © 2011 American Physical Society.

Experimental details of a virtual Compton scattering (VCS) experiment performed on the proton at the MIT-Bates out-of-plane scattering facility are presented. The VCS response functions PLL-PTT/P TT and PLT have been measured at Q2=0.057GeV2/c2. The generalized electric and magnetic polarizabilities, α(Q2) and β(Q2), and the mean-square electric polarizability radius rα2 are obtained from a dispersion analysis of the data. The results are in good agreement with O(p3) heavy baryon chiral perturbation and indicate the dominance of mesonic effects in the polarizabilities. © 2011 American Physical Society.

Se determinó la riqueza de Pteridoflora. Avifauna y Orquídeo-flora del bosque del Centro de Producción e Investigación "Pablo Yacu" de la Facultad de Ecología de la UNSM-T. El área tiene una extensión ele 200 Has., y se ubica entre los 870 y 1700 msnm. Las observaciones se realizaron en octubre del 2008 y marzo del 2009. Para la identificación de helechos, se utilizó claves taxonómicas de Tryon y Stolze ( 1989a, 1989b, 1991. 1992, 1993, 1994 ), se comparó con muestras del Herbarium T ruxi II ience y registros fotográficos. Respecto a la avifauna se utilizó la técnica de presencia/ausencia en horarios matutino y vespertino considerando el hábitat/micro-hábitat. Para las orquídeas, el muestreo se realizó mediante transectos perpendiculares al del Pteridofitos, con determinaciones "in situ" complementadas con bibliografía especifica.El registro fotográfico fue ele las que estuvieron en floración. La riqueza de pteridofitos es de 136 ( 44 géneros y 21 fami I ias). de avifauna fue ele 278 especies: 202 géneros y 40 familias con tres especies endémicas y las orquídeas presentan 45 especies distribuidas en 34 géneros. Finalmente, se concluye que se podría iniciar actividades y acciones para realizar una base ele datos que contribuya a la implementación ele la estrategia ele diversidad biológica de la región San Martín.

We report new measurements of the neutron charge form factor at low momentum transfer using quasielastic electrodisintegration of the deuteron. Longitudinally polarized electrons at an energy of 850 MeV were scattered from an isotopically pure, highly polarized deuterium gas target. The scattered electrons and coincident neutrons were measured by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The neutron form factor ratio $G^{n}_{E}/G^{n}_{M}$ was extracted from the beam-target vector asymmetry $A_{ed}^{V}$ at four-momentum transfers $Q^{2}=0.14$, 0.20, 0.29 and 0.42 (GeV/c)$^{2}$., 5 pages, 3 figures, submitted to Phys. Rev. Lett

We report the first precision measurement of the proton electric to magnetic form factor ratio from spin-dependent elastic scattering of longitudinally polarized electrons from a polarized hydrogen internal gas target. The measurement was performed at the MIT-Bates South Hall Ring over a range of four-momentum transfer squared $Q^2$ from 0.15 to 0.65 (GeV/c)$^2$. Significantly improved results on the proton electric and magnetic form factors are obtained in combination with previous cross-section data on elastic electron-proton scattering in the same $Q^2$ region., 4 pages, 2 figures, submitted to PRL

The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q(2)=0.057 GeV2/c(2) are in agreement with O(p(3)) heavy baryon chiral perturbation theory. The data support the dominance of mesonic effects in the polarizabilities.

We report new precise H(e,e(’)p)pi(0) measurements at the Delta(1232) resonance at Q(2)=0.127 (GeV/c)(2) obtained at the MIT-Bates out-of-plane scattering facility which are particularly sensitive to the transverse electric amplitude (E2) of the gamma(*)N–>Delta transition. The new data have been analyzed together with those of earlier measurements to yield precise quadrupole to dipole amplitude ratios: Re(E-1+(3/2)/M-1+(3/2))=(-2.3+/-0.3(stat+syst)+/-0.6(model))% and Re(S-1+(3/2)/M-1+(3/2))=(-6.1+/-0.2(stat+syst)+/-0.5(model))% for M-1+(3/2)=(41.4+/-0.3(stat+syst)+/-0.4(model))(10(-3)/m(pi)(+)). The derived amplitudes give credence to the conjecture of deformation in hadrons favoring, at low Q(2), the dominance of mesonic effects.

Accurate measurements of the p(→e, e′p)π0 reaction were performed at Q2 = 0.127 (GeV/c)2 in the A resonance energy region. The experiments at the MIT-Bates Linear Accelerator used an 820 MeV polarized electron beam with the out-of-plane magnetic spectrometer system (OOPS). In this Letter we report the first simultaneous determination of both the TL and TL′ ("fifth" or polarized) cross sections at low Q2 where the pion cloud contribution is predicted to dominate the quadrupole amplitudes (E2 and C2). These are the real and imaginary parts of the transverse-longitudinal interference amplitudes and provide a sensitive determination of the Coulomb quadrupole amplitude and a test of reaction calculations. Comparisons with model calculations are presented. The empirical MAID calculation gives the best overall agreement with this accurate data. The parameters of this model for the values of the resonant multipoles are [M1+(I = 3/2)| = (40.9 ± 0.3) × 10-3/mπ, CMR = C2/M1 = -6.5 ± 0.3%, EMR = E2/M1 = -2.2 ± 0.9%, where the errors are due to the experimental uncertainties. © 2003 Elsevier Science B.V. All rights reserved.

Quadrupole amplitudes in the [Formula Presented] 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 [Formula Presented] data obtained at [Formula Presented] and invariant mass of [Formula Presented] using the out-of-plane detection technique with the OOPS spectrometers. The [Formula Presented] and [Formula Presented] response functions were isolated. These results, along with those of previous measurements at [Formula Presented] and [Formula Presented] aim in elucidating the interplay between resonant and nonresonant amplitudes. © 2003 The American Physical Society.

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 $Q^2= 0.070$ (GeV/c)$^2$ and invariant mass of W=1155 MeV using the out-of-plane detection technique with the OOPS spectrometers. The $\sigma_{LT}$ and $\sigma_{T}+\epsilon\cdot$ $\sigma_{L}$ response functions were isolated. These results, along with those of previous measurements at $W$=1172 MeV and $Q^2= 0.127$ (GeV/c)$^2$, aim in elucidating the interplay between resonant and non resonant amplitudes.

Quadrupole amplitudes in the $��^{*}N\to��$ 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$(e,e^\prime p)��^0$ data obtained at $Q^2= 0.070$ (GeV/c)$^2$ and invariant mass of W=1155 MeV using the out-of-plane detection technique with the OOPS spectrometers. The $��_{LT}$ and $��_{T}+��\cdot$ $��_{L}$ response functions were isolated. These results, along with those of previous measurements at $W$=1172 MeV and $Q^2= 0.127$ (GeV/c)$^2$, aim in elucidating the interplay between resonant and non resonant amplitudes.

We report on the design and performance of compact detector packages currently installed in the four magnetic out-of-plane spectrometers for electron scattering experiments at the MIT-Bates Linear Accelerator Center. The detector packages have been designed to meet the mechanical requirements arising from out-of-plane particle detection. They offer good trajectory and momentum reconstruction, particle identification and time-of-flight measurements for electrons, pions, protons, and deuterons with large momentum bites and in broad kinematical ranges and high luminosities. The detectors have so far been used with great success in out-of-plane measurements of 12C(e→,e′p), 2H(e→,e′p), virtual Compton scattering below pion threshold and in studies of the N→Δ transition in both exclusive reaction channels 1H(e→,e′p)π0 and 1H(e→,e′π+)n. © 2002 Elsevier Science B.V. All rights reserved.

High-precision 1H(e, elp)φ0 measurements at Q2 = 0.126 (GeV/c)2 are presented. It allows the determination of quadrupole amplitudes in the γ*N → △ transition, in which the reliability of electroproduction models was simultaneously tested. The derived quadrupole-to-dipole (I = 3/2) amplitude ratios, RSM = (-6.5 ± 0.2stat+sys ± 2.5mod)% and REM = (-2.1 ± 0.2stat+sys ± 2.0mod)%, are dominated by model error.

Physical Review Letters

Measurements of the 2H(e→, e′p)n reaction were performed with the out-of-plane magnetic spectrometers (OOPS) at the MIT-Bates Linear Accelerator. The longitudinal-transverse, fLT and f′LT, and the transverse-transverse, fTT, interference responses at a missing momentum of 210MeV/c were simultaneously extracted in the dip region at Q2 = 0.15(GeV/c)2. In comparison to models of deuteron electrodisintegration, the data clearly reveal strong effects of relativity and final-state interactions and the importance of two-body meson-exchange currents and isobar configurations. We demonstrate that such effects can be disentangled by extracting these responses using the novel out-of-plane technique. © 2001 The American Physical Society.

Measurements of the ${^2}H(\vec{e},e^{\prime}p)n$ reaction were performed using an 800-MeV polarized electron beam at the MIT-Bates Linear Accelerator and with the out-of-plane magnetic spectrometers (OOPS). The longitudinal-transverse, $f_{LT}$ and $f_{LT}^{\prime}$, and the transverse-transverse, $f_{TT}$, interference responses at a missing momentum of 210 MeV/c were simultaneously extracted in the dip region at Q$^2$=0.15 (GeV/c)$^2$. On comparison to models of deuteron electrodisintegration, the data clearly reveal strong effects of relativity and final-state interactions, and the importance of the two-body meson-exchange currents and isobar configurations. We demonstrate that these effects can be disentangled and studied by extracting the interference response functions using the novel out-of-plane technique., Comment: 4 pages, 4 figures, and submitted to PRL for publication

The ultra-thin gas targets used in storage ring internal target experiments allow low energy, heavy nuclei to emerge from the target region. A detector capable of analyzing these nuclei provides unique access to many nuclear reactions. We report here the first use of such a detector in conjunction with a polarized He-3 internal target and a polarized electron beam. The results of using the detector as a luminosity monitor and as a polarimeter to measure the product of beam and target polarizations are presented. The ability to study coherent pion production via the reactions 3 (H) over right arrow e((e) over right arrow,e'' He-3)pi(0) and 3 (H) over right arrow e((e) over right arrow,e'' H-3)pi(+) is shown along with the ability of the detector to unambiguously separate the two- and threebody breakup channels of the reaction 3 (H) over right arrow e((e) over right arrow,e'' p). (C) 2000 Elsevier Science B.V. All rights reserved.

We report on the first measurement of spin-correlation parameters in quasifree electron scattering from vector-polarized deuterium. Polarized electrons were injected into an electron storage ring at a beam energy of 720 MeV. A Siberian snake was employed to preserve longitudinal polarization at the interaction point. Vector-polarized deuterium was produced by an atomic beam source and injected into an open-ended cylindrical cell, internal to the electron storage ring. The spin correlation parameter $A^V_{ed}$ was measured for the reaction $^2 \vec{\rm H}(\vec e,e^\prime n)p$ at a four-momentum transfer squared of 0.21~(GeV/$c$)$^2$ from which a value for the charge form factor of the neutron was extracted., 4 pages, proceedings for the panic99 conference

We report on the first measurement of spin-correlation parameters in quasifree electron scattering from vector-polarized deuterium. Polarized electrons were injected into an electron storage ring at a beam energy of 720~MeV. A Siberian snake was employed to preserve longitudinal polarization at the interaction point. Vector-polarized deuterium was produced by an atomic beam source and injected into an open-ended cylindrical cell, internal to the electron storage ring. The spin correlation parameter A^V_{ed} was measured for the reaction \pol{2H}(\pol{e},e'n)p at a four-momentum transfer squared of 0.21 (GeV/c)^2 from which a value for the charge form factor of the neutron was extracted., 4 pages, 5 files

We report on the first measurement of spin-correlation parameters in quasifree electron scattering from vector-polarized deuterium. Polarized electrons were injected into an electron storage ring at a beam energy of 720 MeV. A Siberian snake was employed to preserve longitudinal polarization at the interaction paint. Vector-polarized deuterium was produced by an atomic beam source and injected into an open-ended cylindrical cell, internal to the electron storage ring. The spin correlation parameter A(ed)(V) was measured for the reaction 2 (H) over right arrow((e) over right arrow, e'' n)p at a four-momentum transfer squared of 0.21 (GeV/c)(2) from which a value for the charge form factor of the neutron was extracted.

High-precision H(e,e'p)pi0 measurements at Q2=0.126 (GeV/c)2 are reported, which allow the determination of quadrupole amplitudes in the gamma* N->Delta transition; they simultaneously test the reliability of electroproduction models. The derived quadrupole-to-dipole amplitude ratios, Rsm=(-6.5 +- 0.2{stat+sys} +- 2.5{mod}) % and Rem=(-2.1 +- 0.2{stat+sys} +- 2.0{mod}) %, are dominated by model error. Previous Rsm and Rem results should be reconsidered after the model uncertainties associated with the method of their extraction are taken into account., 5 pages LATEX, 2 figures; resubmitted to Phys. Rev. Lett

We report on a measurement of the tensor analyzing power T-20 in elastic electron-deuteron scattering in the range of four-momentum transfer from 1.8 to 3.2 fm(-1). Electrons of 704 MeV were scattered from a polarized deuterium internal target. The tensor polarization of the deuterium nuclei was determined with an ion-extraction system, allowing an absolute measurement of T-20 The data are described well by a nonrelativistic calculation that includes the effects of meson-exchange currents.

We present a 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 GeV2/c(2), respectively. We measured a large induced polarization, P-n = -0.397 +/- 0.055 +/- 0.009. The data suggest that the scalar background is larger than expected from a recent effective Hamiltonian model. [S0556-2813(98)02012-3].

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. The integrated strengths of the p- and s-shell are compared with a Distorted Wave Impulse Approximation calculation. The s-shell strength and shape are compared with a Hartree Fock-Random Phase Approximation calculation. The DWIA calculation overestimates the cross sections for p- and s-shell proton knockout as expected, but surprisingly agrees with the extracted R_LT value for both shells. The HF-RPA calculation describes the data more consistently, which may be due to the inclusion of 2-body currents in this calculation., 8 Pages LaTex, 5 postscript figures. Submitted to Phys. Rev. C