[en] Here, we report the measurement of the beam-vector and tensor asymmetries $A_{ed}^V$ and $A_d^T$ in quasielastic $(\overrightarrow{e},e^{\text{'}}p)$ electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator Center up to missing momentum of $500\mathrm{MeV}/c$. Data were collected simultaneously over a momentum transfer range $0.1<Q^2<0.5(\mathrm{GeV}/c{)}^2$ with the Bates Large Acceptance Spectrometer Toroid using an internal deuterium gas target polarized sequentially in both vector and tensor states. The data are compared with calculations. The beam-vector asymmetry $A_{ed}^V$ is found to be directly sensitive to the $D$-wave component of the deuteron and has a zero crossing at a missing momentum of about $320\mathrm{MeV}/c$, as predicted. The tensor asymmetry $A_d^T$ at large missing momentum is found to be dominated by the influence of the tensor force in the neutron-proton final-state interaction. The new data offer a strong constraint on theoretical models.

[en] At the MIT-Bates Linear Accelerator Center, the ratio G_E^p G_M^p has been measured by means of elastic scattering of polarized electrons from polarized hydrogen, 1H(vector sign)(e(vector sign),e'p). The measurements have been carried out with the symmetric Bates Large Acceptance Spectrometer Toroid (BLAST). For values of Q2 between 0.15 and 0.85 (GeV/c)2, the combination of the two simultaneously measured spin-dependent asymmetries in the left and right sectors of BLAST provides the form factor ratio G_E^p G_M^p with high precision and minimal systematic errors. In these proceedings, we will present preliminary results from the BLAST program

[en] Differential cross sections for the neutron-proton bremsstrahlung np → npγ and pion production (np → npπ⁰ and np → ppπ^-) processes have been measured for the first time at the Los Alamos Neutron Science Center. A pulsed neutron beam, produced by 800MeV protons incident on a tungsten spallation target, bombarded a liquid hydrogen target. The outgoing neutrons and protons (in the first two reactions) or pairs of protons (in the third reaction) were observed in coincidence in organic liquid or plastic and CsI(pure) detectors at angles between 12 deg and 32 deg on opposite sides of the beam. For each pair of nucleon angles, the angular distribution of the unobserved photons or pions was deduced from the data

[en] The radiative neutron capture process plays an important role in Big Bang Nucleosynthesis (BBN) models. Recent measurements of the deuterium abundance in high-redshift hydrogen clouds have allowed a precise comparison of the light elemental abundances with BBN-model predictions. These measurements have also demonstrated the need for more precise cross section data. In particular there are very few measurements of the np?d? cross section in the energy region of interest to BBN, none of which cover the important energy range of 50-400 keV. Measurements of this cross section are being undertaken at the WNR facility of the Los Alamos Neutron Science Center (LANSCE)

[en] The MIT-Bates Compton Polarimeter, a laser back-scattering device, is used to measure the polarization of electron beams circulating in the South Hall Ring for a range of energies between 300 and 1000 MeV. The apparatus is described in detail and compared to other polarimeters operating within a similar energy region. Preliminary polarization results at 850 MeV are presented

[en] We report a precision measurement of the deuteron tensor analyzing powers T₂₀ and T₂₁ at the MIT-Bates Linear Accelerator Center. Data were collected simultaneously over a momentum transfer range Q=2.15-4.50 fm^-1 with the Bates Large Acceptance Spectrometer Toroid using a highly polarized deuterium internal gas target. The data are in excellent agreement with calculations in a framework of effective field theory. The deuteron charge monopole and quadrupole form factors G_C and G_Q were separated with improved precision, and the location of the first node of G_C was confirmed at Q=4.19±0.05 fm^-1. The new data provide a strong constraint on theoretical models in a momentum transfer range covering the minimum of T₂₀ and the first node of G_C.

[en] The roles played by mesons in the electromagnetic form factors of the nucleon are explored using as a basis a model containing vector mesons with coupling to the continuum together with the asymptotic Q² behavior of perturbative QCD. Specifically, the vector dominance model (GKex) developed by E. L. Lomon is employed, as it is known to be very successful in representing the existing high-quality data published to date. An analysis is made of the experimental uncertainties present when the differences between the GKex model and the data are expanded in orthonormal basis functions. A main motivation for the present study is to provide insight into how the various ingredients in this model yield the measured behavior, including discussions of when dipole form factors are to be expected or not, of which mesons are the major contributors, for instance, at low Q² or large distances, and of what effects are predicted from coupling to the continuum. Such insights are first discussed in momentum space, followed by an analysis of how different and potentially useful information emerges when both the experimental and theoretical electric form factors are Fourier transformed to coordinate space. While these Fourier transforms should not be interpreted as ''charge distributions,'' nevertheless the roles played by the various mesons, especially those which are dominant at large or small distance scales, can be explored via such experiment-theory comparisons.

[en] 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 Q² 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 existing cross-section data on elastic electron-proton scattering in the same Q² region

[en] The use of a clinical linac in photonuclear experiments is a novel concept. At Akdeniz University a program has been started focused on inducing photonuclear reactions with a Philips SLI-25 clinical linac. A bremsstrahlung photon beam produced by the linac is used to create radioactive nuclei. The decay of said nuclei is observed with a high-purity germanium detector. During the course of the experiment the spectrum of the irradiated sample is recorded. By analyzing the spectrum the energies of gamma-ray transitions in the daughter nuclei as well as the half-life of the parent nucleus are obtained. The results obtained thus far, starting with Zinc nuclei will be presented. (paper)

[en] The neutron-proton bremsstrahlung process (np→npγ) is known to be sensitive to meson exchange currents in the nucleon-nucleon interaction. The triply differential cross section for this reaction has been measured for the first time at the Los Alamos Neutron Science Center, using an intense, pulsed beam of up to 700-MeV neutrons to bombard a liquid hydrogen target. Scattered neutrons were observed at six angles between 12 deg. and 32 deg., and the recoil protons were observed in coincidence at 12 deg., 20 deg., and 28 deg. on the opposite side of the beam. Measurement of the neutron and proton energies at known angles allows full kinematic reconstruction of each event. The data are compared with predictions of two theoretical calculations, based on relativistic soft-photon and nonrelativistic potential models