Measurement of the Vector and Tensor Asymmetries at Large Missing Momentum in Quasielastic (e[over →],e

We report the measurement of the beam-vector and tensor asymmetries A_{ed}^{V} and A_{d}^{T} in quasielastic (e[over →],e^{'}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

The overlap of the EBA and the MT/V5 cluster.

The extrastriate body area (EBA) is located in the lateral occipito-temporal cortex, in the vicinity of the motion-sensitive region hMT/V5+. To investigate the relationship of EBA to the recently mapped retinotopic areas of the MT/V5 cluster (Kolster et al., 2010), we evaluated the proportion of voxels responsive to the presentation of static human bodies (EBA voxels) in each of the four areas of the MT/V5 cluster and neighboring LO and phPIT areas. We evaluated this proportion as both a function of the number of voxels in a given area and the total number of voxels in a broader lateral occipito-temporal cortex (LOTC) ROI. We observed that each of the four retinotopic areas of the MT/V5 cluster includes substantial fractions of EBA voxels, in contrast to the LO and phPIT areas. This proportion was slightly greater in the right than left hemisphere, and did not depend on the control condition. While most EBA voxels in MT/V5 were only body-sensitive, those in pMSTv and pFST were also motion-sensitive. The main locus of EBA voxels outside the MT/V5 cluster was in the LOTC cortex just rostral to the MT/V5 cluster. Although this region contained more EBA voxels than the MT/V5 cluster, the proportion as a function of areal size was much reduced compared to the MT/V5 cluster. Our results show that EBA is not a single cortical area as EBA voxels are located in all four areas of the MT/V5 cluster, and that body-sensitivity is a key feature of the MT/V5 cluster, in keeping with its exquisite sensitivity to observed actions of others.

Precise measurement of deuteron tensor analyzing powers with BLAST.

We report a precision measurement of the deuteron tensor analyzing powers T(20) and T(21) 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 T(20) and the first node of G(C).

Charge form factor of the neutron at low momentum transfer from the 2H-->(e-->,e'n)1H reaction.

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 GEn/GMn was extracted from the beam-target vector asymmetry AedV at four-momentum transfers Q2=0.14, 0.20, 0.29, and 0.42 (GeV/c)2.

-Measurement of the proton's electric to magnetic form factor ratio from 1H(over -->)(e(over -->),e'p).

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.

Spin-dependent electron-proton scattering in the Delta-excitation region.

We report on measurements of the cross section and provide first data on spin correlation parameters A(TT') and A(TL') in inclusive scattering of longitudinally polarized electrons from nuclear-polarized hydrogen. Polarized electrons were injected into an electron storage ring operated at a beam energy of 720 MeV. Polarized hydrogen was produced by an atomic beam source and injected into an open-ended cylindrical cell, located in the electron storage ring. The four-momentum transfer squared ranged from Q2 = 0.2 GeV(2)/c(2) at the elastic scattering peak to Q2 = 0.11 GeV(2)/c(2) at the Delta(1232) resonance. The data provide a stringent test of pion electroproduction models.

Spin-momentum correlations in quasielastic electron scattering from deuterium.

The spin-momentum correlation parameter A(V)(ed) was measured for the 2H-->(e-->,e'p)n reaction for missing momenta up to 350 MeV/c at Q2 = 0.21 (GeV/c)(2) for quasielastic scattering of polarized electrons from vector-polarized deuterium. The data give detailed information about the deuteron spin structure and are in good agreement with the results of microscopic calculations based on realistic nucleon-nucleon potentials and including various spin-dependent reaction mechanism effects. The experiment reveals in a most direct manner the effects of the D state in the deuteron ground-state wave function and shows the importance of isobar configurations for this reaction.