Measurement of target and double-spin asymmetries for the (e)over-right-arrow (p)over-right-arrow -\u3e e pi(+)(n) reaction in the nucleon resonance region at low Q(2)

We report measurements of target- and double-spin asymmetries for the exclusive channel (e) over right arrow (p) over right arrow - \u3e ep(+)(n) in the nucleon resonance region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These asymmetries were extracted from data obtained using a longitudinally polarized NH3 target and a longitudinally polarized electron beam with energies 1.1, 1.3, 2.0, 2.3, and 3.0 GeV. The new results are consistent with previous CLAS publications but are extended to a low Q(2) range from 0.0065 to 0.35 (GeV/c)(2). The Q(2) access was made possible by a custom-built Cherenkov detector that allowed the detection of electrons for scattering angles as low as 6 degrees. These results are compared with the unitary isobar models JANR and MAID, the partial-wave analysis prediction from SAID, and the dynamic model DMT. In many kinematic regions our results, in particular results on the target asymmetry, help to constrain the polarization-dependent components of these models

Measurement of target and double-spin asymmetries for the e→p→eπ+(n) reaction in the nucleon resonance region at low Q(2)

We report measurements of target- and double-spin asymmetries for the exclusive channel $\vec e\vec p\to e\pi^+ (n)$ in the nucleon resonance region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These asymmetries were extracted from data obtained using a longitudinally polarized NH$_3$ target and a longitudinally polarized electron beam with energies 1.1, 1.3, 2.0, 2.3 and 3.0 GeV. The new results are consistent with previous CLAS publications but are extended to a low $Q^2$ range from $0.0065$ to $0.35$ (GeV$/c$)$^2$. The $Q^2$ access was made possible by a custom-built Cherenkov detector that allowed the detection of electrons for scattering angles as low as $6^\circ$. These results are compared with the unitary isobar models JANR and MAID, the partial-wave analysis prediction from SAID and the dynamic model DMT. In many kinematic regions our results, in particular results on the target asymmetry, help to constrain the polarization-dependent components of these models.Comment: 20 pages, 15 figures, to appear in Phys. Rev.

Measurements of the electron-helicity dependent cross sections of deeply virtual compton scattering with CEBAF at 12 GeV

Jefferson Lab PAC-30 proposal. 43 pages, 13 figures - Proposition d'expérienceWe propose precision measurements of the helicity-dependent and helicity independent cross sections for the ep->epg reaction in Deeply Virtual Compton Scattering (DVCS) kinematics. DVCS scaling is obtained in the limits Q^2>>Lambda_{QCD}^2, x_Bj fixed, and -\Delta^2=-(q-q')^22 GeV, and -\Delta^21 GeV^2. We will use our successful technique from the 5.75 GeV Hall A DVCS experiment (E00-110). With polarized 6.6, 8.8, and 11 GeV beams incident on the liquid hydrogen target, we will detect the scattered electron in the Hall A HRS-L spectrometer (maximum central momentum 4.3 GeV/c) and the emitted photon in a slightly expanded PbF_2 calorimeter. In general, we will not detect the recoil proton. The H(e,e'g)X missing mass resolution is sufficient to isolate the exclusive channel with 3% systematic precision

E12-10-006: An update to PR12-09-014: Target Single Spin Asymmetry in Semi-Inclusive Deep-Inelastic (e, e′π±) Reaction on a Transversely Polarized 3He Target at 8.8 and 11 GeV.

We propose to carry out precision measurements of Single target Spin Asymmetries (SSA) from semi-inclusive electroproduction of charged pions from a 40-cm long transversely polarized 3He target in Deep-Inelastic-Scattering kinematics using 11 and 8.8 GeV electron beams. We propose to carry out this coincidence experiment in Hall A with a newly proposed solenoid spectrometer (SoLID) and the Hall A polarized 3He target. The full 2π azimuthal angular coverage on the φS angle and large azimuthal angular coverage on the φh angle are essential in controlling the systematic uncertainties in extracting different asymmetries. The proposed experiment will provide precise 4-D (x, z, PT and Q2) data on the Collins, Sivers and Pretzelosity asymmetries for the neutron through the azimuthal angular dependence