Conference summary

A perspective on the PAVI11 conference is given

Twist-four Corrections to Parity-Violating Electron-Deuteron Scattering

Parity violating electron-deuteron scattering can potentially provide a clean access to electroweak couplings that are sensitive to physics beyond the Standard Model. However hadronic effects can contaminate their extraction from high-precision measurements. Power-suppressed contributions are one of the main sources of uncertainties along with charge-symmetry violating effects in leading-twist parton densities. In this work we calculate the twist-four correlation functions contributing to the left-right polarization asymmetry making use of nucleon multiparton light-cone wave functions.Comment: 12 pages, 3 figure

Study of the neutron skin thickness of 208{}^{208}Pb in mean field models

We study whether the neutron skin thickness $\Delta r_{np}$ of ${}^{208}$Pb originates from the bulk or from the surface of the neutron and proton density distributions in mean field models. We find that the size of the bulk contribution to $\Delta r_{np}$ of ${}^{208}$Pb strongly depends on the slope of the nuclear symmetry energy, while the surface contribution does not. We note that most mean field models predict a neutron density for ${}^{208}$Pb between the halo and skin type limits. We investigate the dependence of parity- violating electron scattering at the kinematics of the PREX experiment on the shape of the nucleon densities predicted by the mean field models for ${}^{208}$Pb. We find an approximate formula for the parity-violating asymmetry in terms of the central radius and the surface diffuseness of the nucleon densities of ${}^{208}$Pb in these models.Comment: 5 pages, 2 figures, proceedings MBC 2011 - Many body correlations from dilute to dense nuclear systems - IHP PARI

Do we understand the incompressibility of neutron-rich matter?

The ``breathing mode'' of neutron-rich nuclei is our window into the incompressibility of neutron-rich matter. After much confusion on the interpretation of the experimental data, consistency was finally reached between different models that predicted both the distribution of isoscalar monopole strength in finite nuclei and the compression modulus of infinite matter. However, a very recent experiment on the Tin isotopes at the Research Center for Nuclear Physics(RCNP) in Japan has again muddled the waters. Self-consistent models that were successful in reproducing the energy of the giant monopole resonance (GMR) in nuclei with various nucleon asymmetries (such as 90Zr, 144Sm, and 208Pb) overestimate the GMR energies in the Tin isotopes. As important, the discrepancy between theory and experiment appears to grow with neutron excess. This is particularly problematic as models artificially tuned to reproduce the rapid softening of the GMR in the Tin isotopes become inconsistent with the behavior of dilute neutron matter. Thus, we regard the question of ``why is Tin so soft?'' as an important open problem in nuclear structure.Comment: 12 pages, 3 figures, and 1 table. Submitted to the "Focus issue on Open Problems in Nuclear Structure", Journal of Physics

A high-finesse Fabry-Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

A high-finesse Fabry-Perot cavity with a frequency-doubled continuous wave green laser (532~nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064~nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO$_{3}$ crystal. The maximum achieved green power at 5 W IR pump power is 1.74 W with a total conversion efficiency of 34.8\%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7~kW with a corresponding enhancement of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7\%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0\% precision in polarization measurements of an electron beam with energy and current of 1.0~GeV and 50~$\mu$A.Comment: 20 pages, 22 figures, revised version of arXiv:1601.00251v1, submitted to NIM

Transversity and Transverse Spin in Nucleon Structure through SIDIS at Jefferson Lab

The JLab 12 GeV upgrade with a proposed solenoid detector and the CLAS12 detector can provide the granularity and three-dimensional kinematic coverage in longitudinal and transverse momentum, $0.1\le x \le 0.5$, $0.3 \le z \le 0.7$ with $P_T \le 1.5 {\rm GeV}$ to precisely measure the leading twist chiral-odd and $T$-odd quark distribution and fragmentation functions in SIDIS. The large $x$ experimental reach of these detectors with a 12 GeV CEBAF at JLab makes it {\em ideal} to obtain precise data on the {\em valence-dominated} transversity distribution function and to access the tensor charge.Comment: 7 Pages, 2 figures. Summary of the working group on Transversity and Transverse Spin Physics, from the workshop, "Inclusive and Semi-Inclusive Spin Physics with High Luminosity and LargeAcceptance at 11 GeV", Thomas Jefferson National Accelerator Facility (JLAB), December 13-14, 2006, Jefferson Lab, Newport News, VA USA. Serves as input for the Nuclear Physics Long Range Plan on QCD and Hadron Physic

Flux profile scanners for scattered high-energy electrons

The paper describes the design and performance of flux integrating Cherenkov scanners with air-core reflecting light guides used in a high-energy, high-flux electron scattering experiment at the Stanford Linear Accelerator Center. The scanners were highly radiation resistant and provided a good signal to background ratio leading to very good spatial resolution of the scattered electron flux profile scans.Comment: 22 pages, 17 figure