480 research outputs found
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 Pb in mean field models
We study whether the neutron skin thickness of 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 of 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 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
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 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
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~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, , with to precisely measure the leading twist
chiral-odd and -odd quark distribution and fragmentation functions in SIDIS.
The large 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
- …