3 research outputs found
Design and Construction of a Longitudinally Polarized Solid Nuclear Target for CLAS12
A new polarized nuclear target has been developed, constructed, and deployed at Jefferson Laboratory in Newport News, VA for use with the upgraded 12 GeV CEBAF (Continuous Electron Beam Accelerator Facility) accelerator and the Hall B CLAS12 (12 GeV CEBAF Large Acceptance Spectrometer) detector array. This āAPOLLOā (Ammonia POLarized LOngitudinally) target is a longitudinally polarized, solid ammonia, nuclear target which employs DNP (Dynamic Nuclear Polarization) to induce a net polarization in samples of protons (NH3) and deuterons (ND3) cooled to 1K via helium evaporation, held in a 5T polarizing field supplied by the CLAS12 spectrometer, and irradiated with 140 GHz microwave radiation. It was utilized in the RGC (Run Group C) experiment suite through a collaboration of the JLab Target Group, Old Dominion University, Christopher Newport University, the University of Virginia, and the CLAS Collaboration. RGC comprised six experiments which measured multiple spin-dependent observables across a wide kinematic phase space for use in nucleon spin studies. The dimensional constraints necessary for the incorporation of APOLLO into CLAS12, as well as the considerations necessary to utilize the CLAS12 solenoid, introduced unique challenges to the target design. This document presents the innovative solutions developed for these challenges including a novel material transport system, superconducting magnetic correction coils, and an all new bespoke NMR (Nuclear Magnetic Resonance) system. In addition to a detailed description of the complete target system and an initial report of the RGC experimental run, it will also present a study of Quark-Hadron Duality in the g1 spin structure function based on Hall B EG1b data and pQCD fits from the JAM (Jefferson Lab Angular Momentum) Collaboration
Polarized Structure Function Ļ\u3csub\u3eLT\u27\u3c/sub\u3e from ā°p Electroproduction Data in the Resonance Region at 0.2 GeVĀ² \u3c QĀ² \u3c 1.0 GeVĀ²
The first results on the ĻLTā² structure function in exclusive Ļ0p electroproduction at invariant masses of the final state of 1.5GeV \u3c W \u3c 1.8 GeV and in the range of photon virtualities 0.4 GeV2 \u3c Q2 \u3c 1.0 GeV2 were obtained from data on beam spin asymmetries and differential cross sections measured with the CLAS detector at Jefferson Lab. The Legendre moments determined from the ĻLTā² structure function have demonstrated sensitivity to the contributions from the nucleon resonances in the second and third resonance regions. These new data on the beam spin asymmetries in Ļ0p electroproduction extend the opportunities for the extraction of the nucleon resonance electro-excitation amplitudes in the mass range above 1.6 GeV
Detailed Study of Quark-Hadron Duality in Spin Structure Functions of the Proton and Neutron
In this paper, we present for the first time comprehensive and detailed
results on the correspondence between the extrapolated deep inelastic structure
function of both the proton and the neutron with the same quantity
measured in the nucleon resonance region. We use a QCD parameterization of the
world data on DIS spin structure functions, extrapolated into the nucleon
resonance region and averaged over various intervals in the scaling variable
. We compare the results with the large data set collected in the
quark-hadron transition region by the CLAS collaboration, averaged over the
same intervals. We present this comparison as a function of the momentum
transfer . We find that, depending on the averaging interval and the
minimum momentum transfer chosen, a clear transition to quark-hadron duality
can be observed in both nucleon species. Furthermore, we show, for the first
time, the scaling behavior of measured in the resonance region at
sufficiently high momentum transfer. Our results can be used to quantify the
deviations from the applicability of pQCD for data taken at moderate energies,
and help with extraction of quark distribution functions from such data.Comment: to be submitted to Phys. Rev.