We have performed precision measurements of the double-spin virtual-photon asymmetry A1 on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer and a longitudinally and transversely polarized 3He target. Our data cover a wide kinematic range 0.277≤x≤0.548 at an average Q2 value of 3.078 (GeV/c)2, doubling the available high-precision neutron data in this x range. We have combined our results with world data on proton targets to make a leading-order extraction of the ratio of polarized-to-unpolarized parton distribution functions for up quarks and for down quarks in the same kinematic range. Our data are consistent with a previous observation of an A1n zero crossing near x=0.5. We find no evidence of a transition to a positive slope in (δd+δd-)/(d+d-) up to x=0.548.
|Number of pages||6|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - May 1 2015|
Bibliographical noteFunding Information:
We gratefully acknowledge the outstanding support of the Jefferson Lab Accelerator Division and Hall A staff in bringing this experiment to a successful conclusion. This material is based upon work supported by the U.S. Department of Energy , Office of Science, Office of Nuclear Physics, under Award Numbers DE-FG02-87ER40315 and DE-FG02-94ER40844 and Contract DE-AC05-06OR23177 , under which the Jefferson Science Associates, LLC, operate Jefferson Lab.
© 2015 The Authors.
- Nucleon structure
- Parton distribution functions
- Polarized electron scattering
- Spin structure functions
ASJC Scopus subject areas
- Nuclear and High Energy Physics