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 An1 zero crossing near x = 0.5. We find no evidence of a transition to a positive slope in ( d + d¯)/(d + d¯) up to x = 0.548.

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Published in Physics Letters B, v. 744, p. 309-314.

© 2015 The Authors. Published by Elsevier B.V.

This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.

This work is a creation of the Jefferson Lab Hall A Collaboration. Due to the large number of authors involved, only the first 10 and the ones affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit the following link: http://dx.doi.org/10.1103/PhysRevC.90.055209

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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.