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Nucleon spin structure functions from HERMES: The first year

Conference ·
OSTI ID:434912
HERMES, {und HE}RA {und Me}asurement of {und S}pin, is a second generation exper to study the spin structure of the nucleon by using polarized internal gas targets in the HERA 28 GeV electron storage ring. Scattered positrons and coincident hadrons are detected in an open geometry spectrometer which includes particle identification. Inclusive data with polarized {sup 3}He give the spin structure function {ital g{sup n}{sub 1}(x)} and the Ellis-Jaffe integral RR{Lambda} = {integral}{sub 0}{sup 1} {ital g{sup n}{sub 1}(x)dx} for the neutron. The semi-inclusive spin asymmetries are a unique and sensitive probe of the flavor dependence of quark helicity distributions and properties of the quark sea. Data taken in 1995 with unpolarized hydrogen and deuterium targets provide measurements of the flavor distributions of sea and valence quarks. In a preliminary analysis, {Lambda}{sup {ital n}}{sub 1} = -0.032{+-}0. 013{sub {ital stat.}} {+-} O.017{sub {ital syst.}} is obtained at Q{sup 2} = 3(GeV/c){sup 2} for the Ellis-Jaffe integral.
Research Organization:
Argonne National Lab., IL (United States)
Sponsoring Organization:
USDOE Office of Energy Research, Washington, DC (United States)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
434912
Report Number(s):
ANL/PHY/CP--91683; CONF-9607177--1; ON: DE97001155
Country of Publication:
United States
Language:
English

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