Precision measurement of the neutron spin dependent structure functions

Technical Report · Sat Feb 01 04:00:00 EST 1997

DOI:https://doi.org/10.2172/485989· OSTI ID:485989

Kolomensky, Y G

In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g{sub 1}{sup n} (x, Q{sup 2}) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized {sup 3}He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014 {le} x {le} 0.7 with an average Q{sup 2} of 5 GeV{sup 2}. The author reports the integral of the spin dependent structure function in the measured range to be {integral}{sub 0.014}{sup 0.7} dx g{sub 1}{sup n}(x, 5 GeV{sup 2}) = {minus}0.036 {+-} 0.004(stat.) {+-} 0.005(syst.). The author observes relatively large values of g{sub 1}{sup n} at low x that call into question the reliability of data extrapolation to x {r_arrow} 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. The author performs a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin dependent structure functions g{sub 1}{sup p} and g{sub 1}{sup n} paying careful attention to the experimental and theoretical uncertainties. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, the author evolves the data to Q{sup 2} = 5 GeV{sup 2}, determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 485989
• Report Number(s): SLAC-R--503; ON: DE97006539
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ELECTRON REACTIONS
GEV RANGE 10-100
HELIUM 3 TARGET
NEUTRONS
POLARIZED BEAMS
POLARIZED TARGETS
SPIN
STRUCTURE FUNCTIONS