Precision Beam Parameter Monitoring in a Measurement of the Weak Mixing Angle in Moeller Scattering

Technical Report · Mon Apr 11 00:00:00 EDT 2005

DOI:https://doi.org/10.2172/839851· OSTI ID:839851

Cooke, M S ^[1]

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1. SLAC

A precision measurement of the parity nonconserving left-right asymmetry, A{sub LR}, in Moeller scattering (e{sup -}e{sup -} {yields} e{sup -}e{sup -}) is currently in progress at the Stanford Linear Accelerator Center (SLAC). This experiment, labeled SLAC-E158, scatters longitudinally polarized electrons off atomic electrons in an unpolarized hydrogen target at a Q{sup 2} of 0.03 (GeV/c){sup 2}. The asymmetry, which is the fractional difference in the scattering cross-sections, measures the effective pseudo-scalar weak neutral current coupling, g{sub ee}, governing Moeller scattering. This quantity is in turn proportional to (1/4 - sin{sup 2} {theta}{sub w}), where {theta}{sub w} is the electroweak mixing angle. The goal is to measure the asymmetry to a precision of 1 x 10{sup -8} which corresponds to {delta}(sin{sup 2} {theta}{sub w}) {approx} 0.0007. Since A{sub LR} is a function of the cross-sections, and the cross-sections depend on the beam parameters, the desired precision of A{sub LR} places stringent requirements on the beam parameters. This paper investigates the requirements on the beam parameters and discusses the means by which they are monitored and accounted for.

• Research Organization: Stanford Linear Accelerator Center (SLAC), Menlo Park, CA
• Sponsoring Organization: SC
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 839851
• Report Number(s): SLAC-R-755
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
43 PARTICLE ACCELERATORS
ACCURACY
ASYMMETRY
CROSS SECTIONS
ELECTRONS
HYDROGEN
MOELLER SCATTERING
MONITORING
PARITY
SCATTERING
STANFORD LINEAR ACCELERATOR CENTER
TARGETS
WEAK NEUTRAL CURRENTS
WEINBERG ANGLE