First Observation of the Parity Violating Asymmetry in Moller Scattering

Technical Report · Wed Jul 06 04:00:00 EDT 2005

DOI:https://doi.org/10.2172/878885· OSTI ID:878885

Younus, Imran

This thesis reports on the E158 experiment at Stanford Linear Accelerator Center (SLAC), which has made the first observation of the parity non-conserving asymmetry in Moller scattering. Longitudinally polarized 48 GeV electrons are scattered off unpolarized (atomic) electrons in a liquid hydrogen target with an average Q{sup 2} of 0.027 GeV{sup 2}. The asymmetry in this process is proportional to (1/4 - sin{sup 2}{theta}{sub W}), where sin{sup 2} {theta}{sub W} gives the weak mixing angle. The thesis describes the experiment in detail, with a particular focus on the design and construction of the electromagnetic calorimeter. This calorimeter was the primary detector in the experiment used to measure the flux of the scattered Moller electrons and eP electrons. It employed the quartz fiber calorimetry technique, and was built at Syracuse University. The preliminary results from the first experimental data taken in spring 2002 give A{sub PV} = -151.9 {+-} 29.0(stat) {+-} 32.5(syst) parts per billion. This in turn gives sin{sup 2} {theta}{sub W} = 0.2371 {+-} 0.0025 {+-} 0.0027, which is consistent with the Standard Model prediction (0.2386 {+-} 0.0006).

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 878885
• Report Number(s): SLAC-R-768
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
43 PARTICLE ACCELERATORS
ASYMMETRY
CALORIMETERS
CALORIMETRY
CONSTRUCTION
DESIGN
ELECTRONS
Experiment-HEP
HEPEX
FIBERS
FORECASTING
HYDROGEN
PARITY
QUARTZ
SCATTERING
STANDARD MODEL
STANFORD LINEAR ACCELERATOR CENTER
TARGETS