First Observation of the Parity Violating Asymmetry in Moller Scattering

Younus, Imran ; U., /Syracuse

Stanford Linear Accelerator Center

关键词: Parity;    Calorimetry;    Quartz;    Forecasting;    Fibers;   

DOI  :  10.2172/878885
RP-ID  :  SLAC-R-768
RP-ID  :  AC02-76SF00515
RP-ID  :  878885

美国|英语

来源: UNT Digital Library

【 摘 要 】

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).