Parity violation in the elastic scattering of polarized electrons from sup 12 C at 250 MeV
Measurements of the parity violating asymmetry in the differential cross section for elastic scattering of polarized electrons from {sup 12}C at 250 MeV energy and 150 MeV/c momentum transfer are reported. The experiment is performed at the Bates Linear Accelerator Center. The systematic errors include electronic pickup, transverse polarization, nuclear structure, systematics in the laser system used to produce polarized electrons, and residual systematics associated with beam parameters. The dominant one was electronic pickup and the next most important one was helicity correlated energy changes. Developments which extended the lifetime of the polarized electron source were of vital importance. The author's present measured asymmetry is {sigma}{sub R}{minus}{sigma}{sub L}/{sigma}{sub R}+{sigma}{sub L} = 0.87 {plus minus} 0.65 (stat.) {plus minus} 0.38 (syst.) {times} 10{sup {minus}6} where {sigma}{sub R(L)} is the differential cross section for right (left) handed electrons. This result was achieved in a data taking time of about two days. The standard model prediction for this electroweak interference effect is 0.68 ppm for the case where the electron polarization was 38%. With the present understanding of systematic errors it should be possible with adequate running time to achieve a precision of about 0.1 ppm in the measurement of the asymmetry.
- Research Organization:
- Yale Univ., New Haven, CT (United States)
- OSTI ID:
- 5244844
- Country of Publication:
- United States
- Language:
- English
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A=6-19
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCELERATORS
ASYMMETRY
CARBON 12 TARGET
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
ELASTIC SCATTERING
ELECTRON REACTIONS
ENERGY RANGE
ERRORS
INVARIANCE PRINCIPLES
LEPTON REACTIONS
LINEAR ACCELERATORS
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 100-1000
MOMENTUM TRANSFER
NUCLEAR REACTIONS
NUCLEAR STRUCTURE
P INVARIANCE
PARTICLE MODELS
SCATTERING
STANDARD MODEL
TARGETS
UNIFIED GAUGE MODELS