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Strange content of the nucleon: asymmetry measurement of parity violation in the PVA4 experiment at MAMI (Mainzer Mikrotron); Contenu etrange du nucleon: mesure de l'asymetrie de violation de parite dans l'experience PVA4 a MAMI. Etude et developpement d'un polarimetre optique

Abstract

Nucleons are bound states of three valence quarks (up and down quarks) surrounded by a sea of gluons and quark pairs (mainly up, down and strange quarks). The PVA4 experiment (Parity Violation in hall A4) aims at determining at MAMI (Mainzer Mikrotron) the contribution of the ss pairs to the electric charge and magnetic moment of the nucleon. This requires the extraction of information from the weak coupling in the elastic scattering of polarized electrons off target protons. The parity non-conserving Z{sup 0} exchange leads to a parity violating asymmetry in the count rates for left and right helicity states. Comparison of the measured asymmetry to the predictions of the Standard Model allows then to extract the strange content of the proton. The success of the experiment essentially lies in the ability of controlling the beam parameters and evaluating the physical background. For this purpose, a Monte Carlo simulation has been developed: it simulates the PVA4 electron-proton scattering (including geometry and detection) for different processes (elastic scattering and pion electroproduction) thus allowing to correct the experimental asymmetry from physical background processes. In addition, an optical polarimeter has been developed to get a precise, on-line and fast measurement of the electron  More>>
Authors:
Publication Date:
Nov 01, 2002
Product Type:
Thesis/Dissertation
Report Number:
IPNO-T-02-04
Resource Relation:
Other Information: TH: These sciences; 153 refs; PBD: Nov 2002
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASYMMETRY COEFFICIENTS; COMPUTERIZED SIMULATION; DATA ANALYSIS; DATA COVARIANCES; DIFFERENTIAL CROSS SECTIONS; ELECTRON BEAMS; ELECTRON-PROTON INTERACTIONS; FORM FACTORS; MICROTRONS; MONTE CARLO METHOD; P INVARIANCE; PROTONS; RADIATIVE CORRECTIONS; STRANGENESS
OSTI ID:
20462975
Research Organizations:
Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR0300273040294
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
175 pages
Announcement Date:
May 28, 2004

Citation Formats

Blaise, C. Strange content of the nucleon: asymmetry measurement of parity violation in the PVA4 experiment at MAMI (Mainzer Mikrotron); Contenu etrange du nucleon: mesure de l'asymetrie de violation de parite dans l'experience PVA4 a MAMI. Etude et developpement d'un polarimetre optique. France: N. p., 2002. Web.
Blaise, C. Strange content of the nucleon: asymmetry measurement of parity violation in the PVA4 experiment at MAMI (Mainzer Mikrotron); Contenu etrange du nucleon: mesure de l'asymetrie de violation de parite dans l'experience PVA4 a MAMI. Etude et developpement d'un polarimetre optique. France.
Blaise, C. 2002. "Strange content of the nucleon: asymmetry measurement of parity violation in the PVA4 experiment at MAMI (Mainzer Mikrotron); Contenu etrange du nucleon: mesure de l'asymetrie de violation de parite dans l'experience PVA4 a MAMI. Etude et developpement d'un polarimetre optique." France.
@misc{etde_20462975,
title = {Strange content of the nucleon: asymmetry measurement of parity violation in the PVA4 experiment at MAMI (Mainzer Mikrotron); Contenu etrange du nucleon: mesure de l'asymetrie de violation de parite dans l'experience PVA4 a MAMI. Etude et developpement d'un polarimetre optique}
author = {Blaise, C}
abstractNote = {Nucleons are bound states of three valence quarks (up and down quarks) surrounded by a sea of gluons and quark pairs (mainly up, down and strange quarks). The PVA4 experiment (Parity Violation in hall A4) aims at determining at MAMI (Mainzer Mikrotron) the contribution of the ss pairs to the electric charge and magnetic moment of the nucleon. This requires the extraction of information from the weak coupling in the elastic scattering of polarized electrons off target protons. The parity non-conserving Z{sup 0} exchange leads to a parity violating asymmetry in the count rates for left and right helicity states. Comparison of the measured asymmetry to the predictions of the Standard Model allows then to extract the strange content of the proton. The success of the experiment essentially lies in the ability of controlling the beam parameters and evaluating the physical background. For this purpose, a Monte Carlo simulation has been developed: it simulates the PVA4 electron-proton scattering (including geometry and detection) for different processes (elastic scattering and pion electroproduction) thus allowing to correct the experimental asymmetry from physical background processes. In addition, an optical polarimeter has been developed to get a precise, on-line and fast measurement of the electron beam polarization. The optical polarimeter (POLO) is based on the collision of polarized electrons on atoms such that spin angular momentum is transferred to the excited atoms, which subsequently decays by emitting a circularly polarized fluorescence. The degree of circular polarization is directly related to the electron polarization. Analyzing the fluorescence's Stokes parameters is equivalent to a measurement of the electron beam polarization. (author)}
place = {France}
year = {2002}
month = {Nov}
}