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HK: Hadronen und Kerne
HK 61: Electromagnetic Probes VIII, Properties of Nucleon, Pion
HK 61.4: Gruppenbericht
Donnerstag, 19. März 1998, 15:30–16:00, B
Measurement of the electric form factor of the neutron in the reaction D(e→,e′n→)p * — •C. Herberg — Institut für Kernphysik, Universität Mainz
The electric form factor of the neutron, GE,n, has been determined at the Mainzer Microtron MAMI in the two reactions 3He→(e→,e′n)pp and D(e→,e′n→)p. Here the measurement of the neutron recoil polarisation in the exclusive quasielastic scattering of longitudinally polarized electrons off unpolarised deuterons at Q2=0.4 GeV2/c2 and Q2=0.15 GeV2/c2 will be reported.
The ejected neutrons were detected in a polarimeter consisting of two walls of plastic scintillators. The neutron detection process itself provides analysing power leading to a measured azimuthal asymmetry in the np- or nC-scattering in the first scintillator wall which is proportional to the polarisation of the neutron. Precession of the neutron spin in a large dipole magnet in front of the neutron detectors allows the form factor ratio GE,n/GM,n to be extracted from the ratio of transverse to longitudinal polarisation Px/Pz independently of the absolute values of the beam polarisation and the analysing power of the polarimeter.
Analysis and results of this measurement will be presented and the influence of binding effects on the extracted value of GE,n will be discussed.
* supported by SFB (201), BMBF (06TU669) and SERC