Köln 2004 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
PV: Plenarvorträge
PV X
PV X: Plenarvortrag
Dienstag, 9. März 2004, 11:30–12:00, P
Double–polarization experiments with 3He at MAMI — •Daniela Rohe — Department für Physik, Universität Basel
In double–polarized experiments of the kind 3He→(e→,e′N) one measures not cross sections but asymmetries with respect to the helicity of the electron beam. Asymmetries are much more sensitive to small quantities like the form factor of the neutron, Gen, and the D-state component in the wave function of 3He→. In the first case polarized 3He→ serves as a polarized neutron target, because the proton spins being in a S–state couple to zero. An averaged target polarization of ≈ 50 % during the beam time was achieved. The electron beam polarization at MAMI was measured with a Moeller polarimeter to ≈ 80 %.
Theoretically electron scattering at polarized 3He→ is well understood by Faddeev calculations for small Q2 (< 0.4 (GeV/c)2) below the pion threshold. Recently, calculations with a limited treatment of FSI and relativistic effects became available and have been confirmed with additional measurements. This allows for correcting Gen at Q2 of 0.67 (GeV/c)2.