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T: Teilchenphysik
T 410: Beschleuniger III
T 410.5: Group Report
Wednesday, March 29, 2006, 17:30–17:50, C2-03-527
Development of a polarized positron source for the ILC. — •K. Laihem1, H. Kolanoski2, and A. Stahl3 — 1DESY — 2HU Berlin. — 3RWTH Aachen.
The full exploitation of the physics potential of an International Linear Collider (ILC), will require the development of polarized positron beams. Having both e+ and e- beams polarized in the linear collider will be a decisive improvement for many physics studies, providing new insight into structures of couplings and thus access to the physics beyond the standard model. The concept of a polarized positron source is based mainly on the development of a circular polarized photon source. Those photons are then converted in a relatively thin target to generate longitudinally polarized positrons and electrons. Two different approaches have been developed to test for the first time a polarized positron source. While in an experiment at KEK a Compton back scattering is used, the E166 experiment uses a one meter long helical undulator in a 46.6 GeV electron beam to produce MeV photons with a hight degree of circular polarization at 8.3 MeV. Beside the development of the helical undulator, the most challenging part in E166 is to measure the positron polarization using the Compton transmission polarimeter. The expected asymmetries for both photons and positrons are about 3.4% and 1% respectively. The E166 experiment had two successful run periods in June and September 2005. The data analysis shows an asymmetry in the expected range for both photons and positrons.With this observed asymmetries the helical undulator method became a preferred candidate for an ILC polarized positron source.