Speaker
Karim Laihem
(Institut fuer Hochenergiephysik Zeuthen)
Description
The full exploitation of the physics potential of an International Linear Collider
(ILC), will require the development of polarized positron beams. Having both
positron and electron beams polarized will be a decisive improvement for
many physics studies in the linear collider, providing new insight into
structures of couplings and thus access to the physics beyond the standard
model. The concepts discussed for a polarized positron source are based on
circularly polarized photon sources. 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 Compton transmission polarimetry. 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 experimental
confirmation, the helical undulator method became a preferred candidate for
an ILC polarized positron source.
Author
Karim Laihem
(Institut fuer Hochenergiephysik Zeuthen)
Co-author
Collaboration E166
(E166)
