Speaker
Description
Polarised beams are indispensable for many experiments in particle, atomic
and nuclear physics where spin-dependent processes are to be studied. Unlike
RF accelerators, Laser-Plasma-Accelerators (LPA) are not limited by material
breakdown and can therefore support thousand times higher accelerating fields,
which make them a promising alternative to conventional accelerators.
The LEAP (Laser Electron Acceleration with Polarisation) project at DESY aims
to generate and measure spin-polarised electron beams from a compact LPA for
the first time.
Spin-polarised electron beams can be generated from an LPA by employing a
pre-polarised plasma source, where hydrogen halide molecules are dissociated
by a circularly polarised UV laser pulse. For the subsequent polarisation mea-
surement photon transmission polarimetry will be used due to the expected
beam energy of tens of MeVs. The basic concept is to pass circularly polarised
gamma rays generated by bremsstrahlung of the longitudinally polarised elec-
trons through a magnetised iron absorber, where the transmission is spin depen-
dent. The transmission asymmetry with respect to the magnetisation direction
is proportional to the initial electron polarisation, which can be measured with a
calorimeter. This poster provides an overview of the LEAP project, the physics
of polarised LPA and experimental progress.
