Gudrid Moortgat-Pick (University of hamburg/DESY)
In order to match the precision requirements at the ILC both beams polarized have to be manipulated. In the talk a few aspects in this context are discussed, for instance, helicity flipping and spin tracking at the spin rotator, as well as, resonance depolarization via an RF kicker.
Dr Kurt Aulenbacher (Institut für Kernphysik, Univresität Mainz)
The P2 experiment at MESA requires sub-percent accuracy of the beam poalrization measurment. Several polarimeters will be needed to obtain a sufficient redundancy of the experiemnt. The two main polarimeters will be a double scattering device at low energy and a new type of Möller polarimeter. The latter can operate online directly in front of the experiment. The status of the two...
Moritz Beckmann (DESY)
At the planned International Linear Collider (ILC), the longitudinal beam polarization needs to be determined with an unprecedented precision. For that purpose, the beam delivery systems (BDS) are equipped with two laser Compton polarimeters each, which are foreseen to achieve a systematic uncertainty of 0.25 %. The polarimeters are located 1.6 km upstream and 150 m downstream of the e^+e^-...
11. Bremsstrahlung polarization correlations and their application for polarimetry of electron beams
Dr Stanislav Tashenov (Physikalisches Institut der Universität Heidelberg)
The angular distribution and linear polarization of bremsstrahlung photons is highly sensitive to the spin of the electrons in relativistic electron-atom collisions. While the former effect was well known, the latter one was observed only in the recent years. We report two experimental studies of linear photon polarization with spin-polarised electron beams at 100 keV and 2 MeV. In these...
3. Spin asymmetry in high-energy electron-nucleus scattering: bremsstrahlung versus elastic scattering
Dr Doris Jakubassa-Amundsen (Mathematics Institute, University of Munich)
The polarization correlations between the incident electron and an emitted bremssstrahlung photon as classified by Tseng and Pratt are extended into the high-energy regime where nuclear structure effects play a dominant role. While electron scattering from spin-zero nuclei is mostly governed by the finite-nuclear-size effects, nuclear bremsstrahlung and magnetic effects come into play when the...
2. Phenomenology and calculations for spin polarisation in high energy electron/positron storage rings
Prof. Desmond Barber (DESY)
The attainable equilibrium polarisation in electron/positron storage rings depends on a balance between polarisation build-up due to the Sokolov-Ternov effect and depolarisation resulting from the stochastic nature of the emission of photons in the synchrotron radiation. The rate of depolarisation rises faster with energy than the rate of polarisation, with the ratio scaling at least like the...
Sabine Riemann (DESY)
At the International Linear Collider (ILC) both beams --electrons and positrons-- will be polarized since the positron source is based on a helical undulator. The electron beam passes the undulator which is located at the end of the main linac. So the undulator parameters are strongly coupled to the centre-of-mass energy. The positron polarization has to be optimized for each energy ...
Andriy Ushakov (University of Hamburg)
The base-line positron source of the future International Linear Collider (ILC) is polarized and designed for an operation with electron drive beam energies between 150 GeV and 250 GeV (corresponding to 300 GeV up to 500 GeV CM energies). However, running at CM energies below 300 GeV reduces the positron yield substantially; running at Ecm = 1 TeV implies a low degree of positron...
Dr Mei Bai (Brookhaven National Lab)
Talk - 30 min
The discovery of Higgs has inspired the idea of dedicated higgs factory of high energy electron-‐positron collisions. Polarization can benefit the physics program not only as an efficient energy calibration, but lso suppress background signals. The experience from high energy electron beams at HERA and LEP has been encouraging, yet also exhibits the great difficulty. The aspect of reaching...
Mr Jan Schmidt (University of Bonn, Physics Institute, ELSA)
The new spin dynamics simulation suite POLE is designed to perform systematic studies of polarization in circular accelerators with fast energy ramps, or short storage times of up to some seconds. A main application is the investigation of crossing depolarizing resonances depending on arbitrary magnet and optics settings. For instance, many simulations of a single resonance crossing are...
Mr Fabian Nillius (Institut für Kernphysik)
Electron/photon tensor-correlation coefficients may allow to design a polarimeter that can measure all components of beam polarisation simultaneously ("vector polarimeter"). Besides its purpose as a beam diagnostic device this would also allow to test theoretical predictions for the correlation coefficients at energies between 1 and 3.5 MeV. As a first step we have set up a measurement of the...
Dr Anthony Hartin (DESY)
Depolarisation of polarised collider beams, due to the strong electromagnetic fields of the bunch-bunch collision at the IP, is important to understand for the precision physics goals of future e+e- colliders. Beam parameters are generally chosen to maximise the collision luminosity whilst minimising non-linear effects from strong IP fields. Here it will be shown that luminosity can be further...
Annika Vauth (DESY)
The physics program of the International Linear Collider requires precise knowledge of the luminosity weighted average polarisation at the electron-positron collision point. One crucial element of the ILC polarimetry concept is the use of Compton-Polarimeters measuring before and behind the collision point. It is foreseen to use Cherenkov detectors to measure the Compton scattered electrons...
Dr Friedrich Staufenbiel (DESY Zeuthen)
An intense polarized positron beam for future linear colliders can be produced using a high power beam of circularly polarized photons which penetrates a thin titanium-alloy target. The degree of polarization can be increased by cutting the outer part of the photon beam generated in a helical undulator using a collimator in front of the target. However, the photon beam induces substantial heat...
Matthias Molitor (Johannes Gutenberg Universität Mainz)
Talk - 30 min
The new Mainzer Energy recovering Superconduting Accelerator (MESA) will be used for high precision measurement of the Weinberg angle at low Q². In order to be able to measure as precise as desired, the polarisation of the incident electron beam has be know with very low uncertainty. Therefore a Double Scattering Polarimeter (DSP) will be installed at MESA at low energies. In my talk I will...