267 research outputs found
Prototype for an Undulator-based Source for Polarised Positrons: International Polarised Positron Collaboration: Project E-166
The full exploitation of the physics potential of a future Linear Collider
requires the development of polarised positron beams. A very promising scheme
for the technical realisation is the use of helical undulators, generating
circular polarised photons of several MeV which are then converted in a thin
target to longitudinally polarised positrons. The experiment E-166 tests this
scheme. It uses the low-emittance 50-GeV electron beam at the Final Focus Test
Beam (FFTB) at SLAC, passing through a 1 meter-long helical undulator. The flux
and polarisation of the undulator photons as well as the properties of the
positrons will be measured and will be compared with simulations.Comment: 3 pages, 5 postscript figures, epj style, talk given at the EPS
conference, Aachen, Germany, July 200
A Future Linear Collider with polarised beams: Searches for New Physics
There exists a world--wide consensus for a future Linear Collider in
the energy range between GeV as the next large facility in
HEP. The Linear Collider has a large physics potential for the discovery of new
physics beyond the Standard Model and for precision studies of the Standard
Model itself. It is well suited to complement and extend the physics program of
the LHC. The use of polarised beams at a Linear Collider will be one of the
powerful tools. In this paper some highlights of searches for physics beyond
the Standard Model at a future Linear Collider with polarised and
beams are summarised.Comment: 15 pages, 10 eps figures, Invited plenary talk given at 15th
International Spin Physics Symposium, September 2002, BNL, Brookhaven, US
Physics aspects of polarized e+ at the linear collider
Polarized e- and e+ at the International Linear Collider play an important
role for discovering physics beyond the Standard Model and for precisely
unravelling the structure of the underlying physics. The physics programme at
the first energy stage at sqrt{s}=500 GeV benefits strongly from the
polarization of both beams. But also at 1 TeV as well as at a possible
multi-TeV design of a linear collider, CLIC, the physics output is greatly
enriched by beam polarization. An overview is given of the impact of providing
polarized e+ at the linear collider in addition to polarized e- for physics
studies in top, Higgs, supersymmetry and further models of physics beyond the
Standard Model.Comment: 14 pages, 16 eps figures Talk given at the Polarized Positrons
Workshop `POSIPOL', CERN, 26-28 April 200
News from polarized e- and e+ at the ILC
The proposed International Linear Collider (ILC) is well-suited for
discovering physics beyond the Standard Model and for precisely unravelling the
structure of the underlying physics. The physics return of the ILC can be
maximized by the use of polarized beams, in particular the simultaneous
polarization of the e- and the e+ beam. Ongoing physics studies are accompanied
by active R&D on the machine part for generating polarized beams and for
measuring the polarization with high precision at the ILC. Some new results on
the physics case and on the technical aspects of the polarization of both beams
are briefly summarized.Comment: 6 pages, 12 eps figures, style files; Contribution to '2005
International Linear Collider Workshop -Stanford, U.S.A.
Nonlinear lepton-photon interactions in external background fields
Nonlinear phenomena of lepton-photon interactions in external backgrounds
with a generalised periodic plane-wave geometry are studied. We discuss
nonlinear Compton scattering in head-on lepton-photon collisions extended
properly to beyond the soft-photon regime. In addition, our results are applied
to stimulated lepton-antilepton pair production in photon collisions with
unrestricted energies. Derivations are considered semi-classically based on
unperturbed fermionic Volkov representations encoding the full interaction with
the background field. Closed expressions for total probabilities considering
S-matrix elements have been derived. The general formula is applied to Compton
scattering by an electron propagating in an external laser-like background. We
obtain additive contributions in the extended unconstrained result which turns
out to be stringently required in the highly nonlinear regime. A detailed
comparison of contributing harmonics is discussed for various field parameters.Comment: 39 pages, 8 figures, minor changes in introduction, references added,
a few misprints foun
- …