Norbert Holtkamp

An interaction region for gamma–gamma and gamma–electron collisions at TESLA/SBLC

Abstract Linear colliders offer a unique opportunity to study γγ and γe interactions. Using the laser backscattering method one can obtain γγ, γe colliding beams with an energy and luminosity comparable to that in e + e − collisions. This work is part of the Conceptual Design of TESLA/SBLC linear colliders considering a second interaction region for γγ and γe collisions. We consider here possible physics in high-energy γγ, γe collisions, e→γ conversion, requirements to lasers, collision schemes, attainable luminosities, backgrounds, possible lasers, optics at the interaction region and other associated problems.

Status and future developments of the wake field transformer experiment

Abstract Future e + e − linear colliders with center-of-mass energies of 2 TeV need high average accelerating gradients to be built within a reasonable length. The gradients required by colliders at this energy range can be economically provided by resonant wake field transformers. At the wake field experiment at DESY a 20 cm long transformer section was investigated. The basic ideas are reviewed and the most recent results are presented in this paper. Furthermore an overview of the present status of research concerning the proposed next stage of a multibunch driver linac with superconducting cavities and long wake field transformer sections is presented.

Wake Field Acceleration, a Way to TeV e+ e- Collisions

Future e + e -- accelerators in the energy range above 1 TeV will be linear colliders with a high accelerating gradient. For creating the high gradient, new concepts are investigated, such as wake field acceleration, which need driver beams with high current and short bunches. At DESY an experiment with a Wake Field Transformer has been set up, where electromagnetic wake fields of a highly charged hollow driver beam are spatially focussed, and the resulting high longitudinal electric field is used for the acceleration of a second beam. The basic idea, the layout of the experiment and the results are presented. In a stage-1 experiment several bunches, each of 50 to 100 nC charge, have been produced and accelerated to an energy of 6.5 MeV and bunched down to a length of 3–4 mm. Using longer bunches of 1 cm, a gradient of 8 MeV/m has already been measured in a short Wake Field Transformer section.