Kay Wittenburg

Proposing a laser based beam size monitor for the future linear collider

Compton scattering techniques for the measurement of the transverse beam size of particle beams at future linear colliders (FLC) are proposed. At several locations of the beam delivery system (BDS) of the FLC, beam spot sizes ranging from several hundreds to a few micrometers have to be measured. This is necessary to verify beam optics, to obtain the transverse beam emittance, and to achieve the highest possible luminosity. The large demagnification of the beam in the BDS and the high beam power puts extreme conditions on any measuring device. With conventional techniques at their operational limit in FLC scenarios, new methods for the detection of the transverse beam size have to be developed. For this laser based techniques are proposed capable of measuring high power beams with sizes in the micrometer range. In this paper general aspects and critical issues of a generic device are outlined and specific solutions proposed. Plans to install a laser wire experiment at an accelerator test facility are presented.

Beam Profile Measurements and Simulations of the Petra Laser-Wire

The Laser-wire will be an essential diagnostic tool at the International Linear Collider. It uses a finely focussed laser beam to measure the transverse profile of electron bunches by detecting the Compton-scattered photons (or degraded electrons) downstream of where the laser beam intersects the electron beam. Such a system has been installed at the PETRA storage ring at DESY, which uses a piezo-driven mirror to scan the laser-light across the electron beam. Latest results of experimental data taking are presented and compared to detailed simulations using the Geant4 based program BDSIM.

Beam profile measurements with the 2-D laser-wire at petra

The current PETRA II Laser-Wire system, being developed for the ILC and PETRA III, uses a piezo- driven mirror to scan laser light across an electron bunch. This paper reports on the recently installed electron-beam finding system, presenting recent horizontal and vertical profile scans with corresponding studies.

Simulation studies and background measurements for a laser based beam size monitor for the future linear collider

At several locations of the beam delivery system (BDS) of a future linear collider (FLC), beam spot sizes ranging from several hundreds to a few micrometers have to be measured. It is anticipated that laser wires will be used for this task in any FLC design. In order to optimize a laser wire system, simulations and background measurements have been carried out. Results are presented from simulations of the Compton scattering for the PETRA scenario. Furthermore results from measurements of backgrounds like synchrotron radiation and gas scattering have been measured at the positron storage ring PETRA at DESY and will be discussed.

Compton scattering techniques for the measurement of the transverse beam size of particle beams at future linear colliders

21st Beam Dynamics Workshop on Laser-Beam Interactions, State University of New York, Stony Brook, NY, USA, 11 Jun 2001 - 15 Jun 2001; 6 pp. (2001).