Luminosity, Energy and Polarization Studies for the Linear Collider: Comparing e+e- and e-e- for NLC and TESLA

We present results from luminosity, energy and polarization studies at a future Linear Collider. We compare e+e- and e-e- modes of operation and consider both NLC and TESLA beam parameter specifications at a center-of-mass energy of 500 GeV. Realistic colliding beam distributions are used, which include dynamic effects of the beam transport from the Damping Rings to the Interaction Point. Beam-beam deflections scans and their impact for beam-based feedbacks are considered. A transverse kink instability is studied, including its impact on determining the luminosity-weighted center-of-mass energy. Polarimetry in the extraction line from the IP is presented, including results on beam distributions at the Compton IP and at the Compton detector.Comment: 17 pages, 12 figures. Presented at 5th International Workshop on Electron-Electron Interactions at TeV Energies, December 12-14, 2003, Santa Cruz, C

Stability Considerations for Final Focus Systems of Future Linear Colliders

The final focus systems for the future linear colliders need to focus beams to nm-range spot sizes at the collision point. The design spot size varies from several nm for 500 GeV to the one nm range for 3 TeV. In order to keep the beams in collision and to maintain the luminosity stringent stability optimization must be applied. We discuss different sources of beam perturbations and estimate the expected beamline stability based on previous experimental observations. Possible measures for beam stabilization are discussed and plans of further collaborative efforts are outlined

First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength

We present the first observation of Self-Amplified Spontaneous Emission (SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width and intensity fluctuations all corroborate the existing models for SASE FELs.Comment: 6 pages including 6 figures; e-mail: [email protected]

Stabilization of Beam Interaction in the TESLA Linear Collider

Vertical beam offsets at the interaction point will degrade the luminosity (3.4 $\centerdot$ 10$^{34}$ cm$^{-2}$s$^{-1}$) in the TESLA linear collider. In order to limit the luminosity loss to 10% per bunch crossing the electron (e$^-$) and positron (e$^+$) beams must interact with an offset and angle of less than 1/10 of the beam size and the angular divergence respectively. The required stabilization of the beam interaction will be provided on a bunch to bunch basis by two feedback systems. One system, located upstream of the vertical chromatic correction system, controls the beam angle. The second system placed at the interaction region steers the two beams into collision using the beam-beam deflection method. This paper describes the feedback designs and presents simulation results. Design modifications necessary for the $e^-e^-$ mode are briefly discussed

Luminosity Issues for the e−e−e^-e^- Option of the TESLA Linear Collider

The future TESLA linear $e^+e^-$ collider can also be used for $e^-e^-$ collisions at a center of mass energy of 500GeV and beyond. A critical issue for the physics potential of this option is the achievable luminosity. For $e^+e^-$ collisions, the pinch effect enhances the luminosity, while due to the repelling forces for $e^-e^-$ collisions, the luminosity is significantly reduced and is more sensitive to beam separations. This report discusses an intra-train feedback to stabilize the luminosity and possibilities to partly overcome the luminosity degradation of the $e^-e^-$ mode

Design and Test of a Fast Feedbacksystem for Orbit Correction at TTF and the TESLA Linear Collider

To achieve high luminosity in the TESLA Linear Collider feedback systems will be needed to provide orbit corrections within the bunch train. A prototype of the complete vertical feedback system has been installed in the TESLA Test Facility at DESY. The use of digital signal processing techniques led to a fast and highly flexible solution for the controller function. Additional features such as data logging and analysis allow easyadjustment of the feedback parameters to achieve the optimum performance of the system. An overview of the system will be presented as well as the results of first measurements