Abstracts Brochure - CERN

TUPCH — Poster Session 27-Jun-06 16:00 - 18:00
Bunched Beam Current Measurements with 100 pA rms Resolution at CRYRING
In CRYRING molecular beams with currents
down to 1 nA are used for experiments. To A. Paal, A. Simonsson (MSL) J. Dietrich, I. Mohos (FZJ)
extend the rms resolution of the bunched
beam current measurements down to 100 pA, a BERGOZ Integrating Current Transformer (ICT) and one of the
the capacitive pick-up’s sum signal are integrated simultaneously. The absolute calibration of the pick-up integrator
signal is carried out at the end of the acceleration stage, during 20-60 ms. The ion beam current can be measured over
a pulse width range of 100 ns to 15 us with a 20-60% bunch duty cycle. For both detectors, low noise amplifiers and a
differential input double integrator have been designed. A programmable phase shifter allows measurement of the
beam current during the acceleration of the ions, generating a gate signal with proper phase for the integrators in the
30 kHz-3 MHz frequency range. The bandwidth of the integrators used is 100 Hz.
Technical Aspects of the Integration of the Optical Replica Synthesizer for the Diagnostics
of Ultra-short Bunches into the VUV-FEL at DESY
Recently, Saldin, et al.* proposed a novel
scheme to characterize ultra-short electron
bunches that is based on inducing an energy
modulation in the electron beam by superimposing
a laser with transversely undulating
electrons. The energy modulation is subse-
V.G. Ziemann (UU/ISV) M. Koerfer, D. Noelle, J. Rossbach, E.
Saldin, E. Schneidmiller, M.V. Yurkov (DESY) M. Larsson (Stockholm
University, Department of Physics) P. van der Meulen
(FYSIKUM, AlbaNova, Stockholm University)
quently transformed into a density modulation in a dispersive section, and a coherent IR light pulse with the
longitudinal profile of the electron bunch is emitted in a second undulator magnet. The emitted IR light pulse can
then be analyzed by standard non-linear optical methods such as frequency resolved optical gating. We discuss the
implementation of such a measurement setup at the VUV-FEL at DESY in Hamburg, Germany, and investigate the
influence of parameter choices on the performance of the device. Topics we address include the beam optics of the
undulators, quadrupoles and the dispersive chicane, windows and optics of the seed laser, as well as synchronization
issues. The properties of the generated IR laser pulse and its separation from the copropagating x-ray laser pulse are
also covered. We close by presenting parameters for an optical replica in the X-FEL.
*E. Saldin, et al. "A simple method for the determination of the structure of ultrashort relativistic electron bunches,"
Nucl. Inst. and Methods A 539 (2005) 499.
The EuroTeV Confocal Resonator Monitor Task
We describe the progress in the analysis of
the confocal resonator monitor task which is
part of the diagnostics workpackage of EuroTeV.
The initial design was analyzed both
V.G. Ziemann, T. J. C. Ekelof, A. Ferrari, M. A. Johnson, E. A.
Ojefors, A. B. Rydberg (UU/ISV) F. Caspers (CERN)
numerically and experimentally and found limitations. We therefore digressed from strict confocality and report the
numerical analysis and S-parameter measurements of a modified design. Furthermore, we discuss the mechanical
design needed for planned tests with beam in CTF3 which requires integration of the monitor into the beam pipe,
damping of trapped modes, and frequency tunability.
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