Abstracts Brochure - CERN

TUPCH022
TUPCH023
TUPCH024
27-Jun-06 16:00 - 18:00 TUPCH — Poster Session
Beam Position Monitor with Large Horizontal Aperture
K.E. Hacker, N. Baboi, F. Ludwig, D. Noelle, H. Schlarb, T. Traber,
A. Winter (DESY) F. Loehl (Uni HH)
166
A beam position monitor with a large horizontal
aperture is being developed for use
in dispersive sections of the TTF2-VUV-FEL
magnetic chicanes. It has a horizontal range
of 15 cm and a resolution requirement of better than 30 microns. A stripline design mounted perpendicularly to the
the electron beam direction is used to provide broadband electrical pulses traveling in opposite directions, the phases
of which give a measure of the beam position. The phase measurement will be accomplished through a combination
of both optical and high-frequency electronic methods. Results from simulation and a stretched-wire test prototype
will be presented.
Direct Observation of Beam-beam Induced Dynamical Beta Beating at HERA
The Hadron Electron Ring Anlage (HERA) at
G. Kube, F.J. Willeke (DESY)
DESY provides collisions between a 920 GeV
proton beam and a 27.5 GeV electron beam
in two interaction regions. The strong beam-beam force, which mainly affects the electrons, induces a tune shift
together with a dynamical beta beat. The latter leads to a modification of the transverse beam profile, which can be
observed in different profile monitors in HERA. The time-like evolution of the electron beam shape during luminosity
tuning and before and after dump of the proton beam, averaged over all bunches, could be studied by means of
a synchrotron radiation profile monitor. Measurements with a wire scanner allowed to see the beam-beam force’s
influence on each individual bunch at the expense of resolution. The observations could be explained qualitatively
in the frame of linear incoherent beam-beam interaction.
Comparative Study of Bunch Length and Arrival Time Measurements at the VUV-FEL at
DESY
H. Schlarb, A. Azima, S. Düsterer, M. Huening, E.-A. Knabbe,
M. Roehrs, R. Rybnikov, B. Schmidt, B. Steffen (DESY) M.C. Ross
(SLAC) P. Schmüser, A. Winter (Uni HH)
Diagnostic devices to precisely measure the
longitudinal electron beam profile and the
bunch arrival time require elaborate new instrumentation
techniques. At the VUV-FEL,
two entirely different methods are used. The
bunch profile can be determined with high precision by a transverse deflecting RF structure. The method is disruptive
and does not allow to monitor multiple bunches in a macro-pulse train. Therefore, it is augmented by two nondisruptive
electro-optical devices, called EO and TEO. The EO setup uses a dedicated diagnostic laser synchronized
to the machine RF. The longitudinal electron beam profile is encoded in the intensity profile of a chirped laser pulse
and analyzed by looking at the spectral composition of the pulse. The second setup, TEO, utilizes the TiSa-based laser
system used for pump-probe experiments. Here, the temporal electron shape is encoded into a spatial dimension
of laser pulse by an intersection angle between the laser and the electron beam at the EO-crystal. In this paper, we
present a comparative study of bunch length and arrival time measurements performed simultaneously with all three
experimental techniques.