Abstracts Brochure - CERN

THOBFI01
THOBFI02
THOBFI03
29-Jun-06 11:30 - 12:30 THOBFI — Beam Instrumentation and Feedback
THOBFI — Beam Instrumentation and Feedback
A Sub 100 fs Electron Bunch Arrival-time Monitor System for the VUV-FEL
F. Loehl, K.E. Hacker, F. Ludwig, H. Schlarb, B. Schmidt (DESY) A.
Winter (Uni HH)
The stability of free-electron lasers and experiments
carried out in pump-probe configurations
depends sensitively on precise
synchronization between the photo-injector
laser, low-level RF-systems, probe lasers, and other components in the FEL. A measurement of the jitter in the arrivaltime
of the electron bunch with respect to the clock signal of a master oscillator is, therefore, of special importance.
For this task, we propose an arrival-time monitor based on a beam pick-up with more than 10GHz bandwidth which
permits measurements in the sub 100 fs regime. The RF-signal from the beam pick-up is sampled by an ultra-short
laser pulse using a broad-band electro-optical modulator. The modulator converts the electron bunch arrival-time
jitter into an amplitude modulation of the laser pulse. This modulation is detected by a photo detector and sampled
by a fast ADC. By directly using the laser pulses from the master laser oscillator of the machine, any additional timing
jitter is avoided. In this paper we present the layout of the system and first experimental results.
Measurement of the Beam Profiles with the Improved Fresnel Zone Plate Monitor
We present the recent progress of the FZP
H. Sakai, N. Nakamura (ISSP/SRL) H. Hayano, T. Muto (KEK) (Fresnel Zone Plate) beam profile monitor
constructed at KEK-ATF damping ring. This
monitor based on an X-ray imaging optics with two FZPs*. In this monitor, the transverse electron beam image at
bending magnet is twenty-times magnified by the two FZPs and detected on an X-ray CCD camera. Then the realtime
and 2-dimentional transverse beam profiles can be obtained with non-destructive manner by using this monitor.
The expected spatial resolution is less than 1 micro-meter. Recently, we install the new mechanical shutter to improve
time resolution of the monitor and avoid the effects of the short-term movement of the beam or the monitor itself. By
applying this shutter, the shutter opening time was reduced less than 1ms and the beam profile could be measured
more accurately. In this paper, we report the new shutter performance and the measurement results of beam profiles
by the improved FZP beam profile monitor.
*K. Iida, et al. Nucl. Instrum. Meth. A 506 (2003) 41-49.
Record-high Resolution Experiments on Comparison of Spin Precession Frequencies of
Electron Bunches Using the Resonant Depolarization Technique in the Storage Ring
S.A. Nikitin, O. Anchugov, V.E. Blinov, A. Bogomyagkov, V.P.
Cherepanov, G.V. Karpov, V. Kiselev, E. Levichev, I.B. Nikolaev, A.A.
Polunin, E. Shubin, E.A. Simonov, V.V. Smaluk, M.V. Struchalin,
G.M. Tumaikin (BINP SB RAS)
The opportunity of performing an experiment
on high precision comparison of the
electron and positron anomalous magnetic
moments following the VEPP-2M experiment
is under study at the VEPP-4M storage
ring. The record accuracy of 1.5x10-8 was
obtained for comparison of spin precession frequencies in the experiment on resonant depolarization with simultaneously
circulating electron bunches, two of them polarized and one unpolarized. It is the first time when the spreading
384 Chair: M.C. Ross (SLAC, Menlo Park, California)