Abstracts Brochure - CERN

THPCH088
THPCH089
THPCH090
29-Jun-06 16:00 - 18:00 THPCH — Poster Session
this cavity lies in the simple geometry with no need for vacuum inside the cavity and high shunt impedance despite
an internal ferrite load. The ferrite load is succesfully used to dampen higher order modes down to Q < 50 while the
fundamental mode is damped by less than 2 dB. While nominal input power is rated at 60 dBm the cavity is prepared
to handle beam loading. In spite of power requirements and ferrite load the cavity needs no active cooling. It can be
tuned in center frequency and bandwidth over a range of 96..105 MHz and 4..7 MHz respectively and in consequence
provides an optimal actuator for the particle beam control system. Presented will be the design details, all relevant
parameters, the design of the internal ferrite load and operational experience.
A Possibility of Constant Energy Extraction at the KEK ATF
Beam energy oscillations of the order of
A. Kalinin (CCLRC/DL/ASTeC)
0.02% take place at the KEK ATF. With extractions,
the synchrotron oscillation amplitude
and phase at the extraction turn randomly fluctuates. The energy jitter causes a position/angle jitter in the
Diagnostic section of the Extraction Line. To reduce it, a feed forward energy stabilisation can be used done by
extraction of the beam at the turn next to that turn at which the energy passes the equilibrium value. For this,
the synchrotron oscillation is measured by a turn-by-turn BPM as a horizontal position oscillation. A fast turn-byturn
processor detects the turn where the oscillation passes zero, and generates an extraction permission signal that
triggers the existing ATF Extraction system. Stability improvement by factor of 10 can be obtained even when the
extraction is done with uncertainty up to three turns after the trigger.
The Electromagnetic Background Environment for the Interaction-point Beam Feedback
System at the International Linear Collider
The Interaction Point (IP) feedback system is
G.B. Christian (JAI)
essential for maintaining the luminosity at
the International Linear Collider (ILC). It is
necessary to demonstrate the performance of the feedback beam position monitor (BPM) in an electron-positron
pair background similar to that expected in the ILC interaction region (IR). We have simulated the ILC beam-beam
interactions and used a GEANT model of the IR to evaluate the pair and photon flux incident on the BPM, for both the
2 mrad and 20 mrad crossing angle geometries. We present results as a function of the proposed machine parameter
schemes, as well as for various system layouts within the IR. We plan to study the degradation of BPM resolution,
and the long term survivability, in beam tests at End Station A at SLAC. To simulate the background environment of
the ILC a ’spray beam’ will be produced, which will scatter from a mechanical mock-up of the forward region of the
IR, and irradiate the BPM with realistic flux of secondary pairs. We present the proposed experimental layout and
planned beam tests.
Stabilization of the ILC Final Focus Using Interferometers
We are developing a system of interferom-
D. Urner, P.A. Coe, A. Reichold (OXFORDphysics)
eters that can measure the relative motion
between two objects (such as the two final
focus quadrupoles) to a few nanometers using interferometric methods. Two instruments are developed at the John
Adams Institute at University of Oxford: A distance meter to measure length changes and a straightness monitor to
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