Abstracts Brochure - CERN

TUPCH083
TUPCH084
TUPCH085
27-Jun-06 16:00 - 18:00 TUPCH — Poster Session
Time-resolved Spectrometry on the CLIC Test Facility 3
T. Lefevre, C.B. Bal, H.-H. Braun, E. Bravin, S. Burger, R. Corsini, S.
Doebert, C.D. Dutriat, F. Tecker, P. Urschütz, C.P. Welsch (CERN)
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The high charge (>6microC) electron beam
produced in the CLIC Test Facility 3 (CTF3)
is accelerated in fully loaded cavities. To be
able to measure the resulting strong transient
effects, the time evolution of the beam energy and its energy spread must be measured with at least 50MHz bandwidth.
Three spectrometer lines were installed all along the linac in order to control and tune the beam. The electrons are
deflected by a dipole magnet onto an Optical Transition Radiation (OTR) screen, which is observed by a CCD camera.
The measured beam size is then directly related to the energy spread. In order to provide time-resolved energy
spectra, a fraction of the OTR photons is sent onto a multichannel photomultiplier. The overall set-up is described,
special focus is given to the design of the OTR screen with its synchrotron radiation shielding. The performance of
the time-resolved measurements are discussed in detail. Finally, the limitations of the system, mainly due to radiation
problems, are discussed.
Expected Signal and Optimal Position for the Ionization Chambers Downstream the
CNGS Target Station
M. Lorenzo Sentis, A. Ferrari, E. Gschwendtner, S. Roesler, L.
Sarchiapone (CERN)
Downstream the carbon graphite target of
the CNGS (CERN Neutrinos to Gran Sasso)
facility at CERN it has been decided to install
a secondary emission monitor called TBID
(Target Beam Instrumentation Downstream) monitor to measure the multiplicities and the left/right as well as up/
down asymmetries of secondary particles from target. Calculations show that the titanium windows used to close
off the TBID vacuum tank might not withstand the highest beam intensities with small spot sizes expected at CNGS,
in case the proton beam accidentally misses the 4-5 mm diameter target rods. Therefore it has been suggested to
place two ionisation chambers as a backup for the TBID located left and right of the TBID monitors. Monte Carlo
simulations with the particle transport code FLUKA were performed firstly to obtain the fluence of charged particles
in the region of interest and secondly to estimate the induced radioactivity (noise) in this area. This allows to assess
the actual signal/noise situation and thus to determine the optimal position (lateral displacement with respect to the
beamline) of the ionisation chambers. This document presents the results of these calculations.
Simulations for the Response of Beam Loss Monitors in IR7 Insertion in LHC
M. Magistris, B. Dehning, A. Ferrari, M. Santana-Leitner, M. Stockner,
V. Vlachoudis (CERN)
The collimation system in the beam cleaning
insertion IR7 of the future Large Hadron Collider
(LHC) cleans the primary halo and the
secondary radiation of a beam with unprece-
dented energy and intensity. Accidental beam losses can therefore entail severe consequences to the hardware of the
machine. Thus, protection mechanisms, e.g. retraction of the collimator jaws, must be instantaneously triggered by
a set of Beam Loss Monitors(BLM’s). The readings in the BLM’s couple the losses from various irradiated objects,
which renders the identification of the faulty unit rather complex. In the present study the detailed geometry of IR7
was upgraded with the insertion of the BLM’s, and the Monte Carlo FLUKA transport code was used to estimate the
individual contribution of every collimator to the showers detected in each BLM.