Abstracts Brochure - CERN

TUPCH — Poster Session 27-Jun-06 16:00 - 18:00
"standard" beam diagnostics technology. Here, new or further developments are required. The paper gives a general
view of the beam diagnostics concept for the CSR and shows in more detail possible solutions for the measurement
of beam position and beam profile.
A New SQUID-based Measurement Tool for Characterization of Superconducting RF Cavities
In this contribution a LTS-SQUID based measurement
tool for characterization of superconducting
RF cavities for the upcoming X-
FEL project at DESY will be presented. The
K. Knaack, K. Wittenburg (DESY) R. Neubert, S. Nietzsche, W.
Vodel (FSU Jena) A. Peters (GSI)
device makes use of the Cryogenic Current Comparator (CCC) principle and measures the so-called dark current,
generated e.g. by superconducting cavities at high voltage gradients. To achieve the maximum possible energy the
gradients should be pushed near to the physical limit of 50 MV/m. The measurement of the undesired field emission
of electrons (the so-called dark current) in correlation with the gradient will give a proper value to characterize the
performance of the RF cavities. The CCC mainly consists of a high performance LTS-DC SQUID system which is able
to measure extremely low magnetic fields, e.g. caused by the extracted dark current of the RF cavities. Therefore,
a special designed toroidal niobium pick-up coil for the passing electron beam is superconducting connected across
the input coil of the SQUID. The noise limited sensitivity of the CCC as well as new experimental results with the
whole measurement device assembled in a special wide-necked LHe cryostat will be presented.
Precise Measurements of the Vertical Beam Size in the ANKA Storage Ring with an In-air
X-ray Detector
A major part of the X-rays generated in the
ANKA dipole magnets is unused by the experimental
beamlines and is, on a number of
dipoles, absorbed in a conical shaped Cop-
A.-S. Müller, I. Birkel, E. Huttel, P. Wesolowski (FZK) K.B. Scheidt
(ESRF)
per absorber. The 8 mm thickness that it presents lets a tiny fraction of the hard X-rays above 70KeV enter the free
air space behind it. The transmitted power of only a few uW/mrad hor. is sufficient to be detected, with sub-second
measurement time, by a novel In-Air X-ray detector. This extremely compact and low-cost device is situated just
behind the absorber. The design, developed and in use at the ESRF, is based on a Cadmium Tungstenate (CdWO4)
scintillator converting X-rays into visible light that is collected and focused onto a commercial CCD camera. Since the
small vertical divergence of the high energy photons and the distance of the detector from the source point are known,
it is possible to derive the vertical electron beam size with a high intrinsic precision. This paper presents results of
beam size measurements as a function of various ANKA machine parameters, that illustrates the great diagnostic
potential of this type of detector for a 2.5GeV medium energy light source like ANKA.
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