| Paper |
Title |
Other Keywords |
Page |
| IT01 |
The Future of Nuclear Physics in Europe and the Demands on Accelerators techniques
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antiproton, diagnostics, heavy ion, synchrotron |
3 |
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- W.F. Henning
GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
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Future large-scale facilities for research are very much under discussion
in Europe. This results, of course, on the one hand from the discussions
in the science communities and their identification of new frontiers in
research; but it also reflects to a certain degree the trend to pool
resources among the countries towards what has been labeled the “European
Research Area”.
In the field of nuclear physics and/or its intersections with particle
physics, several such efforts have been under consideration or are
underway. This applies to the study of the subnuclear degrees of freedom
of the strong interaction system(s) as well as to the extremes of the
atomic nucleus as the many-body system of the strong force.
In this talk an attempt is made to summarize the present status and
future plans, with emphasis on the facility concepts and their demands on
accelerator technology and development
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| PT26 |
Cryogenic Current Comparator for Absolute Measurement of the Dark Current of the Superconducting Cavities for Tesla
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cryogenics, diagnostics, monitoring, pick-up, shielding, TESLA |
234 |
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- K. Knaack, M. Wendt, K. Wittenburg
DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
- R. Neubert, S. Nietzsche, W. Vodel
FSU Jena, Friedrich-Schiller Universität, Jena, Germany
- A. Peters
GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
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A newly high performance SQUID based measurement system for detecting
dark currents, generated by superconducting cavities for TESLA is
proposed. It makes use of the Cryogenic Current Comparator principle and
senses dark currents in the nA range with a small signal bandwidth of 70
kHz.
To reach the maximum possible energy in the TESLA project is a strong
motivation to push the gradients of the superconducting cavities closer
to the physical limit of 50 MV/m. The field emission of electrons (the so
called dark current) of the superconducting cavities at strong fields may
limit the maximum gradient. The absolute measurement of the dark current
in correlation with the gradient will give a proper value to compare and
classify the cavities.
This contribution describes a Cryogenic Current Comparator (CCC) as an
excellent and useful tool for this purpose. The most important component
of the CCC is a high performance DC SQUID system which is able to measure
extremely low magnetic fields, e.g. caused by the extracted dark current.
For this reason the SQUID input coil is connected across a special
designed pick-up coil for the electron beam. Both the SQUID input coil
and the pick-up coil form a closed superconducting loop so that the CCC
is able to detect dc currents down to 2 pA/√Hz. Design issues and the
application for the CHECHIA cavity test stand at DESY as well as
preliminary experimental results are discussed.
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