| Paper |
Title |
Page |
| TUPC022 |
Non-destructive Beam Position and Profile Measurements Using Light Emitted by Residual Gas in a Cyclotron Beam Line
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1095 |
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- J. Dietrich
FZJ, Jülich
- C. Boehme
UniDo/IBS, Dortmund
- A. H. Botha, J. L. Conradie, M. A. Crombie, J. H. Du Toit, D. T. Fourie, H. W. Mostert, P. F. Rohwer, P. A. van Schalkwyk
iThemba LABS, Somerset West
- T. Weis
DELTA, Dortmund
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Non-destructive beam position and profile measurements were made in the transfer beam line between an 8 MeV solid-pole injector cyclotron and a 200 MeV separated-sector cyclotron that is used for nuclear physics research, radioisotope production and proton and neutron therapy. Light emitted from the beam induced ionization of residual gas particles was measured using a multi-cathode photomultiplier tube (PMT). The PMT was mounted outside the vacuum system on a diagnostic chamber and light passing through a glas window was focused on the photocathode array by means of a lens. The anode currents of the PMT were measured with computer-controlled electronic equipment recently developed for measuring the currents of multi-wire beam profile monitors. Software was developed to control the measurement processes, remove offset values and further process the data digitally. The measured beam positions and profiles were compared with those determined with a multi-wire beam profile monitor for a 3.14 MeV proton beam. It was necessary to shield the PMT from gamma rays generated on nearby slits. The design of the measuring equipment is discussed and the results of the measurements are presented.
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| TUPP022 |
Measurements of Broad Band Impedance Related Longitudinal Properties of Electron Bunches at DELTA
|
1577 |
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- R. Burek, H. Huck, G. Schmidt, T. Weis, K. Wille
DELTA, Dortmund
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DELTA is a 1.5 GeV synchrotron light source which can be operated also at 550 MeV for FEL experiments. Due to interactions with the vacuum chamber, the beam induces wake fields, which act back on the beam and result in a disturbed bunch profile because of potential well distortion and turbulent bunch lengthening. These interactions limit the obtainable bunch length and achievable peak current and therefore strongly affect the FEL-operation. Recent results obtained by streak camera measurements have shown that for short bunches with maximum bunch lengths of 40 ps the longitudinal broad band impedance has to be scaled (SPEAR-scaling) to explain the measurements. The broad band impedance fits well to impedance measurements and calculations performed throughout the last years. The energy spread related to the bunch lengthening has been measured by analysing the undulator spectrum.
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