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PS05 |
Measurement of the Time-Structure of the 72 MeV Proton Beam in the PSI Injector-2 Cyclotron
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- R. Dölling
PSI, Paul Scherrer Institut, Villigen, Switzerland
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The time-structure monitor at the last turn of the 72MeV Injector-2
cyclotron has been improved in order to meet the stringent
time-resolution requirement imposed by the short bunch length. Protons
scattered by a thin carbon-fibre target pass through a first
scintillator-photomultiplier detector and are stopped in a second one.
The longitudinal bunch shape is given by the distribution of arrival
times measured with respect to the 50 MHz reference signal from the
acceleration cavities. From a coincidence measurement, the time
resolution of the detectors has been determined to be 51 ps and 31 ps
fwhm. Longitudinal and horizontal bunch shapes have been measured at beam
currents from 25μA to 1700μA. Approximately circular bunches were
observed with diameter increasing with current. The shortest observed
proton bunch length was 38 ps fwhm.
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