Each cycle lasts 10 ms, during which the beam makes 12,000 revolutions in a 163 m circumference, with the proton energy gradually rising from 70 to 800 MeV.
The amount of beam the synchrotron can accelerate is limited by beam losses. A new monitoring system has been developed to analyse data from thirty-nine gas ionization tubes distributed around the synchrotron. Beam losses are identified in individual monitors at any time during acceleration.
Accurate determination and correction of the position of the proton beam is also a major factor in reducing losses. To this end, data acquisition and analysis systems for the fourteen horizontal and seventeen vertical beam position monitors have been installed in the synchrotron. The new system can closely monitor and correct the beam position to within 2 mm of the machine centre.
These developments have helped set new records for maximum beam current from the ISIS synchrotron. The record average current for 24 hours of operation now stands at 217.1 µA.
B Jones, SA Fisher (ISIS)
Research date: January 2010
Further reading: The ISIS Proton Synchrotron: Beam Data Acquisition and Analysis Using NI PXI and LabVIEW