Ph.d. degree
University of Bern, Switzerland, 2017

Konrad Pawel Nesteruk

Supervisor: Antonio Ereditato

A New System for Online Measurement of the Beam Emittance of Particle Accelerators for Research and medical Applications

Keywords:

• Beam-line instrumentation (beam position and profile monitors; beam-intensity monitors; bunch length monitors)
• Instrumentation for particle accelerators and storage rings - low energy (linear accelerators, cyclotrons, electrostatic accelerators)
• Beam dynamics

Abstract:

A system for online measurement of the transverse beam emittance was developed. It was conceived to measure the emittance in a fast and efficient way using the multiple beam profiler method. Beam profiles are measured by four consecutive UniBEaM profilers, which are based on silica fibers passing across the beam. Their development is also a part of the PhD work and their design and performance are reported in this thesis. The new system was deployed for characterization studies of the 18 MeV proton beam produced by the IBA Cyclone 18 MeV cyclotron at Bern University Hospital (Inselspital). The machine serves daily radioisotope production and multi-disciplinary research, which is carried out with a specifically conceived Beam Transport Line (BTL). The transverse RMS beam emittance of the cyclotron was measured as a function of several machine parameters, such as the magnetic field, RF peak voltage, and azimuthal angle of the stripper. The beam emittance was also measured using the method based on the quadrupole strength variation. The results obtained with both techniques were compared and a good agreement was found. In order to characterize the longitudinal dynamics, the proton energy distribution was measured. For this purpose, a method was developed based on aluminum absorbers of different thicknesses, a UniBEaM detector, and a Faraday cup. The results were an input for a simulation of the BTL developed in two different codes. These tools allow machine parameters to be tuned online and the beam characteristics to be optimized for specific applications. The new system was also deployed to evaluate the transverse beam emittance of the TR24 cyclotron at IPHC in Strasbourg (France).