Using the quadrupole scan technique to measure the electron emittance in the booster-to-storage ring transfer line at the canadian light source

The Canadian Light Source is a third generation synchrotron light source with an electron energy of 2.9 GeV on the University of Saskatchewan campus in Saskatoon, Saskatchewan. It consists of three accelerators: a linear accelerator, the Booster Ring, and the Storage Ring. There are two transfer lines that move the electron beam between accelerators to finally circulate in the Storage Ring. In the Storage Ring the electron beam produces synchrotron light to 24 photon beamlines; 22 user beamlines for various experiments and 2 diagnostic beamlines. In the injection process, approximately one third of the electron beam is lost from the Booster Ring to the Storage Ring in the Booster-to-Storage Ring transfer line. To mitigate radiation damage to components in the Storage Ring from the lost electrons and potential secondary radiation caused from collisions, the beam is intentionally scraped away in well shielded areas in the transfer line. The extracted beam from the Booster Ring historically has not been well understood and, by extension, the beam propagating through the transfer line and captured in the Storage Ring has not been well understood either. Measuring the properties and better understanding the electron beam being extracted from the Booster Ring is the beginning of the process to attempt to reduce the losses in the transfer line and work towards increasing the injection efficiency into the Storage Ring. This thesis presents these measurements to better understand the electron beam extracted from the Booster Ring. Purposely designed diagnostic cameras and two quadrupoles, a focusing and a defocusing, were used in the Booster-to-Storage Ring transfer line for the quadrupole scan measurements such that both the horizontal and vertical emittances could be measured individually. Both quadrupoles were also utilized for 2D raster scans that measured both the horizontal and vertical emittances together. An estimated emittance in the Booster Ring was also measured using a combination of images of the synchrotron radiation produced by the Booster Ring and simulated beam values. These emittances measured were then compared to expected theoretical emittances of the Booster Ring based on the lattice design. Some supplementary measurements were done alongside the quadrupole scans that are included in this thesis. The polarity of the quadrupoles were checked to ensure they were as expected. The beam was steered through different positions of the quadrupoles to see if there were non-linear impacts. This lead to learning the steering magnets in the transfer line can have a large impact on the beam in the Booster Ring. The same quadrupole scan techniques were used to measure the emittance of electron beam from the new linear accelerator installed at the Canadian Light Source as part of the commissioning process. The measured emittances are close to the expected theoretical emittances, indicating that this is not the culprit for the losses in the transfer line. Though the emittances do not explain the electron beam losses in the Booster-to-Storage Ring transfer line, the measurements are still important in the process of better understanding the beam that is extracted from the Booster Ring.

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