Dissertation/Thesis Abstract

Optics measurement and correction for the Relativistic Heavy Ion Collider
by Shen, Xiaozhe, Ph.D., Indiana University, 2014, 156; 3636204
Abstract (Summary)

The quality of beam optics is of great importance for the performance of a high energy accelerator like the Relativistic Heavy Ion Collider (RHIC). The turn-by-turn (TBT) beam position monitor (BPM) data can be used to derive beam optics. However, the accuracy of the derived beam optics is often limited by the performance and imperfections of instruments as well as measurement methods and conditions. Therefore, a robust and model-independent data analysis method is highly desired to extract noise-free information from TBT BPM data. As a robust signal-processing technique, an independent component analysis (ICA) algorithm called second order blind identification (SOBI) has been proven to be particularly efficient in extracting physical beam signals from TBT BPM data even in the presence of instrument's noise and error. We applied the SOBI ICA algorithm to RHIC during the 2013 polarized proton operation to extract accurate linear optics from TBT BPM data of AC dipole driven coherent beam oscillation. From the same data, a first systematic estimation of RHIC BPM noise performance was also obtained by the SOBI ICA algorithm, and showed a good agreement with the RHIC BPM configurations. Based on the accurate linear optics measurement, a beta-beat response matrix correction method and a scheme of using horizontal closed orbit bumps at sextupoles for arc beta-beat correction were successfully applied to reach a record-low beam optics error at RHIC. This thesis presents principles of the SOBI ICA algorithm and theory as well as experimental results of optics measurement and correction at RHIC.

Indexing (document details)
Advisor: Lee, Shyh-Yuan
Commitee: Carini, John P., Gottlieb, Steven A., Snow, Michael W.
School: Indiana University
Department: Physics
School Location: United States -- Indiana
Source: DAI-B 76/01(E), Dissertation Abstracts International
Subjects: Atoms & subatomic particles
Keywords: Accelerator physics, Beam optics correction, Beam optics measurement, Independent component analysis, Relativistic heavy ion collider
Publication Number: 3636204
ISBN: 9781321176797
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