Beam based alignment method applications for Sirius storage ring

Author(s)

Alexandre Béo da Cruz

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
• Defense date: 2022-11-16

Examining board members

Antonio Rubens Britto de Castro; Eduardo Granado Monteiro da Silva; Tiago Fiorini da Silva

• Advisor: Antonio Rubens Britto de Castro

Abstract

In this work, using computer simulations, we studied the Beam Based Alignment (BBA) method, applied to SIRIUS storage ring. In BBA the stored electron beam itself is used to measure the alignment of the magnets. We have used the method in usual way for quadrupole magnets and also for sextupoles. A recursive method to scan the beam in vertical and horizontal directions was successfully used in simulations, which proved efficient to minimize coupling effects that appear when skew quadrupoles are used. It has also been investigated the possibility of using the magnetic center of a sextupole as reference, using as merit function the orbit and tune deviation caused by sextupole variation. We describe an effect that occur when magnet used as BBA reference has an dipole field component, which is the displacement of magnetic center. We deduced how this effect appears, so that it was possible to determine an correction equation that allows us to get magnetic center of magnet of interest by BBA even when there are dipole components. With this correction, in the case of SIRIUS, we estimate with 50% confidence that usual BBA has an accuracy of 10 um in quadrupoles, 8 um in skew quadrupoles and 20 um in sextupoles. Simulating the orbit deviation caused by sextupole variation, we found that there may be experimental limitations on maximum variation allowed, which would make it difficult to measure experimentally the merit function obtained in simulations, requiring an resolution of 10^-3 um^2 in this measure, which is equivalent to having position measurers with 30 nm of resolution. Finally, by simulating tune deviation caused by sextupole variation, which in a real experiment would make it possible to measure the center of the field gradient, we observed that only horizontal component of this measure would be possible. We described the theoretical behavior expected for tune shift, so that it was possible to show that in vertical direction the tune shift effect is second order in relation to applied variation. Nevertheless, the simulations indicate that horizontal component can also be determined with accuracy equivalent to usual BBA (AU)

• FAPESP's process: 18/07872-7 - Applications of the beam based alignment method for the Sirius project
• Grantee: Alexandre Béo da Cruz
• Support Opportunities: Scholarships in Brazil - Master