Abstract

Linear coupling is one of the factors that determine beam lifetime in RHIC. The traditional method of measuring the minimum tune separation requires a tune scan and can't be done parasitically or during the acceleration ramp. A new technique of using AC dipoles to measure linear coupling resonance has been developed at RHIC. This method measures the degree of coupling by comparing the amplitude of the horizontal coherent excitation with the amplitude of the vertical coherent excitation if the beam is excited by the vertical AC dipole and vice versa. One advantage of this method is that it can be done without changing tunes from the normal machine working points. In principle, this method can also localize the coupling source by mapping out the coupling driving terms throughout the ring. This is very useful for local decoupling the interaction regions in RHIC. A beam experiment of measuring linear coupling has been performed in RHIC during its 2003 run, and the analysis of the experimental data is discussed in this paper.

Highlights

  • In a circular accelerator, the linear 4x4 one-turn transfer matrix T for the two-dimensional phase space (x,x’,y,y’)can be represented by four 2x2 sub-matrices M, m, n and N T= Mm nN (1)where M and N are the standard transfer matrices in the (x,x’) phase and (y,y’) phase space

  • When the C matrix is zero, there is no coupling between the two transverse planes, and one can use C to characterize the strength of the linear coupling

  • In the absence of linear coupling, a horizontal betatron oscillation at location s is excited with amplitude of x(s)

Read more

Summary

Introduction

When the C matrix is zero, there is no coupling between the two transverse planes, and one can use C to characterize the strength of the linear coupling. Unlike CESR, an AC dipole was used in RHIC to adiabatically excite the beam at the vicinity of the eigen-tune instead. We assume that the horizontal ac dipole (vertical field) is used to adiabatically excite a sizable coherent excitation nearby the horizontal tune Qx. The horizontal AC dipole integrated field ∆ByL is

Results
Conclusion

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.