Beta Function Measurement in the Tevatron Using Quadrupole Gradient Modulation

Abstract

Early in Run2, there was an effort to compare the different emittance measurements in the Tevatron (flying wires and synchrotron light) and understand the origin of the observed differences. To measure the beta function at a few key locations near the instruments, air-core quadrupoles were installed. By modulating the gradient of these magnets and measuring the effect on the tune, the lattice parameters can be extracted. Initially, the results seem to disagree with with other methods. At the time, the lattice was strongly coupled due to a skew component in the main dipoles, caused by sagging of the cryostat. After a large fraction of the superconducting magnets were shimmed to remove a strong skew quadrupole component, the results now agree with the theoretical values to within 20%.

Review of linear optics measurement and correction for charged particle accelerators

“…K modulation has been successfully used to measure average beta functions in almost every accelerator, for example, ISR [12,17], LEP [38,39], HERA [40], RHIC [41,42], SLS [43], Tevatron [44], ALBA [45] and LHC [46,47].…”