BNL, Upton, Long Island, New York, USA
Measurements of amplitude-dependent tune shift are critical for understanding of nonlinear single particle dynamics in storage rings. The conventional method involves scanning of the kicker amplitude while having a short bunch train at the top of the kicker pulse. In this paper we present a novel, alternative technique that uses a long continuous bunch train, or a sequence of bunch trains, that are spread along the ring, such that different bunches experience different kick amplitudes with a single shot of a kicker pulse. With these beams, a curve of tune shift with amplitude can be extracted from the recently added new NSLS-II BPM feature called gated turn-by-turn (TbT) BPM data that can resolve bunches within a turn, either alone or together with a bunch-by-bunch BPM data. This technique is immune to pulse-to-pulse jitters and long-term machine drift.
BNL, Upton, Long Island, New York, USA
J B Optima, LLC, Rocky Point, USA
A fast new linear lattice characterization / correction method based on turn-by-turn (TbT) beam position monitor (BPM) data in storage rings has been recently developed and experimentally demonstrated at NSLS-II. This method performs least-square fitting iteratively on the 4 frequency components extracted from TbT data and dispersion functions. The fitting parameters include the errors for normal/skew quadrupole strength and 4 types of BPM errors (gain, roll, and deformation). The computation of the Jacobian matrix for this system is very fast as it utilizes analytical expressions derived from the resonance driving terms (RDT), from which the method name DTBLOC (Driving-Terms-Based Linear Optics Characterization/Correction) originates. At NSLS-II, a lattice corrected with DTBLOC was estimated to have beta-beating of <1%, dispersion errors of ~1 mm, and emittance coupling ratio on the order of 10-4.
