“…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].…”
Measurement and correction of charged particle beam optics have been a major concern since the advent of strong focusing synchrotron accelerators. Traditionally, particle colliders have led the development of optics control based on turn-by-turn beam centroid measurements, while lepton storage rings have focused on closed-orbit-response matrix techniques. Recently, considerable efforts are being invested in comparing these techniques at different synchrotron radiation sources and colliders. An emerging class of less invasive techniques based on the optimization of performance-related observables is demonstrating a great potential. In this paper, a review of existing techniques is presented highlighting comparisons, relative merits and limitations.
“…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].…”
Measurement and correction of charged particle beam optics have been a major concern since the advent of strong focusing synchrotron accelerators. Traditionally, particle colliders have led the development of optics control based on turn-by-turn beam centroid measurements, while lepton storage rings have focused on closed-orbit-response matrix techniques. Recently, considerable efforts are being invested in comparing these techniques at different synchrotron radiation sources and colliders. An emerging class of less invasive techniques based on the optimization of performance-related observables is demonstrating a great potential. In this paper, a review of existing techniques is presented highlighting comparisons, relative merits and limitations.
“…In LEP for example, the pick-ups are physically attached and aligned to the nearby quadrupole. Nevertheless errors do occur in construction and installation and it is very important to be able to measure and correct [8] any deviations between the pick-ups and quadrupoles. A schematic which explains the technique [9] used to measure such deviations is shown in Figure 3.…”
Measurements of the LEP beam parameters have been fundamental to performance improvements and this report describes the principles and techniques involved in the beam instrumentation systems of LEP.
“…For sextupoles, the skew quadrupole trim, (maximum strength K sq =0.01 m -1 ), is used. Since the damping ring has, by design, a lifetime of about 2 minutes, it is hard to use sine wave field modulation as done previously [6,7,8]. BPM data averaging and filtering is used.…”
The KEK Accelerator Test Facility (ATF) damping ring is a prototype low emittance source for the NLC/JLC linear collider. To achieve the goal normalized vertical emittance γε y = 20 nm-rad, magnet placement accuracy better than 30 µm must be achieved. Accurate beam-based alignment (BBA) is required. The ATF arc optics uses a FOBO cell with two horizontally focusing quadrupoles, two sextupoles and a horizontally defocusing gradient dipole, all of which must be aligned with BBA. BBA at ATF uses the quadrupole and sextupole trim windings to find the trajectory through the center of each magnet. The results can be interpreted to assess the accuracy of the mechanical alignment and the beam position monitor offsets. The KEK Accelerator Test Facility (ATF) damping ring is a prototype low emittance source for the NLC/JLC linear collider. To achieve the goal normalized vertical emittance γε y = 20 nm-rad, magnet placement accuracy better than 30 µm must be achieved. Accurate beam-based alignment (BBA) is required. The ATF arc optics uses a FOBO cell with two horizontally focusing quadrupoles, two sextupoles and a horizontally defocusing gradient dipole, all of which must be aligned with BBA. BBA at ATF uses the quadrupole and sextupole trim windings to find the trajectory through the center of each magnet. The results can be interpreted to assess the accuracy of the mechanical alignment and the beam position monitor offsets.
Presented at the Eighth European Particle Accelerator Conference
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