Machine Protection and Operation for LHC

Since 2010 the Large Hadron Collider (LHC) is the accelerator with the highest stored energy per beam, with a record of 140 MJ at a beam energy of 4 TeV, almost a factor of 50 higher than other accelerators. With such a high stored energy, machine protection aspects set the boundary conditions for operation during all phases of the machine cycle. Only the low-intensity commissioning beams can be considered as relatively safe. This document discusses the interplay of machine operation and machine protection at the LHC, from commissioning to regular operation.Comment: 25 pages, contribution to the 2014 Joint International Accelerator School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14 Nov 201

Response Matrix and Dispersion Study of the TI2 Transfer Line

The optics of the TI2 transfer line was studied with beam trajectories during its commissioning in October 2007. The optics and the quality of the steering magnets and of the beam position monitors were determined from steering magnet response measurements. A strength error of the main quadrupoles was identified with this technique. The dispersion was measured and found to be close to the nominal value

Study of the TI 8 optics and beam stability based on beam trajectories

The optics and the stability of the SPS-LHC transfer line TI 8 was studied with beam trajectories during its commissioning in October 2004. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. A large setting error of a quadrupole was identified with this technique, as well as a 1% phase advance error in the vertical plane. Residual coupling between the planes was evaluated using high statistics samples of trajectories. The same high statistics sample were analysed using the Model Independent Analysis technique to understand possible sources of trajectory movements. The transfer line was found to be very stable and the dominant source of position jitter seems to be due to the ripple of the extraction septum

Protection Controls for High Power Accelerators

The next generation hadron accelerators will operate with MW beams or store beams with an energy of many 100 MJ. Such accelerators must be protected by fast and very reliable interlock systems to avoid damage due to uncontrolled beam loss. Machine protection will constrain operation, but some operational flexibility is still required for commissioning and performance optimization. This is a substantial challenge for control systems and application programs. New tools are developed to face those challenges: critical settings management, software interlocks, role based access to equipment, automatic accelerator mode recognition etc. This talk presents some of the challenges and tools. Experience with novel approaches are discussed

Observation of Radial Ring Deformations using Closed Orbits at LEP

With a circumference of 27.7 km the LEP ring is subject to long large geological deformations which must be monitored accurately to guarantee a sufficient precision on the beam energy for the LEP experiments. Changes of the LEP circimference can be extracted from the radial position of the closed orbits with an accurancy better than 0.1 mm. The observed tidal deformations with amplitudes of up to 1 mm were found to be in good agreement with geological models. Besides such periodic effects seasonalcircumference variations of 2 mm are also observed. A summary of measurements collected between 1993 and 1998 is presented