The LHC collimator controls architecture - design and beam tests

Aßmann

Phys. Rev. ST Accel. Beams

et al. 2012

Full beam-based alignment of the LHC collimation system was a time-consuming procedure (up to 28 hours) as the collimators were set up manually. A yearly alignment campaign has been sufficient for now, although in the future due to tighter tolerances this may lead to a decrease in the cleaning efficiency if machine parameters such as the beam orbit drift over time. Automating the collimator setup procedure can reduce the beam time for collimator setup and allow for more frequent alignments, therefore reducing the risk of performance degradation. This article describes the design and testing of a semiautomatic algorithm as a first step towards a fully automatic setup procedure. The parameters used to measure the accuracy and performance of the alignment are defined and determined from experimental data. A comparison of these measured parameters at 450 GeV and 3.5 TeV with manual and semiautomatic alignment is provided.

Section: Semiautomatic Collimator Jaw Alignment Algorithmmentioning

confidence: 99%

“…A collimator jaw is set up to the beam halo when a clear loss spike is observed in the BLM signal after a jaw movement towards the beam. The alignment is done remotely from the CERN Control Center (CCC) using a top-level application implemented in Java [14,15].…”

Section: Introductionmentioning

confidence: 99%

Semiautomatic beam-based LHC collimator alignment

Aßmann

Phys. Rev. ST Accel. Beams

et al. 2012

“…(2) was implemented into the top-level Java collimator control application [10]. Testing was carried out during alignments held in March 2012.…”

Section: Resultsmentioning

confidence: 99%

Automatic Threshold Selection for BLM Signals during LHC Collimator Beam-Based Alignment

Assmann

2012 Sixth UKSim/AMSS European Symposium on Computer Modeling and Simulation

et al. 2012

Abstract-The Large Hadron Collider at CERN is the largest high-energy particle accelerator in the world. Proton beams are currently collided at an energy of 4 TeV per beam to investigate the fundamental elements of matter. The collider is equipped with a collimation system to ensure that potentially destructive halo particles are absorbed before they hit vulnerable elements. Beam-based alignment of the collimators is required to ensure that they are positioned for maximum cleaning efficiency. The alignment procedure relies on feedback from Beam Loss Monitors, and is currently being automated to speed it up. This paper describes a method for automatically selecting a threshold for the beam loss signal during alignment, based on an empirical analysis of collimator alignment data over one year of operation. The results achieved with threshold selection during alignments at 4 TeV are presented.

“…If G ¼ G min , the algorithm attempts to continue the alignment by moving the jaw closest to the beam outwards, rather than the jaw farthest from the beam inwards. The alignment algorithm was implemented in the existing Java application used to control the prototype collimator in SPS [21]. The algorithm implementation is flexible and allows the use of both the linearized beam axis equation and the polynomial correction.…”

Section: A Algorithmmentioning

confidence: 99%

Successive approximation algorithm for beam-position-monitor-based LHC collimator alignment

Nosych

Phys. Rev. ST Accel. Beams

et al. 2014

Collimators with embedded beam position monitor (BPM) button electrodes will be installed in the Large Hadron Collider (LHC) during the current long shutdown period. For the subsequent operation, BPMs will allow the collimator jaws to be kept centered around the beam orbit. In this manner, a better beam cleaning efficiency and machine protection can be provided at unprecedented higher beam energies and intensities. A collimator alignment algorithm is proposed to center the jaws automatically around the beam. The algorithm is based on successive approximation and takes into account a correction of the nonlinear BPM sensitivity to beam displacement and an asymmetry of the electronic channels processing the BPM electrode signals. A software implementation was tested with a prototype collimator in the Super Proton Synchrotron. This paper presents results of the tests along with some considerations for eventual operation in the LHC.