Beam Loss Monitoring System for the LHC

Holzer, Eva Barbara; Dehning, B.; Effinger, Ewald; Emery, Jonathan D.; Ferioli, G.; Gonzalez, J.L.; Gschwendtner, Edda; Guaglio, G.; Hodgson, M; Kramer, Daniel; Leitner, R.; Ponce, Laurette; Prieto, V.; Stockner, M.; Zamantzas, Christos

doi:10.1109/nssmic.2005.1596433

Cited by 48 publications

(34 citation statements)

References 3 publications

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“…A local beam loss of a fraction of a few 10 −9 of full the beam might induce a quench and a fraction of a few 10 −4 risks to damage sensitive equipment. To avoid this, a beam loss monitor (BLM) system is in place [25,26] that can trigger a beam dump within 1-3 turns if the losses are too high. The beams are extracted by 15 horizontal kicker magnets, called MKDs, that go from zero to full field in about 3 μs or 3% of the revolution period [2].…”

Section: B Lhc Collimationmentioning

confidence: 99%

Calculations of safe collimator settings andβ*at the CERN Large Hadron Collider

Bruce

Assmann

Redaelli

2015

Phys. Rev. ST Accel. Beams

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The first run of the Large Hadron Collider (LHC) at CERN was very successful and resulted in important physics discoveries. One way of increasing the luminosity in a collider, which gave a very significant contribution to the LHC performance in the first run and can be used even if the beam intensity cannot be increased, is to decrease the transverse beam size at the interaction points by reducing the optical function β Ã . However, when doing so, the beam becomes larger in the final focusing system, which could expose its aperture to beam losses. For the LHC, which is designed to store beams with a total energy of 362 MJ, this is critical, since the loss of even a small fraction of the beam could cause a magnet quench or even damage. Therefore, the machine aperture has to be protected by the collimation system. The settings of the collimators constrain the maximum beam size that can be tolerated and therefore impose a lower limit on β Ã . In this paper, we present calculations to determine safe collimator settings and the resulting limit on β Ã , based on available aperture and operational stability of the machine. Our model was used to determine the LHC configurations in 2011 and 2012 and it was found that β Ã could be decreased significantly compared to the conservative model used in 2010. The gain in luminosity resulting from the decreased margins between collimators was more than a factor 2, and a further contribution from the use of realistic aperture estimates based on measurements was almost as large. This has played an essential role in the rapid and successful accumulation of experimental data in the LHC.

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Section: B Lhc Collimationmentioning

confidence: 99%

Calculations of safe collimator settings andβ*at the CERN Large Hadron Collider

Bruce

Assmann

Redaelli

2015

Phys. Rev. ST Accel. Beams

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“…The combination of these two factors means that a single pilot bunch of 5×10 9 protons is close to the damage level at 7TeV, while a loss of only 3×10 -7 of a nominal beam over 10ms can create a quench at 7TeV. In order to monitor and react to these losses the LHC will be equipped with a comprehensive beam loss monitoring system [4] capable of fulfilling the following criteria:…”

Section: Beam Loss Measurement Systemmentioning

confidence: 99%

LHC beam instrumentation

Jones

2007

2007 IEEE Particle Accelerator Conference (PAC)

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The LHC will have very tight tolerances on nearly all beam parameters. Their precise measurement is therefore very important for controlling and understanding the machine. With over two orders of magnitude higher stored beam energy than previous colliders, machine protection is also an issue, with any beam losses having to be closely monitored. This presentation will aim to give an overview of the beam instrumentation foreseen for the LHC together with the requirements for initial and nominal operation. A summary of the main systems will be followed by a discussion of areas where there have been recent advances, such as in the measurement of tune, chromaticity and coupling. AbstractThe LHC will have very tight tolerances on nearly all beam parameters. Their precise measurement is therefore very important for controlling and understanding the machine. With over two orders of magnitude higher stored beam energy than previous colliders, machine protection is also an issue, with any beam losses having to be closely monitored. This presentation will aim to give an overview of the beam instrumentation foreseen for the LHC together with the requirements for initial and nominal operation. A summary of the main systems will be followed by a discussion of areas where there have been recent advances, such as in the measurement of tune, chromaticity and coupling.

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“…T HE Beam Loss Monitoring system [1] is a vital part of the active LHC machine protection. It has to detect dangerous beam losses which could quench the superconductive magnets or even damage components of the accelerator.…”

Section: Blm Systemmentioning

confidence: 99%

Very high radiation detector for the LHC BLM system based on secondary electron emission

Kramer

Dehning

Holzer

et al. 2007

2007 IEEE Nuclear Science Symposium Conference Record

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Beam Loss Monitoring (BLM) system plays a vital role in the active protection of the LHC accelerators elements. It should provide the number of particles lost from the primary hadron beam by measuring the radiation field induced by their interaction with matter surrounding the beam pipe. The LHC BLM system will use ionization chambers as standard detectors but in the areas where very high dose rates are expected, the Secondary Emission Monitor (SEM) chambers will be employed because of their high linearity, low sensitivity and fast response. The SEM needs a high vacuum for proper operation and has to be functional for up to 20 years, therefore all the components were designed according to the UHV requirements and a getter pump was included. The SEM electrodes are made of Ti because of its Secondary Emission Yield (SEY) stability. The sensitivity of the SEM was modelled in Geant4 via the Photo-Absorption Ionization module together with custom parameterization of the very low energy secondary electron production. The prototypes were calibrated by proton beams in CERN PS Booster dump line, SPS transfer line and in PSI Optis line. The results were compared to the simulations.

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Beam Loss Monitoring System for the LHC

Cited by 48 publications

References 3 publications

Calculations of safe collimator settings andβ*at the CERN Large Hadron Collider

Calculations of safe collimator settings andβ*at the CERN Large Hadron Collider

LHC beam instrumentation

Very high radiation detector for the LHC BLM system based on secondary electron emission

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