skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: First Measurement Results of the LHC Longitudinal Density Monitor

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1149345
Report Number(s):
SLAC-PUB-16058
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Journal Name: Conf.Proc.C110904:1105-1107,2011; Conference: Presented at the 2nd International Particle Accelerator Conference (IPAC-2011), San Sebastian, Spain, 4-9 Sep 2011
Country of Publication:
United States
Language:
English
Subject:
Accelerators,ACCPHY

Citation Formats

Jeff, A., /CERN /Liverpool U., Andersen, M., Bravin, E., Boccardi, A., Bozyigit, S., Lefevre, T., Rabiller, A., Roncarolo, F., /CERN, Welsch, C.P., /Cockcroft Inst. Accel. Sci. Tech, Fisher, A.S., and /SLAC. First Measurement Results of the LHC Longitudinal Density Monitor. United States: N. p., 2014. Web.
Jeff, A., /CERN /Liverpool U., Andersen, M., Bravin, E., Boccardi, A., Bozyigit, S., Lefevre, T., Rabiller, A., Roncarolo, F., /CERN, Welsch, C.P., /Cockcroft Inst. Accel. Sci. Tech, Fisher, A.S., & /SLAC. First Measurement Results of the LHC Longitudinal Density Monitor. United States.
Jeff, A., /CERN /Liverpool U., Andersen, M., Bravin, E., Boccardi, A., Bozyigit, S., Lefevre, T., Rabiller, A., Roncarolo, F., /CERN, Welsch, C.P., /Cockcroft Inst. Accel. Sci. Tech, Fisher, A.S., and /SLAC. Tue . "First Measurement Results of the LHC Longitudinal Density Monitor". United States. doi:. https://www.osti.gov/servlets/purl/1149345.
@article{osti_1149345,
title = {First Measurement Results of the LHC Longitudinal Density Monitor},
author = {Jeff, A. and /CERN /Liverpool U. and Andersen, M. and Bravin, E. and Boccardi, A. and Bozyigit, S. and Lefevre, T. and Rabiller, A. and Roncarolo, F. and /CERN and Welsch, C.P. and /Cockcroft Inst. Accel. Sci. Tech and Fisher, A.S. and /SLAC},
abstractNote = {},
doi = {},
journal = {Conf.Proc.C110904:1105-1107,2011},
number = ,
volume = ,
place = {United States},
year = {Tue Aug 05 00:00:00 EDT 2014},
month = {Tue Aug 05 00:00:00 EDT 2014}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • The Large Hadron Collider (LHC) at CERN is the world's largest particle accelerator. It is designed to accelerate and collide protons or heavy ions up to the center-of-mass energies of 14 TeV. Knowledge of the longitudinal distribution of particles is important for various aspects of accelerator operation, in particular to check the injection quality and to measure the proportion of charge outside the nominally filled bunches during the physics periods. In order to study this so-called ghost charge at levels very much smaller than the main bunches, a longitudinal profile measurement with a very high dynamic range is needed. Amore » new detector, the LHC Longitudinal Density Monitor (LDM) is a single-photon counting system measuring synchrotron light by means of an avalanche photodiode detector. The unprecedented energies reached in the LHC allow synchrotron light diagnostics to be used with both protons and heavy ions. A prototype was installed during the 2010 LHC run and was able to longitudinally profile the whole ring with a resolution close to the target of 50 ps. On-line correction for the effects of the detector deadtime, pile-up and afterpulsing allow a dynamic range of 105 to be achieved. First measurements with the LDM are presented here along with an analysis of its performance and an outlook for future upgrades.« less
  • Synchrotron radiation is currently used on the LHC for beam imaging and for monitoring the proton population in the 3 microsecond abort gap. In addition to these existing detectors, a study has been initiated to provide longitudinal density profiles of the LHC beams with a high dynamic range and a 50ps time resolution. This would allow for the precise measurement both of the bunch shape and the number of particles in the bunch tail or drifting into ghost bunches. A solution is proposed based on counting synchrotron light photons with two fast avalanche photo-diodes (APD) operated in Geiger mode. Onemore » is free-running but heavily attenuated and can be used to measure the core of the bunch. The other is much more sensitive, for measurement of the bunch tails, but must be gated off during the passage of the bunch to prevent the detector from being swamped. An algorithm is then applied to combine the two measurements and correct for the detector dead-time, afterpulsing and pile-up effects. Initial results from laboratory testing of this system are described here.« less
  • The Large Hadron Collider (LHC) beam-dump system relies on extraction kickers that need 3 microseconds to rise to their nominal field. Since particles transiting the kickers during the rise will not be dumped properly, the proton population in this interval must always remain below quench and damage limits. A specific monitor to measure the particle population of this gap has been designed based on the detection of synchrotron radiation using a gated photomultiplier. Since the quench and damage limits change with the beam energy, the acceptable population in the abort gap and the settings of the monitor must adapt accordingly.more » This paper presents the design of the monitor, the calibration procedure and the detector performance with beam.« less