| Paper |
Title |
Page |
| WEPC03 |
Secondary Electron Emission Beam Loss Monitor for LHC
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313 |
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- D. K. Kramer, B. Dehning, G. Ferioli, E. B. Holzer
CERN, Geneva
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Beam Loss Monitoring (BLM) system is a vital part of 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 modeled 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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| WEPC09 |
Classification of the LHC BLM Ionization Chamber
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328 |
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- M. Stockner, B. Dehning, C. Fabjan, E. B. Holzer
CERN, Geneva
- D. K. Kramer
TUL, Liberec
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The LHC beam loss monitoring (BLM) system must prevent the super conducting magnets from quenching and protect the machine components from damage. The main monitor type is an ionization chamber. About 4000 of them will be installed around the ring. The lost beam particles initiate hadronic showers through the magnets and other machine components. These shower particles are measured by the monitors installed on the outside of the accelerator equipment. For the calibration of the BLM system the signal response of the ionization chamber to all relevant particles types and energies (keV to TeV range) is simulated in GEANT4. For validation, the simulations are compared to measurements using protons, neutrons, photons, muons and mixed radiation fields at various energies and intensities. This paper will focus on the signal response of the ionization chamber to various particle types and energies including recombination effects in the chamber gas at high ionization densities.
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