| Paper |
Title |
Page |
| WEPC03 |
Secondary Electron Emission Beam Loss Monitor for LHC
|
313 |
| |
- D. K. Kramer, B. Dehning, G. Ferioli, E. B. Holzer
CERN, Geneva
|
|
| |
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.
|
|
| WEPC06 |
Single gain radiation tolerant LHC beam loss acquisition card
|
319 |
| |
- E. Effinger, B. Dehning, J. E. Emery, G. Ferioli, C. Zamantzas
CERN, Geneva
|
|
| |
The beam loss monitoring system is one of the most critical elements for the protection of the LHC. It must prevent the super conducting magnets from quenches and the machine components from damages, caused by beam losses. Ionization chambers and secondary emission based detectors are used on several locations around the ring. The sensors are producing a signal current, which is related to the losses. This current will be measured by a tunnel card, which acquires, digitizes and transmits the data via an optical link to the surface electronic. The usage of the system, for protection and tuning of the LHC and the scale of the LHC, imposed exceptional specifications of the dynamic range and radiation tolerance. The input dynamic allows measurements between 10pA and 1mA and its protected to high pulse of 1.5kV and its corresponding current. To cover this range, a current to frequency converter in combination with an ADC is used. The integrator output voltage is measured with an ADC to improve the resolution. The radiation tolerance required the adaption of conceptional design and a stringent selection components.
|
|
| WEPC09 |
Classification of the LHC BLM Ionization Chamber
|
328 |
| |
- M. Stockner, B. Dehning, C. Fabjan, E. B. Holzer
CERN, Geneva
- D. K. Kramer
TUL, Liberec
|
|
| |
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.
|
|