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Radiation Monitoring in LHC Experiments. Three different aims: measurement of Beam-conditions ( beam abort) Radiation to components during operation TID ≠ NID high dose rates monitors high doses passive dosimeters Remnant radioactivity during personnel access
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Radiation Monitoring in LHC Experiments Three different aims: measurement of Beam-conditions ( beam abort) Radiation to components during operation TID ≠ NID high dose rates monitors high doses passive dosimeters Remnant radioactivity during personnel access only gammas, low dose rates ionizing chambers
1- Beam-Condition Monitoring • Fast active monitors (sensors) • Positioned close to the beam pipe • Real-time radiation monitoring to detect ‘anomalies’ and initiate protection procedures* for detector subsystems at the onset of beam instabilities and accidents * still to be discussed; alarm, beam abort, detector(s) shut-down via DSS… (?)
2- Radiation to componentsF.Ravotti’s presentation at Rad-Mon meeting Dec.2 • Total Ionizing Dose (TID) measurement: • Radiation Field Effect Transistors (RadFETs); • Optically Stimulated Luminescent materials (OSLs); • 1-MeV neutron equivalent fluence (Feq) measurement: • p-i-n diodes & PAD structures; • Thermal neutrons detection (Fth);
2- Radiation to components F.Ravotti’s Conclusions • Several techniques for the ACTIVEmonitoring of TID, FeqandFth • All presented devices are reliable and were characterized in various radiation fields; • Most of them are commonly used in Medicine and Space: customization and calibration for CERN applications needed; • ACTIVE monitors are also PASSIVE dosimeters More on: http://cern.ch/lhc-expt-radmon & http://www.cern.ch/irradiation
2- Radiation to components, Passive Dosimeters for TID • PAD = Polymer-Alanine Dosimeters 1 Gy – 200 kGy adapted for plastics ; not well adapted to Si • RPL = radio-photo-luminescent dosimeters 0.1 Gy – 1 MGy • TLD = thermo-luminescent dosimeters 1 mGy – 1 Gy can also discriminate thermal neutrons • HPD = Hydrogen-pressure dosimeters 10 kGy – 10 MGy adapted for plastics ; not well adapted to Si + some active monitors adapted for Si 1 cGy – 1 kGy
2- Radiation to components, Passive Dosi. for Neutrons • PIN-Diode , several type, well adapted to Si • Activation detectors = foils of pure metal which become radioactive Passive Active Dosimeters • Active = online measurement of dose rates (to be cabled) • Passive = offline measurement of doses (no cable needed)
