Transcript Radiation Monitoring in LHC Experiments

Radiation Monitoring
in LHC Experiments
Three different aims: measurement of
1. Beam-conditions ( beam abort)
2. Radiation to components during operation
- TID ≠ NID
- high dose rates  monitors
- high doses  passive dosimeters
3.
Remnant radioactivity during personnel access
- only gammas, low dose rates  ionizing chambers
TB – February 1, 2005
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… (?)
TB – February 1, 2005
2- Radiation to components
F.Ravotti’s presentation at
Rad-Mon meeting Dec.2
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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);
TB – February 1, 2005
2- Radiation to components
F.Ravotti’s Conclusions
 Several techniques for the ACTIVE monitoring of
TID, Feq and Fth
 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
TB – February 1, 2005
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
TB – February 1, 2005
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
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Active = online measurement of dose rates (to be cabled)
Passive = offline measurement of doses (no cable needed)
TB – February 1, 2005
3- Monitors for induced activity
TB – February 1, 2005
3- Monitors for induced activity
TB – February 1, 2005