1. 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
TB – February 1, 2005

2. 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

3. 2- Radiation to components F
2- Radiation to components F.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);
TB – February 1, 2005

4. 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: &
TB – February 1, 2005

5. 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
TB – February 1, 2005

6. 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)
TB – February 1, 2005

7. 3- Monitors for induced activity
TB – February 1, 2005

8. 3- Monitors for induced activity
TB – February 1, 2005