1. Passive Dosimeters for the LHC Experiments M.Moll, M.Glaser, C.Joram CERN – PH – TA1 – SD (http://cern.ch/ssd) F.Ravotti CERN – TS -LEA RADMON – Technical meeting – 22.July 2004  Why is PH-TA1-SD involved?  Organization of working group (as of 4/2004)  Workplan (as of 4/2004)  Aim of todays meeting … I have 4 more transparencies:

2. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -2- Why is PH-TA1-SD involved?  PH-TA1-SD proposes to work on the evaluation and development of passive and active radiation monitors in collaboration with the LHC experiments with the Motivation to (1) Continue and extend dosimeter developments for the IRRAD facilities to serve all LHC experiments. (2) Keep the Student Federico Ravotti attached to our group  “Deal”: – The LHC experiments provide financing for a doctoral student and TS-LEA the quota – PH-TA1-SD invests manpower into the project (M.Moll and M.Glaser)  Federico Ravotti is doctoral student in TS-LEA (attached to our section) since July 2004 April 2004 July 2004

3. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -3- Organization of the working group (Transparency from April Meeting … just filled in some names)  PH-TA1-SD (M.Moll, M.Glaser, F.Ravotti) + external collaborators together with the Experiments:  Design, develop and provide dosimeters and dosimeter module(s)  Coordination of the common efforts within the dosimeter group  Design of front-end electronics (if OSL needed)  Design of basic prototype readout card with standardized output signals  LHC Experiments  Clarification of the specific requirements of the Experiment  Integration into the Experiment (space, mounting, cabling, power supply,..)  Experiment specific detector control interface  Provide one responsible for these activities: Alice Marc Tavlet (CERN) ATLAS Marko Mikuz (Ljubljana) and Per Grafstroem (CERN) CMS Alick MacPherson (CERN) LHCb Doris Eckstein (CERN)

4. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -4- A possible work plan (Transparency from April meeting)  6/2004 Specification of requirements  Each LHC Experiment documents about its specific requirements  Written agreement between Experiments and dosimeter working group specifying: responsibilities work plan and milestones. A work plan could then look like:  End of 2004  First prototype of an integrated board tested  First prototype of basic readout system ready  Integration into experiments clarified (positions, cabling, signal type)  Middle of 2005  Components for the radiation monitoring boards ‘fixed’  End of 2005  Prototypes of integrated boards with full readout electronics tested  Series production ready to start  Beginning 2006  First boards ready (Is this too late?)  2006: Series of radiation tests of full dosimeter boards (final calibration)

5. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -5- Aim of today's meeting  Update on our activities (PH-TA1-SD)  Maurice Glaser  Which kind of passive dosimeters are used at CERN ? Which infrastructure is available?  Alanine (Helmut Vincke, CS-RP)  RPLs (Helmut Vincke, CS-RP)  TLDs (Marco Silari, Jacques Wolf, CS-RP)  Reports of the LHC experiments radiation monitoring contact persons  Discussion on: - type of dosimeters - number of needed dosimeters  Next meeting – Deadline for providing ourselves with some more detailed information about a) interest to join a common activity on passive dosimeters b) type and number of dosimeters needed The aim of the meeting is to understand which and how many passive dosimeters will be needed by the LHC experiments in order to possibly launch a common purchase of dosimeters respectively a common activity leading to the set-up of the required infrastructure to read them. } Thank you!

6. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -6- …. towards LHC Rough estimate of doses/year

7. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -7- Spare Transparencies Some transparencies shown in April 2004

8. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -8- Radiation Monitoring Technologies - Active devices -  RADFETs  different gate oxide thicknesses (change of sensitivity)  different gate voltages (change of sensitivity)  different producers, different packaging (change of response, fading)  OSLs - Optical Stimulated Luminescence  doping of the substrate Standard devices (“pure” OSLs) sensitive to ionizing radiation Boron doping: increased sensitivity to thermal neutrons Mixing with Polyethylene: increased sensitivity to fast neutrons  Reverse biased Pin diodes  Equivalent principle to the Inner Silicon Tracker detectors  different size and thickness, epitaxial detectors  different doping levels, oxygenated  Forward biased Pin (photo) diodes  commercial devices – little flexibility  New: Semi-commercial source (see presentation of Maurice) … most of the ‘active devices’ can be used as passive dosimeters …. just to remind you: Devices and their flexibility

9. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -9- Radiation Monitoring Technologies - Some passive devices -  Polymer-Alanine dosimeters (PADs)  Irradiation breaks up bonds and forms free radicals  EPR can quantify the number of free spins  Radiophotoluminescent glass dosimeters (RPLs)  Ionization charges color centers  UV light excitation releases visible light  Thermoluminescence dosimeters (TLDs)  Emission of light when the material is heated after irradiation  Can be reused after reading (heating)  7 LiF for ionizing radiation  6 LiF for ionizing radiation and neutrons (n,  ) capture  Hydrogen Pressure Dosimeters (HPDs)  Polyethylene in a sealed quartz container  Disintegration of the polyethylene by irradiation releases hydrogen  Hydrogen gas pressure is proportional to the received dose  LiF Crystals  Formation of color centers increases light absorption  Activation foils  Nuclear reaction form radioactive isotopes  …. many more, including many active dosimeters:  RADFETs, PIN diodes, OSLs …. Note: CERN has a High-Level Dosimetry group in SC(TIS)/RP (H.Vincke, I.Brunner et al.)! Figure: I.Floret (TIS/RP)

10. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -10- Passive Dosimeters TLDLiF crystalPAD (Alanine)Dye filmsRPLHPD Dose Range 10  Gy to 100 Gy 1KGy to 100MGy 10Gy to 1MGy 1-250Gy 10KGy-1MGy 100mGy to 1MGy 10 KGy to 10MGy Readout technique Heating; Light emission Light absorption EPRDensitometerUV (365nm); Light emission Pressure measurement Commentstandard device Thermal neutron measurement Very small Data: I.Floret (SC/RP – High level dosimetry)

11. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -11- Ionization (DOSE)Displacement in Silicon (Particle Fluence) Instantaneous Dose Rate RADFETOSLPhoto-diodePin-diode integratingintegrating, erased by readout integrating instantaneous current Operationunbiaseddarkunbiased~ 100V (reverse) Read-out I DS =10-200  A (~5s) IR 800-1500nm1mA (forward, ~200 ms) ~100V (reverse) SignalV DS = 1-20VLight 500-700nmForward biasLeakage currentInduced current Range10mGy-10KGy10mGy – 100Gy10 12 -10 15 cm -2 10 11 -10 14 cm -2 Sensitivity1-100 mV/Gy Decreasing with integrated dose … depending on photo sensor… ~150mV / 10 12 n/cm 2 ~1  A / 10 12 n/cm 2 ~1nA / 50  Gy/s Positive has already been used in HEP erasable, sensitivity does not decrease, can be adopted to measure fast and thermal neutrons, used in satellites COTS, very low cost has already been used in HEP, high sensitivity in low fluence range has already been used in HEP; beamdump trigger (BCM activities) Negative signal needs T correction, non- linearity New technology in HEP, needs development Annealing not well charact., signal needs T correction annealing difficult to simulate, signal needs T correction - background current increasing with lifetime (irradiation) Costs for one mounted device ~140 CHF~200€ (non commercial) ~ 2 €~ 150 € (??) (non commercial) Fluence to Dose (MIP): 2.666x10 -10 Gy cm 2

12. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -12- “Our Mandate”  Develop and characterize dosimeter boards with on-line readout for and together with the LHC experiments  Boards being as flexible as possible (dose/fluence range, sensitivity, particle type, shape of board …) in order to allow and optimal adoption to specific sub-detector environments.  Output signal compatible to all Detector Control Systems  Provide the dosimeter boards and/or active dosimeters to the experiments  Support the experiments in qualifying passive dosimeters  Impose our radiation monitoring concepts on the experiments  Integrate the dosimeters / dosimeter boards into the experiments Our mandate: Not our mandate:

13. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -13- Towards a workplan (1/2) …. some questions to be discussed  Measurement for which purpose?  (Beam dump?  Beam Condition Monitor Group)  Detector protection (e.g. switching off a sub-detector) ?  Test of radiation shielding?  Long term monitoring?  Analysis of beam accidents?  Instantaneous dose rate measurement needed ?  trigger on too high dose rate/flux needed? if so, in which time scale?  Measure which kind of information?  ionizing dose  displacement damage  thermal neutrons  Dose/Fluence range and sensitivity needed?  Active and/or passive devices ?  readout cycle? / replacement cycle?

14. RADMON Michael Moll - CERN PH-TA1-SD – RADMON Technical Meeting, July 22, 2004 -14- Towards a workplan (2/2) … some questions to be discussed  Number of monitoring modules?  Environment of module?  Temperature and Temperature stability?  Space constrains?  Maximum size of sensor module?  Distance between sensor and readout electronics (cable length)?  Lifetime of modules?  Will we be able to repair/replace/upgrade them?  Readout:  Radiation hard electronics on-board needed (OSL needed)?  Specific restrictions due to the individual experiments?  Which kind of signals can be accepted by the detector control system of the Experiment?  Deadlines  Decision about size of the module  Decision about number of cables  Decision about signal type  Installation deadline  Service/Maintenance after installation  Which kind of service/maintenance is expected after installation?