Radiation Monitoring Technologies for the LHC

Radiation Monitoring Technologies for the LHCFederico Ravotti (TS-LEA-CMS)

Maurice Glaser (PH-TA1-SD) Active Radiation Monitors

RadFETs; OSLs; p-i-n diodes; Passive Radiation Monitors

LHC Exp. RadMon Working Group 06/04/2004

Active Radiation Monitors RadFETsp-i-n diodesBuild-up of charge in MOSFETs SiO2 layer (Ionizing Dose) (integrating measurement).Charge buildup in sensitive material detrapped by IR stimulation (Ionizing Dose) (instantaneous measurement).Bulk damage in high r Si-base (particle fluence) (integrating measurement).Optically StimulatedLuminescence (OSL)


RadFETs General e-/h+ pair generation; e-/h+ pair recombination; e- (~psec) / h+ (~sec) transport; hole trapping; Interface state delayed buildup.

Build-up of charge in SiO2 increase of the p-MOS Threshold Voltage integrated Dose MeasurementSthreshold ~ 1 cGy; S decreasing over .Sub-linearResponsesg responses for different tox


RadFETs DetailsDVth= (particle type, energy, incidence angle, ..);DVth= (packaging) in neutron field.

Care has to be taken in the choice of the proper calibration & packaging for a neutron/HEP enriched radiation environment!MOS exposed in zero bias mode;(2-wires only readout, bigger dynamic range)Long-distance readout of Vth after IDS bias (seconds time-scale);Operation at MTC: if T ~ constant, correction it is not needed;Good reproducibility of the results producer selection.


RadFETs at CERNg-ray calibrations (zero bias mode) from producers & measured at CERNBare die chips ~ 1-2 mm2 dimension !


RadFETs InstabilitiesRead-time instability (Drift-up) during readout, small error (< 5 %) avoided by fixing the readout protocol.Devices have to be selected on the basis of their annealing behaviors Isochronal AnnealingTrapped charge annealing prompt time-scale (i.e. hours), can induce big errors especially at LDR (> 20 % in a few hrs).Interface states generation delayed time-scale (i.e. years), can strongly affect the devices long-time behaviour.


RadFETs IsochronesScaling annealing t annealing T;Annealing periods at increasing T;Charge annealing is oxide (i.e. manufacture) dependent;Simple and quick way to identify not suitable behaviours;Informations about charge spectrum in SiO2.Regular behavioursNot suitable behavioursData from CERN & CEM2 - Montpellier


OSLs General(collaboration between CERN and CEM2 Montpellier University) e-/h+ pair generation and trapping; Infrared stimulation (800-1500 nm); Visible emission (500-700 nm) Dose;After L.DusseauMaterial used at CERN: SrS doped Sthreshold = 100 mGy; S dependent on readout electronics.Linear response(< 100 Gy)The readout completely reset the sensitive material !24 GeV/c protons (IRRAD1)


OSLs DetailsRadiation independent response (X, g, p, p, e, ..);OSL materials characterized with off-line measurements (test bench);Readout process takes 10-15 seconds;Very low fading at room temperature (to be verified);Pure OSL does not suffer radiation damage;n-OSL tested for the first time: first campaign with 5 mm2 samples performed in 2 different neutron environments.OSL Test bench


Neutron-Sensitive OSLs 1The pure OSL material is sensitive to the Ionizing radiation only;The n-OSLs show a 20-times increased sensitivity.Boron doping affects fading behaviour ?OSLs with enhanced neutron-sensitivity:10B(n,a)7Li Thermal neutrons 1H(n,p)1H Fast neutronsOSL pureOSL+BOSL+PEOSL+PE+B


Neutron-Sensitive OSLs 2CERN OSLLjubljana OSLThermalFast1 % 99 % 89 % CERN-PS IRRAD2 Facility(FLUKA)Ljubljana Reactor- Activation measurements -87 % 13 % 3 % 97 % 11 %


OSL on-line approachesThe sensor works in HEP environment(CERN PS-IRRAD1)OSLs deposed on GaAsP photodiodesOptical-Fiber systemOSL material + Radhard electronics = RADHARD INTEGRATED SENSOROSLDesigned for SpaceIntl. Space Station, CUBESAT / PROBA2 (50 mGy 100 Gy)3 cm x 1.5 cmOSLs at the edge of a long optical fiber LED/PD not damaged by radiations.OSL pureOSL+BOSL+ParaffinSupport for off-line readout


p-i-n diodes General Displacement damage in high r Si-base;Macroscopic Effects: Resistivity increase F (forward bias); Leakage current increase F (reverse bias); Forward bias operation:Fast current pulse (~ms), VF on-line readout over long-distances (2-wires);Sensitivity = (w ):w =1.2 mm S ~ 1 mV / 108 cm-2 ; Frange = 108 1012 cm-2 (Feq)w = 0.3 mm S ~ 1.5 mV / 1010 cm-2; Frange = 1012 1014 cm-2 (Feq)Commercial diodes BPW34F characterized in 2003.


BPW34F Osram diodesHigh-fluence measurements: - Linear behaviour (Feq): 1.0x1012 4.0x1014 cm-2 - Sensitivity (Feq): 1.5 mV / 1010 cm-2Strong T dependence: Tc = -5 %C-1;Thermal annealing:< 10 % in the first 14 days.Max DT over irradiations: 0.83 C Response Curve (CERN-PS IRRAD1 & IRRAD2 facilities)(preliminary)


Pad structuresAfter M.MollOff-line measurements after annealing (4 min 80 C)Reverse bias operation:(see next presentations)

ST, Italy Pad structure of 0.25 cm2 for bulk damage studies;Off-line characterization; Very wide fluence range;Complex Annealing behaviour;Possible on-line implementation for high-sensitivity fluence measurements


Passive Radiation Monitors Polymer-Alanine (PAD) & Radio-Photo Luminescent (RPL) Dosimeters: Formation of stable free radicals/color center after irradiation; Readout by CERN SC/RP (TIS); Well known dosimetry systems. [NIM-B 83 (1993) pp. 181-188]Calibration campaign 2003 in the mixed g/n field of CERN-PS IRRAD2 facilityGafchromic Sensitive Films Formation of a stable dye polymer after irradiation; Optical readout (color density); Different sensitivities/ranges24 GeV/c protons (HD-810)


Summary RadFETs:Responses in HEP/n environments fully characterized. Isochronal annealing studies are ongoing with setup in Lab. 14-R-012.OSLs:Responses HEP fully characterized. Neutron-sensitive materials under development.Annealing studies & test on new on-line configurations are planned.BPW34F:Particle responses fully characterized. More on Annealing & readout procedure.Pad Structures:Particle responses well known. Looking forward for an on-line readout. Passive Monitors: Daily used in the operation of the CERN-PS Irradiation Facilities.


and finally More on Acknowledgments p-i-n diodes; RadFETs HEP/n responses, packaging dependence, annealing & instabilities:CERN Technical Note EST/LEA/2003-03, July 2003 (EDMS No. 394670)RadFETs fast-neutron response: Paper in preparation for NSS Rome, 2004Special neutron-sensitive OSLs: Paper submitted to RADECS Madrid, 2004 & CERN Preprints collectionIntegration Issues: CERN-PH-EP-2004-04, February 2004 (Presented at NSREC Atlanta, 2004)Passive technologies, PS Irradiation facilities: http://www.cern.ch/irradiation- M. Moll, C. Joram, E. Tsesmelis from CERN; - L. Dusseau, J R. Vaill from CEM2 - Montpellier University;- G. Sarrabayrouse (CNRS, France), A. Holmes-Siedle (REM, England) for their support in RadFETs studies;- I. Mandic and M. Mikuz from the Josef Stefan Institute, Ljubljana, Slovenia.


Neutrons Cross-sections


Readout parameters

Active DosimeterExternal biasReadout InputPre-irradiation outputAfter irradiation outputReference Val.RadFETsnot neededDC i = 10 mA 160 mA depending on MTC1 V to 3 V depending on tox~ 10 V (1.6 mm) ~ 4 V (0.25 mm)100 Gy~ 41 V (0.25 mm)100k GyOSLs (2003 sensor) 5V (on-board electronics)10-15 sec DC stimulation on LED with i = 50 mAnoise ~ 200 mV with Gout=10~ 2 V with Gout=10100 GyBPW34F (w ~ 300 mm)not neededFast pulse (180 ms) with Forward i = 1 mA0.5 V~ 50 V (linear operation)4.x1014 cm-2 (Feq)Pad structuresnot neededLeakage current at full depletion V = 100 V ?~ nA order~ mA order1014 1015 cm-2 (Feq)PT100 Temp Probenot neededDC i = 1 mA0.1 V (0 C)##


Radiation Monitoring Technologies for the LHC

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