Radiation Monitoring Technologies for the LHC Active Radiation Monitors RadFETs; OSLs; p-i-n diodes; Passive Radiation Monitors Federico Ravotti (TS-LEA-CMS) Maurice Glaser (PH-TA1-SD)

Active Radiation Monitors RadFETs Build-up of charge in MOSFETs SiO2 layer (Ionizing Dose)  (integrating measurement). p-i-n diodes Bulk damage in high r Si-base (particle fluence)  (integrating measurement). Optically Stimulated Luminescence (OSL) Charge buildup in sensitive material detrapped by IR stimulation (Ionizing Dose)  (instantaneous measurement). F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

RadFETs General Sthreshold ~ 1 cGy; S decreasing over ò. e-/h+ pair generation; e-/h+ pair recombination; e- (~psec) / h+ (~sec) transport; hole trapping; Interface state delayed buildup. g responses for different tox Build-up of charge in SiO2 increase of the p-MOS Threshold Voltage  integrated Dose Measurement Sthreshold ~ 1 cGy; S decreasing over ò. Sub-linear Responses F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

RadFETs Details DVth= ¦ (particle type, energy, incidence angle, ..); 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. DVth= ¦ (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! F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

LHC Exp. RadMon Working Group 06/04/2004 RadFETs at CERN g-ray calibrations (“zero bias” mode) from producers & measured at CERN Bare die chips ~ 1-2 mm2 dimension ! F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

RadFETs Instabilities “Read-time” instability (“Drift-up”)  during readout, small error (< 5 %) avoided by fixing the readout protocol. Trapped 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. Devices have to be selected on the basis of their annealing behaviors  Isochronal Annealing F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

LHC Exp. RadMon Working Group 06/04/2004 RadFETs Isochrones Regular behaviours Scaling annealing t Û 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. Data from CERN & CEM2 - Montpellier Not suitable behaviours F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

OSLs General Sthreshold = 100 mGy; (collaboration between CERN and CEM2 – Montpellier University) e-/h+ pair generation and trapping; Infrared stimulation (800-1500 nm); Visible emission (500-700 nm) µ Dose; 24 GeV/c protons (IRRAD1) After L.Dusseau Material used at CERN: SrS doped The readout completely reset the sensitive material ! Linear response (< 100 Gy) Sthreshold = 100 mGy; S dependent on readout electronics. F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

LHC Exp. RadMon Working Group 06/04/2004 OSLs Details Radiation 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; OSL Test bench n-OSL tested for the first time: first campaign with 5 mm2 samples performed in 2 different neutron environments. F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

Neutron-Sensitive OSLs 1 OSLs with enhanced neutron-sensitivity: 10B(n,a)7Li  Thermal neutrons 1H(n,p)1H  Fast neutrons OSL pure OSL+PE OSL+B OSL+PE+B The pure OSL material is sensitive to the Ionizing radiation only; The n-OSLs show a 20-times increased sensitivity. Boron doping affects fading behaviour ? F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

Neutron-Sensitive OSLs 2 89 % CERN-PS IRRAD2 Facility (FLUKA) 99 % 1 % 11 % Ljubljana Reactor - Activation measurements - Thermal Fast CERN OSL 3 % 97 % Ljubljana OSL 87 % 13 % F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

OSL on-line approaches OSLs deposed on GaAsP photodiodes OSL+B OSL OSL pure Designed for Space Intl. Space Station, CUBESAT / PROBA2 (50 mGy – 100 Gy) 3 cm x 1.5 cm OSL material + Radhard electronics = RADHARD INTEGRATED SENSOR OSL+Paraffin Support for off-line readout Optical-Fiber system The sensor works in HEP environment (CERN PS-IRRAD1) OSLs at the edge of a long optical fiber  LED/PD not damaged by radiations. 2003 2004 F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

p-i-n diodes General Forward bias operation: Displacement damage in high r Si-base; Macroscopic Effects: Resistivity increase µ F (forward bias); Leakage current increase µ 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. F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

BPW34F Osram diodes Response Curve High-fluence measurements: (CERN-PS IRRAD1 & IRRAD2 facilities) High-fluence measurements: - Linear behaviour (Feq): 1.0x1012 ÷ 4.0x1014 cm-2 - Sensitivity (Feq): 1.5 mV / 1010 cm-2 Strong T dependence: Tc = -5 %·ºC-1; Thermal annealing: < 10 % in the first 14 days. (preliminary) Max DT over irradiations: ± 0.83 ºC F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

“Pad” structures Reverse bias operation: Off-line measurements after annealing (4 min 80 ºC) 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 After M.Moll F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

Passive Radiation Monitors Polymer-Alanine (PAD) & Radio-Photo Luminescent (RPL) Dosimeters: Calibration campaign 2003 in the mixed g/n field of CERN-PS IRRAD2 facility 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] Gafchromicâ Sensitive Films Formation of a stable dye polymer after irradiation; Optical readout (color density); Different sensitivities/ranges 24 GeV/c protons (HD-810) F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

LHC Exp. RadMon Working Group 06/04/2004 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. F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

LHC Exp. RadMon Working Group 06/04/2004 and finally … More on … 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, 2004 Special neutron-sensitive OSLs: Paper submitted to RADECS Madrid, 2004 & CERN Preprints collection Integration Issues: CERN-PH-EP-2004-04, February 2004 (Presented at NSREC Atlanta, 2004) Passive technologies, PS Irradiation facilities: http://www.cern.ch/irradiation Acknowledgments … - M. Moll, C. Joram, E. Tsesmelis from CERN; - L. Dusseau, J R. Vaillé 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. F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

Neutrons Cross-sections F.Ravotti LHC Exp. RadMon Working Group 06/04/2004

Readout parameters F.Ravotti LHC Exp. RadMon Working Group 06/04/2004 Active Dosimeter External bias Readout Input Pre-irradiation output After irradiation output   Reference Val. RadFETs not needed DC i = 10 mA ÷ 160 mA depending on MTC 1 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 Gy OSLs (2003 sensor) ± 5V (on-board electronics) 10-15 sec DC stimulation on LED with i = 50 mA noise ~ 200 mV with Gout=10 ~ 2 V with Gout=10 BPW34F (w ~ 300 mm) Fast pulse (180 ms) with Forward i = 1 mA 0.5 V ~ 50 V (linear operation) 4.x1014 cm-2 (Feq) Pad structures Leakage current at full depletion V = 100 V ? ~ nA order ~ mA order 1014÷ 1015 cm-2 (Feq) PT100 Temp Probe DC i = 1 mA 0.1 V (0 ºC) # F.Ravotti LHC Exp. RadMon Working Group 06/04/2004