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Radiation Monitoring Technologies for the LHC

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.

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Radiation Monitoring Technologies for the LHC

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  1. 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)

  2. 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). LHC Exp. RadMon Working Group 06/04/2004

  3. RadFETs General • 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 LHC Exp. RadMon Working Group 06/04/2004

  4. RadFETs Details • 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! LHC Exp. RadMon Working Group 06/04/2004

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

  6. 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 affectthe devices long-time behaviour. Devices have to be selected on the basis of their annealing behaviors  Isochronal Annealing LHC Exp. RadMon Working Group 06/04/2004

  7. RadFETs Isochrones Regular behaviours • Scaling annealing tÛ 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 LHC Exp. RadMon Working Group 06/04/2004

  8. 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) 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; Sdependent on readout electronics. LHC Exp. RadMon Working Group 06/04/2004

  9. 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. LHC Exp. RadMon Working Group 06/04/2004

  10. 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 ? LHC Exp. RadMon Working Group 06/04/2004

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

  12. 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 LHC Exp. RadMon Working Group 06/04/2004

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

  14. BPW34F Osram diodes Response Curve (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 LHC Exp. RadMon Working Group 06/04/2004

  15. “Pad” structures 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 LHC Exp. RadMon Working Group 06/04/2004

  16. 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) LHC Exp. RadMon Working Group 06/04/2004

  17. 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. LHC Exp. RadMon Working Group 06/04/2004

  18. 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. LHC Exp. RadMon Working Group 06/04/2004

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

  20. Readout parameters LHC Exp. RadMon Working Group 06/04/2004

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