XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 1/24 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments Fibre Optical Sensors (FOS) applications Fibre Bragg Grating FOS (FBG) specificities First FBG applications in HEP: T and  measurements in CMS New R&D line: FBG as Relative Humidity sensors Polyimide coated FBG as RH sensors: experimental results N. Beni ( ATOMKI / CERN ); G. Breglio ( Federico II / Optosmart ); S. Buontempo ( INFN Napoli / CERN ); M. Consales ( Sannio ); A. Cusano ( Sannio / Optosmart ); A. Cutolo ( Sannio / Optosmart ); M. Giordano ( CNR Napoli / Optosmart ); P. Petagna ( CERN ); Z. Skillasi ( ATOMKI / CERN )

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 2/24 Multipoint distributed sensor through fibre grating Concept of Fibre Optical Sensor (FOS) - B [nm] Reflectivity External medium Sensitive layer Single-mode optical fiber P out =k·R Film ·P in k is a constant R Film is the film reflectance ΔR film =f ( Δε Film, Δd Film, Δε ext ) ε Film is the complex dielectric constant of the film d Film is the film thickness ε ext is the external medium dielectric constant Single point sensor through fibre tip coating

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 3/24 Main advantages of FOS technology For a large number of environmental monitoring and industrial applications fiber-optic sensor technology now offers several advantages for significant metrological improvement through: Immunity to electromagnetic interference Lightweight Possibility to work in hard environments Intrinsic Radiation Hardness High sensitivity, versatility and bandwidth Simple multiplexing Absence of electronic circuitry in the measurement area This technology is suitable for remote measurements and it is, by definition, compatible with the fiber-optic communication networks

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 4/24 FOS fields of application Measured parameters: Strain Temperature Vibration Refractive index Chemical detection Humidity Electric and Magnetic field Integration with: Metal oxide particle layers Nanoporous Polymers Carbon nanotubes 1  0.1 C° Up to 1 MHz < 1 ppm < 1% Bandgap engineering Microstructuration Tapering Application to: Structural health monitoring Damage detection Aeronautic monitoring Geodetical monitoring Enviromental monitoring Acoustic monitoring Railways monitoring Photonic devices Micro-structured Fiber Gratings Tapered Fiber Hollow core optical fiber Micro resonators Long period Fiber Gratings

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 5/24 Examples of “industrial” applications

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 6/24 Fibre Bragg Grating FOS Reflected signal Transmitted signal Cladding Core Source LED Where: n eff is the effective refractive index of the fibre  is the grating pitch B is the reflected Bragg wavelength Any strain or temperature perturbation experienced by the FBG results in a Bragg wavelength shift 1, 2,… n 1 2,… n  1 /2n eff

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 7/24 Why FBG Sensors?

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 8/24 First use of FBG sensors in HEP: CMS ~ 100 T or  sensors placed in the following areas in CMS: –HF region negative side (Raiser and Castor table) –Tracker bulkhead on both sides (10-10 sensor) –Experimental Cavern (60) ( in January 2011) (in 2009) Aim: demonstrate feasibility follow mechanical changes induced by magnetic field (HF-) Monitor the T distribution in front of the Tracker (2011) monitor the cavern environment In the last two years the CMS experiment at LHC accepted to pioneer the application of FOS (FBG) to an HEP experiment

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 9/24  measurement during 2011 magnet ramp-up Near side Far side

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 10/24 T distribution in front of the Tracker Z- Z+ One year record of temperature measured by FBG follows the activity of Tracker and provide information on the thermal mapping of the critical area between the TK and the EE

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 11/24 Additional FBG to map T in the cavern Z+Z Z-Z+ Additional 60 FBG T sensors has been installed in the experimental cavern in January 2011 : - 23 sensors on wall near side - 3 sensors on ceiling +Z side - 23 sensors on wall far side - 8 sensors on shaft far side - 3 sensors on ceiling -Z side Some HOURS of work to install all of them! In the figures a snapshot of the T distribution on the rack balconies is shown

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 12/24 A curiosity about T distribution in the shaft Shaft plug closed Shaft FBGs are installed Daily temperature peak of the top sensor appearing when shaft plug is open (every day a bit later than the previous one): effect of direct sunlight discriminated surface cavern

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 13/24 Humidity sensing issues in HEP Trackers HUMIDITY SENSOR SPECIFICATIONS FOR HEP TRACKING DETECTORS Low mass Small dimensions Insensitivity to magnetic field Operation at temperature down to -40 ˚C Response to the full range [0, 100]% RH Reduced number of wires needed Radiation resistance to doses up to 1 MGy HIH 4000 series by Honeywell Small Inexpencive 3 wires for each measuring point Accuracy of 3,5%RH Response time 15s Minimum operation temperature -40°C Not radiation resistant!!! CURRENTLY AT CERN (typical)

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 14/24 Almost all miniaturized humidity sensors presently available on the market are electronic sensors (mainly capacitive-based, followed by resistive-based). Despite all efforts, these sensors still fail to provide a complete set of favourable characteristics, e.g., good linearity, high sensitivity, low uncertainty, low hysteresis and rapid response time. For an application in HEP detectors, one should add to this the sensitivity to electro-magnetic noise pick-up, the suitability for multi-point distributed measurements and the resistance to ionizing radiations. Motivations for R&D on new RH sensors Nowadays – although important requirements on environmental control exist, in particular for Trackers – there is no miniaturized humidity sensor on the market well suited for HEP detector applications

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 15/24 FBG as relative humidity sensor Bare FBG is insensitive to humidity. Use of sensitive material as coating of the FBG to induce a mechanical effect. Hygroscopic polymers swell upon adsorption of water molecules. Sensing principle Absorbtion of moisture by the polymeric coating Expansion of the coating (“swelling”) Strain induced on the FBG Bragg wavelength shift Realization of humidity sensor by coating the gratings with a suited polymer. POLYIMIDE COATING FBG2 RH SENSOR FBG1 T- SENSOR Temperature compensation is needed

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 16/24 Starting point: polyimide coating Relative humidity range limited to 10 – 90 % RH Temperature range limited to 10 ÷ 65 °C Completely unexplored effect of ionizing radiations

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 17/24 RH testing / calibration CERN Test section Thermally controlled liner Salt solution container (if needed) External air circulation (dry + saturated air mixer) Closed loop circulation (salt solution in box) Chilled mirror Ranges: 0% ≤ RH ≤ 100% -20 °C ≤ T ≤ +30 °C Insulated confinement

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 18/24 Optoelectronic interrogation system

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 19/24 Custom fabricated polyimide coated FBG Naked FBG outsourced under strict specifications In-house multiple dip coating + oven curing cycles with PI2525 HD Microsystem Pyralin Family 1 (thin): coating thickness = 8  mFamily 2 (thick): coating thickness = 17  m

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 20/24 Low temperature & humidity properties Family 1 (thin): coating thickness = 8  m (typical) Family 2 (thick): coating thickness = 17  m (typical) S RH =0.42 pm/%RH±7,.% S T =9.54 pm/°C±0.9% Temperature sensitivity: Humidity sensitivity: S RH =2.09 pm/%RH±19.6% S T =10.08 pm/°C±12.4% Temperature sensitivity: Humidity sensitivity: NOTE: Time response very (too?) slow at T < 0  C

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 21/24 First ionizing irradiation dose: 10 kGy Family 1 (thin): coating thickness = 8  m Family 2 (thick): coating thickness = 17  m Perfect peak invariance after first irradiation Note: Honeywell HIH 4000 dies (no signal) after 10 kGy ionizing irradiation dose

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 22/24 Further irradiation level: 50 kGy T = 20  C: before and after irradiation T = 0  C: before and after irradiation  -irradiation tests up to 50 kGy* show good radiation resistance and suggest no further variation after the first level (possibility of applying a “pre-stress”) * latest data at 100 kGy confirm the observation

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 23/24 More technical details and results? “Relative Humidity Monitoring by Polyimide-Coated Fiber Bragg Grating Sensors for High-Energy Physics Applications” Accepted to IEEE Sensors 2011 (Limerick-Ireland)

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 24/24 Further developments Continue irradiation studies up to 1 MGy Perform tests at intermediate T (accurate T dependence estimate) Accurate measurement of response time in function of T Develop reliable packaging for field operation Study different kind of polymeric coatings (epoxies?) Feasibility of different gratings for direct humidity reading (LPG) Create a real network among all FOS developments suited for HEP ( Full scale cryogenic thermometers, Magnetic field measurement, Dosimeters, CFRP and Silicon –embedded strain measurement,… ) Resubmission of the FOS4HEP MC ITN proposal ONGOING 2012 FUTURE

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 25/24 (RESERVE SLIDES FOLLOW) THANK YOU FOR YOUR ATTENTION!

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 26/24 RESERVE:  and T discrimination in FBG

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 27/24 RESERVE:  and T discrimination in FBG

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 28/24 RESERVE:  and T discrimination in FBG

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 29/24 RESERVE:  and T discrimination in FBG

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 30/24 RESERVE:  and T discrimination in FBG

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 31/24 RESERVE: FBG interrogation

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 32/24 RESERVE: FBG interrogation

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 33/24 RESERVE: FBG interrogation

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 34/24 RESERVE: FBG interrogation

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 35/24 RESERVE: FBG interrogation

XXIII International Symposium on Nuclear Electronics & Computing Bulgaria, Varna, September, 2011 Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN) 36/24 RESERVE: FBG interrogation