XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 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 e 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 & ComputingBulgaria, Varna, 12-19 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)
LTh
DTh Dco
Dclad
L1
L2
-0.5 0 0.50
0.5
1
LTh = 125m
Unperturbed FBG
-B [nm]
Ref
lect
ivity
External medium
Sensitive layer
Single-mode optical fiber
Pout=k·RFilm·Pin
• k is a constant• RFilm is the film reflectance
ΔRfilm=f ( ΔεFilm , ΔdFilm , Δεext)• εFilm is the complex dielectric constant of the film• dFilm is the film thickness• εext is the external medium dielectric constant
•Single point sensor through fibre tip coating
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)4/24
FOS fields of application
Measured parameters: StrainTemperatureVibrationRefractive indexChemical detectionHumidityElectric and Magnetic field
Integration with: Metal oxide particle layers
Nanoporous Polymers
Carbon nanotubes
1 e
0.1 C°Up to 1 MHz10-5
< 1 ppm< 1%
Bandgap engineering
Microstructuration
Tapering
Application to: Structural health monitoringDamage detectionAeronautic monitoringGeodetical monitoringEnviromental monitoringAcoustic monitoringRailways 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 & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)5/24
Examples of “industrial” applications
Undercarriage 1 Undercarriage 2 (engine compartment)
Undercarriage 3
Smart RailwaysSmart Railways
Undercarriage 1
Undercarriage 2
Undercarriage 3Undercarriage 1
Undercarriage 2
Undercarriage 3
A Single FBG element can A Single FBG element can provide useful information provide useful information about:about:- occupation state,- train velocity,- acceleration,- weighing in motion,- axle counting
APPLICATION TO :
ADVANCED CONFIGURATIONS :
Water Monitoring
HYDROCARBONS AND AMMONIA
Limit of Detection: <1 ppm
H2 Detection at -160 °C
CRYOGENIC H2
Limit of Detection: <1 %
Air Pollution MonitoringVAPORS (VOCs)
Limit of Detection: <0.5 ppm
GAS (NO2)
Limit of Detection:0.1 ppm
Near fieldchemo- optic sensors
Hollow- core Fiber filledwith CarbonNanotubes
Microlenses on taperedoptical fibers
• Low cost fabrication
•Spheres diameters: 50-300 μm
Fiber core
Near Field Intensity
Layer Topography
Hollow-core Optical Fiber end
face
Guiding Properties Modifications
Web-like Carbon NanotubesDeposition
MICRO AND NANOPHOTONICS FOR CHEMICAL SENSING
Sphere diameter: 90 μm
Modal Analysis Tests on a Composite Aircraft Model WingModal Analysis Tests on a Composite Aircraft Model Wing
NN°°4 4 FBGsFBGs Embedded within Spar, Parallel Embedded within Spar, Parallel to Wingto Wing’’s Axiss Axis
NN°°4 Uni 4 Uni –– AxialAxial AccelerometersAccelerometers BondedBondedtoto WingWing’’s s SurfaceSurface
29 Excitation Points for 29 Excitation Points for Experimental MeasuresExperimental Measures
20 40 60 80 100 120 140
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
Excitation Point Position [cm]
Arb
itrar
y U
nits
[ A
. U. ]
II Dispalcement Bending Shape
Experimental Data Interpolating Polynomial
20 40 60 80 100 120 140
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
Excitation Point Position [cm]
Arb
itrar
y U
nits
[ A
. U. ]
II Strain Bending Mode Shape
Experimental Data Interpolating Polynomial
AccelerometerAccelerometer FBG OutputFBG OutputSimulationSimulation
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 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
CoreSource LED
effB n2 Where:• neff 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
TSS TB e e
1,2,…n
1
2,…n
1/2neff
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 e 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 & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)9/24
e measurement during 2011 magnet ramp-up
Near side Far side
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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
19.6 19.6 19.5
18.7 --- 19.2 19.2 18.7
19.319.820.019.619.2
19.9
19.1 19.5 20.0 20.1 19.8
19.119.921.720.3
Z+Z-
19.5 19.7 19.4
19.2 19.2 --- 19.2 19.3
---19.219.920.019.8
19.8
19.5 19.6 19.8 19.2 18.9
19.219.921.820.3
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 & ComputingBulgaria, Varna, 12-19 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
16.4
16.4
16.6
16.9
16.8
17.1
17.5
18.6Shaft 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 principleAbsorbtion of
moisture by the polymeric coating
Expansion of the coating (“swelling”)
Strain induced on the FBG
Bragg wavelength
shift
%)(%),( RHfTSRHTf TTB
Realization of humidity sensor by coating the gratings with a suited polymer.
POLYIMIDE COATING
FBG2RH SENSOR
FBG1T- SENSOR
Temperature compensation is needed
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)16/24
Starting point: polyimide coating
2002 2005
• 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 & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)17/24
RH testing / calibration facility @ CERNTest 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 m Family 2 (thick): coating thickness = 17 m
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)20/24
Low temperature & humidity properties
0 10 20 30 40 50 60 70 80 90 100
1529,9
1530,0
1530,1
1530,2
1530,3 T=20°C T=0 °C T= -15°C
nm
RH(%)
T
0 10 20 30 40 50 60 70 80 90 100
1569,4
1569,5
1569,6
1569,7
1569,8
1569,9 T= 20°C T= 0°C T= -15°C
(nm
)
RH (%)
T
Family 1 (thin): coating thickness = 8 m(typical)
Family 2 (thick): coating thickness = 17 m(typical)
SRH=0.42 pm/%RH±7,.%
ST=9.54 pm/°C±0.9%Temperature sensitivity:
Humidity sensitivity:SRH=2.09 pm/%RH±19.6%
ST=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 & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)21/24
First ionizing irradiation dose: 10 kGy
0 5000 10000 15000 20000-30
-20
-10
0
10
20
30
40
50
RH
(%)
t(sec)
HIH pre-irradiation HIH post-irradiation
1568 1568.5 1569 1569.5 1570 1570.5 1571 1571.5 1572 1572.5
-45
-40
-35
-30
-25
-20
-15
-10
[nm]
Am
plitu
de [d
Bm
]
Spectrum
S10 at T=20°C pre irradiationS10 at T=20°C post irradiation
1527 1528 1529 1530 1531 1532 1533 1534-70
-65
-60
-55
-50
-45
-40
-35
-30
-25
-20
[nm]
Am
plitu
de [d
Bm
]
Spectrum
S2 at T=20°C pre irradiation S2 at T=20°C post irradiation
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 & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)22/24
Further irradiation level: 50 kGyT = 20 C: before and after irradiation T = 0 C: before and after irradiation
g-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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)26/24
RESERVE: e and T discrimination in FBG
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)27/24
RESERVE: e and T discrimination in FBG
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)28/24
RESERVE: e and T discrimination in FBG
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)29/24
RESERVE: e and T discrimination in FBG
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)30/24
RESERVE: e and T discrimination in FBG
XXIII International Symposium on Nuclear Electronics & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 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 & ComputingBulgaria, Varna, 12-19 September, 2011
Optical fibre sensors for environmental monitoring at LHC and SLHC experiments - Paolo Petagna (CERN)36/24
RESERVE: FBG interrogation