Fiber optic sensors at INFN Frascati for CMS: past, present and future

1. Fiber optic sensors at INFN Frascati for CMS: past, present and future G.Basile(3), L. Benussi (1), S. Bianco (1), A.Brotzu (3), M.A.Caponero (2) S.Colafranceschi* (3), F.L. Fabbri(1), F. Felli (3), M.Ferrini(3) M.Giardoni(1), S.Grassini (6), E.Angelini (6), C.Lupi (5), M. Pallotta(1) A. Paolozzi(3), M.Parvis (4) L. Passamonti(1), D.Piccolo (1), D.Pierluigi(1) C. Pucci (3), A. Russo(1), G. Saviano (3) (1) Laboratori Nazionali di Frascati dell'INFN (2) Laboratori Nazionali di Frascati dell'INFN and ENEA Frascati (3) Laboratori Nazionali di Frascati dell'INFN and Sapienza Universita’ di Roma (4) Laboratori Nazionali di Frascati dell’INFN and Politecnico Turin (5) Sapienza Universita’ di Roma (6) Politecnico Turin *also at CERN, Geneva In collaboration with A.Sharma (CERN) Presented by Michele Caponero for the INFN-Frascati CMS group michele.caponero@enea.it michele.caponero@lnf.infn.it

2. THE CMS INFN FRASCATI GROUP …in a well assorted collaboration INFN - National Laboratory of Frascati ENEA – Research Centre of Frascati Univ. Rome - Dept. Chemical and Material Eng. Turin Polytechnic – Dept. Electronic Eng. …quite interdisciplinary competences High Energy Physics Fiber Optic Sensing Chemistry Composite materials Electronics and Photonics

3. Optical sensors for HEP Optical sensors of interest for HEP detectors are fast precise electrical noise - free magnetic field - insensitive rad-hard multiplexable Measurement of critical variables provided are Temperature Humidity Gas pollutants concentrations Strain Displacement

4. The CMS INFN Frascati group has introduced Optical sensors in HEP since 1998 • FINUDA at DAFNE (1998) • Operated Monitoring geometrical stability of uvtx detector • BTeV at Fermilab (2002) • R&D of Monitoring geometrical stability of uvtx • R&D of Monitoring repositioning displacement of uvtx • CMS (2005) • Proposal for Monitoring geometrical stability of uvtx and repositioning • CMS (NOW) • R&D for gas pollutants for RPC • CMS (NOW) • Proposal T, H, gas pollutants in RPC upscope • CMS (upgrade) • Proposal for T, H, gas pollutants in hi-eta MPGD muon detectors Bibliography S.Bianco, M.Caponero, F.L.Fabbri Fiber Bragg Grating Sensors in CMS presented by S.Bianco at the March 2006 CMS week. S. Bianco, M.A.Caponero, F.L. Fabbri, A.Paolozzi Omega-Like Fiber Bragg Grating Sensors as Position Monitoring Device: A Possible Pixel Position Detector in CMS? Frascati Preprint LNF - 06 / 13(NT) 23-05-2006. L.Benussi et al., Results on Position Monitoring and Displacement> (Omega-Like Device) by Means of Fiber Bragg Grating Sensors for the BTeV Detector. Frascati Preprint LNF-03/15(IR) 10-09-2003. L.Benussi et al.,  The Omega-Like: A Novel Device Using Fbg Sensors To Position Vertex  Detectors With Micrometric Precision,  Nucl. Phys. Proc. Suppl. 172 (2007) 263. E.Basile et al., A novel approach for an integrated straw tube - microstrip detectors, IEEE Trans. Nucl. Sci.  53 (2006) 1375 E.Basile et al., Micrometric position monitoring using fiber Bragg grating sensors in silicon detectors  arXiv:physics/0512255

5. FINUDA Use of Fiber Optic Sensors for HEP introduced by our group in 1998 for the FINUDA Experiment Use of optical fiber FBG sensors for real-time structural monitoring of the mechanical structure supporting the pixel vertex detector FINUDA: FIsica NUcleare a DAfne (Nuclear Physics at DAFNE)

6. Common requirement for Vertex Detectors • Supporting mechanical structure MUST be extremely ‘light’ AND very stable • (... a no mass AND very stiff mechanical structure would be appreciated!) • With ‘light’ mechanical supports it is hard assuming stable geometry: • Deformation from mounting geometry • thermal stress from mounting condition to data taking condition • static mechanical loads • Deformation from ‘last calibration’ by cosmic ray tracking • backling effects by (even minor) thermal stress for service on/off • Continuous alignment via track residuals is quite difficult !

7. Availability of real-time metrological deformation monitoring CAN ALLOW continuous check of geometry/position stability, providing real-time alarm flag. If alarm flag occurs, alignment via track residuals is started. Fibre Bragg Grating (FBG) optical sensors: a novel but robust technology that can allow developing real-time metrological monitoring for HEP experiments

8. Fibre Bragg Grating (FBG) sensor: Diffraction grating written inside the core of an optical fibre Grating is made by modifying the refraction index of a segment of the optical fibre FBG location (embedded in the optical fibre core) Optical fibre 5mm Modified core: n3 Core: n2 (n2-n3 ≈ 10exp-3) Cladding: n1 Coating (mechanical protection) 250mm 8mm

9. Light propagating along the fiber can be diffracted by the grating Grating is designed to produce a narrow-band back-reflected signal Launched signal: Dl60nm Diffracted signal:Dl 0.3nm @-3dB

10. Wavelength of diffracted signal is a function of grating features • (grating pitch L, effective refraction index neff) • Mechanical and thermal excitation of the grating modify the wavelength of the diffracted signal Ds = 1 meDl = 1 pm (typical values) DT = 0.1 K Dl = 1 pm l = 2Lneff

11. Fibre Bragg Grating (FBG) sensor: optical strain gauge. • Directly integrated in an optical fiber core • Many sensors along the same optical fiber (WDM read-out) • Long term stability in static and dynamic regime • Electromagnetic field insensitivity • Hostile environment endurance and mass lightness. FBGs bonded with thermal/structural contact Structure ‘at rest’ FBG signal l l0 l1 Monitored structure Stressed structure FBG signal l l1 l0

12. FINUDA FINUDA: FIsica NUcleare a DAfne (Nuclear Physics at DAFNE) Use of optical fiber FBG sensors for real-time structural monitoring of the mechanical structure supporting the pixel vertex detector

13. Mechanical structure of FINUDA vertex detector subject to deformations mainly due to microstrip on-board electronics thermal and mechanical stress FBG sensors attached on selected mechanical components to monitor significant structural deformations

14. Microstrip OFF Microstrip OFF Massive ‘trips’ of Microstrip Microstrip ON Microstrip ON 11/Dic/2003 - 03:08 Massive ‘trips’ for some time due to e+ injection 10:10 DAFNE machine development: Microstrip and Tofino off 16:15 Beam stable: Microstip and Tofino on 18:50 Microstrip (OSIM1) ‘trip’: recovery procedure 19:15 Microstrip stable: take data

15. BTeV Experiment (planned to be run at FNAL; cancelled on Feb. 2005 !!!) R&D was performed in order to develop a device based on FBG sensors for monitoring repositioning of pixel detector with micrometric precision Mechanical support of pixel detector: to be removed/repositioned during/after beam steering hold in place by Pixel Support Cylinder

16. W-like gauge: mechanical displacement gauge • one end clamped at vacuum pipe fixed frame • one end clamped at Pixel Support Cylinder 2/2 Pixel Support Cylinder Omega-like Pixel ladder 1/2 Pixel Support Cylinder Actuator

17. W-like displacement gauge instrumented with FBG sensors • one end clamped at vacuum pipe fixed frame • one end clamped at the mechanical support of Pixel Detector Omega-like displacement gauge: position of moving frame is worked out by deformation monitoring of W-like gauge; monitoring of deformation is accomplished by use of FBG sensors FBG signal FBG signal l l0 l l1 l0 FBG sensors Fixed frame Moving frame

18. Experimental tests atSiDet laboratory – FNAL Displacement imposed by motorised translation stage Reference displacement measurements made by CMM (1mm resolution)

19. Experimental Linear fit Experimental Linear fit Displacement [mm] Dl [nm] Displacement [mm] Dl [nm] Test procedure: repeated ‘back and forth’ displacement; 10mm path length Experimental data expected to follow linear fit L. Benussi et al. Nuclear Physics B; 172 (2007) 263-265

20. Residuals of ‘back and forth’ displacement repeated 100times: 8mm displacement 4mm displacement # test # test IV ord. Polinomial signal conditioning Residual [mm] s = 5.6 mm for 10mm long disp. range Displacement [mm] Forward Backward L. Benussi et al. Nuclear Physics B; 172 (2007) 263-265

21. FBG sensor have fair ‘intrinsic’ Radiation Hardness capability FBG production: a grating is ‘written’ modifying the refractive index of the ‘core’ by a space-modulated UV beam. (UV modifies wrong Ge-Si, Ge-O and Ge-Ge bonds) Exposition to uniform ionising radiation affects the refraction index of the optical fiber mainly producing a ‘bias’ effect Optical fiber exposed to space-modulated UV FBG grating ‘written’ in the core of the optical fiber FBG exposed to uniform ionising radiation FBG exposed to uniform ionising radiation

22. Effect of ionizing radiation on optical fibers already reported: • Transmission attenuation (slightly wavelength-dependent) • FBG sensing is based on narrow-band wavelength-encoded measurement, with excellent signal-to-noise ratio: • FBG sensing has high tolerance to Transmission attenuation of optical fiber cables Typical FBG features Reflectivity >90%Reflective bandwidth @-3dB <0.3 nm Side lobe suppression >15dB Typical signal form a string of 3 FBG sensors

23. Neutron beam 14MeV - FNG facility at ENEA Research Centre ‘Frascati’ Total flux: 21.03  1013 n/cm2 @14MeV (35.97 1013 n/cm2 @ 1MeV) Monitoring of FBG spectra during exposition M. Caponero et al. Proc. 10th conference Astroparticle, Particle and Space Physics, Detectors and Medical Physics Applications M. Barone, A. Gaddi (ed.) World Scientific Publishing (2007) 533 - 539

24. Slight spectrum modification up to 121013 /cm2 neutrons@14MeV No further modification up to 211013 /cm2 neutrons@14MeV M. Caponero et al. Proc. 10th conference Astroparticle, Particle and Space Physics, Detectors and Medical Physics Applications M. Barone, A. Gaddi (ed.) World Scientific Publishing (2007) 533 - 539

25. 400 cm CALLIOPE dose rate profile FBG sensor location optical fibre with FBG sensor plastic frame epoxy glue g-rays 60Co – CALLIOPE facility at the ENEA Research Centre ‘Casaccia’ M. Caponero et al. Proc. 10th conference Astroparticle, Particle and Space Physics, Detectors and Medical Physics Applications M. Barone, A. Gaddi (ed.) World Scientific Publishing (2007) 533 - 539 Set up for irradiation: FBG slightly stretched and glued on a plastic frame

26. l [nm] Relative Time[h] Spectra comparison after 1300 hexposition time Amplitude [a.u.] l-lB [nm] Dose rate  1349 Gy/h Dose  1.75 MGy Amplitude [a.u.] M. Caponero et al. Proc. 10th conference Astroparticle, Particle and Space Physics, Detectors and Medical Physics Applications M. Barone, A. Gaddi (ed.) World Scientific Publishing (2007) 533 - 539 l-lB [nm]

27. Temperature monitoring Humidity monitoring Gas contaminants monitoring PROPOSING FIBER OPTIC SENSORSFORCMS RPC MUON DETECTORS

28. R&D on optical sensors for gas pollutants in the RPC detectors PRESENT ACTIVITY

29. The large detector volume and the expensive gas mixture make a closed loop recirculation system mandatory RPC MUON DETECTORS GAS recirculation closed loop Gas total volume: 18 m3 Active surface: 4000 m2 Installed gaps: >800 Flux: 8 m3/h gas mixture (due to the presence of HF) tends to release some elements from zeolite framework, K and Ca increase in gas when currents increase. Fluorine is constantly produced and the zeolite traps it efficiently. Purifiers fail to filter HF and need to be regenerated. HF production increases with radiation Gas mix composition 95.2% of C2H2F4 4.5% of iC4H10 0.3% SF6 40% RU

30. Proposing use of Plastic Optical Fiber: gas pollutants monitoring • POF: Plastic Optical Fiber • Large diameter plastic optical fiber • POF sensors for gas pollutants based on the technique of the ‘evanescent wave attenuation measurement’ • (light transmitted at the core/cladding interface) • Sensor fabrication • The plastic cladding of the fiber is removed • The fiber is coated with a chemical substance ‘sensitive’ to the pollutant to be monitored • Sensing principle • Optical property of the coating is affected by the quantity of pollutant that has been ‘intercepted’ • The variation of the light intensity transmitted by the coated fiber is related to the quantity of ‘intercepted’ pollutant. LED 50 mm PHOTO DIODE NOTE: Usually irreversible cumulative measurement (!!)

31. PECVD Plasma Enhanced Chemical Vapour Deposition Turin Polytecnic Department of Electronic Engineering

32. Ag2S 10 m POF sensor for H2S Coating: Ag before 10 m after

33. Results in use of POF sensor for H2S sensing: POF ELECTROCHEMICAL ppm sensitivity ……..R&D in progress for HF detection

34. Proposing use of Fiber Optic Sensors for RPC upscope & upgrade THE NEAR FUTURE We propose to install a distributed system based on FBG technology to monitor Temperature ad Relative Humidity of upscope RPC detector (and possibly gas pollutants) THE FAR FUTURE Optical sensors for hi-eta MPGD: T, RH, pollutants

35. RPC MUON DETECTORS Temperature and Humidity monitoring is of paramount importance in RPC detectors TemperatureTaffects RPC polarization voltage V Humidity RHaffects bakelite resistivityR

36. RH sensing by FBG sensors: well established application ‘State of the Art’ resolution: 5%RH Proper choice of moisture sensitive polymer coating can improve resolution

37. DT [K] • Temperature sensing by FBG sensors • Typical resolution: 0.1K (at room temperature) • Temperature dependence of glass refraction index • Thermal expansion coefficient of glass M. Caponero et alt.; “long term thermal deformation and creep monitoring of CFRP components” – ENEA Internal Report

38. Sensors in Upscope endcaps Barrel Endcap RE RE RE RE RE RE RE RE RE RE RE RE 1/1 1/2 1/3 2/1 2/2 2/3 3/1 3/2 3/3 4/1 4/2 4/3 No. of chambers 36*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 • Baseline • Six stations in the Barrel • Four station in the Endcap • up to h = 2.1 However, due to technical and financial reasons, only three layers up to h = 1.6 are present in the endcap region.

39. bare optical fiber in-cable optical fiber T sensing (metal coated FBG sensor) Technological specimen RH sensing (FBG embedded in moisture sensitive layer)

40. FBG sensing system (TDM - Time Division Multiplexing): Optical lines sequentially addressed to single-channel Interrogation System (WDM – Wavelength Division Multiplexing): Multiple FBG sensors arranged in-series on one optical line Feed through Optical connector receptacle Fiber Optic ribbon cable Interrogation System Optical Connector Optical Switch RPCs Local Controller Optical fibers with FBG sensors (Temperature; RH) to/from Remote Controller

41. Optical sensors have been successfully applied in HEP detectors in our past experiments and R&D (FINUDA, BTEV) for strain, displacement, temperature monitoring precise, reliable, rad-hard. Started R&D on optical sensors for detection of RPC gas contaminants, to be tested at GIF (2010) If R&D successful, proposal for monitoring gas contaminants in endcaps RPCs (1ppm) Proposed use of optical sensors for T(0.1K) and RH (2÷5%) monitoring in new upscope RPCs In 2011 finalize proposal for use of optical sensors in hi-eta MPGD Conclusions & outlook

43. References S.Bianco, M.Caponero, F.L.Fabbri Fiber Bragg Grating Sensors in CMS presented by S.Bianco at the March 2006 CMS week. S. Bianco, M.A.Caponero, F.L. Fabbri, A.Paolozzi Omega-Like Fiber Bragg Grating Sensors as Position Monitoring Device: A Possible Pixel Position Detector in CMS? Frascati Preprint LNF - 06 / 13(NT) 23-05-2006. L.Benussi et al., Results on Position Monitoring and Displacement> (Omega-Like Device) by Means of Fiber Bragg Grating Sensors for the BTeV Detector. Frascati Preprint LNF-03/15(IR) 10-09-2003. L.Benussi et al.,  The Omega-Like: A Novel Device Using Fbg Sensors To Position Vertex  Detectors With Micrometric Precision,  Nucl. Phys. Proc. Suppl. 172 (2007) 263. E.Basile et al., A novel approach for an integrated straw tube - microstrip detectors, IEEE Trans. Nucl. Sci.  53 (2006) 1375 E.Basile et al., Micrometric position monitoring using fiber Bragg grating sensors in silicon detectors  arXiv:physics/0512255 S.Bianco et al., Chemical study of the CMS RPC closed loop gas system, CMS note 2010 - 007 G.Saviano (for the CMS RPC Collaboration) Results on chemical analysis in the CMS RPC closed loop, presented at RPC2010, Darmstadt (Germany).

44. ADDITIONAL MATERIAL

45. 2010 May Expose POF to high-rad (GIF) Begin design for T, H monitoring FBG sensors integration in upscope endcaps June End of last run of Closed Loop gas purifier characterization @ low-rad July Moving RPC’s from low-rad to high-rad (GIF). Characterize purifiers. Goals: confirm release of contaminants, measure purifiers lifetime, extrapolate to safe lifetime for CMS between purifier regeneration October Install and characterize POF for F- detection @GIF 2011 January End of 3.1 Begin characterization, testing and installation of FBG sensors for T, H monitoring in upscope endcaps March End of 4.1 Decision: POF for F- detection in upscope endcaps ? April Begin conceptual design of FBG and POF for hi-eta region MPGD …………. Proposed Plan & MilestonesOptical fiber activity for RPC

46. F- productionandcurrent increasing in upstream gap F- before zeolite F- after zeolite preliminary