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FBG@nTOF Status

FBG@nTOF Status. Francisco Rogelio Palomo University of Sevilla nTOF meeting Lisbon, 13 th -15 th Dec 2011. Status and Motivation. A FBG mirror is a periodic modulation of the refractive index in an optical fibre core. FBG@nTOF experiment started in November 2011, still ongoing.

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FBG@nTOF Status

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  1. FBG@nTOF Status Francisco Rogelio Palomo University of Sevilla nTOF meeting Lisbon, 13th-15th Dec 2011

  2. Status and Motivation A FBG mirror is a periodic modulation of the refractive index in an optical fibre core • FBG@nTOF experiment started in November 2011, still ongoing. • FBG sensors are periodic modulation of the refractive index of a photosensitive optical fiber (SiO2 core doped with GeO2). • FBG sensors transduce heat, strain and ionization into wavelength shift (very low thermal inertia, <1 cm length, 8 mm core diameter) • Two targets under fast neutron beam: • Fresh Photosensitive Optical Fiber in the neutron dump for damage analysis • FBG sensors in the FIC chamber for dose damage and transduction analysis FBG sensors are inscribed in photosensitive optical fibers (by means of UV laser ilumination) and stimulated by light: A FBG mirror reflects the incident light in only one wavelength: Fiber Bragg Gratings, A.Othonos, Rev. Sci.Instrum. 68(12) Dec 1997 Fco. Rogelio Palomo Pinto University of Sevilla

  3. Neutron Damage on Photosensitive Optical Fibers • 5 meters of fresh photosensitive optical fiber (Nufern NF1, acrylate coated) • No FBG. • Pasive irradiation experiment, parasitic mode. • After irradiation (1 month or more), analysis of Raman spectra to study neutron damage. • This experiment is ongoing, only 5 five days of irradiation • due to PPAC installation and the premature PS stop. Fco. Rogelio Palomo Pinto University of Sevilla

  4. Proton Ionization Experiments CNA Sevilla 2011:13.3 MeV, 1.7e10 p/cm2-s, on air, LETCORE~7 keV/mm 2011: Ionization detection On/Off Beam, 0.5, 1, 2, 5, 10 Mrad 2010: Ionization damage analysis (15 MGy, 13 MeV protons, 90ºC during irradiation ): acrylate coated FBG fibers recovers after natural annealing. • Influence of the Fiber Coating on the proton irradiation sensitivity of Fiber Bragg Gratings • E.Curras et al. RADECS 2011 Proceedings (accepted for Transactions on Nuclear Science). • On the use of FBG sensors as temperature-based Beam Profile Monitors • F.R.Palomo et al. DITANET 2011 Fco. Rogelio Palomo Pinto University of Sevilla

  5. FBG sensors at FIC Chamber • A group of 7 FBG sensors (acrylate coated) in vacuum, inside • the FIC Chamber (parasitic mode) • 4 FBGs under the neutron beam, 3 FBGs for reference • Fast Interrogation (SM130 Full C Band Tunable Laser, 1 KHz) • Supported in kapton and plexyglas (light elements, thermal isolation) • Ready to Measure, waiting for beam (vacuum feedthroug problems) • Two Objectives: • 1. To catch a fast thermal signal, in analogy with the proton experiment (in vacuum to avoid • thermalization with air) • 2 To study fast neutron damage effects in the FBG sensors Fco. Rogelio Palomo Pinto University of Sevilla

  6. Remote Monitoring Status • Remote monitoring by means a dedicated server (Passpartout, nTOF pit) • Access through CERN Terminal Server • Automatic Data Log with a dedicated server (Phyleas, Sevilla) • Working fine! Passpartout @nTOF Dump Chamber SM130 Laser Interrogator FBG sensors @Frame Support Automatic Secure FTP RemoteTerminal Standard Windows Desktop session Phyleas @Sevilla Univ. (Data Logger) RemoteTerminal CERNTS.cern.ch Fco. Rogelio Palomo Pinto University of Sevilla

  7. Stoppers • The FBG setup in vacuum needs optical feedthrough • Simple solutions innefective, a real stopper. • A new optical feedthrough from SEDI is on the way • (very expensive) • The November campaign finished with the PS injector • premature closure. Fco. Rogelio Palomo Pinto University of Sevilla

  8. Previsions • FBG@FIC could start at mid January or February 2012. • Fiber Damage experiment will restart in January 2012 • We hope to receive the new fiber optical feedthrough during December 2011 • Starting collaboration with Athenas University for dosimetric calibration of the whole FBG@nTOF setup using CR-39 sheets at the neutron dump and at the beam exit inside the FIC chamber. Fco. Rogelio Palomo Pinto University of Sevilla

  9. Thanks for Your Attention rogelio@gte.esi.us.es

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