FBGn TOF Status Francisco Rogelio Palomo University of

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

Status and Motivation • FBG@n. TOF experiment started in November 2011, still ongoing. • FBG sensors are periodic modulation of the refractive index of a photosensitive optical fiber (Si. O 2 core doped with Ge. O 2). • 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 A FBG mirror is a periodic modulation of the refractive index in an optical fibre core FBG sensors are inscribed in photosensitive optical fibers (by means of UV laser ilumination) and stimulated by light: Fiber Bragg Gratings, A. Othonos, Rev. Sci. Instrum. 68(12) Dec 1997 Fco. Rogelio Palomo Pinto University of Sevilla A FBG mirror reflects the incident light in only one wavelength:

Neutron Damage on Photosensitive Optical Fibers • 5 meters of fresh photosensitive optical fiber (Nufern NF 1, 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

Proton Ionization Experiments CNA Sevilla 2011: 13. 3 Me. V, 1. 7 e 10 p/cm 2 -s, on air, LETCORE ~7 ke. V/mm 2011: Ionization detection On/Off Beam, 0. 5, 1, 2, 5, 10 Mrad 2010: Ionization damage analysis (15 MGy, 13 Me. V protons, 90ºC during irradiation ): acrylate coated FBG fibers recovers after natural annealing. Fco. Rogelio Palomo Pinto University of Sevilla • 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

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 (SM 130 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

Remote Monitoring Status • Remote monitoring by means a dedicated server (Passpartout, n. TOF pit) • Access through CERN Terminal Server • Automatic Data Log with a dedicated server (Phyleas, Sevilla) • Working fine! Termi Remot e P FT Fco. Rogelio Palomo Pinto University of Sevilla re cu CERNTS. cern. ch Se inal e. Term Remot FBG sensors @Frame Support ic at om Standard Windows Desktop session SM 130 Laser Interrogator ut A nal Passpartout @n. TOF Dump Chamber Phyleas @Sevilla Univ. (Data Logger)

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

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@n. TOF 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

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