FBG@nTOFStatus

Francisco Rogelio PalomoUniversity of Sevilla

nTOF meetingLisbon, 13th-15th Dec 2011

Status and Motivation

Fco. Rogelio Palomo Pinto University of Sevilla

A FBG mirror is a periodic modulation of the refractive index in an optical fibre core

A FBG mirror reflects the incident light in only one wavelength:

2B effn

•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 m 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:

Fiber Bragg Gratings, A.Othonos, Rev. Sci.Instrum.68(12) Dec 1997

Fco. Rogelio Palomo Pinto University of Sevilla

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

Proton Ionization Experiments

CNA Sevilla

•Influence of the Fiber Coating on the proton irradiation sensitivity of Fiber Bragg GratingsE.Curras et al. RADECS 2011 Proceedings (accepted for Transactions on Nuclear Science).•On the use of FBG sensors as temperature-based Beam Profile MonitorsF.R.Palomo et al. DITANET 2011

2010: Ionization damage analysis (15 MGy, 13 MeV protons, 90ºC during irradiation ): acrylate coatedFBG fibers recovers after natural annealing.

2011: Ionization detection On/Off Beam, 0.5, 1, 2, 5, 10 Mrad

2011:13.3 MeV, 1.7e10 p/cm2-s, on air, LETCORE ~7 keV/m

FBG sensors at FIC Chamber

Fco. Rogelio Palomo Pinto University of Sevilla

•A group of 7 FBG sensors (acrylate coated) in vacuum, insidethe FIC Chamber (parasitic mode)•4 FBGs under the neutron beam, 3 FBGs for referenceFast 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 avoidthermalization with air)•2 To study fast neutron damage effects in the FBG sensors

Remote Monitoring Status

Fco. Rogelio Palomo Pinto University of Sevilla

•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!

CERNTS.cern.ch

Standard WindowsDesktop session

Passpartout@nTOF DumpChamber

Phyleas@Sevilla Univ.(Data Logger)

Automatic Secure FTP

Rem

ote

Term

inal

RemoteTerminal

FBG sensors@Frame Support

SM130 LaserInterrogator

Stoppers

Fco. Rogelio Palomo Pinto University of Sevilla

•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 injectorpremature closure.

• 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.

Previsions

Fco. Rogelio Palomo Pinto University of Sevilla

Thanks for Your Attention

rogelio@gte.esi.us.es