Radiation tests on optical fibres for the lhc machine
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Radiation Tests on optical fibres for the LHC machine . T. Wijnands , D. Ricci CERN EN department Fraunhofer INT. First radiation test on optical fibres. December 2002 : First radiation test on SM and MM fibres ~400 Gy total dose (SPS target area) RIA : a few dB/km @ 400 Gy

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Radiation Tests on optical fibres for the LHC machine

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Radiation tests on optical fibres for the lhc machine

Radiation Tests on optical fibres for the LHC machine

T. Wijnands, D. Ricci

CERN EN department

Fraunhofer INT


First radiation test on optical fibres

First radiation test on optical fibres

December 2002 :

First radiation test on SM and MM fibres

  • ~400 Gy total dose (SPS target area)

  • RIA : a few dB/km @ 400 Gy

  • Conclusion was : RIA is not an issue !


Total dose test with 60 co source

Total dose test with 60Co source

March 2005 :

Verification of attenuation data with 60Co source:

  • 1310 nm and 1550 nm

  • Ge-P doped a-SiO2 fibres from Draka NK Cables Ltd

    manufactured using the MCVD (Modified Chemical Vapour Deposition) process

    _Ge-doped a-SiO2 fibres from DrakaFibre Technology BV

    manufactured using the PCVD (Plasma Chemical Vapour Deposition) process


Radiation induced attenuation

Radiation Induced attenuation

Ge-doped fibres

Dose rate : 1 kGy per hour


Radiation induced attenuation1

Radiation Induced attenuation

Ge-doped fibres

After annealing at room temperature


Lhc cleaning sections

LHC cleaning sections

2005 : Difficult situation in the LHC

  • Many SM optical fibres are passing through LHC cleaning sections

  • Dose rate is ~10 kGy/year

  • Maximum attenuation (BPM/BLM system) 7 dB/km

  • For Ge-doped fibres 7dB/km RIA corresponds to 600 Gy !

  • LHC operational in 2007 !

Start of search for SM radiation hard optical fibres


Lhc cleaning sections1

LHC cleaning sections

2005 : Difficult situation for fibres in the LHC !

  • Many SM optical fibres are passing through LHC cleaning sections

  • Dose rate is ~10 kGy/year

  • Maximum attenuation (BPM/BLM system) 7 dB/km

  • For Ge-doped fibres 7dB/km RIA corresponds to 600 Gy !

  • LHC operational in 2007 !

Start of search for SM radiation hard optical fibres for LHC


Radiation tests on optical fibres for the lhc machine

T. Wijnands et al. TWEPP 2007 Prague


Lessons learned

Lessons learned

  • RIA is caused by TID

  • Test results in SPS (complex radiation field) near identical to 60Co.

  • Production process is very special

  • Small manufacturing changes may cause large variations in RIA

  • QA is crucial for the series production and includes sample testing

  • QA is crucial when you test on RIA (procedure, test setup , samples)


M o and new applications

M&O and new applications

  • How to address QA for small batches of radhardfibres ?

  • What fibres can be used for applications > 100 kGy ?

  • What if T = 5 Kelvin ?

  • What coating ?

  • How to achieve compatibility with blowing technique ?

  • Can we also find radhard MM fibres?

  • Can we use light at 850 nm ?


Radiation test of sm optical fibres

Radiation test of SM Optical Fibres

25 January 2010 :

3 random samples from LHC series production :

  • RRSMFB 110A

  • RRSMFB 630A

  • RRSMFB 380A

    one sample from the 3 was selected for the test

    11 February 2010 :

    Start of irradiation test up to 5 MGy:

  • 1310 nm and 1550 nm

  • Room temperature

  • Light power 10 mW

  • Dose rate 220 Gy/min

    4 March 2010 :

    End of first irradiation test


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