Optical absorption in commercial single mode optical fibers for the LHC machine T. Wijnands †, L.K. De Jonge †, J. Kuhnhenn ‡, S. K. Hoeffgen ‡, U. Weinand

Optical absorption in commercial single mode optical fibers for the LHC machine

T. Wijnands†, L.K. De Jonge†, J. Kuhnhenn‡, S. K. Hoeffgen‡, U. Weinand‡

†CERN, TS Department‡ Fraunhofer INT Euskirchen Germany

6th LHC Radiation Workshop : 29-30 November 2007 CERN

https://webh11.cern.ch/radworkshop/Registration.htm

https://webh11.cern.ch/radworkshop/Registration.htm

4 September 2007 TWEPP 2007 - Prague 2

Radiation levels in the LHC

Point 7

Point 8

Point 1

Point 2

ALICE

Point 4Point 5

CMS

Point 6

LHCb

ATLAS

Point 3.3

Point 3.2

Low radiation

High radiation

IR 3 : Momentum Cleaning

IR 7 : Betatron Cleaning


Optical fibers in Collimation areas


Fiber architecture LHC Point 7

600 m

168 m132 m


MC simulations collimation area IR7

Dose rate distributions along the tunnel in Gy/year

RR77 UJ76 RR73

1 LHC year = 200 days


Engineering Constraints for fibers

• SM radiation hard optical fibers– RIA < 10 dB/km after 100 kGy – 1310 nm– High Energy Physics radiation field

• Fibers in cables – cables to be blown• Commercial manufacturer• Series production ~3000 km• Lead time ~1.5 years


Standard LHC optical fibers

• Ge-P doped SM fiber– MCVD produced– Draka NK Cables Ltd.– 85/125 m

• Ge-doped SM fiber– PCVD produced– Draka Fiber Tech. BV– 85/125 m

Co-60 Irradiation (CEA-Saclay)


Co-60 irradiation of standard LHC optical fibers

Ge-doped

Ge-P doped

no irradiation

no irradiation Co-60

1 kGy/hr

Co-60

500 Gy/hr


Radiation Induced Absorption

valence band

conductance band

hEv

Ec

V

V=0

(r,t)=Aei(kr-t)

x=0 x=L

color defects

Photon


Paramagnetic color defects

218 nm 630 nm

630 nm

163 nm 660 nm 760 nm


Attenuation spectrum irradiated SM fibers


From literature studies & experience

• Radhard SM fibers (?) for long wavelengths– Pure Silica Core (PSC)– Fluorine doped– Low OH content

Neutron irradiation ?


Screening test- sample collection

• Fiberware• Fujikura Ltd Japan• Heraeus• J-plasma• Nufern• Oxford Electronics• Sumitomo• Verillon• Corning• J-fiber• Draka


Screening test at Fraunhofer INT

Fusion sp lices

60C o

VariableAttenuator

LED/LDSource

2-Ch opticalPower m eter

BA

Con

nect

ors

C oupler

Lead box

Lead tubes

C oncrete sh ie ld ing

LabView controlleddata acquis ition system

GP

IB

Control com puter forrem ote access

E thernet

T herm ally s tab ilized m easurem ent booth

T est fibre spool

G am m am at TK1000(m ax. 600 C i 60Co)

F ibre optic cables


Radiation Induced attenuation

0 2000 4000 6000 8000 10000

0

5

10

15

20

25

30

35

40

Ge-doped 1,2,3 PSC 1,2 Unknown F-doped

Indu

ced

Loss

[dB

/km

]

Dose [Gy(SiO2)]

=1310 nm, D=104 Gy, D=0.2 Gy/s, T=24-28°C, l=50-200 m, P=10/40 µW

1

3

2

2

1


Standard Ge-doped SM fiber

10-2 10-1 100 101 102 103 104 105

0.1

1

10

100

1

3.0 Gy/s

1.4 Gy/s

0.2 Gy/s

Indu

ced

Loss

[dB

/km

]

Dose [Gy(SiO2)]

Dose rate variationParameter variation(1): Wavelength(2): Lightpower

2

0.02 Gy/s

1

2


Radiation hard F-doped fiber

10-2 10-1 100 101 102 103 104 105

0.1

1

3.0 Gy/s

1.4 Gy/s

0.2 Gy/s

Indu

ced

Loss

[dB

/km

]

Dose [Gy(SiO2)]

Dose rate variationParameter variation(1): Wavelength(2): Lightpower(3): Temperature

1

2

3

0.02 Gy/s

1

2

3


High Energy Physics irradiation test at CERN

Fusion splices

1x8 PLCCoupler

LED/LDSource

2-Ch opticalPower meter

BA

LabView controlleddata acquisition system

GP

IB

Control computer forremote access Internet

Measurement booth

Up to 7 test fibre spools

16 Fibres in 72-way cable

1x8 MEMSSwitch

LightShutter

OTDR

Return fibres in 72-way cable

Inward fibres in 72-way cable

Lead cable reference fibre

Reference fibre

Beam


LHC Radiation Test Facility (TCC2)


High Energy Physics Radiation field

0 200 400 600 800 1000 1200 1400 1600 1800 2000

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

Indu

ced

Loss

[dB

/km

]

Dose [Gy]

Ge-doped Unknown F-doped


High Energy Physics vs Co-60

0.1 1 10 100 1000

0.01

0.1

1

Complex field:

Indu

ced

Loss

[dB

/km

]

Dose [Gy]

Ge-doped Unknown F-doped

Complex field

60CoD1.8 kGy/d

D5 Gy/d D23 Gy/d


Related press releases

London, 17th April 2007CERN Selects Fujikura’s Radiation Resistant FibreFibre to provide communications links within world’s largest particle accelerator Fujikura today announced that its radiation resistant single mode optical fibre has been selected by CERN, the European Laboratory for Particle Physics, to provide communication links within the world’s largest particle accelerator – the Large Hadron Collider (LHC) – near Geneva, Switzerland.Fujikura will supply 2,500km of fibre to collect beam instrumentation data from the LHC. To provide reliable communications, the fibre must be able to withstand localised radiation levels of up to 20 kGy/year – enough to cause radiation-induced attenuation in normal optical fibre. Fujikura FutureGuide® - RR, Radiation Resistant optical fibre

Fiber resists CERN's radiation to carry data2 May 2007A radiation-resistant fiber is soon to be used in the world's largest particle accelerator for essential communication links.A radiation-resistant, single-mode optical fiber developed by Fujikura has been selected by CERN for essential communication links within the world's largest particle accelerator - the Large Hadron Collider (LHC).

CERN Selects Fujikura`s Radiation Resistant Fibre04/19/2007Fujikura Ltd. announced that its radiation resistant single mode optical fibre has been selected by CERN to provide communication links within the world's largest particle accelerator - the Large Hadron Collider (LHC) - near Geneva, Switzerland. Fujikura will supply 2,500km of fibre to collect beam instrumentation data from the LHC. To provide reliable communications, the fibre must be able to withstand localised radiation levels of up to 20 kGy/year enough to cause radiation-induced attenuation in normal optical fibre.


Conclusions

• F-doped SM fibers from Fujikura Ltd show superior performance and have been selected for the LHC :– Production of 3000 km from Nov 06 – Aug 07 completed– Sample tests of series production ongoing

• RIA in Co-60 and HEP radiation fields comparable– radiolysis– knock on process– particle type– particle energy

• RIA < 5 dB/km at 1310 nm and 1550 nm (< 1 MGy)unprecedented result – meets LHC specifications


Series sample testing (60Co)

Documents

Optical absorption in commercial single mode optical fibers for the LHC machine T. Wijnands †, L.K. De Jonge †, J. Kuhnhenn ‡, S. K. Hoeffgen ‡, U. Weinand