Slide 1 5th LHC RADIATION WORKSHOP, CERN, 2005-11-29, Jochen Kuhnhenn, Fraunhofer INT 2005-11-29 Radiation tolerant fibres for LHC controls and communications

Slide 1

5th LHC RADIATION WORKSHOP, CERN, 2005-11-29, Jochen Kuhnhenn, Fraunhofer INT

2005-11-29

Radiation tolerant fibres for LHC controls and communications

Jochen Kuhnhenn

Fraunhofer INTAppelsgarten 2D-53879 EuskirchenGermany

Slide 2


2005-11-29

Outline

Introduction

Project overview: "Radiation tolerant fibres for LHC"

Results

Conclusions

Slide 3


2005-11-29

Introduction

Introduction

Motivation

The Fraunhofer Institute at a glance

Radiation effects on optical fibres

Project overview

Results

Conclusions

Slide 4


2005-11-29

Motivation

More than 1 500 km of optical cables needed for LHC

Control and communication

Beam instrumentation

Advantages of optical communication

Extreme noise immunity and ground potential independence

Lower attenuation (no repeater needed)

Higher flexibility (additional links on demand without tunnel access)

In LHC cleaning insertions IR3 and IR7 high radiation levels expected from day 1

First tests of installed fibres led to concerns if continuous transmission will be possible (Wijnands et al.: LHC Project Note 351, Presentation at 4th LHC radiation workshop)

Slide 5


2005-11-29

The Fraunhofer INT

Experience of more than 30 years on effects of nuclear radiation on electronics and opto-electronics

The institute operates several irradiation facilities(Co-60, 14 MeV neutrons, flash X-Rays, access to 35 MeV protons)

Offering irradiation services to governmental, scientific, and industrial customers including planning and interpretation

Full range of measurement equipment for characterisation and analysis of radiation effects in electronics and opto-electronics

One focus: Radiation effects on optical fibres

Tested several 1 000 fibres of all types and manufacturers

Close contacts to fibre manufacturers and research institutions

Slide 6


2005-11-29

Radiation effects on optical fibres

Ionising radiation changes every property of an optical fibre

Refractive index

Bandwidth

Mechanical properties (e.g., tensile strength)

Additional: Generation of luminescence light

These effects show up typically only at relatively high doses or dose rates

Most obvious and disturbing effect is the increase of attenuation

Slide 7


2005-11-29

Parameter dependencies of RIA

Manufacturing influences

Fibre type (Single mode, graded index, step index)

Doping of core, doping of cladding (for SM fibres)

Preform manufacturer and used processes

Core material manufacturer

OH Content

Cladding core diameter ratio (CCDR)

Coating material

Drawing conditions

Operation conditions

Wavelength

Light power

Launch conditions

Environment

Total dose

Dose rate

Annealing periods

Temperature

Slide 8


2005-11-29

"Radiation tolerant fibres for LHC": Project overview

Introduction

Project overview

Aims

Approach

Experimental details

Results

Conclusions

Slide 9


2005-11-29

Project aims

Verification of previous irradiation tests of currently installed optical fibres by Draka

Full characterisation of radiation effects in used Ge-doped Draka fibre

Identification of optical fibres with better radiation resistance

Modelling of radiation induced loss at different dose rates

Slide 10


2005-11-29

Project steps

Acquisition of possible alternative optical fibres

Screening test of all samples under identical conditions

Fixed dose, dose rate, temperature, light power, wavelength

Detailed testing of current Draka fibre and best two candidates

Variation of dose rate & dose, wavelength, light power

Accelerated simulation of LHC radiation environment

Slide 11


2005-11-29

Experimental details

Screening tests

Dose rate: 0.22 Gy/s

Dose: 10 000 Gy

Room temperature

Wavelength: 1310 nm

Light power: ~ 10 µW

Detailed tests

Dose rate: 0.016 Gy/s 3.7 Gy/s

Dose: up to 150 000 Gy

Wavelengths: 1310 & 1550 nm

Light power: up to 300 µW

Slide 12


2005-11-29

Results

Introduction

Project overview

Results

Identification of alternative products

Screening tests of candidates

Detailed testing of now used fibre and best candidates

Modelling of dose rate dependence

Conclusions

Slide 13


2005-11-29

Identification of other products

Fraunhofer INT contacted 10 manufacturers known for radiation resistant optical fibres

Of those 6 provided samples

• Draka developed new fibre: "Draka New"

• Heraeus

• Fujikura

• Corning

• Manufacturer X

• Manufacturer Y

Additional sample of current Ge-doped fibre "Draka #445755"

Slide 14


2005-11-29

Results of candidate screening test

Logarithmic scale

1 10 100 1000 10000

1

10

Ind

uce

d L

oss

[d

B/k

m]

Dose [Gy(SiO2)]

X

Fu jik ura

Heraeu s

Drak a 4457 55

Drak a N ew

Y

Corn ing

=1 31 0 n m , D =1 04 G y , D =0 .2 2 5 G y /s,

T =28 °C , l=10 0 m , P =1 0/4 0 µ W

0 2000 4000 6000 8000 10000

0

5

10

15

20

25

30

35

40

Ind

uce

d L

oss

[d

B/k

m]

Dose [Gy(SiO2)]

X

Fu jik ura

Heraeu s

Drak a 4457 55

Drak a N ew

Y

Corn ing

=1 31 0 n m , D=1 04 G y , D=0 .2 2 5 G y /s,

T =28 °C , l=10 0 m , P =1 0/4 0 µW

Linear scale

Slide 15


2005-11-29

Detailed tests of Draka #445755: Wavelength dependence

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

0

5

10

15

20

25

Ind

uc

ed

Lo

ss

[dB

/km

]

Dose [Gy(SiO2)]

Drak a 44 5755

Drak a 44 5755 (15 50 nm )

=1 3 10 /15 50 nm , D =104 G y, D= 0.2 25 G y/s ,

T =2 8°C , l=1 00 m , P=1 0 µW

Slide 16


2005-11-29

Detailed tests of Draka #445755: Dose rate dependence

0.1 1 10 100 1000 10000 100000

0.1

1

10

100

Ind

uc

ed

Lo

ss

[dB

/km

]

Dose [Gy(SiO2)]

Drak a 44 5755

Drak a 44 5755 (3.7 Gy /s)

Drak a 44 5755 (1.6 Gy /s)

Drak a 44 5755 (0.02 G y/s)

=1 3 10 nm , D =103, 1 0

4, 10

5 G y,

T =2 8°C , l=1 00 m , P=1 0 µW

Slide 17


2005-11-29

0.1 1 10 100 1000 10000 100000

0.1

1

10

100

Ind

uc

ed

Lo

ss

[dB

/km

]

Dose [Gy(SiO2)]

0.02 Gy/s

0.22 Gy/s

3.7 Gy/s

1.6 Gy/s

0.1 1 10 100 1000 10000 100000

0.1

1

10

100

Ind

uc

ed

Lo

ss

[dB

/km

]

Dose [Gy(SiO2)]

0.02 Gy/s

0.22 Gy/s

3.7 Gy/s

1.6 Gy/s

Comparison of dose rate dependence of new fibres

Draka New Fujikura

0.1 1 10 100 1000 10000 100000

0.1

1

10

100

Ind

uc

ed

Lo

ss

[dB

/km

]

Dose [Gy(SiO2)]

0.02 Gy/s

0.22 Gy/s

3.7 Gy/s1.6 Gy/s

0.1 1 10 100 1000 10000 100000

0.1

1

10

100

Ind

uc

ed

Lo

ss

[dB

/km

]

Dose [Gy(SiO2)]

0.02 Gy/s

0.22 Gy/s

3.7 Gy/s1.6 Gy/s

Draka New

better

Fujikura

better

Slide 18


2005-11-29

Radiation induced loss of used and new fibres: Summary

Results for currently installed Ge-doped fibre by Draka

It is one of the best tested fibres of this type

1310 nm has advantages for doses higher than 6000 Gy

Increased light power does not improve radiation resistance (not shown in slides)

Two new candidates characterised with focus on dose rate dependence

Both candidates show better radiation tolerance for higher doses

• Draka New better at least by a factor of 2 for highest doses

• Fujikura better above 10 Gy with best performance (by a factor of 10) between 100 and 1000 Gy

Slide 19


2005-11-29

LHC operation conditions assumed for loss modelling

LHC Project Note 375

One LHC year: 140 days of physics

Assumptions

• “Nominal” physics

• Fill length + Turn around: 8 + 3 hours

• 2.3×1016 total beam loss per year in IR7

• Dose in fibres ~ 10 000 Gy per 1016 protons(private communication: Wijnands, Kurochkin)

Expected radiation environment for optical fibres in IR7

Maximum averaged dose per year: ~ 23 000 Gy

Maximum mean dose rate: 2 mGy/s

Peak dose rates expected to be much higher

Slide 20


2005-11-29

Extrapolated losses for maximum mean LHC dose rate

10 100 1000 10000 100000

1

10

0.1 1 10 100 1000

Ind

uc

ed

Lo

ss

[dB

/km

]

Dose [Gy(SiO2)]

Fujikura

Draka #445755

Draka New

Constant doserate: ~ 2 mGy/sFactor of 3

Factor of 2

Limit for IR3: 12 dB/km

Corresponding irradiation time [d]

Slide 21


2005-11-29

Accelerated simulation of LHC conditions

Acceleration by factor 10 for 20+10 operation:

Irradiation for 2 hours at ~ 20 mG/s

Annealing for 1 hour

Repeating 10 times

Same dose per cycle (~ 150 Gy) as expected for LHC

Simulates nearly two weeks of LHC operation

Comparison of cyclic irradiation with results of continuous irradiation at corresponding mean dose rate

Slide 22


2005-11-29

Cyclic irradiation compared with continuous irradiation

1 10 100 1000

0.1

1

Ind

uc

ed

Lo

ss

[d

B/k

m]

Dose [Gy]

Continuous irradiation:Dose rate 16 mG y/s

Cyclic irradiation:Dose rate 24 mGy/s

Duty cycle 2+1 hoursAverage dose rate 16 mGy/s

Fujikura

Slide 23


2005-11-29

Cyclic irradiation compared with continuous irradiation

10 100 10001

2

3

4

5

6

7

8

9

Draka New

Continuous irradiation:Dose rate 16 mGy/s

Cyclic irradiation:Dose rate 24 mGy/sDuty cycle 2+1 hoursAverage dose rate 16 mGy/s

Ind

uce

d L

oss

[d

B/k

m]

Dose [Gy]

Slide 24


2005-11-29

Conclusions

Introduction

Project overview

Results

Conclusions

Slide 25


2005-11-29

Conclusions

Currently installed Ge-doped Draka fibre can be operated for extended time(If average mean dose rate scaling is appropriate)

Both new candidates show better radiation tolerance(Extend depending on dose range)

Cyclic irradiations with annealing periods do not lead to a attenuation increase as the corresponding continuous irradiation

Better understanding of realistic conditions at LHC needs time-dependent dose rate data and further investigations

Slide 26


2005-11-29

Thank you very much for your attention

I’m looking forward to your questions …

Contact:Dr. Jochen Kuhnhenn

Fraunhofer INTAppelgarten 2D-53879 EurkichenGermany

Tel.: +49(2251)18200

Fax: +49(2251)18378

Email: [email protected]

Documents

Slide 1 5th LHC RADIATION WORKSHOP, CERN, 2005-11-29, Jochen Kuhnhenn, Fraunhofer INT 2005-11-29 Radiation tolerant fibres for LHC controls and communications