SLHC Radiation Test Results

24/09/09 B. Todd Huffman 1

SLHC Radiation Test ResultsPreliminary measurements Versatile Link project from exposure to gamma rays at SCK-CENB. Todd Huffman (speaker), J. Hanzlik,C. Issever, T. Weidberg


The Outline Brief explanation of facility used

SCK-CEN sources Test procedures then and now.

Some Previous results and motivation for temperature controlled tests

Tests of Mulit-mode fibres Draka RHP-1 SRH InfinicorSX+

Conclusions


The two locations: 60Co rays RITA 0.6kGy/hr BRIGITTE 20kGy/hr


Previous High-dose test result

Draka RHP-1 SRH

Infinicor

Draka 3

Draka Commercial


These Results are Good

Good Candidate MM fibres identified InfinicorSX+ and Draka RHP-1 Draka Fibre is under further development

and will require future tests

But Limitations of Previous tests have prompted further studies. Temperature dependence in particular


RIA and temperature, 1st 6 hours.

7


Previous research on RIA in fibre

Multi-mode

Single-mode

850 nm GRIN fibre at room temp (curve C) and -17 C (curves A & B)credit: Thériault Radiation effects on COTS laser-optimized graded-index multimode fibers exposed to intense gamma radiation fields

Single-mode RIA as fcn of temp.credit: Kanamori et al. Transmission Characteristics and Reliability of Pure Silica-Core Single-Mode Fibers

8

RIA is temperature-dependent!


Cold Container designed Uses Peltier cooling elements

4 coolers – 15V and 7A operation Direct connection to Draka fibre

T = ~60 deg C Able to remove ~40W heat load Suitable only for low dose facility

Radiation Damage and heat load

Heat shed to the shielding water Water ambient temp = 30 deg C.

Goal Maintain -250C


Container to Actively Cool Fibres


InfinicorSX+ Temperature Effects


Draka Fibre Temperature Effects


An interesting Temp. Radiation effect

Prior to radiation, fibre attenuation relatively insensitive to temperature variations.

RIA sensitizes fibres to temperature. Particularly Dramatic with Infinicor fibres Present, but less of an effect with Draka

fibres Keep in mind 50m of fibre are used.


0.05 Deg. C

0.01 dB

Before


0.7 dB

0.05 Deg. C

after


0.05 dB

1 Deg. C

Before


0.2 dB

1 Deg. C

after


Comparisons, InfinicorSX+

T = +300 CDose = 65 kGy(Si)

T = -23.30 CDose = 30 kGy(Si)

Gamma sourceat room temperature.Variation is from prev.Stability limitations.


Comparisons, InfinicorSX+

T = +300 CDose = 65 kGy(Si)

T = -23.30 CDose = 30 kGy(Si)

Gamma sourceat room temperature.Variation is from prev.Stability limitations.


Draka RHP-1 SRH fibre

T = -250 C

T = -40 CTotal Dose ~ 15 kGy(Si)


Attenuation Upper limits

Low doses extrapolate linearly up to SLHC tracker doses 375kGy. CAUTION!!: upper limit

Lower dose rate in Tracker volume RIA follows logarithmic scale at high dose

At -250C inside Tracker volume InfinicorSX+ 1.1 dB

Warm result 0.24 dB

Draka RHP-1 0.6 dB


Conclusions

Infinicor Fibre is Ge doped Draka Fibre is F doped

No Ge used Neither uses Phosphorous in their

manufacturing process F doped fibre (Draka) has better

radiation performance even at cold temperatures ~0.05 dB/m vs. ~0.08 dB/m after 30kGy

integrated exposure.


Conclusions

Are we Qualified for operation of these fibres at Cold Temperatures? Definite Maybe. Extrapolation very conservative, but very dodgy

Ideally we would obtain close to a full SLHC dose (~400kGy) cold

Brigitte can do this Smaller volume. Potentially higher heat load. Peltier system would surely fail.


Conclusions

We believe a CO2 thermal management system can achieve the same goal at the higher dose facility.

Studying the feasibility of this. Back-up is to use dry-ice.

Previous tests show we obtain -780C for 24 hours even with heat load.

But, such a test would teach us little if fibre ends up with more than 1dB/m RIA.


General future

Cold tests finished by April Qualified two fibres Re-qualify Draka fibre with higher

bandwidth Move to qualifications of PLC splitters,

LC connectors, full cabling solutions Mechanical tests


End Of Talk

Next Slides are backup slides


Test set-up: Fibre exposure

Power supply&

Measurement

Splitter

Reference

Fibre undertest

Fibre Section exposedIn rad. area

Light-sensitive diode current Measurements

Single Laser source

Optical Patch cables

Conn.

Splitter No Longer used!


System Stability tests – last year

Ran system for extended time periods. Found stability

limitations Extensive tests

by J. Hanzlik showed the optical splitter was the main cause of instability.

±1.5 dB absolute stability limitation for MM fibres.


Stability of test system

Removing coupler seems to improve stability of MM system

-.11

-.15

dB

1.5

0.2

dB

Output from multi-mode fibre (no coupler in system)

Output from multi-mode fibre (coupler in system)

12

VCSEL coupler

PD

PD = photo-diode

PD

PD

PD

VCSEL

PD = photo-diode

PD

= connector

= connector


Stability by the Numbers Multi-mode fibre

InfinicorSX+ RMS variation using

1x4 optical splitter ~0.15 dB

RMS variation of single channel – no splitter ~0.0053 dB

Single Mode fibre SMF-28 RMS variation using

1x4 optical splitter ~0.014 dB

RMS variation of Single channel ~0.042 dB


You can even watch it turn on.

Temp. oscillates& rad. starts

RIA oscillationsincrease in amplitude


Semi-cold Draka Run

-4 deg C


Behavior of Reference fibresA

ttenuati

on,

dB

Att

enuati

on,

dB


InfinicorSX+ Temperature Effects


Draka RHP-1 SRH fibre

T = -250 C

T = -40 C

Documents

SLHC Radiation Test Results