Transcript The Radiation Tolerance of Specific Optical Fibers at −25 °C Joshua Abramovitch Southern Methodist University Faculty Advisors: Dr.

The Radiation Tolerance of
Specific Optical Fibers at −25 °C
Joshua Abramovitch
Southern Methodist University
Faculty Advisors: Dr. Andy Liu, Dr. Jingbo Ye
National Conference on Undergraduate Research
Ithaca College
Ithaca, NY
April 1, 2011
Optical Fibers
Optical fibers are materials of
high refractive index capable of
transmitting data over long
distances.
The two main types of optical
fibers are multi-mode and
single-mode fibers.
Multi-mode fibers can transmit
multiple packets of data at high
power, but over shorter
distances.
Single-mode fibers transmit
only one data packet at low
power, but over longer
distances.
Optical fibers are omnipresent
in modern telecommunications.
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ATLAS/CMS
ATLAS and CMS are
particle physics
experiments at the Large
Hadron Collider (LHC) at
CERN. They are searching
for new discoveries in the
head-on collisions of
protons of extraordinarily
high energy.
Both experiments have the
same goals – discovering
the Higgs Boson, extra
dimensions, and dark
matter – but utilize
different technology with
their respective detectors
to achieve those goals.
© CERN 2008
© CERN 2008
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Optical Fibers at CERN
Optical fibers will transmit data
between the various detectors
and computers at monitoring
stations, allowing scientists to
observe particle collisions inside
the Super Large Hadron Collider
(SLHC).
The fibers must be able to
transmit data bi-directionally at
~5 Gbps in the presence of low
temperatures and high radiation.
To find radiation-tolerant fibers,
experiments must be conducted
to test their ability to retain
signal integrity in a radioactive
environment.
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Versatile Link Project
The Versatile Link Project was initiated in April 2008.
The project’s main goal is to develop a radiationtolerant optical interface for upgrades to the SLHC.
One of the steps towards achieving this goal is to
find suitable optical fibers to upgrade the SLHC’s
fiber optic links at the ATLAS and CMS detectors.
The project employs scientists and engineers from
CERN, Oxford, Fermi National Lab, and SMU [1].
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Previous Versatile Link Experiments
In 2008, several optical fibers (SMF-28, Infinicor SX+, Draka-1,
Draka-RHP-1, Draka-RHP-2) were tested at room temperature
to 650 kGy at various dose rates (22.5, 1.01, 0.424, 0.343,
0.0265 kGy/hr). Two multi-mode fibers (the Infinicor SX+ and
Draka-RHP-1) and one single-mode fiber (the SMF-28) were
qualified for use in the SLHC environment for warm operations
[2].
In 2009, two multi-meter fibers (Infinicor SX+ and Draka-RHP1) were tested at -25 °C to 30 kGy at 0.5 kGy/hr. It was
observed that radiation-induced absorption (RIA) is
temperature-dependent [3].
In 2010, fibers (SMF-28e+, Infinicor SX+, Draka-SRH-SMF, X)
were tested at -25 °C to 500 kGy at 27 kGy/hr. Two SM fibers
(Draka-SRH-SMF and X) were qualified. The SMF-28e+ and
Infinicor SX+ showed high levels of RIA during the experiment,
but due to the high dose rate used these fibers cannot
necessarily be excluded as SLHC detector candidates [4].
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Experiment Purpose
This experiment is a step towards attaining the Versatile
Link Project’s goals.
The purpose was to determine the RIA of certain fibers
subjected to a relatively low radiation dose rate at low
temperatures.
Certain fibers have already been cleared for use at the
SLHC during operations at room temperature.
These fibers were also evaluated at low temperature and
high dose rates, but there is still not enough information
to qualify them for use at low temperatures.
Also, this experiment tested two new optical fibers (the
ClearCurve OM3 and SMF28) that will render some of
the fibers previously tested obsolete.
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Experiment Setup
Laptop
Digital
Multimeter
Light
Source
15m fiber
15m fiber
(MM) Light
Sensor
Fiber
Roll
Lead
Co-60
 at BNL
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Freezer
Fibers Tested
Ch ID
Manufacturer
S1
Part #
Mode
SMF28XB
Length exposed
to radiation (m)
Dose rate
(Gy/hr)
166.56
56.19
74.11
70.59
0.00
0.00
170.45
55.75
69.55
66.13
118.96
48.91
Single-Mode
S2
M1
SMF28
Corning
Infinicor SX+
M2
Multi-Mode
M3
Clearcurve OM3
M4
•Fiber M1 was used as a control, at room temperature and
outside of the radiation chamber.
•Fiber M3 was removed from the radiation chamber early in the
experiment for other purposes.
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Temperature Control
The fibers were put
inside a chest freezer, to
maintain an average
temperature of -23.81 ±
0.27 °C throughout the
experiment.
For more information on
this aspect of the
project, please attend
Nnadozie Tassie’s
presentation at 4:20 pm
today.
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Light Sources
Four Vertical Cavity
Surface Emitting
Lasers (VCSELs)
generated 850 nm
lasers for the multimode fibers.
Two Fabry-Perot laser
diodes generated
1310 nm lasers for
single-mode fibers.
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Light Power Measurement
Monolithic photodiodes with
on-chip transimpedance
amplifiers (Part# OPT101
from TI) converted light into
voltage.
A digital multimeter (DMM,
Model 2700 produced by
Keithley) then acquired the
data.
For the single-mode fibers,
an HP 8163 Lightwave
multimeter and two
HP81536A power sensors
were used.
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Calibration of Multi-Mode Light Meters
I measured the optical powers with
a commercial light meter at certain
currents of a VCSEL. Then, I
measured the output voltages of a
light sensor at the same currents.
I fitted each Power-Voltage curve
with a 2nd degree polynomial;
higher degrees resulted in very
little improvement.
I then used the fitting coefficients to
calculate the optical powers from
voltages.
Under the assumption that the fits
are adequate, I calculated fitting
errors.
Light source fluctuation is the
dominant error source.
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Results
Ch
Manufacturer
ID
Part #
Mode
S1
SMF28XB
SingleMode
S2
SMF28
M1
Corning
Length
exposed to
radiation
(m)
Dose
rate Dose (kGy)
(Gy/hr)
RIA
(dB/m)
166.56
56.19
9.14
0.065
74.11
70.59
11.48
0.058
0.00
0.00
0.00
0.0000
170.45
55.75
7
0.078
69.55
66.13
10.75
0.009
118.96
48.91
7.95
0.034
Infinicor SX+
M2
MultiMode
M3
Clearcurve OM3
M4
RIA = 10*log[P(t0)/P(t)]
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Results – Attenuation vs. Dose
Infinicor SX+
Clearcurve
OM3
SMF28XB
Clearcurve OM3 OSA
SMF28
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Comparison with Previous Results
Infinicor SX+
-25 °C, 56 Gy/hr
25 °C, 424 Gy/hr
25 °C, 343 Gy/hr
25 °C, 26.5 Gy/hr
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Conclusions
The newer fibers performed better than their
counterparts. The ClearCurve OM3 experienced a RIA
of 0.0344 dB/m, and the SMF28 experienecd a RIA of
0.0575 dB/m.
All fibers tested are viable candidates for use in the
proposed SLHC upgrades, although still more tests are
needed to qualify them. Future experiments will utilize
radiation doses closer to the conditions likely to be found
in the SLHC.
This experiment contributes to the knowledge pool of
radiation tolerant optical fibers, opening the door for
applications in particle physics and many other scientific
endeavors.
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Acknowledgements
I would very much like to thank the following for their
contributions to this project:
 The Hamilton Scholars program for its support of my
participation in this research.
 Dr. Stephen L. Kramer (BNL) and Peter Cameron (BNL)
for their help during the experiment.
 Mr. Kent Liu, Dr. Annie Xiang, Dr. Datao Gong, Dr. James
Kierstead, and Ms. Cotty Kerridge for their collaboration.
 My faculty advisors for allowing me to be a part of the
Versatile Link Project.
 Drs. Todd Huffman (Oxford University), James Kierstead
(BNL), Tony Weidberg (Oxford University), Jan Troska
(CERN), Francois Vasey (CERN), and Alan Prosser
(Fermi National Lab) for their collaboration and guidance.
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References
1. L. Amaral et al., The versatile link, a common project
for super-LHC, JINST 4 P12003, Dec. 2009.
2. B. Arvidsson et al., The radiation tolerance of specific
optical fibres exposed to 650 kGy(Si) of ionizing
radiation, JINST 4 P07010, Jul. 2009.
3. C. Issever et al., The Radiation Hardness of Certain
Optical Fibres for the LHC Upgrades at −25 ◦C, in
proceedings of Topical Workshop on Electronics for
Particle Physics, September, 2009 Paris, France.
4. B.T. Huffman et al., The radiation hardness of specific
multi-mode and single-mode optical fibres at -25°C
beyond a full SLHC dose to a dose of 500 Gy(Si),
JINST 5 C11023, Nov. 2010.
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If you have any lingering questions, feel
free to e-mail me at [email protected].