ATLAS/CMS Opto WG March '10
Tony Weidberg 1
Radiation Damage Passive Components
• Versatile Link WP 2.3– Todd Huffman, Mark Jones, Nick Ryder & Tony Weidberg
• Summary radiation tolerance GRIN and SM fibres– Qualified for warm operation
• RIA variation with Temperature• Plans for RIA measurements at -25C.• Fibre Bandwidth after irradiation.• Other passive components being studied
– PLC splitters @Radiatio 1310 nm– LC & MT connectors.
ATLAS/CMS Opto WG March '10
Tony Weidberg 2
GRIN Fibres
VCSEL @ 850 nm source
Brigitte Co60 source up to full SLHC dose (kGy)
Also performed tests at lower doses, Rita and BNL.
ATLAS/CMS Opto WG March '10
Tony Weidberg 3
SM Fibre• SMF-28 SM fibre, 1310 nm EEL source.
• SMF-28 better radiation tolerance than GRIN fibres (as expected for longer ).
ATLAS/CMS Opto WG March '10
Tony Weidberg 4
Summary Fibre RIA
• Assume plausible fibre routing based on ATLAS SCT
• Conservative calculation of total RIA at end of SLHC ignoring long term annealing– Predicts 0.4 dB for RIA for Infinicor SX+ fibre.– Infinicor SX+ fibre qualified for SLHC if operated
warm.– Draka RHP-1 and SMF-28 better than Infinicor SX+
fibre also qualified for warm operation. – 2 candidate fibres for SM (also have Fujikura fibre
for LHC machine) and MM.
ATLAS/CMS Opto WG March '10
Tony Weidberg 5
Cold Operation
• Inner Detectors will be operated cold @ SLHC (~ -25C).
• Will this affect the fibre radiation damage?
• Limited information available in the literature …
ATLAS/CMS Opto WG March '10
Tony Weidberg 6
Previous research on RIA in fibreMulti-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!
ATLAS/CMS Opto WG March '10
Tony Weidberg 7
Cold Irradiation of Fibres• First tests at Rita low dose rates
• Use Peltier coolers -25C.
4 Peltiers take heat from Al spool and dump it into water outside the cylinder.
Worked ok for low dose but can’t work for high dose because heat load too big and radiation resistance of Peltiers not good enough.
ATLAS/CMS Opto WG March '10
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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.
ATLAS/CMS Opto WG March '10
Tony Weidberg 9
Draka RHP-1 SRH fibre
T = -250 C
T = -40 CTotal Dose ~ 15 kGy(Si)
ATLAS/CMS Opto WG March '10
Tony Weidberg 10
Cold Irradiation Status
• Clear evidence that RIA for GRIN fibres is significantly larger at low T than room T.
• Need compact, rad-hard cooling system that can operate ~ -25C…
ATLAS/CMS Opto WG March '10
Tony Weidberg 11
Blow-off Evaporative CO2 System
CO2 bottle (50bara, 20°C)
vent
Service tube
Hex
Control room
Test vessel
capillaryEvaporator
Electrical heater
Return & feed pipe ¼” OD SS
Some flexible SS tubing needed here
Some flexible SS tubing needed here
Ice is likely to form in this tube!
Back pressure regulator (BPR)
ATLAS/CMS Opto WG March '10
Tony Weidberg 12
CO2 Cooling
• The C02 blow-off cooler progresses!
• Passed first safety test in Oxford (water).
• Start to test it as cooling system iterate lengths of capillary to achieve required pressure drops.
• Further safety tests and approval from SCK safety commission before it can be operated at SCK.
ATLAS/CMS Opto WG March '10
Tony Weidberg 13
Bandwidth Studies
• Many studies of fibre radiation tolerance but none (?) of fibre bandwidth after irradiation.
• Perform before/after radiation comparisons of the fibre bandwidth.
• First measurements (Annie Xiang)
• Draka measurements
ATLAS/CMS Opto WG March '10
Tony Weidberg 14
ATLAS/CMS Opto WG March '10
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ATLAS/CMS Opto WG March '10
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ATLAS/CMS Opto WG March '10
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Fibre Bandwidth Summary• Draka MMF-RH(1) is optimised for bandwidth
but should have same RIA as Draka MMF(1).• No evidence for significant degradation with
radiation but precision limitted.• Better measurements to be performed by Draka
on long fibre sample.
2 m 50m unirradiated 50 m irradiated
Rise (ps) 68 66 68
Fall (ps) 54 84 86
ATLAS/CMS Opto WG March '10
Tony Weidberg 18
Splitters (1)
• Fused taper splitters– Radiation damage is simply equal to
length of fibres used but devices are bulky.
• PLC Splitters– More compact– Radiation tolerance needs to be verified.– First samples from Leoni with active tests
gave inconclusive results (effects of temperature and radiation combined).
ATLAS/CMS Opto WG March '10
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Splitters (2)• Obtained samples 1*4 splitters from different manufacturers
– Browave (Taiwan): 10 devices– Huihong Technologies (China): 4 devices– Fibrenet packaging of 2 devices from WUHAN YILUT OPTICAL
COMMUNICATION CO.,LTD (Taiwan)– Fibrenet package of 1 device from Cololr-Corp: glass substrate
(not Si).– (Promised new samples from Leoni)
• Measure insertion loss before irradiation with multiple mate/demate cycles (all devices look ok).
• Study temperature effects with thermal cycling in environmental chamber.
• Irradiate at room temperature to 500 kGy(Si) using Mega Curie source in Taiwan.
• Repeat measurements after irradiation.