1. ATLAS/CMS Opto WG March '10 Tony Weidberg1 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.

2. ATLAS/CMS Opto WG March '10 Tony Weidberg2 GRIN Fibres VCSEL @ 850 nm source Brigitte Co60 source   up to full SLHC dose (kGy) Also performed tests at lower doses, Rita and BNL.

3. ATLAS/CMS Opto WG March '10 Tony Weidberg3 SM Fibre SMF-28 SM fibre, 1310 nm EEL source. SMF-28 better radiation tolerance than GRIN fibres (as expected for longer ).

4. ATLAS/CMS Opto WG March '10 Tony Weidberg4 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.

5. ATLAS/CMS Opto WG March '10 Tony Weidberg5 Cold Operation Inner Detectors will be operated cold @ SLHC (~ -25C). Will this affect the fibre radiation damage? Limited information available in the literature …

6. ATLAS/CMS Opto WG March '10 Tony Weidberg6 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!

7. ATLAS/CMS Opto WG March '10 Tony Weidberg7 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.

8. ATLAS/CMS Opto WG March '10 Tony Weidberg8 Comparisons, InfinicorSX+ T = +30 0 C Dose = 65 kGy(Si) T = -23.3 0 C Dose = 30 kGy(Si) Gamma source at room temperature. Variation is from prev. Stability limitations.

9. ATLAS/CMS Opto WG March '10 Tony Weidberg9 Draka RHP-1 SRH fibre T = -25 0 C T = -4 0 C Total Dose ~ 15 kGy(Si)

10. ATLAS/CMS Opto WG March '10 Tony Weidberg10 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…

11. ATLAS/CMS Opto WG March '10 Tony Weidberg11 Blow-off Evaporative CO 2 System CO 2 bottle (50bara, 20°C) vent Service tube Hex Control room Test vessel capillary Evaporator Electrical heater Return & feed pipe ¼” OD SS Some flexible SS tubing needed here Ice is likely to form in this tube! Back pressure regulator (BPR)

12. ATLAS/CMS Opto WG March '10 Tony Weidberg12 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.

13. ATLAS/CMS Opto WG March '10 Tony Weidberg13 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

14. ATLAS/CMS Opto WG March '10 Tony Weidberg14

15. ATLAS/CMS Opto WG March '10 Tony Weidberg15

16. ATLAS/CMS Opto WG March '10 Tony Weidberg16

17. ATLAS/CMS Opto WG March '10 Tony Weidberg17 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 m50m unirradiated50 m irradiated Rise (ps)686668 Fall (ps)548486

18. ATLAS/CMS Opto WG March '10 Tony Weidberg18 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).

19. ATLAS/CMS Opto WG March '10 Tony Weidberg19 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.