1. 1 Optical fiber irradiation tests 1.Results from ATLAS LAr 2.Narrow down to Germanium doped GRIN fiber 3.Preliminary tests 4.Tests in the plan Jingbo Ye for the SMU team

2. J. Ye, Dept. of Phys. ATLAS CMS optoelectronics working group meeting 2 Results from ATLAS LAr Ref: Nucl. Phys. B, Proc. Suppl. 78 (1999) 719-24 Irradiation studies of multimode optical fibres for use in ATLAS front-end links POF: Plasma Optics Fiber, Germanium doped. From the production qualification tests:

3. J. Ye, Dept. of Phys. ATLAS CMS optoelectronics working group meeting 3 Results from ATLAS LAr From ATLAS LAr fiber selection: Germanium doped MM fiber from Plasma Optical Fibres have been found to withstand radiations over 800~Gy(Si) and 2 × 10 13 cm -2 (1-MeV equivalent in Si) with less than 0.1~dB/m attenuation. The fiber batch used for the production of the optical cables was verified using a Co-60 source. Two 5 cm diameter rolls with 100~m of fiber each were irradiated with a dose rate of 150 Gy/hr. After 1 hour of irradiation the transmission loss over the 100 m was less than 10% or less than -0.005 dB/m. Immediately after 2 hours irradiation (300 Gy) the loss was -0.04 dB/m, but it improved to -0.015 dB/1m within 10 minutes, indicating a fast annealing process was taking place. The optical loss was measured to be -0.135 dB/m immediatly after the total dose reached 2.8 kGy. Within 1 hour annealing at room temperature, the loss was reduced to -0.1 dB/m, satisfying the requirement we set for radiation induced optical power loss. We expect the actual loss in real ATLAS environment is much less than -0.1 dB/m due to the fast annealing process. Because there are only a few meters of fiber that is actually at the FEB location, we estimate a maximum optical power loss due to radiation to be less than 1 dB, well within the 10 dB power margin we have.

4. J. Ye, Dept. of Phys. ATLAS CMS optoelectronics working group meeting 4 Narrow down to Germanium doped GRIN fiber Ref: IEEE Trans. On Nuclear Science, Vol. 54, No. 4, Aug. 2007, Low-Dose Radiation-Induces Attenuation at InfraRed Wavelengths for P-Doped, Ge-Doped and Pure Silica-Core Optical Fibers 850 nm 1300 nm

5. J. Ye, Dept. of Phys. ATLAS CMS optoelectronics working group meeting 5 Preliminary tests Gamma (Co-60) and Proton (230 MeV) tests Infinicor SX+ 50/250  m/1.6mm MM 10G fiber from Corning. Germanium doped. Very small light loss at low flux (dose rate). Big loss at high flux but anneals very quickly (within 1 hour) back.

6. J. Ye, Dept. of Phys. ATLAS CMS optoelectronics working group meeting 6 Preliminary tests Co-60 at BNL, dose rate: 30 krad/hr. Fiber: Corning Infinicor SX+ 50/125 MM fiber, 45 m under irradiation. Total RIA: 0.04 dB/m after 1.4 Mrad. Annealing effects observed. More annealing results will follow once we get our equipment back to SMU. Run #Dose (krad) Accumulated dose (krad) fibre RIA (dB) Accumulated RIA (dB) Ref. fiber (dB) Accumulated ref. fiber (dB) 1 133.00 -1.05 -0.10 2 700.00833.00-0.79-1.840.01-0.09 3 573.001405.00-0.07-1.910.00-0.09

7. J. Ye, Dept. of Phys. ATLAS CMS optoelectronics working group meeting 7 Tests in the plan We plan for another Co-60 at BNL end of July on more Infinicor SX+ fibers, at 850 nm light source. Should we test with 1300 nm light source? Test plan will be coordinated by Oxford group. Annealing will be monitored after the irradiation for a day or two. This may be our last test on the Infinicor SX+ fiber.