Agenda of SCT links meeting
 9:00 - 11:30 Thursday 3rd June 1999 
 CERN Bat 40-C-SS02

1. PIN Diodes radiation results. (G Mahout).
2. VCSEL radiation and lifetime results. (I. Gregor).
3. SEU studies (I. Gregor).
4. VCSEL operation in B field (G. Mahout).
5. Fujikura fibre status (T. Weidberg).
6. Optopackages:
• GEC Phase 2. (T. Weidberg)
• Honeywell. (T. Weidberg)
• OSU (T. Weidberg)
• Truelight (A. Rudge)
7. DORIC4A, BPM & DRX status (R. Wastie).
8. DORIC4 radiation tests. (D. White).
9. BOC and off-detector for system tests '99 (M. Goodrick).
10. Harness production and testing (J. Troska).
11. Fibre Routing and patch panels (J. Troska/A. Nichols).
12. Forward SCT hybrids/optics tests (T. Smith)
13. Forward SCT fibre routing (T. Smith)

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Minutes

(1) G. Mahout reported the results of the PIN diode ageing tests. The irradiated PIN diodes showed no significant decrease in responsivity during the aging tests. The rise and fall times of the irradiated PIN diodes were shown to be fast provided a PIN bias voltage of greater than about 2V was used. The transparencies are available here.

(2) T. Weidberg reported on behalf of the Wuppertal group on the radiation and lifetime tests of the Mitel VCSELs. A sample of 4 VCSELs was irradiated at ISIS to a fluence of 2.9 10¹⁵ n/cm². These devices recovered when annealed at 20 mA. 20 VCSELs were  irradiated at ISIS to a fluence of 4 10¹⁴ n/cm². These devices annealed fully at 20 mA but only partially at 10 or 15mA. Therefore it is recommended to use 20 mA for VCSEL annealing.  An accelrated ageing test was performed and no devices failed. The conclusion was that at 90% c.l. the upper limit on the fraction of VCSELs that would fail in the 10 years of ATLAS operation is 0.2%. These tests need to be repeated at the higher fluences expected for the Pixel detector. The transparencies are available here.

(3) T. Weidberg reported on the results of the SEU studies at the Birmingham cyclotron. The n flux was 1.1 10⁶ n/cm²/s. No increase in BER was observed with the cyclotron on. These results are sufficient for the SCT but need to be repeated at an order of magnitude higher fluxes for the Pixel detector. The transparencies are available here.

(4) The first samples of the production batch of the Fujikura fibre has been successfully radiation tested. The fibre has now been ribbonised and sent to RAL.

(5) The status of the different options for the optopackages were reviewed:

• The GEC package is the most advanced and should be considered as the baseline option. The production of the phase 2 packages (2VCSEL+1 PIN) will start now. 2 packages will be delivered in 2 months and the 60 packages will be delivered in the next 5 to 7 months. The diagrams for these packages are available.
• Honeywell are producing VCSEL and PIN packages for CMS ECAL. We are expoliring the possibility of them producing suitable on-detector packages for us. They have provided us with a 12-way VCSEL array which we will radiation test. If this is successfull they will try to make a low mass on-detetcor package.
• OSU are developing ceramic packages to mount the VCSELs and the PINs. The first prototype VCSEL only package produced up to 300 microW. Improvements will be made in how the VCSELs are mounted to the ceramic and how the alignment of the base to the cap is performed. Results of the scans of this  device are available here.
• NIKHEF. F. Hartjes presented a package suitable for a plugable opto-package for the forward system tests based on Honeywell VCSELs and PINs. It is not clear if this could be a suitable option for the final ATLAS production. Transparenices are available (PowerPoint File).
• Truelight. A. Rudge presented results on tests of their prototype VCSEL and PIN arrays as well as a first atempt to produce an on-detector pacakge. The transparencies are available here.

(6)  DORIC4A and DRX will come bacl from AMS by the middle of this month. BPM should be back in the next week.

(7) A sample of 20 DORIC4s have been irradiated to 3 10¹⁴ n/cm² at Ljubljana and 10 MRads with a Co60 source at Birmingham. The devices were powered during the gamma irradiation. The devices all worked after irradiation and showed no degredation in performance.

(8) A. Parker reported on the status of the BOC card being developed by Cambridge. Information on the BOC is available here..

(9) J. Troska reported on the plans for the opto-harness test kit. The transparencies are available here.

(10) J. Troska discussed the issues relating to fibre routing and patch panels. The transparencies are available here

(11) T. Smith reviewed the status of the forward opto system with separated optics and electronics. First tests have shown that the cross-talk should be manageable. Tests on a prototype hybrid will be arried out in the next few weeks. These tests should be repeated with VCSEL/PIN packages when they are available.

(12). T. Smith reviewed the services for the forward SCT wheels. The designs are still based on the old drawings from T. Hill.