Production Status
21-10-2004
21-10-2004
Full Electrical and optical measurements of each barrel/EC harness are performed at RAL on receipt of harness. Critical length measurements are also performed. The summary is contained in the files below.
Barrel Harness Summary and Order on Barrels
EC Fibre harness and wiggly tapes: RAL test data
EC Fibre harness and wiggly tapes: NIKHEF test data
A test harness has been mounted on B3 using a specially designed vacuum pick-up jig to transfer the harness to the barrel. The new harness clips were used to hold the LMTs and fibres in place. Special clips were also used to hold the fibres to the castellation at the end of barrel. No show stoppers were encountered. Photos are available here:
harness on barrel and mounting tool
B3 and service cage with 8 harnesses
B6 with 105 harnesses (no cooling loops yet)
B6 with 112 harnesses(2nd photo)
A LH and RH test harness were mounted on B3 with the vacuum pick-up jig and the clearances were checked by mounting a dummy envelope module. There were problems between the top of the opto-package and the "hybrid" of the dummy module and the fibres and the dummy module for some of the 12 doglegs. This problem was caused by the S bend in the dogleg not being correct. The S bends were much too shallow. The LH harness was placed on the old harness forming jig and the S bend was remade for dogleg 2. The good S bend is much steeper than the shallow S bend:
Comparison of Good and Bad Bends
When the harness was remounted on the barrel, the clearances for dogleg 2 to the envelope module was excellent for both the opto-package and the fibres.
Dogleg on Barrel with good S Bend
A LH and RH harness from the second batch of 8 harnesses were mounted on B3. The quality of the dogleg S bends was much better for this batch of 8 than the first batch of 8. The fibre loops were also in general much better. The clearances from the opto-package and dogleg to the envelope module was checked and was very good in all 12 cases (see Clearances photo) . There was one dogleg with a problem with one of the fibres touching the module. This was due to one of the fibres emerging from the opto-package at the wrong angle and separately to the other two fibres (see non ideal fibre photo). By comparison take a look at the photo (ideal fibre photo) showing all three fibres emerging correctly together from a dogleg.
The quality of the dogleg bends was in general good but sometimes the bends were slightly skewed (skewed dogleg photo) which results in the dogleg not lying flat on the bracket (non-flat dogleg photo).
Mechanical grade doglegs were bent on the old Andy Coyle jig (designed for B3) and mounted on B6 at Geneva. An envelope module was used to check the clearances from the opto-package to the dummy hybrid. An old style blue opto cover was used which has a total height 0.25 mm more than the height of the production opto-packages plus cover. The expected clearance is therefore 1.4 mm (from the drawing) -0.25 mm = 1.15 mm. There was clearance when the envelope module was mounted on either a lower or upper brackets (photo of clearance for dogleg on lower bracket). The clearance was verified to be greater than 1 mm by inserting a gauge. The clearance for the short dogleg on the lower bracket was estimated from the photo as about 1.1 mm in good agreement with the expected clearance.
The first production harness (3050101) was mounted on B3 on 14/10/03. The doglegs nuts are attached to the brackets and the permanent harness clips are installed. The clearances were checked with the envelope module and were good for all 6 doglegs. We still have to add glue to the permanent harness clips and install the barrel end clamps. The fibres are stored in a temporary fibre box and will need to be routed around the barrel end to the correct location for the fibre box.
