This page contains results of the tests of the pre-series Barrel Harnesses.

Opto-package Yields

A report on the performance and yield for the opto-packages manufactured for the pre-series is available  here.

Mechanical Clearances:

This has been studied with Eric's mounting jig. A report is available here.

Electrical Performance First Pre-series Harness

The electrical functionality of the harness has been measured with the RAL test system. All the TTC, data links and redundant TTC links are working. The only problem was the amplitude of the LVDS clock output from one dogleg was 50% of the normal value.

VCSEL LI Curves

The results show mean power for 50% duty cycle. One VCSEL is therefore below the new specification (this was simply due to an error in the selection during assembly).

TTC BER Scan

Data link BER scan

Tests of Pre-series Harness with an SCT Module

An SCT barrel module in its box was connected to one of the doglegs on the first pre-series harness. Photos are available

• Module on harness end view
• Module on harness top view

The module box was roughly covered with a black bag to minimise light leaks. This was not very hermetic and the total leakage current was 9.7 mA. There were 4 known dead chips on this module. Apart from these 4 dead chips, the module appeared to be fully functional.

3 point scans were performed to measure the gain and noise. The results of the fits are available as a pdf file The measured input noise was in the range 1500 to 1600 electrons. The summary file is available here.

Tests have been performed to measure the noise on this module mounted in all 6 doglegs for harness 1. The noise for the module mounted on doglegs 1,3,4 or 5 was in the range 1370 to 1470. The noise when the module was mounted on dogleg 2 or 6 was higher, in the range 1620 to 1750. The tests were repeated with the preseries harness#3 and the noise was very similar for the module mounted on all doglegs and was in the range 1330 to 1500. The bad noise performance for the module mounted on doglegs 2 or 6 on harness 1 was due to an intermittent HV connection. This was fixed for dogleg 6 on harness 1 by firmly mating the connectors joining the LMT interface PCB to the dogleg. After this was done the noise on the module was measured and found to be in the range 1320 to 1490.

Modules and Harness on Sector

The pre-series harness#3 was mounted on the sector:

• The doglegs were mounted on the brackets as shown in the picture.
• The fibres were arranged with the harness clip.
• Photo of the complete harness mounted on the B3 sector.

The noise has been measured for 3 of the modules on the sector. The results of the noise scans are available:

• module k3104 ps file
• module 18 ps file
• module 36 ps file

These noise measurements are similar to those obtained with the same modules on the electrical test stand at CERN.