Tracker electronics testing at Imperial College London

Jonathon Fulcher and Rob Bainbridge testing a rack of CMS Tracker readout electronics at Imperial College London. The signals from the front end APV chips will be transmitted optically to racks of electronics ~100m away in an adjacent underground cavern where they are fed into ~20 crates where 500 CMS Front End Driver boards (FEDs) are located. The FED inputs are 8 fibre ribbons, each ribbon consisting of 12 fibres, each fibre carrying the serially multiplexed data originating from 2 APVs. To test the FEDs special tester boards have been designed to produce simulated APV data in optical form. In the picture the yellow cables are the fibres, which originate from the FED tester boards on the left hand side of the crate as 96 individual fibres, which are then combined into the 8 fibre ribbons feeding the FED board on the right hand side of the crate. Fig. 2 shows an APV25 test board mounted in the X-ray irradiation setup, Fig. 3 the X-ray machine where the chips are irradiated and Fig. 4 the MGPA (Multi-Gain Pre-Amplifier) chip under test. Picture by: PPARC, UK