Trigger Tests Patrick Robbe, LAL Orsay, 8 Feb 2012

Reminder Low rate errors seen in the hadron trigger, from time to time, usually after powering on/off a crate, and solved by re-plugging the cable (in a different connector or even in the same one) Reason not understood, very small effect on data but annoying for the automatic monitoring of the L0CALO. Problem is located in the 15.5 m ethernet cable between the HCAL FEBs and the TVB (in the ECAL crates). These cables transfer serialized trigger data (21 data bits on 3 pairs + 1 clock on the 4th pair) 2

Tests Cyril Drancourt designed small cards to understand the origin of the problem, these cards are inserted between the boards and the cable: – Attenuation board: attenuate the signal by 1, 2 or 3 dB, – Dephasing board: delay the clock or one data pair by 1ns compared to the other pairs, – Amplification board: increase the signal levels Two types of test: – ECS (CAT), consisting in sending from the FEB RAM known patterns that are read in the Spy memory of the TVB. Allowed delay ranges of the delay chip used to sample the data at the input of the TVB FPGA are scanned (after deserialization). – DAQ, consisting in using LED flashes in the HCAL and in using the L0CALO/CALO monitoring software to detect errors. 3

Tests (scans) 18 Feb with Marie-Noelle and Cyril, using TVB 9 (A-side, crate 19, right slot, connector 1) and a cable which gave problem in the past. 4 Delay (0 to 24 ns) Rising edge Falling edge Reference -1 dB Nb: the test cards induce some delay -2 dB -3 dB Ampli Data + 1ns Clock + 1ns

Tests (DAQ) Except the test where one data pair is delayed by 1ns, all tests have a large enough working range. Tested with DAQ the -3dB attenuation, and we observed no error during several hours. (However, we observed errors during the first attempts, they disappeared after unplugging/plugging the cable) Pb in the connector itself ? The attenuator is still in the cavern, and plugged. 5

Spare Cables We tested also a possible spare cable (we now have only one 15.5m spare cable): LEONI MegaLine G (skew of 3ns/100 m) The scan with CAT worked fine: I would like to install this cable in « parasitic mode » (ie using free connections that will not disturb the trigger) to test it for a longer time. 6 Delay (0 to 24 ns) Rising edge Falling edge Reference New cable

Conclusions No evidence of problem because of weak signal levels in trigger cables. Problem with connectors ? Perhaps have a dedicated test for that (plugging/unplugging) Continue tests with spare cable candidate to be sure it will work correctly for us. 7