DT Infrastructure: LV, HV, Gas CMS week 28 June 2011 A. Benvenuti (INFN Bologna)

A Few Problems Since May Workshop 5 Work Packages for LV related problems 6 WP for HV fixes Fan Tray Operation test (with Silverio Dos Santos) => It does not !

LV Problems In reality only two problems in YB-1: - A3100 Connector temperature - A3050 (MB1 MB2 S12) repeated power off due to high temperature interlock One UXC access was needed because the A3050 had lost communication due to the brutal switch off following the power cut. Was fixed by extracting and reinserting the module Vcon error on YB+2 MB3S12 only a modest temperature increase (but not the first time)

June 7, Temperature jumped to 37 °C MC OFF (May 24 @ 22:20) °C June 7, Temperature jumped to 37 °C MC OFF (June15 @ 22:16) MC OFF (June25 @ 07:12) YB-1 MB1, MB2 S12 LV Supply The A3050 switched OFF the MC on a high temperature interlock on May 24 ( 64°C), June 15(66°C) and June 25 (72°C) The first two instances were recovered quickly On June 25 , switching ON the MB1 MC caused again the interlock. The rest of the fill was taken with MB1 S12 MC off After the beams were dumped, ~13:20, the MB1 went ON, but we decided to replace the A3050 Looking at the error messages, I discovered two additional cases on February 10 and March 10 What should we do with this module? We can send it to CAEN but I am afraid they will not be able to reproduce the problem.

The temperature stabilized at 29.1 °C . Sensors Mounted on A3100 side Sensors mounted on cable connectors at SC side YB-1 Alarms started on June 24 ~13:00 as the temperature measured with V307 went above 27.7 °C The temperature stabilized at 29.1 °C . In UXC It was measured at 41.5 °C Disconnecting and reconnecting the cable brought V307 down to 25.8 °C The same incident occurred on May 20 The A3100 is in the same crate where we substituted the A3050 for MB1MB2 S12

LV Modules Temperatures The available cooling power is marginal for the crates with A3100 Check heat exchangers during next Technical Stop After the insertion trick the A3100 temperature dropped to 39 °C

HV Problems  16 Channels lost L2 16 Channels lost A876 Replaced 5 modules that failed in the detector but were OK in B904 were inserted in easy positions. OK so far YB-1 MB2S02, switched OFF while in STANDBY 3 DT stuck/tripped due to HV Spikes on wires while at step 1

HV Problems In Summary: 12 Chambers: 4MB1, 1MB2, 2MB3, 5MB4 6 in YB0, 2 in YB±1, 1 in YB±2 If the detector opens for the Pixels, priority to YB-2, we can recover 1 or 2 MB4

Planned Activities During Next TS Done Improving the TJB grounding consists of a few steps: - Substitute plastic cover with aluminum plate - add pigtail ground connection to TJB - close box with aluminum tape - connect ground shield on the cable with box - wrap everything with aluminum foil… Reduces synchronous noise (it can’t hurt) It is difficult to intervene on the TJB (if needed) 10 TJBs to be done Make the procedure simpler

Modified A3050s (Matteo) 4 Modified A3050 are in B904 Daniele will test them this Friday We will replace modules in YB0 sectors that already gave problems: MB1S01, MB4S02, MB2S10, MB3S04

Gas System Stable situation (no changes) YB0 H20 content (ppm) from March 08 to May 31 Stable situation (no changes) H2O content increased 30% (60% in peak) since March 8 O2 content in input lines varies from 82 to 106 ppm and from 89 to 103! In output Position of O2 spikes very stable N2 content measured in USG on common return line but data still not summarized H20 Content in peak from March 08 to June 14 It is summer, vacation time Decided with Roberto to consolidate: - O2 analysis cells calibration - H2O station calibration (YB0) - N2 last measured In September review some issues: Online gas chromatograph, H20 control (~400 ppm), O2 content (100 - 200 ppm)