INFRASTRUCTURE

During the May 31st to June 2nd LHC Technical Stop, a major step was made towards upgrading the endcap cooling circuit. The chilled-water regulation valve on the primary side of the heat-exchanger was changed. This now allows reduction of the set-value of the water temperature cooling the RPCs and CSCs of the CMS endcaps. At the same time, the bypass re-circulating valve on the secondary circuit of the heat-exchanger was also changed to allow better regulation of this set-value.

A project has been launched with the objective of improving the distribution of the chilled water to the different users. This was triggered by evidence that the Tracker compressors in USC55 receive insufficient flow. The chilled water is shared with the HVAC system and experts are now looking at how to better balance the flow between these two main users.

The cooling loop filters located in UXC55 have been inspected and cleaned. Samples were sent to CERN Radioprotection Service to check for activation and to the Material Analysis Lab to measure the dissolved metal content.

Concerning the powering infrastructure, the main activity has been the debugging of the many spurious alarms on the powering control system. Hundreds of fake alarms were active, due essentially to incorrect addressing. The alarms were previously masked to allow operation, but they were still a source of concern for the operators. They have been all cleared and the status displayed on the console now respects properly the actual condition of the power system.

A new UPS will be installed to secure the experiment control room against power cuts. Two new switchboards have been ordered and will be installed soon.

In collaboration with the CCC, a first release of the GTPM project (Gestion Technique des Pannes Majeures) has been presented to CMS Technical Coordination. This is a new interface for real-time monitoring of the status of CMS infrastructures, with both the P5 shift crew and the CCC sharing the same screen-shots. A lot of effort has been made to make the system easily readable, considering that in some cases a fault of a single node might affect more than a hundred sub-nodes. The Technical Shifters are now getting acquainted with a beta-version of the current implementation.

by Andrea Gaddi