CMS Bulletin

MUON DETECTORS: RPC

During LS1, the Resistive Plate Chamber (RPC) collaboration is focusing its efforts on installation and commissioning of the fourth endcap station (RE4) and on the reparation and maintenance of the present system (1100 detectors).

The 600 bakelite gaps, needed to build 200 double-gap RE4 chambers are being produced in Korea. Chamber construction and testing sites are located at CERN, in Ghent University, and at BARC (India). At present, 42 chambers have been assembled, 32 chambers have been successfully tested with cosmic rays runs and 7 Super Modules, made by two chambers, have been built at CERN by a Bulgarian/Georgian/Italian team and are now ready to be installed in the positive endcap. The 36 Super Modules needed to complete the positive endcap will be ready in September and installation is scheduled for October 2013.

The Link-Board system for RE4 is under construction in Naples. Half of the system has been delivered at CERN in June. Six crates (Link-Board Boxes) and 75 boards, needed to instrument the positive endcap are now under test in building 904 at the RPC electronic laboratory. The full system will be delivered and tested at CERN by the end of July for thorough testing and subsequent installation at Point 5.

Concurrently, activities in Point 5 are ongoing for maintenance and repair of the present system, which will start in mid-August. Functionality tests of the RPC Detector Control System (DCS) after its migration to the new architecture have started.  In addition, critical annual tests on the power system, gas-leak rates, and bakelite resistivity measurements are being performed.

Integration of the services on the positive endcap started last winter. 36 double gas patch panels were installed on the YE+3 periphery in March. Gas piping between the gas distribution rack and the panels was completed in April. Cooling mini-manifolds were installed and tested for leaks in early May. RPC trigger fibres, high-voltage cables and flexible gas pipes will be installed by the end of August.  RE+4 Link-System will be equipped with link/control boards and cabled by early September. Similarly, installation of all RPC services for the negative endcap (RE–4) should take place in the last trimester of 2013.

Hardware related activities for the RPC upgrade go hand-in-hand with software development. LS1 is the ideal period to extend the existing tools to meet the need of the upgraded detector, to implement all of improvements and changes of the CMS software framework (CMSSW), and to perform ageing studies. The extension of the existing tools to RE4 concerns DQM, reconstruction, simulation, and geometry. Extension of Offline tools is complete and extensive Monte Carlo validation tests are ongoing. Implementation of CMSSW improvements and changes span across different topics, such as: migration to Git, improvements in the geometry description, centralisation of monitoring tools. Finally, a task force has been put together to study and mathematically model detector ageing.