CERN Accelerating science

LHCb prepares for the major upgrade in LS2

by Rolf Lindner and Eric Thomas

Following the excellent performance of the LHC machine and after a very successful year for LHCb with a recorded luminosity of 1.7 fb-1 over the year 2017 LHCb goes now into the Years-End-Technical-Stop YETS.

The experiment has taken data very efficiently with a detector operating smoothly over the entire period. However most of the detectors will require maintenance and small repair work. This is particularly true for the Muon system which will be opened for the first time since two years.  Nine MWPC chambers (out of 1368), randomly distributed inside the detector, will be replaced. Three of them were recently manufactured in collaborating institutes on purpose. Similarly 2-3 GEM detectors (out of 24) will be exchanged by new ones. The other large detectors (HCAL, ECAL, Outer Tracker) will also be opened to work on some PMTs, fix the electronics, and improve grounding. A few HPDs of RICH 2 will also be replaced toward the end of the Technical Stop. Emphasis will be set as well on the detector services, mainly the detector cooling and gas systems on which an extensive maintenance is scheduled.

Concerning the safety systems, service and tests are planned for the Alarm Level 3 equipment and the Detector Safety System, including upgrade of CPU firmware.

A major work at point 8 will be the exchange of the lift for the LHC machine. Although this work will actually not be in the experimental cavern, the personnel working on the LHC machine sector in the vicinity of LHC Point 8 will have to pass thorough the LHCb experiment. Preparation for this passage have been concluded and means for a safe passing of the cavern will be put in place before the Christmas Closure of CERN.

As the LHCb detector is in good shape and the repair and maintenance work is certainly manageable in the coming month, the LHCb collaboration will concentrate on the preparation for the massive upgrade of the experiment in the long shut-down 2019/20. First cooling transfer lines for the future Vertex Locator and Upstream Tracker were already installed in collaboration with the groups EP-DT and EN-CV, and final tests will take place over the next weeks, including the installation of the junction box that distributes the coolant close to the detector.

Preparation towards the new data centre at point 8 are progressing well. Very recently and with the great support by IPT, the contract for the data centre modules have been signed and the delivery of the first module is scheduled for autumn 2018. In close collaboration with the SMB and EN department, studies for the infrastructure are pursued intensively, as they have to be in place in summer next year.

With the LHC Run 3, Data from all detector Front-End electronics will be sent continuously at 40 MHz over optical fibres to 500 Readout boards into the data centre, 350m away from the detector at the surface, where they will be processed in the PC-Farm. Here, another milestone has been successfully achieved. The Readout boards, called TELL40, have been designed, prototyped and tested, ready for the production. The tendering process has been completed and the company for the board assembly will be selected soon.

Production of the upgraded detector has started in many collaborating institutes and the assembly areas at the experimental site are ready to accept the different sub-system parts for being put together. Modules for the SciFi Tracker have arrived last summer already. Transport and handling tools for the new systems have been design and the first ones are already constructed. To ease the dismantling, transport and storage of existing detector parts, special structures were developed and the construction of these is schedule for the first months of next year. In order to ensure a fast dismantling of the obsolete detector and service systems in LS2, storage areas will have to be erected close to the experimental hall. Negotiations with all stakeholders at LHC Point 8 are completed and areas for a new temporary construction have been defined.

Finally, it should be noted that for every activity in LS2, Work Package Procedures are being established, including all safety aspects. These documents are crucial for a smooth process of the dismantling and installation at the experimental site and will be finalized during a comprehensive LHCb installation review in May 2018.

In less than one year the Long Shutdown 2 will start and the experimental cavern will be open for two years then. Although there are still some critical hurdles to be overcome and the schedule is very tight, the LHCb collaboration is excited as this moment approaches quickly. But before that, the experiment will prepare for another successful year of data taking.


Read also an article on “Grand Unification” of data taking for the LHCb experiment" discussing the simultaneous recording from p-p collisions at 5 TeV and a parallel stream from fixed-target collisions.


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