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CERN Accelerating science

LS1: A special opportunity for LHCb

by Rolf Lindner on behalf of the LHCb Collaboration

An unforgettable first act is drawing to an end for LHCb: incredibly productive data taking during LHC run 1, followed by a long shutdown (LS1), packed full with many tasks and at the same time ever increasing activity on the upgrade of the experiment...

LHCb operated with great success throughout LHC run 1 and has not been subject to any major intervention since its assembly in 2008. The current long shutdown offers a first opportunity for prolonged access, and hence an extensive programme of consolidation and maintenance work has been scheduled. This programme involves all general and detector related services, equipment and safety systems and requires very close collaboration between LHCb, PH support groups and the technical departments.

Figure 1: Installation of the 30 tons shielding for the LHCb muon detector where 2100 blocks were piled up in a confined space

In truth, major activities began already before the long shutdown with the consolidation of the Uninterruptable Power System (UPS). This intervention gave LHCb the possibility to introduce a much higher redundancy by redesigning the electrical distribution at all levels guaranteeing a zero down-time for a power outage of up to 20 minutes for the main online, controls and safety equipment. The success of this work was made possible thanks to the invaluable assistance of the Engineering Department.

The official LS1 started with the dismantling of the beryllium beam pipe, in order to prepare for the installation of a new third section. This intervention will allow the introduction of a new and much lighter support structure for the beam pipe, a project launched together with the Technology Department.

LHCb dipole consolidation. LHCb staff is working closely with members of the PH/DT on one clamp that holds the 25 tones coil in position. The clamp has to be open to exchange the protection between support and coil.

The removal of the beam pipe also facilitates the consolidation work required on the LHCb dipole. Here the support structures that keep the two 25 tons coils in their position have to be opened with large tooling equipment - a project that relies heavily on the expertise of the PH/DT-EO and EM2 groups.

The gas systems of all the LHC experiments require a thorough consolidation during the shutdown, and LHCb was the first experiment to be tackled by the DT gas group. This work was a challenging operation as the nominal pressure and flow through the detectors have to be guaranteed at all times.

Downstream of the experiment, just behind the last muon filter, the iron shielding has been substantially enlarged to protect the muon system from particles entering by the LHC tunnel.  Access to this area is extremely restricted making the operation a demanding task.  A total of 2100 blocks had to be piled up, one by one, to make up a wall of 30 tons built upon a newly installed support structure designed by the PH/DT group.

A large number of visitors have been welcomed at the experimental site over the last months.  To accommodate this large and constantly increasing number of people, a new viewing platform had been designed by the PH/DT-EO group and installed by the technical coordination team. This platform is now highly appreciated by the visitors. As a result LHCb can accept even larger groups by providing an easier and faster access without mitigating safety.

Finally, more than 600 access requests to the experimental cavern have been signed in total, which corresponds to the number of tasks executed at the experimental site over the last 12 months.