SPS completes LS1 activities

On 27 June, the SPS closed its doors to the LS1 engineers, bringing to an end almost 17 months of activities. The machine now enters the hardware-testing phase in preparation for an October restart.


Photo 1: The SPS transfer tunnel, TT10, reinforced with steal beams.

Having completed their LS1 activities right on schedule (to the day!), the SPS team is now preparing the machine for its restart. Over the next eight weeks, hardware tests of the SPS dipole and quadrupole power converters will be underway, led by the TE-EPC (Electrical Power Converters) team. "OP start-up test activities will also be running in parallel, utilising the off hours when EPC is not using the machine," says David McFarlane, the SPS technical coordinator from the Engineering Department. "The primary beam testing phase will start at the beginning of September, once hardware tests and DSO safety tests have been completed."

It has been a long journey to this point, with several major interventions carried out across the accelerator involving teams from all of CERN's departments. Among these many interventions was the complete re-cabling of long straight section 1 (LSS1). "LSS1 is the injection point from the PS and also houses the beam dump. All the cables in the LSS1 region were damaged by radiation and needed to be completely replaced," explains McFarlane. "In order to reduce the dose for our teams and to improve accessibility, we removed all the machine elements while the work was underway. This cabling work alone took 22 weeks and was then followed by the complete reinstallation of the machine."

Unexpected civil-engineering work was also carried out in the TT10 transfer tunnel, which links the PS to the SPS. In early 2013, surveyors noted that the tunnel's age had started to catch up with it, resulting in cracks and other structural issues. Support beams (see photo 1) were installed at critical points along the length of TT10 - work that required most of the beam line to be removed! Monitoring devices were also installed, ensuring that future issues are noticed well in advance.

Photo 2: One of the water reservoirs used during LS1 activities.

Meanwhile, above ground, the high-voltage electrical cables between the SPS points have been completely replaced. "We were able to do most of this work in the years prior to LS1 by laying the new 18 kV cables without connecting them," says McFarlane. "During LS1, we upgraded the machine's transformers and then linked these new cables for the first time."

The SPS's primary water valves were also replaced during LS1, which required the injector's water supply to be fully drained. "As well as losing the main water supply for the magnets, this also drained the water supply for the fire-fighting system," says McFarlane. "So while this work were ongoing, massive external water reservoirs (see photo 2) were placed at each point. Had there been an incident, the Fire Brigade would have used these as their supply."

With all this work now complete, the SPS team are now shifting their focus back to operation with beam. At the end of August, the machine will officially be handed back to the Operations group.

by Katarina Anthony