LS1 Report: A highly choreographed ballet in the SPS

With only one short month left until beam, the SPS teams have been kept busy with powering and operations tests. Alongside this demanding work, they have also successfully removed and replaced four key elements of the accelerator.

 

Since beginning their hardware-testing phase in early July, teams have been carrying out Electrical Power Converter tests and a wide range of start-up tests for the various equipment groups. Slotted amongst this busy schedule of tests were the final checks of the accelerator's magnets and beam dump. "There are three main types of magnet faults and we found we had one of each: an electrical fault (short circuit) in the magnet, a water leak (as the magnets are water cooled) and a vacuum chamber leak," says David McFarlane, the SPS technical coordinator from the Engineering Department. "On top of that, there was a problem with the main beam dump, which meant it also had to be replaced. In the end, rather than stopping the tests for each move, we decided to replace all four elements in one go. "

From 10 August to 12 August, the three magnets and beam dump were removed and replaced with spares in the SPS tunnel. "The logistics for this move were complex, as not only are the magnets and beam dumps extremely heavy, the chariot and lifting equipment used to move the items is a whopping ten tonnes," says McFarlane. "Furthermore, they are big pieces of equipment that take up the entire width of the tunnel. So coordinating which vehicles and teams were where and synchronising their movements was vital."

Although the SPS teams are well-versed at replacing magnets (swapping as many as four magnets in a two-day short technical stop), replacing the beam dump proved a tougher challenge. As the dump is radioactive, the length of transport had to be kept as short as possible and moving the dump from the tunnel to the radiation storage area could not take place if it rained! With this in mind, the Operations team created detailed plans for the move, providing hourly updates and back-up solutions in case of rain. "It was like a highly choreographed ballet - everything was well-timed and perfectly in synchronisation," confirms McFarlane.

Despite these replacements, the SPS is still on schedule to take beam from the PS in early September. The accelerator will be operational in October, providing beams to the North Area. 

Meanwhile, elsewhere...

At the LHC, the cooling of sector 1-2 is still in progress. The cooling of sector 5-6, which was next on the list, started at the end of last week. The vacuum teams are currently checking for any final leaks and carrying out sealing tests in various sectors.

At the same time, the CSCM tests (Copper Stabilizer Continuity Measurement) are in progress in sector 8-1, and will eventually be carried out throughout the machine. This week the first power tests will begin in sector 6-7, which will therefore be the first sector ready for beam. Electrical validation tests are in progress throughout the machine, along with instrumentation tests, particularly on the beam loss sensors. All of the collimators, the kicker magnets and the beam instrumentation in the straight sections of the LHC are now installed and under vacuum.

At the SPS, hardware tests revealed a damaged TIDVG (Target Internal Dump Vertical Graphite). It has now successfully been replaced and the machine is ready for testing of the power converters to recommence, in advance of the restart in October.

 

by Katarina Anthony