Whether they're restarting the accelerator or sending beam to North Area experiments, the SPS Operations team has been hard at work this month returning the machine to operation. Their work is more than just a flip of a switch - rather, operating it is more akin to completing a cryptic crossword...

Instead of your typical re-start, kicking off the SPS was rather like commissioning a new accelerator. From re-cabling campaigns above and below ground to last-minute magnet replacements and alignments, plenty is new in the SPS. "Commissioning a machine from scratch is rather like sitting in front of an empty crossword," explains Karel Cornelis, responsible for SPS operations. "At the beginning there is little to rely on. You may have an answer - or rather, a reading - but you can't be sure it is correct. Then, as more and more "words" are filled in, you can start to rely on your earlier answers. We get our answers from equipment, instrumentation and controls. To progress, we need to convince ourselves that the reading is right and can be relied on."

But what happens when all of the equipment you usually rely upon has been changed? "Usually, when we restart a machine, we can rely on readings from a part which has not been altered," says Karel. "But in the SPS, almost everything was changed so we were starting from scratch." Are the erroneous readings caused by the beam? The software? The magnets? Working out which is a delicate balancing act.

One of the main refurbishments affecting this balancing act was the addition of new function generators. By controlling the functions of SPS pulsing equipment (magnets, RF cavities), these generators are essential tools for the operation within the accelerator complex. Among their many benefits, the generators allow the SPS to be put in "coast", keeping the energy constant. They also feature an "economy mode": the magnets stop pulsing when there is no beam, thus saving energy (and money!). The new beam lines in the North Area also proved complex to calibrate. With work on-going until just 2 weeks ago, there was little time to commission the lines with beam.

"The main issues we found throughout the whole commissioning were installation errors: swapped or missing cables, sign bugs in the software, etc." explains Karel. These are human errors with a human solution: check, double-check and check again!

Meanwhile, elsewhere...

Great news! The last remaining sector (3-4) started its cool-down on Tuesday 14 October. Meanwhile, sector 8-1 completed its cool-down and now has ELQA testing ongoing with powering tests scheduled for two weeks time. In sector 5-6, CSCM testsare being carried out and, in sector 6-7, powering tests are ongoing.

The count so far? Two sectors of the machine have reached final cryogenic operating conditions.