A snapshot of the Linac2 fixed display with the source pulsing at a rate of 1.2 seconds and a beam current of around 250 mA. In the coming week, the other bars in the graph should light up too, as the beam will be accelerated to the end of Linac2 soon.
The 2017 extended year-end technical stop (EYETS) is about to come to an end. Presently, the LHC magnets are being cooled down again, and then the powering tests will take place.
On 14 April, the LHC will be handed back to the operations teams, and in early May the first bunches with protons will be injected again. A beam intensity ramp-up will follow, which should bring the LHC to the level of performance experienced at the end of last year’s proton run by mid-June. The 2017 LHC proton physics run will then end in mid-December.
No ions are planned for the LHC in 2017. However, for the first time this year, xenon ions will be accelerated by Linac3 through LEIR, the PS and the SPS for use in the North Area experimental areas during an eight-week ion run in November and December. To accomplish this, the Linac3 ion source has been converted to a xenon ion source, commissioning of which started during the first week of March.
This year’s extended technical stop has been an opportunity to perform “open-heart surgery” on the CMS detector to replace the pixel tracker as well as an enormous amount of other work throughout the entire accelerator complex.
In the LHC, regular maintenance and repairs were performed in parallel to the replacement of a superconducting dipole magnet in sector 1-2, which went according to planning.
Much work was accomplished on the injector side too: a massive de-cabling campaign in the PS Booster and the Super Proton Synchrotron (SPS) has paved the way for the installation of new equipment for the LHC Injector Upgrade (LIU) project. The project will gradually be deployed in the coming years and it will culminate during long shutdown 2 (LS2).
A new internal beam dump was installed in the SPS during the second week of March. This was in response to a problem that occurred in April last year, during the preparation of the LHC beam in the SPS, when a vacuum leak developed in the SPS internal beam dump, limiting the number of LHC bunches per extraction out of the SPS to 96 for the entire 2016 run. Since then, a heroic effort has been made to re-design and produce a new internal beam dump, which was finally installed on Tuesday, 8 March and which will allow the SPS to reach its full performance again for the 2017 run.
The Linac2 proton source has been functioning again since the end of February. On Friday, 10 March, the Linac2 was closed for hardware commissioning to be followed by commissioning with beam. These are the first steps to get the whole LHC proton injection chain up and running again for another busy (and hopefully successful) year.