Getting ready for the second run of the LHC

Kevin Burkett

Kevin Burkett, acting head of the CMS Center, wrote this column.

The end of the LHC shutdown is now in sight, and members of CMS and machine experts are both beginning preparations for the restart of LHC operations in 2015. The current long shutdown started after the completion of LHC Run 1 in February 2013. Run 1 was a tremendous success, and the experiments are still completing all their analyses using the data accumulated during the run.

Last week LHC machine experts gathered near CERN in Evian, France, to discuss plans for LHC operation in 2015. While the final decision on the collision energy will come after hardware tests of the LHC magnets later this year, the goal will be to deliver collisions at a center-of-mass energy of 13 TeV. This is close to the design energy and a significant increase compared to the 8-TeV collisions in 2012. A second goal is to cut the time between collisions in half, from 50 to 25 nanoseconds.

Members of CMS have been active during the shutdown, performing maintenance and improving the detector, as well as working to improve the algorithms used to reconstruct and identify the particles produced in collisions. Experts in computing have focused on improving the efficiency and reliability of the infrastructure while developing new tools for users.

An important milestone in our preparation for the start of data taking in 2015 is the upcoming Computing, Software and Analysis challenge, or CSA14. Simulated data samples are placed at sites around the globe and analyzed by members of the experiment. As the name suggests, this challenge allows us to test the readiness of many of the key aspects of our computing, offline software and physics analysis. Special emphasis will be placed on new procedures for users to access data and on validation of the output from the improved reconstruction algorithms.

Fermilab’s Joel Butler will lead CSA14. The exercise will require significant work from US CMS computing personnel, especially from the Scientific Computing Division. University members of the LHC Physics Center at Fermilab will also be active in CSA14 analysis. With time to address any issues uncovered in CSA14, CMS will be ready to go when the LHC starts up again in 2015.