After the long-shut down the SPS accelerator restarted in the beginning of October along with a new experiment, NA62.  In contrast to the LHC, where new physics is studied at the highest possible energy, NA62 challenges the Standard Model by looking at tiny quantum fluctuations in ultra-rare kaon decays. These rare decay channels, like   Κ -> πνν are very attractive processes for physicists, because their branching ratios can be calculated in the Standard Model with very high precision.  Unfortunately, measuring such decays is far from easy as their decay probabilities are only about 1 in 10 billion.

Despite these difficulties, 160 physicists from 28 institutions took up the challenge to measure the K⁺ -> π⁺ ν ̅ν decay and build the NA62 detector during the last 6 years. The design chosen makes use of the SPS North-Area extraction line which provides a high intensity hadron beam (containing 6% kaons) at 75 GeV/c.

The NA62 experimental hall in Prevessin. 

The high momentum of the incoming kaons improves the background rejection and sets the longitudinal scale of the experiment (270m from the target to the beam dump).  The detector consists of tracking devices for the K⁺ and the π⁺ and calorimeters to veto muons, positrons  and photons, as well as Cherenkov detectors for further particle identification.

The current run that started this autumn is the first data taking with - practically – every piece of the detector in place.

Busy time at the NA62 control centre as the experiment is ready to search for new physics. 

The collaboration is now focusing on commissioning the beam line, the detectors and the data acquisition system.  Kaon decays from the first runs have been reconstructed, and the brand new sub-systems, like the 17m long RICH, the Straw Tracker or the new read-out of the Liquid Krypton Calorimeter (called CREAM) have already provided a wealth of data.  Another milestone will be reached in mid-November when the new Si-pixel detector, GigaTracker (GTK), will be included for the first time in the data talking.  

Although it might be too early to look into kaon rare decays, the collaboration expects to gain a first understanding of the performance capabilities of the detector during this run. Stay tuned for more updates to come.