The NA62 Experiment at CERN

The main physics goal of the NA62 experiment at CERN is to precisely measure the branching ratio of the Kaon rare decay $K^+\rightarrow \pi^+ \nu \bar\nu$. This decay is strongly suppressed in the Standard Model and its branching ratio is theoretically calculated with high accuracy. The NA62 is designed to measure this decay rate with an uncertainty better than 10\% percents. The measurement can be a good probe of new physics phenomena, which can alter the decay rate. The NA62 experiment has been successfully launched in October 2014. In this article, after the introduction at the theoretical framework, the NA62 experiment is described and the preliminary pilot run results are shown.