Straw tracker prototype for the precise measurement of the very rare decay (NA62 experiment at SPS CERN)

The proposal (CERN no. P326) for a new experiment, NA62, is described. This experiment aims to perform a precise measurement of the very rare kaon decay K + → π + ν ν ¯ branching ratio. About 80 K + → π + ν ν ¯ events with 10% of background are expected to be obtained in two years of data taking. To reconstruct charged pion tracks with high efficiency and high resolution a single magnet spectrometer based on straw tubes, working in vacuum, should be designed and produced. The current status of R&D of this detector and the results of its prototype tests are discussed.