Last results from the DEAR experiment at DAΦNE

The goal of the DEAR (DAΦNE Exotic Atom Research) experiment is the precision measurement of the Kα line shift and width, due to the strong interaction, in kaonic hydrogen and the first similar measurement in kaonic deuterium. The final aim is a precision determination of the antikaon‐nucleon isospin dependent scattering lengths, in order to obtain the kaon nucleon sigma terms. In the first phase of the experiment, dedicated to the calibration and optimization of the setup, the experiment collected data on gaseous kaonic nitrogen: for the first time a pattern of three transitions (7 → 6 at 4.6 keV, 6 → 5 at 7.6 keV and 5 → 4 at 14 keV) was measured, and the corresponding yields obtained. The kaonic hydrogen measurement followed, in the last months of 2002, for a total integrated luminosity of about 60 pb−1 . Data analyses are in progress, preliminary results being hereby presented, together with those on kaonic nitrogen. Future measurements: kaonic deuterium, kaonic helium and precise determination of the...