X-RAY SPECTROSCOPY OF KAONIC ATOMS AT DAΦNE

Abstract

The SIDDHARTA experiment aims a precise measurement of K -series kaonic hydrogen x-rays and the first-ever measurement of the kaonic deuterium x-rays to determine the strong-interaction energy-level shifts and widths of the lowest lying atomic states. These measurements offer a unique possibility to precisely determine the isospin-dependent kaon-nucleon ( KN ) scattering lengths [1] which are directly connected with the physics of the KN interaction. Kaonic Helium transitions to the 2p level ( L -lines) were as well measured. The experiment has been performed at the DAΦNE e+e- collider which produces the Φ-resonance. The resulting low energy negative charged kaons, coming from the Φ decay, are well suited to be stopped efficiently in a high density gas target for producing such kind of atoms. As x-ray detectors, we employed 144 Silicon Drift Detectors developed especially for this experiment, having good energy resolution of 140 eV FWHM at 6keV and time resolution of sub-micro seconds. The data taking was completed in November 2009. In this paper, an overview of this experiment and preliminary results are presented, together with future plans.