X-ray Detectors for Kaonic Atoms Research at DAΦNE

This article presents the kaonic atom studies performed at the INFN National Laboratory of Frascati (Laboratori Nazionali di Frascati dell’INFN, LNF-INFN) since the opening of this field of research at the DA Φ NE collider in early 2000. Significant achievements have been obtained by the DA Φ NE Exotic Atom Research (DEAR) and Silicon Drift Detector for Hadronic Atom Research by Timing Applications (SIDDHARTA) experiments on kaonic hydrogen, which have required the development of novel X-ray detectors. The 2019 installation of the new SIDDHARTA-2 experiment to measure kaonic deuterium for the first time has been made possible by further technological advances in X-ray detection.

KAONIC HELIUM MEASUREMENTS IN THE SIDDHARTA EXPERIMENT

The SIDDHARTA experiment (SIlicon Drift Detector for Hadronic Atom Research by Timing Application) had the aim to perform kaonic atoms X-ray transitions measurements, to better understand aspects of the low-energy QCD in the strangeness sector. The experiment combined the excellent low-energy kaon beam generated at DAΦNE, allowing to use gaseous targets, with excellent fast X-rays detectors: Silicon Drift Detectors. SIDDHARTA was installed on DAΦNE in autumn 2008 and took data till late 2009. Apart of the kaonic hydrogen and kaonic deuterium measurements, we have performed the kaonic helium transitions to the 2p level ( L -lines) measurements: for the first time in a gaseous target for helium4 and for the first time ever for kaonic helium3. The interest for such type of measurement was rather high, being it triggered by two reasons: the so-called "kaonic helium puzzle" (even if this was solved by KEK-PS E570 experiment, but a cross-check was useful) and some theoretical predictions of possible high energy shift (at the level of 10 eV). In this paper the preliminary results for the measurements to the 2p level ( L -series) for kaonic helium4 and kaonic helium3 are presented.

KAONIC ATOMS AT DAΦNE — THE SIDDHARTA EXPERIMENT

With precision X-ray spectroscopy of kaonic hydrogen at the DAΦNE electron-positron collider at Laboratori Nazionali di Frascati the chiral symmetry breaking scenario in the strangeness sector will be investigated by studying the K-p s-wave interaction at threshold. This is possible by observing the strong interaction induced shift and width of the 1s state in kaonic hydrogen atoms. The results of the first measurement at LNF with DEAR (DAΦNE Exotic Atom Research) will be given and the new SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research with Timing Application) project will be described, which is aiming at a substantial improvement of the preceding DEAR result.