EXKALIBUR: Towards a Kaonic Atoms Periodic Table to Test Fundamental Interactions

Kaonic atoms, formed when a negatively charged kaon replaces an electron, provide a unique laboratory to test fundamental interactions at low energies. EXKALIBUR (EXtensive Kaonic Atoms research: from LIthium and Beryllium to URanium) is a program to perform systematic, high-precision X-ray spectroscopy of selected kaonic atoms across the periodic table at the DAФNE accelerator at the National Laboratory of Frascati. Here, we outline its detector-driven strategy: silicon drift detectors for 10–40 keV transitions in light targets (Li, Be, B, O), CdZnTe detectors for 40–300 keV lines in intermediate-Z systems (Mg, Al, Si, S), and a high-purity germanium detector for high-Z atoms (Se, Zr, Ta, Mo, W, Pb), complemented by VOXES, a high-resolution crystal spectrometer for sub eV studies. EXKALIBUR plans to (i) reduce the charged-kaon mass uncertainty below 10 keV, (ii) produce a database of nuclear shifts and widths to constrain multi-nucleon K--nucleus interactions models, and (iii) provide precision data for testing bound-state quantum electrodynamics in strong fields. We summarize the planned measurements and expected sensitivities within DAФNE luminosities.