Kaonic helium atoms Original Research Article

The KEK experiment E570 has measured the Balmer-series x-rays of kaonic 4He atoms using large-area silicon drift x-ray detectors (SDDs) in order to study the low-energy View the MathML source-nucleus strong interaction. The energy of the 3d→2p transition was determined to be View the MathML source. The resulting strong-interaction energy-level shift is in agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment. Using a similar setup, the E17 experiment at J-PARC, the first experiment to be carried out in the hadron hall of J-PARC, will measure the 3d→2p x-rays of kaonic 3He.