Pionic K X-rays in liquid 3He☆

Abstract Energies and lorentzian widths of pionic K X-ray transitions have been measured in liquid 3 He with improved accuracy. The strong interaction on the π 3 He 1s level is found to be attractive and to produce an increase in the K transition energies of 34 ± 4 eV; the measured lorentzian width is 36 ±7 eV. Measured values are also presented for K X-ray energies in liquid π 4 He and μ 4 He, the lorentzian width of the 1s level in π 4 He, and relative intensities of K X-ray transitions in π 3 He, π 4 He and μ 4 He. The measurements are compared with those of others and with recent theoretical calculations.