Absorption of negative k-mesons and the neutron and proton distributions in heavy nuclei

Negative K-mesons captured by the heavy nuclei in nuclear emulsion form K-mesio atoms. It is shown that absorption occurs in the nuclear surface and takes place when the K−-moson is in a 5g state. Observations on capture events producing a visible σ−-hyperon, and on the ratio of π+ to π−-mesons created can give information on the relative neutron and proton densities in the part of the nuclear surface where the total density is less than 10% of the density at the centre of the nucleus. Experimental evidence suggests that in this region of the nucleus the density of neutrons is approximately equal to the density of protons.