ИСТИНА

In this report we present the kinetic energy distributions of muonic and pionic hydrogen atom at the instant of the radiative transitions from $np$-states to the ground state or the charge-exchange reaction (in the case of pionic hydrogen). These distributions were calculated within the improved version of the extended cascade model at different values of the target density. In this model, we used the new differential and integral cross sections for collisional transitions between different atom states with the values of the principal quantum number n=2-12 calculated in the framework of the close-coupling approach. The initial (n,l,E)-distributions are taken into account and in the improved version of the cascade model lead to a very good agreement with the experimental data at very low target density. The results of the present cascade calculations allowed for the first time to explain the observed effects of the kinetic energy distributions and extract from the experimental data hyperfine splitting of the ground state in the case of muonic hydrogen and give the realistic description of the neutron time-of-flight spectrum in the case of the pionic atoms. In particular, our results for the first time explain the high-energy components around 105 eV and 209 eV (due to Coulomb transitions 5-3 and 3-2, respectively) and are in a very good agreement with the experimental weights of these components.