Emission of light nuclei $(p, d, t, \alpha)$ in the process of annihilation of slow antiprotons in nuclear emulsion

The annihilation of slow ($\sim7$ MeV) antiprotons in nuclear emulsion has been studied. The yields and energy spectra of $p$, $d$, $t$ and $\alpha$ particles in the evaporation region have been measured. The shape of the spectra of $p$, $d$ and $t$ is in agreement with the Maxwell distribution and the excitation energy of a nucleus is consistent with a theoretical estimate for evaporation from the equilibrium state. The probability of the absorption of antiprotons inside the nucleus estimated from the multiplicity of $h$ particles is $\varepsilon=(2.0\pm0.6)\cdot10^{-2}$. The relative $d/p$ yield coincides with a similar ratio appearing in the capture of slow $\pi^-$ mesons by nuclei in the nuclear emulsion. The yields of $t$- и $\alpha$ particles in the process of the annihilation of antiprotons are much higher than those in a similar process for pions. To identify $g$ particles $(0.29<\beta<0.70)$, energy losses $dE/dx$ on ionization and multiple scattering have been measured. In this velocity region, the yields of $p$, $d$, $t$, and pions have been observed. The ratios $(n_d/n_p)_g$, $(n_d/n_p)_b$ and $(n_d/n_p)$ measured in the capture of $\pi^-$ mesons are almost the same. In this velocity range ($g$ particles), $\alpha$ particles have not been observed.