Abstract
We examine the momentum dependence of $\bar p$$p$ and $\bar n$$p$
annihilation cross sections by considering the transmission through a
nuclear potential and the $\bar p p$ Coulomb interaction. Compared to
the $\bar n p$ annihilation cross section, the $\bar p p$ annihilation
cross section is significantly enhanced by the Coulomb interaction for
projectile momenta below $p_{\rm lab} <$ 500 MeV/$c$, and the two
annihilation cross sections approach the Pomeranchuk's equality limit
[JETP {\bb 30}, 423 (1956)] at $p_{\rm lab}\sim 500$ MeV/$c$. Using
these elementary cross sections as the basic input data, the extended
Glauber model is employed to evaluate the annihilation cross sections
for $\bar n$ and $\bar p$ interaction with nuclei and the results
compare well with experimental data.
