In this paper, which is the second in a series of papers, we analyse what
parameters can determine the width of the radio pulsar 'death valley' in the
$P$ -$\dot{P}$ diagram. Using exact expression for the maximum potential drop,
which can be realised over magnetic polar caps and the corresponding threshold
for the secondary plasma production determined in Paper I, we analyse in detail
the observed distribution of pulsars taking into account all the possible
parameters (radius $R$ and moment of inertia of a neutron star ${I}_{\mathrm{r}}$ ,
high-energy tail in the $\gamma $ -quanta energy distribution giving rise to
secondary particles, etc.) which could broaden 'the death line'. We show that
the consistent allowance for all these effects leads to a sufficiently wide of
'the death valley' containing all the observed pulsars even for dipole magnetic
field of a neutron star.