THE DISTANCES TO THE GALACTIC PLANE OF OLD NEUTRON-STARS

We compare different methods that have been used to describe the distr ibution of distances z to the Galactic Plane in pulsar population stud ies. Numerical solution of the equation of motion in the Solar Neighbo urhood for pulsars that all have the same age leads to distributions i n z with maxima some distance away from the plane. The z and velocity upsilon(z) in the z-direction are strongly correlated. Analytic soluti ons that approximate such z-distribution with a Gaussian do not descri be this well. However, we show that the difference between semi-analyt ical and fully numerical population studies is not large, due to the p referential detection in sky surveys of young and nearby radio pulsars .