Homogeneity of CVD diamond detectors in tracking applications

Abstract

Data obtained from ion beam induced charge collection measurements on “detector grade” CVD diamond samples have been used in order to “simulate” the collection of charge produced by a minimum ionizing particle. It turns out that both the electric field and the charge collection length are not uniform in the depth of the sample, whereas the profile of the charge collection efficiency is compatible with a linear behaviour of the product (mobility)×(lifetime) of carriers. This is here proposed as a new “linear model”, which is fully compatible with the “old” linear model in all the cases where the electric field is uniform. The contribution of electrons to the charge pulse seems to be in this case more important than that of holes. The homogeneity of the CVD diamond detector as a tracker for minimum ionising particles is higher than for low energy protons and it displays a behaviour as a function of the length scale which is in a relatively good agreement with data reported from measurements with diamond strip detectors.