  Lattice QCD with Wilson fermions generically shows the phenomenon of a first
order phase transition. We study the phase structure of lattice QCD using
Wilson twisted mass fermions and the Wilson plaquette gauge action are used in
a range of beta values where such a first order phase transition is observed.
In particular, we investigate the dependence of the first order phase
transition on the value of the lattice spacing. Using only data in one phase
and neglecting possible problems arising from the phase transition we are able
to perform a first scaling test for physical quantities using this action.
