Finite Temperature Phase Diagram of QCD with improved Wilson Fermions

We present results of an ongoing study of two flavour QCD with Wilson fermions at finite temperature. We have used tree level Symanzik improvement in both the gauge and fermion part of the action. The phase diagram was previously determined on an $8^3 \times 4$ lattice and the existence of Aoki's phase demonstrated. On our current lattice of $12^2 \times 24 \times 4$ we have extended the set of observables and studied chiral and thermal properties at light quark masses.