  Using ac susceptibility, we have determined the pressure dependence of the
metamagnetic critical end point temperature T* for field applied in the
ab-plane in the itinerant metamagnet Sr3Ru2O7. We find that T* falls
monotonically to zero as pressure increases, producing a quantum critical end
point (QCEP) at Pc~13.6 kbar. New features are observed near the QCEP -- the
slope of T* vs pressure changes at ~12.8 kbar, and weak subsidiary maxima
appear on either side of the main susceptibility peak at pressures near Pc --
indicating that some new physics comes into play near the QCEP. Clear
signatures of a nematic phase, however, that were seen in field-angle tuning of
T*, are not observed. As T* is suppressed by pressure, the metamagnetic peak in
the susceptibility remains sharp as a function of applied magnetic field. As a
function of temperature, however, the peak becomes broad with only a very weak
maximum, suggesting that, near the QCEP, the uniform magnetization density is
not the order parameter for the metamagnetic transition.
