  The phase diagram of the superconducting high-Tc cuprates is governed by two
energy scales: T*, the temperature below which a gap is opened in the
excitation spectrum, and Tc, the superconducting transition temperature. The
way these two energy scales are reflected in the low-temperature energy gap is
being intensively debated. Using Zn substitution and carefully controlled
annealing we prepared a set of samples having the same T* but different Tc's,
and measured their gap using Angle Resolved Photoemission Spectroscopy (ARPES).
We show that Tc is not related to the gap shape or size, but it controls the
size of the coherence peak at the gap edge.
