  Phase transitions in superconducting mesoscopic disks have been studied over
the H-T phase diagram through heat capacity measurement of an array of
independent aluminium disks. These disks exhibit non periodic modulations
versus H of the height of the heat capacity jump at the superconducting to
normal transition. This behaviour is attributed to giant vortex states
characterized by their vorticity L. A crossover from a bulk-like to a
mesoscopic behaviour is demonstrated. $C_{\rm p}$ versus H plots exhibit
cascades of phase transitions as L increases or decreases by one unity, with a
strong hysteresis. Phase diagrams of giant vortex states inside the
superconducting region are drawn in the vortex penetration and expulsion
regimes and phase transitions driven by temperature between vortex states are
thus predicted in the zero field cooled regime before being experimentally
evidenced.
