  Considering gravitino dark matter scenarios with a long-lived charged
slepton, we show that collider measurements of the slepton mass and its
lifetime can probe not only the gravitino mass but also the post-inflationary
reheating temperature TR. In a model independent way, we derive upper limits on
TR and discuss them in light of the constraints from the primordial catalysis
of lithium-6 through bound-state effects. In the collider-friendly region of
slepton masses below 1 TeV, the obtained conservative estimate of the maximum
reheating temperature is about TR=3\times 10^9 GeV for the limiting case of a
small gluino-slepton mass splitting and about TR=10^8 GeV for the case that is
typical for universal soft supersymmetry breaking parameters at the scale of
grand unification. We find that a determination of the gluino-slepton mass
ratio at the Large Hadron Collider will test the possibility of TR>10^9 GeV and
thereby the viability of thermal leptogenesis with hierarchical heavy
right-handed Majorana neutrinos.
