Authors: Natasha Dobrinen and Sy-David Friedman Affiliation: KGRC, University of Vienna Address: Waehringer Strasse 25, 1090 Wien, Austria Email: dobrinen@logic.univie.ac.at Title: On the consistency strength of the tree property at the double successor of a measurable cardinal Abstract: Given any regular cardinal $\kappa$ and a weak compact $\lambda$ above $\kappa$, Mitchell showed that $\lambda$ can be collapsed to $\kappa^+$ in such a way that in the forcing extension, $\kappa^+$ has the tree property. His methods used a mixed-support iteration of various Cohen forcings. We show that iterated generalized Sacks forcing can achieve the same goal. We then use these iterations to obtain a model where the tree property holds at the double successor of a measurable cardinal, using much weaker hypotheses than were previously known to suffice.