TITAN reveals shell model breakdown at the extreme: Certain combinations of protons and neutrons form exceptionally stable nuclei. While these closed-shell configurations are well understood in stable nuclei, they change in exotic nuclei. Previous mass determinations with TITAN found a closed shell for calcium (Ca) with 32 neutrons. Now, as reported in Physical Review Letters (2018), TITAN’s measurements of neighbouring titanium isotopes shows that the shell weakens more quickly than predicted by state-of-the-art nuclear theory. The results are also noteworthy as TITAN’s first measurements with its Multi-Reflection Time-Of-Flight mass separator (MR-TOF). The MR-TOF has a remarkable sensitivity, able to make precise measurements with just a single radioactive nucleus.