What mechanism creates elements heavier than iron during the core-collapse supernova?

Answer

The r-process (rapid neutron capture)

Creating elements heavier than iron requires overcoming strong electrostatic repulsion by bombarding nuclei with neutrons in the high-flux environment of the collapsing core, known as the r-process.

What mechanism creates elements heavier than iron during the core-collapse supernova?
Elementastronomystarsupernovanucleosynthesis