What does "iron peak" mean in the collapse of a critical mass iron core?

[GIASAL]

The collapse of the critical-mass iron core accelerates rapidly. This runaway is driven principally by photodissociation of iron-peak nuclei, Fe(γ, α), and by electron captures

What does "iron peak" mean?

 

[phyzguy]

If you look at the binding energy per nucleon of atomic nuclei, it peaks in the vicinity of iron. You can get energy by fusing nuclei lighter than iron or by fissioning nuclei heavier than iron, but once nuclear fusion has arrived at nuclei near iron, no more energy can be obtained. Since no more energy is available from fusion, there is no radiation pressure to support the core against gravity, and the core collapses.

 

[GIASAL]

Is the binding energy per nucleon clearly equal to the energy required to extract a nucleon?