An isotope of iron (proton number Z=26Z = 26Z=26) is measured to have a nuclear radius of 4.59 fm4.59\text{ fm}4.59 fm.
Assuming the constant representing the radius of a single nucleon is r0=1.2 fmr_0 = 1.2\text{ fm}r0=1.2 fm, determine the number of neutrons in this iron nucleus.
