Past exam of the particle and nuclear physics course of the University of Cambridge / 2014 / Paper 1 / 4 / b / i / Solution

An electric multipole has radiation parity $(-1{)}^L$ and a magnetic multipole parity $(-1{)}^{L+1}$. The radiation quantum numbers are thereforeEquivalently, an $EL$ transition requires ${\pi }_f/{\pi }_i=(-1{)}^L$, while an $ML$ transition requires ${\pi }_f/{\pi }_i=(-1{)}^{L+1}$.