The binding energy per nucleon for deuteron $\left[{}_1{}^2\mathrm{H}\right]$ and helium $\left[{}_2{}^4\mathrm{He}\right]$ are $1.1 \mathrm{MeV}$ and $7 \mathrm{MeV}$ respectively. The energy released when two deuterons fuse to form a helium nucleus is