We display the invariant amplitudes for the reaction $n+p\to d+\gamma$ in the absence of restrictions imposed by parity conservation, and demonstrate that Danilov's result that the circular polarization of the $\gamma$ depends only on the isoscalar parity-nonconserving interaction, and that the asymmetry of the $\gamma$ with respect to the neutron spin direction depends only on the isovector parity-nonconserving interaction, holds up to corrections of order $\frac{({\mu }_n+{\mu }_p-{\mu }_d)}{({\mu }_p-{\mu }_n)}\sim 0.005$. It is also pointed out that essentially the same amplitudes can be used to describe the reaction $n+d\to t+\gamma$.

[NUCLEAR REACTIONS ${}_{}{}^1{}_{}{}^{}\mathrm{H}(n,\gamma ){}_{}{}^2{}_{}{}^{}\mathrm{H}$, ${}_{}{}^2{}_{}{}^{}\mathrm{H}(n,\gamma ){}_{}{}^3{}_{}{}^{}\mathrm{H}$, thermal neutrons; formalism for calculating parity-nonconserving effects.]

• Received 26 December 1973

DOI:https://doi.org/10.1103/PhysRevC.9.1790