Neutron-proton radiative capture
= Neutron-proton radiative capture
{title2=$np\to d\gamma$}
Formation of a <deuteron> from a <neutron> and a <proton> with <photon> emission. For an initial pair at rest, two-body <energy> and <momentum> conservation gives $E_\gamma=B-B^2/[2(m_p+m_n)]$ in <natural units>, where $B=m_p+m_n-m_d$. The missing <binding energy> becomes <nuclear recoil>.