p+D→p+p+nReaction at6.5≤Ep≤13MeV

The $D(p, 2p)n$ reaction was studied in a kinematically complete experiment at proton bombarding energies of 6.5-13.0 MeV. Silicon surface-barrier detectors were used to record coincident proton-energy spectra at the two sets of angles ${\theta }_1={30}^{\circ }$, ${\theta }_2={30}^{\circ }$ and ${\theta }_1={30}^{\circ }$, ${\theta }_2={\theta }_p$, where ${\theta }_1$ and ${\theta }_2$ are on opposite sides of the beam axis and ${\theta }_p$ is the proton angle corresponding to an $n-p$ system with low relative energy recoiling at ${\theta }_1={30}^{\circ }$. The spectra at ${\theta }_1={30}^{\circ }$, ${\theta }_2={30}^{\circ }$ were dominated by the direct knockout or quasifree mechanism and the spectra at ${\theta }_1={30}^{\circ }$, ${\theta }_2={\theta }_p$ were dominated by the two-step sequential decay mechanism $p+D\to p+d^{*}\to p+p+n$, where $d^{*}$ is a short-lived particle composed of a neutron and a proton in a ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ configuration. The Kuckes-Wilson-Cooper form of the spectator-model calculation gives a good qualitative fit to the knockout data. A least-squares fit of three forms of the density-of-states function to the $E_p=11\mathrm{}$ MeV, ${\theta }_1={30}^{\circ }$, ${\theta }_p={77}^{\circ }$ data gave the best result with the renormalized density-of-states function. Including the statistically most significant, independently measured spectra at bombarding energies of 9, 11, 12, and 13 MeV, a neutron-proton singlet scattering length of -23.9±0.8 fm is obtained.