Proton Spectra from thep+D Reaction for 5-10 MeV Incident Protons

The proton spectra from the $p+\mathrm{D}\to 2p+n$ reaction have been measured at the four laboratory energies, 10.62, 9.19, 6.97, and 5.53 MeV, and at the two laboratory angles, 14° and 34°. The proton beam from the University of Illinois cyclotron was used to bombard a deuterated polyethylene target. The breakup protons were recorded by a thin CsI scintillation counter used in conjunction with a magnetic spectrometer. The energy resolution of the system was approximately one percent and the minimum energy for which reliable data could be obtained was 1 MeV. All of the spectra have fewer low-energy protons than would be predicted by phase-space arguments alone. They all exhibit rather steep slopes near the maximum breakup energy, reaching one-third to one-half maximum height in less than ¼ MeV. The slope then decreases, the cross section rising to a maximum near $\frac{E}{E_{max}}=\frac{1}{2}$. Structure, in the form of a "knee" in the spectrum, has been observed near the maximum breakup energy for all the spectra with incident proton energies greater than 7 MeV. This structure becomes more pronounced as the scattering angle increases and less pronounced as the incident energy decreases. Similar structure has also been observed near the low-energy end of the spectrum for the 10.6-MeV incident proton energy. The present observations have been compared with the less complete work of other investigators, and the agreement was found to be excellent. A qualitative understanding of the observed structure is provided by the final-state interaction formalism of Watson. A comparison with the impulse approximation theory of Frank and Gammel has also been made and the agreement is rather poor.