Angular Distribution of the (d,p) Reactions Making Two Low States ofO17

Abstract

Angular distributions of the protons from deuteron bombardment of fairly thin oxide targets have been observed both for the long-range protons leading to the ground state of the residual nucleus ${\mathrm{O}}^{17}$, and for the short-range protons leading to the first excited state. The deuteron energies ranged from 0.65 to 3.05 Mev, and the beam, obtained at each energy from one of two statitrons, was practically monoenergetic. The protons were observed by an ionization chamber, linear amplifier, and pulse height discriminator, while the monitoring was done by integrating target current. The yield of the short-range protons is about ten times that of the long-range protons at low bombarding energies, and the two yields become nearly equal at higher energies. Very pronounced variation of proton intensity with angle was observed for both ranges at almost all bombarding energies, the shape of the curves varying markedly with energy. At low bombarding energies the long-range protons are predominantly forward, the short-range predominantly backward. In the neighborhood of a peak in the excitation curves at about 1.8 Mev, the angular distributions become roughly symmetric about 90° for both ranges, and even almost isotropic for the long-range protons. It happens that the high energy side of this peak coincides rather closely with the threshold of the competing ($d,n$) reaction. This peak appears for both ranges in the excitation curves for the total yield, integrated over all angles, but not in the conventional 90° excitation curves. Two further peaks appear at higher energies. It is hoped that relationships between the angular momentum properties of the two low states of the final nucleus may be deduced from detailed angular information of the sort here presented.