Compound Nucleus Effects in Deuteron Reactions:C13(d, α)B11andC13(d, t)C12

Abstract

Excitation functions for the ${\mathrm{C}}^{13}(d, \alpha ){\mathrm{B}}^{11}$ and ${\mathrm{C}}^{13}(d, t){\mathrm{C}}^{12}$ reactions have been measured at several laboratory angles in the range of deuteron energy from 1 to 3 Mev. Two prominent resonances were observed in the ($d, \alpha$) reaction at 1.80 Mev ($\Gamma =55\mathrm{}\pm 10$ kev) and at 2.20 Mev ($\Gamma =22\mathrm{}\pm 4$ kev). The latter resonance was observed at 14 angles of observation from 25° to 140°. The 1.80-Mev resonance was observed at 9 angles in the ($d, \alpha$) reaction and at 3 angles in the ($d, t$) reaction. The 2.20-Mev resonance was not found in the ($d, t$) reaction, but the $\alpha$-particle group leaving ${\mathrm{B}}^{11}$ in the first excited state was observed to be resonant at this energy. Both of the narrow resonances exhibit striking interference effects with the nonresonant background. An analysis of the interference effects at the 2.20-Mev resonance indicates that deuterons with 3 or 4 units of angular momentum are responsible for the formation of the corresponding ${\mathrm{N}}^{15}$ level. The differential cross section for the ($d, \alpha$) reaction was measured at 17 angles from 11.2° to 144.6° (c.m.) at $E_d=2.28\mathrm{}$ Mev. Terms at least as high as ${cos}^4\theta$ are necessary to fit the forward peak. This forward peaking in the ($d, \alpha$) reaction persists over the entire energy range studied in spite of the large number of resonances in this region. This behavior suggests that some of the approximations usually made in the theory of highly excited states of nuclei are not of general validity.