Resonant Absorption of Gamma Radiation from theSi30(p, γ)P31Reaction

Abstract

The technique of collision-produced Doppler shift has been used to induce resonant absorption. The gamma rays emitted by excited ${\mathrm{P}}^{31}$ from the ${\mathrm{Si}}^{30}(p, \gamma ){\mathrm{P}}^{31}$ reaction at $E_p=622\mathrm{}$ kev have been selectively absorbed in phosphorus. Resonant absorption of the 7.90-Mev gamma rays emitted from this level occurs at 76.6 degrees with respect to the proton beam direction. Since the experimental absorption curve is broader than the previously measured instrumental resolution curve, it has been possible to determine directly the total width of the resonance level as 40±7 ev. From the absorption integral, together with this value of the total width, the radiation width for transitions to the ground state is found to be 1.52±0.12 ev. A ${\mathrm{½}}^{+}$ spin assignment is made on the basis of the partial widths thus obtained.