Lower Excited States in P29 from the Si28(p, γ)P29 Reaction

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The gamma-rays from the Si28(p, γ)P29 reaction at the Ep=369 kev resonance were studied with a large NaI(Tl) crystal scintillation spectrometer. The resonance state, corresponding to the 3.116±0.012 Mev fourth excited state in P29, was found to decay by (74±4)% to the first excited state at 1.384±0.008 Mev and by (26±4)% to the second excited state at 1.961±0.013 Mev which decays predominantly to the ground state. From the angular distribution measurements of each gamma-ray line, spins and parities of these lower levels in P29 were unambiguously assigned as follows: 1.38 Mev(1st), J=3⁄2+; 1.96 Mev(2nd), J=5⁄2+; 3.12 Mev(4th), J=5⁄2+. These assignments are all consistent with the known character of the corresponding levels in the mirror nucleus Si29, and are also in agreement with the theoretical predictions. From the precise gamma-ray energy measurements, the Q-value of this reaction was estimated as 2.760±0.013 Mev, which is by about 36 kev larger than the published value based on the β-ray end-point energy measurement. The resonance strength (2J+1)ΓpΓγ⁄(Γp+Γγ) was found to be (4.7±0.8)×10−3 ev.
社団法人日本物理学会の論文