Radiative Transitions in Pb 207 and Pb <mml:…
1967; American Institute of Physics; Volume: 154; Issue: 4 Linguagem: Inglês
10.1103/physrev.154.1136
ISSN1536-6065
AutoresJ. A. Biggerstaff, J.R. Bird, John H. Gibbons, W. M. Good,
Tópico(s)Radioactive Decay and Measurement Techniques
ResumoMeasurements were made of the spectra of gamma rays that are emitted when neutrons of various energies below 100 keV are captured in $^{206}\mathrm{Pb}$ and $^{207}\mathrm{Pb}$. Capture resonances were observed, and gamma-ray de-excitation takes place primarily to the ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$, ${\frac{5}{2}}^{\ensuremath{-}}$, and ${\frac{3}{2}}^{\ensuremath{-}}$ levels in $^{207}\mathrm{Pb}$, and to the ${0}^{+}$ and ${3}^{\ensuremath{-}}$ levels in $^{208}\mathrm{Pb}$. A few other weaker transitions are seen in $^{207}\mathrm{Pb}$ to unidentified levels. It is possible to make plausible spin and parity assignments to the resonant states by combining these results with earlier measurements of total and capture cross sections. The measurements collectively indicate a predominance of negative-parity capturing states in $^{207}\mathrm{Pb}$ and positive-parity capturing states in $^{208}\mathrm{Pb}$. The positive-parity resonances in $^{208}\mathrm{Pb}$ decay predominantly through the ${3}^{\ensuremath{-}}$state at 2.61 MeV, and the ${1}^{\ensuremath{-}}$neutron resonance capture decays directly to ground.
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