Spectrum Shape of K -Orbital Shakeoff Electrons and Accompanying Nuclear Beta Particles in the Decay of Pr 143
1971; American Institute of Physics; Volume: 3; Issue: 1 Linguagem: Inglês
10.1103/physrevc.3.265
ISSN1538-4497
AutoresH. J. Fischbeck, F. Wágner, F. T. Porter, M. S. Freedman,
Tópico(s)Atomic and Molecular Physics
ResumoThe composite ($K$-orbital shakeoff plus nuclear) electron spectrum shape in coincidence with $K$ x rays in the pure $\ensuremath{\beta}$ emitter ${\mathrm{Pr}}^{143}$ (${E}_{0}=930$ keV) was measured with the Argonne magnetic-lens spectrometer and a NaI scintillation x-ray spectrometer. It yields an ordinary Kurie plot nearly linear from ${E}_{max}=888\ifmmode\pm\else\textpm\fi{}5$ keV [930 keV --- ($K$ binding energy)] to \ensuremath{\sim}160 keV, below which the contribution from the $K$ shakeoff spectrum appears as a sharply rising component down to 30 keV. This composite coincidence spectrum agrees fairly well with the recent relativistic shakeoff theory of Stephas and Crasemann, but only if their formulation for the square of the atomic matrix element is multiplied by a factor of $\frac{W}{p}$. Significant differences of both component shapes with this modified theory remain. Comparison of the measured shape to that calculated from the formulation of Feinberg for direct collision indicates that this process contributes negligibly to the decay. The ratio of the higher-energy Kurie component (mainly the nuclear $\ensuremath{\beta}$ component) of the composite spectrum to the singles intensity gives a total $K$-ionization probability ${P}_{K}=(2.95\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$; relativistic self-consistent-field wave-function overlap integrals give 3.0\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$.
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