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Electromagnetic decay of the 1.7 and 2.43 MeV levels in9Be

Nuclear Physics
Publication Date
DOI: 10.1016/0029-5582(66)90109-x
  • Nuclear Reactions11B(D
  • αγ)
  • E= 1.70 Mev
  • MeasuredΓγ/ΓFor9Be Levels9Be
  • Levels Deduced Γ
  • Natural Target


Abstract The 1.7 and 2.43 MeV levels in 9Be were populated with the reaction 11 B( d, α) 9 Be ∗ by bombarding thin boron on carbon foils with 1.7 MeV deuterons. The alpha particles were analysed in energy with a surface-barrier counter set at the kinematically determined angle corresponding to recoiling 9Be nuclei at θ lab = 90°. The latter were analysed in rigidity with a magnetic spectrometer, in energy by a surface-barrier counter at the spectrometer focus and in velocity by the time delay between an alpha and a 9Be count. When a pulse from the spectrometer counter was in the appropriate delayed coincidence with a pulse from the alpha counter, the two pulses were recorded in a two-dimensional pulse-height analyser. Most of the 9Be ∗ decay by particle breakup. Only those that gamma decay are detected by the spectrometer counter. Thus the experiment provides a direct measurement of Γ rad/ Γ. Analysis of 384 observed events gives Γ rad/ Γ = (1.16±0.14) × 10 −4 for the 2.43 MeV level. Combining this ratio with the value of Γ rad = 0.122±0.015 eV found from inelastic electron scattering gives Γ = 1.05±0.18 keV. For the 1.7 MeV level, an upper limit Γ rad/ Γ ≦ 2.4×10 −5 was determined.

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