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Electromagnetic decay of the 1.7- and 2.43-MeV levels in ^9Be
[摘要]

The 1.7- and 2.43-MeV levels in 9Be were populated with the reaction 11B(d, α)9Be* by bombarding thin boron on carbon foils with 1.7-MeV deuterons.The alpha particles were analyzed in energy with a surface-barrier counter set at the unique kinematically determined angle and the recoiling 9Be nuclei at 90o were analyzed 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 analyzer.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 Γrad/Γ.Analysis of 384 observed events gives Γrad/Γ = (1.16 ± 0.14) X 10-4 for the 2.43-MeV level.Combining this ratio with the value of Γrad = 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, Γrad/Γ ≤ 2.4 = 10-5, was determined.

[发布日期]  [发布机构] University:California Institute of Technology;Department:Physics, Mathematics and Astronomy
[效力级别]  [学科分类] 
[关键词] Physics [时效性] 
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