New isotopes of emanation 223Em and 224Em

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Abstract

Two new isotopes of emanation have been identified among the spallation products of thorium: their mass numbers and half lives have been determined by milking the radium descendants, 223Ra and 224Ra. The values obtained were: 223Em, 43 ± 5 min, 224Em, 114 ± 6 min.

223Em has also been made by the reaction 222Em(n,γ)223Em, and the half-life determined by the milking technique.

The cross-sections for production of 223Em and 224Em in the 340 MeV proton bombardment of thorium have been measured, and these have been used, together with other measured cross-sections, to construct a charge distribution curve for spallation products in this mass region. The curve is compared with those obtained at lower mass numbers.

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    Citation Excerpt :

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  • Nuclear data sheets for A = 224

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