Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shell model calculation of the beta- and beta+ partial halflifes of 54Mn
  and other unique second forbidden beta decays   The nucleus 54Mn has been observed in cosmic rays. In astrophysical
environments it is fully stripped of its atomic electrons and its decay is
dominated by the beta- branch to the 54Fe ground state. Application of 54Mn
based chronometer to study the confinement of the iron group cosmic rays
requires knowledge of the corresponding halflife, but its measurement is
impossible at the present time. However, the branching ratio for the related
beta+ decay of 54Mn was determined recently. We use the shell model with only a
minimal truncation and calculate both beta+ and beta- decay rates of 54Mn. Good
agreement for the beta+ branch suggests that the calculated partial halflife of
the beta- decay, (4.94 \pm 0.06) x 10^5 years, should be reliable. However,
this halflife is noticeably shorter than the range 1-2 x 10^6 y indicated by
the fit based on the 54Mn abundance in cosmic rays. We also evaluate other
known unique second forbidden beta decays from the nuclear p and sd shells
(10Be, 22Na, and two decay branches of 26Al) and show that the shell model can
describe them with reasonable accuracy as well.

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The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
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The categories of this paper are: physics
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int