Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unexpectedly large charge radii of neutron-rich calcium isotopes   Despite being a complex many-body system, the atomic nucleus exhibits simple
structures for certain "magic" numbers of protons and neutrons. The calcium
chain in particular is both unique and puzzling: evidence of doubly-magic
features are known in 40,48Ca, and recently suggested in two radioactive
isotopes, 52,54Ca. Although many properties of experimentally known Ca isotopes
have been successfully described by nuclear theory, it is still a challenge to
predict their charge radii evolution. Here we present the first measurements of
the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at
ISOLDE, CERN. The experimental results are complemented by state-of-the-art
theoretical calculations. The large and unexpected increase of the size of the
neutron-rich calcium isotopes beyond N = 28 challenges the doubly-magic nature
of 52Ca and opens new intriguing questions on the evolution of nuclear sizes
away from stability, which are of importance for our understanding of
neutron-rich atomic nuclei.

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The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: astro-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: math
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The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: gr-qc