Magic Nature of Neutrons in ^sup 54^Ca: First Mass Measurements of ^sup 55–57^Ca

We perform the first direct mass measurements of neutron-rich calcium isotopes beyond neutron number 34 at the RIKEN Radioactive Isotope Beam Factory by using the time-of-flight magnetic-rigidity technique. The atomic mass excesses of 55–57Ca are determined for the first time to be −18650(160), −135...

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Veröffentlicht in:Physical review letters 2018-07, Vol.121 (2), p.022506
1. Verfasser: Michimasa, S
Format: Artikel
Sprache:eng
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Zusammenfassung:We perform the first direct mass measurements of neutron-rich calcium isotopes beyond neutron number 34 at the RIKEN Radioactive Isotope Beam Factory by using the time-of-flight magnetic-rigidity technique. The atomic mass excesses of 55–57Ca are determined for the first time to be −18650(160), −13510(250), and −7370(990) keV, respectively. We examine the emergence of neutron magicity at N = 34 based on the new atomic masses. The new masses provide experimental evidence for the appearance of a sizable energy gap between the neutron 2p1/2 and 1f5/2 orbitals in 54 Ca , comparable to the gap between the neutron 2p3/2 and 2p1/2 orbitals in 52Ca. For the 56Ca nucleus, an open-shell property in neutrons is suggested.
ISSN:0031-9007
1079-7114