Document Detail

Discovery of 40Mg and 42Al suggests neutron drip-line slant towards heavier isotopes.
MedLine Citation:
PMID:  17960237     Owner:  NLM     Status:  PubMed-not-MEDLINE    
A fundamental question in nuclear physics is what combinations of neutrons and protons can make up a nucleus. Many hundreds of exotic neutron-rich isotopes have never been observed; the limit of how many neutrons a given number of protons can bind is unknown for all but the lightest elements, owing to the delicate interplay between single particle and collective quantum effects in the nucleus. This limit, known as the neutron drip line, provides a benchmark for models of the atomic nucleus. Here we report a significant advance in the determination of this limit: the discovery of two new neutron-rich isotopes--40Mg and 42Al--that are predicted to be drip-line nuclei. In the past, several attempts to observe 40Mg were unsuccessful; moreover, the observation of 42Al provides an experimental indication that the neutron drip line may be located further towards heavier isotopes in this mass region than is currently believed. In stable nuclei, attractive pairing forces enhance the stability of isotopes with even numbers of protons and neutrons. In contrast, the present work shows that nuclei at the drip line gain stability from an unpaired proton, which narrows the shell gaps and provides the opportunity to bind many more neutrons.
T Baumann; A M Amthor; D Bazin; B A Brown; C M Folden; A Gade; T N Ginter; M Hausmann; M Matos; D J Morrissey; M Portillo; A Schiller; B M Sherrill; A Stolz; O B Tarasov; M Thoennessen
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Nature     Volume:  449     ISSN:  1476-4687     ISO Abbreviation:  Nature     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-10-25     Completed Date:  2007-11-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  1022-4     Citation Subset:  -    
National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.
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Comment In:
Nature. 2007 Oct 25;449(7165):992-3   [PMID:  17960227 ]

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