Mass measurements demonstrate a strong N=28 shell gap in argon.

نویسندگان

  • Z Meisel
  • S George
  • S Ahn
  • J Browne
  • D Bazin
  • B A Brown
  • J F Carpino
  • H Chung
  • R H Cyburt
  • A Estradé
  • M Famiano
  • A Gade
  • C Langer
  • M Matoš
  • W Mittig
  • F Montes
  • D J Morrissey
  • J Pereira
  • H Schatz
  • J Schatz
  • M Scott
  • D Shapira
  • K Smith
  • J Stevens
  • W Tan
  • O Tarasov
  • S Towers
  • K Wimmer
  • J R Winkelbauer
  • J Yurkon
  • R G T Zegers
چکیده

We present results from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. We report the first mass measurements of ^{48}Ar and ^{49}Ar and find atomic mass excesses of -22.28(31)  MeV and -17.8(1.1)  MeV, respectively. These masses provide strong evidence for the closed shell nature of neutron number N=28 in argon, which is therefore the lowest even-Z element exhibiting the N=28 closed shell. The resulting trend in binding-energy differences, which probes the strength of the N=28 shell, compares favorably with shell-model calculations in the sd-pf shell using SDPF-U and SDPF-MU Hamiltonians.

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عنوان ژورنال:
  • Physical review letters

دوره 114 2  شماره 

صفحات  -

تاریخ انتشار 2015