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arXiv 1111.1359nucl-ex
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丰中子K和Ca同位素的Penning阱质量测量:N = 28壳层强度的恢复

Penning-Trap Mass Measurements of the Neutron-Rich K and Ca Isotopes: Resurgence of the N = 28 Shell Strength

A. Lapierre, M. Brodeur, T. Brunner, S. Ettenauer, P. Finlay, A. T. Gallant, V. V. Simon, P. Delheij, D. Lunney, R. Ringle, H. Savajols, J. Dilling

摘要:

本文介绍了在TRIUMF-ISAC的TITAN装置上进行的丰中子44,47 - 50K和49,50Ca同位素的潘宁阱质量测量。利用TITAN EBIT用电荷增殖4+离子进行44K质量测量,并且与文献一致。47 K和49,50 Ca的质量过剩更精确,与2003年原子质量评估(AME '03)中公布的值一致。48、49、50K的质量超出比AME '03值精确一个数量级以上。对于48,49K,我们发现分别有7 sigma和10 sigma的偏差。与从AME '03质量过剩值计算的分离能相比,新的49K质量过剩显著降低了中子数N = 30处的两中子分离能,并且因此使Z = 19处的N = 28中子-壳层带隙能增加了约1 MeV。

英文摘要:

We present Penning-trap mass measurements of neutron-rich 44,47-50K and 49,50Ca isotopes carried out at the TITAN facility at TRIUMF-ISAC. The 44K mass measurement was performed with a charge-bred 4+ ion utilizing the TITAN EBIT, and agrees with the literature. The mass excesses obtained for 47K and 49,50Ca are more precise and agree with the values published in the 2003 Atomic Mass Evaluation (AME'03). The 48,49,50K mass excesses are more precise than the AME'03 values by more than one order of magnitude. For 48,49K, we find deviations by 7 sigma and 10 sigma, respectively. The new 49K mass excess lowers significantly the two-neutron separation energy at the neutron number N=30 compared with the separation energy calculated from the AME'03 mass-excess values, and thus, increases the N=28 neutron-shell gap energy at Z=19 by approximately 1 MeV.

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