Masses of exotic calcium isotopes pin down nuclear forces
Masses of exotic calcium isotopes pin down nuclear forces
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DOI：
10.1038/nature12226
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发表时间：
2013-06
期刊：
影响因子：
64.8
通讯作者：
F. Wienholtz;D. Beck;K. Blaum;Ch. Borgmann;M. Breitenfeldt;R. Cakirli;R. Cakirli;S. George;F. Her
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文献类型：
--
作者：
F. Wienholtz;D. Beck;K. Blaum;Ch. Borgmann;M. Breitenfeldt;R. Cakirli;R. Cakirli;S. George;F. Her
即将存在的奇异核的性质在我们理解核相互作用中起着重要作用。超丰中子核对核力的新方面变得敏感。钙的双魔同位素40 Ca和48 Ca是一个理想的测试核壳演化，从稳定的山谷到存在的极限。由于有一个封闭的质子壳层，钙同位素标志着手征有效场论中三核子力计算的前沿。尽管对51 Ca和52 Ca质量的预测已经通过直接测量得到了验证，但对于较重的钙同位素，核质量如何演变仍是一个悬而未决的问题。本文报道了用欧洲核子研究中心的ISOLTRAP多反射飞行时间质谱仪对外来钙同位素~（53）Ca和~（54）Ca的质量测定。测得的质量明确地建立了一个突出的壳层封闭在中子numberN= 32，在极好的协议与我们的理论计算。这些结果增加了我们对富中子物质的理解，并确定了处于量子色动力学理论发展前沿的核力的微妙组成部分。
The properties of exotic nuclei on the verge of existence play a fundamental part in our understanding of nuclear interactions. Exceedingly neutron-rich nuclei become sensitive to new aspects of nuclear forces. Calcium, with its doubly magic isotopes40Ca and48Ca, is an ideal test for nuclear shell evolution, from the valley of stability to the limits of existence. With a closed proton shell, the calcium isotopes mark the frontier for calculations with three-nucleon forces from chiral effective field theory,,,. Whereas predictions for the masses of51Ca and52Ca have been validated by direct measurements, it is an open question as to how nuclear masses evolve for heavier calcium isotopes. Here we report the mass determination of the exotic calcium isotopes53Ca and54Ca, using the multi-reflection time-of-flight mass spectrometer of ISOLTRAP at CERN. The measured masses unambiguously establish a prominent shell closure at neutron numberN= 32, in excellent agreement with our theoretical calculations. These results increase our understanding of neutron-rich matter and pin down the subtle components of nuclear forces that are at the forefront of theoretical developments constrained by quantum chromodynamics.