New Isotope ^{220}Np: Probing the Robustness of the N=126 Shell Closure in Neptunium

Z Y Zhang; Z G Gan; H B Yang; L Ma; M H Huang; C L Yang; M M Zhang; Y L Tian; Y S Wang; M D Sun; H Y Lu; W Q Zhang; H B Zhou; X Wang; C G Wu; L M Duan; W X Huang; Z Liu; Z Z Ren; S G Zhou; X H Zhou; H S Xu; Yu S Tsyganov; A A Voinov; A N Polyakov

doi:10.1103/PhysRevLett.122.192503

New Isotope ^{220}Np: Probing the Robustness of the N=126 Shell Closure in Neptunium

Phys Rev Lett. 2019 May 17;122(19):192503. doi: 10.1103/PhysRevLett.122.192503.

Authors

Z Y Zhang^{1

2}, Z G Gan^{1

2}, H B Yang¹, L Ma¹, M H Huang^{1

2}, C L Yang^{1

2}, M M Zhang^{1

2}, Y L Tian^{1

2}, Y S Wang^{1

2

3}, M D Sun^{1

2

3}, H Y Lu^{1

2}, W Q Zhang^{1

2}, H B Zhou⁴, X Wang⁵, C G Wu⁵, L M Duan^{1

2}, W X Huang^{1

2}, Z Liu^{1

2}, Z Z Ren⁶, S G Zhou^{7

8}, X H Zhou^{1

2}, H S Xu^{1

2}, Yu S Tsyganov⁹, A A Voinov⁹, A N Polyakov⁹

Affiliations

¹ CAS Key Laboratory of High Precision Nuclear Spectroscopy, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
² School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China.
³ School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China.
⁴ Guangxi Key Laboratory of Nuclear Physics and Technology, Guangxi Normal University, Guilin 541004, China.
⁵ State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China.
⁶ School of Physics Science and Engineering, Tongji University, Shanghai 200092, China.
⁷ CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China.
⁸ Center of Theoretical Nuclear Physics, National Laboratory of Heavy-Ion Accelerator, Lanzhou 730000, China.
⁹ Joint Institute for Nuclear Research, RU-141980 Dubna, Russian Federation.

PMID: 31144958
DOI: 10.1103/PhysRevLett.122.192503

Abstract

A new short-lived neutron-deficient isotope ^{220}Np was synthesized in the fusion-evaporation reaction ^{185}Re(^{40}Ar,5n)^{220}Np at the gas-filled recoil separator SHANS. Based on the measurement of the correlated α-decay chains, the decay properties of ^{220}Np with E_{α}=10040(18) keV and T_{1/2}=25_{-7}^{+14} μs were determined, which are in good agreement with theoretical predictions. From the new experimental results coupled with the recently reported α-decay data of ^{219,223}Np, the α-decay systematics for Np isotopes around N=126 was established, which allows us for the first time to test the robustness of the N=126 shell closure in Z=93 Np isotopes. The results also indicate that, in the region of nuclei with Z≥83, the proton drip line has been reached for all odd-Z isotopes up to Np.