New Isotope 220Np: Probing the Robustness of the N =126 Shell Closure in Neptunium
Abstract
A new short-lived neutron-deficient isotope 220Np was synthesized in the fusion-evaporation reaction 185Re (40Ar,5 n )220Np at the gas-filled recoil separator SHANS. Based on the measurement of the correlated α -decay chains, the decay properties of 220Np with Eα=10 040 (18 ) keV and T1 /2=2 5-7+14 μ s were determined, which are in good agreement with theoretical predictions. From the new experimental results coupled with the recently reported α -decay data of Np,223219 , 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.
- Publication:
-
Physical Review Letters
- Pub Date:
- May 2019
- DOI:
- 10.1103/PhysRevLett.122.192503
- Bibcode:
- 2019PhRvL.122s2503Z