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Short-Lived α-Emitting Isotope ^{222}Np and the Stability of the N=126 Magic Shell
L Ma1, Z Y Zhang1,2, Z G Gan1,2
1CAS Key Laboratory of High Precision Nuclear Spectroscopy, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Physical Review Letters
|August 4, 2020
Summary
Researchers discovered a new neutron-deficient isotope, Neptunium-222 (Np-222), using a fusion reaction. Its alpha decay properties were measured, confirming the N=126 shell effect in Neptunium isotopes.
Area of Science:
- Nuclear Physics
- Nuclear Chemistry
Background:
- Investigating neutron-deficient isotopes provides insights into nuclear structure and stability.
- The N=126 shell closure is a significant feature in nuclear physics, particularly for heavy elements.
Purpose of the Study:
- To synthesize and characterize a new neutron-deficient isotope, Neptunium-222 (Np-222).
- To experimentally determine the alpha decay properties of Np-222.
- To refine the understanding of alpha decay systematics for Neptunium isotopes and validate the N=126 shell effect.
Main Methods:
- Complete-fusion reaction: Re-187(Ar-40, 5n)Np-222.
- Observation using the gas-filled recoil separator SHANS.
- Identification via recoil-alpha correlation measurements.
Main Results:
- Successful production and identification of the new isotope Np-222.
- Establishment of six alpha-decay chains for Np-222.
- Experimental determination of Np-222 alpha decay energy (E_α = 10016(33) keV) and half-life (T_1/2 = 380 ns).
Conclusions:
- The new data for Np-222 enhance the alpha-decay systematics of Neptunium isotopes.
- The experimental results validate the predicted N=126 shell effect in Neptunium isotopes.
- The study contributes to understanding the evolution of nuclear shell closures in neutron-deficient nuclei.
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