Alpha decay properties of the semi-magic nucleus 219Np

Abstract

The semi-magic nucleus Np-219 was produced in the fusion reaction Re-187(Ar-36, 4n)Np-219 at the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure). A fast electronics system based on waveform digitizers was used in the data acquisition and the sampled pulses were processed by digital algorithms. The reaction products were identified using spatial and time correlations between the implants and subsequent alpha decays. According to the observed alpha-decay chain, an energy of E-alpha = 9039(40) keV and a half-life of T-1/2 = 0.15(-0.07)(+0.72) ms were determined for Np-219. The deduced proton binding energy of Np-219 fits well into the systematics, which gives another evidence of that there is no sub-shell closure at Z = 92. The influence of the N = 126 shell closure on the stability of Np isotopes is discussed within the framework of alpha-decay reduced widths. (c) 2017 The Author(s). Published by Elsevier B.V.