Discovery of the α-emitting isotope 210Pa

Abstract

Synthesizing isotopes located far away from the line of β-stability is the core research topic in nuclear physics. However, it remains a challenge due to their tiny production cross sections and short half-lives. Here, we report on the observation of a very neutron-deficient isotope ²¹⁰Pa produced via the fusion-evaporation reaction ¹⁷⁵Lu(⁴⁰Ca, 5n)²¹⁰Pa at a newly constructed China Accelerator Facility for Superheavy Elements. The measured α-particle energy of E_α = 8284(15) keV and half-life of \({T}_{1/2}=6.{0}_{-1.1}^{+1.5}\) ms of ²¹⁰Pa allow us to extend the α-decay systematics and test the predictive power of theoretical models for heavy nuclei near the proton drip line. Based on its unhindered α-decay character, the spin and parity of ²¹⁰Pa is proposed to be (3⁺), supported by the large-scale shell model and cranked shell model calculations. This isotope is discovered with substantial statics within ∼ 3 days using intensive 2 pμA beam, demonstrating the tremendous capability of the facility for the study of heavy and superheavy nuclei.