Eur. Phys. J. A (2004) 21: 75-77
https://doi.org/10.1140/epja/i2003-10190-3

First decay study of the new isotope ¹²⁹Pm near the proton drip line

¹ Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, PRC
² Department of Technical Physics and MOE Key Laboratory, Peking University, 10087, Beijing, PRC

^* e-mail: xsw@ns.lzb.ac.cn

Abstract

The very neutron-deficient nuclide ¹²⁹Pm was produced via the ⁹²Mo(⁴⁰Ca, p2n) reaction and identified for the first time by using the X- coincidence in combination with a He jet tape transport system. According to the decay curve of a 99 keV -ray which corresponds to the known transition in the daughter nucleus ¹²⁹Nd of the ¹²⁹Pm decay, the half-life of ¹²⁹Pm was determined to be 2.4(9) s. Based on the nuclear potential energy surface (PES) calculations, the ground-state spin-parity of ¹²⁹Pm was predicted as 5/2^- which is favorable to feed a 5/2^- low-lying state in the daughter nucleus ¹²⁹Nd via the (EC ) decay.