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The Rare Isotope Science Project in Korea has developed a high current heavy ion accelerator using superconducting linacs. A normal conducting injector system was proposed to supply heavy ions to the superconducting driver linac. A beam physics and engineering design study was performed, and the beam dynamics of the injector was simulated. Optimized beam transmission and emittance were obtained from the beam dynamics simulation. Various normal conducting bunchers, such as multi-harmonic buncher, velocity equalizer, radiofrequency quadrupole, and re-bunchers, will be used and have been electromagnetically calculated.

We report the identification of metastable isomeric states of $$^{228}$$ 228 Ac at 6.28 keV, 6.67 keV and 20.19 keV, with lifetimes of an order of 100 ns. These states are produced by the $$\beta $$ β -decay of $$^{228}$$ 228 Ra, a component of the $$^{232}$$ 232 Th decay chain, with $$\beta $$ β Q-values of 39.52 keV, 39.13 keV and 25.61 keV, respectively. Due to the low Q-value of $$^{228}$$ 228 Ra as well as the relative abundance of $$^{232}$$ 232 Th and their progeny in low background experiments, these observations potentially impact the low-energy background modeling of dark matter search experiments.