Systematics on the low-lying spectra in N = 78 ~ 80 isotones

Combining the new spectroscopy results of ¹⁴⁴Tb and previous spectroscopy studies of neighboring nuclei, a systematic investigation on the low-lying spectra in N = 78 ~ 80 isotones is performed. Good systematics have been found for the coupling patterns which couple the odd nucleon(s), such as πh_11/2, νh^-1_11/2, πh _11/2², νh^-2_11/2, πh _11/2νh^-1_11/2, to the 2⁺, 4 ⁺, 6⁺ and 3^- core excitations. It is found that the relative excitation energies of the states formed by coupling h _11/2 proton(s) to the 2⁺, 4⁺ core excitations are pushed up, in contrast with those formed by coupling h_11/2 neutron hole(s) to the 2⁺, 4⁺ core excitations, which are pulled down. According to the systematics, the interpretation that the 17/2 ⁺ states observed in ¹⁴¹Sm and ¹⁴³Gd are the fully aligned member of coupling the odd h_11/2 neutron hole to the octupole 3^- core excitation, is explored to the isotones ¹⁴⁵Dy, ¹⁴²Eu, and ¹⁴⁴Tb.