Study of the first excited 1/2⁺ state in ¹³¹La

Low-spin states of La-131 have been reinvestigated via the In-115 + Ne-20 reaction at 95 MeV with a pulsed beam and gamma-ray spectroscopy. A doublet of excited states, 1/2(+) at 230.3 keV and 7/2(+) at 231.2 keV, has been definitely established in La-131. Low-spin state systematics in Z=57 and N=74 isotopes are presented and discussed.