Octupole correlations in light neutron-rich $^{143, 144}$La

Intensive investigations have shown strong evidence of octupole deformations and/or correlations in $^{142-148}$Ba, $^{144,146}$Cs and $^{145,147}$La. In the present work the high-spin level scheme of light neutron-rich $^{143}$La is expanded and that of $^{144}$La is proposed for the first time by measuring prompt gamma rays from the spontaneous fission of $^{252}$Cf at Gammasphere. B(E1)/B(E2) ratios, energy displacement $\delta $E(I) and the rotational frequency ratios $\omega ^{-}$(I)/$\omega ^{+}$(I) of the new parity-doublets of $^{143,144}$La indicate that octupole correlations also develop in these light neutron-rich La isotopes. Based on CSM calculations the band-crossings observed in a rotational frequency range of 0.31 to 0.34 MeV for the two even-parity bands in $^{143}$La are interpreted as due to alignment of a pair of $i_{13/2}$ neutrons in the nucleus.