Observation of the proton emitter $${}_{\,57}^{116}$$La59

Abstract The quantum tunneling and emission of a single constituent nucleon provide beautifully simple unique window into the complex properties atomic nuclei at extreme edge nuclear existence. In particular, for odd-odd proton emitting nuclides, associated decay energy partial half-life can be used to probe correlations between valence neutrons protons which have been theoretically predicted favour new type superfluidity, isoscalar neutron-proton pairing, experimental “smoking gun" remains elusive. present work, from lanthanum isotope $${}_{\,57}^{116}$$ 57 116 La 59 , 23 away only stable $${}_{\,57}^{139}$$ 139 82 is reported. 116 were synthesised in fusion-evaporation reaction 58 Ni( 64 Zn, p 5 n ) identified via their radioactivity using mass spectrometer MARA (Mass Analysing Recoil Apparatus) silicon detectors placed its focal plane. Comparisons measured ( E = 718 ± 9 keV) T 1/2 50 22 ms) with values calculated Universal Decay Law approach indicate that emitted an orbital angular momentum l 2 probability enhanced relative closest, less exotic, odd-even $${}_{\,57}^{117}$$ 117 60 while proton-emission Q -value lower. We propose this possible signature presence strong pair neutron deficient system. observations γ decays isomeric states 117 are also