Signature of 0+ excited state and shape coexistence in 94Kr through 93Kr(d,p)94Kr reaction

A measurement of the excitation spectrum of ⁹⁴Kr via one-neutron transfer to the ground state of ⁹³Kr using the ⁹³Kr(d,p)⁹⁴Kr reaction at 8A MeV, observing the outgoing protons, performed with the IRIS facility at TRIUMF is reported. Two states in ⁹⁴Kr, at 1.50±0.14 MeV and 2.20±0.14 MeV, were observed. An adiabatic-wave approximation analysis of the differential cross sections leads us to identify the lower energy state as being populated with neutron transfer to the 3s1/2 orbital. This leads to the first observation of the lowest 0⁺ excited state in ⁹⁴Kr, hence signaling shape co-existence. Theoretical calculations performed within the in-medium similarity renormalization group framework are presented that also show the existence of a low-energy 0⁺ state, aligning qualitatively with the observation.