The shape of the T_z = +1 nucleus ⁹⁴Pd and the role of proton-neutron interactions on the structure of its excited states

Reduced transition probabilities have been extracted between excited, yrast states in the N = Z + 2 nucleus ⁹⁴Pd. The transitions of interest were observed following decays of the I^π = 14⁺ , E_x = 2129-keV isomeric state, which was populated following the projectile fragmentation of a ¹²⁴Xe primary beam at the GSI Helmholtzzentrum für Schwerionenforschung accelerator facility as part of FAIR Phase-0. Experimental information regarding the reduced E2 transition strengths for the decays of the yrast 8⁺ and 6⁺ states was determined following isomer-delayed E_γ1 − E_γ2 − △T_2,1 coincidence method, using the LaBr₃(Ce)-based FATIMA fast-timing coincidence gamma-ray array, which allowed direct determination of lifetimes of states in ⁹⁴Pd using the Generalized Centroid Difference (GCD) method. The experimental value for the half-life of the yrast 8⁺ state of 755(106) ps results in a reduced transition probability of B(E2:8⁺ →6⁺ ) = 205⁺³⁴ ₋₂₅ e²fm⁴ , which enables a precise verification of shell-model calculations for this unique system, lying directly between the N = Z line and the N = 50 neutron shell closure. The determined B(E2) value provides an insight into the purity of (g_9/2)ⁿ configurations in competition with admixtures from excitations between the (lower) N = 3 pf and (higher) N = 4 gds orbitals for the first time. The results indicate weak collectivity expected for near-zero quadrupole deformation and an increasing importance of the T = 0 proton-neutron interaction at N = 48.