Investigating the Structure of Deformed, Neutron-Rich, Odd-Odd Nuclei in the

The A ≈ 100 mass region is a cornerstone of contemporary nuclear structure research, defined by a dramatic structural phase transition from spherical to strongly prolate-deformed shapes (β2 ≈ 0.4) that occurs sharply between neutron numbers N = 58 and N = 60. Investigating the odd-odd nuclei in this area, specifically the Nb (Z = 41) and Tc (Z = 43) isotopic chains, is particularly complex due to the demanding requirement of correctly modeling the proton-neutron (p-n) residual interaction and coupling. A historical deficiency of reliable experimental data, coupled with Jπ assignments often based purely on theoretical models, has led to inconsistencies in the literature. To address this, we conducted specialized y-ray and y-conversion electron coincidence spectroscopy experiments utilizing the LOHENGRIN recoil mass spectrometer at the Institut Laue-Langevin. This technique is designed to determine transition multipolarities via internal conversion coefficients, providing the necessary experimental foundation for unambiguous Jπ assignments. Our systematic study, targeting 100Nb, 102Tc, and 104Nb, is aimed at challenging current theoretical understanding of deformation and p-n coupling far from stability. Preliminary analysis of 104Tc data from the initial campaign reveals new candidate y-ray transitions, confirming the need for fundamental revisions to the existing level schemes.