Neutron-proton pairing competition in
nuclei; Metastable state decays in the proton dripline nuclei
Nb and
Tc
Garnsworthy, A. B.*; Regan, P. H.*; C
ceres, L.*; Pietri, S.*; Sun, Y.*; Rudolph, D.*; G
rska, M.*; Podoly
k, Z.*; Steer, S. J.*; Hoischen, R.*; Heinz, A.*; Becker, F.*; Bednarczyk, P.*; Doornenbal, P.*; Geissel, H.*; Gerl, J.*; Grawe, H.*; Gr
bosz, J.*; Kelic, A.*; Kojouharov, I.*; Kurz, N.*; Montes, F.*; Prokopowicz, W.*; Saito, Takehiko*; Schaffner, H.*; Tashenov, S.*; Werner-Malento, E.*; Wollersheim, H. J.*; Benzoni, G.*; Blank, B. B.*; Brandau, C.*; Bruce, A. M.*; Camera, F.*; Catford, W. N.*; Cullen, I. J.*; Dombr
di, Zs.*; Estevez, E.*; Gelletly, W.*; Ilie, G.*; Jolie, J.*; Jones, G. A.*; Jungclaus, A.*; Kmiecik, M.*; Kondev, F. G.*; Kurtukian-Nieto, T.*; Lalkovski, S.*; Liu, Z.*; Maj, A.*; Myalski, S.*; Pf
tzner, M.*; Schwertel, S.*; Shizuma, Toshiyuki; Simons, A. J.*; Walker, P. M.*; Wieland, O.*; Xu, F. R.*
The low-lying structures of the self-conjugate (
) nuclei
Nb and
Tc have been investigated using isomeric-decay spectroscopy following the projectile fragmentation of a
Ag beam. These represent the heaviest odd-odd
nuclei in which internal decays have been identified to date. The resulting level schemes shed light on the shape evolution along the
line between the doubly-magic systems
Ni and
Sn and support a preference for
states in
odd-odd nuclei at low excitation energies associated with a
neutron-proton pairing gap. Comparison with Projected Shell Model calculations suggests that the decay in
Nb may be interpreted as an isospin-changing
isomer.