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Enhanced neutron-proton (np) pairing correlations can arise when both particle types occupy the same orbitals. In addition to the T = 1 np pairing phase, the opportunity for isoscalar (T = 0) correlations is also present, especially on the N=Z line. Competition between these np-pairing mechanisms is of much interest. Recent work on $^{92}$Pd [1] has indicated the possibility for the existence of a new type of spin-aligned isoscalar np pair. The observation of the β-decaying 16$^+$ isomer in $^{96}$Cd has also revealed evidence for the importance of the T = 0 np interaction at higher spins [2]. Very recently, the gamma rays in the ground state sequence of $^{96}$Cd have been observed [3], following decay of the spin-trap isomer, although the ordering of the transitions could not be confirmed. Calculations suggest that spin-aligned pair approximation should contribute significantly to the structure of the states in the sequence, but varying with spins, and may reduce significantly for the 8$^+$ state [e.g. 4].
To gain further insight into the np-pairing effects, we propose here to use the knockout methodology to populate states in the N=Z systems $^{96}$Cd and $^{92}$Pd up to 8$^+$ through (probably 1-neutron) knockout. The aim will be to firmly establish the ordering of the transitions in both nuclei and also to investigate the extent to which the knockout cross-sections might be affected by changes in the underlying structure along the yrast line.
[1] B. Cederwall, F. G. Moradi, T. Bäck, A. Johnson, J. Blomqvist, E. Clement, G. de France, R. Wadsworth, K. Andgren, K. Lagergren et al., Nature 469, 68 (2011).
[2] P. J. Davies, H. Grawe, K. Moschner, A. Blazhev, R. Wadsworth, P. Boutachkov, F. Ameil, A. Yagi, H. Baba, T. Bäck et al., Phys. Lett. B 767, 474 (2017).
[3] P. J. Davies et al. Phys. Rev C 99, 021302(R) (2019)
[4] G. J. Fu, J. J. Shen, Y. M. Zhao and A. Arima. Phys. Rev C 87, 044312 (2013)
[5] Z. X. Xu, C. Qi, J. Blomqvist, R. J. Liotta and R. Wyss. Nucl. Phys. A 877 (2012) 51
