Evidence for enhanced neutron-proton correlations from the level structure of the N = Z+1 nucleus 8743Tc44

The low-lying excited states in the neutron-deficient N = Z + 1 nucleus (87)(43)Tcc(44) have been studied via the fusion-evaporation reaction Fe-54(Ar-36, 2n1p)Tc-87 at the Grand Accelerateur National d'Ions Lourds (GANIL), France. The AGATA spectrometer was used in conjunction with the auxiliary NEDA, Neutron Wall, and DIAMANT detector arrays to measure coincident prompt gamma rays, neutrons, and charged particles emitted in the reaction. A level scheme of Tc-87 from the (9/2(g.s.)(+)) state to the (33/2(1)(+)) state was established based on six mutually coincident gamma-ray transitions. The constructed level structure exhibits a rotational behavior with a sharp backbending at (h) over bar omega approximate to 0.50 MeV. A decrease in alignment frequency and increase in alignment sharpness in the odd-mass isotonic chains around N = 44 is proposed as an effect of the enhanced isoscalar neutron-proton interactions in odd-mass nuclei when approaching the N = Z line.

Automated summary

In this study, low-lying excited states in the neutron-deficient N = Z + 1 nucleus Tc-87 were investigated using the fusion-evaporation reaction. A level scheme was established, showing a rotational behavior with a sharp backbending. The study suggests a decrease in alignment frequency and an increase in alignment sharpness in the odd-mass isotonic chains around N = 44 due to enhanced isoscalar neutron-proton interactions in odd-mass nuclei near the N = Z line.