The Hartree-Fock-Bogoliubov (HFB) equations with generalized isospin pairing are numerically solved without any approximations, except imposing certain self-consistent symmetries. Realistic forces are used to make definite conclusions concerning the shapes of nuclei and the existence of isospin pairing. Comparison with previous approximations shows that in the s-d shell the HFB equations may not be quantitatively approximated by HF+ BCS, HB -BCS, or by iterating between HF and BCS. Isospin pairing offers an explanation for axial symmetry in Mg and 'S and for the existence of low-lying vibrational states in Ar.

Resonance fluorescence has been used for measuring the widths of over 42 levels in Ar below 11 MeV by employing Ge(Li) detectors and bremsstrahlung beams with end point energies of 8.5, 10.3, and 11. 8 MeV. The gI 0/I of these levels were measured, and several J =1 levels were identified.A strong photon strength was found, extending between 8 and 11 MeV which complements a bump observed between 10.4 and 12.4 MeV using the (y,n) reaction. This behavior is theoretically explained using the open-shell-linear-response method.

The Hartree-Fock-Bogoliubov (HFB) equations are solved for the N=Z even-even nuclei in the s-d shell. The possibility of generalized pairing correlations (e.g. both T=Q and T=l pairing) is studied in detail. It is found that the two kinds of pairing are mutually exclusive and that the lowest HFB solution for the even-even N^Z nuclei has T=0 independent pairs. The validity and the extent of these correlations is further examined by projecting the solutions onto eigenstates of the total number operator. These T=0 pairing correlations occur for the axially symmetric prolate Mg 24 , oblate S 32 , and prolate Ar 36 HFB solutions. In studying the relevance of these HFB solutions to the experimental spectra, it is found that the HFB field gives a more consistent description of the structure of N-Z even-even nuclei and that it can resolve the discrepancies and also the failures of the HF field in the upper half of the s-d shell.