The differential cross sections for the reactions 9 Be(10 B, 10 B) 9 Be and 9 Be(10 B, 9 Be) 10 B have been measured at an incident energy of 100 MeV. The elastic scattering data have been used to determine the optical model parameters for the 9 Beϩ 10 B system at this energy. These parameters are then used in distorted-wave Born approximation ͑DWBA͒ calculations to predict the cross sections of the 9 Be(10 B, 9 Be) 10 B proton exchange reaction, populating the ground and low-lying states in 10 B. By normalizing the theoretical DWBA proton exchange cross sections to the experimental ones, the asymptotic normalization coefficients ͑ANC's͒, defining the normalization of the tail of the 10 B bound state wave functions in the two-particle channel 9 Beϩp, have been found. The ANC for the virtual decay 10 B(g.s.)→ 9 Beϩp will be used in an analysis of the 10 B(7 Be, 8 B) 9 Be reaction to extract the ANC's for 8 B→ 7 Beϩp. These ANC's determine the normalization of the 7 Be(p,␥) 8 B radiative capture cross section at very low energies, which is crucially important for nuclear astrophysics. ͓S0556-2813͑97͒02109-2͔

The level scheme of 57 Cu is investigated via the 1 H( 58 Ni, 57 Cu-␥)2n reaction by using the recoil mass spectrometer MARS at the Texas A&M Cyclotron Institute. Three low-lying excited states are observed in 57 Cu at 1028 Ϯ 4, 1106 Ϯ 4, and 2398 Ϯ 10 keV. The results are compared with well known excited states of the mirror nucleus 57 Ni. The measured excited states of 57 Cu allow recalculation of the astrophysical reaction rate for the stellar radiative proton capture reaction 56 Ni(p,␥) 57 Cu.

The structure of the low-lying levels in the mirror nuclei 57 Ni and 57 Cu is described within the extended unified model. The problem of single-particle energies in 56 Ni is treated in detail. ''Bare'' single-particle energies are extracted from existing experimental data for the energy levels in 57 Ni and 57 Cu by carefully considering the influence of the coupling to excitations of the core. Important contributions arise, influencing especially the results on the spin-orbit splitting. The differences between the Coulomb energy shifts of various orbitals in 56 Ni are discussed and compared with those resulting from Hartree-Fock calculations carried out using a broad range of Skyrme interactions. The parameters of the Woods-Saxon potential reproducing these neutron ''bare'' single-particle energies and the charge root-mean-square radius of 56 Ni are extracted. It is demonstrated that the contributions associated with the Thomas-Ehrman effect and the electromagnetic spinorbit interaction are important and large enough to account for the differences between the Coulomb energy shifts of the single-particle levels in 56 Ni. ͓S0556-2813͑96͒03711-9͔

Absolute branching ratios for the ␤ decay of 57 Cu to excited states up to 3.3 MeV in 57 Ni have been determined, including the l-forbidden Gamow-Teller transition to the first excited state in 57 Ni. Four transitions to excited states at 0.768, 1.113, 2.443, and 3.007 MeV are observed in addition to the superallowed decay to the ground state of 57 Ni. The measured branching ratio to the ground state is 89.9 Ϯ 0.8% and the branching ratios to the four excited states are 0.94 Ϯ 0.09%, 8.6 Ϯ 0.6%, 0.17 Ϯ 0.03%, and 0.35 Ϯ 0.04%, respectively. In addition we have measured the 57 Cu half-life and find it to be 196.3 Ϯ 0.7 ms, which is in good agreement with the most recent measurement. B͑GT͒ values have been extracted from the new results and are compared to shell model calculations.

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