Spin transfer measurements in (p-vector, n-vector) reactions

The measurement of complete sets of spin transfer coefficients in nuclear transitions, induced via charge-exchange (p-vector, n-vector) reactions at intermediate energies, is a unique form of separating the spin-dependent and spin-independent contributions to the differential cross section. The two components of the spin-dependent contribution, the spin-longitudinal and spin-transverse components may equally be separated. This is extremely important in cases where the target nuclei has a non-integer ground state spin. In this study and as an example of the above, differential cross section and complete set of polarization transfer coefficients obtained in the 13C(p-vector, n-vector)13N reaction studied at angles between 0 deg and 33 deg and at 197 MeV incident proton energy are presented. Polarization transfer coefficients are used to obtain the fraction of the Gamow-Teller (GT) component in the mirror ground state transition, which is a combination of the spin-independent Fermi (F) and spin-dependent GT components. Data are also presented for the transition to the first excited state in 13N at 2.34 MeV. This is a (1/2)- → (1/2)+ transition and the cross section is an incoherent admixture of ΔJπ = 1- and ΔJπ = 0- components. The complete set of polarization transfer coefficients are used to obtain differential cross section data for both components. The empirical results are compared with Distorted Wave Impulse Approximation calculations, DWIA. (author)