Spin Transfer Measurements in $(\vec{p},\vec{n})$ Reactions

Abstract

The measurement of complete sets of spin transfer coefficients in nuclear transitions, induced via charge-exchange (\((\vec p, \vec n)\)) 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, we present differential cross section and complete set of polarization transfer coefficients obtained in the (\(^{13} C(\vec p, \vec n)\)) 13N reaction studied at angles between 0° and 33° and at 197 MeV incident proton energy. 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 ΔJ π = 1− and ΔJ π = 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.