Antisymmetric distorted wave impulse approximation calculations of spin transfer cross sections for ((3)(He)over-right-arrow,(t)over-right-arrow) reactions to the continuum - art. no. 044611

A formalism is presented for the calculation of spin transfer cross section for intermediate energy charge exchange ((3)<(He)over right arrow>, (t) ov er right arrow) [and ((p) over right arrow,(n) over right arrow)] reactions to the continuum. The nuclear structure part of the formalism is based on the continuum Tamm-Dancoff method and the nuclear reaction part is treated within the distorted wave impulse approximation. In the nuclear structure p art, we thus include particle-hole correlations and continuum effects on th e excited particle. The knockon-exchange effect and the damping of the part icle through an imaginary potential added to the single particle real poten tial are also taken into account. Results of numerical calculations an pres ented for the inclusive cross sections sigma(0 degrees) and the spin transf er coefficients D-nn(0 degrees) for forward scattering, for the intermediat e energy ((3)<(He)over right arrow>, (t) over right arrow) and ((p) over ri ght arrow, (n) over right arrow) reactions on C-12 and Zr-90 targets leadin g to Gamow-Teller resonances in the continuum. It is shown that D-nn(0 degr ees) for this case takes a value of - 1/3, regardless of the details of nuc lear structure and reaction mechanisms, if the reaction is assumed to proce ed as an orbital angular momentum transfer l(t) = 0 process, and that devia tions from - 1/3 come from admixture of l(t) = 2 components. A simple close d form of the expression is derived which can be used to understand a subtl e dependence of the D-nn values on nuclear structure and effective interact ion.