Gamow-teller strength in the continuum and quenching problem

Abstract

Differential cross sections at θ lab = 0.0° – 12.3° and a complete set of polarization transfer observables at θ lab = 0.0° are measured for the 90 Zr( p,n ) reaction at T p = 295 MeV. A multipole decomposition analysis (MDA) technique is applied to the cross sections to deduce the Gamow-Teller (GT) strength B (GT). The obtained S β − = Σ B (GT) value is 28.0 ± 1.6. The total spin transfer Σ is obtained for the continuum by using polarization transfer measurements. The S β − — S β + value is deduced to be 27.0 and this is 90% of Ikeda's sum rule value of 3( N — Z )=30. Thus the quenching of the GT strength is small and the quenching mechanism due to the ΔN − admixture seems to play a minor role.