Spin-isospin resonances in nuclei

Abstract

Spin-isospin excitations in nuclei have been investigated via the ( 3He,t) reaction at 450 MeV. The volume integrals of the effective interactions J στ and J τ for the ( 3He,t) reaction at 450 MeV have been empirically determined to be 172±17 MeV-fm 3 and 53±5 MeV-fm 3, respectively. These values are consistent with those obtained for the (p,n) reaction at the same bombarding energy per nucleon. The Gamow-Teller strength can be deduced with the same reliability as the (p,n) reaction at the bombarding energy above 100 MeV. The neutrino absorption cross sections by 71Ga is obtained on basis of the present ( 3He,t) measurement. The new SNU value obtained for 71Ga is 130.3±1.6(stat.)±16.8(syst.). The spin-isospin responses for the Sn isotopes, 116Cd and 100Mo are presented and are discussed in relation with double β-decay. A measurement of decay protons from the spin-isospin resonances in 13N is presented. A new possibility of studying the spin-isospin responses on the β + side via the (t, 3He) reaction using a dispersion matching technique is discussed.