Possible evidences for Giant Quadrupole Resonances within neutron-induced <i>α</i>-particle emission

A fine agreement of recently measured and presently calculated ( n, α ) cross sections at a low incident energy almost entirely related to the ground-state activation, supports additionally an α -particle OMP. Further calculated underestimation of the energy dependence of these data, beyond any model parameter uncertainty, is described by a Gaussian distribution around isoscalar giant quadrupole resonance (ISGQR) energy, of ~14.2 MeV, with a peak cross section of 0.36±0.04 mb, width of 1.8±0.1 MeV, and ISGQR-like strength function of 4.3±1.9% energy weighted sum rule (EWSR). The α -particle decay of nuclei excited at ISGQR energies in ( n, α ) reactions is linked to ISGQR-like strength functions with even around 50% larger uncertainty than ISGQR strengths measured by 3 He and α -particle inelastic scattering. An isotope effect is also observed in the corresponding ( γ, α ) and neutron-induced α -emission data, following the Q -value decrease with the asymmetry parameter ( N − Z ) /A of the target nuclei.