Isospin asymmetries in pion scattering to isoscalar giant quadrupole states in Ni isotopes

Isospin dependence of the isoscalar giant quadrupole response: Relevance to pion scattering in the Ni isotopes

“…3 the theoretical values of Mn/Mp are compared with experiment as a function of isotope number. Note that on the figure we have followed the idea by Oakley et al to display (M./Mv) 2 rather than (M,/Mp) in order to make the isospin dependence more prominent [6]. The experimental trend is well reproduced by our RPA results with a value of R c consistent with the RMS radii of the Ni isotopes.…”

“…We present here quantitative evidence to suggest that the same calculations which yield an isoscalar character to the GQR can also explain the high rc-/~z + ratios once the highly selective nature of the surface pion absorption process is taken into account. As an example, we undertake an explicit study of the isospin nature of the nuclear response in the GQR channel pion scattering by examining the recent inelastic scattering results of zc-and 7c + from 58'6~ [6]. The experimental results of 180 MeV pion beam at LAMPF show prominent quadrupole features that have been identified as predominantly isoscalar in character [3,6].…”

“…As an example, we undertake an explicit study of the isospin nature of the nuclear response in the GQR channel pion scattering by examining the recent inelastic scattering results of zc-and 7c + from 58'6~ [6]. The experimental results of 180 MeV pion beam at LAMPF show prominent quadrupole features that have been identified as predominantly isoscalar in character [3,6]. For the heavier isotopes, the zc-scattering cross sections greatly exceed those for ~z + (and are in that context consistent with pion scattering observations on heavier nuclei) [7,8].…”

Isospin character of transitions to bound states inPb204,206,208Hören1, Auble2, Beene3 et al. 1991Phys. Rev. C22320View full textAdd to dashboardCite

“…(tr+ ) calculations (or data), the argument persists that the reported ratios of o(vr )/o(tr+) for excitation of states in the continuum are a reAection of the radial difFerences of the neutron and proton transition densities. In fact, Oakley et al [12] have purported to demonstrate this effect by tr /tr measurements on a series of nickel isotopes, ' ' ' Ni, where the neutron separation energies vary from 12.2 to 9.66 MeV. Using Tassie model transition densities in DWIA calculations, they deduce M" /M ratios which increase from -N /Z for Ni to -1.54K /Z and 1.74%/Z for Ni and Ni, respectively.…”

Inelastic electron scattering to collective states ofSn118

“…The greater strength in alpha scattering could be due to the enhancement of the neutron contribution in the transition to the unbound final state, as suggested by model calculations including the unbound final wave functions [5]. This also could account for the observed asymmetry between sr+ and w scattering to the GQR [3,4,38]. One of the principal purposes of the present study was to test this concept.…”