Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping?

The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in 40Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at E_p = 200 MeV. Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon-nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for 40Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle two-hole (2p-2h) states.Comment: Phys. Lett. B, in pres

0f7/2 proton transfer on 55Mn

Proton pickup data have been obtained through the 55Mn(d,3He)54Cr (Ed = 46 MeV) reaction in the 6°-30° angular range using a magnetic spectrometer with a resolution of ∼ 40 keV full width at half maximum. Spectroscopic factors associated with transitions to 24 54Cr final slates (E*≤ 6.104 MeV) were determined from local, zero-range distorted-wave Born approximation analyses of the measured angular distributions allowing for / = 0, 1, 2, and 3 transfer. A spin-dependent sum-rule analysis of the 0f7/2 proton transfer data has been performed using complementary stripping data from a study of the 55Mn(α,t)56Fe reaction. The 0f7/2 proton transfer data have also been compared to results from a 0f1p shell-model calculation based on a new effective interaction for A = 41-66 nuclei.Articl

Role of knockout contributions in giant resonance studies with (p ,p′ x) reactions

The giant-resonance region in 40Ca and 48Ca has been studied using the reactions 48Ca(p ,p′ n0)47Ca, 40Ca(p ,p′ p0)39K, and 40Ca(p ,p′ α0)36Ar for an incident proton energy Ep= 100 MeV. Knockout cross sections for these reactions were calculated within the distorted wave impulse approximation formalism using parameters fixed from previous investigations. The results quantitatively account for the data at higher excitation energies while the knockout contributions underneath the main resonance strength are small.Articl

Low-energy isoscalar quadrupole strength in 40Ca and 48Ca from (p, p'x) reactions

A decomposition of giant multipole strength in 40Ca and 48Ca is performed from angular correlations and emission angle-integrated angular distributions of the reactions 40Ca(p,p'α0)36Ar, 40Ca(p,p'p0)39K and 48Ca(p,p'n0)47Ca. The deduced B(E2) strength distributions agree reasonably well in shape and magnitude with the results of electron-induced experiments. Previous suggestions of a systematic discrepancy of the total E2 strengths in the α0 channel derived from hadronic and electromagnetic probes are shown to be unfounded. In 48Ca, for the first time evidence for sizable isoscalar E2 strength at low excitation energies, similar to 40Ca, could be established. © 2001 Elsevier Science B.V.Articl