Excitation of the 21+ and 22+ states in the 88Sr(p, p′) reaction at 25 and 31 MeV:A look behind the nuclear surface

Data for the excitation of the 21+ and 22+ states in the 88Sr(p, p′) reaction at 25 and 31 MeV indicate substantial contributions from the interior of the nucleus, Microscopic DWBA calculations reproduce this and yield a fair description of the data. A detailed description, especially of the 22+ state, is sensitive to the effective nucleon-nucleon interaction used and the non-locality of the optical potential, which are insufficiently known at present

Angular distribution of photons from the delay of the GDR in hot and rotating light Yb nuclei from exclusive experiments

Abstract Angular distributions of photons associated with the damping of excited-state giant dipole resonances (GDR) in hot and rotating 161,162 Yb nuclei have been measured in exclusive experiments using the HECTOR array. In reactions with heavy ions ( 48 T) angular distributions are determined as a function of the angular momentum of the compound nuclei. In reactions with lighter ions ( 17,18 O) a difference method is applied to isolate GDR decays originating from specific excitation regions. The systematics of the measured angular distributions as a function of excitation energy and angular momentum are compared to theories taking into account fluctuations of the shape and orientation of the excited nuclei

Angular momentum dependence of the GDR width in Sn nuclei at fixed excitation energy

Abstract High-energy γ-rays from the decay of the giant-dipole resonance (GDR) in the hot 106Sn compound nucleus and its daughters were measured in coincidence with heavy recoiling evaporation residues. The compound nucleus was formed at excitation energy E ∗ = 80 MeV using the reaction 56Ni+48Ti at a bombarding energy of 260 MeV. The analysis yields the GDR width for two different intervals of angular momentum 〈J〉 = 24 and 36ℏ. The present data, combined with previous data at higher angular momentum permit a study of the angular momentum dependence of the GDR width for 10 ⩽ J ⩽ 60ℏ at approximately fixed temperature. The width of the GDR is found to be roughly constant for

Excitation of low-lying states in 144Nd by means of (e,e') scattering

Abstract The low-lying states of 144Nd have been investigated up to an excitation energy of 3.1 MeV by means of high-resolution inelastic electron scattering. Transition charge densities have been extracted for natural-parity states. The experimental data have been compared with the predictions of the quasiparticle-phonon model. The calculations show that both collective and single-particle degrees of freedom are important for describing the low-lying states of 144Nd. A comparison of the present data with data for 142Nd and 142Ce emphasizes the role played by the two valence neutrons outside the N = 82 closed shell

Effect of E1 decay in the population of superdeformed structures

Abstract Spectra of the yrast and excited superdeformed bands, forming the E2 quasi-continuum, are measured with the EUROBALL array for the nucleus 143 Eu, in coincidence with high-energy γ-rays (Eγ>3 MeV). It is found that the intensity population of the superdeformed states is enhanced by a factor of ≈1.6 when a coincidence with a γ-ray with energy >6 MeV is required, in reasonable agreement with the increase of the line shape of the Giant Dipole Resonance built on a superdeformed configuration. This result shows that when an high energy E1 γ-ray is involved in the decay it is more likely connected with a SD rather than a ND nucleus. In addition, the analysis of the rotational quasi-continuum suggests the presence of a superdeformed component. The data are also compared and found consistent with simulation calculations of the relative intensities of the SD states, including the E1 decay of superdeformed nature

The rotational γ-continuum in the mass region A≈110

Abstract Unresolved γ transitions of 114 Te and of 112 Sn sorted into one-dimensional and two-dimensional spectra have been studied. The reaction 64 Ni + 54 Cr at bombarding energies 230, 240, 250, 260, 270 MeV was used and the γ -rays were detected with the EUROBALL array. In the case of the nucleus 114 Te the values of the multiplicity as a function of bombarding energy and of the moment of inertia were obtained. The effective moment of inertia was found to be almost constant in the interval I=20 – 40 ℏ , in contrast to the decreasing behaviour of the dynamic moment of inertia for the terminating yrast band. The ridge valley structures in E γ 1 ×E γ 2 spectra of 114 Te and of 112 Sn were analysed with the fluctuation analysis technique. The analysis of the two nuclei are compared to simulations based on microscopic cranking calculations with residual interactions included. A rather good agreement is found between data and predictions

Quantum tunneling of the excited rotational bands in the superdeformed nucleus 143Eu

The properties of the thermally excited rotational motion up to the region of rotational damping are studied experimentally in the superdeformed nucleus 143 Eu. The effective lifetime of the excited discrete rotational bands forming ridge structures in ‐ matrices is measured at the EUROBALL array using the DSAM technique, giving a quadrupole momentQt 10 e b, consistent with the deformation of the superdeformed yrast band. In addition, the effective number of excited superdeformed bands is extracted by a statistical analysis of the ridge structure, for transition energies down to the region where the effect of the decay-out into the normal deformed well shows up. The experimental data are compared with microscopic cranked shell model calculations including a residual interaction of surface delta type. Satisfactory agreement between data and theory is obtained when the quantum tunneling of the excited superdeformed states is included in the model. © 2001 Published by Elsevier Science B.V

Low-lying octupole strength in 112Cd

The low-lying octupole strength distribution in 112Cd has been measured by means of inelastic proton scattering. A splitting of the strength has been observed and interpreted as due to the interaction between the quadrupole and octupole degrees of freedom. The splitting can be reproduced by the IBA-1 model if the coupling of f- and d-bosons is considered

Quadrupole core polarization charges in the A=100 and 150 mass regions

The neutron and proton quadrupole core polarization charges are evaluated from the comparison of 0gs+ → 21+ quadrupole transition matrix elements measured by inelastic scattering of different incident probes on Mo, Pd, Cd, Nd, Sm, Gd and Dy isotopes. The resulting values, and in particular those obtained in the framework of the interacting boson model, are discussed with special attention to the evaluation of the strength of low-lying mixed-symmetry states

Low-lying states of 56 Fe

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