8 research outputs found
First Measurement of Collectivity of Coexisting Shapes based on Type II Shell Evolution: The Case of Zr
Background: Type II shell evolution has recently been identified as a
microscopic cause for nuclear shape coexistence. Purpose: Establish a low-lying
rotational band in 96-Zr. Methods: High-resolution inelastic electron
scattering and a relative analysis of transition strengths are used. Results:
The B(E2; 0_1^+ -> 2_2^+) value is measured and electromagnetic decay strengths
of the secdond 2^+ state are deduced. Conclusions: Shape coexistence is
established for 96-Zr. Type II shell evolution provides a systematic and
quantitative mechanism to understand deformation at low excitation energies.Comment: 5 pages, 4 figure
Evolution of the dipole polarizability in the stable tin isotope chain
The dipole polarizability of stable even-mass tin isotopes
112,114,116,118,120,124 was extracted from inelastic proton scattering
experiments at 295 MeV under very forward angles performed at RCNP. Predictions
from energy density functionals cannot account for the present data and the
polarizability of 208Pb simultaneously. The evolution of the polarizabilities
in neighboring isotopes indicates a kink at 120Sn while all model results show
a nearly linear increase with mass number after inclusion of pairing
corrections.Comment: 10 pages, 6 figures, submitted to Phys. Lett.
Electric and magnetic dipole strength in 112,114,116,118,120,124Sn
Inelastic proton scattering experiments were performed at the Research Center
for Nuclear Physics, Osaka, with a 295 MeV beam covering laboratory angles
0{\deg}-6{\deg} and excitation energies 6-22 MeV. Cross sections due to E1 and
M1 excitations were extracted with a multipole decomposition analysis and then
converted to reduced transition probabilities with the "virtual photon method"
for E1 and the "unit cross section method" for M1 excitations, respectively.
Including a theory-aided correction for the high excitation energy region not
covered experimentally, the electric dipole polarizability was determined from
the E1 strength distributions. Total photoabsorption cross sections derived
from the E1 and M1 strength distributions show significant differences compared
to those from previous (,xn) experiments in the energy region of the
isocvector giant dipole resonance (IVGDR). The widths of the IVGDR deduced from
the present data with a Lorentz parameterization show an approximately constant
value of about 4.5 MeV in contrast to the large variations between isotopes
observed in previous work. The IVGDR centroid energies are in good
correspondence to expectations from systematics of their mass dependence.
Furthermore, a study of the dependence of the IVGDR energies on bulk matter
properties is presented. The E1 strengths below neutron threshold show fair
agreement with results from (,') experiments on
112,116,120,124Sn in the energy region between 6 and 7 MeV. At higher
excitation energies large differences are observed pointing to a different
nature of the excited states with small ground state branching ratios. The
isovector spin-M1 strengths exhibit a broad distribution between 6 and 12 MeV
in all studied nuclei.Comment: 32 pages, 23 figures, submitted to Phys. Rev.
Study of the
The 4He(4He,4He)4He* inelastic scattering was revisited in a new coincidence measurement at the MAGNEX facility of Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud. The 4He + 4He → 4He + 4He* → 4He + 3H + 1H and 4He + 4He → 4He + 4He* → 4He + 3He + n reactions were measured simultaneously by detecting the 4He particles at the MAGNEX magnetic spectrometer in coincidence with the 3H and 3He at the OSCAR silicon telescope. The main concept of the experiment is described and the data reduction strategy is reported