arXiv subjects

D. Galaviz

Publications and source records attributed to D. Galaviz.

41 records · Page 3Linked to original sources

arXiv2006

Z=50 shell gap near $^{100}$Sn from intermediate-energy Coulomb excitations in even-mass $^{106--112}$Sn isotopes

Rare isotope beams of neutron-deficient $^{106,108,110}$Sn nuclei from the fragmentation of $^{124}$Xe were employed in an intermediate-energy Coulomb excitation experiment yielding $B(E2, 0^+_1 \to 2^+_1)$ transition strengths. The results indicate that these $B(E2,0^+_1 \to 2^+_1)$ values are much larger than predicted by current state-of-the-art shell model calculations. This discrepancy can be explained if protons from within the Z = 50 shell are contributing to the structure of low-energy excited states in this region. Such contributions imply a breaking of the doubly-magic $^{100}$Sn core in the light Sn isotopes.

nucl-ex↗

arXiv2005

$^{187}$Re(\gamm,n) cross section close to and above the neutron threshold

The neutron capture cross section of the unstable nucleus $^{186}$Re is studied by investigating the inverse photodisintegration reaction $^{187}$Re($γ$,n). The special interest of the {\it s}-process branching point $^{186}$Re is related to the question of possible {\it s}-process contributions to the abundance of the {\it r}-process chronometer nucleus ^{187}$Re. We use the photoactivation technique to measure photodisintegration rates. Our experimental results are in good agreement with two different statistical model calculations. Although the cross sections predicted by both models for the inverse reaction $^{186}$Re(n,$γ$) is too low to remove the overproduction of $^{186}$Os; the two predicted neutron-capture cross sections differ by a factor of 2.4; this calls for future theoretical study.

astro-ph↗

arXiv2005

Elastic alpha-scattering of 112Sn and 124Sn at astrophysically relevant energies

The cross sections for the elastic scattering reactions {112,124}Sn(a,a){112,124}Sn at energies above and below the Coulomb barrier are presented and compared to predictions for global alpha-nucleus potentials. The high precision of the new data allows a study of the global alpha-nucleus potentials at both the proton and neutron-rich sides of an isotopic chain. In addition, local alpha-nucleus potentials have been extracted for both nuclei, and used to reproduce elastic scattering data at higher energies. Predictions from the capture cross section of the reaction 112Sn(a,g)116Te at astrophysically relevant energies are presented and compared to experimental data.

astro-ph↗

arXiv2005

Systematic study of (g,n) reaction rates for Z>=78 isotopes

The (g,n) reaction rates of the isotopes 196,198,204-Hg and 204-Pb have been determined using the photoactivation technique in an energy region relevant for p process nucleosynthesis. The systematic study of the ground-state (g,n) reaction rates on even-even nuclei in the mass region Z>=78 is complemented with these experiments. The data are compared to rates predicted in the framework of two statistical model approaches.

astro-ph↗

arXiv2001

$^{92}$Mo($α,α$)$^{92}$Mo scattering,the $^{92}$Mo--$α$ optical potential, and the $^{96}$Ru($γ,α$)$^{92}$Mo reaction rate at astrophysically relevant energies

The elastic scattering cross section of$^{92}$Mo($α$,$α$)$^{92}$Mo has been measured at energies of $E_{\rm{c.m.}} \approx$ 13, 16, and 19 MeV in a wide angular range. The real and imaginary parts of the optical potential for the system $^{92}$Mo - $α$ have been derived at energies around and below the Coulomb barrier. The result fits into the systematic behavior of $α$-nucleus folding potentials. The astrophysically relevant $^{96}$Ru($γ$,$α$)$^{92}$Mo reaction rates at $T_9=2.0$ and $T_9=3.0$ could be determined to an accuracy of about 16 % and are compared to previously published theoretical rates.

astro-ph↗