Shell model description of Ge isotopes

A shell model study of the low energy region of the spectra in Ge isotopes for $38\leq N\leq 50$ is presented, analyzing the excitation energies, quadrupole moments, $B(E2)$ values and occupation numbers. The theoretical results have been compared with the available experimental data. The shell model calculations have been performed employing three different effective interactions and valence spaces.We have used two effective shell model interactions, JUN45 and jj44b, for the valence space $f_{5/2} \, p \,g_{9/2}$ without truncation. To include the proton subshell $f_{7/2}$ in valence space we have employed the $fpg$ effective interaction due to Sorlin {\it et al.}, with $^{48}$Ca as a core and a truncation in the number of excited particles.Comment: 10 pages, 10 figures, Proc. of the XXXV Nuclear Physics Symposium, January 3-6 2012, Cocoyoc, Morelos, Mexico. IOP Journal of Physics: Conference Series (in press

Double-magic nature of 132Sn and 208Pb through lifetime and cross-section measurements

Single-neutron states in Sn133 and Pb209, which are analogous to single-electron states outside of closed atomic shells in alkali metals, were populated by the (Be9, Be8) one-neutron transfer reaction in inverse kinematics using particle-γ coincidence s

High-precision B(E2) measurements of semi-magic Ni 58,60,62,64 by Coulomb excitation

High-precision reduced electric-quadrupole transition probabilities B(E2;01+→21+) have been measured from single-step Coulomb excitation of semi-magic Ni58,60,62,64 (Z=28) beams at 1.8 MeV per nucleon on a natural carbon target. The energy loss of the

Measurement of two-halo neutron transfer reaction p(11^{11}Li,9^{9}Li)t at 3AA MeV

The p(\nuc{11}{Li},\nuc{9}{Li})t reaction has been studied for the first time at an incident energy of 3$A$ MeV delivered by the new ISAC-2 facility at TRIUMF. An active target detector MAYA, build at GANIL, was used for the measurement. The differential cross sectionshave been determined for transitions to the \nuc{9}{Li} ground andthe first excited states in a wide range of scattering angles. Multistep transfer calculations using different \nuc{11}{Li} model wave functions, shows that wave functions with strong correlations between the halo neutrons are the most successful in reproducing the observation.Comment: 6 pages, 3 figures, submitted to Physical Review Letter

Electromagnetic properties of the 21+ state in 134Te: Influence of core excitation on single-particle orbits beyond 132Sn

The g factor and B(E2) of the first excited 2+ state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide 134Te (two protons outside 132Sn) produced as a radioactive beam. The precision achieved matches related g-factor m

Magnetic moments of 2 1 + states in 124,126,128 Sn

The g factors of the first-excited states of stable 124Sn and radioactive 126,128Sn were measured by the recoil-in-vacuum method with comparatively high precision. The experiments were performed at the Holifield Radioactive Ion Beam Facility by Coulomb e

Recent direct reaction experimental studies with radioactive tin beams

Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z=50 proton shell closure, as well as the neutron shell closures lying in the neutron-rich, N=82, and neutron-deficient, N=50, regions. Here we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in 131Sn from across the N=82 shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient 106,108Sn. In both cases, measurements of gamma rays in coincidence with charged particles proved to be invaluable.Comment: 11 pages, 5 figures, Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape", Zakopane, Poland, August 31 - September 7, 201