21 research outputs found
Polarization and relaxation of radon
Investigations of the polarization and relaxation of Rn by spin
exchange with laser optically pumped rubidium are reported. On the order of one
million atoms per shot were collected in coated and uncoated glass cells.
Gamma-ray anisotropies were measured as a signal of the alignment (second order
moment of the polarization) resulting from the combination of polarization and
quadrupole relaxation at the cell walls. The temperature dependence over the
range 130C to 220C shows the anisotropies increasing with
increasing temperature as the ratio of the spin exchange polarization rate to
the wall relaxation rate increases faster than the rubidium polarization
decreases. Polarization relaxation rates for coated and uncoated cells are
presented. In addition, improved limits on the multipole mixing ratios of some
of the main gamma-ray transitions have been extracted. These results are
promising for electric dipole moment measurements of octupole-deformed
Rn and other isotopes, provided sufficient quantities of the rare
isotopes can be produced.Comment: 4 pages, 4 figure
A study on the transition between seniority-type and collective excitations in 204Po and 206Po
Low-lying yrast states in 204Po and 206Po have been investigated by the γ-γ fast timing technique with LaBr3(Ce) detectors. Excited states of these nuclei were populated in the 197Au(11B,4n) and the 198Pt(12C,4n) fusion-evaporation reactions, respectively, at the FN-Tandem Facility at the University of Cologne. The lifetimes of the 4+1 states in both nuclei were measured, along with an upper limit for the 2+1 state in 204Po. The preliminary results are discussed in the scope of the systematic behavior of the transition strengths between yrast states in polonium isotopes
Coulomb Excitation of Proton-rich N = 80 Isotones at HIE-ISOLDE
A projectile Coulomb-excitation experiment was performed at the radioactive ion beam facility HIE-ISOLDE at CERN. The radioactive ¹⁴⁰Nd and ¹⁴²Sm ions were post accelerated to the energy of 4.62 MeV/A and impinged on a 1.45 mg/cm²-thin ²⁰⁸Pb target. The γ rays depopulating the Coulomb-excited states were recorded by the HPGe-array MINIBALL. The scattered charged particles were detected by a double-sided silicon strip detector in forward direction. Experimental γ-ray intensities were used for the determination of electromagnetic transition matrix elements. Preliminary results for the reduced transition strength of the B(M1;23+→21+)=0.35(19)μN2 of ¹⁴⁰Nd and a first estimation for ¹⁴²Sm have been deduced using the Coulomb-excitation calculation software GOSIA. The 2³₊ states of ¹⁴⁰Nd and ¹⁴²Sm show indications of being the main fragment of the proton-neutron mixed-symmetry 2⁺₁,ms state
Benchmarking the PreSPEC@GSI experiment for Coulex-multipolarimetry on the π(p3 / 2) → π(p1 / 2) spin-flip transition in 85Br
Aydın, Sezgin ( Aksaray, Yazar )A first performance test of the Coulomb excitation multipolarimetry (Coulex-multipolarimetry) method is presented. It is based on a 85Brπp3/2→πp1/2 spin-flip experiment performed as part of the PreSPEC-AGATA campaign at the GSI Helmholtzzentrum für Schwerionenforschung (GSI). Via determination of background levels around the expected 85Br excitations as well as measured 197Au excitations, an upper limit for the M1 transition strength of the 1/21-→3/2g.s.- transition in 85Br and a lower beam time limit for upcoming experimental campaigns utilizing Coulex-multipolarimetry have been inferred. The impact of the use of AGATA in its anticipated 1 π configuration on these estimates is deduced via Geant4 simulations. © 2020, Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature
Lifetimes and electromagnetic transition strength in 124Ba
Lifetimes of excited states of 124Ba were measured by the Recoil Distance Doppler Shift (RDDS) technique. The γ-ray coincidence data were analysed by the Differential Decay Curve method (DDCM). The trend of the experimentally deduced normalized B(E2) values reveals a drop at the 8+1 state, which may be caused by structural changes in the backbending region
Lifetimes and electromagnetic transition strength in
Lifetimes of excited states of 124Ba were measured by the Recoil Distance Doppler Shift (RDDS) technique. The γ-ray coincidence data were analysed by the Differential Decay Curve method (DDCM). The trend of the experimentally deduced normalized B(E2) values reveals a drop at the 8+1 state, which may be caused by structural changes in the backbending region