0000000000900244
AUTHOR
Daniel Cano Ott
Measurement of the a ratio and (n,¿) cross section of U 235 from 0.2 to 200 eV at n_TOF
We measured the neutron capture-to-fission cross-section ratio (a ratio) and the capture cross section of 235U between 0.2 and 200 eV at the n_TOF facility at CERN. The simultaneous measurement of neutron-induced capture and fission rates was performed by means of the n_TOF BaF2 Total Absorption Calorimeter (TAC), used for detection of ¿ rays, in combination with a set of micromegas detectors used as fission tagging detectors. The energy dependence of the capture cross section was obtained with help of the 6 Li(n,t) standard reaction determining the n_TOF neutron fluence; the well-known integral of the 235U(n, f ) cross section between 7.8 and 11 eV was then used for its absolute normalizat…
Fine structure of the Gamow-Teller resonance revealed in the decay of Ho-150 2(-) isomer
The γ rays following the 72s 150Ho 2- Gamow-Teller β decay have been investigated with the CLUSTER CUBE setup, an array of six EUROBALL CLUSTER Ge detectors in close cubic geometry, providing a γ ray detection sensitivity of 2×10-5 per β-parent decay for γ-ray energies up to 5 MeV. The fine structure of the Gamow-Teller resonance at 4.4-MeV excitation in 150Dy has been studied. The resolved levels are compared with Shell Model predictions.
beta decay of Ag-97: Evidence for the Gamow-Teller resonance near Sn-100
In two complementary measurements, a cubelike array of 6 Euroball-Cluster germanium detectors and a total-absorption gamma-spectrometer were used to investigate the beta decay of 97Ag, a three proton-hole nucleus with respect to the 100Sn core. The half-life and QEC value of the decay of the 9/2+ ground state of 97Ag were determined to be 25.9(4) s and 6.98(11) MeV, respectively. A total of 603 gamma rays (578 new) was observed, and 151 levels (132 new) in 97Pd have been identified. An interesting beta-delayed gamma cascade was observed, which comprises 6 gamma-transitions with a deexcitation pattern involving an initial increase of the level spin. The Gamow-Teller (GT) beta-decay strength …
Deformation of the N = Z nucleus Sr-76 using beta-decay studies
A novel method of deducing the deformation of the N=Z nucleus 76Sr is presented. It is based on the comparison of the experimental Gamow-Teller strength distribution B(GT) from its beta decay with the results of QRPA calculations. This method confirms previous indications of the strong prolate deformation of this nucleus in a totally independent way. The measurement has been carried out with a large Total Absorption gamma Spectrometer, 'Lucrecia', newly installed at CERN-ISOLDE.
B(GT) strength from beta-decay measurements and inferred shape mixing in Kr-74
A total absorption spectrometer, dedicated to the study of very short-lived atomic species, has been built and installed at the CERN/ISOLDE mass separator. The beta decay of the neutron-deficient Kr-74 nucleus has been studied using this new device. The Gamow-Teller strength distribution has been observed over most of the Q(EC) window, and a total strength of 0.69(3) g(A)(2)/4pi has been measured for states with excitation energy below 3 MeV. Shape mixing in the Kr-74 ground state is inferred from a comparison of the experimental strength distribution with self-consistent, deformed, quasiparticle-random-phase-approximation calculations.