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

High-precision reduced electric-quadrupole transition probabilities B(E2) have been measured from single-step Coulomb excitation of semi-magic 58,60,62,64 Ni (Z = 28) beams at 1.8 MeV per nucleon on a natural carbon target. The energy loss of the nickel beams through the carbon target were directly measured with a zero-degree Bragg detector and the absolute B(E2) values were normalized by Rutherford scattering. The B(E2) values disagree with recent lifetime studies that employed the Doppler-shift attenuation method. The present high-precision B(E2) values reveal an asymmetry about 62 Ni, midshell between N = 28 and 40, with larger values towards 56 Ni (Z = N = 28). The experimental B(E2) values are compared with shell-model calculations in the full pf model space and the results indicate a soft 56 Ni core.

Allmond, James M↗

Production of Ni-Cr-Ti-natural fibres composite and investigation of mechanical properties

Intermetallic materials such as Ni{sub 2}Ti, Cr{sub 2}Ti are among advanced technology materials that have outstanding mechanical and physical properties for high temperature applications. Especially creep resistance, low density and high hardness properties stand out in such intermetallics. The microstructure, mechanical properties of (%50Ni-%48Cr-%2Ti)-%10Naturel Fibres and (%64Ni-%32Cr-%4Ti)-%10Naturel Fibres powders were investigated using specimens produced by tube furnace sintering at 1000-1200-1400°C temperature. A composite consisting of ternary additions, a metallic phase, Ti,Cr and Ni have been prepared under Ar shroud and then tube furnace sintered. XRD, SEM (Scanning Electron Microscope), were investigated to characterize the properties of the specimens. Experimental results carried out for composition (%64Ni-%32Cr-%4Ti)-%10Naturel at 1400°C suggest that the best properties as 112.09HV and 5,422g/cm{sup 3} density were obtained at 1400°C.

36 MATERIALS SCIENCE↗

Near-barrier fusion of Sn+Ni and Te+Ni Systems: Examining the influence of neutron transfer couplings

The fusion excitation functions for radioactive 132Sn+58Ni and stable 130Te+58;64Ni were measured at energies near the Coulomb barrier. The role of transfer couplings in heavy-ion fusion was examined through a comparison of Sn+Ni and Te+Ni systems, which have large variations in the number of positive Q-value nucleon transfer channels. In contrast with previous comparisons, where increased sub-barrier fusion cross sections were observed in the systems with positive Q-value neutron transfer channels, the reduced excitation functions were equivalent for the different Sn+Ni and Te+Ni systems. The present results suggest a significant change in the influence of transfer couplings on the fusion process for the Sn+Ni and Te+Ni systems.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Sub-barrier fusion enhancement with radioactive 134Te

The fusion cross sections of radioactive 134Te + 40Ca were measured at energies above and below the Coulomb barrier. The evaporation residues produced in the reaction were detected in a zero-degree ionization chamber providing high efficiency for inverse kinematics. Both coupled-channel calculations and comparison with similar Sn + Ca systems indicate an increased sub-barrier fusion probability that is correlated with the presence of positive Q-value neutron transfer channels. In comparison, the measured fusion excitation functions of 130Te + 58,64Ni, which have positive Q-value neutron transfer channels, were accurately reproduced by coupled-channel calculations including only inelastic excitations. The results demonstrate that the coupling of transfer channels can lead to enhanced sub-barrier fusion but this is not directly correlated with positive Q-value neutron transfer channels in all cases.

Kohley, Zachary W↗

Final Scientific EFNUDAT Workshop

F. Kappeler speaks about EFNUDAT synergies in astrophysics in this second session of the Final Scientific EFNUDAT Workshop. The workshop was organized by the CERN/EN-STI group on behalf of n_TOF Collaboration - will be held at CERN, Geneva (Switzerland) from 30 August to 2 September 2010 inclusive. EFNUDAT website: http://www.efnudat.euTopics of interest include: Data evaluation Cross section measurements Experimental techniques Uncertainties and covariances Fission properties Current and future facilities; International Advisory Committee: C. Barreau (CENBG, France) T. Belgya (IKI KFKI, Hungary) E. Gonzalez (CIEMAT, Spain)F. Gunsing (CEA, France)F.-J. Hambsch (IRMM, Belgium)A. Junghans (FZD, Germany) R. Nolte (PTB, Germany)S. Pomp (TSL UU, Sweden);Workshop Organizing Committee: Enrico Chiaveri (Chairman) Marco Calviani Samuel Andriamonje Eric Berthoumieux Carlos Guerrero Roberto Losito Vasilis Vlachoudis Workshop Assistant: Geraldine Jean.

22NI↗