A large strain explicit formulation for composites Rubert, José B.; Oller, Sergio; Las Casas, Estevam B. ...
International journal for numerical methods in engineering,
12/1999, Letnik:
46, Številka:
10
Journal Article
Using state-of-the-art γ-ray spectroscopic techniques, the first rotational band of a superheavy element, extending up to a spin of 20 ℏ, was discovered in the nucleus 256Rf. To perform such an ...experiment at the limits of the present instrumentation, several developments were needed. The most important of these developments was of an intense isotopically enriched 50Ti beam using the MIVOC method. The experimental set-up and subsequent analysis allowed the 256Rf ground-state band to be revealed. The rotational properties of the band are discussed and compared with neighboring transfermium nuclei through the study of their moments of inertia. These data suggest that there is no evidence of a significant deformed shell gap at Z = 104.
A high intensity ion beam of
50
Ti ions was obtained using the ECR ion source on the U400 cyclotron. The experimental tests using accelerated
50
Ti ions were performed with a modernized VASSILISSA ...separator (SHELS). Data has been obtained on the transmission coefficients of recoil nuclei synthesized in complete fusion reactions. Estimates from ion optical calculations performed in the design phase of the project of modernizing the separator are completely confirmed.
Decay spectroscopy of the odd-proton nuclei $^{249}$Md and $^{251}$Md has
been performed. High-$K$ isomeric states were identified for the first time in
these two nuclei through the measurement of ...their electromagnetic decay. An
isomeric state with a half-life of $2.8(5)$ ms and an excitation energy $\geq
910$ keV was found in $^{249}$Md. In $^{251}$Md, an isomeric state with a
half-life of $1.4(3)$ s and an excitation energy $\geq 844$ keV was found.
Similarly to the neighbouring $^{255}$Lr, these two isomeric states are
interpreted as 3 quasi-particle high-$K$ states and compared to new theoretical
calculations. Excited nuclear configurations were calculated within two
scenarios: via blocking nuclear states located in proximity to the Fermi
surface or/and using the quasiparticle Bardeen-Cooper-Schrieffer method.
Relevant states were selected on the basis of the microscopic-macroscopic model
with a deformed Woods-Saxon potential. The most probable candidates for the
configurations of $K$-isomeric states in Md nuclei are proposed.
The odd-\(Z\) \(^{251}\)Md nucleus was studied using combined \(\gamma\)-ray and conversion-electron in-beam spectroscopy. Besides the previously observed rotational band based on the \(5211/2^-\) ...configuration, another rotational structure has been identified using \(\gamma\)-\(\gamma\) coincidences. The use of electron spectroscopy allowed the rotational bands to be observed over a larger rotational frequency range. Using the transition intensities that depend on the gyromagnetic factor, a \(5147/2^-\) single-particle configuration has been inferred for this band, i.e., the ground-state band. A physical background that dominates the electron spectrum with an intensity of \(\simeq\) 60% was well reproduced by simulating a set of unresolved excited bands. Moreover, a detailed analysis of the intensity profile as a function of the angular momentum provided a method for deriving the orbital gyromagnetic factor, namely \(g_K = 0.69^{+0.19}_{-0.16}\) for the ground-state band. The odd-\(Z\) \(^{249}\)Md was studied using \(\gamma\)-ray in-beam spectroscopy. Evidence for octupole correlations resulting from the mixing of the \(\Delta l = \Delta j = 3\) \(5213/2^-\) and \(6337/2^+\) Nilsson orbitals were found in both \(^{249,251}\)Md. A surprising similarity of the \(^{251}\)Md ground-state band transition energies with those of the excited band of \(^{255}\)Lr has been discussed in terms of identical bands. Skyrme-Hartree-Fock-Bogoliubov calculations were performed to investigate the origin of the similarities between these bands.
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