973 research outputs found
Angular momentum projection of cranked Hartree-Fock states: Application to terminating bands in A~44 nuclei
We present the first systematic calculations based on the angular-momentum
projection of cranked Slater determinants. We propose the Iy --> I scheme, by
which one projects the angular momentum I from the 1D cranked state constrained
to the average spin projection of =I. Calculations performed for the
rotational band in 46Ti show that the AMP Iy --> I scheme offers a natural
mechanism for correcting the cranking moment of inertia at low-spins and
shifting the terminating state up by ~2 MeV, in accordance with data. We also
apply this scheme to high-spin states near the band termination in A~44 nuclei,
and compare results thereof with experimental data, shell-model calculations,
and results of the approximate analytical symmetry-restoration method proposed
previously.Comment: 9 RevTeX pages, 8 EPS figures, submitted to Physical Review
Study of Deformation Effects in the Charged Particle Emission from 46Ti
The 46Ti compound nucleus, as populated by the fusion-evaporation reaction
27Al + 19F at the bombarding energy of 144 MeV, has been investigated by
charged particle spectroscopy using the multidetector array ICARE at the
VIVITRON tandem facility of the IReS (Strasbourg). The light charged particles
have been measured in coincidence with evaporation residues. The CACARIZO code,
a Monte Carlo implementation of the statistical-model code CASCADE, has been
used to calculate the spectral shapes of evaporated alpha-particles which are
compared with the experimental spectra. This comparison indicates the possible
signature of large deformations of the compound nucleus.Comment: 6 pages, 4 figures, Proceedings od the Zakopane 20004 Symposium, to
be published in Acta Phys. Pol. B36 (2005
Spin-orbit term and spin-fields: extension of Skyrme-force induced local energy density approach
A systematic study of terminating states in A50 mass region using the
self-consistent Skyrme-Hartree-Fock model is presented. The objective is to
demonstrate that the terminating states, due to their intrinsic simplicity,
offer unique and so far unexplored opportunities to study different aspects of
the effective NN interaction or nuclear local energy density functional. In
particular, we demonstrate that the agreement of the calculations to the data
depend on the spin fields and the spin-orbit term which, in turn, allows to
constrain the appropriate Landau parameters and the strength of the spin-orbit
potential.Comment: 23 pages, 9 figures, submitted to PR
Large Deformation Effects in the N = Z 44Ti Compound Nucleus
The N = Z 44Ti* nucleus has been populated in Fusion Evaporation process at
very high excitation energies and angular momenta using two entrance channels
with different mass-asymmetry. The deformation effects in the rapidly rotating
nuclei have been investigated through the energy distribution of the
alpha-particle combined to statistical-model calculations. In the case of
low-multiplicity events, the ratio between first particle emitted has been
measured and shows significant disagreement with the predictions of the
statistical-model. This may explain The large discrepancies observed in proton
energy spectra measured in previous experiments performed in the same mass
region.Comment: Proceeding of the 10th International Conference on Nuclear Reaction
Mechanisms, Varenna Italy, June 9-13 2003. 10 pages, 6 figures, 1 tabl
Strong Deformation Effects in Hot Rotating 46Ti
Exotic-deformation effects in 46Ti nucleus were investigated by analysing the
high-energy gamma-ray and the alpha-particle energy spectra. One of the
experiments was performed using the charged-particle multi-detector array ICARE
together with a large volume (4"x4") BGO detector. The study focused on
simultaneous measurement of light charged particles and gamma-rays in
coincidence with the evaporation residues. The experimental data show a
signature of very large deformations of the compound nucleus in the Jacobi
transition region at the highest spins. These results are compared to data from
previous experiments performed with the HECTOR array coupled to the EUROBALL
array, where it was found that the GDR strength function is highly fragmented,
strongly indicating a presence of nuclei with very large deformation.Comment: 10 pages, 6 figures, Proceedings of the Zakopane Conference on
Nuclear Physics, to be published in Acta Phys. Pol. B (2007
Search for Fingerprints of Tetrahedral Symmetry in
Theoretical predictions suggest the presence of tetrahedral symmetry as an
explanation for the vanishing intra-band E2-transitions at the bottom of the
odd-spin negative parity band in . The present study reports on
experiment performed to address this phenomenon. It allowed to determine the
intra-band E2 transitions and branching ratios B(E2)/B(E1) of two of the
negative-parity bands in .Comment: presented by Q.T. Doan at XLII Zakopane School of Physics: Breaking
Frontiers: Submicron Structures in Physics and Biology, May 2008. 5 pages,
minor corrections. To be published in the proceeding
GDR Feeding of the Highly-Deformed Band in 42Ca
The gamma-ray spectra from the decay of the GDR in the compound nucleus
reaction 18O+28Si at bombarding energy of 105 MeV have been measured in an
experiment using the EUROBALL IV and HECTOR arrays. The obtained experimental
GDR strength function is highly fragmented, with a low energy (10 MeV)
component, indicating a presence of a large deformation and Coriolis effects.
In addition, the preferential feeding of the highly-deformed band in 42Ca by
this GDR low energy component is observed.Comment: 6 pages, 2 figures, Proceedings of the Zakopane2004 Symposium, to be
published in Acta Phys. Pol. B36 (2005
High-spin states and band terminations in v 49
High-spin states in 49 V have been studied through the 28 Si(28 Si, α3p) reaction using the EUROBALL Îł-ray detector array. The 49 V level scheme has been extended up to 13.1 MeV including 21 new states. Both negative and positive parity states have been interpreted in the framework of theShell Model. The 27/2â and the 31/2+ band termination states have been observed in agreement with theoretical predictions.Fil: Rodrigues Ferreira Maltez, Dario Pablo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de InvestigaciĂłn y Aplicaciones No Nucleares. Gerencia FĂsica (Centro AtĂłmico Constituyentes). Proyecto Tandar; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de FĂsica; ArgentinaFil: Hojman, Daniel Leonardo. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de InvestigaciĂłn y Aplicaciones No Nucleares. Gerencia FĂsica (Centro AtĂłmico Constituyentes). Proyecto Tandar; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Lenzi, Silvia M.. Istituto Nazionale Di Fisica Nucleare.; Italia. UniversitĂ di Padova; ItaliaFil: Cardona, Maria Angelica. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de InvestigaciĂłn y Aplicaciones No Nucleares. Gerencia FĂsica (Centro AtĂłmico Constituyentes). Proyecto Tandar; Argentina. Universidad Nacional de San MartĂn. Escuela de Ciencia y TecnologĂa; ArgentinaFil: Fernea, Enrico. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Axiotis, M.. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Beck, C.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Bednarczyk, P.. Polish Academy of Sciences; ArgentinaFil: Bizzetti, P. G.. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Bizzetti Sona, A. M.. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Della Vedova, F.. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Grebosz, J.. Polish Academy of Sciences; ArgentinaFil: Haas, F.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Kmiecik, M.. Polish Academy of Sciences; ArgentinaFil: Maj, A.. Polish Academy of Sciences; ArgentinaFil: MÄczyĆski, W.. Polish Academy of Sciences; ArgentinaFil: Napoli, D. R.. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Nespolo, M.. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Papka, P.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: SĂĄnchez i Zafra, A.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Styczen, J.. Polish Academy of Sciences; ArgentinaFil: Thummerer, S.. Alfred-Wegener-Institut, Helmholtz-Zentrum fĂŒr Polar- und Meeresforschung; AlemaniaFil: ZiÄbliĆski, M.. Polish Academy of Sciences; Argentin
Reverse Bisimulations on Stable Configuration Structures
The relationships between various equivalences on configuration structures,
including interleaving bisimulation (IB), step bisimulation (SB) and hereditary
history-preserving (HH) bisimulation, have been investigated by van Glabbeek
and Goltz (and later Fecher). Since HH bisimulation may be characterised by the
use of reverse as well as forward transitions, it is of interest to investigate
forms of IB and SB where both forward and reverse transitions are allowed. We
give various characterisations of reverse SB, showing that forward steps do not
add extra power. We strengthen Bednarczyk's result that, in the absence of
auto-concurrency, reverse IB is as strong as HH bisimulation, by showing that
we need only exclude auto-concurrent events at the same depth in the
configuration
Application of Diamond Detectors in Tracking of Heavy Ion Slowed Down Radioactive Beams
Results of irradiation of thin Chemical Vapor Deposition (CVD) diamond detectors with low energy: p,α and 7Li beams are presented. Energy resolution: ÎE/E<1% of a single crystal detector was achieved. A coincident measurement with two diamond detectors showed time resolution of 100âps and efficiency above 70%. Despite a high beam flux reaching 109 particles/sâcm2 the tested detectors showed low dead-time and satisfactory radiation hardness. Perspectives of applying thin CVD diamond detectors in monitoring of a slowed down radioactive beam (RIB) are discussed.Spanish Ministry of Education and Science (MEC) FFPA2003-05958 and PA-2005-0446
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