Data di Pubblicazione:
2004
Citazione:
Study of thermally excited nuclei through E1 and E2 decay from collective modes / B. Million, A. Bracco, G. Benzoni, S. Leoni, F. Camera, O. Wieland, A. Maj, M. Kmiecik, A. Gadea, B. Herskind. - In: THE EUROPEAN PHYSICAL JOURNAL. A, HADRONS AND NUCLEI. - ISSN 1434-6001. - 20:1(2004), pp. 157-162.
Abstract:
The nuclear system at the limit of excitation energy and angular momentum is here studied in
the case of the superdeformed nucleus 143Eu using γ-spectroscopy techniques. The data are based on a
EUROBALL experiment using the reaction 37Cl + 110Pd →143Eu + 4n. The influence of thermal energy on
superdeformed configurations is investigated through the analysis of the quasi-continuum spectra formed
by E2 transitions among states of excited rotational bands with energy extending up to 4-5 MeV above
the yrast line. In particular, the effective lifetimes of the discrete rotational bands forming ridge structures
in γ-γ coincidence matrices is measured by a Doppler Shift Attenuation Method. The deduced quadrupole
deformation of Qt ≈ 10 eb indicates that the nucleus maintains its collectivity with increasing excitation
energy, supporting the superdeformed character of the excited nuclear rotation. The obtained number of
superdeformed discrete bands forming the ridge structures is found in good agreement with microscopic
cranked shell model calculations including the decay-out process into the lower deformation minimum. In
addition, the nuclear properties at higher excitation energies are investigated through the E1 γ-decay of
the giant dipole resonance (GDR). It is found that the intensity of the superdeformed yrast and excited
bands increases by a factor of approximately 1.6 when a coincidence with a high-energy γ-ray is required,
showing the importance of the E1 cooling in the feeding mechanism of the superdeformed states.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
B. Million, A. Bracco, G. Benzoni, S. Leoni, F. Camera, O. Wieland, A. Maj, M. Kmiecik, A. Gadea, B. Herskind
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