Isomers in neutron-rich A ≈ 190 nuclides from 208Pb fragmentation

Caamaño, M.; Walker, P. M.; Regan, P. H.; Pfützner, M.; Podolyák, Zs.; Gerl, J.; Hellström, M.; Mayet, P.; Mineva, Milena; Aprahamian, A.; Benlliure, J.; Bruce, A. M.; Butler, P. A.; Gil, D.; Cullen, D. M.; Döring, J.; Enqvist, T.; Fox, C.; Narro, J. Garcés; Geißel, H.; Gelletly, W.; Giovinazzo, J.; Górska, M.; Grawe, H.; Grzywacz, R.; Kleinböhl, A.; Körten, W.; Lewitowicz, M.; Lucas, R.; Mach, H.; O’Leary, C. D.; Oliveira, F. de; Pearson, C. J.; Rejmund, F.; Rejmund, M.; Sawicka, M.; Schaffner, H.; Schlegel, C.; Schmidt, K.‐H.; Stevenson, P. D.; Theisen, Ch.; Vivès, F.; Warner, D. D.; Wheldon, C.; Wollersheim, H. J.; Wooding, S. C.; Fang, Xu; Yordanov, O.

doi:10.1140/epja/i2004-10079-7

Cited by 98 publications

(35 citation statements)

References 43 publications

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“…Isomeric states also provide increased experimental sensitivity in non-selective reaction processes such as relativistic fragmentation [1], and deep-inelastic collisions (see, for example, Ref. [2] and references therein).…”

Section: Introductionmentioning

confidence: 99%

High-spin yrast structure ofHg204from the decay of a four-hole,22+isomer

et al. 2015

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Section: Introductionmentioning

confidence: 99%

High-spin yrast structure ofHg204from the decay of a four-hole,22+isomer

et al. 2015

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“…Experimentally, low-lying spectroscopy provides a very powerful source of information that allows one to establish signatures correlating the nuclear shape evolution with the energy spectra [14][15][16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Collective structural evolution in neutron-rich Yb, Hf, W, Os, and Pt isotopes

et al. 2011

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An interacting-boson-model Hamiltonian determined from Hartree-Fock-Bogoliubov calculations with the microscopic Gogny energy density functional D1M is applied to the spectroscopic analysis of neutron-rich Yb, Hf, W, Os, and Pt isotopes with mass A ∼ 180-200. Excitation energies and transition rates for the relevant low-lying quadrupole collective states are calculated by this method. Transitions from prolate to oblate ground-state shapes are analyzed as a function of neutron number N in a given isotopic chain by calculating excitation energies, B(E2) ratios, and correlation energies in the ground state. It is shown that such transitions tend to occur more rapidly for the isotopes with lower proton number Z when departing from the proton shell closure Z = 82. The triaxial degrees of freedom turn out to play an important role in describing the considered mass region. Predicted low-lying spectra for the neutron-rich exotic Hf and Yb isotopes are presented. The approximations used in the model and the possibilities to refine its predictive power are addressed.

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“…8 The fragments of the Pb nucleus, after being tracked through a magnetic separator, were stopped and their g-decay photons were measured in germanium detectors (see figure 3). The experimenters were able to associate the emitted gammas, ion by ion, with specific fragments over decay-sequence correlation times as long as 100 ms.…”

Section: Box 1 Broken Pairs and Isomer Half-livesmentioning

confidence: 99%

“…The fragment separator at GSI, the heavy-ion accelerator facility in Darmstadt, Germany, is a prolific source of newly discovered isomers. In a recent experiment, 8 lead-208 nuclei, accelerated to 1 GeV per nucleon, fragment on a beryllium target. Fragments are separated and steered by magnets, and tracked and timed by wire-chamber and scintillation detectors.…”

Section: Vibration and Rotationmentioning

confidence: 99%

Ups and Downs of Nuclear Isomers

Walker¹,

Carroll²

2005

Physics Today

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W hat could one do with a clean source of nuclear energy? That tantalizing question reflects a dream that some have hoped to realize by exploiting the energy-storage capabilities of nuclear isomers. But the hope hinges on facets of nuclear behavior that remain unknown despite decades of study. Electromagnetic transitions and b decay, the basic mechanisms that largely determine isomer halflives, are well understood. In many cases, however, it is still not possible to predict half-lives even to within an order of magnitude.Today's isomer research seeks a better understanding of the degrees of freedom that will reveal new aspects of nuclear structure and lead the way to new applications. In this article, we lay out the essential ingredients of nuclear isomerism and take a look at future possibilities. Metastable excited statesThe term "isomer" is borrowed from chemistry, where it refers to molecules that have different geometrical configurations of the same collection of atoms. Isomeric nuclei, as distinguished from isotopes, are different states of the same numbers of protons and neutrons. Whereas chemical isomers have energy states that are similar, sometimes identical, to each other, nuclear isomers always have different energies. Excitation energies can be as high as several MeV.An interesting example of a nuclear isomer is 99m Tc, an excited state of technetium-99. The "m" after the mass number denotes a metastable state-that is, a long-lived isomer. The half-life of 99m Tc is six hours and its excitation energy above the nuclear ground state of 99 Tc is 143 keV. By contrast, typical half-lives of excited nuclear states are about a picosecond. Isomers live at least a thousand times longer. The appellation is usually reserved for excited nuclear states that live longer than a nanosecond. The superscript "m" is even more restrictive; it's reserved for isomers with half-lives of more than a millisecond. If a nuclear species has more than one metastable isomer, an ordinal number after the "m" distinguishes between them in ascending order of excitation energy.Perhaps the most widely known nuclear isomer is the long-lived hafnium excitation 178m2 Hf. With a half-life of 31 years, it sits 2.4 MeV above the stable 178 Hf ground state. The exceptional combination of high excitation energy and conveniently long halflife has led to claims for practical applications that have lent the hafnium isomer unusual visibility (see PHYSICS TODAY, May 2004, page 21).Nature's sole example of an isomer long-lived enough to be called stable is 180m Ta. This tantalum isomer's half-life exceeds 10 15 years. One can only quote a lower lifetime limit, because the isomer's spontaneous decay has never been observed. But the isomer sits 77 keV above a ground state that is itself unstable, with a b-decay halflife of only eight hours.Isomers can lose their excess energy by the usual radioactive decay modes: a, b, or g. The favored mode in any particular case depends on the energies and quantum numbers of the states involved. Decay by neutron o...

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Isomers in neutron-rich A ≈ 190 nuclides from 208Pb fragmentation

Cited by 98 publications

References 43 publications

High-spin yrast structure ofHg204from the decay of a four-hole,22+isomer

High-spin yrast structure ofHg204from the decay of a four-hole,22+isomer

Collective structural evolution in neutron-rich Yb, Hf, W, Os, and Pt isotopes

Ups and Downs of Nuclear Isomers

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