Quadrupole Moment of the 8-μs Fission Isomer in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Pu</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>239</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>

Habs, D.; Metag, V.; Specht, H.J.; Ulfert, G.

doi:10.1103/physrevlett.38.387

Cited by 68 publications

(10 citation statements)

References 7 publications

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“…This, apparently, is true also for the realistic potentials where at approximately this deformation pronounced shell structure develops (which was found responsible for the shape isomers). The experimental deformation point for N= 146 and t/= 2 4-0.2 in Figure 1 a corresponds to the recently measured [22,23] quadrupole moments of the shape isomeric states in 239pu and 236pu. They agree with the position of the shell minimum in the level density which can be related to the 2:1 nonpianar orbits.…”

Section: Discussion Of the Gross-shell Distributionsmentioning

confidence: 95%

Semiclassical interpretation of the gross-shell structure in deformed nuclei

et al. 1977

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An analysis of the classical closed orbits in the infinitely deep elongated ellipsoidat well is given with respect to their relevance to the gross-shell structure of the single-particle spectra in deformed nuclei. It is shown that the deformed-shape gross-shells responsible for the ground state deformations, as well as those responsible for the fission intermediate states, find a reasonable explanation in terms of the semiclassical three-dimensional quantization involving the planar orbits in the axis-of-symmetry plane and the simplest three-dimensional orbits which appear at large distortions. The former are found important for the ground state shapes. The results are also compared with the harmonic oscillator model.

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Section: Discussion Of the Gross-shell Distributionsmentioning

confidence: 95%

Semiclassical interpretation of the gross-shell structure in deformed nuclei

et al. 1977

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“…With the use of this information a more accurate value for the quadrupole moment is derived from previous chargeplunger measurements. 4 Conversion electrons are measured with a solenoid spectrometer applying the recoil-shadow technique 0 5 The experimental arrangement is shown in Fig. 1.…”

Section: Spectroscopy In the Second Minimum Of The Potential Energy Smentioning

confidence: 99%

Spectroscopy in the Second Minimum of the Potential Energy Surface ofPu239

et al. 1979

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Conversion electrons from the decay of a spin isomer in the secondary minimum of 239 Pu have been measured. They are interpreted as transitions feeding and depopulating a rotational band built on the fission isomeric ground state with spin f. Rotational parameters of A = 3.36 ±0.10 keV and B =4 ±3 eV have been deduced. The observed upper limit on the M1/E2 mixing ratio of 1.4 suggests an antiparallel coupling between orbital angular momentum and spin vectors for the wave function of the fission isomer.Up to now single-particle models have not been crucially tested at large deformations of shape isomers (/3=t).6). Earlier attempts to identify single-particle states were based on measurements of fission-fragment angular distributions 1 and g factors 2 of the fissioning isomers in 237 Pu. This Letter reports on the identification of states in the second minimum of 239 Pu by observing conversion electrons feeding and depopulating the rotational band built on the fission isomeric state. Delayed feeding occurs from a T 1 / 2 = 2.6t*'£ ns spin isomer which on the average emits 1.6 conversion electrons in its decay to the 8-JUS fission isomer. 3 From the energies and theMl/E2 mixing ratio of the rotational transitions the spin and single-particle configuration of the fission isomer can be inferred. With the use of this information a more accurate value for the quadrupole moment is derived from previous chargeplunger measurements. 4

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“…Download Date | 6/13/16 9:10 AM A charge plunger method applicable to highly converted transitions has been developed by the Heidelberg group [89,90] and has been used to measure the lifetimes of rotational bands in the second minimum of actinide nuclei. The basic idea is illustrated in Fig.…”

Section: Unauthenticatedmentioning

confidence: 99%

12 The Measurement of Nuclear Lifetimes

1997

Experimental Techniques in Nuclear Physics

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Table of Contents I. Scope and definitions 425 II. Decay constants of "rare" decays 427 A. Very long lifetimes 427 B. Very small activities 428 C. Precision studies of the neutron lifetime 434 III. Direct timing methods (10~6 > τ > 10" 15 s) 437 A. Electronic and pulsed beam timing methods 437 B. Recoil shadow timing methods 445 C. The recoil distance "plunger" method 447 D. The Doppler shift attenuation method 453 E. The GRID method 466 IV. Measurement of very short lifetimes (τ < 10" 15 s) 472 A. X-ray timing 473 B. Crystal blocking 474 C. Nuclear resonance fluorescence 475 D. Determination of narrow resonance widths 478 References 482 I. Scope and definitionsThe decay modes of ground states and the low-lying nuclear states up to about 10 MeV excitation energy via ß-decay, electromagnetic radiations, particle emission and/or fission have been extensively studied for many decades. In all domains of nuclear structure investigations, the measurement of absolute decay probabilities and nuclear lifetimes has given important insight into the facets of nuclear many-body systems and has provided detailed data for in-depth tests of nuclear models. Some of these decay modes involve fundamentally known interactions, e.g. the electro-weak interaction in the case of β-and γ-decay processes, and thus are directly sensitive to the nuclear model wave functions to be tested. Other processes like nucleon emission, α-decay and fission are more difficult to deal with theoretically, as here the wave functions of the nuclear states involved in the transition and the nuclear transition operator, which both determine the decay probabilities, depend on the model used.The experimentally accessible range of nuclear lifetimes covers more than forty-five (!) orders of magnitude. When just considering α-decays, we have, on the one hand, the Unauthenticated Download Date | 6/13/16 9:10 AM

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Quadrupole Moment of the 8-μs Fission Isomer inPu239

Cited by 68 publications

References 7 publications

Semiclassical interpretation of the gross-shell structure in deformed nuclei

Semiclassical interpretation of the gross-shell structure in deformed nuclei

Spectroscopy in the Second Minimum of the Potential Energy Surface ofPu239

12 The Measurement of Nuclear Lifetimes

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