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Wild, J. F.; Aarle, J. van; Westmeier, W.; Lougheed, R. W.; Hulet, E.K.; Moody, K. J.; Dougan, R.J.; Koop, Esther; Glaser, RE; Brandt, R.; Patzelt, P.

doi:10.1103/physrevc.41.640

Cited by 47 publications

(21 citation statements)

References 8 publications

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“…The most striking and significant features are that the mass-yield distribution is essentially single-peaked around the symmetric masssplit, resulting in products with the mass number A ∼ 130, whereas the TKE distribution apparently exhibits the structure with a shoulder that strongly suggests the presence of at least two components in the TKE distribution. As typical data, the TKE and mass-yield distributions observed in SF of 260 Md [41] are depicted in Fig. 5a,b, respectively; two components are clearly seen in the TKE distribution.…”

Section: Total Kinetic Energy (Tke) Distribution Of Fission Fragmentsmentioning

confidence: 99%

“…The neutron multiplicity (ν) distributions in correlation with TKE of the fragments were also measured and a large drop in the number of neutrons emitted from the high-TKE component was observed (dashed histogram in Fig. 5c), implying that the fragments with the high-TKE component are less deformed while those with low-TKE are largely deformed at scission [41]. The authors called the fission with such phenomena as bimodal fission.…”

Section: Total Kinetic Energy (Tke) Distribution Of Fission Fragmentsmentioning

confidence: 99%

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Two-mode fission – experimental verification and characterization of two fission-modes

Nagame

Nakahara

2012

Radiochimica Acta

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Summary.Experimental verification and characterization of the two-mode fission are reviewed. The presence of two independent deformation-paths in low energy fission of actinides is demonstrated by studying correlation among saddle-point configurations, scission-point configurations, and mass-yield distributions; the elongated scission configuration is related with the fission process that goes over a higher threshold energy and results in a symmetric mass-division mode, while the compact scission configuration with the process that experiences a lower threshold ends up with an asymmetric mass-division mode. Based on an extensive systematic analysis of scission properties in a wide range of actinide fission, the bimodal fission observed in the spontaneous fission of the heavy actinides is interpreted as the result of the presence of two fission paths, namely, the ordinary asymmetric fission path and a strongly shell-influenced symmetric mode.

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Section: Total Kinetic Energy (Tke) Distribution Of Fission Fragmentsmentioning

confidence: 99%

Section: Total Kinetic Energy (Tke) Distribution Of Fission Fragmentsmentioning

confidence: 99%

Two-mode fission – experimental verification and characterization of two fission-modes

Nagame

Nakahara

2012

Radiochimica Acta

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“…The most striking and significant features are that the mass-yield distribution is essentially single-peaked around the symmetric mass split, resulting in products with the mass number A ≈ 130, whereas the total kinetic energy (TKE) distribution apparently exhibits the structure with a shoulder that strongly suggests the presence of at least two components in the TKE distribution. As typical data, the TKE and massyield distributions observed in SF of 260 Md [68] are depicted in Fig. 8a,b, respectively; two components are clearly seen in the TKE distribution.…”

Section: Spontaneous Fissionmentioning

confidence: 79%

Production and properties of transuranium elements

Nagame¹,

Hirata

2011

Radiochimica Acta

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Actinides / Syntheses / Electronic structure / Physical and chemical properties Summary. We summarize historical perspective of the transuranium elements, neptunium (Np) through lawrencium (Lr), and recent progress on production, and nuclear and chemical properties of these elements. Exotic decay properties of heavy nuclei are also introduced. Chemical properties of transuranium elements in aqueous and solid states are summarized based on the actinide concept.

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“…The two such valleys have been found in recent potential-energy-surface calculations 2,4 " 6 to be separated by a rather high ridge which serves to prevent reequilibration during the descent to scission. Recent results from the neutron multiplicity measurements 10 in the spontaneous fission of 260 Md provide rather conclusive evidence in support of explaining the bimodal symmetric fission in terms of two such valleys corresponding to distinctly different scission configurations.…”

Section: B S Bhandari Physics Department Faculty Of Science Univementioning

confidence: 90%

Resonant tunneling and the bimodal symmetric fission ofFm258

Bhandari

1991

Phys. Rev. Lett.

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The concept of resonant tunneling is invoked to explain the sharp drop in the measured spontaneousfission half-life when going from 256 Fm to 258 Fm. Various consequences of such a suggestion on the other observed characteristics of the bimodal symmetric fission of 258 Fm are briefly discussed.PACS numbers: 25.85.Ca, 27.90.+b Bimodal symmetric fission of the heaviest known elements has been of considerable interest 1 " 9 over the past few years. It exhibits two distinctly different components in the total-kinetic-energy (TKE) distributions of the fission fragments occurring concurrently in the symmetric mass division in the spontaneous fission of 258 Fm and of a few other elements in this region of the actinide nuclei. Such results are qualitatively understood in terms of two distinguishable modes of spontaneous fission, each of which is derived from the effects of the shell structure. The first mode corresponds to the effects of the shell structure in the parent fissioning nucleus and leads to fission along the so-called "old" valley resulting in liquid-drop-type elongated scission shapes similar to the scission configuration for the lighter actinides, with relatively low TKE values centered around 200 MeV and a broadly symmetric fission-fragment mass distribution. On the other hand, the second mode produces a sharply symmetric fission-fragment mass distribution with rather large values of the TKE of the fragments ( -235 MeV) approaching the Q value for the fission reaction. This mode is believed to occur because of the strong shell effects in the emerging fission fragments approaching the doubly magic l32 Sn nuclei with closed proton and neutron shells (Z=50, TV =82). Such fragment-shelldirected symmetric fission is found to occur along the so-called "new" valley leading to very compact scission configuration of two touching spheres. The two such valleys have been found in recent potential-energy-surface calculations 2,4 " 6 to be separated by a rather high ridge which serves to prevent reequilibration during the descent to scission. Recent results from the neutron multiplicity measurements 10 in the spontaneous fission of 260 Md provide rather conclusive evidence in support of explaining the bimodal symmetric fission in terms of two such valleys corresponding to distinctly different scission configurations.Spontaneous-fission properties of the actinide nuclei are known to vary fairly smoothly as one goes from uranium (Z =92) to fermium (Z = 100). An increase in the proton number of the fissioning nucleus leads to a gradual decrease in fission-fragment mass asymmetry, an increase in fission-fragment kinetic energies, and a decrease in fission half-lives. Except for the fission halflives these quantities vary fairly slowly with the neutron number of the fissioning nucleus. However, at 258 Fm there are sudden dramatic changes in all of these quantities. Fission becomes symmetric with a very narrow mass distribution, the average TKE values are about 35 MeV higher than in the asymmetric fission of 256 Fm, and th...

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Prompt neutron emission from the spontaneous fission ofMd260

Cited by 47 publications

References 8 publications

Two-mode fission – experimental verification and characterization of two fission-modes

Two-mode fission – experimental verification and characterization of two fission-modes

Production and properties of transuranium elements

Resonant tunneling and the bimodal symmetric fission ofFm258

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