Evidence for nucleon pair breaking even in the coldest scission configurations of 234U and 236U

Signarbieux, C.; Montoya, M.; Ribrag, M.; Mazur, C.; Guet, C.; Perrin, Paul B.; Maurel, Marie‐Christine

doi:10.1051/jphyslet:019810042019043700

Cited by 75 publications

(58 citation statements)

References 7 publications

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“…La separación de masas con el método de tiempo de vuelo de los fragmentos fue la prueba de que no hubo emisión de neutrones. El experimento se realizó en el reactor HFR del ILL de Grenoble [8,9].…”

Section: Emisión De Neutrones Y Efectos Par-impar En La Fisión Fríaunclassified

Ruptura de pares y efectos coulombianos en la fisión fría de las reacciones 233U(NTH, F), 235U(NTH, F) Y 239PU(NTH, F)

Montoya

2013

TEC

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Section: Emisión De Neutrones Y Efectos Par-impar En La Fisión Fríaunclassified

Ruptura de pares y efectos coulombianos en la fisión fría de las reacciones 233U(NTH, F), 235U(NTH, F) Y 239PU(NTH, F)

Montoya

2013

TEC

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“…In the thermal neutron induced fission, the mass and charge distributions of fragments exhibit a fine structure that show a preference for even neutrons and protons fission products [1][2][3][4][5]. We expect that this phenomenon will be more evidenced in the case of cold fission, where the excitation energy of the fragments is so small that no neutrons can be emitted.…”

Section: Introductionmentioning

confidence: 99%

Inversion of the Odd-Even Effect in Cold Fission from the Time-Dependent Pairing Equations

Mirea

2016

EPJ Web of Conferences

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Abstract.A peculiar phenomenon was observed experimentally in cold fission: the odd partition yields are favored over the even ones for excitations energies of the fragments smaller than 4 MeV. In this contribution, a microscopic model is proposed for the explanation of this odd-even effect in cold fission. This explanation is based on a mixing configuration mechanism that is produced during the fission process. This configuration mixing mechanism is obtained dynamically by solving a the generalized system of time-dependent pairing equations, which include a pair-breaking effect. The time dependent equations of motion for the pair breaking effect were corroborated with a condition that fixes dynamically the number of particles on the two fission fragment. The single particle level scheme was calculated with the Woods-Saxon superasymmetric two center shell model, providing a continuous variation of the single particle energies and of the wave functions from one nucleus up to two separated fragments. A first rule can be extracted from this model. The even-even fission products cannot be obtained at zero excitation energies because of the existence of dynamical excitations produced in the avoided-level-crossing regions when the nuclear system deforms slowly.

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“…Taking into account the events from thermal neutron induced fission of 235 U, obtained in 1981 by Signarbieux et al [2], in 1984 M. Montoya presents the curve of threshold values for the 10 events with the highest total kinetic energy values [7]. These threshold values are assumed to correspond to the maximum total kinetic energy for each isobaric fragmentation.…”

Section: Even-odd Effects In the Maximum Total Kinetic Energymentioning

confidence: 99%

Coulomb and even-odd effects in cold and super-asymmetric fragmentation for thermal neutron induced fission of 235U

Montoya

2016

AIP Conference Proceedings

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The Coulomb effects hypothesis is used to interpret even-odd effects of maximum total kinetic energy as a function of mass and charge of fragments from thermal neutron induced fission of 235 U. Assuming spherical fragments at scission, the Coulomb interaction energy between fragments ( ) is higher than the -value, the available energy. Therefore at scission the fragments must be deformed, so that the Coulomb interaction energy does not exceed the -value. The fact that the even-odd effects in the maximum total kinetic energy as a function of the charge and mass, respectively, are lower than the even-odd effects of is consistent with the assumption that odd mass fragments are softer than the even-even fragments. Even-odd effects of charge distribution in super asymmetric fragmentation also are interpreted with the Coulomb effect hypothesis. Because the difference between and increases with asymmetry, fragmentations require higher total deformation energy to occur. Higher deformation energy of the fragments implies lower free energy to break pairs of nucleons. This explains why in the asymmetric fragmentation region, the even-odd effects of the distribution of proton number and neutron number increases with asymmetry. Based on a similar reasoning, a prediction of a relatively high even-odd effect in symmetric fragmentations is proposed.

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Evidence for nucleon pair breaking even in the coldest scission configurations of 234U and 236U

Cited by 75 publications

References 7 publications

Ruptura de pares y efectos coulombianos en la fisión fría de las reacciones 233U(NTH, F), 235U(NTH, F) Y 239PU(NTH, F)

Ruptura de pares y efectos coulombianos en la fisión fría de las reacciones 233U(NTH, F), 235U(NTH, F) Y 239PU(NTH, F)

Inversion of the Odd-Even Effect in Cold Fission from the Time-Dependent Pairing Equations

Coulomb and even-odd effects in cold and super-asymmetric fragmentation for thermal neutron induced fission of 235U

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