Coulomb effects in low energy fission

Montoya, M.; Hasse, Rainer W.; Koczoń, P.

doi:10.1007/bf01294620

Cited by 10 publications

(23 citation statements)

References 9 publications

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“…However, we should note that charge fragmentation 41/51 is more asymmetric than the 42/50 fragmentation. Therefore that result is also consistent with the Coulomb effect: for neighboring masses with similar values of energy available, the more asymmetric fragmentation reaches the higher values of total kinetic energy [11,12].…”

Section: Fig 4: Thermal Neutron Induced Fission Of 235 U For Each Lsupporting

confidence: 75%

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

2018

Rev. ECIPeru

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Coulomb and even-odd effects in cold and super-asymmetric fragmentation for thermal neutron induced fission of 235U M. Montoya Instituto Peruano de Energía Nuclear, Canadá 1470, San Borja, Lima, Peru Universidad Nacional de Ingeniería, Av. Túpac Amaru 210, Rímac, Lima, Peru DOI: https://doi.org/10.33017/RevECIPeru2015.0004/ Abstract 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 235U. 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. Keywords: cold fission, asymmetric fragmentation, symmetric fission, kinetic energy, uranium 235 Resumen La hipótesis del efecto Coulomb es usado para interpretar los efectos par-impar sobre la energía total máxima en función de la masa y carga de los fragmentos de la fisión inducida por neutrones térmicos del 235U. Suponiendo que en la escisión los fragmentos son esféricos, la energía de interacción coulombiana entre fragmentos ( ) es mayor que el valor , la energía disponible. Entonces, los fragmentos en la escisión deben estar deformados, de modo que la energía de interacción coulombiana no exceda el valor de la reacción. El hecho de que los efectos par-impar sobre el valor máximo de la energía cinética total en función de la carga y la masa, respectivamente, son menores que los efectos par-impar de es consistente con la suposición que los fragmentos con masa impar son más blandos que los fragmentos par-par. Los efectos par-impar de la distribución de carga en las fragmentaciones super asimétricas también son interpretados con la hipótesis del efecto Coulomb. Debido a que la diferencia entre y crece con la asimetría, las fragmentaciones requieren mayor energía total de deformación para ocurrir. Mayor energía de deformación de los fragmentos implica menor energía libre para romper pares de nucleones. Esto explica por qué en la region de asimetría, los efectos par-impar en la distribución de número de protons y número de neutrones crece con la asimetría. Basado en un razonamiento similar, se predice un alto efecto par-impar en las fragmentaciones simétricas. Descriptores: fisión fría, fragmentación asimétrica, fisión simétrica, energía cinética, uranio 235.

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Section: Fig 4: Thermal Neutron Induced Fission Of 235 U For Each Lsupporting

confidence: 75%

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

2018

Rev. ECIPeru

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“…A lower P permits to reach a more compact scission configuration which implies a higher Coulomb Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. energy, then a higher yield of charge for the higher values of kinetic energy [6,7]. Moreover, a higher free energy (F=Q−P) of a given configuration implies a higher probability for that configuration to occur.…”

Section: Introductionmentioning

confidence: 99%

“…In this cold fission region, it was observed that for two isobaric fragmentations with the similar Q-value, the more asymmetric charge split (lower light fragment charge) occurs with higher probability. This property was named Coulomb effect [6,7].…”

Section: Introductionmentioning

confidence: 99%

Influence of neutron emission on the charge, mass and kinetic energy distribution of final fragments from ²³⁵U(n_th, f) reaction

Montoya

Rivera

2018

J. Phys. Commun.

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Using a Monte Carlo method we simulate an experiment that measures the mass, charge and kinetic energy of final fragments (after neutron emission) from the 235 U(n th , f) reaction. As input data for the simulation, for primary fragments (before neutron emission), we assume (i) a distribution of mass and kinetic energy; (ii) an average number of emitted neutron as a decreasing linear function of kinetic energy and (iii) for each mass, a constant yield of charges as a function of kinetic energy, equal to that obtained by W Lang et al for the highest measured kinetic energy window (108.5 MeV) which corresponds to the lowest measured excitation energy, that corresponds to the so called cold fission. The output of the simulation is the distribution of mass, charge and kinetic energy of final fragments. From this output we obtain that, for a given mass, the charge that has the highest yield in cold fission region has a yield obeying an increasing function of kinetic energy in all other region. Conversely, the yield of the less probable charge in cold fission is a decreasing function of kinetic energy in all other region. Our results of simulation suggest that, for two primary isobaric fragmentations with similar Q-value, the preference for more asymmetric charge splits (called Coulomb effect), observed in cold fission, is valid in all region, but neutron emission shadows this property in final fragments distribution.

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“…Las mediciones sobre las reacciones 233 U(n th , f), 235 U(n th , f) y 239 Pu(n th , f) muestran resultados que son interpretados como efectos de la variación de la energía de interacción electrostática entre fragmentos al cambiar por una unidad la carga de uno de los fragmentos [17,18].…”

Section: Efectos De Capas Y Efectos Coulombianos 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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Coulomb effects in low energy fission

Cited by 10 publications

References 9 publications

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

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

Influence of neutron emission on the charge, mass and kinetic energy distribution of final fragments from ²³⁵U(n_th, f) reaction

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

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Coulomb effects in low energy fission

Cited by 10 publications

References 9 publications

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

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

Influence of neutron emission on the charge, mass and kinetic energy distribution of final fragments from 235U(nth, f) reaction

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

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Influence of neutron emission on the charge, mass and kinetic energy distribution of final fragments from ²³⁵U(n_th, f) reaction