Comparison of the energy and mass characteristics of the<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:mo>(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">n</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">th</mml:mi></mml:mrow></mml

Wagemans, C.; Allaert, E.; Deruytter, A.J.; Barthelemy, Ramón S.; Schillebeeckx, P.

doi:10.1103/physrevc.30.218

Cited by 83 publications

(64 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Adding this pre-kinetic energy, our description gives a total kinetic energy (TKE) of 195 MeV which exceeds by only 10 MeV the experimental value 184.8 ± 1.7 MeV obtained by averaging the data sets available in the literature [13][14][15].…”

mentioning

confidence: 68%

Nuclear Scission and Quantum Localization

Younes

Gogny

2011

Phys. Rev. Lett.

View full text Add to dashboard Cite

We examine nuclear scission within a fully quantum-mechanical microscopic framework, focusing on the non-local aspects of the theory. Using 240 Pu hot fission as an example, we discuss the identification of the fragments and the calculation of their kinetic, excitation, and interaction energies, through the localization of the orbital wave functions. We show that the "disentanglement" of the fragment wave functions is essential to the quantum-mechanical definition of scission and the calculation of physical observables. Finally, we discuss the fragments' pre-scission excitation mechanisms and give a non-adiabatic description of their evolution beyond scission.Nuclear scission, the process wherein a nucleus breaks into two or more fragments, poses a fundamental challenge to quantum many-body theory: scission implies a separation of the nucleus into independent fragments, while the Pauli exclusion principle introduces a persistent correlation between the fragments, no matter how far apart they are. The objective of this paper is to resolve this paradox by disentangling the fragments in a fully quantum-mechanical description that is consistent with experimental data. In addition to shedding light on fundamental aspects of many-body physics, a microscopic theory of scission is needed to make reliable predictions of fission-fragment properties, such as their excitation and kinetic energies, and their shapes. In particular, we revisit in a microscopic approach the question of the energy partition between light and heavy fragments which was addressed in a recent letter [1] within a statistical-mechanic treatment. While many technical challenges remain in the 70-year quest to develop a predictive theory of fission, understanding scission, remains a formidable conceptual obstacle to such a theory.Previous descriptions of scission have always been formulated within the context of a nuclear density, with an identifiable neck joining two pre-fragments. The neck ruptures at some point along its length, and all the matter to one side or the other of the rupture is relegated to the corresponding fragment. Despite its usefulness, this is ultimately a classical view of scission. In 1959 [2], this picture was used to qualitatively account for the different observed mass divisions in fission and the well-known "sawtooth" shape of the average neutronmultiplicity distribution. Later on, a more quantitative description of the nuclear shape was introduced [3], and scission was equated with a vanishing neck size. This criterion was later improved [4] by requiring that scission occurs when the Coulomb repulsion exceeds the attractive nuclear force between the fragments. Nörenberg [5] took a step toward a more microscopic description using a molecular model of fission calculated in a two-center Hartree-Fock+BCS approach. Bonneau et al.[6] used separate microscopic calculations of each fragment and a phenomenological nuclear interaction between them to define a scission criterion based on the ratio of their mutual nuclear and Coulomb ener...

show abstract

mentioning

confidence: 68%

Nuclear Scission and Quantum Localization

Younes

Gogny

2011

Phys. Rev. Lett.

View full text Add to dashboard Cite

show abstract

“…5 were obtained in experiments using thermal neutrons [26][27][28]. Unfortunately, there are no such data for higher incident energy.…”

Section: Fragment Energiesmentioning

confidence: 99%

Event-by-event evaluation of the prompt fission neutron spectrum from239Pu(n,f)

et al. 2012

View full text Add to dashboard Cite

“…Figure 6 shows the mean total fragment kinetic energy as a function of mass number of the heavy fragment as obtained by using a common tip separation d 0 for all fission channels. A comparison to the data [26,27,28] shows significant discrepancies near symmetry where the calculated TKE exhibit an enhancement whereas the data have a dip.…”

Section: B Fragment Energiesmentioning

confidence: 74%

“…Figure 3 shows the principal measurements of the mean TKE as a function of the mass number of the heavy fragment, A H , which were made by Wagemans et al [26], Nishio et al [27], and Tsuchiya et al [28]. (The mass number of the heavy fragment is found by simultaneously measuring the velocities and energies of both fragments [27].…”

Section: Fission Fragment Energiesmentioning

confidence: 99%

Event-by-event study of prompt neutrons fromPu239(n,f)

et al. 2009

View full text Add to dashboard Cite

Employing a recently developed Monte-Carlo model, we study the fission of 240 Pu induced by neutrons with energies from thermal to just below the threshold for second chance fission. Current measurements of the mean number of prompt neutrons emitted in fission, together with less accurate measurements of the neutron energy spectra, place remarkably fine constraints on predictions of microscopic calculations. In particular, the total excitation energy of the nascent fragments must be specified to within 1 MeV to avoid disagreement with measurements of the mean neutron multiplicity. The combination of the Monte-Carlo fission model with a statistical likelihood analysis also presents a powerful tool for the evaluation of fission neutron data. Of particular importance is the the fission spectrum, which plays a key role in determining reactor criticality. We show that our approach can be used to develop an estimate of the fission spectrum with uncertainties several times smaller than current experimental uncertainties for outgoing neutron energies of less than 2 MeV.

show abstract

Comparison of the energy and mass characteristics of thePu239(nth

Cited by 83 publications

References 9 publications

Nuclear Scission and Quantum Localization

Nuclear Scission and Quantum Localization

Event-by-event evaluation of the prompt fission neutron spectrum from239Pu(n,f)

Event-by-event study of prompt neutrons fromPu239(n,f)

Contact Info

Product

Resources

About