Fission fragment decay simulations with the CGMF code

Talou, P.; Stetcu, I.; Jaffke, P.; Rising, Michael Evan; Lovell, A. E.; Kawano, Toshihiko

doi:10.1016/j.cpc.2021.108087

Cited by 53 publications

(38 citation statements)

References 87 publications

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“…The results of the 2E analysis (described above) are presented in the following sections. [44] (blue filled circles) and CGMF [45,46] (magenta open diamonds) up to E n = 20 MeV. The data are compared to the GEF (red dot-dashed curve) and CGMF [45] (cyan dashed curve) model predictions, as well as the reference [8] data (black open squares).…”

Section: Resultsmentioning

confidence: 99%

“…Since it is impractical to measure the actual number of neutrons emitted by each fragment, a statistical approach using the average prompt neutron multiplicity ν (m * i , E n ) to calculate primary fragment masses with equation ( 16) is employed. However, data on ν (m * i , E n ) is sparse [45], so a Monte Carlo simulation of the de-excitation of fission fragments is used to determine ν (m * i , E n ) (see section section IV E 3). Once the post-neutron evaporation masses are calculated, the measured kinetic energies of the fission products can be corrected for PHD using the measured PHD as a function of ion mass (see section section IV E 4).…”

Section: Mass Determinationmentioning

confidence: 99%

“…The probability of different modes of multichance fission occuring increases with increasing excitation energy of the compound nucleus (and hence, increasing incident neutron energy). In order to treat multichance fission in this work, the General Description of Fission Observables (GEF) [44] and Cascade Gamma Multiplicities from Fission (CGMF) [45] codes were used to generate compound nuclear mass probability distributions at the incident neutron energies listed in section section IV E 3. Multichance fission was then treated event-by-event when calculating post-neutron evaporation product masses via the 2E method by randomly selecting a mass from the compound nuclear mass distribution for the appropriate incident neutron energy range and using that [44] and CGMF [45,46] model simulations.…”

Section: Multichance Fissionmentioning

confidence: 99%

“…For the present analysis, neutron sawtooths for incident neutron energies from E n = 0.2 − 20.0 MeV were obtained from two different codes of the Monte-Carlo simulation of the de-excitation of fission fragments -GEF [44] and CGMF [45]. Presently, the CGMF model only performs simulations of 237 Np(n, f ) for incident neutron energies up to E n = 20.0 MeV, so only GEF neutron sawtooths and compound nuclear mass probability distributions (see section section IV E 2) were used in the the 2E analysis for E n > 20.0 MeV.…”

Section: Prompt Neutron Evaporationmentioning

confidence: 99%

“…Pre-and post-neutron evaporation T KE results for incident neutron energies in the range 0.0 ≤ E n ≤ 100.0 MeV using GEF neutron sawtooths in the 2E mass calculation are displayed in figure 14 and compared to the results of reference [8]. The red dot-dashed curves in figures 13 and 14 are the raw prediction of the GEF [44] model and the cyan dashed curves are the CGMF [45,46] predictions. For thermal neutron induced fission of 237 Examining figure 14, one observes a significant increase in the T KE values of the experimental data relative to the GEF model's prediction beginning at incident neutron energies of approximately E n ≈ 20 − 30 MeV.…”

Section: A Average Total Kinetic Energy Of Fission Fragments and Prod...mentioning

confidence: 99%

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Properties of correlated fission fragments from neutron induced fission of Np-237 at incident neutron energies between 200 keV and 100 MeV

Connolly¹,

Montoya²,

Duke³

et al. 2021

Preprint

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Background: Measurements of the neutron-induced fission of major actinides are vital to applications such as nuclear energy, nuclear forensics, nuclear nonproliferation and stockpile stewardship. Contemporary fission models are informed by additional correlated fission data, advancing toward a fully predictive fission model. Of particular interest are the average total kinetic energy ( T KE ) of the fission fragments, fission fragment mass yield distributions and correlations between mass and T KE as they evolve with excitation energy of the fissioning system. Neptunium-237 is produced in significant quantities in the nuclear fuel cycle. Its presence in spent reactor fuel and ∼ 2 × 10 6 year half life make a complete and precise understanding of its production and destruction desirable to inform reactor design. Little T KE data exists for 237 Np(n, f ), and until recently, there was no T KE nor mass yield data for 237 Np(n, f ) at incident neutron energies above E n = 5.55 MeV. The most recent measurement suffered from low statistics and relatively poor energy resolution compared to previous studies, so a higher quality data set is desired.Purpose: This study aimed to measure post-neutron evaporation mass yields and average total kinetic energy release of correlated fission products from neutron-induced fission of 237 Np over a wide range of incident neutron energies (particularly incident neutron energies above E n = 5.55 MeV), as well as to analyze how these quantities evolve with incident neutron energy. Method:The aforementioned measurements were obtained using a twin Frisch-gridded ionization chamber (TFGIC) and a thin-backed 237 Np target at the Los Alamos Neutron Science Center -Weapons Neutron Research (LANSCE -WNR) facility, which provides a collimated beam of neutrons with energies ranging from 100s of keV to 100s of MeV. The data were analyzed using the double-energy (or 2E) method, with mass-dependant corrections for prompt-fission neutrons and pulse height defect.Results: A total of 1.15 × 10 6 coincident fission events were recorded and analyzed using the 2E method. Preand post-neutron evaporation T KE values are reported for 54 incident neutron energies in the energy range 0.20 ≤ E n ≤ 100.0 MeV and compared to existing data and models. Pre-and post-neutron evaporation mass yields were extracted with a full width at half maximum (FWHM) resolution of approximately 4u and compared to existing data and evaluations. Conclusions:The present T KE and mass yield data agree with previous results and also with statistical models of 237 Np(n, f ) at incident neutron energies between E n = 0.2 − 20.0 MeV. A flattening of the T KE data is observed (relative to the GEF model's prediction) above E n = 20.0 MeV. However, the interpretation of this discrepancy is unclear as the analysis method's neglect of incomplete momentum transfer at high energies as well as pre-equilibrium pre-fission phenomena likely have a significant impact on the measurement at such high incident neutron energies.

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