Prompt fission neutron multiplicity and spectrum model for 30–80 MeV neutrons incident on 238U

Tudora, Anabella; Vlăducă, G.; Morillon, B.

doi:10.1016/j.nuclphysa.2004.04.112

Cited by 31 publications

(36 citation statements)

References 11 publications

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“…[2] clearly show that RF of the secondary Th chain and the partial RF of the deuteron way are very low (of about 10 −3 and less than 10 −3 , respectively). Consequently in this work the contribution of the Th secondary chain and of the "deuteron" way have been neglected.…”

Section: Features Of the Modelingmentioning

confidence: 91%

“…The prompt emission from nuclei of secondary chains was already included in the extended Los Alamos model (LAM) described in Refs. [1,2]. In the case of n+ 238 U at En up to 80 MeV, the extended LAM calculation of Ref.…”

Section: Features Of the Modelingmentioning

confidence: 99%

“…In the case of n+ 238 U at En up to 80 MeV, the extended LAM calculation of Ref. [2] has taken into account the following nucleus chains and ways: (i) the main nucleus chain, indexed (1) with neutron evaporation from the precursor of this chain; (ii) the "proton" way (denoted as "p") consisting in proton emission from the nuclei of the main chain, leading to nuclei of the secondary chain indexed (2); (iii) the "neutron via proton" (pn) way consisting in neutron evaporation from the precursor of the secondary chain (2); (iv) the "deuteron" way consisting in deuteron emission from the nuclei of the main chain, also leading to nuclei of the secondary chain (2); (v) the "alpha" way consisting in alpha emission from the nuclei of the main chain, leading to the formation of another secondary nucleus chain (3); (vi) the "neutron via alpha" way consisting in neutron evaporation from the precursor of the secondary chain (3). Recursive formulae giving the average excitation energies of the fissioning nuclei formed by the 6 ways mentioned above can be found in Ref.…”

Section: Features Of the Modelingmentioning

confidence: 99%

“…Recursive formulae giving the average excitation energies of the fissioning nuclei formed by the 6 ways mentioned above can be found in Ref. [2].…”

Section: Features Of the Modelingmentioning

confidence: 99%

“…These probabilities are expressed as total and partial fission cross-section ratios RF (for details see Ref. [2] and references therein). At the upper limit of the present calculations, being En = 80 MeV for n+ 238 U, the prompt emission from 10 nuclei of the main uranium chain, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Point-by-point model calculation of the prompt neutron multiplicity distribution ν(A) in the incident neutron energy range of multi-chance fission

Tudora

Hambsch²,

Tobosaru

2017

EPJ Web Conf.

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Abstract. Prompt neutron multiplicity distributions ν(A) are required for prompt emission correction of double energy (2E) measurements of fission fragments to determine pre-neutron fragment properties. The lack of experimental ν(A) data especially at incident neutron energies (En) where the multi-chance fission occurs impose the use of ν(A) predicted by models. The Point-by-Point model of prompt emission is able to provide the individual ν(A) of the compound nuclei of the main and secondary nucleus chains undergoing fission at a given En. The total ν(A) is obtained by averaging these individual ν(A) over the probabilities of fission chances (expressed as total and partial fission cross-section ratios). An indirect validation of the total ν(A) results is proposed. At high En, above 70 MeV, the PbP results of individual ν(A) of the first few nuclei of the main and secondary nucleus chains exhibit an almost linear increase. This shape is explained by the damping of shell effects entering the super-fluid expression of the level density parameters. They tend to approach the asymptotic values for most of the fragments. This fact leads to a smooth and almost linear increase of fragment excitation energy with the mass number that is reflected in a smooth and almost linear behaviour of ν(A).

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Section: Features Of the Modelingmentioning

confidence: 91%

Section: Features Of the Modelingmentioning

confidence: 99%

Section: Features Of the Modelingmentioning

confidence: 99%

“…Recursive formulae giving the average excitation energies of the fissioning nuclei formed by the 6 ways mentioned above can be found in Ref. [2].…”

Section: Features Of the Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Point-by-point model calculation of the prompt neutron multiplicity distribution ν(A) in the incident neutron energy range of multi-chance fission

Tudora

Hambsch²,

Tobosaru

2017

EPJ Web Conf.

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Prompt and Delayed Emission

et al. 2022

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Physical Models

Корнилов¹

2014

Fission Neutrons

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We selected the process of the Prompt Fission Neutron Spectra (PFNS) analysis into two parts, or separate sections:1. Evaluation on the basis of semiempirical model, which allows us to compare of different experimental data, select wrong results, and give recommendations for data library creation; 2. Development of theoretical models, which first of all are addressed for understanding of the nature of prompt fission neutron (PFN) emission, explanation semiempirical relations, and of course made recommendations for data library, if the theoretical model agrees with experimental data in the whole energy range and for all isotopes. Or provide the recommendation for future experimental efforts, to understand problem and explain the mechanism of neutron emission in fission.This splitting of the problem has very simple explanation: till now we have a problem with theoretical modeling which can predict all sets of experimental data without tuning of model parameters, sometimes outside the reasonable range. The most important data for practical application are the neutron multiplicity as function of input neutron energy for main isotopes, and the shape of the PFNS. Therefore, main attention was paid for investigations of these data; sometimes very important results were outside the attention of models' creators.The German "ansatz" is the best word to define modeling of the neutron emission in fission. An ansatz is the establishment of the starting equation(s), the theorem(s), or the value(s) describing a mathematical or physical problem or solution. It can take into consideration boundary conditions. After an ansatz has been established (constituting nothing more than an assumption), the equations are solved for the general function of interest (constituting a confirmation of the assumption).It is not clear at what time the neutrons are emitted; measured neutron widths at thermal energies, extrapolated to high energies [58], give emission times of the order of 10 −16 s, and an upper limit of 4×10 −14 s has been found from angular correlation measurements. However, the neutron emission times may be considerably shorter; the lower limit must be of the order of 10 −22 s, the time required for a

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Prompt fission neutron multiplicity and spectrum model for 30–80 MeV neutrons incident on 238U

Cited by 31 publications

References 11 publications

Point-by-point model calculation of the prompt neutron multiplicity distribution ν(A) in the incident neutron energy range of multi-chance fission

Point-by-point model calculation of the prompt neutron multiplicity distribution ν(A) in the incident neutron energy range of multi-chance fission

Prompt and Delayed Emission

Physical Models

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