Precision Measurements of Prompt Neutron Spectra in<sup>240</sup>Pu and<sup>242</sup>Pu Spontaneous Fission

Gerasimenko, B. F.; Drapchinsky, L.V.; Kostochkin, O. I.; Kuz’mina, T. E.; Skovorodkin, N.V.; Trenkin, Valery

doi:10.1080/00223131.2002.10875115

Cited by 7 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In reaction 239 Pu(nth,f) neutron yield comes mostly from J  = 0 + states, same as in 240 Pu(sf) spontaneous fission neutron spectra (SFNS). Comparison of PFNS of 239 Pu(nth,f) and SFNS of 240 Pu(sf) [9] in [1] shows that at ε<0.2 MeV PFNS and SFNS of fissioning nuclide 240 Pu depend only weakly on the excitation energy, while at ε≳ E the PFNS of 239 Pu(nth,f) is much harder than SFNS. The same happens in case of calculated 241 Pu(nth,f) PFNS and 242 Pu(sf) [9].…”

Section: Pu(nf) Prompt Fission Neutron Spectramentioning

confidence: 97%

See 1 more Smart Citation

239Pu prompt fission neutron spectra

Maslov

2007

At Energy

View full text Add to dashboard Cite

Calculations of 239 Pu(n, F) prompt fission neutron spectra have been performed for neutron energy up to 20 MeV. The exclusive spectra of pre-fission neutron reactions (n, xnf) were calculated on the basis of the Hauser-Feshbach model simultaneously with the cross sections of (n, F) and (n, 2n) reactions. The spectra of neutrons emitted by fission fragments were approximated by a sum of two Watt distributions. The components of the prompt fission neutron spectra due to pre-fission neutrons are manifested in the prompt fission neutron spectra and the average neutron energy. A correlation is established between this effect in the contribution of emissive fission (n, xnf) in the fission cross-section of 239 Pu(n, F) and 235 U(n, F). It is shown that the 239 Pu(n, F) prompt fission neutron spectra used in applied calculations do not correspond to the experimental differential data and the systematic regularities in the spectra and their average energy found for the most carefully studied nuclei 235,238 U and 232 Th.The prompt fission neutron spectra of actinides have been investigated theoretically and experimentally from the moment the fission process was first discovered [1, 2]. Nevertheless, they have been investigated in detail only for 235 U and 238 U nuclei for neutron energy E n below and above the threshold for emissive fission, when together with the first chance fission reaction (n, f) the emissive fission reaction (n, xnf) with emission of x (≥ 1) neutrons is possible [3,4]. A decrease of the average energy of the spectrum of prompt fission neutrons near the threshold of the second chance fission reaction 235(238) U(n, nf) and the third chance fission reaction 235(238) U(n,2nf) has been investigated in detail experimentally [5,6].Pre-and post-fission neutrons contribute to the observed prompt fission neutron spectra at emissive fission excitation energies. This occurs when the energy E n of the neutrons is higher than E nnf , the threshold of the reaction (n, nf) (≈5-6 MeV). Post-fission prompt neutrons are emitted by primary fission fragments. Analysis of the spectra of prompt neutrons from the reactions 232 Th(n, f), 235 U(n, F), and 238 U(n, f) [here (n, F) denotes the sum of the reactions (n, f) and (n, xnf)] shows that many of their characteristic features can be correlated with the influence of pre-fission neutrons. For example, for E n > E n2nf the step features in the spectra of the prompt neutrons from the reactions 238 U(n, F) and 232 Th(n, F) at energy ε~ 3-5 MeV are due to the first neutron of the reaction (n, 2nf)-(n, 2nf) 1 [7-9]. The characteristic features of the shape of the spectra are also manifested for average energy 〈E〉; they are closely related with the chance (n, xnf) structure of the observed the fission cross-sections. This structure depends on the fissility of the nuclei (A + 1, Z), (A, Z), (A -1, Z), and so on, where (A, Z) is the target nucleus. Small-scale variations of the average energy were predicted for the reaction 232 Th(n, f) near the theshold of the reaction 232 Th(...

show abstract

Section: Pu(nf) Prompt Fission Neutron Spectramentioning

confidence: 97%

“…240 Pu(nth,f) PFNS and SFNS of 240 Pu(sf)[9], the former being harder at ε≳ E . The 239 Pu(n,f) PFNS data at En~1.5 MeV[2] are consistent with hardening of the calculated PFNS with increase of En .…”

mentioning

confidence: 96%

239Pu prompt fission neutron spectra

Maslov

2007

At Energy

View full text Add to dashboard Cite

show abstract

“…In reaction 239 Pu(nth, f) neutrons yield mostly from  J = 0 + states, same as in 240 Pu(sf) spontaneous fission neutron spectra (SFNS). Comparison of PFNS of 239 Pu(nth, f) and SFNS of 240 Pu(sf) [7] in [5,6] shows that at ε<0.2 MeV PFNS and SFNS of fissioning nuclide 240 Pu depend only weakly on the excitation energy, while at ε≳ E the PFNS of 239 Pu(nth, f) is much harder than SFNS of 240 Pu(sf). The same happens in case of calculated 241 Pu(nth, f) PFNS and measured SFNS of 242 Pu(sf) [7].…”

Section: Introductionmentioning

confidence: 99%

“…Comparison of PFNS of 239 Pu(nth, f) and SFNS of 240 Pu(sf) [7] in [5,6] shows that at ε<0.2 MeV PFNS and SFNS of fissioning nuclide 240 Pu depend only weakly on the excitation energy, while at ε≳ E the PFNS of 239 Pu(nth, f) is much harder than SFNS of 240 Pu(sf). The same happens in case of calculated 241 Pu(nth, f) PFNS and measured SFNS of 242 Pu(sf) [7]. For a pair of reactions 240 Pu(nth, f)& 241 Pu(sf) such augmentation is hardly would be ever possible, though some guidance stems from comparing a pair of spectra of 240 Pu(nth, f)& 240 Pu(sf).…”

Section: Introductionmentioning

confidence: 99%

U, Np, Pu & Am Prompt Fission Neutron Spectra

Maslov¹,

Demetriou²,

Julin³

et al. 2008

AIP Conference Proceedings

View full text Add to dashboard Cite

Prompt fission γ-rays are responsible for approximately 5% of the total energy released in fission, and therefore important to understand when modelling nuclear reactors. In this work we present prompt γ-ray emission characteristics in fission, for the first time as a function of the nuclear excita-tion energy of the fissioning system. Emitted γ-ray spectra were measured, and γ-ray multiplicities and average and total γ energies per fission were determined for the 233 U(d,pf) reaction for excita-tion energies between 4.8 and 10 MeV, and for the 239 Pu(d,pf) reaction between 4.5 and 9 MeV. The spectral characteristics show no significant change as a function of excitation energy above the fission barrier, despite the fact that an extra ∼5 MeV of energy is potentially available in the excited fragments for γ-decay. The measured results are compared to model calculations made for prompt γ-ray emission with the fission model code GEF. Further comparison with previously obtained results from thermal neutron induced fission is made to characterize possible differences arising from using the surrogate (d,p) reaction. PACS numbers: 25.85.Ge 24.75.+i 07.85.Nc

show abstract

“…The parameters of some nuclides are presented in the Tables 2 and 3 in comparison with [17][18][19]. Neutron spectral measurements have been reported [6] for two mixtures, one contains 227 AcO2 with daughter products and the second contains dioxide 244 CmO2 mixed with 13 C powder target material and [7] for 210 Po- 13 C source of neutrons .…”

Section: Icrs-13 and Rpsd-2016 7033mentioning

confidence: 99%

Calculation of Neutron Production Rates and Spectra from Compounds of Actinides and Light Elements

Vlaskin¹,

Khomiakov²

2017

EPJ Web Conf.

View full text Add to dashboard Cite

show abstract

Precision Measurements of Prompt Neutron Spectra in²⁴⁰Pu and²⁴²Pu Spontaneous Fission

Cited by 7 publications

References 8 publications

239Pu prompt fission neutron spectra

239Pu prompt fission neutron spectra

U, Np, Pu & Am Prompt Fission Neutron Spectra

Calculation of Neutron Production Rates and Spectra from Compounds of Actinides and Light Elements

Contact Info

Product

Resources

About

Precision Measurements of Prompt Neutron Spectra in240Pu and242Pu Spontaneous Fission

Cited by 7 publications

References 8 publications

239Pu prompt fission neutron spectra

239Pu prompt fission neutron spectra

U, Np, Pu & Am Prompt Fission Neutron Spectra

Calculation of Neutron Production Rates and Spectra from Compounds of Actinides and Light Elements

Contact Info

Product

Resources

About

Precision Measurements of Prompt Neutron Spectra in²⁴⁰Pu and²⁴²Pu Spontaneous Fission