Measurement of the ratio of the236U and235U fission cross sections in the neutron-energy range 0.34?7.4 MeV

Fursov, B. I.; Klemyshev, M. P.; Samylin, B. F.; Smirenkin, G.N.; Turchin, Yu. M.

doi:10.1007/bf01123318

Cited by 5 publications

(7 citation statements)

References 3 publications

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“…Unlike the procedure of [7], in the present experiment, to determine the contribution by the neutrons from the reaction D(d, n) 3 He to the measured quantities, the effect of the accompanying source N D (t k ) was studied first in a wide range of accumulated implanted-ion charge, which made it possible to obtain the information needed in the calculations of this effect for any nuclide, deuteron energy, and accumulated charge of deuterium ions. In the present work, the determining quantity of this effect was the saturation activity A d 0 (ΣQ) arising from the 238 U sample when it is irradiated by a flux of neutrons from the a tritium-free template target bombarded with deuterium ions.…”

Section: Study Of the Effect Of The Secondary Neutron Source D(d N) mentioning

confidence: 99%

Relative yield of delayed neutrons and half-life of their precursor nuclei from 238U fission by 14.2–17.9 MeV neutrons

2007

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The energy dependence of the relative yield of delayed neutrons and half-life of their precursor nuclei from 238 U fission by 14.2-17.9 MeV neutrons is measured. In addition, the detector-blocking effect, which is due to the exposure of the detector to intense fluxes of high-energy neutrons, and the effect of the secondary neutron source D(d, n) 3 He, a reaction which occurs when a T(d, n) 4 He based neutron source is used, are investigated experimentally and taken into account in the data analysis. The data are analyzed in terms of the average half-life of the precursor nuclei of the delayed neutrons. It is shown that the observed increase of with increasing primary-neutron energy in the energy range studied is predominantly due to the opening of emissive nuclear fission channels. The energy dependence of the average half-life of the delayed-neutron precursors can be described on the basis of the model of emissive fission of three nuclei that fission in this energy range -237 U * , 238 U * , and 239 U * .New designs of nuclear reactors, characterized by a complex neutron spectrum and fuel composition and the possibility of being used for transmuting wastes, are given a large role in the development of nuclear power. The operational safety and efficiency of these reactors impose greater requirements on the database for delayed neutrons. However, despite the efforts made to study the emission of delayed neutrons, substantial uncertainties still remain in the nuclear-physical data on delayed neutrons even for the main isotopes -235 U, 238 U, and 239 Pu.Until now, individual sets of the group parameters of delayed neutrons -the relative yield a i of the ith group of delayed neutrons and the half-life T i of the precursor nuclei belonging to the ith group -have been checked by comparing with the corresponding experimental data the dependences obtained for the reactivity from these data on the asymptotic period of the reactor. In [1], this approach was to show on the basis of experiments performed with the UARR research reactor (USA) that the group parameters for 235 U satisfactorily describe the kinetics of the reactor in which the experiments were performed [2]. Specifically, the data for 235 U from [2] make it possible to predict the reactivity of the system to within 3%. At the same time, it was shown that the group parameters for 235 U from the ENDF/B VI library [3] gave values for the reactivity in the range from 0.8β eff to -0.8β eff which are too low by 2-47%.The objective of the present work is to measure the energy dependence of the relative yield of delayed neutrons and of the half-life of their precursor nuclei from 238 U fission by 14.2-17.9 MeV neutrons. Attention is focused on describing the special features of an experiment where the reaction T(d, n) 4 He is used as the neutron source.Experimental Method. The method is based on cyclic irradiation of a fissile sample by neutrons from a target in an accelerator followed by measurement of the time dependence of the intensity of the delayed neutro...

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Section: Study Of the Effect Of The Secondary Neutron Source D(d N) mentioning

confidence: 99%

Relative yield of delayed neutrons and half-life of their precursor nuclei from 238U fission by 14.2–17.9 MeV neutrons

2007

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“…The measured ratio of the neutron-induced fission cross section of 236 U and 235 U is shown in Fig. 17 and compared to some measurements performed by other authors [2][3][4][5][6][8][9][10][11]. Despite the fact that the Lisovski et al data presented in EXFOR are not final, as the authors themselves noted, and were obtained by digitizing points from a figure published in the conference proceedings [9], this data are also presented in the Fig.…”

Section: A Present Measurementsmentioning

confidence: 80%

“…Figure 18 shows the fission cross section of 236 U determined from our ratio data using expression (10) and the standard (below 200 MeV) and recommended (300-1000 MeV) neutron-induced fission cross section of 235 U [14,15], which are also shown. For comparison, the figure also shows the results of earlier works [3,8] and relatively recent measurements [10,11], together with an estimate from the ENDF/B-VIII.0 library [42] (the data from [9] is not shown because there is no information about the measurement errors in this work). All data presented in this figure were determined using the same standard.…”

Section: A Present Measurementsmentioning

confidence: 98%

“…The data available in the literature on the neutroninduced fission cross section of the 236 U were obtained both using beams of quasi-monoenergetic neutrons formed at Van de Graaf accelerators [2][3][4][5][6][7] and neutron sources with a continuous spectrum using the timeof-flight method [8][9][10][11][12]. Most of these data relate to neutrons with energies below 40 MeV, and only in two works [9,11] the incident neutron energy range was expanded to 400 MeV and 200 MeV, respectively.…”

Section: Inroductionmentioning

confidence: 99%

“…Within the total error of the data obtained, which also includes the error in determining the number of nuclei in the targets, there is an agreement between the data of this work and the data of other authors in the entire neutron energy range studied. [3,8,10,11]. The standard (below 200 MeV) [15] and recommended (300-1000 MeV) [14] neutron-induced fission cross section of 235 U are shown in red squares.…”

Section: A Present Measurementsmentioning

confidence: 99%

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Measurement of the $^{236}$U fission cross section and angular distributions of fragments from fission of $^{235}$U and $^{236}$U in neutron energy range of 0.3-500 MeV

Vorobyev¹,

Gagarski²,

Shcherbakov³

et al. 2023

Preprint

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Modelling Neutron-induced Reactions on 232–237U from 10 keV up to 30 MeV

Sin

Capote

Herman

et al. 2017

Nuclear Data Sheets

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Comprehensive calculations of cross sections for neutron-induced reactions on 232−237 U targets are performed in the 10 keV-30 MeV incident energy range with the code EMPIRE-3.2 Malta. The advanced modelling and consistent calculation scheme are aimed at improving our knowledge of the neutron scattering and emission cross sections, and to assess the consistency of available evaluated libraries for light uranium isotopes. The reaction model considers a dispersive optical potential (RIPL 2408) that couples from five (even targets) to nine (odd targets) levels of the groundstate rotational band, and a triple-humped fission barrier with absorption in the wells described within the optical model for fission. A modified Lorentzian model (MLO) of the radiative strength function and Enhanced Generalized Superfluid Model nuclear level densities are used in Hauser-Feschbach calculations of the compound-nuclear decay that include width fluctuation corrections. The starting values for the model parameters are retrieved from RIPL. Excellent agreement with available experimental data for neutron emission and fission is achieved, giving confidence that the quantities for which there is no experimental information are also accurately predicted. Deficiencies in existing evaluated libraries are highlighted.

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Measurement of the ratio of the236U and235U fission cross sections in the neutron-energy range 0.34?7.4 MeV

Cited by 5 publications

References 3 publications

Relative yield of delayed neutrons and half-life of their precursor nuclei from 238U fission by 14.2–17.9 MeV neutrons

Relative yield of delayed neutrons and half-life of their precursor nuclei from 238U fission by 14.2–17.9 MeV neutrons

Measurement of the $^{236}$U fission cross section and angular distributions of fragments from fission of $^{235}$U and $^{236}$U in neutron energy range of 0.3-500 MeV

Modelling Neutron-induced Reactions on 232–237U from 10 keV up to 30 MeV

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