Measurement of the total neutron cross sections and resonance parameters of243Cm in the 0.4-66-eV energy region

Anufriev, V. A.; Babich, S. I.; Kocherygin, N. G.; Лебедев, В. М.; Никольский, С. Н.; Nefedov, V. N.; Nikolaev, V. M.; Poruchikov, V. A.; Elesin, A.A.

doi:10.1007/bf01135898

Cited by 8 publications

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“…The resonance absorption integral (1770 ± 300 b) was obtained in [7] by the method of summing over individual resonances in the total cross section. It follows from here, relying on the estimates of the average widths Γ ƒ and Γ γ , that I ƒ = 1585 ± 270 b for E 1 = 0.5 eV.…”

Section: The Model Function E(t) Depends On the Time As [10]mentioning

confidence: 99%

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243Cm neutron fission cross section

et al. 2009

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The neutron fission cross section of 243 Cm for neutron energies 0.03 eV -20 keV is measured with a neutron spectrometer at the Institute for Nuclear Research of the Russian Academy of Sciences on the basis of the moderation time in lead . The values of the resonance fission integral and the Westcott factor g(T) are obtained. A comparison is made with existing data and recommended values. A new evaluation of the fission cross section for thermal neutrons is made.Transuranium isotopes (Np, Am, Cm) play an important role in the transmutation of nuclear wastes by means of reactor and accelerator technologies [1,2]. The fission of nuclei by low-and medium-energy neutrons is a basic process of transmutation. For this reason, an experimental problem given priority status is measuring the cross sections of stimulated fission of Np, Am, and Cm. The difficulties arising in performing measurements are due to the high α activity of the nuclei being studied and the need to use targets with a small amount of material and high-intensity neutron sources. In the present work, we have studied the fission cross section of 243 Cm(n, ƒ) for neutron energies in the resonance region (below 20 keV).The fission cross section of 243 Cm in this energy range (E > 15 eV) was previously studied only in a single experiment with a one-time action pulsed neutron source (bomb explosion, time-of-flight method with a 240 m baseline) at Los Alamos [3]. The fission events were measured by detecting fission fragments. The cross sections of the reactions 6 Li(n, t) and 235 U(n, ƒ) were used to monitor the neutron flux. The 243 Cm layer investigated contained an 11% admixture of 244 Cm impurity nuclei. The error in the values obtained for the fission cross sections (taking account of normalization) is no better than 10%.The thermal-neutron (E 0 = 0.0253 eV) fission cross section of 244 Cm (σ 0 ) was measured in two experiments performed in reactor spectra: σ 0 = 609.6 ± 25.9 b (neutron spectrum temperature 323 K) in the first [4] and σ 0 = 672 ± 60 b (T = 353 K) in the second [5]. The ENDF/BVII recommended value is σ 0 = 620.3 b [6], which is the weighted-mean of the measured values. However, it neglected a 5% systematic error in the data given in [4].The ENDF/BVII estimate assumes that the experimental neutron-energy E n range (10 -5 eV -20 MeV) is divided into two regions. In the first region E n ≤ 100 eV, the reaction cross section is a superposition of the contributions of isolated resonances. One-hundred five separate s resonances with spins J π = 2 + , 3 + were identified for the intermediate system 243 Cm + n. The average distance between the resonances is D(2 + ) = 1.565 eV and D(3 + ) = 1.199 eV. The average fission width is Γ ƒ = 334.8 meV with variance 196 meV. The radiative width Γ γ is assumed to be the same for all resonances and

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Section: The Model Function E(t) Depends On the Time As [10]mentioning

confidence: 99%

“…The evaluation of the parameters of the low resonances relies on the data on the total neutron cross section measured by means of the time-of-flight technique and a mechanical selector of neutrons in the beam of a SM-2 reactor (Research Institute of Nuclear Reactors) [7]. The average neutron width is Γ n = 1.555 ± 1.692 meV (Γ n 0 = 0.2446 ± 0.2599 meV).…”

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confidence: 99%