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Journal Articles

CIELO collaboration summary results; International evaluations of neutron reactions on uranium, plutonium, iron, oxygen and hydrogen

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Kahler, A. C.*; Talou, P.*; Plompen, A. J.*; Schillebeeckx, P.*; et al.

Nuclear Data Sheets, 148, p.189 - 213, 2018/02

 Times Cited Count:8 Percentile:4(Physics, Nuclear)

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear facilities - $$^{235}$$U, $$^{238}$$U, $$^{239}$$Pu, $$^{56}$$Fe, $$^{16}$$O and $$^{1}$$H - with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality. This report summarizes our results and outlines plans for the next phase of this collaboration.

Journal Articles

Inter-comparison of Hauser-Feshbach model codes toward better actinide evaluations

Capote, R.*; Hilaire, S.*; Iwamoto, Osamu; Kawano, Toshihiko*; Sin, M.*

EPJ Web of Conferences (Internet), 146, p.12034_1 - 12034_4, 2017/09

 Percentile:100

Journal Articles

The CIELO collaboration; Progress in international evaluations of neutron reactions on Oxygen, Iron, Uranium and Plutonium

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Kahler, A. C.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Pigni, M.*; Dunn, M.*; Leal, L.*; et al.

EPJ Web of Conferences (Internet), 146, p.02001_1 - 02001_9, 2017/09

 Times Cited Count:4 Percentile:0.6

The CIELO collaboration has studied neutron cross sections on nuclides ($$^{16}$$O, $$^{56}$$Fe, $$^{235,238}$$U and $$^{239}$$Pu) that significantly impact criticality in nuclear technologies with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

Journal Articles

A New evaluation of the neutron data standards

Carlson, A. D.*; Pronyaev, V.*; Hale, G. M.*; Zhenpeng, C.*; Capote, R.*; Dur$'a$n, I.*; Hambsch, F.-J.*; Kawano, Toshihiko*; Kunieda, Satoshi; 13 of others*

EPJ Web of Conferences (Internet), 146, p.02025_1 - 02025_4, 2017/09

 Times Cited Count:3 Percentile:1.43

Evaluations are being done for the $$^1$$H(n,n), $$^6$$Li(n,t), $$^{10}$$B(n,$$alphagamma$$), $$^{10}$$B(n,$$alpha$$), C(n,n), $$^{197}$$Au(n,$$gamma$$), $$^{235}$$U(n,f) and $$^{238}$$U(n,f) standard cross sections. Evaluations are also being done for data that are not traditional standards including: the Au(n,$$gamma$$) cross section at energies below where it is considered a standard; reference cross sections for prompt $$gamma$$-ray production in fast neutron-induced reactions; reference cross sections for very high energy fission cross sections; the $$^{235}$$U thermal neutron fission spectrum and the $$^{252}$$Cf spontaneous fission neutron spectrum and the thermal constants.

Journal Articles

The CIELO Collaboration; Neutron reactions on $$^1$$H, $$^{16}$$O, $$^{56}$$Fe, $$^{235,238}$$U, and $$^{239}$$Pu

Chadwick, M. B.*; Dupont, E.*; Bauge, E.*; Blokhin, A.*; Bouland, O.*; Brown, D. A.*; Capote, R.*; Carlson, A. D.*; Danon, Y.*; De Saint Jean, C.*; et al.

Nuclear Data Sheets, 118, p.1 - 25, 2014/04

 Times Cited Count:75 Percentile:0.97(Physics, Nuclear)

CIELO (Collaborative International Evaluated Library Organization) provides a new working paradigm to facilitate evaluated nuclear reaction data advances. It brings together experts from across the international nuclear reaction data community to identify and document discrepancies among existing evaluated data libraries, measured data, and model calculation interpretations, and aims to make progress in reconciling these discrepancies to create more accurate ENDF-formatted files. The focus will initially be on a small number of the highest-priority isotopes, namely $$^{1}$$H, $$^{16}$$O, $$^{56}$$Fe, $$^{235,238}$$U, and $$^{239}$$Pu. This paper identifies discrepancies between various evaluations of the highest priority isotopes. The evaluated data for these materials in the existing nuclear data libraries are reviewed, and some integral properties are given. The paper summarizes a program of nuclear science and computational work needed to create the new CIELO nuclear data evaluations.

Journal Articles

ENDF/B-VII.1 nuclear data for science and technology; Cross sections, covariances, fission product yields and decay data

Chadwick, M. B.*; Herman, M.*; Oblo$v{z}$insk$'y$, P.*; Dunn, M. E.*; Danon, Y.*; Kahler, A. C.*; Smith, D. L.*; Pritychenko, B.*; Arbanas, G.*; Arcilla, R.*; et al.

Nuclear Data Sheets, 112(12), p.2887 - 2996, 2011/12

 Times Cited Count:1155 Percentile:0.01(Physics, Nuclear)

The ENDF/B-VII.1 library is our latest recommended evaluated nuclear data file for use in nuclear science and technology applications, and incorporates advances made in the five years since the release of ENDF/B-VII.0. These advances focus on neutron cross sections, covariances, fission product yields and decay data, and represent work by the US Cross Section Evaluation Working Group (CSEWG) in nuclear data evaluation that utilizes developments in nuclear theory, modeling, simulation, and experiment. It features extension of covered nuclei, covariance data for 190 nuclei, R-matrix analyses of neutron reactions on light nuclei, updates for some medium-heavy and actinoid nuclei, etc. Criticality benchmark tests with a transport simulation code MCNP shows improved performances.

Journal Articles

Evaluation and use of the prompt fission neutron spectrum and spectra covariance matrices in criticality and shielding

Kodeli, I.*; Trkov, A.*; Capote, R.*; Nagaya, Yasunobu; Maslov, V.*

Nuclear Instruments and Methods in Physics Research A, 610(2), p.540 - 552, 2009/11

 Times Cited Count:22 Percentile:12.32(Instruments & Instrumentation)

The prompt fission neutron spectra covariance matrices of $$^{235}$$U, $$^{238}$$U and $$^{239}$$Pu were evaluated using the Monte Carlo method for two empirical spectra formulations, Watt and Kornilov, and compared to the existing evaluations such as JENDL-3.3. The fission spectra, together with the covariance matrices and the methods for the calculation of the corresponding sensitivity profiles were validated on several applications, including shielding (VENUS-3 benchmark, pressure vessel dosimetry) as well as on fast and thermal reactor systems (KRITZ and SNEAK critical experiments). A new set of parameters for a Kornilov model is proposed that improve both benchmark performance and the agreement with recently measured differential spectra. A recommendation to use constrained sensitivity coefficients was confirmed for the case of the fission spectrum induced uncertainty in the effective multiplication factor and in the detector responses, in order to assure the proper normalisation of the corresponding covariance matrices.

Journal Articles

A Dispersive, lane-consistent coupled-channel optical model based on soft-rotator theory for accurate calculation of nuclear reaction data

Chiba, Satoshi; Soukhovitski, E. Sh.*; Capote, R.*; Quesada, J.*

Proceedings of 2009 International Congress on Advances in Nuclear Power Plants (ICAPP '09) (CD-ROM), p.9172_1 - 9172_7, 2009/05

Coupled-channels optical model code OPTMAN is widely applied to analyze experimental nucleon-nucleus interaction data. Sophisticated dispersive optical potential forms had been included in the code along with the possibility to calculate direct excitations of isobar analog states in (p,n) reactions. The latter along with accounting of the proton "effective" energy decrease due to Coulomb repulsion by nuclei, leads to full Lane-consistent optical potential. Such approach had been successfully applied to nucleon-nucleus interaction reaction analyses of experimental data for several nuclei up to 200 MeV incident energies.

JAEA Reports

Supplement to OPTMAN code, Manual version 10 (2008)

Soukhovitski, E.*; Chiba, Satoshi; Capote, R.*; Quesada, J.*; Kunieda, Satoshi; Morogovskij, G.*

JAEA-Data/Code 2008-025, 55 Pages, 2008/12

JAEA-Data-Code-2008-025.pdf:1.8MB

A coupled-channel code to calculate nuclear cross sections, OPTMAN, has been improved after OPTMAN version 8 was published as JAERI-Data/Code 2005-002. The most important addition is the inclusion of dispersive relationships between imaginary and real parts of the optical potential within a Lane consistent formalism. The obtained CCOM potentials allow for the description of nucleon induced reactions up to 200 MeV, including (p,n) reactions with excitation of isobaric analog states. Relativistic corrections consistent with those used in the ECIS06 code are also added.

Journal Articles

A Global dispersive coupled-channel optical model potential for actinides

Capote, R.*; Chiba, Satoshi; Soukhovitskij, E. Sh.*; Quesada, J. M.*; Bauge, E.*

Journal of Nuclear Science and Technology, 45(4), p.333 - 340, 2008/04

 Times Cited Count:35 Percentile:5.98(Nuclear Science & Technology)

A global dispersive coupled-channel optical model (DCCOM) potential is proposed to describe neutron and proton interactions with actinide nuclei at 0.001 to 200 MeV range. A linear dependence of the geometrical parameters on mass number $$A$$ is employed, and deformation parameters are adjusted for each nucleus to extend the DCCOM determined previously for $$^{238}$$U and $$^{232}$$Th to neighboring nuclei, $$^{241}$$Am, $$^{242,240,239}$$Pu and $$^{235,233}$$U. Fitted deformations are in reasonable agreement with those derived theoretically. The present DCCOM is capable of describing not only the cross sections but also the total cross section differences between $$^{232}$$Th and $$^{238}$$U up to 200 MeV within experimental uncertainty, verifying that the isovector potential and assumed geometrical parameters are adequate to describe the minute difference of the cross sections of actinide nuclei and its energy dependence.

Journal Articles

Approximate Lane consistency of the dispersive coupled-channel potential for actinides

Quesada, J. M.*; Capote, R.*; Soukhovitskii, E. Sh.*; Chiba, Satoshi

Physical Review C, 76(5), p.057602_1 - 057602_3, 2007/11

 Times Cited Count:17 Percentile:22.43(Physics, Nuclear)

A previously derived dispersive coupled-channel optical model potential for nucleon scattering on $$^{232}$$Th and $$^{238}$$U nuclei has been challenged against experimental data on quasi-elastic ($$p,n$$) scattering to the isobaric analog states of corresponding target nuclei. The Lane potential derived from the isovector term of the dispersive coupled-channel optical model potential has been shown to approximately reproduce available experimental differential cross-section data for the quasi-elastic ($$p,n$$) reaction; therefore the approximated Lane consistency of that potential has been established.

Journal Articles

Angular distributions of protons scattered by $$^{40}$$Ar nuclei with excitation of the 2$$^{+}$$ (1.46 MeV) and 3$$^{-}$$ (3.68 MeV) collective levels for incident energies of 25.1, 32.5, and 40.7 MeV

Okumusoglu, N. T.*; Gorur, F. K.*; Birchall, J.*; Soukhovitskij, E. Sh.*; Capote, R.*; Quesada, J. M.*; Chiba, Satoshi

Physical Review C, 75(3), p.034616_1 - 034616_10, 2007/03

 Times Cited Count:3 Percentile:66.77(Physics, Nuclear)

Elastic and inelastic scattering of unpolarized and polarized protons by $$^{40}$$Ar nuclei for incident energies between 20 and 50 MeV has been studied by reanalyzing experimental scattering spectra for the 2$$^{+}$$ (1.46 MeV) and 3$$^{-}$$ (3.68 MeV) levels in the angular range 30$$^{circ}$$ - 160$$^{circ}$$ for incident protons of energies of 25.1, 32.5, and 40.7 MeV. An isospin dependent soft-rotator coupled channels optical model with the potential containing a dispersive term with a nonlocal contribution is used to analyze the data.

Journal Articles

Measurement of the neutron capture cross section of the $$s$$-only isotope $$^{204}$$Pb from 1 eV to 440 keV

Domingo-Pardo, C.*; Abbondanno, U.*; Aerts, G.*; $'A$lvarez, H.*; Alvarez-Velarde, F.*; Andriamonje, S.*; Andrzejewski, J.*; Assimakopoulos, P.*; Audouin, L.*; Badurek, G.*; et al.

Physical Review C, 75(1), p.015806_1 - 015806_9, 2007/01

 Times Cited Count:27 Percentile:13.21(Physics, Nuclear)

The neutron capture cross section of $$^{204}$$Pb has been measured at the CERN n_TOF installation with high resolution in the energy range from 1 eV to 440 keV. In the interval between 100 keV and 440 keV we report the average cross section. The background in the entire energy range was reliably determined from the measurement of a $$^{208}$$Pb sample. We obtain a Maxwellian average capture cross section for $$^{204}$$Pb at $$kT$$ = 30 keV of 79(3) mb, in agreement with previous experiments. However our cross section at $$kT$$ = 5 keV is about 35 % larger than the values reported so far. The implications of the new cross section for the $$s$$-process abundance contributions in the Pb/Bi region are discussed.

Journal Articles

Resonance capture cross section of $$^{207}$$Pb

Domingo-Pardo, C.*; Abbondanno, U.*; Aerts, G.*; $'A$lvarez, H.*; Alvarez-Velarde, F.*; Andriamonje, S.*; Andrzejewski, J.*; Assimakopoulos, P.*; Audouin, L.*; Badurek, G.*; et al.

Physical Review C, 74(5), p.055802_1 - 055802_6, 2006/11

 Times Cited Count:20 Percentile:20.91(Physics, Nuclear)

The radiative neutron capture cross section of $$^{207}$$Pb has been measured at the CERN n_TOF facility using the pulse height weighting technique in the resoleved region. The measurement has been performed with an optimized setup of two $$C_{6}D_{6}$$ scintillation detectors, which allowed us to reduce scattered neutron backgrounds down to a negligible level. Resonance parameters have been determined for 16 resonances by means of an R-matrix analysis in the neutron energy range from 3 keV to 320 keV. Good agreement with previous measurements was found at low neutron energies, whereas substantial discrepancies appear beyond 45 keV. With the present results, we obtain an s-process contribution of 77$$pm$$8 % to the solar abundance of $$^{207}$$Pb.

Journal Articles

New measurement of neutron capture resonances in $$^{209}$$Bi

Domingo-Pardo, C.*; Abbondanno, U.*; Aerts, G.*; $'A$lvarez, H.*; Alvarez-Velarde, F.*; Andriamonje, S.*; Andrzejewski, J.*; Assimakopoulos, P.*; Audouin, L.*; Badurek, G.*; et al.

Physical Review C, 74(2), p.025807_1 - 025807_10, 2006/08

 Times Cited Count:30 Percentile:13.18(Physics, Nuclear)

The neutron capture cross section of $$^{209}$$Bi has been measured at the CERN n_TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which led to a practically negligible neutron sensitivity. Because $$^{209}$$Bi is the last stable isotope in the reaction path of the stellar s-process, the Maxwellian averaged capture cross section is important for the recycling of the reaction flow by alpha decays. In the relevant stellar range of thermal energies between $$kT$$ = 5 and 8 keV our new capture rate is about 16% higher than the presently accepted value used for nucleosynthesis calculations. The present cross section measurement is also of relevance for the design of accelerator driven systems based on a liquid metal Pb/Bi spallation target.

Journal Articles

Neutron capture cross section of $$^{232}$$Th measured at the n_TOF facility at CERN in the unresolved resonance region up to 1 MeV

Aerts, G.*; Abbondanno, U.*; $'A$lvarez, H.*; Alvarez-Velarde, F.*; Andriamonje, S.*; Andrzejewski, J.*; Assimakopoulos, P.*; Audouin, L.*; Badurek, G.*; Baumann, P.*; et al.

Physical Review C, 73(5), p.054610_1 - 054610_10, 2006/05

We have measured the neutron capture reaction yield of $$^{232}$$Th at the neutron tim-of-flight facility n_TOF at CERN in the energy range from 1 eV to 1 MeV. The average capture cross section has been extracted in the energy range from 4 keV up to 1 MeV with an overall accuracy better than 4 %. An independent IAEA evaluation shows good agreement with the data.

Journal Articles

Neutron capture cross section of $$^{232}$$Th measured at the n_TOF facility at CERN in the unresolved resonance region up to 1 MeV

Aerts, G.*; Abbondanno, U.*; $'A$lvarez, H.*; Alvarez-Velarde, F.*; Andriamonje, S.*; Andrzejewski, J.*; Assimakopoulos, P.*; Audouin, L.*; Badurek, G.*; Baumann, P.*; et al.

Physical Review C, 73(5), p.054610_1 - 054610_10, 2006/05

 Times Cited Count:37 Percentile:9.99(Physics, Nuclear)

We have measured the neutron capture reaction yield of $$^{232}$$Th at the neutron time-of-flight facility n_TOF at CERN in the energy range from 1 eV to 1 MeV. The average capture cross section has been extracted in the energy range from 4 keV up to 1 MeV with an overall accuracy better than 4%. An independent IAEA evaluation shows good agreement with the data.

Journal Articles

Measurement of the resonance capture cross section of $$^{204,206}$$Pb and termination of the $$s$$-process

Domingo-Pardo, C.*; O'Brien, S.*; Abbondanno, U.*; Aerts, G.*; $'A$lvarez, H.*; Alvarez-Velarde, F.*; Andriamonje, S.*; Andrzejewski, J.*; Assimakopoulos, P.*; Audouin, L.*; et al.

AIP Conference Proceedings 819, p.288 - 292, 2006/03

The neutron capture cross sections of $$^{204}$$Pb and $$^{206}$$Pb have been measured at the CERN n_TOF installation using the time of flight method with the pulse height weighting technique. In a preliminary analysis of $$^{204}$$Pb we have determined by first time the capture cross sections for two strong $$s$$-wave resonances below 2.5 keV. In $$^{206}$$Pb we have determined capture cross sections for a large number of resonances, which were not reported in the two previous capture measurements. We discuss preliminary implications of the new cross sections in the stellar nucleosynthesis of the Pb isotopes.

Journal Articles

Measurement of $$^{139}$$La($$n$$,$$gamma$$) cross section

Terlizzi, R.*; Abbondanno, U.*; Aerts, G.*; $'A$lvarez, H.*; Alvarez-Velarde, F.*; Andriamonje, S.*; Andrzejewski, J.*; Assimakopoulos, P.*; Audouin, L.*; Badurek, G.*; et al.

AIP Conference Proceedings 819, p.283 - 287, 2006/03

We measured the neutron capture cross section of $$^{139}$$La relative to $$^{197}$$Au in the energy range of 0.6 eV to 9 keV at n_TOF, the neutron time-of-flight facility at CERN. The data were fitted using R-matrix formalism to extract resonance parameters which were used to calculate average level spacings. The data were used to determine Maxwellian-averaged neutron capture cross sections which, in turn, were used to calculate the $$^{139}$$La abundance synthesized in a steller model of the main component of the $$s$$ process.

Journal Articles

Neutron cross section measurements at n-TOF for ADS related studies

Mastinu, P. F.*; Abbondanno, U.*; Aerts, G.*; $'A$lvarez, H.*; Alvarez-Velarde, F.*; Andriamonje, S.*; Andrzejewski, J.*; Assimakopoulos, P.*; Audouin, L.*; Badurek, G.*; et al.

Journal of Physics; Conference Series, 41, p.352 - 360, 2006/00

A neutron Time-of-Flight facility (n_TOF) is operative at CERN since 2001. The innovative features of the neutron beam, in particular the high instantaneous flux, the wide energy range, the high resolution and the low background, makes this facility unique for measurements of neutron induced reactions relevant to the field of Emerging Nuclear Technologies, as well as to Nuclear Astrophysics and fundamental Nuclear Physics. The scientific motivations that have led to the construction of this new facility are here presented.

24 (Records 1-20 displayed on this page)