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n_TOF Collaboration (Stamatopoulos, A. et al); Domingo-Pardo, C.; Tain, J.L.; Tarifeño-Saldivia, A. |
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Title |
Investigation of the Pu-240(n, f) reaction at the n_TOF/EAR2 facility in the 9 meV-6 MeV range |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
102 |
Issue |
1 |
Pages |
014616 - 23pp |
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Abstract |
Background: Nuclear waste management is considered amongst the major challenges in the field of nuclear energy. A possible means of addressing this issue is waste transmutation in advanced nuclear systems, whose operation requires a fast neutron spectrum. In this regard, the accurate knowledge of neutron-induced reaction cross sections of several (minor) actinide isotopes is essential for design optimization and improvement of safety margins of such systems. One such case is Pu-240, due to its accumulation in spent nuclear fuel of thermal reactors and its usage in fast reactor fuel. The measurement of the Pu-240(n, f) cross section was previously attempted at the CERN nTOF facility EAR1 measuring station using the time-of-flight technique. Due to the low amount of available material and the given flux at EAR1, the measurement had to last several months to achieve a sufficient statistical accuracy. This long duration led to detector deterioration due to the prolonged exposure to the high alpha activity of the fission foils, therefore the measurement could not be successfully completed. Purpose: It is aimed to determine whether it is feasible to study neutron-induced fission at nTOF/EAR2 and provide data on the Pu-240(n, f) reaction in energy regions requested for applications. Methods: The study of the Pu-240(n, f) reaction was made at a new experimental area (EAR2) with a shorter flight path which delivered on average 30 times higher flux at fast neutron energies. This enabled the measurement to be performed much faster, thus limiting the exposure of the detectors to the intrinsic activity of the fission foils. The experimental setup was based on microbulk Micromegas detectors and the time-of-flight data were analyzed with an optimized pulse-shape analysis algorithm. Special attention was dedicated to the estimation of the non-negligible counting loss corrections with the development of a new methodology, and other corrections were estimated via Monte Carlo simulations of the experimental setup. Results: This new measurement of the Pu-240(n, f) cross section yielded data from 9 meV up to 6 MeV incident neutron energy and fission resonance kernels were extracted up to 10 keV. Conclusions: Neutron-induced fission of high activity samples can be successfully studied at the n_TOF/EAR2 facility at CERN covering a wide range of neutron energies, from thermal to a few MeV. |
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Address |
[Stamatopoulos, A.; Tsinganis, A.; Kokkoris, M.; Vlastou, R.; Diakaki, M.] Natl Tech Univ Athens, Athens, Greece, Email: athanasios.stamatopoulos@cern.ch |
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Amer Physical Soc |
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English |
Summary Language |
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Series Volume |
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ISSN |
0556-2813 |
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Conference |
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Notes |
WOS:000551057500002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4466 |
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Author |
n_TOF Collaboration (Sosnin, N.V. et al.); Babiano-Suarez, V.; Caballero, L.; Domingo-Pardo, C.; Ladarescu, I.; Tain, J.L. |
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Title |
Measurement of the 77Se(n,gamma) cross section up to 200 keV at the n_TOF facility at CERN |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
107 |
Issue |
6 |
Pages |
065805 - 9pp |
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Keywords |
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Abstract |
The 77Se(n,gamma) reaction is of importance for 77Se abundance during the slow neutron capture process in massive stars. We have performed a new measurement of the 77Se radiative neutron capture cross section at the Neutron Time-of-Flight facility at CERN. Resonance capture kernels were derived up to 51 keV and cross sections up to 200 keV. Maxwellian-averaged cross sections were calculated for stellar temperatures between kT = 5 keV and kT = 100 keV, with uncertainties between 4.2% and 5.7%. Our results lead to substantial decreases of 14% and 19% in 77Se abundances produced through the slow neutron capture process in selected stellar models of 15M0 and 2M0, respectively, compared to using previous recommendation of the cross section. |
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Address |
[V. Sosnin, N.; Lederer-Woods, C.; Garg, R.; Dietz, M.; Murphy, A. St. J.; Lonsdale, S.; Woods, P. J.] Univ Edinburgh, Sch Phys & Astron, Edinburgh, Scotland, Email: nsosnin@ed.ac.uk |
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Amer Physical Soc |
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English |
Summary Language |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9985 |
ISBN |
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Conference |
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Notes |
WOS:001023903800002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5599 |
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Author |
n_TOF Collaboration (Patronis, N. et al); Babiano-Suarez, V.; Balibrea Correa, J.; Domingo-Pardo, C.; Ladarescu, I.; Lerendegui-Marco, J. |
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Title |
Status report of the n_TOF facility after the 2nd CERN long shutdown period |
Type |
Journal Article |
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Year |
2023 |
Publication |
EPJ Techniques and Instrumentation |
Abbreviated Journal |
EPJ Tech. Instrum. |
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Volume |
10 |
Issue |
1 |
Pages |
13 - 10pp |
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Keywords |
Neutron time of flight; Spallation target; Nuclear astrophysics; Neutron physics; Neutron induced fission; Neutron reactions |
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Abstract |
During the second long shutdown period of the CERN accelerator complex (LS2, 2019-2021), several upgrade activities took place at the nTOF facility. The most important have been the replacement of the spallation target with a next generation nitrogen-cooled lead target. Additionally, a new experimental area, at a very short distance from the target assembly (the NEAR Station) was established. In this paper, the core commissioning actions of the new installations are described. The improvement in the nTOF infrastructure was accompanied by several detector development projects. All these upgrade actions are discussed, focusing mostly on the future perspectives of the n_TOF facility. Furthermore, some indicative current and future measurements are briefly reported. |
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Address |
[Patronis, N.; Goula, S.; Eleme, Z.; Stamati, M. E.; Vagena, E.] Univ Ioannina, Ioannina, Greece, Email: nikolaos.patronis@cern.ch |
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Publisher |
Springer |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Edition |
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ISSN |
2195-7045 |
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Notes |
WOS:001008786600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5591 |
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Author |
n_TOF Collaboration (Moreno-Soto, J. et al); Babiano-Suarez, V.; Caballero-Ontanaya, L.; Domingo-Pardo, C.; Ladarescu, I.; Tain, J.L. |
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Title |
Constraints on the dipole photon strength for the odd uranium isotopes |
Type |
Journal Article |
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Year |
2022 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
105 |
Issue |
2 |
Pages |
024618 - 14pp |
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Keywords |
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Abstract |
Background: The photon strength functions (PSFs) and nuclear level density (NLD) are key ingredients for calculation of the photon interaction with nuclei, in particular the reaction cross sections. These cross sections are important especially in nuclear astrophysics and in the development of advanced nuclear technologies. Purpose: The role of the scissors mode in the M1 PSF of (well-deformed) actinides was investigated by several experimental techniques. The analyses of different experiments result in significant differences, especially on the strength of the mode. The shape of the low-energy tail of the giant electric dipole resonance is uncertain as well. In particular, some works proposed a presence of the E1 pygmy resonance just above 7 MeV. Because of these inconsistencies additional information on PSFs in this region is of great interest. Methods: The gamma-ray spectra from neutron-capture reactions on the U-234, U-236, and U-238 nuclei have been measured with the total absorption calorimeter of the n_TOF facility at CERN. The background-corrected sum-energy and multi-step-cascade spectra were extracted for several isolated s-wave resonances up to about 140 eV. Results: The experimental spectra were compared to statistical model predictions coming from a large selection of models of photon strength functions and nuclear level density. No combination of PSF and NLD models from literature is able to globally describe our spectra. After extensive search we were able to find model combinations with modified generalized Lorentzian (MGLO) E1 PSF, which match the experimental spectra as well as the total radiative widths. Conclusions: The constant temperature energy dependence is favored for a NLD. The tail of giant electric dipole resonance is well described by the MGLO model of the E1 PSF with no hint of pygmy resonance. The M1 PSF must contain a very strong, relatively wide, and likely double-resonance scissors mode. The mode is responsible for about a half of the total radiative width of neutron resonances and significantly affects the radiative cross section. |
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Address |
[Moreno-Soto, J.; Berthoumieux, E.; Dupont, E.; Gunsing, F.; Bacak, M.] Univ Paris Saclay, CEA Irfu, F-91191 Gif Sur Yvette, France, Email: jmoreno53@us.es; |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9985 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000810791100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5278 |
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Author |
n_TOF Collaboration (Michalopoulou, V. et al); Babiano-Suarez, V.; Caballero, L.; Domingo-Pardo, C.; Ladarescu, I.; Tain, J.L. |
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Title |
Measurement of the neutron-induced fission cross section of Th-230 at the CERN n_TOF facility |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
108 |
Issue |
1 |
Pages |
014616 - 15pp |
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Keywords |
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Abstract |
The neutron-induced fission cross section of Th-230 has been measured at the neutron time-of-flight facility n_TOF located at CERN. The experiment was performed at the experimental area EAR-1 with a neutron flight path of 185 m, using Micromegas detectors for the detection of the fission fragments. The Th-230(n, f ) cross section was determined relative to the U-235(n, f ) one, covering the energy range from the fission threshold up to 400 MeV. The results from the present work are compared with existing cross-section datasets and the observed discrepancies are discussed and analyzed. Finally, using the code EMPIRE 3.2.3 a theoretical study, based on the statistical model, was performed leading to a satisfactory reproduction of the experimental results with the proper tuning of the respective parameters, while for incident neutron energy beyond 200 MeV the fission of( 230)Th was described by Monte Carlo simulations. |
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Address |
[Michalopoulou, V; Stamatopoulos, A.; Diakaki, M.; Vlastou, R.; Kokkoris, M.; Tassan-Got, L.] Natl Tech Univ Athens, Dept Phys, Zografou Campus, Athens, Greece, Email: veatriki.michalopoulou@cern.ch |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9985 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001063908000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5700 |
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