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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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Keywords |
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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 |
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ISSN |
0556-2813 |
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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 |
Ikeno, N.; Ono, A.; Nara, Y.; Ohnishi, A. |
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Title |
Effects of Pauli blocking on pion production in central collisions of neutron-rich nuclei |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
101 |
Issue |
3 |
Pages |
034607 - 9pp |
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Keywords |
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Abstract |
Pauli blocking is carefully investigated for the processes of NN <-> N Delta and Delta -> N pi in heavy-ion collisions, aiming at a more precise prediction of the pi(-)/pi(+) ratio which is an important observable to constrain the high-density symmetry energy. We use the AMD + JAM approach, which combines the antisymmetrized molecular dynamics for the time evolution of nucleons and the Jet AA Microscopic transport model to treat processes for Delta resonances and pions. As is known in general transport-code simulations, it is difficult to treat Pauli blocking very precisely due to unphysical fluctuations and additional smearing of the phase-space distribution function, when Pauli blocking is treated in the standard method of JAM. We propose an improved method in AMD + JAM to use the Wigner function precisely calculated in AMD as the blocking probability. Different Pauli blocking methods are compared in heavy-ion collisions of neutron-rich nuclei, Sn-132+Sn-124, at 270 MeV/nucleon. With the more accurate method, we find that Pauli blocking is stronger, in particular for the neutron in the final state in NN -> N Delta and Delta -> N pi, compared to the case with a proton in the final state. Consequently, the pi(-)/pi(+) ratio becomes higher when the Pauli blocking is improved, the effect of which is found to be comparable to the sensitivity to the high-density symmetry energy. |
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Address |
[Ikeno, Natsumi] Tottori Univ, Dept Agr Life & Environm Sci, Tottori 6808551, Japan |
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Amer Physical Soc |
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English |
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ISSN |
2469-9985 |
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Conference |
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Notes |
WOS:000519701800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4327 |
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Author |
Ciemala, M. et al; Domingo-Pardo, C.; Perez-Vidal, R.M. |
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Title |
Testing ab initio nuclear structure in neutron-rich nuclei: Lifetime measurements of second 2(+) state in C-16 and O-20 |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
101 |
Issue |
2 |
Pages |
021303 - 7pp |
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Keywords |
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Abstract |
To test the predictive power of ab initio nuclear structure theory, the lifetime of the second 2(+) state in neutron-rich O-20, tau(2(2)(+)) = 150(-30)(+80) fs, and an estimate for the lifetime of the second 2(+) state in C-16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O-18 (7.0 MeV/u) + Ta-181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced gamma-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O-20 and with the no-core shell model for C-16. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles nuclear structure calculations, complementing common benchmarks based on nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available. |
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Address |
[Ciemala, M.; Fornal, B.; Maj, A.; Bednarczyk, P.; Cieplicka-Orynczak, N.; Grebosz, J.; Iskra, L. W.; Kmiecik, M.; Mazurek, K.; Matejska-Minda, M.; Wasilewska, B.; Zieblinski, M.] Inst Nucl Phys, PAN, PL-31342 Krakow, Poland, Email: michal.ciemala@ifj.edu.pl; |
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Amer Physical Soc |
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English |
Summary Language |
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Abbreviated Series Title |
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ISSN |
2469-9985 |
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Notes |
WOS:000517222700001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4311 |
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Author |
ATLAS Collaboration (Aad, G. et al); Alvarez Piqueras, D.; Aparisi Pozo, J.A.; Bailey, A.J.; Cabrera Urban, S.; Castillo, F.L.; Castillo Gimenez, V.; Cerda Alberich, L.; Costa, M.J.; Escobar, C.; Estrada Pastor, O.; Ferrer, A.; Fiorini, L.; Fullana Torregrosa, E.; Fuster, J.; Garcia, C.; Garcia Navarro, J.E.; Gonzalez de la Hoz, S.; Gonzalvo Rodriguez, G.R.; Guerrero Rojas, J.G.R.; Higon-Rodriguez, E.; Jimenez Pena, J.; Lacasta, C.; Lozano Bahilo, J.J.; Madaffari, D.; Mamuzic, J.; Marti-Garcia, S.; Melini, D.; Miñano, M.; Mitsou, V.A.; Moreno Llacer, M.; Rodriguez Bosca, S.; Rodriguez Rodriguez, D.; Ruiz-Martinez, A.; Salt, J.; Santra, A.; Soldevila, U.; Sanchez, J.; Valero, A.; Valls Ferrer, J.A.; Vos, M. |
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Title |
Measurement of the azimuthal anisotropy of charged-particle production in Xe plus Xe collisions at root S-NN=5.44 TeV with the ATLAS detector |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
101 |
Issue |
2 |
Pages |
024906 - 35pp |
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Keywords |
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Abstract |
This paper describes the measurements of flow harmonics v(2)-v(6) in 3 μb(-1) of Xe Xe collisions at root S-NN = 5.44 TeV performed using the ATLAS detector at the Large Hadron Collider (LHC). Measurements of the centrality, multiplicity, and p(T) dependence of the v(n) obtained using two-particle correlations and the scalar product technique are presented. The measurements are also performed using a template-fit procedure, which was developed to remove nonflow correlations in small collision systems. This nonflow removal is shown to have a significant influence on the measured v(n) at high p(T), especially in peripheral events. Comparisons of the measured v(n) with measurements in Pb + Pb collisions and p + Pb collisions at root S-NN = 5.02 TeV are also presented. The v(n) values in Xe + Xe collisions are observed to be larger than those in Pb + Pb collisions for n = 2, 3, and 4 in the most central events. However, with decreasing centrality or increasing harmonic order n, the v(n) values in Xe + Xe collisions become smaller than those in Pb + Pb collisions. The v(n) in Xe + Xe and Pb + Pb collisions are also compared as a function of the mean number of participating nucleons, < N-part >, and the measured charged-particle multiplicity in the detector. The v(3) values in Xe + Xe and Pb + Pb collisions are observed to be similar at the same < N-part > or multiplicity, but the other harmonics are significantly different. The ratios of the measured v(n) in Xe + Xe and Pb + Pb collisions, as a function of centrality, are also compared to theoretical calculations. |
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Address |
[Deliot, F.; Duvnjak, D.; Jackson, P.; Kong, A. X. Y.; Oliver, J. L.; Petridis, A.; Qureshi, A.; Sharma, A. S.; White, M. J.] Univ Adelaide, Dept Phys, Adelaide, SA, Australia |
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Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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ISSN |
2469-9985 |
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Conference |
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Notes |
WOS:000513213800003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4286 |
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Author |
ATLAS Collaboration (Aaboud, M. et al); Alvarez Piqueras, D.; Aparisi Pozo, J.A.; Bailey, A.J.; Cabrera Urban, S.; Castillo, F.L.; Castillo Gimenez, V.; Cerda Alberich, L.; Costa, M.J.; Escobar, C.; Estrada Pastor, O.; Ferrer, A.; Fiorini, L.; Fullana Torregrosa, E.; Fuster, J.; Garcia, C.; Garcia Navarro, J.E.; Gonzalez de la Hoz, S.; Gonzalvo Rodriguez, G.R.; Guerrero Rojas, J.G.; Higon-Rodriguez, E.; Lacasta, C.; Lozano Bahilo, J.J.; Madaffari, D.; Mamuzic, J.; Marti-Garcia, S.; Melini, D.; Miñano, M.; Mitsou, V.A.; Rodriguez Bosca, S.; Rodriguez Rodriguez, D.; Ruiz-Martinez, A.; Salt, J.; Santra, A.; Soldevila, U.; Sanchez, J.; Valero, A.; Valls Ferrer, J.A.; Vos, M. |
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Title |
Measurement of angular and momentum distributions of charged particles within and around jets in Pb plus Pb and pp collisions at root s(NN)=5.02 TeV with the ATLAS detector |
Type |
Journal Article |
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Year |
2019 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
100 |
Issue |
6 |
Pages |
064901 - 29pp |
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Keywords |
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Abstract |
Studies of the fragmentation of jets into charged particles in heavy-ion collisions can provide information about the mechanism of jet quenching by the hot and dense QCD matter created in such collisions, the quark-gluon plasma. This paper presents a measurement of the angular distribution of charged particles around the jet axis in root s(NN) = 5.02 TeV Pb + Pb and pp collisions, using the ATLAS detector at the LHC. The Pb + Pb and pp data sets have integrated luminosities of 0.49 nb(-1) and 25 pb(-1), respectively. The measurement is performed for jets reconstructed with the anti-k(t) algorithm with radius parameter R = 0.4 and is extended to an angular distance of r = 0.8 from the jet axis. Results are presented as a function of Pb + Pb collision centrality and distance from the jet axis for charged particles with transverse momenta in the 1- to 63-GeV range, matched to jets with transverse momenta in the 126- to 316-GeV range and an absolute value of jet rapidity of less than 1.7. Modifications to the measured distributions are quantified by taking a ratio to the measurements in pp collisions. Yields of charged particles with transverse momenta below 4 GeV are observed to be increasingly enhanced as a function of angular distance from the jet axis, reaching a maximum at r = 0.6. Charged particles with transverse momenta above 4 GeV have an enhanced yield in Pb + Pb collisions in the jet core for angular distances up to r = 0.05 from the jet axis, with a suppression at larger distances. |
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Address |
[Deliot, F.; Duvnjak, D.; Jackson, P.; Oliver, J. L.; Petridis, A.; Qureshi, A.; Sharma, A. S.; White, M. J.] Univ Adelaide, Dept Phys, Adelaide, SA, Australia |
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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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Area |
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Expedition |
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Conference |
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Notes |
WOS:000499977600003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4213 |
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