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n_TOF Collaboration (Zugec, P. et al); Domingo-Pardo, C.; Giubrone, G.; Tain, J.L. |
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Title |
Experimental neutron capture data of Ni-58 from the CERN n_TOF facility |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
89 |
Issue |
1 |
Pages |
014605 - 9pp |
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Keywords |
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Abstract |
The Ni-58(n,gamma) cross section has been measured at the neutron time of flight facility n_TOF at CERN, in the energy range from 27 meV up to 400 keV. In total, 51 resonances have been analyzed up to 122 keV. Maxwellian averaged cross sections (MACS) have been calculated for stellar temperatures of kT = 5-100 keV with uncertainties of less than 6%, showing fair agreement with recent experimental and evaluated data up to kT = 50 keV. The MACS extracted in the present work at 30 keV is 34.2 +/- 0.6(stat) +/- 1.8(sys) mb, in agreement with latest results and evaluations, but 12% lower relative to the recent KADoNIS compilation of astrophysical cross sections. When included in models of the s-process nucleosynthesis in massive stars, this change results in a 60% increase of the abundance of Ni-58, with a negligible propagation on heavier isotopes. The reason is that, using both the old or the new MACS, Ni-58 is efficiently depleted by neutron captures. |
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Address |
[Zugec, P.; Bosnar, D.] Univ Zagreb, Fac Sci, Dept Phys, Zagreb 41000, Croatia, Email: pzugec@phy.hr |
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Publisher |
Amer Physical Soc |
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English |
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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 |
0556-2813 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000332151100002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1727 |
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Author |
n_TOF Collaboration (Zugec, P. et al); Domingo-Pardo, C.; Giubrone, G.; Tain, J.L. |
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Title |
GEANT4 simulation of the neutron background of the C6D6 set-up for capture studies at n_TOF |
Type |
Journal Article |
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Year |
2014 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
760 |
Issue |
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Pages |
57-67 |
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Keywords |
GEANT4 simulations; Neutron time of flight; Neutron background; N_TOF; Neutron capture |
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Abstract |
The neutron sensitivity of the Cr6D6 detector setup used at nTOF facility for capture measurements has been studied by means of detailed GEANT4 simulations. A realistic software replica of the entire nTOF experimental hall, including the neutron beam line, sample, detector supports and the walls of the experimental area has been implemented in the simulations. The simulations have been analyzed in the same manner as experimental data, in particular by applying the Pulse Height Weighting Technique. The simulations have been validated against a measurement of the neutron background performed with a(nat)-C sample, showing an excellent agreement above 1 keV. At lower energies, an additional component in the measured C-nat yield has been discovered, which prevents the use of C-nat data for neutron background estimates at neutron energies below a few hundred eV. The origin and time structure of the neutron background have been derived from the simulations. Examples of the neutron background for two different samples are demonstrating the important role of accurate simulations of the neutron background in capture cross-section measurements. |
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Address |
[Zugec, P.; Bosnar, D.] Univ Zagreb, Fac Sci, Dept Phys, Zagreb 41000, Croatia, Email: pzugec@phy.hr |
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Thesis |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Series Volume |
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ISSN |
0168-9002 |
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Conference |
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Notes |
WOS:000338350500008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1828 |
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Author |
n_TOF Collaboration (Paradela, C. et al); Domingo-Pardo, C.; Giubrone, G.; Tain, J.L. |
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Title |
High-accuracy determination of the U-238/U-235 fission cross section ratio up to approximate to 1 GeV at n_TOF at CERN |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
91 |
Issue |
2 |
Pages |
024602 - 11pp |
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Keywords |
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Abstract |
The U-238 to U-235 fission cross section ratio has been determined at nTOF up to approximate to 1 GeV, with two different detection systems, in different geometrical configurations. A total of four datasets has been collected and compared. They are all consistent to each other within the relative systematic uncertainty of 3-4%. The data collected at nTOF have been suitably combined to yield a unique fission cross section ratio as a function of neutron energy. The result confirms current evaluations up to 200 MeV. Good agreement is also observed with theoretical calculations based on the INCL++ /Gemini++ combination up to the highest measured energy. The n_TOF results may help solve a long-standing discrepancy between the two most important experimental datasets available so far above 20 MeV, while extending the neutron energy range for the first time up to approximate to 1 GeV. |
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Address |
[Paradela, C.; Tarrio, D.; Leal-Cidoncha, E.; Duran, I.; Alvarez, H.] Univ Santiago de Compostela, Santiago De Compostela, Spain, Email: nicola.colonna@ba.infn.it |
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Publisher |
Amer Physical Soc |
Place of Publication |
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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 |
0556-2813 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000350174000004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2139 |
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Author |
n_TOF Collaboration (Mingrone, F. et al); Domingo-Pardo, C.; Giubrone, G.; Tain, J.L. |
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Title |
Neutron capture cross section measurement of U-238 at the CERN n_TOF facility in the energy region from 1 eV to 700 keV |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
95 |
Issue |
3 |
Pages |
034604 - 14pp |
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Keywords |
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Abstract |
The aim of this work is to provide a precise and accurate measurement of the U-238(n,gamma) reaction cross section in the energy region from 1 eV to 700 keV. This reaction is of fundamental importance for the design calculations of nuclear reactors, governing the behavior of the reactor core. In particular, fast reactors, which are experiencing a growing interest for their ability to burn radioactive waste, operate in the high energy region of the neutron spectrum. In this energy region most recent evaluations disagree due to inconsistencies in the existing measurements of up to 15%. In addition, the assessment of nuclear data uncertainty performed for innovative reactor systems shows that the uncertainty in the radiative capture cross section of U-238 should be further reduced to 1-3% in the energy region from 20 eV to 25 keV. To this purpose, addressed by the Nuclear Energy Agency as a priority nuclear data need, complementary experiments, one at the GELINA and two at the nTOF facility, were proposed and carried out within the 7th Framework Project ANDES of the European Commission. The results of one of these U-238(n, gamma) measurements performed at the nTOF CERN facility are presented in this work. The gamma-ray cascade following the radiative neutron capture has been detected exploiting a setup of two C6D6 liquid scintillators. Resonance parameters obtained from this work are on average in excellent agreement with the ones reported in evaluated libraries. In the unresolved resonance region, this work yields a cross section in agreement with evaluated libraries up to 80 keV, while for higher energies our results are significantly higher. |
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Address |
[Mingrone, F.; Berthoumieux, E.; Brugger, M.; Calviani, M.; Cerutti, F.; Chiaveri, E.; Chin, M.; Guerrero, C.; Hernandez-Prieto, A.; Kadi, Y.; Losito, R.; Rubbia, C.; Tsinganis, A.; Vlachoudis, V.] CERN, European Org Nucl Res, Geneva, Switzerland, Email: federica.mingrone@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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Area |
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Expedition |
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Conference |
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Notes |
WOS:000396022500002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3030 |
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Author |
n_TOF Collaboration (Massimi, C. et al.); Domingo-Pardo, C.; Giubrone, G.; Tain, J.L. |
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Title |
Neutron spectroscopy of Mg-26 states: Constraining the stellar neutron source Ne-22(alpha, n)Mg-25 |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
768 |
Issue |
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Pages |
1-6 |
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Keywords |
s Process; alpha+Ne-22; Neutron spectroscopy |
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Abstract |
This work reports on accurate, high-resolution measurements of the Mg-25(n, gamma)Mg-26 and Mg-25(n, tot) cross sections in the neutron energy range from thermal to about 300 keV, leading to a significantly improved Mg-25(n, gamma)Mg-26 parametrization. The relevant resonances for n+Mg-25 were characterized from a combined R-matrix analysis of the experimental data. This resulted in an unambiguous spin/parity assignment of the corresponding excited states in Mg-26. With this information experimental upper limits of the reaction rates for Ne-22(alpha, n)Mg-25 and Ne-22(alpha, gamma)Mg-26 were established, potentially leading to a significantly higher (alpha, n)/(alpha, gamma) ratio than previously evaluated. The impact of these results has been studied for stellar models in the mass range 2 to 25 M-circle dot. (C) 2017 The Author(s). Published by Elsevier B.V. |
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Address |
[Massimi, C.; Barbagallo, M.; Becvar, F.; Bisterzok, S.; Castelluccio, D. M.; Eleftheriadis, C.; Finocchiaro, P.; Kokkoris, M.; Marganiec, J.; Plompen, A.; Praena, J.; Rubbia, C.; Weiss, C.] Ist Nazl Fis Nucl, Bologna, Italy, Email: cristian.massimi@bo.infn.it |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier Science Bv |
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 |
0370-2693 |
ISBN |
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Area |
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Conference |
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Notes |
WOS:000400677700001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3112 |
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