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Author |
Guerrero, C.; Domingo-Pardo, C.; Kappeler, F.; Lerendegui-Marco, J.; Palomo, F.R.; Quesada, J.M.; Reifarth, R. |
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Title |
Prospects for direct neutron capture measurements on s-process branching point isotopes |
Type |
Journal Article |
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Year |
2017 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume  |
53 |
Issue |
5 |
Pages |
87 - 5pp |
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Keywords |
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Abstract |
The neutron capture cross sections of several unstable key isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure directly due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n, gamma) measurement, where high neutron fluxes and effective background rejection capabilities are required. At present there are about 21 relevant s-process branching point isotopes whose cross section could not be measured yet over the neutron energy range of interest for astrophysics. However, the situation is changing with some very recent developments and upcoming technologies. This work introduces three techniques that will change the current paradigm in the field: the use of gamma-ray imaging techniques in (n,gamma) experiments, the production of moderated neutron beams using high-power lasers, and double capture experiments in Maxwellian neutron beams. |
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Address |
[Guerrero, C.; Lerendegui-Marco, J.; Quesada, J. M.] Univ Seville, Dept Fis Atom Mol & Nucl, E-41012 Seville, Spain, Email: carlos.guerrero@cern.ch |
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Publisher |
Springer |
Place of Publication |
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Language |
English |
Summary Language |
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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 |
1434-6001 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000400982700002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3129 |
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Author |
n_TOF Collaboration (Guerrero, C. et al); Domingo-Pardo, C.; Tain, J.L. |
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Title |
Study of Photon Strength Function of Actinides: the Case of (235)U, (238)Np and (241)Pu |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of the Korean Physical Society |
Abbreviated Journal |
J. Korean Phys. Soc. |
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Volume |
59 |
Issue |
2 |
Pages |
1510-1513 |
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Keywords |
Photon/Gamma strength functions; Pygmy; Scissor mode; n_TOF; Total absorption calorimeter; TAC; Neutron capture |
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Abstract |
The decay from excited levels in medium and heavy nuclei can be described in a statistical approach by means of Photon Strength Functions and Level Density distributions. The study of electromagnetic cascades following neutron capture based on the use of high efficiency detectors has been shown to be well suited for probing the properties of the Photon Strength Function of heavy (high level density) and/or radioactive (high background) nuclei. In this work we have investigated for the first time the validity of the recommended PSF of actinides, in particular (235)U, (238)Np and (241)Pu. Our study includes the search for resonance structures in the PSF below S(n) and draws conclusions regarding their existence and their characteristics in terms of energy, width and electromagnetic nature. |
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Address |
[Guerrero, C; Alvarez-Velarde, F; Ano-Ott, DC; Martinez, T; Mendoza, E; Villamarin, D] Ctr Invest Energet Medioambientales & Technol CIE, Madrid, Spain, Email: carlos.guerrero@ciemat.es |
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Corporate Author |
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Thesis |
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Publisher |
Korean 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 |
0374-4884 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000294080700013 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
731 |
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Author |
n_TOF Collaboration (Guerrero, C. et al); Giubrone, G.; Tain, J.L. |
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Title |
Characterization of the New n_TOF Neutron Beam: Fluence, Profile and Resolution |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of the Korean Physical Society |
Abbreviated Journal |
J. Korean Phys. Soc. |
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Volume |
59 |
Issue |
2 |
Pages |
1624-1627 |
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Keywords |
n_TOF; Time-of-flight; Neutron beam; Nuclear data; Cross sections |
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Abstract |
After a halt of four years, the nTOF spallation neutron facility at CERN has resumed operation in November 2008 with a new spallation target characterized by an improved safety and engineering design, resulting in a more robust overall performance and efficient cooling. The first measurement during the 2009 run has aimed at the full characterization of the neutron beam. Several detectors, such as calibrated fission chambers, the nTOF Silicon Monitor, a MicroMegas detector with (10)B and (235)U samples, as well as liquid and solid scintillators have been used in order to characterize the properties of the neutron fluence. The spatial profile of the beam has been studied with a specially designed “X-Y” MicroMegas which provided a 2D image of the beam as a function of neutron energy. Both properties have been compared with simulations performed. with the FLUKA code. The characterization of the resolution function is based on results from simulations which have been verified by the study of narrow capture resonances. of (56)Fe, which were measured as part of a new campaign of (n,gamma) measurements on Fe and Ni isotopes. |
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Address |
[Guerrero, C; Becares, V; Cano-Ott, D; Fernandez-Ordonez, M; Gonzalez-Romero, E; Martin-Fuertes, F; Martinez, T; Mendoza, E; Pina, G; Quinones, J; Vlachoudis, V] Ctr Invest Energet Medioambientales & Tecnol, Madrid 28040, Spain, Email: carlos.guerrero@ciemat.es |
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Corporate Author |
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Thesis |
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Publisher |
Korean 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 |
0374-4884 |
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:000294080700041 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
735 |
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Author |
n_TOF Collaboration (Guerrero, C. et al); Domingo-Pardo, C.; Tain, J.L. |
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Title |
Measurement and resonance analysis of the Np-237 neutron capture cross section |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
85 |
Issue |
4 |
Pages |
044616 - 15pp |
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Keywords |
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Abstract |
The neutron capture cross section of Np-237 was measured between 0.7 and 500 eV at the CERN n_TOF facility using the 4 pi BaF2 Total Absorption Calorimeter. The experimental capture yield was extracted minimizing all the systematic uncertainties and was analyzed together with the most reliable transmission data available using the SAMMY code. The result is a complete set of individual as well as average resonance parameters [D-0 = 0.56(2) eV, <Gamma(gamma)> = 40.9(18) meV, 10(4)S(0) = 0.98(6), R' = 9.8(6) fm]. The capture cross section obtained in this work is in overall agreement with the evaluations and the data of Weston and Todd [Nucl. Sci. Eng. 79, 184 (1981)], thus showing sizable differences with respect to previous data from Scherbakov et al. [J. Nucl. Sci. Technol. 42, 135 (2005)] and large discrepancies with data Kobayashi et al. [J. Nucl. Sci. Technol. 39, 111 (2002)]. The results indicate that a new evaluation combining the present capture data with reliable transmission data would allow reaching an accuracy better than 4%, in line with the uncertainty requirements of the nuclear data community for the design and operation of current and future nuclear devices. |
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Address |
[Guerrero, C.; Cano-Ott, D.; Mendoza, E.; Alvarez-Velarde, F.; Embid-Segura, M.; Gonzalez-Romero, E.; Martinez, T.; Villamarin, D.; Vicente, M. C.] Ctr Invest Energet Medioambientales & Tecnol, CIEMAT, Madrid, Spain |
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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 |
0556-2813 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000303069400004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
993 |
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Author |
n_TOF Collaboration (Guerrero, C. et al); Domingo-Pardo, C.; Tain, J.L. |
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Title |
Neutron Capture on the s-Process Branching Point Tm-171 via Time-of-Flight and Activation |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
125 |
Issue |
14 |
Pages |
142701 - 8pp |
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Keywords |
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Abstract |
The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable Tm-171 (t(1/2) = 1.92 yr) is part of the branching around mass A similar to 170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of Tm-171 at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (nTOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time -of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384 (40) mb, with which the estimation from the nTOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KAlloNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A similar to 170 branching, namely, the Yb-171 abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation. |
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Address |
[Guerrero, C.; Lerendegui-Marco, J.; Quesada, J. M.; Cortes-Giraldo, M. A.; Millan-Callado, M. A.; Praena, J.; Rodriguez-Gonzalez, T.; Sabate-Gilarte, M.] Univ Seville, Seville, Spain, Email: cguerrero4@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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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 |
0031-9007 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000574781200004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4551 |
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