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4 results on '"P. Sedyshev"'

1. Shedding Light on the Origin of ^{204}Pb, the Heaviest s-Process-Only Isotope in the Solar System.

Author

Casanovas-Hoste A, Domingo-Pardo C, Lerendegui-Marco J, Guerrero C, Tarifeño-Saldivia A, Krtička M, Pignatari M, Calviño F, Schumann D, Heinitz S, Dressler R, Köster U, Aberle O, Andrzejewski J, Audouin L, Bécares V, Bacak M, Balibrea-Correa J, Barbagallo M, Barros S, Bečvář F, Beinrucker C, Berthoumieux E, Billowes J, Bosnar D, Brugger M, Caamaño M, Calviani M, Cano-Ott D, Cardella R, Castelluccio DM, Cerutti F, Chen YH, Chiaveri E, Colonna N, Cortés G, Cortés-Giraldo MA, Cosentino L, Damone LA, Diakaki M, Dupont E, Durán I, Fernández-Domínguez B, Ferrari A, Ferreira P, Finocchiaro P, Furman V, Göbel K, García AR, Gawlik-Ramięga A, Glodariu T, Gonçalves IF, González-Romero E, Goverdovski A, Griesmayer E, Gunsing F, Harada H, Heftrich T, Heyse J, Jenkins DG, Jericha E, Käppeler F, Kadi Y, Katabuchi T, Kavrigin P, Ketlerov V, Khryachkov V, Kimura A, Kivel N, Kokkoris M, Leal-Cidoncha E, Lederer-Woods C, Leeb H, Lo Meo S, Lonsdale SJ, Losito R, Macina D, Marganiec J, Martínez T, Massimi C, Mastinu P, Mastromarco M, Matteucci F, Maugeri EA, Mendoza E, Mengoni A, Milazzo PM, Mingrone F, Mirea M, Montesano S, Musumarra A, Nolte R, Oprea A, Patronis N, Pavlik A, Perkowski J, Porras I, Praena J, Quesada JM, Rajeev K, Rauscher T, Reifarth R, Riego-Perez A, Romanets Y, Rout PC, Rubbia C, Ryan JA, Sabaté-Gilarte M, Saxena A, Schillebeeckx P, Schmidt S, Sedyshev P, Smith AG, Stamatopoulos A, Tagliente G, Tain JL, Tassan-Got L, Tsinganis A, Valenta S, Vannini G, Variale V, Vaz P, Ventura A, Vlachoudis V, Vlastou R, Wallner A, Warren S, Weigand M, Weiss C, Wolf C, Woods PJ, Wright T, and Žugec P

Abstract

Asymptotic giant branch stars are responsible for the production of most of the heavy isotopes beyond Sr observed in the solar system. Among them, isotopes shielded from the r-process contribution by their stable isobars are defined as s-only nuclei. For a long time the abundance of ^{204}Pb, the heaviest s-only isotope, has been a topic of debate because state-of-the-art stellar models appeared to systematically underestimate its solar abundance. Besides the impact of uncertainties from stellar models and galactic chemical evolution simulations, this discrepancy was further obscured by rather divergent theoretical estimates for the neutron capture cross section of its radioactive precursor in the neutron-capture flow, ^{204}Tl (t_{1/2}=3.78  yr), and by the lack of experimental data on this reaction. We present the first ever neutron capture measurement on ^{204}Tl, conducted at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of ^{204}Tl produced at the Institute Laue Langevin high flux reactor. By complementing our new results with semiempirical calculations we obtained, at the s-process temperatures of kT≈8  keV and kT≈30  keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new ^{204}Tl MACS, the uncertainty arising from the ^{204}Tl(n,γ) cross section on the s-process abundance of ^{204}Pb has been reduced from ∼30% down to +8%/-6%, and the s-process calculations are in agreement with the latest solar system abundance of ^{204}Pb reported by K. Lodders in 2021.

Published
2024
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2. Neutron Capture on the s-Process Branching Point ^{171}Tm via Time-of-Flight and Activation.

Author

Guerrero C, Lerendegui-Marco J, Paul M, Tessler M, Heinitz S, Domingo-Pardo C, Cristallo S, Dressler R, Halfon S, Kivel N, Köster U, Maugeri EA, Palchan-Hazan T, Quesada JM, Rochman D, Schumann D, Weissman L, Aberle O, Amaducci S, Andrzejewski J, Audouin L, Bécares V, Bacak M, Balibrea J, Barak A, Barbagallo M, Barros S, Bečvář F, Beinrucker C, Berkovits D, Berthoumieux E, Billowes J, Bosnar D, Brugger M, Buzaglo Y, Caamaño M, Calviño F, Calviani M, Cano-Ott D, Cardella R, Casanovas A, Castelluccio DM, Cerutti F, Chen YH, Chiaveri E, Colonna N, Cortés G, Cortés-Giraldo MA, Cosentino L, Dafna H, Damone A, Diakaki M, Dietz M, Dupont E, Durán I, Eisen Y, Fernández-Domínguez B, Ferrari A, Ferreira P, Finocchiaro P, Furman V, Göbel K, García AR, Gawlik A, Glodariu T, Gonçalves IF, González-Romero E, Goverdovski A, Griesmayer E, Gunsing F, Harada H, Heftrich T, Heyse J, Hirsh T, Jenkins DG, Jericha E, Käppeler F, Kadi Y, Kaizer B, Katabuchi T, Kavrigin P, Ketlerov V, Khryachkov V, Kijel D, Kimura A, Kokkoris M, Kriesel A, Krtička M, Leal-Cidoncha E, Lederer-Woods C, Leeb H, Lo Meo S, Lonsdale SJ, Losito R, Macina D, Manna A, Marganiec J, Martínez T, Massimi C, Mastinu P, Mastromarco M, Matteucci F, Mendoza E, Mengoni A, Milazzo PM, Millán-Callado MA, Mingrone F, Mirea M, Montesano S, Musumarra A, Nolte R, Oprea A, Patronis N, Pavlik A, Perkowski J, Piersanti L, Porras I, Praena J, Rajeev K, Rauscher T, Reifarth R, Rodríguez-González T, Rout PC, Rubbia C, Ryan JA, Sabaté-Gilarte M, Saxena A, Schillebeeckx P, Schmidt S, Shor A, Sedyshev P, Smith AG, Stamatopoulos A, Tagliente G, Tain JL, Tarifeño-Saldivia A, Tassan-Got L, Tsinganis A, Valenta S, Vannini G, Variale V, Vaz P, Ventura A, Vlachoudis V, Vlastou R, Wallner A, Warren S, Weigand M, Weiss C, Wolf C, Woods PJ, Wright T, and Žugec P

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 ^{171}Tm (t_{1/2}=1.92  yr) is part of the branching around mass A∼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 ^{171}Tm 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 (n_TOF) 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 n_TOF 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 KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the ^{171}Yb 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.

Published
2020
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3. ^{7}Be(n,p)^{7}Li Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN.

Author

Damone L, Barbagallo M, Mastromarco M, Mengoni A, Cosentino L, Maugeri E, Heinitz S, Schumann D, Dressler R, Käppeler F, Colonna N, Finocchiaro P, Andrzejewski J, Perkowski J, Gawlik A, Aberle O, Altstadt S, Ayranov M, Audouin L, Bacak M, Balibrea-Correa J, Ballof J, Bécares V, Bečvář F, Beinrucker C, Bellia G, Bernardes AP, Berthoumieux E, Billowes J, Borge MJG, Bosnar D, Brown A, Brugger M, Busso M, Caamaño M, Calviño F, Calviani M, Cano-Ott D, Cardella R, Casanovas A, Castelluccio DM, Catherall R, Cerutti F, Chen YH, Chiaveri E, Correia JGM, Cortés G, Cortés-Giraldo MA, Cristallo S, Diakaki M, Dietz M, Domingo-Pardo C, Dorsival A, Dupont E, Duran I, Fernandez-Dominguez B, Ferrari A, Ferreira P, Furman W, Ganesan S, García-Rios A, Gilardoni S, Glodariu T, Göbel K, Gonçalves IF, González-Romero E, Goodacre TD, Griesmayer E, Guerrero C, Gunsing F, Harada H, Heftrich T, Heyse J, Jenkins DG, Jericha E, Johnston K, Kadi Y, Kalamara A, Katabuchi T, Kavrigin P, Kimura A, Kivel N, Köster U, Kokkoris M, Krtička M, Kurtulgil D, Leal-Cidoncha E, Lederer-Woods C, Leeb H, Lerendegui-Marco J, Lo Meo S, Lonsdale SJ, Losito R, Macina D, Marganiec J, Marsh B, Martínez T, Masi A, Massimi C, Mastinu P, Matteucci F, Mazzone A, Mendoza E, Milazzo PM, Mingrone F, Mirea M, Musumarra A, Negret A, Nolte R, Oprea A, Patronis N, Pavlik A, Piersanti L, Piscopo M, Plompen A, Porras I, Praena J, Quesada JM, Radeck D, Rajeev K, Rauscher T, Reifarth R, Riego-Perez A, Rothe S, Rout P, Rubbia C, Ryan J, Sabaté-Gilarte M, Saxena A, Schell J, Schillebeeckx P, Schmidt S, Sedyshev P, Seiffert C, Smith AG, Sosnin NV, Stamatopoulos A, Stora T, Tagliente G, Tain JL, Tarifeño-Saldivia A, Tassan-Got L, Tsinganis A, Valenta S, Vannini G, Variale V, Vaz P, Ventura A, Vlachoudis V, Vlastou R, Wallner A, Warren S, Weigand M, Weiß C, Wolf C, Woods PJ, Wright T, and Žugec P

Abstract

We report on the measurement of the ^{7}Be(n,p)^{7}Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n_TOF facility at CERN. This reaction plays a key role in the lithium yield of the big bang nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and they showed a large discrepancy between each other. The measurement was performed with a Si telescope and a high-purity sample produced by implantation of a ^{7}Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low energy, relative to current evaluations, in the region of BBN interest, the present results are consistent with the values inferred from the time-reversal ^{7}Li(p,n)^{7}Be reaction, thus yielding only a relatively minor improvement on the so-called cosmological lithium problem. The relevance of these results on the near-threshold neutron production in the p+^{7}Li reaction is also discussed.

Published
2018
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4. ^{7}Be(n,α)^{4}He Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN.

Author

Barbagallo M, Musumarra A, Cosentino L, Maugeri E, Heinitz S, Mengoni A, Dressler R, Schumann D, Käppeler F, Colonna N, Finocchiaro P, Ayranov M, Damone L, Kivel N, Aberle O, Altstadt S, Andrzejewski J, Audouin L, Bacak M, Balibrea-Correa J, Barros S, Bécares V, Bečvář F, Beinrucker C, Berthoumieux E, Billowes J, Bosnar D, Brugger M, Caamaño M, Calviani M, Calviño F, Cano-Ott D, Cardella R, Casanovas A, Castelluccio DM, Cerutti F, Chen YH, Chiaveri E, Cortés G, Cortés-Giraldo MA, Cristallo S, Diakaki M, Domingo-Pardo C, Dupont E, Duran I, Fernandez-Dominguez B, Ferrari A, Ferreira P, Furman W, Ganesan S, García-Rios A, Gawlik A, Glodariu T, Göbel K, Gonçalves IF, González-Romero E, Griesmayer E, Guerrero C, Gunsing F, Harada H, Heftrich T, Heyse J, Jenkins DG, Jericha E, Katabuchi T, Kavrigin P, Kimura A, Kokkoris M, Krtička M, Leal-Cidoncha E, Lerendegui J, Lederer C, Leeb H, Lo Meo S, Lonsdale SJ, Losito R, Macina D, Marganiec J, Martínez T, Massimi C, Mastinu P, Mastromarco M, Mazzone A, Mendoza E, Milazzo PM, Mingrone F, Mirea M, Montesano S, Nolte R, Oprea A, Pappalardo A, Patronis N, Pavlik A, Perkowski J, Piscopo M, Plompen A, Porras I, Praena J, Quesada J, Rajeev K, Rauscher T, Reifarth R, Riego-Perez A, Rout P, Rubbia C, Ryan J, Sabate-Gilarte M, Saxena A, Schillebeeckx P, Schmidt S, Sedyshev P, Smith AG, Stamatopoulos A, Tagliente G, Tain JL, Tarifeño-Saldivia A, Tassan-Got L, Tsinganis A, Valenta S, Vannini G, Variale V, Vaz P, Ventura A, Vlachoudis V, Vlastou R, Vollaire J, Wallner A, Warren S, Weigand M, Weiß C, Wolf C, Woods PJ, Wright T, and Žugec P

Abstract

The energy-dependent cross section of the ^{7}Be(n,α)^{4}He reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of ^{7}Be and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure ^{7}Be, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-^{7}Be-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.

Published
2016
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