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27 results on '"Dillmann, I."'

1. Study of decay properties for Ba to Nd nuclei relevant for the formation of the r-process rare-earth peak (A∼160).

Author

Pallàs, M., Tarifeño-Saldivia, A., Kiss, G. G., Tain, J. L., Tolosa-Delgado, A., Vitéz-Sveiczer, A., Calviño, F., Agramunt, J., Aguilera, P., Algora, A., Allmond, J. M., Baba, H., Brewer, N. T., Caballero-Folch, R., Coleman-Smith, P. J., Cortes, G., Davinson, T., Dillmann, I., Domingo-Pardo, C., and Estrade, A.

Subjects
RARE earth metals, NUCLEAR reactions, NEUTRON capture, NUCLEOSYNTHESIS, NUCLEAR astrophysics
Abstract

At the RIKEN Nishina Center, exotic neutron-rich isotopes of Ba, La, Ce, Pr, and Nd were measured. This work reports their half-lives (T1/2) and β-delayed neutron-emission probabilities (Pxn). The setup consisted of the BigRIPS in-flight separator for particle identification, the Advanced Implantation Detector Array (AIDA) for ions and β detection, and the BRIKEN neutron counter for neutron detection. Using this arrangement, 4 new T1/2 and 14 new P1n were measured. Furthermore, 38 T1/2 and 2 P1n values were remeasured, decreasing the uncertainties for some of them. In addition to improving predictions of nucleosynthesis models that describe the production of the rare-earth peak at A ∼ 160 via the r-process, these additional experimental data should help to constrain theoretical models for calculations of T1/2 and Pxn in this region. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Indirect measurements of neutron-induced reaction cross sections at storage rings.

Author

Sguazzin, M., Jurado, B., Pibernat, J., Swartz, J. A., Grieser, M., Glorius, J., Litvinov, Y. A., Reifarth, R., Blaum, K., Alfaurt, P., Ascher, P., Audouin, L., Berthelot, C., Blank, B., Bruckner, B., Dellmann, S., Dillmann, I., Domingo-Pardo, C., Dupuis, M., and Erbacher, P.

Subjects
NEUTRON capture, NUCLEOSYNTHESIS, NUCLEAR astrophysics, NUCLEAR reactions, STORAGE rings
Abstract

Neutron-induced reaction cross sections of unstable nuclei are essential for understanding the synthesis of heavy elements in stars. However, their measurement is very difficult due to the radioactivity of the targets involved. We propose to circumvent this problem by using for the first time the surrogate reaction method in inverse kinematics at heavy-ion storage rings. In this contribution, we describe the developments we have done to perform surrogate-reaction studies at the storage rings of GSI/FAIR. In particular, we present the first results of the proof of principle experiment, which we conducted recently at the Experimental Storage Ring (ESR). [ABSTRACT FROM AUTHOR]

Published
2023
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3. Measuring the β -decay Properties of Neutron-rich Exotic Pm, Sm, Eu, and Gd Isotopes to Constrain the Nucleosynthesis Yields in the Rare-earth Region.

Author

Kiss, G. G., Vitéz-Sveiczer, A., Saito, Y., Tarifeño-Saldivia, A., Pallas, M., Tain, J. L., Dillmann, I., Agramunt, J., Algora, A., Domingo-Pardo, C., Estrade, A., Appleton, C., Allmond, J. M., Aguilera, P., Baba, H., Brewer, N. T., Bruno, C., Caballero-Folch, R., Calvino, F., and Coleman-Smith, P. J.

Subjects
NUCLEOSYNTHESIS, RARE earth metals, ISOTOPES, NUCLEAR physics, NEUTRON counters, DATA reduction
Abstract

The β -delayed neutron-emission probabilities of 28 exotic neutron-rich isotopes of Pm, Sm, Eu, and Gd were measured for the first time at RIKEN Nishina Center using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The existing β -decay half-life (T 1/2) database was significantly increased toward more neutron-rich isotopes, and uncertainties for previously measured values were decreased. The new data not only constrain the theoretical predictions of half-lives and β -delayed neutron-emission probabilities, but also allow for probing the mechanisms of formation of the high-mass wing of the rare-earth peak located at A ≈ 160 in the r -process abundance distribution through astrophysical reaction network calculations. An uncertainty quantification of the calculated abundance patterns with the new data shows a reduction of the uncertainty in the rare-earth peak region. The newly introduced variance-based sensitivity analysis method offers valuable insight into the influence of important nuclear physics inputs on the calculated abundance patterns. The analysis has identified the half-lives of 168Sm and of several gadolinium isotopes as some of the key variables among the current experimental data to understand the remaining abundance uncertainty at A = 167â€"172. [ABSTRACT FROM AUTHOR]

Published
2022
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4. β -decay half-lives and β -delayed neutron emission probabilities for several isotopes of Au, Hg, Tl, Pb, and Bi, beyond N=126

Author

Caballero-Folch, R., Domingo-Pardo, C., Agramunt, J., Algora, A., Ameil, F., Ayyad, Y., Benlliure, J., Bowry, M., Calviño, F., Cano-Ott, D., Cortès, G., Davinson, T., Dillmann, I., Estrade, A., Evdokimov, A., Faestermann, T., Farinon, F., Galaviz, D., García, A.R., Geissel, H., Gelletly, W., Gernhäuser, R., Gómez-Hornillos, M.B., Guerrero, C., Heil, M., Hinke, C., Knöbel, R., Kojouharov, I., Kurcewicz, J., Kurz, N., Litvinov, Yu. A., Maier, L., Marganiec, J., Marta, M., Martínez, T., Montes, F., Mukha, I., Napoli, D.R., Nociforo, C., Paradela, C., Pietri, S., Podolyák, Zs., Prochazka, A., Rice, S., Riego, A., Rubio, B., Schaffner, H., Scheidenberger, Ch., Smith, K., Sokol, E., Steiger, K., Sun, B., Taín, J.L., Takechi, M., Testov, D., Weick, H., Wilson, E., Winfield, J.S., Wood, R., Woods, P.J., Yeremin, A., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Physique Nucléaire d'Orsay ( IPNO ), and Université Paris-Sud - Paris 11 ( UP11 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Centre National de la Recherche Scientifique ( CNRS )

Subjects
21.10.-k, r-process, Nuclear Theory, nucleosynthesis, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], nucl-ex, β-delayed neutron emission, 26.30.-k, 27.80.+w, β-decay half-life, nuclear structure, Nuclear Physics - Experiment, neutron detector, [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

$Background:$ Previous measurements of $\beta$-delayed neutron emitters comprise around 230 nuclei, spanning from the $^{8}$He up to $^{150}$La. Apart from $^{210}$Tl, with a minuscule branching ratio of 0.007\%, no other neutron emitter is measured yet beyond $A=150$. Therefore new data are needed, particularly in the heavy mass region around N=126, in order to guide theoretical models and to understand the formation of the third r-process peak at $A\sim195$. $Purpose:$ To measure both, $\beta$-decay half-lives and neutron branching ratios of several neutron-rich Au, Hg, Tl, Pb and Bi isotopes beyond $N=126$. $Method:$ Ions of interest are produced by fragmentation of a $^{238}$U beam, selected and identified via the GSI-FRS fragment separator. A stack of segmented silicon detectors (SIMBA) is used to measure ion-implants and $\beta$-decays. An array of 30 $^3$He tubes embedded in a polyethylene matrix (BELEN) is used to detect neutrons with high efficiency and selectivity. A self-triggered digital system is employed to acquire data and to enable time-correlations. The latter are analyzed with an analytical model and results for the half-lives and neutron-branching ratios are derived using the binned Maximum-Likelihood method. $Results:$ Twenty new $\beta$-decay half-lives are reported for $^{204-206}$Au, $^{208-211}$Hg,$^{211-216}$Tl,$^{215-218}$Pb and $^{218-220}$Bi, nine of them for the first time. Neutron emission probabilities are reported for $^{210,211}$Hg and $^{211-216}$Tl. $Conclusions:$ The new $\beta$-decay half-lives are in good agreement with previous measurements in this region. The measured neutron emission probabilities are comparable or smaller than values predicted by global models like RHB+RQRPA., Comment: 17 pages, 21 figures, will be submitted at PRC

Published
2017

5. Determination of the Neutron-Capture Rate of 17C for the R-process Nucleosynthesis

Author

Heine, M., Typel, S., Wu, M.-R., Adachi, T., Aksyutina, Y., Alcantara, J., Altstadt, S., Alvarez-Pol, H., Ashwood, N., Avdeichikov, T. A. V., Barr, M., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boretzky, K., Borge, M. J. G., Burgunder, G., Caamano, M., Caesar, C., Casarejos, E., Catford, W., Cederkäll, J., Chakraborty, S., Chartier, M., Chulkov, L. V., Cortina-Gil, D., Crespo, R., Datta Pramanik, U., Diaz Fernandez, P., Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Freudenberger, M., Fynbo, H. O. U., Galaviz, D., Geissel, H., Gernhäuser, R., Göbel, K., Golubev, P., Gonzalez Diaz, D., Hagdahl, J., Heftrich, T., Heil, M., Heinz, A., Henriques, A., Holl, M., Ickert, G., Ignatov, A., Jakobsson, B., Johansson, H. T., Jonson, B., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knöbel, R., Kröll, T., Krücken, R., Kurcewicz, J., Kurz, N., Labiche, M., Langer, C., Le Bleis, T., Lemmon, R., Lepyoshkina, O., Lindberg, S., Machado, J., Marganiec, J., Martínez-Pinedo, G., Maroussov, V., Mostazo, M., Movsesyan, A., Najafi, A., Neff, T., Nilsson, T., Nociforo, C., Panin, V., Paschalis, S., Perea, A., Petri, M., Pietri, S., Plag, R., Prochazka, A., Rahaman, A., Rastrepina, G., Reifarth, R., Ribeiro, G., Ricciardi, M. V., Rigollet, C., Riisager, K., Röder, M., Rossi, D., Sanchez Del Rio, J., Savran, D., Scheit, H., Simon, H., Sorlin (Ganil), O., Stoica, V., Streicher, B., Taylor, J. T., Tengblad, O., Terashima, S., Thies, R., Togano, Y., Uberseder, E., Walle, J., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Weigand, M., Wheldon, C., Wilson, G., Wimmer, C., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M. V., Zilges, A., and Zuber, K.

Subjects
r-process, nucleosynthesis, Coulomb dissociation, Nuclear Experiment, radiative neutron capture
Abstract

With the R3B-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of 18C at a projectile energy around 425~AMeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of 17C into the ground state of 18C. Those data have been used to constrain theoretical calculations for transitions populating excited states in 18C. This allowed to derive the astrophysical cross section σ∗nγ accounting for the thermal population of 17C target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures T9≤1~GK. Network simulations with updated neutron-capture rates and hydrodynamics according to the neutrino-driven wind model as well as the neutron-star merger scenario reveal no pronounced influence of neutron capture of 17C on the production of second- and third-peak elements in contrast to earlier sensitivity studies.

Published
2017

6. Accelerator mass spectrometry measurements of the 13C(n,γ)14C and 14N(n,p)14C cross sections

Author

Wallner, A, Bichler, M, Buczak, K, Dillmann, I, Käppeler, F, Karakas, A, Lederer, C, Lugaro, M, Mair, K, Mengoni, A, Schätzel, G, Steier, P, and Trautvetter, H P

Subjects
STELLAR ENERGIES, NUCLEOSYNTHESIS, Astrophysics and Astronomy, C-13 POCKET, AGB STARS, NUCLEAR-DATA, METAL-POOR STARS, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Physics - Experiment, NEUTRON-CAPTURE, GIANT BRANCH STARS, S-PROCESS, LOW METALLICITY
Abstract

The technique of accelerator mass spectrometry (AMS), offering a complementary tool for sensitive studies of key reactions in nuclear astrophysics, was applied for measurements of the C-13(n,gamma)C-14 and the N-14(n,p)C-14 cross sections, which act as a neutron poison in s-process nucleosynthesis. Solid samples were irradiated at Karlsruhe Institute of Technology with neutrons closely resembling a Maxwell-Boltzmann distribution for kT = 25 keV, and also at higher energies between En = 123 and 182 keV. After neutron irradiation the produced amount of C-14 in the samples was measured by AMS at the Vienna Environmental Research Accelerator (VERA) facility. For both reactions the present results provide important improvements compared to previous experimental data, which were strongly discordant in the astrophysically relevant energy range and missing for the comparably strong resonances above 100 keV. For C-13(n,gamma) we find a four times smaller cross section around kT = 25 keV than a previous measurement. For N-14(n,p), the present data suggest two times lower cross sections between 100 and 200 keV than had been obtained in previous experiments and data evaluations. The effect of the new stellar cross sections on the s process in low-mass asymptotic giant branch stars was studied for stellar models of 2 M-circle dot initial mass, and solar and 1/10th solar metallicity.

Published
2016

7. Au-197(n,gamma) cross section in the unresolved resonance region

Author

Lederer, C., Colonna, N., Domingo-Pardo, C., Gunsing, F., Kappeler, F., Massimi, C., Mengoni, A., Wallner, A., Abbondanno, U., Aerts, G., Alvarez, H., Alvarez-Velarde, F., Andriamonje, S., Andrzejewski, J., Assimakopoulos, P., Audouin, L., Badurek, G., Barbagallo, M., Baumann, P., Becvar, F., Belloni, F., Berthoumieux, E., Calviani, M., Calvino, F., Cano-Ott, D., Capote, R., Carrapico, C., de Albornoz, A. C., Cennini, P., Chepel, V., Chiaveri, E., Cortes, G., Couture, A., Cox, J., Dahlfors, M., David, S., Dillmann, I., Dolfini, R., Dridi, W., Duran, I., Eleftheriadis, C., Embid-Segura, M., Ferrant, L., Ferrari, A., Ferreira-Marques, R., Fitzpatrick, L., Frais-Koelbl, H., Fujii, K., Furman, W., Goncalves, I., Gonzalez-Romero, E., Goverdovski, A., Gramegna, F., Griesmayer, E., Guerrero, C., Haas, B., Haight, R., Heil, M., Herrera-Martinez, A., Igashira, M., Isaev, S., Jericha, E., Kadi, Y., Karadimos, D., Karamanis, D., Kerveno, M., Ketlerov, V., Koehler, P., Konovalov, V., Kossionides, E., Krticka, M., Lampoudis, C., Leeb, H., Lindote, A., Lopes, I., Losito, R., Lozano, M., Lukic, S., Marganiec, J., Marques, L., Marrone, S., Martinez, T., Mastinu, P., Mendoza, E., Milazzo, P. M., Moreau, C., Mosconi, M., Neves, F., Oberhummer, H., O'Brien, S., Oshima, M., Pancin, J., Papachristodoulou, C., Papadopoulos, C., Paradela, C., Patronis, N., Pavlik, A., Pavlopoulos, P., Perrot, L., Pigni, M. T., Plag, R., Plompen, A., Plukis, A., Poch, A., Praena, J., Pretel, C., Quesada, J., Rauscher, T., Reifarth, R., Rosetti, M., Rubbia, C., Rudolf, G., Rullhusen, P., Salgado, J., Santos, C., Sarchiapone, L., Sarmento, R., Savvidis, I., Stephan, C., Tagliente, G., Tain, J. L., Tarrio, D., Tassan-Got, L., Tavora, L., Terlizzi, R., Vannini, G., Vaz, P., Ventura, A., Villamarin, D., Vlachoudis, V., Vlastou, R., Voss, F., Walter, S., Wendler, H., Wiescher, M., Wisshak, K., and n TOF Collaboration

Subjects
stars, detector, nuclear-science, cern, nucleosynthesis, library, gold, au-197, neutron-capture
Abstract

The cross section of the reaction Au-197(n,gamma) was measured with the time-of-flight technique at the n_TOF (neutron time-of-flight) facility in the unresolved resonance region between 5 and 400 keV using a pair of C6D6 (where D denotes H-2) liquid scintillators for the detection of prompt capture gamma rays. The results with a total uncertainty of 3.9%-6.7% for a resolution of 20 bins per energy decade show fair agreement with the Evaluated Nuclear Data File Version B-VII.0 (ENDF/B-VII.0), which contains the standard evaluation. The Maxwellian-averaged cross section (MACS) at 30 keV is in excellent agreement with the one according to the ENDF/B-VII.0 evaluation and 4.7% higher than the MACS measured independently by activation technique. Structures in the cross section, which had also been reported earlier, have been interpreted as being due to clusters of resonances. Physical Review C

Published
2011

8. Neutron capture on Zr-94: Resonance parameters and Maxwellian-averaged cross sections

Author

Tagliente, G., Milazzo, P. M., Fujii, K., Abbondanno, U., Aerts, G., Alvarez, H., Alvarez-Velarde, F., Andriamonje, S., Andrzejewski, J., Audouin, L., Badurek, G., Baumann, P., Becvar, F., Belloni, F., Berthoumieux, E., Bisterzo, S., Calvino, F., Calviani, M., Cano-Ott, D., Capote, R., Carrapico, C., Cennini, P., Chepel, V., Chiaveri, E., Colonna, N., Cortes, G., Couture, A., Cox, J., Dahlfors, M., David, S., Dillmann, I., Domingo-Pardo, C., Dridi, W., Duran, I., Eleftheriadis, C., Embid-Segura, M., Ferrari, A., Ferreira-Marques, R., Furman, W., Gallino, R., Goncalves, I., Gonzalez-Romero, E., Gramegna, F., Guerrero, C., Gunsing, F., Haas, B., Haight, R., Heil, M., Herrera-Martinez, A., Jericha, E., Kappeler, F., Kadi, Y., Karadimos, D., Karamanis, D., Kerveno, M., Kossionides, E., Krticka, M., Lamboudis, C., Leeb, H., Lindote, A., Lopes, I., Lozano, M., Lukic, S., Marganiec, J., Marrone, S., Martinez, T., Massimi, C., Mastinu, P., Mengoni, A., Moreau, C., Mosconi, M., Neves, F., Oberhummer, H., O'Brien, S., Pancin, J., Papachristodoulou, C., Papadopoulos, C., Paradela, C., Patronis, N., Pavlik, A., Pavlopoulos, P., Perrot, L., Pigni, M. T., Plag, R., Plompen, A., Plukis, A., Poch, A., Praena, J., Pretel, C., Quesada, J., Rauscher, T., Reifarth, R., Rosetti, M., Rubbia, C., Rudolf, G., Rullhusen, P., Salgado, J., Santos, C., Sarchiapone, L., Savvidis, I., Stephan, C., Tain, J. L., Tassan-Got, L., Tavora, L., Terlizzi, R., Vannini, G., Vaz, P., Ventura, A., Villamarin, D., Vincente, M. C., Vlachoudis, V., Vlastou, R., Voss, F., Walter, S., Wiescher, M., and Wisshak, K.

Subjects
nuclear-data library, n-tof, elements, facility, evolution, nucleosynthesis, zirconium, giant branch stars, system, s-process
Abstract

The neutron capture cross sections of the Zr isotopes play an important role in nucleosynthesis studies. The s-process reaction flow between the Fe seed and the heavier isotopes passes through the neutron magic nucleus Zr-90 and through Zr-91,Zr-92,Zr-93,Zr-94, but only part of the flow extends to Zr-96 because of the branching point at Zr-95. Apart from their effect on the s-process flow, the comparably small isotopic (n, gamma) cross sections make Zr also an interesting structural material for nuclear reactors. The Zr-94 (n, gamma) cross section has been measured with high resolution at the spallation neutron source n_TOF at CERN and resonance parameters are reported up to 60 keV neutron energy. Physical Review C

Published
2011

9. Neutron physics of the Re/Os clock. III. Resonance analyses and stellar (n, gamma) cross sections of (186,187,188)Os

Author

Fujii, K., Mosconi, M., Mengoni, A., Domingo-Pardo, C., Kappeler, F., Abbondanno, U., Aerts, G., Alvarez-Pol, H., Alvarez-Velarde, F., Andriamonje, S., Andrzejewski, J., Assimakopoulos, P., Audouin, L., Badurek, G., Baumann, P., Becvar, F., Belloni, F., Berthoumieux, E., Bisterzo, S., Calviani, M., Calvino, F., Cano-Ott, D., Capote, R., de Albornoz, A. C., Cennini, P., Chepel, V., Chiaveri, E., Colonna, N., Cortes, G., Couture, A., Cox, J., Dahlfors, M., David, S., Dillmann, I., Dolfini, R., Dridi, W., Duran, I., Eleftheriadis, C., Embid-Segura, M., Ferrant, L., Ferrari, A., Ferreira-Marques, R., Fitzpatrick, L., Frais-Koelbl, H., Furman, W., Gallino, R., Goncalves, I., Gonzalez-Romero, E., Goverdovski, A., Gramegna, F., Griesmayer, E., Guerrero, C., Gunsing, F., Haas, B., Haight, R., Heil, M., Herrera-Martinez, A., Igashira, M., Isaev, S., Jericha, E., Kadi, Y., Karamanis, D., Karadimos, D., Kerveno, M., Ketlerov, V., Koehler, P., Konovalov, V., Kossionides, E., Krticka, M., Lamboudis, C., Leeb, H., Lindote, A., Lopes, I., Lozano, M., Lukic, S., Marganiec, J., Marques, L., Marrone, S., Massimi, C., Mastinu, P., Milazzo, P. M., Moreau, C., Neves, F., Oberhummer, H., Oshima, M., O'Brien, S., Pancin, J., Papachristodoulou, C., Papadopoulos, C., Paradela, C., Patronis, N., Pavlik, A., Pavlopoulos, P., Perrot, L., Plag, R., Plompen, A., Plukis, A., Poch, A., Praena, J., Pretel, C., Quesada, J., Rauscher, T., Reifarth, R., Rosetti, M., Rubbia, C., Rudolf, G., Rullhusen, P., Salgado, J., Sarchiapone, L., Savvidis, I., Stephan, C., Tagliente, G., Tain, J. L., Tassan-Got, L., Tavora, L., Terlizzi, R., Vannini, G., Vaz, P., Ventura, A., Villamarin, D., Vincente, M. C., Vlachoudis, V., Vlastou, R., Voss, F., Walter, S., Wendler, H., Wiescher, M., and Wisshak, K.

Subjects
osmium isotopes, re-187-os-187 systematics, statistical-model, age, cosmochronology, nucleosynthesis, giant branch stars, chemical evolution, capture, metal-poor
Abstract

Neutron resonance analyses have been performed for the capture cross sections of (186)Os, (187)Os, and (188)Os measured at the n_TOF facility at CERN. Resonance parameters have been extracted up to 5, 3, and 8 keV, respectively, using the SAMMY code for a full R-matrix fit of the capture yields. From these results average resonance parameters were derived by a statistical analysis to provide a comprehensive experimental basis for modeling of the stellar neutron capture rates of these isotopes in terms of the Hauser-Feshbach statistical model. Consistent calculations for the capture and inelastic reaction channels are crucial for the evaluation of stellar enhancement factors to correct the Maxwellian averaged cross sections obtained from experimental data for the effect of thermally populated excited states. These factors have been calculated for the full temperature range of current scenarios of s-process nucleosynthesis using the combined information of the experimental data in the region of resolved resonances and in the continuum. The consequences of this analysis for the s-process component of the (187)Os abundance and the related impact on the evaluation of the time duration of galactic nucleosynthesis via the Re/Os cosmochronometer are discussed. Physical Review C

Published
2010

10. Recent Efforts in Data Compilations for Nuclear Astrophysics

Author

Dillmann, I. and Collaboration, the JINA-CARINA

Subjects
Nuclear reaction, Information retrieval, Computer science, Astrophysics (astro-ph), Online database, FOS: Physical sciences, 020206 networking & telecommunications, 02 engineering and technology, Astrophysics, 7. Clean energy, Set (abstract data type), Stellar nucleosynthesis, Big Bang nucleosynthesis, Nucleosynthesis, 0202 electrical engineering, electronic engineering, information engineering, Nuclear astrophysics, 020201 artificial intelligence & image processing, Nuclear Experiment (nucl-ex), s-process, Nuclear Experiment
Abstract

Some recent efforts in compiling data for astrophysical purposes are introduced, which were discussed during a JINA-CARINA Collaboration meeting on "Nuclear Physics Data Compilation for Nucleosynthesis Modeling" held at the ECT* in Trento/ Italy from May 29th- June 3rd, 2007. The main goal of this collaboration is to develop an updated and unified nuclear reaction database for modeling a wide variety of stellar nucleosynthesis scenarios. Presently a large number of different reaction libraries (REACLIB) are used by the astrophysics community. The "JINA Reaclib Database" on http://www.nscl.msu.edu/\~nero/db/ aims to merge and fit the latest experimental stellar cross sections and reaction rate data of various compilations, e.g. NACRE and its extension for Big Bang nucleosynthesis, Caughlan and Fowler, Iliadis et al., and KADoNiS. The KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars, http://nuclear-astrophysics.fzk.de/kadonis) project is an online database for neutron capture cross sections relevant to the s process. The present version v0.2 is already included in a REACLIB file from Basel university (http://download.nucastro.org/astro/reaclib). The present status of experimental stellar $(n,\gamma)$ cross sections in KADoNiS is shown. A "high priority list" for measurements and evaluations for light charged-particle reactions set up by the JINA-CARINA collaboration is presented. The central web access point to submit and evaluate new data is provided by the Oak Ridge group via the http://www.nucastrodata.org homepage. "Workflow tools" aim to make the evaluation process transparent and allow users to follow the progress., Comment: Proceedings 10th Int. Symp. on Origin of Matter and Evolution of Galaxies OMEG07, Sapporo/ Japan, December 4-7 2007

Published
2008

11. Nuclear physics for the Re/Os clock

Author

Mosconi, M., Heil, M., Kappeler, F., Plag, R., Mengoni, A., Fujii, K., Domingo-Pardo, C., Aerts, G., Terlizzi, R., Gallino, R., Abbondanno, U., Alvarez, H., Alvarez-Velarde, F., Andriamonje, S., Andrzejewski, J., Assimakopoulos, P., Audouin, L., Badurek, G., Baumann, P., Becvar, F., Berthoumieux, E., Calvino, F., Calviani, M., Cano-Ott, D., Capote, R., Carrapico, C., Cennini, P., Chepel, V., Colonna, N., Cortes, G., Couture, A., Cox, J., Dahlfors, M., David, S., Dillmann, I., Dridi, W., Duran, I., Eleftheriadis, C., Embid-Segura, M., Ferrant, L., Ferrari, A., Ferreira-Marques, R., Furman, W., Goncalves, I., Gonzalez-Romero, E., Gramegna, F., Guerrero, C., Gunsing, F., Haas, B., Haight, R., Herrera-Martinez, A., Igashira, M., Jericha, E., Kadi, Y., Karadimos, D., Karamanis, D., Kerveno, M., Koehler, P., Kossionides, E., Krticka, M., Lamboudis, C., Leeb, H., Lindote, A., Lopes, I., Lozano, M., Lukic, S., Marganiec, J., Marrone, S., Massimi, C., Mastinu, P., Milazzo, P. M., Neves, F., Oberhummer, H., O'Brien, S., Pancin, J., Papachristodoulou, C., Papadopoulos, C., Paradela, C., Patronis, N., Pavlik, A., Pavlopoulos, P., Perrot, L., Pigni, M. T., Plompen, A., Plukis, A., Poch, A., Pretel, C., Quesada, J., Rauscher, T., Reifarth, R., Rubbia, C., Rudolf, G., Rullhusen, P., Salgado, J., Santos, C., Sarchiapone, L., Savvidis, I., Stephan, C., Tagliente, G., Tain, J. L., Tassan-Got, L., Tavora, L., Vannini, G., Vaz, P., Ventura, A., Villamarin, D., Vincente, M. C., Vlachoudis, V., Vlastou, R., Voss, F., Walter, S., Wiescher, M., Wisshak, K., and n TOF Collaboration

Subjects
stars, age, neutron cross-sections, nucleosynthesis, os-187, inelastic-scattering, isotopes
Abstract

Dating the age of the universe by the beta-decay of (187)Re (t(1/2) = 41.2 Gyr) requires the accurate assessment of the s-process reaction flow. The daughter nucleus (187)Os as well as its immediate s-only neighbor (186)Os are shielded from the r-process. Therefore, the radiogenic contribution to (187)Os can be derived via the local approximation of the s-process, which is well justified in this mass region: ( N(s))(187) = ( N(s))(186). Accordingly, accurate Maxwellian-averaged (n,gamma) cross sections have to be known for (186)Os and (187)Os over the full range of s-process temperatures. Because (187)Os has low-lying excited states, which are significantly populated during the s-process, neutron captures on these excited states have to be properly taken into account. The input for the corresponding Hauser-Feshbach calculations can be constrained by deriving the strength functions from a detailed resonance analysis of the measured (n,gamma) cross sections as well as by an additional measurement of the inelastic scattering cross section for the first exited level, which dominates the competition between the capture and scattering channels. This contribution reports on measurements of the neutron capture cross sections of (186)Os, (187)Os and (188)Os from the eV region to 1MeV at the CERN/n_TOF facility and of the inelastic scattering cross section of (187)Os around 30 keV at the Karlsruhe 3.7 MV Van de Graaff accelerator. Based on these results and on a detailed resonance analysis, improved Maxwellian-averaged cross sections were obtained for thermal energies between 5 keV and 100 keV. The implications of these results for the Re/Os clock are discussed. Journal of Physics G-Nuclear and Particle Physics

Published
2008

12. Experimental study of the 91Zr(n gamma) reaction up to 26 keV

Author

Tagliente, G, Milazzo, P M, Fujii, K, Aerts, G, Abbondanno, U, Alvarez, H, Alvarez-Velarde, F, Andriamonje, Samuel A, Andrzejewski, J, Assimakopoulos, Panayiotis, Audouin, L, Badurek, G, Baumann, P, Becvár, F, Belloni, F, Berthoumieux, E, Calviño, F, Calviani, M, Cano-Ott, D, Capote, R, Carrapiço, C, Cennini, P, Chepel, V, Colonna, N, Cortés, G, Couture, A, Cox, J, Dahlfors, M, David, S, Dillmann, I, Domingo-Pardo, C, Dridi, W, Durán, I, Eleftheriadis, C, Embid-Segura, M, Ferrant, L, Ferrari, A, Ferreira-Marques, R, Furman, W, Gonçalves, I, Gonzalez-Romero, E, Gramegna, F, Guerrero, C, Gunsing, F, Haas, B, Haight, R, Heil, M, Herrera-Martínez, A, Igashira, M, Jericha, E, Kappeler, F, Kadi, Y, Karadimos, D, Karamanis, D, Kerveno, M, Köhler, P, Kossionides, E, Krticka, M, Lamboudis, C, Leeb, H, Lindote, A, Lopes, I, Lozano, M, Lukic, S, Marganiec, J, Marrone, S, Martínez, T, Massimi, C, Mastinu, P, Mengoni, A, Moreau, C, Mosconi, M, Neves, F, Oberhummer, H, O'Brien, S, Pancin, J, Papachristodoulou, C, Papadopoulos, C, Paradela, C, Patronis, N, Pavlik, A, Pavlopoulos, P, Perrot, L, Pigni, M T, Plag, R, Plompen, A, Plukis, A, Poch, A, Praena-Rodriguez, J, Pretel, C, Quesada, J, Rauscher, T, Reifarth, R, Rubbia, C, Rudolf, G, Rullhusen, P, Salgado, J, Santos, C, Sarchiapone, L, Savvidis, I, Stéphan, C, Taín, J L, Tassan-Got, L, Tavora, L, Terlizzi, R, Vannini, G, Vaz, P, Ventura, A, Villamarín, D, Vincente, M C, Vlachoudis, V, Vlastou, R, Voss, F, Walter, S, Wiescher, M, Wisshak, K, Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Laboratori Nazionali di Legnaro (LNL), Istituto Nazionale di Fisica Nucleare (INFN), European Organization for Nuclear Research (CERN), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Fisica Nucleare, Sezione di Bologna (INFN, Sezione di Bologna), nTOF, Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and National Institute for Nuclear Physics (INFN)

Subjects
statistical-model, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, cern, transmission, nucleosynthesis, capture cross-sections, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 25.40.Lw, 25.70.Ef, 27.60.+j, 97.10.Cv, n-tof, evolution, Nuclear Physics - Experiment, giant branch stars, Nuclear Experiment, neutron-capture, s-process
Abstract

The neutron capture cross sections of the Zr isotopes are relevant to studies in nuclear structure, nuclear astrophysics, and nuclear technology. The valence neutron of (91)Zr with respect to the neutron magic nucleus (90)Zr has interesting implications for the statistical analysis in the proximity of shell closures. In stellar nucleosynthesis, the Zr isotopes are important for the s-process reaction flow between the Fe seeds and the heavier isotopes. Because of its relatively small (n, gamma) cross sections, Zr represents also an interesting structural material for nuclear reactors. For the same reason, these cross sections are difficult to measure and reliable data are sparse. Therefore, the (n, gamma) cross sections of the Zr isotopes have been remeasured at the CERN n_TOF facility. Thanks to its high instantaneous flux, good energy resolution, and low background, this facility is particularly suited for the determination of small, resonance-dominated cross sections. In this work, results for the (91)Zr(n, gamma) (92)Zr reaction are reported in the neutron energy range from thermal to 26 keV. In this region, accurate data of 157 resonances could be obtained, 33 of these resonances are not present in the main databases and/or were observed for the first time. Physical Review C

Published
2008

13. Measurement of the neutron capture cross section of the s-only isotope Pb-204 from 1 eV to 440 keV

Author

Domingo Pardo, César, Abbondanno, U., Aerts, G., Álvarez-Pol, H., Álvarez-Velarde, F., Andriamonje, S., Andrzejewski, J., Assimakopoulos, P., Audouin, L., Badurek, G., Baumann, P., Vaz, P., Ventura, A., Villamarin, D., Vincente, M. C., Berthoumieux, E., Vlachoudis, V., Vlastou, R., Voss, F., Wendler, H., Wiescher, M., Dahlfors, M., Wisshak, K., Bisterzo, S., Calvino, F., Cano Ott, Daniel, Capote, R., Carrapico, C., Eleftheriadis, C., Cennini, P., Chepel, V., Chiaveri, E., David, S., Colonna, N., Cortés Rossell, Guillem, Couture, A., Cox, J., Dillmann, I., Embid-Segura, M., Dolfini, R., Dridi, W., Durán, Ignacio, Ferrant, L., Ferrari, A., Ferreira-Marques, R., Haight, R., Fitzpatrick, L., Frais-Koelbl, H., Fujii, K., Furman, W., Gallino, R., Jericha, E., Goncalves, I., González-Romero, E., Goverdovski, A., Gramegna, F., Heil, M., Griesmayer, E., Guerrero, C., Gunsing, F., Haas, B., Kadi, Y., Herrera-Martínez, A., Igashira, M., Isaev, S., Kappeler, F., Karamanis, D., Karadimos, D., Kerveno, M., Mastinu, P., Ketlerov, V., Koehler, P., Konovalov, V., Kossionides, E., Mosconi, M., Krticka, M., Lamboudis, C., Leeb, H., Lindote, A., Lopes, I., Neves, F., Lozano, M., Lukic, S., Marganiec, J., Marrone, S., Mengoni, A., Milazzo, P. M., Moreau, C., Oberhummer, H., Oshima, M., O'Brien, S., Pancin, J., Papachristodoulou, C., Rauscher, T., Papadopoulos, C., Paradela, C., Patronis, N., Rudolf, G., Pavlik, A., Pavlopoulos, P., Perrot, L., Plag, R., Plompen, A., Plukis, A., Rullhusen, P., Poch, A., Pretel, C., Quesada, J., n_TOF Collaboration, Reifarth, R., Rosetti, M., Rubbia, C., Salgado, J., Sarchiapone, L., Savvidis, I., Stephan, C., Tagliente, G., Walter, S., Taín, José Luis, Tassan-Got, L., Tavora, L., Becvar, F., Terlizzi, R., and Vannini, G.

Subjects
[PACS] Stellar structure, interiors, evolution, nucleosynthesis, ages, R-process, Abundances, Elements, [PACS] Nucleon radiative capture, Nucleosynthesis, [PACS] Properties of nuclei with 190 ≤ A ≤ 219, Galactic chemical evolution, Giant Branch Stars
Abstract

9 pages, 3 figures.-- PACS nrs.: 25.40.Lw; 27.80.+w; 97.10.Cv.-- ISI Article Identifier: 000243896000061.-- ArXiv pre-print available at: http://arxiv.org/abs/nucl-ex/0610033, The neutron capture cross section of Pb-204 has been measured at the CERN n_TOF installation with high resolution in the energy range from 1 eV to 440 keV. An R-matrix analysis of the resolved resonance region, between 1 eV and 100 keV, was carried out using the SAMMY code. In the interval between 100 keV and 440 keV we report the average capture cross section. The background in the entire neutron energy range was reliably determined from the measurement of a Pb-208 sample. Other systematic effects in this measurement were investigated and precisely corrected by means of detailed Monte Carlo simulations. We obtain a Maxwellian average capture cross section for Pb-204 at kT=30 keV of 79(3) mb, in agreement with previous experiments. However our cross section at kT=5 keV is about 35% larger than the values reported so far. The implications of the new cross section for the s-process abundance contributions in the Pb/Bi region are discussed., This work was supported by the European Commission (FIKW-CT-2000-00107), by the Spanish Ministry of Science and Technology (FPA2001-0144-C05), and partly by the Italian MIUR-FIRB grant "The astrophysical origin of the heavy elements beyond Fe".

Published
2007

14. Measurement of the neutron capture cross section of the s-only isotope Pb-204 from 1 eV to 440 keV

Author

Domingo-Pardo, C., Abbondanno, U., Aerts, G., Alvarez-Pol, H., Alvarez-Velarde, F., Andriamonje, S., Andrzejewski, J., Assimakopoulos, P., Audouin, L., Badurek, G., Baumann, P., Becvar, F., Berthoumieux, E., Bisterzo, S., Calvino, F., Cano-Ott, D., Capote, R., Carrapico, C., Cennini, P., Chepel, V., Chiaveri, E., Colonna, N., Cortes, G., Couture, A., Cox, J., Dahlfors, M., David, S., Dillmann, I., Dolfini, R., Dridi, W., Duran, I., Eleftheriadis, C., Embid-Segura, M., Ferrant, L., Ferrari, A., Ferreira-Marques, R., Fitzpatrick, L., Frais-Koelbl, H., Fujii, K., Furman, W., Gallino, R., Goncalves, I., Gonzalez-Romero, E., Goverdovski, A., Gramegna, F., Griesmayer, E., Guerrero, C., Gunsing, F., Haas, B., Haight, R., Heil, M., Herrera-Martinez, A., Igashira, M., Isaev, S., Jericha, E., Kadi, Y., Kappeler, F., Karamanis, D., Karadimos, D., Kerveno, M., Ketlerov, V., Koehler, P., Konovalov, V., Kossionides, E., Krticka, M., Lamboudis, C., Leeb, H., Lindote, A., Lopes, I., Lozano, M., Lukic, S., Marganiec, J., Marrone, S., Mastinu, P., Mengoni, A., Milazzo, P. M., Moreau, C., Mosconi, M., Neves, F., Oberhummer, H., Oshima, M., O'Brien, S., Pancin, J., Papachristodoulou, C., Papadopoulos, C., Paradela, C., Patronis, N., Pavlik, A., Pavlopoulos, P., Perrot, L., Plag, R., Plompen, A., Plukis, A., Poch, A., Pretel, C., Quesada, J., Rauscher, T., Reifarth, R., Rosetti, M., Rubbia, C., Rudolf, G., Rullhusen, P., Salgado, J., Sarchiapone, L., Savvidis, I., Stephan, C., Tagliente, G., Tain, J. L., Tassan-Got, L., Tavora, L., Terlizzi, R., Vannini, G., Vaz, P., Ventura, A., Villamarin, D., Vincente, M. C., Vlachoudis, V., Vlastou, R., Voss, F., Walter, S., Wendler, H., Wiescher, M., and Wisshak, K.

Subjects
elements, lead, abundances, Astrophysics::High Energy Astrophysical Phenomena, r-process, cern, nucleosynthesis, giant branch stars, galactic chemical evolution, solar, chronometers
Abstract

The neutron capture cross section of Pb-204 has been measured at the CERN n_TOF installation with high resolution in the energy range from 1 eV to 440 keV. An R-matrix analysis of the resolved resonance region, between 1 eV and 100 keV, was carried out using the SAMMY code. In the interval between 100 keV and 440 keV we report the average capture cross section. The background in the entire neutron energy range was reliably determined from the measurement of a Pb-208 sample. Other systematic effects in this measurement were investigated and precisely corrected by means of detailed Monte Carlo simulations. We obtain a Maxwellian average capture cross section for Pb-204 at kT=30 keV of 79(3) mb, in agreement with previous experiments. However our cross section at kT=5 keV is about 35% larger than the values reported so far. The implications of the new cross section for the s-process abundance contributions in the Pb/Bi region are discussed. ispartof: Physical Review C vol:75 issue:1 pages:1-9 status: published

Published
2007

15. The 139Lan,gamma cross section: Key for the onset of the s-process

Author

Terlizzi, R., Abbondanno, U., Aerts, G., Alvarez, H., Alvarez-Velarde, H., Alvarez-Velarde, F., Andriamonje, S., Andrzejewski, J., Assimakopoulos, P., Audouin, L., Badurek, G., Baumann, P., Becvar, F., Berthoumieux, E., Calviani, M., Calvino, F., Cano-Ott, D., Capote, R., De Albornoz, A.C., Cennini, P., Chepel, V., Chiaveri, E., Colonna, N., Cortes, G., Couture, A., Cox, J., Dahlfors, M., David, S., Dillmann, I., Dolfini, R., Domingo-Pardo, C., Dridi, W., Duran, I., Eleftheriadis, C., Embid-Segura, M., Ferrant, L., Ferrari, Anthony, Ferreira-Marques, R., Fitzpatrick, L., Frais-Koelbl, H., Fujii, K., Furman, W., Gallino, R., Goncalves, I., Gonzalez-Romero, E., Goverdovski, A., Gramegna, F., Griesmayer, E., Guerrero, C., Gunsing, F., Haas, B., Haight, R., Heil, M., Herrera-Martinez, A., Igashira, M., Isaev, S., Jericha, E., Kadi, Y., Kappeler, F., Karamanis, D., Karadimos, D., Kerveno, M., Ketlerov, V., Koehler, P., Konovalov, V., Kossionides, E., Krticka, M., Lamboudis, C., Leeb, H., Lindote, A., Lopes, I., Lozano, M., Lukic, S., Marganiec, J., Marques, L., Marrone, S., Massimi, C., Mastinu, P., Mengoni, A., Milazzo, P.M., Moreau, C., Mosconi, M., Neves, F., Oberhummer, H., O'Brien, S., Pancin, J., Papachristodoulou, C., Papadopoulos, C., Paradela, C., Patronis, N., Pavlik, A., Pavlopoulos, P., Perrot, L., Pignatari, M., Plag, R., Plompen, A., Plukis, A., Poch, A., Pretel, C., Quesada, J., Rauscher, T., Reifarth, R., Rosetti, M., Rubbia, C., Rudolf, G., Rullhusen, P., Salgado, J., Sarchiapone, L., Savvidis, I., Stephan, C., Tagliente, G., Tain, J.L., Tassan-Got, L., Tavora, L., Vannini, G., Vaz, P., Ventura, A., Villamarin, D., Vincente, M.C., Vlachoudis, V., Vlastou, R., Voss, F., Walter, S., Wendler, H., Wiescher, M., Wisshak, K., Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), nTOF, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
level density, Nuclear Theory, s and r process, FOS: Physical sciences, nucleosynthesis, 25.40.Lw, 26.20.+f, 27.60.+j, 97.10.Cv, Nuclear Experiment (nucl-ex), 139La, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, neutron capture, neutron strength function
Abstract

The nuclear resonance parameters and the capture cross section of the neutron magic isotope 139La has been measured n_TOF. The description of the experimental apparata is followed by the data analysis procedures. We extracted the resonance parameters, the main nuclear quantities such as the resonance integral, the average gamma widths for s- and p-waves, the nuclear level densities and the neutron strength functions. These results represent a signifcant improvement over previous data. The deduced Maxwellian-averaged capture cross sections are important for the interpretation of the most recent spectroscopic observations in low metallicity stars., Comment: 50 pages and 9 Figures

Published
2007

16. s-process nucleosynthesis in massive stars: new results on 60Fe, 62Ni and 64Ni.

Author

Domingo-Pardo, C., Dillmann, I., Faestermann, T., Giesen, U., Görres, J., Heil, M., Horn, S., Käppeler, F., Köchli, S., Korschinek, G., Lachner, J., Maiti, M., Marganiec, J., Neuhausen, J., Nolte, R., Poutivtsev, M., Reifarth, R., Rugel, R., Schumann, D., and Uberseder, E.

Subjects
*NUCLEOSYNTHESIS, *SUPERGIANT stars, *IRON, *NICKEL, *NEUTRONS, *ISOTOPES, *MASS spectrometry, *GERMANIUM
Abstract

The s process synthesizes the elements between Fe and Sr in massive stars during two major evolutionary stages, convective core He burning and C shell burning. This scenario implies fascinating consequences for the chemical evolution of the star. For instance, the neutron capture rate at each isotope can have a big influence on the production of many of the subsequent higher mass isotopes. Correspondingly, one needs to know the (n,γ) cross sections of the involved isotopes with high accuracy in order to determine the abundance pattern reliably and to obtain a consistent picture of this stage. This contribution gives an overview on recent and future experiments for the Fe/Ni nucleosynthesis in massive stars. New results on 60Fe, 62Ni and 64Ni are reported. 60Fe is mostly produced during the short convective C shell burning phase, where peak densities of ∼1011 cm-3 are reached, prior to the SN explosion. The stellar (n,γ) cross section of 60Fe could be measured with a 1 μg sample obtained at PSI (Switzerland), which was sufficient for an activation measurement using the intense, quasi-stellar neutron field for a thermal energy of 25 keV at the Karlsruhe Van de Graaff accelerator. The FZK accelerator was also used for an activation of 62Ni, whereas in this case, the number of 63Ni nuclei produced were determined via accelerator mass spectroscopy at the Maier-Leibnitz-Laboratorium in Garching/Munich. The (n,γ) cross section of 64Ni at a stellar temperature equivalent to 50 keV has been measured in a collaboration between FZK Karlsruhe and PTB Braunschweig. Finally, complementary time of flight measurements on the Fe and Ni isotopes over a broad energy range are planned at the white neutron source n_TOF of CERN for the future campaign in 2009. [ABSTRACT FROM AUTHOR]

Published
2009
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17. The Karlsruhe Astrophysical Database of Nucleosynthesis in Stars Project - Status and Prospects.

Author

Dillmann, I., Szücs, T., Plag, R., Fülöp, Z., Käppeler, F., Mengoni, A., and Rauscher, T.

Subjects
*ASTROPHYSICS, *NUCLEOSYNTHESIS, *NUCLEAR cross sections, *HEAVY ions, *BISMUTH isotopes, *NUCLEAR physics experiments
Abstract

The KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars) project is an astrophysical online database for cross sections relevant for nucleosynthesis in the s process and the &#947 process. The s-process database (http://www.kadonis.org) was started in 2005 and is presently facing its 4th update (KADoNiS v1.0). The &#947-process database (KADoNiS-p, http://www.kadonis.org/pprocess) was recently revised and re-launched in March 2013. Both databases are compilations for experimental cross sections with relevance to heavy ion nucleosynthesis. For the s process recommended Maxwellian averaged cross sections for kT=5-100 keV are given for more than 360 isotopes between ¹H and 210Bi. For the &#947-process database all available experimental data from (p,&#947),(p,n),(p,α),(α,&#947),(α,n), and (α,p) reactions between 70Ge and 209Bi in or close to the respective Gamow window were collected and can be compared to theoretical predictions. The aim of both databases is a quick and user-friendly access to the available data in the astrophysically relevant energy regions. [ABSTRACT FROM AUTHOR]

Published
2014
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18. AMS Applications in Nuclear Astrophysics: New Results for [sup 13]C(n, γ)[sup 14] C and [sup 14]N(n,p)[sup 14]C.

Author

Wallner, A., Buczak, K., Dillmann, I., Feige, J., Käppeler, F., Korschinek, G., Lederer, C., Mengoni, A., Ott, U., Paul, M., Schätzel, G., Steier, P., and Trautvetter, H. P.

Abstract

The technique of accelerator mass spectrometry (AMS) offers a complementary tool for studying long-lived radionuclides in nuclear astrophysics: (1) as a tool for investigating nucleosynthesis in the laboratory; and (2) via a direct search of live long-lived radionuclides in terrestrial archives as signatures of recent nearby supernova-events. A key ingredient to our understanding of nucleosynthesis is accurate cross-section data. AMS was applied for measurements of the neutron-induced cross sections [sup 13]C(n,γ) and [sup 14]N(n,p), both leading to the long-lived radionuclide [sup 14]C. Solid samples were irradiated at Karlsruhe Institute of Technology with neutrons closely resembling a Maxwell-Boltzmann distribution for kT = 25 keV, and with neutrons of energies between 123 and 178 keV. After neutron activation the amount of [sup 14]C nuclides in the samples was measured by AMS at the VERA (Vienna Environmental Research Accelerator) facility. Both reactions, [sup 13]C(n,γ)[sup 14]C and [sup 14]N(n,p)[sup 14]C, act as neutron poisons in s-process nucleosynthesis. However, previous experimental data are discordant. The new data for both reactions tend to be slightly lower than previous measurements for the 25 keV Maxwell-Boltzmann energy distribution. For the higher neutron energies no previous data did exist for [sup 13]C(n,γ), but model calculations indicated a strong resonance structure between 100 and 300 keV which is confirmed by our results. Very limited information is available for [sup 14]N(n,p) at these energies. Our new data at 123 and 178 keV suggest lower cross sections than expected from previous experiments and data evaluations. The complementary technique of neutron activation and subsequent accelerator mass spectrometry (AMS) measurement was for the first time applied to studying [sup 14]C production from [sup 13]C(n,γ) and [sup 14]N(n,p). New data for these neutron poisons obtained for neutron energies between 25 and 178 keV are slightly lower than previous results and evaluations suggest. [ABSTRACT FROM AUTHOR]

Published
2012
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19. OPPORTUNITIES TO CONSTRAIN ASTROPHYSICAL REACTION RATES FOR THE s-PROCESS VIA DETERMINATION OF THE GROUND-STATE CROSS-SECTIONS.

Author

RAUSCHER, T., MOHR, P., DILLMANN, I., and FLAG, R.

Subjects
ASTROPHYSICS, ASTRONOMY, NUCLEOSYNTHESIS, COSMOCHEMISTRY, CHEMICAL elements
Abstract

Modern models of s-process nucleosynthesis in stars require stellar reaction rates of high precision. Most neutron-capture cross-sections in the s-process have been measured, and for an increasing number of reactions the required precision is achieved. This does not necessarily mean, however, that the stellar rates are constrained equally well, because only the capture of the ground state of a target is measured in the laboratory. Captures of excited states can contribute considerably to stellar rates that are already at typical s-process temperatures. We show that the ground-state contribution X to a stellar rate is the relevant measure to identify reactions that are or could be well constrained by experiments and apply it to (n,γ) reactions in the s-process. We further show that the maximum possible reduction in uncertainty of a rate via determination of the ground-state cross-section is given directly by X. An error analysis of X is presented, and it is found that X is a robust measure with mostly small uncertainties. Several specific examples (neutron capture of 79Se, 95Zr, 121Sn, 187Os, and 193Pt) are discussed in detail. The ground-state contributions for a set of 412 neutron-capture reactions around the s-process path are presented in a table. This allows identification of reactions that may be better constrained by experiments and that cannot be constrained solely by measuring ground-state cross-sections (and thus require supplementary studies). General trends and implications are discussed. [ABSTRACT FROM AUTHOR]

Published
2011
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20. (n,γ) cross-sections of light p nuclei.

Author

Dillmann, I., Heil, M., Käppeler, F., Plag, R., Rauscher, T., and Thielemann, F.-K.

Subjects
*IRON, *NUCLEOSYNTHESIS, *STABLE isotopes, *SUPERNOVAE, *NEUTRON capture, *PHOTONUCLEAR reactions, *RADIATIVE capture
Abstract

The nucleosynthesis of elements beyond iron is dominated by the s and r processes. However, a small amount of stable isotopes on the proton-rich side cannot be made by neutron capture and is thought to be produced by photodisintegration reactions on existing seed nuclei in the so-called “ p process”. So far most of the p-process reactions are not yet accessible by experimental techniques and have to be inferred from statistical Hauser-Feshbach model calculations. The parametrization of these models has to be constrained by measurements on stable proton-rich nuclei. A series of ( n,γ) activation measurements on p nuclei, related by detailed balance to the respective photodisintegrations, was carried out at the Karlsruhe Van de Graaff accelerator using the 7Li( p, n) 7Be source for simulating a Maxwellian neutron distribution of kT = 25keV. We present here preliminary results of our extended measuring program in the mass range between A = 74 and A = 132, including first experimental ( n,γ) cross-sections of 74Se, 84Sr, 120Te and 132Ba, and an improved value for 130Ba. In all cases we find perfect agreement with the recommended MACS predictions from the Bao et al. compilation. [ABSTRACT FROM AUTHOR]

Published
2006
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21. Stellar (n, γ) cross sections of neutron-rich nuclei.

Author

Marganiec, J., Dillmann, I., Domingo Pardo, C., and Käppeler, F.

Subjects
*PARTICLE accelerators, *NEUTRONS, *IRRADIATION, *NUCLEOSYNTHESIS, *NUCLEAR astrophysics
Abstract

The present measurements were performed by means of the activation technique. Neutrons were produced at the Karlsruhe Van de Graaff accelerator via the 7Li(p,n)7Be reaction. For proton energies just above threshold, one obtains a neutron spectrum similar to a Maxwellian distribution for kT = 25 keV. This quasi-stellar neutron spectrum allowed us to measure the Maxwellian averaged cross sections directly. The experimental results of 174,176Yb, 184,186W, 190,192Os, 196,198Pt, and 202Hg were extrapolated from kT = 25 keV to lower and higher temperatures. [ABSTRACT FROM AUTHOR]

Published
2010
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22. KADoNiS-p: The Astrophysical p-Process Database.

Author

Szücs, T., Dillmann, I., Plag, R., and Fülöp, Zs.

Subjects
*NUCLEAR astrophysics, *NUCLEAR cross sections, *NUCLEOSYNTHESIS, *NUCLEAR physics experiments, *NUCLEAR reactions
Abstract

The KADoNiS-p project is an online database for cross sections relevant to the p-process. All existing experimental data was collected and reviewed. With this contribution a user-friendly database using the KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars) framework is launched, including all available experimental data from (p,&#947), (p,n), (p,α), (α,&#947), (α,n) and (α,p) reactions in or close to the respective Gamow window with cut-off date of August 2012 (http://www.kadonis.org/pprocess). [ABSTRACT FROM AUTHOR]

Published
2014
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23. First Experimental Constraint on the 59Fe(w,γ)60Fe Reaction Cross Section at Astrophysical Energies via the Coulomb Dissociation of 60Fe.

Author

Uberseder, E., Adachi, T., Aumann, T., Beceiro-Novo, S., Boretzky, K., Caesar, C., Dillmann, I., Ershova, O., Estrade, A., Farinon, E., Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Holl, M., Ignatov, A., Johansson, H. T., Kalantar, N., Langer, C., and Le Bleis, T.

Subjects
*RADIOISOTOPES, *NUCLEAR astrophysics, *GALACTIC dynamics, *NUCLEOSYNTHESIS, *COULOMB functions
Abstract

The radionuclide 60Fe has been of great interest to the nuclear astrophysics community for over a decade. An initial discrepancy between the observed and modeled Galactic 60Fe/26Al ratio motivated numerous studies focused on the nucleosynthesis of these two isotopes, though the cross section of the primary astrophysical production reaction, 59Fe(n, γ)60Fe, has remained purely theoretical. The present work offers a first experimental constraint on the 59Fe(n, γ)60Fe cross section at astrophysical energies, obtained indirectly via Coulomb dissociation, and demonstrates that the theoretical reaction rates used in present stellar models are not highly erroneous. [ABSTRACT FROM AUTHOR]

Published
2014
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24. What are the astrophysical sites for the -process and the production of heavy elements?

Author

Thielemann, F.-K., Arcones, A., Käppeli, R., Liebendörfer, M., Rauscher, T., Winteler, C., Fröhlich, C., Dillmann, I., Fischer, T., Martinez-Pinedo, G., Langanke, K., Farouqi, K., Kratz, K.-L., Panov, I., and Korneev, I.K.

Subjects
*ASTROPHYSICS, *HEAVY elements, *NUCLEOSYNTHESIS, *SUPERNOVAE, *HEAVY nuclei, *PHOTONUCLEAR reactions
Abstract

Abstract: This article addresses three of the four nucleosynthesis processes involved in producing heavy nuclei beyond Fe (with a main focus on the -process). Opposite to the fourth process (the -process), which operates in stellar evolution during He- and C-burning, they are all related to explosive burning phases, (presumably) linked to core collapse supernova events of massive stars. The (classical) -process is identified with explosive Ne/O-burning in outer zones of the progenitor star. It is initiated by the passage of the supernova shock wave and acts via photodisintegration reactions like a spallation process which produces neighboring (proton-rich) isotopes from pre-existing heavy nuclei. The reproduction of some of the so-called lighter -isotopes with faces problems in this environment. The only recently discovered -process is related to the innermost ejecta, the neutrino wind expelled from the hot proto-neutron star after core collapse and the supernova explosion. This neutrino wind is proton-rich in its early phase, producing nuclei up to 64Ge. Reactions with neutrinos permit to overcome decay/reaction bottlenecks for the flow beyond 64Ge, thus producing light -isotopes, which face problems in the classical -process scenario. The understanding of the -process, being identified for a long time with rapid neutron captures and passing through nuclei far from stability, is still experiencing major problems. These are on the one hand related to nuclear uncertainties far from stability (masses, half-lives, fission barriers), affecting the process speed and abundance peaks. On the other hand the site is still not definitely located, yet. (i) Later, possibly neutron-rich, high entropy phases of the neutrino wind (if they materialize!) could permit its operation. (ii) Other options include the ejection of very neutron-rich neutron star-like matter, occurring possibly in neutron star mergers or core collapse supernova events with jets, related to prior stellar evolution with high rotation rates and magnetic fields. Two different environments are required for a weak and a main/strong -process, witnessed by observations of low metallicity stars and meteoritic inclusions, which could possibly be identified with the two options listed above, i.e. the weak -process could be related to the neutrino wind when changing from -rich to -rich conditions. [Copyright &y& Elsevier]

Published
2011
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25. Production of intermediate-mass and heavy nuclei

Author

Thielemann, F.-K., Fröhlich, C., Hirschi, R., Liebendörfer, M., Dillmann, I., Mocelj, D., Rauscher, T., Martinez-Pinedo, G., Langanke, K., Farouqi, K., Kratz, K.-L., Pfeiffer, B., Panov, I., Nadyozhin, D.K., Blinnikov, S., Bravo, E., Hix, W.R., Höflich, P., and Zinner, N.T.

Subjects
*CHEMICAL elements, *COSMOCHEMISTRY, *NUCLEOSYNTHESIS, *STAR formation
Abstract

Abstract: Nucleosynthesis is the science related to all astrophysical processes which are responsible for the abundances of the elements and their isotopes in the universe. The astrophysical sites are the big bang and stellar objects. The working of nucleosynthesis processes is presented in a survey of events which act as abundance sources. For intermediate-mass and heavy elements, these are stellar evolution, type Ia and core collapse supernovae as well as hypernovae. We discuss successes and failures of existing processes and possible solutions via new (hitherto unknown) processes. Finally an analysis of their role is given in the puzzle to explain the evolution of the elemental and isotopic compositions found in galaxies, and especially the mixture found in the solar system. Different timescales due to the progenitor mass dependence of the endpoints of stellar evolution (type II supernova explosions — SNe II vs. planetary nebulae) or single vs. binary stellar systems (the latter being responsible for novae, type Ia supernovae — SNe Ia, or X-ray bursts) are the keys to understand galactic evolution. At very early times, the role of explosion energies of events, polluting pristine matter with a composition originating only from the big bang, might also play a role. We also speculate on the role of very massive stars not undergoing SN II explosions but rather causing “hypernovae” after the formation of a central black hole via core collapse. [Copyright &y& Elsevier]

Published
2007
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26. β-decay and β-delayed Neutron Emission Measurements at GSI-FRS Beyond N=126, for r-process Nucleosynthesis.

Author

Caballero-Folch, R., Domingo-Pardo, C., Cortès, G., Taín, J. L., Agramunt, J., Algora, A., Ameil, F., Ayyad, Y., Benlliure, J., Bowry, M., Calviño, F., Cano-Ott, D., Davinson, T., Dillmann, I., Estrade, A., Evdokimov, A., Faestermann, T., Farinon, F., Galaviz, D., and García-Ríos, A.

Subjects
*BETA decay, *NEUTRON emission, *NEUTRON temperature, *NUCLEOSYNTHESIS, *NEUTRON measurement, *MERCURY isotopes
Abstract

New measurements of very exotic nuclei in the neutron-rich region beyond N=126 have been performed at the GSI facility with the fragment separator (FRS). The aim of the experiment is to determine half-lives and β-delayed neutron emission branching ratios of isotopes of Hg, Tl and Pb in this region. This contribution summarizes final counting statistics for identification and for implantation, as well as the present status of the data analysis of the half-lives. In summary, isotopes of Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn and Fr were clearly identified and several of them (208-211Hg, 211-215Tl, 214-218Pb) were implanted with enough statistics to determine their half-lives. About half of them are expected to be neutron emitters, in such cases it will become possible to obtain the neutron emission probabilities, Pn. [ABSTRACT FROM AUTHOR]

Published
2014
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27. Accelerator mass spectrometry measurements of the 13C(n,γ)14C and 14N(n,p)14C cross sections.

Author

Wallner, A., Bichler, M., Buczak, K., Dillmann, I., Käppeler, F., Karakas, A., Lederer, C., Lugaro, M., Mair, K., Mengoni, A., Schätzel, G., Steier, P., and Trautvetter, H. P.

Subjects
*ACCELERATOR mass spectrometry, *NUCLEAR astrophysics, *NUCLEOSYNTHESIS
Abstract

The technique of accelerator mass spectrometry (AMS), offering a complementary tool for sensitive studies of key reactions in nuclear astrophysics, was applied for measurements of the 13C(n,γ)14C and the 14N(n,p)14C cross sections, which act as a neutron poison in s-process nucleosynthesis. Solid samples were irradiated at Karlsruhe Institute of Technology with neutrons closely resembling a Maxwell-Boltzmann distribution for kT=25 keV, and also at higher energies between En=123 and 182 keV. After neutron irradiation the produced amount of 14C in the samples was measured by AMS at the Vienna environmental Research Accelerator (VERA) facility. For both reactions the present results provide important improvements compared to previous experimental data, which were strongly discordant in the astrophysically relevant energy range and missing for the comparably strong resonances above 100 keV. For 13C(n,γ) we find a four times smaller cross section around kT=25 keV than a previous measurement. For 14N(n,p), the present data suggest two times lower cross sections between 100 and 200 keV than had been obtained in previous experiments and data evaluations. The effect of the new stellar cross sections on the s process in low-mass asymptotic giant branch stars was studied for stellar models of 2M⊙ initial mass, and solar and 1/10th solar metallicity. [ABSTRACT FROM AUTHOR]

Published
2016
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