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1. Direct measurements of low-energy resonance strengths of the 23Na(p,γ)24Mg reaction for astrophysics

Author

A. Boeltzig, A. Best, F.R. Pantaleo, G. Imbriani, M. Junker, M. Aliotta, J. Balibrea-Correa, D. Bemmerer, C. Broggini, C.G. Bruno, R. Buompane, A. Caciolli, F. Cavanna, T. Chillery, G.F. Ciani, P. Corvisiero, L. Csedreki, T. Davinson, R.J. deBoer, R. Depalo, A. Di Leva, Z. Elekes, F. Ferraro, E.M. Fiore, A. Formicola, Zs. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, I. Kochanek, M. Lugaro, P. Marigo, R. Menegazzo, V. Mossa, F. Munnik, V. Paticchio, R. Perrino, D. Piatti, P. Prati, L. Schiavulli, K. Stöckel, O. Straniero, F. Strieder, T. Szücs, M.P. Takács, D. Trezzi, M. Wiescher, and S. Zavatarelli

Subjects
Physics, QC1-999
Abstract

The NeNa and the MgAl cycles play a fundamental role in the nucleosynthesis of asymptotic giant branch stars undergoing hot bottom burning. The Na23(p,γ)24Mg reaction links these two cycles and a precise determination of its rate is required to correctly estimate the contribution of these stars to the chemical evolution of various isotopes of Na, Mg and Al. At temperatures of 50≲T≲110MK, narrow resonances at Ep=140 and 251keV are the main contributors to the reaction rate, in addition to the direct capture that dominates in the lower part of the temperature range. We present new measurements of the strengths of these resonances at the Laboratory for Underground Nuclear Astrophysics (LUNA). We have used two complementary detection approaches: high efficiency with a 4π BGO detector for the 140keV resonance, and high resolution with a HPGe detector for the 251keV resonance. Thanks to the reduced cosmic ray background of LUNA, we were able to determine the resonance strength of the 251keV resonance as ωγ=482(82)μeV and observed new gamma ray transitions for the decay of the corresponding state in Mg24 at Ex=11931keV. With the highly efficient BGO detector, we observed a signal for the 140keV resonance for the first time in a direct measurement, resulting in a strength of ωγ140=1.46−0.53+0.58neV (68% CL). Our measurement reduces the uncertainty of the Na23(p,γ)24Mg reaction rate in the temperature range from 0.05 to 0.1GK to at most −35%+50% at 0.07GK. Accordingly, our results imply a significant reduction of the uncertainties in the nucleosynthesis calculations. Keywords: Experimental nuclear astrophysics, Underground nuclear physics, Hydrogen burning, Stellar evolution

Published
2019
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2. Improved astrophysical rate for the 18O(p,α)15N reaction by underground measurements

Author

C.G. Bruno, M. Aliotta, P. Descouvemont, A. Best, T. Davinson, D. Bemmerer, A. Boeltzig, C. Broggini, A. Caciolli, F. Cavanna, T. Chillery, G.F. Ciani, P. Corvisiero, R. Depalo, A. Di Leva, Z. Elekes, F. Ferraro, A. Formicola, Zs. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, G. Imbriani, M. Junker, M. Lugaro, P. Marigo, R. Menegazzo, V. Mossa, F.R. Pantaleo, D. Piatti, P. Prati, K. Stöckel, O. Straniero, F. Strieder, T. Szücs, M.P. Takács, and D. Trezzi

Subjects
Physics, QC1-999
Abstract

The 18O(p,α)15N reaction affects the synthesis of 15N, 18O and 19F isotopes, whose abundances can be used to probe the nucleosynthesis and mixing processes occurring deep inside asymptotic giant branch (AGB) stars. We performed a low-background direct measurement of the 18O(p,α)15N reaction cross-section at the Laboratory for Underground Nuclear Astrophysics (LUNA) from center of mass energy Ec.m.=340 keV down to Ec.m.=55 keV, the lowest energy measured to date corresponding to a cross-section of less than 1 picobarn/sr. The strength of a key resonance at center of mass energy Er=90 keV was found to be a factor of 10 higher than previously reported. A multi-channel R-matrix analysis of our and other data available in the literature was performed. Over a wide temperature range, T=0.01–1.00 GK, our new astrophysical rate is both more accurate and precise than recent evaluations. Stronger constraints can now be placed on the physical processes controlling nucleosynthesis in AGB stars with interesting consequences on the abundance of 18O in these stars and in stardust grains, specifically on the production sites of oxygen-rich Group II grains. Keywords: Stellar hydrogen burning, Hydrostatic stellar nucleosynthesis

Published
2019
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3. Cross section of the reaction 18O(p,γ)19F at astrophysical energies: The 90 keV resonance and the direct capture component

Author

A. Best, F.R. Pantaleo, A. Boeltzig, G. Imbriani, M. Aliotta, J. Balibrea-Correa, D. Bemmerer, C. Broggini, C.G. Bruno, R. Buompane, A. Caciolli, F. Cavanna, T. Chillery, G.F. Ciani, P. Corvisiero, L. Csedreki, T. Davinson, R.J. deBoer, R. Depalo, A. Di Leva, Z. Elekes, F. Ferraro, E.M. Fiore, A. Formicola, Zs. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, M. Junker, I. Kochanek, M. Lugaro, P. Marigo, R. Menegazzo, V. Mossa, V. Paticchio, R. Perrino, D. Piatti, P. Prati, L. Schiavulli, K. Stöckel, O. Straniero, F. Strieder, T. Szücs, M.P. Takács, D. Trezzi, M. Wiescher, and S. Zavatarelli

Subjects
Physics, QC1-999
Abstract

The observation of oxygen isotopes in giant stars sheds light on mixing processes operating in their interiors. Due to the very strong correlation between nuclear burning and mixing processes it is very important to reduce the uncertainty on the cross sections of the nuclear reactions that are involved. In this paper we focus our attention on the reaction O18(p,γ)19F. While the O18(p,α)15N channel is thought to be dominant, the (p,γ) channel can still be an important component in stellar burning in giants, depending on the low energy cross section. So far only extrapolations from higher-energy measurements exist and recent estimates vary by orders of magnitude. These large uncertainties call for an experimental reinvestigation of this reaction. We present a direct measurement of the O18(p,γ)19F cross section using a high-efficiency 4π BGO summing detector at the Laboratory for Underground Nuclear Astrophysics (LUNA). The reaction cross section has been directly determined for the first time from 140 keV down to 85 keV and the different cross section components have been obtained individually. The previously highly uncertain strength of the 90 keV resonance was found to be 0.53 ± 0.07 neV, three orders of magnitude lower than an indirect estimate based on nuclear properties of the resonant state and a factor of 20 lower than a recently established upper limit, excluding the possibility that the 90 keV resonance can contribute significantly to the stellar reaction rate. Keywords: Experimental nuclear astrophysics, Underground nuclear physics, Hydrogen burning, Stellar evolution

Published
2019
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4. Advances in radiative capture studies at LUNA with a segmented BGO detector

Author

J Skowronski, R M Gesuè, A Boeltzig, G F Ciani, D Piatti, D Rapagnani, M Aliotta, C Ananna, F Barile, D Bemmerer, A Best, C Broggini, C G Bruno, A Caciolli, M Campostrini, F Cavanna, P Colombetti, A Compagnucci, P Corvisiero, L Csedreki, T Davinson, R Depalo, A Di Leva, Z Elekes, F Ferraro, A Formicola, Zs Fülöp, G Gervino, A Guglielmetti, C Gustavino, Gy Gyürky, G Imbriani, M Junker, M Lugaro, P Marigo, E Masha, R Menegazzo, V Paticchio, R Perrino, P Prati, V Rigato, L Schiavulli, R S Sidhu, O Straniero, T Szücs, and S Zavatarelli

Subjects
Nuclear and High Energy Physics, gamma-ray total absorption spectroscopy, radiation shielding and background reduction, nuclear astrophysics experiment, activation measurement, segmented bismuth germanium oxide (BGO) detector, Settore FIS/04 - Fisica Nucleare e Subnucleare
Abstract

Studies of charged-particle reactions for low-energy nuclear astrophysics require high sensitivity, which can be achieved by means of detection setups with high efficiency and low backgrounds, to obtain precise measurements in the energy region of interest for stellar scenarios. High-efficiency total absorption spectroscopy is an established and powerful tool for studying radiative capture reactions, particularly if combined with the cosmic background reduction by several orders of magnitude obtained at the Laboratory for Underground Nuclear Astrophysics (LUNA). We present recent improvements in the detection setup with the Bismuth Germanium Oxide (BGO) detector at LUNA, aiming to reduce high-energy backgrounds and increase the summing detection efficiency. The new design results in enhanced sensitivity of the BGO setup, as we demonstrate and discuss in the context of the first direct measurement of the 65 keV resonance (E x = 5672 keV) of the 17O(p,γ)18F reaction. Moreover, we show two applications of the BGO detector, which exploit its segmentation. In the case of complex γ-ray cascades, e.g. the de-excitation of E x = 5672 keV in 18F, the BGO segmentation allows to identify and suppress the beam-induced background signals that mimic the sum peak of interest. We demonstrate another new application for such a detector in form of in situ activation measurements of a reaction with β + unstable product nuclei, e.g. the 14N(p,γ)15O reaction.

Published
2023
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5. The CARMENES search for exoplanets around M dwarfs: Rubidium abundances in nearby cool stars

Author

A. Kaminski, S. V. Jeffers, M. Lafarga, Mathias Zechmeister, C. Rodríguez López, Th. Henning, Carlos Abia, A. Lopez-Gallifa, Andreas Quirrenbach, S. A. Korotin, V. M. Passegger, Andreas Schweitzer, Emilio Marfil, Juan Carlos Morales, Nikos Prantzos, Ansgar Reiners, Stefan Dreizler, Víctor J. S. Béjar, Evangelos Nagel, Hugo M. Tabernero, P. J. Amado, J. A. Caballero, D. Montes, O. Straniero, Martin Kürster, S. Pedraz, Ignasi Ribas, M. Cortés-Contreras, Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709, Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548, López Gallifa, A. [0000-0001-6049-9366], Tabernero, H. [0000-0002-8087-4298], Montes, D. [0000-0002-7779-238X], Korotin, S. [0000-0002-4058-8780], Fundacao para a Ciencia e a Tecnologia (FCT), Generalitat de Catalunya, National Aeronautics and Space Administration (NASA), Agencia Estatal de Investigación (AEI), Ministerio de Ciencia e Innovación (España), European Commission, Universidad Complutense de Madrid, Fundação para a Ciência e a Tecnologia (Portugal), National Aeronautics and Space Administration (US), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), European Regional Development Fund (ERDF), FICTS-2011-02 ICTS-2017-07-CAHA-4 CAHA16-CE-3978, and Deutsche Forschungsgemeinschaft (DFG) through Research Unit 'Blue Planets around Red Stars'

Subjects
Astrofísica, Solar System, Metallicity, FOS: Physical sciences, chemistry.chemical_element, Astrophysics, Stars: late-type, 7. Clean energy, 01 natural sciences, Rubidium, late type [Stars], Abundance (ecology), Nucleosynthesis, 0103 physical sciences, Abundances, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Physics, 010308 nuclear & particles physics, Stars: abundances, Astronomy and Astrophysics, Exoplanet, Galaxy, Astronomía, Stars, Astrophysics - Solar and Stellar Astrophysics, chemistry, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, late-type [Stars], abundances [Stars], Nuclear reactions
Abstract

Due to their ubiquity and very long main-sequence lifetimes, abundance determinations in M dwarfs provide a powerful and alternative tool to GK dwarfs to study the formation and chemical enrichment history of our Galaxy. In this study, abundances of the neutron-capture elements Rb, Sr, and Zr are derived, for the first time, in a sample of nearby M dwarfs. We focus on stars in the metallicity range-0.5 ≲ [Fe/H] ≲ +0.3, an interval poorly explored for Rb abundances in previous analyses. To do this we use high-resolution, high-signal-to-noise-ratio, optical and near-infrared spectra of 57 M dwarfs observed with CARMENES. The resulting [Sr/Fe] and [Zr/Fe] ratios for most M dwarfs are almost constant at about the solar value, and are identical to those found in GK dwarfs of the same metallicity. However, for Rb we find systematic underabundances ([Rb/Fe] < 0.0) by a factor two on average. Furthermore, a tendency is found for Rb-but not for other heavy elements (Sr, Zr)-to increase with increasing metallicity such that [Rb/Fe] ≳ 0.0 is attained at metallicities higher than solar. These are surprising results, never seen for any other heavy element, and are difficult to understand within the formulation of the s-and r-processes, both contributing sources to the Galactic Rb abundance. We discuss the reliability of these findings for Rb in terms of non-LTE (local thermodynamic equilibrium) effects, stellar activity, or an anomalous Rb abundance in the Solar System, but no explanation is found. We then interpret the full observed [Rb/Fe] versus [Fe/H] trend within the framework of theoretical predictions from state-of-the-art chemical evolution models for heavy elements, but a simple interpretation is not found either. In particular, the possible secondary behaviour of the [Rb/Fe] ratio at super-solar metallicities would require a much larger production of Rb than currently predicted in AGB stars through the s-process without overproducing Sr and Zr. © 2020 ESO., CARMENES is an instrument for the Centro Astronomico Hispano-Aleman (CAHA) at Calar Alto (Almeria, Spain), operated jointly by the Junta de Andalucia and the Instituto de Astrofisica de Andalucia (CSIC). CARMENES was funded by the Max-Planck-Gesellschaft (MPG), the Consejo Superior de Investigaciones Cientificas (CSIC), the Ministerio de Economia y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through projects FICTS-2011-02, ICTS-2017-07-CAHA-4, and CAHA16-CE-3978, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the MINECO, the Deutsche Forschungsgemeinschaft through the Major Research Instrumentation Programme and Research Unit FOR2544 "Blue Planets around Red Stars", the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. We acknowledge financial support from the Agencia Estatal de Investigacion of the Ministerio de Ciencia e Innovacion, the Universidad Complutense de Madrid, the Fundacao para a Ciencia e a Tecnologia, the Generalitat de Catalunya, ERDF, and NASA through projects PGC2018-095317-B-C21, PID2019-109522GB-C51/2/3/4, PGC2018-098153-B-C33, AYA2016-79425-C3[1,2,3]-P, FPU15/01476, UID[B,P]/04434/2020, PTDC/FIS-AST/28953/2017, POCI-01-0145-FEDER-028953, SEV-2015-0548, SEV-2017-0709, MDM-20170737, NNX17AG24G, and the CERCA programme.

Published
2020
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6. Erratum: Three New Low-Energy Resonances in the ^{22}Ne(p,γ)^{23}Na Reaction [Phys. Rev. Lett. 115, 252501 (2015)]

Author

F, Cavanna, R, Depalo, M, Aliotta, M, Anders, D, Bemmerer, A, Best, A, Boeltzig, C, Broggini, C G, Bruno, A, Caciolli, P, Corvisiero, T, Davinson, A, di Leva, Z, Elekes, F, Ferraro, A, Formicola, Zs, Fülöp, G, Gervino, A, Guglielmetti, C, Gustavino, Gy, Gyürky, G, Imbriani, M, Junker, R, Menegazzo, V, Mossa, F R, Pantaleo, P, Prati, D A, Scott, E, Somorjai, O, Straniero, F, Strieder, T, Szücs, M P, Takács, and D, Trezzi

Abstract

This corrects the article DOI: 10.1103/PhysRevLett.115.252501.

Published
2018

7. Underground study of the O17(p,g)F18 reaction relevant for explosive hydrogen burning

Author

DI LEVA, ANTONINO, D. A. Scott, A. Caciolli, A. Formicola, F. Strieder, M. Aliotta, M. Anders, D. Bemmerer, C. Broggini, P. Corvisiero, Z. Elekes, Z.s. F?l?p, G. Gervino, A. Guglielmetti, C. Gustavino, G.y. Gy?rky, IMBRIANI, GIANLUCA, J. Jos?, M. Junker, M. Laubenstein, R. Menegazzo, E. Napolitani, P. Prati, V. Rigato, ROCA, VINCENZO, E. Somorjai, C. Salvo, O. Straniero, T. Sz?cs, F. Terrasi, D. Trezzi, DI LEVA, Antonino, D. A., Scott, A., Caciolli, A., Formicola, F., Strieder, M., Aliotta, M., Ander, D., Bemmerer, C., Broggini, P., Corvisiero, Z., Eleke, F?l?p, Z. s., G., Gervino, A., Guglielmetti, C., Gustavino, Gy?rky, G. y., Imbriani, Gianluca, J., Jos?, M., Junker, M., Laubenstein, R., Menegazzo, E., Napolitani, P., Prati, V., Rigato, Roca, Vincenzo, E., Somorjai, C., Salvo, O., Straniero, T., Sz?c, F., Terrasi, and D., Trezzi

Subjects
Nuclear Astrophysic, underground measurement, Experimental Nuclear Physics
Abstract

Background: The O17(p,γ)F18 reaction affects the production of key isotopes (e.g., F18 and O18) in the explosive hydrogen burning that powers classical novae. Under these explosive conditions, the reaction rate is dominated by contributions from a narrow resonance at Ec.m.=183keV and by the combined contributions of direct capture and low-energy tails of broad resonances. At present, the astrophysical reaction rate is not well constrained because of the lack of data in the energy region appropriate to classical novae. Purpose: This study aims at the measurement of the O17(p,γ)F18 reaction cross section in order to determine its reaction rate in the temperature region appropriate to explosive hydrogen burning in novae. Method: The O17(p,γ)F18 reaction cross section was measured using both the prompt detection of the emitted γ rays and an activation technique. Measurements were carried out at the Laboratory for Underground Nuclear Astrophysics (Gran Sasso, Italy) where the strongly reduced cosmic-ray-induced background allows for improved sensitivity compared to previous studies. Results: The O17(p,γ)F18 reaction cross section was measured in the range Ec.m.=160 to 370keV. The strength of the Ec.m.=183keV resonance, ωγ=1. 67±0.12μeV, was determined with unprecedented precision. The total S factor was obtained through a combined fit of prompt γ-ray and activation results. An overall global fit including other existing data sets was also carried out and a recommended astrophysical reaction rate is presented. Conclusions: The reaction rate uncertainty attained in this work is now below the required precision for nova models. We verified, following a full set of hydrodynamic nova models, that the abundances of oxygen and fluorine isotopes obtained with the present reaction rate are determined with 10% precision and put firmer constraints on observational signatures of novae events.

Published
2014

8. Impact of a revised 25Mg(p, γ)26Al reaction rate on the operation of the Mg-Al cycle

Author

O. Straniero, G. Imbriani, F. Strieder, D. Bemmerer, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, S. Cristallo, A. Dileva, A. Formicola, Elekes Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, M. Junker, A. Lemut, B. Limata, M. Marta, C. Mazzocchi, R. Menegazzo, L. Piersanti, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, H. P. Trautvetter, H. P., TERRASI, Filippo, O., Straniero, G., Imbriani, F., Strieder, D., Bemmerer, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, S., Cristallo, A., Dileva, A., Formicola, Elekes Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, M., Junker, A., Lemut, B., Limata, M., Marta, C., Mazzocchi, R., Menegazzo, L., Piersanti, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, Terrasi, Filippo, H. P., Trautvetter, and H., P.

Published
2013

9. First Direct Measurement of the ^{17}O(p,\gamma)^{18}F Reaction Cross-Section at Gamow Energies for Classical Novae

Author

D. A. Scott, A. Caciolli, A. Formicola, M. Aliotta, M. Anders, D. Bemmerer, C. Broggini, M. Campeggio, P. Corvisiero, Z. Elekes, Z.s. Fulop, G. Gervino, A. Guglielmetti, C. Gustavino, G.y. Gyurky, M. Junker, M. Laubenstein, R. Menegazzo, M. Marta, E. Napolitani, P. Prati, V. Rigato, E. Somorjai, C. Salvo, O. Straniero, F. Strieder, T. Szus, F. Terrasi, D. Trezzi, DI LEVA, ANTONINO, IMBRIANI, GIANLUCA, ROCA, VINCENZO, D. A., Scott, A., Caciolli, DI LEVA, Antonino, A., Formicola, M., Aliotta, M., Ander, D., Bemmerer, C., Broggini, M., Campeggio, P., Corvisiero, Z., Eleke, Fulop, Z. s., G., Gervino, A., Guglielmetti, C., Gustavino, Gyurky, G. y., Imbriani, Gianluca, M., Junker, M., Laubenstein, R., Menegazzo, M., Marta, E., Napolitani, P., Prati, V., Rigato, Roca, Vincenzo, E., Somorjai, C., Salvo, O., Straniero, F., Strieder, T., Szu, F., Terrasi, and D., Trezzi

Subjects
Nuclear astrophysic, Proton-capture reaction, Astrophysics - Solar and Stellar Astrophysics, Reaction rate, CNO cycle, Nuclear Experiment
Abstract

Classical novae are important contributors to the abundances of key isotopes, such as the radioactive ^{18}F, whose observation by satellite missions could provide constraints on nucleosynthesis models in novae. The ^{17}O(p,\gamma)^{18}F reaction plays a critical role in the synthesis of both oxygen and fluorine isotopes but its reaction rate is not well determined because of the lack of experimental data at energies relevant to novae explosions. In this study, the reaction cross section has been measured directly for the first time in a wide energy range Ecm = 200 - 370 keV appropriate to hydrogen burning in classical novae. In addition, the E=183 keV resonance strength, \omega \gamma=1.67\pm0.12 \mueV, has been measured with the highest precision to date. The uncertainty on the ^{17}O(p,\gamma)^{18}F reaction rate has been reduced by a factor of 4, thus leading to firmer constraints on accurate models of novae nucleosynthesis., Comment: accepted by Phys. Rev. Lett

Published
2012

10. The 25Mg(p, γ) 26Al reaction at low astrophysical energies.Physics Letters B707(2012)60

Author

F. Strieder, B. Limata, A. Formicola, G. Imbriani, M. Junker, D. Bemmerer, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, A. DiLeva, Z. Elekes, Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, A. Lemut, M. Marta, C. Mazzocchi, R. Menegazzo, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, H. P. Trautvetter, TERRASI, Filippo, F., Strieder, B., Limata, A., Formicola, G., Imbriani, M., Junker, D., Bemmerer, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, A., Dileva, Z., Eleke, Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, A., Lemut, M., Marta, C., Mazzocchi, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, O., Straniero, Terrasi, Filippo, and H. P., Trautvetter

Published
2012

11. The 14N( p,γ )15O reaction studied with a composite germanium detector

Author

M. Marta, A. Formicola, D. Bemmerer, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, Z. Elekes, Z.s. Fulop, G. Gervino, A. Guglielmetti, C. Gustavino, G.y. Gyurky, M. Junker, A. Lemut, B. Limata, C. Mazzocchi, R. Menegazzo, P. Prati, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, H. P. Trautvetter, A. Vomiero, IMBRIANI, GIANLUCA, ROCA, VINCENZO, M., Marta, A., Formicola, D., Bemmerer, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, Z., Eleke, Fulop, Z. s., G., Gervino, A., Guglielmetti, C., Gustavino, Gyurky, G. y., Imbriani, Gianluca, M., Junker, A., Lemut, B., Limata, C., Mazzocchi, R., Menegazzo, P., Prati, Roca, Vincenzo, C., Rolf, C., Rossi Alvarez, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, H. P., Trautvetter, and A., Vomiero

Subjects
Fisica Nucleare Sperimentale, Spettroscopia Gamma, Astrofisica Nucleare
Abstract

The rate of the carbon-nitrogen-oxygen (CNO) cycle of hydrogen burning is controlled by the 14N(p,γ )15O reaction. The reaction proceeds by capture to the ground states and several excited states in 15O. In order to obtain a reliable extrapolation of the excitation curve to astrophysical energy, fits in the R-matrix framework are needed. In an energy range that sensitively tests such fits, new cross-section data are reported here for the four major transitions in the 14N(p,γ )15O reaction. The experiment has been performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400-kV accelerator placed deep underground in the Gran Sasso facility in Italy. Using a composite germanium detector, summing corrections have been considerably reduced with respect to previous studies. The cross sections for capture to the ground state and to the 5181, 6172, and 6792 keV excited states in 15O have been determined at 359, 380, and 399 keV beam energy. In addition, the branching ratios for the decay of the 278-keV resonance have been remeasured.

Published
2011

12. Revision of the 15N(p, γ)16O reaction rate and oxygen abundance in H-burning zones Astronomy & Astrophysics 533(2011)

Author

A. Caciolli, C. Mazzocchi, V. Capogrosso, D. Bemmerer, C. Broggini, P. Corvisiero, H. Costantini, Z. Elekes, A. Formicola, Z.s. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G.y. Gyürky, G. Imbriani, M. Junker, A. Lemut, M. Marta, R. Menegazzo, S. Palmerini, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, F. Strieder, H. P. Trautvetter, A. Vomiero, TERRASI, Filippo, A., Caciolli, C., Mazzocchi, V., Capogrosso, D., Bemmerer, C., Broggini, P., Corvisiero, H., Costantini, Z., Eleke, A., Formicola, Fülöp, Z. s., G., Gervino, A., Guglielmetti, C., Gustavino, Gyürky, G. y., G., Imbriani, M., Junker, A., Lemut, M., Marta, R., Menegazzo, S., Palmerini, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, H. P., Trautvetter, and A., Vomiero

Subjects
stars: AGB and post-AGB – nuclear reactions, nucleosynthesis, abundances – novae – cataclysmic variables
Abstract

Context. The NO cycle takes place in the deepest layer of a H-burning core or shell, when the temperature exceeds T 30 × 106 K. The O depletion observed in some globular cluster giant stars, always associated with a Na enhancement, may be due to either a deep mixing during the red giant branch (RGB) phase of the star or to the pollution of the primordial gas by an early population of massive asymptotic giant branch (AGB) stars, whose chemical composition was modified by the hot bottom burning. In both cases, the NO cycle is responsible for the O depletion. Aims. The activation of this cycle depends on the rate of the 15N(p, γ)16O reaction. A precise evaluation of this reaction rate at temperatures as low as experienced in H-burning zones in stellar interiors is mandatory to understand the observed O abundances. Methods. We present a new measurement of the 15N(p, γ)16O reaction performed at LUNA covering for the first time the center of mass energy range 70−370 keV, which corresponds to stellar temperatures between 65 × 106 K and 780 × 106 K. This range includes the 15N(p, γ)16O Gamow-peak energy of explosive H-burning taking place in the external layer of a nova and the one of the hot bottom burning (HBB) nucleosynthesis occurring in massive AGB stars. Results. With the present data, we are also able to confirm the result of the previous R-matrix extrapolation. In particular, in the temperature range of astrophysical interest, the new rate is about a factor of 2 smaller than reported in the widely adopted compilation of reaction rates (NACRE or CF88) and the uncertainty is now reduced down to the 10% level.

Published
2011

13. The N14(p,γ)O15 reaction studied with a composite germanium detector Physical Review C83(2011)045804

Author

M. Marta, A. Formicola, D. Bemmerer, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, Z. Elekes, Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, G. Imbriani, M. Junker, A. Lemut, B. Limata, C. Mazzocchi, R. Menegazzo, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, F. Strieder, H. P. Trautvetter, A. Vomiero, TERRASI, Filippo, M., Marta, A., Formicola, D., Bemmerer, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, Z., Eleke, Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, G., Imbriani, M., Junker, A., Lemut, B., Limata, C., Mazzocchi, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, H. P., Trautvetter, and A., Vomiero

Published
2011

14. Constraining the S factor of N15(p,γ)O16 at astrophysical energies

Author

P. J. Leblanc, G. Imbriani, J. Görres, M. Junker, R. Azuma, M. Beard, D. Bemmerer, A. Best, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, M. Couder, R. Deboer, Z. Elekes, S. Falahat, A. Formicola, Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, F. Käppeler, A. Kontos, R. Kuntz, H. Leiste, A. Lemut, Q. Li, B. Limata, M. Marta, C. Mazzocchi, R. Menegazzo, S. O'Brien, A. Palumbo, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, E. Stech, O. Straniero, F. Strieder, W. Tan, H. P. Trautvetter, E. Uberseder, M. Wiescher, TERRASI, Filippo, P. J., Leblanc, G., Imbriani, J., Görre, M., Junker, R., Azuma, M., Beard, D., Bemmerer, A., Best, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, M., Couder, R., Deboer, Z., Eleke, S., Falahat, A., Formicola, Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, F., Käppeler, A., Konto, R., Kuntz, H., Leiste, A., Lemut, Q., Li, B., Limata, M., Marta, C., Mazzocchi, R., Menegazzo, S., O'Brien, A., Palumbo, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, E., Stech, O., Straniero, F., Strieder, W., Tan, Terrasi, Filippo, H. P., Trautvetter, E., Uberseder, and M., Wiescher

Published
2010

15. An actively vetoed Clover gamma-detector for nuclear astrophysics at LUNA. Eur. Phys. J. A44(2010)513-519

Author

T. SZUCS, D. BEMMERER, C. BROGGINI, A. CACIOLLI, F. CONFORTOLA, P. CORVISIERO, Z. ELEKES, A. FORMICOLA, Z.S. FULOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G.Y. GYURKY, G. IMBRIANI, M. JUNKER, A. LEMUT, M. MARTA, C. MAZZOCCHI, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, T., Szuc, D., Bemmerer, C., Broggini, A., Caciolli, F., Confortola, P., Corvisiero, Z., Eleke, A., Formicola, Fulop, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, Gyurky, G. Y., G., Imbriani, M., Junker, A., Lemut, M., Marta, C., Mazzocchi, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2010

16. NGC 1866: a milestone for understanding the chemical evolution of stellar populations in the Large Magellanic Cloud

Author

MUCCIARELLI, ALESSIO, S. Cristallo, E. Brocato, L. Pasquini, O. Straniero, E. Caffau, G. Raimondo, A. Kaufer, I. Musella, V. Ripepi, M. Romaniello, A. R. Walker, A. Mucciarelli, S. Cristallo, E. Brocato, L. Pasquini, O. Straniero, E. Caffau, G. Raimondo, A. Kaufer, I. Musella, V. Ripepi, M. Romaniello, and A. R. Walker

Subjects
Stars: abundance, Magellanic Cloud, Techniques: spectroscopic, Astrophysics::Cosmology and Extragalactic Astrophysics, Spectroscopic, Galaxies, Stars, Techniques, NGC 1866, Globular clusters, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Abundances, Large Magellanic Clouds (LMC), Globular clusters: individual: NGC 1866, Astrophysics::Galaxy Astrophysics
Abstract

We present new FLAMES@VLT spectroscopic observations of 30 stars in the field of the LMC stellar cluster NGC 1866. NGC 1866 is one of the few young and massive globular cluster that is close enough so that its stars can be individually studied in detail. Radial velocities have been used to separate stars belonging to the cluster and to the LMC field and the same spectra have been used to derive chemical abundances for a variety of elements, from [Fe/H] to the light (i.e. Na, O, Mg...) to the heavy ones. The average iron abundance of NGC 1866 turns out to be [Fe/H]= -0.43+-0.01 dex (with a dispersion of 0.04 dex), from the analysis of 14 cluster-member stars. Within our uncertainties, the cluster stars are homogeneous, as far as chemical composition is concerned, independent of the evolutionary status. The observed cluster stars do not show any sign of the light elements 'anti-correlation' present in all the Galactic globular clusters so far studied, and also found in the old LMC stellar clusters. A similar lack of anti-correlations has been detected in the massive intermediate-age LMC clusters, indicating a different formation/evolution scenario for the LMC massive clusters younger than ~3 Gyr with respect to the old ones. Also opposite to the Galactic globulars, the chemical composition of the older RGB field stars and of the young post-MS cluster stars show robust homogeneity suggesting a quite similar process of chemical evolution. The field and cluster abundances are in agreement with recent chemical analysis of LMC stars, which show a distinctive chemical pattern for this galaxy with respect to the Milky Way. We discuss these findings in light of the theoretical scenario of chemical evolution of the LMC., Part of this work has been supported by the Spanish Ministry of Science and Innovation projects AYA2008-04211-C02-02.

Published
2010

17. New experimental study of low-energy (p,γ) resonances in magnesium isotopes. Phys. Rev. C82(2010)015801

Author

B. LIMATA, F. STRIEDER, A. FORMICOLA, G. IMBRIANI, M. JUNKER, H. W. BECKER, D. BEMMERER, A. BEST, R. BONETTI, C. BROGGINI, A. CACIOLLI, P. CORVISIERO, H. COSTANTINI, A. DILEVA, Z. ELEKES, Z.S. FÜLÖP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G.Y. GYÜRKY, A. LEMUT, M. MARTA, C. MAZZOCCHI, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, C. SALVO, E. SOMORJAI, O. STRANIERO, AND H. P. TRAUTVETTER, TERRASI, Filippo, B., Limata, F., Strieder, A., Formicola, G., Imbriani, M., Junker, H. W., Becker, D., Bemmerer, A., Best, R., Bonetti, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, A., Dileva, Z., Eleke, Fülöp, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, Gyürky, G. Y., A., Lemut, M., Marta, C., Mazzocchi, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, C., Salvo, E., Somorjai, O., Straniero, Terrasi, Filippo, and AND H. P., Trautvetter

Published
2010

18. First direct measurement of the H 2 (α,γ) Li 6 cross section at big bang energies and the primordial lithium problem

Author

M, Anders, D, Trezzi, R, Menegazzo, M, Aliotta, A, Bellini, D, Bemmerer, C, Broggini, A, Caciolli, P, Corvisiero, H, Costantini, T, Davinson, Z, Elekes, M, Erhard, A, Formicola, Zs, Fülöp, G, Gervino, A, Guglielmetti, C, Gustavino, Gy, Gyürky, M, Junker, A, Lemut, M, Marta, C, Mazzocchi, P, Prati, C, Rossi Alvarez, D A, Scott, E, Somorjai, O, Straniero, and T, Szücs

Subjects
LUNA, Underground nuclear astrophysics, Physics and Astronomy (all), nuclear astrophysics, fisica underground, big-bang nucleosynthesis, Big Bang nucleosynthesis
Abstract

Recent observations of (6)Li in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the (2)H(α,γ)(6)Li reaction dominates (6)Li production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles (2)H and α at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of (6)Li only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the (2)H(α,γ)(6)Li cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial (6)Li/(7)Li isotopic abundance ratio has been determined to be (1.5 ± 0.3) × 10(-5), from our experimental data and standard BBN theory. The much higher (6)Li/(7)Li values reported for halo stars will likely require a nonstandard physics explanation, as discussed in the literature.

Published
2014

19. Precision study of ground state capture in the 14N(p,g)15O reaction

Author

M. Marta, A. Formicola, Gy Gyurky, D. Bemmerer, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, Z. Elekes, Z.s. Fulop, G. Gervino, A. Guglielmetti, C. Gustavino, M. Junker, R. Kunz, A. Lemut, C. Mazzocchi, R. Menegazzo, P. Prati, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, H. P. Trautvetter, IMBRIANI, GIANLUCA, LIMATA, BENEDICTA NORMANNA, ROCA, VINCENZO, ROMANO, MARIO, M., Marta, A., Formicola, Gy, Gyurky, D., Bemmerer, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, Z., Eleke, Fulop, Z. s., G., Gervino, A., Guglielmetti, C., Gustavino, Imbriani, Gianluca, M., Junker, R., Kunz, A., Lemut, Limata, BENEDICTA NORMANNA, C., Mazzocchi, R., Menegazzo, P., Prati, Roca, Vincenzo, C., Rolf, Romano, Mario, C., Rossi Alvarez, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, and H. P., Trautvetter

Abstract

The rate of the hydrogen-burning carbon-nitrogen-oxygen (CNO) cycle is controlled by the slowest process, 14N(p,γ )15O, which proceeds by capture to the ground and several excited states in 15O. Previous extrapolations for the ground state contribution disagreed by a factor 2, corresponding to 15% uncertainty in the total astrophysical S factor. At the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator placed deep underground in the Gran Sasso facility in Italy, a new experiment on ground state capture has been carried out at 317.8, 334.4, and 353.3 keV center-of-mass energy. Systematic corrections have been reduced considerably with respect to previous studies by using a Clover detector and by adopting a relative analysis. The previous discrepancy has been resolved, and ground state capture no longer dominates the uncertainty of the total S factor.

Published
2008

20. The 3He(α,γ)7Be S-factor at solar energies: the prompt &gamma experiment at LUNA

Author

H. COSTANTINI, D. BEMMERER, F. CONFORTOLA, A. FORMICOLA, G.Y. GYURKY, P. BEZZON, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z.S. FULOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, V. LOZZA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, H., Costantini, D., Bemmerer, F., Confortola, A., Formicola, Gyurky, G. Y., P., Bezzon, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Fulop, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, V., Lozza, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2008

21. 3He(alpha,gamma)7Be cross section at low energies

Author

G.Y. GYÜRKY, F. CONFORTOLA, H. COSTANTINI, A. FORMICOLA, D. BEMMERER, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z.S. FÜLÖP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER, LOZZA, VALENTINA, Gyürky, G. Y., F., Confortola, H., Costantini, A., Formicola, D., Bemmerer, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Fülöp, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, Lozza, Valentina, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, and H. P., Trautvetter

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Astrophysics, Nuclear Experiment
Abstract

The flux of 7Be and 8B neutrinos from the Sun and the production of 7Li via primordial nucleosynthesis depend on the rate of the 3He(alpha,gamma)7Be reaction. In extension of a previous study showing cross section data at 127 - 167 keV center of mass energy, the present work reports on a measurement of the 3He(alpha,gamma)7Be cross section at 106 keV performed at Italy's Gran Sasso underground laboratory by the activation method. This energy is closer to the solar Gamow energy than ever reached before. The result is sigma = 0.567 +- 0.029(stat) +- 0.016(syst) nbarn. The data are compared with previous activation studies at high energy, and a recommended S(0) value for all 3He(alpha,gamma)7Be activation studies, including the present work, is given., Accepted for publication in PRC

Published
2007

22. Astrophysical S factor of the 3He(alpha,gamma)7Be reaction measured at low energy via detection of prompt and delayed gamma rays

Author

F. CONFORTOLA, D. BEMMERER, H. COSTANTINI, A. FORMICOLA, G.Y. GYÜRKY, P. BEZZON, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z.S. FÜLÖP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER, LOZZA, VALENTINA, F., Confortola, D., Bemmerer, H., Costantini, A., Formicola, Gyürky, G. Y., P., Bezzon, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Fülöp, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, Lozza, Valentina, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, and H. P., Trautvetter

Published
2007

23. 3He(α,γ)7Be cross section at low energies

Author

G. GYURKY, F. CONFORTOLA, H. COSTANTINI, A. FORMICOLA, D. BEMMERER, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z. FULOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, V. LOZZA, M. MARTA, R. MENEGAZZO, P. PRATI, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER, IMBRIANI, GIANLUCA, ROCA, VINCENZO, G., Gyurky, F., Confortola, H., Costantini, A., Formicola, D., Bemmerer, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Z., Fulop, G., Gervino, A., Guglielmetti, C., Gustavino, Imbriani, Gianluca, M., Junker, M., Laubenstein, A., Lemut, B., Limata, V., Lozza, M., Marta, R., Menegazzo, P., Prati, Roca, Vincenzo, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, and H. P., Trautvetter

Abstract

The flux of Be-7 and B-8 neutrinos from the Sun and the production of Li-7 via primordial nucleosynthesis depend on the rate of the He-3(alpha,gamma)Be-7 reaction. In an extension of a previous study showing cross section data at 127-167 keV center-of-mass energy, the present work reports on a measurement of the He-3(alpha,gamma)Be-7 cross section at 106 keV performed at Italy's Gran Sasso underground laboratory by the activation method. This energy is closer to the solar Gamow energy than ever reached before. The result is sigma=0.567 +/- 0.029(stat)+/- 0.016(syst) nb. The data are compared with previous activation studies at high energy, and a recommended S(0) value for all He-3(alpha,gamma)Be-7 activation studies, including the present work, is given.

Published
2007

24. Astrophysical S factor of the He3(α,γ)Be7 reaction measured at low energy via detection of prompt and delayed γ rays

Author

F. Confortola, D. Bemmerer, H. Costantini, A. Formicola, G.y. Gyürky, P. Bezzon, R. Bonetti, C. Broggini, P. Corvisiero, Z. Elekes, Z.s. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, M. Junker, M. Laubenstein, A. Lemut, B. Limata, V. Lozza, M. Marta, R. Menegazzo, P. Prati, C. Rolfs, C. Alvarez, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, H. Trautvetter, IMBRIANI, GIANLUCA, ROCA, VINCENZO, F., Confortola, D., Bemmerer, H., Costantini, A., Formicola, Gyürky, G. y., P., Bezzon, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Fülöp, Z. s., G., Gervino, A., Guglielmetti, C., Gustavino, Imbriani, Gianluca, M., Junker, M., Laubenstein, A., Lemut, B., Limata, V., Lozza, M., Marta, R., Menegazzo, P., Prati, Roca, Vincenzo, C., Rolf, C., Alvarez, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, and H., Trautvetter

Subjects
solar neutrino, Experimental nuclear physic, nuclear astrophysic
Abstract

Solar neutrino fluxes depend both on astrophysical and on nuclear physics inputs, namely on the cross sections of the reactions responsible for neutrino production inside the Solar core. While the flux of solar 8B neutrinos has been recently measured at Superkamiokande with a 3.5% uncertainty and a precise measurement of 7Be neutrino flux is foreseen in the next future, the predicted fluxes are still affected by larger errors. The largest nuclear physics uncertainty to determine the fluxes of 8B and 7Be neutrinos comes from the 3He(alpha,gamma )7Be reaction. The uncertainty on its S-factor is due to an average discrepancy in results obtained using two different experimental approaches: the detection of the delayed γ rays from 7Be decay and the measurement of the prompt-gamma emission. Here we report on a new high precision experiment performed with both techniques at the same time. Thanks to the low background conditions of the Gran Sasso LUNA accelerator facility, the cross section has been measured at Ec.m. = 170, 106, and 93 keV, the latter being the lowest interaction energy ever reached. The S-factors from the two methods do not show any discrepancy within the experimental errors. An extrapolated S(0) = 0.560 +/- 0.017 keVbarn is obtained. Moreover, branching ratios between the two prompt-gamma transitions have been measure with 5–8% accuracy.

Published
2007

25. Measurement of 25Mg(p; gamma)26Al resonance strengths via gamma spectrometry

Author

A. Formicola, BEST, ANDREAS, M. Junker, D. Bemmerer, R. Bonetti, C. Broggini, A. Caciolli, F. Confortola, P. Corvisiero, H. Costantini, Z. Elekes, Z. Fulop, G. Gervino, A. Guglielmetti, G. Gyürky, C. Gustavino, A. Lemut, M. Marta, C. Mazzocchi, R. Menegazzo, P. Prati, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, H. P. T.r.a.u.t.v.e.t.t.e.r. In: Journal of physics G. : nuclear, particle p.h.y.s.i.c.s. ISSN 0954 3.8.9.9. 3.5.:.1. p. 014013 0.1.4.0.1.3., IMBRIANI, GIANLUCA, LIMATA, BENEDICTA NORMANNA, ROCA, VINCENZO, A., Formicola, Best, Andrea, Imbriani, Gianluca, M., Junker, D., Bemmerer, R., Bonetti, C., Broggini, A., Caciolli, F., Confortola, P., Corvisiero, H., Costantini, Z., Eleke, Z., Fulop, G., Gervino, A., Guglielmetti, G., Gyürky, C., Gustavino, A., Lemut, Limata, BENEDICTA NORMANNA, M., Marta, C., Mazzocchi, R., Menegazzo, P., Prati, Roca, Vincenzo, C., Rolf, C., Rossi Alvarez, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, nuclear, H. P. T. r. a. u. t. v. e. t. t. e. r. In: Journal of physics G., and Particle, p. h. y. s. i. c. s. ISSN 0954 3. 8. 9. 9. 3. 5. :. 1. p. 014013 0. 1. 4. 0. 1. 3.

Subjects
Physics, Nuclear and High Energy Physics, COSMIC cancer database, Photon, Detector, Resonance, FOS: Physical sciences, Mass spectrometry, Galaxy, Nuclear physics, Underground laboratory, Mg abbundance, Nuclear Experiment (nucl-ex), Hpge detector, Nuclear Experiment, nuclear astrophysic
Abstract

The COMPTEL instrument performed the first mapping of the 1.809 MeV photons in the Galaxy, triggering considerable interest in determing the sources of interstellar 26Al. The predicted 26Al is too low compared to the observation, for a better understanding more accurate rates for the 25Mg(p; gamma)26Al reaction are required. The 25Mg(p;gamma)26Al reaction has been investigated at the resonances at Er= 745; 418; 374; 304 keV at Ruhr-Universitat-Bochum using a Tandem accelerator and a 4piNaI detector. In addition the resonance at Er = 189 keV has been measured deep underground laboratory at Laboratori Nazionali del Gran Sasso, exploiting the strong suppression of cosmic background. This low resonance has been studied with the 400 kV LUNA accelerator and a HPGe detector. The preliminary results of the resonance strengths will be reported., Comment: Accepted for publication in Journal of Physics G

Published
2007
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26. Activation Measurement of the 3He(alpha,gamma)7Be Cross Section at Low Energy

Author

D. BEMMERER, F. CONFORTOLA, H. COSTANTINI, A. FORMICOLA, G. GYURKY, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z. FULOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, V. LOZZA, M. MARTA, R. MENEGAZZO, P. . PRATI, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER, IMBRIANI, GIANLUCA, ROCA, VINCENZO, D., Bemmerer, F., Confortola, H., Costantini, A., Formicola, Gyürky, G. Y., R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Fülöp, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, Lozza, Valentina, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, H. P., Trautvetter, G., Gyurky, Z., Fulop, Imbriani, Gianluca, V., Lozza, Prati, P., and Roca, Vincenzo

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Astrophysics, Nuclear Experiment
Abstract

The nuclear physics input from the 3He(alpha,gamma)7Be cross section is a major uncertainty in the fluxes of 7Be and 8B neutrinos from the Sun predicted by solar models and in the 7Li abundance obtained in big-bang nucleosynthesis calculations. The present work reports on a new precision experiment using the activation technique at energies directly relevant to big-bang nucleosynthesis. Previously such low energies had been reached experimentally only by the prompt-gamma technique and with inferior precision. Using a windowless gas target, high beam intensity, and low background gamma-counting facilities, the 3He(alpha,gamma)7Be cross section has been determined at 127, 148, and 169 keV center-of-mass energy with a total uncertainty of 4%. The sources of systematic uncertainty are discussed in detail. The present data can be used in big-bang nucleosynthesis calculations and to constrain the extrapolation of the 3He(alpha,gamma)7Be astrophysical S factor to solar energies.

Published
2006

27. Low energy measurement of the 14N(p,γ)15O total cross section at the LUNA underground facility

Author

D. BEMMERER, F. CONFORTOLA, H. COSTANTINI, A. FORMICOLA, G. GYU, RKY, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z. FU, LOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, V. LOZZA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, D., Bemmerer, F., Confortola, H., Costantini, A., Formicola, G., Gyu, Rky, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Z., Fu, Lop, G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, V., Lozza, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2006

28. Recent results of the 14N(p,g)measurement at LUNA

Author

H. COSTANTINI, C. ANGULO, D. BEMMERER, R. BONETTI, C. BROGGINI, F. CONFORTOLA, P. CORVISIERO, J. CRUZ, A. FORMICOLA, Z. FÜLÖP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. GYÜRKY, G. IMBRIANI, A. P. JESUS, M. JUNKER, B. LIMATA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, M. ROMANO, C. ROSSI ALVAREZ, F. SCHÜMANN, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, H., Costantini, C., Angulo, D., Bemmerer, R., Bonetti, C., Broggini, F., Confortola, P., Corvisiero, J., Cruz, A., Formicola, Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, G., Imbriani, A. P., Jesu, M., Junker, B., Limata, R., Menegazzo, P., Prati, V., Roca, C., Rolf, M., Romano, C., ROSSI ALVAREZ, F., Schümann, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2005

29. The 14N(p,γ)15O measurement at low energy

Author

F. CONFORTOLA, D. BEMMERER, R. BONETTI, C. BROGGINI, P. CORVISIERO, H. COSTANTINI, J. CRUZ, A. FORMICOLA, Z. FU, LOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. GYU, RKY, G, IMBRIANI, A. P. JESUS, M. JUNKER, A. LEMUT, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, M. ROMANO, G. ROSSI ALVAREZ, F. SCHU, MANN, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, S. ZAVATARELLI, TERRASI, Filippo, F., Confortola, D., Bemmerer, R., Bonetti, C., Broggini, P., Corvisiero, H., Costantini, J., Cruz, A., Formicola, Z., Fu, Lop, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyu, Rky, G, Imbriani, A. P., Jesu, M., Junker, A., Lemut, R., Menegazzo, P., Prati, V., Roca, C., Rolf, M., Romano, G., ROSSI ALVAREZ, F., Schu, Mann, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, H. P., Trautvetter, and S., Zavatarelli

Published
2004

31. First measurement of the d(p,γ)3He cross section down to the solar Gamow peak

Author

C. CASELLA, H. COSTANTINI, A. LEMUT, B. LIMATA, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, J. CRUZ, A. DONOFRIO, A. FORMICOLA, Z. FLP, G. GERVINO, L. GIALANELLA, A. GUGLIELMETTI, C. GUSTAVINO, G. GYURKY, IMBRIANI, GIANLUCA, A. P. JESUS, M. JUNKER, A. ORDINE, J. V. PINTO, P. PRATI, J. P. RIBEIRO, ROCA, VINCENZO, D. ROGALLA, C. ROLFS, C. R. ALVAREZ, F. SCHMANN, E. SOMORJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER AND S. ZAVATARELLI, ROMANO, MARIO, C., Casella, H., Costantini, A., Lemut, B., Limata, R., Bonetti, C., Broggini, L., Campajola, P., Corvisiero, J., Cruz, A., Donofrio, A., Formicola, Z., Flp, G., Gervino, L., Gialanella, A., Guglielmetti, C., Gustavino, G., Gyurky, Imbriani, Gianluca, A. P., Jesu, M., Junker, A., Ordine, J. V., Pinto, P., Prati, J. P., Ribeiro, Roca, Vincenzo, D., Rogalla, C., Rolf, M., Romano, C. R., Alvarez, F., Schmann, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, H. P. TRAUTVETTER AND S., Zavatarelli, and Romano, Mario

Published
2002

32. Absolute cross section of 7Be(p,gamma)8B. Nucl. Phys. A 696 (2001) 219S

Author

F. STRIEDER, L. GIALANELLA, G. GYRKY, F. SCHMANN, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, H. COSTANTINI, A. DONOFRIO, A. FORMICOLA, Z. FLP, G. GERVINO, U. GREIFE, A. GUGLIELMETTI, C. GUSTAVINO, IMBRIANI, GIANLUCA, M. JUNKER, P. G. P. MORONI, A. ORDINE, P. PRATI, ROCA, VINCENZO, D. ROGALLA, C. ROLFS, E. SOMORJAI, O. STRANIERO, F. TERRASI, H. P. TRAUTVETTER AND S. Z.A.V.A.T.A.R.E.L.L.I., ROMANO, MARIO, F., Strieder, L., Gialanella, G., Gyrky, F., Schmann, R., Bonetti, C., Broggini, L., Campajola, P., Corvisiero, H., Costantini, A., Donofrio, A., Formicola, Z., Flp, G., Gervino, U., Greife, A., Guglielmetti, C., Gustavino, Imbriani, Gianluca, M., Junker, P. G. P., Moroni, A., Ordine, P., Prati, Roca, Vincenzo, D., Rogalla, C., Rolf, Romano, Mario, E., Somorjai, O., Straniero, F., Terrasi, and H. P. TRAUTVETTER AND S. Z. A. V. A. T. A. R. E. L. L., I.

Published
2001

34. Absolute cross section of 7Be(p,γ)8B, Nucl Phys.A

Author

F. STRIEDER, L. GIALANELLA, G. GYURKY, F. SCHUMAN, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, H. COSTANTINI, A. DONOFRIO, A. FORMICOLA, Z. FULOP, G. GERVINO, C. ROLFS, M. ROMANO, E. SOMORJAI, O. STRANIERO, F. TERRASI, H. P. TRAUTVETTER, S. ZAVATARELLI, ROCA, VINCENZO, F., Strieder, L., Gialanella, G., Gyurky, F., Schuman, R., Bonetti, C., Broggini, L., Campajola, P., Corvisiero, H., Costantini, A., Donofrio, A., Formicola, Z., Fulop, G., Gervino, C., Rolf, Roca, Vincenzo, M., Romano, E., Somorjai, O., Straniero, F., Terrasi, H. P., Trautvetter, and S., Zavatarelli

Published
2001

35. Electron screening effect in the reactions 3He(d,p)4He and d(3He,p)4He, Nucl. Phys. A690(2001)790

Author

M. ALIOTTA, F. RAIOLA, G. GYURKY, A. FORMICOLA, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, H. COSTANTINI, A. D'ONOFRIO, Z. FULOP, G. GERVINO, L. GIALANELLA, A. GUGLIELMETTI, C. GUSTAVINO, IMBRIANI, GIANLUCA, M. JUNKER, R. W. KAVANAGH, P. G. MORONI, A. ORDINE, P. PRATI, D. ROGALLA, C. ROLFS, M. ROMANO, F. SCHUMANN, E. SOMORIJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER AND S. ZAVATARELLI, ROCA, VINCENZO, M., Aliotta, F., Raiola, G., Gyurky, A., Formicola, R., Bonetti, C., Broggini, L., Campajola, P., Corvisiero, H., Costantini, A., D'Onofrio, Z., Fulop, G., Gervino, L., Gialanella, A., Guglielmetti, C., Gustavino, Imbriani, Gianluca, M., Junker, R. W., Kavanagh, P. G., Moroni, A., Ordine, P., Prati, Roca, Vincenzo, D., Rogalla, C., Rolf, M., Romano, F., Schumann, E., Somorijai, O., Straniero, F., Strieder, F., Terrasi, and H. P. TRAUTVETTER AND S., Zavatarelli

Published
2001

36. Stopping power of low-energy deuterons in 3He gas

Author

F. RAIOLA, G. GYURKY, M. ALIOTTA, A. FORMICOLA, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, H. COSTANTINI, A. D'ONOFRIO, Z. FULOP, G. GERVINO, L. GIALANELLA, A. GUGLIELMETTI, C. GUSTAVINO, IMBRIANI, GIANLUCA, M. JUNKER, R. W. KAVANAGH, P. G. MORONI, A. ORDINE, P. PRATI, ROCA, VINCENZO, D. ROGALLA, C. ROLFS, F. SCHUMANN, E. SOMORIJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER AND S. Z.A.V.A.T.A.R.E.L.L.I., ROMANO, MARIO, F., Raiola, G., Gyurky, M., Aliotta, A., Formicola, R., Bonetti, C., Broggini, L., Campajola, P., Corvisiero, H., Costantini, A., D'Onofrio, Z., Fulop, G., Gervino, L., Gialanella, A., Guglielmetti, C., Gustavino, Imbriani, Gianluca, M., Junker, R. W., Kavanagh, P. G., Moroni, A., Ordine, P., Prati, Roca, Vincenzo, D., Rogalla, C., Rolf, Romano, Mario, F., Schumann, E., Somorijai, O., Straniero, F., Strieder, F., Terrasi, and H. P. TRAUTVETTER AND S. Z. A. V. A. T. A. R. E. L. L., I.

Published
2001

37. CNO hydrogen burning studied deep underground

Author

D. Bemmerer, F. Confortola, A. Lemut, R. Bonetti, C. Broggini, P. Corvisiero, H. Costantini, J. Cruz, A. Formicola, Zs. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, G. Imbriani, A. P. Jesus, M. Junker, B. Limata, R. Menegazzo, P. Prati, V. Roca, D. Rogalla, C. Rolfs, M. Romano, C. Rossi Alvarez, F. Schümann, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, and H. P. Trautvetter

Published
2010
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38. Towards a high-precision measurement of the 3He(α, γ)7Be cross section at LUNA

Author

H. Costantini, D. Bemmerer, P. Bezzon, R. Bonetti, C. Broggini, M. L. Casanova, F. Confortola, P. Corvisiero, J. Cruz, Z. Elekes, A. Formicola, Zs. Fülop, G. Gervino, C. Gustavino, A. Guglielmetti, Gy. Gyürky, G. Imbriani, A. P. Jesus, M. Junker, A. Lemut, M. Marta, R. Menegazzo, P. Prati, E. Roc, C. Rolfs, M. Romano, C. Rossi Alvarez, F. Schümann, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, and H. P. Trautvetter

Published
2010
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39. White dwarfs of very low mass with C/O core

Author

P. G. Prada Moroni, O. Straniero, Giuliana Giobbi, Amedeo Tornambe, Gabriella Raimondo, Marco Limongi, L. A. Antonelli, Nicola Menci, and Enzo Brocato

Subjects
Red shift, Physics, Core (optical fiber), Star formation, Astronomy, White dwarf, Astrophysics, Massive compact halo object, Low Mass, Black dwarf
Abstract

It is commonly believed that white dwarfs (WDs) with a carbon‐oxygen core must have mass larger than about 0.5M⊙. We will discuss a possible scenario for the formation of C/O WDs with mass as low as 0.33M⊙. A description of both the pre‐WD and the cooling evolution of such models of very low mass will be presented.

Published
2009

40. The Progenitors of Thermonuclear Supernovae

Author

L. Piersanti, A. Tornambé, O. Straniero, I. Domìnguez, Giuliana Giobbi, Amedeo Tornambe, Gabriella Raimondo, Marco Limongi, L. A. Antonelli, Nicola Menci, and Enzo Brocato

Subjects
Physics, Thermonuclear fusion, Star formation, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Light curve, Universe, Galaxy, Luminosity, Supernova, Astrophysics::Solar and Stellar Astrophysics, Low Mass, Astrophysics::Galaxy Astrophysics, media_common
Abstract

In the framework of the rotating Double Degenerate Scenario for type Ia Supernovae progenitors, we show that the dichotomy between explosive events in early and late type galaxies can be easily explained. Assuming that more massive progenitors produce slow‐decline (high‐luminosity) light curve, it comes out that, at the current age of the Universe, in late type galaxies the continuous star formation provides very massive exploding objects (prompt component) corresponding to slow‐decline (bright) SNe; on the other hand, in early type galaxies, where star formation ended many billions years ago, only low mass “normal luminosity” objects (delayed component) are present.

Published
2009
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41. Abundances of Heavy Elements in PNe and AGB Model Predictions

Author

M. Pignatari, R. Gallino, S. Cristallo, O. Straniero, Roald Guandalini, Sara Palmerini, and Maurizio Busso

Subjects
Physics, Nebula, Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Giant star, Planetary nebula, Protoplanetary nebula, Stars, Emission nebula, Nucleosynthesis, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Stellar evolution, Astrophysics::Galaxy Astrophysics
Abstract

During the AGB phase of low and intermediate mass stars heavy s–process elements are produced and dredged–up in the envelope. In the following Planetary Nebula phase part of the AGB envelope will form the nebula around the hot central star, carrying the s–process signature unchanged. Recently, heavy elements have been observed is many Planetary Nebulae, providing a new tool to analyze the s–process nucleosynthesis working in the AGB stars. In this paper we present s–process predictions for a large spread of stellar masses, metallicities and 13C–pocket efficiencies. Theoretical results are compared with the most recent observations in PNe, finding a general good agreement.

Published
2008
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42. Progresses in AGB Modelling

Author

S. Cristallo, O. Straniero, R. Gallino, M. T. Lederer, L. Piersanti, I. Domínguez, Roald Guandalini, Sara Palmerini, and Maurizio Busso

Subjects
Physics, Convection, Stars, Nucleosynthesis, Milky Way, Astrophysics::Solar and Stellar Astrophysics, Astronomy, Astrophysics, Dredge-up, Low Mass, Giant star, Stellar evolution, Astrophysics::Galaxy Astrophysics
Abstract

The full understanding of final stellar evolution phases is a fundamental request to properly investigate the Universe at any temporal and spatial scale. While the theoretical scenarios of H‐ and He‐burning have been deeply investigated in the last 30 years, the modelling of stellar evolution beyond the core‐helium burning phase and the related nucleosynthesis still present problems related to the physics and to the numerical methods. Low mass AGB Stars (1

Published
2008
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43. Analysis of Two Carbon Stars in the Carina Dwarf Spheroidal Galaxy

Author

C. Abia, P. de Laverny, R. Wahlin, I. Domínguez, S. Cristallo, O. Straniero, Roald Guandalini, Sara Palmerini, and Maurizio Busso

Subjects
Physics, Spiral galaxy, K-type main-sequence star, Stellar collision, Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Carbon star, Dwarf spheroidal galaxy, T Tauri star, Stellar mass loss, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Dwarf galaxy
Abstract

We present a chemical analysis of two metal‐poor carbon stars belonging to the Carina Dwarf Spheroidal galaxy using high resolution optical spectra obtained with the VLT/UVES instrument. Their derived properties and chemical composition are compatible with these stars being in the TP‐AGB phase undergoing third dredge‐up episodes, although their extrinsic nature cannot be definitively discarded. The analysis indicates that these stars have large s‐element enhancements, which are compatible with theoretical s‐process nucleosynthesis predictions in low‐mass AGB stars (∼1.5M⊙), and also large carbon enhancements (C/O⩾5), much larger than the values typically found in galactic AGB carbon stars (C/O∼1–2). This is also in agreement with the theoretical prediction that carbon stars are formed more easily through third dredge‐up episodes as the initial stellar metallicity drops. We speculate on the possibility that the abundance pattern found in the low‐mass s‐elements (Y, Zr) may be revealing the existence of som...

Published
2008
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44. Observing Third Dredge Up in NGC 1846

Author

T. Lebzelter, K. H. Hinkle, M. T. Lederer, S. Cristallo, O. Straniero, W. Nowotny, P. Wood, Roald Guandalini, Sara Palmerini, and Maurizio Busso

Subjects
Physics, Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Horizontal branch, Dredge-up, Giant star, Blue straggler, Luminosity, Stars, Globular cluster, Astrophysics::Solar and Stellar Astrophysics, Stellar evolution, Astrophysics::Galaxy Astrophysics
Abstract

In this contribution we present the first measurements of the C/O ratio for a sample of AGB stars in the LMC globular cluster NGC 1846. From a variability study we set strong constraints on the mass of the cluster stars, which is an important quantity for comparison with evolutionary models. Variations of the surface abundance both with luminosity and pulsation properties were found and the various relevant factors are discussed. We find a good agreement with our synthetic models if we assume [O/Fe] = ±0.2 dex. The F abundance seems to increase with the C/O ratio. As variability plays a key role on the AGB we give some preliminary results from our study of abundance determination in the dynamical case at the end of this paper.

Published
2008
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45. Neutron capture on (180)Ta(m): clue for an s-process origin of nature's rarest isotope

Author

K, Wisshak, F, Voss, C, Arlandini, F, Becvár, O, Straniero, R, Gallino, M, Heil, F, Käppeler, M, Krticka, S, Masera, R, Reifarth, and C, Travaglio

Abstract

The neutron capture cross section of (180)Ta(m) has been measured in the keV range, yielding a stellar average of 1465+/-100 mb at kT = 30 keV. Though the sample contained only 6.7 mg (180)Ta(m) (at an enrichment of 5.5%), the few capture events could be separated from much larger backgrounds by a unique combination of high efficiency, good energy resolution, and high granularity of the Karlsruhe 4 pi BaF(2) detector. A detailed s-process analysis based on this first experimental value indicates that (180)Ta(m) is predominantly of s-process origin.

Published
2001

47. Electron screening effect in the reactions 3He(d,p)4He and d(3He,p)4He

Author

M. ALIOTTA, F. RAIOLA, G. GYURKY, A. FORMICOLA, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, H. COSTANTINI, Z. FULOP, G. GERVINO, L. GIALANELLA, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, R. W. KAVANAGH, P. G. MORONI, A. ORDINE, P. PRATI, V. ROCA, D. ROGALLA, C. ROLFS, M. ROMANO, F. SCHUMANN, E. SOMORIJAI, O. STRANIERO, F. STRIEDER, TERRASI, Filippo, H. P. TRAUTVETTER, S. ZAVATARELLI, D'ONOFRIO, Antonio, Aliotta, M., Raiola, F., Gyurky, G., Formicola, A., Bonetti, R., Broggini, C., Campajola, L., Corvisiero, P., Costantini, H., D'Onofrio, Antonio, Fulop, Z., Gervino, G., Gialanella, L., Guglielmetti, A., Gustavino, C., Imbriani, G., Junker, M., Kavanagh, R. W., Moroni, P. G., Ordine, A., Prati, P., Roca, V., Rogalla, D., Rolfs, C., Romano, M., Schumann, F., Somorijai, E., Straniero, O., Strieder, F., Terrasi, Filippo, Trautvetter, H. P., and Zavatarelli, S.

Published
2001

48. Stopping power of low-energy deuterons in 3He gas: a threshold effect

Author

F. RAIOLA, G. GYURKY, M. ALIOTTA, A. FORMICOLA, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, H. COSTANTINI, Z. FULOP, G. GERVINO, L. GIALANELLA, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, R. W. KAVANAGH, P. G. MORONI, A. ORDINE, P. PRATI, V. ROCA, D. ROGALLA, C. ROLFS, M. ROMANO, F. SCHUMANN, E. SOMORIJAI, O. STRANIERO, F. STRIEDER, TERRASI, Filippo, H. P. TRAUTVETTER, S. ZAVATARELLI, D'ONOFRIO, Antonio, Raiola, F., Gyurky, G., Aliotta, M., Formicola, A., Bonetti, R., Broggini, C., Campajola, L., Corvisiero, P., Costantini, H., D'Onofrio, Antonio, Fulop, Z., Gervino, G., Gialanella, L., Guglielmetti, A., Gustavino, C., Imbriani, G., Junker, M., Kavanagh, R. W., Moroni, P. G., Ordine, A., Prati, P., Roca, V., Rogalla, D., Rolfs, C., Romano, M., Schumann, F., Somorijai, E., Straniero, O., Strieder, F., Terrasi, Filippo, Trautvetter, H. P., and Zavatarelli, S.

Published
2001

49. Electron screening and ion stopping power at low energy

Author

H. COSTANTINI, A. FORMICOLA, M. JUNKER, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, A. FUBINI, G. GERVINO, L. GIALANELLA, U. GREIFE, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, P. G. P. MORONI, A. ORDINE, P. PRATI, V. ROCA, C. ROLFS, M. ROMANO, F. SCHÜMANN, O. STRANIERO, F. STRIEDER, TERRASI, Filippo, H. P. TRAUTVETTER, S. ZAVATARELLI, D'ONOFRIO, Antonio, Costantini, H., Formicola, A., Junker, M., Bonetti, R., Broggini, C., Campajola, L., Corvisiero, P., D'Onofrio, Antonio, Fubini, A., Gervino, G., Gialanella, L., Greife, U., Guglielmetti, A., Gustavino, C., Imbriani, G., Moroni, P. G. P., Ordine, A., Prati, P., Roca, V., Rolfs, C., Romano, M., Schümann, F., Straniero, O., Strieder, F., Terrasi, Filippo, Trautvetter, H. P., and Zavatarelli, S.

Published
2000

50. Energy loss of deuterons in 3He gas: a threshold effect

Author

A. FORMICOLA, M. ALIOTTA, G. GYURKY, F. RAIOLA, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, H. COSTANTINI, Z. FULOP, G. GERVINO, L. GIALANELLA, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, A. ORDINE, P. PRATI, V. ROCA, D. ROGALLA, C. ROLFS, M. ROMANO, F. SCHUMANN, E. SOMORJAI, O. STRANIERO, F. STRIEDER, TERRASI, Filippo, H. P. TRAUTVETTER AND S. ZAVATARELLI, D'ONOFRIO, Antonio, Formicola, A., Aliotta, M., Gyurky, G., Raiola, F., Bonetti, R., Broggini, C., Campajola, L., Corvisiero, P., Costantini, H., D'Onofrio, Antonio, Fulop, Z., Gervino, G., Gialanella, L., Guglielmetti, A., Gustavino, C., Imbriani, G., Junker, M., Ordine, A., Prati, P., Roca, V., Rogalla, D., Rolfs, C., Romano, M., Schumann, F., Somorjai, E., Straniero, O., Strieder, F., Terrasi, Filippo, and Zavatarelli, H. P. TRAUTVETTER AND S.

Published
2000

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