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Title: New Improved Indirect Measurement of the {sup 19}F( p , α ){sup 16}O Reaction at Energies of Astrophysical Relevance

Abstract

Fluorine abundance determination is of great importance in stellar physics to understand s-elements production and mixing processes in asymptotic giant branch (AGB) stars. Up to now, theoretical models overproduce F abundances in AGB stars with respect to the observed values, thus calling for further investigation of the reactions involving fluorine. In particular, the {sup 19}F( p , α ){sup 16}O reaction is the main destruction channel of fluorine at the bottom of the convective envelope in AGB stars, an H-rich environment where it can experience temperatures high enough to determine its destruction, owing to additional mixing processes. In this paper the Trojan horse method (THM) was used to extract the {sup 19}F( p , α {sub 0}){sup 16}O S-factor in the energy range of astrophysical interest ( E {sub cm} ≈ 0–1 MeV). This is the most relevant channel at the low temperatures (few 10{sup 7} K) characterizing the bottom of the convective envelope, according to current knowledge. A previous indirect experiment using the THM has observed three resonances in the energy regions below E {sub cm} ≈ 450 keV. These energies correspond to typical AGB temperatures, thus implying a significant increase in the reaction rate. Statistics are scarce formore » performing an accurate separation between resonances, preventing one from drawing a quantitative conclusion about their total widths and spin parities. Before THM measurement, only extrapolations were available below about 500 keV, showing a non-resonant behavior that sharply contradicts the trend of the astrophysical factor at higher energies. A new experiment has been performed to verify the measured TH astrophysical factor and to perform more accurate spectroscopy of the involved resonances.« less

Authors:
; ; ; ; ; ; ; ;  [1]; ; ; ;  [2];  [3]; ; ;  [4]
  1. INFN, Laboratori Nazionali del Sud, Catania (Italy)
  2. Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic)
  3. RIKEN, CNS, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
  4. INFN, Sezione di Padova, Padova (Italy)
Publication Date:
OSTI Identifier:
22663287
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 845; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ALPHA DECAY; ASTROPHYSICS; ASYMPTOTIC SOLUTIONS; EXTRAPOLATION; FLUORINE 19 TARGET; GIANT STARS; MEV RANGE; NUCLEAR REACTIONS; NUCLEOSYNTHESIS; OXYGEN 16; PROTON REACTIONS; RESONANCE; SPECTROSCOPY; SPIN; STARS; STATISTICS

Citation Formats

Indelicato, I., La Cognata, M., Spitaleri, C., Cherubini, S., Gulino, M., Lamia, L., Pizzone, R. G., Romano, S., Tumino, A., Burjan, V., Hons, Z., Kroha, V., Mrazek, J., Hayakawa, S., Mazzocco, M., Strano, E., and Torresi, D., E-mail: indelicato@lns.infn.it. New Improved Indirect Measurement of the {sup 19}F( p , α ){sup 16}O Reaction at Energies of Astrophysical Relevance. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA7DE7.
Indelicato, I., La Cognata, M., Spitaleri, C., Cherubini, S., Gulino, M., Lamia, L., Pizzone, R. G., Romano, S., Tumino, A., Burjan, V., Hons, Z., Kroha, V., Mrazek, J., Hayakawa, S., Mazzocco, M., Strano, E., & Torresi, D., E-mail: indelicato@lns.infn.it. New Improved Indirect Measurement of the {sup 19}F( p , α ){sup 16}O Reaction at Energies of Astrophysical Relevance. United States. doi:10.3847/1538-4357/AA7DE7.
Indelicato, I., La Cognata, M., Spitaleri, C., Cherubini, S., Gulino, M., Lamia, L., Pizzone, R. G., Romano, S., Tumino, A., Burjan, V., Hons, Z., Kroha, V., Mrazek, J., Hayakawa, S., Mazzocco, M., Strano, E., and Torresi, D., E-mail: indelicato@lns.infn.it. Thu . "New Improved Indirect Measurement of the {sup 19}F( p , α ){sup 16}O Reaction at Energies of Astrophysical Relevance". United States. doi:10.3847/1538-4357/AA7DE7.
@article{osti_22663287,
title = {New Improved Indirect Measurement of the {sup 19}F( p , α ){sup 16}O Reaction at Energies of Astrophysical Relevance},
author = {Indelicato, I. and La Cognata, M. and Spitaleri, C. and Cherubini, S. and Gulino, M. and Lamia, L. and Pizzone, R. G. and Romano, S. and Tumino, A. and Burjan, V. and Hons, Z. and Kroha, V. and Mrazek, J. and Hayakawa, S. and Mazzocco, M. and Strano, E. and Torresi, D., E-mail: indelicato@lns.infn.it},
abstractNote = {Fluorine abundance determination is of great importance in stellar physics to understand s-elements production and mixing processes in asymptotic giant branch (AGB) stars. Up to now, theoretical models overproduce F abundances in AGB stars with respect to the observed values, thus calling for further investigation of the reactions involving fluorine. In particular, the {sup 19}F( p , α ){sup 16}O reaction is the main destruction channel of fluorine at the bottom of the convective envelope in AGB stars, an H-rich environment where it can experience temperatures high enough to determine its destruction, owing to additional mixing processes. In this paper the Trojan horse method (THM) was used to extract the {sup 19}F( p , α {sub 0}){sup 16}O S-factor in the energy range of astrophysical interest ( E {sub cm} ≈ 0–1 MeV). This is the most relevant channel at the low temperatures (few 10{sup 7} K) characterizing the bottom of the convective envelope, according to current knowledge. A previous indirect experiment using the THM has observed three resonances in the energy regions below E {sub cm} ≈ 450 keV. These energies correspond to typical AGB temperatures, thus implying a significant increase in the reaction rate. Statistics are scarce for performing an accurate separation between resonances, preventing one from drawing a quantitative conclusion about their total widths and spin parities. Before THM measurement, only extrapolations were available below about 500 keV, showing a non-resonant behavior that sharply contradicts the trend of the astrophysical factor at higher energies. A new experiment has been performed to verify the measured TH astrophysical factor and to perform more accurate spectroscopy of the involved resonances.},
doi = {10.3847/1538-4357/AA7DE7},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 845,
place = {United States},
year = {2017},
month = {8}
}