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Title: Experimental determination of the {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates

Abstract

The {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reactions are of major importance to hydrogen-burning nucleosynthesis in a number of different stellar sites. In particular, {sup 17}O and {sup 18}F nucleosynthesis in classical novae is strongly dependent on the thermonuclear rates of these two reactions. The previously estimated rate for {sup 17}O(p,{alpha}){sup 14}N carries very large uncertainties in the temperature range of classical novae (T=0.01-0.4 GK), whereas a recent measurement has reduced the uncertainty of the {sup 17}O(p,{gamma}){sup 18}F rate. We report on the observation of a previously undiscovered resonance at E{sub c.m.}=183.3 keV in the {sup 17}O(p,{alpha}){sup 14}N reaction, with a measured resonance strength {omega}{gamma}{sub p{alpha}}=(1.6{+-}0.2)x10{sup -3} eV. We studied in the same experiment the {sup 17}O(p,{gamma}){sup 18}F reaction by an activation method, and the resonance strength was found to amount to {omega}{gamma}{sub p{gamma}}=(2.2{+-}0.4)x10{sup -6} eV. The excitation energy of the corresponding level in {sup 18}F was determined to be 5789.8{+-}0.3 keV in a Doppler shift attenuation method measurement, which yielded a value of {tau}<2.6 fs for the level lifetime. The {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates were calculated using the measured resonance properties and reconsidering some previous analyses of the contributions of other levels ormore » processes. The {sup 17}O(p,{alpha}){sup 14}N rate is now well established below T=1.5 GK, with uncertainties reduced by orders of magnitude in the temperature range T=0.1-0.4 GK. The uncertainty in the {sup 17}O(p,{gamma}){sup 18}F rate is somewhat larger because of remaining obscurities in the knowledge of the direct capture process. These new resonance properties have important consequences for {sup 17}O nucleosynthesis and {gamma}-ray emission of classical novae.« less

Authors:
;  [1]; ; ; ; ; ;  [2];  [3];  [4];  [5];  [6];  [2];  [7]
  1. USTHB-Faculte de Physique, BP 32, El-Alia, 16111 Bab Ezzouar, Algiers (Algeria)
  2. CSNSM, IN2P3-CNRS and Universite Paris-Sud, F-91405 Orsay Cedex (France)
  3. CENBG, IN2P3-CNRS and Universite Bordeaux I, F-33175 Gradignan (France)
  4. UMBM, B.P. 166, Route ICHBILLIA, 28000 M'sila (Algeria)
  5. Institut de Ciencies de l'Espai (CSIC) and Institut d'Estudis Espacials de Catalunya, E-08034 Barcelona (Spain)
  6. Departament de Fisica i Enginyeria Nuclear (UPC) and Institut d'Estudis Espacials de Catalunya, E-08034 Barcelona (Spain)
  7. (Belgium)
Publication Date:
OSTI Identifier:
20995177
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevC.75.035810; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; DSA METHOD; EV RANGE; EXCITATION; FLUORINE 18; GAMMA RADIATION; HYDROGEN BURNING; KEV RANGE; NITROGEN 14; NOVAE; NUCLEOSYNTHESIS; OXYGEN 17 TARGET; PROTONS; REACTION KINETICS; RESONANCE; TEMPERATURE RANGE

Citation Formats

Chafa, A., Ouichaoui, S., Tatischeff, V., Coc, A., Garrido, F., Kiener, J., Lefebvre-Schuhl, A., Thibaud, J.-P., Aguer, P., Barhoumi, S., Hernanz, M., Jose, J., Sereville, N. de, and Universite Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve. Experimental determination of the {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.035810.
Chafa, A., Ouichaoui, S., Tatischeff, V., Coc, A., Garrido, F., Kiener, J., Lefebvre-Schuhl, A., Thibaud, J.-P., Aguer, P., Barhoumi, S., Hernanz, M., Jose, J., Sereville, N. de, & Universite Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve. Experimental determination of the {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates. United States. doi:10.1103/PHYSREVC.75.035810.
Chafa, A., Ouichaoui, S., Tatischeff, V., Coc, A., Garrido, F., Kiener, J., Lefebvre-Schuhl, A., Thibaud, J.-P., Aguer, P., Barhoumi, S., Hernanz, M., Jose, J., Sereville, N. de, and Universite Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve. Thu . "Experimental determination of the {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates". United States. doi:10.1103/PHYSREVC.75.035810.
@article{osti_20995177,
title = {Experimental determination of the {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates},
author = {Chafa, A. and Ouichaoui, S. and Tatischeff, V. and Coc, A. and Garrido, F. and Kiener, J. and Lefebvre-Schuhl, A. and Thibaud, J.-P. and Aguer, P. and Barhoumi, S. and Hernanz, M. and Jose, J. and Sereville, N. de and Universite Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve},
abstractNote = {The {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reactions are of major importance to hydrogen-burning nucleosynthesis in a number of different stellar sites. In particular, {sup 17}O and {sup 18}F nucleosynthesis in classical novae is strongly dependent on the thermonuclear rates of these two reactions. The previously estimated rate for {sup 17}O(p,{alpha}){sup 14}N carries very large uncertainties in the temperature range of classical novae (T=0.01-0.4 GK), whereas a recent measurement has reduced the uncertainty of the {sup 17}O(p,{gamma}){sup 18}F rate. We report on the observation of a previously undiscovered resonance at E{sub c.m.}=183.3 keV in the {sup 17}O(p,{alpha}){sup 14}N reaction, with a measured resonance strength {omega}{gamma}{sub p{alpha}}=(1.6{+-}0.2)x10{sup -3} eV. We studied in the same experiment the {sup 17}O(p,{gamma}){sup 18}F reaction by an activation method, and the resonance strength was found to amount to {omega}{gamma}{sub p{gamma}}=(2.2{+-}0.4)x10{sup -6} eV. The excitation energy of the corresponding level in {sup 18}F was determined to be 5789.8{+-}0.3 keV in a Doppler shift attenuation method measurement, which yielded a value of {tau}<2.6 fs for the level lifetime. The {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates were calculated using the measured resonance properties and reconsidering some previous analyses of the contributions of other levels or processes. The {sup 17}O(p,{alpha}){sup 14}N rate is now well established below T=1.5 GK, with uncertainties reduced by orders of magnitude in the temperature range T=0.1-0.4 GK. The uncertainty in the {sup 17}O(p,{gamma}){sup 18}F rate is somewhat larger because of remaining obscurities in the knowledge of the direct capture process. These new resonance properties have important consequences for {sup 17}O nucleosynthesis and {gamma}-ray emission of classical novae.},
doi = {10.1103/PHYSREVC.75.035810},
journal = {Physical Review. C, Nuclear Physics},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}