Experimental study of the 30Si(p,γ)31P reaction for understanding elemental anomalies in globular clusters
Creators
- Harrouz, Djamila Sarah
- Universite Paris-Saclay, Ecole doctorale no. 576, Particules, hadrons, energie et noyau, instrumentation, imagerie, cosmos et simulation - Pheniics (France)
- Faculte des sciences d'Orsay, Laboratoire de Physique des 2 Infinis Irene Joliot-Curie - IJCLab, Bat. 100 et 200, 15 rue Georges Clemenceau, 91405 Orsay (France)
Description
Globular clusters are essential objects for studying stellar evolutionary patterns and the early phases of galaxy formation. The abundance anomalies observed in the globular cluster NGC 2419, such as potassium overabundance and magnesium depletion, can be explained if an earlier generation of stars contaminates the currently observed stars. However, the nature and properties of this first generation of stars are not clearly identified. The temperature and density range of this one depends on a number of reaction rates. The 30Si(p,γ)31P reaction is one of the few reactions identified as having sufficient influence to constrain the nature of the stellar site(s) that contaminated NGC 2419. The objective of this thesis is to reduce the nuclear uncertainties associated with the 30Si(p,γ)31P reaction by determining the resonance strengths in the energy range of astrophysical interest. The study of this reaction was done via two distinct experiments. For low energy resonances, up to 500 keV above the threshold of proton emission, the 30Si(3He,d)31P transfer reaction was performed at the Tandem of the MLL laboratory in Munich. The light particles produced during the reaction were momentum analyzed by the very high resolution Q3D magnetic spectrometer and their angular distributions were interpreted in the DWBA (Distorted Wave Born Approximation) framework to obtain the proton spectroscopic factors. These are essential for the calculation of the proton widths used to compute the strengths of the resonances. For higher energy resonances, a direct measurement of the resonance strengths was performed using the DRAGON recoil spectrometer installed at TRIUMF in Vancouver, Canada. The results of these experiments were used to calculate the new rate of the 30Si(p,γ)31P reaction and its astrophysical impact was studied in order to better constrain the stellar conditions that can explain the abundances observed in the stars of the globular cluster NGC 2419. (author)
Abstract (French)
Les amas globulaires sont des objets essentiels pour etudier les modeles d'evolution stellaire et les premieres phases de la formation des galaxies. Les anomalies d'abondance observees dans l'amas globulaire NGC 2419, telles que la surabondance de potassium et la depletion de magnesium, peuvent etre expliquees si une generation anterieure d'etoiles contamine les etoiles actuellement observees. Cependant, la nature et les proprietes de cette premiere generation d'etoiles ne sont pas clairement identifiees. La plage de temperatures et de densites de celle-ci depend d'un certain nombre de taux de reaction. La reaction 30Si(p,γ)31P est l'une des rares reactions identifiees comme ayant une influence suffisante permettant de contraindre la nature du ou des sites stellaires ayant contamine NGC 2419. L'objectif de cette these est de reduire les incertitudes nucleaires associees a la reaction 30Si(p,γ)31P en determinant les forces de resonances dans la gamme d'energie d'interet astrophysique. L'etude de cette reaction s'est faite via deux experiences distinctes. Pour les resonances a basse energie, jusqu'a 500 keV au-dessus du seuil de l'emission proton, la reaction de transfert 30Si(3He,d)31P a ete realisee au Tandem du laboratoire MLL a Munich. Les particules legeres produites au cours de la reaction ont ete analysees en moment par le spectrographe magnetique Q3D de tres haute resolution et leurs distributions angulaires ont ete interpretees dans le cadre de la DWBA (Distorded Wave Born Approximation) pour obtenir les facteurs spectroscopiques proton. Ces derniers sont essentiels pour le calcul des largeurs proton servant a calculer les forces des resonances. Pour les resonances a plus haute energie, une mesure directe des forces de resonances a ete effectuee a l'aide du separateur de recul DRAGON installe a TRIUMF a Vancouver au Canada. Les resultats de ces experiences ont ete utilises pour calculer le nouveau taux de la reaction 30Si(p,γ)31P et son impact astrophysique a ete etudie afin de mieux contraindre les conditions stellaires pouvant expliquer les abondances observees dans les etoiles de l'amas globulaire NGC 2419. (auteur)
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Additional details
Additional titles
- Original title (English)
- Etude experimentale de la reaction 30Si(p,γ)31P pour comprendre les anomalies nucleosynthetiques dans les amas globulaires
Publishing Information
- Imprint Pagination
- 251 p.
- Report number
- FRNC-TH--14827
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 54102332
- Subject category
- S73: NUCLEAR PHYSICS AND RADIATION PHYSICS;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- DATA ANALYSIS; DIFFERENTIAL CROSS SECTIONS; DWBA; HELIUM 3 REACTIONS; KEV RANGE; MEV RANGE; ONE-NUCLEON TRANSFER REACTIONS; PHOSPHORUS 31; PROTON REACTIONS; SILICON 30 TARGET; STAR EVOLUTION
- Descriptors DEC
- APPROXIMATIONS; BARYON REACTIONS; BORN APPROXIMATION; CALCULATION METHODS; CHARGED-PARTICLE REACTIONS; CROSS SECTIONS; DATA PROCESSING; DIRECT REACTIONS; ENERGY RANGE; EVOLUTION; HADRON REACTIONS; ISOTOPES; LIGHT NUCLEI; NUCLEAR REACTIONS; NUCLEI; NUCLEON REACTIONS; ODD-EVEN NUCLEI; PHOSPHORUS ISOTOPES; PROCESSING; STABLE ISOTOPES; TARGETS; TRANSFER REACTIONS
Optional Information
- Notes
- 123 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses