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A. Lefebvre-Schuhl. Athens 2009 March 11 th. Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse. Nuclear structure and fundamental interactions Solid state physics Material irradiation Micrometeorite research and study Astrophysics Nuclear astrophysics. - PowerPoint PPT Presentation
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• Nuclear structure and fundamental interactions
• Solid state physics
• Material irradiation
• Micrometeorite research and study
• Astrophysics
• Nuclear astrophysics
Centre de Spectrométrie Nucléaire et Centre de Spectrométrie Nucléaire et de Spectrométrie de Massede Spectrométrie de Masse
A. Lefebvre-Schuhl
Athens 2009 March 11th
JANNuSJANNuS
• Implantation with 2 ions beams
• Thin targets characterization
• In situ observation with the TEM
SEMIRAMISSEMIRAMIS A. Lefebvre-Schuhl
Athens 2009 March 11th
Joint Accelerators for Nano-sciences and Nuclear Simulation
Ion beam analysis + channeling
Irradiation & implantationTandem 2 MV
190 kV200 kV
Y. Serruys et al. Nucl. Instr. and Meth. B240 (2005) 124
detection
135° DoublyFocusing
Magnet
• Electromagnetic isotope separator
• Direct isotope collection
• Preparation of thin targets
SIDONIESIDONIE
A. Lefebvre-Schuhl
Athens 2009 March 11th
Central stellar nucleosynthesis:• nuclear reaction predominantly at low energies• in a narrow energy window: Gamow peak
Example: 7Be(p,)8B (solar interior) • stellar temperature: T = 1.5 x 107 K• 12 E 24 keV
very low projectile energies in the laboratory Charged particle induced nuclear reactions Coulomb barrier
Very low energies very low cross sections (~1 nb)high ion beam currents (up to 1mA)
and high detection efficiency for the reaction products.A. Lefebvre-Schuhl
Athens 2009 March 11th
Nuclear astrophysicsNuclear astrophysics
PAPAPPAPAPPetit Accélérateur Pour l’AstroPhysique
G. Bogaert et al. Nucl. Instr. and Meth. B89 (1994) 8A. Lefebvre-Schuhl
Athens 2009 March 11th
250 kV proton accelerator for applications in nuclear astrophysics high proton beam currents in the range of 0.5 mA
coupling with a superconducting solenoidal spectrometer SOLENO for studies of particle emitting reactions
SOLENOSOLENO
Requirements: • high detection efficiency• scattered protons and emitted -particles separation
Henri THUREL
A. Lefebvre-Schuhl
Athens 2009 March 11th
F. Hammache et al.,Phys. Rev. Lett. 86 (2001) 3985
p
cible
B=3 Teslas
Low energy measurements of the Low energy measurements of the 77Be(p,Be(p,))88B B cross sectioncross section
6 detectors (plastic scintillators)
efficiency: 25 %
24 -detectors (Si detectors) 100o < < 160o
efficiency : 11.5 % for 1 MeV < E < 3.36 MeV
GEANT simulation of the experiment
Cross section measurement for Ec.m. 185.8, 134.7, and 111.7 keV with a radioactive 7Be target (132 mCi)
(target thickness: RBS and (d,p) profile analysis)S(0)
A. Lefebvre-Schuhl
Athens 2009 March 11th
1717O and O and 1818F nucleosynthesisF nucleosynthesis
• Various stellar sites such as classical novae• Before 2004: very large uncertainties on the thermonuclear
rates of these two reactions in the temperature range of classical novae (T = 0.01–0.4 GK)
• New resonance at Ecm= 183.3 keV in the 17O(p,α)14N reaction Resonance strength measurement relatively to the
Ecm= 150.9 keV 18O(p,α)15N resonance:
ωγp= (1.6 ± 0.2) 10-3 eV Excitation energy: 5789.8 ± 0.3 keV for the 18F level• Activation method for the 17O(p,γ)18F reaction study
Resonance strength : ωγpγ = (2.2 ± 0.4) 10-6 eV
In hydrogen-burning nucleosynthesis: 17O(p,α)14N and 17O(p,γ)18F reaction rates
A. Lefebvre-Schuhl
Athens 2009 March 11th
1717O and O and 1818F nucleosynthesisF nucleosynthesis
• 17O(p, α)14N rate now well established below T = 1.5 GKUncertainties reduced by orders of magnitude in T= 0.1–0.4
GK
• 17O(p,γ)18F rate Larger uncertainty because of remaining obscurities in the
knowledge of the direct capture process
Important consequences for 17O nucleosynthesis
and γ-ray emission of classical novae
In hydrogen-burning nucleosynthesis: 17O(p,α)14N and 17O(p,γ)18F reaction rates
A. Chafa et al. Phys. Rev. Lett. 95 (2005) 031101A. Chafa et al. Phys. Rev. C75 (2007) 035810
A. Lefebvre-Schuhl
Athens 2009 March 11th
• Target study– stability under high beam currents– purity vs unwanted induced reactions
• Detection study : – expected cross section– scattered incident particles
• …
Each study is particular and needs time to be succesfull
1919F(p,F(p,))1616OO1313C(C(,n),n)1616O O beam beam
A. Lefebvre-Schuhl
Athens 2009 March 11th