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

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