1. Elastic alpha scattering experiments
G. G. Kiss
ATOMKI
Debrecen, Hungary

2. Astrophysical p-process
synthesis of the rare, heavy proton-rich isotopes, the so called p-nuclei, which can`t be produced by the s- and r- processes
-induced reactions
high temperature
needed 
explosive scenarios

3. Astrophysical p-process
dominant (,n) reactions complemented
by (,) and (,p) reactions
(g,n) Sn
108
109
110
111
112
113
114
115
116
(g,p)
(g,a) Cd
106
p-abundances  network calculation
( ~ reactions, ~ 2000 nuclei)
reaction rates are calculated using statistical model
nuclear physics input

4. 106Cd(a,g)110Sn
Nucl. Phys. 84, (1966) 177
Nucl. Phys. A707, (2002) 253
Nucl. Phys. A723, (2003) 104

5. 106Cd(a,g)110Sn

6. Experimental tests for global parameterization
Elastic alpha scattering
D. Galaviz et al.,
Phys. Rev. C71 (2006)

7. Present experiments 89Y(a,a)89Y 92Mo 91Zr 93Nb 94Mo 90Zr 89Y 92Zr
Fülöp et al.,
Phys. Rev. C64
(2003)
92Mo
91Zr
93Nb
94Mo
90Zr
89Y
92Zr
N=50
89Y(a,a)89Y
ATOMKI, cyclotron
Ec.m.~ 15.5 and 18.6 MeV
Beam current: 300 nA
Target:
Natural 89Y (100%)
Carbon backing, evaporation
thickness: ~250 μg/cm2
Angular range:
20-100° : 1° step
° : 1.5° step
° : 2° step
G. G. Kiss et al., J. Phys G, in press

8. Present experiments II.
D. Galaviz et al.,
Phys. Rev. C71
(2006) Sn
(50)
112Sn
114Sn
115Sn
116Sn
117Sn
118Sn
119Sn
120Sn
122Sn
124Sn In
111In
113In Cd
106Cd
108Cd
110Cd
111Cd
112Cd
112Sn
113Cd
114Cd
116Cd
G.G.Kiss et al.,
Eur. Phys. J A27
(2005)
106,110,116Cd(a,a)106,110,116Cd
ATOMKI, cyclotron Ec.m.~ 15.5 and 18.9 MeV
Beam current: 300 nA
Target:
Highly enriched (95+%) 106,110,116Cd on carbon backing, evaporation, thickness: ~ 200 μg/cm2
Angular range:
20-120° : 1° step
° : 2.5° step

9. Experimental setup Chamber: 78.8 cm in diameter
beamspot: 2mm in diameter
remote controlled target ladder
6 / 8 ion implanted Silicon
surface barrier detectors
2 turntables with 2 detectors each
Monitor detectors
fixed angle ± 150
corrections to the beam
displacements
Current measurement
with Faraday cup

10. Spectra 89Y(a,a)89Y

11. Angular calibration ≤ ± 0.12º Final angular uncertainties:
Crucial importance for precision
Measured with kinematical coincidence (recoil C-alpha)
(pure carbon backing as target & alpha beam)
Final angular
uncertainties:
≤ ± 0.12º

12. Global parameterizations
U (r) =
VC (r) +
V (r) + iW(r)
Coulomb +
nuclear potential
MacFadden and Satchler [ Nucl. Phys. 84 (1966) 177 ]
4 parameter Woods-Saxon potential
mass and energy independent
Demetriou [ Nucl. Phys. A707 (2002) 253
improvement: AIP conf. proc. 891 (2006) 281 ]
medium mass, double folding parameterization for real part,
mass and energy dependent imaginary potential
Avrigeanu [Nucl. Phys. A723 (2003) 104
improvements: Nucl. Phys. A764 (2006) 246
Phys. Rev. C73 (2006) ]
A ~ 100, volume Woods-Saxon parameterization for the real part
volume + surface Woods-Saxon parameterization for the imaginary part

13. Angular distributions
≤ 5%
Total uncertainties
≤ 0.12º
Total angular uncertainties
G. G. Kiss et al., in preparation

14. Ratio of the elastic scattering cross sections of 92Mo / 89Y
Ec.m. ≈ 15.5 MeV
Ec.m. ≈ 18.6 MeV

15. Summary Reactions involving alpha particles are
playing important role at astrophysics
It is necessary to fix the form of the optical potential
More experimental data is needed
Investigating the variation of the elastic scattering cross section along isotopic
and isotonic chains are useful for
testing global parameterizations

16. Thank you for your attention!
ATOMKI Nucl. Astrophys. Group:
Zs. Fülöp
Gy. Gyürky
Z. Elekes
E. Somorjai
In Collaborations with:
Technische Universität
Darmstadt GERMANY
University of Notre Dame, USA
Instituto De Escructura
De La Materia, SPAIN