2.1
Alpha capture reaction of
113
In in the p-process energy range
C. Yalçın a) , R. T. Güray a) , N. Özkan a) , S. Kutlu a) , Gy. Gyürky, Zs. Fülöp, G. G. Kiss, Z. Elekes,
J. Farkas, E. Somorjai
were able to see clear peak (Eγ=158 keV) coming from 113 In(α,γ)117 Sb reaction. The obtained spectrum is in Figure 1. For the experiment, targets will be prepared by evaporating
highly enriched (93.1%) 113 In onto thin Al foil.
Thus 158keV peak will be about 22 times more
intense at the same energy. This work is in
progress.
100000
Counts
The p-process is one of the least studied nucleosynthesis processes. Due to the lack of experimental data most p-process nucleosynthesis simulations rely on an extensive use of the
Hauser Feshbach model for predicting the relevant reaction rates (e.g. [1]). While the Hauser
Feshbach cross section predictions for proton
capture on intermediate mass nuclei typically
agree well within a factor of two with the observed data [2,3,4], there seem to be considerable discrepancies between the predicted and
observed alpha capture cross sections. This is
underlined by the first results of alpha capture
measurements in this mass range with the goal
to probe the reliability of the Hauser Feshbach
approach for p-process studies [5,6,7]. This has
been interpreted as caused by insufficiencies in
the choice of the alpha potential for the Hauser
Feshbach calculations and considerable effort
has been spent in investigating improved alpha
potential parameters [8,9,10].
113 In(α,γ)117 Sb reaction cross section measurements are being performed at the MGC cyclotron accelerator at energies between 8 MeV
and 12 MeV using the activation method. The
reaction product 117 Sb is relatively long-lived
with half-life of 2.8h. The induced activity
can be determined through the measurement
the characteristic gamma decay transitions of
158keV by using HPGe detector at ATOMKI.
In order to determine target homogeneity
and target stability we made test targets from
natural indium. The targets were prepared
by evaporating natural indium onto thin (d =
2.4µm) Al foil. The Al foil was placed 4.5 cm
above the crucible in a holder defining a circular spot with a diameter of 12mm on the foil for
In deposition. This procedure made it possible
to determine the target thickness by weighing.
The weight of the Al foil was measured before
and after the evaporation with a precision better than 5µg the indium number density could
be determined from the difference.
A test irradiation was made at 12.427MeV
energy with a natural indium target. Although
the natural indium contains 4.29% 113 In, we
10000
158 keV
1000
0
1000
2000
3000
4000
5000
6000
Channel
Figure 1. Measured spectrum from natural indium target for test.
This work was supported by Kocaeli University, Scientific Research Projects Unit [grant
BAP-2007/37] and ERASMUS(LLLP).
a) Kocaeli University, Phys. Dept., 41380, Kocaeli,
Turkey.
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Data Tabl. 75 (2000) 1.
[2] S. Sauter, F. Käppeler, Phys. Rev. C 55, (1997)
3127.
[3] S. Harissopoulos et al., Phys. Rev. C 64 (2001)
055804.
[4] F. Chloupek et al., Nucl. Phys. A652 (1999) 391.
[5] E. Somorjai et al., Astron.&Astrophys. 333 (1998)
1112.
[6] W. Rapp et al., Phys. Rev. C 66, (2002) 015803.
[7] N. Özkan et al., Phys. Rev. C, 75(2), (2007)
025801.
[8] P. Mohr, Phys. Rev. C 61, (2000) 045802.
[9] W. Rapp et al., Phys. Rev. C 68 (2003) 015802.
[10] P. E. Koehler et al., Phys. Rev. C 69 (2004)
015803.
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