Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 48: Nuclear and Particle Astrophysics IV

HK 48.5: Talk

Thursday, March 11, 2004, 17:30–17:45, F

ERNA: a status report — •Daniel Schürmann — Institut für Experimentalphysik III, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum

The fusion of Carbon and Helium in the nuclear reaction ¹²C(α,γ)¹⁶O takes place in the helium burning phase of red giant stars. This reaction is commonly refered to as a key reaction in nuclear astrophysics. Still the uncertainties of the astrophysical S(E) factor used in stellar model calculations are too large.

To improve this situation we are performing a new measurement of the ¹²C(α,γ)¹⁶O cross section. Previous measurements are mainly based on the detection of the reaction gamma rays. Using the European Recoil separator for Nuclear Astrophysics (ERNA) we will detect the free oxygen recoil nuclei. Therefore a ⁴He gas target is bombarded by a ¹²C ion beam. A combination of two Wien filters and a dipole magnet filters reaction products from beam particles. The oxygen recoils are then identified in an ionisation chamber telescope. Additionally one can detect the gamma rays in coincidence.

The talk will discuss the gas target used in the experiment as well as first measurements. The influence of the charge exchange during the nuclear reaction on the recoil charge state will be shown.

This project is supported by the Deutsche Forschungsgemeinschaft (RO 429/35-2).