Determination of the stellar n,gamma cross section of 40Ca with accelerator mass spectrometry - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




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Abstract: The stellar n,gamma cross section of 40Ca at kT=25 keV has been measuredwith a combination of the activation technique and accelerator massspectrometry AMS. This combination is required when direct off-line countingof the produced activity is compromised by the long half-life and-or missinggamma-ray transitions. The neutron activations were performed at the KarlsruheVan de Graaff accelerator using the quasistellar neutron spectrum of kT=25 keVproduced by the 7Lip,n7Be reaction. The subsequent AMS measurements werecarried out at the Vienna Environmental Research Accelerator VERA with a 3 MVtandem accelerator. The doubly magic 40Ca is a bottle-neck isotope inincomplete silicon burning, and its neutron capture cross section determinesthe amount of leakage, thus impacting on the eventual production of iron groupelements. Because of its high abundance, 40Ca can also play a secondary role as-neutron poison- for the s-process. Previous determinations of this value atstellar energies were based on time-of-flight measurements. Our method uses anindependent approach, and yields for the Maxwellian-averaged cross section atkT=30 keV a value of 30 keV= 5.73+-0.34 mb.



Author: I. Dillmann, C. Domingo-Pardo, M. Heil, F. Käppeler, A. Wallner, O. Forstner, R. Golser, W. Kutschera, A. Priller, P. Steier, A.

Source: https://arxiv.org/



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