The Karlsruhe Astrophysical Database of Nucleosynthesis in Stars Project - Status and Prospects

The KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars) project is an astrophysical online database for cross sections relevant for nucleosynthesis in the s process and the γ process. The s-process database (http://www.kadonis.org) was started in 2005 and is presently facing its 4th update (KADoNiS v1.0). The γ-process database (KADoNiS-p, http://www.kadonis.org/pprocess) was recently revised and re-launched in March 2013. Both databases are compilations for experimental cross sections with relevance to heavy ion nucleosynthesis. For the s process recommended Maxwellian averaged cross sections for kT=5-100 keV are given for more than 360 isotopes between 1H and 210Bi. For the γ-process database all available experimental data from (p, γ), (p, n), (p, α), (α, γ), (α, n), and (α, p) reactions between 70Ge and 209Bi in or close to the respective Gamow window were collected and can be compared to theoretical predictions. The aim of both databases is a quick and user-friendly access to the available data in the astrophysically relevant energy regions. © 2014 Elsevier Inc.Peer reviewe

Investigation of alpha-induced reactions on 130Ba and 132Ba and their importance for the synthesis of heavy p nuclei

Captures of alpha particles on the proton-richest Barium isotope, 130Ba, have been studied in order to provide cross section data for the modeling of the astrophysical gamma process. The cross sections of the 130Ba(alpha,gamma)134Ce and 130Ba(alpha,n)133Ce reactions have been measured with the activation technique in the center-of mass energy range between 11.6 and 16 MeV, close above the astrophysically relevant energies. As a side result, the cross section of the 132Ba(alpha,n)135Ce reaction has also been measured. The results are compared with the prediction of statistical model calculations, using different input parameters such as alpha+nucleus optical potentials. It is found that the (alpha,n) data can be reproduced employing the standard alpha+nucleus optical potential widely used in astrophysical applications. Assuming its validity also in the astrophysically relevant energy window, we present new stellar reaction rates for 130Ba(alpha,gamma)134Ce and 132Ba(alpha,gamma)136Ce and their inverse reactions calculated with the SMARAGD statistical model code. The highly increased 136Ce(gamma,alpha)132Ba rate implies that the p nucleus 130Ba cannot directly receive contributions from the Ce isotopic chain. Further measurements are required to better constrain this result.Comment: Accepted for publication in Phys. Rev.

Direct study of the alpha-nucleus optical potential at astrophysical energies using the 64Zn(p,alpha)61Cu reaction

In the model calculations of heavy element nucleosynthesis processes the nuclear reaction rates are taken from statistical model calculations which utilize various nuclear input parameters. It is found that in the case of reactions involving alpha particles the calculations bear a high uncertainty owing to the largely unknown low energy alpha-nucleus optical potential. Experiments are typically restricted to higher energies and therefore no direct astrophysical consequences can be drawn. In the present work a (p,alpha) reaction is used for the first time to study the alpha-nucleus optical potential. The measured 64Zn(p,alpha)61Cu cross section is uniquely sensitive to the alpha-nucleus potential and the measurement covers the whole astrophysically relevant energy range. By the comparison to model calculations, direct evidence is provided for the incorrectness of global optical potentials used in astrophysical models.Comment: Accepted for publication in Physical Review C as a Rapid Communicatio

Cross section measurement of the astrophysically important 17O(p,gamma)18F reaction in a wide energy range

The 17O(p,g)18F reaction plays an important role in hydrogen burning processes in different stages of stellar evolution. The rate of this reaction must therefore be known with high accuracy in order to provide the necessary input for astrophysical models. The cross section of 17O(p,g)18F is characterized by a complicated resonance structure at low energies. Experimental data, however, is scarce in a wide energy range which increases the uncertainty of the low energy extrapolations. The purpose of the present work is therefore to provide consistent and precise cross section values in a wide energy range. The cross section is measured using the activation method which provides directly the total cross section. With this technique some typical systematic uncertainties encountered in in-beam gamma-spectroscopy experiments can be avoided. The cross section was measured between 500 keV and 1.8 MeV proton energies with a total uncertainty of typically 10%. The results are compared with earlier measurements and it is found that the gross features of the 17O(p,g)18F excitation function is relatively well reproduced by the present data. Deviation of roughly a factor of 1.5 is found in the case of the total cross section when compared with the only one high energy dataset. At the lowest measured energy our result is in agreement with two recent datasets within one standard deviation and deviates by roughly two standard deviations from a third one. An R-matrix analysis of the present and previous data strengthen the reliability of the extrapolated zero energy astrophysical S-factor. Using an independent experimental technique, the literature cross section data of 17O(p,g)18F is confirmed in the energy region of the resonances while lower direct capture cross section is recommended at higher energies. The present dataset provides a constraint for the theoretical cross sections.Comment: Accepted for publication in Phys. Rev. C. Abstract shortened in order to comply with arxiv rule

Ultrasound-guided paravertebral puncture and placement of catheters in human cadavers: an imaging study

Background During paravertebral block, the anterolateral limit of the paravertebral space, which consists of the pleura, should preferably not be perforated. Also it is possible that, during the block, the constant superior costotransverse ligament can be missed in the loss-of-resistance technique. We therefore aimed to develop a new technique for an ultrasound-guided puncture of the paravertebral space. Methods We performed 20 punctures and catheter placements in 10 human cadavers. A sonographic view showing the pleura and the superior costotransverse ligament was obtained with a slightly oblique scan using a curved array transducer. After inline approach, injection of 10 ml normal saline confirmed the correct position of the needle tip, distended the space, and enabled catheter insertion. The spread of contrast dye injected through the catheters was assessed by CT scans. Results The superior costotransverse ligament and the paravertebral space were easy to identify. The needle tip reached the paravertebral space without problems under visualization. In contrast, the introduction of the catheter was difficult. The CT scan revealed a correct paravertebral spread of contrast in 11 cases. Out of the remaining, one catheter was found in the pleural space, in six cases there was an epidural, and in two cases there was a prevertebral spread of contrast dye. Conclusions We successfully developed a technique for an accurate ultrasound-guided puncture of the paravertebral space. We also showed that when a catheter is introduced through the needle with the tip lying in the paravertebral space, there is a high probability of catheter misplacement into the epidural, mediastinal, or pleural space