R. Plag

Pulse shape analysis of liquid scintillators for neutron studies

The acquisition of signals from liquid scintillators with Flash ADC of high sampling rate ð 1G S=sÞ has been investigated. The possibility to record the signal waveform is of great advantage in studies with g’s and neutrons in a high count-rate environment, as it allows to easily identify and separate pile-up events. The shapes of pulses produced by g-rays and neutrons have been studied for two different liquid scintillators, NE213 and C6D6: A 1-parameter fitting procedure is proposed, which allows to extract information on the particle type and energy. The performance of this method in terms of energy resolution and n=g discrimination is analyzed, together with the capability to identify and resolve pile-up events. r 2002 Elsevier Science B.V. All rights reserved.

KADoNiS‐ The Karlsruhe Astrophysical Database of Nucleosynthesis in Stars

The “Karlsruhe Astrophysical Database of Nucleosynthesis in Stars” (KADoNiS) project is an online database for experimental cross sections relevant to the s process and p process. It is available under http://nuclear‐astrophysics.fzk.de/kadonis and consists of two parts. Part 1 is an updated sequel to the previous Bao et al. compilations from 1987 and 2000 for (n,γ) cross sections relevant to the big bang and s‐process nucleosynthesis. The second part will be an experimental p‐process database, which is expected to be launched in winter 2005/06. The KADoNiS project started in April 2005, and a first partial update is online since August 2005. In this paper we present a short overview of the first update of the s‐process database, as well as an overview of the status of stellar (n,γ) cross sections of all 32 p isotopes.

An optimized C6D6 detector for studies of resonance-dominated (n, γ) cross-sections

Hydrogen-free scintillators are indispensable for determining the small, resonance-dominated neutron capture cross-sections of light and neutron magic nuclei, data which are needed for advanced reactor concepts, for transmutation of radioactive wastes as well as for astrophysical scenarios of neutron capture nucleosynthesis. A critical comparison of the existing detector concepts by means of detailed GEANT simulations revealed large differences in neutron sensitivity. Based on these simulations, an optimized detector was developed and successfully tested. Compared to a commercial detector, the neutron sensitivity of this solution is more than an order of magnitude lower, thus allowing even extremely small capture/scattering ratios to be measured reliably.

PINO-a tool for simulating neutron spectra resulting from the 7Li(p,n) reaction

The 7 Li(p,n) reaction in combination with a 3.7 MV Van de Graaff accelerator was routinely used at FZK to perform activation as well as time-of-flight measurements with neutrons in the keV-region. Planned new setups with much higher proton currents like SARAF and FRANZ and the availability of liquid-lithium target technology will trigger a renaissance of this method. A detailed understanding of the neutron spectrum is not only important during the planning phase of an experiment, but also during for the analysis of activation experiments. Therefore, the Monte-Carlo based program PINO (Protons In Neutrons Out) was developed, which allows the simulation of neutron spectra considering the geometry of the setup and the proton-energy distribution.

The C 14 ( n , γ ) cross section between 10 keV and 1 MeV

The neutron capture cross section of 14C is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The 14C(n,gamma) reaction is also important for the validation of the Coulomb dissociation method, where the (n,gamma) cross section can be indirectly obtained via the time-reversed process. So far, the example of 14C is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the 14C(n,gamma) reaction with neutron energies ranging from 20 to 800 keV.

Accuracy of the Pulse Height Weighting Technique for Capture Cross Section Measurements

The accuracy of the pulse height weighting technique for the measurement of neutron capture (n,γ) cross sections is investigated. Detailed Monte Carlo simulations of capture measurements are compared to experimental data. Several causes of systematic deviation are investigated and their effect is quantified.

First measurement of the 96Ru( p,γ )97Rh cross section for the p process with a storage ring

This work presents a direct measurement of the

Sensitivity study for s process nucleosynthesis in AGB stars

^{96}

Neutron activation of natural zinc samples at kT = 25 keV

Ru(

KADoNiS-

p, \gamma