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The stable nuclide 22Ne plays an important role in astrophysical novae, and in supernovae where it provides neutrons for neutron-capture driven nucleosynthesis. In a hydrogen-rich scenario, 22Ne is mainly destroyed by the 22Ne(p,γ)23Na reaction. Only upper limits exist on the cross section of this reaction at relevant energies.
Currently, a systematical study of this reaction is being performed at LUNA. The experiment, which is based on a windowless gas target system, takes place in two phases. The recently completed first phase concentrated on the study of selected low-energy resonances using two high-purity germanium detectors The second phase, started in November 2014, using a 4π bismuth germanate summing crystal, will push the lowest energy limit even further down.
This new scintillator based measurement setup will require a new data acquisition system: In order to restore the full energy of the gamma peak, the signals of the eight BGO crystals have to be summed up. Classically, this task is done by a carefully executed gain matching of the photomultiplier tubes and an analog summing circuit. However, the recent developments in the field of digital data-acquisition made such systems obsolete.
A digitizer-based system can considerably simplify the experimental setup and make the measurement more robust. However, the shift between the analog and digital world is not always smooth. In my talk, I would like to explore the advantages and disadvantages of such systems with respect to the BGO phase of the 22Ne(p,γ)23Na experiment.
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Marcell Takács
Helmholtz-Zentrum Dresden-Rossendorf