Abstract

Cross sections for neutron-induced reactions of short-lived nuclei are essential for nuclear astrophysics since these reactions in the stars are responsible for the production of most heavy elements in the universe. These reactions are also key in applied domains like energy production and medicine. Nevertheless, neutron-induced cross-section measurements can be extremely challenging or even impossible to perform due to the radioactivity of the targets involved. Indirect measurements through the surrogate-reaction method can help to overcome these difficulties.The surrogate-reaction method relies on the use of an alternative reaction that will lead to the formation of the same excited nucleus as in the neutron-induced reaction of interest. The decay probabilities (for fission, neutron and gamma-ray emission) of the nucleus produced via the surrogate reaction allow one to constrain models and the prediction of the desired neutron cross sections.We propose to perform surrogate reaction measurements in inverse kinematics at heavy-ion storage rings, in particular at the CRYRING@ESR of the GSI/FAIR facility. We present the conceptual idea of the most promising setup to measure for the first time simultaneously the fission, neutron and gamma-ray emission probabilities. The results of the first simulations considering the 238U(d,d’) reaction are shown, as well as new technical developments that are being carried out towards this set-up.

Highlights

  • The synthesis of elements from iron to uranium that takes place in stars, can only be understood through the study of neutron reactions on radioactive nuclei [1,2]

  • The promising advantages of performing surrogate reaction experiments in inverse kinematics using heavy-ion storage rings led to the study of the feasibility of this idea proposed by B

  • The transmission efficiency along the storage ring beam line up to the focal point is of 100% for the beam-like 238U residues and of 98.8% for the 237U residues. This shows the power of performing such experiments in inverse kinematics where we can expect a detection efficiencies close to 100%, much larger than the ones obtained in direct kinematics

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Summary

Introduction

The synthesis of elements from iron to uranium that takes place in stars, can only be understood through the study of neutron reactions on radioactive nuclei [1,2]. Density is very high, many neutrons will be captured consecutively and form very heavy isotopes of a certain element before they decay. At the end of the r-process path one can find extremely neutron-rich nuclei in the actinide region. Neutron capture will continue forming new heavy elements that will fission. This will form the so-called fission recycling process and after few cycles the abundances may become dominated by the fission-fragment distributions. Capture measurements require the detection of Ȗ-UD\V LQ WKH SUHVHQFH RI D Ȗ-ray background due to the decay of the target material [3]

Surrogate reactions
Surrogate reactions at Storage Rings൮
Decay probabilities measurements at heavy-ion storage rings
The future setup
Simulations
Solar Cells
Conclusions
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