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Accueil du site > Publications récentes > Frustrated fragmentation and re-aggregation in nuclei : A non-equilibrium description in spallation

Frustrated fragmentation and re-aggregation in nuclei : A non-equilibrium description in spallation

P. Napolitani

Atomic nuclei bombarded with protons or deuterons close to the speed of light may become highly unstable.
Most of the times, they decay by evaporating particles and by fissioning into two fragments.
More rarely, it has been observed experimentally that the bombarded nucleus can also divide into two or few fragments in a very short time of around one zeptosecond (10^-21 s), ten times faster than conventional fission.

In this work we found that these very rapid splits, so far not understood, may be explained as a chaotic process driven by two antagonist tendencies.
First of all, the bombarded nucleus enters a condition of mechanical instability : it disintegrates into several pieces, somehow like breaking a glass with sound at the resonance frequency.
Secondly, this disassembly is contrasted by the action of the attractive nuclear force, which tends to re-aggregate the fragments into few or eventually only two nuclei.

This rapid process is responsible for the production of light elements in nuclear reactions induced by cosmic rays, in sub-critical nuclear reactors driven by particle accelerators, and even in hadron-therapy applications.

Voir en ligne : Phys. Rev. C 92, 034607 (2015)


 

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