Darmstadt 2008 – scientific programme

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A: Fachverband Atomphysik

A 20: Experiments with FLASH and FEL perspectives: an overview

A 20.7: Talk

Thursday, March 13, 2008, 12:45–13:00, 3C

From Fission to Explosion: a Momentum Resolved Survey over the Rayleigh Instability Barrier — •Matthias Hoener¹, Sebastian Schorb¹, Heiko Thomas¹, Lutz Foucar², Thomas Möller¹, and Christoph Bostedt¹ — ¹IOAP, TU Berlin, Germany — ²IKP, Uni Frankfurt a.M., Germany

We investigated the fragmentation processes of Ne (liquid)- and Xe (solid)-clusters with a momentum resolving reaction microscope. Irradiating different sized clusters with different excitation energies leads through Auger decays to a distinct amount of average charge on the clusters. Through variation of inner coulombic energy (E(coul)) and surface tension (E(sur)) we can set the fissility X of the the system (X=E(coul)/2E(sur)) based on the liquid trop model (LDM) for macroscopic particles. The fissility determines the scenario of fragmentation: X < 1, non-isotropic fission into a few large, less energetic ions, X > 1, isotropic explosion into many small, energetic ions. The COLTRIMS system enables us to detect all generated ionic fragments in a momentum resolved manner. In this way we can determine the three dimensional fragmentation geometry in dependance of X and the phases of the clusters. Both, the fragmentation pattern of liquid Ne- and solid Xe-clusters, show a very different behavior for the two regimes. The clusters show for X < 1 a fission-like behavior and for X > 1 an explosion-like behavior in qualitative agreement with the LDM. However, the data show a strong correlation of the fragmentation with the cluster phase.