Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 5: Posters Tuesday (Photoionisation, Multi Photon Processes)
A 5.30: Poster
Dienstag, 3. April 2001, 12:30–15:00, AT3
Threshold laws for four-particle fragmentation — •Valentin Ostrovsky — Institute of Physics, The University of St Petersburg, 198904 St Petersburg, Russia
Break-up of atomic particle into several charged fragments can be achieved by multiple photoionization or by collision processes. The threshold behaviour of fragmentation cross sections generally is described by power laws, σfrag ∼ Eµ, where E is excess energy above break-up threshold. For three charged fragments the threshold law of this type was revealed in the famous paper by Wannier who considered two electrons receding from charged core. The general universal approach to calculation of threshold indices µ was developed recently by Kuchiev and Ostrovsky [1]. In the present contribution we consider in more detail break up into four fragments. The threshold behaviour of these processes remains object of active experimental and theoretical studies. We presume that masses of all fragments are finite and thus fully account for recoil effects. For the fragment charges we consider two possibilities available: (i) two particles with the positive charge and two particles with negative charge; (ii) one particle with positive (negative) charge and three particles with negative (positive) charge. All the fragments have different masses and charges with only one restriction imposed to limit the choice systems considered: it is presumed that two fragments represent identical particles. The threshold indices are evaluated for large number of systems, including systems that contain exotic particles. Some previously suggested threshold laws are revised.
[1] M. Yu. Kuchiev and V. N. Ostrovsky, Phys. Rev. A 58, 321 (1998).