Benutzer:Madrich/Protonium

Steht für das Isotope 1H, siehe auch Protium.

Protonium ist ein exotisches Atom, bei dem ein Proton und ein Antiproton umeinander kreisen. Es gibt zwei Verfahren zu deren Herstellung.

1. Durch Partikelkollision

2. Durch magnetischen Einschluss

Diese Methode wurde erstmalig im "Athena" (Apparatus for High precision Experiment on Neutral Antimatter) im CERN (Geneve) im Jahr 2002 durchgeführt, wurde aber erst 2006 durch Analyse der Daten entdeckt.

Noch zu übersetzen aus dem Englischen...

Protonium is a exotic atom in which a proton and an antiproton orbit each other. There are two known methods to generate protonium. One method involves violent particle collisions. The other method involves putting antiprotons and positrons into the same magnetic cage. The latter method was first used during experiment "Athena" (Apparatus for High precision Experiment on Neutral Antimatter) at CERN (Geneve) in 2002, but it was not until 2006 that scientists realized protonium was generated during the experiment. It is an electrically uncharged boson with zero baryon number.

Reactions involving a proton and an antiproton at high energies give rise to many particle final states. In fact, such reactions are the basis of particle colliders such as the Tevatron at Fermilab. Indirect searches for protonium at LEAR (Low energy antiproton ring in CERN) have used antiprotons impinging on nuclei such as Helium, with unclear results. Very low energy collisions, in the energy range of 10 eV to 1 keV may lead to the formation of the protonium.

Planned experiments will use traps as the source of low energy antiprotons. Such a beam would be allowed to impinge on atomic hydrogen targets, in the field of a laser, which is meant to excite the proton-antiproton pair into a protonium with some efficiency (whose computation is an open theoretical problem). Unbound particles are rejected by bending them in a magnetic field. Since the protonium is uncharged, it will not be deflected by such a field. This undeflected protonium, if formed, would be allowed to traverse a meter of high vacuum, within which it is expected to decay. The decay products would give unmistakable signatures of the formation of the protonium.

There have been theoretical studies of protonium, mainly using non-relativistic quantum mechanics. These give predictions for the binding energy and lifetime of the states. Computed lifetimes are in the range of 0.1 to 10 microseconds. Unlike the hydrogen atom in which the dominant interactions are due to the charge of the electron and the proton, the constituents of the protonium interact dominantly through the strong interactions. Thus multiparticle interactions involving mesons in intermediate states may be important. Hence the production and study of protonium would be of interest also for the understanding of internucleon forces.

[edit] References and external links

   * Antinucleon-nucleon interaction at low energy: scattering and protonium, by Klempt, Eberhard; Bradamante, Franco; Martin, Anna; Richard, Jean-Marc (2002) Physics Reports vol 368, pp 119-316;
   * Antimatter and matter combine in chemical reaction - A 2002 "antichemistry" experiment at CERN revealed in October 2006.