Dynamics of antiprotons collisions with positronium atom in Debye plasma environments
Mukesh Kumar Pandey1*, Yen-Chang Lin1,2, Yew Kam Ho1
1Institute of Atomic and Molecular Sciences, Academia Sinica,, Taipei, Taiwan
2Graduate Institute of Applied Science and Engineering, Catholic Fu-Jen University, New Taipei, Taiwan
* presenting author:Mukesh Kumar Pandey, email:pandey@pub.iams.sinica.edu.tw
The recently created antihydrogen at CERN [1] and Fermilab [2] has stimulated atomic and molecular physicists to study dynamic of antiparticle and antimatter collisions. Understanding the interaction of antiproton with Ps atom has become an interesting subject ever since the development of low-energy antiproton beams and also because of the exotic nature of Ps atom. Antihydrogen formation in the Ps antiproton collision has recently been realized in experiment at GeV kinetic energies performed at CERN [1]. These collisions however, have not been examined theoretically or experimentally so far under Debye plasma environments. It would, therefore, be worthwhile to make an attempt to understand such interactions that lead to formation of antihydrogen in collisions under Debye plasma environments. In the present work the emphasis is on understanding of the effects of Debye plasmas on the charge exchange and ionization processes in antiproton and Ps collisions.
There are few theoretical and experimental studies on the ionization and charge transfer involving antihydrogen atom [3-6]. But in previous studies [3-6], investigators have been concentrated on the coalitional ionization cross sections in the absence of plasmas. However, most of the environments, in which ionization and charge transfer plays an important role, are not free of plasma effects. For example, the reactions of these atoms may be important in environments such as plasmas, gaseous nebulae, or any type of gaseous discharge medium where ion-electron recombination into a highly excited Rydberg atom might take place. In these environments the presence of microfields is almost guaranteed, and it raises questions on the effect of the field on ionization cross sections. For the unscreened cases, our results are in good agreement with the existing experimental and theoretical predictions. Cross sections are determined in both screening and un-screening environments, and a comparative study between both environments has been carried out. The present calculations have further provided confirmation that the plasma screening effect enhances the ionization cross sections, and reduces the antihydrogen formation cross sections almost at all energies. Detail results will be presented at the meeting.

This work was supported by the Ministry of Science and Technology (MOST) of Taiwan.

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Keywords: antihydrogen, Debye plasmas, antimatter collisions, ionization and charge transfer, CTMC