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Title: Magnetobound positronium and protonium

Abstract

The formation of magnetobound positronium and protonium is investigated via classical trajectory simulations of binary point charge interactions in an external magnetic field. A magnetobound state is a predicted pair-particle system that is temporarily bound due to the presence of an external magnetic field. The magnetic field constrains the motion of charged particles in the direction perpendicular to it, while allowing them to move freely in the parallel dimension. At large separations, each particle undergoes helical motion with an adiabatically invariant magnetic moment. As the charges approach each other, the electric interaction breaks the adiabatic constant of the motion, and the particles may temporarily behave as a highly correlated pair. The results of computer simulations of the fully three-dimensional trajectories of classical and non-relativistic point charges with the same mass, equal charge magnitude, and opposite sign are reported. The simulations show the formation of magnetobound positronium and protonium. The results yield formation cross sections, which are compared to analytical expressions. Additionally, the results reveal that magnetobound states drift across magnetic field lines. Observations on the drift distance, lifetime, and drift speed of simulated magnetobound states are reported.

Authors:
;  [1]
  1. Department of Physics, University of North Texas, Denton, Texas 76203 (United States)
Publication Date:
OSTI Identifier:
22303586
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPUTERIZED SIMULATION; CROSS SECTIONS; MAGNETIC FIELDS; MAGNETIC MOMENTS; POINT CHARGE; POSITRONIUM; PROTONIUM; RELATIVISTIC RANGE

Citation Formats

Correa, J. R., and Ordonez, C. A., E-mail: cao@unt.edu. Magnetobound positronium and protonium. United States: N. p., 2014. Web. doi:10.1063/1.4894107.
Correa, J. R., & Ordonez, C. A., E-mail: cao@unt.edu. Magnetobound positronium and protonium. United States. doi:10.1063/1.4894107.
Correa, J. R., and Ordonez, C. A., E-mail: cao@unt.edu. Fri . "Magnetobound positronium and protonium". United States. doi:10.1063/1.4894107.
@article{osti_22303586,
title = {Magnetobound positronium and protonium},
author = {Correa, J. R. and Ordonez, C. A., E-mail: cao@unt.edu},
abstractNote = {The formation of magnetobound positronium and protonium is investigated via classical trajectory simulations of binary point charge interactions in an external magnetic field. A magnetobound state is a predicted pair-particle system that is temporarily bound due to the presence of an external magnetic field. The magnetic field constrains the motion of charged particles in the direction perpendicular to it, while allowing them to move freely in the parallel dimension. At large separations, each particle undergoes helical motion with an adiabatically invariant magnetic moment. As the charges approach each other, the electric interaction breaks the adiabatic constant of the motion, and the particles may temporarily behave as a highly correlated pair. The results of computer simulations of the fully three-dimensional trajectories of classical and non-relativistic point charges with the same mass, equal charge magnitude, and opposite sign are reported. The simulations show the formation of magnetobound positronium and protonium. The results yield formation cross sections, which are compared to analytical expressions. Additionally, the results reveal that magnetobound states drift across magnetic field lines. Observations on the drift distance, lifetime, and drift speed of simulated magnetobound states are reported.},
doi = {10.1063/1.4894107},
journal = {Physics of Plasmas},
number = 8,
volume = 21,
place = {United States},
year = {Fri Aug 15 00:00:00 EDT 2014},
month = {Fri Aug 15 00:00:00 EDT 2014}
}
  • Using the model for the nucleon-antinucleon interaction proposed by Ball and Chew, the capture rates for the various eigenstates of protonium, the bound system of a proton and an antiproton were calculated. It was found that these rates depend sensitively on spin, isotopic spin. and total angular momentum eigenvalues of protonium. not just on orbital angular momentum, as was usually assumed. The average capture rates for the nS and nP states were 5 3 x l0/sup 18/ /n/sup 3/ and 4.3 x l0/sup 14//n/sup 3/ sec/sup -1/, respecti vely. This P capture rate was two orders of magnitude larger thanmore » in the case of the (K/sup -/ - p) atom because of the relatively long range of interaction in the Ball-Chew model. The problem of the Stark effect collisions, studied by Day, Snow, and Sacher in connection with the (K- - p) atom, was therefore re-investigated. Centain impontant effects which were not considered by these authors were studied. Rough calculations indicated that for protonium the capture would take place predominantly from S sthtes. (auth)« less