Calculation of density matrices in the formation of positronium

Journal Article · Thu Apr 15 04:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.81.042502· OSTI ID:21408592

Swaminathan, Sudha R ^[1]

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1. Department of Physical and Earth Sciences, Worcester State College 486 Chandler Street, Worcester, Massachusetts 01602 (United States)

We study single collisions between spin-polarized positron beams and targets that result in the production of positronium and target ions. We consider unpolarized as well as polarized targets with 0,1, and 2 unpaired electrons. First, we use angular momentum coupling to calculate the spin scattering matrices in all three cases. Then, for some targets, we define an angle {beta} between the polarization vectors of the positron beam and the target, and calculate density matrices whose elements are functions of {beta}. Finally, from the density matrices, we obtain the probabilities of forming para- and ortho-positronium atoms for specific spins of the target ions. We present ratios of para- to ortho-positronium yields as well as total positronium annihilation rates.

• OSTI ID: 21408592
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 81; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR MOMENTUM
ANNIHILATION
ATOMS
BEAMS
CHARGED PARTICLES
COUPLING
DENSITY MATRIX
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
INTERACTIONS
IONS
LEPTON BEAMS
LEPTONS
MATRICES
ORIENTATION
PARTICLE BEAMS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
POLARIZATION
POLARIZED TARGETS
POSITRON BEAMS
POSITRONIUM
PROBABILITY
SPIN
SPIN ORIENTATION
TARGETS
TENSORS
VECTORS