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J Mitroy

Publications and source records attributed to J Mitroy.

At least 19 recordsLinked to original sources
PubMed2006

Existence of a 2P(o) excited state for the e+ Ca system.

The configuration interaction method is used to demonstrate that there is an electronically stable state of positronic calcium with an orbital angular momentum of L=1. This prediction relies on the use of an asymptotic series to estimate the variational limit of the energy. The best estimate of the binding energy is 37 meV. A discussion of the structure of the system is also presented.

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PubMed2005

Positron-atom complexes as quantum halo states.

The wave functions of a number of positron-atom complexes are analyzed and three of the systems, namely, e(+)Be, e(+)Na, and e(+)He((3)S(e)), are seen to exhibit quantum halo structures with 45%-50% of their probability distribution lying in the large r classically forbidden region. The mean square distance between the large r fragments (e(+) + Be, Ps + Na+, Ps + He+) for these systems range from 1.8 to 2.2 times larger than the square of the classical turning point, another indication of their halolike nature.

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PubMed2003

Spin-orbit quenching of positronium during atomic collisions.

When positrons are injected into a gas, 75% of the positronium (Ps) is likely to be formed as long-lived ortho-Ps. The main decay mechanisms for the ortho-Ps have been assumed to be natural decay of ortho-Ps and pickoff annihilation of the positron during Ps-atom collisions. A third possibility for annihilation is ortho-Ps-->para-Ps conversion due to the spin-orbit interaction between the atom and colliding Ps. This extra quenching mechanism may explain a number of phenomena observed in the annihilation spectrum of Kr and Xe, including the very small Ps fraction of 3% seen for Xe.

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PubMed2001

Elastic positronium-atom scattering using the stochastic variational method.

The stochastic variational method is used in conjunction with stabilization ideas to compute the low energy phase shifts and scattering lengths for positronium-atom scattering. Results are obtained for the Ps-H, Ps- Li+, Ps-He, and Ps-Ps systems. The Ps-H scattering lengths are probably accurate to better than 5% and are the most accurate so far computed. The results for Ps- Li+ and Ps-Ps scattering represent the first published scattering lengths for these systems. The positive scattering length for completely spin-aligned 3Ps-3Ps scattering, namely 2.95a(0), is particularly significant since it demonstrates the feasibility of forming a stable Bose-Einstein condensate of 3Ps atoms.

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