418 research outputs found
Can we observe the gravitational quantum states of Positronium?
In this paper we consider the feasibility of observing the gravitational
quantum states of positronium. The proposed scheme employs the flow-throw
technique used for the first observation of this effect with neutrons.
Collimation and Stark deceleration of Rydberg positronium atoms allow to select
the required velocity class. If this experiment could be realized with
positronium it would lead to a determination of g for this matter-antimatter
system at the few % level. As discussed in this contribution, most of the
required techniques are currently available but important milestones have to be
demonstrated experimentally before such an experiment could become reality.
Those are: the efficient focusing of a bunched positron beam, Stark
deceleration of Rydberg positronium and its subsequent excitation into states
with large angular momentum. We provide an estimate of the efficiencies we
expect for these steps and assuming those could be confirmed we calculate the
signal rate.Comment: 12 pages, 1 figure, contribution to the GRANIT 2014 workshop: Quantum
gravitationnal spectroscopy with ultra-cold system
Antideuteron production in proton-proton and proton-nucleus collisions
The experimental data of the antideuteron production in proton-proton and
proton-nucleus collisions are analyzed within a simple model based on the
diagrammatic approach to the coalescence model. This model is shown to be able
to reproduce most of existing data without any additional parameter.Comment: To appear in Eur. Phys. J A (2002
Quantum ballistic experiment on antihydrogen fall
We study an interferometric approach to measure gravitational mass of
antihydrogen. The method consists of preparing a coherent superposition of
antihydrogen quantum state localized near a material surface in the
gravitational field of the Earth, and then observing the time distribution of
annihilation events followed after the free fall of an initially prepared
superposition from a given height to the detector plate. We show that a
corresponding time distribution is related to the momentum distribution in the
initial state that allows its precise measurement. This approach is combined
with a method of production of a coherent superposition of gravitational states
by inducing a resonant transition using oscillating gradient magnetic field. We
estimate an accuracy of measuring the gravitational mass of antihydrogen atom
which could be deduced from such a measurement.Comment: arXiv admin note: text overlap with arXiv:1403.478
Quantum reflection of antihydrogen from nanoporous media
We study quantum reflection of antihydrogen atoms from nanoporous media due
to the Casimir-Polder (CP) potential. Using a simple effective medium model, we
show a dramatic increase of the probability of quantum reflection of
antihydrogen atoms if the porosity of the medium increases. We discuss the
limiting case of reflections at small energies, which have interesting
applications for trapping and guiding antihydrogen using material walls
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