arXiv subjects

J. F. McCann

Publications and source records attributed to J. F. McCann.

21 records · Page 2Linked to original sources

arXiv1998

Output coupling and flow of a dilute Bose-Einstein condensate

We solve the Gross-Pitaevskii equation to model the behaviour of a weakly-interacting Bose condensate. Solutions are presented for the eigenstates in one- and two-dimensional harmonic traps. We include the effect of gravity and coupling to a second condensate to simulate an output coupler for Bose condensed atoms, and find that the output pulse shape is in qualitative agreement with experiment. We also model flow under gravity through a constriction, demonstrating excitation and separation of eigenmodes in the condensate.

cond-mat.stat-mech↗

arXiv1997

Vortex formation in weakly-interacting inhomogeneous Bose condensates

We solve the time-dependent Gross-Pitaevskii in 2-D to simulate the flow of an object through a dilute Bose condensate trapped in a harmonic well. We demonstrate vortex formation and analyze the process in terms of the accumulation of phase-slip and the evolution of the fluid velocity.

cond-mat.stat-mech↗

arXiv1997

The distorted-wave impulse approximation for electron capture into excited states

Total cross sections for electron capture are calculated for collisions of fast protons and alpha-particles with atomic hydrogen. The distorted- wave impulse approximation is applied over the energy range 10-1500 keV/u. State-selective results are given for the 1s, 2s and 2p levels. Both the 'post' and 'prior' forms of the model are calculated and compared with results from other theories and experimental measurements. In general the model performs very well in comparison with experiment over this energy range though discrepancies arise at lower energies.

physics.atom-ph↗