Three-dimensional Doppler, polarization-gradient, and magneto-optical forces for atoms and molecules with dark states

We theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations. We focus on the case where there are dark states because the atom is driven on a "type-II" system where the angular momentum of the excited state, $F'$, is less than or equal to that of the ground state, $F$. For these systems we find that the force in a three-dimensional light field has very different behaviour to its one dimensional counterpart. This differs from the more commonly used "type-I" systems ($F'=F+1$) where the 1D and 3D behaviours are similar. Unlike type-I systems where, for red-detuned light, both Doppler and sub-Doppler forces damp the atomic motion towards zero velocity, in type-II systems in 3D, the Doppler force and polarization gradient force have opposite signs. As a result, the atom is driven towards a non-zero equilibrium velocity, $v_{0}$, where the two forces cancel. We find that $v_{0}^{2}$ scales linearly with the intensity of the light and is fairly insensitive to the detuning from resonance. We also discover a new magneto-optical force that alters the normal MOT force at low magnetic fields and whose influence is greatest in the type-II systems. We discuss the implications of these findings for the laser cooling and magneto-optical trapping of molecules where type-II transitions are unavoidable in realising closed optical cycling transitions.Comment: 20 pages, 7 figures. Revised version to correct several small typographical errors and clarify the discussion on page 9. Labeling of figure 1 and colours in figure 5 also changed, and additional information provided for equations 13 and 1

The health state preferences and logistical inconsistencies of New Zealanders: a tale of two tariffs

Notwithstanding the proposed use of Cost-Utility Analysis (CUA) to inform health care priority setting in New Zealand, to date there has been no research into New Zealanders’ valuations of health-related quality of life. This paper reports the results of a study of the health state preferences of adult New Zealanders generated from a postal survey to which 1360 people responded (a 50% response rate). The survey employed a self-completed questionnaire in which a selection of health states were described using the EQ-5D health state classification system and respondents’ valuations were sought using a visual analogue scale (VAS). Close attention is paid to the quality of the data, in particular to the ‘logical inconsistencies’ in respondents’ valuations. Regression analysis is used to interpolate values over the 245 possible EQ-5D states. Two tariffs of health state preferences, arising from contrasting treatments of the logical inconsistencies, are reported.New Zealand, EuroQol, EQ-5D

The magnetic reorientation transition in thin ferromagnetic films treated by many-body Green's function theory

This contribution describes the reorientation of the magnetization of thin ferromagnetic Heisenberg films as function of the temperature and/or an external field. Working in a rotating frame allows an exact treatment of the single-ion anisotropy when going to higher-order Green's functions. Terms due to the exchange interaction are treated by a generalized Tyablikov (RPA) decoupling.Comment: 9 pages, 2 figure

Coincident multi-point observations of the E- and F- region decametre-scale plasma waves at high latitudes

Presented is an extensive analysis of the E-region backscatter observed at magnetic latitudes 75°-80°N by the PolarDARN component of the Super Dual Auroral Radar Network (SuperDARN). The statistical occurrence characteristics of the short-range echoes reveal significant differences from those of the auroral and sub-auroral SuperDARN radars