A multi-photon magneto-optical trap

We demonstrate a Magneto-Optical Trap (MOT) configuration which employs optical forces due to light scattering between electronically excited states of the atom. With the standard MOT laser beams propagating along the {\it x}- and {\it y}- directions, the laser beams along the {\it z}-direction are at a different wavelength that couples two sets of {\it excited} states. We demonstrate efficient cooling and trapping of cesium atoms in a vapor cell and sub-Doppler cooling on both the red and blue sides of the two-photon resonance. The technique demonstrated in this work may have applications in background-free detection of trapped atoms, and in assisting laser-cooling and trapping of certain atomic species that require cooling lasers at inconvenient wavelengths.Comment: 10 pages, 5 figure

Quantum interference and light polarization effects in unresolvable atomic lines: application to a precise measurement of the 6,7 Li D2 lines

We characterize the effect of quantum interference on the line shapes and measured line positions in atomic spectra. These effects, which occur when the excited state splittings are of order the excited state line widths, represent an overlooked but significant systematic effect. We show that excited state interference gives rise to non-Lorenztian line shapes that depend on excitation polarization, and we present expressions for the corrected line shapes. We present spectra of 6,7 Li D lines taken at multiple excitation laser polarizations and show that failure to account for interference changes the inferred line strengths and shifts the line centers by as much as 1 MHz. Using the correct lineshape, we determine absolute optical transition frequencies with an uncertainty of <= 25kHz and provide an improved determination of the difference in mean square nuclear charge radii between 6 Li and 7 Li. This analysis should be important for a number of high resolution spectral measurements that include partially resolvable atomic lines.Comment: 13 pages, 11 figures, 7 tables, typos in appendix tables V and VI correcte

Immigrants, Crime, and the American Dream: Testing a Segmented Assimilation Theory of Crime

The immigrant-crime relationship is often misunderstood and highly complex. To date, criminological research has largely ignored theory testing of this relationship. This paper examines the extant literature on intergenerational offending amongst immigrant youth and subsequently tests whether the segmented assimilation theory- a theory borrowed from the interdisciplinary social sciences- adequately explains immigrant offending. The study uses data ( N = 1,267) from the Pathways to Desistance Study (PTD) to examine intergenerational differences in changes to offending between immigrant youth and the native-born. The analyses largely reveal that the theory, based on its original assumptions, fails to adequately explain youth offending, and that the models provide more support for the straight-line theory of assimilation in regards to delinquency. Limitations and recommendations are discussed and proffered, respectively. </jats:p