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We study dependence of dipole-dipole interaction in dense Rb vapour on optical excitation. We measure the dipole-dipole contribution to the selective reflection spectrum of D2 line. Optical excitation is created by intense laser beam, which depletes the 5S1/2 population and decreases the dipole-dipole interaction, narrowing the observed spectrum. The limit of the dipole-dipole interaction change is determined by the optical saturation of the D2 transition and corresponds to the 5S1/2 population approximately equal to 1/3.

See the retraction notice E3S Web of Conferences 549, 00001 (2024), https://doi.org/10.1051/e3sconf/202454900001

Charged particle detection systems are widely used in modern atomic physics experiments. In this paper we describe an experimental setup for ultracold plasma (UCP) diagnostics based on the basis of a microchannel plate-based detector (MCP). Two different readout techniques for the MCP output are described in detail. Expansion of the low-density UCP and the frequency-dependent response of the UCP to an external electric field are measured. Preliminary results are obtained.

We report a measurement of the photoionization cross-section of the lithium 2P3/2 state in a magneto-optical trap (MOT) by means of a single-frequency cw laser. Intensity of the photoionizing radiation seen by atoms is determined by means of averaging the intensity distribution of the photoionizing beam over the spatial distribution of trapped atoms. We use the photoionizing laser beam with large waist to reduce a possible misalignment between the photoionizing beam and the MOT density distribution. The excited state fraction is also accurately measured under our MOT conditions. The near-threshold photoionization cross-section of lithium-7 2P3/2 state at λPI = 349.846(1) nm is found to be equal to σ = 13.7(1.4) Mb, with better accuracy in comparison with the previous measurements. We study the variation of the photoionization cross section on the polarization of the ionizing beam. Further experiments are suggested. [ABSTRACT FROM AUTHOR]