S. D. Bergeson

We report an optical dipole trap for calcium. The trap is created by focusing a 488 nm argon-ion laser beam into a calcium magneto-optical trap. The argon-ion laser photo-ionizes atoms in the trap because of a near-resonance with the 4s4f 1F3 level. By measuring the dipole trap decay rate as a function of argon-ion laser intensity, we determine the 1F3 photo-ionization cross section at our wavelength to be approximately 230 Mb.

We report the creation of an ultracold neutral plasma by photoionization of laser-cooled xenon atoms. The charge carrier density is as high as 2 x 10^9 cm^-3, and the temperatures of electrons and ions are as low as 100 mK and 10 uK, respectively. Plasma behavior is evident in the trapping of electrons by the positive ion cloud when the Debye screening length becomes smaller than the size of the sample. We produce plasmas with parameters such that both electrons and ions are strongly coupled.