We report the confinement and cooling of an optically dense cloud of neutral sodium atoms by radiation pressure. The trapping and damping forces were provided by three retroreflected laser beams propagating along orthogonal axes, with a weak magnetic field used to distinguish between the beams. We have trapped as many as 10 7 atoms for 2 min at densities exceeding lOll atoms cm-3. The trap was =0.4 K deep and the atoms, once trapped, were cooled to less than a millikelvin and compacted into a region less than 0.5 mm in diameter.
We have observed that two-body collisions between cold sodium atoms confined within a magnetic-molasses optical trap lead to significant atomic-density-dependent trap losses. Such losses set an upper limit to the product of atomic density and confinement time that can be achieved in such a trap.
Neutral sodium atoms have been continuously loaded into a 0. 1-k-deep superconducting magnetic trap with laser light used to slow and stop them. At least 1x10 atoms were trapped with a decay time of 2 -, ' min. The fluorescence of the trapped atoms was studied as a function of time; possible loss mechanisms from the trap are discussed.PACS numbers: 32.80.PjTrapping neutral atoms and cooling them to microkelvin temperatures will make possible a variety of experiments including precision spectroscopy, atomic collision studies in the s-wave-only regime, and studies of collective behavior including, possibly, Bose condensation. This Letter reports several important advances toward the accomplishment of such experiments. We have continuously stopped thermal sodium atoms with laser light and continuously loaded them into a 0. 1-K-deep superconducting magnetic trap. The continuous loading process has allowed us to accumulate up to 1&10 trapped atoms. This is 4 orders of magnitude more than for the previous magnetic trapping results of Migdall et al. , ' and 6 orders of magnitude more than Chu et al. obtained with use of an optical trap. We have observed trapping times of up to 2 -, ' min. -2 orders of magnitude greater than in these previous experiments -and studied the fluorescence of the trapped atoms. These increases in trapping time and number of trapped atoms will permit useful experiments with the trapped atoms for the first time. The trap has the added feature of having a uniform magnetic field at its bottom, opening up the possibility of precision spectroscopy of the trapped atoms.The arrangement of longitudinal magnetic fields, laser beams, and fluorescence detectors used in our experiment is shown in Fig. 1. The magnetic fields are generated by superconducting magnets operated in a persistent mode.
We demonstrate high resolution reduction imaging in the soft x-ray spectral region using multilayer-coated reflective optics. In particular, a Schwarzschild objective was used at 20:1 reduction with 14 nm radiation to image line and space features from a transmission mask onto a resist-coated silicon wafer with a resolution better than 0.1 μm. The mirrors of the objective were coated with Mo/Si multilayers to provide nearly 40% reflectance at near-normal incidence for the 14 nm radiation. Our results demonstrate that multilayer coatings are capable of enhancing the reflectance of optical components at soft x-ray wavelengths without significantly degrading their imaging performance.
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