We present measurements of loading and loss rates for a vapor-cell optical trap of the two naturally occurring potassium isotopes 39 K and 41 K. The unresolved excited-state hyperfine structure makes trapping of K fundamentally different from trapping of the other alkalis and leads to an enhanced loading rate. We measure the loading rate as a function of laser intensity, beam size, and detuning and find that the results are in reasonable agreement with a simple rate-equation model for the loading process. The dependence of the loss rate on trapped-atom density determines the contribution to the loss rates from excited-state collisions. We find a substantial difference between the collisional loss rates for the two isotopes.

search into the genetics of Kentucky bluegrass can be difficult because of a complex genome that can affect Kentucky bluegrass (Poa pratensis L.) is an important cool-season many different variables. For instance, genome size has grass species in the turfgrass and forage industries. Understanding the genetics of Kentucky bluegrass is useful in developing improved adaptive significance and influences phenotype by the cultivars and hybrids. However, studying the genetics of Kentucky expression of its genic content and by the physical effects bluegrass can often be difficult because of the high variation in ploidy of its mass and/or volume (Bennett and Leitch, 1995). In level that results from its facultative apomictic reproductive nature.angiosperms, DNA amount has been shown to correlate Flow cytometry provides an easy and accurate method for assessing with a wide range of important characters such as minithis variation by quantifying DNA content. The purpose of our study mum generation time and ecological behavior. Large was to determine the level of variation in ploidy in Kentucky bluegrass variations in ploidy level exist within and between cultiby analyzing its DNA content using flow cytometry. In addition, DNA vars because of the facultative apomictic nature of recontent was compared with genetic similarity derived from DNA production in Kentucky bluegrass. Therefore, it is not marker data, and was also correlated with chromosome number. possible to assign a specific ploidy level to Kentucky Twenty-two cultivars of Kentucky bluegrass were selected for the study by considering the range of variability in morphological traits bluegrass cultivars. The production of reduced and unand genetic distance derived from DNA marker data. We found that reduced eggs accounts for the differences in chromothe DNA content of Kentucky bluegrass genotypes from the 22 cultisome number. Research has demonstrated that the chrovars ranged from 5.39 to 17.69 pg of DNA/2C and that a majority of mosome number in Kentucky bluegrass can vary from the genotypes had a DNA content value in the range of 7 to 13 pg. 28 to 140, which corresponds to euploid chromosome A significant correlation between DNA content and chromosome numbers with x ϭ 7 (Lö ve and Lö ve, 1975; Barcaccia number was detected. Euploid chromosome numbers (x ϭ 7) with a et al., 1997). range from the pentaploid (2n ϭ 5x ϭ 35) to the quindecaploid (2n ϭ The ability to quickly estimate DNA amount would 15x ϭ 105) were found along with aneuploid numbers. The results facilitate Kentucky bluegrass research by allowing the of this research could aid both breeders and researchers in studying inclusion or exclusion of DNA amount as a variable in the genetics of the species and in improving Kentucky bluegrass cultivars via intra-and interspecific hybridizations.

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We have demonstrated the transfer of 39 K and 40 K atoms from a magneto-optical funnel (a hollow pyramidal mirror) through a low (0:05 l/s) conductance hole and into a conventional magneto-optical trap (mot) 35 cm away, with an efficiency of approximately six percent. This simple scheme should be useful for experiments requiring high loading rates with minimal contamination from hot untrapped atoms.

We present observations of a spontaneous-force optical trap in which rubidium atoms are spin polarized by optical pumping. Stable trapping is achieved in two dimensions by the same force as in the Zeeman-shift optical trap, and in the third dimension by a macroscopic vortex force that is insensitive to light polarizations and magnetic fields. When the light along this third direction is circularly polarized and a parallel magnetic field is applied, the atoms become spin polarized.PACS numbers: 32.80. Pj, 32.80.Bx, 33.80.Ps The techniques of optical pumping have been used for many years to manipulate the internal (spin) degrees of freedom of atoms by controlled absorption and emission of polarized light. Recently, precise manipulation of the external (momentum, position) degrees of freedom of atoms has also become possible using laser cooling and trapping techniques. In this Letter, we describe our observations of an atomic vapor in which both external and internal degrees of freedom are simultaneously controlled: An optically pumped spontaneous-force atom trap. In addition to observing spin polarization of atoms in this trap, we find that, in contrast to conventional optically pumped vapors, small magnetic fields of a few gauss dramatically affect the optical pumping process. The use of appropriate polarizations and magnetic fields is necessary for efficient optical pumping of these samples.Optical pumping of atoms [1] is a tremendously useful technique for atomic spectroscopy. Lately, optical pumping with lasers has also been successful in producing dense spin-polarized vapors for applications such as spinpolarized targets for high-energy and nuclear physics [2], production of spin-polarized proton beams [3], and sensitive surface probes [4,5]. Independently, much progress has been made in optical cooling and trapping of atoms. Recent simplification of the apparatus required to load atoms into traps [6] and increased numbers of trapped atoms [7] make atom traps attractive for many applications. In particular, the robust Zeeman-shift optical trap (ZOT) [8] can trap over 10 10 unpolarized atoms at microkelvin temperatures in a vapor cell [7]. It is clear that many new experiments may be feasible with a trap of spin-polarized atoms.While the ZOT is efficient for trapping and cooling atoms, the atoms in such a trap experience light fields whose polarizations change over a X/2 spatial dimension, so while the atoms may be locally optically pumped, the ensemble is necessarily unpolarized. This difficulty in achieving a net spin polarization is overcome in the present work by using a vortex trap that allows considerable freedom in the choices of light polarization and magnetic field along one dimension. This allows us to spin polarize the sample as described below.The vortex trap uses the ZOT trapping mechanism along two directions and a vortex force along the third to achieve three-dimensional trapping [9]. The operation of this trap can be understood from Fig. 1. The laser beams are derived from a single laser tune...