An intense, slow and cold beam of metastable Ne(3s) ^3P_2 atoms

We employ laser cooling to intensify and cool an atomic beam of metastable Ne(3s) atoms. Using several collimators, a slower and a compressor we achieve a ^{20}Ne^* flux of 6 10^{10} atoms/s in an 0.7 mm diameter beam traveling at 100 m/s, and having longitudinal and transverse temperatures of 25mK and 300microK, respectively. This constitutes the highest flux in a concentrated beam achieved to date with metastable rare gas atoms. We characterize the action of the various cooling stages in terms of their influence on the flux, diameter and divergence of the atomic beam. The brightness and brilliance achieved are 2.1 10^{21} s^{-1} m^{-2} sr^{-1} and 5.0 10^{22} s^{-1} m^{-2} sr^{-1}, respectively, comparable to the highest values reported for alkali-metal beams. Bright beams of the ^{21}Ne and ^{22}Ne isotopes have also been created.Comment: 18 pages, 9 figures, RevTe

Long-range diatomic s + p potentials of heavy rare gases

We examine the long-range part of the rare-gas diatomic potentials that connect to the R͕(nϪ1)p 5 ns͖ ϩR͕(nϪ1)p 5 np͖ atomic states in the separated atom limit ͑nϭ3, 4, 5, and 6 for Ne, Ar, Kr, and Xe, respectively͒. We obtain our potentials by diagonalization of a Hamiltonian matrix containing the atomic energies and the electric dipole-dipole interaction, with experimentally determined parameters ͑atomic energies, lifetimes, transition wavelengths, and branching ratios͒ as input. Our numerical studies focus on Ne and Kr in this paper, but apply in principle to all other rare gases lacking hyperfine structure. These diatomic potentials are essential for applications in which homonuclear rare-gas pairs interact at large internuclear separations, greater than about 20 Bohr radii. Among such applications are the study of cold atomic collisions and photoassociative spectroscopy

Metastable neon collisions: anisotropy and scattering length

In this paper we investigate the effective scattering length $a$ of spin-polarized Ne*. Due to its anisotropic electrostatic interaction, its scattering length is determined by five interaction potentials instead of one, even in the spin-polarized case, a unique property among the Bose condensed species and candidates. Because the interaction potentials of Ne* are not known accurately enough to predict the value of the scattering length, we investigate the behavior of $a$ as a function of the five phase integrals corresponding to the five interaction potentials. We find that the scattering length has five resonances instead of only one and cannot be described by a simple gas-kinetic approach or the DIS approximation. However, the probability for finding a positive or large value of the scattering length is not enhanced compared to the single potential case. The complex behavior of $a$ is studied by comparing a quantum mechanical five-channel numerical calculation to simpler two-channel models. We find that the induced dipole-dipole interaction is responsible for coupling between the different |\Omega> states, resulting in an inhomogeneous shift of the resonance positions and widths in the quantum mechanical calculation as compared to the DIS approach. The dependence of the resonance positions and widths on the input potentials turns out to be rather straightforward. The existence of two bosonic isotopes of Ne* enables us to choose the isotope with the most favorable scattering length for efficient evaporative cooling towards the Bose-Einstein Condensation transition, greatly enhancing the feasibility to reach this transition.Comment: 13pages, 8 eps figures, analytical model in section V has been remove

Cold and trapped metastable noble gases

We review experimental and theoretical work on cold, trapped metastable noble gases. We em- phasize the aspects which distinguish work with these atoms from the large body of work on cold, trapped atoms in general. These aspects include detection techniques and collision processes unique to metastable atoms. We describe several experiments exploiting these unique features in fields including atom optics and statistical physics. We also discuss precision measurements on these atoms including fine structure splittings, isotope shifts, and atomic lifetimes

Lower limb strength training in children with cerebral palsy – a randomized controlled trial protocol for functional strength training based on progressive resistance exercise principles

<p>Abstract</p> <p>Background</p> <p>Until recently, strength training in children with cerebral palsy (CP) was considered to be inappropriate, because it could lead to increased spasticity or abnormal movement patterns. However, the results of recent studies suggest that progressive strength training can lead to increased strength and improved function, but low methodological quality and incomplete reporting on the training protocols hampers adequate interpretation of the results. This paper describes the design and training protocol of a randomized controlled trial to assess the effects of a school-based progressive functional strength training program for children with CP.</p> <p>Methods/Results</p> <p>Fifty-one children with Gross Motor Function Classification Systems levels I to III, aged of 6 to 13 years, were recruited. Using stratified randomization, each child was assigned to an intervention group (strength training) or a control group (usual care). The strength training was given in groups of 4–5 children, 3 times a week, for a period of 12 weeks. Each training session focussed on four exercises out of a 5-exercise circuit. The training load was gradually increased based on the child's maximum level of strength, as determined by the 8 Repetition Maximum (8 RM). To evaluate the effectiveness of the training, all children were evaluated before, during, directly after, and 6 weeks after the intervention period. Primary outcomes in this study were gross motor function (measured with the Gross Motor Function Measure and functional muscle strength tests) and walking ability (measured with the 10-meter, the 1-minute and the timed stair test). Secondary outcomes were lower limb muscle strength (measured with a 6 RM test, isometric strength tests, and a sprint capacity test), mobility (measured with a mobility questionnaire), and sport activities (measured with the Children's Assessment of Participation and Enjoyment). Spasticity and range of motion were assessed to evaluate any adverse events.</p> <p>Conclusion</p> <p>Randomized clinical trials are considered to present the highest level of evidence. Nevertheless, it is of utmost importance to report on the design, the applied evaluation methods, and all elements of the intervention, to ensure adequate interpretation of the results and to facilitate implementation of the intervention in clinical practice if the results are positive.</p> <p>Trial Registration</p> <p>Trial Register NTR1403</p

Measurement of the photoionization cross section of the (2p)5 (3p)3 D3 state of neon

We report a new measurement of the photoionization cross section for the 2p 5 3p 3D3 state of neon at the wavelengths of 351 and 364nm. These data were obtained by monitoring the decay of the fluorescence of atoms trapped in a magneto-optical atom trap under the presence of a photoionizing laser, a technique developed by Dinneen et al. [Opt. Lett. 17, 1706 (1992)]. We obtain absolute photoionization cross sections of [data omitted], an improvement in accuracy of a factor of 4 over previously published values. These new values are not consistent with published theoretical data

Properties of Cold Collisions of

We have determined properties of cold 39 K + 39 K and 41 K + 41 K collisions by a multichannel Inverted Perturbation Approach applied to spectroscopic data of highly-excited 39 K singlet and triplet bound states. We predict positive scattering lengths for the 39 K + 39 K and 41 K + 41 K singlet potentials, as well as for the 41 K + 41 K triplet potential, and a negative value for 39 K + 39 K triplet scattering. From a study of the magnetic field dependence we conclude that 41 K may be the first example of an alkali species with a Feshbach resonance in the magnetic field range where these atoms can be trapped in the f = 1; m f = \Gamma1 hyperfine state, thus providing a possibility to switch between stable and instable condensates in a Bose-Einstein condensation experiment. Typeset using REVT E X The recent observation of Bose Einstein condensation (BEC) in weakly-interacting atomic gases of rubidium [1], lithium [2] and sodium [3] is an important step tow..