[en] At the site of British Nuclear Fuels plc in Sellafield, Cumbria, reprocessing of nuclear fuel results in the emission of ¹²⁹I to the atmosphere. Doses to the critical group of people living close to the site an consuming locally produced food are assessed, using simple compartment equilibrium models, and compared with recommended dose limits for members of the public. 7 refs, 1 tab

[en] Discharges of radionuclides from Sellafield affect a number of different 'critical groups' in the local population. For discharges to sea, high rate consumers of seafood have been the limiting group. Reduction in discharges and recent revisions in metabolic parameters have reduced the committed effective dose equivalent incurred by this group to about 150 μSv.y^-1. For discharges to atmosphere, the critical group has been assumed to consist of people living close to the site and obtaining essentially all their food supplies from the same locality. On this basis the group would incur a committed effective dose equivalent of about 110 μSv.y^-1. A specific local habit survey has permitted the calculation of a dose contribution for this group, which shows that the 110 μSv.y^-1 value is conservative. (author)

[en] In this paper we examine some properties of the thermoluminescence (TL) emission from LiF doped with Mg, Cu and P. Pulse thermal annealing of diffuse reflectance spectra from irradiated powders suggests that the TL signals from this material are caused by similar defects to those responsible for emission in TLD-100. From a study of the variation in the TL output as a function of different impurity concentrations we determine that the height of the main TL peak (peak 4) is a maximum and the residual level (expressed as the ratio of peaks 5 and 4) is a minimum for Mg = 0.2 M%, Cu²⁺ = 0.002 M% or Cu⁺ = 0.004 M%, and P = 5 M%. Finally, glow curve deconvolution suggests that the high activation energies in these materials may be caused by multiphonon charge capture processes leading to a thermally activated capture cross-section. (Author)

[en] The ORNL superconducting motor, is a device consisting of 4 DC superconducting magnets in a square cross section. These coils are arranged in a N-S-N-S configuration and at present have no iron flux return paths. Experimentally the device has been operated and has been shown to produce 102.3 kg-m of locked rotor torque at 100 Ampers winding current. The superconductors were operating at 40 Kelvin. The peak magnetic field at 2,100 amperes operating current was 2 Tesla on the cryostat face. Recently there has been an effort under way to improve the operating parameters of the device by improving the flux utilization of the device. This was to be accomplished by the use of flux focusing pole pieces. The effects of the pole pieces and the vacuum magnetic field have been modeled with the MSC EMAS code to see the possible benefit of adding pole pieces to the in situ experiment

[en] The number of atoms trapped within the mode of an optical cavity is determined in real time by monitoring the transmission of a weak probe beam. Continuous observation of atom number is accomplished in the strong coupling regime of cavity quantum electrodynamics and functions in concert with a cooling scheme for radial atomic motion. The probe transmission exhibits sudden steps from one plateau to the next in response to the time evolution of the intracavity atom number, from N≥3 to N=2→1→0 atoms, with some trapping events lasting over 1 s

[en] Our recent paper reports the experimental realization of a one-atom laser in a regime of strong coupling [J. McKeever, A. Boca, A. D. Boozer, J. R. Buck, and H. J. Kimble, Nature (London) 425, 268 (2003)]. Here we provide the supporting theoretical analysis relevant to the operating regime of our experiment. By way of a simplified four-state model, we investigate the passage from the domain of conventional laser theory into the regime of strong coupling for a single intracavity atom pumped by coherent external fields. The four-state model is also employed to exhibit the vacuum-Rabi splitting and to calculate the optical spectrum. We next extend this model to incorporate the relevant Zeeman hyperfine states as well as a simple description of the pumping processes in the presence of polarization gradients and atomic motion. This extended model is employed to make quantitative comparisons with our earlier measurements for the intracavity photon number versus pump strength and for the photon statistics as expressed by the intensity correlation function g⁽²⁾(τ)

[en] Recent experimental advances in the field of cavity quantum electrodynamics (QED) have opened new possibilities for control of atom-photon interactions. A laser with 'one and the same atom' demonstrates the theory of laser operation pressed to its conceptual limit. The generation of single photons on demand and the realization of cavity QED with well defined atomic numbers N = 0, 1, 2,... both represent important steps toward realizing diverse protocols in quantum information science. Coherent manipulation of the atomic state via Raman transitions provides a new tool in cavity QED for in situ monitoring and control of the atom-cavity system. All of these achievements share a common point of departure: the regime of strong coupling. It is thus interesting to consider briefly the history of the strong coupling criterion in cavity QED and to trace out the path that research has taken in the pursuit of this goal

[en] Single cesium atoms are cooled and trapped inside a small optical cavity by way of a novel far-off-resonance dipole-force trap, with observed lifetimes of 2-3 s. Trapped atoms are observed continuously via transmission of a strongly coupled probe beam, with individual events lasting ≅1 s. The loss of successive atoms from the trap N≥3→2→1→0 is thereby monitored in real time. Trapping, cooling, and interactions with strong coupling are enabled by the trap potential, for which the center-of-mass motion is only weakly dependent on the atom's internal state

[en] The transmission spectrum for one atom strongly coupled to the field of a high finesse optical resonator is observed to exhibit a clearly resolved vacuum Rabi splitting characteristic of the normal modes in the eigenvalue spectrum of the atom-cavity system. A new Raman scheme for cooling atomic motion along the cavity axis enables a complete spectrum to be recorded for an individual atom trapped within the cavity mode, in contrast to all previous measurements in cavity QED that have required averaging over 10³-10⁵ atoms

[en] We investigate the low-lying compression modes of a unitary Fermi gas with imbalanced spin populations. For low polarization, the strong coupling between the two spin components leads to a hydrodynamic behavior of the cloud. For large population imbalance we observe a decoupling of the oscillations of the two spin components, giving access to the effective mass of the Fermi polaron, a quasiparticle composed of an impurity dressed by particle-hole pair excitations in a surrounding Fermi sea. We find m*/m=1.17(10), in agreement with the most recent theoretical predictions.