Convection-Dominated Accretion Flows with Radiative Cooling

By numerically solving the set of basic equations describing black hole accretion flows with low accretion rates, we show that although the dynamical structure of these flows is essentially unaffected by radiative processes in comparison with the case in which the radiation is not considered, the radiative cooling can be more important than the advective cooling in the flow＇s convection-dominated zone, and this result may have implications to distinguish observationally convection-dominated accretion flows from advection-dominated accretion flows.     

Thermodynamic design data for absorption heat pump systems operating on ammonia-water—Part I. Cooling

The free choice of operating temperature in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy based coefficients of performance have been presented for ammonia—water absorption systems for cooling. The interaction of operating temperatures have been illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on ammonia-sodium thiocyanate—I. Cooling

The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy based coefficients of performance have been presented for ammonia-sodium thiocyanate absorption systems for cooling. The interaction of operating temperatures has been illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on water-lithium chloride—Part one. Cooling

The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. For a given combination of temperatures, the concentrations in the absorber and the generator are fixed automatically. This determines the flow ratio. Therefore for any particular working pair, the coefficient of performance is related to the flow ratio.Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalphy based coefficients of performance have been presented for a water-lithium chloride absorption system for cooling. The interaction of operating temperatures has been illustrated graphically. The data obtained are also compared with published data for the water-lithium bromide absorption system under identical conditions.     

Thermodynamic design data for absorption heat pump systems operating on water-lithium iodide—part I. Cooling

The operating temperatures in the absorption heat pump system fix the absorber and the generator concentration for a given working pair. Derived thermodynamic design data, including Carnot coefficients of performance and enthalpy-based coefficients of performance, with and without an economizer heat exchanger for possible combinations of operating temperatures, are presented for water-lithium iodide absorption systems for cooling. The effects of operating temperatures as well as economizer heat exchanger on the performance of an absorption cooler are illustrated graphically.     

An Enriched ^40K Source for Atomic Cooling

We have developed an enriched ⁴⁰K source used in ⁴⁰K--⁸⁷Rb atomic mixture cooling experiment. The enriched ⁴⁰K source is a home-made dispenser which releases ⁴⁰K atoms by the redox reaction between ⁴⁰K enriched KCl and calcium. It is efficient and easy to be made and used. We collect 10⁷ ～10^{8 40}K atoms in collection magneto-optical trap. With this dispenser, we perform a quantum degenerate Fermi gas experiment.     

Cooling induced by parametric resonance in a magnetic quadrupole trap

It is demonstrated experimentally that the anharmonic property of the quadrupole trap can be exploited to cool trapped atoms by modulating the trap potential anisotropically.This cooling effect arises from the energy-selective removal of the most energetic trapped atoms and the thermal equilibrium of the remaining atoms.The frequency dependences of the temperature and the fraction of the atoms left in the trap after the modulation are explored.It is also demonstrated that the cooling induced by parametric resonance can also increase the phase space density of the trapped atoms.     

Laser Cooling and Trapping of Sodium Atoms in Magneto-optical Trap

ＬａｓｅｒＣｏｏｌｉｎｇａｎｄＴｒａｐｐｉｎｇｏｆＳｏｄｉｕｍＡｔｏｍｓｉｎＭａｇｎｅｔｏ－ｏｐｔｉｃａｌＴｒａｐ￥ＬＩＵＸｕｎｍｉｎｇ；ＬＩＮＹｕｅｍｉｎｇ；ＺＨＯＵＳｈａｎｙｕ；ＨＵＯＹｕｎｓｈｅｎｇ；ＷＡＮＧＹｕｚｈｕ（Ｌａｂｏｒａｔｏｒｙｆｏ...     

Pd-Si Binary Bulk Metallic Glass Prepared at Low Cooling Rate

We report that binary bulk metallic glasses can be made up to 6ram in diameter in a Pd Si ahoy system by air cooling at slow cooling rate (about 8 K/s). The high stability of the undercooled liquid and the large glass-forming ability (GFA) of the binary alloy are contributed to the removing of heterogeneous impurities in the alloy melt by employing the fluxing technique. It has been found that decreasing cooling rate can increase the supercooled liquid region and thermal stability of the glassy alloy. After fluxing, a wider supercooled liquid region (△T = 58 K) and higher glass-forming ability have been obtained in a Pd81Si19 binary glassy alloy prepared by slow cooling rate.     

Cooling by Coulomb Heat Drag Based on Three Coupled Quantum Dots

We establish a model for a four-terminal thermoelectric system, based on three coupled quantum dots, which consists of a left/right electron reservoir(the source and the drain), two thermal reservoirs and three coupled quantum dots. Based on the master equation theory, we derive the expressions of the electron current and heat flow among the three quantum dots and the corresponding reservoir. We show that the source can be cooled by passing a thermal current between the two thermal reservoirs, w...     

Control Method of Cooling a Charged Particle Pair in a Paul Trap

We propose a simple feedback cooling method, including both the component feedback and the velocity feedback,for cooling a charged particle pair in a Paul trap. It is found that the system can be cooled to periodic orbits;and if control intensity is strong, the system can be cooled to a one-periodic orbit, which is only in a horizontalplane. The result shows that the cooled system is also robust for noise.     

Cooling of multilevel atoms below the one-photon recoil limit by Raman π-pulses

Analysis of optical excitation of a double Λ system with three lower and two excited states (so-called M atom) by the field of four travelling optical waves is carried out. It is shown that excitation of such a system by Raman π pulses can be used for deep cooling of M atoms to a temperature much lower than the temperature controlled by the recoil energy. The application of the proposed scheme considerably simplifies practical implementation of deep Raman cooling, which considerably extends the range of application of this technique.     

Cooling of SU(3) lattice gauge field configurations and the η' mass

A method is proposed to calculate the topological susceptibility in SU(3) lattice gauge theory by measuring the asymptotic action of cooled configurations for an ensemble of configurations. The results of a pilot study are presenred.     

Molecular Dynamics Simulation of Microstructure Transitions in a Large-Scale Liquid Metal Al System During Rapid Cooling Processes

We perform a molecular dynamics simulation of microstructure transitions in a large-scale system consisting of 400000 atoms of liquid metal Al by the Clare supercomputer.A cluster-type index method is proposed to describe the structures of various short-range-order clusters in the liquid system.It is demonstrated that the icosahedron cluster (12 0 12 0) plays the most important role in the microstructure transition and that some larger clusters (containing more than 130 atoms) are formed in the system during the rapid cooling processes.It is obvious that the larger clusters are formed by means of combining some middle clusters,and that the middle clusters are formed with several smaller clusters.However,the larger clustens are not formed to be the multi-shell configuration as shown in the mass spectrum analysis of the cluster configurations of Al obtained by gaseous deposition,ionic spray methods and so on.This result can be used to explain the essential distinction between the cluster configurations of Al formed in two different ways.     

Production of ~(87)Rb Bose–Einstein Condensate with a Simple Evaporative Cooling Method

A Bose–Einstein condensate with a large atom number is an important experimental platform for quantum simulation and quantum information research. An optical dipole trap is the a conventional way to hold the ultracold atoms, where an atomic cloud is evaporatively cooled down before reaching the Bose–Einstein condensate. A carefully designed trap depth controlling curve is typically required to realize the optimal evaporation cooling.We present and demonstrate a simple way to optimize the evaporation cooling in a crossed optical dipole trap.A polyline shape optical power control profile is easily obtained with our method, by which a pure Bose–Einstein condensate with atom number 1.73 × 105 is produced. Theoretically, we numerically simulate the optimal evaporation cooling using the parameters of our apparatus based on a kinetic theory. Compared to the simulation results, our evaporation cooling shows a good performance. We believe that our simple method can be used to quickly realize evaporation cooling in optical dipole traps.     

Effect of Laser Cooling on Frequency Standard of Single Ca^＋ Ion Trapped in a Radio-Frequency Paul Trap

The source of systematic frequency shift of single-ion optical frequency standard of^40 Ca^＋ ion trapped in endcap trap and laser-cooled to a few of mK is analysed and calculated. Second-order Doppler shift, Stark shift due to micromotion and thermal motion, blackbody Stark shift and ac Stark shift are calculated for the ground state and excited 3d ^2D5/2 state. The Hertz-level measurement of the optical clock frequency in a single ^40Ca^＋ ion can be performed.     

Energy Levels and Transition Rates for Laser Cooling Os- and a General Approach to Produce Cold Atoms and Molecules

High-resolution photoelectron energy spectra of osmium anions are obtained using the slow-electron velocitymap imaging method.The energy levels of excited states ⁴F_7/2,⁴F_5/2and ⁴F_3/2of Os^- are determined to be 148.730(13),155.69(15),and 176.76(13) THz[or 4961.09(41),5193.4(49),and 5896.1(42) cm^-1],respectively.The lifetime of the opposite-parity excited state ⁶D^o_9/2 is determi...