New ion trap for atomic frequency standard applications

A novel linear ion trap that permits storage of a large number of ions with reduced susceptibility to the second-order Doppler effect caused by the radio frequency (RF) confining fields has been designed and built. This new trap should store about 20 times the number of ions a conventional RF trap stores with no corresponding increase in second-order Doppler shift from the confining field. In addition, the sensitivity of this shift to trapping parameters, i.e., RF voltage, RF frequency, and trap size, is greatly reduced

Atomic frequency standards for ultra-high-frequency stability

The general features of the Hg-199(+) trapped-ion frequency standard are outlined and compared to other atomic frequency standards, especially the hydrogen maser. The points discussed are those which make the trapped Hg-199(+) standard attractive: high line Q, reduced sensitivity to external magnetic fields, and simplicity of state selection, among others

The JPL trapped mercury ion frequency standard

In order to provide frequency standards for the Deep Space Network (DSN) which are more stable than present-day hydrogen masers, a research task was established under the Advanced Systems Program of the TDA to develop a Hg-199(+) trapped ion frequency standard. The first closed-loop operation of this kind is described. Mercury-199 ions are confined in an RF trap and are state-selected through the use of optical pumping with 194 nm UV light from a Hg-202 discharge lamp. Absorption of microwave radiation at the hyperfine frequency (40.5 GHz) is signaled by atomic fluorescence of the UV light. The frequency of a 40.5 GHz oscillator is locked to a 1.6 Hz wide atomic absorption line of the trapped ions. The measured Allan variance of this locked oscillator is currently gamma sub y (pi) = 4.4 x 10 to the minus 12th/square root of pi for 20 is less than pi is less than 320 seconds, which is better stability than the best commercial cesium standards by almost a factor of 2. This initial result was achieved without magnetic shielding and without regulation of ion number

Spinor Dynamics-Driven Formation of a Dual-Beam Atom Laser

We demonstrate a novel dual-beam atom laser formed by outcoupling oppositely polarized components of an F=1 spinor Bose-Einstein condensate whose Zeeman sublevel populations have been coherently evolved through spin dynamics. The condensate is formed through all-optical means using a single-beam running-wave dipole trap. We create a condensate in the field-insensitive $m_F=0$ state, and drive coherent spin-mixing evolution through adiabatic compression of the initially weak trap. Such dual beams, number-correlated through the angular momentum-conserving reaction $2m_0\leftrightharpoons m_{+1}+m_{-1}$, have been proposed as tools to explore entanglement and squeezing in Bose-Einstein condensates, and have potential use in precision phase measurements.Comment: 4 pages, 4 figure

A study of the influence of Hg(6(3)P2) population in a low-pressure discharge on mercury ion emission at 194.2 nm

A low-pressure mercury-argon discharge, similar to the type existing in the mercury lamp for the trapped-ion standard, is probed with a new technique of laser spectroscopy to determine the influence of the Hg(6 3P(sub 2)) population on discharge emission. The discharge is excited with inductively coupled rf power. Variations in the intensity of emission lines in the discharge were examined as lambda = 546.1 nm light from a continuous wave (CW) laser excited the Hg(6 3P(sub 2)) to (7 3S (sub 1)) transition. The spectrum of the discharge viewed in the region of laser irradiation showed increased emission in lambda = 546.1, 435.8, 404.7, 253.7, and 194.2 nm lines. Other lines in Hg I exhibited a decrease in emission. When the discharge was viewed outside the region of laser irradiation, all lines exhibited an increased emission. Based on these results, it is concluded that the dominant mechanism for the excitation of higher lying levels of mercury is the the electron-impact excitation via the 3P(sub 2) level. The depopulation of this metastable is also responsible for the observed increase in the electron temperature when the laser irradiates the discharge. It is also concluded that the 3P(sub 2) metastable level of mercury does not play a significant role in the excitation of the 3P(sub 1/2) level of mercury ion

Simple analytic potentials for linear ion traps

A simple analytical model was developed for the electric and ponderomotive (trapping) potentials in linear ion traps. This model was used to calculate the required voltage drive to a mercury trap, and the result compares well with experiments. The model gives a detailed picture of the geometric shape of the trapping potenital and allows an accurate calculation of the well depth. The simplicity of the model allowed an investigation of related, more exotic trap designs which may have advantages in light-collection efficiency

Computer simulations of ions in radio-frequency traps

The motion of ions in a trapped-ion frequency standard affects the stability of the standard. In order to study the motion and structures of large ion clouds in a radio-frequency (RF) trap, a computer simulation of the system that incorporates the effect of thermal excitation of the ions was developed. Results are presented from the simulation for cloud sizes up to 512 ions, emphasizing cloud structures in the low-temperature regime

Stripe formation in horizontally oscillating granular suspensions

We present the results of an experimental study of pattern formation in horizontally oscillating granular suspensions. Starting from a homogeneous state, the suspension turns into a striped pattern within a specific range of frequencies and amplitudes of oscillation. We observe an initial development of layered structures perpendicular to the vibration direction and a gradual coarsening of the stripes. However, both processes gradually slow down and eventually saturate. The probability distribution of the stripe width approaches a nonmonotonic steady-state form which can be approximated by a Poisson distribution. We observe similar structures in MD simulations of soft spherical particles coupled to the motion of the surrounding fluid.Comment: 7 pages, 8 figures, to appear in Europhys. Lett. (2014

An apparatus for the electrodynamic containment of charged macroparticles

The dynamic moition of the ions contained in the trapped (199)Hg+ frequency standard contributes to the stability of the standard. In order to study these dynamics, a macroscopic analog of the (199)Hg+ trap is constructed. Containment of micron-sized particles in this trap allows direct visual observation of the particles' motion. Influenced by the confining fields and their own Coulomb repulsion, the particles can form stable arrays

Comparison anti-giardia activity of Satureja hortensis alcoholic extract and metronidazole in vitro

Background and aims: Giardiasis is known as intestinal infection and created by the flagellate protozoan Giardia lamblia. Some studies showed that phenolic components, present in plant extracts and essential oils, have anti-Giardia activity. The current study was performed to compare anti-Giardia activity of Satureja hortensis (SH) alcoholic extract and metronidazole in vitro. Methods: In this Laboratory-experimental study, it was separated cysts from the feces by Bingham procedure with minor modification. The numbers of cysts were calculated with Hemusytumetr and the purified cysts of Giardia lamblia (500 µl) were exposed with 500 µl of extract at concentrations of 10, 100 and 200 mg/ml and 125 mg/kg of metronidazole for 30, 60 and 120 min. The numbers of dead and live cysts was enumerated with a microscope. Results: Findings in the currnt studyshowed an increase in anti-Giardia activity of extract at high concentrations with increasing time. SH, at 100 mg/ml killed 53 in 30 min, 68 in 60 min and 78 in 120 min. Also, the extract killed by 62 in 30 min, about 88 in 60 minutes and 92 in 120 minutes. The drug had similar effects in 60 and 120 minutes, but it killed 83 in 30 minutes. Conclusion: SH alcoholic extract showed anti-Giardia activity at high rates and more time. Thus, SH extract at 200 mg may be suitable alternative for Metronidazole, without side effects. However, anti-Giardia activity of SH needs to more attentions, especially clinical investigations