Particle parameter analyzing system

An X-Y plotter circuit apparatus is described which displays an input pulse representing particle parameter information, that would ordinarily appear on the screen of an oscilloscope as a rectangular pulse, as a single dot positioned on the screen where the upper right hand corner of the input pulse would have appeared. If another event occurs, and it is desired to display this event, the apparatus is provided to replace the dot with a short horizontal line

The SiRi Particle-Telescope System

A silicon particle-telescope system for light-ion nuclear reactions is described. In particular, the system is designed to be optimized for level density and gamma-ray strength function measurements with the so-called Oslo method. Eight trapezoidal modules are mounted at 5 cm distance from the target, covering 8 forward angles between theta = 40 and 54 degrees. The thin front dE detectors (130 micrometer) are segmented into eight pads, determining the reaction angle for the outgoing charged ejectile. Guard rings on the thick back E detectors (1550 micrometer) guarantee low leakage current at high depletion voltage.Comment: 6 pages, 8 figure

GPU-Enabled Particle-Particle Particle-Tree Scheme for Simulating Dense Stellar Cluster System

We describe the implementation and performance of the ${\rm P^3T}$ (Particle-Particle Particle-Tree) scheme for simulating dense stellar systems. In ${\rm P^3T}$, the force experienced by a particle is split into short-range and long-range contributions. Short-range forces are evaluated by direct summation and integrated with the fourth order Hermite predictor-corrector method with the block timesteps. For long-range forces, we use a combination of the Barnes-Hut tree code and the leapfrog integrator. The tree part of our simulation environment is accelerated using graphical processing units (GPU), whereas the direct summation is carried out on the host CPU. Our code gives excellent performance and accuracy for star cluster simulations with a large number of particles even when the core size of the star cluster is small

Two-Particle Circular Billiards Versus Randomly Perturbed One-Particle Circular Billiards

We study a two-particle circular billiard containing two finite-size circular particles that collide elastically with the billiard boundary and with each other. Such a two-particle circular billiard provides a clean example of an "intermittent" system. This billiard system behaves chaotically, but the time scale on which chaos manifests can become arbitrarily long as the sizes of the confined particles become smaller. The finite-time dynamics of this system depends on the relative frequencies of (chaotic) particle-particle collisions versus (integrable) particle-boundary collisions, and investigating these dynamics is computationally intensive because of the long time scales involved. To help improve understanding of such two-particle dynamics, we compare the results of diagnostics used to measure chaotic dynamics for a two-particle circular billiard with those computed for two types of one-particle circular billiards in which a confined particle undergoes random perturbations. Importantly, such one-particle approximations are much less computationally demanding than the original two-particle system, and we expect them to yield reasonable estimates of the extent of chaotic behavior in the two-particle system when the sizes of confined particles are small. Our computations of recurrence-rate coefficients, finite-time Lyapunov exponents, and autocorrelation coefficients support this hypothesis and suggest that studying randomly perturbed one-particle billiards has the potential to yield insights into the aggregate properties of two-particle billiards, which are difficult to investigate directly without enormous computation times (especially when the sizes of the confined particles are small).Comment: 9 pages, 7 figures (some with multiple parts); published in Chao

Magnetic particle clutch controls servo system

Magnetic clutches provide alternative means of driving low-power rate or positioning servo systems. They may be used over wide variety of input speed ranges and weigh comparatively little. Power drain is good with overall motor/clutch efficiency greater than 50 percent, and gain of clutch is close to linear, following hysteresis curve of core and rotor material

A MEMS electrostatic particle transportation system

We demonstrate here an electrostatic MEMS system capable of transporting particles 5-10μm in diameter in air. This system consists of 3-phase electrode arrays covered by insulators (Figs. 1, 2). Extensive testing of this system has been done using a variety of insulation materials (silicon nitride, photoresist, and Teflon), thickness (0- 12μm), particle sizes (1-10μm), particle materials (metal, glass, polystyrene, spores, etc), waveforms, frequencies, and voltages. Although previous literature [1-2] claimed it impractical to electrostatically transport particles with sizes 5-10μm due to complex surface forces, this effort actually shows it feasible (as high as 90% efficiency) with the optimal combination of insulation thickness, electrode geometry, and insulation material. Moreover, we suggest a qualitative theory for our particle transportation system which is consistent with our data and finite-element electrostatic simulations

Propagation of chaos for the thermostatted Kac master equation

The Kac model is a simplified model of an $N$-particle system in which the collisions of a real particle system are modeled by random jumps of pairs of particle velocities. Kac proved propagation of chaos for this model, and hence provided a rigorous validation of the corresponding Boltzmann equation. Starting with the same model we consider an $N$-particle system in which the particles are accelerated between the jumps by a constant uniform force field which conserves the total energy of the system. We show propagation of chaos for this model

Particle parameter selection system for an electrostatic particle accelerator

Particle selection system for electrostatic accelerator for hypervelocity impact testin