Single Particle Tracking

The shedding of vortices and #ow interference between two circular cylinders in tandem and side-by-side arrangements are investigated numerically in this paper. A Fractional Step Method is used for the simulations and the #ow is assumed two-dimensional. The calculations are carried out on a three-noded unstructured mesh. The simulations are performed for a Reynolds number range varying from 100 to 200, and the #ow is solved through the "nite-element method. The mesh is "ner close to the cylinder wall in order to have a better description of the boundary layer. Vorticity contours of the #ow around the cylinders and force time histories are presented. The calculations are also compared to the experimental results obtained by Bearman & Wadcock in 1973 and Williamson in 1985. The numerical simulations, in this sense, complement their work with very detailed vorticity calculations and #ow visualizations. 2001 Academic Press.

Investigation of lipid lateral mobility in biological membranes and their artificial models provides information on membrane dynamics and structure; methods based on optical microscopy are very convenient for such investigations. We focus on fluorescence correlation spectroscopy (FCS), explain its principles and review its state of the art versions such as 2-focus, Z-scan or scanning FCS, which overcome most artefacts of standard FCS (especially those resulting from the need for an external calibration) making it a reliable and versatile method. FCS is also compared to single particle tracking and fluorescence photobleaching recovery and the applicability and the limitations of the methods are briefly reviewed. We discuss several key questions of lateral mobility investigation in planar lipid membranes, namely the influence which membrane and aqueous phase composition (ionic strength and sugar content), choice of a fluorescent tracer molecule, frictional coupling between the two membrane leaflets and between membrane and solid support (in the case of supported membranes) or presence of membrane inhomogeneities has on the lateral mobility of lipids. The recent FCS studies addressing those questions are reviewed and possible explanations of eventual discrepancies are mentioned.

Beam position monitors are required in all accelerators for the measurement and optimization of the beam parameters. Cavity beam position monitors (CBPM) offer the possibility of measurement of beam centroid positions at the nanometer scale. These devices can be and typically are used at electron accelerator facilities, both existing light sources and test facilities proposed for future linear colliders, such as the International Linear Collider (ILC) and Compact Linear Collider (CLIC). The requirements for the CLIC main linac are to measure the beam position using approximately 5000 beam position monitors (BPM) with 50 nm resolution, at every 50 ns. The high resolution, enormous scale of the system and the small bunch separation of 0.5 ns present many challenges and demand innovative approaches for the design and operation of the CBPM system. A cylindrical cavity BPM system has been designed in collaboration with the Diamond Light Source, in the C-Band frequency region. The design ideas, which will be beneficial to CLIC BPM and other designs, such as the deliberate separation of modes coupled to the x and y position measurements and the cavity operation without mechanical tuning are tested in the design. The major resonance modes of the cavity are simulated using Eigenmode simulation. The coupling and isolation characteristics are simulated using S-parameter simulations, while the beam coupling is studied through time domain simulations. Four cavities were fabricated according to the design discussed in this thesis. Their coupling and isolation were tested through S-parameter measurements. The dipole modes are separated by more than 5 MHz in frequency. The values of the quality factors were measured using the impedance method. The field orientation of the dipole and quadrupole modes were measured using the bead-pull perturbation technique and found to be rotated by 12 • and 3 • from

Research in the ecology of wetlands is quite established. However, research in the hydrology of wetlands is much less developed. In Flanders, Belgium, a research project was initiated to investigate ecohydrological differences in wetlands. Three wetlands (Doode Bemde, Vorsdonkbos, and Zwarte Beek Valley) have been examined in detail. As these wetlands are predominantly fed by discharging groundwater, the groundwater flow to the wetlands is here investigated by way of modelling and the results discussed. A supra-regional groundwater model was developed, as well as three regional groundwater models. Together with particle tracking models, these models reveal the flow system characteristics of the wetlands. The results indicate the dependence and vulnerability of the wetlands with respect to their recharge area. The results also form the basis for further hydrochemical analysis of the wetland groundwater system.

The EEE (Extreme Energy Event) Project will study extensive air showers through the detection of the muon component by means of a network of tracking detectors, installed inside high schools distributed all over Italy. Project's aim is to involve teachers and students in a frontier cosmic ray experiment, as well. The EEE telescope is based on a large but simplified and cheap version of the detector designed for the time of flight measurements (TOF) of the ALICE experiment at LHC: 3 large (~2 m 2 ) Multi-gap Resistive Plate Chambers (MRPC), built at CERN by high school students and teachers, which contribute directly to the full operation of the telescope. Using multiple small gas gaps combined with the use of high gain and fast gas mixture (Freon and SF6 based), the MRPCs show a time resolution of the order of 100 ps. Particle tracking is performed equipping MRPCs with 24 strips read, at both ends, by front-end electronics based on NINO ASIC and using commercial multi-hit TDCs. The two-dimensional information on the cosmic muon impact point is obtained by the hit strip, in one direction, and by the time difference of the signals arriving at the two strip ends in the other direction, thus providing space resolution of the order of 1 cm. By using the three impact points it is possible to reconstruct the direction of the crossing muon. The angular resolution obtained for the muon zenith angle is about 1°. The GPS synchronization of the telescopes will open the way to search for coincidences. The school involvement in the Project started around 2003 with 7 pilot towns. The project, supported by the Ministero dell'Università e della Ricerca (MIUR), Istituto Nazionale di Fisica Nucleare (INFN), European Organization for Nuclear Research (CERN), Consiglio Nazionale delle Ricerche (CNR) and Museo Storico della Fisica e Centro Studi e Ricerche "E. Fermi", has been conceived and lead by Prof. Antonino Zichichi.

We present the complete Lagrangian formulation of the Absolute Medium (AM) model. The AM Lagrangian L_AM is a scalar density that encodes the dynamics of two primary fields: the strain tensor ε_ij and the flow velocity u_i. It incorporates nonlinear elasticity with strain saturation, volumetric coupling, and causal propagation. The Lagrangian is variationally closed, meaning all evolution equations (the AM Master Equation) follow from Hamilton’s principle. We derive the Euler–Lagrange equations, discuss the role of dissipation and relaxation as effective terms arising from coarse-graining, and show how the Unity of Persistence (UP) selection rule remains separate. This document provides the canonical statement of
the AM Lagrangian.

A superconducting, combined-function, 5 T, 901, toroidal magnet with a large bore is described in this paper. This magnet is designed to be the last and most difficult part of a compact superconducting magnet-based carbon gantry optics for ion beam cancer therapy. The relatively small size of this toroidal magnet allows for a gantry the size of which is smaller or at least comparable to that of a proton gantry. The gantry design places the toroidal magnet between the scanning magnets and the patient, that is the scanning magnets are placed midway through the gantry. By optimizing the coil winding configuration of this magnet, near point-to-parallel optics is achieved between the scanning magnets and the patient; while at the same time there is only a small distortion of the beam-shape when scanning. We show that the origin of the beam-shape distortion is the strong sextupole components, whose effects are greatly pronounced when the beam is widely steered in the magnet. A method to correct such an undesirable effect is suggested and demonstrated by a numerical particle tracking through the calculated three-dimensional magnetic field.

We present a four-pillar isotopic and geometric case that the supernova remnant Vela Jr. (G266.2-1.2, ~300 ly) produced a system-wide thermalized neutron flash within the Young Earth Chronology (YEC) post-Flood window. The primary evidence derives from the dissociation of ³⁶Cl and ²⁶Al in Martian meteorites Tissint and EETA 79001: ³⁶Cl exceeds the GCR expectation by 16.0σ and 11.8σ respectively while ²⁶Al remains within normal bounds, a pattern physically only explicable by a short-duration thermalized neutron flux (NIT-2 event). The Robbins crater database independently confirms that both meteorite source regions represent old, deeply buried highland terrain, ruling out extended GCR exposure as an alternative. A unified directional model shows that Earth, Moon, Mars, and the Sun share a single Vela sightline geometry consistent with one solar-system-wide impact event. The possibility of two temporally distinct NIT events (NIT-1: Flood 2463 BCE terrestrial; NIT-2: Vela post-Flood extraterrestrial) is examined and neither can presently be falsified by available data.

Daresbury Laboratory is currently building an Energy Recovery Linac Prototype (ERLP) that will serve as a research and development facility for the study of beam dynamics and accelerator technology important to the design and construction of the proposed 4th Generation Light Source (4GLS) project. Two major objectives of the ERLP are the demonstration of energy recovery and of energy recovery from a beam disrupted by an FEL interaction as supplied by an infrared oscillator system. In this paper we present start-to-end simulations of the ERLP including such an FEL interaction. The beam dynamics in the highbrightness injector, which consists of a DC photocathode gun and a superconducting booster, have been modelled using the particle tracking code ASTRA. After the booster the particles have been tracked with the code elegant. The 3D code GENESIS 1.3 was used to model the FEL interaction with the electron beam at 35 MeV. A brief summary of impedance and wakefield calculations for the whole machine is also given.

Daresbury Laboratory is currently building an Energy Recovery Linac Prototype (ERLP) that will serve as a research and development facility for the study of beam dynamics and accelerator technology important to the design and construction of the proposed 4th Generation Light Source (4GLS) project. Two major objectives of the ERLP are the demonstration of energy recovery and of energy recovery from a beam disrupted by an FEL interaction as supplied by an infrared oscillator system. In this paper we present start-to-end simulations of the ERLP including such an FEL interaction. The beam dynamics in the highbrightness injector, which consists of a DC photocathode gun and a superconducting booster, have been modelled using the particle tracking code ASTRA. After the booster the particles have been tracked with the code elegant. The 3D code GENESIS 1.3 was used to model the FEL interaction with the electron beam at 35 MeV. A brief summary of impedance and wakefield calculations for the whole machine is also given.

MARYLIE/IMPACT (ML/I) is a hybrid code that combines the beam optics capabilities of MARYLIE with the parallel Particle-In-Cell capabilities of IMPACT. In addition to combining the capabilities of these codes, ML/I has a number of powerful features, including a choice of Poisson solvers, a fifth-order rf cavity model, multiple reference particles for rf cavities, a library of soft-edge magnet models, representation of magnet systems in terms of coil stacks with possibly overlapping fields, and wakefield effects. The code allows for map production, map analysis, particle tracking, and 3D envelope tracking, all within a single, coherent user environment. ML/I has a front end that can read both MARYLIE input and MAD lattice descriptions. The code can model beams with or without acceleration, and with or without space charge. Developed under a US DOE Scientific Discovery through Advanced Computing (SciDAC) project, ML/I is well suited to largescale modeling, simulations having been performed with up to 100M macroparticles. The code inherits the powerful fitting and optimizing capabilities of MARYLIE augmented for the new features of ML/I. The combination of soft-edge magnet models, high-order capability, space charge effects, and fitting/optimization capabilities, make ML/I a powerful code for a wide range of beam optics design problems. This paper provides a description of the code and its unique capabilities.

Wide-field microscopy with a double-helix point spread function (DH-PSF) provides three-dimensional (3D) position information beyond the optical diffraction limit. We compare the theoretical localization precision for an unbiased estimator of the DH-PSF to that for 3D localization by astigmatic and biplane imaging using Fisher information analysis including pixelation and varying levels of background. The DH-PSF results in almost constant localization precision in all three dimensions for a 2 μm thick depth of field while astigmatism and biplane improve the axial localization precision over smaller axial ranges. For high signal-to-background ratio, the DH-PSF on average achieves better localization precision.

The characteristics of the CR-39 nuclear track detectors have been studied using the techniques of chemical etching and electrochemical etching. While electrochemical etching can be used to enlarge the track-pits for simplifying the counting procedure, it would only yield a maximum registration efficiency for alpha particle tracks up to approximately 3 MeV. The range of energy for which the registration efficiency is a maximum in the case of chemical etching is up to about 4.5 MeV alphas. The optimum etching condition for alpha tracks can be chosen at any point on the plateau extending from a thickness of 2.2 μm to about 9 μm of the layer removed from the surface of the detectors. The detectors have been applied to measurements of radon in soil air and indoor atmosphere. The result suggests that the CR-39 detectors etched chemically would have sufficient sensitivity for the survey of airborne alpha particles.
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https://www.sciencedirect.com/science/article/abs/pii/0167508783903976

A digital longitudinal damper is being developed in SRRC to stabilize the longitudinal coupled-bunch instabilities observed in the TLS storage ring. It is a bunch by bunch feedback system designed for 200 bunches at 2 ns bunch interval. Designs of the bunch phase detection circuit, the digital electronics and the 1125 MHz wideband RF system for correction of phase errors are presented in this article. The core of the digital electronics is a DSP array that utilizes commercially available DSP modules performing parallel processing at a data throughput of 500 Mbytes/sec. This will greatly reduce the time required for both hardware and software developments. A prototype operating at one eighth of the data rate of the final system is under construction to evaluate the system design.

The distribution of the leptocephalus larvae of European (Anguilla anguilla) and American (Anguilla rostrata) eels collected during recent Sargasso Sea surveys was used to model larval drift. The drift trajectories of individual larva were back-calculated to the estimated time of spawning, using current data from two global oceanographic assimilation models. The results of both models give the same overall result; widespread spawning extended in time from December to March. The drift was also calculated forwards for approximately 1 year. The forward drift modelling showed that most leptocephali remained in the area south of the Subtropical Frontal Zone. One conclusion is that the majority of leptocephali remain trapped and possibly die in the retention area. A small proportion of leptocephali are entrained into the Gulf Stream system. An implication is that the spawning success may be highly sensitive to oceanographic and climatic factors that alter the dispersion of leptocephali ou...

In this paper, starting from the basic description of the equation that governs the bunch motion and looking at the advances of the technology, three examples of feedback designs versus technology trend are presented and discussed. In particular the author compares three digital systems implemented or proposed for DAFNE and other e+/e- accelerators. Descriptions of some relevant features are also done. Conclusions on the digital feedback design trend are reported.