Multi-particle Tracking Research Articles

Change of beam distribution due to decoherence in the presence of transverse feedback

The effect of Landau damping is often calculated based on a Gaussian beam distribution in all degrees of freedom. The stability of the beam is however strongly dependent on the details of the distribution. The present study focuses on the change of bunch distributions caused by the decoherence of the excitation driven by an external source of noise, in the presence of both amplitude detuning and a transverse feedback. Both multiparticle tracking simulations and theoretical models show a similar change of the distribution. The possible loss of Landau damping driven by this change is discussed.

Performance Simulation for a Prototype 1.5 GHz Superconducting Harmonic Cavity

Superconducting radio frequency cavities are used as main accelerating cavities and harmonic cavities in modern light sources. The addition of a harmonic cavity provides the possibility to increase the electron bunch length and therefore to improve the beam life time. The effects on instabilities and the bunch lengthening factor by harmonic cavities can be obtained from theoretical calculations. However, these calculations ignore phase transient effects and may overestimate the desired performance of the harmonic cavities. A multibunch multiparticle tracking method was developed to simulate the performance of harmonic cavities for non-uniform filling patterns, which take into account phase transient effects. Performance simulations using this tracking method for a prototype 1.5-GHz superconducting harmonic cavity for the Taiwan photon source are presented here.

Measurements of Particle-Surface Interactions in Both Equilibrium and Nonequilibrium Systems.

Total internal reflection microscopy (TIRM) is a passive technique that measures colloidal interactions in aqueous solution. A traditional Boltzmann method requires that particles must fluctuate around equilibrium positions for a long time. A method based on multiparticle tracking and drift velocity method was developed to measure interactions in both equilibrium and nonequilibrium systems. This method relaxed the limitation of the traditional Boltzmann method and do not require any external force like optical tweezer. Theoretical predictions of particle sedimentation under the influence of various forces were investigated to determine the proper particle size and solution properties. We found that the polystyrene (PS) particle with a size of 2.1 μm took the longest time to finish sedimentation, and 5% (w/w) sucrose was chosen to suppress the Brownian motion. For single and ensemble particles in equilibrium, the experimental diffusion coefficients and potential energy profiles were consistent with the theoretical prediction. In nonequilibrium experiments, the van der Waals force between the bare/hybrid particles and flat surface was measured, and the silica shell acted to strengthen the van der Waals attraction. This method extends the application of TIRM to nonequilibrium systems without any active control. Moreover, the silica-coated PS core-shell hybrid particles facilitate surface modification with a variety of active chemicals. It would be a great advantage to measure all kinds of long-range interactions between surface-modified particles and surface in aqueous solution with TIRM.

Effects of systematic octupole coupling resonances

The Xi’an proton accelerator facility synchrotron lattice has a systematic fourth-order resonance. The systematic octupole component in dipole magnets is found to have no adverse effect on the dynamic aperture in multiparticle tracking. The frequency map shows particles locked onto the \(2\nu _x-2\nu _z=0\) resonance. However, we will show that the instantaneous betatron tunes can vary widely around the resonance line for particles locked onto the resonance.

Diff_classifier: Parallelization of multi-particle tracking video analyses.

SummaryThe diff_classifier package seeks to address the issue of scale-up in multi-particle tracking (MPT) analyses via a parallelization approach. MPT is a powerful analytical tool that has been used in fields ranging from aeronautics to oceanography (Pulford, 2005) allowing researchers to collect spatial and velocity information of moving objects from video datasets. Examples include: Tracking tracers in ocean currents to study fluid flowTracking molecular motors (e.g., myosin, kinesin) to assess motile activityMeasuring intracellular trafficking by tracking membrane vesiclesAssessing microrheological properties by tracking nanoparticle movement.

Self-consistent calculation of transient beam loading in electron storage rings with passive harmonic cavities

The ongoing trend towards synchrotron light storage rings with ultralow emittance lattices leads to greater challenges to achieve beam stability, sufficient Touschek lifetime, low heating of machine components, and conservation of the emittance at high bunch charge. One solution to meet these challenges is to lengthen the electron bunches with harmonic cavities. Many upgrade proposals therefore include harmonic cavities to enhance the machine performance. This is also the case for the MAX IV 3 GeV storage ring, which employs passive third harmonic cavities to achieve up to five times bunch lengthening. Unfortunately, the performance of the harmonic cavities is reduced if a gap in the fill pattern is required. In this paper, the effect on synchronous phase and bunch length due to a gap in the fill pattern for rings with passive harmonic cavities is calculated in a self-consistent way including the bunch form factor. The aim is to achieve faster simulation of various schemes for compensating a gap compared to multiparticle tracking. A new semianalytical method based on an iterative matrix formulation is presented, as well as a single-particle tracking code including the bunch form factor. The results from these methods are compared to both results from a multiparticle tracking code and measurements at the MAX IV 3 GeV storage ring. The importance of including the bunch form factor in simulations is evaluated and discussed.

Beam parameters optimization and characterization for a TUrning LInac for Protontherapy

TULIP (TUrning LInac for Protontherapy) is a novel compact accelerator system for protontherapy mounted on a rotating gantry (Amaldi et al., 2013, 2010, 2009). Its high-energy Linac has the unique property of being able to modulate the beam energy from one pulse to the next, in only a couple of milliseconds. The main purpose of this study is to optimize the properties of the beam exiting the Linac to make them compatible to medical therapy and to characterize their medical physics properties for later implementation in a Treatment Planning System. For this purpose, multi-particle tracking and Monte Carlo (MC) simulations are used to follow the particles through their path up to the treatment isocenter, following the so-called phase-space method. The data compiled includes particle fluences in air and depth-dose curves and provides the basis for a specific model of the TULIP beam.

Formation of a uniform ion beam using octupole magnets for BioLEIR facility at CERN

The possibility to transform the Low Energy Ion Ring (LEIR) accelerator at CERN into a multidisciplinary, biomedical research facility (BioLEIR) was investigated based on a request from the biomedical community. BioLEIR aims to provide a unique facility with a range of fully stripped ion beams (e.g. He, Li, Be, B, C, N, O) and energies suitable for multidisciplinary biomedical, clinically-oriented research. Two horizontal and one vertical beam transport lines have been designed for transporting the extracted beam from LEIR to three experimental end-stations. The vertical beamline was designed for a maximum energy of 75 MeV/u, while the two horizontal beamlines shall deliver up to a maximum energy of 440 MeV/u. A pencil beam of 4.3 mm FWHM (Full Width Half Maximum) as well as a homogeneous broad beam of 40 × 40 mm2, with a beam homogeneity better than ±4%, are available at the first horizontal (H1) irradiation point, while only a pencil beam is available at the second horizontal (H2) and vertical (V) irradiation points. The H1 irradiation point shall be used to conduct systematic studies of the radiation effect from different ion species on cell-lines. The H1 beamline was designed to utilize two octupole magnets which transform the Gaussian beam distribution at the target location into an approximately uniformly distributed rectangular beam. In this paper, we report on the multi-particle tracking calculations performed using MAD-X software suite for the H1 beam optics to arrive at a homogeneous broad beam on target using nonlinear focusing techniques, and on those to create a Gaussian pencil beam on target by adjusting quadrupoles strengths and positions.

Structural, macro- and micro-mechanical properties of supramolecular bi-component l-Lysine-sodium tetraphenyl borate based hydrogels

We present a new system of bi-component hydrogels formed of l-lysine hydrochloride mixed with sodium tetraphenyl borate with unusual viscoelastic properties which might be useful in tissue engineering, nano-particles synthesis or bioseparation. Beside cationic-anionic molecular interactions, 1H-NMR experiments have also shown the presence of π-electrons cloud interactions as well as hydrogen bonds stabilizing the supramolecular structure. Bulk rheological and mechanical properties have been characterized using steady and oscillatory shear rheometry as well as uniaxial compression tests. Microstructural information has been deduced from multi particle tracking (MPT) optical microrheology and cryo-preparation scanning electron microscopy (SEM). These gels are shear thickening at low concentrations and shear thinning at higher gelator concentration. Shear and Young’s modulus data obtained from different techniques agree fairly well. Zero shear viscosity as well as modulus data obtained for gels with equimolar lysine and borate concentration exhibit concentration dependence η0∼c5±0.5and G0∼c3.4±0.35, respectively. The scaling exponent for η0agrees well with predictions for neutral polymer in theta solvent or wormlike micelles in the slow breaking regime whereas the variation in G0 is unexpectedly high. We attribute this to the unique microstructure consisting of a cellular structure composed of thin sheets connected by tiny fibers. At low concentrations the mesh size of this structure is about 10 μm and fiber diameter increases from ∼200 nm to ∼2 μm, only at the highest gelator concentration of 7 wt.% the mesh size shrinks to ∼5 μm and the fiber diameter to ∼400 nm. Consistently, tracer particles in low concentrated gels diffuse freely in an aqueous environment. At higher gelator concentration, however, gelation takes place so fast that tracers are trapped in the elastic sheets / fibrous regions and the modulus GMPT´ agrees fairly well with bulk data. Varying the molar ratio of both gel-forming components results in a pronounced viscosity maximum at fixed total gelator concentration. Corresponding microstructural changes could again be visualized using cryo-SEM consistent with MPT data. At high lysine fraction, a coarse coral reef type sheet structure is found while at low lysine to borate ratio a network of thick struts is formed. Finally, diffusing wave spectroscopy experiments performed on samples with different lysine to borate ratio revealed that the plateau modulus G0 is almost independent of temperature whereas the relaxation time TR becomes faster as temperature increases.

Symplectic multi-particle tracking on GPUs

A symplectic multi-particle tracking model is implemented on the Graphic Processing Units (GPUs) using the Compute Unified Device Architecture (CUDA) language. The symplectic tracking model can preserve phase space structure and reduce non-physical effects in long term simulation, which is important for beam property evaluation in particle accelerators. Though this model is computationally expensive, it is very suitable for parallelization and can be accelerated significantly by using GPUs. In this paper, we optimized the implementation of the symplectic tracking model on both single GPU and multiple GPUs. Using a single GPU processor, the code achieves a factor of 2–10 speedup for a range of problem sizes compared with the time on a single state-of-the-art Central Processing Unit (CPU) node with similar power consumption and semiconductor technology. It also shows good scalability on a multi-GPU cluster at Oak Ridge Leadership Computing Facility. In an application to beam dynamics simulation, the GPU implementation helps save more than a factor of two total computing time in comparison to the CPU implementation.

Electron cooling of a bunched ion beam in a storage ring

A combination of electron cooling and rf system is an effective method to compress the beam bunch length in storage rings. A simulation code based on multiparticle tracking was developed to calculate the bunched ion beam cooling process, in which the electron cooling, intrabeam scattering (IBS), ion beam space-charge field, transverse and synchrotron motion are considered. Meanwhile, bunched ion beam cooling experiments have been carried out in the main cooling storage ring (CSRm) of the Heavy Ion Research Facility in Lanzhou, to investigate the minimum bunch length obtained by the cooling method, and study the dependence of the minimum bunch length on beam and machine parameters. The experiments show comparable results to those from simulation. Based on these simulations and experiments, we established an analytical model to describe the limitation of the bunch length of the cooled ion beam. It is observed that the IBS effect is dominant for low intensity beams, and the space-charge effect is much more important for high intensity beams. Moreover, the particles will not be bunched for much higher intensity beam. The experimental results in CSRm show a good agreement with the analytical model in the IBS dominated regime. The simulation work offers us comparable results to those from the analytical model both in IBS dominated and space-charge dominated regimes.

Colloidal probe dynamics in gelatin solution during the sol-gel transition.

The dynamics of the colloidal probes in a gelatin solution during the time-dependent sol-gel transition was investigated by multi-particle tracking. The relationship between the relaxation of the medium at the critical gel point and the mean square displacement of the probes was elucidated. Based on this understanding, the critical gel point of gelatin and the corresponding critical exponent n were unambiguously determined by the loss angle criterion and the time-cure superposition. The shift factors of the latter are further used to estimate the time/length-scale evolution of the gelatin during the sol-gel transition. The growth of the medium length scale crossed with the two measuring length scales successively at the pre-gel regime. Coinciding with the length-scale crossovers, the probability density function (PDF) of the probe displacements displayed two transient peaks of non-Gaussianity. In the post-gel regime, the third peak of Gaussianity suggested inhomogeneity in the gel network. The non-Gaussianity results from the bifurcation of diffusivity. The present work showed that the non-Gaussian dynamics of the probes are not the direct equivalence of that of the medium, but an effect of length-scale coupling.

Abstract ID: 55 Beam characterization for the TULIP accelerator for protontherapy through full Monte Carlo simulations

TULIP, Turning LInac for Protontherapy, is a novel accelerator systems for protontherapy mounted on a rotating gantry designed by the TERA Foundation and CERN [1] , [2] . TULIP is natively designed with a 3D active scanning system that, besides the transverse scanning with fast magnets, features a fast beam energy variation from the linac to scan in the longitudinal direction in few ms. The main goal of this research is to characterize TULIP’s beams, through Full Monte Carlo (MC) simulations. The study combines the multi-particle tracking programs, RF Track [2] , Travel [3] , MADx-PTC [4] and the FLuka Monte-Carlo code [5] , [6] , enabling to follow each particle from the source through the linac, the beam transfer lines and the nozzle elements, until the isocenter such that transverse and longitudinal phase space characteristics are accounted for each particle. The particle fluence results in air at the isocenter and in upstream and downstream positions along the beam direction and the depth-dose curves are obtained and presented in a beamline model for a set of beam energy values and scanning magnet kick strengths. The results, suitable for characterizing in detail the beam spots for this particular accelerator system, can be used as input to generate a beam model in a commercial TPS and thus to allow the comparison with Fluka results in real patient case scenarios.

Simulation of longitudinal dynamics of laser-cooled and RF-bunched C3+ ion beams at heavy ion storage ring CSRe**Supported by National Natural Science Foundation of China (11405237, 11504388)

Laser cooling of Li-like C3+ and O4+ relativistic heavy ion beams is planned at the experimental Cooler Storage Ring (CSRe). Recently, a preparatory experiment to test important prerequisites for laser cooling of relativistic 12C3+ ion beams using a pulsed laser system has been performed at the CSRe. Unfortunately, the interaction between the ions and the pulsed laser cannot be detected. In order to study the laser cooling process and find the optimized parameters for future laser cooling experiments, a multi-particle tracking method has been developed to simulate the detailed longitudinal dynamics of laser-cooled ion beams at the CSRe. Simulations of laser cooling of the 12C3+ion beams by scanning the frequency of the RF-buncher or continuous wave (CW) laser wavelength have been performed. The simulation results indicate that ion beams with a large momentum spread could be laser-cooled by the combination of only one CW laser and the RF-buncher, and show the requirements of a successful laser cooling experiment. The optimized parameters for scanning the RF-buncher frequency or laser frequency have been obtained. Furthermore, the heating effects have been estimated for laser cooling at the CSRe. The Schottky noise spectra of longitudinally modulated and laser-cooled ion beams have been simulated to fully explain and anticipate the experimental results. The combination of Schottky spectra from the highly sensitive resonant Schottky pick-up and the simulation methods developed in this paper will be helpful to investigate the longitudinal dynamics of RF-bunched and ultra-cold ion beams in the upcoming laser cooling experiments at the CSRe.

UmUTracker: A versatile MATLAB program for automated particle tracking of 2D light microscopy or 3D digital holography data

We present a versatile and fast MATLAB program (UmUTracker) that automatically detects and tracks particles by analyzing video sequences acquired by either light microscopy or digital in-line holographic microscopy. Our program detects the 2D lateral positions of particles with an algorithm based on the isosceles triangle transform, and reconstructs their 3D axial positions by a fast implementation of the Rayleigh–Sommerfeld model using a radial intensity profile. To validate the accuracy and performance of our program, we first track the 2D position of polystyrene particles using bright field and digital holographic microscopy. Second, we determine the 3D particle position by analyzing synthetic and experimentally acquired holograms. Finally, to highlight the full program features, we profile the microfluidic flow in a 100μm high flow chamber. This result agrees with computational fluid dynamic simulations. On a regular desktop computer UmUTracker can detect, analyze, and track multiple particles at 5 frames per second for a template size of 201 ×201 in a 1024 × 1024 image. To enhance usability and to make it easy to implement new functions we used object-oriented programming. UmUTracker is suitable for studies related to: particle dynamics, cell localization, colloids and microfluidic flow measurement. Program summaryProgram title : UmUTrackerProgram Files doi : http://dx.doi.org/10.17632/fkprs4s6xp.1Licensing provisions : Creative Commons by 4.0 (CC by 4.0)Programming language : MATLABNature of problem: 3D multi-particle tracking is a common technique in physics, chemistry and biology. However, in terms of accuracy, reliable particle tracking is a challenging task since results depend on sample illumination, particle overlap, motion blur and noise from recording sensors. Additionally, the computational performance is also an issue if, for example, a computationally expensive process is executed, such as axial particle position reconstruction from digital holographic microscopy data. Versatile robust tracking programs handling these concerns and providing a powerful post-processing option are significantly limited.Solution method: UmUTracker is a multi-functional tool to extract particle positions from long video sequences acquired with either light microscopy or digital holographic microscopy. The program provides an easy-to-use graphical user interface (GUI) for both tracking and post-processing that does not require any programming skills to analyze data from particle tracking experiments. UmUTracker first conduct automatic 2D particle detection even under noisy conditions using a novel circle detector based on the isosceles triangle sampling technique with a multi-scale strategy. To reduce the computational load for 3D tracking, it uses an efficient implementation of the Rayleigh–Sommerfeld light propagation model. To analyze and visualize the data, an efficient data analysis step, which can for example show 4D flow visualization using 3D trajectories, is included. Additionally, UmUTracker is easy to modify with user-customized modules due to the object-oriented programming styleAdditional comments: Program obtainable from https://sourceforge.net/projects/umutracker/

Effect of Salt Concentration on the Motion of Particles near the Substrate in Drying Sessile Colloidal Droplets.

The motions of the particles on the substrate of a drying sessile colloidal droplet of water were measured using multiparticle tracking. Droplets with different concentrations (0-250 mM) of sodium chloride (NaCl) were compared. Several statistical quantities were proposed to characterize the heterogeneous behaviors of the particles and distinguish the effects of the flow field and the substrate interaction. For the salt-free droplet, most of the particles were nonadsorbed and mobile without friction. With the presence of salt, the fraction of the adsorbed particles increases with increasing evaporation time and the initial salt concentration, which was explained by Derjaguin-Landau-Verwey-Overbeek interaction. The fraction of mobile particles is mostly frictionless for all samples. At low salt concentrations, the velocity of mobile particles increases with the evaporation time to a peak and then decreases. The velocity is lower for higher salt concentrations. The effect of salt on the nonadsorbed particles was attributed to the electrokinetic effect.

Design of a compact ring for proton radiation applications

This paper presents the design of a compact proton synchrotron, including lattice structure, injection system and extraction system, for radiation applications. The lattice is based on a DBFO cell and shows good properties like small βmax and decent kick arm. Radiation applications require relative strong and continuous beam, so we propose strip injection and resonance extraction for the design. A phase space painting scheme is designed and simulated by ORBIT. The scheme achieves good uniformity in phase space. The extraction system is designed and optimized by multi-particle tracking.

Application of DH-PSF three-dimensional dynamic multi-particle tracking method in living cell imaging

Application of DH-PSF three-dimensional dynamic multi-particle tracking method in living cell imaging

Numerical analysis corresponding with experiment in compact beam simulator for heavy ion inertial fusion driver

Tune depression in a compact beam equipment is estimated, and numerical simulation results are compared with an experimental one for the compact beam simulator in a driver of heavy ion inertial fusion. The numerical simulation with multi-particle tracking is carried out, corresponding to the experimental condition, and the result is discussed with the experimental one. It is expected that the numerical simulation developed in this paper is useful tool to investigate the beam dynamics in the experiment with the compact beam simulator.

Analysis and modeling of proton beam loss and emittance growth in the Relativistic Heavy Ion Collider

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been operating since 2000. Over the past decade, thanks to the continuously increased bunch intensity and reduced ${\ensuremath{\beta}}^{*}\mathrm{s}$ at the interaction points, the peak luminosity in the polarized proton operation has been increased by more than two orders of magnitude. In this article, we will present the operational observations at the routine proton physics stores. The mechanisms for the beam loss, transverse emittance growth, and bunch lengthening are analyzed. Numerical calculations and multiparticle tracking are used to model these observations.