scholarly journals OuroborosBEM: a fast multi-GPU microscopic Monte Carlo simulation for gaseous detectors and charged particle dynamics

2022 ◽  
Vol 17 (01) ◽  
pp. P01020
Author(s):  
G. Quéméner ◽  
S. Salvador
Keyword(s):  
Nuclear Physics ◽  
Gaseous Medium ◽  
Dielectric Materials ◽  
Electrostatic Problem ◽  
Charge Effects ◽  
Nvidia Cuda ◽  
Ion Recombination ◽  
Gem Detectors ◽  
Gas Medium ◽  
Graphical Processor

Abstract The design of gaseous detectors for accelerator, particle and nuclear physics requires simulations relying on multi-physics aspects. In fact, these simulations deal with the dynamics of a large number of charged particles interacting in a gaseous medium immersed in the electric field generated by a more or less complex assembly of electrodes and dielectric materials. We report here on a homemade software, called ouroborosbem, able to tackle the different features involved in such simulations. After solving the electrostatic problem for which a solver based on the boundary element method (BEM) has been implemented, particles are tracked and will microscopically interact with the gas medium. Dynamical effects have been included such as the electron-ion recombination process, the charging-up of the dielectric materials and other space charge effects that might alter the detector performances. These were made possible thanks to the nVidia CUDA language specifically optimised to run on Graphical Processor Units (GPUs) to minimize the computing times. Comparisons of the results obtained for parallel plate avalanche counters and GEM detectors to literature data on swarm parameters fully validate the performances of ouroborosbem. Moreover, we were able to precisely reproduce the measured gains of single and double GEM detectors as a function of the applied voltage.

scholarly journals Численное исследование возможности генерации убегающих электронов в формирующемся катодном слое самостоятельного объемного разряда высокого давления

2020 ◽  
Vol 90 (5) ◽  
pp. 740
Author(s):  
В.В. Лисенков
Keyword(s):  
Electric Field ◽  
Gaseous Medium ◽  
Cathode Layer ◽  
Volume Discharge ◽  
Runaway Electrons ◽  
Field Amplification ◽  
Streamer Channel ◽  
Formation Conditions ◽  
Gas Medium ◽  
Plasma Streamer

Calculations of the formation of the cathode layer of an self-sustained high-pressure volume discharge with pre-ionization of the gas medium excited by nano-and subnanosecond voltage pulses are carried out. It is shown that at pressures of ~ 1 atm at the final stage of the cathode layer formation, conditions for the generation of escaping electrons arise. We also considered the transition of electrons into runaway mode from the area of electric field amplification in front of the plasma (streamer) channel, which originates from the top of the micro-spike on the cathode. It is shown that at pressures of ~ 10 atm, electrons can transfer into runaway mode immediately after emission from the top of micro-spike in amplified electric field. Thus obtained runaway electrons can create pre-ionization of the gaseous medium and provide the formation of the initial phase of the discharge in volume form in the system without external pre-ionization.

scholarly journals Interaction of Liquid Droplets in Gas and Vapor Flows

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4256 ◽  
Author(s):  
A. V. Demidovich ◽  
S. S. Kralinova ◽  
P. P. Tkachenko ◽  
N. E. Shlegel ◽  
R. S. Volkov
Keyword(s):  
Surface Area ◽  
Large Scale ◽  
Gaseous Medium ◽  
Liquid Surface ◽  
Liquid Droplet ◽  
Video Frame ◽  
Liquid Droplets ◽  
Large Scale Change ◽  
Frame Processing ◽  
Gas Medium

We investigated the conditions, characteristics, and outcomes of liquid droplet interaction in the gas medium using video frame processing. The frequency of different droplet collision outcomes and their characteristics were determined. Four interaction regimes were identified: bounce, separation, coalescence, and disruption. Collision regime maps were drawn up using the Weber, Reynolds, Ohnesorge, Laplace, and capillary numbers, as well as dimensionless linear and angular parameters of interaction. Significant differences were established between interaction maps under ideal conditions (two droplets colliding without a possible impact of the neighboring ones) and collision of droplets as aerosol elements. It was shown that the Weber number could not be the only criterion for changing the collision mode, and sizes and concentration of droplets in aerosols influence collision modes. It was established that collisions of droplets in a gaseous medium could lead to an increase in the liquid surface area by 1.5–5 times. Such a large-scale change in the surface area of the liquid significantly intensifies heat transfer and phase transformations in energy systems.

scholarly journals The Particle Track Reconstruction based on deep Neural networks

2019 ◽  
Vol 214 ◽  
pp. 06018
Author(s):  
Dmitriy Baranov ◽  
Sergey Mitsyn ◽  
Pavel Goncharov ◽  
Gennady Ososkov
Keyword(s):  
Nuclear Physics ◽  
High Energy ◽  
Neural Nets ◽  
Track Reconstruction ◽  
Reconstruction Procedure ◽  
Event Reconstruction ◽  
Fire Detector ◽  
Pass Through ◽  
Two Stages ◽  
Gem Detectors

One of the most important problems of data processing in high energy and nuclear physics is the event reconstruction. Its main part is the track reconstruction procedure which consists in looking for all tracks that elementary particles leave when they pass through a detector among a huge number of points, so-called hits, produced when flying particles fire detector coordinate planes. Unfortunately, the tracking is seriously impeded by the famous shortcoming of multiwired, strip in GEM detectors due to the appearance in them a lot of fake hits caused by extra spurious crossings of fired strips. Since the number of those fakes is several orders of magnitude greaterthan for true hits, one faces with the quite serious difficulty to unravelpossible track-candidates via true hits ignoring fakes. On the basis of our previous two-stage approach based on hits preprocessing using directed K-d tree search followed by a deep neural classifier we introduce here two new tracking algorithms. Both algorithms combine those two stages in one while using different types of deep neural nets. We show that both proposed deep networks do not require any special preprocessing stage, are more accurate, faster and can be easier parallelized. Preliminary results of our new approaches for simulated events are presented.

Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

1976 ◽  
Vol 32 ◽  
pp. 169-182
Author(s):  
B. Kuchowicz
Keyword(s):  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Chemical Elements ◽  
Fission Products ◽  
Abundance Pattern ◽  
Isotopic Shifts ◽  
Processed Material ◽  
R Process ◽  
Ap Stars ◽  
Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

Specimen Collection Effect in Scanning Electron Microscopy Images

1972 ◽  
Vol 30 ◽  
pp. 448-449
Author(s):  
J. Temple Black ◽  
Jose Guerrero
Keyword(s):  
Surface Morphology ◽  
Secondary Electron Emission ◽  
Secondary Electrons ◽  
Charge Effects ◽  
Material Density ◽  
Specimen Collection ◽  
The Subject ◽  
Curved Paths ◽  
Subject Material ◽  
Microscopy Images

In the SEM, contrast in the image is the result of variations in the volume secondary electron emission and backscatter emission which reaches the detector and serves to intensity modulate the signal for the CRT's. This emission is a function of the accelerating potential, material density, chemistry, crystallography, local charge effects, surface morphology and especially the angle of the incident electron beam with the particular surface site. Aside from the influence of object inclination, the surface morphology is the most important feature In producing contrast. “Specimen collection“ is the name given the shielding of the collector by adjacent parts of the specimen, producing much image contrast. This type of contrast can occur for both secondary and backscatter electrons even though the secondary electrons take curved paths to the detector-collector.Figure 1 demonstrates, in a unique and striking fashion, the specimen collection effect. The subject material here is Armco Iron, 99.85% purity, which was spark machined.

Improvements on the gaseous detector device

1986 ◽  
Vol 44 ◽  
pp. 630-631 ◽  
Author(s):  
G.D. Danilatos
Keyword(s):  
Gaseous Medium ◽  
The Other ◽  
Beam Specimen ◽  
Thin Wires ◽  
Interference Noise ◽  
Backscattered Electron ◽  
Detection Of Signals ◽  
Environmental Sem

The possibility of placing the specimen in a gaseous medium in the environmental SEM (ESEM) has created novel ways for detection of signals from the beam-specimen interactions. It was originally reported by Oanilatos that the ionization produced by certain signals inside the conditioning medium can be used to produce images. The aim of this report is to demonstrate some of the improvements on the system that have occurred thereafter.Two straight thin wires are aligned horizontally along a direction normal to the direction of the two scintillator backscattered electron (BSE) detectors reported elsewhere. The free end tips of the wires are about 5 mm apart halfway between the specimen and the pressure limiting aperture (specimen distance = 1.5 mm). The other end of each wire makes contact with the input of a separate preamplifier, two of which are built inside a shielding aluminum stub. With such a design, interference noise from the input cables is avoided.

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