Solving for the particle-number-projected HFB wavefunction

International Nuclear Information System (INIS)

Jia, L.Y.

2015-01-01

Recently we proposed a particle-number-conserving theory for nuclear pairing (Jia, 2013) [19] through the generalized density matrix formalism. The relevant equations were solved for the case when each single-particle level has a distinct set of quantum numbers and could only pair with its time-reversed partner (BCS-type Hamiltonian). In this work we consider the more general situation when several single-particle levels could have the same set of quantum numbers and pairing among these levels is allowed (HFB-type Hamiltonian). The pair condensate wavefunction (the HFB wavefunction projected onto good particle number) is determined by the equations of motion for density matrix operators instead of the variation principle. The theory is tested in the simple two-level model with factorizable pairing interactions, and semi-realistic models with the zero-range delta interaction and the realistic Bonn-CD interaction

Gravitational sedimentation of cloud of solid spherical particles at small Reynolds numbers

Directory of Open Access Journals (Sweden)

Arkhipov Vladimir

2015-01-01

Full Text Available The experimental results of study of gravitational sedimentation of highly-concentrated systems of solid spherical particles at small Reynolds numbers Re<1 are presented. Empirical equation for drag coefficient of the particle assembly has been obtained. The influence of initial particle concentration in the cloud on its dynamics and velocity has been analysed.

Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions

Directory of Open Access Journals (Sweden)

A. Wiedensohler

2012-03-01

Full Text Available Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers or SMPS (Scanning Mobility Particle Sizers have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer.

We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data.

Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the

Long-term cloud condensation nuclei number concentration, particle number size distribution and chemical composition measurements at regionally representative observatories

Directory of Open Access Journals (Sweden)

J. Schmale

2018-02-01

Full Text Available Aerosol–cloud interactions (ACI constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce the uncertainties and gain more confidence in the simulation of ACI, models need to be evaluated against observations, in particular against measurements of cloud condensation nuclei (CCN. Here we present a data set – ready to be used for model validation – of long-term observations of CCN number concentrations, particle number size distributions and chemical composition from 12 sites on 3 continents. Studied environments include coastal background, rural background, alpine sites, remote forests and an urban surrounding. Expectedly, CCN characteristics are highly variable across site categories. However, they also vary within them, most strongly in the coastal background group, where CCN number concentrations can vary by up to a factor of 30 within one season. In terms of particle activation behaviour, most continental stations exhibit very similar activation ratios (relative to particles  > 20 nm across the range of 0.1 to 1.0 % supersaturation. At the coastal sites the transition from particles being CCN inactive to becoming CCN active occurs over a wider range of the supersaturation spectrum. Several stations show strong seasonal cycles of CCN number concentrations and particle number size distributions, e.g. at Barrow (Arctic haze in spring, at the alpine stations (stronger influence of polluted boundary layer air masses in summer, the rain forest (wet and dry season or Finokalia (wildfire influence in autumn. The rural background and urban sites exhibit relatively little variability throughout the year, while short-term variability can be high especially at the urban site. The average hygroscopicity parameter, κ, calculated from the chemical composition of submicron particles was highest at the coastal site of Mace Head (0.6 and lowest at the rain forest station ATTO (0.2–0.3. We performed closure

Estimation of inhaled airborne particle number concentration by subway users in Seoul, Korea

International Nuclear Information System (INIS)

Kim, Minhae; Park, Sechan; Namgung, Hyeong-Gyu; Kwon, Soon-Bark

2017-01-01

Exposure to airborne particulate matter (PM) causes several diseases in the human body. The smaller particles, which have relatively large surface areas, are actually more harmful to the human body since they can penetrate deeper parts of the lungs or become secondary pollutants by bonding with other atmospheric pollutants, such as nitrogen oxides. The purpose of this study is to present the number of PM inhaled by subway users as a possible reference material for any analysis of the hazards to the human body arising from the inhalation of such PM. Two transfer stations in Seoul, Korea, which have the greatest number of users, were selected for this study. For 0.3–0.422 μm PM, particle number concentration (PNC) was highest outdoors but decreased as the tester moved deeper underground. On the other hand, the PNC between 1 and 10 μm increased as the tester moved deeper underground and showed a high number concentration inside the subway train as well. An analysis of the particles to which subway users are actually exposed to (inhaled particle number), using particle concentration at each measurement location, the average inhalation rate of an adult, and the average stay time at each location, all showed that particles sized 0.01–0.422 μm are mostly inhaled from the outdoor air whereas particles sized 1–10 μm are inhaled as the passengers move deeper underground. Based on these findings, we expect that the inhaled particle number of subway users can be used as reference data for an evaluation of the hazards to health caused by PM inhalation. - Highlights: • Size-dependent aerosol number was measured along the path of subway user. • Particles less than 0.4 μm were inhaled in outdoor but less so as deeper underground. • Coarse particles were inhaled significantly as users moved deeper underground. - We estimated the inhaled aerosol number concentration depending on particle size along the path of subway users.

DNS of buoyancy-driven flows and Lagrangian particle tracking in a square cavity at high Rayleigh numbers

International Nuclear Information System (INIS)

Puragliesi, R.; Dehbi, A.; Leriche, E.; Soldati, A.; Deville, M.O.

2011-01-01

Highlights: → 2D study of micro-size particle depletion driven by chaotic natural convective flows in square domains. → Description of velocity and temperature first and second moments with changing in the Rayleigh number. → Strong decoupling between the turbulent kinetic energy and the dissipation rate. → Particle recirculation sustained by the vertical hot boundary layer. → Deposition mostly induced by gravity, thermophoretic and lift forces are negligible. - Abstract: In this work we investigate numerically particle deposition in the buoyancy driven flow of the differentially heated cavity (DHC). We consider two values of the Rayleigh number (Ra = 10 9 , 10 10 ) and three values of the particle diameter (d p = 15, 25, 35 [μm]). We consider the cavity filled with air and particles with the same density of water ρ w = 1000 [kg/m 3 ] (aerosol). We use direct numerical simulations (DNS) for the continuous phase, and we solve transient Navier-Stokes and energy transport equations written in an Eulerian framework, under the Boussinesq approximation, for the viscous incompressible Newtonian fluid with constant Prandtl number (Pr = 0.71). First- and second-order statistics are presented for the continuous phase as well as important quantities like turbulent kinetic energy (TKE) and temperature variance with the associated production and dissipation fields. The TKE production shows different behaviour at the two Rayleigh numbers. The Lagrangian approach has been chosen for the dispersed phase description. The forces taken into account are drag, gravity, buoyancy, lift and thermophoresis. A first incursion in the sedimentation mechanisms is presented. Current results indicate that the largest contribution to particle deposition is caused by gravitational settling, but a strong recirculating zone, which liftoffs and segregates particles, contributes to decrease settling. Deposition takes place mostly at the bottom wall. The influence of lift and thermophoretic

DNS of buoyancy-driven flows and Lagrangian particle tracking in a square cavity at high Rayleigh numbers

Energy Technology Data Exchange (ETDEWEB)

Puragliesi, R., E-mail: riccardo.puragliesi@psi.ch [Nuclear Energy and Safety Research Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Laboratoire d' Ingenierie Numerique, Ecole Polytechnique Federale de Lausanne, Station 9, CH-1015 Lausanne (Switzerland); Dehbi, A., E-mail: abdel.dehbi@psi.ch [Nuclear Energy and Safety Research Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Leriche, E., E-mail: emmanuel.leriche@univ-st-etienne.fr [Universite de Lyon, F-42023 Saint-Etienne, LMFA-UJM St-Etienne, CNRS UMR 5509 Universite de St-Etienne, 23 rue Docteur Paul Michelon, F-42023 Saint-Etienne (France); Soldati, A., E-mail: soldati@uniud.it [Dipartimento di Energetica e Macchine, Universita di Udine, Via delle Scienze 208, IT-33100 Udine (Italy); Deville, M.O., E-mail: michel.deville@epfl.ch [Laboratoire d' Ingenierie Numerique, Ecole Polytechnique Federale de Lausanne, Station 9, CH-1015 Lausanne (Switzerland)

2011-10-15

Highlights: > 2D study of micro-size particle depletion driven by chaotic natural convective flows in square domains. > Description of velocity and temperature first and second moments with changing in the Rayleigh number. > Strong decoupling between the turbulent kinetic energy and the dissipation rate. > Particle recirculation sustained by the vertical hot boundary layer. > Deposition mostly induced by gravity, thermophoretic and lift forces are negligible. - Abstract: In this work we investigate numerically particle deposition in the buoyancy driven flow of the differentially heated cavity (DHC). We consider two values of the Rayleigh number (Ra = 10{sup 9}, 10{sup 10}) and three values of the particle diameter (d{sub p} = 15, 25, 35 [{mu}m]). We consider the cavity filled with air and particles with the same density of water {rho}{sub w} = 1000 [kg/m{sup 3}] (aerosol). We use direct numerical simulations (DNS) for the continuous phase, and we solve transient Navier-Stokes and energy transport equations written in an Eulerian framework, under the Boussinesq approximation, for the viscous incompressible Newtonian fluid with constant Prandtl number (Pr = 0.71). First- and second-order statistics are presented for the continuous phase as well as important quantities like turbulent kinetic energy (TKE) and temperature variance with the associated production and dissipation fields. The TKE production shows different behaviour at the two Rayleigh numbers. The Lagrangian approach has been chosen for the dispersed phase description. The forces taken into account are drag, gravity, buoyancy, lift and thermophoresis. A first incursion in the sedimentation mechanisms is presented. Current results indicate that the largest contribution to particle deposition is caused by gravitational settling, but a strong recirculating zone, which liftoffs and segregates particles, contributes to decrease settling. Deposition takes place mostly at the bottom wall. The influence of lift

Temperature-dependent particle-number projected moment of inertia

International Nuclear Information System (INIS)

Allal, N. H.; Fellah, M.; Benhamouda, N.; Oudih, M. R.

2008-01-01

Expressions of the parallel and perpendicular temperature-dependent particle-number projected nuclear moment of inertia have been established by means of a discrete projection method. They generalize that of the FTBCS method and are well adapted to numerical computation. The effects of particle-number fluctuations have been numerically studied for some even-even actinide nuclei by using the single-particle energies and eigenstates of a deformed Woods-Saxon mean field. It has been shown that the parallel moment of inertia is practically not modified by the use of the projection method. In contrast, the discrepancy between the projected and FTBCS perpendicular moment of inertia values may reach 5%. Moreover, the particle-number fluctuation effects vary not only as a function of the temperature but also as a function of the deformation for a given temperature. This is not the case for the system energy

High pulse number thermal shock tests on tungsten with steady state particle background

Science.gov (United States)

Wirtz, M.; Kreter, A.; Linke, J.; Loewenhoff, Th; Pintsuk, G.; Sergienko, G.; Steudel, I.; Unterberg, B.; Wessel, E.

2017-12-01

Thermal fatigue of metallic materials, which will be exposed to severe environmental conditions e.g. plasma facing materials in future fusion reactors, is an important issue in order to predict the life time of complete wall components. Therefore experiments in the linear plasma device PSI-2 were performed to investigate the synergistic effects of high pulse number thermal shock events (L = 0.38 GW m-2, Δt = 0.5 ms) and stationary D/He (6%) plasma particle background on the thermal fatigue behavior of tungsten. Similar to experiments with pure thermal loads, the induced microstructural and surface modifications such as recrystallization and roughening as well as crack formation become more pronounced with increasing number of thermal shock events. However, the amount of damage significantly increases for synergistic loads showing severe surface roughening, plastic deformation and erosion resulting from the degradation of the mechanical properties caused by bombardment and diffusion of D/He to the surface and the bulk of the material. Additionally, D/He induced blistering and bubble formation were observed for all tested samples, which could change the thermal and mechanical properties of near surface regions.

Estimation of inhaled airborne particle number concentration by subway users in Seoul, Korea.

Science.gov (United States)

Kim, Minhae; Park, Sechan; Namgung, Hyeong-Gyu; Kwon, Soon-Bark

2017-12-01

Exposure to airborne particulate matter (PM) causes several diseases in the human body. The smaller particles, which have relatively large surface areas, are actually more harmful to the human body since they can penetrate deeper parts of the lungs or become secondary pollutants by bonding with other atmospheric pollutants, such as nitrogen oxides. The purpose of this study is to present the number of PM inhaled by subway users as a possible reference material for any analysis of the hazards to the human body arising from the inhalation of such PM. Two transfer stations in Seoul, Korea, which have the greatest number of users, were selected for this study. For 0.3-0.422 μm PM, particle number concentration (PNC) was highest outdoors but decreased as the tester moved deeper underground. On the other hand, the PNC between 1 and 10 μm increased as the tester moved deeper underground and showed a high number concentration inside the subway train as well. An analysis of the particles to which subway users are actually exposed to (inhaled particle number), using particle concentration at each measurement location, the average inhalation rate of an adult, and the average stay time at each location, all showed that particles sized 0.01-0.422 μm are mostly inhaled from the outdoor air whereas particles sized 1-10 μm are inhaled as the passengers move deeper underground. Based on these findings, we expect that the inhaled particle number of subway users can be used as reference data for an evaluation of the hazards to health caused by PM inhalation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Association of Air Pollution Exposures With High-Density Lipoprotein Cholesterol and Particle Number: The Multi-Ethnic Study of Atherosclerosis.

Science.gov (United States)

Bell, Griffith; Mora, Samia; Greenland, Philip; Tsai, Michael; Gill, Ed; Kaufman, Joel D

2017-05-01

The relationship between air pollution and cardiovascular disease may be explained by changes in high-density lipoprotein (HDL). We examined the cross-sectional relationship between air pollution and both HDL cholesterol and HDL particle number in the MESA Air study (Multi-Ethnic Study of Atherosclerosis Air Pollution). Study participants were 6654 white, black, Hispanic, and Chinese men and women aged 45 to 84 years. We estimated individual residential ambient fine particulate pollution exposure (PM 2.5 ) and black carbon concentrations using a fine-scale likelihood-based spatiotemporal model and cohort-specific monitoring. Exposure periods were averaged to 12 months, 3 months, and 2 weeks prior to examination. HDL cholesterol and HDL particle number were measured in the year 2000 using the cholesterol oxidase method and nuclear magnetic resonance spectroscopy, respectively. We used multivariable linear regression to examine the relationship between air pollution exposure and HDL measures. A 0.7×10 - 6 m - 1 higher exposure to black carbon (a marker of traffic-related pollution) averaged over a 1-year period was significantly associated with a lower HDL cholesterol (-1.68 mg/dL; 95% confidence interval, -2.86 to -0.50) and approached significance with HDL particle number (-0.55 mg/dL; 95% confidence interval, -1.13 to 0.03). In the 3-month averaging time period, a 5 μg/m 3 higher PM 2.5 was associated with lower HDL particle number (-0.64 μmol/L; 95% confidence interval, -1.01 to -0.26), but not HDL cholesterol (-0.05 mg/dL; 95% confidence interval, -0.82 to 0.71). These data are consistent with the hypothesis that exposure to air pollution is adversely associated with measures of HDL. © 2017 American Heart Association, Inc.

Alpha-particle effects on high-n instabilities in tokamaks

International Nuclear Information System (INIS)

Rewoldt, G.

1988-06-01

Hot α-particles and thermalized helium ash particles in tokamaks can have significant effects on high toroidal mode number instabilities such as the trapped-electron drift mode and the kinetically calculated magnetohydrodynamic ballooning mode. In particular, the effects can be stabilizing, destabilizing, or negligible, depending on the parameters involved. In high-temperature tokamaks capable of producing significant numbers of hot α-particles, the predominant interaction of the mode with the α-particles is through resonances of various sorts. In turn, the modes can cause significant anomalous transport of the α-particles and the helium ash. Here, results of comprehensive linear eigenfrequency-eigenfunction calculations are presented for relevant realistic cases to show these effects. 24 refs., 12 figs., 6 tabs

Symmetry mappings concomitant to particle-number-conservation-baryon-number conservation

International Nuclear Information System (INIS)

Davis, W.R.

1977-01-01

Four theorem serve to demonstrate that matter fields in space-time admit certain timelike symmetry mappings concomitant to the familiar notion of particle number conservation, which can be more fundamentally accounted for by a type of projective invariance principle. These particular symmetry mappings include a family of symmetry properties that may be admitted by Riemannian space-times. In their strongest form, the results obtained provide some insight relating to the conservation of baryon number

High resolution study of high mass pairs and high transverse momentum particles

International Nuclear Information System (INIS)

Smith, S.R.

1983-01-01

Preliminary experiments involving the high resolution spectrometer (experiment 605) at Fermilab are described. The spectrometer is designed for the study of pairs of particles at large invariant masses and single particles at large transverse momenta. A number of applications of the apparatus in the study of Drell-Yan processes, e.g. transverse momentum measurement, are discussed

Particle-pair relative velocity measurement in high-Reynolds-number homogeneous and isotropic turbulence using 4-frame particle tracking velocimetry

Science.gov (United States)

Dou, Zhongwang; Ireland, Peter J.; Bragg, Andrew D.; Liang, Zach; Collins, Lance R.; Meng, Hui

2018-02-01

The radial relative velocity (RV) between particles suspended in turbulent flow plays a critical role in droplet collision and growth. We present a simple and accurate approach to RV measurement in isotropic turbulence—planar 4-frame particle tracking velocimetry—using routine PIV hardware. It improves particle positioning and pairing accuracy over the 2-frame holographic approach by de Jong et al. (Int J Multiphas Flow 36:324-332; de Jong et al., Int J Multiphas Flow 36:324-332, 2010) without using high-speed cameras and lasers as in Saw et al. (Phys Fluids 26:111702, 2014). Homogeneous and isotropic turbulent flow ({R_λ }=357) in a new, fan-driven, truncated iscosahedron chamber was laden with either low-Stokes (mean St=0.09, standard deviation 0.05) or high-Stokes aerosols (mean St=3.46, standard deviation 0.57). For comparison, DNS was conducted under similar conditions ({R_λ }=398; St=0.10 and 3.00, respectively). Experimental RV probability density functions (PDF) and mean inward RV agree well with DNS. Mean inward RV increases with St at small particle separations, r, and decreases with St at large r, indicating the dominance of "path-history" and "inertial filtering" effects, respectively. However, at small r, the experimental mean inward RV trends higher than DNS, possibly due to the slight polydispersity of particles and finite light sheet thickness in experiments. To confirm this interpretation, we performed numerical experiments and found that particle polydispersity increases mean inward RV at small r, while finite laser thickness also overestimates mean inward RV at small r, This study demonstrates the feasibility of accurately measuring RV using routine hardware, and verifies, for the first time, the path-history and inertial filtering effects on particle-pair RV at large particle separations experimentally.

Approximate particle number projection in hot nuclei

International Nuclear Information System (INIS)

Kosov, D.S.; Vdovin, A.I.

1995-01-01

Heated finite systems like, e.g., hot atomic nuclei have to be described by the canonical partition function. But this is a quite difficult technical problem and, as a rule, the grand canonical partition function is used in the studies. As a result, some shortcomings of the theoretical description appear because of the thermal fluctuations of the number of particles. Moreover, in nuclei with pairing correlations the quantum number fluctuations are introduced by some approximate methods (e.g., by the standard BCS method). The exact particle number projection is very cumbersome and an approximate number projection method for T ≠ 0 basing on the formalism of thermo field dynamics is proposed. The idea of the Lipkin-Nogami method to perform any operator as a series in the number operator powers is used. The system of equations for the coefficients of this expansion is written and the solution of the system in the next approximation after the BCS one is obtained. The method which is of the 'projection after variation' type is applied to a degenerate single j-shell model. 14 refs., 1 tab

Pseudo-random number generation for Brownian Dynamics and Dissipative Particle Dynamics simulations on GPU devices

International Nuclear Information System (INIS)

Phillips, Carolyn L.; Anderson, Joshua A.; Glotzer, Sharon C.

2011-01-01

Highlights: → Molecular Dynamics codes implemented on GPUs have achieved two-order of magnitude computational accelerations. → Brownian Dynamics and Dissipative Particle Dynamics simulations require a large number of random numbers per time step. → We introduce a method for generating small batches of pseudorandom numbers distributed over many threads of calculations. → With this method, Dissipative Particle Dynamics is implemented on a GPU device without requiring thread-to-thread communication. - Abstract: Brownian Dynamics (BD), also known as Langevin Dynamics, and Dissipative Particle Dynamics (DPD) are implicit solvent methods commonly used in models of soft matter and biomolecular systems. The interaction of the numerous solvent particles with larger particles is coarse-grained as a Langevin thermostat is applied to individual particles or to particle pairs. The Langevin thermostat requires a pseudo-random number generator (PRNG) to generate the stochastic force applied to each particle or pair of neighboring particles during each time step in the integration of Newton's equations of motion. In a Single-Instruction-Multiple-Thread (SIMT) GPU parallel computing environment, small batches of random numbers must be generated over thousands of threads and millions of kernel calls. In this communication we introduce a one-PRNG-per-kernel-call-per-thread scheme, in which a micro-stream of pseudorandom numbers is generated in each thread and kernel call. These high quality, statistically robust micro-streams require no global memory for state storage, are more computationally efficient than other PRNG schemes in memory-bound kernels, and uniquely enable the DPD simulation method without requiring communication between threads.

Treatment of the intrinsic Hamiltonian in particle-number nonconserving theories

International Nuclear Information System (INIS)

Hergert, H.; Roth, R.

2009-01-01

We discuss the implications of using an intrinsic Hamiltonian in theories without particle-number conservation, e.g., the Hartree-Fock-Bogoliubov approximation, where the Hamiltonian's particle-number dependence leads to discrepancies if one naively replaces the particle-number operator by its expectation value. We develop a systematic expansion that fixes this problem and leads to an a posteriori justification of the widely-used one- plus two-body form of the intrinsic kinetic energy in nuclear self-consistent field methods. The expansion's convergence properties as well as its practical applications are discussed for several sample nuclei.

Frozen density embedding with non-integer subsystems' particle numbers.

Science.gov (United States)

Fabiano, Eduardo; Laricchia, Savio; Della Sala, Fabio

2014-03-21

We extend the frozen density embedding theory to non-integer subsystems' particles numbers. Different features of this formulation are discussed, with special concern for approximate embedding calculations. In particular, we highlight the relation between the non-integer particle-number partition scheme and the resulting embedding errors. Finally, we provide a discussion of the implications of the present theory for the derivative discontinuity issue and the calculation of chemical reactivity descriptors.

Estimating particle number size distributions from multi-instrument observations with Kalman Filtering

Energy Technology Data Exchange (ETDEWEB)

Viskari, T.

2012-07-01

Atmospheric aerosol particles have several important effects on the environment and human society. The exact impact of aerosol particles is largely determined by their particle size distributions. However, no single instrument is able to measure the whole range of the particle size distribution. Estimating a particle size distribution from multiple simultaneous measurements remains a challenge in aerosol physical research. Current methods to combine different measurements require assumptions concerning the overlapping measurement ranges and have difficulties in accounting for measurement uncertainties. In this thesis, Extended Kalman Filter (EKF) is presented as a promising method to estimate particle number size distributions from multiple simultaneous measurements. The particle number size distribution estimated by EKF includes information from prior particle number size distributions as propagated by a dynamical model and is based on the reliabilities of the applied information sources. Known physical processes and dynamically evolving error covariances constrain the estimate both over time and particle size. The method was tested with measurements from Differential Mobility Particle Sizer (DMPS), Aerodynamic Particle Sizer (APS) and nephelometer. The particle number concentration was chosen as the state of interest. The initial EKF implementation presented here includes simplifications, yet the results are positive and the estimate successfully incorporated information from the chosen instruments. For particle sizes smaller than 4 micrometers, the estimate fits the available measurements and smooths the particle number size distribution over both time and particle diameter. The estimate has difficulties with particles larger than 4 micrometers due to issues with both measurements and the dynamical model in that particle size range. The EKF implementation appears to reduce the impact of measurement noise on the estimate, but has a delayed reaction to sudden

First long-term study of particle number size distributions and new particle formation events of regional aerosol in the North China Plain

Directory of Open Access Journals (Sweden)

X. J. Shen

2011-02-01

Full Text Available Atmospheric particle number size distributions (size range 0.003–10 μm were measured between March 2008 and August 2009 at Shangdianzi (SDZ, a rural research station in the North China Plain. These measurements were made in an attempt to better characterize the tropospheric background aerosol in Northern China. The mean particle number concentrations of the total particle, as well as the nucleation, Aitken, accumulation and coarse mode were determined to be 1.2 ± 0.9 × 10⁴, 3.6 ± 7.9 × 10³, 4.4 ± 3.4 × 10³, 3.5 ± 2.8 × 10³ and 2 ± 3 cm⁻³, respectively. A general finding was that the particle number concentration was higher during spring compared to the other seasons. The air mass origin had an important effect on the particle number concentration and new particle formation events. Air masses from northwest (i.e. inner Asia favored the new particle formation events, while air masses from southeast showed the highest particle mass concentration. Significant diurnal variations in particle number were observed, which could be linked to new particle formation events, i.e. gas-to-particle conversion. During particle formation events, the number concentration of the nucleation mode rose up to maximum value of 10⁴ cm⁻³. New particle formation events were observed on 36% of the effective measurement days. The formation rate ranged from 0.7 to 72.7 cm⁻³ s⁻¹, with a mean value of 8.0 cm⁻³ s⁻¹. The value of the nucleation mode growth rate was in the range of 0.3–14.5 nm h⁻¹, with a mean value of 4.3 nm h⁻¹. It was an essential observation that on many occasions the nucleation mode was able to grow into the size of cloud condensation nuclei (CCN within a matter of several hours. Furthermore, the new particle formation was regularly followed by a measurable increase in particle mass

Pseudo-random number generation for Brownian Dynamics and Dissipative Particle Dynamics simulations on GPU devices

Science.gov (United States)

Phillips, Carolyn L.; Anderson, Joshua A.; Glotzer, Sharon C.

2011-08-01

Brownian Dynamics (BD), also known as Langevin Dynamics, and Dissipative Particle Dynamics (DPD) are implicit solvent methods commonly used in models of soft matter and biomolecular systems. The interaction of the numerous solvent particles with larger particles is coarse-grained as a Langevin thermostat is applied to individual particles or to particle pairs. The Langevin thermostat requires a pseudo-random number generator (PRNG) to generate the stochastic force applied to each particle or pair of neighboring particles during each time step in the integration of Newton's equations of motion. In a Single-Instruction-Multiple-Thread (SIMT) GPU parallel computing environment, small batches of random numbers must be generated over thousands of threads and millions of kernel calls. In this communication we introduce a one-PRNG-per-kernel-call-per-thread scheme, in which a micro-stream of pseudorandom numbers is generated in each thread and kernel call. These high quality, statistically robust micro-streams require no global memory for state storage, are more computationally efficient than other PRNG schemes in memory-bound kernels, and uniquely enable the DPD simulation method without requiring communication between threads.

On-board measurement of particle numbers and their size distribution from a light-duty diesel vehicle: Influences of VSP and altitude.

Science.gov (United States)

Liu, Jia; Ge, Yunshan; Wang, Xin; Hao, Lijun; Tan, Jianwei; Peng, Zihang; Zhang, Chuanzhen; Gong, Huiming; Huang, Ying

2017-07-01

In this study, the particle size-resolved distribution from a China-3 certificated light-duty diesel vehicle was measured by using a portable emission measurement system (PEMS). In order to examine the influences of vehicle specific power (VSP) and high-altitude operation, measurements were conducted at 8 constant speeds, which ranged from 10 to 80km/hr at 10km/hr intervals, and two different high altitudes, namely 2200 and 3200m. The results demonstrated that the numbers of particles in all size ranges decreased significantly as VSP increased when the test vehicle was running at lower speeds (vehicle resulted in increased particle number emissions at low and high driving speeds; however, particle numbers obtained at moderate speeds decreased as altitude rose. When the test vehicle was running at moderate speeds, particle numbers measured at the two altitudes were very close, except for comparatively higher number concentrations of nanoparticles measured at 2200m. Copyright © 2017. Published by Elsevier B.V.

On creating macroscopically identical granular systems with different numbers of particles

Science.gov (United States)

van der Meer, Devaraj; Rivas, Nicolas

2015-11-01

One of the fundamental differences between granular and molecular hydrodynamics is the enormous difference in the total number of constituents. The small number of particles implies that the role of fluctuations in granular dynamics is of paramount importance. To obtain more insight in these fluctuations, we investigate to what extent it is possible to create identical granular hydrodynamic states with different number of particles. A definition is given of macroscopically equivalent systems, and the dependency of the conservation equations on the particle size is studied. We show that, in certain cases, and by appropriately scaling the microscopic variables, we are able to compare systems with significantly different number of particles that present the same macroscopic phenomenology. We apply these scalings in simulations of a vertically vibrated system, namely the density inverted granular Leidenfrost state and its transition to a buoyancy-driven convective state.

Particle number size distributions in urban air before and after volatilisation

Directory of Open Access Journals (Sweden)

W. Birmili

2010-05-01

Full Text Available Aerosol particle number size distributions (size range 0.003–10 μm in the urban atmosphere of Augsburg (Germany were examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration between November 2004 and November 2006 was 12 200 cm⁻³, i.e. similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer as consequence of more frequent inversion situations and enhanced particulate emissions. The diurnal variations of particle number were shaped by a remarkable maximum in the morning during the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening concentration maximum could frequently be observed, suggesting a re-stratification of the urban atmosphere. Overall, the mixed layer height turned out to be the most influential meteorological parameter on the particle size distribution. Its influence was even greater than that of the geographical origin of the prevailing synoptic-scale air mass.

Size distributions below 0.8 μm were also measured downstream of a thermodenuder (temperature: 300 °C, allowing to retrieve the volume concentration of non-volatile compounds. The balance of particle number upstream and downstream of the thermodenuder suggests that practically all particles >12 nm contain a non-volatile core while additional nucleation of particles smaller than 6 nm could be observed after the thermodenuder as an interfering artifact of the method. The good correlation between the non-volatile volume concentration and an independent measurement of the aerosol absorption coefficient (R²=0.9 suggests a close correspondence of the refractory and light-absorbing particle fractions. Using the "summation method", an average diameter ratio of particles before and after volatilisation could

The average number of alpha-particle hits to the cell nucleus required to eradicate a tumour cell population

International Nuclear Information System (INIS)

Roeske, John C; Stinchcomb, Thomas G

2006-01-01

Alpha-particle emitters are currently being considered for the treatment of micrometastatic disease. Based on in vitro studies, it has been speculated that only a few alpha-particle hits to the cell nucleus are considered lethal. However, such estimates do not consider the stochastic variations in the number of alpha-particle hits, energy deposited, or in the cell survival process itself. Using a tumour control probability (TCP) model for alpha-particle emitters, we derive an estimate of the average number of hits to the cell nucleus required to provide a high probability of eradicating a tumour cell population. In simulation studies, our results demonstrate that the average number of hits required to achieve a 90% TCP for 10 4 clonogenic cells ranges from 18 to 108. Those cells that have large cell nuclei, high radiosensitivities and alpha-particle emissions occurring primarily in the nuclei tended to require more hits. As the clinical implementation of alpha-particle emitters is considered, this type of analysis may be useful in interpreting clinical results and in designing treatment strategies to achieve a favourable therapeutic outcome. (note)

On the time-averaging of ultrafine particle number size spectra in vehicular plumes

Directory of Open Access Journals (Sweden)

X. H. Yao

2006-01-01

Full Text Available Ultrafine vehicular particle (<100 nm number size distributions presented in the literature are mostly averages of long scan-time (~30 s or more spectra mainly due to the non-availability of commercial instruments that can measure particle distributions in the <10 nm to 100 nm range faster than 30 s even though individual researchers have built faster (1–2.5 s scanning instruments. With the introduction of the Engine Exhaust Particle Sizer (EEPS in 2004, high time-resolution (1 full 32-channel spectrum per second particle size distribution data become possible and allow atmospheric researchers to study the characteristics of ultrafine vehicular particles in rapidly and perhaps randomly varying high concentration environments such as roadside, on-road and tunnel. In this study, particle size distributions in these environments were found to vary as rapidly as one second frequently. This poses the question on the generality of using averages of long scan-time spectra for dynamic and/or mechanistic studies in rapidly and perhaps randomly varying high concentration environments. One-second EEPS data taken at roadside, on roads and in tunnels by a mobile platform are time-averaged to yield 5, 10, 30 and 120 s distributions to answer this question.

Aerosol particle mixing state, refractory particle number size distributions and emission factors in a polluted urban environment: Case study of Metro Manila, Philippines

Science.gov (United States)

Kecorius, Simonas; Madueño, Leizel; Vallar, Edgar; Alas, Honey; Betito, Grace; Birmili, Wolfram; Cambaliza, Maria Obiminda; Catipay, Grethyl; Gonzaga-Cayetano, Mylene; Galvez, Maria Cecilia; Lorenzo, Genie; Müller, Thomas; Simpas, James B.; Tamayo, Everlyn Gayle; Wiedensohler, Alfred

2017-12-01

studies reported such high number concentration of ultrafine refractory particles under ambient conditions. Inverse modeling of emission factors of refractory particle number size distributions revealed that diesel-fed public utility Jeepneys, commonly used for public transportation, are responsible for 94% of total roadside emitted refractory particle mass. The observed results showed that the majority of urban pollution in Metro Manila is dominated by carbonaceous aerosol. This suggests that PM10 or PM2.5 metrics do not fully describe possible health related effects in this kind of urban environments. Extremely high concentrations of ultrafine particles have been and will continue to induce adverse health related effects, because of their potential toxicity. We imply that in megacities, where the major fraction of particulates originates from the transport sector, PM10 or PM2.5 mass concentration should be complemented by legislative measurements of equivalent black carbon mass concentration.

Fast digital processor for event selection according to particle number difference

International Nuclear Information System (INIS)

Basiladze, S.G.; Gus'kov, B.N.; Li Van Sun; Maksimov, A.N.; Parfenov, A.N.

1978-01-01

A fast digital processor for a magnetic spectrometer is described. It is used in experimental searches for charmed particles. The basic purpose of the processor is discriminating events in the difference of numbers of particles passing through two proportional chambers (PC). The processor consists of three units for detecting signals with PC, and a binary coder. The number of inputs of the processor is 32 for the first PC and 64 for the second. The difference in the number of particles discriminated is from 0 to 8. The resolution time is 180 ns. The processor is built in the CAMAC standard

How comparable are size-resolved particle number concentrations from different instruments?

Science.gov (United States)

Hornsby, K. E.; Pryor, S. C.

2012-12-01

The need for comparability of particle size resolved measurements originates from multiple drivers including: (i) Recent suggestions that air quality standards for particulate matter should migrate from being mass-based to incorporating number concentrations. This move would necessarily be predicated on measurement comparability which is absolutely critical to compliance determination. (ii) The need to quantify and diagnose causes of variability in nucleation and growth rates in nano-particle experiments conducted in different locations. (iii) Epidemiological research designed to identify key parameters in human health responses to fine particle exposure. Here we present results from a detailed controlled laboratory instrument inter-comparison experiment designed to investigate data comparability in the size range of 2.01-523.3 nm across a range of particle composition, modal diameter and absolute concentration. Particle size distributions were generated using a TSI model 3940 Aerosol Generation System (AGS) diluted using zero air, and sampled using four TSI Scanning Mobility Particle Spectrometer (SMPS) configurations and a TSI model 3091 Fast Mobility Particle Sizer (FMPS). The SMPS configurations used two Electrostatic Classifiers (EC) (model 3080) attached to either a Long DMA (LDMA) (model 3081) or a Nano DMA (NDMA) (model 3085) plumbed to either a TSI model 3025A Butanol Condensed Particle Counting (CPC) or a TSI model 3788 Water CPC. All four systems were run using both high and low flow conditions, and were operated with both the internal diffusion loss and multiple charge corrections turned on. The particle compositions tested were sodium chloride, ammonium nitrate and olive oil diluted in ethanol. Particles of all three were generated at three peak concentration levels (spanning the range observed at our experimental site), and three modal particle diameters. Experimental conditions were maintained for a period of 20 minutes to ensure experimental

Baryon number violation and particle collider experiments

International Nuclear Information System (INIS)

Klinkhamer, F.R.; Nationaal Inst. voor Kernfysica en Hoge-Energiefysica

1992-09-01

Baryon number non-conservation, due to non-perturbative effects (sphalerons) in the standard model, may have been important in the early Universe. In this paper the possibility is discussed that similar effects could show up at future particle collider experiments. (author). 16 refs.; 3 figs

Multi-particle correlation observables in high energy nucleus-nucleus collisions

International Nuclear Information System (INIS)

Stock, R.

1981-01-01

Global features of exclusively measured events, including number correlations and vector correlations, and hybrid analysis of measurements of one or two specific fragments like spectator nuclei, high transverse momentum particles, polarization of one particle, etc., are considered

Particle number fluctuations for the van der Waals equation of state

International Nuclear Information System (INIS)

Vovchenko, V; Anchishkin, D V; Gorenstein, M I

2015-01-01

The van der Waals (VDW) equation of state describes a thermal equilibrium in system of particles, where both repulsive and attractive interactions between them are included. This equation predicts the existence of the first order liquid–gas phase transition and the critical point. The standard form of the VDW equation is given by the pressure function in a canonical ensemble (CE) with a fixed number of particles. In this paper the VDW equation is derived within the grand canonical ensemble (GCE) formulation. We argue that this procedure can be useful for new physical applications, in particular, the fluctuations of the number of particles, which are absent in the CE, can be studied in the GCE. For the VDW equation of state in the GCE the particle number fluctuations are calculated for the whole phase diagram, both outside and inside the liquid–gas mixed phase region. It is shown that the scaled variance of these fluctuations remains finite within the mixed phase and goes to infinity at the critical point. The GCE formulation of the VDW equation of state can also be an important step for its application in the statistical description of hadronic systems, where numbers of different particle species are usually not conserved. (paper)

Irradiation of single cells with individual high-LET particles

International Nuclear Information System (INIS)

Nelson, J.M.; Braby, L.A.

1993-01-01

The dose-limiting normal tissue of concern when irradiating head and neck lesions is often the vascular endothelium within the treatment field. Consequently, the response of capillary endothelial cells exposed to moderate doses of high LET particles is essential for establishing exposure limits for neutron-capture therapy. In an effort to characterize the high-LET radiation biology of cultured endothelial cells, the authors are attempting to measure cellular response to single particles. The single-particle irradiation apparatus, described below, allows them to expose individual cells to known numbers of high-LET particles and follow these cells for extended periods, in order to assess the impact of individual particles on cell growth kinetics. Preliminary cell irradiation experiments have revealed complications related to the smooth and efficient operation of the equipment; these are being resolved. Therefore, the following paragraphs deal primarily with the manner by which high LET particles deposit energy, the requirements for single-cell irradiation, construction and assembly of such apparatus, and testing of experimental procedures, rather than with the radiation biology of endothelial cells

Particle capture efficiency in a multi-wire model for high gradient magnetic separation

KAUST Repository

Eisenträger, Almut

2014-07-21

High gradient magnetic separation (HGMS) is an efficient way to remove magnetic and paramagnetic particles, such as heavy metals, from waste water. As the suspension flows through a magnetized filter mesh, high magnetic gradients around the wires attract and capture the particles removing them from the fluid. We model such a system by considering the motion of a paramagnetic tracer particle through a periodic array of magnetized cylinders. We show that there is a critical Mason number (ratio of viscous to magnetic forces) below which the particle is captured irrespective of its initial position in the array. Above this threshold, particle capture is only partially successful and depends on the particle\\'s entry position. We determine the relationship between the critical Mason number and the system geometry using numerical and asymptotic calculations. If a capture efficiency below 100% is sufficient, our results demonstrate how operating the HGMS system above the critical Mason number but with multiple separation cycles may increase efficiency. © 2014 AIP Publishing LLC.

Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

Directory of Open Access Journals (Sweden)

E. Järvinen

2013-08-01

Full Text Available We studied new particle formation and modal behavior of ultrafine aerosol particles on the high East Antarctic plateau at the Concordia station, Dome C (75°06' S, 123°23' E. Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, natural new particle formation was observed on 60 days and for 15 of these days the particle growth rates from 10 to 25 nm in size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed at other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events slowly growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in central Antarctica.

Variability of sub-micrometer particle number size distributions and concentrations in the Western Mediterranean regional background

Directory of Open Access Journals (Sweden)

Michael Cusack

2013-02-01

Full Text Available This study focuses on the daily and seasonal variability of particle number size distributions and concentrations, performed at the Montseny (MSY regional background station in the western Mediterranean from October 2010 to June 2011. Particle number concentrations at MSY were shown to be within range of various other sites across Europe reported in literature, but the seasonality of the particle number size distributions revealed significant differences. The Aitken mode is the dominant particle mode at MSY, with arithmetic mean concentrations of 1698 cm3, followed by the accumulation mode (877 cm−3 and the nucleation mode (246 cm−3. Concentrations showed a strong seasonal variability with large increases in particle number concentrations observed from the colder to warmer months. The modality of median size distributions was typically bimodal, except under polluted conditions when the size distribution was unimodal. During the colder months, the daily variation of particle number size distributions are strongly influenced by a diurnal breeze system, whereby the Aitken and accumulation modes vary similarly to PM1 and BC mass concentrations, with nocturnal minima and sharp day-time increases owing to the development of a diurnal mountain breeze. Under clean air conditions, high levels of nucleation and lower Aitken mode concentrations were measured, highlighting the importance of new particle formation as a source of particles in the absence of a significant condensation sink. During the warmer months, nucleation mode concentrations were observed to be relatively elevated both under polluted and clean conditions due to increased photochemical reactions, with enhanced subsequent growth owing to elevated concentrations of condensable organic vapours produced from biogenic volatile organic compounds, indicating that nucleation at MSY does not exclusively occur under clean air conditions. Finally, mixing of air masses between polluted and non

Fluctuations in non-ideal pion gas with dynamically fixed particle number

Science.gov (United States)

Kolomeitsev, E. E.; Voskresensky, D. N.

2018-05-01

We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the λϕ4 interaction. The effective Lagrangian for the description of such a system is obtained after dropping the terms responsible for the change of the total particle number. Reactions π+π- ↔π0π0, which determine the isospin balance of the medium, are permitted. Within the self-consistent Hartree approximation we compute the effective pion mass, thermodynamic characteristics of the system and the variance of the particle number at temperatures above the critical point of the induced Bose-Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. We analyze conditions for the condensate formation in the process of thermalization of an initially non-equilibrium pion gas. The normalized variance of the particle number increases with a temperature decrease but remains finite in the critical point of the Bose-Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case. In the kinetic regime of the condensate formation the variance is shown to stay finite also.

Explaining the spatiotemporal variation of fine particle number concentrations over Beijing and surrounding areas in an air quality model with aerosol microphysics

International Nuclear Information System (INIS)

Chen, Xueshun; Wang, Zifa; Li, Jie; Chen, Huansheng; Hu, Min; Yang, Wenyi; Wang, Zhe; Ge, Baozhu; Wang, Dawei

2017-01-01

In this study, a three-dimensional air quality model with detailed aerosol microphysics (NAQPMS + APM) was applied to simulate the fine particle number size distribution and to explain the spatiotemporal variation of fine particle number concentrations in different size ranges over Beijing and surrounding areas in the haze season (Jan 15 to Feb 13 in 2006). Comparison between observations and the simulation indicates that the model is able to reproduce the main features of the particle number size distribution. The high number concentration of total particles, up to 26600 cm −3 in observations and 39800 cm −3 in the simulation, indicates the severity of pollution in Beijing. We find that primary particles with secondary species coating and secondary particles together control the particle number size distribution. Secondary particles dominate particle number concentration in the nucleation mode. Primary and secondary particles together determine the temporal evolution and spatial pattern of particle number concentration in the Aitken mode. Primary particles dominate particle number concentration in the accumulation mode. Over Beijing and surrounding areas, secondary particles contribute at least 80% of particle number concentration in the nucleation mode but only 10–20% in the accumulation mode. Nucleation mode particles and accumulation mode particles are anti-phased with each other. Nucleation or primary emissions alone could not explain the formation of the particle number size distribution in Beijing. Nucleation has larger effects on ultrafine particles while primary particles emissions are efficient in producing large particles in the accumulation mode. Reduction in primary particle emissions does not always lead to a decrease in the number concentration of ultrafine particles. Measures to reduce fine particle pollution in terms of particle number concentration may be different from those addressing particle mass concentration. - Highlights: �

Gravitational settling of a highly concentrated system of solid spherical particles

Science.gov (United States)

Arkhipov, V. A.; Usanina, A. S.

2017-09-01

In the present paper, we report on the results of an experimental study of the process of gravity sedimentation of a cloud of monodispersed solid spherical particles with initial volume concentration C > 0.03, which was performed in a wide range of Reynolds numbers. An analytical estimate of the settling regimes of spherical particle clouds is presented. A new method for creating a spherical particle cloud with a high concentration of particles is proposed. A qualitative picture of the settling process of a highly concentrated particle cloud under gravity is revealed. A criterial dependence for the drag coefficient of a sedimenting spherical particle cloud as an entity is obtained.

[Particle Size and Number Density Online Analysis for Particle Suspension with Polarization-Differentiation Elastic Light Scattering Spectroscopy].

Science.gov (United States)

Chen, Wei-kang; Fang, Hui

2016-03-01

The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products.

Exposure to carbon monoxide, fine particle mass, and ultrafine particle number in Jakarta, Indonesia: effect of commute mode.

Science.gov (United States)

Both, Adam F; Westerdahl, Dane; Fruin, Scott; Haryanto, Budi; Marshall, Julian D

2013-01-15

We measured real-time exposure to PM(2.5), ultrafine PM (particle number) and carbon monoxide (CO) for commuting workers school children, and traffic police, in Jakarta, Indonesia. In total, we measured exposures for 36 individuals covering 93 days. Commuters in private cars experienced mean (st dev) exposures of 22 (9.4) ppm CO, 91 (38) μg/m(3)PM(2.5), and 290 (150)×10(3) particles cm(-3). Mean concentrations were higher in public transport than in private cars for PM(2.5) (difference in means: 22%) and particle counts (54%), but not CO, likely reflecting in-vehicle particle losses in private cars owing to air-conditioning. However, average commute times were longer for private car commuters than public transport commuters (in our sample, 24% longer: 3.0 vs. 2.3 h per day). Commute and traffic-related exposures experienced by Jakarta residents are among the highest in the world, owing to high on-road concentrations and multi-hour commutes. Copyright © 2012 Elsevier B.V. All rights reserved.

Particle number emissions of gasoline hybrid electric vehicles; Partikelanzahl-Emission bei Hybridfahrzeugen mit Ottomotor

Energy Technology Data Exchange (ETDEWEB)

Porter, Scott [Horiba Instruments Inc., Ann Arbor, MI (United States)

2012-04-15

Hybrid Electric Vehicles (HEV) are commonly reputed to be environmentally friendly. Different studies show that this assumption raises some questions in terms of particle number emissions. Against the background that upcoming emission standards will not only limit particle matter emissions but also particle number emissions for gasoline engines, the exhaust behaviour of downsized gasoline engines used in HEV should be investigated more extensively. A Horiba study compares the particle number emissions of a gasoline vehicle to those of a gasoline powered HEV. (orig.)

Characterisation of sub-micron particle number concentrations and formation events in the western Bushveld Igneous Complex, South Africa

Directory of Open Access Journals (Sweden)

A. Hirsikko

2012-05-01

Full Text Available South Africa holds significant mineral resources, with a substantial fraction of these reserves occurring and being processed in a large geological structure termed the Bushveld Igneous Complex (BIC. The area is also highly populated by informal, semi-formal and formal residential developments. However, knowledge of air quality and research related to the atmosphere is still very limited in the area. In order to investigate the characteristics and processes affecting sub-micron particle number concentrations and formation events, air ion and aerosol particle size distributions and number concentrations, together with meteorological parameters, trace gases and particulate matter (PM were measured for over two years at Marikana in the heart of the western BIC. The observations showed that trace gas (i.e. SO₂, NO_x, CO and black carbon concentrations were relatively high, but in general within the limits of local air quality standards. The area was characterised by very high condensation sink due to background aerosol particles, PM₁₀ and O₃ concentration. The results indicated that high amounts of Aitken and accumulation mode particles originated from domestic burning for heating and cooking in the morning and evening, while during daytime SO₂-based nucleation followed by the growth by condensation of vapours from industrial, residential and natural sources was the most probable source for large number concentrations of nucleation and Aitken mode particles. Nucleation event day frequency was extremely high, i.e. 86% of the analysed days, which to the knowledge of the authors is the highest frequency ever reported. The air mass back trajectory and wind direction analyses showed that the secondary particle formation was influenced both by local and regional pollution and vapour sources. Therefore, our observation of the annual cycle and magnitude of the particle formation and growth rates during

On the number of elementary particles in a resolution dependent fractal spacetime

International Nuclear Information System (INIS)

He Jihuan

2007-01-01

We reconsider the fundamental question regarding the number of elementary particles in a minimally extended standard model. The main conclusion is that since the dimension of E-infinity spacetime is resolution dependent, then the number of elementary particles is also resolution dependent. For D = 10 of superstrings, D = 11 of M theory and D = 12 of F theory one finds N(SM) equal to (6)(10) = 60 (6)(11) = 66 and (6)(12) = 72 particles, respectively. This is in perfect agreement with prediction made previously by Mohamed Saladin El-Naschie and Marek-Crnjac

Determination of the critical Shields number for particle erosion in laminar flow

OpenAIRE

Ouriemi , Malika; Aussillous , Pascale; Medale , Marc; Peysson , Yannick; Guazzelli , Élisabeth

2007-01-01

International audience; We present reproducible experimental measurements for the onset of grain motion in laminar flow and find a constant critical Shields number for particle erosion, i.e., c = 0.12± 0.03, over a large range of small particle Reynolds number: 1.5 10 −5 Re p 0.76. Comparison with previous studies found in the literature is provided.

Statistics of an ideal homogeneous Bose gas with a fixed number of particles

International Nuclear Information System (INIS)

Alekseev, Vladimir A

2001-01-01

The distribution function w 0 (n 0 ) of the number n 0 of particles is found for the condensate of an ideal gas of free bosons with a fixed total number N of particles. It is shown that above the critical temperature (T > T c ) this function has the usual form w 0 (n 0 ) = (1 - e μ )e μn 0 , where μ is the chemical potential in temperature units. In a narrow vicinity of the critical temperature |T/T c - 1| ≤ N -1/3 , this distribution changes and at T c acquires the form of a resonance. The width of the resonance depends on the shape of the volume occupied by the gas and it has exponential (but not the Gaussian) wings. As the temperature is lowered, the resonance maximum shifts to larger values of n 0 and its width tends to zero, which corresponds to the suppression of fluctuations. For N → ∞, this change occurs abruptly. The distribution function of the number of particles in excited states for the systems with a fixed and a variable number of particles (when only a mean number of particles is fixed) prove to be identical and have the usual form. (physical basis of quantum electronics)

Broken flavor symmetries in high energy particle phenomenology

International Nuclear Information System (INIS)

Antaramian, A.

1995-01-01

Over the past couple of decades, the Standard Model of high energy particle physics has clearly established itself as an invaluable tool in the analysis of high energy particle phenomenon. However, from a field theorists point of view, there are many dissatisfying aspects to the model. One of these, is the large number of free parameters in the theory arising from the Yukawa couplings of the Higgs doublet. In this thesis, we examine various issues relating to the Yukawa coupeng structure of high energy particle field theories. We begin by examining extensions to the Standard Model of particle physics which contain additional scalar fields. By appealing to the flavor structure observed in the fermion mass and Kobayashi-Maskawa matrices, we propose a reasonable phenomenological parameterization of the new Yukawa couplings based on the concept of approximate flavor symmetries. It is shown that such a parameterization eliminates the need for discrete symmetries which limit the allowed couplings of the new scalars. New scalar particles which can mediate exotic flavor changing reactions can have masses as low as the weak scale. Next, we turn to the issue of neutrino mass matrices, where we examine a particular texture which leads to matter independent neutrino oscillation results for solar neutrinos. We, then, examine the basis for extremely strict limits placed on flavor changing interactions which also break lepton- and/or baryon-number. These limits are derived from cosmological considerations. Finally, we embark on an extended analysis of proton decay in supersymmetric SO(10) grand unified theories. In such theories, the dominant decay diagrams involve the Yukawa couplings of a heavy triplet superfield. We argue that past calculations of proton decay which were based on the minimal supersymmetric SU(5) model require reexamination because the Yukawa couplings of that theory are known to be wrong

Nuclear reactions induced by high-energy alpha particles

Science.gov (United States)

Shen, B. S. P.

1974-01-01

Experimental and theoretical studies of nuclear reactions induced by high energy protons and heavier ions are included. Fundamental data needed in the shielding, dosimetry, and radiobiology of high energy particles produced by accelerators were generated, along with data on cosmic ray interaction with matter. The mechanism of high energy nucleon-nucleus reactions is also examined, especially for light target nuclei of mass number comparable to that of biological tissue.

A Non-Perturbative, Finite Particle Number Approach to Relativistic Scattering Theory

Energy Technology Data Exchange (ETDEWEB)

Lindesay, James V

2001-05-11

We present integral equations for the scattering amplitudes of three scalar particles, using the Faddeev channel decomposition, which can be readily extended to any finite number of particles of any helicity. The solution of these equations, which have been demonstrated to be calculable, provide a non-perturbative way of obtaining relativistic scattering amplitudes for any finite number of particles that are Lorentz invariant, unitary, cluster decomposable and reduce unambiguously in the non-relativistic limit to the non-relativistic Faddeev equations. The aim of this program is to develop equations which explicitly depend upon physically observable input variables, and do not require ''renormalization'' or ''dressing'' of these parameters to connect them to the boundary states.

Effects of the particle-number projection on the isovector pairing energy

International Nuclear Information System (INIS)

Allal, N.H.; Fellah, M.; Oudih, M.R.; Benhamouda, N.

2006-01-01

The usual neutron-proton BCS wave function is simultaneously projected on both the good neutron and proton numbers using a discrete projection operator. The projected energy of the system is deduced as a limit of rapidly convergent sequence. It is numerically studied for the N=Z nuclei of which ''experimental'' pairing gaps may be deduced from the experimental odd-even mass differences. It then appears that the particle-number fluctuation effect is even more important than in the case of pairing between like-particles. (orig.)

Reynolds number and settling velocity influence for finite-release particle-laden gravity currents in a basin

Science.gov (United States)

Francisco, E. P.; Espath, L. F. R.; Laizet, S.; Silvestrini, J. H.

2018-01-01

Three-dimensional highly resolved Direct Numerical Simulations (DNS) of particle-laden gravity currents are presented for the lock-exchange problem in an original basin configuration, similar to delta formation in lakes. For this numerical study, we focus on gravity currents over a flat bed for which density differences are small enough for the Boussinesq approximation to be valid. The concentration of particles is described in an Eulerian fashion by using a transport equation combined with the incompressible Navier-Stokes equations, with the possibility of particles deposition but no erosion nor re-suspension. The focus of this study is on the influence of the Reynolds number and settling velocity on the development of the current which can freely evolve in the streamwise and spanwise direction. It is shown that the settling velocity has a strong influence on the spatial extent of the current, the sedimentation rate, the suspended mass and the shape of the lobe-and-cleft structures while the Reynolds number is mainly affecting the size and number of vortical structures at the front of the current, and the energy budget.

On quantum statistics for ensembles with a finite number of particles

International Nuclear Information System (INIS)

Trifonov, Evgenii D

2011-01-01

The well-known Bose-Einstein and Fermi-Dirac quantum distributions can be considered as stationary solutions of kinetic equations for the mean occupation numbers in an ideal gas of an arbitrary finite number of identical particles. (methodological notes)

Baryon number fluctuations in quasi-particle model

Energy Technology Data Exchange (ETDEWEB)

Zhao, Ameng [Southeast University Chengxian College, Department of Foundation, Nanjing (China); Luo, Xiaofeng [Central China Normal University, Key Laboratory of Quark and Lepton Physics (MOE), Institute of Particle Physics, Wuhan (China); Zong, Hongshi [Nanjing University, Department of Physics, Nanjing (China); Joint Center for Particle, Nuclear Physics and Cosmology, Nanjing (China); Institute of Theoretical Physics, CAS, State Key Laboratory of Theoretical Physics, Beijing (China)

2017-04-15

Baryon number fluctuations are sensitive to the QCD phase transition and the QCD critical point. According to the Feynman rules of finite-temperature field theory, we calculated various order moments and cumulants of the baryon number distributions in the quasi-particle model of the quark-gluon plasma. Furthermore, we compared our results with the experimental data measured by the STAR experiment at RHIC. It is found that the experimental data can be well described by the model for the colliding energies above 30 GeV and show large discrepancies at low energies. This puts a new constraint on the qQGP model and also provides a baseline for the QCD critical point search in heavy-ion collisions at low energies. (orig.)

In situ formation and spatial variability of particle number concentration in a European megacity

Science.gov (United States)

Pikridas, M.; Sciare, J.; Freutel, F.; Crumeyrolle, S.; von der Weiden-Reinmüller, S.-L.; Borbon, A.; Schwarzenboeck, A.; Merkel, M.; Crippa, M.; Kostenidou, E.; Psichoudaki, M.; Hildebrandt, L.; Engelhart, G. J.; Petäjä, T.; Prévôt, A. S. H.; Drewnick, F.; Baltensperger, U.; Wiedensohler, A.; Kulmala, M.; Beekmann, M.; Pandis, S. N.

2015-09-01

Ambient particle number size distributions were measured in Paris, France, during summer (1-31 July 2009) and winter (15 January to 15 February 2010) at three fixed ground sites and using two mobile laboratories and one airplane. The campaigns were part of the Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation (MEGAPOLI) project. New particle formation (NPF) was observed only during summer on approximately 50 % of the campaign days, assisted by the low condensation sink (about 10.7 ± 5.9 × 10-3 s-1). NPF events inside the Paris plume were also observed at 600 m altitude onboard an aircraft simultaneously with regional events identified on the ground. Increased particle number concentrations were measured aloft also outside of the Paris plume at the same altitude, and were attributed to NPF. The Paris plume was identified, based on increased particle number and black carbon concentration, up to 200 km away from the Paris center during summer. The number concentration of particles with diameters exceeding 2.5 nm measured on the surface at the Paris center was on average 6.9 ± 8.7 × 104 and 12.1 ± 8.6 × 104 cm-3 during summer and winter, respectively, and was found to decrease exponentially with distance from Paris. However, further than 30 km from the city center, the particle number concentration at the surface was similar during both campaigns. During summer, one suburban site in the NE was not significantly affected by Paris emissions due to higher background number concentrations, while the particle number concentration at the second suburban site in the SW increased by a factor of 3 when it was downwind of Paris.

Single particle aerosol mass spectrometry of coal combustion particles associated with high lung cancer rates in Xuanwei and Fuyuan, China.

Science.gov (United States)

Lu, Senlin; Tan, Zhengying; Liu, Pinwei; Zhao, Hui; Liu, Dingyu; Yu, Shang; Cheng, Ping; Win, Myat Sandar; Hu, Jiwen; Tian, Linwei; Wu, Minghong; Yonemochi, Shinich; Wang, Qingyue

2017-11-01

Coal combustion particles (CCPs) are linked to the high incidence of lung cancer in Xuanwei and in Fuyuan, China, but studies on the chemical composition of the CCPs are still limited. Single particle aerosol mass spectrometry (SPAMS) was recently developed to measure the chemical composition and size of single particles in real-time. In this study, SPAMS was used to measure individual combustion particles emitted from Xuanwei and Fuyuan coal samples and the results were compared with those by ICP-MS and transmission electron microscopy (TEM). The total of 38,372 particles mass-analyzed by SPAMS can be divided into 9 groups based on their chemical composition and their number percentages: carbonaceous, Na-rich, K-rich, Al-rich, Fe-rich, Si-rich, Ca-rich, heavy metal-bearing, and PAH-bearing particles. The carbonaceous and PAH-bearing particles are enriched in the size range below 0.56 μm, Fe-bearing particles range from 0.56 to 1.0 μm in size, and heavy metals such as Ti, V, Cr, Cu, Zn, and Pb have diameters below 1 μm. The TEM results show that the particles from Xuanwei and Fuyuan coal combustion can be classified into soot aggregates, Fe-rich particles, heavy metal containing particles, and mineral particles. Non-volatile particles detected by SPAMS could also be observed with TEM. The number percentages by SPAMS also correlate with the mass concentrations measured by ICP-MS. Our results could provide valuable insight for understanding high lung cancer incidence in the area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Coupled force-balance and particle-occupation rate equations for high-field electron transport

International Nuclear Information System (INIS)

Lei, X. L.

2008-01-01

It is pointed out that in the framework of balance-equation approach, the coupled force-balance and particle-occupation rate equations can be used as a complete set of equations to determine the high-field transport of semiconductors in both strong and weak electron-electron interaction limits. We call to attention that the occupation rate equation conserves the total particle number and maintains the energy balance of the relative electron system, and there is no need to introduce any other term in it. The addition of an energy-drift term in the particle-occupation rate equation [Phys. Rev. B 71, 195205 (2005)] is physically inadequate for the violation of the total particle-number conservation and the energy balance. It may lead to a substantial unphysical increase of the total particle number by the application of a dc electric field

Number concentrations of solid particles from the spinning top aerosol generator

International Nuclear Information System (INIS)

Mitchell, J.P.

1983-02-01

A spinning top aerosol generator has been used to generate monodisperse methylene blue particles in the size range from 0.6 to 6 μm. The number concentrations of these aerosols have been determined by means of an optical particle counter and compared with the equivalent measurements obtained by filter collection and microscopy. (author)

Number and mass analysis of particles emitted by aircraft engine

Directory of Open Access Journals (Sweden)

Jasiński Remigiusz

2017-01-01

Full Text Available Exhaust emissions from aircraft is a complex issue because of the limited possibility of measurements in flight conditions. Most of the studies on this subject were performed on the basis of stationary test. Engine certification data is used to calculate total emissions generated by air transport. However, it doesnt provide any information about the local effects of air traffic. The main threat to local communities is particulate matter emissions, which adversely affects human health. Emissions from air transport affect air quality, particularly in the vicinity of the airports; it also contributes to the greenhouse effect. The article presents the measurement results of the concentration and size distribution of particles emitted during aircraft landing operation. Measurements were carried out during the landings of aircraft at a civilian airport. It was found that a single landing operation causes particle number concentration value increase of several ten-fold in a short period of time. Using aircraft engine certification data, the methodology for determination of the total number of particles emitted during a single landing operation was introduced.

Particle number fluctuations in the moment of inertia

International Nuclear Information System (INIS)

Allal, N.H.; Fellah, M.

1991-01-01

The nonphysical effects due to the false components introduced by the nonconservation of the particle number in the BCS states are eliminated in the theoretical values of the moment of inertia calculated by the microscopic cranking model. The states of the system are obtained by successive projections of the BCS states in the occupation number space. The moment of inertia appears then as a limit of a rapidly convergent sequence. The errors due to this false component have been numerically estimated and appear to be important both in the BCS states and in the matrix elements of the angular momentum. The predicted values of the moment of inertia satisfactorily reproduce the experimental data over a large number of nuclei within rare-earth and actinide regions with discrepancies ranging from 0.1% to 8%

Deposition of magnetite particles from high velocity water onto isothermal tubes

International Nuclear Information System (INIS)

Burrill, K.A.

1977-02-01

The deposition rate of magnetite particles from a high velocity water slurry onto isothermal metal tubes was measured. The effects of velocity (5 to 100 m/s), slurry concentration (200 to 1000 mg Fe/kg H 2 O), temperature (25 0 to 90 0 C), pH (4 to 10 at 25 0 C), and tube material (nickel, Zircaloy-4) on deposition rate were studied. The data are interpreted in terms of two steps in series for deposition: a mass transfer step followed by a deposition or inertial coasting step. Mass transfer of particles through the bulk water phase apparently limits the deposition of particles at high Reynolds number

Sub-micron particle number size distribution characteristics at two urban locations in Leicester

Science.gov (United States)

Hama, Sarkawt M. L.; Cordell, Rebecca L.; Kos, Gerard P. A.; Weijers, E. P.; Monks, Paul S.

2017-09-01

The particle number size distribution (PNSD) of atmospheric particles not only provides information about sources and atmospheric processing of particles, but also plays an important role in determining regional lung dose. Owing to the importance of PNSD in understanding particulate pollution two short-term campaigns (March-June 2014) measurements of sub-micron PNSD were conducted at two urban background locations in Leicester, UK. At the first site, Leicester Automatic Urban Rural Network (AURN), the mean number concentrations of nucleation, Aitken, accumulation modes, the total particles, equivalent black carbon (eBC) mass concentrations were 2002, 3258, 1576, 6837 # cm-3, 1.7 μg m-3, respectively, and at the second site, Brookfield (BF), were 1455, 2407, 874, 4737 # cm-3, 0.77 μg m-3, respectively. The total particle number was dominated by the nucleation and Aitken modes, with both consisting of 77%, and 81% of total number concentrations at AURN and BF sites, respectively. This behaviour could be attributed to primary emissions (traffic) of ultrafine particles and the temporal evolution of mixing layer. The size distribution at the AURN site shows bimodal distribution at 22 nm with a minor peak at 70 nm. The size distribution at BF site, however, exhibits unimodal distribution at 35 nm. This study has for the first time investigated the effect of Easter holiday on PNSD in UK. The temporal variation of PNSD demonstrated a good degree of correlation with traffic-related pollutants (NOX, and eBC at both sites). The meteorological conditions, also had an impact on the PNSD and eBC at both sites. During the measurement period, the frequency of NPF events was calculated to be 13.3%, and 22.2% at AURN and BF sites, respectively. The average value of formation and growth rates of nucleation mode particles were 1.3, and 1.17 cm-3 s-1 and 7.42, and 5.3 nm h-1 at AURN, and BF sites, respectively. It can suggested that aerosol particles in Leicester originate mainly

Thermodynamic identities and particle number fluctuations in weakly interacting Bose-Einstein condensates

Energy Technology Data Exchange (ETDEWEB)

Illuminati, Fabrizio [Institut fuer Physik, Universitaet Potsdam, Am Neuen Palais 10, D-14415, Potsdam (Germany); Dipartimento di Fisica, Universita di Salerno, and INFM, Unita di Salerno, I-84081 Baronissi SA (Italy); Navez, Patrick [Institut fuer Physik, Universitaet Potsdam, Am Neuen Palais 10, D-14415, Potsdam (Germany); Institute of Materials Science, Demokritos NCSR, POB 60228, 15310 Athens (Greece); Wilkens, Martin [Institut fuer Physik, Universitaet Potsdam, Am Neuen Palais 10, D-14415, Potsdam (Germany)

1999-08-14

We derive exact thermodynamic identities relating the average number of condensed atoms and the root-mean-square fluctuations determined in different statistical ensembles for the weakly interacting Bose gas confined in a box. This is achieved by introducing the concept of auxiliary partition functions for model Hamiltonians that do conserve the total number of particles. Exploiting such thermodynamic identities, we provide the first, completely analytical prediction of the microcanonical particle number fluctuations in the weakly interacting Bose gas. Such fluctuations, as a function of the volume V of the box are found to behave normally, in contrast with the anomalous scaling behaviour V{sup 4/3} of the fluctuations in the ideal Bose gas. (author). Letter-to-the-editor.

Contribution from indoor sources to particle number and mass concentrations in residential houses

Science.gov (United States)

He, Congrong; Morawska, Lidia; Hitchins, Jane; Gilbert, Dale

As part of a large study investigating indoor air in residential houses in Brisbane, Australia, the purpose of this work was to quantify emission characteristics of indoor particle sources in 15 houses. Submicrometer particle number and approximation of PM 2.5 concentrations were measured simultaneously for more than 48 h in the kitchen of all the houses by using a condensation particle counter (CPC) and a photometer (DustTrak), respectively. In addition, characterizations of particles resulting from cooking conducted in an identical way in all the houses were measured by using a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS) and a DustTrak. All the events of elevated particle concentrations were linked to indoor activities using house occupants diary entries, and catalogued into 21 different types of indoor activities. This enabled quantification of the effect of indoor sources on indoor particle concentrations as well as quantification of emission rates from the sources. For example, the study found that frying, grilling, stove use, toasting, cooking pizza, cooking, candle vaporizing eucalyptus oil and fan heater use, could elevate the indoor submicrometer particle number concentration levels by more than five times, while PM 2.5 concentrations could be up to 3, 30 and 90 times higher than the background levels during smoking, frying and grilling, respectively.

Number Size Distribution of Ambient Particles in a Typical Urban Site: The First Polish Assessment Based on Long-Term (9 Months Measurements

Directory of Open Access Journals (Sweden)

Krzysztof Klejnowski

2013-01-01

Full Text Available This work presents results from the long-term measurements of particle number carried out at an urban background station in Zabrze, Poland. Ambient particles with aerodynamic diameters of between 28 nm and 10 μm were investigated by means of a DEKATI thirteen-stage electrical low pressure impactor (ELPI. The particle number-size distribution was bimodal, whilst its density function had the local maxima in the aerodynamic diameter intervals 0.056–0.095 μm and 0.157–0.263 μm. The average particle number in winter was nearly twice as high as in summer. The greatest number concentrations in winter were those of the particles with diameters of between 0.617 and 2.41 μm, that is, the anthropogenic particles from fossil fuel combustion. Approximately 99% of the particles observed in Zabrze had aerodynamic diameters ≤1 μm—they may have originated from the combustion of biomass, liquid, and gaseous fuels in domestic stoves or in car engines. The daily variation of particle number was similar for both seasons—the highest values were observed in the morning (traffic rush hour and in the afternoon/late evening (traffic and house heating emissions. An additional maximum (0.028–0.056 μm observed in the early afternoon in summer was due to the intensive formation of new PM particles from gas precursors.

Enumeration of an extremely high particle-to-PFU ratio for Varicella-zoster virus.

Science.gov (United States)

Carpenter, John E; Henderson, Ernesto P; Grose, Charles

2009-07-01

Varicella-zoster virus (VZV) is renowned for its low titers. Yet investigations to explore the low infectivity are hampered by the fact that the VZV particle-to-PFU ratio has never been determined with precision. Herein, we accomplish that task by applying newer imaging technology. More than 300 images were taken of VZV-infected cells on 4 different samples at high magnification. We enumerated the total number of viral particles within 25 cm(2) of the infected monolayer at 415 million. Based on these numbers, the VZV particle:PFU ratio was approximately 40,000:1 for a cell-free inoculum.

Simultaneous measurements of particle number size distributions at ground level and 260 m on a meteorological tower in urban Beijing, China

Science.gov (United States)

Du, Wei; Zhao, Jian; Wang, Yuying; Zhang, Yingjie; Wang, Qingqing; Xu, Weiqi; Chen, Chen; Han, Tingting; Zhang, Fang; Li, Zhanqing; Fu, Pingqing; Li, Jie; Wang, Zifa; Sun, Yele

2017-06-01

Despite extensive studies into the characterization of particle number size distributions at ground level, real-time measurements above the urban canopy in the megacity of Beijing have never been performed to date. Here we conducted the first simultaneous measurements of size-resolved particle number concentrations at ground level and 260 m in urban Beijing from 22 August to 30 September. Our results showed overall similar temporal variations in number size distributions between ground level and 260 m, yet periods with significant differences were also observed. Particularly, accumulation-mode particles were highly correlated (r2 = 0. 85) at the two heights, while Aitken-mode particles presented more differences. Detailed analysis suggests that the vertical differences in number concentrations strongly depended on particle size, and particles with a mobility diameter between 100 and 200 nm generally showed higher concentrations at higher altitudes. Particle growth rates and condensation sinks were also calculated, which were 3.2 and 3.6 nm h-1, and 2.8 × 10-2 and 2.9 × 10-2 s-1, at ground level and 260 m, respectively. By linking particle growth with aerosol composition, we found that organics appeared to play an important role in the early stage of the growth (09:00-12:00 LT) while sulfate was also important during the later period. Positive matrix factorization of size-resolved number concentrations identified three common sources at ground level and 260 m, including a factor associated with new particle formation and growth events (NPEs), and two secondary factors that represent photochemical processing and regional transport. Cooking emission was found to have a large contribution to small particles and showed much higher concentration at ground level than 260 m in the evening. These results imply that investigation of NPEs at ground level in megacities needs to consider the influences of local cooking emissions. The impacts of regional emission controls on

Pairing vibrational and isospin rotational states in a particle number and isospin projected generator coordinate method

International Nuclear Information System (INIS)

Chen, H.T.; Muether, H.; Faessler, A.

1978-01-01

Pairing vibrational and isospin rotational states are described in different approximations based on particle number and isospin projected, proton-proton, neutron-neutron and proton-neutron pairing wave functions and on the generator coordinate method (GCM). The investigations are performed in models for which an exact group theoretical solution exists. It turns out that a particle number and isospin projection is essential to yield a good approximation to the ground state or isospin yrast state energies. For strong pairing correlations (pairing force constant equal to the single-particle level distance) isospin cranking (-ωTsub(x)) yields with particle number projected pairing wave function also good agreement with the exact energies. GCM wave functions generated by particle number and isospin projected BCS functions with different amounts of pairing correlations yield for the lowest T=0 and T=2 states energies which are practically indistinguishable from the exact solutions. But even the second and third lowest energies of charge-symmetric states are still very reliable. Thus it is concluded that also in realistic cases isospin rotational and pairing vibrational states may be described in the framework of the GCM method with isospin and particle number projected generating wave functions. (Auth.)

Emulsifier-free emulsion polymerization produces highly charged, monodisperse particles for near infrared photonic crystals.

Science.gov (United States)

Reese, Chad E; Asher, Sanford A

2002-04-01

We have developed emulsifier-free, emulsion polymerization recipes for the synthesis of highly charged, monodisperse latex particles of diameters between 500 and 1100 nm. These latexes consist of poly[styrene-(co-2-hydroxyethyl methacrylate)] spherical particles whose surfaces are functionalized with sulfate and carboxylic acid groups. These highly charged, monodisperse particles readily self-assemble into robust, three-dimensionally ordered crystalline colloidal array photonic crystals that Bragg diffract light in the near infrared spectral region. By altering the particle number density, the diffraction wavelength can be tuned from approximately 1000 to approximately 4000 nm.

Summertime observations of elevated levels of ultrafine particles in the high Arctic marine boundary layer

Science.gov (United States)

Burkart, Julia; Willis, Megan D.; Bozem, Heiko; Thomas, Jennie L.; Law, Kathy; Hoor, Peter; Aliabadi, Amir A.; Köllner, Franziska; Schneider, Johannes; Herber, Andreas; Abbatt, Jonathan P. D.; Leaitch, W. Richard

2017-05-01

Motivated by increasing levels of open ocean in the Arctic summer and the lack of prior altitude-resolved studies, extensive aerosol measurements were made during 11 flights of the NETCARE July 2014 airborne campaign from Resolute Bay, Nunavut. Flights included vertical profiles (60 to 3000 m above ground level) over open ocean, fast ice, and boundary layer clouds and fogs. A general conclusion, from observations of particle numbers between 5 and 20 nm in diameter (N5 - 20), is that ultrafine particle formation occurs readily in the Canadian high Arctic marine boundary layer, especially just above ocean and clouds, reaching values of a few thousand particles cm-3. By contrast, ultrafine particle concentrations are much lower in the free troposphere. Elevated levels of larger particles (for example, from 20 to 40 nm in size, N20 - 40) are sometimes associated with high N5 - 20, especially over low clouds, suggestive of aerosol growth. The number densities of particles greater than 40 nm in diameter (N > 40) are relatively depleted at the lowest altitudes, indicative of depositional processes that will lower the condensation sink and promote new particle formation. The number of cloud condensation nuclei (CCN; measured at 0.6 % supersaturation) are positively correlated with the numbers of small particles (down to roughly 30 nm), indicating that some fraction of these newly formed particles are capable of being involved in cloud activation. Given that the summertime marine Arctic is a biologically active region, it is important to better establish the links between emissions from the ocean and the formation and growth of ultrafine particles within this rapidly changing environment.

Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai.

Science.gov (United States)

Wang, Xuemei; Chen, Jianmin; Cheng, Tiantao; Zhang, Renyi; Wang, Xinming

2014-09-01

The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe (visibilitysmog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15μm(3)/cm(3) and 949, 649, 206μm(2)/cm(3), respectively. As haze events got more severe, the number concentration of particles smaller than 50nm decreased, but the particles of 50-200nm and 0.5-1μm increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4(+), SO4(2-) and NO3(-) increased greatly, followed by Na(+), K(+), Ca(2+) and Cl(-). These ions were very different in size-resolved particles during haze and photochemical smog episodes. Copyright © 2014. Published by Elsevier B.V.

Rapid, topology-based particle tracking for high-resolution measurements of large complex 3D motion fields.

Science.gov (United States)

Patel, Mohak; Leggett, Susan E; Landauer, Alexander K; Wong, Ian Y; Franck, Christian

2018-04-03

Spatiotemporal tracking of tracer particles or objects of interest can reveal localized behaviors in biological and physical systems. However, existing tracking algorithms are most effective for relatively low numbers of particles that undergo displacements smaller than their typical interparticle separation distance. Here, we demonstrate a single particle tracking algorithm to reconstruct large complex motion fields with large particle numbers, orders of magnitude larger than previously tractably resolvable, thus opening the door for attaining very high Nyquist spatial frequency motion recovery in the images. Our key innovations are feature vectors that encode nearest neighbor positions, a rigorous outlier removal scheme, and an iterative deformation warping scheme. We test this technique for its accuracy and computational efficacy using synthetically and experimentally generated 3D particle images, including non-affine deformation fields in soft materials, complex fluid flows, and cell-generated deformations. We augment this algorithm with additional particle information (e.g., color, size, or shape) to further enhance tracking accuracy for high gradient and large displacement fields. These applications demonstrate that this versatile technique can rapidly track unprecedented numbers of particles to resolve large and complex motion fields in 2D and 3D images, particularly when spatial correlations exist.

Exotic highly ionising particles at the LHC

CERN Document Server

De Roeck, A; Mermod, P; Milstead, D; Sloan, T

2012-01-01

The experiments at the Large Hadron Collider (LHC) are able to discover or set limits on the production of exotic particles with TeV-scale masses possessing values of electric and/or magnetic charge such that they appear as highly ionising particles (HIPs). In this paper the sensitivity of the LHC experiments to HIP production is discussed in detail. It is shown that a number of different detection methods are required to investigate as fully as possible the charge-mass range. These include direct detection as the HIPs pass through detectors and, in the case of magnetically charged objects, the so-called induction method with which monopoles which stop in accelerator and detector material could be observed. The benefit of using complementary approaches to HIP detection is discussed.

Asymptotic expansion in the local limit theorem for the particle number in the grand canonical ensemble

International Nuclear Information System (INIS)

Pogosian, S.

1981-01-01

It is known that in the grand canonical ensemble (for the case of small density of particles) the fluctuations (approximately mod(Λ)sup(1/2)) in the particle number have an asymptotic normal distribution as Λ→infinity. A similar statement holds for the distribution of the particle number in a bounded domain evaluated with respect to the limiting Gibbs distribution. The author obtains an asymptotic expansion in the local limit theorem for the particle number in the grand canonical ensemble, by using the asymptotic expansion of the grand canonical partition function. The coefficients of this expansion are not constants but depend on the form of the domain Λ. More precisely, they are constant up to a correction which is small (for large Λ). The author obtains an explicit form for the second term of the asymptotic expansion in the local limit theorem for the particle number, and also gets the first correction terms for the coefficients of this expansion. (Auth.)

Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation

Science.gov (United States)

Spracklen, D. V.; Carslaw, K. S.; Merikanto, J.; Mann, G. W.; Reddington, C. L.; Pickering, S.; Ogren, J. A.; Andrews, E.; Baltensperger, U.; Weingartner, E.; Boy, M.; Kulmala, M.; Laakso, L.; Lihavainen, H.; Kivekäs, N.; Komppula, M.; Mihalopoulos, N.; Kouvarakis, G.; Jennings, S. G.; O'Dowd, C.; Birmili, W.; Wiedensohler, A.; Weller, R.; Gras, J.; Laj, P.; Sellegri, K.; Bonn, B.; Krejci, R.; Laaksonen, A.; Hamed, A.; Minikin, A.; Harrison, R. M.; Talbot, R.; Sun, J.

2010-05-01

We synthesised observations of total particle number (CN) concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300-2000 cm-3 in the marine boundary layer and free troposphere (FT) and 1000-10 000 cm-3 in the continental boundary layer (BL). Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2-10 greater than wintertime concentrations. We used these CN observations to evaluate primary and secondary sources of particle number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R2=0.46) but fail to explain the observed seasonal cycle (R2=0.1). The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=-88%) unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=-25%). Simulated CN concentrations in the continental BL were also biased low (NMB=-74%) unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J, proportional to gas-phase sulfuric acid concentration to the power one) or kinetic-type mechanism (J proportional to sulfuric acid to the power two) with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R2=0.3) than by increasing the number emission from primary anthropogenic sources (R2=0.18). The nucleation constants that resulted in best overall match between model and observed CN concentrations were consistent with values derived in previous studies from detailed case studies at individual sites. In our model, kinetic and activation

Contribution from the interaction Hamiltonian to the expectation value of particle number with the non-equilibrium quantum field theory

International Nuclear Information System (INIS)

Hotta, Ryuuichi; Morozumi, Takuya; Takata, Hiroyuki

2012-01-01

We develop the method analyzing particle number non-conserving phenomena with non-equilibrium quantum field-theory. In this study, we consider a CP violating model with interaction Hamiltonian that breaks particle number conservation. To derive the quantum Boltzmann equation for the particle number, we solve Schwinger-Dyson equation, which are obtained from two particle irreducible closed-time-path (2PI CTP) effective action. In this calculation, we show the contribution from interaction Hamiltonian to the time evolution of expectation value of particle number.

Nuclear fragmentation and the number of particle tracks in tissue

International Nuclear Information System (INIS)

Ponomarev, A. L.; Cucinotta, F. A.

2006-01-01

For high energy nuclei, the number of particle tracks per cell is modified by local nuclear reactions that occur, with large fluctuations expected for heavy ion tracks. Cells near the interaction site of a reaction will experience a much higher number of tracks than estimated by the average fluence. Two types of reaction products are possible and occur in coincidence; projectile fragments, which generally have smaller charge and similar velocity to that of the projectile, and target fragments, which are produced from the fragmentation of the nuclei of water atoms or other cellular constituents with low velocity. In order to understand the role of fragmentation in biological damage a new model of human tissue irradiated by heavy ions was developed. A box of the tissue is modelled with periodic boundary conditions imposed, which extrapolates the technique to macroscopic volumes of tissue. The cross sections for projectile and target fragmentation products are taken from the quantum multiple scattering fragmentation code previously developed at NASA Johnson Space Center. Statistics of fragmentation pathways occurring in a cell monolayer, as well as in a small volume of 10 x 10 x 10 cells are given. A discussion on approaches to extend the model to describe spatial distributions of inactivated or other cell damage types, as well as highly organised tissues of multiple cell types, is presented. (authors)

Inward particle transport at high collisionality in the Experimental Advanced Superconducting Tokamak

International Nuclear Information System (INIS)

Wang, G. Q.; Ma, J.; Weiland, J.; Zang, Q.

2013-01-01

We have made the first drift wave study of particle transport in the Experimental Advanced Superconducting Tokamak (Wan et al., Nucl. Fusion 49, 104011 (2009)). The results reveal that collisions make the particle flux more inward in the high collisionality regime. This can be traced back to effects that are quadratic in the collision frequency. The particle pinch is due to electron trapping which is not very efficient in the high collisionality regime so the approach to equilibrium is slow. We have included also the electron temperature gradient (ETG) mode to give the right electron temperature gradient, since the Trapped Electron Mode (TE mode) is weak in this regime. However, at the ETG mode number ions are Boltzmann distributed so the ETG mode does not give particle transport

Single-particle characterization of the high-Arctic summertime aerosol

Directory of Open Access Journals (Sweden)

B. Sierau

2014-07-01

unknown composition and source. In general, the study suffered from low counting statistics due to the overall small number of particles found in this pristine environment, the small sizes of the prevailing aerosol below the detection limit of the ATOFMS, and its low hit rate. To our knowledge, this study reports on the first in situ single-particle mass-spectrometric measurements in the marine boundary layer of the high-Arctic pack ice region.

Single-particle characterization of the high-Arctic summertime aerosol

Science.gov (United States)

Sierau, B.; Chang, R. Y.-W.; Leck, C.; Paatero, J.; Lohmann, U.

2014-07-01

and source. In general, the study suffered from low counting statistics due to the overall small number of particles found in this pristine environment, the small sizes of the prevailing aerosol below the detection limit of the ATOFMS, and its low hit rate. To our knowledge, this study reports on the first in situ single-particle mass-spectrometric measurements in the marine boundary layer of the high-Arctic pack ice region.

Single-particle characterization of the High Arctic summertime aerosol

Science.gov (United States)

Sierau, B.; Chang, R. Y.-W.; Leck, C.; Paatero, J.; Lohmann, U.

2014-01-01

and source. In general, the study suffered from low counting statistics due to the overall small number of particles found in this pristine environment, the small sizes of the prevailing aerosol below the detection limit of the ATOFMS and its low hit rate. To our knowledge, this study reports on the first in-situ single-particle mass spectrometric measurements in the marine boundary layer of the High-Arctic pack-ice region.

The deposition of magnetite particles from high velocity water onto isothermal tubes

International Nuclear Information System (INIS)

Burrill, K.A.

1977-02-01

The deposition rate of magnetite particles from a high velocity water slurry onto isothermal metal tubes was measured. The effects of velocity (5 to 100 m/s), slurry concentration (200 to 1000 mg Fe/kg H 2 O), temperature (25 to 90 deg C), pH (4 to 10 at 25 deg C), and tube material (nickel, Zircaloy-4) on deposition rate were studied. The data are interpreteω in terms of two steps in series for deposition: a mass transfer step followed by a deposition or ''inertial coasting'' step. Mass transfer of particles through the bulk water phase apparently limits the deposition of particles at high Reynolds number (10 5 ). (author)

High-PT Physics with Identified Particles

Energy Technology Data Exchange (ETDEWEB)

Fries, R.; Liu, W.

2009-11-09

The suppression of high-P{sub T} particles in heavy ion collisions was one of the key discoveries at the Relativistic Heavy Ion Collider. This is usually parameterized by the average rate of momentum-transfer squared to this particle, {cflx q}. Here we argue that measurements of identified particles at high P{sub T} can lead to complementary information about the medium. The leading particle of a jet can change its identity through interactions with the medium. Tracing such flavor conversions could allow us to constrain the mean free path. Here we review the basic concepts of flavor conversions and discuss applications to particle ratios and elliptic flow. We make a prediction that strangeness is enhanced at high P{sub T} at RHIC energies while its elliptic flow is suppressed.

Dragon kings of the deep sea: marine particles deviate markedly from the common number-size spectrum.

Science.gov (United States)

Bochdansky, Alexander B; Clouse, Melissa A; Herndl, Gerhard J

2016-03-04

Particles are the major vector for the transfer of carbon from the upper ocean to the deep sea. However, little is known about their abundance, composition and role at depths greater than 2000 m. We present the first number-size spectrum of bathy- and abyssopelagic particles to a depth of 5500 m based on surveys performed with a custom-made holographic microscope. The particle spectrum was unusual in that particles of several millimetres in length were almost 100 times more abundant than expected from the number spectrum of smaller particles, thereby meeting the definition of "dragon kings." Marine snow particles overwhelmingly contributed to the total particle volume (95-98%). Approximately 1/3 of the particles in the dragon-king size domain contained large amounts of transparent exopolymers with little ballast, which likely either make them neutrally buoyant or cause them to sink slowly. Dragon-king particles thus provide large volumes of unique microenvironments that may help to explain discrepancies in deep-sea biogeochemical budgets.

States with a great number of quasi-particles in even lead isotopes

International Nuclear Information System (INIS)

Auger, G.; Manfredi, V.R.

1975-01-01

The even lead isotopes have been studied by means of a spectral distribution calculation in the sub-spaces defined by their number of quasi-particles. The comparison with results obtained in the thin isotopes shows that the overlap of the various sub-spaces is strongly dependent on the residual interaction used; namely, states with a great number of quasi-particles do exist in the low energy part of the spectra. The problem of spurious states implied by this method, states responsible for an over-estimation of the sub-space coupling, is treated and various corrections are proposed for the dimensions as well as for the centroids and widths of the sub-spaces [fr

Primary standard for the number concentration of liquid-borne particles in the 10 to 20 µm diameter range

Science.gov (United States)

Sakaguchi, T.; Ehara, K.

2011-02-01

The national primary standard for the number concentration of liquid-borne particles in the 10 to 20 µm diameter range has been developed at the National Institute of Advanced Industrial Science and Technology (AIST), Japan. The standard consists of a total number counting type flow cytometer (T-FCM) and an electronic balance. The T-FCM is a commercial flow cytometer modified so that the total number of particles in an aqueous suspension sampled in a test tube can be counted, and the electronic balance is used to determine the mass of the suspension. This standard is intended to be used for calibrating commercial standard suspensions of monodisperse polystyrene latex (PSL) particles. The measurand in the calibration is the mass-based number concentration (the particle number in a unit mass of a suspension), and the calibration capability covers the concentration range from 5 × 102 to 2 × 106 particles g-1. When the concentration of the suspension is higher than 2 × 103 particles g-1, the suspension is first diluted to about 1 × 103 particles g-1 to suppress the coincidence loss in particle counting by the T-FCM. The validity of the calibration with the T-FCM was examined by comparison with an independent method in which a scanning electron microscope (SEM) was used to determine the number concentration of particles deposited on a silicon wafer. For a suspension of 10 µm PSL particles with a concentration of approximately 1 × 106 particles g-1, the concentration values determined by the T-FCM and SEM methods were 1.042 × 106 and 1.035 × 106 particles g-1, respectively: The difference was less than 0.7%. The relative expanded uncertainty of the measurement by the T-FCM method with the coverage factor k = 2 was 4.4%.

Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation

Directory of Open Access Journals (Sweden)

D. V. Spracklen

2010-05-01

Full Text Available We synthesised observations of total particle number (CN concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300–2000 cm⁻³ in the marine boundary layer and free troposphere (FT and 1000–10 000 cm⁻³ in the continental boundary layer (BL. Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2–10 greater than wintertime concentrations. We used these CN observations to evaluate primary and secondary sources of particle number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R²=0.46 but fail to explain the observed seasonal cycle (R²=0.1. The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=−88% unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=−25%. Simulated CN concentrations in the continental BL were also biased low (NMB=−74% unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J, proportional to gas-phase sulfuric acid concentration to the power one or kinetic-type mechanism (J proportional to sulfuric acid to the power two with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R²=0.3 than by increasing the number emission from primary anthropogenic sources (R²=0.18. The nucleation constants that resulted in best overall match between model and observed CN concentrations were

Aerosol and NOx emission factors and submicron particle number size distributions in two road tunnels with different traffic regimes

Directory of Open Access Journals (Sweden)

D. Imhof

2006-01-01

Full Text Available Measurements of aerosol particle number size distributions (18–700 nm, mass concentrations (PM2.5 and PM10 and NOx were performed in the Plabutsch tunnel, Austria, and in the Kingsway tunnel, United Kingdom. These two tunnels show different characteristics regarding the roadway gradient, the composition of the vehicle fleet and the traffic frequency. The submicron particle size distributions contained a soot mode in the diameter range D=80–100 nm and a nucleation mode in the range of D=20–40 nm. In the Kingsway tunnel with a significantly lower particle number and volume concentration level than in the Plabutsch tunnel, a clear diurnal variation of nucleation and soot mode particles correlated to the traffic density was observed. In the Plabutsch tunnel, soot mode particles also revealed a diurnal variation, whereas no substantial variation was found for the nucleation mode particles. During the night a higher number concentration of nucleation mode particles were measured than soot mode particles and vice versa during the day. In this tunnel with very high soot emissions during daytime due to the heavy-duty vehicle (HDV share of 18% and another 40% of diesel driven light-duty vehicles (LDV semivolatile species condense on the pre-existing soot surface area rather than forming new particles by homogeneous nucleation. With the low concentration of soot mode particles in the Kingsway tunnel, also the nucleation mode particles exhibit a diurnal variation. From the measured parameters real-world traffic emission factors were estimated for the whole vehicle fleet as well as differentiated into the two categories LDV and HDV. In the particle size range D=18–700 nm, each vehicle of the mixed fleet emits (1.50±0.08×1014 particles km-1 (Plabutsch and (1.26±0.10×1014 particles km-1 (Kingsway, while particle volume emission factors of 0.209±0.008 cm3 km-1 and 0.036±0.004 cm3 km-1, respectively, were obtained. PM1 emission factors of 104±4 mg

Quantum particle-number fluctuations in a two-component Bose gas in a double-well potential

International Nuclear Information System (INIS)

Zin, Pawel; Oles, Bartlomiej; Sacha, Krzysztof

2011-01-01

A two-component Bose gas in a double-well potential with repulsive interactions may undergo a phase separation transition if the interspecies interactions outweigh the intraspecies ones. We analyze the transition in the strong interaction limit within the two-mode approximation. Numbers of particles in each potential well are equal and constant. However, at the transition point, the ground state of the system reveals huge fluctuations of numbers of particles belonging to the different gas components; that is, the probability for observation of any mixture of particles in each potential well becomes uniform.

Interpretation of quarks having fractional quantum numbers as structural quasi-particles by means of the composite model with integral quantum numbers

International Nuclear Information System (INIS)

Tyapkin, A.A.

1976-01-01

The problem is raised on the interpretation of quarks having fractional quantum numbers as structural quasi-particles. A new composite model is proposed on the basis of the fundamental triplet representation of fermions having integral quantum numbers

Uncertainty in particle number modal analysis during transient operation of compressed natural gas, diesel, and trap-equipped diesel transit buses.

Science.gov (United States)

Holmén, Britt A; Qu, Yingge

2004-04-15

monitor particle emissions with high-resolution real-time instruments and account for the operating regime of the vehicle using time-series analysis to develop predictive number emissions models.

Quasi-particle and collective magnetism: Rotation, pairing and blocking in high-K isomers

International Nuclear Information System (INIS)

Stone, N.J.; Stone, J.R.; Walker, P.M.; Bingham, C.R.

2013-01-01

For the first time, a wide range of collective magnetic g-factors g R , obtained from a novel analysis of experimental data for multi-quasi-particle configurations in high-K isomers, is shown to exhibit a striking systematic variation with the relative number of proton and neutron quasi-particles, N p −N n . Using the principle of additivity, the quasi-particle contribution to magnetism in high-K isomers of Lu–Re, Z=71–75, has been estimated. Based on these estimates, band-structure branching ratio data are used to explore the behavior of the collective contribution as the number and proton/neutron nature (N p , N n ), of the quasi-particle excitations, change. Basic ideas of pairing, its quenching by quasi-particle excitation and the consequent changes to moment of inertia and collective magnetism are discussed. Existing model calculations do not reproduce the observed g R variation adequately. The paired superfluid system of nucleons in these nuclei, and their excitations, present properties of general physics interest. The new-found systematic behavior of g R in multi-quasi-particle excitations of this unique system, showing variation from close to zero for multi-neutron states to above 0.5 for multi-proton states, opens a fresh window on these effects and raises the important question of just which nucleons contribute to the ‘collective’ properties of these nuclei

Number size distribution of fine and ultrafine fume particles from various welding processes.

Science.gov (United States)

Brand, Peter; Lenz, Klaus; Reisgen, Uwe; Kraus, Thomas

2013-04-01

Studies in the field of environmental epidemiology indicate that for the adverse effect of inhaled particles not only particle mass is crucial but also particle size is. Ultrafine particles with diameters below 100 nm are of special interest since these particles have high surface area to mass ratio and have properties which differ from those of larger particles. In this paper, particle size distributions of various welding and joining techniques were measured close to the welding process using a fast mobility particle sizer (FMPS). It turned out that welding processes with high mass emission rates (manual metal arc welding, metal active gas welding, metal inert gas welding, metal inert gas soldering, and laser welding) show mainly agglomerated particles with diameters above 100 nm and only few particles in the size range below 50 nm (10 to 15%). Welding processes with low mass emission rates (tungsten inert gas welding and resistance spot welding) emit predominantly ultrafine particles with diameters well below 100 nm. This finding can be explained by considerably faster agglomeration processes in welding processes with high mass emission rates. Although mass emission is low for tungsten inert gas welding and resistance spot welding, due to the low particle size of the fume, these processes cannot be labeled as toxicologically irrelevant and should be further investigated.

Hierarchy of kissing numbers for exceptional Lie symmetry groups in high energy physics

International Nuclear Information System (INIS)

El Naschie, M.S.

2008-01-01

We are constructing a hierarchy of kissing numbers representing singular contact points of hyper-spheres in exceptional Lie symmetry groups lattice arrangement embedded in the 26 dimensional bosonic strings spacetime. That way we find a total number of points and dimensions equal to 548. This is 52 more than the order of E 8 E 8 of heterotic string theory and leads to the prediction of 69 elementary particles at an energy scale under 1 T. In other words, our mathematical model predicts nine more particles than what is currently experimentally known to exist in the standard model of high energy physics namely only 60. The result is thus in full agreement with all our previous theoretical findings

Effects of biodiesel, engine load and diesel particulate filter on nonvolatile particle number size distributions in heavy-duty diesel engine exhaust

Energy Technology Data Exchange (ETDEWEB)

Young, Li-Hao, E-mail: lhy@mail.cmu.edu.tw [Department of Occupational Safety and Health, China Medical University, 91, Hsueh-Shih Road, Taichung 40402, Taiwan (China); Liou, Yi-Jyun [Department of Occupational Safety and Health, China Medical University, 91, Hsueh-Shih Road, Taichung 40402, Taiwan (China); Cheng, Man-Ting [Department of Environmental Engineering, National Chung Hsing University, 250, Kuo-Kuang Road, Taichung 40254, Taiwan (China); Lu, Jau-Huai [Department of Mechanical Engineering, National Chung Hsing University, 250, Kuo-Kuang Road, Taichung 40254, Taiwan (China); Yang, Hsi-Hsien [Department of Environmental Engineering and Management, Chaoyang University of Technology, 168, Jifeng E. Road, Taichung 41349, Taiwan (China); Tsai, Ying I. [Department of Environmental Engineering and Science, Chia Nan University of Pharmacy and Science, 60, Sec. 1, Erh-Jen Road, Tainan 71710, Taiwan (China); Wang, Lin-Chi [Department of Chemical and Materials Engineering, Cheng Shiu University, 840, Chengcing Road, Kaohsiung 83347, Taiwan (China); Chen, Chung-Bang [Fuel Quality and Engine Performance Research, Refining and Manufacturing Research Institute, Chinese Petroleum Corporation, 217, Minsheng S. Road, Chiayi 60036, Taiwan (China); Lai, Jim-Shoung [Department of Occupational Safety and Health, China Medical University, 91, Hsueh-Shih Road, Taichung 40402, Taiwan (China)

2012-01-15

Highlights: Black-Right-Pointing-Pointer The effects of waste cooking oil biodiesel, engine load and DOC + DPF on nonvolatile particle size distributions in HDDE exhaust. Black-Right-Pointing-Pointer Increasing biodiesel blends cause slight decreases in the total particle number concentrations and negligible changes in size distributions. Black-Right-Pointing-Pointer Increasing load results in modest increases in both the total particle number concentrations and sizes. Black-Right-Pointing-Pointer The effects of semivolatile materials are strongest at idle, during which nonvolatile cores <16 nm were observed. Black-Right-Pointing-Pointer The DOC + DPF shows remarkable filtration efficiency for both the core and soot particles, irrespective of biodiesel blend and load. - Abstract: Diesel engine exhaust contains large numbers of submicrometer particles that degrade air quality and human health. This study examines the number emission characteristics of 10-1000 nm nonvolatile particles from a heavy-duty diesel engine, operating with various waste cooking oil biodiesel blends (B2, B10 and B20), engine loads (0%, 25%, 50% and 75%) and a diesel oxidation catalyst plus diesel particulate filter (DOC + DPF) under steady modes. For a given load, the total particle number concentrations (N{sub TOT}) decrease slightly, while the mode diameters show negligible changes with increasing biodiesel blends. For a given biodiesel blend, both the N{sub TOT} and mode diameters increase modestly with increasing load of above 25%. The N{sub TOT} at idle are highest and their size distributions are strongly affected by condensation and possible nucleation of semivolatile materials. Nonvolatile cores of diameters less than 16 nm are only observed at idle mode. The DOC + DPF shows remarkable filtration efficiency for both the core and soot particles, irrespective of the biodiesel blend and engine load under study. The N{sub TOT} post the DOC + DPF are comparable to typical ambient levels of

Nano-particle drag prediction at low Reynolds number using a direct Boltzmann-BGK solution approach

Science.gov (United States)

Evans, B.

2018-01-01

This paper outlines a novel approach for solution of the Boltzmann-BGK equation describing molecular gas dynamics applied to the challenging problem of drag prediction of a 2D circular nano-particle at transitional Knudsen number (0.0214) and low Reynolds number (0.25-2.0). The numerical scheme utilises a discontinuous-Galerkin finite element discretisation for the physical space representing the problem particle geometry and a high order discretisation for molecular velocity space describing the molecular distribution function. The paper shows that this method produces drag predictions that are aligned well with the range of drag predictions for this problem generated from the alternative numerical approaches of molecular dynamics codes and a modified continuum scheme. It also demonstrates the sensitivity of flow-field solutions and therefore drag predictions to the wall absorption parameter used to construct the solid wall boundary condition used in the solver algorithm. The results from this work has applications in fields ranging from diagnostics and therapeutics in medicine to the fields of semiconductors and xerographics.

High flux Particle Bed Reactor systems for rapid transmutation of actinides and long lived fission products

International Nuclear Information System (INIS)

Powell, J.; Ludewig, H.; Maise, G.; Steinberg, M.; Todosow, M.

1993-01-01

An initial assessment of several actinide/LLFP burner concepts based on the Particle Bed Reactor (PBR) is described. The high power density/flux level achievable with the PBR make it an attractive candidate for this application. The PBR based actinide burner concept also possesses a number of safety and economic benefits relative to other reactor based transmutation approaches including a low inventory of radionuclides, and high integrity, coated fuel particles which can withstand extremely high in temperatures while retaining virtually all fission products. In addition the reactor also posesses a number of ''engineered safety features,'' which, along with the use of high temperature capable materials further enhance its safety characteristics

Influence of isovector pairing and particle-number projection effects on spectroscopic factors for one-pair like-particle transfer reactions in proton-rich even-even nuclei

Science.gov (United States)

Benbouzid, Y.; Allal, N. H.; Fellah, M.; Oudih, M. R.

2018-04-01

Isovector neutron-proton (np) pairing and particle-number fluctuation effects on the spectroscopic factors (SF) corresponding to one-pair like-particle transfer reactions in proton-rich even-even nuclei are studied. With this aim, expressions of the SF corresponding to two-neutron stripping and two-proton pick-up reactions, which take into account the isovector np pairing effect, are established within the generalized BCS approach, using a schematic definition proposed by Chasman. Expressions of the same SF which strictly conserve the particle number are also established within the Sharp-BCS (SBCS) discrete projection method. In both cases, it is shown that these expressions generalize those obtained when only the pairing between like particles is considered. First, the formalism is tested within the Richardson schematic model. Second, it is applied to study even-even proton-rich nuclei using the single-particle energies of a Woods-Saxon mean-field. In both cases, it is shown that the np pairing effect and the particle-number projection effect on the SF values are important, particularly in N = Z nuclei, and must then be taken into account.

Elementary particles. 2

International Nuclear Information System (INIS)

Ranft, G.; Ranft, J.

1977-01-01

In this part the subject is covered under the following headings, methods for producing high-energy particles; interaction of high-energy particles with matter; methods for the detection of high-energy particles; symmetry properties and conservation laws; quantum number and selection rules; theorem of scattering behaviour at asymptotically high energies; statistical methods in elementary particle physics; interaction of high-energy particles with nuclei; relations of high-energy physics to other branches of science and its response to engineering. Intended as information on high-energy physics for graduate students and research workers familiar with the fundamentals of classical and quantum physics

Primary standard for the number concentration of liquid-borne particles in the 10 to 20 µm diameter range

International Nuclear Information System (INIS)

Sakaguchi, T; Ehara, K

2011-01-01

The national primary standard for the number concentration of liquid-borne particles in the 10 to 20 µm diameter range has been developed at the National Institute of Advanced Industrial Science and Technology (AIST), Japan. The standard consists of a total number counting type flow cytometer (T-FCM) and an electronic balance. The T-FCM is a commercial flow cytometer modified so that the total number of particles in an aqueous suspension sampled in a test tube can be counted, and the electronic balance is used to determine the mass of the suspension. This standard is intended to be used for calibrating commercial standard suspensions of monodisperse polystyrene latex (PSL) particles. The measurand in the calibration is the mass-based number concentration (the particle number in a unit mass of a suspension), and the calibration capability covers the concentration range from 5 × 10 2 to 2 × 10 6 particles g −1 . When the concentration of the suspension is higher than 2 × 10 3 particles g −1 , the suspension is first diluted to about 1 × 10 3 particles g −1 to suppress the coincidence loss in particle counting by the T-FCM. The validity of the calibration with the T-FCM was examined by comparison with an independent method in which a scanning electron microscope (SEM) was used to determine the number concentration of particles deposited on a silicon wafer. For a suspension of 10 µm PSL particles with a concentration of approximately 1 × 10 6 particles g −1 , the concentration values determined by the T-FCM and SEM methods were 1.042 × 10 6 and 1.035 × 10 6 particles g −1 , respectively: The difference was less than 0.7%. The relative expanded uncertainty of the measurement by the T-FCM method with the coverage factor k = 2 was 4.4%

Tethered balloon-based particle number concentration, and size distribution vertical profiles within the lower troposphere of Shanghai

Science.gov (United States)

Zhang, Kun; Wang, Dongfang; Bian, Qinggen; Duan, Yusen; Zhao, Mengfei; Fei, Dongnian; Xiu, Guangli; Fu, Qingyan

2017-04-01

A tethered balloon-based measurement campaign of particle number concentration (PNC) and particle number size distribution (PNSD) in the size range of 15.7-661.2 nm was conducted within the lower troposphere of 1000 m in Shanghai, a Chinese megacity, during December of 2015. The meteorological conditions, PNC, and PNSD were synchronously measured at the ground-based station as well as by the tethered balloon. On ground level, the 88.2 nm particles were found to have the highest PNC. The Pearson correlation analysis based on the ground level data showed NO2 had a strong correlation with PNC. The synchronous measurement of PNC and PNSD at the ground station and on the tethered balloon showed that the 15.7-200 nm particles had higher PNC on ground level, but the PNC of 200-661.2 nm particles was higher at 400 m. One haze event (Dec 22nd-Dec 23rd) was selected for detailed discussion on the variation of vertical profiles of PNSD and PNC. The vertical distribution of characteristics of PNC and PNSD were observed and compared. Results indicated that the highest MaxDm (the diameter with the highest PNC) during those three launches all appeared at a high altitude, usually above 300 m. Compared to the clean days, the relatively bigger MaxDm at each height in the haze days also indicated regional transport of pollutants might contribute to more to that haze event.

Applications of high-throughput clonogenic survival assays in high-LET particle microbeams

Directory of Open Access Journals (Sweden)

Antonios eGeorgantzoglou

2016-01-01

Full Text Available Charged particle therapy is increasingly becoming a valuable tool in cancer treatment, mainly due to the favorable interaction of particle radiation with matter. Its application is still limited due, in part, to lack of data regarding the radiosensitivity of certain cell lines to this radiation type, especially to high-LET particles. From the earliest days of radiation biology, the clonogenic survival assay has been used to provide radiation response data. This method produces reliable data but it is not optimized for high-throughput microbeam studies with high-LET radiation where high levels of cell killing lead to a very low probability of maintaining cells’ clonogenic potential. A new method, therefore, is proposed in this paper, which could potentially allow these experiments to be conducted in a high-throughput fashion. Cells are seeded in special polypropylene dishes and bright-field illumination provides cell visualization. Digital images are obtained and cell detection is applied based on corner detection, generating individual cell targets as x-y points. These points in the dish are then irradiated individually by a micron field size high-LET microbeam. Post-irradiation, time-lapse imaging follows cells’ response. All irradiated cells are tracked by linking trajectories in all time-frames, based on finding their nearest position. Cell divisions are detected based on cell appearance and individual cell temporary corner density. The number of divisions anticipated is low due to the high probability of cell killing from high-LET irradiation. Survival curves are produced based on cell’s capacity to divide at least 4-5 times. The process is repeated for a range of doses of radiation. Validation shows the efficiency of the proposed cell detection and tracking method in finding cell divisions.

Applications of High-Throughput Clonogenic Survival Assays in High-LET Particle Microbeams.

Science.gov (United States)

Georgantzoglou, Antonios; Merchant, Michael J; Jeynes, Jonathan C G; Mayhead, Natalie; Punia, Natasha; Butler, Rachel E; Jena, Rajesh

2015-01-01

Charged particle therapy is increasingly becoming a valuable tool in cancer treatment, mainly due to the favorable interaction of particle radiation with matter. Its application is still limited due, in part, to lack of data regarding the radiosensitivity of certain cell lines to this radiation type, especially to high-linear energy transfer (LET) particles. From the earliest days of radiation biology, the clonogenic survival assay has been used to provide radiation response data. This method produces reliable data but it is not optimized for high-throughput microbeam studies with high-LET radiation where high levels of cell killing lead to a very low probability of maintaining cells' clonogenic potential. A new method, therefore, is proposed in this paper, which could potentially allow these experiments to be conducted in a high-throughput fashion. Cells are seeded in special polypropylene dishes and bright-field illumination provides cell visualization. Digital images are obtained and cell detection is applied based on corner detection, generating individual cell targets as x-y points. These points in the dish are then irradiated individually by a micron field size high-LET microbeam. Post-irradiation, time-lapse imaging follows cells' response. All irradiated cells are tracked by linking trajectories in all time-frames, based on finding their nearest position. Cell divisions are detected based on cell appearance and individual cell temporary corner density. The number of divisions anticipated is low due to the high probability of cell killing from high-LET irradiation. Survival curves are produced based on cell's capacity to divide at least four to five times. The process is repeated for a range of doses of radiation. Validation shows the efficiency of the proposed cell detection and tracking method in finding cell divisions.

A method for measuring particle number emissions from vehicles driving on the road.

Science.gov (United States)

Shi, J P; Harrison, R M; Evans, D E; Alam, A; Barnes, C; Carter, G

2002-01-01

Earlier research has demonstrated that the conditions of dilution of engine exhaust gases profoundly influence the size distribution and total number of particles emitted. Since real world dilution conditions are variable and therefore difficult to simulate, this research has sought to develop and validate a method for measuring particle number emissions from vehicles driving past on a road. This has been achieved successfully using carbon dioxide as a tracer of exhaust gas dilution. By subsequent adjustment of data to a constant dilution factor, it is possible to compare emissions from different vehicles using different technologies and fuels based upon real world emission data. Whilst further optimisation of the technique, especially in terms of matching the instrument response times is desirable, the measurements offer useful insights into emissions from gasoline and diesel vehicles, and the substantial proportion of particles emitted in the 3-7 nanometre size range.

Hydrodynamic interaction of two particles in confined linear shear flow at finite Reynolds number

Science.gov (United States)

Yan, Yiguang; Morris, Jeffrey F.; Koplik, Joel

2007-11-01

We discuss the hydrodynamic interactions of two solid bodies placed in linear shear flow between parallel plane walls in a periodic geometry at finite Reynolds number. The computations are based on the lattice Boltzmann method for particulate flow, validated here by comparison to previous results for a single particle. Most of our results pertain to cylinders in two dimensions but some examples are given for spheres in three dimensions. Either one mobile and one fixed particle or else two mobile particles are studied. The motion of a mobile particle is qualitatively similar in both cases at early times, exhibiting either trajectory reversal or bypass, depending upon the initial vector separation of the pair. At longer times, if a mobile particle does not approach a periodic image of the second, its trajectory tends to a stable limit point on the symmetry axis. The effect of interactions with periodic images is to produce nonconstant asymptotic long-time trajectories. For one free particle interacting with a fixed second particle within the unit cell, the free particle may either move to a fixed point or take up a limit cycle. Pairs of mobile particles starting from symmetric initial conditions are shown to asymptotically reach either fixed points, or mirror image limit cycles within the unit cell, or to bypass one another (and periodic images) indefinitely on a streamwise periodic trajectory. The limit cycle possibility requires finite Reynolds number and arises as a consequence of streamwise periodicity when the system length is sufficiently short.

Tadpoles, anomaly cancellation and the expectation value of the number of the Higgs particles in the standard model

International Nuclear Information System (INIS)

El Naschie, M.S.

2005-01-01

We motivate the concept of infinitely large and hierarchical matrices in connection with the eight-dimensional super Riemannian tensor and the unification of all fundamental forces. Subsequently, we derive the number of particle-like states and the expectation value of the number of elementary particle content of a minimally extended standard model using the total number of tadpoles and anomaly cancellation condition:nH+29nt-nv=R(8)-N(SM)=2α-bar 0-1=273 where n H is the number of hyper multiplets, n t the number of tensor multiplets, n v the vector multiplets, R (8) is the number of independent components of Riemann's curvature tensor in eight dimensions, N(SM) is the number of elementary particles content of the standard model and α-bar 0 is the inverse fine structure constant. We can conclude that N(SM)=66. Consequently, we conjecture that five Higgs particles should be involved in the standard model

Effects of particle-number-projection on nuclear moment of intertia

International Nuclear Information System (INIS)

Rozmej, P.

1976-01-01

The formalism of the moment of inertia in cranking model and BCS theory has been extended for the partially particle-number-projected BCS wave functions. The ground state moments of inertia obtained by this method are a little greater than those calculated by BCS method. A smooth growth of the moments of inertia for diminishing pairing strength constant has been obtained. (author)

Mass transfer in wetted-wall columns: correlations at high Reynolds numbers

DEFF Research Database (Denmark)

Nielsen, Christian H.E.; Kiil, Søren; Thomsen, Henrik W.

1998-01-01

(G)) were determined. In dimensionless form, the correlations are given by Sh(L) = 0.01613 Re-G(0.664) Re-L(0.426) Sc-L(0.5) Sh(G) = 0.00031 Re-G(1.05) Re-L(0.207) Sc-G(0.5) and are valid at gas-phase Reynolds numbers from 7500 to 18,300 and liquid-phase Reynolds numbers from 4000 to 12,000, conditions...... of industrial relevance. To our knowledge, no correlations for Sh(G) have been reported in the literature which are valid at such high Reynolds numbers. The wetted-wall column was equipped with six intermediate measuring positions for gas and two for liquid samples, giving rise to a high accuracy...... of the obtained correlations. Our data showed that Sh(L) and Sh(G) both depend on Re-G and Re-L due to changes in the interfacial area at the high Reynolds numbers employed. The presence of inert particles in the liquid-phase may influence the rate of mass transport, and experimental work was initiated to study...

Simultaneous projection of particle-number and angular momentum BCS wave-functions in the rare-earth nuclei

International Nuclear Information System (INIS)

Oudih, M.R.; Benhamouda, N.; Fellah, M.; Allal, N.H.

2000-01-01

A method of simultaneous particle-number and angular-momentum projection of the BCS wave-function is presented. The particle number projection method is of FBCS type. In the frame work of the adiabatic approximation, the rotational energies of the axially symmetric even-even nuclei are established and numerically calculated for the rare-earth region. (author)

High-LET particle exposure of Skylab astronauts

International Nuclear Information System (INIS)

Benton, E.V.; Peterson, D.D.; Bailey, J.V.; Parnell, T.

1977-01-01

High-LET particle radiation was registered in nuclear track recording plastic dosimeters worn on the wrists of Skylab astronauts and located in a heavily shielded film vault. The mission-average planar flux of high-LET particles with LET >= 100 keV/micron . tissue has been determined to be 2.7 +- 0.6 particles/cm 2 . day . 2π sr and 0.34 +- 0.4 particles/cm 2 . day . 2π sr, respectively, for the nine astronauts and for the film vault. Comparison of results representative of a wide range of shielding depths reveals that the magnitude and slope of the integral LET spectrum of high-LET particles inside spacecraft are proportional to the amount of shielding. (author)

High energy electromagnetic particle transportation on the GPU

Energy Technology Data Exchange (ETDEWEB)

Canal, P. [Fermilab; Elvira, D. [Fermilab; Jun, S. Y. [Fermilab; Kowalkowski, J. [Fermilab; Paterno, M. [Fermilab; Apostolakis, J. [CERN

2014-01-01

We present massively parallel high energy electromagnetic particle transportation through a finely segmented detector on a Graphics Processing Unit (GPU). Simulating events of energetic particle decay in a general-purpose high energy physics (HEP) detector requires intensive computing resources, due to the complexity of the geometry as well as physics processes applied to particles copiously produced by primary collisions and secondary interactions. The recent advent of hardware architectures of many-core or accelerated processors provides the variety of concurrent programming models applicable not only for the high performance parallel computing, but also for the conventional computing intensive application such as the HEP detector simulation. The components of our prototype are a transportation process under a non-uniform magnetic field, geometry navigation with a set of solid shapes and materials, electromagnetic physics processes for electrons and photons, and an interface to a framework that dispatches bundles of tracks in a highly vectorized manner optimizing for spatial locality and throughput. Core algorithms and methods are excerpted from the Geant4 toolkit, and are modified and optimized for the GPU application. Program kernels written in C/C++ are designed to be compatible with CUDA and OpenCL and with the aim to be generic enough for easy porting to future programming models and hardware architectures. To improve throughput by overlapping data transfers with kernel execution, multiple CUDA streams are used. Issues with floating point accuracy, random numbers generation, data structure, kernel divergences and register spills are also considered. Performance evaluation for the relative speedup compared to the corresponding sequential execution on CPU is presented as well.

Financial Knudsen number: Breakdown of continuous price dynamics and asymmetric buy-and-sell structures confirmed by high-precision order-book information.

Science.gov (United States)

Yura, Yoshihiro; Takayasu, Hideki; Sornette, Didier; Takayasu, Misako

2015-10-01

We generalize the description of the dynamics of the order book of financial markets in terms of a Brownian particle embedded in a fluid of incoming, exiting, and annihilating particles by presenting a model of the velocity on each side (buy and sell) independently. The improved model builds on the time-averaged number of particles in the inner layer and its change per unit time, where the inner layer is revealed by the correlations between price velocity and change in the number of particles (limit orders). This allows us to introduce the Knudsen number of the financial Brownian particle motion and its asymmetric version (on the buy and sell sides). Not being considered previously, the asymmetric Knudsen numbers are crucial in finance in order to detect asymmetric price changes. The Knudsen numbers allows us to characterize the conditions for the market dynamics to be correctly described by a continuous stochastic process. Not questioned until now for large liquid markets such as the USD-JPY and EUR-USD exchange rates, we show that there are regimes when the Knudsen numbers are so high that discrete particle effects dominate, such as during market stresses and crashes. We document the presence of imbalances of particles depletion rates on the buy and sell sides that are associated with high Knudsen numbers and violent directional price changes. This indicator can detect the direction of the price motion at the early stage while the usual volatility risk measure is blind to the price direction.

Financial Knudsen number: Breakdown of continuous price dynamics and asymmetric buy-and-sell structures confirmed by high-precision order-book information

Science.gov (United States)

Yura, Yoshihiro; Takayasu, Hideki; Sornette, Didier; Takayasu, Misako

2015-10-01

We generalize the description of the dynamics of the order book of financial markets in terms of a Brownian particle embedded in a fluid of incoming, exiting, and annihilating particles by presenting a model of the velocity on each side (buy and sell) independently. The improved model builds on the time-averaged number of particles in the inner layer and its change per unit time, where the inner layer is revealed by the correlations between price velocity and change in the number of particles (limit orders). This allows us to introduce the Knudsen number of the financial Brownian particle motion and its asymmetric version (on the buy and sell sides). Not being considered previously, the asymmetric Knudsen numbers are crucial in finance in order to detect asymmetric price changes. The Knudsen numbers allows us to characterize the conditions for the market dynamics to be correctly described by a continuous stochastic process. Not questioned until now for large liquid markets such as the USD-JPY and EUR-USD exchange rates, we show that there are regimes when the Knudsen numbers are so high that discrete particle effects dominate, such as during market stresses and crashes. We document the presence of imbalances of particles depletion rates on the buy and sell sides that are associated with high Knudsen numbers and violent directional price changes. This indicator can detect the direction of the price motion at the early stage while the usual volatility risk measure is blind to the price direction.

Surfing and drift acceleration at high mach number quasi-perpendicular shocks

International Nuclear Information System (INIS)

Amano, T.

2008-01-01

Electron acceleration in high Mach number collisionless shocks relevant to supernova remnant is discussed. By performing one- and two-dimensional particle-in-cell simulations of quasi-perpendicular shocks, we find that energetic electrons are quickly generated in the shock transition region through shock surfing and drift acceleration. The electron energization is strong enough to account for the observed injection at supernova remnant shocks. (author)

Niacin extended-release/simvastatin combination therapy produces larger favorable changes in high-density lipoprotein particles than atorvastatin monotherapy

Directory of Open Access Journals (Sweden)

Toth PP

2012-01-01

Full Text Available Peter P Toth1, Kamlesh M Thakker2, Ping Jiang2, Robert J Padley21University of Illinois College of Medicine, Peoria, and CGH Medical Center, Sterling, 2Abbott, Abbott Park, IL, USABackground: The purpose of this research was to compare the effects of niacin extended-release in combination with simvastatin (NER/S versus atorvastatin monotherapy on high-density lipoprotein (HDL particle number and size in patients with hyperlipidemia or dyslipidemia from the SUPREME study.Methods: This was a post hoc analysis of patients (n = 137 who completed the SUPREME study and who had lipid particle number and size measurements at both baseline and at week 12 by nuclear magnetic resonance spectroscopy. Following ≥4 weeks without lipid-modifying therapy (washout period, the patients received NER/S 1000/40 mg/day for 4 weeks followed by NER/S 2000/40 mg/day for 8 weeks, or atorvastatin 40 mg/day for 12 weeks. Median percent changes in HDL particle number and size from baseline to week 12 were compared between the NER/S and atorvastatin treatment groups using the Wilcoxon rank-sum test. Distribution of HDL particle subclasses at week 12 was compared between the treatment groups using the Cochran–Mantel–Haenszel test.Results: Treatment with NER/S resulted in a significantly greater percent reduction in small HDL particle number at week 12 compared with atorvastatin monotherapy (-1.8% versus 4.2%, P = 0.014, and a numerically greater percent increase in large HDL particle number (102.4% versus 39.2%, P = 0.078 compared with atorvastatin monotherapy. A significantly greater percent increase in HDL particle size from baseline at week 12 was observed with NER/S compared with atorvastatin (6.0% versus 1.3%, P < 0.001. NER/S treatment also resulted in a significant shift in HDL particle size from small and medium at baseline to large at week 12 (P < 0.0001.Conclusion: Treatment with NER/S resulted in larger favorable changes in number and size of HDL particle

Particle-number conserving analysis for the 2-quasiparticle and high-K multi-quasiparticle states in doubly-odd 174,176Lu

International Nuclear Information System (INIS)

Li Bingheng; Lei Yi'an; Zhang Zhenhua

2013-01-01

Two-quasiparticle bands and low-lying excited high-K four-, six-, and eight-quasiparticle bands in the doubly-odd 174,176 Lu are analyzed by using the cranked shell model (CSM) with the pairing correlations treated by a particle-number conserving (PNC) method, in which the blocking effects are taken into account exactly. The proton and neutron Nilsson level schemes for 174,176 Lu are taken from the adjacent odd-A Lu and Hf isotopes, which are adopted to reproduce the experimental bandhead energies of the one-quasiproton and one-quasineutron bands of these odd-A Lu and Hf nuclei, respectively. Once the quasiparticle configurations are determined, the experimental bandhead energies and the moments of inertia of these two- and multi-quasiparticle bands are well reproduced by PNC-CSM calculations. The Coriolis mixing of the low-K (K=|Ω 1 -Ω 2 |) two-quasiparticle band of the Gallagher-Moszkowski doublet with one nucleon in the Ω=1/2 orbital is analyzed. (authors)

Cholesterol Efflux Capacity, High-Density Lipoprotein Particle Number, and Incident Cardiovascular Events: An Analysis From the JUPITER Trial (Justification for the Use of Statins in Prevention: An Intervention Trial Evaluating Rosuvastatin).

Science.gov (United States)

Khera, Amit V; Demler, Olga V; Adelman, Steven J; Collins, Heidi L; Glynn, Robert J; Ridker, Paul M; Rader, Daniel J; Mora, Samia

2017-06-20

Recent failures of drugs that raised high-density lipoprotein (HDL) cholesterol levels to reduce cardiovascular events in clinical trials have led to increased interest in alternative indices of HDL quality, such as cholesterol efflux capacity, and HDL quantity, such as HDL particle number. However, no studies have directly compared these metrics in a contemporary population that includes potent statin therapy and low low-density lipoprotein cholesterol. HDL cholesterol levels, apolipoprotein A-I, cholesterol efflux capacity, and HDL particle number were assessed at baseline and 12 months in a nested case-control study of the JUPITER trial (Justification for the Use of Statins in Prevention: An Intervention Trial Evaluating Rosuvastatin), a randomized primary prevention trial that compared rosuvastatin treatment to placebo in individuals with normal low-density lipoprotein cholesterol but increased C-reactive protein levels. In total, 314 cases of incident cardiovascular disease (CVD) (myocardial infarction, unstable angina, arterial revascularization, stroke, or cardiovascular death) were compared to age- and gender-matched controls. Conditional logistic regression models adjusting for risk factors evaluated associations between HDL-related biomarkers and incident CVD. Cholesterol efflux capacity was moderately correlated with HDL cholesterol, apolipoprotein A-I, and HDL particle number (Spearman r = 0.39, 0.48, and 0.39 respectively; P capacity (OR/SD, 0.89; 95% CI, 0.72-1.10; P =0.28), HDL cholesterol (OR/SD, 0.82; 95% CI, 0.66-1.02; P =0.08), or apolipoprotein A-I (OR/SD, 0.83; 95% CI, 0.67-1.03; P =0.08). Twelve months of rosuvastatin (20 mg/day) did not change cholesterol efflux capacity (average percentage change -1.5%, 95% CI, -13.3 to +10.2; P =0.80), but increased HDL cholesterol (+7.7%), apolipoprotein A-I (+4.3%), and HDL particle number (+5.2%). On-statin cholesterol efflux capacity was inversely associated with incident CVD (OR/SD, 0.62; 95% CI, 0

International conference on production of particles with new quantum numbers: Proceedings

International Nuclear Information System (INIS)

1976-01-01

This report contains papers on the following topics: mechanisms of new particle production; the total cross section for e + e/sup /minus// → hadrons and its associated spectroscopy; recent results on the new particle states below 3.7 GeV produced in e + e/sup /minus// annihilations; new results on J//psi/ and /psi/' decays from DASP; excess muons and new results in /psi/ photoproduction; probing the new particles with hadron beams; properties of prompt leptons; muon production in hadron-hadron collisions; large transverse momentum photons from high energy proton proton collisions; dimuon and trimuon production in deep inelastic muon interactions; streamer chamber search for narrow hadrons with a muon-enriched trigger; threshold effects of new particle production by high energy neutrinos and antineutrinos; the observation of neutrino induced μ/sup /minus//e + events in the Fermilab bubble chamber; search for antineutrino induced μ + e/sup /minus// events; observation of muon-neutrino reactions producing a positron and a strange particle; observation of the reaction ν/sub μ/ + p → ν/sub μ/ + p; search for muonic pairs; strange particle production in neutrino interactions; neutral currents---the structure of the coupling; evidence for parity non-conservation in the weak neutral current; observation of elastic neutrino-proton scattering; threshold and other properties of U particle production in e + e/sup /minus// annihilation; anomalous muon production in e + e/sup /minus// collisions; electron production; strongly interacting heavy lepton; and /psi/'s without charm

Theory of the Thermal Diffusion of Microgel Particles in Highly Compressed Suspensions

Science.gov (United States)

Sokoloff, Jeffrey; Maloney, Craig; Ciamarra, Massimo; Bi, Dapeng

One amazing property of microgel colloids is the ability of the particles to thermally diffuse, even when they are compressed to a volume well below their swollen state volume, despite the fact that they are surrounded by and pressed against other particles. A glass transition is expected to occur when the colloid is sufficiently compressed for diffusion to cease. It is proposed that the diffusion is due to the ability of the highly compressed particles to change shape with little cost in free energy. It will be shown that most of the free energy required to compress microgel particles is due to osmotic pressure resulting from either counterions or monomers inside of the gel, which depends on the particle's volume. There is still, however, a cost in free energy due to polymer elasticity when particles undergo the distortions necessary for them to move around each other as they diffuse through the compressed colloid, even if it occurs at constant volume. Using a scaling theory based on simple models for the linking of polymers belonging to the microgel particles, we examine the conditions under which the cost in free energy needed for a particle to diffuse is smaller than or comparable to thermal energy, which is a necessary condition for particle diffusion. Based on our scaling theory, we predict that thermally activated diffusion should be possible when the mean number of links along the axis along which a distortion occurs is much larger than N 1 / 5, where Nis the mean number of monomers in a polymer chain connecting two links in the gel.

Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

Energy Technology Data Exchange (ETDEWEB)

Babu, S. Suresh, E-mail: s_sureshbabu@vssc.gov.in [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Kompalli, Sobhan Kumar [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Moorthy, K. Krishna [Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012 (India)

2016-09-01

Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

International Nuclear Information System (INIS)

Babu, S. Suresh; Kompalli, Sobhan Kumar; Moorthy, K. Krishna

2016-01-01

Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

Deep-hole and high-lying particle states in heavy nuclei

International Nuclear Information System (INIS)

Gales, S.

1985-01-01

Our present knowledge on single-particle strength functions from one nucleon transfer reactions is reviewed. Results on deeply-bound neutron hole states in the Sn and Pb region are discussed with emphasis on the investigation of a very large excitation energy range. The first measurements on the γ-decay of deeply-bound hole states in the Sn isotopes are reported. High energy neutron and proton stripping reactions are used to study the particle response function. These reactions are particularly well suited to the study of high-spin outer subshells. For the proton states, the behaviour of the 1h 11/2 and 1i 13/2 strength distributions, as a function of deformation in the Sm region, is discussed. Strong transitions to high-lying neutron states are observed in the 112, 116, 118, 120, 122, 124 Sn and 208 Pb nuclei. The empirical systematics for both proton and neutron particle strength distributions are compared to the predictions from the quasi particle-phonon and the single-particle vibration coupling nuclear models. (orig.)

Source apportionment of aerosol particles at a European air pollution hot spot using particle number size distributions and chemical composition.

Science.gov (United States)

Leoni, Cecilia; Pokorná, Petra; Hovorka, Jan; Masiol, Mauro; Topinka, Jan; Zhao, Yongjing; Křůmal, Kamil; Cliff, Steven; Mikuška, Pavel; Hopke, Philip K

2018-03-01

Ostrava in the Moravian-Silesian region (Czech Republic) is a European air pollution hot spot for airborne particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), and ultrafine particles (UFPs). Air pollution source apportionment is essential for implementation of successful abatement strategies. UFPs or nanoparticles of diameter hot-spot including nanoparticles, Positive Matrix Factorization (PMF) was applied to highly time resolved particle number size distributions (NSD, 14 nm-10 μm) and PM 0.09-1.15 chemical composition. Diurnal patterns, meteorological variables, gaseous pollutants, organic markers, and associations between the NSD factors and chemical composition factors were used to identify the pollution sources. The PMF on the NSD reveals two factors in the ultrafine size range: industrial UFPs (28%, number mode diameter - NMD 45 nm), industrial/fresh road traffic nanoparticles (26%, NMD 26 nm); three factors in the accumulation size range: urban background (24%, NMD 93 nm), coal burning (14%, volume mode diameter - VMD 0.5 μm), regional pollution (3%, VMD 0.8 μm) and one factor in the coarse size range: industrial coarse particles/road dust (2%, VMD 5 μm). The PMF analysis of PM 0.09-1.15 revealed four factors: SIA/CC/BB (52%), road dust (18%), sinter/steel (16%), iron production (16%). The factors in the ultrafine size range resolved with NSD have a positive correlation with sinter/steel production and iron production factors resolved with chemical composition. Coal combustion factor resolved with NSD has moderate correlation with SIA/CC/BB factor. The organic markers homohopanes correlate with coal combustion and the levoglucosan correlates with urban background. The PMF applications to NSD and chemical composition datasets are complementary. PAHs in PM 1 were found to be associated with coal combustion factor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Calculation of the output power in self-amplified spontaneous radiation using scaling of power with number of simulation particles

International Nuclear Information System (INIS)

Yu, L.H.

1998-01-01

Recent advances in self-amplified spontaneous emission (SASE) experiments stimulate interest in quantitative comparison of measurements with theory. In this paper we show that the widely used simulation code TDA3D, developed by Tran and Wurtele [Comput. Phys. Commun. 54, 263 (1989)] even though a single frequency code, can be used to determine the output power in the SASE process with excellent approximation in the exponential growth regime. The method applies when the gain is not very high, which is a special advantage, because when the gain is not very high, the analytical calculation is particularly difficult since the exponential growing term does not dominate. The analysis utilizes a scaling relation between the output power and the number of simulation particles in the code TDA3D: left-angle P right-angle=N λ ' /N λ left-angle P ' right-angle, where left-angle P right-angle is the output power and N λ is the line density of the electrons, while left-angle P ' right-angle is the calculated output power using a line density N λ ' of the number of simulation particles in the code TDA3D. Because of the scaling property, the number of simulation particles can be taken to be many orders of magnitude less than the actual experiment. Comparison of our results with experiment yields new insight into the SASE process. copyright 1998 The American Physical Society

Neutrino fluxes produced by high energy solar flare particles

International Nuclear Information System (INIS)

Kolomeets, E.V.; Shmonin, V.L.

1975-01-01

In this work the calculated differential energy spectra of neutrinos poduced by high energy protons accelerated during 'small' solar flares are presented. The muon flux produced by neutrino interactions with the matter at large depths under the ground is calculated. The obtained flux of muons for the total number of solar flare accelerated protons of 10 28 - 10 32 is within 10 9 - 10 13 particles/cm 2 X s x ster. (orig.) [de

In Situ Balloon-Borne Ice Particle Imaging in High-Latitude Cirrus

Science.gov (United States)

Kuhn, Thomas; Heymsfield, Andrew J.

2016-09-01

Cirrus clouds reflect incoming solar radiation, creating a cooling effect. At the same time, these clouds absorb the infrared radiation from the Earth, creating a greenhouse effect. The net effect, crucial for radiative transfer, depends on the cirrus microphysical properties, such as particle size distributions and particle shapes. Knowledge of these cloud properties is also needed for calibrating and validating passive and active remote sensors. Ice particles of sizes below 100 µm are inherently difficult to measure with aircraft-mounted probes due to issues with resolution, sizing, and size-dependent sampling volume. Furthermore, artefacts are produced by shattering of particles on the leading surfaces of the aircraft probes when particles several hundred microns or larger are present. Here, we report on a series of balloon-borne in situ measurements that were carried out at a high-latitude location, Kiruna in northern Sweden (68N 21E). The method used here avoids these issues experienced with the aircraft probes. Furthermore, with a balloon-borne instrument, data are collected as vertical profiles, more useful for calibrating or evaluating remote sensing measurements than data collected along horizontal traverses. Particles are collected on an oil-coated film at a sampling speed given directly by the ascending rate of the balloon, 4 m s-1. The collecting film is advanced uniformly inside the instrument so that an always unused section of the film is exposed to ice particles, which are measured by imaging shortly after sampling. The high optical resolution of about 4 µm together with a pixel resolution of 1.65 µm allows particle detection at sizes of 10 µm and larger. For particles that are 20 µm (12 pixel) in size or larger, the shape can be recognized. The sampling volume, 130 cm3 s-1, is well defined and independent of particle size. With the encountered number concentrations of between 4 and 400 L-1, this required about 90- to 4-s sampling times to

Particle image velocimetry measurements of Mach 3 turbulent boundary layers at low Reynolds numbers

Science.gov (United States)

Brooks, J. M.; Gupta, A. K.; Smith, M. S.; Marineau, E. C.

2018-05-01

Particle image velocimetry (PIV) measurements of Mach 3 turbulent boundary layers (TBL) have been performed under low Reynolds number conditions, Re_τ =200{-}1000, typical of direct numerical simulations (DNS). Three reservoir pressures and three measurement locations create an overlap in parameter space at one research facility. This allows us to assess the effects of Reynolds number, particle response and boundary layer thickness separate from facility specific experimental apparatus or methods. The Morkovin-scaled streamwise fluctuating velocity profiles agree well with published experimental and numerical data and show a small standard deviation among the nine test conditions. The wall-normal fluctuating velocity profiles show larger variations which appears to be due to particle lag. Prior to the current study, no detailed experimental study characterizing the effect of Stokes number on attenuating wall-normal fluctuating velocities has been performed. A linear variation is found between the Stokes number ( St) and the relative error in wall-normal fluctuating velocity magnitude (compared to hot wire anemometry data from Klebanoff, Characteristics of Turbulence in a Boundary Layer with Zero Pressure Gradient. Tech. Rep. NACA-TR-1247, National Advisory Committee for Aeronautics, Springfield, Virginia, 1955). The relative error ranges from about 10% for St=0.26 to over 50% for St=1.06. Particle lag and spatial resolution are shown to act as low-pass filters on the fluctuating velocity power spectral densities which limit the measurable energy content. The wall-normal component appears more susceptible to these effects due to the flatter spectrum profile which indicates that there is additional energy at higher wave numbers not measured by PIV. The upstream inclination and spatial correlation extent of coherent turbulent structures agree well with published data including those using krypton tagging velocimetry (KTV) performed at the same facility.

Constraints on the dark matter particle mass from the number of Milky Way satellites

International Nuclear Information System (INIS)

Polisensky, Emil; Ricotti, Massimo

2011-01-01

We have conducted N-body simulations of the growth of Milky Way-sized halos in cold and warm dark matter cosmologies. The number of dark matter satellites in our simulated Milky Ways decreases with decreasing mass of the dark matter particle. Assuming that the number of dark matter satellites exceeds or equals the number of observed satellites of the Milky Way, we derive lower limits on the dark matter particle mass. We find with 95% confidence m s >13.3 keV for a sterile neutrino produced by the Dodelson and Widrow mechanism, m s >8.9 keV for the Shi and Fuller mechanism, m s >3.0 keV for the Higgs decay mechanism, and m WDM >2.3 keV for a thermal dark matter particle. The recent discovery of many new dark matter dominated satellites of the Milky Way in the Sloan Digital Sky Survey allows us to set lower limits comparable to constraints from the complementary methods of Lyman-α forest modeling and x-ray observations of the unresolved cosmic x-ray background and of dark matter halos from dwarf galaxy to cluster scales. Future surveys like LSST, DES, PanSTARRS, and SkyMapper have the potential to discover many more satellites and further improve constraints on the dark matter particle mass.

First passage times in homogeneous nucleation: Dependence on the total number of particles

International Nuclear Information System (INIS)

Yvinec, Romain; Bernard, Samuel; Pujo-Menjouet, Laurent; Hingant, Erwan

2016-01-01

Motivated by nucleation and molecular aggregation in physical, chemical, and biological settings, we present an extension to a thorough analysis of the stochastic self-assembly of a fixed number of identical particles in a finite volume. We study the statistics of times required for maximal clusters to be completed, starting from a pure-monomeric particle configuration. For finite volumes, we extend previous analytical approaches to the case of arbitrary size-dependent aggregation and fragmentation kinetic rates. For larger volumes, we develop a scaling framework to study the first assembly time behavior as a function of the total quantity of particles. We find that the mean time to first completion of a maximum-sized cluster may have a surprisingly weak dependence on the total number of particles. We highlight how higher statistics (variance, distribution) of the first passage time may nevertheless help to infer key parameters, such as the size of the maximum cluster. Finally, we present a framework to quantify formation of macroscopic sized clusters, which are (asymptotically) very unlikely and occur as a large deviation phenomenon from the mean-field limit. We argue that this framework is suitable to describe phase transition phenomena, as inherent infrequent stochastic processes, in contrast to classical nucleation theory

Effects of biodiesel, engine load and diesel particulate filter on nonvolatile particle number size distributions in heavy-duty diesel engine exhaust.

Science.gov (United States)

Young, Li-Hao; Liou, Yi-Jyun; Cheng, Man-Ting; Lu, Jau-Huai; Yang, Hsi-Hsien; Tsai, Ying I; Wang, Lin-Chi; Chen, Chung-Bang; Lai, Jim-Shoung

2012-01-15

Diesel engine exhaust contains large numbers of submicrometer particles that degrade air quality and human health. This study examines the number emission characteristics of 10-1000 nm nonvolatile particles from a heavy-duty diesel engine, operating with various waste cooking oil biodiesel blends (B2, B10 and B20), engine loads (0%, 25%, 50% and 75%) and a diesel oxidation catalyst plus diesel particulate filter (DOC+DPF) under steady modes. For a given load, the total particle number concentrations (N(TOT)) decrease slightly, while the mode diameters show negligible changes with increasing biodiesel blends. For a given biodiesel blend, both the N(TOT) and mode diameters increase modestly with increasing load of above 25%. The N(TOT) at idle are highest and their size distributions are strongly affected by condensation and possible nucleation of semivolatile materials. Nonvolatile cores of diameters less than 16 nm are only observed at idle mode. The DOC+DPF shows remarkable filtration efficiency for both the core and soot particles, irrespective of the biodiesel blend and engine load under study. The N(TOT) post the DOC+DPF are comparable to typical ambient levels of ≈ 10(4)cm(-3). This implies that, without concurrent reductions of semivolatile materials, the formation of semivolatile nucleation mode particles post the after treatment is highly favored. Copyright © 2011 Elsevier B.V. All rights reserved.

Nonrelativistic trace and diffeomorphism anomalies in particle number background

Science.gov (United States)

Auzzi, Roberto; Baiguera, Stefano; Nardelli, Giuseppe

2018-04-01

Using the heat kernel method, we compute nonrelativistic trace anomalies for Schrödinger theories in flat spacetime, with a generic background gauge field for the particle number symmetry, both for a free scalar and a free fermion. The result is genuinely nonrelativistic, and it has no counterpart in the relativistic case. Contrary to naive expectations, the anomaly is not gauge invariant; this is similar to the nongauge covariance of the non-Abelian relativistic anomaly. We also show that, in the same background, the gravitational anomaly for a nonrelativistic scalar vanishes.

Decreasing particle number concentrations in a warming atmosphere and implications

Directory of Open Access Journals (Sweden)

F. Yu

2012-03-01

Full Text Available New particle formation contributes significantly to the number concentration of condensation nuclei (CN as well as cloud CN (CCN, a key factor determining aerosol indirect radiative forcing of the climate system. Using a physics-based nucleation mechanism that is consistent with a range of field observations of aerosol formation, it is shown that projected increases in global temperatures could significantly inhibit new particle, and CCN, formation rates worldwide. An analysis of CN concentrations observed at four NOAA ESRL/GMD baseline stations since the 1970s and two other sites since 1990s reveals long-term decreasing trends that are consistent in sign with, but are larger in magnitude than, the predicted temperature effects. The possible reasons for larger observed long-term CN reductions at remote sites are discussed. The combined effects of rising temperatures on aerosol nucleation rates and other chemical and microphysical processes may imply substantial decreases in future tropospheric particle abundances associated with global warming, delineating a potentially significant feedback mechanism that increases Earth's climate sensitivity to greenhouse gas emissions. Further research is needed to quantify the magnitude of such a feedback process.

High energy particle physics in the United Kingdom

International Nuclear Information System (INIS)

1985-06-01

The paper reviews the U.K. participation in High Energy Particle Physics (HEPP) research. The funding of science in Higher Education and the Research Councils; high energy particle physics; relevance of particle physics to science and technology; particle physics in the U.K.; CERN; and the opportunity cost of HEPP within the science budget; are all discussed. (U.K.)

Baryon number violation in high energy collisions

International Nuclear Information System (INIS)

Farrar, G.R.; Meng, R.

1990-08-01

We study the phenomenology of baryon number violation induced by electroweak instantons. We find that if the naive-instanton amplitudes were valid for arbitrarily high energies, the event rate at the SSC would be a few per hour, with a typical event consisting of 3 'primary' antileptons and 7 'primary' antiquark jets, accompanied by ≅ 85 electroweak gauge bosons, having a sharp threshold in the total sub-energy at about 17 TeV. We describe how to establish their electroweak-instanton-induced origin. The naive instanton approximation is known to overestimate the rate for these processes, so this work focusses attention on the need for more accurate calculations, and for a calculational method which is appropriate when the energy of the initial particles is above the sphaleron energy. (orig.)

Ultrafine particles in inhabited areas in the Arctic - From very low to high concentrations

DEFF Research Database (Denmark)

Pétursdóttir, Una; Kirkelund, Gunvor Marie; Press-Kristensen, Kåre

2017-01-01

The Arctic is considered a pristine environment, where pollution mainly originates from global sources. The present study examines particle number concentrations (PNCs) and the main sources of airborne ultrafine particles (UFPs, d < 100 nm) in the town Sisimiut and two nearby settlements, Sarfann......The Arctic is considered a pristine environment, where pollution mainly originates from global sources. The present study examines particle number concentrations (PNCs) and the main sources of airborne ultrafine particles (UFPs, d ..., Sarfannguit and Itilleq, in West Greenland. Measurements were carried out during three weeks in April and May 2016. Air temperatures during the measurements ranged from −4.4 to +8.7 °C. A portable condensation particle counter (P-Trak) was used for the measurements. Results showed that the lowest...... in Sisimiut, while subsequent measurements at the same location showed much lower PNCs. The presence of heavy machinery elevated PNCs highly during two measurement events, giving PNCs up to 270,993 cm−3 but dropping to 1180 cm−3 10 min later, after the vehicle had passed by. A measurement event in Sisimiut...

Explicit high-order non-canonical symplectic particle-in-cell algorithms for Vlasov-Maxwell systems

International Nuclear Information System (INIS)

Xiao, Jianyuan; Liu, Jian; He, Yang; Zhang, Ruili; Qin, Hong; Sun, Yajuan

2015-01-01

Explicit high-order non-canonical symplectic particle-in-cell algorithms for classical particle-field systems governed by the Vlasov-Maxwell equations are developed. The algorithms conserve a discrete non-canonical symplectic structure derived from the Lagrangian of the particle-field system, which is naturally discrete in particles. The electromagnetic field is spatially discretized using the method of discrete exterior calculus with high-order interpolating differential forms for a cubic grid. The resulting time-domain Lagrangian assumes a non-canonical symplectic structure. It is also gauge invariant and conserves charge. The system is then solved using a structure-preserving splitting method discovered by He et al. [preprint http://arxiv.org/abs/arXiv:1505.06076 (2015)], which produces five exactly soluble sub-systems, and high-order structure-preserving algorithms follow by combinations. The explicit, high-order, and conservative nature of the algorithms is especially suitable for long-term simulations of particle-field systems with extremely large number of degrees of freedom on massively parallel supercomputers. The algorithms have been tested and verified by the two physics problems, i.e., the nonlinear Landau damping and the electron Bernstein wave

Explicit high-order non-canonical symplectic particle-in-cell algorithms for Vlasov-Maxwell systems

Energy Technology Data Exchange (ETDEWEB)

Xiao, Jianyuan [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China; Qin, Hong [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA; Liu, Jian [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China; He, Yang [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China; Zhang, Ruili [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China; Sun, Yajuan [LSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, P.O. Box 2719, Beijing 100190, China

2015-11-01

Explicit high-order non-canonical symplectic particle-in-cell algorithms for classical particle-field systems governed by the Vlasov-Maxwell equations are developed. The algorithms conserve a discrete non-canonical symplectic structure derived from the Lagrangian of the particle-field system, which is naturally discrete in particles. The electromagnetic field is spatially discretized using the method of discrete exterior calculus with high-order interpolating differential forms for a cubic grid. The resulting time-domain Lagrangian assumes a non-canonical symplectic structure. It is also gauge invariant and conserves charge. The system is then solved using a structure-preserving splitting method discovered by He et al. [preprint arXiv: 1505.06076 (2015)], which produces five exactly soluble sub-systems, and high-order structure-preserving algorithms follow by combinations. The explicit, high-order, and conservative nature of the algorithms is especially suitable for long-term simulations of particle-field systems with extremely large number of degrees of freedom on massively parallel supercomputers. The algorithms have been tested and verified by the two physics problems, i.e., the nonlinear Landau damping and the electron Bernstein wave. (C) 2015 AIP Publishing LLC.

Damage in agitated vessels of large visco-elastic particles dispersed in a highly viscous fluid.

Science.gov (United States)

Bouvier, Laurent; Moreau, Anne; Line, Alain; Fatah, Nouria; Delaplace, Guillaume

2011-01-01

Many food recipes entail several homogenization steps for solid particles in hot or cold viscous liquids, such as pureed fruit and sugar, jam or sauce with mushroom pieces. Unfortunately, these unavoidable processes induce damage to the solid particles. To date, little is known of the extent and nature of the damage caused. Consequently, few clear guidelines are available for monitoring solid particle integrity when mixing solid/liquid suspensions in an agitated tank. In this study, an attempt is made to quantify the impact of various physical parameters including the influence of the rotational speed of the impeller and the processing time on particle attrition, when a suspension of large visco-elastic particles in a highly viscous fluid is mixed under isothermal condition. Pectin gel particles were immerged in a viscous liquid and homogenized for various times and rotational speeds, while the evolution of the particle's morphological parameters was monitored. Then, a set of dimensionless numbers governing the attrition mechanism is established and some empirical process relationships are proposed to correlate these numbers to the morphological characteristics and mass balance ratios. From the conditions observed, it is clear that 2 dimensionless ratios could be responsible for a change in the damaging mechanisms. These 2 ratios are the Froude and impeller rotation numbers. Finally, in the conditions tested, mass balance ratios appear to be mainly sensitive to the impeller rotational number, while the shape ratios are both impacted by the Froude and impeller rotational numbers. Damage to solid particles suspended in a stirred vessel reduce the final product quality in industrial cooking processes. Examples of this are fruit in jam or sauces with mushroom pieces. The attrition phenomenon was measured and the influences of the impeller rotational speed and processing time were evaluated quantitatively in function of dimensionless numbers. This study contributes key

The drag and lift of different non-spherical particles from low to high Re

Science.gov (United States)

Sanjeevi, Sathish K. P.; Padding, Johan

2017-11-01

The present work investigates a simplified drag and lift model that can be used for different non-spherical particles. The flow around different non-spherical particles is studied using a multi-relaxation-time lattice Boltzmann method. We compute the mean drag coefficient CD , ϕ at different incident angles ϕ for a wide range of Reynolds numbers (Re). We show that the sine-squared drag law CD , ϕ =CD , ϕ =0° +(CD , ϕ =90° -CD , ϕ =0°) sin2 ϕ holds up to large Reynolds numbers Re = 2000 . The sine-squared dependence of CD occurs at Stokes flow (very low Re) due to linearity of the flow fields. We explore the physical origin behind the sine-squared law at high Re , and reveal that surprisingly, this does not occur due to linearity of flow fields. Instead, it occurs due to an interesting pattern of pressure distribution contributing to the drag, at higher Re , for different incident angles. Similarly, we find that the equivalent theoretical equation of lift coefficient CL can provide a decent approximation, even at high Re , for elongated particles. Such a drag and lift law valid at high Re is very much useful for Euler-Lagrangian fluidization simulations of the non-spherical particles. European Research Council (ERC) consolidator Grant scheme, Contract No. 615096 (NonSphereFlow).

High-Mach number, laser-driven magnetized collisionless shocks

International Nuclear Information System (INIS)

Schaeffer, Derek B.; Fox, W.; Haberberger, D.; Fiksel, G.; Bhattacharjee, A.

2017-01-01

Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to high energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of high-Mach number collisionless shocks created through the interaction of a laser-driven magnetic piston and magnetized ambient plasma. Through time-resolved, 2-D imaging we observe large density and magnetic compressions that propagate at super-Alfvenic speeds and that occur over ion kinetic length scales. Electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the piston laser-plasma are modeled with 2-D radiation-hydrodynamic simulations, which are used to initialize 2-D particle-in-cell simulations of the interaction between the piston and ambient plasmas. The numerical results show the formation of collisionless shocks, including the separate dynamics of the carbon and hydrogen ions that constitute the ambient plasma and their effect on the shock structure. Furthermore, the simulations also show the shock separating from the piston, which we observe in the data at late experimental times.

On the functional form of particle number size distributions: influence of particle source and meteorological variables

Science.gov (United States)

Cugerone, Katia; De Michele, Carlo; Ghezzi, Antonio; Gianelle, Vorne; Gilardoni, Stefania

2018-04-01

Particle number size distributions (PNSDs) have been collected periodically in the urban area of Milan, Italy, during 2011 and 2012 in winter and summer months. Moreover, comparable PNSD measurements were carried out in the rural mountain site of Oga-San Colombano (2250 m a.s.l.), Italy, during February 2005 and August 2011. The aerosol data have been measured through the use of optical particle counters in the size range 0.3-25 µm, with a time resolution of 1 min. The comparison of the PNSDs collected in the two sites has been done in terms of total number concentration, showing higher numbers in Milan (often exceeding 103 cm-3 in winter season) compared to Oga-San Colombano (not greater than 2×102 cm-3), as expected. The skewness-kurtosis plane has been used in order to provide a synoptic view, and select the best distribution family describing the empirical PNSD pattern. The four-parameter Johnson system-bounded distribution (called Johnson SB or JSB) has been tested for this aim, due to its great flexibility and ability to assume different shapes. The PNSD pattern has been found to be generally invariant under site and season changes. Nevertheless, several PNSDs belonging to the Milan winter season (generally more than 30 %) clearly deviate from the standard empirical pattern. The seasonal increase in the concentration of primary aerosols due to combustion processes in winter and the influence of weather variables throughout the year, such as precipitation and wind speed, could be considered plausible explanations of PNSD dynamics.

Coating Thickness Measurement of the Simulated TRISO-Coated Fuel Particles using an Image Plate and a High Resolution Scanner

International Nuclear Information System (INIS)

Kim, Woong Ki; Kim, Yeon Ku; Jeong, Kyung Chai; Lee, Young Woo; Kim, Bong Goo; Eom, Sung Ho; Kim, Young Min; Yeo, Sung Hwan; Cho, Moon Sung

2014-01-01

In this study, the thickness of the coating layers of 196 coated particles was measured using an Image Plate detector, high resolution scanner and digital image processing techniques. The experimental results are as follows. - An X-ray image was acquired for 196 simulated TRISO-coated fuel particles with ZrO 2 kernel using an Image Plate with high resolution in a reduced amount of time. - We could observe clear boundaries between coating layers for 196 particles. - The geometric distortion error was compensated for the calculation. - The coating thickness of the TRISO-coated fuel particles can be nondestructively measured using X-ray radiography and digital image processing technology. - We can increase the number of TRISO-coated particles to be inspected by increasing the number of Image Plate detectors. A TRISO-coated fuel particle for an HTGR (high temperature gas-cooled reactor) is composed of a nuclear fuel kernel and outer coating layers. The coating layers consist of buffer PyC (pyrolytic carbon), inner PyC (I-PyC), SiC, and outer PyC (O-PyC) layer. The coating thickness is measured to evaluate the soundness of the coating layers. X-ray radiography is one of the nondestructive alternatives for measuring the coating thickness without generating a radioactive waste. Several billion particles are subject to be loaded in a reactor. A lot of sample particles should be tested as much as possible. The acquired X-ray images for the measurement of coating thickness have included a small number of particles because of the restricted resolution and size of the X-ray detector. We tried to test many particles for an X-ray exposure to reduce the measurement time. In this experiment, an X-ray image was acquired for 196 simulated TRISO-coated fuel particles using an image plate and high resolution scanner with a pixel size of 25Χ25 μm 2 . The coating thickness for the particles could be measured on the image

Effects of rigid or adaptive confinement on colloidal self-assembly. Fixed vs. fluctuating number of confined particles

Energy Technology Data Exchange (ETDEWEB)

Pȩkalski, J.; Ciach, A. [Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warszawa (Poland); Almarza, N. G. [Instituto de Química Física Rocasolano, CSIC, Serrano 119, E-28006 Madrid (Spain)

2015-05-28

The effects of confinement on colloidal self-assembly in the case of fixed number of confined particles are studied in the one dimensional lattice model solved exactly in the grand canonical ensemble (GCE) in Pȩkalski et al. [J. Chem. Phys. 142, 014903 (2015)]. The model considers a pair interaction defined by a short-range attraction plus a longer-range repulsion. We consider thermodynamic states corresponding to self-assembly into clusters. Both fixed and adaptive boundaries are studied. For fixed boundaries, there are particular states in which, for equal average densities, the number of clusters in the GCE is larger than in the canonical ensemble. The dependence of pressure on density has a different form when the system size changes with fixed number of particles and when the number of particles changes with fixed size of the system. In the former case, the pressure has a nonmonotonic dependence on the system size. The anomalous increase of pressure for expanding system is accompanied by formation of a larger number of smaller clusters. In the case of elastic confining surfaces, we observe a bistability, i.e., two significantly different system sizes occur with almost the same probability. The mechanism of the bistability in the closed system is different to that of the case of permeable walls, where the two equilibrium system sizes correspond to a different number of particles.

Detailed SEM-EPMA investigation of high specific radioactivity particles (hot particles)

International Nuclear Information System (INIS)

Burin, K.; Tsacheva, Ts.; Mandjoukov, I.; Mandjoukova, B.

1993-01-01

Scanning electron microscope (SEM) images and electron probe microanalysis (EPMA) spectra of a group of hot particles collected in Bulgaria after the Chernobyl accident have been obtained. A technique for hot particle localization is described. The object is irradiated for two days with a β source and the resulting autoradiographs show particles location precisely. High resolution x-ray spectrum of each particle has been obtained using EPMA. The distribution of chemical elements is visualized by colour dot maps representing the regions of interest of the spectrum. It is concluded that apart from reactor fuel the investigated hot particles come from either construction materials or materials used for the covering of the damaged reactor. 7 figs., 2 ref

The Higgs--physical and number theoretical arguments for the necessity of a triple elementary particle in super symmetric spacetime

International Nuclear Information System (INIS)

El Naschie, M.S.

2004-01-01

A careful counting routine of all experimentally confirmed elementary particles plus the theoretically conjectured ones needed for a sound formulation of a mathematically consistent field theory is undertaken within a minimal N=1 super symmetric extension of the standard model of high energy physics. The number arrived at is subsequently linked to certain massless on shell representations connected to the quantized gravity interaction. Finally with the help of number theoretical arguments arising from a rigorous application of the formalism of transfinite Heterotic super string and E-infinity theory, we show that the proposed scheme would lack mathematical consistency and elegant simplicity unless we retain a postulated triplet which is logically identified as the H + , H - and H 0 Higgs particles. Connections to the 11 dimensional M theory and Harari's extended 'sub-quarks' theory is also discussed

Increasing effective number of neutrinos by decaying particles

Energy Technology Data Exchange (ETDEWEB)

Ichikawa, K.; Kawasaki, M.; Nakayama, K.; Senami, M. [Tokyo Univ. (Japan). Inst. for Cosmic Ray Research; Takahashi, F. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2007-03-15

We present models of decaying particles to increase the effective number of neutrinos N{sub {nu}} after big bang nucleosynthesis but before the structure formation begins. We point out that our scenario not only solves the discrepancy between the constraints on N{sub {nu}} from these two epochs, but also provides a possible answer to deeper inconsistency in the estimation of the matter power spectrum amplitude at small scales, represented by {sigma}{sub 8}, between the WMAP and some small scale matter power measurements such as the Lyman-{alpha} forest and weak lensing. We consider (a) saxion decay into two axions; (b) gravitino decay into axino and axion; (c) Dirac right-handed sneutrino decay into gravitino and right-handed neutrino. (orig.)

Number of particle creation and decoherence in the nonideal dynamical Casimir effect at finite temperature

International Nuclear Information System (INIS)

Celeri, L.C.; Pascoal, F.; Ponte, M.A. de; Moussa, M.H.Y.

2009-01-01

In this work we investigate the dynamical Casimir effect in a nonideal cavity by deriving an effective Hamiltonian. We first compute a general expression for the average number of particle creation, applicable for any law of motion of the cavity boundary, under the only restriction of small velocities. We also compute a general expression for the linear entropy of an arbitrary state prepared in a selected mode, also applicable for any law of motion of a slow moving boundary. As an application of our results we have analyzed both the average number of particle creation and linear entropy within a particular oscillatory motion of the cavity boundary. On the basis of these expressions we develop a comprehensive analysis of the resonances in the number of particle creation in the nonideal dynamical Casimir effect. We also demonstrate the occurrence of resonances in the loss of purity of the initial state and estimate the decoherence times associated with these resonances. Since our results were obtained in the framework of the perturbation theory, they are restricted, under resonant conditions, to a short-time approximation.

Numerical investigation of the influence of particle-particle and particle-wall collisions in turbulent wall-bounded flows at high mass loadings

International Nuclear Information System (INIS)

Alletto, Michael

2014-01-01

collisions is described in detail. With this efficient algorithm it is possible to detect the interparticle collisions with computational costs which scale linearly with the number of particles present in the computational domain. The resulting methodology is validated based on a variety of test cases. The validation process starts with two turbulent channel flows at different Reynolds numbers and one turbulent pipe flow. Using this simple test cases possible error sources can be detected easily. After that, a turbulent pipe flow is simulated, where the gravity points vertical to the mean streamwise direction. The appearance of an interesting secondary flow of second kind, for which the particles are only indirectly responsible, is analyzed in detail. In order to demonstrate the applicability of the present methodology in practically relevant turbulent flow configurations, the particle-laden cold flow in a combustion chamber model and the flow in a cyclone separator are tackled. The results are discussed in detail, compared with experimental reference data and interpreted from a physical point of view. Regarding the combustion chamber model, good agreement is found with the reference experiment. Furthermore, it is shown that the present methodology is capable to reproduce in the high mass loading case the disappearance of two stagnation points present on the axis of the low mass loading configuration. Regarding the cyclone separator flow, in the core region still some differences with the reference experiment remain.

Numerical investigation of the influence of particle-particle and particle-wall collisions in turbulent wall-bounded flows at high mass loadings

Energy Technology Data Exchange (ETDEWEB)

Alletto, Michael

2014-05-16

collisions is described in detail. With this efficient algorithm it is possible to detect the interparticle collisions with computational costs which scale linearly with the number of particles present in the computational domain. The resulting methodology is validated based on a variety of test cases. The validation process starts with two turbulent channel flows at different Reynolds numbers and one turbulent pipe flow. Using this simple test cases possible error sources can be detected easily. After that, a turbulent pipe flow is simulated, where the gravity points vertical to the mean streamwise direction. The appearance of an interesting secondary flow of second kind, for which the particles are only indirectly responsible, is analyzed in detail. In order to demonstrate the applicability of the present methodology in practically relevant turbulent flow configurations, the particle-laden cold flow in a combustion chamber model and the flow in a cyclone separator are tackled. The results are discussed in detail, compared with experimental reference data and interpreted from a physical point of view. Regarding the combustion chamber model, good agreement is found with the reference experiment. Furthermore, it is shown that the present methodology is capable to reproduce in the high mass loading case the disappearance of two stagnation points present on the axis of the low mass loading configuration. Regarding the cyclone separator flow, in the core region still some differences with the reference experiment remain.

Nuclear shape transitions and some properties of aligned-particle configurations at high spin

International Nuclear Information System (INIS)

Koo, T.L.; Chowdhury, P.; Emling, H.

1982-01-01

Two topics are addressed in this paper. First, we discuss the variation of shapes with spin and neutron number for nuclei in the N approx. = 88 transitional region. Second, we present comments on the feeding times of very high spin single-particle yrast states

Load balancing in highly parallel processing of Monte Carlo code for particle transport

International Nuclear Information System (INIS)

Higuchi, Kenji; Takemiya, Hiroshi; Kawasaki, Takuji

1998-01-01

In parallel processing of Monte Carlo (MC) codes for neutron, photon and electron transport problems, particle histories are assigned to processors making use of independency of the calculation for each particle. Although we can easily parallelize main part of a MC code by this method, it is necessary and practically difficult to optimize the code concerning load balancing in order to attain high speedup ratio in highly parallel processing. In fact, the speedup ratio in the case of 128 processors remains in nearly one hundred times when using the test bed for the performance evaluation. Through the parallel processing of the MCNP code, which is widely used in the nuclear field, it is shown that it is difficult to attain high performance by static load balancing in especially neutron transport problems, and a load balancing method, which dynamically changes the number of assigned particles minimizing the sum of the computational and communication costs, overcomes the difficulty, resulting in nearly fifteen percentage of reduction for execution time. (author)

Particle-number conservation in odd mass proton-rich nuclei in the isovector pairing case

International Nuclear Information System (INIS)

Fellah, M.; Allal, N.H.; Oudih, M.R.

2015-01-01

An expression of a wave function which describes odd–even systems in the isovector pairing case is proposed within the BCS approach. It is shown that it correctly generalizes the one used in the pairing between like-particles case. It is then projected on the good proton and neutron numbers using the Sharp-BCS (SBCS) method. The expressions of the expectation values of the particle-number operator and its square, as well as the energy, are deduced in both approaches. The formalism is applied to study the isovector pairing effect and the number projection one on the ground state energy of odd mass N ≈ Z nuclei using the single-particle energies of a deformed Woods–Saxon mean-field. It is shown that both effects on energy do not exceed 2%, however, the absolute deviations may reach several MeV. Moreover, the np pairing effect rapidly diminishes as a function of (N - Z). The deformation effect is also studied. It is shown that the np pairing effect, either before or after the projection, as well as the projection effect, when including or not the isovector pairing, depends upon the deformation. However, it seems that the predicted ground state deformation will remain the same in the four approaches. (author)

High-energy nuclear optics of polarized particles

CERN Document Server

Baryshevsky, Vladimir G

2012-01-01

The various phenomena caused by refraction and diffraction of polarized elementary particles in matter have opened up a new research area in the particle physics: nuclear optics of polarized particles. Effects similar to the well-known optical phenomena such as birefringence and Faraday effects, exist also in particle physics, though the particle wavelength is much less than the distance between atoms of matter. Current knowledge of the quasi-optical effects, which exist for all particles in any wavelength range (and energies from low to extremely high), will enable us to investigate different properties of interacting particles (nuclei) in a new aspect. This pioneering book will provide detailed accounts of quasi-optical phenomena in the particle polarization, and will interest physicists and professionals in experimental particle physics.

Effects of biodiesel, engine load and diesel particulate filter on nonvolatile particle number size distributions in heavy-duty diesel engine exhaust

International Nuclear Information System (INIS)

Young, Li-Hao; Liou, Yi-Jyun; Cheng, Man-Ting; Lu, Jau-Huai; Yang, Hsi-Hsien; Tsai, Ying I.; Wang, Lin-Chi; Chen, Chung-Bang; Lai, Jim-Shoung

2012-01-01

Highlights: ► The effects of waste cooking oil biodiesel, engine load and DOC + DPF on nonvolatile particle size distributions in HDDE exhaust. ► Increasing biodiesel blends cause slight decreases in the total particle number concentrations and negligible changes in size distributions. ► Increasing load results in modest increases in both the total particle number concentrations and sizes. ► The effects of semivolatile materials are strongest at idle, during which nonvolatile cores TOT ) decrease slightly, while the mode diameters show negligible changes with increasing biodiesel blends. For a given biodiesel blend, both the N TOT and mode diameters increase modestly with increasing load of above 25%. The N TOT at idle are highest and their size distributions are strongly affected by condensation and possible nucleation of semivolatile materials. Nonvolatile cores of diameters less than 16 nm are only observed at idle mode. The DOC + DPF shows remarkable filtration efficiency for both the core and soot particles, irrespective of the biodiesel blend and engine load under study. The N TOT post the DOC + DPF are comparable to typical ambient levels of ∼10 4 cm −3 . This implies that, without concurrent reductions of semivolatile materials, the formation of semivolatile nucleation mode particles post the aftertreatment is highly favored.

High-temperature LDV seed particle development

Science.gov (United States)

Frish, Michael B.; Pierce, Vicky G.

1989-05-01

The feasibility of developing a method for making monodisperse, unagglomerated spherical particles greater than 50 nm in diameter was demonstrated. Carbonaceous particles were made by pyrolyzing ethylene with a pulsed CO2 laser, thereby creating a non-equilibrium mixture of carbon, hydrogen, hydrocarbon vapors, and unpyrolyzed ethylene. Via a complex series of reactions, the carbon and hydrocarbon vapors quickly condensed into the spherical particles. By cooling and dispersing them in a supersonic expansion immediately after their creation, the hot newly-formed spheres were prevented from colliding and coalescing, thus preventing the problem of agglomeration which as plagued other investigators studying laser-simulated particle formation. The cold particles could be left suspended in the residual gases indefinitely without agglomerating. Their uniform sizes and unagglomerated nature were visualized by collecting the particles on filters that were subsequently examined using electron microscopy. It was found the mean particle size can be coarsely controlled by varying the initial ethylene pressure, and can be finely controlled by varying the fluence (energy/unit area) with which the laser irradiates the gas. The motivating application for this research was to manufacture particles that could be used as laser Doppler velocimetry (LDV) seeds in high-temperature high-speed flows. Though the particles made in this program will not evaporate until heated to about 3000 K, and thus could serve as LDV seeds in some applications, they are not ideal when the hot atmosphere is also oxidizing. In that situation, ceramic materials would be preferable. Research performed elsewhere has demonstrated that selected ceramic materials can be manufactured by laser pyrolysis of appropriate supply gases. It is anticipated that, when the same gases are used in conjunction with the rapid cooling technique, unagglomerated spherical ceramic particles can be made with little difficulty. Such

The Dynamics of Very High Alfvén Mach Number Shocks in Space Plasmas

Energy Technology Data Exchange (ETDEWEB)

Sundberg, Torbjörn; Burgess, David [School of Physics and Astronomy, Queen Mary University of London, London, E1 4NS (United Kingdom); Scholer, Manfred [Max-Planck-Institut für extraterrestrische Physik, Garching (Germany); Masters, Adam [The Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Sulaiman, Ali H., E-mail: torbjorn.sundberg@gmail.com [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

2017-02-10

Astrophysical shocks, such as planetary bow shocks or supernova remnant shocks, are often in the high or very-high Mach number regime, and the structure of such shocks is crucial for understanding particle acceleration and plasma heating, as well inherently interesting. Recent magnetic field observations at Saturn’s bow shock, for Alfvén Mach numbers greater than about 25, have provided evidence for periodic non-stationarity, although the details of the ion- and electron-scale processes remain unclear due to limited plasma data. High-resolution, multi-spacecraft data are available for the terrestrial bow shock, but here the very high Mach number regime is only attained on extremely rare occasions. Here we present magnetic field and particle data from three such quasi-perpendicular shock crossings observed by the four-spacecraft Cluster mission. Although both ion reflection and the shock profile are modulated at the upstream ion gyroperiod timescale, the dominant wave growth in the foot takes place at sub-proton length scales and is consistent with being driven by the ion Weibel instability. The observed large-scale behavior depends strongly on cross-scale coupling between ion and electron processes, with ion reflection never fully suppressed, and this suggests a model of the shock dynamics that is in conflict with previous models of non-stationarity. Thus, the observations offer insight into the conditions prevalent in many inaccessible astrophysical environments, and provide important constraints for acceleration processes at such shocks.

High energy particle experiment for the GEOTAIL mission

International Nuclear Information System (INIS)

1989-09-01

The high energy particle experiment for GEOTAIL mission was designed to understand the particle acceleration mechanism, energy flow, boundary dynamics and magnetic reconnection mechanism in the geotail region, solar flare particle acceleration mechanism, the propagation mechanism through interplanetary space, and the origin, lifetime and propagation mechanism of cosmic ray heavy ions. In order to achieve these objectives, particle detectors, burst detectors, medium energy isotope telescopes and a high energy isotope telescope will be placed in the spacecraft which will be launched in 1992 as one of the spacecraft missions in the International Solar Terrestrial Physics program. With these detectors, electrons, protons and helium, carbon, silicon and iron particles will be detected. The characteristics and the main technique used for each instrument to observe high energy particles are summarized. The details of the scientific objectives, the basic principle of particle identification, the electronic system and data processing system, key parameter information, telemetry data formats, preflight and in-flight calibration method and data an analysis plan are described in this report. (K.I.)

Gas-liquid transition in the model of particles interacting at high energy

International Nuclear Information System (INIS)

Bondarenko, S.; Komoshvili, K.

2013-01-01

An application of the ideas of the inertial confinement fusion process in the case of particles interacting at high energy is investigated. A possibility of the gas-liquid transition in the gas is considered using different approaches. In particular, a shock wave description of interactions between particles is studied and a self-similar solution of Euler's equation is discussed. Additionally, the Boltzmann equation is solved for a self-consistent field (Vlasov's equation) in the linear approximation for the case of a gas under external pressure and the corresponding change of the Knudsen number of the system is calculated. (orig.)

Application of the non-extensive statistical approach to high energy particle collisions

Science.gov (United States)

Bíró, Gábor; Barnaföldi, Gergely Gábor; Biró, Tamás Sándor; Ürmössy, Károly

2017-06-01

In high-energy collisions the number of created particles is far less than the thermodynamic limit, especially in small colliding systems (e.g. proton-proton). Therefore final-state effects and fluctuations in the one-particle energy distribution are appreciable. As a consequence the characterization of identified hadron spectra with the Boltzmann - Gibbs thermodynamical approach is insuffcient [1]. Instead particle spectra measured in high-energy collisions can be described very well with Tsallis -Pareto distributions, derived from non-extensive thermodynamics [2, 3]. Using the Tsallis q-entropy formula, a generalization of the Boltzmann - Gibbs entropy, we interpret the microscopic physics by analysing the Tsallis q and T parameters. In this paper we give a quick overview on these parameters, analyzing identified hadron spectra from recent years in a wide center-of-mass energy range. We demonstrate that the fitted Tsallis-parameters show dependency on the center-of-mass energy and particle species. Our findings are described well by a QCD inspired evolution ansatz. Based on this comprehensive study, apart from the evolution, both mesonic and barionic components found to be non-extensive (q > 1), beside the mass ordered hierarchy observed in parameter T.

Investigation of the Capture of Magnetic Particles From High-Viscosity Fluids Using Permanent Magnets.

Science.gov (United States)

Garraud, Alexandra; Velez, Camilo; Shah, Yash; Garraud, Nicolas; Kozissnik, Bettina; Yarmola, Elena G; Allen, Kyle D; Dobson, Jon; Arnold, David P

2016-02-01

This paper investigates the practicality of using a small, permanent magnet to capture magnetic particles out of high-viscosity biological fluids, such as synovial fluid. Numerical simulations are used to predict the trajectory of magnetic particles toward the permanent magnet. The simulations are used to determine a "collection volume" with a time-dependent size and shape, which determines the number of particles that can be captured from the fluid in a given amount of time. The viscosity of the fluid strongly influences the velocity of the magnetic particles toward the magnet, hence, the collection volume after a given time. In regards to the design of the magnet, the overall size is shown to most strongly influence the collection volume in comparison to the magnet shape or aspect ratio. Numerical results showed good agreement with in vitro experimental magnetic collection results. In the long term, this paper aims to facilitate optimization of the collection of magnetic particle-biomarker conjugates from high-viscosity biological fluids without the need to remove the fluid from a patient.

The high energy multicharged particle exposure of the microbial ecology evaluation device on board the Apollo 16 spacecraft

Science.gov (United States)

Benton, E. V.; Henke, R. P.

1973-01-01

The high energy multicharged cosmic-ray-particle exposure of the Microbial Ecology Evaluation Device package on board the Apollo 16 spacecraft was monitored using cellulose nitrate, Lexan polycarbonate, nuclear emulsion, and silver chloride crystal nuclear-track detectors. The results of the analysis of these detectors include the measured particle fluences, the linear energy transfer spectra, and the integral atomic number spectrum of stopping particle density. The linear energy transfer spectrum is used to compute the fractional cell loss in human kidney (T1) cells caused by heavy particles. Because the Microbial Ecology Evaluation Device was better shielded, the high-energy multicharged particle exposure was less than that measured on the crew passive dosimeters.

Multi-resolution Delta-plus-SPH with tensile instability control: Towards high Reynolds number flows

Science.gov (United States)

Sun, P. N.; Colagrossi, A.; Marrone, S.; Antuono, M.; Zhang, A. M.

2018-03-01

It is well known that the use of SPH models in simulating flow at high Reynolds numbers is limited because of the tensile instability inception in the fluid region characterized by high vorticity and negative pressure. In order to overcome this issue, the δ+-SPH scheme is modified by implementing a Tensile Instability Control (TIC). The latter consists of switching the momentum equation to a non-conservative formulation in the unstable flow regions. The loss of conservation properties is shown to induce small errors, provided that the particle distribution is regular. The latter condition can be ensured thanks to the implementation of a Particle Shifting Technique (PST). The novel variant of the δ+-SPH is proved to be effective in preventing the onset of tensile instability. Several challenging benchmark tests involving flows past bodies at large Reynolds numbers have been used. Within this a simulation characterized by a deforming foil that resembles a fish-like swimming body is used as a practical application of the δ+-SPH model in biological fluid mechanics.

The break-up of a viscous liquid drop in a high Reynolds number shear flow

Science.gov (United States)

Ng, Chin Hei; Aliseda, Alberto

2015-11-01

The break-up of a viscous liquid droplet in a sheared turbulent flow evolves in several steps, the most visually dominant of which is the formation of high aspect ratio ligaments. This feature takes them apart from the various break-up models based on the Hinze-Kolmogorov paradigm of eddy-spherical particle collisions. We investigate the development of ligaments in a high Reynolds number (up to 250,000) submerged round jet, within the high viscosity, near-unity density ratio regime. Unlike in H-K theory, applicable to the break-up of inviscid fluid particles, break-up of inertial-scale viscous droplets occurs through a sequence of eddy collisions and long-term deformation, as evidenced by measurements of the aspect ratio that fluctuates and increases progressively during the deformation stage, and results in non-binary break-up. Additionally, the ligament formation stretches a droplet to multiple times its original size, bringing the influence of integral-scale structures. High speed imaging has been statistically analyzed to inform and validate theoretical models for the break-up time and the break-up probability. In addition, a particle size scaling model has been developed and compared with the experimental measurements of the frozen-state particle size.

Statistical and direct decay of high-lying single-particle excitations

International Nuclear Information System (INIS)

Gales, S.

1993-01-01

Transfer reactions induced by hadronic probes at intermediate energies have revealed a rich spectrum of high-lying excitations embedded in the nuclear continuum. The investigation of their decay properties is believed to be a severe test of their microscopic structure as predicted by microscopic nuclear models. In addition the degree of damping of these simple modes in the nuclear continuum can be obtained by means of the measured particle (n,p) decay branching ratios. The neutron and proton decay studies of high-lying single-particle states in heavy nuclei are presented. (author). 13 refs., 9 figs

Fibre bundle varieties and the number of generations of elementary particles

International Nuclear Information System (INIS)

Ross, D.K.

1985-01-01

The idea is presented that the number of generations of elementary particles in a gauge theory characterised by a given Lie algebra is the same as the number of topologically distinct principal fibre bundles with a structure group having the same Lie algebra and R 3 -(0) as base space. Two different generations thus have a different global structure or 'twist' to their fibre bundles. It is found that at most three generations are allowed for groups with the same Lie algebra as E 6 , at most four generations for groups with the same Lie algebra as SOsub(41+2) with 1>=2, and at most n generations for groups with the same Lie algebra as SUsub(n). (author)

Trends in size classified particle number concentration in subtropical Brisbane, Australia, based on a 5 year study

Science.gov (United States)

Mejía, J. F.; Wraith, D.; Mengersen, K.; Morawska, L.

Particle number size distribution data in the range from 0.015 to 0.630 μm were collected over a 5-year period in the central business district (CBD) of Brisbane, Australia. Particle size distribution was summarised by total number concentration and number median diameter (NMD) as well as the number concentration of the 0.015-0.030 ( N15-30), 0.030-0.050 ( N30-50), 0.050-0.100 ( N50-100), 0.100-0.300 ( N100-300) and 0.300-0.630 ( N300-630) μm size classes. Morning (6:00-10:00) and afternoon (16:00-19:00) measurements, the former representing fresh traffic emissions (based on the local meteorological conditions) and the latter well-mixed emissions from the CBD, during weekdays were extracted and the respective monthly mean values were estimated for time series analysis. For all size fractions, average morning concentrations were about 1.5 higher than in the afternoon whereas NMD did not vary between the morning and afternoon. The trend and seasonal components were extracted through weighted linear regression models, using the monthly variance as weights. Only the morning measurements exhibited significant trends. During this time of the day, total particle number increased by 105.7% and the increase was greater for larger particles, resulting in a shift in NMD by 7.9%. Although no seasonal component was detected the evidence against it remained weak due to the limitations of the database.

The acceleration of particles to high energy

International Nuclear Information System (INIS)

Parker, E.N.

1976-01-01

The common occurrence, and often spectacular consequence, of fast particles in active astrophysical bodies has attracted the attention of physicists for more than four decades. The acceleration mechanisms, whatever they may be, are remarkably efficient, converting a major fraction of the total energy into fast particles. A variety of ideas have arisen, suggesting how and why fast particles are generated in various circumstances. The principal limitation on particle acceleration theories has been the realization that the universe in not filled with a hard vacuum, but rather is pervaded everywhere by tenuous ionized gases quite able to short circuit any large-scale electric fields that occur under ordinary circumstances. A number of the early ideas on the acceleration of cosmic rays have been discarded for this reason. The basic theoretical ideas can be grouped roughly into five parts: 1. hydromagnetic fields; 2. field in reduced conductivity; 3. plasma turbulence; 4. low frequency electromagnetic waves; 5. supernova explosion. Each of these is considered in turn. (Auth.)

Investigation of the two-quasiparticle bands in the doubly-odd nucleus 166Ta using a particle-number conserving cranked shell model

Science.gov (United States)

Zhang, ZhenHua

2016-07-01

The high-spin rotational properties of two-quasiparticle bands in the doubly-odd 166Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency hω are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.

Dragon kings of the deep sea: marine particles deviate markedly from the common number-size spectrum

NARCIS (Netherlands)

Bochdansky, A.B.; Clouse, M.A.; Herndl, G.

2016-01-01

Particles are the major vector for the transfer of carbon from the upper ocean to the deep sea. However, little is known about their abundance, composition and role at depths greater than 2000?m. We present the first number-size spectrum of bathy- and abyssopelagic particles to a depth of 5500?m

Some problems of high-energy elementary particle physics

International Nuclear Information System (INIS)

Isaev, P.S.

1995-01-01

The problems of high-energy elementary particle physics are discussed. It is pointed out that the modern theory of elementary-particle physics has no solutions of some large physical problems: origin of the mass, electric charge, identity of particle masses, change of the mass of elementary particles in time and others. 7 refs

Long term particle size distribution measurements at Mount Waliguan, a high-altitude site in inland China

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N. Kivekäs

2009-08-01

Full Text Available Particle number size distributions in size range 12–570 nm were measured continuously at Mount Waliguan, a remote mountain-top station in inland China. The station is located at the altitude of 3816 m a.s.l., and some 600–1200 m above the surrounding area. The measurement period lasted from September 2005 to May 2007. The measurements were verified with independent CPC measurements at the same site. The average particle concentration in ambient conditions was 2030 cm⁻³, which is higher than the values measured at similar altitude in other regions of the world. On average, the Aitken mode contributed to roughly half of the particle number concentration. The concentrations were found to be higher during the summer than during the winter. The diurnal variation was also investigated and a clear pattern was found for the nucleation mode during all seasons, so that the nucleation mode particle concentration increased in the afternoon. The same pattern was visible in the Aitken mode during the summer, whereas the accumulation mode did not show any level of diurnal pattern during any season. Excluding the nucleation mode, the average day-time particle concentrations were not significantly higher than those measured at night-time, indicating no systematic pattern of change between planetary boundary layer conditions and free troposphere conditions. In air masses coming from east, the number concentration of particles was higher than in other air masses, which indicates that the air mass might be affected anthropogenic pollution east of the station. Also other factors, such as active new-particle formation, keep aerosol number concentrations high in the area.

Study on Sumbawa gold ore liberation using rod mill: effect of rod-number and rotational speed on particle size distribution

Science.gov (United States)

Prasetya, A.; Mawadati, A.; Putri, A. M. R.; Petrus, H. T. B. M.

2018-01-01

Comminution is one of crucial steps in gold ore processing used to liberate the valuable minerals from gaunge mineral. This research is done to find the particle size distribution of gold ore after it has been treated through the comminution process in a rod mill with various number of rod and rotational speed that will results in one optimum milling condition. For the initial step, Sumbawa gold ore was crushed and then sieved to pass the 2.5 mesh and retained on the 5 mesh (this condition was taken to mimic real application in artisanal gold mining). Inserting the prepared sample into the rod mill, the observation on effect of rod-number and rotational speed was then conducted by variating the rod number of 7 and 10 while the rotational speed was varied from 60, 85, and 110 rpm. In order to be able to provide estimation on particle distribution of every condition, the comminution kinetic was applied by taking sample at 15, 30, 60, and 120 minutes for size distribution analysis. The change of particle distribution of top and bottom product as time series was then treated using Rosin-Rammler distribution equation. The result shows that the homogenity of particle size and particle size distribution is affected by rod-number and rotational speed. The particle size distribution is more homogeneous by increasing of milling time, regardless of rod-number and rotational speed. Mean size of particles do not change significantly after 60 minutes milling time. Experimental results showed that the optimum condition was achieved at rotational speed of 85 rpm, using rod-number of 7.

A role of valence particles number equal to 20

International Nuclear Information System (INIS)

Kumar, V.; Kumar, S.; Hasan, Z.; Kumar, D.; Pradeep; Koranga, B.S.; Kumar, S.; Negi, D.

2012-01-01

The importance of the N p N n parametrization was first demonstrated by Casten in connection with the role of the proton-neutron interaction in the growth of deformation away from shell closures, and there have subsequently been many developments in this theme. The symbols N p and N n are number of valence particles/holes of protons and neutrons, respectively (where nucleons are counted as holes beyond the middle of a major shell). The observables which reflect collective structure in the deformed mass region for even-even nuclei such as E(2 + ), R 4/2 ≡ E(4 + )/E(2 + ) and B(E2) have behaved smoothly with N p N n

Particle accelerators and lasers high energy sources

International Nuclear Information System (INIS)

Watteau, J.P.

1985-04-01

Particle accelerators and lasers are to-day precious devices for physicist and engineer. Their performance and scope do not stop growing. Producing thin beams of high energy particles or photons, they are able to be very high energy sources which interact strongly with matter. Numerous applications use them: research, industry, communication, medicine, agroalimentary, defence, and soon. In this note, their operation principles are described and some examples of their use as high energy sources are given [fr

Configuration mixing of mean-field wave functions projected on angular momentum and particle number: Application to 24Mg

International Nuclear Information System (INIS)

Valor, A.; Heenen, P.-H.; Bonche, P.

2000-01-01

We present in this paper the general framework of a method which permits to restore the rotational and particle number symmetries of wave functions obtained in Skyrme HF + BCS calculations. This restoration is nothing but a projection of mean-field intrinsic wave functions onto good particle number and good angular momentum. The method allows us also to mix projected wave functions. Such a configuration mixing is discussed for sets of HF + BCS intrinsic states generated in constrained calculations with suitable collective variables. This procedure gives collective states which are eigenstates of the particle number and the angular momentum operators and between which transition probabilities are calculated. An application to 24 Mg is presented, with mean-field wave functions generated by axial quadrupole constraints. Theoretical spectra and transition probabilities are compared to the experiment

Simultaneous projection of particle-number and angular momentum BCS wave-functions in the rare-earth nuclei

International Nuclear Information System (INIS)

Oudih, M.R.; Fellah, M.; Allal, N.H.; Benhamouda, N.

1999-01-01

It is well established that the BCS wave-functions are neither eigen-functions of the particle-number operator nor of the angular momentum operator. In a previous paper, we have developed a particle-number projection before variation method (of FBCS type). This discrete projection method is based on the SBCS wave-function. The aim of the present contribution is to perform a subsequent angular momentum projection by means of the Peierls-Yoccoz method. The general expression of the system energy, after the double projection, is established in the case of axial symmetry. For practical calculations, an approximation method is introduced. It leads to a semi-classical form of the rotational energy. The rotational spectra have been evaluated numerically for some even-even rare-earth nuclei. The single-particle energies and eigen-states are those of a deformed Woods-Saxon mean field. The obtained results are compared on one hand, to the experimental data, and on the other hand, to the theoretical spectra evaluated by a particle-number projection after variation method (of PBCS type). For all studied nuclei, the spectra determined by the FBCS method reproduce the experimental data better than those of the PBCS method. However, even if the present method is satisfying for low angular momenta, the agreement with the experimental data is lesser for I ≥ 8, particularly for the lighter studied nuclei. (authors)

Decay properties of high-lying single-particles modes

NARCIS (Netherlands)

Beaumel, D; Fortier, S; Gales, S; Guillot, J; LangevinJoliot, H; Laurent, H; Maison, JM; Vernotte, J; Bordewijck, J; Brandenburg, S; Krasznahorkay, A; Crawley, GM; Massolo, CP; Renteria, M; Khendriche, A

1996-01-01

The neutron decay of high-lying single-particle states in Ni-64, Zr-90, Sn-120 and (208)pb excited by means of the (alpha,He-3) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular

Surgical smoke and ultrafine particles

Directory of Open Access Journals (Sweden)

Nowak Dennis

2008-12-01

Full Text Available Abstract Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine ( Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc. was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3 of particles in the diameter range of 10 nm to 1 μm. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure.

Effects of the virtual particle number on the S matrix of the (phi4)/sub 1+1/ model

International Nuclear Information System (INIS)

Kroeger, H.; Girard, R.; Dufour, G.

1987-01-01

We present results of the S matrix in the (phi 4 )/sub 1 + 1/ model obtained by a nonperturbative calculation using a momentum-space discretization technique. First, we calculate the two-body S matrix in the strong-coupling regime (up to λ/sub eff/ = 3), with the restriction of taking into account only two-body virtual particle states. We find agreement with standard perturbation theory obtained by summing up the corresponding graphs to infinite order. We also estimate the effect of mass renormalization. Second, we investigate the effect of including higher virtual particle numbers in two-particle scattering in the cases λ/sub eff/ = (1/6) and λ/sub eff/ = 1. In both cases we find convergence of the S matrix with respect to increasing the virtual-particle-number cutoff

Colloids exposed to random potential energy landscapes: From particle number density to particle-potential and particle-particle interactions

International Nuclear Information System (INIS)

Bewerunge, Jörg; Capellmann, Ronja F.; Platten, Florian; Egelhaaf, Stefan U.; Sengupta, Ankush; Sengupta, Surajit

2016-01-01

Colloidal particles were exposed to a random potential energy landscape that has been created optically via a speckle pattern. The mean particle density as well as the potential roughness, i.e., the disorder strength, were varied. The local probability density of the particles as well as its main characteristics were determined. For the first time, the disorder-averaged pair density correlation function g (1) (r) and an analogue of the Edwards-Anderson order parameter g (2) (r), which quantifies the correlation of the mean local density among disorder realisations, were measured experimentally and shown to be consistent with replica liquid state theory results.

Nested high voltage generator/particle accelerator

International Nuclear Information System (INIS)

Adler, R.J.

1992-01-01

This patent describes a modular high voltage particle accelerator having an emission axis and an emission end, the accelerator. It comprises: a plurality of high voltage generators in nested adjacency to form a nested stack, each the generator comprising a cup-like housing having a base and a tubular sleeve extending from the base, a primary transformer winding encircling the nested stack; a secondary transformer winding between each adjacent pair of housings, magnetically linked to the primary transformer winding through the gaps; a power supply respective to each of the secondary windings converting alternating voltage from its respective secondary winding to d.c. voltage, the housings at the emission end forming a hollow throat for particle acceleration, a vacuum seal at the emission end of the throat which enables the throat to be evacuated; a particle source in the thrond power means to energize the primary transformer winding

High Pressure Quick Disconnect Particle Impact Tests

Science.gov (United States)

Rosales, Keisa R.; Stoltzfus, Joel M.

2009-01-01

NASA Johnson Space Center White Sands Test Facility (WSTF) performed particle impact testing to determine whether there is a particle impact ignition hazard in the quick disconnects (QDs) in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). Testing included standard supersonic and subsonic particle impact tests on 15-5 PH stainless steel, as well as tests performed on a QD simulator. This paper summarizes the particle impact tests completed at WSTF. Although there was an ignition in Test Series 4, it was determined the ignition was caused by the presence of a machining imperfection. The sum of all the test results indicates that there is no particle impact ignition hazard in the ISS ECLSS QDs. KEYWORDS: quick disconnect, high pressure, particle impact testing, stainless steel

Three-Dimensional Interaction of a Large Number of Dense DEP Particles on a Plane Perpendicular to an AC Electrical Field

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Chuanchuan Xie

2017-01-01

Full Text Available The interaction of dielectrophoresis (DEP particles in an electric field has been observed in many experiments, known as the “particle chains phenomenon”. However, the study in 3D models (spherical particles is rarely reported due to its complexity and significant computational cost. In this paper, we employed the iterative dipole moment (IDM method to study the 3D interaction of a large number of dense DEP particles randomly distributed on a plane perpendicular to a uniform alternating current (AC electric field in a bounded or unbounded space. The numerical results indicated that the particles cannot move out of the initial plane. The similar particles (either all positive or all negative DEP particles always repelled each other, and did not form a chain. The dissimilar particles (a mixture of positive and negative DEP particles always attracted each other, and formed particle chains consisting of alternately arranged positive and negative DEP particles. The particle chain patterns can be randomly multitudinous depending on the initial particle distribution, the electric properties of particles/fluid, the particle sizes and the number of particles. It is also found that the particle chain patterns can be effectively manipulated via tuning the frequency of the AC field and an almost uniform distribution of particles in a bounded plane chip can be achieved when all of the particles are similar, which may have potential applications in the particle manipulation of microfluidics.

High performance stream computing for particle beam transport simulations

International Nuclear Information System (INIS)

Appleby, R; Bailey, D; Higham, J; Salt, M

2008-01-01

Understanding modern particle accelerators requires simulating charged particle transport through the machine elements. These simulations can be very time consuming due to the large number of particles and the need to consider many turns of a circular machine. Stream computing offers an attractive way to dramatically improve the performance of such simulations by calculating the simultaneous transport of many particles using dedicated hardware. Modern Graphics Processing Units (GPUs) are powerful and affordable stream computing devices. The results of simulations of particle transport through the booster-to-storage-ring transfer line of the DIAMOND synchrotron light source using an NVidia GeForce 7900 GPU are compared to the standard transport code MAD. It is found that particle transport calculations are suitable for stream processing and large performance increases are possible. The accuracy and potential speed gains are compared and the prospects for future work in the area are discussed

Phase transitions in ideal and weakly interacting Bose gases with a finite number of particles confined in a box

International Nuclear Information System (INIS)

Wang Jianhui; Ma Yongli

2009-01-01

We generalize the scheme to characterize phase transitions of finite systems in a complex temperature plane and approach the classifications of phase transitions in ideal and weakly interacting Bose gases of a finite number of particles, confined in a cubic box of volume L 3 with different boundary conditions. For this finite ideal Bose system, by extending the classification parameters to all regions, we predict that the phase transition for periodic boundary conditions is of second order, while the transition in Dirichlet boundary conditions is of first order. For a weakly interacting Bose gas with periodic boundary conditions, we discuss the effects of finite particle numbers and inter-particle interactions on the nature of the phase transitions. We show that this homogenous weakly interacting Bose gas undergoes a second-order phase transition, which is in accordance with universality arguments for infinite systems. We also discuss the dependence of transition temperature on interaction strengths and particle numbers.

Development and testing of high performance pseudo random number generator for Monte Carlo simulation

International Nuclear Information System (INIS)

Chakraborty, Brahmananda

2009-01-01

Random number plays an important role in any Monte Carlo simulation. The accuracy of the results depends on the quality of the sequence of random numbers employed in the simulation. These include randomness of the random numbers, uniformity of their distribution, absence of correlation and long period. In a typical Monte Carlo simulation of particle transport in a nuclear reactor core, the history of a particle from its birth in a fission event until its death by an absorption or leakage event is tracked. The geometry of the core and the surrounding materials are exactly modeled in the simulation. To track a neutron history one needs random numbers for determining inter collision distance, nature of the collision, the direction of the scattered neutron etc. Neutrons are tracked in batches. In one batch approximately 2000-5000 neutrons are tracked. The statistical accuracy of the results of the simulation depends on the total number of particles (number of particles in one batch multiplied by the number of batches) tracked. The number of histories to be generated is usually large for a typical radiation transport problem. To track a very large number of histories one needs to generate a long sequence of independent random numbers. In other words the cycle length of the random number generator (RNG) should be more than the total number of random numbers required for simulating the given transport problem. The number of bits of the machine generally limits the cycle length. For a binary machine of p bits the maximum cycle length is 2 p . To achieve higher cycle length in the same machine one has to use either register arithmetic or bit manipulation technique

Novel results in particle physics. AIP conference proceedings number 93; particle and fields subseries No. 27

International Nuclear Information System (INIS)

Panvini, R.S.; Alam, M.S.; Csorna, S.E.

1982-09-01

Topics include free quark searches, axions, charmed particle lifetimes, a composite model of the weak interactions, e + e - interactions, neutrino and beam dump experiments, grand unified theories, proton decay, neutrino oscillations, and high energy p anti p interactions. Separate entries were made in the data base for the papers presented

Tight coupling of particle size, number and composition in atmospheric cloud droplet activation

Directory of Open Access Journals (Sweden)

D. O. Topping

2012-04-01

Full Text Available The substantial uncertainty in the indirect effect of aerosol particles on radiative forcing in large part arises from the influences of atmospheric aerosol particles on (i the brightness of clouds, exerting significant shortwave cooling with no appreciable compensation in the long wave, and on (ii their ability to precipitate, with implications for cloud cover and lifetime.

Predicting the ambient conditions at which aerosol particles may become cloud droplets is largely reliant on an equilibrium relationship derived by Köhler (1936. However, the theoretical basis of the relationship restricts its application to particles solely comprising involatile compounds and water, whereas a substantial fraction of particles in the real atmosphere will contain potentially thousands of semi-volatile organic compounds in addition to containing semi-volatile inorganic components such as ammonium nitrate.

We show that equilibration of atmospherically reasonable concentrations of organic compounds with a growing particle as the ambient humidity increases has potentially larger implications on cloud droplet formation than any other equilibrium compositional dependence, owing to inextricable linkage between the aerosol composition, a particles size and concentration under ambient conditions.

Whilst previous attempts to account for co-condensation of gases other than water vapour have been restricted to one inorganic condensate, our method demonstrates that accounting for the co-condensation of any number of organic compounds substantially decreases the saturation ratio of water vapour required for droplet activation. This effect is far greater than any other compositional dependence; more so even than the unphysical effect of surface tension reduction in aqueous organic mixtures, ignoring differences in bulk and surface surfactant concentrations.

Identified particle yield associated with a high-$p_T$ trigger particle at the LHC

CERN Document Server

Veldhoen, Misha; van Leeuwen, Marco

Identified particle production ratios are important observables, used to constrain models of particle production in heavy-ion collisions. Measurements of the inclusive particle ratio in central heavy-ion collisions showed an increase of the baryon-to-meson ratio compared to proton-proton collisions at intermediate pT, the so-called baryon anomaly. One possible explanation of the baryon anomaly is that partons from the thermalized deconfined QCD matter hadronize in a different way compared to hadrons produced in a vacuum jet. In this work we extend on previous measurements by measuring particle ratios in the yield associated with a high-pT trigger particle. These measurements can potentially further constrain the models of particle production since they are sensitive to the difference between particles from a jet and particles that are produced in the bulk. We start by developing a particle identification method that uses both the specific energy loss of a particle and the time of flight. From there, we presen...

Number-unconstrained quantum sensing

Science.gov (United States)

Mitchell, Morgan W.

2017-12-01

Quantum sensing is commonly described as a constrained optimization problem: maximize the information gained about an unknown quantity using a limited number of particles. Important sensors including gravitational wave interferometers and some atomic sensors do not appear to fit this description, because there is no external constraint on particle number. Here, we develop the theory of particle-number-unconstrained quantum sensing, and describe how optimal particle numbers emerge from the competition of particle-environment and particle-particle interactions. We apply the theory to optical probing of an atomic medium modeled as a resonant, saturable absorber, and observe the emergence of well-defined finite optima without external constraints. The results contradict some expectations from number-constrained quantum sensing and show that probing with squeezed beams can give a large sensitivity advantage over classical strategies when each is optimized for particle number.

Effects of the Reynolds number on two-dimensional dielectrophoretic motions of a pair of particles under a uniform electric field

International Nuclear Information System (INIS)

Kang, Sang Mo; Mannoor, Madhusoodanan; Maniyeri, Ranjith Maniyeri

2016-01-01

This paper presents two-dimensional direct numerical simulations to explore the effect of the Reynolds number on the Dielectrophoretic (DEP) motion of a pair of freely suspended particles in an unbounded viscous fluid under an external uniform electric field. Accordingly, the electric potential is obtained by solving the Maxwell'00s equation with a great sudden change in the electric conductivity at the particle-fluid interface and then the Maxwell stress tensor is integrated to determine the DEP force exerted on each particle. The fluid flow and particle movement, on the other hand, are predicted by solving the continuity and Navier-Stokes equations together with the kinetic equations. Numerical simulations are carried out using a finite volume approach, composed of a sharp interface method for the electric potential and a direct-forcing immersed-boundary method for the fluid flow. Through the simulations, it is found that both particles with the same sign of the conductivity revolve and eventually align themselves in a line with the electric field. With different signs, to the contrary, they revolve in the reverse way and eventually become lined up at a right angle with the electric field. The DEP motion also depends significantly on the Reynolds number defined based on the external electric field for all the combinations of the conductivity signs. When the Reynolds number is approximately below Re cr ≈ 0.1, the DEP motion becomes independent of the Reynolds number and thus can be exactly predicted by the no-inertia solver that neglects all the inertial and convective effects. With increasing Reynolds number above the critical number, on the other hand, the particles trace larger trajectories and thus take longer time during their revolution to the eventual in-line alignment.

Effects of the Reynolds number on two-dimensional dielectrophoretic motions of a pair of particles under a uniform electric field

Energy Technology Data Exchange (ETDEWEB)

Kang, Sang Mo; Mannoor, Madhusoodanan [Dong-A University, Busan (Korea, Republic of); Maniyeri, Ranjith Maniyeri [National Institute of Technology Karnataka, Mangalore (India)

2016-07-15

This paper presents two-dimensional direct numerical simulations to explore the effect of the Reynolds number on the Dielectrophoretic (DEP) motion of a pair of freely suspended particles in an unbounded viscous fluid under an external uniform electric field. Accordingly, the electric potential is obtained by solving the Maxwell'00s equation with a great sudden change in the electric conductivity at the particle-fluid interface and then the Maxwell stress tensor is integrated to determine the DEP force exerted on each particle. The fluid flow and particle movement, on the other hand, are predicted by solving the continuity and Navier-Stokes equations together with the kinetic equations. Numerical simulations are carried out using a finite volume approach, composed of a sharp interface method for the electric potential and a direct-forcing immersed-boundary method for the fluid flow. Through the simulations, it is found that both particles with the same sign of the conductivity revolve and eventually align themselves in a line with the electric field. With different signs, to the contrary, they revolve in the reverse way and eventually become lined up at a right angle with the electric field. The DEP motion also depends significantly on the Reynolds number defined based on the external electric field for all the combinations of the conductivity signs. When the Reynolds number is approximately below Re{sub cr} ≈ 0.1, the DEP motion becomes independent of the Reynolds number and thus can be exactly predicted by the no-inertia solver that neglects all the inertial and convective effects. With increasing Reynolds number above the critical number, on the other hand, the particles trace larger trajectories and thus take longer time during their revolution to the eventual in-line alignment.

Structure of proton-proton events at high center-of-mass energy with an identified particle of large transverse momentum

International Nuclear Information System (INIS)

Hanke, P.

1977-01-01

At the CERN-ISR events of pp-collisions, in which particles of large transverse momentum psub(T) are produced, were studied at √S = 52 GeV center-of-mass energy, using the 'Split-Field'-magnetspectrometer. The lorentz-invariant production cross-section of positive particles with high psub(T) was measured in the fragmentation region (average* approximately 20 0 ). In the same kinematical region the pion-fraction of produced particles for both charges was determined. In these events the effect of 'strangeness'-conservation on the dynamics of additionally produced particles was investigated. The comparison of events with negative pions and events with heavier particles - mainly kaons - at high psub(T) indicates, that the compensation of transverse momentum does not depend on the 'strangeness' of the particle at high psub(T). The quantum-number conservation rather influences the particle-content from the hadronic rest inside longitudinal phase-space. This was shown by reconstruction of decay-vertices of neutral kaons. The results obtained can be interpreted by 'constituent'-models of the proton-structure. (orig.) [de

High-LET charged particle radiotherapy

International Nuclear Information System (INIS)

Castro, J.R.; California Univ., San Francisco, CA

1991-07-01

The Department of Radiation Oncology at UCSF Medical Center and the Radiation Oncology Department at UC Lawrence Berkeley Laboratory have been evaluating the use of high LET charged particle radiotherapy in a Phase 1--2 research trial ongoing since 1979. In this clinical trail, 239 patients have received at least 10 Gy (physical) minimum tumor dose with neon ions, meaning that at least one-half of their total treatment was given with high-LET charged particle therapy. Ninety-one patients received all of their therapy with neon ions. Of the 239 patients irradiated, target sites included lesions in the skin, subcutaneous tissues, head and neck such as paranasal sinuses, nasopharynx and salivary glands (major and minor), skull base and juxtaspinal area, GI tract including esophagus, pancreas and biliary tract, prostate, lung, soft tissue and bone. Analysis of these patients has been carried out with a minimum followup period of 2 years

Aerosol formation from high-velocity uranium drops: Comparison of number and mass distributions. Final report

Energy Technology Data Exchange (ETDEWEB)

Rader, D.J.; Benson, D.A.

1995-05-01

This report presents the results of an experimental study of the aerosol produced by the combustion of high-velocity molten-uranium droplets produced by the simultaneous heating and electromagnetic launch of uranium wires. These tests are intended to simulate the reduction of high-velocity fragments into aerosol in high-explosive detonations or reactor accidents involving nuclear materials. As reported earlier, the resulting aerosol consists mainly of web-like chain agglomerates. A condensation nucleus counter was used to investigate the decay of the total particle concentration due to coagulation and losses. Number size distributions based on mobility equivalent diameter obtained soon after launch with a Differential Mobility Particle Sizer showed lognormal distributions with an initial count median diameter (CMD) of 0.3 {mu}m and a geometric standard deviation, {sigma}{sub g} of about 2; the CMD was found to increase and {sigma}{sub g} decrease with time due to coagulation. Mass size distributions based on aerodynamic diameter were obtained for the first time with a Microorifice Uniform Deposit Impactor, which showed lognormal distributions with mass median aerodynamic diameters of about 0.5 {mu}m and an aerodynamic geometric standard deviation of about 2. Approximate methods for converting between number and mass distributions and between mobility and aerodynamic equivalent diameters are presented.

Aerosol formation from high-velocity uranium drops: Comparison of number and mass distributions. Final report

International Nuclear Information System (INIS)

Rader, D.J.; Benson, D.A.

1995-05-01

This report presents the results of an experimental study of the aerosol produced by the combustion of high-velocity molten-uranium droplets produced by the simultaneous heating and electromagnetic launch of uranium wires. These tests are intended to simulate the reduction of high-velocity fragments into aerosol in high-explosive detonations or reactor accidents involving nuclear materials. As reported earlier, the resulting aerosol consists mainly of web-like chain agglomerates. A condensation nucleus counter was used to investigate the decay of the total particle concentration due to coagulation and losses. Number size distributions based on mobility equivalent diameter obtained soon after launch with a Differential Mobility Particle Sizer showed lognormal distributions with an initial count median diameter (CMD) of 0.3 μm and a geometric standard deviation, σ g of about 2; the CMD was found to increase and σ g decrease with time due to coagulation. Mass size distributions based on aerodynamic diameter were obtained for the first time with a Microorifice Uniform Deposit Impactor, which showed lognormal distributions with mass median aerodynamic diameters of about 0.5 μm and an aerodynamic geometric standard deviation of about 2. Approximate methods for converting between number and mass distributions and between mobility and aerodynamic equivalent diameters are presented

Particle correlations in high-multiplicity reactions

International Nuclear Information System (INIS)

Hayot, Fernand.

1976-01-01

A comprehensive review of the results obtained in the study of short range correlations in high-multiplicity events is presented: introduction of the fundamental short-range order hypothesis, introduction of clusters in nondiffractive events (only the production of identical, independent, and neutral clusters was considered); search for short range dynamical effects between particles coming from the decay of a same cluster by studying two-particle rapidity correlations in inclusive and semi-inclusive experiments; study of transverse momentum correlations [fr

Power Supplies for High Energy Particle Accelerators

Science.gov (United States)

Dey, Pranab Kumar

2016-06-01

The on-going research and the development projects with Large Hadron Collider at CERN, Geneva, Switzerland has generated enormous enthusiasm and interest amongst all to know about the ultimate findings on `God's Particle'. This paper has made an attempt to unfold the power supply requirements and the methodology adopted to provide the stringent demand of such high energy particle accelerators during the initial stages of the search for the ultimate particles. An attempt has also been made to highlight the present status on the requirement of power supplies in some high energy accelerators with a view that, precautionary measures can be drawn during design and development from earlier experience which will be of help for the proposed third generation synchrotron to be installed in India at a huge cost.

Chaotic sedimentation of particle pairs in a vertical channel at low Reynolds number: Multiple states and routes to chaos

Science.gov (United States)

Verjus, Romuald; Guillou, Sylvain; Ezersky, Alexander; Angilella, Jean-Régis

2016-12-01

The sedimentation of a pair of rigid circular particles in a two-dimensional vertical channel containing a Newtonian fluid is investigated numerically, for terminal particle Reynolds numbers (ReT) ranging from 1 to 10, and for a confinement ratio equal to 4. While it is widely admitted that sufficiently inertial pairs should sediment by performing a regular DKT oscillation (Drafting-Kissing-Tumbling), the present analysis shows in contrast that a chaotic regime can also exist for such particles, leading to a much slower sedimentation velocity. It consists of a nearly horizontal pair, corresponding to a maximum effective blockage ratio, and performing a quasiperiodic transition to chaos while increasing the particle weight. For less inertial regimes, the classical oblique doublet structure and its complex behavior (multiple stable states and hysteresis, period-doubling cascade and chaotic attractor) are recovered, in agreement with previous work [Aidun, C. K. and Ding, E.-J., "Dynamics of particle sedimentation in a vertical channel: Period-doubling bifurcation and chaotic state," Phys. Fluids 15, 1612 (2003)]. As a consequence of these various behaviors, the link between the terminal Reynolds number and the non-dimensional driving force is complex: it contains several branches displaying hysteresis as well as various bifurcations. For the range of Reynolds number considered here, a global bifurcation diagram is given.

100 years of elementary particles [Beam Line, vol. 27, number 1, Spring 1997

International Nuclear Information System (INIS)

Pais, Abraham; Weinberg, Steven; Quigg, Chris; Riordan, Michael; Panofsky, Wolfgang K.H.; Trimble, Virginia

1997-01-01

This issue of Beam Line commemorates the 100th anniversary of the April 30, 1897 report of the discovery of the electron by J.J. Thomson and the ensuing discovery of other subatomic particles. In the first three articles, theorists Abraham Pais, Steven Weinberg, and Chris Quigg provide their perspectives on the discoveries of elementary particles as well as the implications and future directions resulting from these discoveries. In the following three articles, Michael Riordan, Wolfgang Panofsky, and Virginia Trimble apply our knowledge about elementary particles to high-energy research, electronics technology, and understanding the origin and evolution of our Universe

Comparison of sources of submicron particle number concentrations measured at two sites in Rochester, NY.

Science.gov (United States)

Kasumba, John; Hopke, Philip K; Chalupa, David C; Utell, Mark J

2009-09-01

Sources contributing to the submicron particles (100-470 nm) measured between January 2002 and December 2007 at two different New York State Department of Environmental Conservation (NYS DEC) sites in Rochester, NY were identified and apportioned using a bilinear receptor model, positive matrix factorization (PMF). Measurements of aerosol size distributions and number concentrations for particles in the size range of 10-500 nm have been made since December 2001 to date in Rochester. The measurements are being made using a scanning mobility particle sizer (SMPS) consisting of a DMA and a CPC (TSI models 3071 and 3010, respectively). From December 2001 to March 2004, particle measurements were made at the NYS DEC site in downtown Rochester, but it was moved to the eastside of Rochester in May 2004. Each measurement period was divided into three seasons i.e., winter (December, January, and February), summer (June, July, and August), and the transitional periods (March, April, May, September, October, and November) so as to avoid experimental uncertainty resulting from too large season-to-season variability in ambient temperature and solar photon intensity that would lead to unstable/non-stationary size distributions. Therefore, the seasons were analyzed independently for possible sources. Ten sources were identified at both sites and these include traffic, nucleation, residential/commercial heating, industrial emissions, secondary nitrate, ozone- rich secondary aerosol, secondary sulfate, regionally transported aerosol, and a mixed source of nucleation and traffic. These results show that the measured total outdoor particle number concentrations in Rochester generally vary with similar temporal patterns, suggesting that the central monitoring site data can be used to estimate outdoor exposure in other parts of the city.

Use of a generalized Stokes number to determine the aerodynamic capture efficiency of non-Stokesian particles from a compressible gas flow

Science.gov (United States)

Israel, R.; Rosner, D. E.

1983-01-01

The aerodynamic capture efficiency of small but nondiffusing particles suspended in a high-speed stream flowing past a target is known to be influenced by parameters governing small particle inertia, departures from the Stokes drag law, and carrier fluid compressibility. By defining an effective Stokes number in terms of the actual (prevailing) particle stopping distance, local fluid viscosity, and inviscid fluid velocity gradient at the target nose, it is shown that these effects are well correlated in terms of a 'standard' (cylindrical collector, Stokes drag, incompressible flow, sq rt Re much greater than 1) capture efficiency curve. Thus, a correlation follows that simplifies aerosol capture calculations in the parameter range already included in previous numerical solutions, allows rational engineering predictions of deposition in situations not previously specifically calculated, and should facilitate the presentation of performance data for gas cleaning equipment and aerosol instruments.

Big Bang Day: 5 Particles - 3. The Anti-particle

CERN Multimedia

Franck Close

2008-01-01

Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 3. The Anti-particle. It appears to be the stuff of science fiction. Associated with every elementary particle is an antiparticle which has the same mass and opposite charge. Should the two meet and combine, the result is annihilation - and a flash of light. Thanks to mysterious processes that occurred after the Big Bang there are a vastly greater number of particles than anti-particles. So how could their elusive existence be proved? At CERN particle physicists are crashing together subatomic particles at incredibly high speeds to create antimatter, which they hope will finally reveal what happened at the precise moment of the Big Bang to create the repertoire of elementary particles and antiparticles in existence today.

Dedicated Trigger for Highly Ionising Particles at ATLAS

CERN Document Server

Katre, Akshay; The ATLAS collaboration

2015-01-01

In 2012, a novel strategy was designed to detect signatures of Highly Ionising Particles (HIPs) such as magnetic monopoles, dyons or Qballs with the ATLAS trigger system. With proton-proton collisions at a centre of mass enegy of 8 TeV, the trigger was designed to have unique properties as a tracker for HIPs. It uses only the Transition Radiation Tracker (TRT) system, applying an algorithm distinct from standard tracking ones. The unique high threshold readout capability of the TRT is used at the location where HIPs in the detector are looked for. In particular the number and the fraction of TRT high threshold hits is used to distinguish HIPs from background processes. The trigger requires significantly lower energy depositions in the electro-magnetic calorimeters as a seed unlike previously used trigger algorithms for such searches. Thus the new trigger is capable of probing a large range of HIP masses and charges. We will give a description of the algorithms for this newly developed trigger for HIP searches...

Hard scattering contribution to particle production in high energy heavy-ion collisions

International Nuclear Information System (INIS)

Pareek, Pooja; Mishra, Aditya Nath; Sahoo, Pragati; Sahoo, Raghunath

2014-01-01

Global observables like the multiplicity of produced charged particles and transverse energy, are the key observables used to characterize the properties of the matter created in heavy-ion collisions. In order to study the dependence of the charged particle density on colliding system, center of mass energy and collision centrality, there have been measurements starting few GeV to TeV energies at LHC. There is a need to understand the particle production contribution coming from the QCD hard processes, which scale with number of binary nucleon-nucleon collisions, N coll and soft processes scaling with number of participant nucleons, N part

Mathematical Relationship Between Particle Reynolds Number and Ripple Factor using Tapi River Data, India.

Directory of Open Access Journals (Sweden)

S. M. Yadav

2011-02-01

Full Text Available The computation of bed load allows for the fact that only part of the shear stress is used for transport of sediments and some of the shear stress is wasted in overcoming the resistance due to bed forms therefore the total shear stress developed in the open channel requires correction in the form of correction factor called ripple factor. Different methods have been followed for correcting the actual shear stress in order to compute the sediment load. Correction factors are based on particular characteristics grain size of particle. In the present paper the ripple factor has been obtained for non uniform bed material considering the various variables like discharge, hydraulic mean depth, flow velocity, bed slope, average diameter of particle etc. by collecting the field data of Tapi river for 15 years for a particular gauging station. The ripple factor is obtained using Meyer Peter and Muller formula, Einstein Formula, Kalinske’s formula, Du Boy’s formula, Shield’s formula, Bagnold’s formula, average of six formulae and multiple regression analysis. The variation of ripple factor with particle Reynolds Number is studied. The ripple factor obtained by different approaches are further analyzed using Origin software and carrying out multiple regression on the 15 years of data with more than 10 parameters, ripple factor by multiple regression has been obtained. These values are further analysed and giving statistical mean to the parameters a relationship of power form has been developed. The ripple factor increases with the increase in the value of Particle Reynolds number. The large deviation is observed in case of Kalinske’s approach when compare with other approaches

Constraints on the Dark Matter Particle Mass from the Number of Milky Way Satellites

Science.gov (United States)

2010-04-12

assuming dark matter only simulations (we do not include the effect of baryons in our simulations). We adopted values for cosmological parameters from the...ar X iv :1 00 4. 14 59 v1 [ as tr o- ph .C O ] 9 A pr 2 01 0 Constraints on the Dark Matter Particle Mass from the Number of Milky Way...simulations of the growth of Milky Way-sized halos in cold and warm dark matter cosmologies. The number of dark matter satellites in our simulated Milky

Why is solar cycle 24 an inefficient producer of high-energy particle events?

Science.gov (United States)

Vainio, Rami; Raukunen, Osku; Tylka, Allan J.; Dietrich, William F.; Afanasiev, Alexandr

2017-08-01

Aims: The aim of the study is to investigate the reason for the low productivity of high-energy SEPs in the present solar cycle. Methods: We employ scaling laws derived from diffusive shock acceleration theory and simulation studies including proton-generated upstream Alfvén waves to find out how the changes observed in the long-term average properties of the erupting and ambient coronal and/or solar wind plasma would affect the ability of shocks to accelerate particles to the highest energies. Results: Provided that self-generated turbulence dominates particle transport around coronal shocks, it is found that the most crucial factors controlling the diffusive shock acceleration process are the number density of seed particles and the plasma density of the ambient medium. Assuming that suprathermal populations provide a fraction of the particles injected to shock acceleration in the corona, we show that the lack of most energetic particle events as well as the lack of low charge-to-mass ratio ion species in the present cycle can be understood as a result of the reduction of average coronal plasma and suprathermal densities in the present cycle over the previous one.

The development of Micromegas for high particle-flux environments

International Nuclear Information System (INIS)

Giomataris, Y.; Mangeot, Ph.; Rebourgeard, Ph.; Robert, J.P.

1996-01-01

Detectors able to operate in high rate environments, with particle flux beyond 10 14 particles/mm 2 /s, are needed for future high energy physics projects and medical radiography. A new promising technique called Micromegas has been proposed. It consists of a 2-stage parallel-plate avalanche chamber of small amplification gap (100 μm) combined with a conversion-drift space. In this paper we present results obtained with such a detector and we see that the detector combines most of the qualities required for high-rate position-sensitive particle detection, particularly it shows excellent spatial and energy resolutions. (author)

Number Size Distributions and Seasonality of Submicron Particles in Europe 2008–2009

Czech Academy of Sciences Publication Activity Database

Asmi, A.; Wiedensohler, A.; Laj, P.; Fjaeraa, A.-M.; Sellegri, K.; Birmili, W.; Weingartner, E.; Baltensperger, U.; Ždímal, Vladimír; Zíková, Naděžda; Putaud, J.-P.; Marioni, A.; Tunved, P.; Hansson, H.-C.; Fiebig, M.; Kivekäs, N.; Lihavainen, H.; Asmi, E.; Ulevicius, V.; Aalto, P.P.; Swietlicki, E.; Kristensson, E.; Mihalopoulos, N.; Kalivitis, N.; Kalapov, I.; Kiss, G.; de Leeuw, G.; Henzig, B.; Harrison, R. M.; Beddows, D.; O´Dowd, C.; Jennings, S.G.; Flentje, H.; Weinhold, K.; Meinhardt, F.; Ries, L.; Kulmala, M.

2011-01-01

Roč. 11, - (2011), s. 5505-5538 ISSN 1680-7316 EU Projects: European Commission(XE) RII3-CT-2006-026140; European Commission(XE) 36833; European Commission(IT) Ev-K2-CNR Grant - others:AFCE(FI) 1118615 Program:FP6 Institutional research plan: CEZ:AV0Z40720504 Keywords : aerosol particle number * aerosol concentrations * european submicron Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.520, year: 2011

High viscosity fluid simulation using particle-based method

KAUST Repository

Chang, Yuanzhang

2011-03-01

We present a new particle-based method for high viscosity fluid simulation. In the method, a new elastic stress term, which is derived from a modified form of the Hooke\\'s law, is included in the traditional Navier-Stokes equation to simulate the movements of the high viscosity fluids. Benefiting from the Lagrangian nature of Smoothed Particle Hydrodynamics method, large flow deformation can be well handled easily and naturally. In addition, in order to eliminate the particle deficiency problem near the boundary, ghost particles are employed to enforce the solid boundary condition. Compared with Finite Element Methods with complicated and time-consuming remeshing operations, our method is much more straightforward to implement. Moreover, our method doesn\\'t need to store and compare to an initial rest state. The experimental results show that the proposed method is effective and efficient to handle the movements of highly viscous flows, and a large variety of different kinds of fluid behaviors can be well simulated by adjusting just one parameter. © 2011 IEEE.

Characterization of particle number concentrations and PM2.5 in a school: influence of outdoor air pollution on indoor air.

Science.gov (United States)

Guo, Hai; Morawska, Lidia; He, Congrong; Zhang, Yanli L; Ayoko, Godwin; Cao, Min

2010-07-01

The impact of air pollution on school children's health is currently one of the key foci of international and national agencies. Of particular concern are ultrafine particles which are emitted in large quantities, contain large concentrations of toxins and are deposited deeply in the respiratory tract. In this study, an intensive sampling campaign of indoor and outdoor airborne particulate matter was carried out in a primary school in February 2006 to investigate indoor and outdoor particle number (PN) and mass concentrations (PM(2.5)), and particle size distribution, and to evaluate the influence of outdoor air pollution on the indoor air. For outdoor PN and PM(2.5), early morning and late afternoon peaks were observed on weekdays, which are consistent with traffic rush hours, indicating the predominant effect of vehicular emissions. However, the temporal variations of outdoor PM(2.5) and PN concentrations occasionally showed extremely high peaks, mainly due to human activities such as cigarette smoking and the operation of mower near the sampling site. The indoor PM(2.5) level was mainly affected by the outdoor PM(2.5) (r = 0.68, p changes to the modal structure of particle number and size distribution, even though the I/O ratio was different for different size classes. The I/O curves had a maximum value for particles with diameters of 100-400 nm under both occupied and unoccupied scenarios, whereas no significant difference in I/O ratio for PM(2.5) was observed between occupied and unoccupied conditions. Inspection of the size-resolved I/O ratios in the preschool centre and the classroom suggested that the I/O ratio in the preschool centre was the highest for accumulation mode particles at 600 nm after school hours, whereas the average I/O ratios of both nucleation mode and accumulation mode particles in the classroom were much lower than those of Aitken mode particles. The findings obtained in this study are useful for epidemiological studies to estimate the

Nanoparticle filtration performance of NIOSH-certified particulate air-purifying filtering facepiece respirators: evaluation by light scattering photometric and particle number-based test methods.

Science.gov (United States)

Rengasamy, Samy; Eimer, Benjamin C

2012-01-01

National Institute for Occupational Safety and Health (NIOSH) certification test methods employ charge neutralized NaCl or dioctyl phthalate (DOP) aerosols to measure filter penetration levels of air-purifying particulate respirators photometrically using a TSI 8130 automated filter tester at 85 L/min. A previous study in our laboratory found that widely different filter penetration levels were measured for nanoparticles depending on whether a particle number (count)-based detector or a photometric detector was used. The purpose of this study was to better understand the influence of key test parameters, including filter media type, challenge aerosol size range, and detector system. Initial penetration levels for 17 models of NIOSH-approved N-, R-, and P-series filtering facepiece respirators were measured using the TSI 8130 photometric method and compared with the particle number-based penetration (obtained using two ultrafine condensation particle counters) for the same challenge aerosols generated by the TSI 8130. In general, the penetration obtained by the photometric method was less than the penetration obtained with the number-based method. Filter penetration was also measured for ambient room aerosols. Penetration measured by the TSI 8130 photometric method was lower than the number-based ambient aerosol penetration values. Number-based monodisperse NaCl aerosol penetration measurements showed that the most penetrating particle size was in the 50 nm range for all respirator models tested, with the exception of one model at ~200 nm size. Respirator models containing electrostatic filter media also showed lower penetration values with the TSI 8130 photometric method than the number-based penetration obtained for the most penetrating monodisperse particles. Results suggest that to provide a more challenging respirator filter test method than what is currently used for respirators containing electrostatic media, the test method should utilize a sufficient number

Solid Particle Number Emission Factors of Euro VI Heavy-Duty Vehicles on the Road and in the Laboratory

Science.gov (United States)

Giechaskiel, Barouch

2018-01-01

Particulate matter (PM), and in particular ultrafine particles, have a negative impact on human health. The contribution of vehicle PM emissions to air pollution is typically quantified with emission inventories, which need vehicle emission factors as input. Heavy-duty vehicles, although they represent a small percentage of the vehicle population in nearly every major country, contribute the majority of the on-road PM emissions. However, the published data of modern heavy-duty vehicle emissions are scarce, and for the newest Euro VI technologies, almost non-existent. The main objective of this paper is to present Solid Particle Number (SPN) emission factors from Euro VI heavy-duty vehicles using diesel, Compressed Natural Gas (CNG), or Liquefied Natural Gas (LNG). Urban, rural and motorway (highway) emissions were determined on the road at various European cities using SPN Portable Emission Measurement Systems (PEMS). Additional tests on a heavy-duty chassis dynamometer showed that the solid sub-23 nm fraction, which is not covered at the moment in the European regulation, is high, especially for CNG engines. The significant contribution of regeneration events and the effect of ambient temperature and engine cold-start on particle emissions were also discussed. PMID:29425174

Solid Particle Number Emission Factors of Euro VI Heavy-Duty Vehicles on the Road and in the Laboratory

Directory of Open Access Journals (Sweden)

Barouch Giechaskiel

2018-02-01

Full Text Available Particulate matter (PM, and in particular ultrafine particles, have a negative impact on human health. The contribution of vehicle PM emissions to air pollution is typically quantified with emission inventories, which need vehicle emission factors as input. Heavy-duty vehicles, although they represent a small percentage of the vehicle population in nearly every major country, contribute the majority of the on-road PM emissions. However, the published data of modern heavy-duty vehicle emissions are scarce, and for the newest Euro VI technologies, almost non-existent. The main objective of this paper is to present Solid Particle Number (SPN emission factors from Euro VI heavy-duty vehicles using diesel, Compressed Natural Gas (CNG, or Liquefied Natural Gas (LNG. Urban, rural and motorway (highway emissions were determined on the road at various European cities using SPN Portable Emission Measurement Systems (PEMS. Additional tests on a heavy-duty chassis dynamometer showed that the solid sub-23 nm fraction, which is not covered at the moment in the European regulation, is high, especially for CNG engines. The significant contribution of regeneration events and the effect of ambient temperature and engine cold-start on particle emissions were also discussed.

Solid Particle Number Emission Factors of Euro VI Heavy-Duty Vehicles on the Road and in the Laboratory.

Science.gov (United States)

Giechaskiel, Barouch

2018-02-09

Particulate matter (PM), and in particular ultrafine particles, have a negative impact on human health. The contribution of vehicle PM emissions to air pollution is typically quantified with emission inventories, which need vehicle emission factors as input. Heavy-duty vehicles, although they represent a small percentage of the vehicle population in nearly every major country, contribute the majority of the on-road PM emissions. However, the published data of modern heavy-duty vehicle emissions are scarce, and for the newest Euro VI technologies, almost non-existent. The main objective of this paper is to present Solid Particle Number (SPN) emission factors from Euro VI heavy-duty vehicles using diesel, Compressed Natural Gas (CNG), or Liquefied Natural Gas (LNG). Urban, rural and motorway (highway) emissions were determined on the road at various European cities using SPN Portable Emission Measurement Systems (PEMS). Additional tests on a heavy-duty chassis dynamometer showed that the solid sub-23 nm fraction, which is not covered at the moment in the European regulation, is high, especially for CNG engines. The significant contribution of regeneration events and the effect of ambient temperature and engine cold-start on particle emissions were also discussed.

Wire-number effects on high-power annular z-pinches and some characteristics at high wire number

Energy Technology Data Exchange (ETDEWEB)

SANFORD,THOMAS W. L.

2000-05-23

Characteristics of annular wire-array z-pinches as a function of wire number and at high wire number are reviewed. The data, taken primarily using aluminum wires on Saturn are comprehensive. The experiments have provided important insights into the features of wire-array dynamics critical for high x-ray power generation, and have initiated a renaissance in z-pinches when high numbers of wires are used. In this regime, for example, radiation environments characteristic of those encountered during the early pulses required for indirect-drive ICF ignition on the NIF have been produced in hohlraums driven by x-rays from a z-pinch, and are commented on here.

Wire-number effects on high-power annular z-pinches and some characteristics at high wire number

International Nuclear Information System (INIS)

SANFORD, THOMAS W. L.

2000-01-01

Characteristics of annular wire-array z-pinches as a function of wire number and at high wire number are reviewed. The data, taken primarily using aluminum wires on Saturn are comprehensive. The experiments have provided important insights into the features of wire-array dynamics critical for high x-ray power generation, and have initiated a renaissance in z-pinches when high numbers of wires are used. In this regime, for example, radiation environments characteristic of those encountered during the early pulses required for indirect-drive ICF ignition on the NIF have been produced in hohlraums driven by x-rays from a z-pinch, and are commented on here

[High energy particle physics at Purdue, 1990--1991

International Nuclear Information System (INIS)

Gaidos, J.A.; Loeffler, F.J.; McIlwain, R.L.; Miller, D.H.; Palfrey, T.R.; Shibata, E.I.; Shipsey, I.P.

1991-05-01

Progress made in the experimental and theoretical high energy physics program is reviewed. The CLEO experiment, particle astrophysics, dynamical symmetry breaking in gauge theories, the Collider Detector at Fermilab, the TOPAZ Experiment, and elementary particle physics beyond the standard model are included

Wobbling excitations in odd-A nuclei with high-j aligned particles

International Nuclear Information System (INIS)

Hamamoto, Ikuko

2002-01-01

Using the particle-rotor model in which one high-j quasiparticle is coupled to the core of triaxial shape, wobbling excitations are studied. The family of wobbling phonon excitations can be characterized by: (a) very similar intrinsic structure while collective rotation shows the wobbling feature; (b) strong B(E2;I→I-1) values for Δn w =1 transitions where n w expresses the number of wobbling phonons. For the Fermi level lying below the high-j shell with the most favorable triaxiality γ≅+20 deg., the wobbling phonon excitations may be more easily identified close to the yrast line, compared with the Fermi level lying around the middle of the shell with γ≅-30 deg. The spectroscopic study of the yrast states for the triaxial shape with -60 deg. <γ<0 are illustrated by taking a representative example with γ=-30 deg., in which a quantum number related with the special symmetry is introduced to help the physics understanding

Small numbers are sensed directly, high numbers constructed from size and density.

Science.gov (United States)

Zimmermann, Eckart

2018-04-01

Two theories compete to explain how we estimate the numerosity of visual object sets. The first suggests that the apparent numerosity is derived from an analysis of more low-level features like size and density of the set. The second theory suggests that numbers are sensed directly. Consistent with the latter claim is the existence of neurons in parietal cortex which are specialized for processing the numerosity of elements in the visual scene. However, recent evidence suggests that only low numbers can be sensed directly whereas the perception of high numbers is supported by the analysis of low-level features. Processing of low and high numbers, being located at different levels of the neural hierarchy should involve different receptive field sizes. Here, I tested this idea with visual adaptation. I measured the spatial spread of number adaptation for low and high numerosities. A focused adaptation spread of high numerosities suggested the involvement of early neural levels where receptive fields are comparably small and the broad spread for low numerosities was consistent with processing of number neurons which have larger receptive fields. These results provide evidence for the claim that different mechanism exist generating the perception of visual numerosity. Whereas low numbers are sensed directly as a primary visual attribute, the estimation of high numbers however likely depends on the area size over which the objects are spread. Copyright © 2017 Elsevier B.V. All rights reserved.

High-LET particle dosimetry in the ASTP-Biostack III: Zea mays experiment

International Nuclear Information System (INIS)

Peterson, D.D.; Benton, E.V.; Tran, M.; Yang, T.; Freeling, M.; Craise, L.; Tobias, C.A.

1977-01-01

High-LET particle hits in embryos of Zea mays (corn) seeds, flown as part of the ASTP-Biostack III, were determined via plastic nuclear track detectors. Based on etched particle-tracks measurements, 41 embryos were hit in seed layer 1 which contained 80 seeds, and 49 hits occurred in layer 2 which contained 79 seeds. The mean LET value and range of atomic numbers of recorded hits is, respectively, 210 +- 57 keV/μm and 9 approximately less than Z approximately less than 26. Detailed analysis of one particular seed showing marked growth anomalies revealed two hits in the central region of the embryo. These two hits had LET values in the region of 100 to 150 keV/μm, and Z less than approximately 20. (author)

photon-plasma: A modern high-order particle-in-cell code

International Nuclear Information System (INIS)

Haugbølle, Troels; Frederiksen, Jacob Trier; Nordlund, Åke

2013-01-01

We present the photon-plasma code, a modern high order charge conserving particle-in-cell code for simulating relativistic plasmas. The code is using a high order implicit field solver and a novel high order charge conserving interpolation scheme for particle-to-cell interpolation and charge deposition. It includes powerful diagnostics tools with on-the-fly particle tracking, synthetic spectra integration, 2D volume slicing, and a new method to correctly account for radiative cooling in the simulations. A robust technique for imposing (time-dependent) particle and field fluxes on the boundaries is also presented. Using a hybrid OpenMP and MPI approach, the code scales efficiently from 8 to more than 250.000 cores with almost linear weak scaling on a range of architectures. The code is tested with the classical benchmarks particle heating, cold beam instability, and two-stream instability. We also present particle-in-cell simulations of the Kelvin-Helmholtz instability, and new results on radiative collisionless shocks

Multistage charged particle accelerator, with high-vacuum insulation

International Nuclear Information System (INIS)

Holl, P.

1976-01-01

A multistage charged-particle accelerator for operating with accelerating voltages higher than 150 kV is described. The device consists essentially of a high-voltage insulator, a source for producing charged particles, a Wehnelt cylinder, an anode, and a post-accelerating tube containing stack-wise positioned post-accelerating electrodes. A high vacuum is used for insulating the parts carrying the high voltages, and at least one cylindrical screen surrounding these parts is interposed between them and the vacuum vessel, which can itself also function as a cylindrical screen

Particle-number fluctuations and neutron-proton pairing effects on proton and neutron radii of even-even N Almost-Equal-To Z nuclei

Energy Technology Data Exchange (ETDEWEB)

Douici, M.; Allal, N. H.; Fellah, M.; Benhamouda, N.; Oudih, M. R. [Laboratoire de Physique Theorique, Faculte de Physique, USTHB BP 32 El-Alia, 16111 Bab-Ezzouar, Alger (Algeria) and Institut des Sciences et Technologie, Centre Universitaire de Khemis Miliana, Route de Theniet-El-Had, 44225 Khemis-Milia (Algeria); Laboratoire de Physique Theorique, Faculte de Physique, USTHB BP 32 El-Alia, 16111 Bab-Ezzouar, Alger (Algeria) and Centre de Recherche Nucleaire d' Alger, COMENA, BP399 Alger-Gare, Alger (Algeria); Laboratoire de Physique Theorique, Faculte de Physique, USTHB BP 32 El-Alia, 16111 Bab-Ezzouar, Alger (Algeria)

2012-10-20

The particle-number fluctuation effect on the root-mean-square (rms) proton and neutron radii of even-even N Almost-Equal-To Z nuclei is studied in the isovector neutron-proton (np) pairing case using an exact particle-number projection method and the Woods-Saxon model.

Calculation of concentration fields of high-inertia aerosol particles in the flow past a cylindrical fibre

Science.gov (United States)

Zaripov, T. S.; Gilfanov, A. K.; Zaripov, S. K.; Rybdylova, O. D.; Sazhin, S. S.

2018-01-01

The behaviour of high-inertia aerosol particles’ concentration fields in stationary gas suspension flows around a cylinder is investigated using a numerical solution to the Navier-Stokes equations and the fully Lagrangian approach for four Stokes numbers (Stk = 0.1, 1, 4, 10) and three Reynolds numbers (Re = 1, 10, 100). It has been shown that the points of maximum particle concentration along each trajectory shift downstream both when Stk and/or Re increase.

Particle fluxes above forests: Observations, methodological considerations and method comparisons

International Nuclear Information System (INIS)

Pryor, S.C.; Larsen, S.E.; Sorensen, L.L.; Barthelmie, R.J.

2008-01-01

This paper reports a study designed to test, evaluate and compare micro-meteorological methods for determining the particle number flux above forest canopies. Half-hour average particle number fluxes above a representative broad-leaved forest in Denmark derived using eddy covariance range from -7 x 10 7 m -2 s -1 (1st percentile) to 5 x 10 7 m -2 s -1 (99th percentile), and have a median value of -1.6 x 10 6 m -2 s -1 . The statistical uncertainties associated with the particle number flux estimates are larger than those for momentum fluxes and imply that in this data set approximately half of the particle number fluxes are not statistically different to zero. Particle number fluxes from relaxed eddy accumulation (REA) and eddy covariance are highly correlated and of almost identical magnitude. Flux estimates from the co-spectral and dissipation methods are also correlated with those from eddy covariance but exhibit higher absolute magnitude of fluxes. - Number fluxes of ultra-fine particles over a forest computed using four micro-meteorological techniques are highly correlated but vary in magnitude

Polymer-Particle Pressure-Sensitive Paint with High Photostability

Directory of Open Access Journals (Sweden)

Yu Matsuda

2016-04-01

Full Text Available We propose a novel fast-responding and paintable pressure-sensitive paint (PSP based on polymer particles, i.e. polymer-particle (pp-PSP. As a fast-responding PSP, polymer-ceramic (PC-PSP is widely studied. Since PC-PSP generally consists of titanium (IV oxide (TiO2 particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP.

Size-resolved particle number emission patterns under real-world driving conditions using positive matrix factorization

NARCIS (Netherlands)

Domínguez-Sáez, A.; Viana, M.; Barrios, C.C.; Rubio, J.R.; Amato, F.; Pujadas, M.; Querol, X.

2012-01-01

A novel on-board system was tested to characterize size-resolved particle number emission patterns under real-world driving conditions, running in a EURO4 diesel vehicle and in a typical urban circuit in Madrid (Spain). Emission profiles were determined as a function of driving conditions. Source

High-performance supercapacitors based on hierarchically porous graphite particles

Energy Technology Data Exchange (ETDEWEB)

Chen, Zheng; Wen, Jing; Yan, Chunzhu; Rice, Lynn; Sohn, Hiesang; Lu, Yunfeng [Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095 (United States); Shen, Meiqing [School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 (China); Cai, Mei [General Motor R and D Center, Warren, MI 48090 (United States); Dunn, Bruce [Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095 (United States)

2011-07-15

Hierarchically porous graphite particles are synthesized using a continuous, scalable aerosol approach. The unique porous graphite architecture provides the particles with high surface area, fast ion transportation, and good electronic conductivity, which endows the resulting supercapacitors with high energy and power densities. This work provides a new material platform for high-performance supercapacitors with high packing density, and is adaptable to battery electrodes, fuel-cell catalyst supports, and other applications. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Superconductivity in high energy particle accelerators

International Nuclear Information System (INIS)

Schmueser, P.

2002-08-01

The basics of superconductivity are outlined with special emphasis on the features which are relevant for the application in magnets and radio frequency cavities for high energy particle accelerators. The special properties of superconducting accelerator magnets are described in detail: design principles, magnetic field calculations, magnetic forces, quench performance, persistent magnetization currents and eddy currents. The design principles and basic properties of superconducting cavities are explained as well as the observed performance limitations and the countermeasures. The ongoing research efforts towards maximum accelerating fields are addressed and the coupling of radio frequency power to the particle beam is treated. (orig.)

A nested sampling particle filter for nonlinear data assimilation

KAUST Repository

Elsheikh, Ahmed H.

2014-04-15

We present an efficient nonlinear data assimilation filter that combines particle filtering with the nested sampling algorithm. Particle filters (PF) utilize a set of weighted particles as a discrete representation of probability distribution functions (PDF). These particles are propagated through the system dynamics and their weights are sequentially updated based on the likelihood of the observed data. Nested sampling (NS) is an efficient sampling algorithm that iteratively builds a discrete representation of the posterior distributions by focusing a set of particles to high-likelihood regions. This would allow the representation of the posterior PDF with a smaller number of particles and reduce the effects of the curse of dimensionality. The proposed nested sampling particle filter (NSPF) iteratively builds the posterior distribution by applying a constrained sampling from the prior distribution to obtain particles in high-likelihood regions of the search space, resulting in a reduction of the number of particles required for an efficient behaviour of particle filters. Numerical experiments with the 3-dimensional Lorenz63 and the 40-dimensional Lorenz96 models show that NSPF outperforms PF in accuracy with a relatively smaller number of particles. © 2013 Royal Meteorological Society.

Bounds on the number of possible Higgs particles using grand unification and exceptional Lie groups

International Nuclear Information System (INIS)

El Naschie, M.S.

2008-01-01

The total sum of dimensions of a magnum exceptional Lie symmetry groups hierarchy is 4α-bar o =(4)(137+k o )≅548. Dividing this value among the various quantum fields leads to the possibility of an eight degrees of freedom Higgs field. However analyzing the same situation using sub groups of the largest exceptional Lie group leads to the conclusion that we are likely to find three Higgs particles only at the energy scale of the standard model. Consequently five of the eight degrees of freedom are unlikely to materialize as particles at this particular energy scale. This conclusion is reinforced by an entirely different approach based on grand unification analysis which excludes any grand unification using 4HD, i.e. four Higgs doublets. This leaves us with one, two and three Higgs doublets. Noting that a super symmetric standard model with two Higgs doublets gives almost perfect grand unification and that the result agrees with our exceptional Lie symmetry groups analysis, we exclude everything else. The final result is that we expect to find at least three more Higgs particles leading to a total of 66 elementary particles while at a somewhat higher energy, the expected number of 69 particles found using E-infinity theory is obtained

Genotoxic effects of daily personal exposure to particle mass and number concentrations on buccal cells

Science.gov (United States)

de Almeida, Daniela S.; da Costa, Silvano César; Ribeiro, Marcos; Moreira, Camila A. B.; Beal, Alexandra; Squizzato, Rafaela; Rudke, Anderson Paulo; Rafee, Sameh Adib Abou; Martins, Jorge A.; Palioto, Graciana Freitas; Kumar, Prashant; Martins, Leila D.

2018-03-01

The aim of this study is to assess personal exposure to Particle Number Concentrations (PNC) in four size ranges between 0.3 and 10 μm, and particulate matter (PM1; PM2.5; PM4; PM10) in order to evaluate possible genotoxic effects through a comet assay in buccal cells. A convenience cohort of 30 individuals from a Brazilian medium-sized city was selected. These individuals aged between 20 and 61 and worked in typical job categories (i.e., administrative, commerce, education, general services and transport). They were recruited to perform personal exposure measurements during their typical daily routine activities, totaling 240 h of sampling. The 8-h average mass concentrations in air for volunteers ranged from 2.4 to 31.8 μg m-3 for PM1, 4.2-45.1 μg m-3 for PM2.5, 7.9-66.1 μg m-3 for PM4 and from 23.1 to 131.7 μg m-3 for PM10. The highest PNC variation was found for 0.3-0.5 range, between 14 and 181 particles cm-3, 1 to 14 particles cm-3 for the 0.5-1.0 range, 0.2 to 2 particles cm-3 for the 1.0-2.5 range, and 0.06 to 0.7 particles cm-3 for the 2.5-10 range. Volunteers in the 'education' category experienced the lowest inhaled dose of PM2.5, as opposed to those involved in 'commercial' activities with the highest doses for PM10 (1.63 μg kg-1 h-1) and PM2.5 (0.61 μg kg-1 h-1). The predominant cause for these high doses was associated with the proximity of the workplace to the street and vehicle traffic. The comet assay performed in buccal cells indicated that the volunteers in 'commerce' category experienced the highest damage to their DeoxyriboNucleic Acid (DNA) compared with the control category (i.e. 'education'). These results indicate the variability in personal exposure of the volunteers in different groups, and the potential damage to DNA was much higher for those spending time in close proximity to the vehicle sources (e.g. commercial services) leading to exposure to a higher fraction of fine particles. This study builds understanding on the exposure

Charged-particle mutagenesis II. Mutagenic effects of high energy charged particles in normal human fibroblasts

Science.gov (United States)

Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

1994-01-01

The biological effects of high LET charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 micrometer2 and 0.09 to 5.56 x 10(-3) micrometer2, respectively. The maximum values were obtained by 56Fe with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(-5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

High-density lipoprotein-like particle formation of Synuclein variants.

Science.gov (United States)

Eichmann, Cédric; Kumari, Pratibha; Riek, Roland

2017-01-01

α-Synuclein (α-Syn) is an intrinsically disordered protein in solution whose fibrillar aggregates are the hallmark of Parkinson's disease (PD). Although the specific function of α-Syn is still unclear, its high structural plasticity is key for the interactions of α-Syn with biological membranes. Recently, it has been observed that α-Syn is able to form high-density lipoprotein-like (HDL-like) particles that are reminiscent of self-assembling phospholipid bilayer nanodiscs. Here, we extended our preparation method for the production of α-Syn lipoprotein particles to the β- and γ-Syn variants, and the PD-related familial α-Syn mutants. We show that all human Syns can form stable and homogeneous populations of HDL-like particles with distinct morphologies. Our results characterize the impact of the individual Syns on the formation capacity of these particles and indicate that Syn HDL-like particles are neither causing toxicity nor a toxicity-related loss of α-Syn in PD. © 2016 Federation of European Biochemical Societies.

Turbulent boundary layer in high Rayleigh number convection in air.

Science.gov (United States)

du Puits, Ronald; Li, Ling; Resagk, Christian; Thess, André; Willert, Christian

2014-03-28

Flow visualizations and particle image velocimetry measurements in the boundary layer of a Rayleigh-Bénard experiment are presented for the Rayleigh number Ra=1.4×1010. Our visualizations indicate that the appearance of the flow structures is similar to ordinary (isothermal) turbulent boundary layers. Our particle image velocimetry measurements show that vorticity with both positive and negative sign is generated and that the smallest flow structures are 1 order of magnitude smaller than the boundary layer thickness. Additional local measurements using laser Doppler velocimetry yield turbulence intensities up to I=0.4 as in turbulent atmospheric boundary layers. From our observations, we conclude that the convective boundary layer becomes turbulent locally and temporarily although its Reynolds number Re≈200 is considerably smaller than the value 420 underlying existing phenomenological theories. We think that, in turbulent Rayleigh-Bénard convection, the transition of the boundary layer towards turbulence depends on subtle details of the flow field and is therefore not universal.

Influence of high-dose gamma radiation and particle size on antioxidant properties of Maize ( Zea mays L.) flour

International Nuclear Information System (INIS)

Nawaz, Haq; Shad, Muhammad Aslam; Rehman, Tanzila; Ramzan, Ayesha

2016-01-01

Influence of high-dose gamma radiation and particle size on antioxidant properties of maize (Zea mays L.) flour was studied using response surface methodology. A central composite design based on three levels of each of particle size, in terms of mesh number (40, 60 and 80 meshes), and gamma radiation dose (25, 50 and 75 kGy) was constructed. A statistically significant dose-dependent decrease (p<0.05) in antioxidant properties of gamma irradiated flour was observed. However, an increase in the mesh number (decrease in particle size of flour) resulted in an increase in antioxidant properties. The optimum level of radiation dose to achieve maximum value of responses was found to be 50 kGy for Trolox equivalent total antioxidant activity (TETAOA), 25 kGy for iron chelating ability (ICA), 25 kGy for reducing power (RP) and 75 kGy for linoleic acid reduction capacity (LARC). However, the optimum level of mesh number to achieve desired levels of TETAOA, ICA, RP and LARC was found to be 80 meshes. (author)

Influence of high-dose gamma radiation and particle size on antioxidant properties of Maize ( Zea mays L.) flour

Energy Technology Data Exchange (ETDEWEB)

Nawaz, Haq; Shad, Muhammad Aslam; Rehman, Tanzila; Ramzan, Ayesha, E-mail: haqnawaz@bzu.edu.pk [Bahauddin Zakariya University, Multan (Pakistan)

2016-10-15

Influence of high-dose gamma radiation and particle size on antioxidant properties of maize (Zea mays L.) flour was studied using response surface methodology. A central composite design based on three levels of each of particle size, in terms of mesh number (40, 60 and 80 meshes), and gamma radiation dose (25, 50 and 75 kGy) was constructed. A statistically significant dose-dependent decrease (p<0.05) in antioxidant properties of gamma irradiated flour was observed. However, an increase in the mesh number (decrease in particle size of flour) resulted in an increase in antioxidant properties. The optimum level of radiation dose to achieve maximum value of responses was found to be 50 kGy for Trolox equivalent total antioxidant activity (TETAOA), 25 kGy for iron chelating ability (ICA), 25 kGy for reducing power (RP) and 75 kGy for linoleic acid reduction capacity (LARC). However, the optimum level of mesh number to achieve desired levels of TETAOA, ICA, RP and LARC was found to be 80 meshes. (author)

Effect of meal composition on postprandial lipid concentrations and lipoprotein particle numbers: A randomized cross-over study.

Directory of Open Access Journals (Sweden)

Meena Shah

Full Text Available It is unclear how high-protein (HP and high-monounsaturated fat (HMF meals affect postprandial blood lipids and lipoprotein particle numbers (LPN.To compare a HP versus a HMF meal on postprandial lipid and LPN responses.Twenty-four participants (age: 36.3±15.0 years; body mass index: 23.6±2.0 kg/m2; 45.8% female were fed a HP (31.9% energy from protein and a HMF (35.2% fat and 20.7% monounsaturated fat meal in a randomized cross-over trial design. Energy and carbohydrate content were the same across meals. Blood samples were drawn in the fasting state and 3 hour postprandial state, and assessed for lipids and LPN.Repeated measures analysis showed a significant (p<0.05 treatment by time interaction effect for triglycerides (TG, the primary variable, total high-density lipoprotein particles (T-HDLP and T-HDLP minus large-buoyant high-density lipoprotein 2b (T-HDLP-LB-HDL2b. HP versus HMF condition led to significantly lower TG at 120 (geometric mean: 90.1 (95% confidence interval (CI: 76.4-106.3 vs. 146.5 (124.2-172.9 mg/dL and 180 (101.4 (83.1-123.8 vs. 148.7 (121.9-181.4 mg/dL min and higher T-HDLP at 120 (mean difference: 297.3 (95% CI: 48.6-545.9 nmol/L and 180 (291.6 (15.8-567.5 nmol/L min. The difference in T-HDLP by condition was due to the significantly higher small-dense HDLP (T-HDLP-LB-HDL2b during HP versus HMF condition at 120 (mean difference: 452.6 (95% CI: 177.4-727.9 nmol/L and 180 (496.8 (263.1-730.6 nmol/L min. Area under the curve analysis showed that HP versus HMF condition led to significantly lower TG, non-HDLP, and very-low-density lipoprotein particles (VLDLP responses but significantly less favorable responses in LB-HDL2b particles, T-HDLP-LB-HDL2b, and LB-HDL2b/T-HDLP ratio.The HP meal led to lower TG, non-HDLP, and VLDLP but less favorable LB-HDL2b, small-dense HDLP, and LB-HDL2b/T-HDLP ratio responses versus a HMF meal. Further studies are needed to confirm these findings over multiple meals.

DECAY MODES OF HIGH-LYING SINGLE-PARTICLE STATES IN PB-209

NARCIS (Netherlands)

BEAUMEL, D; FORTIER, S; GALES, S; GUILLOT, J; LANGEVINJOLIOT, H; LAURENT, H; MAISON, JM; VERNOTTE, J; BORDEWIJK, JA; BRANDENBURG, S; KRASZNAHORKAY, A; CRAWLEY, GM; MASSOLO, CP; RENTERIA, M

The neutron decay of high-lying single-particle states in Pb-209 excited by means of the (alpha, He-3) reaction has been investigated at 122 MeV incident energy using a multidetector array. The high-spin values of these states, inferred from previous inclusive experiments, are confirmed by the

Measurements of humidified particle number size distributions in a Finnish boreal forest: derivation of hygroscopic particle growth factors

Energy Technology Data Exchange (ETDEWEB)

Birmili, W.; Schwirn, K.; Nowak, A.; Rose, D.; Wiedensohler, A. (Leibniz Institute for Tropospheric Research, Leipzig (Germany)); Petaejae, T.; Haemeri, K.; Aalto, P.; Kulmala, M.; Boy, M. (Dept. of Physics, Univ. of Helsinki (Finland)); Joutsensaari, J. (Univ. of Kuopio, Dept. of Physics (Finland))

2009-07-01

Dry and humidified size distributions of atmospheric particles were characterised at the atmospheric research station SMEAR 2, Finland between May and July 2004. Particles were classified in a size range between 3 and 800 nm at controlled relative humidities up to 90% by two instruments complementary in size range (HDMPS; Nano-HDMPS). Using the summation method, descriptive hygroscopic growth factors (DHGF) were derived for particle diameters between 70 and 300 nm by comparing dry and humidified size distributions. At 90% relative humidity, DHGF showed mean values between 1.25 and 1.45 in the accumulation mode, between 1.20 and 1.25 in the Aitken mode, and between 1.15 and 1.20 in the nucleation mode. Due to the high size resolution of the method, the transition in DHGF between the Aitken and accumulation modes, which reflects differences in the soluble fraction, could be pinpointed efficiently. For the accumulation mode, experimental DHGFs were compared to those calculated from a simplistic growth model initialised by in-situ chemical composition measurements, and yielded maximum deviations around 0.1. The variation in DHGF could only imperfectly be linked to meteorological factors. A pragmatic parameterisation of DHGF as a function of particle diameter and relative humidity was derived, and subsequently used to study the sensitivity of the condensational sink parameter (CS) as a function of height in a well-mixed boundary layer. (orig.)

Approximate energy correction for particle number summetry breaking in constrained Hartree-Fock plus BCS calculations

International Nuclear Information System (INIS)

Redon, N.; Meyer, J.; Meyer, M.

1989-01-01

An approximate restoration of the particle number symmetry, a la Lipkin-Nogami, is numerically investigated in the context of Constrained Hartree-Fock plus BCS calculations. Its effect is assessed in a variety of physical situations like potential energy landscapes in transitional nuclei, shape isomerism at low spin and fission barriers of actinide nuclei

Particle Settling in Low Energy Turbulence

Science.gov (United States)

Allen, Rachel; MacVean, Lissa; Tse, Ian; Mazzaro, Laura; Stacey, Mark; Variano, Evan

2014-11-01

Particle settling velocities can be altered by turbulence. In turbulence, dense particles may get trapped in convergent flow regions, and falling particles may be swept towards the downward side of turbulent eddies, resulting in enhanced settling velocities. The degree of velocity enhancement may depend on the Stokes number, the Rouse number, and the turbulent Reynolds number. In a homogeneous, isotropic turbulence tank, we tested the effects of particle size and type, suspended sediment concentration, and level of turbulence on the settling velocities of particles typically found in muddy estuaries. Two Acoustic Doppler Velocimeters (ADVs), separated vertically, measured turbulent velocities and suspended sediment concentrations, which yield condition dependent settling velocities, via ∂/á C ñ ∂ t = -∂/∂ z (ws á C ñ + á w ' C ' ñ) . These results are pertinent to fine sediment transport in estuaries, where high concentrations of suspended material are transported and impacted by low energy turbulence.

A Critical Shock Mach Number for Particle Acceleration in the Absence of Pre-existing Cosmic Rays: M = √5

NARCIS (Netherlands)

Vink, J.; Yamazaki, R.

2014-01-01

It is shown that, under some generic assumptions, shocks cannot accelerate particles unless the overall shock Mach number exceeds a critical value M > √5. The reason is that for M ≤ √5 the work done to compress the flow in a particle precursor requires more enthalpy flux than the system can sustain.

Effects of particles on macrophage migration

International Nuclear Information System (INIS)

Mueller, H.L.; Robinson, B.; Muggenburg, B.A.; Guilmette, R.A.

1988-01-01

Random and directed migration of cells lavaged from the lungs of rats and dogs were studied in vitro using formyl-methionyl-leucyl-phenylalanine (FMLP) as a chemo attractant. Rats and dogs were intratracheally instilled with either saline (controls) or about 10 9 fluorescent polystyrene microspheres, and lungs were lavaged after 1 or 7 days. More rat cells than dog cells migrated at 1 day after both particle and saline instillations; at 7 days, only cells lavaged from rats after particle instillations showed enhanced migration abilities. FMLP caused a 1.5 to 2-fold enhancement compared to random migration in cell numbers counted on the lower sides of chemotactic membranes. Cells with low particle numbers were more likely to migrate than those with high numbers of ingested particles. (author)

Parallel Monte Carlo Particle Transport and the Quality of Random Number Generators: How Good is Good Enough?

International Nuclear Information System (INIS)

Procassini, R J; Beck, B R

2004-01-01

It might be assumed that use of a ''high-quality'' random number generator (RNG), producing a sequence of ''pseudo random'' numbers with a ''long'' repetition period, is crucial for producing unbiased results in Monte Carlo particle transport simulations. While several theoretical and empirical tests have been devised to check the quality (randomness and period) of an RNG, for many applications it is not clear what level of RNG quality is required to produce unbiased results. This paper explores the issue of RNG quality in the context of parallel, Monte Carlo transport simulations in order to determine how ''good'' is ''good enough''. This study employs the MERCURY Monte Carlo code, which incorporates the CNPRNG library for the generation of pseudo-random numbers via linear congruential generator (LCG) algorithms. The paper outlines the usage of random numbers during parallel MERCURY simulations, and then describes the source and criticality transport simulations which comprise the empirical basis of this study. A series of calculations for each test problem in which the quality of the RNG (period of the LCG) is varied provides the empirical basis for determining the minimum repetition period which may be employed without producing a bias in the mean integrated results

Numerical simulations on a high-temperature particle moving in coolant

International Nuclear Information System (INIS)

Li Xiaoyan; Shang Zhi; Xu Jijun

2006-01-01

This study considers the coupling effect between film boiling heat transfer and evaporation drag around a hot-particle in cold liquid. Taking momentum and energy equations of the vapor film into account, a transient single particle model under FCI conditions has been established. The numerical simulations on a high-temperature particle moving in coolant have been performed using Gear algorithm. Adaptive dynamic boundary method is adopted during simulating to matching the dynamic boundary that is caused by vapor film changing. Based on the method presented above, the transient process of high-temperature particles moving in coolant can be simulated. The experimental results prove the validity of the HPMC model. (authors)

Charged-particle mutagenesis 2. Mutagenic effects of high energy charged particles in normal human fibroblasts

Science.gov (United States)

Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

1994-01-01

The biological effects of high Linear Energy Transfer (LET) charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 sq micrometer and 0.09 to 5.56 x 10(exp -3) sq micrometer respectively. The maximum values were obtained by Fe-56 with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(exp -5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

Direct determination of highly size-resolved turbulent particle fluxes with the disjunct eddy covariance method and a 12 – stage electrical low pressure impactor

Directory of Open Access Journals (Sweden)

A. Schmidt

2008-12-01

Full Text Available During summer 2007, turbulent vertical particle mass and number fluxes were measured for a period of 98 days near the city centre of Münster in north-west Germany. For this purpose, a valve controlled disjunct eddy covariance system was mounted at 65 m a.g.l. on a military radio tower. The concentration values for 11 size bins with aerodynamic diameters (D50 from 0.03 to 10 μm were measured with an electrical low pressure impactor. After comparison with other fluxes obtained from 10 Hz measurements with the classical eddy covariance method, the loss of information concerning high frequent parts of the flux could be stated as negligible. The results offer an extended insight in the turbulent atmospheric exchange of aerosol particles by highly size-resolved particle fluxes covering 11 size bins and show that the city of Münster acts as a relevant source for aerosol particles.

Significant differences occur between the fluxes of the various particle size classes. While the total particle number flux shows a pattern which is strictly correlated to the diurnal course of the turbulence regime and the traffic intensity, the total mass flux exhibits a single minimum in the evening hours when coarse particles start to deposit.

As a result, a mean mass deposition of about 10 mg m⁻² per day was found above the urban test site, covering the aerosol size range from 40 nm to 2.0 μm. By contrast, the half-hourly total number fluxes accumulated over the lower ELPI stages range from −4.29×10⁷ to +1.44×10⁸ particles m⁻² s⁻¹ and are clearly dominated by the sub-micron particle fraction of the impactor stages with diameters between 40 nm and 320 nm. The averaged number fluxes of particles with diameters between 2.0 and 6.4 μm show lower turbulent dynamics during daytime and partially remarkably high negative fluxes with mean deposition velocities of 2×10⁻³ m

Numerical evaluation of high energy particle effects in magnetohydrodynamics

International Nuclear Information System (INIS)

White, R.B.; Wu, Y.

1994-03-01

The interaction of high energy ions with magnetohydrodynamic modes is analyzed. A numerical code is developed which evaluates the contribution of the high energy particles to mode stability using orbit averaging of motion in either analytic or numerically generated equilibria through Hamiltonian guiding center equations. A dispersion relation is then used to evaluate the effect of the particles on the linear mode. Generic behavior of the solutions of the dispersion relation is discussed and dominant contributions of different components of the particle distribution function are identified. Numerical convergence of Monte-Carlo simulations is analyzed. The resulting code ORBIT provides an accurate means of comparing experimental results with the predictions of kinetic magnetohydrodynamics. The method can be extended to include self consistent modification of the particle orbits by the mode, and hence the full nonlinear dynamics of the coupled system

The influence of the Kubo number on the transport of energetic particles

International Nuclear Information System (INIS)

Shalchi, A

2016-01-01

We discuss the interaction between charged energetic particles and magnetized plasmas by using analytical theory. Based on the unified nonlinear transport (UNLT) theory we compute the diffusion coefficient across a large scale magnetic field. To achieve analytical tractability we use a simple Gaussian approach to model the turbulent magnetic fields. We show that the perpendicular diffusion coefficient depends only on two parameters, namely the Kubo number and the parallel mean free path. We combine the aforementioned turbulence model with the UNLT theory and we solve the corresponding integral equation numerically to show how these two parameters control the perpendicular diffusion coefficient. Furthermore, we consider two extreme cases, namely the case of strong and suppressed pitch-angle scattering, respectively. For each case we consider small and large Kubo numbers to achieve a further simplification. All our analytical findings are compared with formulas which are known in diffusion theory. (paper)

Destabilization of low mode number Alfven modes in a tokamak by energetic or alpha particles

International Nuclear Information System (INIS)

Tsang, K.T.; Sigmar, D.J.; Whitson, J.C.

1980-12-01

With the inclusion of finite Larmor radius effects in the shear Alfven eigenmode equation, the continuous Alfven spectrum, which has been extensively discussed in ideal magnetohydrodynamics, is removed. Neutrally stable, discrete radial eigenmodes appear in the absence of sources of free energy and dissipation. Alpha (or energetic) particle toroidal drifts destabilize these modes, provided the particles are faster than the Alfven speed. Although the electron Landu resonance contributes to damping, a stability study of the parametric variation of the energy and the density scale length of the energetic particles shows that modes with low radial mode numbers remain unstable in most cases. Since the alpha particles are concentrated in the center of the plasma, this drift-type instability suggests anomalous helium ash diffusion. Indeed, it is shown that stochasticity of alpha orbits due to the overlapping of radially neighboring Alfven resonances is induced at low amplitudes, e/sub i//sup approx./phi/T/sub i/ greater than or equal to 0.05, implying a diffusion coefficient D/sub r//sup α/ greater than or equal to 4.4 x 10 3 cm 2 /s

Are consistent equal-weight particle filters possible?

Science.gov (United States)

van Leeuwen, P. J.

2017-12-01

Particle filters are fully nonlinear data-assimilation methods that could potentially change the way we do data-assimilation in highly nonlinear high-dimensional geophysical systems. However, the standard particle filter in which the observations come in by changing the relative weights of the particles is degenerate. This means that one particle obtains weight one, and all other particles obtain a very small weight, effectively meaning that the ensemble of particles reduces to that one particle. For over 10 years now scientists have searched for solutions to this problem. One obvious solution seems to be localisation, in which each part of the state only sees a limited number of observations. However, for a realistic localisation radius based on physical arguments, the number of observations is typically too large, and the filter is still degenerate. Another route taken is trying to find proposal densities that lead to more similar particle weights. There is a simple proof, however, that shows that there is an optimum, the so-called optimal proposal density, and that optimum will lead to a degenerate filter. On the other hand, it is easy to come up with a counter example of a particle filter that is not degenerate in high-dimensional systems. Furthermore, several particle filters have been developed recently that claim to have equal or equivalent weights. In this presentation I will show how to construct a particle filter that is never degenerate in high-dimensional systems, and how that is still consistent with the proof that one cannot do better than the optimal proposal density. Furthermore, it will be shown how equal- and equivalent-weights particle filters fit within this framework. This insight will then lead to new ways to generate particle filters that are non-degenerate, opening up the field of nonlinear filtering in high-dimensional systems.

Distribution of latex particles in lung and lymph node tissues of rats and dogs

International Nuclear Information System (INIS)

Mueller, H.L; Muggenburg, B.A.; Gillett, N.A.; Guilmette, R.A.

1988-01-01

The distribution of fluorescent poly sytrene microspheres in different lung compartments, with differing particle numbers within individual lung and lymph node cells was examined In methacrylate-embedded tissue slices. Rat tissues were analyzed at 1, 7 and 13 days after particle instillation, dog tissues at 7 and 13 days. A much higher fraction of particles was seen in the lung interstitium and in lung-associated lymph nodes in dogs than in rats. Particle concentrations in TBLN cells were generally very low in both species, but were high in free alveolar cells after high particle numbers were instilled, and increased from 1 to 13 days, suggesting that alveolar cells with few particles were cleared faster than those wth high ingested particle numbers. (author)

Fully kinetic particle simulations of high pressure streamer propagation

Science.gov (United States)

Rose, David; Welch, Dale; Thoma, Carsten; Clark, Robert

2012-10-01

Streamer and leader formation in high pressure devices is a dynamic process involving a hierarchy of physical phenomena. These include elastic and inelastic particle collisions in the gas, radiation generation, transport and absorption, and electrode interactions. We have performed 2D and 3D fully EM implicit particle-in-cell simulation model of gas breakdown leading to streamer formation under DC and RF fields. The model uses a Monte Carlo treatment for all particle interactions and includes discrete photon generation, transport, and absorption for ultra-violet and soft x-ray radiation. Central to the realization of this fully kinetic particle treatment is an algorithm [D. R. Welch, et al., J. Comp. Phys. 227, 143 (2007)] that manages the total particle count by species while preserving the local momentum distribution functions and conserving charge. These models are being applied to the analysis of high-pressure gas switches [D. V. Rose, et al., Phys. Plasmas 18, 093501 (2011)] and gas-filled RF accelerator cavities [D. V. Rose, et al. Proc. IPAC12, to appear].

Estimate of main local sources to ambient ultrafine particle number concentrations in an urban area

Science.gov (United States)

Rahman, Md Mahmudur; Mazaheri, Mandana; Clifford, Sam; Morawska, Lidia

2017-09-01

Quantifying and apportioning the contribution of a range of sources to ultrafine particles (UFPs, D oil refineries, and seaport) sources to the total ambient particle number concentration (PNC) in a busy, inner-city area in Brisbane, Australia using Bayesian statistical modelling and other exploratory tools. The Bayesian model was trained on the PNC data on days where NP formations were known to have not occurred, hourly traffic counts, solar radiation data, and smooth daily trend. The model was applied to apportion and quantify the contribution of NP formations and local traffic and non-traffic sources to UFPs. The data analysis incorporated long-term measured time-series of total PNC (D ≥ 6 nm), particle number size distributions (PSD, D = 8 to 400 nm), PM2.5, PM10, NOx, CO, meteorological parameters and traffic counts at a stationary monitoring site. The developed Bayesian model showed reliable predictive performances in quantifying the contribution of NP formation events to UFPs (up to 4 × 104 particles cm- 3), with a significant day to day variability. The model identified potential NP formation and no-formations days based on PNC data and quantified the sources contribution to UFPs. Exploratory statistical analyses show that total mean PNC during the middle of the day was up to 32% higher than during peak morning and evening traffic periods, which were associated with NP formation events. The majority of UFPs measured during the peak traffic and NP formation periods were between 30-100 nm and smaller than 30 nm, respectively. To date, this is the first application of Bayesian model to apportion different sources contribution to UFPs, and therefore the importance of this study is not only in its modelling outcomes but in demonstrating the applicability and advantages of this statistical approach to air pollution studies.

Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

International Nuclear Information System (INIS)

Kim, J.-H.; Nishihara, M.; Adamovich, I.V.; Samimy, M.; Gorbatov, S.V.; Pliavaka, F.V.

2010-01-01

Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

High power density reactors based on direct cooled particle beds

Science.gov (United States)

Powell, J. R.; Horn, F. L.

Reactors based on direct cooled High Temperature Gas Cooled Reactor (HTGR) type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out along the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBRs) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed.

Decay properties of high-lying single-particles modes

Science.gov (United States)

Beaumel, D.; Fortier, S.; Galès, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J. M.; Vernotte, J.; Bordewijck, J.; Brandenburg, S.; Krasznahorkay, A.; Crawley, G. M.; Massolo, C. P.; Renteria, M.; Khendriche, A.

1996-02-01

The neutron decay of high-lying single-particle states in 64Ni, 90Zr, 120Sn and 208Pb excited by means of the (α, 3He) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular correlation analysis. The structure located between 11 and 15 MeV in 91Zr, and between 8 and 12 MeV excitation energy in 209Pb display large departures from a pure statistical decay. The corresponding non-statistical branching ratios are compared with the results of two theoretical calculations.

Particle creation and Dirac's large number hypothesis; and Reply

International Nuclear Information System (INIS)

Canuto, V.; Adams, P.J.; Hsieh, S.H.; Tsiang, E.; Steigman, G.

1976-01-01

The claim made by Steigman (Nature; 261:479 (1976)), that the creation of matter as postulated by Dirac (Proc. R. Soc.; A338:439 (1974)) is unnecessary, is here shown to be incorrect. It is stated that Steigman's claim that Dirac's large Number Hypothesis (LNH) does not require particle creation is wrong because he has assumed that which he was seeking to prove, that is that rho does not contain matter creation. Steigman's claim that Dirac's LNH leads to nonsensical results in the very early Universe is superficially correct, but this only supports Dirac's contention that the LNH may not be valid in the very early Universe. In a reply Steigman points out that in Dirac's original cosmology R approximately tsup(1/3) and using this model the results and conclusions of the present author's paper do apply but using a variation chosen by Canuto et al (T approximately t) Dirac's LNH cannot apply. Additionally it is observed that a cosmological theory which only predicts the present epoch is of questionable value. (U.K.)

Modified Mason number for charged paramagnetic colloidal suspensions

Science.gov (United States)

Du, Di; Hilou, Elaa; Biswal, Sibani Lisa

2016-06-01

The dynamics of magnetorheological fluids have typically been described by the Mason number, a governing parameter defined as the ratio between viscous and magnetic forces in the fluid. For most experimental suspensions of magnetic particles, surface forces, such as steric and electrostatic interactions, can significantly influence the dynamics. Here we propose a theory of a modified Mason number that accounts for surface forces and show that this modified Mason number is a function of interparticle distance. We demonstrate that this modified Mason number is accurate in describing the dynamics of a rotating pair of paramagnetic colloids of identical or mismatched sizes in either high or low salt solutions. The modified Mason number is confirmed to be pseudoconstant for particle pairs and particle chains undergoing a stable-metastable transition during rotation. The interparticle distance term can be calculated using theory or can be measured experimentally. This modified Mason number is more applicable to magnetorheological systems where surface forces are not negligible.

Number of Packages of Information which are processed in a Second by the Fundamental Particles (strings) of a Human Body

Science.gov (United States)

Gholibeigian, Hassan; Gholibeigian, Ghasem; Gholibeigian, Kazem

2016-11-01

The fundamental particle (string) gets a package of complete information of its quantum state via inside of its sub-particle (sub-string) from dimension of information. This package is processed by sub-particle in each Planck time [Gholibeigian, APS 2015, abstract #L1.027]. On the other hand, a 70 kg human's body would have approximately 7*1027 atoms. Of that, 4.7*1027 would be hydrogen atoms. Another 1.8*1027 would be oxygen and there are 7.0*1026 carbon atoms. If we add that all up, total is 2.3*1028 protons, 1.8*1028 neutrons, and 2.3*1028 electrons. Each proton and neutron has 6 fundamental particles. So the total number of packages of information which are processed by each of us in a second becomes: I = [ 6 × (2 . 3 + 1 . 8) ×1028 + 2 . 3 ×1028 ] ×1044 = 2 . 69 ×1073 The processed information carry by fundamental particles. Based on Shanon equation, I = - S , this number can be equal to the increased entropy of each of us per second too. AmirKabir University of Technology, Tehran, Iran.

Experimental study of high spin states in low-medium mass nuclei by use of charge particle induced reactions

International Nuclear Information System (INIS)

Alenius, N.G.

1975-01-01

For the test of nuclear models the study of the properties of nuclear states of high angular momentum is especially important, because such states can often be given very simple theoretical descriptions. High spin states are easily populated by use of reactions initiated by alpha particles or heavy ions. In this thesis a number of low-medium mass nuclei have been studied, with emphasis on high spin states. (Auth.)

High-Throughput Particle Manipulation Based on Hydrodynamic Effects in Microchannels

Directory of Open Access Journals (Sweden)

Chao Liu

2017-03-01

Full Text Available Microfluidic techniques are effective tools for precise manipulation of particles and cells, whose enrichment and separation is crucial for a wide range of applications in biology, medicine, and chemistry. Recently, lateral particle migration induced by the intrinsic hydrodynamic effects in microchannels, such as inertia and elasticity, has shown its promise for high-throughput and label-free particle manipulation. The particle migration can be engineered to realize the controllable focusing and separation of particles based on a difference in size. The widespread use of inertial and viscoelastic microfluidics depends on the understanding of hydrodynamic effects on particle motion. This review will summarize the progress in the fundamental mechanisms and key applications of inertial and viscoelastic particle manipulation.

Predicting abundance and variability of ice nucleating particles in precipitation at the high-altitude observatory Jungfraujoch

Directory of Open Access Journals (Sweden)

E. Stopelli

2016-07-01

Full Text Available Nucleation of ice affects the properties of clouds and the formation of precipitation. Quantitative data on how ice nucleating particles (INPs determine the distribution, occurrence and intensity of precipitation are still scarce. INPs active at −8 °C (INPs−8 were observed for 2 years in precipitation samples at the High-Altitude Research Station Jungfraujoch (Switzerland at 3580 m a.s.l. Several environmental parameters were scanned for their capability to predict the observed abundance and variability of INPs−8. Those singularly presenting the best correlations with observed number of INPs−8 (residual fraction of water vapour, wind speed, air temperature, number of particles with diameter larger than 0.5 µm, season, and source region of particles were implemented as potential predictor variables in statistical multiple linear regression models. These models were calibrated with 84 precipitation samples collected during the first year of observations; their predictive power was successively validated on the set of 15 precipitation samples collected during the second year. The model performing best in calibration and validation explains more than 75 % of the whole variability of INPs−8 in precipitation and indicates that a high abundance of INPs−8 is to be expected whenever high wind speed coincides with air masses having experienced little or no precipitation prior to sampling. Such conditions occur during frontal passages, often accompanied by precipitation. Therefore, the circumstances when INPs−8 could be sufficiently abundant to initiate the ice phase in clouds may frequently coincide with meteorological conditions favourable to the onset of precipitation events.

Difference in particle transport between two coastal areas in the Baltic Sea investigated with high-resolution trajectory modeling.

Science.gov (United States)

Corell, Hanna; Döös, Kristofer

2013-05-01

A particle-tracking model based on high-resolution ocean flow data was used to investigate particle residence times and spatial distribution of settling sediment for two geo-morphologically different Swedish coastal areas. The study was a part of a safety assessment for the location of a future nuclear-waste repository, and information about the particle-transport patterns can contribute to predictions of the fate of a possible leakage. It is also, to our knowledge, the first time particle-transport differences between two coastal areas have been quantified in this manner. In Forsmark, a funnel-shaped bay shielded by a number of islands, the average residence time for clay particles was 5 times longer than in the modeled part of Simpevarp, which is open to the Baltic Sea. In Forsmark, <10 % of the released particles left the domain compared to 60-80 % in Simpevarp. These site-specific differences will increase over time with the differences in land uplift between the areas.

Difference in Particle Transport Between Two Coastal Areas in the Baltic Sea Investigated with High-Resolution Trajectory Modeling

International Nuclear Information System (INIS)

Corell, Hanna; Doeoes, Kristofer

2013-01-01

A particle-tracking model based on high-resolution ocean flow data was used to investigate particle residence times and spatial distribution of settling sediment for two geo-morphologically different Swedish coastal areas. The study was a part of a safety assessment for the location of a future nuclear-waste repository, and information about the particle-transport patterns can contribute to predictions of the fate of a possible leakage. It is also, to our knowledge, the first time particle-transport differences between two coastal areas have been quantified in this manner. In Forsmark, a funnel-shaped bay shielded by a number of islands, the average residence time for clay particles was 5 times longer than in the modeled part of Simpevarp, which is open to the Baltic Sea. In Forsmark, <10 % of the released particles left the domain compared to 60-80 % in Simpevarp. These site-specific differences will increase over time with the differences in land uplift between the areas

High beta, sawtooth-free tokamak operation using energetic trapped particles

International Nuclear Information System (INIS)

White, R.B.; Bussac, M.N.; Romanelli, F.

1988-08-01

It is shown that a population of high energy trapped particles, such as that produced by ion cyclotron heating in tokamaks, can result in a plasma completely stable to both sawtooth oscillations and the fishbone mode. The stable window of operation increases in size with plasma temperature and with trapped particle energy, and provides a means of obtaining a stable plasma with high current and high beta. 13 refs., 2 figs

Simulation study for high resolution alpha particle spectrometry with mesh type collimator

International Nuclear Information System (INIS)

Park, Seunghoon; Kwak, Sungwoo; Kang, Hanbyeol; Shin, Jungki; Park, Iljin

2014-01-01

An alpha particle spectrometry with a mesh type collimator plays a crucial role in identifying specific radionuclide in a radioactive source collected from the atmosphere or environment. The energy resolution is degraded without collimation because particles with a high angle have a longer path to travel in the air. Therefore, collision with the background increases. The collimator can cut out particles which traveling at a high angle. As a result, an energy distribution with high resolution can be obtained. Therefore, the mesh type collimator is simulated for high resolution alpha particle spectrometry. In conclusion, the collimator can improve resolution. With collimator, the collimator is a role of cutting out particles with a high angle, so, low energy tail and broadened energy distribution can be reduced. The mesh diameter is found out as an important factor to control resolution and counting efficiency. Therefore, a target particle, for example, 235 U, can be distinguished by a detector with a collimator under a mixture of various nuclides, for example: 232 U, 238 U, and 232 Th

High energy model for irregular absorbing particles

International Nuclear Information System (INIS)

Chiappetta, Pierre.

1979-05-01

In the framework of a high energy formulation of relativistic quantum scattering a model is presented which describes the scattering functions and polarization of irregular absorbing particles, whose dimensions are greater than the incident wavelength. More precisely in the forward direction an amplitude parametrization of eikonal type is defined which generalizes the usual diffraction theory, and in the backward direction a reflective model is used including a shadow function. The model predictions are in good agreement with the scattering measurements off irregular compact and fluffy particles performed by Zerull, Giese and Weiss (1977)

High power density reactors based on direct cooled particle beds

International Nuclear Information System (INIS)

Powell, J.R.; Horn, F.L.

1985-01-01

Reactors based on direct cooled HTGR type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out long the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBR's) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed. 12 figs

Charged particle tracking in high multiplicity events at RHIC

International Nuclear Information System (INIS)

Foley, K.J.; Love, W.A.

1985-01-01

It is generally accepted that the ability to track some fraction of the charged particles produced in heavy ion collisions is very desirable. At a very minimum, one must detect the occurance of multiple interactions in a single crossing. The very tight beam structure at RHIC does not favor time separation, so the location of separate vertices seems the best solution. The limits of tracking large numbers of tracks in a solid angle approaching 4π have been explored. A model detector considered is a 2.5 m radius TPC, a true 3D tracking device. In order to estimate the particle density of a function of production angle, five Hijet Au-Au central events were used to deduce the particle density distribution as a function of polar angle. An important feature of a tracking detector is the effective ''pixel'' size - the area within which two tracks cannot be resolved. In a TPC with multistep avalanche chamber readout this is approximately 3 mm x 3 mm or approx.0.1 cm 2 . Using this pixel size we have calculated the radius at which the number of particles/pixel is 0.01 and 0.1. With the exception of the region very near the beam expect these distributions aren't expected to change very much with the application of a low (approx. 0.5 tesla) magnetic field. While the actual reconstruction efficiency will depend on the fine details of the apparatus and reconstruction program, the 1% fill fraction is safe for efficiencies in the 80 to 90% region. Tracking is found to be feasible at pseudorapidities up to 3

A novel robust and efficient algorithm for charge particle tracking in high background flux

International Nuclear Information System (INIS)

Fanelli, C; Cisbani, E; Dotto, A Del

2015-01-01

The high luminosity that will be reached in the new generation of High Energy Particle and Nuclear physics experiments implies large high background rate and large tracker occupancy, representing therefore a new challenge for particle tracking algorithms. For instance, at Jefferson Laboratory (JLab) (VA,USA), one of the most demanding experiment in this respect, performed with a 12 GeV electron beam, is characterized by a luminosity up to 10 39 cm -2 s -1 . To this scope, Gaseous Electron Multiplier (GEM) based trackers are under development for a new spectrometer that will operate at these high rates in the Hall A of JLab. Within this context, we developed a new tracking algorithm, based on a multistep approach: (i) all hardware - time and charge - information are exploited to minimize the number of hits to associate; (ii) a dedicated Neural Network (NN) has been designed for a fast and efficient association of the hits measured by the GEM detector; (iii) the measurements of the associated hits are further improved in resolution through the application of Kalman filter and Rauch- Tung-Striebel smoother. The algorithm is shortly presented along with a discussion of the promising first results. (paper)

High-resolution extraction of particle size via Fourier Ptychography

Science.gov (United States)

Li, Shengfu; Zhao, Yu; Chen, Guanghua; Luo, Zhenxiong; Ye, Yan

2017-11-01

This paper proposes a method which can extract the particle size information with a resolution beyond λ/NA. This is achieved by applying Fourier Ptychographic (FP) ideas to the present problem. In a typical FP imaging platform, a 2D LED array is used as light sources for angle-varied illuminations, a series of low-resolution images was taken by a full sequential scan of the array of LEDs. Here, we demonstrate the particle size information is extracted by turning on each single LED on a circle. The simulated results show that the proposed method can reduce the total number of images, without loss of reliability in the results.

Decay properties of high-lying single-particles modes

Energy Technology Data Exchange (ETDEWEB)

Beaumel, D. [Institut de Physique Nucleaire, 91 - Orsay (France); Fortier, S. [Institut de Physique Nucleaire, 91 - Orsay (France); Gales, S. [Institut de Physique Nucleaire, 91 - Orsay (France); Guillot, J. [Institut de Physique Nucleaire, 91 - Orsay (France); Langevin-Joliot, H. [Institut de Physique Nucleaire, 91 - Orsay (France); Laurent, H. [Institut de Physique Nucleaire, 91 -Orsay (France); Maison, J.M. [Institut de Physique Nucleaire, 91 - Orsay (France); Vernotte, J. [Institut de Physique Nucleaire, 91 - Orsay (France); Bordewijck, J. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Brandenburg, S. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Krasznahorkay, A. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Crawley, G.M. [NSCL, Michigan State University, East Lansing, MI 48824 (United States); Massolo, C.P. [Universitad Nacional de La Plata, 1900 La Plata (Argentina); Renteria, M. [Universitad Nacional de La Plata, 1900 La Plata (Argentina); Khendriche, A. [University of Tizi-Ouzou, Tizi-Ouzou (Algeria)

1996-03-18

The neutron decay of high-lying single-particle states in {sup 64}Ni, {sup 90}Zr, {sup 120}Sn and {sup 208}Pb excited by means of the ({alpha},{sup 3}He) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular correlation analysis. The structure located between 11 and 15 MeV in {sup 91}Zr, and between 8 and 12 MeV excitation energy in {sup 209}Pb display large departures from a pure statistical decay. The corresponding non-statistical branching ratios are compared with the results of two theoretical calculations. (orig.).

High-energy particles associated with solar flares

International Nuclear Information System (INIS)

Sakurai, K.; Klimas, A.J.

1974-05-01

High energy particles, the so-called solar cosmic rays, are often generated in association with solar flares, and then emitted into interplanetary space. These particles, consisting of electrons, protons, and other heavier nuclei, including the iron-group, are accelerated in the vicinity of the flare. By studying the temporal and spatial variation of these particles near the earth's orbit, their storage and release mechanisms in the solar corona and their propagation mechanism can be understood. The details of the nuclear composition and the rigidity spectrum for each nuclear component of the solar cosmic rays are important for investigating the acceleration mechanism in solar flares. The timing and efficiency of the acceleration process can also be investigated by using this information. These problems are described in some detail by using observational results on solar cosmic rays and associated phenomena. (U.S.)

High frequency sonar variability in littoral environments: Irregular particles and bubbles

Science.gov (United States)

Richards, Simon D.; Leighton, Timothy G.; White, Paul R.

2002-11-01

Littoral environments may be characterized by high concentrations of suspended particles. Such suspensions contribute to attenuation through visco-inertial absorption and scattering and may therefore be partially responsible for the observed variability in high frequency sonar performance in littoral environments. Microbubbles which are prevalent in littoral waters also contribute to volume attenuation through radiation, viscous and thermal damping and cause dispersion. The attenuation due to a polydisperse suspension of particles with depth-dependent concentration has been included in a sonar model. The effects of a depth-dependent, polydisperse population of microbubbles on attenuation, sound speed and volume reverberation are also included. Marine suspensions are characterized by nonspherical particles, often plate-like clay particles. Measurements of absorption in dilute suspensions of nonspherical particles have shown disagreement with predictions of spherical particle models. These measurements have been reanalyzed using three techniques for particle sizing: laser diffraction, gravitational sedimentation, and centrifugal sedimentation, highlighting the difficulty of characterizing polydisperse suspensions of irregular particles. The measurements have been compared with predictions of a model for suspensions of oblate spheroids. Excellent agreement is obtained between this model and the measurements for kaolin particles, without requiring any a priori knowledge of the measurements.

Ultrafine particle emission characteristics of diesel engine by on-board and test bench measurement.

Science.gov (United States)

Huang, Cheng; Lou, Diming; Hu, Zhiyuan; Tan, Piqiang; Yao, Di; Hu, Wei; Li, Peng; Ren, Jin; Chen, Changhong

2012-01-01

This study investigated the emission characteristics of ultrafine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of (0.56-8.35) x 10(8) cm(-3). The on-board measurement results illustrated that the ultrafine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 x 10(6) cm(-3) and 2.7 x 10(7) cm(-3) under decelerating and idling operations and as high as 5.0 x 10(8) cm(-3) under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a "U" shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.

New directions in elementary particle physics: p anti p from very low to very high energies

International Nuclear Information System (INIS)

Jacob, M.

1979-01-01

The review covers low energy anti pp physics including annihilation processes, the spectroscopy of baryonium states, quasinuclear states and their relation to baryonium, the spectroscopy of protonium, and access to the whole charmonium family. High energy anti pp physics is reviewed covering total cross section rise, the common shape of cross sections, real part of forward amplitude, particle production, quantum number excitation, high transverse momentum, and high mass lepton pair. Also reviewed are the search for the weak bosons, hadron physics at collider energies, and the anti pp collider program. 47 references

Construction of Non-Perturbative, Unitary Particle-Antiparticle Amplitudes for Finite Particle Number Scattering Formalisms

International Nuclear Information System (INIS)

Lindesay, James V

2002-01-01

Starting from a unitary, Lorentz invariant two-particle scattering amplitude, we show how to use an identification and replacement process to construct a unique, unitary particle-antiparticle amplitude. This process differs from conventional on-shell Mandelstam s,t,u crossing in that the input and constructed amplitudes can be off-diagonal and off-energy shell. Further, amplitudes are constructed using the invariant parameters which are appropriate to use as driving terms in the multi-particle, multichannel nonperturbative, cluster decomposable, relativistic scattering equations of the Faddeev-type integral equations recently presented by Alfred, Kwizera, Lindesay and Noyes. It is therefore anticipated that when so employed, the resulting multi-channel solutions will also be unitary. The process preserves the usual particle-antiparticle symmetries. To illustrate this process, we construct a J=0 scattering length model chosen for simplicity. We also exhibit a class of physical models which contain a finite quantum mass parameter and are Lorentz invariant. These are constructed to reduce in the appropriate limits, and with the proper choice of value and sign of the interaction parameter, to the asymptotic solution of the nonrelativistic Coulomb problem, including the forward scattering singularity , the essential singularity in the phase, and the Bohr bound-state spectrum

A particle-number conserving microscopic approach to octupole deformation of normal deformed and superdeformed states in 194Pb

International Nuclear Information System (INIS)

Nhan Hao, T.V.; Phu Dat, D.H.; Hoang Tung, N.; Tran, H.N.

2015-01-01

The left–right asymmetric deformation of normal deformed (ND) and superdeformed (SD) states of 194 Pb has been investigated in the framework of the parity-symmetry projection of the highly truncated diagonalization approach (HTDA), which is suited to treat the correlations in an explicitly particle-number conserving microscopic approach. A Skyrme energy density functional using the SIII and SkM* interactions has been considered to treat the particle–hole channel, whereas a density-independent δ force has been adopted for the residual interaction. The obtained results are compared with previous approaches. The calculated octupole phonon excitation energy is found to be in good qualitative agreement with available data in the ND state. (author)

The Granular Blasius Problem: High inertial number granular flows

Science.gov (United States)

Tsang, Jonathan; Dalziel, Stuart; Vriend, Nathalie

2017-11-01

The classical Blasius problem considers the formation of a boundary layer through the change at x = 0 from a free-slip to a no-slip boundary beneath an otherwise steady uniform flow. Discrete particle model (DPM) simulations of granular gravity currents show that a similar phenomenon exists for a steady flow over a uniformly sloped surface that is smooth upstream (allowing slip) but rough downstream (imposing a no-slip condition). The boundary layer is a region of high shear rate and therefore high inertial number I; its dynamics are governed by the asymptotic behaviour of the granular rheology as I -> ∞ . The μ(I) rheology asserts that dμ / dI = O(1 /I2) as I -> ∞ , but current experimental evidence is insufficient to confirm this. We show that `generalised μ(I) rheologies', with different behaviours as I -> ∞ , all permit the formation of a boundary layer. We give approximate solutions for the velocity profile under each rheology. The change in boundary condition considered here mimics more complex topography in which shear stress increases in the streamwise direction (e.g. a curved slope). Such a system would be of interest in avalanche modelling. EPSRC studentship (Tsang) and Royal Society Dorothy Hodgkin Fellowship (Vriend).

Particle identification methods in High Energy Physics

Energy Technology Data Exchange (ETDEWEB)

Va' Vra, J.

2000-01-27

This paper deals with two major particle identification methods: dE/dx and Cherenkov detection. In the first method, the authors systematically compare existing dE/dx data with various predictions available in the literature, such as the Particle Data group recommendation, and judge the overall consistency. To my knowledge, such comparison was not done yet in a published form for the gaseous detectors used in High-Energy physics. As far as the second method, there are two major Cherenkov light detection techniques: the threshold and the Ring imaging methods. The authors discuss the recent trend in these techniques.

Particle cosmology comes of age

International Nuclear Information System (INIS)

Turner, M.S.

1988-01-01

The application of modern ideas in particle physics to astrophysical and cosmological settings is a continuation of a fruitful tradition in astrophysics which began with the application of atomic physics, and then nuclear physics. In the past decade particle cosmology and particle astrophysics have been recognized as 'legitimate activities' by both particle physicists and astrophysicists and astronomers. During this time there has been a high level of theoretical activity producing much speculation about the earliest history of the Universe, as well as important and interesting astrophysical and cosmological constraints to particle physics theories. This period of intense theoretical activity has produced a number of ideas most worthy of careful consideration and scrutiny, and even more importantly, amenable to experimental/observational test. Among the ideas which are likely to be tested in the next decade are: the cosmological bound to the number of neutrino flavors, inflation, relic WIMPs as the dark matter, and MSW neutrino oscillations as a solution to the solar neutrino problems. (orig.)

Particle cosmology comes of age

International Nuclear Information System (INIS)

Turner, M.S.

1987-12-01

The application of modern ideas in particle physics to astrophysical and cosmological settings is a continuation of a fruitful tradition in astrophysics which began with the application of atomic physics, and then nuclear physics. In the past decade particle cosmology and particle astrophysics have been recognized as 'legitimate activities' by both particle physicists and astrophysicists and astronomers. During this time there has been a high level of theoretical activity producing much speculation about the earliest history of the Universe, as well as important and interesting astrophysical and cosmological constraints to particle physics theories. This period of intense theoretical activity has produced a number of ideas most worthy of careful consideration and scrutiny, and even more importantly, amenable to experimental/observational test. Among the ideas which are likely to be tested in the next decade are: the cosmological bound to the number of neutrino flavors, inflation, relic WIMPs as the dark matter, and MSW neutrino oscillations as a solution to the solar neutrino problems. 94 refs

High $p_T$ particle correlations in pp collisions at LHC/ALICE

CERN Document Server

Mao, Yaxian

2011-01-01

Two-particle correlation triggered by high-\\pt{} particles allows us to study hard scattering phenomena when full jet reconstruction is challenging. An analysis of the first ALICE pp data where charged and neutral particles isolated or not are used as trigger particles is presented. The two-particle correlation between the trigger ($t$) and the associate ($a$) particles is studied as a function of the imbalance parameter \\xe=-$\\vec{p}_{T_{a}} \\cdot \\vec{p}_{T_{t}}/\\mid \\vec{p}_{T_{t}}\\mid ^{2}$ and interpreted in terms of jet fragmentation function.

Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

International Nuclear Information System (INIS)

Guo Zhanhu; Park, Sung; Wei Suying; Pereira, Tony; Moldovan, Monica; Karki, Amar B; Young, David P; Hahn, H Thomas

2007-01-01

Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer-particle interactions

High-energy charged particle bursts in the near-Earth space as earthquake precursors

Directory of Open Access Journals (Sweden)

S. Yu. Aleksandrin

2003-02-01

Full Text Available The experimental data on high-energy charged particle fluxes, obtained in various near-Earth space experiments (MIR orbital station, METEOR-3, GAMMA and SAMPEX satellites were processed and analyzed with the goal to search for particle bursts. Particle bursts have been selected in every experiment considered. It was shown that the significant part of high-energy charged particle bursts correlates with seismic activity. Moreover, the particle bursts are observed several hours before strong earthquakes; L-shells of particle bursts and corresponding earthquakes are practically the same. Some features of a seismo-magnetosphere connection model, based on the interaction of electromagnetic emission of seismic origin and radiation belt particles, were considered. Key words. Ionospheric physics (energetic particles, trapped; energetic particles, precipitating; magnetosphere-ionosphere interactions

Numerical Study of Particle Interaction in Gas-Particle and Liquid-Particle Flows: Part II Particle Response

Directory of Open Access Journals (Sweden)

K. Mohanarangam

2009-09-01

Full Text Available In this paper the numerical model, which was presented in the first paper (Mohanarangam & Tu; 2009 of this series of study, is employed to study the different particle responses under the influence of two carrier phases namely the gas and the liquid. The numerical model takes into consideration the turbulent behaviour of both the carrier and the dispersed phases, with additional equations to take into account the combined fluid particle behaviour, thereby effecting a two-way coupling. The first paper in this series showed the distinct difference in particulate response both at the mean as well as at the turbulent level for two varied carrier phases. In this paper further investigation has been carried out over a broad range of particle Stokes number to further understand their behaviour in turbulent environments. In order to carry out this prognostic study, the backward facing step geometry of Fessler and Eaton (1999 has been adopted, while the inlet conditions for the carrier as well as the particle phases correspond to that of the experiments of Founti and Klipfel (1998. It is observed that at the mean velocity level the particulate velocities increased with a subsequent increase in the Stokes number for both the GP (Gas-Particle as well as the LP (Liquid-Particle flow. It was also observed that across the Stokes number there was a steady increase in the particulate turbulence for the GP flows with successive increase in Stokes number. However, for the LP flows, the magnitude of the increase in the particulate turbulence across the increasing of Stokes number is not as characteristic as the GP flow. Across the same sections for LP flows the majority of the trend shows a decrease after which they remain more or less a constant.

Isovector pairing effect on the particle-number projection two-proton separation energy

Energy Technology Data Exchange (ETDEWEB)

Mokhtari, Djamila; Kerrouchi, Slimane [Laboratoire de Physique Theorique, Faculte de Physique, Algiers (Algeria); Fellah, Mohamed; Allal, Nassima-Hosni [Laboratoire de Physique Theorique, Faculte de Physique, Algiers (Algeria); Centre de Recherche Nucleaire d' Alger, Comena, Algiers (Algeria)

2009-07-01

The two-proton separation energy is studied by performing a particle-number projection with and without inclusion of the isovector neutron-proton (np) pairing correlations. It is numerically evaluated for even-even rare-earth nuclei such that the np pairing parameter is non-zero. It is shown that the two-proton separation energy values calculated using the two approaches join, for almost all the considered elements, for the highest values of (N-Z). However, the results including the np pairing correlations are closest to the experimental data when available. Moreover, the two methods lead to the same prediction of the two-proton drip-line position, except for the Dysprosium and the Tungsten.

A comparative study of the number and mass of fine particles emitted with diesel fuel and marine gas oil (MGO)

Science.gov (United States)

Nabi, Md. Nurun; Brown, Richard J.; Ristovski, Zoran; Hustad, Johan Einar

2012-09-01

The current investigation reports on diesel particulate matter emissions, with special interest in fine particles from the combustion of two base fuels. The base fuels selected were diesel fuel and marine gas oil (MGO). The experiments were conducted with a four-stroke, six-cylinder, direct injection diesel engine. The results showed that the fine particle number emissions measured by both SMPS and ELPI were higher with MGO compared to diesel fuel. It was observed that the fine particle number emissions with the two base fuels were quantitatively different but qualitatively similar. The gravimetric (mass basis) measurement also showed higher total particulate matter (TPM) emissions with the MGO. The smoke emissions, which were part of TPM, were also higher for the MGO. No significant changes in the mass flow rate of fuel and the brake-specific fuel consumption (BSFC) were observed between the two base fuels.

Charge identification of highly ionizing particles in desensitized nuclear emulsion using high speed read-out system

International Nuclear Information System (INIS)

Toshito, T.; Kodama, K.; Yusa, K.; Ozaki, M.; Amako, K.; Kameoka, S.; Murakami, K.; Sasaki, T.; Aoki, S.; Ban, T.; Fukuda, T.; Naganawa, N.; Nakamura, T.; Natsume, M.; Niwa, K.; Takahashi, S.; Kanazawa, M.; Kanematsu, N.; Komori, M.; Sato, S.; Asai, M.; Koi, T.; Fukushima, C.; Ogawa, S.; Shibasaki, M.; Shibuya, H.

2006-01-01

We performed an experimental study of charge identification of heavy ions from helium to carbon having energy of about 290MeV/u using an emulsion chamber. Emulsion was desensitized by means of forced fading (refreshing) to expand a dynamic range of response to highly charged particles. For the track reconstruction and charge identification, the fully automated high speed emulsion read-out system, which was originally developed for identifying minimum ionizing particles, was used without any modification. Clear track by track charge identification up to Z=6 was demonstrated. The refreshing technique has proved to be a powerful technique to expand response of emulsion film to highly ionizing particles

Collective and single-particle states at high excitation energy

International Nuclear Information System (INIS)

Van den Berg, A.M.; Van der Molen, H.K.T.; Harakeh, M.N.; Akimune, H.; Daito, I.; Fujimura, H.; Fujiwara, M.; Ihara, F.; Inomata, T.

2000-01-01

Complete text of publication follows. Damping of high-lying single-particle states was investigated by the study of proton decay from high-lying states in 91 Nb, populated by the 90 Zr(α,t) reaction with E α = 180 MeV. In addition to decay to the ground state of 90 Zr, semi-direct decay was observed to the low-lying (2 + and 3 - ) phonon states, confirming the conclusion from other experiments that these phonon states play an important role in the damping process of the single-particle states. Furthermore, the population and decay of Isobaric Analogue States of 91 Zr, which are located at an excitation energy of about 10 - 12 MeV in 91 Nb, has been studied in the same reaction. (author)

Ultrasmooth, Highly Spherical Monocrystalline Gold Particles for Precision Plasmonics

KAUST Repository

Lee, You-Jin

2013-12-23

Ultrasmooth, highly spherical monocrystalline gold particles were prepared by a cyclic process of slow growth followed by slow chemical etching, which selectively removes edges and vertices. The etching process effectively makes the surface tension isotropic, so that spheres are favored under quasi-static conditions. It is scalable up to particle sizes of 200 nm or more. The resulting spherical crystals display uniform scattering spectra and consistent optical coupling at small separations, even showing Fano-like resonances in small clusters. The high monodispersity of the particles we demonstrate should facilitate the self-assembly of nanoparticle clusters with uniform optical resonances, which could in turn be used to fabricate optical metafluids. Narrow size distributions are required to control not only the spectral features but also the morphology and yield of clusters in certain assembly schemes. © 2013 American Chemical Society.

Particle Emissions from Biomass Combustion

Energy Technology Data Exchange (ETDEWEB)

Szpila, Aneta; Bohgard, Mats [Lund Inst. of Technology (Sweden). Div. of Ergonomics and Aerosol Technology; Strand, Michael; Lillieblad, Lena; Sanati, Mehri [Vaexjoe Univ. (Sweden). Div. of Bioenergy Technology; Pagels, Joakim; Rissler, Jenny; Swietlicki, Erik; Gharibi, Arash [Lund Univ. (Sweden). Div. of Nuclear Physics

2003-05-01

We have shown that high concentrations of fine particles of the order of 2-7x10{sup -7} particles per cm{sup 3} are being formed in all the combustion units studied. There was a higher difference between the units in terms of particle mass concentrations. While the largest differences was found for gas-phase constituents (CO and THC) and polyaromatic hydrocarbons. In 5 out of 7 studied units, multi-cyclones were the only measure for flue-gas separation. The multicyclones had negligible effect on the particle number concentration and a small effect on the mass of particles smaller than 5 {mu}m. The separation efficiency was much higher for the electrostatic precipitators. The boiler load had a dramatic influence on the coarse mode concentration during combustion of forest residue. PM0.8-6 increased from below 5 mg/m{sup 3} to above 50 mg/m{sup 3} even at a moderate change in boiler load from medium to high. A similar but less pronounced trend was found during combustion of dry wood. PM0.8-PM6 increased from 12 to 23 mg/m{sup 3} when the load was changed from low to high. When increasing the load, the primary airflow taken through the grate is increased; this itself may lead to a higher potential of the air stream to carry coarse particles away from the combustion zone. Measurements with APS-instrument with higher time-resolution showed a corresponding increase in coarse mode number concentration with load. Additional factor influencing observed higher concentration of coarse mode during combustion of forest residues, could be relatively high ash content in this type of fuel (2.2 %) in comparison to dry wood (0.3 %) and pellets (0.5 %). With increasing load we also found a decrease in PM1 during combustion of forest residue. Whether this is caused by scavenging of volatilized material by the high coarse mode concentration or a result of a different amount of volatilized material available for formation of fine particles needs to be shown in future studies. The

Method of determining the partial cross sections in a heavy liquid. Application to the production of strange particles by high energy π"-

International Nuclear Information System (INIS)

Lloret, Antonio

1964-01-01

This research thesis reports the study if the measurement of cross sections on proton, and more particularly the development of a method of determination of cross sections which takes problems raised by a heavy liquid into account. This method is applied with sufficiently high energies for the Fermi momentum to have no influence on cross sections. The author first presents the general method of determination of partial cross sections in a heavy liquid: case of a hydrogen chamber, ideal case of a heavy liquid chamber without possibility of secondary interactions nor evaporations, search for a formula removing secondary interactions, correction due to the fact that the number of neutrons is not equal to the number of protons in the mixture nuclei, application to cross sections of production of high energy strange particles, calculation of the number of produced high energy particles. The experiment is then presented with its chamber, its measurement and calculation techniques. The author then reports and discusses cross section calculations and compares results with those of previous experiments. The last part addresses the study of secondary interactions in nuclei

Induced fission track distribution from highly radioactive particles in fallout materials

International Nuclear Information System (INIS)

Hashimoto, Tetsuo; Okada, Tatemichi

1987-01-01

Some highly radioactive fallout particles (GPs) from the 19th Chinese nuclear detonation were followed to the neutron irradiation in a reactor after sandwiched with mica detectors. The interesting star-like fission track patterns were revealed on the etched surface of the mica detectors. The simple chemical separation procedure for the GPs was applied for the separation of U and Pu as fissile elements and the both resultant fractions were examined with the similar high sensitive fission tracking detection. Subsequently, a representative track pattern from a black spherical particle was subjected to the determination of fissile nuclide content; comparing the total fission events evaluated on the basis of the numerical calculation of track densities with the total thermal neutron fluence. The results implied that the uranium is responsible for the main fissile nuclide remaining within a particle as unfissioned fractions and should be certainly enriched with respect to U-235 within such small fallout particles. This sophisticated method was also applied to determine the dead GPs, which have been highly radioactive particles just after the detonations, in the rain and snow-residual materials. Many induced star-like fission tracks verified certainly that there remains a lot of dead particles in the atmosheric environment till nowadays. (author)

Theoretical aspects of effects of high-energy particles on MHD modes

International Nuclear Information System (INIS)

Villard, L.; Brunner, S.; Vaclavik, J.

1994-01-01

In this paper we adopt a global approach. The TAEs are computed globally in true toroidal geometry consistent with an ideal MHD equilibrium. Kinetic effects (damping and driving mechanisms) and fast particles are treated perturbatively. More precisely, we first obtain the global eigenmodes an then use these given eigenmode fields to evaluate the global overall wave-particle power transfer assuming given fast particle density profiles. The marginal stability point is obtained by scaling the number of fast particles so that the overall power transfer is zero. The wave-particle power transfers are evaluated using the drift-kinetic equations. The paper is structured as follows: In section two, the plasma model in toroidal geometry is briefly presented. The expressions for the DKE powers are derived for the various species in the companion paper in these proceedings. In section 3 we show the results of our model applied to a wide variety of plasma parameters. In particular, the critical volume-averaged fast particle beta corresponding to marginal stability, f > cr , is calculated for a wide range of bulk plasma parameters and fast particle profile widths. We discuss the results in section 4 and draw some conclusions in section 5.(author) 13 figs., 21 refs

Atom probe characterization of yttria particles in ODS Eurofer steel

International Nuclear Information System (INIS)

Aleev, A.A.; Zaluzhny, A.G.; Nikitin, A.A.; Rogozhkin, S.V.; Iskandarov, N.A.; Vladimirov, P.; Moeslang, A.; Lindau, R.; Klimenkov, M.

2009-01-01

Oxide dispersion strengthened steels exhibit higher temperature and radiation resistance than conventionally produced ferritic/martensitic steels. Such behaviour, as believed, is mainly caused by presence of highly dispersed and extremely stable oxide particles with sizes of few nanometers. It was shown that the most promising oxide additive was yttria (Y 2 O 3 ) and as mechanical parameters were strongly depended on size and number density of formed peculiarities it is required to reduce their dimensions to few nanometers and drastically increase their number. At present, considerable effort is focused on investigation of behaviour and properties of such particles. Recent studies of Eurofer ODS steel (9%-CrWVTa) by SANS and PoAS revealed the presence of high number density structural peculiarities with size approximately one nanometer. At the same time, previous studies by TEM identified only high number of small (5-10 nm) Y 2 O 3 particles. So, the purpose of this work was to look into this material by means of tomographic atom probe and find out the chemistry and origin of peculiarities with sizes less than 5 nm. These investigations revealed fine (∼ 2 nm) particles that were enriched not only in yttrium and oxygen but also in vanadium and nitrogen. Concentration of vanadium in them is approximately at the same level as yttrium. Moreover, some particles were found to be enriched in only three or even two elements mentioned above. However, total concentration of chemical elements in these particles is considerably less than that of iron. Estimated number density for detected particles is (1 / 5) x 10 23 m -3 . (author)

Energetics and dynamics of droplet evaporation in high temperature intermediate Reynolds number flows

Science.gov (United States)

Renksizbulut, M.

Nusselt Numbers and drag coefficients of single-component liquid droplets and solid spheres in high temperature, intermediate Reynolds Number flows were investigated. The evaporation of suspended water, Methanol and n-Heptane droplets were followed in laminar air streams up to 1059 K in temperature using a steady-state measurement technique. It is found that the dynamic blowing effect of evaporation causes large reductions in heat transfer rates, and that the film conditions constitute an appropriate reference state for the evaluation of thermophysical properties. The numerical results indicate that the blowing effect of evaporation on momentum transfer is to reduce friction drag very significantly but at the same time increase pressure drag by almost an equal amount; the net effect on the total drag force being only a marginal reduction. In all cases, it is found that thermophysical property variations play a very dominant role in reducing the drag forces acting on cold particles. Results are analysed and a correlation for stagnation-point heat transfer is also presented.

Load management strategy for Particle-In-Cell simulations in high energy particle acceleration

Energy Technology Data Exchange (ETDEWEB)

Beck, A., E-mail: beck@llr.in2p3.fr [Laboratoire Leprince-Ringuet, École polytechnique, CNRS-IN2P3, Palaiseau 91128 (France); Frederiksen, J.T. [Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø (Denmark); Dérouillat, J. [CEA, Maison de La Simulation, 91400 Saclay (France)

2016-09-01

In the wake of the intense effort made for the experimental CILEX project, numerical simulation campaigns have been carried out in order to finalize the design of the facility and to identify optimal laser and plasma parameters. These simulations bring, of course, important insight into the fundamental physics at play. As a by-product, they also characterize the quality of our theoretical and numerical models. In this paper, we compare the results given by different codes and point out algorithmic limitations both in terms of physical accuracy and computational performances. These limitations are illustrated in the context of electron laser wakefield acceleration (LWFA). The main limitation we identify in state-of-the-art Particle-In-Cell (PIC) codes is computational load imbalance. We propose an innovative algorithm to deal with this specific issue as well as milestones towards a modern, accurate high-performance PIC code for high energy particle acceleration.

High-energy particle diffraction

International Nuclear Information System (INIS)

Barone, V.; Predazzi, E.

2002-01-01

This monograph gives a comprehensive and up-to-date overview of soft and hard diffraction processes in strong interaction physics. The first part covers the general formalism (the optical analogy, the eikonal picture, high-energy kinematics, S-matrix theory) and soft hadron-hadron scattering (including the Regge theory) in a complete and mature presentation. It can be used as a textbook in particle physics classes. The remainder of the book is devoted to the 'new diffraction': the pomeron in QCD, low-x physics, diffractive deep inelastic scattering and related processes, jet production etc. It presents recent results and experimental findings and their phenomenological interpretations. This part addresses graduate students as well as researchers. (orig.)

Scintillation and ionization yields produced by α-particles in high-density gaseous xenon

International Nuclear Information System (INIS)

Kusano, H.; Ishikawa, T.; Lopes, J.A.M.; Miyajima, M.; Shibamura, E.; Hasebe, N.

2012-01-01

The average numbers of scintillation photons and liberated electrons produced by 5.49-MeV α-particles were measured in high-density gaseous xenon. The density range is 0.12–1.32 g/cm 3 for scintillation measurements at zero electric field, and 0.12–1.03 g/cm 3 for the scintillation and ionization measurements under various electric fields. The density dependence of scintillation yield at zero electric field was observed. The W s -value, which is defined as the average energy expended per photon, increases with density and becomes almost constant in the density range above 1.0 g/cm 3 . Anti-correlations between average numbers of scintillation photons and liberated electrons were found to vary with density. It was also found that the total number of scintillation photons and liberated electrons decreases with increasing density. Several possible reasons for the variation in scintillation and ionization yields with density are discussed.

Fractal Dimension of Particle Showers Measured in a Highly Granular Calorimeter

CERN Document Server

Ruan, Manqi; Bourdy, Vincent; Brients, Jean-Claude; Videau, Henri

2014-01-01

fractal dimension of showers measured in a high granularity calorimeter designed for a future lepton collider. The shower fractal dimension reveals detailed information of the spatial configuration of the shower. It is found to be characteristic of the type of interaction and highly sensitive to the nature of the incident particle. Using the shower fractal dimension, we demonstrate a particle identification algorithm that can efficiently separate electromagnetic showers, hadronic showers and non-showering tracks. We also find a logarithmic dependence of the shower fractal dimension on the particle energy.

New challenges in high-energy particle radiobiology

Science.gov (United States)

2014-01-01

Densely ionizing radiation has always been a main topic in radiobiology. In fact, α-particles and neutrons are sources of radiation exposure for the general population and workers in nuclear power plants. More recently, high-energy protons and heavy ions attracted a large interest for two applications: hadrontherapy in oncology and space radiation protection in manned space missions. For many years, studies concentrated on measurements of the relative biological effectiveness (RBE) of the energetic particles for different end points, especially cell killing (for radiotherapy) and carcinogenesis (for late effects). Although more recently, it has been shown that densely ionizing radiation elicits signalling pathways quite distinct from those involved in the cell and tissue response to photons. The response of the microenvironment to charged particles is therefore under scrutiny, and both the damage in the target and non-target tissues are relevant. The role of individual susceptibility in therapy and risk is obviously a major topic in radiation research in general, and for ion radiobiology as well. Particle radiobiology is therefore now entering into a new phase, where beyond RBE, the tissue response is considered. These results may open new applications for both cancer therapy and protection in deep space. PMID:24198199

Particle states of lattice QCD

Energy Technology Data Exchange (ETDEWEB)

Kapoyannis, A.S.; Panagiotou, A.D. [University of Athens, Nuclear and Particle Physics Section, Faculty of Physics, Athens (Greece)

2017-11-15

We determine the degeneracy factor and the average particle mass of particles that produce the lattice QCD pressure and specific entropy at zero baryon chemical potential. The number of states of the gluons and the quarks are found to converge above T = 230 MeV to almost constant values, close to the number of states of an ideal quark-gluon phase, while their assigned masses retain high values. The number of states and the average mass of a system containing quarks in interaction with gluons are found to decrease steeply with increase of temperature between T ∝ 150 and 160 MeV, a region contained within the region of the chiral transition. The minimum value of the number of states within this temperature interval indicates that the states are of hadronic nature. (orig.)

High performance current controller for particle accelerator magnets supply

DEFF Research Database (Denmark)

Maheshwari, Ram Krishan; Bidoggia, Benoit; Munk-Nielsen, Stig

2013-01-01

The electromagnets in modern particle accelerators require high performance power supply whose output is required to track the current reference with a very high accuracy (down to 50 ppm). This demands very high bandwidth controller design. A converter based on buck converter topology is used...

Energetic Particles at High Latitudes of the Heliosphere

International Nuclear Information System (INIS)

Zhang Ming

2004-01-01

Ulysses has by now made two complete out-of-ecliptic orbits around the sun. The first encounter of the solar poles occurred in 1994-1995, when the sun was near the minimum of its activity cycle, while the second one was in 2000-2001, when the sun was at solar maximum. To our surprise, energetic particles of all origins at high latitude are not much different from those we observe near the ecliptic for at least these two phases of solar cycle. The latitude gradients of galactic and anomalous cosmic rays are positive but small at the 1994-1995 solar minimum and almost zero at the 2000-2001 solar maximum, while temporal solar cycle variation dominates their flux variation at all latitudes. Solar energetic particles from all large gradual events can be seen at both Ulysses and Earth no matter how large their spatial separations from the solar event are, and the particle flux often reaches a uniform level in the entire inner heliosphere within a few days after event onset and remains so throughout the decay phase that can sometimes last over a month. Energetic particles accelerated by low-latitude CIRs can appear at high latitudes, far beyond the latitudinal range of CIRs. All these observations suggest that latitudinal transport of energetic particles is quite easy. In addition, because the average magnetic field is radial at the pole, The Ulysses observations indicate that parallel diffusion and drift in the radial direction need to be reduced at the poles relative to their equatorial values. To achieve such behaviors of particle transport, the heliospheric magnetic field needs a significant latitudinal component at the poles. A non-zero latitudinal magnetic field component can be produced by latitudinal motion of the magnetic field line in solar corona, which can be in form of either random walk suggested by Jokipii or large scale systematic motion suggested by Fisk

Charge-coupled devices for particle detection with high spatial resolution

International Nuclear Information System (INIS)

Farley, F.J.; Damerell, C.J.S.; Gillman, A.R.; Wickens, F.J.

1980-10-01

The results of a study of the possible application of a thin microelectronic device (the charge-coupled device) to high energy physics as particle detectors with good spatial resolution which can distinguish between tracks emerging from the primary vertex and those from secondary vertices due to the decay of short lived particles with higher flavours, are reported. Performance characteristics indicating the spatial resolution, particle discrimination, time resolution, readout time and lifetime of such detectors have been obtained. (U.K.)

Characteristics of Ambient Black Carbon Mass and Size-Resolved Particle Number Concentrations during Corn Straw Open-Field Burning Episode Observations at a Rural Site in Southern Taiwan.

Science.gov (United States)

Cheng, Yu-Hsiang; Yang, Li-Sing

2016-07-08

Information on the effect of open-field burning of agricultural residues on ambient black carbon (BC) mass and size-resolved particle number concentrations is scarce. In this study, to understand the effect of such open-field burning on short-term air quality, real-time variations of the BC mass and size-resolved particle number concentrations were monitored before and during a corn straw open-field burning episode at a rural site. Correlations between the BC mass and size-resolved particle number concentrations during the episode were investigated. Moreover, the particle number size distribution and absorption Ångström exponent were determined for obtaining the characteristics of aerosol emissions from the corn straw open-field burning. The results can be used to address public health concerns and as a reference for managing similar episodes of open-field burning of agricultural residues.

Graphical User Interface for High Energy Multi-Particle Transport, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Computer codes such as MCNPX now have the capability to transport most high energy particle types (34 particle types now supported in MCNPX) with energies extending...

Graphical User Interface for High Energy Multi-Particle Transport, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Computer codes such as MCNPX now have the capability to transport most high energy particle types (34 particle types now supported in MCNPX) with energies extending...

Quantum entanglement of identical particles

International Nuclear Information System (INIS)

Shi Yu

2003-01-01

We consider entanglement in a system with a fixed number of identical particles. Since any operation should be symmetrized over all the identical particles and there is the precondition that the spatial wave functions overlap, the meaning of identical-particle entanglement is fundamentally different from that of distinguishable particles. The identical-particle counterpart of the Schmidt basis is shown to be the single-particle basis in which the one-particle reduced density matrix is diagonal. But it does not play a special role in the issue of entanglement, which depends on the single-particle basis chosen. The nonfactorization due to (anti)symmetrization is naturally excluded by using the (anti)symmetrized basis or, equivalently, the particle number representation. The natural degrees of freedom in quantifying the identical-particle entanglement in a chosen single-particle basis are occupation numbers of different single-particle basis states. The entanglement between effectively distinguishable spins is shown to be a special case of the occupation-number entanglement

Delay in solar energetic particle onsets at high heliographic latitudes

Directory of Open Access Journals (Sweden)

S. Dalla

2003-06-01

Full Text Available Ulysses observations have shown that solar energetic particles (SEPs can easily reach high heliographic latitudes. To obtain information on the release and propagation of SEPs prior to their arrival at Ulysses, we analyse the onsets of nine large high-latitude particle events. We measure the onset times in several energy channels, and plot them versus inverse particle speed. This allows us to derive an experimental path length and time of release from the solar atmosphere. We repeat the procedure for near-Earth observations by Wind and SOHO. We find that the derived path lengths at Ulysses are 1.06 to 2.45 times the length of a Parker spiral magnetic field line connecting the spacecraft to the Sun. The time of particle release from the Sun is between 100 and 350 min later than the release time derived from in-ecliptic measurements. We find no evidence of correlation between the delay in release and the inverse of the speed of the CME associated with the event, or the inverse of the speed of the corresponding interplanetary shock. The main parameter determining the magnitude of the delay appears to be the difference in latitude between the flare and the footpoint of the spacecraft.Key words. Interplanetary physics (energetic particles – Solar physics, astrophysics and astronomy (energetic particles, flares and mass ejections

A low-cost, high-magnification imaging system for particle sizing applications

International Nuclear Information System (INIS)

Tipnis, Tanmay J; Lawson, Nicholas J; Tatam, Ralph P

2014-01-01

A low-cost imaging system for high magnification and high resolution was developed as an alternative to long-working-distance microscope-based systems, primarily for particle sizing applications. The imaging optics, comprising an inverted fixed focus lens coupled to a microscope objective, were able to provide a working distance of approximately 50 mm. The system magnification could be changed by using an appropriate microscope objective. Particle sizing was achieved using shadow-based techniques with the backlight illumination provided by a pulsed light-emitting diode light source. The images were analysed using commercial sizing software which gave the particle sizes and their distribution. A range of particles, from 6 to 8 µm to over 100 µm, was successfully measured with a minimum spatial resolution of approximately 2.5 µm. This system allowed measurement of a wide range of particles at a lower cost and improved operator safety without disturbing the flow. (technical design note)

Low-frequency modes with high toroidal mode numbers. A general formulation

International Nuclear Information System (INIS)

Pegoraro, F.; Schep, T.J.

1979-09-01

Low-frequency waves with high toroidal mode numbers in an axisymmetric toroidal configuration are studied. In particular, the relationship between the periodicity constraints imposed by the geometry, magnetic shear and the spatial structure of eigenmodes is investigated. By exploiting the radial translational invariance and the poloidal periodicity of the gyrokinetic and Maxwell equations, the two-dimensional problem can be converted into a one-dimensional one and the mode structure can be expressed in terms of a single extended poloidal variable. This representation is used in the description of electromagnetic modes with phase velocities larger than the ion thermal velocity and with frequencies below the ion gyro-frequency. Trapped particle, curvature and compressional effects are retained. The dispersion equations for drift mode and Alfven-type modes are given in general geometry and simplified solutions are presented in the configuration of a double periodic plane slab. (Auth.)

Modelling of prompt losses of high energy charged particles in Tokamaks

International Nuclear Information System (INIS)

Dillner, Oe.; Anderson, D.; Hamnen, H.; Lisak, M.

1990-01-01

A simple analytical expression for the total prompt loss fraction of high energy charged particles in an axisymmetric Tokamak is derived. The results are compared with predictions obtained from numerical simulations and show good agreement. An application is made to sawtooth induced changes in the losses of fusion generated high energy charged particles. Particular emphasis is given to the importance of sawtooth induced profile changes of the background ion densities and temperature as well as to redistribution of particles which have accumulated during the sawtooth rise but are being lost by redistribution at the sawtooth crash. (au)

Scattering of a high-order Bessel beam by a spheroidal particle

Science.gov (United States)

Han, Lu

2018-05-01

Within the framework of generalized Lorenz-Mie theory (GLMT), scattering from a homogeneous spheroidal particle illuminated by a high-order Bessel beam is formulated analytically. The high-order Bessel beam is expanded in terms of spheroidal vector wave functions, where the spheroidal beam shape coefficients (BSCs) are computed conveniently using an intrinsic method. Numerical results concerning scattered field in the far zone are displayed for various parameters of the incident Bessel beam and of the scatter. These results are expected to provide useful insights into the scattering of a Bessel beam by nonspherical particles and particle manipulation applications using Bessel beams.

Cryogenic Beam Screens for High-Energy Particle Accelerators

CERN Document Server

Baglin, V; Tavian, L; van Weelderen, R

2013-01-01

Applied superconductivity has become a key enabling technology for high-energy particle accelerators, thus making them large helium cryogenic systems operating at very low temperature. The circulation of high-intensity particle beams in these machines generates energy deposition in the first wall through different processes. For thermodynamic efficiency, it is advisable to intercept these beam-induced heat loads, which may be large in comparison with cryostat heat in-leaks, at higher temperature than that of the superconducting magnets of the accelerator, by means of beam screens located in the magnet apertures. Beam screens may also be used as part of the ultra-high vacuum system of the accelerator, by sheltering the gas molecules cryopumped on the beam pipe from impinging radiation and thus avoiding pressure runaway. Space being extremely tight in the magnet apertures, cooling of the long, slender beam screens also raises substantial problems in cryogenic heat transfer and fluid flow. We present sizing rule...

Particle Physics in High School: A Diagnose Study.

Directory of Open Access Journals (Sweden)

Paula Tuzón

Full Text Available The science learning process improves when the contents are connected to students' lives. Particle physics has had a great impact in our society in the last years and has changed the theoretical picture about matter fundamental dynamics. Thus, we think that academic contents about matter components and interactions should be updated. With this study we aim to characterize the level of knowledge of high school students about this topic. We built a test with questions about classical atomic models, particle physics, recent discoveries, social implications and students opinions about it. Contrary to our first suspicion, students' answers show a high variability. They have new physics ideas and show a great interest towards modern concepts. We suggest including an updated view of this topic as part of the curriculum.

Particle Physics in High School: A Diagnose Study.

Science.gov (United States)

Tuzón, Paula; Solbes, Jordi

2016-01-01

The science learning process improves when the contents are connected to students' lives. Particle physics has had a great impact in our society in the last years and has changed the theoretical picture about matter fundamental dynamics. Thus, we think that academic contents about matter components and interactions should be updated. With this study we aim to characterize the level of knowledge of high school students about this topic. We built a test with questions about classical atomic models, particle physics, recent discoveries, social implications and students opinions about it. Contrary to our first suspicion, students' answers show a high variability. They have new physics ideas and show a great interest towards modern concepts. We suggest including an updated view of this topic as part of the curriculum.

Quantum random number generator

Science.gov (United States)

Soubusta, Jan; Haderka, Ondrej; Hendrych, Martin

2001-03-01

Since reflection or transmission of a quantum particle on a beamsplitter is inherently random quantum process, a device built on this principle does not suffer from drawbacks of neither pseudo-random computer generators or classical noise sources. Nevertheless, a number of physical conditions necessary for high quality random numbers generation must be satisfied. Luckily, in quantum optics realization they can be well controlled. We present an easy random number generator based on the division of weak light pulses on a beamsplitter. The randomness of the generated bit stream is supported by passing the data through series of 15 statistical test. The device generates at a rate of 109.7 kbit/s.

A time of flight detector for high energy heavy particles

Energy Technology Data Exchange (ETDEWEB)

Fang, Z.; O`Connor, D.J. [Newcastle Univ., NSW (Australia). Dept. of Physics

1993-12-31

As a commonly used method to measure the energy of a particle with known mass, the flight time of the particle travelling over a certain distance is measured. A detector based on this principle is called a time-of-flight (TOF) detector which has attracted interests constantly during the last 15 years. For high energy heavy particle energy detection, TOF detector is an appropriated choice and such a system, developed recently, is described in this paper. 8 refs., 3 figs.

A time of flight detector for high energy heavy particles

Energy Technology Data Exchange (ETDEWEB)

Fang, Z; O` Connor, D J [Newcastle Univ., NSW (Australia). Dept. of Physics

1994-12-31

As a commonly used method to measure the energy of a particle with known mass, the flight time of the particle travelling over a certain distance is measured. A detector based on this principle is called a time-of-flight (TOF) detector which has attracted interests constantly during the last 15 years. For high energy heavy particle energy detection, TOF detector is an appropriated choice and such a system, developed recently, is described in this paper. 8 refs., 3 figs.

Experimental investigation of acoustic streaming in a cylindrical wave guide up to high streaming Reynolds numbers.

Science.gov (United States)

Reyt, Ida; Bailliet, Hélène; Valière, Jean-Christophe

2014-01-01

Measurements of streaming velocity are performed by means of Laser Doppler Velocimetry and Particle Image Velociimetry in an experimental apparatus consisting of a cylindrical waveguide having one loudspeaker at each end for high intensity sound levels. The case of high nonlinear Reynolds number ReNL is particularly investigated. The variation of axial streaming velocity with respect to the axial and to the transverse coordinates are compared to available Rayleigh streaming theory. As expected, the measured streaming velocity agrees well with the Rayleigh streaming theory for small ReNL but deviates significantly from such predictions for high ReNL. When the nonlinear Reynolds number is increased, the outer centerline axial streaming velocity gets distorted towards the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes. This kind of behavior is followed by outer streaming cells only and measurements in the near wall region show that inner streaming vortices are less affected by this substantial evolution of fast streaming pattern. Measurements of the transient evolution of streaming velocity provide an additional insight into the evolution of fast streaming.

Dynamic chaos phenomenon and coherent radiation accompanying high energy particle motion through crystals

International Nuclear Information System (INIS)

Akhiezer, A.I.; Truten', V.I.; Shul'ga, N.F.

1991-01-01

A crystal has a regular structure, therefore every motion in such a structure seems to be regular. However, it is not actually so and even in perfect crystals the particle motion may be either regular or chaotic. Everything depends on the number of integrals of motion determining a particle trajectory. The character of particle motion in a crystal, i.e. its regularity or chaoticity, affects many physical processes accompanying the particle's motion. In this paper we shall consider the effect of dynamic chaos on the coherent radiation of fast particles in a crystal. We also consider the validity conditions of coherent radiation theory results, the role of the second and higher Born approximations in the radiation theory of fast particles in crystals, the continuous string approximation in this theory, the coherent radiation in the model of random strings, and the multiple scattering effect on the coherent radiation. (author)

Rare Particle Searches with the high altitude SLIM experiment

CERN Document Server

Balestra, S; Fabbri, F; Giacomelli, G; Giacomelli, R; Giorgini, M; Kumar, A; Manzoor, S; McDonald, J; Margiotta, A; Medinaceli, E; Nogales, J; Patrizii, L; Popa, V; Quereshi, I; Saavedra, O; Sher, G; Shahzad, M; Spurio, M; Ticona, R; Togo, V; Velarde, A; Zanini, A

2005-01-01

The search for rare particles in the cosmic radiation remains one of the main aims of non-accelerator particle astrophysics. Experiments at high altitude allow lower mass thresholds with respect to detectors at sea level or underground. The SLIM experiment is a large array of nuclear track detectors located at the Chacaltaya High Altitude Laboratory (5290 m a.s.l.). The preliminary results from the analysis of a part of the first 236 sq.m exposed for more than 3.6 y are here reported. The detector is sensitive to Intermediate Mass Magnetic Monopoles and to SQM nuggets and Q-balls, which are possible Dark Matter candidates.

Failure mechanisms in high temperature gas cooled reactor fuel particles

International Nuclear Information System (INIS)

Soo, P.; Uneberg, G.; Sabatini, R.L.; Schweitzer, D.G.

1979-01-01

BISO coated UO 2 and ThO 2 particles were heated to high temperatures to determine failure mechanisms during hypothetical loss of coolant scenarios. Rapid failure begins when the oxides are reduced to liquid carbides. Several failure mechanisms are applicable, ranging from hole and crack formation in the coatings to catastrophic particle disintegration

Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

International Nuclear Information System (INIS)

Lee, E. Y.; Kim, J. H.; Jeong, S. I.; Lee, S. H.; Eum, G. W.

2015-01-01

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating

Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

Energy Technology Data Exchange (ETDEWEB)

Lee, E. Y.; Kim, J. H.; Jeong, S. I. [Andong National University, Andong (Korea, Republic of); Lee, S. H.; Eum, G. W. [Corporate R and D Institute Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

2015-04-15

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating.

Nanoparticle production by UV irradiation of combustion generated soot particles

International Nuclear Information System (INIS)

Stipe, Christopher B.; Choi, Jong Hyun; Lucas, Donald; Koshland, Catherine P.; Sawyer, Robert F.

2004-01-01

Laser ablation of surfaces normally produce high temperature plasmas that are difficult to control. By irradiating small particles in the gas phase, we can better control the size and concentration of the resulting particles when different materials are photofragmented. Here, we irradiate soot with 193 nm light from an ArF excimer laser. Irradiating the original agglomerated particles at fluences ranging from 0.07 to 0.26 J/cm 2 with repetition rates of 20 and 100 Hz produces a large number of small, unagglomerated particles, and a smaller number of spherical agglomerated particles. Mean particle diameters from 20 to 50 nm are produced from soot originally having a mean electric mobility diameter of 265nm. We use a non-dimensional parameter, called the photon/atom ratio (PAR), to aid in understanding the photofragmentation process. This parameter is the ratio of the number of photons striking the soot particles to the number of the carbon atoms contained in the soot particles, and is a better metric than the laser fluence for analyzing laser-particle interactions. These results suggest that UV photofragmentation can be effective in controlling particle size and morphology, and can be a useful diagnostic for studying elements of the laser ablation process

Total and size-resolved particle number and black carbon concentrations in urban areas near Schiphol airport (the Netherlands)

NARCIS (Netherlands)

Keuken, M.P.; Moerman, M.; Zandveld, P.; Henzing, J.S.; Hoek, G.

2015-01-01

The presence of black carbon, and size-resolved and total particle number concentrations (PNC) were investigated in the vicinity of Schiphol airport in the Netherlands, the fourth busiest airport in Europe. Continuous measurements were conducted between March and May 2014at Adamse Bos, located 7km

Azimuthal asymmetry of slow particles in high energy nuclear interaction

International Nuclear Information System (INIS)

Sarkar, Subir; Goswami, T.D.

2002-01-01

An asymmetry in the angular distribution of slow particles in the azimuthal plane has been observed during high energy nuclear disintegration of photo emulsion nuclei exposed to 1.8 GeV/c k - and 20 GeV/c protons. The mechanism of disintegration is not in accordance with the cascade-evaporation model, which is based on isotropic emission of slow particles. Deviation from isotropy indicates that some of the slow particles might be emitted well before the thermal equilibrium is reached in the disintegrating system. (author)

Systematic Analysis of the Non-Extensive Statistical Approach in High Energy Particle Collisions—Experiment vs. Theory †

Directory of Open Access Journals (Sweden)

Gábor Bíró

2017-02-01

Full Text Available The analysis of high-energy particle collisions is an excellent testbed for the non-extensive statistical approach. In these reactions we are far from the thermodynamical limit. In small colliding systems, such as electron-positron or nuclear collisions, the number of particles is several orders of magnitude smaller than the Avogadro number; therefore, finite-size and fluctuation effects strongly influence the final-state one-particle energy distributions. Due to the simple characterization, the description of the identified hadron spectra with the Boltzmann–Gibbs thermodynamical approach is insufficient. These spectra can be described very well with Tsallis–Pareto distributions instead, derived from non-extensive thermodynamics. Using the q-entropy formula, we interpret the microscopic physics in terms of the Tsallis q and T parameters. In this paper we give a view on these parameters, analyzing identified hadron spectra from recent years in a wide center-of-mass energy range. We demonstrate that the fitted Tsallis-parameters show dependency on the center-of-mass energy and particle species (mass. Our findings are described well by a QCD (Quantum Chromodynamics inspired parton evolution ansatz. Based on this comprehensive study, apart from the evolution, both mesonic and baryonic components found to be non-extensive ( q > 1 , besides the mass ordered hierarchy observed in the parameter T. We also study and compare in details the theory-obtained parameters for the case of PYTHIA8 Monte Carlo Generator, perturbative QCD and quark coalescence models.

Development of a High Irradiance LED Configuration for Small Field of View Motion Estimation of Fertilizer Particles

Directory of Open Access Journals (Sweden)

Simon Cool

2015-11-01

Full Text Available Better characterization of the fertilizer spreading process, especially the fertilizer pattern distribution on the ground, requires an accurate measurement of individual particle properties and dynamics. Both 2D and 3D high speed imaging techniques have been developed for this purpose. To maximize the accuracy of the predictions, a specific illumination level is required. This paper describes the development of a high irradiance LED system for high speed motion estimation of fertilizer particles. A spectral sensitivity factor was used to select the optimal LED in relation to the used camera from a range of commercially available high power LEDs. A multiple objective genetic algorithm was used to find the optimal configuration of LEDs resulting in the most homogeneous irradiance in the target area. Simulations were carried out for different lenses and number of LEDs. The chosen configuration resulted in an average irradiance level of 452 W/m2 with coefficient of variation less than 2%. The algorithm proved superior and more flexible to other approaches reported in the literature and can be used for various other applications.

Scintillating plastic optical fiber radiation detectors in high energy particle physics

International Nuclear Information System (INIS)

Bross, A.D.

1991-01-01

We describe the application of scintillating optical fiber in instrumentation for high energy particle physics. The basic physics of the scintillation process in polymers is discussed first and then we outline the fundamentals of scintillating fiber technology. Fiber performance, optimization, and characterization measurements are given. Detector applications in the areas of particle tracking and particle energy determination are then described. 13 refs., 12 figs

Seasonal variation of atmospheric particle number concentrations, new particle formation and atmospheric oxidation capacity at the high Arctic site Villum Research Station, Station Nord

DEFF Research Database (Denmark)

Nguyen, Quynh T.; Glasius, Marianne; Sørensen, Lise L.

2016-01-01

mode was observed during the darker months from October until mid-May, which became considerably more pronounced during the prominent Arctic haze months from March to mid-May. In contrast, nucleation- and Aitken-mode particles were predominantly observed during the summer months. Analysis of wind...

Poisson solvers for self-consistent multi-particle simulations

International Nuclear Information System (INIS)

Qiang, J; Paret, S

2014-01-01

Self-consistent multi-particle simulation plays an important role in studying beam-beam effects and space charge effects in high-intensity beams. The Poisson equation has to be solved at each time-step based on the particle density distribution in the multi-particle simulation. In this paper, we review a number of numerical methods that can be used to solve the Poisson equation efficiently. The computational complexity of those numerical methods will be O(N log(N)) or O(N) instead of O(N2), where N is the total number of grid points used to solve the Poisson equation

Some questions on the research in particle physics

International Nuclear Information System (INIS)

Kiss, D.

1978-01-01

Some new developments in elementary particle physics and interaction processes are reviewed. Recent advances in the field of particle physics including the observation of an anomalous behaviour of interaction cross section at high energy levels, the deep inelastic scattering of electrons from protons, the existence of neutral currents and the relative frequency of events with high transverse pulses are pointed out. A special development is the discovery and identification of a number of new particles and processes. New advances in understanding of the structure of subelementary particles, and the combination of electromagnetic and weak interactions are described. After a discussion of the technical and instrumental requirements and possibilities in the field of elementary particle research, the role and achievements of Hungarian scientists in high-energy facilities of the Soviet Union are emphasized. (P.J.)

High-speed scattering of charged and uncharged particles in general relativity

International Nuclear Information System (INIS)

Westphal, K.

1985-01-01

After a brief consideration of the high-speed scattering of two point charges high-speed scattering is thoroughly discussed for a charged particle by a fixed mass and of two uncharged particles of comparable masses. Perturbation technique is used over Minkowski spacetime in the de Donder gauge and the field equations and the resulting equations of motion (which take the reaction of the particles' quasistatic self-field into account) are solved by iteration. The obtained energy-momentum conservation laws allow the computation of second-order corrections for the scattering angle and the cross section. The asymptotic structure of the far-field indicates synchrotron radiation (electromagnetic and gravitational, respectively) which causes an energy loss whose reaction on the motion is briefly considered in the low-velocity limit including bound motion. (For neutral particles this is a third-order effect.) (author)

Dynamic forces on agglomerated particles caused by high-intensity ultrasound.

Science.gov (United States)

Knoop, Claas; Fritsching, Udo

2014-03-01

In this paper the acoustic forces on particles and agglomerates caused by high-intensity ultrasound in gaseous atmosphere are derived by means of computational fluid dynamics (CFD). Sound induced forces cause an oscillating stress scenario where the primary particles of an agglomerate are alternatingly pressed together and torn apart with the frequency of the applied wave. A comparison of the calculated acoustic forces with respect to the inter particle adhesion forces from Van-der-Waals and liquid bridge interactions reveals that the separation forces may reach the same order of magnitude for 80 μm sized SiO2-particles. Hence, with finite probability acoustically agitated gases may de-agglomerate/disperse solid agglomerate structures. This effect is confirmed by dispersion experiments in an acoustic particle levitation setup. Copyright © 2013 Elsevier B.V. All rights reserved.

Correlations between high momentum particles in proton-proton collisions at high energies

International Nuclear Information System (INIS)

Bobbink, G.J.

1981-01-01

This thesis describes an experiment performed at the CERN Intersecting Storage Rings. The experiment studies the reaction p+p→h 1 +h 2 +X at two centre-of-mass energies, √s=44.7 GeV and √s=62.3 GeV. Two of the outgoing particles (h 1 and h 2 ) are detected in opposite c.m.s. hemispheres at small polar angles with respect to the direction of two incident protons. The remaining particles produced (X) are not detected. The hadrons hsub(i) are identified mesons (π + , π - , K + , K - ) or baryons (p, Λ) with relatively large longitudinal psub(L) and small transverse momentum psub(T). The aim of the experiment is twofold. The first aim is to study whether the momentum distributions of the fast particles hsub(i) are correlated and thereby to constrain the possible interaction mechanisms responsible for the production of high psub(L), low psub(T) particles. The second aim is to establish to what extent the production of pions and kaons in inclusive proton-proton collisions (e.g. p+p→π+X, X=all other particles) resembles the production of pions and kaons in diffractive proton-proton collisions (e.g. p+p→p+π+X, in which the final-state proton has a momentum close to its maximum possible value). (Auth.)

Beyond the relativistic mean-field approximation. II. Configuration mixing of mean-field wave functions projected on angular momentum and particle number

International Nuclear Information System (INIS)

Niksic, T.; Vretenar, D.; Ring, P.

2006-01-01

The framework of relativistic self-consistent mean-field models is extended to include correlations related to the restoration of broken symmetries and to fluctuations of collective variables. The generator coordinate method is used to perform configuration mixing of angular-momentum and particle-number projected relativistic wave functions. The geometry is restricted to axially symmetric shapes, and the intrinsic wave functions are generated from the solutions of the relativistic mean-field+Lipkin-Nogami BCS equations, with a constraint on the mass quadrupole moment. The model employs a relativistic point-coupling (contact) nucleon-nucleon effective interaction in the particle-hole channel, and a density-independent δ-interaction in the pairing channel. Illustrative calculations are performed for 24 Mg, 32 S, and 36 Ar, and compared with results obtained employing the model developed in the first part of this work, i.e., without particle-number projection, as well as with the corresponding nonrelativistic models based on Skyrme and Gogny effective interactions

Evaluation and modelling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki - Part I: Modelling results within the LIPIKA project

Science.gov (United States)

Pohjola, M. A.; Pirjola, L.; Karppinen, A.; Härkönen, J.; Korhonen, H.; Hussein, T.; Ketzel, M.; Kukkonen, J.

2007-08-01

A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17-20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm-10 μm (aerodynamic diameter) by the Electrical Low Pressure Impactor (ELPI) and in the size range of 3-50 nm (mobility diameter) by Scanning Mobility Particle Sizer (SMPS), total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC), temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. For model comparison purposes, one of the cases was additionally computed using the aerosol process model UHMA, combined with the CAR-FMI model. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes). We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible on this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of condensable organic

High Temperature Falling Particle Receiver (2012 - 2016) - Final DOE Report

Energy Technology Data Exchange (ETDEWEB)

Ho, Clifford K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-04-15

The objective of this work was to advance falling particle receiver designs for concentrating solar power applications that will enable higher temperatures (>700 °C) and greater power-cycle efficiencies (≥50% thermal-to-electric). Modeling, design, and testing of components in Phases 1 and 2 led to the successful on-sun demonstration in Phase 3 of the world’s first continuously recirculating high-temperature 1 MW_t falling particle receiver that achieved >700 °C particle outlet temperatures at mass flow rates ranging from 1 – 7 kg/s.

VOLUME STUDY WITH HIGH DENSITY OF PARTICLES BASED ON CONTOUR AND CORRELATION IMAGE ANALYSIS

Directory of Open Access Journals (Sweden)

Tatyana Yu. Nikolaeva

2014-11-01

Full Text Available The subject of study is the techniques of particle statistics evaluation, in particular, processing methods of particle images obtained by coherent illumination. This paper considers the problem of recognition and statistical accounting for individual images of small scattering particles in an arbitrary section of the volume in case of high concentrations. For automatic recognition of focused particles images, a special algorithm for statistical analysis based on contouring and thresholding was used. By means of the mathematical formalism of the scalar diffraction theory, coherent images of the particles formed by the optical system with high numerical aperture were simulated. Numerical testing of the method proposed for the cases of different concentrations and distributions of particles in the volume was performed. As a result, distributions of density and mass fraction of the particles were obtained, and the efficiency of the method in case of different concentrations of particles was evaluated. At high concentrations, the effect of coherent superposition of the particles from the adjacent planes strengthens, which makes it difficult to recognize images of particles using the algorithm considered in the paper. In this case, we propose to supplement the method with calculating the cross-correlation function of particle images from adjacent segments of the volume, and evaluating the ratio between the height of the correlation peak and the height of the function pedestal in the case of different distribution characters. The method of statistical accounting of particles considered in this paper is of practical importance in the study of volume with particles of different nature, for example, in problems of biology and oceanography. Effective work in the regime of high concentrations expands the limits of applicability of these methods for practically important cases and helps to optimize determination time of the distribution character and

The motion of a cloud of solid spherical particles falling in a cellular flow field at low Stokes number

Science.gov (United States)

Marchetti, Benjamin; Bergougnoux, Laurence; Guazzelli, Elisabeth

2017-11-01

We present a jointed experimental and numerical study examining the influence of vortical structures on the settling of a cloud of solid spherical particles under the action of gravity at low Stokes numbers. The two-dimensional model experiment uses electro-convection to generate a two-dimensional array of controlled vortices which mimics a simplified vortical flow. Particle image-velocimetry and tracking are used to examine the motion of the cloud within this vortical flow. The cloud motion is compared to the predictions of a two-way-coupling numerical simulation.

High Spatial Resolution of Atmospheric Particle Mixing State and Its Links to Particle Evolution in a Metropolitan Area

Science.gov (United States)

Ye, Q.; Gu, P.; Li, H.; Robinson, E. S.; Apte, J.; Sullivan, R. C.; Robinson, A. L.; Presto, A. A.; Donahue, N.

2017-12-01

Traditional air quality studies in urban areas have mostly relied on very few monitoring locations either at urban background sites or at roadside sites.However, air pollution is highly complex and dynamic and will undergo complicated transformations. Therefore, results from one or two monitoring sites may not be sufficient to address the spatial gradients of pollutants and their evolution after atmosphere processing on a local scale. Our study, as part of the Center for Air, Climate, and Energy Solutions, performed stratified mobile sampling of atmospheric particulate matter with high spatial resolution to address intra-city variability of atmospheric particle composition and mixing state. A suite of comprehensive real-time instrumentations including a state-of-the-art aerosol mass spectrometer with single particle measurement capability are deployed on the mobile platform. Our sampling locations covered a wide variety of places with substantial differences in emissions and land use types including tunnels, inter-state highways, commercial areas, residential neighborhood, parks, as well as locations upwind and downwind of the city center. Our results show that particles from traffic emissions and restaurant cookings are two major contributors to fresh particles in the urban environment. In addition, there are large spatial variabilities of source-specific particles and we identify the relevant physicochemical processes governing transformation of particle composition, size and mixing state. We also combine our results with demographic data to study population exposure to particles of specific sources. This work will help evaluate the performance of existing modeling tools for air quality and population exposure studies.

Real-time visualization of dynamic particle contact failures

Energy Technology Data Exchange (ETDEWEB)

Parab, Niranjan D.; Hudspeth, Matthew; Claus, Ben; Guo, Zherui; Sun, Tao; Fezzaa, Kamel; Chen, Weinong W.

2017-01-01

Granular materials are widely used to resist impact and blast. Under these dynamic loadings, the constituent particles in the granular system fracture. To study the fracture mechanisms in brittle particles under dynamic compressive loading, a high speed X-ray phase contrast imaging setup was synchronized with a Kolsky bar apparatus. Controlled compressive loading was applied on two contacting particles using the Kolsky bar apparatus and fracture process was captured using the high speed X-ray imaging setup. Five different particles were investigated: soda-lime glass, polycrystalline silica (silicon dioxide), polycrystalline silicon, barium titanate glass, and yttrium stabilized zirconia. For both soda lime glass and polycrystalline silica particles, one of the particles fragmented explosively, thus breaking into many small pieces. For Silicon and barium titanate glass particles, a finite number of cracks were observed in one of the particles causing it to fracture. For yttrium stabilized zirconia particles, a single meridonial crack developed in one of the particles, breaking it into two parts.

Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

Science.gov (United States)

Collins, David J; Ma, Zhichao; Ai, Ye

2016-05-17

Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

Particle acceleration through the resonance of high magnetic field and high frequency electromagnetic wave

International Nuclear Information System (INIS)

Hong, Liu; He, X.T.; Chen, S.G.; Zhang, W.Y.; He, X.T.; Hong, Liu

2004-01-01

We propose a new particle acceleration mechanism. Electrons can be accelerated to relativistic energy within a few electromagnetic wave cycles through the mechanism which is named electromagnetic and magnetic field resonance acceleration (EMRA). We find that the electron acceleration depends not only on the electromagnetic wave intensity, but also on the ratio between electron Larmor frequency and electromagnetic wave frequency. As the ratio approaches to unity, a clear resonance peak is observed, corresponding to the EMRA. Near the resonance regime, the strong magnetic fields still affect the electron acceleration dramatically. We derive an approximate analytical solution of the relativistic electron energy in adiabatic limit, which provides a full understanding of this phenomenon. In typical parameters of pulsar magnetospheres, the mechanism allows particles to increase their energies through the resonance of high magnetic field and high frequency electromagnetic wave in each electromagnetic wave period. The energy spectra of the accelerated particles exhibit the synchrotron radiation behavior. These can help to understand the remaining emission of high energy electron from radio pulsar within supernova remnant. The other potential application of our theory in fast ignition scheme of inertial confinement fusion is also discussed. (authors)

Measurement of the atmospheric aerosol particle size distribution in a highly polluted mega-city in Southeast Asia (Dhaka-Bangladesh)

Science.gov (United States)

Salam, Abdus; Mamoon, Hassan Al; Ullah, Md. Basir; Ullah, Shah M.

2012-11-01

Aerosol particle size distribution was measured with an aerodynamic particle sizer (APS) spectrometer continuously from January 21 to April 24, 2006 in Dhaka, Bangladesh. Particles number, surface and mass distributions data were stored automatically with Aerosol Instrument Manager (AIM) software on average every half an hour in a computer attached to the APS. The grand total average of number, surface and mass concentrations were 8.2 × 103 ± 7.8 × 103 particles cm-3, 13.3 × 103 ± 11.8 × 103 μm2 cm-3 and 3.04 ± 2.10 mg m-3, respectively. Fine particles with diameter smaller than 1.0 μm aerodynamic diameter (AD) dominated the number concentration, accounted for 91.7% of the total particles indicating vehicular emissions were dominating in Dhaka air either from fossil fuel burning or compressed natural gas (CNGs). The surface and mass concentrations between 0.5 and 1.0 μm AD were about 56.0% and 26.4% of the total particles, respectively. Remarkable seasonal differences were observed between winter and pre-monsoon seasons with the highest monthly average in January and the lowest in April. Aerosol particles in winter were 3.79 times higher for number, 3.15 times for surface and 2.18 times for mass distributions than during the pre-monsoon season. Weekends had lower concentrations than weekdays due to less vehicular traffic in the streets. Aerosol particles concentrations were about 15.0% (ranging from 9.4% to 17.3%) higher during traffic peak hours (6:00am-8:00pm) than off hours (8:00pm-6:00am). These are the first aerosol size distribution measurements with respect to number, surface and mass concentrations in real time at Dhaka, Bangladesh.

Characterization of biomass combustion at high temperatures based on an upgraded single particle model

International Nuclear Information System (INIS)

Li, Jun; Paul, Manosh C.; Younger, Paul L.; Watson, Ian; Hossain, Mamdud; Welch, Stephen

2015-01-01

Highlights: • High temperature rapid biomass combustion is studied based on single particle model. • Particle size changes in devolatilization and char oxidation models are addressed. • Time scales of various thermal sub-processes are compared and discussed. • Potential solutions are suggested to achieve better biomass co-firing performances. - Abstract: Biomass co-firing is becoming a promising solution to reduce CO 2 emissions, due to its renewability and carbon neutrality. Biomass normally has high moisture and volatile contents, complicating its combustion behavior, which is significantly different from that of coal. A computational fluid dynamics (CFD) combustion model of a single biomass particle is employed to study high-temperature rapid biomass combustion. The two-competing-rate model and kinetics/diffusion model are used to model biomass devolatilization reaction and char burnout process, respectively, in which the apparent kinetics used for those two models were from high temperatures and high heating rates tests. The particle size changes during the devolatilization and char burnout are also considered. The mass loss properties and temperature profile during the biomass devolatilization and combustion processes are predicted; and the timescales of particle heating up, drying, devolatilization, and char burnout are compared and discussed. Finally, the results shed light on the effects of particle size on the combustion behavior of biomass particle

NACRE II: an update of the NACRE compilation of charged-particle-induced thermonuclear reaction rates for nuclei with mass number A<16

International Nuclear Information System (INIS)

Xu, Y.; Takahashi, K.; Goriely, S.; Arnould, M.; Ohta, M.; Utsunomiya, H.

2013-01-01

An update of the NACRE compilation [3] is presented. This new compilation, referred to as NACRE II, reports thermonuclear reaction rates for 34 charged-particle induced, two-body exoergic reactions on nuclides with mass number A 6 ≲T⩽10 10 K range. Along with the ‘adopted’ rates, their low and high limits are provided. The new rates are available in electronic form as part of the Brussels Library (BRUSLIB) of nuclear data. The NACRE II rates also supersede the previous NACRE rates in the Nuclear Network Generator (NETGEN) for astrophysics. [ (http://www.astro.ulb.ac.be/databases.html)

Charged particle beam scanning using deformed high gradient insulator

Science.gov (United States)

Chen, Yu -Jiuan

2015-10-06

Devices and methods are provided to allow rapid deflection of a charged particle beam. The disclosed devices can, for example, be used as part of a hadron therapy system to allow scanning of a target area within a patient's body. The disclosed charged particle beam deflectors include a dielectric wall accelerator (DWA) with a hollow center and a dielectric wall that is substantially parallel to a z-axis that runs through the hollow center. The dielectric wall includes one or more deformed high gradient insulators (HGIs) that are configured to produce an electric field with an component in a direction perpendicular to the z-axis. A control component is also provided to establish the electric field component in the direction perpendicular to the z-axis and to control deflection of a charged particle beam in the direction perpendicular to the z-axis as the charged particle beam travels through the hollow center of the DWA.

Extending the Modelling Framework for Gas-Particle Systems

DEFF Research Database (Denmark)

Rosendahl, Lasse Aistrup

, with very good results. Single particle combustion has been tested using a number of different particle combustion models applied to coal and straw particles. Comparing the results of these calculations to measurements on straw burnout, the results indicate that for straw, existing heterogeneous combustion...... models perform well, and may be used in high temperature ranges. Finally, the particle tracking and combustion model is applied to an existing coal and straw co- fuelled burner. The results indicate that again, the straw follows very different trajectories than the coal particles, and also that burnout...

Plasma based charged-particle accelerators

International Nuclear Information System (INIS)

Bingham, R; Mendonca, J T; Shukla, P K

2004-01-01

Studies of charged-particle acceleration processes remain one of the most important areas of research in laboratory, space and astrophysical plasmas. In this paper, we present the underlying physics and the present status of high gradient and high energy plasma accelerators. We will focus on the acceleration of charged particles to relativistic energies by plasma waves that are created by intense laser and particle beams. The generation of relativistic plasma waves by intense lasers or electron beams in plasmas is important in the quest for producing ultra-high acceleration gradients for accelerators. With the development of compact short pulse high brightness lasers and electron positron beams, new areas of studies for laser/particle beam-matter interactions is opening up. A number of methods are being pursued vigorously to achieve ultra-high acceleration gradients. These include the plasma beat wave accelerator mechanism, which uses conventional long pulse (∼100 ps) modest intensity lasers (I ∼ 10 14 -10 16 W cm -2 ), the laser wakefield accelerator (LWFA), which uses the new breed of compact high brightness lasers ( 10 18 W cm -2 , the self-modulated LWFA concept, which combines elements of stimulated Raman forward scattering, and electron acceleration by nonlinear plasma waves excited by relativistic electron and positron bunches. In the ultra-high intensity regime, laser/particle beam-plasma interactions are highly nonlinear and relativistic, leading to new phenomena such as the plasma wakefield excitation for particle acceleration, relativistic self-focusing and guiding of laser beams, high-harmonic generation, acceleration of electrons, positrons, protons and photons. Fields greater than 1 GV cm -1 have been generated with particles being accelerated to 200 MeV over a distance of millimetre. Plasma wakefields driven by positron beams at the Stanford Linear Accelerator Center facility have accelerated the tail of the positron beam. In the near future

PREFACE: High Energy Particle Physics Workshop (HEPPW2015)

Science.gov (United States)

Cornell, Alan S.; Mellado, B.

2015-10-01

The motivation for this workshop began with the discovery of the Higgs boson three years ago, and the realisation that many problems remain in particle physics, such as why there is more matter than anti-matter, better determining the still poorly measured parameters of the strong force, explaining possible sources for dark matter, naturalness etc. While the newly discovered Higgs boson seems to be compatible with the Standard Model, current experimental accuracy is far from providing a definitive statement with regards to the nature of this new particle. There is a lot of room for physics beyond the Standard Model to emerge in the exploration of the Higgs boson. Recent measurements in high-energy heavy ion collisions at the LHC have shed light on the complex dynamics that govern high-density quark-gluon interactions. An array of results from the ALICE collaboration have been highlighted in a recent issue of CERN courier. The physics program of high-energy heavy ion collisions promises to further unveil the intricacies of high-density quark-gluon plasma physics. The great topicality of high energy physics research has also seen a rapid increase in the number of researchers in South Africa pursuing such studies, both experimentally through the ATLAS and ALICE colliders at CERN, and theoretically. Young researchers and graduate students largely populate these research groups, with little experience in presenting their work, and few support structures (to their knowledge) to share experiences with. Whilst many schools and workshops have sought to educate these students on the theories and tools they will need to pursue their research, few have provided them with a platform to present their work. As such, this workshop discussed the various projects being pursued by graduate students and young researchers in South Africa, enabling them to develop networks for future collaboration and discussion. The workshop took place at the iThemba Laboratories - North facility, in