scholarly journals Neutrino Transport with the Monte Carlo Method. II. Quantum Kinetic Equations

2021 ◽  
Vol 257 (2) ◽  
pp. 55
Author(s):  
Chinami Kato ◽  
Hiroki Nagakura ◽  
Taiki Morinaga
Keyword(s):  
Monte Carlo ◽  
Technical Problem ◽  
Sudden Change ◽  
Kinetic Equations ◽  
Mean Free Path ◽  
High Energy ◽  
The Monte Carlo Method ◽  
Numerical Treatments ◽  
Quantum Feature ◽  
Statistical Noise

Abstract Neutrinos have a unique quantum feature as flavor conversions. Recent studies suggested that collective neutrino oscillations play important roles in high-energy astrophysical phenomena. The quantum kinetic equation (QKE) is capable of describing the neutrino flavor conversion, transport, and matter collision self-consistently. However, we have experienced many technical difficulties in their numerical implementation. In this paper, we present a new QKE solver based on a Monte Carlo (MC) approach. This is an upgraded version of our classical MC neutrino transport solver; in essence, a flavor degree of freedom including mixing state is added into each MC particle. This extension requires updating numerical treatments of collision terms, in particular for scattering processes. We deal with the technical problem by generating a new MC particle at each scattering event. To reduce statistical noise inherent in MC methods, we develop the effective mean free path method. This suppresses a sudden change of flavor state due to collisions without increasing the number of MC particles. We present a suite of code tests to validate these new modules with comparison to the results reported in previous studies. Our QKE-MC solver is developed with fundamentally different philosophy and design from other deterministic and mesh methods, suggesting that it will be complementary to others and potentially provide new insights into physical processes of neutrino dynamics.

Monte Carlo Modelling of Secondary Electron Yield from Rough Surfaces

1990 ◽  
Vol 48 (1) ◽  
pp. 422-423
Author(s):  
John C. Russ
Keyword(s):  
Monte Carlo ◽  
Energy Loss ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Analytical Calculation ◽  
Mean Free Path ◽  
Single Scattering ◽  
High Energy ◽  
Secondary Electron Yield ◽  
Electron Yield

Monte-Carlo programs are well recognized for their ability to model electron beam interactions with samples, and to incorporate boundary conditions such as compositional or surface variations which are difficult to handle analytically. This success has been especially powerful for modelling X-ray emission and the backscattering of high energy electrons. Secondary electron emission has proven to be somewhat more difficult, since the diffusion of the generated secondaries to the surface is strongly geometry dependent, and requires analytical calculations as well as material parameters. Modelling of secondary electron yield within a Monte-Carlo framework has been done using multiple scattering programs, but is not readily adapted to the moderately complex geometries associated with samples such as microelectronic devices, etc.This paper reports results using a different approach in which simplifying assumptions are made to permit direct and easy estimation of the secondary electron signal from samples of arbitrary complexity. The single-scattering program which performs the basic Monte-Carlo simulation (and is also used for backscattered electron and EBIC simulation) allows multiple regions to be defined within the sample, each with boundaries formed by a polygon of any number of sides. Each region may be given any elemental composition in atomic percent. In addition to the regions comprising the primary structure of the sample, a series of thin regions are defined along the surface(s) in which the total energy loss of the primary electrons is summed. This energy loss is assumed to be proportional to the generated secondary electron signal which would be emitted from the sample. The only adjustable variable is the thickness of the region, which plays the same role as the mean free path of the secondary electrons in an analytical calculation. This is treated as an empirical factor, similar in many respects to the λ and ε parameters in the Joy model.

Simulation of 12 C+ 12 C elastic scattering at high energy by using the Monte Carlo method

2012 ◽  
Vol 36 (3) ◽  
pp. 205-209 ◽  
Author(s):  
Chen-Lei Guo ◽  
Gao-Long Zhang ◽  
I. Tanihata ◽  
Xiao-Yun Le
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Elastic Scattering ◽  
High Energy ◽  
The Monte Carlo Method

Application of the monte carlo method to high energy electron scattering (0.3-1.5 MeV)

1978 ◽  
Vol 36 (1) ◽  
pp. 202-203
Author(s):  
G. Soum ◽  
F. Arnal ◽  
J.L. Balladore ◽  
B. Jouffrey ◽  
P. Verdier
Keyword(s):  
Monte Carlo ◽  
Angular Distribution ◽  
Monte Carlo Method ◽  
Transmission Coefficient ◽  
Electron Scattering ◽  
High Energy ◽  
Angular Aperture ◽  
Method Of Calculation ◽  
Total Transmission ◽  
The Monte Carlo Method

Techniques for using the Monte-Carlo method for studying electron scattering in solids have been developed by several authors (1). The method is used to determine the angular distribution of electrons emerging from amorphous or polycrystalline specimens ; the total transmission and backscattering coefficients can also be obtained.- Method of calculation -Let Iθ be the intensity scattered in the direction making an angle θ with the incident electrons ; thus Iθ represents the number of electrons scattered in this direction within a solid angle Δw = πα2, where α is the semi-angle of the collector as seen from the specimen. For a specimen of thickness x, the angular distribution function may be written:I∘ denotes the intensity of the incident monoenergetic electron beam, Tα the transmission coefficient along the direction of incidence for a semi-angular aperture α and TθN the normalized transmission coefficient in the direction θ

scholarly journals The Ecology of Magnetic Rotators

1996 ◽  
Vol 165 ◽  
pp. 81-92
Author(s):  
V.M. Lipunov
Keyword(s):  
Monte Carlo ◽  
Compact Star ◽  
High Energy ◽  
Compact Stars ◽  
High Energy Radiation ◽  
Theory Of Evolution ◽  
Current State ◽  
Evolutionary Scenario ◽  
The Monte Carlo Method ◽  
Radiation Sources

A review is given concerning the current state of the theory of evolution of magnetic compact stars. The intrinsic evolution of the magnetized compact star is shown, both theoretically and numerically, to be the decisive factor in explaining observable properties, and in predicting yet unknown properties of high-energy radiation sources in our and other galaxies. The main results are given of recent evolutionary scenario simulations (Scenario Machine) by the Monte-Carlo method.

The Monte Carlo Method Used in Self-Switching Device

2013 ◽  
Vol 760-762 ◽  
pp. 607-611
Author(s):  
Yang Heng ◽  
Kun Yuan Xu
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Ballistic Transport ◽  
Mean Free Path ◽  
Electron Velocity ◽  
Nanometer Scale ◽  
Switching Device ◽  
The Monte Carlo Method ◽  
The Mean ◽  
Device Size

Optoelectronic Devices have obtained great interests for many decades. With the development of technology and in-depth research, the devices are scaled down rapidly, reaching sub-millimeter or even nanometer scale, and resulting in various new features. In recent years, a so called Self-Switching Device (SSD) which has diode-like I-V characteristics has attracted more and more attentions. Using Monte Carlo method, we have studied the electron transport in the self-switching device. Simulation results show that when the device size is smaller than the mean free path of electrons, the electron velocity is very different from that of larger device. The electron velocity and the energy become faster and higher, respectively. The reason of this phenomenon is explained by ballistic transport of electrons in the small size device. Since ballistic transport plays an important role in determining the behavior of electrons in small size device, it is need to be included in nanometer scale device modeling.

Neutron dose evaluation of Elekta Linac at two energies (10 & 18 MV) by MCNP code and comparison with experimental measurements

2014 ◽  
Vol 6 (1) ◽  
pp. 1006-1015
Author(s):  
Negin Shagholi ◽  
Hassan Ali ◽  
Mahdi Sadeghi ◽  
Arjang Shahvar ◽  
Hoda Darestani ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Measurement Data ◽  
Calculated Data ◽  
High Energy ◽  
Neutron Dose ◽  
Dose Assessment ◽  
Photon Flux ◽  
Dose Equivalent ◽  
Monte Carlo Techniques ◽  
Neutron Dose Equivalent

Medical linear accelerators, besides the clinically high energy electron and photon beams, produce other secondary particles such as neutrons which escalate the delivered dose. In this study the neutron dose at 10 and 18MV Elekta linac was obtained by using TLD600 and TLD700 as well as Monte Carlo simulation. For neutron dose assessment in 2020 cm2 field, TLDs were calibrated at first. Gamma calibration was performed with 10 and 18 MV linac and neutron calibration was done with 241Am-Be neutron source. For simulation, MCNPX code was used then calculated neutron dose equivalent was compared with measurement data. Neutron dose equivalent at 18 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 3.3, 4, 5 and 6 cm. Neutron dose at depths of less than 3.3cm was zero and maximized at the depth of 4 cm (44.39 mSvGy-1), whereas calculation resulted  in the maximum of 2.32 mSvGy-1 at the same depth. Neutron dose at 10 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 2.5, 3.3, 4 and 5 cm. No photoneutron dose was observed at depths of less than 3.3cm and the maximum was at 4cm equal to 5.44mSvGy-1, however, the calculated data showed the maximum of 0.077mSvGy-1 at the same depth. The comparison between measured photo neutron dose and calculated data along the beam axis in different depths, shows that the measurement data were much more than the calculated data, so it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry in linac central axis due to high photon flux, whereas MCNPX Monte Carlo techniques still remain a valuable tool for photonuclear dose studies.

Sign in / Sign up

Export Citation Format

Share Document