Application of Cloud Chambers for Heuristic Comprehension of Radiation

2013 ◽  
Author(s):  
Yuzuru Tawara ◽  
Shinji Hara ◽  
Kazuo Koga ◽  
Kenji Tsuji
Keyword(s):  
Radiation Source ◽  
Background Radiation ◽  
Deep Understanding ◽  
Radiation Detectors ◽  
High Energy ◽  
Cloud Chamber ◽  
Shielding Effect ◽  
X Rays ◽  
Natural Background ◽  
Background Radiations

In the nuclear-related public relation center, a variety of displays such as models of nuclear facility, panel presentations to explain radiation properties, radiation detectors are used for the visitors to help the understanding of nuclear power and radiation. The PR center demonstrates various aspect of the radiation such as the presence of natural background radiations around us in the daily life, shielding effect for the different kind of radiations. Cloud Chambers are often used to demonstrate the presence of natural background radiation, showing tracks caused by the ionizing effect. The shielding effect of radiation is demonstrated by inserting a shield material between a radiation source and the detector such as GM counter. It is usually illustrated in the panel that the penetration properties are different for kinds of radiation but actual demonstration is seldom used. Then a question arises that people cannot properly understand overall characteristics of the radiation in the above described demonstrations in the PR center. So we have been trying to improve a utilization method of a cloud chamber to help the deep understanding of properties of radiation. The improved cloud chamber has the area size of 225 mm × 225 mm with 100 mm in depth and has the structure for the function of insertion and extraction of both a radiation source and a shield material, independently. When a radiation source such as Cs-137 or Fe-55 is inserted in the chamber, it is clearly shown that high energy electron created by gamma-ray or X-ray emitted from such radioisotope can make track with different length. It is also shown using lantern core with thorium-series isotopes that thick track can be made by alpha particle. Fe-55 radioisotope generates 5.9 keV X-rays, which produces about 1mm track in the chamber through photoelectron. When a shield material of lead with a thickness of 1mm was inserted in front of the source, the fading out of the tracks is clearly observed. Thus shielding effect can be easily confirmed by eye using cloud chamber. The demonstrations of shielding effect described above can help more clear and essential understanding of the radiations. This was shown by the questionnaire survey done before and after the demonstrations for the 32 participants. For further improvements of the cloud chamber, we are planning to enlarge the size of cloud chamber and to get much clearer track image by improving track illumination method. Finally we will re-consider more effective explanation to give correct understanding of the radiation and will verify the effectiveness of utilization method of new cloud chamber.

scholarly journals MCNPX simulations of the silicon carbide semiconductor detector response to fast neutrons from D–T nuclear reaction

2016 ◽  
Vol 44 ◽  
pp. 1660226 ◽  
Author(s):  
Katarína Sedlačková ◽  
Andrea Šagátová ◽  
Bohumír Zat'ko ◽  
Vladimír Nečas ◽  
Michael Solar ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Monte Carlo ◽  
Nuclear Reaction ◽  
Charged Particles ◽  
Radiation Detectors ◽  
High Energy ◽  
Nuclear Radiation ◽  
Fast Neutrons ◽  
Detector Response ◽  
X Rays

Silicon Carbide (SiC) has been long recognized as a suitable semiconductor material for use in nuclear radiation detectors of high-energy charged particles, gamma rays, X-rays and neutrons. The nuclear interactions occurring in the semiconductor are complex and can be quantified using a Monte Carlo-based computer code. In this work, the MCNPX (Monte Carlo N-Particle eXtended) code was employed to support detector design and analysis. MCNPX is widely used to simulate interaction of radiation with matter and supports the transport of 34 particle types including heavy ions in broad energy ranges. The code also supports complex 3D geometries and both nuclear data tables and physics models. In our model, monoenergetic neutrons from D–T nuclear reaction were assumed as a source of fast neutrons. Their energy varied between 16 and 18.2 MeV, according to the accelerating voltage of the deuterons participating in D–T reaction. First, the simulations were used to calculate the optimum thickness of the reactive film composed of High Density PolyEthylene (HDPE), which converts neutral particles to charged particles and thusly enhancing detection efficiency. The dependency of the optimal thickness of the HDPE layer on the energy of the incident neutrons has been shown for the inspected energy range. Further, from the energy deposited by secondary charged particles and recoiled ions, the detector response was modeled and the effect of the conversion layer on detector response was demonstrated. The results from the simulations were compared with experimental data obtained for a detector covered by a 600 and 1300 [Formula: see text]m thick conversion layer. Some limitations of the simulations using MCNPX code are also discussed.

scholarly journals An Investigation of Natural Background Radiation and Health Risk Assessment in Kohgiluyeh and Boyer-Ahmad Province, Iran

2020 ◽  
Vol In Press (In Press) ◽  
Author(s):  
Mahmoud Bagheri ◽  
Mohammad Reza Fouladi ◽  
Razzagh Abedi-Firouzjah
Keyword(s):  
Hot Springs ◽  
Background Radiation ◽  
Outdoor Exposure ◽  
Natural Background ◽  
High Exposure ◽  
Indoor Exposure ◽  
Background Radiations ◽  
Dose Rates ◽  
Average Value ◽  
Risk Sources

Background: The natural radiation, which comes from the environment, is one of the most important cancer risk sources. Objectives: This study aimed to measure the natural background radiations (BRs) and estimate the annual effective dose (AED), as well as the health risks in Kohgiluyeh and Boyer-Ahmad Province, Iran. Methods: background radiations for both indoors and outdoors were measured using a Geiger-Muller detector (X5C plus) in eight cities. Five points were chosen in each city for the BR measurements, and in each point, five stations were randomly selected and measured. Results: The average outdoor and indoor dose rates were obtained 136.9 ± 12.5 and 149.3 ± 19.8 nSv.h-1, respectively. The mean AEDs for adults, children, and infants were 0.17, 0.19, and 0.22 mSv.y-1 resulting from the outdoor exposure, in that order, and these values for indoor irradiation were 0.73, 0.84, and 0.94 mSv.y-1. The percentage of excess lifetime cancer risks due to indoor exposure was 4.6% for whole populations and 3% for adults. The heritable effects risk for these groups were 0.17 and 0.073%, respectively. Conclusions: The findings of the present study indicated that the average value of BR dose rates was higher than the global value. The reason can be due to the high exposure levels of hot springs, igneous rock, and high altitudes in Kohgiluyeh and Boyer-Ahmad Province.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

1985 ◽  
Vol 43 ◽  
pp. 154-157
Author(s):  
A.J. Tousimis
Keyword(s):  
Ion Beam ◽  
Depth Resolution ◽  
Sample Surface ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Electrons And Ions ◽  
Spatial Depth ◽  
Minimum Surface Area ◽  
Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

“Cartography” in 7-Dimensions at CHESS: Mapping of Structure in Real Space, Reciprocal Space, and Time Using High-Energy X-rays

2020 ◽  
Vol 33 (6) ◽  
pp. 11-16
Author(s):  
K. E. Nygren, ◽  
D. C. Pagan, ◽  
J. P. C. Ruff ◽  
E. Arenholz ◽  
J. D. Brock
Keyword(s):  
High Energy ◽  
Real Space ◽  
Reciprocal Space ◽  
X Rays ◽  
Space And Time

scholarly journals The interstellar medium in young supernova remnants: key to the production of cosmic X-rays and $\gamma $-rays

2021 ◽  
Vol 366 (6) ◽  
Author(s):  
Hidetoshi Sano ◽  
Yasuo Fukui
Keyword(s):  
Interstellar Medium ◽  
Supernova Remnants ◽  
Cosmic Ray ◽  
High Energy ◽  
X Rays ◽  
Interstellar Gas ◽  
High Energy Radiation ◽  
Dense Cores ◽  
The Relationship ◽  
Turbulent Velocity Field

AbstractWe review recent progress in elucidating the relationship between high-energy radiation and the interstellar medium (ISM) in young supernova remnants (SNRs) with ages of ∼2000 yr, focusing in particular on RX J1713.7−3946 and RCW 86. Both SNRs emit strong nonthermal X-rays and TeV $\gamma $ γ -rays, and they contain clumpy distributions of interstellar gas that includes both atomic and molecular hydrogen. We find that shock–cloud interactions provide a viable explanation for the spatial correlation between the X-rays and ISM. In these interactions, the supernova shocks hit the typically pc-scale dense cores, generating a highly turbulent velocity field that amplifies the magnetic field up to 0.1–1 mG. This amplification leads to enhanced nonthermal synchrotron emission around the clumps, whereas the cosmic-ray electrons do not penetrate the clumps. Accordingly, the nonthermal X-rays exhibit a spatial distribution similar to that of the ISM on the pc scale, while they are anticorrelated at sub-pc scales. These results predict that hadronic $\gamma $ γ -rays can be emitted from the dense cores, resulting in a spatial correspondence between the $\gamma $ γ -rays and the ISM. The current pc-scale resolution of $\gamma $ γ -ray observations is too low to resolve this correspondence. Future $\gamma $ γ -ray observations with the Cherenkov Telescope Array will be able to resolve the sub-pc-scale $\gamma $ γ -ray distribution and provide clues to the origin of these cosmic $\gamma $ γ -rays.

scholarly journals Introducing the HD+B model for pulsar wind nebulae: a hybrid hydrodynamics/radiative approach

2020 ◽  
Vol 494 (3) ◽  
pp. 4357-4370
Author(s):  
B Olmi ◽  
D F Torres
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Theoretical Modelling ◽  
X Rays ◽  
Pulsar Wind Nebulae ◽  
New Approach ◽  
Energy Gamma ◽  
Radiative Model ◽  
Pulsar Wind

ABSTRACT Identification and characterization of a rapidly increasing number of pulsar wind nebulae is, and will continue to be, a challenge of high-energy gamma-ray astrophysics. Given that such systems constitute -by far- the most numerous expected population in the TeV regime, such characterization is important not only to learn about the sources per se from an individual and population perspective, but also to be able to connect them with observations at other frequencies, especially in radio and X-rays. Also, we need to remove the emission from nebulae in highly confused regions of the sky for revealing other underlying emitters. In this paper, we present a new approach for theoretical modelling of pulsar wind nebulae: a hybrid hydrodynamic-radiative model able to reproduce morphological features and spectra of the sources, with relatively limited numerical cost.

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