scholarly journals Investigation of Photon Radiation Attenuation Capability of Different Clay Materials

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6702
Author(s):  
Mohamed Elsafi ◽  
Yousry Koraim ◽  
Mansour Almurayshid ◽  
Fahad I Almasoud ◽  
M. I. Sayyed ◽  
...  
Keyword(s):  
Theoretical Data ◽  
Bentonite Clay ◽  
Mass Attenuation Coefficient ◽  
High Energy ◽  
Photon Radiation ◽  
Kaolin Clay ◽  
Clay Sample ◽  
Red Clay ◽  
Radiation Attenuation ◽  
Low Energies

This work aims to experimentally report the radiation attenuation factors for four different clays (red, ball, kaolin and bentonite clays) at four selected energies (emitted from Am-241, Cs-137, and Co-60). The highest relative difference in the mass attenuation coefficient (MAC) is equal to −3.02%, but most of the other results are much smaller than this value, proving that the experimental and theoretical data greatly agree with each other. From the MAC results, the shielding abilities of the clay samples at 0.060 MeV follow the order of: bentonite > red > ball > kaolin. Thus, at low energies, the bentonite clay sample provides the most effective attenuation capability out of the tested clays. The half value layer (HVL) increases as energy increases, which suggests that, only a thin clay sample is needed to sufficiently absorb the radiation at low energies, while at higher energies a thicker sample is needed to shield the same amount of high energy radiated. Furthermore, bentonite clay has the lowest HVL, while the kaolin clay has the greatest HVL at all energies. The radiation protection efficiency (RPE) values at 0.060 MeV are equal to 97.982%, 97.137%, 94.242%, and 93.583% for bentonite clay, red clay, ball clay, and kaolin clay, respectively. This reveals that at this energy, the four clay samples can absorb almost all of the incoming photons, but the bentonite clay has the greatest attenuation capability at this energy, while kaolin clay has the lowest.

scholarly journals Ion tracks in silicon formed by much lower energy deposition than the track formation threshold

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
H. Amekura ◽  
M. Toulemonde ◽  
K. Narumi ◽  
R. Li ◽  
A. Chiba ◽  
...  
Keyword(s):  
Nuclear Energy ◽  
Energy Deposition ◽  
Ion Irradiation ◽  
High Energy ◽  
Electronic Energy ◽  
Synergy Effect ◽  
Ion Tracks ◽  
Track Formation ◽  
Low Energies ◽  
High Energy Ions

AbstractDamaged regions of cylindrical shapes called ion tracks, typically in nano-meters wide and tens micro-meters long, are formed along the ion trajectories in many insulators, when high energy ions in the electronic stopping regime are injected. In most cases, the ion tracks were assumed as consequences of dense electronic energy deposition from the high energy ions, except some cases where the synergy effect with the nuclear energy deposition plays an important role. In crystalline Si (c-Si), no tracks have been observed with any monomer ions up to GeV. Tracks are formed in c-Si under 40 MeV fullerene (C60) cluster ion irradiation, which provides much higher energy deposition than monomer ions. The track diameter decreases with decreasing the ion energy until they disappear at an extrapolated value of ~ 17 MeV. However, here we report the track formation of 10 nm in diameter under C60 ion irradiation of 6 MeV, i.e., much lower than the extrapolated threshold. The diameters of 10 nm were comparable to those under 40 MeV C60 irradiation. Furthermore, the tracks formed by 6 MeV C60 irradiation consisted of damaged crystalline, while those formed by 40 MeV C60 irradiation were amorphous. The track formation was observed down to 1 MeV and probably lower with decreasing the track diameters. The track lengths were much shorter than those expected from the drop of Se below the threshold. These track formations at such low energies cannot be explained by the conventional purely electronic energy deposition mechanism, indicating another origin, e.g., the synergy effect between the electronic and nuclear energy depositions, or dual transitions of transient melting and boiling.

Dosimetry of High-Energy Photon Beams Based on Standards of Absorbed Dose to Water: Abstract

2001 ◽  
Vol 1 (1) ◽  
pp. 8-8 ◽  
Author(s):  
K. Hohlfeld ◽  
P. Andreo ◽  
O. Mattsson ◽  
J. P. Simoen
Keyword(s):  
Reference Conditions ◽  
International Comparisons ◽  
Absorbed Dose ◽  
High Energy ◽  
National Standards ◽  
Photon Radiation ◽  
Photon Beams ◽  
Radiation Induced ◽  
Absorbed Dose To Water ◽  
Primary Standards

This report examines the methods by which absorbed dose to water can be determined for photon radiations with maximum energies from approximately 1 MeV to 50 MeV, the beam qualities most commonly used for radiation therapy. The report is primarily concerned with methods of measurement for photon radiation, but many aspects are also relevant to the dosimetry of other therapeutic beams (high-energy electrons, protons, etc.). It deals with methods that are sufficiently precise and well established to be incorporated into the dosimetric measurement chain as primary standards (i.e., methods based on ionisation, radiation-induced chemical changes, and calorimetry using either graphite or water). The report discusses the primary dose standards used in several national standards laboratories and reviews the international comparisons that have been made. The report also describes the reference conditions that are suitable for establishing primary standards and provides a formalism for determining absorbed dose, including a discussion of correction factors needed under conditions other than those used to calibrate an instrument at the standards laboratory.

scholarly journals New vistas in charm production

2019 ◽  
Vol 206 ◽  
pp. 02004
Author(s):  
Antoni Szczurek
Keyword(s):  
Large Deviations ◽  
Transition Probabilities ◽  
High Energy ◽  
Lhcb Collaboration ◽  
Charm Production ◽  
High Energy Neutrino ◽  
Neutrino Production ◽  
Energy Neutrino ◽  
Low Energies

We discuss some new aspects of charm production trigerred by recent observations of the LHCb collaboration. The LHCb collaboration measured small asymmetries in production of D+D−mesons as well as $ D_s^ + D_s^ - $ mesons. Is this related to initial quark/antiquark asymmetries in the proton ? Here we discuss a scenario in which unfavored fragmentations $ q/\bar {q} \to D $ and $ s/\bar {s} \to D_s $ are responsible for the asymmetries. We fix the strength of such fragmentations – transition probabilities, by adjusting to the size of the LHCb asymmetries. This has consequences for production of D mesons in forward directions (large xF ) as well as at low energies. Large asymmetries are predicted then in these regions. We present here some of our predictions. Consequences for high-energy neutrino production in the atmosphere are discussed and quantified. The production of Λc baryon at the LHC is disussed. Large deviations from the independent-parton fragmentation picture are found.

scholarly journals Physical Constraints on Models of Gamma-Ray Bursters

1986 ◽  
Vol 89 ◽  
pp. 305-321
Author(s):  
Richard I. Epstein
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
X Rays ◽  
Burst Source ◽  
Gamma Ray Burst ◽  
Physical Constraints ◽  
Low Energies ◽  
Energy Gamma ◽  
Photon Interactions

AbstractThe power per logarithmic bandwidth in gamma-ray burst spectra generally increases rapidly with energy through the x-ray range and does not cut off sharply above a few MeV. This spectral form indicates that a very small fraction of the energy from a gamma-ray burst source is emitted at low energies or is reprocessed into x-rays and that the high-energy gamma rays are not destroyed by photon-photon interactions. The implications are that the emission mechanism for the gamma-ray bursts is not synchrotron radiation from electrons that lose most of their energy before being re-accelerated and that either the regions from which the gamma rays are emitted are large compared to the size of a neutron star or the emission is collimated and beamed away from the stellar surface.

Comparative study of X-ray charge-density data on CoSb3

2013 ◽  
Vol 69 (6) ◽  
pp. 570-582 ◽  
Author(s):  
Mette Stokkebro Schmøkel ◽  
Lasse Bjerg ◽  
Finn Krebs Larsen ◽  
Jacob Overgaard ◽  
Simone Cenedese ◽  
...  
Keyword(s):  
Charge Density ◽  
High Performance ◽  
Theoretical Data ◽  
High Energy ◽  
Data Sets ◽  
High Symmetry ◽  
X Ray ◽  
Structure Factors ◽  
Small Crystals ◽  
Density Analysis

CoSb3is an example of a highly challenging case for experimental charge-density analysis due to the heavy elements (suitability factor of ∼0.01), the perfect crystallinity and the high symmetry of the compound. It is part of a family of host–guest structures that are potential candidates for use as high-performance thermoelectric materials. Obtaining and analysing accurate charge densities of the undoped host structure potentially can improve the understanding of the thermoelectric properties of this family of materials. In a previous study, analysis of the electron density gave a picture of covalent Co–Sb and Sb–Sb interactions together with relatively low atomic charges based on state-of-the-art experimental and theoretical data. In the current study, several experimental X-ray diffraction data sets collected on the empty CoSb3framework are compared in order to probe the experimental requirements for obtaining data of high enough quality for charge-density analysis even in the case of very unsuitable crystals. Furthermore, the quality of the experimental structure factors is tested by comparison with theoretical structure factors obtained from periodic DFT calculations. The results clearly show that, in the current study, the data collected on high-intensity, high-energy synchrotron sources and very small crystals are superior to data collected at conventional sources, and in fact necessary for a meaningful charge-density study, primarily due to greatly diminished effects of extinction and absorption which are difficult to correct for with sufficient accuracy.

Resonant emission of hard gamma-quanta at scattering of ultrarelativistic electrons on a nucleus within the external light field

2020 ◽  
Vol 35 (03) ◽  
pp. 2040024 ◽  
Author(s):  
Alexander Dubov ◽  
Victor V. Dubov ◽  
Sergei P. Roshchupkin
Keyword(s):  
Cross Section ◽  
Gamma Quantum ◽  
External Electromagnetic Field ◽  
High Energy ◽  
Scattering Cross Section ◽  
Photon Radiation ◽  
Order Effects ◽  
Data Simulation ◽  
Scattering Cross ◽  
Resonant Emission

The contemporary theoretical investigation researches the resonant emission of high-energy gamma-quanta within the process of scattering of ultrarelativistic electrons on a nucleus in the external electromagnetic field. With implementation of the resonant conditions under the field ambience the particle in the intermediate state re-modulates into the real form. Therefore, the phenomenon examination determines the functional splitting of the second order process into a pair of first-order effects that possess a possibility to develop within two reaction channels. Consequently, the first channel characterizes the kinematics of electron scattering by a nucleus and following radiation of a spontaneous gamma-quantum. The second channel delineates the spontaneous gamma-quantum radiation by an electron with subsequent scattering on a nucleus. It is important to emphasize that within a specific range of observation the calculations derive three discrete magnitudes for the resonant frequency dependency on the angle of spontaneous photon radiation. As a result, the work represents an estimation of the resonant differential scattering cross-section in ratio to the scattering cross-section computed without the external field. In conclusion, various scientific facilities may verify the project data simulation (SLAC, FAIR, XFEL, ELI, XCELS).

ON FERMION NUMBER VIOLATION AT HIGH ENERGIES

1990 ◽  
Vol 05 (16) ◽  
pp. 1279-1289 ◽  
Author(s):  
KENICHIRO AOKI
Keyword(s):  
High Energy ◽  
Back Reaction ◽  
Coupling Constant ◽  
Fermion Number ◽  
High Energy Behavior ◽  
Energy Behavior ◽  
Low Energies ◽  
Naive Dimensional Analysis ◽  
Group Flow ◽  
Electroweak Model

By considering the back reaction of the scattered particles on instantons, the explicit high energy behavior of fermion number violating amplitudes in the standard electroweak model is obtained to the leading order in the coupling constant. The amplitudes decay faster than what is expected from naive dimensional analysis due to the renormalization group flow of the coupling constant and this is consistent with unitarity. Also, it is shown that the constrained instanton approach is valid at low energies, while the high energy behavior is governed by the back reaction of the external particles.

scholarly journals Emergent Chiral Symmetry: Parity and Time Reversal Doubles

1997 ◽  
Vol 12 (29) ◽  
pp. 5325-5357 ◽  
Author(s):  
A. P. Balachandran ◽  
S. Vaidya
Keyword(s):  
Time Reversal ◽  
Particle Physics ◽  
Nuclear Physics ◽  
Degrees Of Freedom ◽  
High Energy ◽  
Approximate Symmetry ◽  
Opposite Parity ◽  
Doublet Structure ◽  
Low Energies ◽  
Oppenheimer Approximation

There are numerous examples of approximately degenerate states of opposite parity in molecular physics. Theory indicates that these doubles can occur in molecules that are reflection-asymmetric. Such parity doubles occur in nuclear physics as well, among nuclei with odd A ~ 219–229. We have also suggested elsewhere that such doubles occur in particle physics for baryons made up of cbu and cbd quarks. In this article, we discuss the theoretical foundations of these doubles in detail, demonstrating their emergence as a surprisingly subtle consequence of the Born–Oppenheimer approximation, and emphasizing their bundle-theoretic and topological underpinnings. Starting with certain "low energy" effective theories in which classical symmetries like parity and time reversal are anomalously broken on quantization, we show how these symmetries can be restored by judicious inclusion of "high-energy" degrees of freedom. This mechanism of restoring the symmetry naturally leads to the aforementioned doublet structure. A novel byproduct of this mechanism is the emergence of an approximate symmetry (corresponding to the approximate degeneracy of the doubles) at low energies which is not evident in the full Hamiltonian. We also discuss the implications of this mechanism for Skyrmion physics, monopoles, anomalies and quantum gravity.

Total and Partial Photon Interactions of BaSO4-Na2O-B2O3-SiO2

2016 ◽  
Vol 872 ◽  
pp. 138-144
Author(s):  
Natthakridta Chanthima ◽  
Jakrapong Kaewkhao ◽  
Sunisa Sarachai ◽  
Narong Sangwaranatee ◽  
Nisakorn W. Sangwaranatee
Keyword(s):  
Theoretical Approach ◽  
Glass Sample ◽  
Effective Atomic Number ◽  
Mass Attenuation Coefficient ◽  
Photoelectric Effect ◽  
Radiation Shielding ◽  
Effective Electron ◽  
Low Energies ◽  
Electron Field ◽  
Photon Interactions

The radiation parameters of barite sodium silicoborate glass (BaSO4:Na2O:SiO2:B2O3) with different concentration of barite (BaSO4) were studied. The mass attenuation coefficient (μ/ρ), effective atomic number (Zeff) effective electron densities (Ne,eff) and half value layer (HVL) have been calculated by theoretical approach using WinXCom program in the energy range of 1 keV to 100 GeV. The results of these parameters are show graphically for total and partial photon interaction. It was found that the Zeff show discontinuous jumps related to absorption edges and dominance photoelectric effect at low energies, pair production have two types which are nuclear and electron field and its slightly increased with increasing photon energies. The variation of Ne,eff was related to the value of Zeff. The half value layer (HVL) of glasses were compared with commercial window and some standard shielding concretes which observed that the value of 20 mol% BaSO4 has lower than commercial window, ordinary and hematite-serpentine concretes. These results showed that glass sample is promising radiation shielding materials.

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