scholarly journals High Energies and Radiation Effects

2021 ◽  
pp. 135-149
Author(s):  
Donald V. Reames
Keyword(s):  
Radiation Dose ◽  
Radiation Effects ◽  
Radial Distance ◽  
High Energy ◽  
Upper Atmosphere ◽  
Energy Spectra ◽  
The Sun ◽  
Deep Space ◽  
Strong Function ◽  
Radiation Induced

AbstractIn this chapter we characterize the high-energy spectra of protons that can penetrate shielding and determine the radiation dose to humans and equipment in space. High-energy spectral breaks or “knees”, seen in all large SEP events, determine the contribution of highly penetrating protons. The streaming limit, discussed earlier, places an upper bound on particle fluences early in events and the radial variation of intensities is important for near-solar and deep-space missions. The streaming limit is a strong function of radial distance from the Sun. We also consider requirements for a radiation storm shelter for deep space, a mission to Mars, suitability of exoplanets for life, and radiation-induced chemistry of the upper atmosphere of Earth.

Evaluating the Martian radiation environment based on state-of-art measurements and modelling results

2020 ◽  
Author(s):  
Jingnan Guo ◽  
Robert Wimmer-Schweingruber ◽  
Cary Zeitlin ◽  
Donald Hassler ◽  
Bent Ehresmann
Keyword(s):  
Space Exploration ◽  
Galactic Cosmic Rays ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Radiation Environment ◽  
Whole Body ◽  
The Sun ◽  
Deep Space ◽  
Radiation Risks ◽  
Radiation Induced

<p>In recent years, space agencies such as ESA, NASA, the Chinese space agency and even private sectors have been planning human deep space exploration programs to the Moon and Mars. This requires a very timely and thorough investigation to better understand the space weather conditions and effects for such deep space activities in order to further develop mitigation strategies against the associated radiation risks on humans in space.</p> <p>Radiation damage in deep space comes mainly from two sources, Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs). As an omnipresent background, radiation induced by GCRs, which are modulated by solar activities, may increase the chance of long-term health consequences, such as onset of cancer, cardiovascular diseases, skin atrophy, eye cataract, leukemia, anemia, leucopenia and malfunctions of the central nervous system. On the other hand, intense solar energetic particles (SEPs) can be considered as mightily related to deterministic radiation effects which are of great concern for space exploration. Acute radiation syndrome (ARS) or sickness or poisoning or toxicity is induced after a whole-body exposure to high doses of radiation between at the Gy [J/kg] level. Such events, despite of being rather infrequent, could result in severe damage to humans and equipment and lead to potential failure of the entire mission and therefore should be detected and mitigated as immediately as possible.</p> <p>Under different shielding environment, the intensity and composition of the GCRs/SEPs may vary due to the interactions of primary particles (of different energies and charges) with the surrounding material and the generation of secondaries. Therefore, a precise quantification of the change of particle spectra under different shielding environment (e.g., within a spacecraft in deep space or at Martian surface or even subsurface which might be used for future habitat shielding) using a synergistic combination of measurements and particle-transport models is essential for assessing and predicting the radiation environment therein as well as its changes during different solar activities.</p> <p>Another major challenge in predicting the radiation risks for humans in space is the sudden and sporadic radiation induced by SEPs which can be very intense, dynamic and may vary drastically in time and location. Specifically speaking, the radiation and particle enhancement measured at (or predicted for) Earth’s vicinity may be completely different from of that detected elsewhere in the heliosphere as for a Mars mission, due to the different magnetic connection and distance of Mars (or the cruise spacecraft) from the acceleration and release region of SEPs near the Sun. We highlight the utmost importance of utilizing multi-spacecraft in-situ and remote sensing observations of the Sun and the heliosphere to better understand such dynamic events and their dynamic effects across the heliosphere in particular at locations where human explorations may take place.</p>

Crosslinking and Radiation Effects in Some Natural and Synthetic Rubbers

1957 ◽  
Vol 30 (1) ◽  
pp. 27-41 ◽  
Author(s):  
A. Charlesby ◽  
D. Groves
Keyword(s):  
Radiation Dose ◽  
Natural Rubber ◽  
Radiation Effects ◽  
Main Chain ◽  
High Energy ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Physical Technique ◽  
Chemical Agents ◽  
Natural And Synthetic

Abstract When subjected to atomic energy radiation certain polymers crosslink, a process which is equivalent to vulcanization, but occurs without the admixture of extraneous chemical agents. Other polymers degrade by main chain fracture, a process which occurs at random throughout the molecule, and is different from thermal or ultraviolet degradation. Methods available for detecting crosslinking in irradiated polymers, include those based on solubility and swelling which have been used to study the effect of high energy radiation on a number of natural and synthetic rubbers. The polymers investigated include natural rubber, polychloroprene, polyisobutylene, polybutadiene, and thioplasts, as well as some copolymers. The results show the degree of crosslinking to be proportional to radiation dose, and to be reduced by the presence of styrene or acrylonitrile units in copolymers. Possible applications of this physical technique of linking molecules are discussed briefly.

scholarly journals Positron annihilation spectroscopy study of radiation-induced defects in W and Fe irradiated with neutrons with different spectra

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
O. V. Ogorodnikova ◽  
M. Majerle ◽  
J. Čížek ◽  
S. Simakov ◽  
V. V. Gann ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Radiation Effects ◽  
Defect Formation ◽  
Wide Spectrum ◽  
High Energy ◽  
Primary Radiation ◽  
Vacancy Clusters ◽  
Mean Size ◽  
Radiation Induced ◽  
Fission Neutrons

Abstract The paper presents new knowledge on primary defect formation in tungsten (W) and iron (Fe) irradiated by fission and high-energy neutrons at near-room temperature. Using a well-established method of positron-annihilation lifetime-spectroscopy (PALS), it was found that irradiation of W in the fission reactor and by high-energy neutrons from the p(35 MeV)-Be generator leads to the formation of small radiation-induced vacancy clusters with comparable mean size. In the case of Fe, smaller mean size of primary radiation-induced vacancy clusters was measured after irradiation with fission neutrons compared to irradiation with high-energy neutrons from the p(35 MeV)-Be generator. It was found that one of the reasons of the formation of the larger size of the defects with lower density in Fe is lower flux in the case of irradiation with high-energy neutrons from the p(35 MeV)-Be source. The second reason is enhanced defect agglomeration and recombination within the energetic displacement cascade at high energy primary knock-on-atoms (PKAs). This is consistent with the concept of the athermal recombination corrected (arc-dpa) model, although the measured dpa cross-section of both fission neutrons and wide-spectrum high-energy neutrons in W is between the conventional Norgett–Robinson–Torrens (NRT-dpa) and arc-dpa predictions. This means that the physics of the primary radiation effects in materials is still not fully known and requires further study through a combination of modeling and experimental efforts. The present data serve as a basis for the development of an improved concept of the displacement process.

Radiation-induced racemization and amplification of chirality: implications for comets and meteorites

2007 ◽  
Vol 6 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Franco Cataldo
Keyword(s):  
Cosmic Rays ◽  
Radiation Dose ◽  
Optical Activity ◽  
High Energy ◽  
Chiral Molecules ◽  
Radiation Processing ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Naturally Occurring ◽  
Radiation Induced

The action of high-energy radiation on prebiotic chiral molecules plays against the preservation of chirality. Chiral molecules incorporated in comets and meteorites are bombarded for billions of years by cosmic rays and by the high-energy radiation due to the decay of naturally occurring radionuclides. The action of cosmic rays on the surface of comets and meteorites causes the complete radiation processing of the surface of these bodies, but at depths of 20 m or so the cosmic rays are completely shielded and the radiation should derive only from the decay of radionuclides. In 4.6×109 yr the radiation dose supplied by the radionuclide decay to the organic molecules present inside the cometary or meteoritic body is equivalent to 14000 kGy. Our studies on the radiolysis of a series of naturally occurring chiral molecules, the terpenes, have shown that although all undergo the radioracemization reaction, the extent of radioracemization is such that a significant fraction of chiral excess and chiral molecules can survive a radiation dose equivalent to 14000 kGy. A unique exception is represented by the terpene β-(−)-pinene which, instead of the expected radioracemization reaction, undergoes a radiation-induced polymerization. The resulting poly-β-pinene, having an highly ordered supramolecular structure, displays an optical activity which is 1.7 times higher than the starting monomer. Thus, in this specific case, the optical activity is not reduced but enhanced by the action of radiation and remains locked into a polymer which displays a considerable radiation resistance and may act as a chiral template and as a chiral surface for prebiotic chemistry.

In situ TEM studies of irradiation effects for materials improvement

1991 ◽  
Vol 49 ◽  
pp. 452-453
Author(s):  
Charles W. Allen
Keyword(s):  
Nuclear Reactor ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Point Of View ◽  
In Situ Tem ◽  
Irradiation Effects ◽  
Tem Analysis ◽  
Radiation Induced ◽  
Analytical Tools

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.

A review on radiation induced nausea and vomiting: “Current management strategies and prominence of radio sensitizers”

2021 ◽  
pp. 107815522110115
Author(s):  
Meenu Vijayan ◽  
Sherin Joseph ◽  
Emmanuel James ◽  
Debnarayan Dutta
Keyword(s):  
Radiation Therapy ◽  
Cell Damage ◽  
Genetic Material ◽  
High Energy ◽  
Concurrent Chemotherapy ◽  
Nausea And Vomiting ◽  
Dose Fractionation ◽  
Psychological State ◽  
Related Factors ◽  
Radiation Induced

Radiations dissipated are high energy waves used mostly as treatment intervention in controlling the unwanted multiplication of cell. About 60%–65% of cancer treatment requires radiation therapy and 40%–80% of radiation therapy causes RINV which are true troublemakers. Radiation therapy (RT) is targeted therapy mostly used to treat early stages of tumour and prevent their reoccurrence. They mainly destroy the genetic material (DNA) of cancerous cells to avoid their unwanted growth and division. The RINV affects the management and quality of life of patients which further reduces the patient outcome. RINV depends on RT related factors (dose, fractionation, irradiation volume, RT techniques) and patient related factors like (gender, health conditions, age, concurrent chemotherapy, psychological state, and tumour stage). RT is an active area of research and there is only limited progress in tackling the RINV crisis. Advanced technological methods are adopted that led to better understanding of total lethal doses. Radiation therapy also affects the immunity system that leads to radiation induced immune responses and inflammation. Radio sensitizers are used to sensitize the tumour cells to radiations that further prevent the normal cell damage from radiation exposure. There is a need for future studies and researches to re-evaluate the data available from previous trials in RINV to make better effective antiemetic regimen. The article focuses on radiation therapy induced nausea and vomiting along with their mechanism of action and treatment strategies in order to have a remarkable patient care.

Preliminarily study of Saturn’s upper atmosphere density by observing Cassini plunging via China’s deep space station

2020 ◽  
Vol 20 (7) ◽  
pp. 102
Author(s):  
Lue Chen ◽  
Jin-Song Ping ◽  
Xiang Liu ◽  
Na Wang ◽  
Jian-Feng Cao ◽  
...  
Keyword(s):  
Space Station ◽  
Upper Atmosphere ◽  
Deep Space ◽  
Atmosphere Density

scholarly journals Exploring Flaring Behaviour on Low Mass Stars, Solar-type Stars and the Sun

2019 ◽  
Vol 15 (S354) ◽  
pp. 384-391
Author(s):  
L. Doyle ◽  
G. Ramsay ◽  
J. G. Doyle ◽  
P. F. Wyper ◽  
E. Scullion ◽  
...  
Keyword(s):  
High Energy ◽  
The Sun ◽  
Low Mass Stars ◽  
Highly Active ◽  
Rotation Phase ◽  
Solar Type ◽  
Low Mass ◽  
Insight Into ◽  
Reconnection Model ◽  
High Cadence

AbstractWe report on our project to study the activity in both the Sun and low mass stars. Utilising high cadence, Hα observations of a filament eruption made using the CRISP spectropolarimeter mounted on the Swedish Solar Telescope has allowed us to determine 3D velocity maps of the event. To gain insight into the physical mechanism which drives the event we have qualitatively compared our observation to a 3D MHD reconnection model. Solar-type and low mass stars can be highly active producing flares with energies exceeding erg. Using K2 and TESS data we find no correlation between the number of flares and the rotation phase which is surprising. Our solar flare model can be used to aid our understanding of the origin of flares in other stars. By scaling up our solar model to replicate observed stellar flare energies, we investigate the conditions needed for such high energy flares.

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.

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