Effects Of Heavy Charged Particles Research Articles

Экспериментальные исследования радиационного воздействия на микросхемы FRAM

The work is devoted to the study of radiation effects on FRAM memory chips. The effects of heavy charged particles entering the microcircuits are considered, the results in static and dynamic modes are analyzed. In statistical mode, the sensitivity of FRAM did not show any dependencies on the data pattern, but showed a relationship with fluence. In dynamic mode, the order of access to memory cells does not affect the sensitivity of memory. The dependences of the consumption current on the radiation dose and the annealing time after irradiation are given. An effects map is shown showing a two-band area sensitive to the laser. According to its relative area, this is the peripheral logic of the device. Studies have confirmed the usefulness of only a few effect maps. This is consistent with the results of tests for exposure to heavy charged particles.

Схемотехнические методы обеспечения стойкости ЭКБ к воздействию тяжёлых заряженных частиц

The paper considers circuit engineering methods for protecting the electronic component base from the effects of heavy charged particles. One of the main methods is to increase the capacity of the device, which leads to an increase in the capacity of diffusion regions and a decrease in the frequency of single events. The structure of a capacitor is shown, which is connected to various nodes of the circuit to increase the sensitivity of the capacitance of the node. The article focuses on the method of using active RC circuits in the feedback circuit of a storage device cell. The advantages and disadvantages of the methods of using a storage device cell with internal redundancy are noted. The paper shows that the use of circuit engineering methods will provide the required level of fault and fault tolerance to the effects of heavy charged particles.

Анализ чувствительности и результаты испытаний электронной компонентной базы к воздействию тяжелых заряженных частиц

The work is devoted to the study of the sensitivity of the electronic component base (ECB) to the effects of heavy charged particles. At the same time, the degree of sensitivity is distinguished depending on the functional group of ECB products to the effects of ionization radiation from outer space and on the design and technological design of ECB products. The paper presents the characteristics and conditions for the use of ECB in the radio-electronic equipment of outer space to ensure minimal sensitivity to the effects of ionization radiation and to the thyristor effect. After the sensitivity analysis of ECB products is carried out, a preliminary selection of ECB is performed, requiring testing. The article discusses the criteria for determining the ECB that requires testing and is possible to use without testing. The methods of increasing the durability of radio-electronic equipment of space equipment and the directions of optimization of the methodology of analysis of ECB lists are determined.

Genomic Instability and Carcinogenesis of Heavy Charged Particles Radiation: Clinical and Environmental Implications.

One of the uses of ionizing radiation is in cancer treatment. The use of heavy charged particles for treatment has been introduced in recent decades because of their priority for deposition of radiation energy in the tumor, via the Bragg peak phenomenon. In addition to medical implications, exposure to heavy charged particles is a crucial issue for environmental and space radiobiology. Ionizing radiation is one of the most powerful clastogenic and carcinogenic agents. Studies have shown that although both low and high linear energy transfer (LET) radiations are carcinogenic, their risks are different. Molecular studies have also shown that although heavy charged particles mainly induce DNA damage directly, they may be more potent inducer of endogenous generation of free radicals compared to the low LET gamma or X-rays. It seems that the severity of genotoxicity for non-irradiated bystander cells is potentiated as the quality of radiation increases. However, this is not true in all situations. Evidence suggests the involvement of some mechanisms such as upregulation of pro-oxidant enzymes and change in the methylation of DNA in the development of genomic instability and carcinogenesis. This review aimed to report important issues for genotoxicity of carcinogenic effects of heavy charged particles. Furthermore, we tried to explain some mechanisms that may be involved in cancer development following exposure to heavy charged particles.

Защиты микросхем от воздействия тяжелых заряженных частиц

Защиты микросхем от воздействия тяжелых заряженных частиц

Radial dose distributions from protons of therapeutic energies calculated with Geant4-DNA

Models based on the amorphous track structure approximation have been successful in predicting the biological effects of heavy charged particles. Development of such models remains an active area of research that includes applications to hadrontherapy. In such models, the radial distribution of the dose deposited by delta electrons and directly by the particle is the main characteristic of track structure. We calculated these distributions with Geant4-DNA Monte Carlo code for protons in the energy range from 10 to 100 MeV. These results were approximated by a simple formula that combines the well-known inverse square distance dependence with two factors that eliminate the divergence of the radial dose integral at both small and large distances. A clear physical interpretation is given to the asymptotic behaviour of the radial dose distribution resulting from these two factors. The proposed formula agrees with the Monte Carlo data within 10% for radial distances of up to 10 μm, which corresponds to a dose range covering over eight orders of magnitude. Differences between our results and those of previously published analytical models are discussed.

Ground-based research with heavy ions for space radiation protection

Human exposure to ionizing radiation is one of the acknowledged potential showstoppers for long duration manned interplanetary missions. Human exploratory missions cannot be safely performed without a substantial reduction of the uncertainties associated with different space radiation health risks, and the development of effective countermeasures. Most of our knowledge of the biological effects of heavy charged particles comes from accelerator-based experiments. During the 35th COSPAR meeting, recent ground-based experiments with high-energy iron ions were discussed, and these results are briefly summarised in this paper. High-quality accelerator-based research with heavy ions will continue to be the main source of knowledge of space radiation health effects and will lead to reductions of the uncertainties in predictions of human health risks. Efforts in materials science, nutrition and pharmaceutical sciences and their rigorous evaluation with biological model systems in ground-based accelerator experiments will lead to the development of safe and effective countermeasures to permit human exploration of the Solar System.

Heavy ion radiobiology for hadrontherapy and space radiation protection

Research in the field of biological effects of heavy charged particles is needed for both heavy-ion therapy (hadrontherapy) and protection from the exposure to galactic cosmic radiation in long-term manned space missions. Although the exposure conditions (e.g. high- vs. low-dose rate) and relevant endpoints (e.g. cell killing vs. neoplastic transformation) are different in the two fields, it is clear that a substantial overlap exists in several research topics. Three such topics are discussed in this short review: individual radiosensitivity, mixed radiation fields, and late stochastic effects of heavy ions. In addition, researchers involved either in experimental studies on space radiation protection or heavy-ion therapy will basically use the same accelerator facilities. It seems to be important that novel accelerator facilities planned (or under construction) for heavy-ion therapy reserve a substantial amount of beamtime to basic studies of heavy-ion radiobiology and its applications in space radiation research.

Mutagenic Effects of Heavy Charged Particles

Heavy charged particles constitute the most important radiation risk in space. Since mutations can give rise to cancer the investigation of their induction may be helpful for risk quantification. This paper describes experiments in a number of mammalian cells performed with a large range of linear energy transfer (LET). RBE values are always found to increase with LET up to about 100 keV/microm and are similar to those suggested by ICRP. Molecular analyses demonstrate that heavy charged particles not only lead to sometimes very large deletions but also to smaller changes which might represent point mutations. Recent evidence shows that repair phenomena play an important role in the processing of initial DNA lesions to mutagenic alterations.

Effects of Heavy Charged Particles on Rhodopsin and Isolated Retina

Effects of Heavy Charged Particles on Rhodopsin and Isolated Retina

Track structure and the calculation of biological effects of heavy charged particles

A new approach for the calculation of biological effects of heavy charged particles is discussed. In contrast to other models, the biological effect is determined locally as a function of the local dose deposited by the charged particle tracks. Based on measurable quantities like the X-ray survival curve, the radial dose profile within a track and a geometrical description of the cell nucleus, the model is able to predict several high LET specific properties of charge particle beams, like • • the relationship of inactivation cross sections vs. LET and vs. specific energy; • • the RBE as a function of energy and atomic number of the particles, including the Z-dependent shift of RBE-maxima from 30 keV/μ m for protons to 300 keV/μ m for carbon ions; • • the transition from exponential to shouldered survival curves, depending on the size of the biological object and the corresponding particle fluences.

Production of DNA Strand Breaks by Direct Effects of Heavy Charged Particles

A theoretical model has been developed to calculate the yields of single- and double-strand breaks in DNA induced by direct effects of ionizing radiation. In this model, which involves no fitted parameters, elements of track structure and stopping power theory are combined with a detailed geometrical description of DNA to calculate the energy deposited by fast charged particles to DNA molecules. The average energy per interaction with a DNA molecule is estimated to be 30 eV from the available data on oscillator strength measurements. These ideas have been incorporated in a Monte Carlo computer program using Poisson statistics to treat the stochastic nature of the energy deposition processes and thereby determine the excitation and ionization states of the molecule. Each ionization reaction on the DNA backbone is assumed to lead to a DNA strand break. In our model double-strand breaks result from nearby independent breaks on opposite strands. Our calculated single- and double-strand break yields compare well with measured cellular data under conditions such that direct effects are thought to dominate strand break production.

The preparation of biological targets for heavy-ion experiments up to 20 MeV/u

The radiobiological effects of heavy charged particles are of fundamental interest for the understanding of radioprotection problems in manned space flights and for the increasing use of heavy ions in radiotherapy. Therefore, an increasing number of radiobiological experiments are performed at heavy-ion accelerators. In these experiments biological targets such as, for instance, cultures of living mammalian cells have to be irradiated under sterile conditions and atmospheric pressure. The experimental solution of these and other biology-specific problems is discussed and a general outline of the experiments is given.

Cellular and subcellular effect of heavy ions: A comparison of the induction of strand breaks and chromosomal aberration with the incidence of inactivation and mutation

Radiobiological effects of heavy charged particles are compared for a large variety of ions from Helium to Uranium and energies between 1 and 1000 MeV/u which correspond to LET values between 10 and 16000 keV/μm. The different cross section for the induction of strand breaks and chromosomal aberrations as well as for inactivation and mutation induction exhibit striking similarities when compared as function of the linear energy transfer (LET). At LET values below 100 keV/μm all data points of one specific effect form one single curve as a function of LET, independent of the atomic number of the ion. In this LET range, the biological effects are independ from the particle energy or track structure and depend only on the energy transfer. Therefore, LET is a good parameter in this regime. For LET values greater than 100 keV/μm, the curves for the different ions separate from the common curve in order of increasing atomic numbers. In this regime LET is no longer a good parameter and the physical parameters of the formation of particle tracks are important. The similarity of the σ-LET curves for different endpoints indicates that the ‘hook-structure’ is produced by physical and chemical effects which occur before the biologically relevant lesions are formed. However, from the existing data of biological effects, it can be concluded that the efficiencies for cell killing are always smaller than those extrapolated from X-ray data on the basis of the energy deposition only. Therefore, cells which are directly hit by an HZE particle are not killed and undergo a finite risk of mutation and transformation.

Cataract analysis and the assessment of radiation risk in space

Radiation cataract, a non-stochastic effect on the lens, is readily amenable to non-invasive analysis. Thus, it provides the means to assess radiation risk in space and for long-term monitoring of those who frequent that environment. The importance of such evaluations are underscored by the uncertainties associated with the assignment of quality factors for the effects of heavy charged particles constituting cosmic and solar radiation. Experimental studies were conducted using albino rats to evaluate the cataractogenic potential of 570 MeV/amu Argon ions administered as both single and protracted doses. The cataract studies and investigations of quantitative cytopathological changes associated with them indicate that as the dose of heavy particles decreases, the relative biological effectiveness, compared to X rays, increases. Fractionating the exposures not only failed to reduce the cataractogenic effect but caused a dose- dependent enhancement in the time of onset of opacification. Cytopathologically, the damage caused by heavy particles, when compared to low-LET radiation was found to be quantitatively dissimilar but qualitatively identical. In addition, damage which might be consistent with microlesions was not evident. The data indicates that as regards the cataractogenic potential of heavy particles at low doses an assignment of a Quality Factor (QF) of at least 40 may be in order.

Late Effects of Heavy Charged Particles on the Fine Structure of the Mouse Coronary Artery

A pilot study was conducted to evaluate ultrastructural changes in the coronary arteries of the B6CF1 mouse 15 months after irradiation with photons or heavy charged particles. Irradiations, given at 4 months of age, included single upper-body doses of 1.6 Gy 40Ar, 0.2, 0.4, 0.8, or 3.2 Gy 2?Ne, 0.1 or 3.2 Gy '2C, and 1.6, 3.2, or 7.0 Gy 60Co y. Coronary artery degeneration was found in both irradiated and unirradiated control animals. Radiation appeared to produce more severe degenerative changes than that seen in the age-matched controls. The major changes included medial smooth muscle degeneration, fibrosis, accumulation of debris, and extracellular matrix. On the basis of quantitative analysis, about 12% of the smooth muscle areas examined showed deterioration in the age-matched unirradiated animals. This percentage was increased significantly at doses above 0.1 Gy, ranging between 20 (P < 0.01) and 44% (P < 0.001), in the irradiated groups. A single dose of only 0.2 Gy 20Ne ions produced significant damage to the smooth muscle cells. Over at least part of the dose range explored, smooth muscle damage increased with dose for all radiation qualities. Although heavy charged particles are more effective in producing damage than photons, the present data are insufficient to demonstrate a LET dependence among charged particles or estimate relative biological effectiveness.

The Technique of Bombarding Organic Compounds with Deuterons

In order to study the chemical effects of heavy charged particles, a number of organic compounds—gases, liquids, and solids—have been bombarded with deuterons from the M.I.T.cyclotron. This work, carried out under American Petroleum Institute Project 43c, included paraffins, organic acids, salts, and some complex mixtures. Gas bombardments were made at approximately atmospheric pressure in a water-cooled gas chamber (volume: 2.54 liters) provided with a 2-mil copper window for the entry of the external deuteron beam. A thermocouple and a Bourdon gauge connected to a Microtorque potentiometer allowed the gas temperature and pressure to be recorded electrically at the control bench during the bombardment of liquids and solids. Water-cooled target-holders provided with 2-mil copper windows were mounted inside the gas chamber which served to collect the product gases. To prevent chemical reactions of the compounds with the metal parts, chamber and target-holders were gold-plated.