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Sample records for alpha particles biological effects

  1. Moisture content of seeds affects relative biological effectiveness of alpha particles but not protons in thermal neutron exposure

    International Nuclear Information System (INIS)

    The influences of moisture content of barley (Hordeum vulgare L.) seeds which were presoaked for 13 h and re-dried before irradiation on boron addition effect (BAE) and relative biological effectiveness (RBE) of alpha particles and protons were evaluated. Seeds of normal (10.21% in embryo), low (2.55%) and high (28.0%) moisture content showed different regression of BAE values on the absorbed amount of sup(10)B. The regression coefficient was highest for normal moisture content, followed by low moisture content, and the lowest for high moisture content. RBE of alpha particles also significantly differed between the moisture contents. Seeds of normal, low and high moisture contents showed 46.4, 37.4 and 17.0 of RBE value, respectively. Contrarily, RBE values of protons did not significantly vary with moisture content. It was found that the ratio of RBE of alpha particles between different moisture contents could be expressed by the product of the three ratios, i.e. ratio of sensitivity to gamma-rays, ratio of BAE, and ratio of moisture content. It was concluded that adjustment of moisture of the seeds to normal content (about 10%) is important to get a high value of both BAE and RBE of alpha particles

  2. Alpha particle effects on MHD ballooning

    International Nuclear Information System (INIS)

    During the period, as the first step towards the goal of detail understanding of the effects of alpha particle on MHD Ballooning Modes, a new numerical approach to investigate the stability of low-frequency fluctuations in high temperature tokamaks was developed by solving the gyrokinetic equations for the ion and electron directly as an initial value problem. The advantage of this approach is the inclusion of many important kinetic features of the problem without approximations and computationally more economical than particle-pushing simulation. The ion-temperature-gradient-mode was investigated to benchmark this new simulation technique. Previous results in literature were recovered. Both the adiabatic electron model and the full drift-kinetic electron model are studied. Numerical result shows that the full drift-kinetic electron model is more unstable. The development of subcycling technique to handle the fast electron bounce time is particularly significant to apply this new approach to the alpha particle problem since alpha particle bounce frequency is also significantly higher than the mode frequency. This new numerical technique will be the basis of future study of the microstability in high temperature tokamaks with alpha particles (or any energetic species). 15 refs., 13 figs

  3. Simultaneous estimation of relative biological effectiveness of alpha particles and protons in thermal neutron exposure of barley (Hordeum vulgare L.) seeds

    International Nuclear Information System (INIS)

    The relative biological effectiveness (RBE) of alpha particles and protons emitted during exposure of barley (Hordeum vulgare L.) seeds to thermal neutrons were estimated. sup(10)B-enriched re-dried seeds were irradiated with thermal neutrons or gamma-rays. Two assumptions so far believed that boron distribution was uniform throughout either natural dormant seeds or sup(10)B -enriched seeds, and that boron atoms enter the seeds as freely as water molecules do, were found to be invalid. A boron addition effect (BAE) as high as 58.2 was obtained after thermal neutron exposure of seeds presoaked in 4800 microg/g of sup(10)B-enriched boric acid solution. Estimates of RBE of alpha particles were nearly constant and independent of the contents of absorbed sup(10)B. RBE averaged 55.0 and 55.1 for the seed and spike presoaking methods of boron absorption, respectively. We could also obtain RBE of protons as high as 48.7 and 43.9 for the seed and spike methods, respectively. Boron addition converted the principal capture element during thermal neutron exposure from protons in dormant seeds to boron in sup(10)B enriched-seeds

  4. Biological dosimeter for UV-radiation and alpha particles, based on DNA damages

    International Nuclear Information System (INIS)

    A bioluminescence method for determination of biologically relevant (DNA damaging) doses of UV-radiation and alpha particles is developed. The method is based on bacterial luminescence as a bio-marker regulated by the SOS system. Cultures of E. coli cells transformed with the plasmid pPSL1 which carries the lux gene under control of the col promotor, an SOS-controlling gene, is used. The lux gene encode the enzyme luciferase which takes part in the reaction, resulting in the emission of a visible light at 490 nm. The light output is measured by photomultiplier and one channel analyzer. SOS-response kinetic curves of bacteria, UV-irradiated and treated with alpha particles, are obtained. An assessment of the risk from solar UV-radiation is made. The method has the sensitivity required to be used as biological UV-dosimeter (author)

  5. Metabolism and biological effects of alpha-emitting radionuclides

    International Nuclear Information System (INIS)

    The emphasis of much of the current and planned research on the toxicity of alpha-emitting radionuclides is directed toward the complexities of actual and potential conditions of occupational environmental exposures of human beings. These, as well as the more limited studies on mechanisms of biological transport and effects, should increase our ability to predict health risks more accurately and to deal more confidently with human exposures, if and when they occur

  6. Alpha-particle diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Young, K.M.

    1991-01-01

    This paper will focus on the state of development of diagnostics which are expected to provide the information needed for {alpha}- physics studies in the future. Conventional measurement of detailed temporal and spatial profiles of background plasma properties in DT will be essential for such aspects as determining heating effectiveness, shaping of the plasma profiles and effects of MHD, but will not be addressed here. This paper will address (1) the measurement of the neutron source, and hence {alpha}-particle birth profile, (2) measurement of the escaping {alpha}-particles and (3) measurement of the confined {alpha}-particles over their full energy range. There will also be a brief discussion of (4) the concerns about instabilities being generated by {alpha}-particles and the methods necessary for measuring these effects. 51 refs., 10 figs.

  7. Studying effects of Magnolol on alpha-particle induced bystander effects using PADC-film based dishes

    Energy Technology Data Exchange (ETDEWEB)

    Wong, T.P.W. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Tse, A.K.W.; Fong, W.F. [Research and Development Division, School of Chinese Medicine, Hong Kong Baptist University, Baptist University Road, Kowloon Tong (Hong Kong); Yu, K.N., E-mail: peter.yu@cityu.edu.h [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

    2009-10-15

    Radiation-induced bystander effect refers to the biological response found in cells (called bystander cells) which are not irradiated directly by ionizing radiation but are next to cells irradiated directly by ionizing radiation. In the present paper, the effects of Magnolol, an extract from the bark of Magnolia officinalis which is used as a traditional Chinese medicine, were studied on alpha-particle induced bystander effects. In our experiments, Chinese hamster ovary (CHO) cells were cultured in PADC-film based dishes and were irradiated with low fluences of alpha particles passing through the PADC films. The precise number of cells traversed or missed by alpha particles could be determined by studying the alpha-particle tracks developed on the PADC films upon subsequent chemical etching. TdT-mediated dUTP Nick-End Labeling (TUNEL) assay was employed to analyze the biological response of bystander cells in terms of DNA strand breaks. With the pretreatment of Magnolol, the DNA strand breaks in bystander cells were reduced, which showed that the alpha-particle induced bystander effects were suppressed with the presence of Magnolol. Since Magnolol is an antioxidant which can scavenge reactive oxygen species (ROS), our results give support to that ROS play a role in the bystander signal transmission in our experiments.

  8. Influence of Magnolol on the bystander effect induced by alpha-particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wong, T.P.W.; Law, Y.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Tse, A.K.W.; Fong, W.F. [Research and Development Division, School of Chinese Medicine, Hong Kong Baptist University, Baptist University Road, Kowloon Tong (Hong Kong); Yu, K.N. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)], E-mail: peter.yu@cityu.edu.hk

    2010-04-15

    In this work, the influence of Magnolol on the bystander effect in alpha-particle irradiated Chinese hamster ovary (CHO) cells was examined. The bystander effect was studied through medium transfer experiments. Cytokinesis-block micronucleus (CBMN) assay was performed to quantify the chromosome damage induced by alpha-particle irradiation. Our results showed that the alpha-particle induced micronuclei (MN) frequencies were suppressed with the presence of Magnolol.

  9. Alpha particle effects on global MHD modes, and alpha particle transport in ignited tokamaks

    International Nuclear Information System (INIS)

    The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable primarily by the circulating α-particles through wave-particle resonances. To destabilize the TAE modes, the inverse Landau damping associated with the α-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the α-particles and the core electrons and ions, as well as Alfven continuum damping. Stability criteria are presented for TFTR, CIT, and ITER tokamaks in terms of the α-particle beta βα, the α-particle pressure gradient parameter (ω*/ωA), where ω* is the α-particle diamagnetic drift frequency, and the α-particle velocity (vα/vA) parameter. Typically the volume averaged α-particle beta threshold is on the order of 10-4. Rough estimates of the TAE mode saturation level give δBr/B ∼ 10-3 for typical D-T tokamak operations. Significant α-particle losses are found when the amplitude of the global MHD modes is large, on the order of (δBr/B) ≥ 10-4. For (δBr/B) = 5 x 10-4, the α-particle loss time is appreciably shorter than the α-particle slowing-down time. 13 refs., 1 fig

  10. Effect of Alpha-Particle Irradiation on Brain Glycogen in the Rat

    Science.gov (United States)

    Wolfe, L. S.; Klatzo, Igor; Miquel, Jaime; Tobias, Cornelius; Haymaker, Webb

    1962-01-01

    The studies of Klatzo, Miquel, Tobias and Haymaker (1961) have shown that one of the earliest and most sensitive indications of the effects of alpha-particle irradiation on rat bran is the appearance of glycogen granules mainly in the neuroglia of the exposed area of the brain. Periodic acid-Schiff (PAS) positive, alpha-amylase soluble granules were demonstrated within 12 hr after irradiation, preceding by approximately 36 hr the first microscopically detectable vascular permeability disturbances, as shown by the fluorescein labeled serum protein technique. These studies suggested that the injurious effects of alpha-particle energy were on cellular elements primarily, according to the physical properties and distribution of the radiation in the tissue, and that the vascular permeability disturbances played a secondary role in pathogenesis. The purpose of this study was to correlate the histochemical observations on glycogen with a quantitative assessment of the glycogen in the irradiated brain tissue. It is felt that such a study may contribute to the understanding of radiation injury at the molecular level. A practical aspect of this problem is that the information on biological radiation effects due to accelerated particles from the cyclotron source, is employed in this study, is applicable to radiation from cosmic particles both in free space and entrapped in the Van Allen belts.

  11. Synergy between chemotherapy and alpha particles: effects in cells directly hit and in bystander cells

    International Nuclear Information System (INIS)

    Full text: Radioimmunotherapy with alpha-emitting nuclides offers the potential for selective targeting of micrometastatic sites. The short range of alpha particles and limited penetration of the labeled antibody into the tumor make it difficult to deliver a lethal dose to all tumor cells. In an effort to improve the extent and uniformity of tumor cell kill, experiments are underway to evaluate the ability of chemotherapy agents to produce synergistic effects in cells directly hit by alpha particles and in bystander cells. An alpha particle cell irradiation system comprised of planar americium-241 alpha particle sources together with custom-made cell culture dishes with replaceable mylar bottoms has been constructed and characterized. By changing the alpha particle source, the dose rate to cells on the mylar membrane can be varied from 0.0013 Gy/min to 13 Gy/min. The residual range of the alpha particles after exiting the mylar membrane is approximately 30 ∝/m. Preliminary results with alpha particle exposure in the presence or absence of low concentrations of either taxol or oxaliplatin show evidence of synergistic effects. A series of plastic grids have been designed and constructed that can be interposed between the alpha particle source and the cells to partially block the alpha particles. The ratio of open area to shielded area is kept constant at 50% but the diameter and total number of circular openings in the grid is varied, thus changing the proportion of bystander cells present close to the edge between the open and shielded zones. This approach creates a two-dimensional model system for micrometastatic tumors of various sizes where the shielded areas represent the deeper portions of a tumor beyond the range of surface-bound alpha particles. Experiments are underway to determine whether there are synergistic effects between the chemotherapy agents and the bystander cells

  12. Imaging alpha particle detector

    Science.gov (United States)

    Anderson, D.F.

    1980-10-29

    A method and apparatus for detecting and imaging alpha particles sources is described. A dielectric coated high voltage electrode and a tungsten wire grid constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source to be quantitatively or qualitatively analyzed. A thin polyester film window allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

  13. Studies on the biological effects of internal exposure of alpha emitters. Carcinogenicity test of plutonium

    International Nuclear Information System (INIS)

    Outlines of carcinogenicity tests in animals given with injected or inhaled plutonium (Pu) were described. Insoluble 239PuO2 particles were nasally inhaled in rats maintained for life. The dose response relationship between incidence of their lung tumor and absorbed radiation dose in the lung revealed that>1 Gy dose increased the incidence of malignant lung tumors, which differed from findings in the U.S. probably due to the difference between particle sizes. Further, a carcinogenic mechanism specific for alpha-ray was suggested based on tumor-related gene analysis. After soluble 239Pu (citrate salt) was injected in mice, significant reduction of lifetime and early tumor- or non-tumor-death were observed when the bone dose exceeded 3 Gy. Tumors were mostly osteosarcoma, lymphoma and other soft tissue solid cancers and were different from those induced by gamma-ray, X-ray and neutron irradiation. Studies on the strain difference, on the carcinogenic mechanism and alpha-ray induced mutation and transformation are in progress, which may lead to elucidation of the biological effects of internal exposure of alpha-emitters. (K.H.)

  14. The Effects of Alpha Particle Confinement on Burning Plasma Tokamak Performance

    Science.gov (United States)

    Gormley, Robert P.

    In this thesis, three effects of alpha particle plasma interactions on the global performance of a fusion reactor are studied, namely, (i) the energy coupling efficiency of the fast alpha particles with the bulk plasma, (ii) the relationship between imperfect alpha energy coupling to the bulk plasma and the resultant alpha particle/helium ash fuel dilution; and (iii) the neoclassical bootstrap current induced by fusion born alpha particles calculated self-consistently with the plasma equilibrium. First, the ion drift kinetic equation for the high energy alpha particles is reduced from the exact five dimensional form to a two dimensional form in radius r and energy E (plus time t). The resulting slowing-down diffusion equation is solved by a multiple energy group method. A theoretically based anomalous diffusion coefficient D_sp{alpha}{an} is then introduced from a self-consistent alpha particle Alfven wave turbulence solution (by F. Gang), in which D_sp{alpha}{an } itself depends on the gradient in alpha density. The temporal and spatial behavior of eta_ alpha is analyzed for an ITER-CDA physics phase fusion reactor. We find that eta_ alpha can be as low as 0.95 depending on the plasma operating temperature. Next, the relationship between the alpha-particle power coupling efficiency and the actual alpha-particle power that is coupled with the bulk plasma is investigated, this time taking into account the concomitant helium ash accumulation. It is found that the coupled power varies less than linearly with eta_alpha and is, in fact, significantly depressed for eta_alpha near unity. Combining these effects with a thermal power balance shows that the high temperature "thermally stable" side of the ignition boundary is pushed toward lower temperatures if either D_alpha increases (which results in a lower eta_alpha) or the helium-ash confinement time lengthens. This is a consequence of strengthened fuel dilution and imperfect alpha power coupling. Implications on the

  15. Alpha particle emitters in medicine

    International Nuclear Information System (INIS)

    Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 (211At) and natural bismuth-212 (212Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 (223Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs

  16. Alpha particle physics for ITER

    International Nuclear Information System (INIS)

    The paper is devoted to the analysis of a variety of physical processes which, in the ITER EDA configuration, determine the nature of alpha particle heating in the plasma interior and alpha particle losses to the first wall. The paper consists of results from the alpha particle toroidal field (TF) ripple loss calculations and an analysis of alpha particle collective effects including Alfven modes, sawtooth stabilization, etc. It is shown that the ripple loss in the present ITER configuration is only a few per cent, which cannot directly affect the achievement of ignition. In spite of the up-down asymmetry, the loss fraction does not strongly depend on the toroidal drift direction. However, the heat load is highly localized and can be as high as 1 MW/m2 on the top of the protective limiters. Preliminary calculations of toroidicity induced Alfven eigenmode (TAE) stability indicate that high n numbers may be unstable, but the computational tools, needed for reliable quantitative predictions, are still in a state of development. The likelihood of appreciable alpha particle loss will depend on whether TAE modes produce stochastic alpha particle diffusion or not. The effect of fast particles on the m = 1 mode is also discussed. (author). 15 refs, 2 figs, 1 tab

  17. Alpha particles in fusion research

    International Nuclear Information System (INIS)

    This collection of 39 (mostly view graph) presentations addresses various aspects of alpha particle physics in thermonuclear fusion research, including energy balance and alpha particle losses, transport, the influence of alpha particles on plasma stability, helium ash, the transition to and sustainment of a burning fusion plasma, as well as alpha particle diagnostics. Refs, figs and tabs

  18. Nanodosimetry of radon alpha particles

    International Nuclear Information System (INIS)

    It is currently accepted that energy deposition at the nanometer level (rather than conventional microdosimetry) determines the biological effects of ionizing radiation. Many previously established experimental techniques (e.g., the Rossi proportional counter) or theoretical methods (e.g., simplified calculations using the continuous slowing-down approximation (CSDA)) are inapplicable to the study of nanodosimetry. The peculiarities of the geometry of exposure to radon progeny further complicate the problem. This is because the conditions under which several open-quotes classicalclose quotes models of radiation action are obtained (e.g., the alpha-beta formulation of the Theory of Dual Radiation Action, which is built on microdosimetry) are no longer valid. It thus becomes clear that not only new techniques but new concepts are required to describe the effects of radon alpha particles. In this paper we discuss a number of computational aspects specific to radon nanodosimetry. In particular, we describe the novel concept of open-quotes associated surfaceclose quotes (AS) which is necessary for efficiently converting Monte-Carlo-generated particle tracks to nanodosimetric spectra. The AS is the analog of Lea's associated volume, applied to radiation sources subject to the geometrical restrictions of internal exposure. We systematically analyze factors affecting the nanodosimetry of radon progeny, such as the distance between the radioactive source and the sensitive volume, the size of the sensitive volume, and CSDA versus full Monte-Carlo track generation

  19. Nanodosimetry of radon alpha particles

    Energy Technology Data Exchange (ETDEWEB)

    Zaider, M. [Columbia Univ. New York, NY (United States); Varma, M.N. [U.S. Department of Energy, Washington, DC (United States)

    1992-12-31

    It is currently accepted that energy deposition at the nanometer level (rather than conventional microdosimetry) determines the biological effects of ionizing radiation. Many previously established experimental techniques (e.g., the Rossi proportional counter) or theoretical methods (e.g., simplified calculations using the continuous slowing-down approximation (CSDA)) are inapplicable to the study of nanodosimetry. The peculiarities of the geometry of exposure to radon progeny further complicate the problem. This is because the conditions under which several {open_quotes}classical{close_quotes} models of radiation action are obtained (e.g., the alpha-beta formulation of the Theory of Dual Radiation Action, which is built on microdosimetry) are no longer valid. It thus becomes clear that not only new techniques but new concepts are required to describe the effects of radon alpha particles. In this paper we discuss a number of computational aspects specific to radon nanodosimetry. In particular, we describe the novel concept of {open_quotes}associated surface{close_quotes} (AS) which is necessary for efficiently converting Monte-Carlo-generated particle tracks to nanodosimetric spectra. The AS is the analog of Lea`s associated volume, applied to radiation sources subject to the geometrical restrictions of internal exposure. We systematically analyze factors affecting the nanodosimetry of radon progeny, such as the distance between the radioactive source and the sensitive volume, the size of the sensitive volume, and CSDA versus full Monte-Carlo track generation.

  20. Alpha Particle Diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Ray, K.

    2009-05-13

    The study of burning plasmas is the next frontier in fusion energy research, and will be a major objective of the U.S. fusion program through U.S. collaboration with our international partners on the ITER Project. For DT magnetic fusion to be useful for energy production, it is essential that the energetic alpha particles produced by the fusion reactions be confined long enough to deposit a significant fraction of their initial ~3.5 MeV energy in the plasma before they are lost. Development of diagnostics to study the behavior of energetic confined alpha particles is a very important if not essential part of burning plasma research. Despite the clear need for these measurements, development of diagnostics to study confined the fast confined alphas to date has proven extremely difficult, and the available techniques remain for the most part unproven and with significant uncertainties. Research under this grant had the goal of developing diagnostics of fast confined alphas, primarily based on measurements of the neutron and ion tails resulting from alpha particle knock-on collisions with the plasma deuterium and tritium fuel ions. One of the strengths of this approach is the ability to measure the alphas in the hot plasma core where the interesting ignition physics will occur.

  1. Effects of alpha particle transport driven by Alfvenic instabilities on proposed burning plasma scenarios on ITER

    International Nuclear Information System (INIS)

    The consistency of proposed burning plasma scenarios with Alfvenic instabilities driven by alpha particles is investigated. If the alpha particle pressure is above the threshold for resonant excitation of Energetic Particle driven Modes (EPMs), significant modification of the alpha particle pressure profile can take place. Model simulations are performed using the Hybrid MHD-Gyrokinetic Code (HMGC) retaining relevant thermal-plasma parameters, safety factor and alpha particle pressure profiles. ITER monotonic-q and reversed-shear scenarios are considered. A 'hybrid' ITER scenario is also studied and quantitatively compared with the previous ones. We find that, unlike the latter, the former equilibria are unstable. Nonlinear effects on the alpha-particle pressure profile result, however, to be negligible for the monotonic-q case. They can instead be relevant for the reversed-shear scenario. The assessment of such a conclusion requires further investigations concerning the possibility that the strong EPM instability is regulated, in realistic conditions, by nonlinear effects of weaker Alfven modes. (author)

  2. Effect of alpha particles on the stability of Elmo Bumpy Torus (EBT) reactor. Final report

    International Nuclear Information System (INIS)

    The macroscopic stability of an ignited EBT reactor is investigated by studying the effects of the alpha particles generated by the Deuterium-Tritium (D-T) fusion reaction on the background interchange mode, the interacting interchange mode, and the high-frequency compressional Alfven and coupled modes. A fluid description is used for the background plasma while a kinetic treatment is utilized for the hot electron species and the alpha particles. It is shown that the alphas tend to mildly destabilize the interacting interchange while stabilizing the background interchange due to their sizable Larmor radii. The destabilization is most pronounced when the beta of the alpha particles in highest, i.e., at birth, and recovery of stabilization takes place as these particles slow down toward thermalization. It is also shown that the alphas completely stabilize the high frequency modes so that it can safely be concluded that fusion alphas present no detrimental effects on the stability of an EBT reactor that possesses an appropriate hot electron ring for macroscopic stability

  3. Effects of q(r) on the Alpha Particle Ripple Loss in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    D.S. Darrow; M. Diesso; R.V. Budny; S. Batha; S.J. Zweben; et al.

    1997-09-01

    An experiment was done with TFTR DT plasmas to determine the effect of the q(r) profile on the alpha particle ripple loss to the outer midplane. The alpha particle loss measurements were made using a radially movable scintillator detector 20 degrees below the outer midplane. The experimental results were compared with TF ripple loss calculations done using a Monte Carlo guiding center orbit following code, ORBIT. Although some of the experimental results are consistent with the ORBIT code modeling, the variation of the alpha loss with the q(r) profiles is not well explained by this code. Quantitative interpretation of these measurements requires a careful analysis of the limiter shadowing effect, which strongly determines the diffusion of alphas into the detector aperture.

  4. Effect of a biological activated carbon filter on particle counts

    Institute of Scientific and Technical Information of China (English)

    Su-hua WU; Bing-zhi DONG; Tie-jun QIAO; Jin-song ZHANG

    2008-01-01

    Due to the importance of biological safety in drinking water quality and the disadvantages which exist in traditional methods of detecting typical microorganisms such as Cryptosporidium and Giardia,it is necessary to develop an alternative.Particle counts is a qualitative measurement of the amount of dissolved solids in water.The removal rate of particle counts was previously used as an indicator of the effectiveness of a biological activated carbon(BAC)filter in removing Cryptosporidium and Giardia.The particle counts in a BAC filter effluent over one operational period and the effects of BAC filter construction and operational parameters were investigated with a 10 m3/h pilot plant.The results indicated that the maximum particle count in backwash remnant water was as high as 1296 count/ml and it needed about 1.5 h to reduce from the maximum to less than 50 count/ml.During the standard filtration period,particle counts stay constant at less than 50 count/ml for 5 d except when influ-enced by sand filter backwash remnant water.The removal rates of particle counts in the BAC filter are related to characteristics of the carbon.For example,a columned carbon and a sand bed removed 33.3% and 8.5% of particles,respectively,while the particle counts in effluent from a cracked BAC filter was higher than that of the influent.There is no significant difference among particle removal rates with different filtration rates.High post-ozone dosage(>2 mg/L)plays an important role in particle count removal;when the dosage was 3 mg/L,the removal rates by carbon layers and sand beds decreased by 17.5% and increased by 9.5%,respectively,compared with a 2 mg/L dosage.

  5. Energetic/alpha particle effects on MHD modes and transport

    International Nuclear Information System (INIS)

    A nonvariational kinetic-MHD stability code (NOVA-K) has been employed to study TAE stability in TFRR D-T and DIII-D experiments and to achieve understanding of TAE instability drive and damping mechanism. Reasonably good agreement between theory and experiment has been obtained. In these experiments the dominant damping mechanism is due to both the thermal ion Landau damping and/or the beam ion Landau damping. Based on ITER EDA parameters, the TAE modes are expected to be unstable in normal ITER operations. Energetic particle transport has been studied using a test particle code (ORBIT). Energetic particle loss scales linearly with the TAE mode amplitude and can be large for TFRR and DIII-D for δBr/B > 10-4 due to large banana orbit. From quasi-linear (ORBIT) and nonlinear kinetic-MHD (MH3D-K) simulations the saturation of TAE modes is due to nonlinear wave particle trapping and energetic particle profile modification in both radial and energy space. Finally, a convective bucket transport mechanism by MHD waves with time-dependent frequency is presented. Based on the energy-selective characteristics of the bucket transport mechanism, undesirable particles such as helium ash can be removed from the plasma core efficiently

  6. Alpha particle effects as a test domain for PAP, a Plasma Apprentice Program

    International Nuclear Information System (INIS)

    A new type of computational tool under development, employing techniques of symbolic computation and artificial intelligence to automate as far as possible the research activities of a human plasma theorist, is described. Its present and potential uses are illustrated using the area of the theory of alpha particle effects in fusion plasmas as a sample domain. (orig.)

  7. Alpha-particle diagnostics

    International Nuclear Information System (INIS)

    This paper will focus on the state of development of diagnostics which are expected to provide the information needed for α- physics studies in the future. Conventional measurement of detailed temporal and spatial profiles of background plasma properties in DT will be essential for such aspects as determining heating effectiveness, shaping of the plasma profiles and effects of MHD, but will not be addressed here. This paper will address (1) the measurement of the neutron source, and hence α-particle birth profile, (2) measurement of the escaping α-particles and (3) measurement of the confined α-particles over their full energy range. There will also be a brief discussion of (4) the concerns about instabilities being generated by α-particles and the methods necessary for measuring these effects. 51 refs., 10 figs

  8. Analysis of radiation risk from alpha particle component of soalr particle events

    Science.gov (United States)

    Cucinotta, F. A.; Townsend, L. W.; Wilson, J. W.; Golightly, M. J.; Weyland, M.

    1994-01-01

    The Solar Particle Events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and Linear Energy Transfer (LET) spectra in shielding are discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup.

  9. Analysis of radiation risk from alpha particle component of solar particle events

    Science.gov (United States)

    Cucinotta, F. A.; Townsend, L. W.; Wilson, J. W.; Golightly, M. J.; Weyland, M.

    1994-01-01

    The solar particle events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and linear energy transfer (LET) spectra in shielding discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup.

  10. Track-nanodosimetry of an alpha particle

    Energy Technology Data Exchange (ETDEWEB)

    De Nardo, L.; Tornielli, G. [Padova Univ., Padova (Italy); INFN, Padova (Italy); Cesari, V.; Colautti, P.; Conte, V. [INFN Laboratori Nazionali, Legnaro (Italy); Baek, W.Y.; Grosswendt, B. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Alkaa, A.; Segur, P. [Centre de Physique des Plasmas et de leur Applications, Toulouse (France)

    2002-07-01

    Effects of radiation are primarily determined by what happens in individual small volumes representative of DNA segments. Such sites are so small that the interactions due to radiation are very few and it is necessary to consider the stochastic of the number and nature of primary interactions and of secondary processes in order to understand the subsequent biological effects. Track-nanodosimetry has the objective to investigate stochastic aspect of energy deposition in particle tracks, by measuring the ionisation distributions induced by a charged particle in nanometric volumes of tissue-equivalent matter, positioned at different distances from the track. This paper is concerned with measurements and Monte Carlo calculations of ionisation distributions produced in a site of about 20 nm by a {sup 244}Cm alpha particle.

  11. Track-nanodosimetry of an alpha particle

    International Nuclear Information System (INIS)

    Effects of radiation are primarily determined by what happens in individual small volumes representative of DNA segments. Such sites are so small that the interactions due to radiation are very few and it is necessary to consider the stochastic of the number and nature of primary interactions and of secondary processes in order to understand the subsequent biological effects. Track-nanodosimetry has the objective to investigate stochastic aspect of energy deposition in particle tracks, by measuring the ionisation distributions induced by a charged particle in nanometric volumes of tissue-equivalent matter, positioned at different distances from the track. This paper is concerned with measurements and Monte Carlo calculations of ionisation distributions produced in a site of about 20 nm by a 244Cm alpha particle

  12. Prospects for alpha particle studies on TFTR

    International Nuclear Information System (INIS)

    TFTR is expected to produce approximately 5 MW of alpha heating during the D/T Q ≅ 1 phase of operation in 1990. At that point the collective confinement properties and the heating effects of alpha particles become accessible for study for the first time. This paper outlines the potential performance of TFTR with respect to alpha particle production, the diagnostics which will be available for alpha particle measurements, and the physics issues which can be studied both before and during D/T operation

  13. Alpha Particle Emission in Fission

    International Nuclear Information System (INIS)

    Soon after it was discovered that alpha particles are occasionally emitted in fission, it was concluded, on the basis of the energy and angular distributions of these particles, that they are emitted from the space between the fragments at times close to that of the snapping of the neck that connects them. It is shown that, independent of any (still unknown) dynamic features of the alpha-particle ejection process, the energy required to emit alpha particles from between the fragments at the indicated time is barely available. Presumably the rareness of alpha particles in fission, and the apparent absence of still heavier ''third'' particles, is associated with the marginal energy supply at the time of actual fragment division. The fact that the total kinetic energy release in so-called ternary fission is roughly equal to that in normal binary fission instead of being about 20 MeV larger is shown to imply that the mean fragment separation at the division time is larger in ternary fission. This is interpreted to indicate that alpha particles are emitted with greatest probability n those fissions where ample energy happens to be provided through the stretching of an abnormally long neck between the fragments before they actually divide. It is suggested that the release of the alpha particles is a sudden rather than adiabatic process. (author)

  14. The alpha channeling effect

    Energy Technology Data Exchange (ETDEWEB)

    Fisch, N. J.

    2015-12-10

    Alpha particles born through fusion reactions in a tokamak reactor tend to slow down on electrons, but that could take up to hundreds of milliseconds. Before that happens, the energy in these alpha particles can destabilize on collisionless timescales toroidal Alfven modes and other waves, in a way deleterious to energy confinement. However, it has been speculated that this energy might be instead be channeled into useful energy, so as to heat fuel ions or to drive current. Such a channeling needs to be catalyzed by waves Waves can produce diffusion in energy of the alpha particles in a way that is strictly coupled to diffusion in space. If these diffusion paths in energy-position space point from high energy in the center to low energy on the periphery, then alpha particles will be cooled while forced to the periphery. The energy from the alpha particles is absorbed by the wave. The amplified wave can then heat ions or drive current. This process or paradigm for extracting alpha particle energy collisionlessly has been called alpha channeling. While the effect is speculative, the upside potential for economical fusion is immense. The paradigm also operates more generally in other contexts of magnetically confined plasma.

  15. Relative Biological Effectiveness of HZE Particles for Chromosomal Exchanges and Other Surrogate Cancer Risk Endpoints

    OpenAIRE

    Cacao, Eliedonna; Hada, Megumi; Saganti, Premkumar B.; George, Kerry A.; Francis A Cucinotta

    2016-01-01

    The biological effects of high charge and energy (HZE) particle exposures are of interest in space radiation protection of astronauts and cosmonauts, and estimating secondary cancer risks for patients undergoing Hadron therapy for primary cancers. The large number of particles types and energies that makeup primary or secondary radiation in HZE particle exposures precludes tumor induction studies in animal models for all but a few particle types and energies, thus leading to the use of surrog...

  16. Wood smoke particle sequesters cell iron to impact a biological effect.

    Science.gov (United States)

    The biological effect of an inorganic particle (i.e., silica) can be associated with a disruption in cell iron homeostasis. Organic compounds included in particles originating from combustion processes can also complex sources of host cell iron to disrupt metal homeostasis. We te...

  17. Coulomb excitation effects on alpha-particle optical potential below the Coulomb barrier

    CERN Document Server

    Avrigeanu, V; Mănăilescu, C

    2016-01-01

    A competition of the low-energy Coulomb excitation (CE) with the compound nucleus (CN) formation in alpha-induced reactions below the Coulomb barrier has recently been assumed in order to make possible the description of the latter as well as the alpha-particle emission by the same optical model (OM) potential. On the contrary, we show in the present work that the corresponding partial waves and integration radii provide evidence for the distinct account of the CE cross section and OM total-reaction cross section $\\sigma_R$. Thus the largest contribution to CE cross section comes by far from partial waves larger than the ones contributing to the $\\sigma_R$ values.

  18. Effect of Alpha-Particle Energies on CR-39 Line-Shape Parameters using Positron Annihilation Technique

    Directory of Open Access Journals (Sweden)

    Lotfy Y. A.

    2006-07-01

    Full Text Available Polyally diglycol carbonate "CR-39" is widely used as etched track type particle detector. Doppler broadening positron annihilation (DBPAT provides direct information about core and valance electrons in (CR-39 due to radiation effects. It provides a non-destructive and non-interfering probe having a detecting efficiency. This paper reports the effect of irradiation alpha-particle intensity emitted from 241-Am (5.486 MeV source on the line shape S- and W-parameters for CR-39 samples. Modification of the CR-39 samples due to irradiation were studied using X-ray diffraction (XRD and scanning electron microscopy (SEM techniques.

  19. Alpha particles diffusion due to charge changes

    Energy Technology Data Exchange (ETDEWEB)

    Clauser, C. F., E-mail: cesar.clauser@ib.edu.ar; Farengo, R. [Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 Bariloche (Argentina)

    2015-12-15

    Alpha particles diffusion due to charge changes in a magnetized plasma is studied. Analytical calculations and numerical simulations are employed to show that this process can be very important in the pedestal-edge-SOL regions. This is the first study that presents clear evidence of the importance of atomic processes on the diffusion of alpha particles. A simple 1D model that includes inelastic collisions with plasma species, “cold” neutrals, and partially ionized species was employed. The code, which follows the exact particle orbits and includes the effect of inelastic collisions via a Monte Carlo type random process, runs on a graphic processor unit (GPU). The analytical and numerical results show excellent agreement when a uniform background (plasma and cold species) is assumed. The simulations also show that the gradients in the density of the plasma and cold species, which are large and opposite in the edge region, produce an inward flux of alpha particles. Calculations of the alpha particles flux reaching the walls or divertor plates should include these processes.

  20. Alpha-particle effects on high-n instabilities in tokamaks

    International Nuclear Information System (INIS)

    Hot α-particles and thermalized helium ash particles in tokamaks can have significant effects on high toroidal mode number instabilities such as the trapped-electron drift mode and the kinetically calculated magnetohydrodynamic ballooning mode. In particular, the effects can be stabilizing, destabilizing, or negligible, depending on the parameters involved. In high-temperature tokamaks capable of producing significant numbers of hot α-particles, the predominant interaction of the mode with the α-particles is through resonances of various sorts. In turn, the modes can cause significant anomalous transport of the α-particles and the helium ash. Here, results of comprehensive linear eigenfrequency-eigenfunction calculations are presented for relevant realistic cases to show these effects. 24 refs., 12 figs., 6 tabs

  1. Optics of Biological Particles

    CERN Document Server

    Hoekstra, Alfons; Videen, Gorden

    2007-01-01

    This book covers the optics of single biological particles, both theory and experiment, with emphasis on Elastic Light Scattering and Fluorescence. It deals with the optics of bacteria (bio-aerosols), marine particles (selected phytoplankton communities) and red and white blood cells. Moreover, there are dedicated chapters on a general theory for scattering by a cell, and modelling and simulation of scattering by inhomogeneous biological cells. Finally, one chapter is dedicated to astro-biological signatures, discussing the possibilities for detecting non-terrestrial biological material. The volume has up-to-date discussions on new experimental and numerical techniques, and many examples of applications of these techniques in real-life systems, as used to detect and characterize e.g. biological warfare agents or human blood cells.

  2. Physico-chemical properties and biological effects of diesel and biomass particles.

    Science.gov (United States)

    Longhin, Eleonora; Gualtieri, Maurizio; Capasso, Laura; Bengalli, Rossella; Mollerup, Steen; Holme, Jørn A; Øvrevik, Johan; Casadei, Simone; Di Benedetto, Cristiano; Parenti, Paolo; Camatini, Marina

    2016-08-01

    Diesel combustion and solid biomass burning are the major sources of ultrafine particles (UFP) in urbanized areas. Cardiovascular and pulmonary diseases, including lung cancer, are possible outcomes of combustion particles exposure, but differences in particles properties seem to influence their biological effects. Here the physico-chemical properties and biological effects of diesel and biomass particles, produced under controlled laboratory conditions, have been characterized. Diesel UFP were sampled from a Euro 4 light duty vehicle without DPF fuelled by commercial diesel and run over a chassis dyno. Biomass UFP were collected from a modern automatic 25 kW boiler propelled by prime quality spruce pellet. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of both diesel and biomass samples showed aggregates of soot particles, but in biomass samples ash particles were also present. Chemical characterization showed that metals and PAHs total content was higher in diesel samples compared to biomass ones. Human bronchial epithelial (HBEC3) cells were exposed to particles for up to 2 weeks. Changes in the expression of genes involved in xenobiotic metabolism were observed after exposure to both UFP already after 24 h. However, only diesel particles modulated the expression of genes involved in inflammation, oxidative stress and epithelial-to-mesenchymal transition (EMT), increased the release of inflammatory mediators and caused phenotypical alterations, mostly after two weeks of exposure. These results show that diesel UFP affected cellular processes involved in lung and cardiovascular diseases and cancer. Biomass particles exerted low biological activity compared to diesel UFP. This evidence emphasizes that the study of different emission sources contribution to ambient PM toxicity may have a fundamental role in the development of more effective strategies for air quality improvement. PMID:27194366

  3. Alpha particle problems in shielded support systems

    International Nuclear Information System (INIS)

    Alpha particle confinement is considered in the case of internal conductor systems with magnetically shielded supports. The treatment includes problems of energy transfer to the background plasma, the balance between radiation losses and alpha particle heating, mirror confinement in the main poloidal field, the cut-off and shielding conditions at the supports, ambipolar electric fields, wall interaction, and support location. With a proper and technically realizable choice of parameter values, it should become possible to achieve alpha particle heating as well as to manage the reactor technological problems due to alpha particle interaction with the supports. (Auth.)

  4. Alpha particle effects in burning tokamak plasmas: overview and specific examples

    International Nuclear Information System (INIS)

    Using the total power balance of an ignited tokamak plasma as a guideline, a range of alpha driven effects is surveyed regarding their impact on achieving and maintaining fusion burn. Specific examples of MHD and kinetic modes and multi species transport dynamics are discussed, including the possible interaction of these categories of effects. This power balance approach rather than a straightforward enumeration of possible effects serves to reveal their non-linear dependence and the ensuing fragility of our understanding of the approach to and maintenance of ignition. Specific examples are given of the interaction between α-power driven sawtoothing and ideal MHD stability, and direct α-effects on MHD modes including kinetic corrections. Anomalous ion heat transport and central impurity peaking mechanisms and anomalous and collisional α-transport including the ambipolar electric field are discussed

  5. Alpha particles detection in nitrocellulose

    International Nuclear Information System (INIS)

    The method for the manufacturing of the detection films follows these steps: preparation of the mass which includes nitrocellulose in the form of cotton as raw material ethyl acetate, cellosolve acetate, isopropyl and butyl alcohols as solvents and dioctyl phtalate as plasticiser; dilution of the paste; pouring of the diluted mass; and drying of the detection films. The results obtained experimentally are: The determination of the development times of the different thicknesses of the manufactured films. Response linearity of the detectors, variation of the number of tracks according to the distance of the source to the detector. Sizes of the diameter of the tracks depending of the distance detector-alpha emmission source. As a conclusion we can say the the nitrocellulose detectors are specific for alpha radiation; the more effective thicknesses in uranium prospecting works were those of 60 microns, since for the laboratory works the thicknesses of 30 to 40 microns were the ideal; the development technique of the detection films is simple and cheap and can be realized even in another place than the laboratory; this way of the manufacturing of nitrocellulose detection film sensitive to alpha nuclear radiation is open to future research. (author)

  6. Effects of complex symmetry-breakings on alpha particle power loads on first wall structures and equilibrium in ITER

    International Nuclear Information System (INIS)

    Within the ITPA Topical Group on Energetic Particles, we have investigated the impact that various mechanisms breaking the tokamak axisymmetry can have on the fusion alpha particle confinement in ITER as well as on the wall power loads due to these alphas. In addition to the well-known TF ripple, the 3D effect due to ferromagnetic materials (in ferritic inserts and test blanket modules) and ELM mitigation coils are included in these mechanisms. ITER scenario 4 was chosen since, due to its lower plasma current, it is more vulnerable for various off-normal features. First, the validity of using a 2D equilibrium was investigated: a 3D equilibrium was reconstructed using the VMEC code, and it was verified that no 3D equilibrium reconstruction is needed but it is sufficient to add the vacuum field perturbations onto an axisymmetric equilibrium. Then the alpha particle confinement was studied using three independent codes, ASCOT, DELTA5D and F3D OFMC, all of which assume MHD quiescent background plasma and no anomalous diffusion. All the codes gave a loss power fraction of about 0.2%. The distribution of the peak power load was found to depend on the first wall shape. We also made the first attempt to accommodate the effect of fast-ion-related MHD on the wall loads in ITER using the HMGC and ASCOT codes. The power flux to the wall was found to increase due to the redistribution of fast ions by the MHD activity. Furthermore, the effect of the ELM mitigation field on the fast-ion confinement was addressed by simulating NBI ions with the F3D OFMC code. The loss power fraction of NBI ions was found to increase from 0.3% without the ELM mitigation field to 4-5% with the ELM mitigation field.

  7. Effects of Complex Symmetry-Breakings on Alpha Particle Power Loads on First Wall Structures and Equilibrium in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Shinohara, K. [Japan Atomic Energy Agency (JAEA), Naka; Kurki-Suonio, T. [Aalto University, Finland; Spong, Donald A [ORNL; Asunta, O. [Aalto University, Finland; Tani, K. [Japan Atomic Energy Agency (JAEA), Naka; Strumberger, E. [Max Planck Institute for Plasma Physics, Garching, Germany; Briguglio, S. [EURATOM / ENEA, Italy; Koskela, T. [Aalto University, Finland; Vlad, G. [EURATOM / ENEA, Italy; Günter, S. [Max-Planck Institute, Garching, Germany; Kramer, G. [Princeton Plasma Physics Laboratory (PPPL); Putvinski, S. [ITER Organization, Cadarache, France; Hamamatsu, K. [Japan Atomic Energy Agency (JAEA), Naka

    2011-01-01

    Within the ITPA Topical Group on Energetic Particles, we have investigated the impact that various mechanisms breaking the tokamak axisymmetry can have on the fusion alpha particle confinement in ITER as well as on the wall power loads due to these alphas. In addition to the well-known TF ripple, the 3D effect due to ferromagnetic materials (in ferritic inserts and test blanket modules) and ELM mitigation coils are included in these mechanisms. ITER scenario 4 was chosen since, due to its lower plasma current, it is more vulnerable for various off-normal features. First, the validity of using a 2D equilibrium was investigated: a 3D equilibrium was reconstructed using the VMEC code, and it was verified that no 3D equilibrium reconstruction is needed but it is sufficient to add the vacuum field perturbations onto an axisymmetric equilibrium. Then the alpha particle confinement was studied using three independent codes, ASCOT, DELTA5D and F3D OFMC, all of which assume MHD quiescent background plasma and no anomalous diffusion. All the codes gave a loss power fraction of about 0.2%. The distribution of the peak power load was found to depend on the first wall shape. We also made the first attempt to accommodate the effect of fast-ion-related MHD on the wall loads in ITER using the HMGC and ASCOT codes. The power flux to the wall was found to increase due to the redistribution of fast ions by the MHD activity. Furthermore, the effect of the ELM mitigation field on the fast-ion confinement was addressed by simulating NBI ions with the F3D OFMC code. The loss power fraction of NBI ions was found to increase from 0.3% without the ELM mitigation field to 4-5% with the ELM mitigation field.

  8. The induction of bystander mutagenic effects in vivo by alpha-particle irradiation in whole Arabidopsis thaliana plants.

    Science.gov (United States)

    Li, Fanghua; Liu, Ping; Wang, Ting; Bian, Po; Wu, Yuejin; Wu, Lijun; Yu, Zengliang

    2010-08-01

    Our previous studies demonstrated distant/abscopal bystander effects in A. thaliana seeds and embryos; the postembryonic development of bystander tissues, such as root hair differentiation, primary root elongation, lateral root initiation and survival, were inhibited significantly by localized irradiation with microbeam protons and low-energy ions. In the present study, we further investigated radiation-induced bystander mutagenic effects in vivo in A. thaliana plants using homologous recombination (HR) and the expression level of the HR-related AtRAD54 gene as mutagenic end points. We found that alpha-particle irradiation of distal primary roots of young seedlings resulted in a significant increase in the frequency of HR in the aerial plants; the increased induction of HR occurred in every true leaf over the course of rosette development. Moreover, we also found that localized alpha-particle irradiation of roots induced a short-term up-regulated expression of the HR-related AtRAD54 gene in the nonirradiated aerial plants. These results suggested the existence of bystander mutagenic effects in vivo in plants. Treatment with the ROS scavenger DMSO dramatically reduced the effects of localized root irradiation on the induction of HR and expression of the AtRAD54 gene in bystander tissues, suggesting that ROS play a critical role in mediating the bystander mutagenic effects in plants. PMID:20681789

  9. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles

    Energy Technology Data Exchange (ETDEWEB)

    Zaider, M.

    1992-01-01

    We report on a theory for describing the biological effects of ionizing radiation in particular radon [alpha] particles. Behind this approach is the recognition that biological effects such as chromosome aberrations, cellular transformation, cellular inactivation, etc, are the result of a hierarchic sequence of radiation effects. We indicate how to treat each of the individual processes in this sequence, and also how to relate one effect to the hierarchically superior one.

  10. Effects of spins and resonance parities of 12C on the mechanism of emission of three alpha particles in the 11B (p, 3 α) reaction

    International Nuclear Information System (INIS)

    This research thesis reports the study of the mechanism of emission of alpha particles in the 11B (p, 3 α) reaction with respect to the effects of spins and parities of the various resonances met between 150 keV and 4 MeV. From an experimental point of view, the reaction has been studied by two methods: the detection of alpha particles by a semiconductor-based counter located at a given angle with respect to the beam direction and study of continuous spectra of alpha particles with respect to projectile energies, and recording, for a given resonance, of alpha-alpha coincidences by using the multi-parametric technique with two semiconductor-based sensors with a varying relative angular position. After a discussion of the main characteristics of resonance and of the mechanism of emission of alpha particles, the author first reports the theoretical study of a reaction producing three particles in the final state, and then reports the theoretical calculation of direct alpha spectrum shapes in the case of the 11B (p, 3 α) reaction (statistic hypothesis, hypothesis of interaction with two particles in the final state). The next part reports the experimental study of the 11B (p, 3 α) reaction

  11. Relative Biological Effectiveness of HZE Particles for Chromosomal Exchanges and Other Surrogate Cancer Risk Endpoints.

    Science.gov (United States)

    Cacao, Eliedonna; Hada, Megumi; Saganti, Premkumar B; George, Kerry A; Cucinotta, Francis A

    2016-01-01

    The biological effects of high charge and energy (HZE) particle exposures are of interest in space radiation protection of astronauts and cosmonauts, and estimating secondary cancer risks for patients undergoing Hadron therapy for primary cancers. The large number of particles types and energies that makeup primary or secondary radiation in HZE particle exposures precludes tumor induction studies in animal models for all but a few particle types and energies, thus leading to the use of surrogate endpoints to investigate the details of the radiation quality dependence of relative biological effectiveness (RBE) factors. In this report we make detailed RBE predictions of the charge number and energy dependence of RBE's using a parametric track structure model to represent experimental results for the low dose response for chromosomal exchanges in normal human lymphocyte and fibroblast cells with comparison to published data for neoplastic transformation and gene mutation. RBE's are evaluated against acute doses of γ-rays for doses near 1 Gy. Models that assume linear or non-targeted effects at low dose are considered. Modest values of RBE (10) are predicted at low doses <0.1 Gy. The radiation quality dependence of RBE's against the effects of acute doses γ-rays found for neoplastic transformation and gene mutation studies are similar to those found for simple exchanges if a linear response is assumed at low HZE particle doses. Comparisons of the resulting model parameters to those used in the NASA radiation quality factor function are discussed. PMID:27111667

  12. Relative Biological Effectiveness of HZE Particles for Chromosomal Exchanges and Other Surrogate Cancer Risk Endpoints

    Science.gov (United States)

    Cacao, Eliedonna; Hada, Megumi; Saganti, Premkumar B.; George, Kerry A.; Cucinotta, Francis A.

    2016-01-01

    The biological effects of high charge and energy (HZE) particle exposures are of interest in space radiation protection of astronauts and cosmonauts, and estimating secondary cancer risks for patients undergoing Hadron therapy for primary cancers. The large number of particles types and energies that makeup primary or secondary radiation in HZE particle exposures precludes tumor induction studies in animal models for all but a few particle types and energies, thus leading to the use of surrogate endpoints to investigate the details of the radiation quality dependence of relative biological effectiveness (RBE) factors. In this report we make detailed RBE predictions of the charge number and energy dependence of RBE’s using a parametric track structure model to represent experimental results for the low dose response for chromosomal exchanges in normal human lymphocyte and fibroblast cells with comparison to published data for neoplastic transformation and gene mutation. RBE’s are evaluated against acute doses of γ-rays for doses near 1 Gy. Models that assume linear or non-targeted effects at low dose are considered. Modest values of RBE (10) are predicted at low doses <0.1 Gy. The radiation quality dependence of RBE’s against the effects of acute doses γ-rays found for neoplastic transformation and gene mutation studies are similar to those found for simple exchanges if a linear response is assumed at low HZE particle doses. Comparisons of the resulting model parameters to those used in the NASA radiation quality factor function are discussed. PMID:27111667

  13. Relative Biological Effectiveness of HZE Particles for Chromosomal Exchanges and Other Surrogate Cancer Risk Endpoints.

    Directory of Open Access Journals (Sweden)

    Eliedonna Cacao

    Full Text Available The biological effects of high charge and energy (HZE particle exposures are of interest in space radiation protection of astronauts and cosmonauts, and estimating secondary cancer risks for patients undergoing Hadron therapy for primary cancers. The large number of particles types and energies that makeup primary or secondary radiation in HZE particle exposures precludes tumor induction studies in animal models for all but a few particle types and energies, thus leading to the use of surrogate endpoints to investigate the details of the radiation quality dependence of relative biological effectiveness (RBE factors. In this report we make detailed RBE predictions of the charge number and energy dependence of RBE's using a parametric track structure model to represent experimental results for the low dose response for chromosomal exchanges in normal human lymphocyte and fibroblast cells with comparison to published data for neoplastic transformation and gene mutation. RBE's are evaluated against acute doses of γ-rays for doses near 1 Gy. Models that assume linear or non-targeted effects at low dose are considered. Modest values of RBE (10 are predicted at low doses <0.1 Gy. The radiation quality dependence of RBE's against the effects of acute doses γ-rays found for neoplastic transformation and gene mutation studies are similar to those found for simple exchanges if a linear response is assumed at low HZE particle doses. Comparisons of the resulting model parameters to those used in the NASA radiation quality factor function are discussed.

  14. Alpha particle confinement in tandem mirrors

    International Nuclear Information System (INIS)

    Mechanisms leading to loss of alpha particles from non-axisymmetric tandem mirrors are considered. Stochastic diffusion due to bounce-drift resonances, which can cause rapid radial losses of high-energy alpha particles, can be suppressed by imposing a 20% rise in axisymmetric fields before the quadrupole transition sections. Alpha particles should then be well-confined until thermal energies when they enter the resonant plateau require. A fast code for computation of drift behavior in reactors is described. Sample calculations are presented for resonant particles in a proposed coil set for the Tandem Mirror Next Step

  15. 3D Effect of Ferromagnetic Materials on Alpha Particle Power Loads on First Wall Structures and Equilibrium on ITER

    International Nuclear Information System (INIS)

    Full text: The finite number and limited toroidal extent of the TF coils cause a periodic variation of the toroidal field called the magnetic ripple. This ripple can provide a significant channel for fast particle leakage, leading to very localized fast particle loads on the walls. Ferromagnetic inserts will be embedded in the double wall structure of the vacuum vessel in order to reduce the ripple. In ITER the toroidal field deviations are locally further enhanced by the presence of discrete ferromagnetic structures, e.g. TBM. Thus, there are complex symmetry-breaking effects. It is not yet fully understood how superimposing the periodic ripple and a local perturbation affect the fast ion confinement and concerns have been voiced that the combined effect might lead to significant channelling of the alpha power. In this work, the wall power loads due to fusion-born alpha particles were restudied for a variety of cases addressing issues such as different wall configurations, proper inclusion of the TBM effect on the magnetic background, and the possible corrections to 3D equilibrium introduced by the ferromagnetic materials using the 3D equilibrium code, VMEC, since 3D corrections to the equilibrium might enhance the alpha particle loss. To properly include the TBM effect on the magnetic background, the FEMAG code was used, and the effect was calculated on the total field including the poloidal field by the plasma current as well as the vacuum field. In the VMEC analysis, it was found that the difference between a full 3D equilibrium reconstruction and 'an axisymmetric equilibrium + vacuum fields' was small. Thus, it was concluded that no 3D equilibrium reconstruction was needed and that it was sufficient to add the vacuum field perturbations onto an axisymmetric equilibrium. Under the new boundary condition, the wall load calculation was carried out by using ASCOT, DELTA5D, and F3D OFMC code. Including the plasma current contribution in the magnetic field

  16. The alpha-particle irradiator set up at the ISS for radiobiological studies on targeted and non-targeted effects

    International Nuclear Information System (INIS)

    In this paper we describe the alpha-particle irradiator that has been set up at the Istituto Superiore di Sanita (ISS) for controlled exposure of cultured mammalian cells. It can be equipped with two different sources, namely 2'4'4'Cm and 2'4'1'Am, allowing irradiation at different dose-rates (typically 1-100 mGy/min). The irradiator has dimensions small enough to be inserted into a standard cell culture incubator to perform irradiation of cultured cells in physiological conditions. The dose uniformity is such that the variations in the irradiation area are less than ± 12% of the average dose value on different irradiation areas up to ∼ 25 cm'2. Moreover, in the framework of the FP6 Euratom Integrated Project Non-targeted effects of ionizing radiation (NOTE), Petri dishes were realized for housing permeable membrane insert(s) to be used in co-culture experiments. Aluminium shields were also realized for half shield irradiation experiments. The alpha-particle irradiator of the ISS has been successfully used for studying DNA damage, namely double strand breaks (DSB, as measured by the γ-H2AX assay), in directly hit and in bystander primary human fibroblasts

  17. High resolution alpha particle spectrometry through collimation

    International Nuclear Information System (INIS)

    Alpha particle spectrometry with collimation is a useful method for identifying nuclear materials among various nuclides. A mesh type collimator reduces the low energy tail and broadened energy distribution by cutting off particles with a low incidence angle. The relation between the resolution and the counting efficiency can be investigated by changing a ratio of the mesh hole diameter and the collimator thickness. Through collimation, a target particle can be distinguished by a PIPS® detector under a mixture of various nuclides. - Highlights: • Alpha particle spectrometry with collimation a useful method for identifying nuclear materials among various radionuclides. • A collimator cut off alpha particles with low angle emitted from a source. • We confirm that that a collimator improves the resolution of alpha spectra through both simulation and experiments

  18. Chromosomal aberrations induced by alpha particles

    International Nuclear Information System (INIS)

    The chromosomal aberrations produced by the ionizing radiation are commonly used when it is necessary to establish the exposure dose of an individual, it is a study that is used like complement of the traditional physical systems and its application is only in cases in that there is doubt about what indicates the conventional dosimetry. The biological dosimetry is based on the frequency of aberrations in the chromosomes of the lymphocytes of the individual in study and the dose is calculated taking like reference to the dose-response curves previously generated In vitro. A case of apparent over-exposure to alpha particles to which is practiced analysis of chromosomal aberrations to settle down if in fact there was exposure and as much as possible, to determine the presumed dose is presented. (Author)

  19. Alpha-particles microbeam irradiation: impact of reactive oxygen species in bystander effect

    International Nuclear Information System (INIS)

    Ionizing radiation-induced bystander effects arise in bystander cells that receive signals from directly irradiated cells. To date, free radicals are believed to play an active role in the bystander response, but this is incompletely characterized. To mark temporal and spatial impacts of bystander effect, we employed a precise α-particle microbeam to target a small fraction of sub-confluent osteoblastic cell cultures (MC3T3-E1). We identified the cellular membrane and mitochondria like two distinct places generating reactive oxygen species. The global oxidative stress observed after irradiation was significantly attenuated after filipin treatment, evidencing the pivotal role of membrane in MC3T3-E1 cells bystander response. To determine impact of bystander effect at a cell level, cellular consequences of this membrane-dependant bystander effect were then investigated. A variable fraction of the cell population (10 to 100%) was individually targeted. In this case, mitotic death and micronuclei yield both increased in bystander cells as well as in targeted cells demonstrating a role of bystander signals between irradiated cells in an autocrine or paracrine manner. Our results indicate a complex interaction of direct irradiation and bystander signals that lead to a membrane-dependant amplification of cell responses. (author)

  20. Detection of alpha particles with undoped poly (ethylene naphthalate)

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Hidehito, E-mail: hidehito@rri.kyoto-u.ac.jp [Kyoto University, 2, Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555 (Japan); Shirakawa, Yoshiyuki; Kitamura, Hisashi [National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555 (Japan); Sato, Nobuhiro; Takahashi, Sentaro [Kyoto University, 2, Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2014-03-01

    There has been recent interest in the use of undoped, aromatic-ring polymers as organic scintillation materials for radiation detectors. Here, we characterise the response of poly (ethylene naphthalate) (PEN) to alpha particles. The energy response to 5486 keV alpha particles emitted from {sup 241}Am was 554±45 keV electron equivalents (keVee), with an energy resolution of 11.2±0.1%. The energy response to 6118 keV alpha particles emitted from {sup 252}Cf was 618±45 keVee, with a resolution of 8.8±0.1%. It is also important to characterise the refractive index because it determines how efficiently light propagates in scintillation materials to the photodetector. By taking into account the PEN emission spectrum, it was revealed that its effective refractive index was 1.70. Overall, the results indicate that PEN has potential as a scintillation material for the detection of alpha particles. - Highlights: • PEN is characterised as a scintillation material for alpha particles. • The effective refractive index for PEN is 1.70 in its emission spectrum. • The response to 5486 (6118) keV alpha particles was 554±45 (618±45) keVee. • The energy resolution for 5486 (6118) keV alpha particles was 11.2±0.1 (8.8±0.1) %. • This work will stimulate future use of PEN for radiation detection.

  1. Alpha emitters in Chernobyl hot particles

    International Nuclear Information System (INIS)

    The alpha radioactive component of hot particles from the Chernobyl fallout was analysed for cases studied previously by gamma spectroscopy. Correlations established from the absolute alpha activity determination and high resolution analysis provided information on actinides release during accident and on some aspects of the Chernobyl reactor fuel composition. Unexpected features revealed during the analysis of one specific particle are presented. 11 refs., 5 figs., 5 tabs. (author)

  2. Alpha emitters in Chernobyl hot particles

    Energy Technology Data Exchange (ETDEWEB)

    Broda, R.; Kubica, B.; Szeglowski, Z.; Zuber, K. (Institute of Nuclear Physics, Krakow (Poland))

    1989-01-01

    The alpha radioactive component of hot particles from the Chernobyl fallout was analyzed for cases studied previously by gamma spectroscopy. Correlations established from the absolute alpha activity determination and high resolution analysis provided information on the release of actinides during the accident and on some aspects of the Chernobyl reactor fuel composition. Unexpected features revealed during the analysis of one specific particle are presented. (orig.).

  3. Characterization and biological effect of Buenos Aires urban air particles on mice lungs

    International Nuclear Information System (INIS)

    Exposure to increased levels of ambient air particulate matter (PM) is associated with increased cardiopulmonary morbidity and mortality. Its association with adverse health effects and the still unclear mechanisms of action are of concern worldwide. Our objective was to analyze air PM from downtown Buenos Aires (UAP-BA), and evaluate its biological impact on normal airways. We studied the inflammatory response to intranasal instillation of UAP-BA in a short-term-exposure mouse model. We analyzed UAP-BA morphology by scanning electron microscopy and characterized particle chemical composition by energy dispersive X-ray analysis and capillary gas chromatography. We evaluated lung changes by histomorphometry and histochemical methods. Regarding size, surface area and distribution, UAP-BA proved to be small spherical ultrafine particles: free, in clusters and associated to a matrix. The particles contained polycyclic aromatic hydrocarbons, polychlorinated biphenyls and almost no metal traces. Histologically, UAP-BA induced the recruitment of phagocytes, a reduction in air spaces, an increase in mucous PAS positive cells and weak incomplete elastic fiber network. Our results demonstrate that UAP-BA causes adverse biological effects on the respiratory tract generating inflammation that, in turn, may cause tissue injury or organ dysfunction and may contribute to the pathogenesis of lung diseases

  4. ON THE RELATIVE SPEED AND TEMPERATURE RATIO OF SOLAR WIND ALPHA PARTICLES AND PROTONS: COLLISIONS VERSUS WAVE EFFECTS

    International Nuclear Information System (INIS)

    We study the relative flow speed and the temperature ratio of alpha particles and protons and their connections to the helium ion abundance, the collisional age, and the power of transverse fluctuations within the inertial range. It is found that the alpha-to-proton temperature ratio, Tα/Tp , anti-correlates with the helium ion abundance. Despite a relatively high collisional age and small wave power, the ratio Tα/Tp can reach comparatively high values (even above 2) whenever the helium ion abundance is below about 0.02. In contrast, the differential speed of alpha particles with respect to protons is correlated with the total wave power and anti-correlated with the collisional age. Ultimately, the individual heating of each ion species is positively correlated with the total wave power. Our findings suggest that a high-friction collision could be efficient in reducing the differential speed between alpha particles and protons, but appears not to be sufficient to equalize the alpha and proton temperatures, i.e., to make Tα ≅ Tp . This is a hint that the local wave heating process is acting on a timescale shorter than the collision time.

  5. Alpha particles spectrometer with photodiode PIN

    International Nuclear Information System (INIS)

    The radiation propagates in form of electromagnetic waves or corpuscular radiation; if the radiation energy causes ionization in environment that crosses it is considered ionizing radiation. To detect radiation several detectors types are used, if the radiation are alpha particles are used detectors proportional type or trace elements. In this work the design results, construction and tests of an alpha particles spectrometer are presented, which was designed starting from a photodiode PIN type. The system design was simulated with a code for electronic circuits. With results of simulation phase was constructed the electronic phase that is coupled to a multichannel analyzer. The resulting electronic is evaluated analyzing the electronic circuit performance before an alphas triple source and alpha radiation that produce two smoke detectors of domestic use. On the tests phase we find that the system allows obtain, in a multichannel, the pulses height spectrum, with which we calibrate the system. (Author)

  6. Alpha particle spectroscopy by gridded ionization chamber

    International Nuclear Information System (INIS)

    A gridded ionization chamber has been constructed with the aim of determining its ultimate energy resolution in alpha spectroscopy, utilizing a cooled FET pre-amplifier of the type normally employed with semiconductor detectors. With suitable mechanical collimation of the alpha particles, their fine structure has been measured with an energy resolution of -11.5 keV (fwhm), achieved using an Ar + 0.75% C2H2 mixture as the filling gas. (orig.)

  7. Study of the biological and clinical effects caused by neutron on charged-particle radiotherapy

    International Nuclear Information System (INIS)

    During the particle therapy, a lot of secondly particles are generated through nuclear reactions in a patient's body or irradiation devices. Because the neutron is distributed broadly and its relative biological effectiveness (RBE) is high, an evaluation of second cancer risk should be associated with neutrons. Therefore we studied the distribution of secondly neutrons in a human phantom by metal foil activation method and compared with the estimation of Monte Carlo code PHITS (Particle and Heavy Ion Transport code System). The experiment was performed at BIO beam port of the Heavy Ion Medical Accelerator in Chiba (HIMAC) in National Institute of Radiological Sciences (NIRS) with 400 MeV/u carbon beam. Al, Co, Fe and Bi foils were used in this study. The metal foils were placed in a human phantom. The yield of isotopes produced in the foil by the incidence of neutrons was measured by counting corresponding emitted gamma ray with a Ge detector. Activation rate was estimated with the experimental result and calculation by PHITS. Neutron distribution inside of the human phantom was measured by metal foil activation method and the result was compared with PHITS. Through the comparison it is found that estimation of neutron spectrum by PHITS reproduces experimental result around a several dozen MeV. (author)

  8. Alpha particles energy straggling in noble gases

    International Nuclear Information System (INIS)

    The comparison of the calculated spectra by the Monte-Carlo simulation with the experimental alpha-particles spectra after their passage through noble gases target has good agreement for Ar, Kr, and Xe and significant deviation for He and Ne. These agreement or disagreement of the calculated and experimental spectra were ascribed to adequacy or inadequacy of the applied Bohr's charged particles energy loss formula for the specific medium. (author)

  9. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles. Progress report, July 1990--June 1992

    Energy Technology Data Exchange (ETDEWEB)

    Zaider, M.

    1992-12-31

    We report on a theory for describing the biological effects of ionizing radiation in particular radon {alpha} particles. Behind this approach is the recognition that biological effects such as chromosome aberrations, cellular transformation, cellular inactivation, etc, are the result of a hierarchic sequence of radiation effects. We indicate how to treat each of the individual processes in this sequence, and also how to relate one effect to the hierarchically superior one.

  10. Superparamagnetic relaxation in alpha-Fe particles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Pedersen, Michael Stanley; Svedlindh, P.; Jonsson, G.T.; Garcia-Palacios, J.L.; Lazaro, F.J.

    1998-01-01

    The superparamagnetic relaxation time of carbon-supported alpha-Fe particles with an average size of 3.0 Mm has been studied over a large temperature range by the use of Mossbauer spectroscopy combined with AC and DC magnetization measurements. It is found that the relaxation time varies with...

  11. Effect of UV radiation on the bulk etching rate activation energy and response of Cr-39 to alpha particles

    International Nuclear Information System (INIS)

    A set of CR-39 plastic sheets is exposed to UV radiation from mercury lamp for different periods of time. Then irradiated by alpha particles from 241Am point source at different energies. The Bulk etching rate activation energy is calculated for non-exposed and exposed sheets for time periods of 1.5 and 3 hr. It is found that their energy values are 0.76, 0.75 and 0.72 eV respectively. The track diameter (d) is calculated for different exposure times, it is found that d increased gradually as the exposure time increases before saturation. Further, two samples are irradiated by alpha particles but one is pre-exposed to UV for a time period of 3 h before being exposed to alpha, then the response function (V) is calculated for both. The values of V decreased for pre-exposed sample. The present data are the first measurements of the recent nuclear track laboratory at the experimental nuclear physics department, NRC, AEA

  12. Discrimination of nuclear recoils from alpha particles with superheated liquids

    Energy Technology Data Exchange (ETDEWEB)

    Aubin, F; Auger, M; Genest, M-H; Giroux, G; Gornea, R; Faust, R; Leroy, C; Lessard, L; Martin, J-P; Morlat, T; Piro, M-C; Starinski, N; Zacek, V [Departement de Physique, Universite de Montreal, Montreal, H3C 3J7 (Canada); Beltran, B; Krauss, C B [Department of Physics, University of Alberta, Edmonton, T6G 2G7 (Canada); Behnke, E; Levine, I; Shepherd, T [Department of Physics and Astronomy, Indiana University South Bend, South Bend, IN 46634 (United States); Nadeau, P; Wichoski, U [Department of Physics, Laurentian University, Sudbury, P3E 2C6 (Canada)], E-mail: zacekv@lps.umontreal.ca (and others)

    2008-10-15

    The PICASSO collaboration observed for the first time a significant difference between the acoustic signals induced by neutrons and alpha particles in a detector based on superheated liquids. This new discovery offers the possibility of improved background suppression and could be especially useful for dark matter experiments. This new effect may be attributed to the formation of multiple bubbles on alpha tracks, compared to single nucleations created by neutron-induced recoils.

  13. A practical alpha particle irradiator for studying internal alpha particle exposure.

    Science.gov (United States)

    Lee, Ki-Man; Lee, Ui-Seob; Kim, Eun-Hee

    2016-09-01

    An alpha particle irradiator has been built in the Radiation Bioengineering Laboratory at Seoul National University (SNU) to investigate the cellular responses to alpha emissions from radon and the progeny. This irradiator is designed to have the energy of alpha particles entering target cells similar to that of alpha emissions from the radon progeny Po-218 and Po-214 residing in the human respiratory tract. For the SNU alpha particle irradiator, an irradiation system is equipped with cell dishes of 4µm thick Mylar bottom and a special setup of cells on slide for gamma-H2AX assay. Dose calibration for the alpha particle irradiator was performed by dual approaches, detection and computer simulation, in consideration of the source-to-target distance (STD) and the size of a cell dish. The uniformity of dose among cells in a dish is achieved by keeping the STD and the size of cell dish in certain ranges. The performance of the SNU alpha particle irradiator has been proven to be reliable through the gamma-H2AX assay with the human lung epithelial cells irradiated. PMID:27475622

  14. Method to detect biological particles

    International Nuclear Information System (INIS)

    A medical-diagnostic method to detect immunological as well as other specific reactions is described. According to the invention, first reactive particles (e.g. antibodies) are adsorbed on the surface of a solid, non-reactive substrate. The coated substrate is subjected to a solution which one assumes to contain the second biological particles (e.g. antigens) which are specific to the first and form complexes with these. A preferential radioactive labelling (e.g. with iodine 125) of the second biological particle is then directly or indirectly carried out. Clearage follows labelling in order to separate the second biological particles from the first ones. A specific splitting agent can selectively break the bond of both types of particle. The splitting agent solution is finally separated off and its content is investigated for the presence of labelling. (VJ)

  15. Alpha particle diagnostics using impurity pellet injection

    International Nuclear Information System (INIS)

    We have proposed using impurity injection to measure the energy distribution of the fast confined alpha particles in a reacting plasma. The ablation cloud surrounding the injected pellet is thick enough that an equilibrium fraction Fo∞(E) of the incident alphas should be neutralized as they pass through the cloud. By observing neutrals created in the large spatial region of the cloud which is expected to be dominated by the helium-like ionization state, e.g., Li+ ions, we can determine the incident alpha distribution dnHe2+/dE from the measured energy distribution of neutral helium atoms. Initial experiments were performed on TEXT in which we compared pellet penetration with our impurity pellet ablation model, and measured the spatial distribution of various ionization states in carbon pellet clouds. Experiments have recently begun on TFTR with the goal of measuring the alpha particle energy distribution during D-T operation in 1993--94. A series of preliminary experiments are planned to test the diagnostic concept. The first experiments will observe neutrals from beam-injected deuterium ions and the high energy 3He tail produced during ICH minority heating on TFTR interacting with the cloud. We will also monitor by line radiation the charge state distributions in lithium, boron, and carbon clouds

  16. Alpha Particle Emitter Radiolabeled Antibody for Metastatic Cancer: What Can We Learn from Heavy Ion Beam Radiobiology?

    Directory of Open Access Journals (Sweden)

    Hong Song

    2012-06-01

    Full Text Available Alpha-particle emitter labeled monoclonal antibodies are being actively developed for treatment of metastatic cancer due to the high linear energy transfer (LET and the resulting greater biological efficacy of alpha-emitters. Our knowledge of high LET particle radiobiology derives primarily from accelerated heavy ion beam studies. In heavy ion beam therapy of loco-regional tumors, the modulation of steep transition to very high LET peak as the particle approaches the end of its track (known as the Bragg peak enables greater delivery of biologically potent radiation to the deep seated tumors while sparing normal tissues surrounding the tumor with the relatively low LET track segment part of the heavy ion beam. Moreover, fractionation of the heavy ion beam can further enhance the peak-to-plateau relative biological effectiveness (RBE ratio. In contrast, internally delivered alpha particle radiopharmaceutical therapy lack the control of Bragg peak energy deposition and the dose rate is determined by the administered activity, alpha-emitter half-life and biological kinetics of the radiopharmaceutical. The therapeutic ratio of tumor to normal tissue is mainly achieved by tumor specific targeting of the carrier antibody. In this brief overview, we review the radiobiology of high LET radiations learned from ion beam studies and identify the features that are also applicable for the development of alpha-emitter labeled antibodies. The molecular mechanisms underlying DNA double strand break repair response to high LET radiation are also discussed.

  17. Intercomparison of alpha particle spectrometry software packages

    International Nuclear Information System (INIS)

    Software has reached an important level as the 'logical controller' at different levels, from a single instrument to an entire computer-controlled experiment. This is also the case for software packages in nuclear instruments and experiments. In particular, because of the range of applications of alpha-particle spectrometry, software packages in this field are often used. It is the aim of this intercomparison to test and describe the abilities of four such software packages. The main objectives of the intercomparison were the ability of the programs to determine the peak areas and the peak area uncertainties, and the statistical control and stability of reported results. In this report, the task, methods and results of the intercomparison are presented in order to asist the potential users of such software and to stimulate the development of even better alpha-particle spectrum analysis software

  18. Interaction of alpha particles at the cellular level - Implications for the radiation weighting factor

    International Nuclear Information System (INIS)

    Since low dose effects of alpha particles are produced by cellular hits in a relatively small fraction of exposed cells, the present study focuses on alpha particle interactions in bronchial epithelial cells following exposure to inhaled radon progeny. A computer code was developed for the calculation of microdosimetric spectra, dose and hit probabilities for alpha particles emitted from uniform and non-uniform source distributions in cylindrical and Y-shaped bronchial airway geometries. Activity accumulations at the dividing spur of bronchial airway bifurcations produce hot spots of cellular hits, indicating that a small fraction of cells located at such sites may receive substantially higher doses. While presently available data on in vitro transformation frequencies suggest that the relative biological effectiveness for alpha particles ranges from about 3 to 10, the effect of inhomogeneous activity distributions of radon progeny may slightly increase the radiation weighting factor relative to a uniform distribution. Thus a radiation weighting factor of about 10 may be more realistic than the current value of 20, at least for lung cancer risk following inhalation of short-lived radon progeny. (authors)

  19. Turbulent transport of alpha particles in tokamak plasmas

    CERN Document Server

    Croitoru, A; Vlad, M; Spineanu, F

    2016-01-01

    We investigate the ExB diffusion of fusion born \\alpha particles in tokamak plasmas. We determine the transport regimes for a realistic model that has the characteristics of the ion temperature gradient (ITG) or of the trapped electron modes (TEM) driven turbulence. It includes a spectrum of potential fluctuations that is modeled using the results of the numerical simulations, the drift of the potential with the effective diamagnetic velocity and the parallel motion. Our semi-analytical statistical approach is based on the decorrelation trajectory method (DTM), which is adapted to the gyrokinetic approximation. We obtain the transport coefficients as a function of the parameters of the turbulence and of the energy of the \\alpha particle. According to our results, signficant turbulent transport of the \\alpha particles can appear only at energies of the order of 100KeV. We determine the corresponding conditions.

  20. Biological effects in lung cells In vitro of exhaust aerosols from a gasoline passenger car with and without particle filter

    OpenAIRE

    Bisig, Christoph; Steiner, Sandro; Comte, Pierre; Czerwinski, Jan; Mayer, Andreas; Petri-Fink, Alke; Rothen-Rutishauser, Barbara

    2016-01-01

    Exhaust aerosol from gasoline passenger cars is a complex mixture of a particulate fraction as well as volatile compounds. In contrary to the observed adverse effects of diesel exhaust particles the gasoline exhaust has, however, received little attention so far. The aim of this study was to perform a comparison of exhaust composition and biological responses from freshly produced non-filtered exhaust as well as from exhaust filtered with a noncoated gasoline particle filter (GPF). A 3D model...

  1. Effects of Alpha Particle and Proton Beam Irradiation as Putative Cross-Talk between A549 Cancer Cells and the Endothelial Cells in a Co-Culture System

    Energy Technology Data Exchange (ETDEWEB)

    Riquier, Hélène; Abel, Denis [URBC-NARILIS, University of Namur, 61 rue de Bruxelles, Namur 5000 (Belgium); Wera, Anne-Catherine; Heuskin, Anne-Catherine [LARN-PMR, NARILIS, University of Namur, Namur 5000 (Belgium); Genard, Géraldine [URBC-NARILIS, University of Namur, 61 rue de Bruxelles, Namur 5000 (Belgium); Lucas, Stéphane [LARN-PMR, NARILIS, University of Namur, Namur 5000 (Belgium); Michiels, Carine, E-mail: carine.michiels@unamur.be [URBC-NARILIS, University of Namur, 61 rue de Bruxelles, Namur 5000 (Belgium)

    2015-03-18

    Background: High-LET ion irradiation is being more and more often used to control tumors in patients. Given that tumors are now considered as complex organs composed of multiple cell types that can influence radiosensitivity, we investigated the effects of proton and alpha particle irradiation on the possible radioprotective cross-talk between cancer and endothelial cells. Materials and Methods: We designed new irradiation chambers that allow co-culture study of cells irradiated with a particle beam. A549 lung carcinoma cells and endothelial cells (EC) were exposed to 1.5 Gy of proton beam or 1 and 2 Gy of alpha particles. Cell responses were studied by clonogenic assays and cell cycle was analyzed by flow cytometry. Gene expression studies were performed using Taqman low density array and by RT-qPCR. Results: A549 cells and EC displayed similar survival fraction and they had similar cell cycle distribution when irradiated alone or in co-culture. Both types of irradiation induced the overexpression of genes involved in cell growth, inflammation and angiogenesis. Conclusions: We set up new irradiation chamber in which two cell types were irradiated together with a particle beam. We could not show that tumor cells and endothelial cells were able to protect each other from particle irradiation. Gene expression changes were observed after particle irradiation that could suggest a possible radioprotective inter-cellular communication between the two cell types but further investigations are needed to confirm these results.

  2. Effects of Alpha Particle and Proton Beam Irradiation as Putative Cross-Talk between A549 Cancer Cells and the Endothelial Cells in a Co-Culture System

    International Nuclear Information System (INIS)

    Background: High-LET ion irradiation is being more and more often used to control tumors in patients. Given that tumors are now considered as complex organs composed of multiple cell types that can influence radiosensitivity, we investigated the effects of proton and alpha particle irradiation on the possible radioprotective cross-talk between cancer and endothelial cells. Materials and Methods: We designed new irradiation chambers that allow co-culture study of cells irradiated with a particle beam. A549 lung carcinoma cells and endothelial cells (EC) were exposed to 1.5 Gy of proton beam or 1 and 2 Gy of alpha particles. Cell responses were studied by clonogenic assays and cell cycle was analyzed by flow cytometry. Gene expression studies were performed using Taqman low density array and by RT-qPCR. Results: A549 cells and EC displayed similar survival fraction and they had similar cell cycle distribution when irradiated alone or in co-culture. Both types of irradiation induced the overexpression of genes involved in cell growth, inflammation and angiogenesis. Conclusions: We set up new irradiation chamber in which two cell types were irradiated together with a particle beam. We could not show that tumor cells and endothelial cells were able to protect each other from particle irradiation. Gene expression changes were observed after particle irradiation that could suggest a possible radioprotective inter-cellular communication between the two cell types but further investigations are needed to confirm these results

  3. Effects of Alpha Particle and Proton Beam Irradiation as Putative Cross-Talk between A549 Cancer Cells and the Endothelial Cells in a Co-Culture System

    Directory of Open Access Journals (Sweden)

    Hélène Riquier

    2015-03-01

    Full Text Available Background: High-LET ion irradiation is being more and more often used to control tumors in patients. Given that tumors are now considered as complex organs composed of multiple cell types that can influence radiosensitivity, we investigated the effects of proton and alpha particle irradiation on the possible radioprotective cross-talk between cancer and endothelial cells. Materials and Methods: We designed new irradiation chambers that allow co-culture study of cells irradiated with a particle beam. A549 lung carcinoma cells and endothelial cells (EC were exposed to 1.5 Gy of proton beam or 1 and 2 Gy of alpha particles. Cell responses were studied by clonogenic assays and cell cycle was analyzed by flow cytometry. Gene expression studies were performed using Taqman low density array and by RT-qPCR. Results: A549 cells and EC displayed similar survival fraction and they had similar cell cycle distribution when irradiated alone or in co-culture. Both types of irradiation induced the overexpression of genes involved in cell growth, inflammation and angiogenesis. Conclusions: We set up new irradiation chamber in which two cell types were irradiated together with a particle beam. We could not show that tumor cells and endothelial cells were able to protect each other from particle irradiation. Gene expression changes were observed after particle irradiation that could suggest a possible radioprotective inter-cellular communication between the two cell types but further investigations are needed to confirm these results.

  4. Discrimination of nuclear recoils from alpha particles with superheated liquids

    CERN Document Server

    Aubin, F; Behnke, E; Beltran, B; Clark, K; Dai, X; Davour, A; Genest, M-H; Giroux, G; Gornea, R; Faust, R; Krauss, C B; Leroy, C; Lessard, L; Levine, I; Levy, C; Martin, J -P; Noble, A J; Morlat, T; Nadeau, P; Piro, M -C; Pospísil, S; Shepherd, T; Sodomka, J; Starinski, N; Stekl, I; Storey, C; Wichoski, U; Zacek, V

    2008-01-01

    The PICASSO collaboration observed for the first time a significant difference between the acoustic signals induced by neutrons and alpha particles in a detector based on superheated liquids. This new effect offers the possibility of improved background suppression and could be especially useful for rare event searches such as dark matter experiments.

  5. Single particle level scheme for alpha decay

    International Nuclear Information System (INIS)

    The fine structure phenomenon in alpha decay was evidenced by Rosenblum. In this process the kinetic energy of the emitted particle has several determined values related to the structure of the parent and the daughter nucleus. The probability to find the daughter in a low lying state was considered strongly dependent on the spectroscopic factor defined as the square of overlap between the wave function of the parent in the ground state and the wave functions of the specific excited states of the daughter. This treatment provides a qualitative agreement with the experimental results if the variations of the penetrability between different excited states are neglected. Based on single particle structure during fission, a new formalism explained quantitatively the fine structure of the cluster decay. It was suggested that this formalism can be applied also to alpha decay. For this purpose, the first step is to construct the level scheme of this type of decay. Such a scheme, obtained with the super-asymmetric two-center potential, is plotted for the alpha decay of 223Ra. It is interesting to note that, diabatically, the level with spin 3/2 emerging from 1i11/2 (ground state of the parent) reaches an excited state of the daughter in agreement with the experiment. (author)

  6. The Fission of Thorium with Alpha Particles

    Energy Technology Data Exchange (ETDEWEB)

    Newton, Amos S.

    1948-04-15

    The fission distribution of fission of thorium with alpha particle of average energy 37.5 Mev has been measured by the chemical method. The distribution found shows that the characteristic dip in the fission yield mass spectrum has been raised to within a factor of two of the peaks compared to a factor of 600 in slow neutron fission of U{sup 235}. The raise in the deip has caused a corresponding lowering in fission yield of these elements at the peaks. The cross section for fission of thorium with 37.5 Mev alphas was found to be about 0.6 barn, and the threshold for fission was found to be 23 to 24 Mev.

  7. Alpha particle induced DNA damage and repair in normal cultured thyrocytes of different proliferation status

    Energy Technology Data Exchange (ETDEWEB)

    Lyckesvärd, Madeleine Nordén, E-mail: madeleine.lyckesvard@oncology.gu.se [Department of Oncology, Sahlgrenska Academy, University of Gothenburg (Sweden); Delle, Ulla; Kahu, Helena [Department of Oncology, Sahlgrenska Academy, University of Gothenburg (Sweden); Lindegren, Sture [Department of Radiation Physics, Sahlgrenska Academy, University of Gothenburg (Sweden); Jensen, Holger [The PET and Cyclotron Unit Copenhagen University Hospital, Rigshospitalet (Denmark); Bäck, Tom [Department of Radiation Physics, Sahlgrenska Academy, University of Gothenburg (Sweden); Swanpalmer, John [Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg (Sweden); Elmroth, Kecke [Department of Oncology, Sahlgrenska Academy, University of Gothenburg (Sweden)

    2014-07-15

    Highlights: • We study DNA damage response to low-LET photons and high-LET alpha particles. • Cycling primary thyrocytes are more sensitive to radiation than stationary cells. • Influence of radiation quality varies due to cell cycle status of normal cells. • High-LET radiation gives rise to a sustained DNA damage response. - Abstract: Childhood exposure to ionizing radiation increases the risk of developing thyroid cancer later in life and this is suggested to be due to higher proliferation of the young thyroid. The interest of using high-LET alpha particles from Astatine-211 ({sup 211}At), concentrated in the thyroid by the same mechanism as {sup 131}I [1], in cancer treatment has increased during recent years because of its high efficiency in inducing biological damage and beneficial dose distribution when compared to low-LET radiation. Most knowledge of the DNA damage response in thyroid is from studies using low-LET irradiation and much less is known of high-LET irradiation. In this paper we investigated the DNA damage response and biological consequences to photons from Cobolt-60 ({sup 60}Co) and alpha particles from {sup 211}At in normal primary thyrocytes of different cell cycle status. For both radiation qualities the intensity levels of γH2AX decreased during the first 24 h in both cycling and stationary cultures and complete repair was seen in all cultures but cycling cells exposed to {sup 211}At. Compared to stationary cells alpha particles were more harmful for cycling cultures, an effect also seen at the pChk2 levels. Increasing ratios of micronuclei per cell nuclei were seen up to 1 Gy {sup 211}At. We found that primary thyrocytes were much more sensitive to alpha particle exposure compared with low-LET photons. Calculations of the relative biological effectiveness yielded higher RBE for cycling cells compared with stationary cultures at a modest level of damage, clearly demonstrating that cell cycle status influences the relative

  8. I. Excluded Volume Effects in Ising Cluster Distributions and Nuclear Multifragmentation II. Multiple-Chance Effects in Alpha-Particle Evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Breus, Dimitry E.

    2005-05-16

    In Part 1, geometric clusters of the Ising model are studied as possible model clusters for nuclear multifragmentation. These clusters may not be considered as non-interacting (ideal gas) due to excluded volume effect which predominantly is the artifact of the cluster's finite size. Interaction significantly complicates the use of clusters in the analysis of thermodynamic systems. Stillinger's theory is used as a basis for the analysis, which within the RFL (Reiss, Frisch, Lebowitz) fluid-of-spheres approximation produces a prediction for cluster concentrations well obeyed by geometric clusters of the Ising model. If thermodynamic condition of phase coexistence is met, these concentrations can be incorporated into a differential equation procedure of moderate complexity to elucidate the liquid-vapor phase diagram of the system with cluster interaction included. The drawback of increased complexity is outweighted by the reward of greater accuracy of the phase diagram, as it is demonstrated by the Ising model. A novel nuclear-cluster analysis procedure is developed by modifying Fisher's model to contain cluster interaction and employing the differential equation procedure to obtain thermodynamic variables. With this procedure applied to geometric clusters, the guidelines are developed to look for excluded volume effect in nuclear multifragmentation. In part 2, an explanation is offered for the recently observed oscillations in the energy spectra of {alpha}-particles emitted from hot compound nuclei. Contrary to what was previously expected, the oscillations are assumed to be caused by the multiple-chance nature of {alpha}-evaporation. In a semi-empirical fashion this assumption is successfully confirmed by a technique of two-spectra decomposition which treats experimental {alpha}-spectra has having contributions from at least two independent emitters. Building upon the success of the multiple-chance explanation of the oscillations, Moretto

  9. Track nanodosimetry of an alpha particle

    International Nuclear Information System (INIS)

    Experimental measurements and calculations are described of ionisation distributions in propane wall-less gas cavities of about 20 nm simulated size, performed at different distances from a 244Cm alpha particle track. Ionisation events are detected one by one by collecting electrons from the sensitive volume and by separating them with a drift column. Experimental results and Monte Carlo calculations indicate that, in the delta ray cloud, conditional probability curves, average cluster size and the ratio of second moment above first moment of the cluster distribution are invariant with track distance. (author)

  10. Track nanodosimetry of an alpha particle.

    Science.gov (United States)

    De Nardo, L; Colautti, P; Baek, W Y; Grosswendt, B; Alkaa, A; Ségur, P; Tornielli, G

    2002-01-01

    Experimental measurements and calculations are described of ionisation distributions in propane wall-less gas cavities of about 20 nm simulated size, performed at different distances from a 244Cm alpha particle track. Ionisation events are detected one by one by collecting electrons from the sensitive volume and by separating them with a drift column. Experimental results and Monte Carlo calculations indicate that, in the delta ray cloud, conditional probability curves, average cluster size and the ratio of second moment above first moment of the cluster distribution are invariant with track distance. PMID:12194323

  11. Track nanodosimetry of an alpha particle

    Energy Technology Data Exchange (ETDEWEB)

    De Nardo, L.; Colautti, P.; Baek, W.Y.; Grosswendt, B.; Alkaa, A.; Segur, P.; Tornielli, G

    2002-07-01

    Experimental measurements and calculations are described of ionisation distributions in propane wall-less gas cavities of about 20 nm simulated size, performed at different distances from a {sup 244}Cm alpha particle track. Ionisation events are detected one by one by collecting electrons from the sensitive volume and by separating them with a drift column. Experimental results and Monte Carlo calculations indicate that, in the delta ray cloud, conditional probability curves, average cluster size and the ratio of second moment above first moment of the cluster distribution are invariant with track distance. (author)

  12. Superparamagnetic relaxation in alpha-Fe particles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Pedersen, Michael Stanley; Svedlindh, P.; Jonsson, G.T.; Garcia-Palacios, J.L.; Lazaro, F.J.

    1998-01-01

    The superparamagnetic relaxation time of carbon-supported alpha-Fe particles with an average size of 3.0 Mm has been studied over a large temperature range by the use of Mossbauer spectroscopy combined with AC and DC magnetization measurements. It is found that the relaxation time varies with...... temperature in accordance with Ni el's expression, tau = tau(0) exp (KV/kT) with tau(0) = (1.0 +/- 0.5) x 10(-10) s and K = (1.2 +/- 0.2) x 10(5) J m(-3). (C) 1998 Elsevier Science B.V. All rights reserved....

  13. Global alpha-particle optical potentials

    International Nuclear Information System (INIS)

    A search for a global optical potential for alpha-particles is described. It did not prove possible to find such a potential valid for a wide range of energies and nuclei, even treating the absorbing potential as an adjustable parameter for each nucleus. For practical purposes the best that can be done is to define an average potential, and such a potential is compared with a wide range of experimental data. Its energy variation is determined by fitting the total reaction cross-section. (author). 7 refs, 15 figs, 1 tab

  14. Evaluation of biological effectiveness of high energy charged particles in terms of cytogenetic disorders in murine sex cells

    International Nuclear Information System (INIS)

    The frequency of reciprocal translocations in spermatogenia of F1(CBAxC57Bl6) mice irradiated with 50 MeV protons, 4.2 GeV deuterons, 1.8 GeV/nuclon helium ions, or 60Co γ-rays was investigated. The relative biological effectiveness of these particles calculated by comparing the equiffective doses of reference and experimental radiations was less than 1.0 under the assumption of the linear dose-effect relationship. The RBE of the particles calculated by means of the nonparametric method largely depended on the doses applied

  15. Alpha particles (citations from the International Aerospace Abstracts data base). Report for 1974-July 1979

    International Nuclear Information System (INIS)

    This bibliography of citations to the international literature covers various aspects of alpha particles as applied to controlled fusion devices, solar activity, and geomagnetically trapped particles. Included are articles concerning Tokamak devices, plasma heating and control, plasma-particle interactions, solar particles, solar wind, solar flares, energy spectra, and magnetohydrodynamic stability. Articles concerning effects of alpha particles on different kinds of devices are also included

  16. Theoretical and observational analysis of individual ionizing particle effects in biological tissue

    International Nuclear Information System (INIS)

    The microstructural damage to living tissue caused by heavy ion radiation was studied. Preliminary tests on rat corneal tissue, rat cerebellar tissue grown in culture, and rat retinal tissue indicated that the best assay for heavy ion damage is the rat cornea. The corneal tissue of the living rat was exposed to beams of carbon at 474 MeV/amu, neon at 8.5 MeV/amu, argon at 8.5 MeV/amu, silicon at 530 MeV/amu, iron at 500 MeV/amu, and iron at 600 MeV/amu. X-rays were also used on corneas to compare with the heavy ion irradiated corneas. Scanning electron microscopy revealed lesions with circular symmetry on the external plasma membranes of corneal epithelium which were irradiated with heavy ions, but similar lesions were not observed on the plasma membranes of x-ray irradiated or non-irradiated control samples. These data verify the special way in which heavy ions interact with matter: each ion interacts coulombically with electrons all along its trajectory to generate a track. The dose from heavy ion radiation is not distributed homogeneously on a tissue microstructural scale but is concentrated along the individual particle track. Even along a single particle track the dose is discontinuous except at the Bragg peak when the LET is maximum. Micrographs of heavy-ion-irradiated corneas demonstrated two significant correlations with the heavy ion beam: (1) the number of plasma membrane lesions per unit area was correlated with the particle fluence, and (2) the diameter of the lesions were linearly related to the energy loss or LET of the individual particle. These observations corroborate what has already been suggested theoretically about heavy ion tracks and what has been shown experimentally. But the new data indicate that particle tracks occur in biological tissues as well, and that a single heavy ion is responsible for each membrane lesion

  17. Monte Carlo nanodosimetry of alpha particle passages through the capillary endothelial nucleus application to systemic Targeted Alpha Therapy

    International Nuclear Information System (INIS)

    Full text: The biological effects of Targeted Alpha Therapy are strongly affected by the heterogeneous specific energy delivered to tumor cells. For systemic Targeted Alpha Therapy, all blood vessels inevitably received a background radiation from non-targeted decays with the blood circulation. The Geant4 Monte Carlo code was adapted to simulate the spatial non-uniform distribution of the alpha emitting radioisotope sources 213Bi, 212Bi and 211At. A cylindrical annulus was taken as a geometrical model to approximate the capillary. The endothelial cell nucleus was set to be an ellipsoid filled with liquid water to simulate nanometric target volumes at unit density. The Geant4 Low Energy physics model, based on the Livermore approach, was selected to model the particle interactions with the material in the experimental setup. The threshold of production of secondary particles was 7 eV. We validated the program with published results using spheroid cell geometry. The specific energy deposited in a capillary endothelial cell nucleus per radioactive decay and the capillary endothelial cell survival rates were calculated for the source constrained in the capillary lumen or the source binding to the surface antigen on the perivascular cancer cells. The measurement of nanodosimetric event size spectra based on simulated nanodosimetric data is presented. The value and limitations of this approach are discussed. (author)

  18. Alpha-particle losses in compact torsatron reactors

    International Nuclear Information System (INIS)

    Loss of alpha particles in compact torsatron reactors is studied. For 6, 9, and 12 field period reactors, the direct loss is a relatively weak function of radius and energy and varies from ≅33% for M = 6 to ≅18% for M = 12. Loss of alpha particles through scattering into the loss region is calculated using the Fokker-Plank equation for fast ions and found to contribute an additional alpha-particle energy loss of ≅15%. The consequences of these relatively large losses for torsatron reactor design are discussed. The relationship between the direct particle losses and the magnetic field structure is also studied. Orbit losses from a variety of stellarator configurations are calculated and a figure-of-merit that characterizes the orbit confinement of a magnetic configuration is deduced from these calculations. This figure-of-merit is used to show how the direct losses might be reduced at low aspect-ratio. Effects of finite beta on the direct particle losses are also addressed, and are shown to significantly increase the direct losses in some configurations. 15 refs., 8 figs

  19. Biological Effects of Particles with Very High Energy Deposition on Mammalian Cells Utilizing the Brookhaven Tandem Van de Graaff Accelerator

    Science.gov (United States)

    Saha, Janapriya; Cucinotta, Francis A.; Wang, Minli

    2013-01-01

    High LET radiation from GCR (Galactic Cosmic Rays) consisting mainly of high charge and energy (HZE) nuclei and secondary protons and neutrons, and secondaries from protons in SPE (Solar Particle Event) pose a major health risk to astronauts due to induction of DNA damage and oxidative stress. Experiments with high energy particles mimicking the space environment for estimation of radiation risk are being performed at NASA Space Radiation Laboratory at BNL. Experiments with low energy particles comparing to high energy particles of similar LET are of interest for investigation of the role of track structure on biological effects. For this purpose, we report results utilizing the Tandem Van de Graaff accelerator at BNL. The primary objective of our studies is to elucidate the influence of high vs low energy deposition on track structure, delta ray contribution and resulting biological responses. These low energy ions are of special relevance as these energies may occur following absorption through the spacecraft and shielding materials in human tissues and nuclear fragments produced in tissues by high energy protons and neutrons. This study will help to verify the efficiency of these low energy particles and better understand how various cell types respond to them.

  20. Alpha particle loss in the TFTR DT experiments

    International Nuclear Information System (INIS)

    Alpha particle loss was measured during the TFTR DT experiments using a scintillator detector located at the vessel bottom in the ion grad-B drift direction. The DT alpha particle loss to this detector was consistent with the calculated first-orbit loss over the whole range of plasma current I=0.6-2.7 MA. In particular, the alpha particle loss rate per DT neutron did not increase significantly with fusion power up to 10.7 MW, indicating the absence of any new ''collective'' alpha particle loss processes in these experiments

  1. Study on cytotoxicities induced by alpha particle irradiation combined with NNK treatment

    International Nuclear Information System (INIS)

    Objective: To investigate cytotoxicities of alpha-particle irradiation combined with NNK treatment. Methods: Exponentially growing immortalized human bronchial epithelial cells were divided into normal control group (NC), alpha particle irradiation group (α), NNK administration group (NNK), NNK administration (100 μg/ml) followed by alpha particle irradiation group (NNK + α), and alphaparticle irradiation followed by NNK administration (100 μg/ml) group (α + NNK). Cell survival fractions were measured by cloning rate of low-density plating cell. Ethidium bromide and 2', 7'-dichlorofluorescein, fluorescent products of the membrane-permeable dyes hydroethine and 2', 7'-dichloroflurescindiacetate were used to monitor the inarticulate reactive oxygen species (ROS) . Damage to membrane permeability was evaluated through testing LDH activity in medium. Results: In the groups exposed to both alpha particles and NNK, the survival rates were significantly lower than that of the groups administrated with the same dose of alpha particles or NNK alone. The levels of intracellular ROS and the activity of LDH in medium were significantly higher than that of the groups administrated with the same dose of alpha particles or NNK alone. Subtracted the NNK effect, the survival rates of the groups received both alpha particle irradiation and NNK treatment were significantly lower than that of alpha particle irradiated only group. However, the intracellular ROS level and the activity of LDH in medium were significantly higher than that of alpha-particle irradiated only group. In addition, the survival rates of the cells in groups exposed to alpha particle irradiation followed by NNK administration were significantly lower than that of cells treated with NNK administration followed by alpha particle irradiation. Conclusions: Alpha particle irradiation and NNK administration had synergisticity in cytotoxicity, and furthermore different schedules of the administration resulted in

  2. Alpha particle destabilization of the TAE modes

    International Nuclear Information System (INIS)

    The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped α-particles through the wave-particle resonances. For a poloidal harmonic to satisfy the resonance condition it requires that the α-particle birth speed vα ≥ vA/(2|m-nq|), where vA is the Alfven speed, m is the poloidal mode number, and n is the toroidal mode number. To destabilize the TAE modes, the inverse Landau damping associated with the α-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the slowing-down α-particle and the core Maxwellian electron and ion distributions. Stability criteria in terms of the α-particle beta βα, α-particle pressure gradient parameter (ω*/ωA) (ω* is the α-particle diamagnetic drift frequency), and (vα/vA) parameters are presented for TFTR, CIT, and ITER tokamaks. The volume averaged α-particle beta threshold for TAE instability also depends sensitively on the core electron and ion temperature. Typically the volume averaged α-particle beta threshold is in the order of 10-4 if the continuum damping effect is absent. Typical growth rates of the n = 1 TAE mode can be in the order of 10-2ωA, where ωA = vA/qR. Stability of higher n TAE modes is also studied. Other types of global Alfven waves are stable due to sideband mode continuum damping resulting from toroidal coupling effects. If the Alfven continuum gap does not exist across the whole minor radius, continuum damping exists for some poloidal harmonics. The continuum damping effect is studied by employing both a resistive MHD stability code (NOVA-R) and an analytical matching method, and the results are presented. 1 ref

  3. Anomalous loss of DT alpha particles in the Tokamak Fusion Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, H.W.

    1997-09-01

    An escaping alpha collector probe has been developed for TFTR`s DT phase. Energy distributions of escaping alphas have been determined by measuring the range of {alpha}-particles implanted into nickel foils located within the alpha collector. Results at 1.0 MA of plasma current are in good agreement with predictions for first orbit alpha loss. Results at 1.8 MA, however, show a significant anomalous loss of partially thermalized alphas (in addition to the expected first orbit loss), which is not observed with the lost alpha scintillator detectors in DT plasmas, but does resemble the anomalous delayed loss seen in DD plasmas. None of the candidate explanations proposed thus far are fully consistent with the anomalous loss observations. An experiment designed to study the effect of plasma major radius shifts on {alpha}-particle loss has led to a better understanding of {alpha}-particle dynamics in tokamaks. Intuitively, one might suppose that confined marginally passing {alpha}-particles forced to move toward higher magnetic field during an inward major radius shift (i.e., compression) would mirror and become trapped particles, leading to increased alpha loss. Such an effect was looked for during the shift experiment, however, no significant changes in alpha loss to the 90{degree} lost alpha scintillator detector were observed during the shifts. It is calculated that the energy gained by an {alpha}-particle during the inward shift is sufficient to explain this result. However, an unexpected loss of partially thermalized {alpha}-particles near the passing/trapped boundary was observed to occur between inward and outward shifts at an intermediate value of plasma current (1.4 MA). This anomalous loss feature is not yet understood.

  4. Biologically produced sulfur particles and polysulfide ions

    OpenAIRE

    Kleinjan, W.E.

    2005-01-01

    This thesis deals with the effects of particles of biologically produced sulfur (or 'biosulfur') on a biotechnological process for the removal of hydrogen sulfide from gas streams. Particular emphasis is given to the role of polysulfide ions in such a process. These polysulfide ions are formed from reaction of sulfide with biologically produced sulfur. The basic concepts of this H 2 S removal process were developed at the department of Environmental Technology of Wageningen University and the...

  5. Lorentz alpha orbit calculation in search of position suitable for escaping alpha particle diagnostics in ITER

    International Nuclear Information System (INIS)

    The Lorentz orbit code is developed to understand escaping alpha particle orbits and to contribute to the design of an escaping alpha particle probe in ITER. The code follows the full gyromotion of an alpha particle in ITER equilibrium, considering the toroidal field magnetic field ripple produced by the finite number of toroidal field coils as well as full three-dimensional first wall panels placed at the outboard side of the torus. It is shown that alpha particles that exist in the peripheral region and have banana orbits intersect the first wall placed at the outboard side on the lower plane. (author)

  6. Effects of alpha-calcitonin gene-related peptide on osteoprotegerin and receptor activator of nuclear factor-κB ligand expression in MG-63 osteoblast-like cells exposed to polyethylene particles

    Directory of Open Access Journals (Sweden)

    Kauther Max D

    2010-11-01

    Full Text Available Abstract Background Recent studies demonstrated an impact of the nervous system on particle-induced osteolysis, the major cause of aseptic loosening of joint replacements. Methods In this study of MG-63 osteoblast-like cells we analyzed the influence of ultra-high molecular weight polyethylene (UHMWPE particles and the neurotransmitter alpha-calcitonin gene-related peptide (CGRP on the osteoprotegerin/receptor activator of nuclear factor-κB ligand/receptor activator of nuclear factorκB (OPG/RANKL/RANK system. MG-63 cells were stimulated by different UHMWPE particle concentrations (1:100, 1:500 and different doses of alpha-CGRP (10-7 M, 10-9 M, 10-11 M. RANKL and OPG mRNA expression and protein levels were measured by RT-PCR and Western blot. Results Increasing particle concentrations caused an up-regulation of RANKL after 72 hours. Alpha-CGRP showed a dose-independent depressive effect on particle-induced expression of RANKL mRNA in both cell-particle ratios. RANKL gene transcripts were significantly (P -7 M lead to an up-regulation of OPG protein. Conclusion In conclusion, a possible osteoprotective influence of the neurotransmitter alpha-CGRP on particle stimulated osteoblast-like cells could be shown. Alpha-CGRP might be important for bone metabolism under conditions of particle-induced osteolysis.

  7. Biological Effects of Osteoblast-Like Cells on Nanohydroxyapatite Particles at a Low Concentration Range

    Directory of Open Access Journals (Sweden)

    Xiaochen Liu

    2011-01-01

    Full Text Available The biological effects of osteoblast-like MG-63 cells on nanohydroxyapatite (n-HA at the low concentration range (5–25 g/mL for 5 days was investigated. The results showed the viability and actin cytoskeleton of the cells descended with the increase of the concentration of n-HA, and the actin cytoskeleton of cells was depolymerised and became more disordered. Apoptotic rate of cells (1.85%, 1.99%, and 2.29% increased with the increase of n-HA concentration (5, 15, and 25 g/mL and become significantly higher than the control. Total intracellular protein content decreased with n-HA concentration increase, showing significant difference between 25 g/mL and the control, and no significant change of ALP activity was observed at the 5th day. The results revealed that the cell growth was inhibited by n-HA in a concentration-dependent manner, and the obvious biological effects of MG-63 cells on n-HA existed at the low concentration range from 5 to 25 g/mL.

  8. Anomalous Loss of DT Alpha Particles in the Tokamak Fusion Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, Hans W.

    1997-06-01

    Princeton's Tokamak Fusion Test Reactor (TFTR) is the first experimental fusion device to routinely use tritium to study the deuterium-tritium (DT) fusion reaction,allowing the first systematic study of DT alpha particles in tokamak plasmas. A crucial aspect of alpha-particle physics is the fraction of alphas that escape from the plasma, particularly since these energetic particles can do severe damage to the first wall of a reactor. An escaping alpha collector probe has been developed for TFTR's DT phase. Energy distributions of escaping alphas have been determined by measuring the range of alpha-particles implanted into nickel foils located within the alpha collector. Results at 1.0 MA of plasma current are in good agreement with predictions for first orbit alpha loss. Results at 1.8 MA, however, show a significant anomalous loss of partially thermalized alphas (in addition to the expected first orbit loss), which is not observed with the lost alpha scintillator detectors in DT plasmas, but does resemble the anomalous "delayed" loss seen in DD plasmas. None of the candidate explanations proposed thus far are fully consistent with the anomalous loss observations. An experiment designed to study the effect of plasma major radius shifts on alpha-particle loss has led to a better understanding of alpha-particle dynamics in tokamaks. Intuitively, one might suppose that confined marginally passing alpha-particles forced to move toward higher magnetic field during an inward major radius shift (i.e. compression) would mirror and become trapped particles, leading to increased alpha loss. Such an effect was looked for during the shift experiment, however, no significant changes in alpha loss to the 90 degree lost alpha scintillator detector were observed during the shifts. It is calculated that the energy gained by an alpha-particle during the inward shift is sufficient to explain this result. However, an unexpected loss of partially thermalized alpha-particles

  9. Biological stress responses induced by alpha radiation exposure in Lemna minor

    Energy Technology Data Exchange (ETDEWEB)

    Van Hoeck, A.; Horemans, N.; Van Hees, M.; Nauts, R. [Belgian Nuclear Research Centre SCK-CEN (Belgium); Knapen, D.; Blust, R. [University of Antwerp (Belgium)

    2014-07-01

    To enhance the robustness of radiation protection criteria for biota, additional information on the biological impact of radionuclides on non-human biota is needed. In particular the effects of alpha emitting isotopes have been poorly studied within a radioecological contextual though they exhibit a high linear energy transfer which can cause significant biological damage when taken up by organisms. Therefore, it is not only essential to measure alpha radiation toxicity, but also try to understand the underlying mechanisms of this stressor. The current study aimed to contribute to a better knowledge of the fundamental processes regulating alpha radiation stress response mechanisms in higher plants. {sup 241}Am was primarily selected as it is an almost pure alpha emitter and, as a daughter nuclide of {sup 241}Pu, it will become one of the dominant pollutants in plutonium affected areas. The aquatic macrophyte Lemna minor has proven its value in eco-toxicological research as representative of higher aquatic plants (OECD guideline nr. 221) and will be used to analyze alpha radiation stress in plant systems. An individual growth inhibition test was set up by means of single dose-response curve in order to identify the Effective Dose Rates (EDR-values) for frond size and biomass. As the mean path length is small for alpha particles, the accumulation of the radionuclide inside species represents almost exclusively the dosimetry. Therefore, quantification of {sup 241}Am uptake and {sup 241}Am distribution were evaluated separately for roots and fronds taking the activity concentrations of growth medium into account. Taken together with the respective dose conversion coefficients from the ERICA tool, this allowed to construct an accurate dosimetric model to determine internal and external dose rates. Different standard media were tested on growth rate and biomass to analyse the amount of {sup 241}Am taken up by the plants exposed from 2.5 to 100 kBq/L. From these

  10. Relative biological effectiveness in canine osteosarcoma cells irradiated with accelerated charged particles

    Science.gov (United States)

    Maeda, Junko; Cartwright, Ian M.; Haskins, Jeremy S.; Fujii, Yoshihiro; Fujisawa, Hiroshi; Hirakawa, Hirokazu; Uesaka, Mitsuru; Kitamura, Hisashi; Fujimori, Akira; Thamm, Douglas H.; Kato, Takamitsu A.

    2016-01-01

    Heavy ions, characterized by high linear energy transfer (LET) radiation, have advantages compared with low LET protons and photons in their biological effects. The application of heavy ions within veterinary clinics requires additional background information to determine heavy ion efficacy. In the present study, comparison of the cell-killing effects of photons, protons and heavy ions was investigated in canine osteosarcoma (OSA) cells in vitro. A total of four canine OSA cell lines with various radiosensitivities were irradiated with 137Cs gamma-rays, monoenergetic proton beams, 50 keV/µm carbon ion spread out Bragg peak beams and 200 keV/µm iron ion monoenergetic beams. Clonogenic survival was examined using colony-forming as says, and relative biological effectiveness (RBE) values were calculated relative to gamma-rays using the D10 value, which is determined as the dose (Gy) resulting in 10% survival. For proton irradiation, the RBE values for all four cell lines were 1.0–1.1. For all four cell lines, exposure to carbon ions yielded a decreased cell survival compared with gamma-rays, with the RBE values ranging from 1.56–2.10. Iron ions yielded the lowest cell survival among tested radiation types, with RBE values ranging from 3.51–3.69 observed in the three radioresistant cell lines. The radiosensitive cell line investigated demonstrated similar cell survival for carbon and iron ion irradiation. The results of the present study suggest that heavy ions are more effective for killing radioresistant canine OSA cells when compared with gamma-rays and protons. This markedly increased efficiency of cell killing is an attractive reason for utilizing heavy ions for radioresistant canine OSA. PMID:27446477

  11. High resolution alpha-particle-spectrometry for radium analysis -the effects of sample thickness and filter pore size

    International Nuclear Information System (INIS)

    In the α-particle spectrometric technique for radium isotope analysis, the effects of the barium carrier thickness and pore size of the membrane filter (used for the main Ba-Ra sulphate filtration) on the resolution of the α-particle energy peaks were investigated. With 0.45 μm Millipore membrane filters, the full width at half maximum (FWHM) for 4.78 MeV α-decay peak of 226Ra decreased from 221.7 to 121.3 keV with reduction in barium carrier additions from 320 to 20 μg Ba. The resolution further improved to 67.0 keV for 20 μg Ba carrier when 0.2 μm Nucleopore filters were used. There was also a significant decrease (20-50%) in the retention of radon and its daughters compared to their equilibrium concentrations as the barium carrier thickness was reduced. A correlation study between 133Ba tracer and 226Ra isotopes recovery factors gave a recovery factor 226Ra/133Ba ratio of 0.93 ± 0.08 in the main Ba-Ra sulphate precipitate under various pH and sulphate concentration conditions. (author)

  12. Biological effects

    International Nuclear Information System (INIS)

    Following an introduction into the field of cellular radiation effect considering the most important experimental results, the biological significance of the colony formation ability is brought out. The inactivation concept of stem cells does not only prove to be good, according to the present results, in the interpretation of the pathogenesis of acute radiation effects on moult tissue, it also enables chronicle radiation injuries to be interpreted through changes in the fibrous part of the organs. Radiation therapy of tumours can also be explained to a large extent by the radiation effect on the unlimited reproductiveness of tumour cells. The more or less similar dose effect curves for healthy and tumour tissue in practice lead to intermittent irradiation. The dependence of the intermittent doses and intervals on factors such as Elkind recovery, synchronisation, redistribution, reoxygenation, repopulation and regeneration are reviewed. (ORU/LH)

  13. Alpha spectrometry for particle size determination of mineral sands dust samples

    International Nuclear Information System (INIS)

    A method is proposed for assessing the size distribution of the radioactive particles directly from the alpha spectrum of a dust sample. The residual range distribution of alpha particles emerging from a sphere containing a monoenergetic alpha emitter is simply a quadratic function of the diameter of the sphere. The residual range distribution from a typical dust particle closely approximates that of a sphere of the same mass. For mixtures of various size particles of similar density the (multiparticle) residual range distribution can thus readily be calculated for each of the alpha emitters contained in the particles. Measurement of the composite residual range distribution can be made in a vacuum alpha spectrometer provided the dust sample has no more than a monolayer of particles. The measured energy distribution is particularly sensitive to upper particle size distributions in the diameter region of 4μm to 20μm of 5 mg/cm3 density particles, i.e. 2 to 10 mg/ch2. For dust particles containing212Po or known ratios of alpha emitters a measured alpha spectrum can be unraveled to the underlying particle size distribution. Uncertainty in the size distribution has been listed as deserving research priority in the overall radiation protection program of the mineral sands industry. The proposed method had the potential of reducing this uncertainty, thus permitting more effective radiation protection control. 2 refs., 1 tabs., 1 figs

  14. Alpha particle radiography of ants using a 244Cm alpha source

    International Nuclear Information System (INIS)

    Alpha particles emitted from a radioisotope 244Cm were used for the radiography of ants. Cellulose nitrate films, LR-115 from Kodak Pathe, were used as solid state nuclear track detectors to make the radiographs. Alpha particles of energies from 3.5 to 5.5 MeV were obtained by varying the air spacing between the 244Cm and the sample with stainless steel spacers of thickness from 2.4 to 0.5 cm to slow the 5.81 MeV alpha particles from the 244Cm by air. The resulting radiographs of the ants put on the LR-115 films and irradiated by alpha particles of different energies show that only the profiles of the ants were obtained when the ants were exposed to alpha particles of energies lower than 3.5 MeV, and almost all parts of the ant except a portion in the head were penetrated by alpha particles of energies higher than 5.0 MeV to register high density alpha tracks on the LR-115. The details of the internal organs of the ant can be shown clearly by radiography with alpha particles of energies between 4.0 and 5.0 MeV. (author)

  15. Radiation damage effects from alpha particle and influence of thermal annealing to defects at room temperature in silicon multiplication avalanche photo diode (MAPD)

    International Nuclear Information System (INIS)

    The increasing interest of new generation accelerators demand to produce detectors based on semiconductors which have radiation hardness. The getting progress in detectors based on semiconductor do not allow to say that the problem was solved. Thus producing radiation hardness detectors became problem for today. In the last several years the advanced progress in area MAPD allows to use this type diode in high energy physics as multiplier tube and detectors so investigation of radiation hardness of MAPD is very important. Influence of high energy protons, neutron and positron to MAPD were investigated. Influence of alpha particle is not investigated yet so this paper dedicated to investigate influence of alpha particle to MAPD.

  16. Alpha particle slowing-down characteristics and the effect on MHD instability excitation at high-density operation points in FFHRs

    International Nuclear Information System (INIS)

    Alpha-particle slowing-down behaviors at low-temperature, high-density operation points in force-free helical reactors (FFHRs) are examined on the basis of a Fokker-Planck (FP) simulation that simultaneously consider the balance among generation, slowing down, and loss from the plasma in parallel with the density dependence of the Alfvén speed. An accurate treatment of the boundary velocity region between thermal and non-thermal components is shown to be important in evaluating the alpha particle population that can induce instability. In a typical high-density, low-temperature operation point in an FFHR, this population is reduced. (author)

  17. Heavy charged particle radiobiology: using enhanced biological effectiveness and improved beam focusing to advance cancer therapy.

    Science.gov (United States)

    Allen, Christopher; Borak, Thomas B; Tsujii, Hirohiko; Nickoloff, Jac A

    2011-06-01

    Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation. PMID:21376738

  18. Investigation of fusion alpha particle ripple losses by means of a kinetic code - alpha particle ripple losses in ITER

    International Nuclear Information System (INIS)

    The discrete nature of a tokamak magnetic system as a consequence of N separate field coils leads to a deviation from axial symmetry and causes additional transport referred to as ripple transport. This loss mechanism whose effectiveness increases with the particle energy must be investigated carefully for fusion alpha particles. The first part of the paper treats the ripple problem by means of a kinetic equation based on a modified Fokker-Planck equation generalized for ripple transport in 1.5-dimensional geometry. For a NET-type tokamak, ripple fluxes have been calculated with the edge ripple δ as a parameter and have been compared to neoclassical and anomalous fluxes. It has been found that particle and power loss fractions are small if the ripple is less than 1%. This results has been confirmed in the second part of the paper that studies the alpha particle ripple losses in ITER by Monte Carlo numerical modelling. Calculations were performed for physics phase and technology phase operation, and it has been shown that the first wall heat deposition profile is very sensitive to the details of plasma equilibrium shape, first wall position and ripple profile. The peak heat load, being small for the reference configuration, may easily be increased up to small changes in the ripple profile and the plasma configuration. (author). 7 refs, 6 figs, 1 tab

  19. Scintillation of thin tetraphenyl butadiene films under alpha particle excitation

    CERN Document Server

    Pollmann, Tina; Kuźniak, Marcin

    2010-01-01

    The alpha induced scintillation of the wavelength shifter 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) was studied to improve the understanding of possible surface alpha backgrounds in the DEAP dark matter search experiment. We found that vacuum deposited thin TPB films emit 882 +/-210 photons per MeV under alpha particle excitation. The scintillation pulse shape consists of a double exponential decay with lifetimes of 11 +/-5 ns and 275 +/-10ns.

  20. Chromosomal aberrations induced by alpha particles; Aberraciones cromosomicas inducidas por particulas {alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero C, C.; Brena V, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: cgc@nuclear.inin.mx

    2005-07-01

    The chromosomal aberrations produced by the ionizing radiation are commonly used when it is necessary to establish the exposure dose of an individual, it is a study that is used like complement of the traditional physical systems and its application is only in cases in that there is doubt about what indicates the conventional dosimetry. The biological dosimetry is based on the frequency of aberrations in the chromosomes of the lymphocytes of the individual in study and the dose is calculated taking like reference to the dose-response curves previously generated In vitro. A case of apparent over-exposure to alpha particles to which is practiced analysis of chromosomal aberrations to settle down if in fact there was exposure and as much as possible, to determine the presumed dose is presented. (Author)

  1. Heavy Charged Particle Radiobiology: Using Enhanced Biological Effectiveness and Improved Beam Focusing to Advance Cancer Therapy

    OpenAIRE

    Allen, Christopher; Borak, Thomas B.; Tsujii, Hirohiko; Jac A Nickoloff

    2011-01-01

    Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilitie...

  2. The 1997 IAEA test spectra for alpha-particle spectrometry

    CERN Document Server

    Garcia-Torano, E; Woods, S; Blaauw, M; Fazinic, S

    1999-01-01

    In the framework of an IAEA intercomparison of software for alpha-particle spectrometry, a set of test spectra with reference files was produced for validation and comparison of alpha spectrum analysis programs. The considerations, the spectra and the methods employed to obtain them are presented.

  3. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles

    International Nuclear Information System (INIS)

    The objective of our research work is to provide -- with the aid of biophysical models of radiation action -- information on human risks following exposure to radon alpha particles. The approach proposed consists of (1) developing appropriate models (parametric and non-parametric) for alpha radiation induction of relevant end points (survival, cellular transformation), (2) providing an accurate physical characterization of the particle tracks in terms of nanodosimetric distributions, (3) supporting the models by detailed, molecular studies of the direct and indirect effects of alpha particles on DNA. Activities in the second year of this project are described

  4. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    The objective of our research work is to provide -- with the aid of biophysical models of radiation action -- information on human risks following exposure to radon alpha particles. The approach proposed consists of (1) developing appropriate models (parametric and non-parametric) for alpha radiation induction of relevant end points (survival, cellular transformation), (2) providing an accurate physical characterization of the particle tracks in terms of nanodosimetric distributions, (3) supporting the models by detailed, molecular studies of the direct and indirect effects of alpha particles on DNA. Activities in the second year of this project are described.

  5. Alpha particle response characterization of CdZnTe

    Energy Technology Data Exchange (ETDEWEB)

    Amman, Mark; Lee, Julie S.; Luke, Paul N.

    2001-06-28

    The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. The performance of these detectors is limited by the degree of uniformity in both electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alpha-particle response characterization of CdZnTe crystals fabricated into simple planar detectors is an effective tool to accurately study electron generation and transport. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. A clear correlation has been observed between the distribution of precipitates near the entrance contact on some crystals and their alpha-response maps. Further studies are ongoing to determine the mechanism for the observed response variations and the reason for the correlation. This paper presents the results of these studies and their relationship to coplanar-grid gamma-ray detector performance.

  6. Alpha particle response characterization of CdZnTe

    International Nuclear Information System (INIS)

    The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. The performance of these detectors is limited by the degree of uniformity in both electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alpha-particle response characterization of CdZnTe crystals fabricated into simple planar detectors is an effective tool to accurately study electron generation and transport. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. A clear correlation has been observed between the distribution of precipitates near the entrance contact on some crystals and their alpha-response maps. Further studies are ongoing to determine the mechanism for the observed response variations and the reason for the correlation. This paper presents the results of these studies and their relationship to coplanar-grid gamma-ray detector performance

  7. NASA space cancer risk model-2014: Uncertainties due to qualitative differences in biological effects of HZE particles

    Science.gov (United States)

    Cucinotta, Francis

    Uncertainties in estimating health risks from exposures to galactic cosmic rays (GCR) — comprised of protons and high-energy and charge (HZE) nuclei are an important limitation to long duration space travel. HZE nuclei produce both qualitative and quantitative differences in biological effects compared to terrestrial radiation leading to large uncertainties in predicting risks to humans. Our NASA Space Cancer Risk Model-2012 (NSCR-2012) for estimating lifetime cancer risks from space radiation included several new features compared to earlier models from the National Council on Radiation Protection and Measurements (NCRP) used at NASA. New features of NSCR-2012 included the introduction of NASA defined radiation quality factors based on track structure concepts, a Bayesian analysis of the dose and dose-rate reduction effectiveness factor (DDREF) and its uncertainty, and the use of a never-smoker population to represent astronauts. However, NSCR-2012 did not include estimates of the role of qualitative differences between HZE particles and low LET radiation. In this report we discuss evidence for non-targeted effects increasing cancer risks at space relevant HZE particle absorbed doses in tissue (animal experiments. The NSCR-2014 model considers how these qualitative differences modify the overall probability distribution functions (PDF) for cancer mortality risk estimates from space radiation. Predictions of NSCR-2014 for International Space Station missions and Mars exploration will be described, and compared to those of our earlier NSCR-2012 model.

  8. Luminescence imaging of water during alpha particle irradiation

    Science.gov (United States)

    Yamamoto, Seiichi; Komori, Masataka; Koyama, Shuji; Toshito, Toshiyuki

    2016-05-01

    The luminescence imaging of water using the alpha particle irradiation of several MeV energy range is thought to be impossible because this alpha particle energy is far below the Cerenkov-light threshold and the secondary electrons produced in this energy range do not emit Cerenkov-light. Contrary to this consensus, we found that the luminescence imaging of water was possible with 5.5 MeV alpha particle irradiation. We placed a 2 MBq of 241Am alpha source in water, and luminescence images of the source were conducted with a high-sensitivity, cooled charge-coupled device (CCD) camera. We also carried out such imaging of the alpha source in three different conditions to compare the photon productions with that of water, in air, with a plastic scintillator, and an acrylic plate. The luminescence imaging of water was observed from 10 to 20 s acquisition, and the intensity was linearly increased with time. The intensity of the luminescence with the alpha irradiation of water was 0.05% of that with the plastic scintillator, 4% with air, and 15% with the acrylic plate. The resolution of the luminescence image of water was better than 0.25 mm FWHM. Alpha particles of 5.5 MeV energy emit luminescence in water. Although the intensity of the luminescence was smaller than that in air, it was clearly observable. The luminescence of water with alpha particles would be a new method for alpha particle detection and distribution measurements in water.

  9. Particle Physics Aspects of Antihydrogen Studies with ALPHA at CERN

    CERN Document Server

    Fujiwara, M C; Bertsche, W; Bowe, P D; Bray, C C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Funakoshi, R; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A J; Hydomako, R; Jenkins, M J; Jørgensen, L V; Kurchaninov, L; Lai, W; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; Van der Werf, D P; Wasilenko, L; Wurtele, J S; Yamazaki, Y

    2008-01-01

    We discuss aspects of antihydrogen studies, that relate to particle physics ideas and techniques, within the context of the ALPHA experiment at CERN's Antiproton Decelerator facility. We review the fundamental physics motivations for antihydrogen studies, and their potential physics reach. We argue that initial spectroscopy measurements, once antihydrogen is trapped, could provide competitive tests of CPT, possibly probing physics at the Planck Scale. We discuss some of the particle detection techniques used in ALPHA. Preliminary results from commissioning studies of a partial system of the ALPHA Si vertex detector are presented, the results of which highlight the power of annihilation vertex detection capability in antihydrogen studies.

  10. The alpha-particle structure of 44 Ti

    International Nuclear Information System (INIS)

    Some of the bound and unbound states of 44 Ti have a pronounced alpha-particle structure, and their energies and widths may be obtained from an alpha 40 Ca potential. The differential cross-sections for the elastic scattering of alpha particles by 40 a may also be described by such a potential, and some features indicate the presence of unbound states of 44 Ti. The attempts to unify these bound and scattering phenomena by the same potential are described, together with some new calculations using a cosh potential. (author)

  11. An evaluation of alpha particle clustering in heavy nuclei

    International Nuclear Information System (INIS)

    In recent years, the pre-equilibrium models of nuclear reactions have been used to analyze many experiments involving the emission of alpha particles. The results of these analyses have been used as the basis for a calculation of the extent of alpha particle clustering in heavy nuclei. Calculations are presented of the rate of nucleon-nucleon and nucleon-alpha interactions in nuclear matter. Normalizing these to the preformation factors found in reaction studies, the number of alpha clusters in several complex nuclei has been obtained. It is suggested that the number of such performed alpha clusters in nuclei having A = 50, 90, 141, 202, and 232 are, respectively, 2.1, 3.6, 5.2, 6.9, and 7.8. (orig.) 891 FKS/orig. 892 MB

  12. Comparative cytotoxicity, mutagenicity, and transforming potency of X-rays, alpha particles and MNNG for rat tracheal epithelial cells

    International Nuclear Information System (INIS)

    To characterize the potential roles of high- and low-LET radiation in respiratory carcino-genesis, the biological effects of X rays and alpha particles on rat tracheal epithelial (RTE) cells were determined and compared to the effects of the direct-acting carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Each agent caused logarithmic, dose-dependent killing of RTE cells, although the curve for X rays had a significant shoulder. At equitoxic doses, all three agents induced similar frequencies of preneoplastic transformation. Similarly, each agent was capable of inducing a similar level of mutations in RTE cell lines. These data suggest that both high- and low-LET radiation can induce changes involved in early stages of carcinogenesis. In addition, it suggests that inactivation of critical genes, caused by alpha particle-induced deletions, may play a role in the preneoplastic transformation of RTE cells. (author)

  13. Preparation and preclinical evaluation of {sup 211}At-labelled compounds for {alpha}-particle radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, R.H.

    1994-12-31

    The interest for {alpha}-particle emitters in internal radiotherapy is increasing due to improved conjugation chemistry. Experimental work has concentrated on {sup 211}At and {sup 212}Bi since these to nuclides have radiochemical and physical properties suitable for medical application. In this report it is demonstrated that biologically active {sup 211}At-labelled compounds can be prepared within a relatively short time allowing utilization of this 7.2 h {alpha}-particle. It is further shown that {sup 211}At-TP-3 treatment of human osteosarcoma in vitro gives promising therapeutic ratios. 76 refs., 5 figs., 3 tabs.

  14. Theoretical and observational analysis of individual ionizing particle effects in biological tissue

    International Nuclear Information System (INIS)

    This investigation was conducted in an effort to gain a deeper understanding of the microstructural damage to living tissue caused by heavy ion radiation. Preliminary tests on rat corneal tissue, rat cerebellar tissue grown in culture, and rat retinal tissue indicated that of these three tissues the best assay for heavy ion damage might be the rat cornea. The anterior surface of the cornea consists of squamous epithelial cells whose plasma membrane morphology is readily characterized under high resolution scanning electron microscopy (SEM). Thus any structural changed leading to alterations in corneal morphology should be relatively easy to detect if they are within the resolution capability of the SEM. Prior to this work, biological lesions caused by ionizing radiation were almost never observed shortly after a dose was delivered even if the dose was lethal

  15. Springtime precipitation effects on the abundance of fluorescent biological aerosol particles and HULIS in Beijing

    Science.gov (United States)

    Yue, Siyao; Ren, Hong; Fan, Songyun; Sun, Yele; Wang, Zifa; Fu, Pingqing

    2016-07-01

    Bioaerosols and humic-like substances (HULIS) are important components of atmospheric aerosols, which can affect regional climate by acting as cloud condensation nuclei and some of which can damage human health. Up to date, release of bioaerosols and HULIS initiated by precipitation is still poorly understood. Here we present different release processes for bioaerosols, non-bioaerosols and HULIS during a precipitation event in Beijing, China. Large fungal-spore-like aerosols were emitted at the onset and later weak stage of precipitation, the number concentration of which increased by more than two folds, while the number concentration of bacteria-like particles doubled when the precipitation strengthened. Besides, a good correlation between protein-like substances that were measured simultaneously by on-line and off-line fluorescence techniques consolidated their applications to measure bioaerosols. Furthermore, our EEM results suggest that the relative contribution of water-soluble HULIS to microbial materials was enhanced gradually by the rain event.

  16. Alpha-particle diagnostics with high energy neutral beams

    International Nuclear Information System (INIS)

    We have examined the feasibility of alpha-particle diagnostics using a high energy neutral beam on the R-tokamak, a planned device at IPP-Nagoya, Japan, for reacting plasma experiments. In this method, injected neutral particles neutralize alpha particles so as to escape from the magnetically confined plasma through double charge exchange processes, He++ + A0 -- → He0 + A++. Requirements for a probing beam are dis cussed from viewpoints of penetration of an injected beam in the plasma and a neutralization efficiency of alpha particles in a wide velocity range. Either a Li0 beam or a He0 beam in the ground state, produced from a negative ion beam is suitable. A method to neutralize a He- beam into the ground state through an auto-detachment process is proposed. (author)

  17. Detection of alpha particles using DNA/Al Schottky junctions

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ta' ii, Hassan Maktuff Jaber, E-mail: hassankirkukly@gmail.com, E-mail: vengadeshp@um.edu.my [Low Dimensional Materials Research Centre (LDMRC), 50603 Kuala Lumpur (Malaysia); Department of Physics, Faculty of Science, University of Al-Muthana, Al-Muthana 66001 (Iraq); Periasamy, Vengadesh, E-mail: hassankirkukly@gmail.com, E-mail: vengadeshp@um.edu.my [Low Dimensional Materials Research Centre (LDMRC), 50603 Kuala Lumpur (Malaysia); Amin, Yusoff Mohd [Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-09-21

    Deoxyribonucleic acid or DNA can be utilized in an organic-metallic rectifying structure to detect radiation, especially alpha particles. This has become much more important in recent years due to crucial environmental detection needs in both peace and war. In this work, we fabricated an aluminum (Al)/DNA/Al structure and generated current–voltage characteristics upon exposure to alpha radiation. Two models were utilized to investigate these current profiles; the standard conventional thermionic emission model and Cheung and Cheung's method. Using these models, the barrier height, Richardson constant, ideality factor and series resistance of the metal-DNA-metal structure were analyzed in real time. The barrier height, Φ value calculated using the conventional method for non-radiated structure was 0.7149 eV, increasing to 0.7367 eV after 4 min of radiation. Barrier height values were observed to increase after 20, 30 and 40 min of radiation, except for 6, 8, and 10 min, which registered a decrease of about 0.67 eV. This was in comparison using Cheung and Cheung's method, which registered 0.6983 eV and 0.7528 eV for the non-radiated and 2 min of radiation, respectively. The barrier height values, meanwhile, were observed to decrease after 4 (0.61 eV) to 40 min (0.6945 eV). The study shows that conventional thermionic emission model could be practically utilized for estimating the diode parameters including the effect of series resistance. These changes in the electronic properties of the Al/DNA/Al junctions could therefore be utilized in the manufacture of sensitive alpha particle sensors.

  18. Detection of alpha particles using DNA/Al Schottky junctions

    International Nuclear Information System (INIS)

    Deoxyribonucleic acid or DNA can be utilized in an organic-metallic rectifying structure to detect radiation, especially alpha particles. This has become much more important in recent years due to crucial environmental detection needs in both peace and war. In this work, we fabricated an aluminum (Al)/DNA/Al structure and generated current–voltage characteristics upon exposure to alpha radiation. Two models were utilized to investigate these current profiles; the standard conventional thermionic emission model and Cheung and Cheung's method. Using these models, the barrier height, Richardson constant, ideality factor and series resistance of the metal-DNA-metal structure were analyzed in real time. The barrier height, Φ value calculated using the conventional method for non-radiated structure was 0.7149 eV, increasing to 0.7367 eV after 4 min of radiation. Barrier height values were observed to increase after 20, 30 and 40 min of radiation, except for 6, 8, and 10 min, which registered a decrease of about 0.67 eV. This was in comparison using Cheung and Cheung's method, which registered 0.6983 eV and 0.7528 eV for the non-radiated and 2 min of radiation, respectively. The barrier height values, meanwhile, were observed to decrease after 4 (0.61 eV) to 40 min (0.6945 eV). The study shows that conventional thermionic emission model could be practically utilized for estimating the diode parameters including the effect of series resistance. These changes in the electronic properties of the Al/DNA/Al junctions could therefore be utilized in the manufacture of sensitive alpha particle sensors

  19. Detection of alpha particles using DNA/Al Schottky junctions

    Science.gov (United States)

    Al-Ta'ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2015-09-01

    Deoxyribonucleic acid or DNA can be utilized in an organic-metallic rectifying structure to detect radiation, especially alpha particles. This has become much more important in recent years due to crucial environmental detection needs in both peace and war. In this work, we fabricated an aluminum (Al)/DNA/Al structure and generated current-voltage characteristics upon exposure to alpha radiation. Two models were utilized to investigate these current profiles; the standard conventional thermionic emission model and Cheung and Cheung's method. Using these models, the barrier height, Richardson constant, ideality factor and series resistance of the metal-DNA-metal structure were analyzed in real time. The barrier height, Φ value calculated using the conventional method for non-radiated structure was 0.7149 eV, increasing to 0.7367 eV after 4 min of radiation. Barrier height values were observed to increase after 20, 30 and 40 min of radiation, except for 6, 8, and 10 min, which registered a decrease of about 0.67 eV. This was in comparison using Cheung and Cheung's method, which registered 0.6983 eV and 0.7528 eV for the non-radiated and 2 min of radiation, respectively. The barrier height values, meanwhile, were observed to decrease after 4 (0.61 eV) to 40 min (0.6945 eV). The study shows that conventional thermionic emission model could be practically utilized for estimating the diode parameters including the effect of series resistance. These changes in the electronic properties of the Al/DNA/Al junctions could therefore be utilized in the manufacture of sensitive alpha particle sensors.

  20. Anomalous loss of DT alpha particles in the Tokamak Fusion Test Reactor

    International Nuclear Information System (INIS)

    An escaping alpha collector probe has been developed for TFTR's DT phase. Energy distributions of escaping alphas have been determined by measuring the range of α-particles implanted into nickel foils located within the alpha collector. Results at 1.0 MA of plasma current are in good agreement with predictions for first orbit alpha loss. Results at 1.8 MA, however, show a significant anomalous loss of partially thermalized alphas (in addition to the expected first orbit loss), which is not observed with the lost alpha scintillator detectors in DT plasmas, but does resemble the anomalous delayed loss seen in DD plasmas. None of the candidate explanations proposed thus far are fully consistent with the anomalous loss observations. An experiment designed to study the effect of plasma major radius shifts on α-particle loss has led to a better understanding of α-particle dynamics in tokamaks. Intuitively, one might suppose that confined marginally passing α-particles forced to move toward higher magnetic field during an inward major radius shift (i.e., compression) would mirror and become trapped particles, leading to increased alpha loss. Such an effect was looked for during the shift experiment, however, no significant changes in alpha loss to the 90 degree lost alpha scintillator detector were observed during the shifts. It is calculated that the energy gained by an α-particle during the inward shift is sufficient to explain this result. However, an unexpected loss of partially thermalized α-particles near the passing/trapped boundary was observed to occur between inward and outward shifts at an intermediate value of plasma current (1.4 MA). This anomalous loss feature is not yet understood

  1. II. Biological studies of radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, J.H.

    1948-05-24

    With the completion of the 184 inch cyclotron in Berkeley and the successful construction of a deflector system, it was possible to bring the 190 Mev deuteron and the 380 Mev alpha beams out into the air and to begin a study of the effects of high-energy deuteron beams by direct irradiation of biological specimens. The direct biological use of deuteron beams was attempted earlier in Berkeley by Marshak, MacLeish, and Walker in 1940. These and other investigators have been aware for some time of the potential usefulness of high energy particle beams for radio-biological studies and their suitability for biological investigations. R.R. Wilson advanced the idea of using fast proton beams to deliver radiation and intervening tissues. R.E. Zirkle pointed out that such particle beams may be focused or screened until a cross-section of the beam is small enough to study effects of irradiation under the microscope on single cells or on parts of single cells. This article gives an overview of the radiological use of high energy deuteron beams, including the following topics: potential uses of high energy particle beams; experiments on the physical properties of the beam; lethal effect of the deuteron beam on mice.

  2. Springtime precipitation effects on the abundance of fluorescent biological aerosol particles and HULIS in Beijing.

    Science.gov (United States)

    Yue, Siyao; Ren, Hong; Fan, Songyun; Sun, Yele; Wang, Zifa; Fu, Pingqing

    2016-01-01

    Bioaerosols and humic-like substances (HULIS) are important components of atmospheric aerosols, which can affect regional climate by acting as cloud condensation nuclei and some of which can damage human health. Up to date, release of bioaerosols and HULIS initiated by precipitation is still poorly understood. Here we present different release processes for bioaerosols, non-bioaerosols and HULIS during a precipitation event in Beijing, China. Large fungal-spore-like aerosols were emitted at the onset and later weak stage of precipitation, the number concentration of which increased by more than two folds, while the number concentration of bacteria-like particles doubled when the precipitation strengthened. Besides, a good correlation between protein-like substances that were measured simultaneously by on-line and off-line fluorescence techniques consolidated their applications to measure bioaerosols. Furthermore, our EEM results suggest that the relative contribution of water-soluble HULIS to microbial materials was enhanced gradually by the rain event. PMID:27470588

  3. Ionization cluster size distribution for alpha particles: Experiment, modelling

    International Nuclear Information System (INIS)

    The paper presents data for measured ionization cluster size distributions by alpha particles in tissue equivalent media and comparison with the simulated data for liquid water. The experiments were carried out with a beam of 4.6 MeV alpha particles performed in a setup called the JET Counter. The theoretically derived cluster size distributions for alphas particles were obtained using the K-means algorithm. The simulation was carried out by Monte Carlo track structure calculations using cross sections for liquid water. The first moments of cluster size distributions, derived from K-means algorithm as a function of diameter of cluster centroid, were compared with the corresponding moments derived from the experiments for nitrogen and propane targets. It was found that the ratio of the first moments for water to gas targets correlates well with the corresponding ratio of the mean free paths for primary ionization by alpha particles in the two media. It is shown that the cluster size distributions for alpha particles in water, obtained from K-means algorithm, are in agreement with the corresponding distributions measured experimentally in nitrogen or propane gas targets of nano-meter sizes. (authors)

  4. The Biological Effectiveness of Accelerated Particles for the Induction of Chromosome Damage: Track Structure Effects and Cytogenetic Signatures of High-LET Exposure

    Science.gov (United States)

    George, K.; Hada, M.; Chappell, L.; Cucinotta, F. A.

    2012-01-01

    Track structure models predict that at a fixed value of LET, particles with lower charge number, Z will have a higher biological effectiveness compared to particles with a higher Z. In this report we investigated how track structure effects induction of chromosomal aberration in human cells. Human lymphocytes were irradiated in vitro with various energies of accelerated iron, silicon, neon, or titanium ions and chromosome damage was assessed in using three color FISH chromosome painting in chemically induced PCC samples collected a first cell division post irradiation. The LET values for these ions ranged from 30 to 195 keV/micrometers. Of the particles studied, Neon ions have the highest biological effectiveness for induction of total chromosome damage, which is consistent with track structure model predictions. For complex-type exchanges 64 MeV/ u Neon and 450 MeV/u Iron were equally effective and induced the most complex damage. In addition we present data on chromosomes exchanges induced by six different energies of protons (5 MeV/u to 2.5 GeV/u). The linear dose response term was similar for all energies of protons suggesting that the effect of the higher LET at low proton energies is balanced by the production of nuclear secondaries from the high energy protons. All energies of protons have a much higher percentage of complex-type chromosome exchanges than gamma rays, signifying a cytogenetic signature for proton exposures.

  5. Carcinogenic risk of non-uniform alpha particle irradiation in the lungs: radon progeny effects at bronchial bifurcations

    International Nuclear Information System (INIS)

    The combined effect of enhanced deposition and reduced clearance at bronchial bifurcations leads to increased radon progeny doses within branching sites compared with uniformly distributed activity within a given airway generation. A multi-stage carcinogenesis model was used to predict the probability of lung cancer induction at different sites of the bronchial region. For relatively low radon progeny exposures, lung cancer risk is significantly higher in bifurcation zones, particularly at carinal ridges, than along tubular segments. At sufficiently high exposures, however, lung cancer risk is highest in the tubular portions of a generation. This suggests that the common assumption of a uniform dose distribution provides realistic risk estimates for high uranium miner exposures, but may underestimate lung cancer risk at low, environmental exposures. If concomitant exposure to cigarette smoke is factored into our risk analysis in a multiplicative fashion, then the effect related to risk inhomogeneity becomes even more pronounced. (author)

  6. Nuclear track detector characterization for alpha-particle spectroscopy

    International Nuclear Information System (INIS)

    Solid State Nuclear Track Detectors (SSNTDs), CR-39™ type, are usually adopted in many applications in which it could be necessary to select tracks according to the incident alpha-particle energy; so several authors have argued that track parameters such as the major/minor axis being the most often reported, can be used to determine the alpha-particle’s energy. However, the use of these parameters only do an univocal result, for example the same axis length can be obtained for different combinations of incident angles and energies. We report on a track analysis performed by a semiautomatic system that classifies tracks according to two parameters, diameter length and mean grey level. This kind of analysis can give information about the track depth, that increases monotonically with the incident energy and angle of the alpha particle. Combining the information on the two parameters it is possible to determine univocally the incident alpha-particle energy values. In order to characterize CR-39 detectors according to the physical track parameters, detectors were irradiated, inside a vacuum chamber, by alpha particles at thirteen energy values, obtained by different mylar layers in front of a 241Am source. After the exposure the detectors were chemically etched to enlarge the tracks and then analyzed by means of a semiautomatic system, consisting on an optical microscope equipped with a CCD camera connected to a personal computer for image storage. A suitable routine analyzed the track parameters: diameter and mean grey level, allowing us to differentiate tracks according to the incident alpha-particle energy and then to individuate the discrimination factors for radon alpha tracks, when nuclear track detectors are applied in radon surveys. - Highlights: ► CR-39. ► Geometric and optical parameter. ► α spectrometry. ► Calibration

  7. Radon monitor and control system based upon alpha particle detection

    International Nuclear Information System (INIS)

    A system is designed for monitoring or controlling the level of radon in indoor air, based upon measuring alpha particles due to the decay of radon or its daughter atoms. In one embodiment, the alpha particle decay of radon itself is detected and analyzed to control a vent in the heating and air conditioning system to automatically keep the radon level below a preselected level. In another embodiment, the daughter atoms 218Po and 214Po are collected from the indoor air and their alpha particle decays are analyzed to provide a sensitive monitor of radon levels or to control vents in the HVAC system to reduce radon concentrations to permissible levels. In addition, the system provides information on the quality of the air filter and indicates when it needs servicing

  8. Alpha-particle radiobiological experiments using thin CR-39 detectors

    International Nuclear Information System (INIS)

    The present paper studied the feasibility of applying comet assay to evaluate the DNA damage in individual HeLa cervix cancer cells after alpha-particle irradiation. We prepared thin CR-39 detectors (<20 μm) as cell-culture substrates, with UV irradiation to shorten the track formation time. After irradiation of the HeLa cells by alpha particles, the tracks on the underside of the CR-39 detector were developed by chemical etching in (while floating on) a 14 N KOH solution at 37 deg. C. Comet assay was then applied. Diffusion of DNA out of the cells could be generally observed from the images of stained DNA. The alpha-particle tracks corresponding to the comets developed on the underside of the CR-39 detectors could also be observed by just changing the focal plane of the confocal microscope. (authors)

  9. Performance comparison of scintillators for alpha particle detectors

    Science.gov (United States)

    Morishita, Yuki; Yamamoto, Seiichi; Izaki, Kenji; Kaneko, Junichi H.; Toui, Kohei; Tsubota, Youichi; Higuchi, Mikio

    2014-11-01

    Scintillation detectors for alpha particles are often used in nuclear fuel facilities. Alpha particle detectors have also become important in the research field of radionuclide therapy using alpha emitters. ZnS(Ag) is the most often used scintillator for alpha particle detectors because its light output is high. However, the energy resolution of ZnS(Ag)-based scintillation detectors is poor because they are not transparent. A new ceramic sample, namely the cerium doped Gd2Si2O7 (GPS) scintillator, has been tested as alpha particle detector and its performances have been compared to that one of three different scintillating materials: ZnS(Ag), GAGG and a standard plastic scintillator. The different scintillating materials have been coupled to two different photodetectors, namely a photomultiplier tube (PMT) and a Silicon Photo-multiplier (Si-PM): the performances of each detection system have been compared. Promising results as far as the energy resolution performances (10% with PMT and 14% with Si-PM) have been obtained in the case of GPS and GAGG samples. Considering the quantum efficiencies of the photodetectors under test and their relation to the emission wavelength of the different scintillators, the best results were achieved coupling the GPS with the PMT and the GAGG with the Si-PM

  10. Modification of thermal, optical and structural properties of bayfol nuclear track detector by alpha particles irradiation

    International Nuclear Information System (INIS)

    The effect of alpha particle dose on the thermal, optical and structural properties of Bayfol solid state nuclear track detector (SSNTD) was investigated. Non-isothermal studies were carried out using thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG) to obtain the activation energy of decomposition for Bayfol detector. Thermal gravimetric analysis (TGA) indicates that the Bayfol samples decompose in one main break down stage. Samples from 250 cm thickness sheets were exposed to alpha particles in the dose range 3.5-67.03 Gy. The variation of transition temperatures with the alpha particle dose has been determined using differential thermal analysis (DTA). The results indicate that the irradiation with alpha particles in the dose range 26.81-67.03 Gy decreases the melting temperature of the Bayfol samples and this is most suitable for applications requiring the molding of this polymer at lower temperatures. Also, the alpha particle dose gives advantage for increasing the correlation between melting temperatures and the amount of crystalline regions that is related to both cross-linking and degradation phenomena. In addition, optical and structural property studies using refractive index, IR spectroscopy, and x-ray diffraction measurements were performed on non irradiated and irradiated Bayfol samples. The results indicate that the anisotropic character, absorbance and the degree of ordering of the Bayfol polymer are dependent on the alpha particle dose

  11. Relative biological effect of high Z, high LET charged particles for spermatogonial killing

    International Nuclear Information System (INIS)

    The effects of high LET radiations produced with accelerated heavy-ion beams on weight loss of the mouse testes have been examined. It is assumed that weight loss is due primarily to cell death in the germinal epithelium. Results indicate that little or no recovery of sublethal injury occurs in this cell renewal system. Generally, the RBE rises continuously and monotonically for all LET values associated with helium and carbon from 6 to 100 keV/μm. On the other hand, the data for neon and argon do not appear to fit. From the standpoint of the radiobiology of heavy ions, the most significant observation is that LET alone does not account for variation in radiation response of the spermatogonial population

  12. Development of low level alpha particle counting system

    International Nuclear Information System (INIS)

    Much attention has been paid to the trace analysis of uranium and thorium contained in the base material of LSI or VLSI, since the so-called ''soft-error'' of the memory device was known to be due to alpha particles emitted from these radioactive elements. We have developed an apparatus to meet the needs of estimating such a very small quantity of U and Th of the level of ppb, by directly counting alpha particles using a gas-flow type proportional counter. This method requires no sophisticated analytical skill, and the accuracy of the result is satisfactory. The instrumentation and some application of this apparatus are described. (author)

  13. Nuclear reaction diagnostics of fast confined and escaping alpha particles

    International Nuclear Information System (INIS)

    The resonant radiative capture nuclear reactions D(α,γ)6Li, 6Li(α,γ) 19B and 7Li(α,γ)11B are examined as diagnostics of the energy distribution of confined fast alpha particles in tokamak plasmas. Count rates for realistic Q=1 DT plasma conditions are presented and compared to expected backgrounds. The design of and preliminary results from the prototype fusion gamma ray detector on TFTR are presented. The activation reactions are similarly examined as diagnostics of escaping fast alpha particles. Where possible, count rate estimates for Q=1 DT plasmas and proposed ignition devices are presented

  14. Biological agents targeting beyond TNF-alpha

    Directory of Open Access Journals (Sweden)

    Sharma Rashmi

    2008-01-01

    Full Text Available Biological agents represent an important addition to the therapies for immuno-inflammatory conditions and have a great impact on the disease course and quality of life of these patients. However, recent reports of serious infections like tuberculosis, demyelinating and neurodegenerative diseases, pancytopenia, cardiovascular diseases, etc. after anti-TNF therapy raised questions on their safety. Hence, focus is shifted towards drugs targeting cytokine checkpoints in the inflammatory cascades beyond TNF-a. Existing therapeutic targets include the biological agents acting as antagonists of various inflammatory cytokines (Anakinra, Tocilizumab, Atlizumab and modulators of CD80 or CD86-CD28 co-stimulatory signal (Abatacept, CD2 receptors on T-cells (Alefacept, CD11a, subunit of leukocyte function-associated antigen 1 (Efalizumab, vitronectin receptor and CD20 antigen on pre-B, immature and mature B cells (Rituximab. With the introduction of these novel molecules the future for immunomodulatory intervention in rheumatology, asthma, crohn′s disease, septic shock etc. looks very promising. These novel therapeutic agents could truly give a new hope to the clinician to modify the disease and achieve tangible improvements in the lives of the patients.

  15. Alpha-particle condensation in nuclei

    International Nuclear Information System (INIS)

    A round up of the present status of the conjecture that nα nuclei form an α-particle condensate in excited states close to the nα threshold is given. Experiments which could demonstrate the condensate character are proposed. Possible lines of further theoretical developments are discussed. (authors)

  16. Alpha-particle condensation in nuclei

    International Nuclear Information System (INIS)

    A round-up of the present status of the conjecture that nα nuclei form an α-particle condensate in excited states close to the nα threshold is given. Experiments which could demonstrate the condensate character are proposed. Possible lines of further theoretical developments are discussed. (author)

  17. EFFECT OF PARTICLE SIZE AND AERATION ON THE BIOLOGICAL DELIGNIFICATION OF CORN STRAW USING Trametes sp 44

    Directory of Open Access Journals (Sweden)

    Samuel Quintanar Gómez,

    2011-11-01

    Full Text Available Straw is an agricultural byproduct that can be utilized to obtain bioethanol without affecting animal or human sustinence. This process involves recovering the sugars and reducing the lignin content present through the use of ligninolytic fungi such as the basidiomycete Trametes sp. 44. Fermentation was carried out using particle sizes 4 (4.76 mm, No. 4 sieve and 8 (2.30 mm, No. 8 sieve, and two velocities of airflow (100 and 200 mL/min. Study results showed that particle size affected the production of hydrolytic enzymes, as particle size 8 favored the expression of cellulases and hemicellulases. In addition, both aeration and particle size affected the expression of ligninolytic enzymes, as it was observed that with particle size 8 and airflow of 200 mL/min, the study detected 63 AU/mL of LiP and 11 AU/mL of MnP. In the case of laccase, the enzymatic activity detected reached 220 AU/mL using particle size 8 and an airflow velocity of 200 mL/min. Statistical analysis indicated that the treatment that produced the highest biological delignification occurred when Trametes sp. 44 was grown on corn straw at particle size 4 and airflow of 100 mL/min, conditions that yielded 34% delignification at day 12 of fermentation.

  18. Instrument for measuring total alpha particle energies of alpha emitters in ambient air

    Energy Technology Data Exchange (ETDEWEB)

    Kronenberg, S.; Brucker, G.J.; Cummings, B.; Bechtel, E.; Gentner, F.; Horne, S

    2000-11-11

    This paper describes the design, fabrication, testing and evaluation of a self-reading, carbon fiber, electrometer-type instrument. It is used for measuring the total energy of alpha particles emitted in air by progenies of {sup 222}Rn ({sup 218}Po, {sup 214}Pb, and {sup 214}Bi), and sometimes by other types of alpha emitters (e.g. {sup 212}Pb, {sup 238}U, and {sup 239}Pu). The purpose of these measurements is to assess the energy delivered by alpha emission from these sources to the lung tissue. A sample (charged progenies attached to aerosols) is collected on filter paper from a known volume of air and placed on the instrument. The discharge rate indicates the alpha energy in MeV l{sup -1} of air per min that is produced by the alpha emitters. The calibration procedure shows that the instrument has an energy sensitivity for alpha particles of 800.5 MeV/scale unit. The range of the readout scale is 30 units. Measurements of alpha contamination in air were made using this instrument in buildings, private homes and in a standard chamber. The value of the radon concentration in this chamber is traceable back to the US Environmental Protection Agency (EPA) and to the National Institute of Standards and Technology (NIST)

  19. Model of cell response to {\\alpha}-particle radiation

    CERN Document Server

    Liu, Longjian

    2012-01-01

    Starting from a general equation for organism (or cell system) growth and attributing additional cell death rate (besides the natural rate) to therapy, we derive an equation for cell response to {\\alpha} radiation. Different from previous models that are based on statistical theory, the present model connects the consequence of radiation with the growth process of a biosystem and each variable or parameter has meaning regarding the cell evolving process. We apply this equation to model the dose response for {\\alpha}-particle radiation. It interprets the results of both high and low linear energy transfer (LET) radiations. When LET is high, the additional death rate is a constant, which implies that the localized cells are damaged immediately and the additional death rate is proportional to the number of cells present. While at low LET, the additional death rate includes a constant term and a linear term of radiation dose, implying that the damage to some cell nuclei has a time accumulating effect. This model ...

  20. Biological effects of radiation

    International Nuclear Information System (INIS)

    This fourth chapter presents: cell structure and metabolism; radiation interaction with biological tissues; steps of the production of biological effect of radiation; radiosensitivity of tissues; classification of biological effects; reversibility, transmissivity and influence factors; pre-natal biological effects; biological effects in therapy and syndrome of acute irradiation

  1. Biological effects of repeated inhalation exposure of beagle dogs to aerosols of 144Ce in fused clay particles I

    International Nuclear Information System (INIS)

    This experiment was initiated to study the biological behavior and long-term effects of repeated inhalation exposures to 144Ce in fused clay particles compared with those seen in Beagle dogs that received a single exposure as young adults. The 36 dogs, divided into four equal groups, are exposed every 8 weeks to achieve the following: to maintain lung burdens of 9 and 4.5 μCi 144Ce/kg body weight in the first and second groups, respectively; to increase the lung burden by 2.5 μCi 144Ce/kg body weight in the third group with each exposure and to expose controls (fourth group) to fused clay containing stable cerium. With these exposure sequences, the 144Ce-exposed dogs will receive increasing or maintained β dose rates in contrast to the steadily decreasing dose rate seen after a single inhalation exposure. Exposures to the first and third groups will produce a cumulative absorbed dose to lung of approximately equal to 35,000 rads and those to the second group will yield approximately equal to 17,000 rads within 2 yr after the first exposure. Single exposure dogs that had died with pulmonary neoplasia when this experiment was initiated had cumulative doses to death of 29,000 to 61,000 rads. Six of the planned 13 exposures have been completed to date. All exposed dogs are surviving and will be maintained for lifespan observation. (U.S.)

  2. 226Ra determination in phosphogypsum by alpha-particle spectrometry

    International Nuclear Information System (INIS)

    A radiochemical method for 226Ra determination by alpha-particle spectrometry in environmental samples has been developed in our laboratory. The method has been validated by measurements in samples with known concentrations of this radionuclide and it has been applied in studies related to 226Ra behaviour in phosphogypsum (the main by-product of producing phosphoric acid from phosphate rocks). (author)

  3. Investigation of advanced materials for fusion alpha particle diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Bonheure, G., E-mail: g.bonheure@fz-juelich.de [Laboratory for Plasma Physics, Association “Euratom-Belgian State”, Royal Military Academy, Avenue de la Renaissance, 30 Kunstherlevinglaan, B-1000 Brussels (Belgium); Van Wassenhove, G. [Laboratory for Plasma Physics, Association “Euratom-Belgian State”, Royal Military Academy, Avenue de la Renaissance, 30 Kunstherlevinglaan, B-1000 Brussels (Belgium); Hult, M.; González de Orduña, R. [Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440 Geel (Belgium); Strivay, D. [Centre Européen d’Archéométrie, Institut de Physique Nucléaire, Atomique et de Spectroscopie, Université de Liège (Belgium); Vermaercke, P. [SCK-CEN, Boeretang, B-2400 Mol (Belgium); Delvigne, T. [DSI SPRL, 3 rue Mont d’Orcq, Froyennes B-7503 (Belgium); Chene, G.; Delhalle, R. [Centre Européen d’Archéométrie, Institut de Physique Nucléaire, Atomique et de Spectroscopie, Université de Liège (Belgium); Huber, A.; Schweer, B.; Esser, G.; Biel, W.; Neubauer, O. [Forschungszentrum Jülich GmbH, Institut für Plasmaphysik, EURATOM-Assoziation, Trilateral Euregio Cluster, D-52425 Jülich (Germany)

    2013-10-15

    Highlights: ► We examine the feasibility of alpha particle measurements in ITER. ► We test advanced material detectors borrowed from the GERDA neutrino experiment. ► We compare experimental results on TEXTOR tokamak with our detector response model. ► We investigate the detector response in ITER full power D–T plasmas. ► Advanced materials show good signal to noise ratio and alpha particle selectivity. -- Abstract: Fusion alpha particle diagnostics for ITER remain a challenging task. Standard escaping alpha particle detectors in present tokamaks are not applicable to ITER and techniques suitable for fusion reactor conditions need further research and development [1,2]. The activation technique is widely used for the characterization of high fluence rates inside neutron reactors. Tokamak applications of the neutron activation technique are already well developed [3] whereas measuring escaping ions using this technique is a novel fusion plasma diagnostic development. Despite low alpha particle fluence levels in present tokamaks, promising results using activation technique combined with ultra-low level gamma-ray spectrometry [4] were achieved before in JET [5,6]. In this research work, we use new advanced detector materials. The material properties beneficial for alpha induced activation are (i) moderate neutron cross-sections (ii) ultra-high purity which reduces neutron-induced background activation and (iii) isotopic tailoring which increases the activation yield of the measured activation product. Two samples were obtained from GERDA[7], an experiment aimed at measuring the neutrinoless double beta decay in {sup 76}Ge. These samples, made of highly pure (9 N) germanium highly enriched to 87% in isotope Ge-76, were irradiated in real D–D fusion plasma conditions inside the TEXTOR tokamak. Comparison of the calculated and the experimentally measured activity shows good agreement. Compared to previously investigated high temperature ceramic material [8

  4. Pressure control and particle`s motion in ALPHA

    CERN Document Server

    Rudakov, Kirill

    2013-01-01

    The first project was a system to control the pressure of water and gas. The second project was the calculation of tracks of particles. The third project was to make an estimation of mutual inductance.

  5. The role of alpha particles in the dynamics of ring-stabilized devices

    International Nuclear Information System (INIS)

    The use of relativistic electron rings to stabilize plasmas against the interchange modes has been utilized in such devices as the Elmo Bumpy Torus (EBT) and the plugs of a Tandem Mirror device (STM). In the EBT case enhanced stability is reflected in higher betas (ratio of plasma to magnetic field pressures), while in the Tandem Mirror case symmetry in the plug magnetic geometry results in reduced particle diffusion across the magnetic field in the central cell. Regardless of the application, the question arises as to what effect would alpha particles generated by the Deuterium-Tritium (DT) reactions have on the stability of such ring-stabilized devices. In this paper the macroscopic stability of such systems is reexamined in order to assess the effect of alphas on the background interchange mode, the interacting interchange mode, and the high frequency compressional Alfven and coupled modes. A fluid description is used for the background plasma while a kinetic treatment is utilized for the hot electron species and alpha particles. It is shown that the alphas tend to mildly destabilize the interacting interchange while stabilizing the background interchange due to their sizeable Larmor radii. The destabilization is most pronounced at high alpha energies i.e., at birth, and near complete recovery of stability is achieved as these particles approach thermalization with the background ions. It is also shown that the alphas completely stabilize the high frequency modes. (orig.)

  6. Skeletal dosimetry models for alpha-particles for use in molecular radiotherapy

    Science.gov (United States)

    Watchman, Christopher J.

    Molecular radiotherapy is a cancer treatment methodology whereby a radionuclide is combined with a biologically active molecule to preferentially target cancer cells. Alpha-particle emitting radionuclides show significant potential for use in molecular radiotherapy due to the short range of the alpha-particles in tissue and their high rates of energy deposition. Current radiation dosimetry models used to assess alpha emitter dose in the skeleton were developed originally for occupational applications. In medical dosimetry, individual variability in uptake, translocation and other biological factors can result in poor correlation of clinical outcome with marrow dose estimates determined using existing skeletal models. Methods presented in this work were developed in response to the need for dosimetry models which account for these biological and patient-specific factors. Dosimetry models are presented for trabecular bone alpha particle dosimetry as well as a model for cortical bone dosimetry. These radiation transport models are the 3D chord-based infinite spongiosa transport model (3D-CBIST) and the chord-based infinite cortical transport model (CBICT), respectively. Absorbed fraction data for several skeletal tissues for several subjects are presented. Each modeling strategy accounts for biological parameters, such as bone marrow cellularity, not previously incorporated into alpha-particle skeletal dosimetry models used in radiation protection. Using these data a study investigating the variability in alpha-particle absorbed fractions in the human skeleton is also presented. Data is also offered relating skeletal tissue masses in individual bone sites for a range of ages. These data are necessary for dose calculations and have previously only been available as whole body tissue masses. A revised 3D-CBIST model is also presented which allows for changes in endosteum thickness to account for revised target cell location of tissues involved in the radiological

  7. The Emission of Long-Range Alpha Particles in Fission

    International Nuclear Information System (INIS)

    Fraenkel and Thompson (1964) have shown that the most probable direction of emission of the long-range alpha particles in the spontaneous fission of californium-252 varies with the ratio of the masses of the residual fission fragments. The angle of emission relative to the direction of motion of the lighter fragment increases significantly as the mass of the lighter fragment decreases. Assuming that the alpha particle is emitted at the scission point, these authors conclude that the scission point, in ternary fission, occurs progressively nearer to the lighter fragment as the fragment mass ratio is greater. They point out that this is one of the assumptions underlying the ''geometrical'' model of mass division of Whetstone (1959) and Vladimirski (1957), and is the feature of that model in terms of which the variation of the average number of neutrons with fragment mass in binary fission is successfully explained. They suggest that these various considerations together indicate that the configuration of the scissioning nucleus at (and before) scission in ternary fission closely resembles the corresponding configuration in binary fission. Adopting this last hypothesis in relation to the thermal-neutron-induced fission of uranium-235, the writer (1964) has shown that if the liberation cf the alpha particle occurs at or just after the moment of scission, so that it may be regarded as emitted from a newly formed, but still deformed, fragment then the probability of emission can be deduced from the experiments of Schmitt et al. (1962), if certain further assumptions are made. On the assumption that the alpha particle is derived from the heavy fragment exclusively, it appears that the prob-ability of release from that fragment correlates directly with the average number of secondary neutrons emitted in in binary fission, and also with the energy available for alpha-particle emission from the undeformed (ground state) fragment. There would be no correlation with the energy

  8. Biological impacts of TiO2 on human lung cell lines A549 and H1299: particle size distribution effects

    International Nuclear Information System (INIS)

    Increasing use of titanium dioxide (TiO2) nanoparticles in many commercial applications has led to emerging concerns regarding the safety and environmental impact of these materials. In this study, we have investigated the biological impact of nano-TiO2 (with particle primary size of 20 nm Aeroxide P25) on human lung cell lines in vitro and also the effect of particle size distribution on the particle uptake and apparent toxicity. The biological impact of nano-TiO2 is shown to be influenced by the concentration and particle size distribution of the TiO2 and the impact was shown to differ between the two cell lines (A549 and H1299) investigated herein. A549 cell line was shown to be relatively resistant to the total amount of TiO2 particles uptaken, as measured by cell viability and metabolic assays, while H1299 had a much higher capacity to ingest TiO2 particles and aggregates, with consequent evidence of impact at concentrations as low as 30–150 μg/mL TiO2. Evidence gathered from this study suggests that both viability and metabolic assays (measuring metabolic and mitochondrial activities and also cellular ATP level) should be carried out collectively to gain a true assessment of the impact of exposure to TiO2 particles.

  9. RPL in alpha particle irradiated Ag+-doped phosphate glass

    International Nuclear Information System (INIS)

    The objective of this study is to investigate the emission mechanism of radiophotoluminescence (RPL) in the Ag+-doped phosphate glass (glass dosimeter), which is now used as individual radiation dosimeter, because the emission mechanism of RPL in glass dosimeter has been not fully understood. We have investigated the assignments and characteristics of the X-ray induced color centers in the Ag+-doped phosphate glass up to now (Miyamoto et al., 2010). Optical properties such as optical absorption spectra related with alpha-particles and X-rays irradiation were measured for commercially available glass dosimeter. In this study optical properties such as optical absorption spectrum as a function of alpha-particles and X-rays irradiation were measured for commercially available glass dosimeter. Comparison of the RPL in Ag+-doped phosphate glass irradiated with alpha-particles and X-rays is discussed. - Highlights: • A Yellow and blue emission are included in the RPL of Ag+-doped phosphate glass. • The ratio of yellow and blue emission was different between alpha and X-ray irradiation. • RPL emission intensity increased in an atmosphere below room temperature

  10. Phoswich Detector for Simultaneous Measuring Alpha/beta Particles

    International Nuclear Information System (INIS)

    The new type phoswich detector consisting of the ZnS(Ag) and plastic scintillator for alpha/beta-ray simultaneous counting was developed for monitoring radiological contamination inside pipes. The detection performance was estimated using the PSD (pulse shape discrimination) method as a function of distance between the scintillator and radioactive source. The attenuation of particles traveling through a thin film for preventing the detector from being contaminated was experimentally estimated. It is concluded from our investigation that the phoswich detector developed can provide a sufficient alpha/beta-ray discrimination. The application of a thin film for preventing the detector from being contaminated was proven to be feasible.

  11. Low energy alpha particle spectroscopy using CR-39 detector

    CERN Document Server

    Izerrouken, M; Ilic, R

    1999-01-01

    The possibility of using CR-39 to measure the depth profile of sup 1 sup 0 B in Si is analysed. The measuring technique exploits the sup 1 sup 0 B(n, alpha) sup 7 Li nuclear reaction. For this reason the track parameters (size, optical properties) of low energy alpha-particles (<1.47 MeV) were studied. The results showed that an energy resolution of about 100 keV could be obtained by an appropriate selection of etching conditions. The profile of sup 1 sup 0 B in Si at a depth as small as 1 mu m can be measured.

  12. Alpha particle emitters in cancer therapy: establishing the rationale and overcoming the difficulties

    International Nuclear Information System (INIS)

    Full text: Once a tumor has metastasized, the possibility of cure is significantly diminished, if not excluded. Since metastatic spread arises due to the release of single tumor cells or tumor cell clusters, treatment regimens following an overt metastasis must include agents that eradicate individual tumor cells and cell clusters or that prevent their dissemination. Alpha particles may be highly effective in eradicating rapidly accessible disease. The effectiveness of alpha particles arises because the amount of energy deposited per unit distance traveled (linear energy transfer or LET) is approximately 400 times greater than that of beta particles (80 keV/μm vs. 0.2 keV/μm). Each traversal of an alpha particle through a cell nucleus results in a very highly ionizing track. Cell survival studies have shown that alpha-particle killing is independent of oxygenation state or cell-cycle during irradiation and that as few as 1 to 6 tracks across the nucleus may result in cell death. Most studies with alpha-particle emitting radionuclides for therapy have examined either bismuth-212 or astatine-211. Both radionuclides are short-lived with 61 minute and 7.2 hour half-lives, respectively, yielding intermediates with 3-minute and 32 year half-lives, respectively. Both emit alpha particles whose range is 40 to 80 μm. Alpha-particle emitting radionuclides have been attached to antibodies against tumor cell associated antigen. Antibodies have been the most widely used vehicle for delivery of alpha particles due to their specificity. Bismuth-212 has demonstrated a significant curative potential with minimal toxicity. In an ascites tumor mouse model, specific targeting and 80% cure following injection of Bi-212-labeled antibody has been observed (Macklis RM et al, Science, 240:1024-1026, 1988). It is important to define the realm of applicability for alpha particle emitting radionuclides. The short half-life of most currently available radionuclides, limits their use to

  13. Alpha particle induced DNA damage and repair in normal cultured thyrocytes of different proliferation status

    DEFF Research Database (Denmark)

    Lyckesvärd, Madeleine Nordén; Delle, Ulla; Kahu, Helena;

    2014-01-01

    Childhood exposure to ionizing radiation increases the risk of developing thyroid cancer later in life and this is suggested to be due to higher proliferation of the young thyroid. The interest of using high-LET alpha particles from Astatine-211 ((211)At), concentrated in the thyroid by the same...... levels of γH2AX decreased during the first 24h in both cycling and stationary cultures and complete repair was seen in all cultures but cycling cells exposed to (211)At. Compared to stationary cells alpha particles were more harmful for cycling cultures, an effect also seen at the pChk2 levels...... cultures at a modest level of damage, clearly demonstrating that cell cycle status influences the relative effectiveness of alpha particles....

  14. Alpha particles for treatment of disseminated melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Link, E.M. [London Univ. (United Kingdom)

    2010-11-15

    Invading melanoma spreads to local and unpredictable distant location at the early stages of its development. It is justifiable, therefore to classify the disease as a systemic disorder. This requires a systemic treatment that reaches all melanoma cells irrespective of whether they are singly dispersed and in circulation or already forming solid tumours of various sizes. Targeted radiotherapy affects directly and selectively cancer cells provided an appropriate radionuclide and its carrier are chosen. Melanoma is a pigmented tumour. Methylene blue (MTB) accumulates selectively in melanoma cells due to its exceptionally high affinity to melanin. MTB serves, therefore, as a carrier for radionuclides. {sup 211}At-MTB has proved to be particularly effective in treating disseminated melanoma when administered systemically and, at the same time, non-toxic to normal non-pigmented and pigmented organs. (author)

  15. Alpha particles for treatment of disseminated melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Link, E.M. [London University (United Kingdom)

    2010-07-01

    Invading melanoma spreads to local and unpredictable distant location at the early stages of its development. It is justifiable, therefore, to classify the disease as a systemic disorder. This requires a systemic treatment that reaches all melanoma cells irrespective of whether they are singly dispersed and in circulation or already forming solid tumours of various sizes. Targeted radiotherapy affects directly and selectively cancer cells provided an appropriate radionuclide and its carrier are chosen. Melanoma is a pigmented tumour. Methylene blue (MTB)) accumulates selectively in melanoma cells due to its exceptionally high affinity to melanin. MTB serves, therefore, as a carrier for radionuclides. {sup 211}At-MTB has proved to be particularly effective in treating disseminated melanoma when administered systemically and, at the same time, non-toxic to normal non-pigmented and pigmented organs. (authors)

  16. The determination of plutonium alpha activity in urine, faeces and biological materials

    International Nuclear Information System (INIS)

    Methods have been developed for the determination of plutonium alpha activity in urine, faeces and biological materials. The chemical stages involved give practically complete separation of all extraneous material from the plutonium, which is electrodeposited on to a 0.5 inch stainless steel disc to produce a thin high resolution source. The limit of detection is 0.025 μμc/sample (sixteen-hour count) when the sources are counted in a small scintillator counter, but is lowest when counted in a counter which counts particles of energy 5.05-5.25 MeV only, and which therefore discriminates against small quantities of α-active materials introduced with the reagents in the final electrodeposition stage of the process. (Any such alpha activity may readily be identified by alpha pulse height analysis). (author)

  17. Alpha particle track coloration in CR-39: Improved observability

    CERN Document Server

    Oezguemues, A

    1999-01-01

    A comparative study of the observability of alpha particle tracks in CR-39 was performed with an optical microscope before and after coloration. The implantation of ink helped in observing the damage zones. At first glance through the microscope, the coloration makes the tracks stand out right away. This coloration is helpful, from the start, in the morphological study of the tracks (size, area, orientation, shape, perimeter). This operation is advantageous in distinguishing the alpha particle tracks from stains or scratches. Thus, the routine counting of the tracks is more easily performed. Consequently, this procedure allowed us: to decrease significantly the standard deviation of the approximate total of the parameters given from the image analysis system (Olympus CUE2); to envision the possibility of reasonably decreasing the etching time in order to limit the loss of information caused by the destruction of the CR-39 during chemical etching and to use a weaker enlarging lens in order to cover a larger fi...

  18. Ripple Loss of Alpha Particles in a Low-Aspect-Ratio Tokamak Reactor

    International Nuclear Information System (INIS)

    Studies on the loss of alpha particles enhanced by toroidal field (TF) ripple in a low-aspect-ratio tokamak reactor (VECTOR) have been made by using an orbit-following Monte-Carlo code. In actual TF coil systems, the ripple loss of alpha particles is strongly reduced as the aspect ratio becomes low (the power loss ∝ A8.8 for A≥2.5) and the reduction of the number of TF coils results in a large amount of ripple loss even in a low-aspect-ratio tokamak. To reduce the number of TF coils from 12 to 6, about 40% of coil size enlargement is necessary in VECTOR. Ferrite plates are very effective to reduce ripple losses of alpha particles. By using ferrite plates, the coil size enlargement for N=6 can be relaxed to 15% and the number of coils can be reduced from 12 to 8 without enlargement of coil size in VECTOR. (author)

  19. A Novel Experiment to Investigate the Attenuation of Alpha Particles in Air

    Science.gov (United States)

    Andrews, D. G. H.

    2008-01-01

    A simple student experiment investigating dependence on air pressure of the attenuation of alpha particles in air is described. An equation giving the pressure needed to absorb all alpha particles of a given energy is derived from the Bethe-Bloch formula. Results are presented for the attenuation of alpha particles from americium 241 and radium…

  20. Effects of Low-Dose Alpha-Particle Irradiation in Human Cells: The Role of Induced Genes and the Bystander Effect. Final Technical Report (9/15/1998-5/31/2005)

    Energy Technology Data Exchange (ETDEWEB)

    Little, John B.

    2013-09-17

    This grant was designed to examine the cellular and molecular mechanisms for the bystander effect of radiation (initially described in this laboratory) whereby damage signals are passed from irradiated to non-irradiated cells in a population. These signals induce genetic effects including DNA damage, mutations and chromosomal aberrations in the nonirradiated cells. Experiments were carried out in cultured mammalian cells, primarily human diploid cells, irradiated with alpha particles. This research resulted in 17 publications in the refereed literature and is described in the Progress Report where it is keyed to the publication list. This project was initiated at the Harvard School of Public Health (HSPH) and continued in collaboration with students/fellows at Colorado State University (CSU) and the New Jersey Medical School (NJMS).

  1. Preliminary Study of Natural Alpha Particle Track Areal Distribution Behind Eyeglasses Obstacles

    International Nuclear Information System (INIS)

    Plastic nuclear track detectors are widely used to register tracks of alpha particles emitted from radon gas nuclei and radioactive daughter nuclei. Eye glasses, finger rings, necklaces and many other accessories intimately accompany most people. The eyeglasses may modify the surface distribution of alpha particle pass spots just behind them. There may be some effects due to the earth's magnetic field on the motion of the charged alpha particle emitters (radon ions). In metallic frames of the eyeglasses, the earth's magnetic field and charged radio-ions enforce free electrons to move setting electric current, which reduces the magnetic field at the frame. Being weak at the frame and stronger on both sides away, the magnetic field lines may form a magnetic trap of some charged radio-ions in the air. The polymer Solid State Nuclear Track Detector (SSNTD) CR-39 which is a polyalyl diglycol carbonate is used to register alpha particles behind the eyeglasses obstacles. Remarkable decrease in alpha track density was noticed in CR-39 registration due both to glass and magnetic screening. The obtained results call for more studies on all metallic tools used or possessed in mines and non-ventilated underground cavities.

  2. Is the increased relative biological effectiveness of high LET particles due to spatial or temporal effects? Characterization and OER in V79-4 cells

    International Nuclear Information System (INIS)

    The efficiency of producing biological damage varies with radiation quality. Conventional explanations rely on spatial differences in the radiation track structure; generally however there are also very large temporal differences in delivery of the radiation at the cellular level. High-LET radiation normally deposits substantial amounts of energy by individual heavily ionizing tracks on a timescale of the order of picoseconds. By contrast each low-LET radiation track deposits a small amount of energy. Many of these tracks, distributed over the whole cell, are required to deliver an equivalent dose to a high-LET track and they are usually delivered over much longer timescales (typically seconds) during which chemical, biochemical and biological processes are occurring. In this paper the design, characterization and initial application of a high-brightness, laser-plasma ultrasoft x-ray source is described. This has been used to investigate the importance of the temporal differences by irradiating mammalian cells with an energy deposition with spatial properties of low-LET radiation and temporal properties similar to high-LET radiation. The present system delivers a typical dose, to the incident surface of the cells, of 0.12 Gy per pulse delivered in <10 ps. The capabilities of the x-ray source were tested by determining the survival of V79-4 hamster cells irradiated with picosecond pulses of ultrasoft x-rays under aerobic and anaerobic conditions, which were found to be consistent with previously published non pulsed data with x-rays of similar energy. These results support the expectation that the disappearance of an oxygen effect for high-LET radiation particles is due to their spatial properties rather than the very short timescale of each particle traversal. For other effects, particularly non-targeted phenomena such as induced genomic instability, expectations may be less clear cut. (author)

  3. Gross {alpha}-particle activities in the ground waters in Western Anatolia

    Energy Technology Data Exchange (ETDEWEB)

    Akyil, S.; Erees, F.S.; Olmez, S. [Ege Universitesi, Izmir (Turkey)

    1996-07-01

    The purpose of this study is to present data on gross {alpha}-particle activity, pH and conductivity in the ground waters in Western Anatolia. The gross {alpha}-particle activities in 27 ground water samples were determined by radiochemical carrier-precipitation methods. The gross {alpha}-particle activities of water samples were measured by using a ZnS (Ag) detector system. Measureable {alpha}-particle activity is present in all ground water samples, with one ground water sample having a gross {alpha}-particle activity > 0.55 Bq/L. (Author).

  4. Alpha-particle Measurements Needed for Burning Plasma Experiments

    International Nuclear Information System (INIS)

    The next major step in magnetic fusion studies will be the construction of a burning plasma (BP) experiment where the goals will be to achieve and understand the plasma behavior with the internal heating provided by fusion-generated alpha particles. Two devices with these physics goals have been proposed: the International Thermonuclear Experimental Reactor (ITER) and the Fusion Ignition Research Experiment (FIRE). Extensive conceptual design work for the instrumentation to try to meet the physics demands has been done for these devices, especially ITER. This article provides a new look at the measurements specifically important for understanding the physics aspects of the alpha particles taking into account two significant events. The first is the completion of physics experiments on the Joint European Torus (JET) and the Tokamak Fusion Test Reactor (TFTR) with deuterium-tritium fueling with the first chances to study alpha physics and the second is the realization that relatively compact plasmas, making use of advanced tokamak plasma concepts, are the most probable route to burning plasmas and ultimately a fusion reactor

  5. Alpha-particle Measurements Needed for Burning Plasma Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kenneth M. Young

    2001-09-26

    The next major step in magnetic fusion studies will be the construction of a burning plasma (BP) experiment where the goals will be to achieve and understand the plasma behavior with the internal heating provided by fusion-generated alpha particles. Two devices with these physics goals have been proposed: the International Thermonuclear Experimental Reactor (ITER) and the Fusion Ignition Research Experiment (FIRE). Extensive conceptual design work for the instrumentation to try to meet the physics demands has been done for these devices, especially ITER. This article provides a new look at the measurements specifically important for understanding the physics aspects of the alpha particles taking into account two significant events. The first is the completion of physics experiments on the Joint European Torus (JET) and the Tokamak Fusion Test Reactor (TFTR) with deuterium-tritium fueling with the first chances to study alpha physics and the second is the realization that relatively compact plasmas, making use of advanced tokamak plasma concepts, are the most probable route to burning plasmas and ultimately a fusion reactor.

  6. The biological response to nanometre-sized polymer particles.

    Science.gov (United States)

    Liu, Aiqin; Richards, Laura; Bladen, Catherine L; Ingham, Eileen; Fisher, John; Tipper, Joanne L

    2015-09-01

    Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1-1.0μm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20nm, 60nm, 200nm and 1.0μm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20nm FluoSpheres had no significant effect on TNF-α, IL-1β, IL-6 and IL-8 release from PBMNCs at a concentration of 100μm(3) particles per cell after 12 and 24h. The micrometre-size UHMWPE wear particles (0.1-1.0μm) and 60nm, 200nm and 1.0μm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages. PMID:26004221

  7. Simulations of alpha particle ripple loss from the International Thermonuclear Experimental Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Redi, M.H.; Budny, R.V.; McCune, D.C.; Miller, C.O.; White, R.B.

    1996-05-01

    Calculations of collisional stochastic ripple loss of alpha particles from the new 20 toroidal field (TF) coil International Thermonuclear Experimental Reactor (ITER) predict small alpha ripple losses, less than 0.4%, close to the loss calculated for the full current operation of the earlier 24 TF coil design. An analytic fit is obtained to the ITER ripple data field demonstrating the nonlinear height dependence of the ripple minimum for D shaped ripple contours. In contrast to alpha loss simulations for the Tokamak Fusion Test Reactor (TFTR), a simple Goldston, White, Boozer stochastic loss criterion ripple loss model is found to require an increased renormalization of the stochastic threshold {delta}{sub s}/{delta}{sub GWB} {ge} 1. Effects of collisions, sawtooth broadening and reversal of the grad B drift direction are included in the particle following simulations.

  8. Simulations of alpha particle ripple loss from the International Thermonuclear Experimental Reactor

    International Nuclear Information System (INIS)

    Calculations of collisional stochastic ripple loss of alpha particles from the new 20 toroidal field (TF) coil International Thermonuclear Experimental Reactor (ITER) predict small alpha ripple losses, less than 0.4%, close to the loss calculated for the full current operation of the earlier 24 TF coil design. An analytic fit is obtained to the ITER ripple data field demonstrating the nonlinear height dependence of the ripple minimum for D shaped ripple contours. In contrast to alpha loss simulations for the Tokamak Fusion Test Reactor (TFTR), a simple Goldston, White, Boozer stochastic loss criterion ripple loss model is found to require an increased renormalization of the stochastic threshold δs/δGWB ≥ 1. Effects of collisions, sawtooth broadening and reversal of the grad B drift direction are included in the particle following simulations

  9. Measurements of DT alpha particle loss near the outer midplane of TFTR

    International Nuclear Information System (INIS)

    Measurements of DT alpha particle loss to the outer midplane region of TFTR have been made using a radially movable scintillator detector. The conclusion from this data is that mechanisms determining the DT alpha loss to the outer midplane are not substantially different from those for DD fusion products. Some of these results are compared with a simplified theoretical model for TF ripple-induced alpha loss, which is expected to be the dominant classical alpha loss mechanism near the outer midplane. An example of plasma-driven MHD-induced alpha particle loss is shown, but no signs of any ''collective'' alpha instability-induced alpha loss have yet been observed

  10. GaN-based PIN alpha particle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guo [Peking University, Shenzhen Graduate School, Guangdong Shenzhen 518055 (China); Peking University, Beijing, 100871 (China); Fu Kai; Yao Changsheng [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Science, Jiangsu Suzhou 215123 (China); Su Dan; Zhang Guoguang [China Institute of Atomic Energy, Beijing 102413 (China); Wang Jinyan [Peking University, Beijing, 100871 (China); Lu Min, E-mail: mlu2006@sinano.ac.cn [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Science, Jiangsu Suzhou 215123 (China)

    2012-01-21

    GaN-based PIN alpha particle detectors are studied in this article. The electrical properties of detectors have been investigated, such as current-voltage (I-V) and capacitance-voltage (C-V). The reverse current of all detectors is in nA range applied at 30 V, which is suitable for detector operation. The charge collection efficiency (CCE) is measured to be approximately 80% but the energy resolution is calculated to be about 40% mostly because the intrinsic layer is not sufficiently thick enough.

  11. Cluster states and alpha particle condensation in 13C

    International Nuclear Information System (INIS)

    The structure of 13C is studied with the semi-microscopic cluster model, 3α+n orthogonality condition model (OCM). The energy spectra of four 1/2- states and three 1/2+ states up to Ex ~ 13 MeV are successfully reproduced, in particular, three monopole transition strengths are in fair agreement with the observed ones. We discuss the cluster states and alpha particle condensation in the 1/2± states appearing around the 12C+n, 9Be+α and 3α+n thresholds. (author)

  12. GaN-based PIN alpha particle detectors

    International Nuclear Information System (INIS)

    GaN-based PIN alpha particle detectors are studied in this article. The electrical properties of detectors have been investigated, such as current-voltage (I-V) and capacitance-voltage (C-V). The reverse current of all detectors is in nA range applied at 30 V, which is suitable for detector operation. The charge collection efficiency (CCE) is measured to be approximately 80% but the energy resolution is calculated to be about 40% mostly because the intrinsic layer is not sufficiently thick enough.

  13. CIT alpha particle extraction and measurement: Low-Z ablation cloud profile simulation for alpha-particle diagnostics

    International Nuclear Information System (INIS)

    In order to determine the expected properties of the ablation cloud of low-Z pellets interacting with a thermonuclear plasma, which in turn is proposed as a charge-neutralization medium for confined alpha particles, a numerical program has been developed. The physical model for this program is based on Park's low-Z pellet-plasma interaction model for the interior of the cloud adjacent to the pellet's surface out to the sonic surface (roughly, a millimeter in separation), and then propagating outward from this region using the conservation laws of enthalpy, momentum, and mass, along with the assumption of charge-state equilibrium. The effects of local heating by the plasma electrons slowing down in the cloud, and ionization of the ablatant material are treated self-consistently in the model. In collaboration with Dr. Paul Parks of General Atomics Corporation, a joint ODU-GAC research plan for modeling low-Z pellet-plasma interactions has been devised, and considerable progress has been made in its implementation. Recently, using a constraint in the ablatant flow, so that it approximates its observed flow along the magnetic field, results from the program were obtained which could be compared with the results from the GAC experiments on TEXT. The predictions of the program are in poor agreement with the TEXT data as to the dimensions of the C+3 region of the cloud along the magnetic field. The failure of the model appears to be the breakdown of the assumption that charge-state equilibrium exists in the cloud. This problem is particularly severe for the TEXT parameters so modifications in the model to include non-equilibrium effects are being implemented

  14. Innershell ionization by fast protons, alpha particles and carbon ions

    International Nuclear Information System (INIS)

    The subject of this thesis is the study of inner-shell excitations of atoms induced by fast charged particle collisions. A new method is described for measuring the spectrum of delta-electrons emitted by 208Pb after excitation by 15 MeV protons or 50 MeV alpha particles. Experimental equipment is described. Results of both experiments are presented and compared with PWBA models and with calculations based on a semi-classical approximation. The small-impact-parameter ionization probabilities obtained are then compared with literature. Also small-impact-parameter measurements done with 100 MeV carbon ions are described. Besides K-shell measurements, the author also presents L-subshell ionization probability results for Pb. An appendix is added in which energy straggling problems in solid targets are treated. (Auth./G.J.P.)

  15. Investigations of electrical properties of structures Al-DNA-ITO-Al exposed to alpha particles

    International Nuclear Information System (INIS)

    The detection of alpha particles and other radiation sources has been an important field of research since the inception of radioactive materials in medical technology approximately a century ago. While different types of radiation sensors exist, in recent history, in light of a few catastrophic nuclear meltdowns, the development of sensors with rapid and effective detection properties have become crucial. To probe the feasibility of incorporating such features into the detector architecture, a simple sensor based on mushroom Deoxyribonucleic acid or DNA (Aluminium (Al)/DNA/Indium Tin Oxide (ITO)) was built, and the possibility of employing DNA electronics for the potential detection of alpha particles was investigated. Current–voltage (I–V) profiles were obtained following radiation using alpha particles at different dosages and exposure periods at room temperature. Properties such as series resistance, RS and other properties (barrier height, ideality factor and hypersensitivity) were calculated and analyzed using Conventional, Cheung and Cheung and Norde methods. RS values of the non-radiated samples calculated using the first method was about 8.6 MΩ. Using Conventional and Norde methods, samples irradiated for 4 min demonstrated the highest RS values of 5.79 and 1.81 MΩ, respectively. The results obtained were used to demonstrate the possibility of applying the sensitivity of DNA sensors to the measurement of alpha radiation. - Highlights: • Freshly prepared DNA solution was deposited as thin films by using the self-assembly method. • Series resistances, barrier heights and ideality factors were determined from I–V measurements. • A novel DNA hypersensitivity phenomenon was observed at low alpha radiation. • DNA based diodes can be employed as sensitive alpha particle sensors

  16. Immersion freezing of biological particles at LACIS

    Science.gov (United States)

    Clauss, T.; Hartmann, S.; Temkiv, T. S.; Augustin, S.; Gosewinkel Karlson, U.; Sahyoun, M. M.; Niedermeier, D.; Wex, H.; Voigtländer, J.; Raddatz, M.; Stratmann, F.

    2012-04-01

    Biological particles, especially bacteria being ubiquitous in the atmosphere, belong to the most efficient ice nuclei (IN) (Möhler, 2008) and hence might have a large impact on weather and climate. In this study, the immersion freezing behavior of different size segregated biological particles is investigated at the laminar flow tube LACIS (Leipzig Aerosol Cloud Interaction Simulator, Hartmann et al., 2011). For these experiments, SNOMAX and outer membrane vesicles (OMV) are used as IN. SNOMAX industrially produced from Pseudomonas-syringae bacteria, which are very ice nucleation active, can be seen as a proxy for ice nucleating bacteria in general. On the surface of these bacteria, ice nucleating proteins that initiate the freezing are situated (Maki et al., 1974). Additionally, it has been found that some ice nucleating bacteria strains have the ability to produce OMV, i.e., strangulated parts of the bacterial cell consisting of the same membrane material (Phelps et al., 1986). These OMV might contain the same ice nucleating proteins on their surface and thus might be able to nucleate ice as well. The OMV used in our experiments were extracted from bacteria cultivated from rain samples collected in Denmark from 30 m height. In our experiments, the biological particles are suspended in air via atomization, size selected by means of a Differential Mobility Particle Sizer, and then fed into LACIS. In LACIS, well defined droplets are produced by activating the biological particles to cloud droplets, so that each droplet contains only one biological particle. By decreasing the temperature in LACIS, these droplets are frozen. To determine the ice fraction, i.e., the fraction of frozen droplets to all particles, the liquid and frozen droplets are distinguished by means of a newly self-built optical device, which is positioned under LACIS, using the depolarization of light scattered by a single particle. The ice fractions are measured as a function of temperature and

  17. Mechanistic model of radon-induced lung cancer risk at low exposure levels based on cellular alpha particle hits

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Hofmann; Hatim, Fakir [Salzburg Univ., Div. of Physics and Biophysics, Dept. of Material Science (Austria); Lucia-Adina, Truta-Popa [Babes-Bolyai Univ., Faculty of Physics (Romania)

    2006-07-01

    To explore the role of the multiplicity of cellular hits by radon progeny alpha particles for lung cancer incidence, the number of single and multiple alpha particle hits were computed for basal and secretory cells in the bronchial epithelium of human airway bifurcations employing Monte Carlo methods. Hot spots of alpha particle hits were observed at the branching points of bronchial airway bifurcations, suggesting that multiple alpha particle hits may occur primarily at carinal ridges. Random alpha particle intersections of bronchial cells during a given exposure period, selected from a Poisson distribution, were simulated by an initiation-promotion model, based on experimentally observed cellular transformation and survival functions. To consider potential bystander effects, which have been observed in cellular in vitro studies, alpha particle interactions were also simulated for larger sensitive target volumes in bronchial epithelium, consisting of a collection of cells. Lung cancer risk simulations indicated that cancer induction for continuous exposures is related to the cycle time of an irradiated cell, thus exhibiting a distinct dose-rate effect. While the dominant role of single hits leads to a linear dose-response relationship at low radon exposure levels, predicted lung cancer risk for a collection of interacting cells exhibits a linear-quadratic response, suggesting that bystander effects, if operating at all under in vivo irradiations, may be restricted to a small number of adjacent cells. (author)

  18. Mechanistic model of radon-induced lung cancer risk at low exposure levels based on cellular alpha particle hits

    International Nuclear Information System (INIS)

    To explore the role of the multiplicity of cellular hits by radon progeny alpha particles for lung cancer incidence, the number of single and multiple alpha particle hits were computed for basal and secretory cells in the bronchial epithelium of human airway bifurcations employing Monte Carlo methods. Hot spots of alpha particle hits were observed at the branching points of bronchial airway bifurcations, suggesting that multiple alpha particle hits may occur primarily at carinal ridges. Random alpha particle intersections of bronchial cells during a given exposure period, selected from a Poisson distribution, were simulated by an initiation-promotion model, based on experimentally observed cellular transformation and survival functions. To consider potential bystander effects, which have been observed in cellular in vitro studies, alpha particle interactions were also simulated for larger sensitive target volumes in bronchial epithelium, consisting of a collection of cells. Lung cancer risk simulations indicated that cancer induction for continuous exposures is related to the cycle time of an irradiated cell, thus exhibiting a distinct dose-rate effect. While the dominant role of single hits leads to a linear dose-response relationship at low radon exposure levels, predicted lung cancer risk for a collection of interacting cells exhibits a linear-quadratic response, suggesting that bystander effects, if operating at all under in vivo irradiations, may be restricted to a small number of adjacent cells. (author)

  19. Alpha particle track coloration in CR-39: Improved observability

    International Nuclear Information System (INIS)

    A comparative study of the observability of alpha particle tracks in CR-39 was performed with an optical microscope before and after coloration. The implantation of ink helped in observing the damage zones. At first glance through the microscope, the coloration makes the tracks stand out right away. This coloration is helpful, from the start, in the morphological study of the tracks (size, area, orientation, shape, perimeter). This operation is advantageous in distinguishing the alpha particle tracks from stains or scratches. Thus, the routine counting of the tracks is more easily performed. Consequently, this procedure allowed us: to decrease significantly the standard deviation of the approximate total of the parameters given from the image analysis system (Olympus CUE2); to envision the possibility of reasonably decreasing the etching time in order to limit the loss of information caused by the destruction of the CR-39 during chemical etching and to use a weaker enlarging lens in order to cover a larger field of observation for the counting operations

  20. The effect of dimethyl sulfoxide on the induction of DNA double-strand breaks in V79-4 mammalian cells by alpha particles

    International Nuclear Information System (INIS)

    The present study was undertaken to assess the protective effect of dimethyl sulfoxide (DMSO) against the induction and rejoining of DNA double-strand breaks (DSBs) and inactivation of V79-4 Chinese hamster cells by both high- and low-linear energy transfer (LET) radiations. The cells were exposed under aerobic conditions as monolayers to either low-LET photons (60Co γ rays) or high-LET α particles (238Pu) at 277 K. The initial yield of DSBs, determined by elution under nondenaturing conditions, is linearly dependent on dose. When the irradiation was carried out in the presence of DMSO (0-0.6 mol dm-3), the initial yields of DSBs induced by both γ and α-particle irradiation decrease. With γ irradiation at [DMSO]>0.6 mol dm-3, a further decrease in the yield of DSBs by 50 ± 5% and 32 ± 4% for photons and α-particle irradiation with protection factors of 1.7 and 1.4, respectively, for survival and 2.0 and 1.5, respectively, for DSBs. After incubation of the irradiated cells for 3 h at 310K after high-LET irradiation, the residual yield of DSBs is reduced by -3 DMSO. With γ irradiation in the presence of 0.5 mol dm-3 DMSO, 90% of the DSBs are rejoined by 3 h incubation at 310 K. Therefore, the nonscavengeable DSBs induced by α particles are not significantly rejoined within 3 h, in contrast to rejoining of the majority of the nonscavengeable DSBs induced by γ irradiation. From comparison of the data on DSBs and survival for α-particle irradiation, it is inferred that the severity of damage is reduced by DMSO through minimizing the formation of OH-induced sugar/base modifications in the vicinity of nonscavengeable DSBs. 47 refs., 5 figs

  1. CIT alpha particle extraction and measurement: Low-Z ablation cloud profile simulation for alpha-particle diagnostics

    International Nuclear Information System (INIS)

    In order to determine the expected properties of the ablation cloud of low-Z pellets interacting with a thermonuclear plasma, which in turn is proposed as a charge-neutralization medium for confined alpha particles, a numerical program has been developed. The physical model for this program is based on Parks' low-Z pellet-plasma interaction model for the interior of the cloud adjacent to the pellet's surface out to the sonic surface (roughly, a millimeter in separation) and then propagating outward from this region using the conservation laws of enthalpy, momentum, and mass, along with the assumption of charge-state equilibrium. The effects of local heating by the plasma electrons slowing down in the cloud, and ionization of the ablatant material are treated self-consistently in the model. In collaboration with Dr. Paul Parks of General Atomics Corporation, a joint ODU-GAC research plan for modeling low-Z pellet-plasma interactions has been devised, and considerable progress has been made in its implementation. Recently, using a constraint in the ablatant flow, results from the program were obtained which could be compared with the results from the GAC experiments on TEXT. The predictions of the program are in pretty good agreement with the TEXT data as to the dimensions of the C+3 region of the cloud along the magnetic field. Also a small improvement has been made in the low-Z pellet plasma-penetration program, which brings the predictions of the model in closer agreement with the carbon pellet injection experiments on TFTR. 22 refs., 3 figs

  2. Fokker Planck kinetic modeling of suprathermal alpha-particles in a fusion plasma

    CERN Document Server

    Peigney, Benjamin-Edouard; Tikhonchuk, Vladimir

    2014-01-01

    We present an ion kinetic model describing the ignition and burn of the deuterium-tritium fuel of inertial fusion targets. The analysis of the underlying physical model enables us to develop efficient numerical methods to simulate the creation, transport and collisional relaxation of fusion reaction products (alpha-particles) at a kinetic level. A two-energy-scale approach leads to a self-consistent modeling of the coupling between suprathermal alpha-particles and the thermal bulk of the imploding plasma. This method provides an accurate numerical treatment of energy deposition and transport processes involving suprathermal particles. The numerical tools presented here are validated against known analytical results. This enables us to investigate the potential role of ion kinetic effects on the physics of ignition and thermonuclear burn in inertial confinement fusion schemes.

  3. Stability of the Global Alfven Eigenmode in the presence of fusion alpha particles in an ignited tokamak plasma

    International Nuclear Information System (INIS)

    The stability of the Global Alfven Eigenmodes is investigated in the presence of super-Alfvenic energetic particles, such as the fusion-product alpha particles in an ignited deuterium-tritium tokamak plasma. Alpha particles tend to destabilize these modes when ω*α > ωA, where ωA is the shear-Alfven modal frequency and ω*α is the alpha particle diamagnetic drift frequency. This destabilization due to alpha particles is found to be significantly enhanced when the alpha particles are modeled with a slowing-down distribution function rather than with a Maxwellian. However, previously neglected electron damping due to the magnetic curvature drift is found to be comparable in magnitude to the destabilizing alpha particle term. Furthermore, the effects of toroidicity are also found to be stabilizing, since the intrinsic toroidicity induces poloidal mode coupling, which enhances the parallel electron damping from the sideband shear-Alfven Landau resonance. In particular, for the parameters of the proposed Compact Ignition Tokamak, the Global Alfven Eigenmodes are found to be completely stabilized by either the electron damping that enters through the magnetic curvature drift or the damping introduced by finite toroidicity. 29 refs., 8 figs., 1 tab

  4. Mapping alpha-Particle X-Ray Fluorescence Spectrometer (Map-X)

    Science.gov (United States)

    Blake, D. F.; Sarrazin, P.; Bristow, T.

    2014-01-01

    Many planetary surface processes (like physical and chemical weathering, water activity, diagenesis, low-temperature or impact metamorphism, and biogenic activity) leave traces of their actions as features in the size range 10s to 100s of micron. The Mapping alpha-particle X-ray Spectrometer ("Map-X") is intended to provide chemical imaging at 2 orders of magnitude higher spatial resolution than previously flown instruments, yielding elemental chemistry at or below the scale length where many relict physical, chemical, and biological features can be imaged and interpreted in ancient rocks.

  5. A Feasibility Study of a Portable Alpha Particle Spectrometer

    International Nuclear Information System (INIS)

    Alpha spectroscopy is widely used for detecting undeclared nuclear facilities, activities, and materials. Due to the heavy equipment required to carry out this technique, its applications is limited. With the goal of quickly and efficiently responding to undeclared nuclear facilities, activities, and materials, the present authors have designed and built a portable α-particle spectrometer. This study was conducted in order to develop a new portable α-particle spectrometer with the purpose of detecting undeclared nuclear facilities, activities, and materials on site quickly and efficiently. All heavy and large components, which are typically required for a laboratory such as a αparticle spectrometry system, were minimized and placed in a small container with a weight of 14 kg and a size of 30 cm x 30 cm x 30 cm. In the feasibility study, the calculated enrichment values of 235U obtained from the portable α-particle spectrometer were 1.868 % and 3.083 %, similar to the results from a commercial spectrometry system used in laboratories, 2.049 % and 3.253 %. These differences were possibly caused by different channel setups for each system

  6. A Comparitive Assessement of Cytokine Expression in Human-Derived Cell Lines Exposed to Alpha Particles and X-Rays

    Directory of Open Access Journals (Sweden)

    Vinita Chauhan

    2012-01-01

    Full Text Available Alpha- (α- particle radiation exposure has been linked to the development of lung cancer and has been identified as a radiation type likely to be employed in radiological dispersal devices. Currently, there exists a knowledge gap concerning cytokine modulations associated with exposure to α-particles. Bio-plex technology was employed to investigate changes in proinflammatory cytokines in two human-derived cell lines. Cells were irradiated at a dose of 1.5 Gy to either α-particles or X-rays at equivalent dose rates. The two cell lines exhibited a unique pattern of cytokine expression and the response varied with radiation type. Of the 27 cytokines assessed, only vascular endothelin growth factor (VEGF was observed to be modulated in both cell lines solely after α-particle exposure, and the expression of VEGF was shown to be dose responsive. These results suggest that certain proinflammatory cytokines may be involved in the biological effects related to α- particle exposure and the responses are cell type and radiation type specific.

  7. Nuclear reactions induced by high-energy alpha particles

    Science.gov (United States)

    Shen, B. S. P.

    1974-01-01

    Experimental and theoretical studies of nuclear reactions induced by high energy protons and heavier ions are included. Fundamental data needed in the shielding, dosimetry, and radiobiology of high energy particles produced by accelerators were generated, along with data on cosmic ray interaction with matter. The mechanism of high energy nucleon-nucleus reactions is also examined, especially for light target nuclei of mass number comparable to that of biological tissue.

  8. Alpha particle losses from Tokamak Fusion Test Reactor deuterium-tritium plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Darrow, D.S.; Zweben, S.J. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Batha, S. [Fusion Physics and Technology, Torrance, CA (United States)

    1996-01-01

    Because alpha particle losses can have a significant influence on tokamak reactor viability, the loss of deuterium-tritium alpha particles from the Tokamak Fusion Test Reactor (TFTR) has been measured under a wide range of conditions. In TFTR, first orbit loss and stochastic toroidal field ripple diffusion are always present. Other losses can arise due to magnetohydrodynamic instabilities or due to waves in the ion cyclotron range of frequencies. No alpha particle losses have yet been seen due to collective instabilities driven by alphas. Ion Bernstein waves can drive large losses of fast ions from TFTR, and details of those losses support one element of the alpha energy channeling scenario.

  9. Alpha particle losses from Tokamak Fusion Test Reactor deuterium-tritium plasmas

    International Nuclear Information System (INIS)

    Because alpha particle losses can have a significant influence on tokamak reactor viability, the loss of deuterium-tritium alpha particles from the Tokamak Fusion Test Reactor (TFTR) has been measured under a wide range of conditions. In TFTR, first orbit loss and stochastic toroidal field ripple diffusion are always present. Other losses can arise due to magnetohydrodynamic instabilities or due to waves in the ion cyclotron range of frequencies. No alpha particle losses have yet been seen due to collective instabilities driven by alphas. Ion Bernstein waves can drive large losses of fast ions from TFTR, and details of those losses support one element of the alpha energy channeling scenario

  10. Differential Superiority of Heavy Charged-Particle Irradiation to X-Rays: Studies on Biological Effectiveness and Side Effect Mechanisms in Multicellular Tumor and Normal Tissue Models.

    Science.gov (United States)

    Walenta, Stefan; Mueller-Klieser, Wolfgang

    2016-01-01

    This review is focused on the radiobiology of carbon ions compared to X-rays using multicellular models of tumors and normal mucosa. The first part summarizes basic radiobiological effects, as observed in cancer cells. The second, more clinically oriented part of the review, deals with radiation-induced cell migration and mucositis. Multicellular spheroids from V79 hamster cells were irradiated with X-rays or carbon ions under ambient or restricted oxygen supply conditions. Reliable oxygen enhancement ratios could be derived to be 2.9, 2.8, and 1.4 for irradiation with photons, (12)C(+6) in the plateau region, and (12)C(+6) in the Bragg peak, respectively. Similarly, a relative biological effectiveness of 4.3 and 2.1 for ambient pO2 and hypoxia was obtained, respectively. The high effectiveness of carbon ions was reflected by an enhanced accumulation of cells in G2/M and a dose-dependent massive induction of apoptosis. These data clearly show that heavy charged particles are more efficient in sterilizing tumor cells than conventional irradiation even under hypoxic conditions. Clinically relevant doses (3 Gy) of X-rays induced an increase in migratory activity of U87 but not of LN229 or HCT116 tumor cells. Such an increase in cell motility following irradiation in situ could be the source of recurrence. In contrast, carbon ion treatment was associated with a dose-dependent decrease in migration with all cell lines and under all conditions investigated. The radiation-induced loss of cell motility was correlated, in most cases, with corresponding changes in β1 integrin expression. The photon-induced increase in cell migration was paralleled by an elevated phosphorylation status of the epidermal growth factor receptor and AKT-ERK1/2 pathway. Such a hyperphosphorylation did not occur during (12)C(+6) irradiation under all conditions registered. Comparing the gene toxicity of X-rays with that of particles using the γH2AX technique in organotypic cultures of the oral

  11. Differential Superiority of Heavy Charged-Particle Irradiation to X-Rays: Studies on Biological Effectiveness and Side Effect Mechanisms in Multicellular Tumor and Normal Tissue Models

    Science.gov (United States)

    Walenta, Stefan; Mueller-Klieser, Wolfgang

    2016-01-01

    This review is focused on the radiobiology of carbon ions compared to X-rays using multicellular models of tumors and normal mucosa. The first part summarizes basic radiobiological effects, as observed in cancer cells. The second, more clinically oriented part of the review, deals with radiation-induced cell migration and mucositis. Multicellular spheroids from V79 hamster cells were irradiated with X-rays or carbon ions under ambient or restricted oxygen supply conditions. Reliable oxygen enhancement ratios could be derived to be 2.9, 2.8, and 1.4 for irradiation with photons, 12C+6 in the plateau region, and 12C+6 in the Bragg peak, respectively. Similarly, a relative biological effectiveness of 4.3 and 2.1 for ambient pO2 and hypoxia was obtained, respectively. The high effectiveness of carbon ions was reflected by an enhanced accumulation of cells in G2/M and a dose-dependent massive induction of apoptosis. These data clearly show that heavy charged particles are more efficient in sterilizing tumor cells than conventional irradiation even under hypoxic conditions. Clinically relevant doses (3 Gy) of X-rays induced an increase in migratory activity of U87 but not of LN229 or HCT116 tumor cells. Such an increase in cell motility following irradiation in situ could be the source of recurrence. In contrast, carbon ion treatment was associated with a dose-dependent decrease in migration with all cell lines and under all conditions investigated. The radiation-induced loss of cell motility was correlated, in most cases, with corresponding changes in β1 integrin expression. The photon-induced increase in cell migration was paralleled by an elevated phosphorylation status of the epidermal growth factor receptor and AKT-ERK1/2 pathway. Such a hyperphosphorylation did not occur during 12C+6 irradiation under all conditions registered. Comparing the gene toxicity of X-rays with that of particles using the γH2AX technique in organotypic cultures of the oral mucosa, the

  12. Electronic Properties of DNA-Based Schottky Barrier Diodes in Response to Alpha Particles

    Directory of Open Access Journals (Sweden)

    Hassan Maktuff Jaber Al-Ta'ii

    2015-05-01

    Full Text Available Detection of nuclear radiation such as alpha particles has become an important field of research in recent history due to nuclear threats and accidents. In this context; deoxyribonucleic acid (DNA acting as an organic semiconducting material could be utilized in a metal/semiconductor Schottky junction for detecting alpha particles. In this work we demonstrate for the first time the effect of alpha irradiation on an Al/DNA/p-Si/Al Schottky diode by investigating its current-voltage characteristics. The diodes were exposed for different periods (0–20 min of irradiation. Various diode parameters such as ideality factor, barrier height, series resistance, Richardson constant and saturation current were then determined using conventional, Cheung and Cheung’s and Norde methods. Generally, ideality factor or n values were observed to be greater than unity, which indicates the influence of some other current transport mechanism besides thermionic processes. Results indicated ideality factor variation between 9.97 and 9.57 for irradiation times between the ranges 0 to 20 min. Increase in the series resistance with increase in irradiation time was also observed when calculated using conventional and Cheung and Cheung’s methods. These responses demonstrate that changes in the electrical characteristics of the metal-semiconductor-metal diode could be further utilized as sensing elements to detect alpha particles.

  13. A novel experiment to investigate the attenuation of alpha particles in air

    International Nuclear Information System (INIS)

    A simple student experiment investigating dependence on air pressure of the attenuation of alpha particles in air is described. An equation giving the pressure needed to absorb all alpha particles of a given energy is derived from the Bethe-Bloch formula. Results are presented for the attenuation of alpha particles from americium 241 and radium 226. The experimental results are in close agreement with the theoretical predictions

  14. New alpha particle counter based on micro-pixel avalanche photodiode

    International Nuclear Information System (INIS)

    Full text : The main goal of this work is study of possibility to detect alpha particles with micro-pixel avalanche photodiode which has very thin active volume. The obtained results show that alpha detectors based on the micro-pixel avalanche photodiodes can be used as alpha particle counter in many experiments : public security, radioactive contamination monitoring in various environments and detection of charged particles from nuclear reactions

  15. The Influence of Shielding on the Biological Effectiveness of Accelerated Particles for the Induction of Chromosome Damage

    Science.gov (United States)

    Goeorge, Kerry; Cucinotta, Francis A.

    2007-01-01

    Chromosome damage was assessed in human peripheral blood lymphocytes after in vitro exposure to the either Si-28 (490 or 600 MeV/n), Ti-48 (1000 MeV/n), or Fe-56 (600, 1000, or 5000 MeV/n). LET values for these ions ranged from 51 to 184 keV/micron and doses ranged from 10 to 200 cGy. The effect of either aluminum or polyethylene shielding on the induction of chromosome aberrations was investigated for each ion. Chromosome exchanges were measured using fluorescence in situ hybridization (FISH) with whole chromosome probes in cells collected at G2 and mitosis in first division post irradiation after chromosomes were prematurely condensed using calyculin-A. The yield of chromosomal aberrations increased linearly with dose and the relative biological effectiveness (RBE) for the primary beams, estimated from the initial slope of the dose response curve for total chromosomal exchanges with respect to gamma-rays, ranged from 9 to 35. The RBE values increased with LET, reaching a maximum for the 600 MeV/n Fe ions with LET of 184 keV/micron. When the LET of the primary beam was below approximately 100 keV/micron, the addition of shielding material increased the effectiveness per unit dose. Whereas shielding decreased the effectiveness per unit dose when the LET of primary beams was higher than 100 keV/micron. The yield of aberrations correlated with the dose-average LET of the beam after traversal through the shielding.

  16. Collisional stochastic ripple diffusion of alpha particles and beam ions on TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Redi, M.H.; Zarnstorff, M.C,; White, R.B.; Budny, R.V.; Schivell, J.F.; Scott, S.D.; Zweben, S.J.

    1994-09-01

    Predictions for ripple loss of fast ions from TFTR are investigated with a guiding center including both collisional and ripple effects. Discrepancies between measurements and calculations of plasma beta at low current and large major radius are resolved when both effects are included for neutral beam ions. A synergistic enhancement of fast ion diffusion is found for toroidal field ripple with collisions. S = 5.4 for neutral beam ions and S = 1.4--2.4 for alpha particles. A 20--30% reduction in alpha particle heating is predicted for R = 2.6 m DT plasmas on TFTR due to first orbit and collisional stochastic ripple diffusion, although these losses will be reduced if q{sub a} and R are smaller, as for most planned DT experiments.

  17. Collisional stochastic ripple diffusion of alpha particles and beam ions on TFTR

    International Nuclear Information System (INIS)

    Predictions for ripple loss of fast ions from TFTR are investigated with a guiding center including both collisional and ripple effects. Discrepancies between measurements and calculations of plasma beta at low current and large major radius are resolved when both effects are included for neutral beam ions. A synergistic enhancement of fast ion diffusion is found for toroidal field ripple with collisions. S = 5.4 for neutral beam ions and S = 1.4--2.4 for alpha particles. A 20--30% reduction in alpha particle heating is predicted for R = 2.6 m DT plasmas on TFTR due to first orbit and collisional stochastic ripple diffusion, although these losses will be reduced if qa and R are smaller, as for most planned DT experiments

  18. Control of alpha particle transport by spatially inhomogeneous ion cyclotron resonance heating

    International Nuclear Information System (INIS)

    Control of the radial alpha particle transport by using Ion Cyclotron Range of Frequency waves is investigated in a large-aspect-ratio tokamak geometry. It is shown that spatially inhomogeneous ICRF-wave energy with properly selected frequencies and wave numbers can induce fast convective transport of alpha particles at the speed of order υalpha ∼ (PRF/nαε0) ρp, where PRF is the ICRF-wave power density, nα is the alpha density, ε0 is the alpha birth energy, and ρp is the poloidal gyroradius of alpha particles at the birth energy. Application to ITER plasmas is studied and possible antenna designs to control alpha particle flux are discussed. 8 refs., 3 figs

  19. New concept for a wall detector for alpha particles

    International Nuclear Information System (INIS)

    A new concept for a wall-mounted detector is described here that would measure D-T alpha flux and corresponding pitch angle distribution in tokamaks (or related toroidal devices). The sensing element is a conical Micro Channel Ring (MCR) coated with 1 to 2μ of ZnS scintillator (or possibly ZnO). The collimation of the α particles is provided by two circumferential slots at the wall surface. The alpha scintillation events on the MCR are transferred through the ring channels and coupled fiber optics bundle to an external processor. From the magnetic field vector at a given point on the device wall, a certain relation can be set up between the α-induced scintillation position on the MCR and its original pitch angle (i.e., the angle between the α emission from the fusion reaction and the magnetic field vector) which is equal to the local pitch angle since the wall α flux is dominated by prompt losses

  20. Detection of lost alpha particle by concealed lost ion probe

    International Nuclear Information System (INIS)

    Full orbit-following calculation is performed for the final orbit of the lost alpha particles, showing some orbits escaping from the last closed flux surface could be detected by a concealed lost ion probe (CLIP) installed under the shadow of the original first wall surface. While both passing and trapped orbits hit the same wall panel, detecting a trapped orbit by the CLIP is easier than detecting passing orbits. Whether the final orbit is detected or not is determined by the position of the reflection point. The CLIP successfully detects the trapped orbits, which are reflected before they hit to a first wall. Then the pitch angles of the orbits at the CLIP are close to and smaller than 90 deg. Optimization of the position of the CLIP in terms of broader detection window is investigated.

  1. Energetic particle effects on global MHD modes

    International Nuclear Information System (INIS)

    The effects of energetic particles on MHD type modes are studied by analytical theories and the nonvariational kinetic-MHD stability code (NOVA-K). In particular we address the problems of (1) the stabilization of ideal MHD internal kink modes and the excitation of resonant ''fishbone'' internal modes and (2) the alpha particle destabilization of toroidicity-induced Alfven eigenmodes (TAE) via transit resonances. Analytical theories are presented to help explain the NOVA-K results. For energetic trapped particles generated by neutral-beam injection (NBI) or ion cyclotron resonant heating (ICRH), a stability window for the n=1 internal kink mode in the hot particle beat space exists even in the absence of core ion finite Larmor radius effect (finite ω*i). On the other hand, the trapped alpha particles are found to resonantly excite instability of the n=1 internal mode and can lower the critical beta threshold. The circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha particle pressure. 23 refs., 5 figs

  2. Alpha particle destabilization of the toroidicity-induced Alfven eigenmodes

    International Nuclear Information System (INIS)

    The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped α-particles through the wave-particle resonances. Satisfying the resonance condition requires that the α-particle birth speed vα ≥ vA/2|m-nq|, where vA is the Alfven speed, m is the poloidal model number, and n is the toroidal mode number. To destabilize the TAE modes, the inverse Landau damping associated with the α-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the α-particles and the core electrons and ions. The growth rate was studied analytically with a perturbative formula derived from the quadratic dispersion relation, and numerically with the aid of the NOVA-K code. Stability criteria in terms of the α-particle beta βα, α-particle pressure gradient parameter (ω*/ωA) (ω* is the α-particle diamagnetic drift frequency), and (vα/vA) parameters will be presented for TFTR, CIT, and ITER tokamaks. The volume averaged α-particle beta threshold for TAE instability also depends sensitively on the core electron and ion temperature. Typically the volume averaged α-particle beta threshold is in the order of 10-4. Typical growth rates of the n=1 TAE mode can be in the order of 10-2ωA, where ωA=vA/qR. Other types of global Alfven waves are stable in D-T tokamaks due to toroidal coupling effects

  3. Turbulent transport of MeV range cyclotron heated minorities as compared to alpha particles

    CERN Document Server

    Pusztai, István; Kazakov, Yevgen O; Fülöp, Tünde

    2016-01-01

    We study the turbulent transport of an ion cyclotron resonance heated (ICRH), MeV range minority ion species in tokamak plasmas. Such highly energetic minorities, which can be produced in the three ion minority heating scheme [Ye. O. Kazakov et al. (2015) Nucl. Fusion 55, 032001], have been proposed to be used to experimentally study the confinement properties of fast ions without the generation of fusion alphas. We compare the turbulent transport properties of ICRH ions with that of fusion born alpha particles. Our results indicate that care must be taken when conclusions are drawn from experimental results: While the effect of turbulence on these particles is similar in terms of transport coefficients, differences in their distribution functions - ultimately their generation processes - make the resulting turbulent fluxes different.

  4. Biological effectiveness of antiproton annihilation

    CERN Document Server

    Holzscheiter, Michael H.; Bassler, Niels; Beyer, Gerd; De Marco, John J.; Doser, Michael; Ichioka, Toshiyasu; Iwamoto, Keisuke S.; Knudsen, Helge V.; Landua, Rolf; Maggiore, Carl; McBride, William H.; Møller, Søren Pape; Petersen, Jorgen; Smathers, James B.; Skarsgard, Lloyd D.; Solberg, Timothy D.; Uggerhøj, Ulrik I.; Withers, H.Rodney; Vranjes, Sanja; Wong, Michelle; Wouters, Bradly G.

    2004-01-01

    We describe an experiment designed to determine whether or not the densely ionizing particles emanating from the annihilation of antiprotons produce an increase in “biological dose” in the vicinity of the narrow Bragg peak for antiprotons compared to protons. This experiment is the first direct measurement of the biological effects of antiproton annihilation. The experiment has been approved by the CERN Research Board for running at the CERN Antiproton Decelerator (AD) as AD-4/ACE (Antiproton Cell Experiment) and has begun data taking in June of 2003. The background, description and the current status of the experiment are given.

  5. EFFECT OF PARTICLE SIZE AND AERATION ON THE BIOLOGICAL DELIGNIFICATION OF CORN STRAW USING Trametes sp 44

    OpenAIRE

    Samuel Quintanar Gómez,; Ainhoa Arana Cuenca; Yuridia Mercado Flores; Jorge Noel Gracida Rodríguez,; Alejandro Téllez Jurado

    2011-01-01

    Straw is an agricultural byproduct that can be utilized to obtain bioethanol without affecting animal or human sustinence. This process involves recovering the sugars and reducing the lignin content present through the use of ligninolytic fungi such as the basidiomycete Trametes sp. 44. Fermentation was carried out using particle sizes 4 (4.76 mm, No. 4 sieve) and 8 (2.30 mm, No. 8 sieve), and two velocities of airflow (100 and 200 mL/min). Study results showed that particle size affected the...

  6. Bond scission cross sections for alpha-particles in cellulose nitrate (LR115)

    CERN Document Server

    Barillon, R; Chambaudet, A; Katz, R; Stoquert, J P; Pape, A

    1999-01-01

    Chemical damage created by alpha-particles in cellulose nitrate (LR115) have been studied by infrared spectroscopy. This technique enables identifying the sensitive bonds and giving an order of magnitude of their scission cross sections for given alpha-particle energies. The high cross sections observed suggest a new description of the track etch velocity in this material.

  7. Computation and measurement of differential ranges of low-energy alpha particles in matter

    International Nuclear Information System (INIS)

    The stopping power formula of Bethe is discussed and is used to compute differential ranges of low-energy alpha particles in air, argon, aluminium and copper. A single radioactive source containing three active elements is used in experiments to measure the differential ranges in these materials. Finally a range-energy relationship for the alpha particles in air is deduced. (author)

  8. Simulation of Alpha Particles in Rotating Plasma Interacting with a Stationary Ripple

    Energy Technology Data Exchange (ETDEWEB)

    Abraham J. Fetterman and Nathaniel J. Fisch

    2011-01-11

    Superthermal ExB rotation can provide magnetohydrodynamic (MHD) stability and enhanced confinement to axisymmetric mirrors. However, the rotation speed has been limited by phenomena at end electrodes. A new prediction is that rotation might instead be produced using a magnetic ripple and alpha particle kinetic energy, in an extension of the alpha channeling concept. The interaction of alpha particles with the ripple results in visually interesting and practically useful orbits.

  9. Simulation of Alpha Particles in Rotating Plasma Interacting with a Stationary Ripple

    International Nuclear Information System (INIS)

    Superthermal ExB rotation can provide magnetohydrodynamic (MHD) stability and enhanced confinement to axisymmetric mirrors. However, the rotation speed has been limited by phenomena at end electrodes. A new prediction is that rotation might instead be produced using a magnetic ripple and alpha particle kinetic energy, in an extension of the alpha channeling concept. The interaction of alpha particles with the ripple results in visually interesting and practically useful orbits.

  10. Alpha-Calcitonin Gene-Related Peptide Can Reverse The Catabolic Influence Of UHMWPE Particles On RANKL Expression In Primary Human Osteoblasts

    Directory of Open Access Journals (Sweden)

    Max D. Kauther, Jie Xu, Christian Wedemeyer

    2010-01-01

    Full Text Available Background and purpose: A linkage between the neurotransmitter alpha-calcitonin gene-related peptide (alpha-CGRP and particle-induced osteolysis has been shown previously. The suggested osteoprotective influence of alpha-CGRP on the catabolic effects of ultra-high molecular weight polyethylene (UHMWPE particles is analyzed in this study in primary human osteoblasts. Methods: Primary human osteoblasts were stimulated by UHMWPE particles (cell/particle ratios 1:100 and 1:500 and different doses of alpha-CGRP (10-7 M, 10-9 M, 10-11 M. Receptor activator of nuclear factor-κB ligand (RANKL and osteoprotegerin (OPG mRNA expression and protein levels were measured by RT-PCR and Western blot. Results: Particle stimulation leads to a significant dose-dependent increase of RANKL mRNA in both cell-particle ratios and a significant down-regulation of OPG mRNA in cell-particle concentrations of 1:500. A significant depression of alkaline phosphatase was found due to particle stimulation. Alpha-CGRP in all tested concentrations showed a significant depressive effect on the expression of RANKL mRNA in primary human osteoblasts under particle stimulation. Comparable reactions of RANKL protein levels due to particles and alpha-CGRP were found by Western blot analysis. In cell-particle ratios of 1:100 after 24 hours the osteoprotective influence of alpha-CGRP reversed the catabolic effects of particles on the RANKL expression. Interpretation: The in-vivo use of alpha-CGRP, which leads to down-regulated RANKL in-vitro, might inhibit the catabolic effect of particles in conditions of particle induced osteolysis.

  11. Feasibility study on the use of polyallyldiglycol-carbonate cell dishes in TUNEL assay for alpha particle radiobiological experiments

    Science.gov (United States)

    Chan, K. F.; Yum, E. H. W.; Wan, C. K.; Fong, W. F.; Yu, K. N.

    2007-08-01

    In the present work, we have studied the feasibility of a method based on polyallyldiglycol-carbonate (PADC) films to investigate the effects of alpha particles on HeLa cervix cancer cells. Thin PADC films with thickness of about 20 μm were prepared from commercially available CR-39 films by chemical etching to fabricate custom-made petri dishes for cell culture, which could accurately record alpha particle hit positions. A special method involving "base tracks" for aligning the images of cell nuclei and alpha particle hits has been proposed, so that alpha particle transversals of cell nuclei can be visually counted. Radiobiological experiments were carried out to induce DNA damages, with the TdT-mediated d UTP Nick- End Labeling (TUNEL) fluorescence method employed to detect DNA strand breaks. The staining results were investigated by flow cytometer. The preliminary results showed that more strand breaks occurred in cells hit by alpha particles with lower energies. Moreover, large TUNEL positive signals were obtained even with small percentages of cells irradiated and TUNEL signals were also obtained from non-targeted cells. These provided evidence for the bystander effect.

  12. Feasibility study on the use of polyallyldiglycol-carbonate cell dishes in TUNEL assay for alpha particle radiobiological experiments

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K.F. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Yum, E.H.W. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Wan, C.K. [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Fong, W.F. [Research and Development Division, School of Chinese Medicine, Hong Kong Baptist University, Baptist University Road, Kowloon Tong, Hong Kong (China); Yu, K.N. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)]. E-mail: peter.yu@cityu.edu.hk

    2007-08-15

    In the present work, we have studied the feasibility of a method based on polyallyldiglycol-carbonate (PADC) films to investigate the effects of alpha particles on HeLa cervix cancer cells. Thin PADC films with thickness of about 20 {mu}m were prepared from commercially available CR-39 films by chemical etching to fabricate custom-made petri dishes for cell culture, which could accurately record alpha particle hit positions. A special method involving 'base tracks' for aligning the images of cell nuclei and alpha particle hits has been proposed, so that alpha particle transversals of cell nuclei can be visually counted. Radiobiological experiments were carried out to induce DNA damages, with the TdT-mediated dUTP Nick-End Labeling (TUNEL) fluorescence method employed to detect DNA strand breaks. The staining results were investigated by flow cytometer. The preliminary results showed that more strand breaks occurred in cells hit by alpha particles with lower energies. Moreover, large TUNEL positive signals were obtained even with small percentages of cells irradiated and TUNEL signals were also obtained from non-targeted cells. These provided evidence for the bystander effect.

  13. Influence of catechins on bystander responses in CHO cells induced by alpha-particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Law, Y.L.; Wong, T.P.W. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Yu, K.N. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)], E-mail: peter.yu@cityu.edu.hk

    2010-04-15

    In this work, we studied alpha-particle induced and medium-mediated bystander effects in Chinese hamster ovary (CHO) cells through micronucleus (MN) assay. We showed that signal transduction from irradiated cells to bystander cells occur within a short time after irradiation. We then studied the effects of ROS (reactive oxygen species)-scavenging catechins in the medium before irradiation. We observed decreases in the percentage of bystander cells with MN formation and thus proved the protection effect of catechins on bystander cells from radiation.

  14. Determination of the range of alpha particles in SSNTD by optical density method

    CERN Document Server

    El-Hofy, M; Arafa, W

    1999-01-01

    A technique based on the optical density (D) measurement of the etched track is useful for charged particles spectroscopy using SSNTD. It was shown that the stopping power of alpha particles in CR-39 is proportional to D. We measured the optical density and derived an expression to estimate the range of alpha particles in CR-39 detector as a function of the bulk etching rate and etching time. The relation between the etching time, track parameters (depth, radius) and D for different alpha particles energy and etching conditions were studied. A relation describing D as a function of track size is proposed.

  15. The biokinetics of alpha-particle emitting radiopharmaceuticals

    International Nuclear Information System (INIS)

    The past two decades have seen wide interest in the application of alpha-particle emitting radionuclides for targeted endoradiotherapy and a large number of compounds labeled with 211At (T1/2 7.21 h), 212Bi (T1/2 1 h) or 213Bi (T1/2 0.78 h) have been studied. Knowledge of the biokinetic behaviour of such agents is important both for their optimal clinical exploitation and for general radiological protection purposes. Animal studies of the distribution and retention of 211At compounds, including ionic astatide, substituted aromatic compounds and labelled monoclonal antibodies, have provided new information on the biochemistry of astatine. With respect the thyroid gland the uptake of the astatide ion has been shown to be very much lower than that of the iodide ion. Less information is available for 212Bi-labelled radiopharmaceuticals. The available data for both 211At and 212Bi radiopharmaceuticals are reviewed. Cautious generic biokinetic models for inorganic and simple organic compounds of 211At and 212Bi; for [211At]-, and [212Bi]-biphosphonates and for [211At]-, and [212Bi]-monoclonal antibodies, are proposed for use in general radiological protection when compound-specific data are not available. (orig.)

  16. The biokinetics of alpha-particle emitting radiopharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, D.M. [School of Chemistry, Cardiff Univ., Cardiff (United Kingdom); Duffield, J.R. [Faculty of Applied Sciences, Univ. of the West of England, Bristol (United Kingdom)

    2005-07-01

    The past two decades have seen wide interest in the application of alpha-particle emitting radionuclides for targeted endoradiotherapy and a large number of compounds labeled with {sup 211}At (T{sup 1}/{sub 2} 7.21 h), {sup 212}Bi (T{sup 1}/{sub 2} 1 h) or {sup 213}Bi (T{sup 1}/{sub 2} 0.78 h) have been studied. Knowledge of the biokinetic behaviour of such agents is important both for their optimal clinical exploitation and for general radiological protection purposes. Animal studies of the distribution and retention of {sup 211}At compounds, including ionic astatide, substituted aromatic compounds and labelled monoclonal antibodies, have provided new information on the biochemistry of astatine. With respect the thyroid gland the uptake of the astatide ion has been shown to be very much lower than that of the iodide ion. Less information is available for {sup 212}Bi-labelled radiopharmaceuticals. The available data for both {sup 211}At and {sup 212}Bi radiopharmaceuticals are reviewed. Cautious generic biokinetic models for inorganic and simple organic compounds of {sup 211}At and {sup 212}Bi; for [{sup 211}At]-, and [{sup 212}Bi]-biphosphonates and for [{sup 211}At]-, and [{sup 212}Bi]-monoclonal antibodies, are proposed for use in general radiological protection when compound-specific data are not available. (orig.)

  17. Self-consistent analysis of alpha-particle heating of a fast-solenoid plasma

    International Nuclear Information System (INIS)

    A numerical technique has been developed to analyse the dynamics of a linear, magnetically confined plasma column and its associated fusion-produced alpha-particles in a self consistent manner. The thermonuclear background plasma is considered as a radially non-uniform, axially symmetric magnetofluid in pressure equilibrium with the surrounding axial magnetic field. A multi-group technique is utilized to examine the alphas as a collection of particles distributed among a continuous spectrum of confined orbits. The technique is shown to be an effective one for observing the interaction between super-thermal particles with large orbit sizes and a stable plasma of comparable size. The use of a distribution function in an adiabatic-invariant representation results in an enormous increase in the time scale which can be treated. This enables analysis of the entire duty cycle of a laser solenoid plasma in reasonable computation times. An analysis of a fast solenoid plasma is described, where the initial plasma radius and temperature are varied parametrically. A plasma column of radius 7mm, temperature 6keV, and β=0.95 will reach an ion temperature of 10keV, corresponding to a fusion energy gain of 8, after 3ms. A range of maximum gain occurs for initial temperatures of 5 to 7keV, with larger radius plasmas more favoured by the cooler limits. The effect of increasing the alpha-particle-electron energy transfer rate by a moderate amount to account for anomalous effects is to increase the plasma temperature at longer times, as long as this energy transfer is well-coupled to the electron-ion energy transfer. Increasing the rate at which plasma transport processes occur (''anomalous transport'') always results in lower fusion yield, because of rapid plasma diffusion. (author)

  18. Microscopic visualization of a biological response to charged particle traversal

    Science.gov (United States)

    Taucher-Scholz, G.; Jakob, B.; Becker, G.; Scholz, M.

    2003-08-01

    Understanding the molecular mechanisms underlying biological effects of charged particle radiation has become increasingly important in view of the use of ion beams in tumor therapy. Elucidating how the enhanced efficiency of densely ionizing radiation in cell killing is related to the initial causative lesions, namely DNA double-strand breaks, constitutes a major task in radiobiology. The inhomogeneous spatial distribution of energy deposition leading to the induction of more complex and less reparable DNA lesions is the basis for high-LET effects. But the cellular response to radiation damage also involves the interplay between repair and signal transduction proteins with the aim of coordinating the processing of DNA damage and cell cycle progression to allow time for repair. Charged particles are used as a probe for the production of localized subcellular damage to study these aspects of the biological response to ionizing radiation. Immunocytochemical techniques applied in combination with confocal laser microscopy allow to monitor the relocalization of DNA damage response proteins within individual nuclei following irradiation. In particular, the rapid accumulation of the signalling protein p21 at sites of heavy ion-induced DNA damage reflects the microscopic distribution of dose deposited within nuclei of irradiated human fibroblasts. The biological response pattern for p21 is presented for high and low energy ion beams, involving different particle species and representing a wide range of radiation qualities.

  19. Model of alpha particle diffusion in the outer limiter shadow of TFTR

    International Nuclear Information System (INIS)

    A new code, Monte Carlo Collisional Stochastic Orbit Retracing (MCCSOR), has been developed to model the alpha particle loss signal as measured by the outer midplane scintillator detector in TFTR. The shadowing effects due to the outer limiters and the detector itself have been included, along with a pitch angle scattering and stochastic ripple diffusion. Shadowing by the outer limiters has a strong effect on both the magnitude and pitch angle distribution of the calculated loss. There is at least qualitative agreement between the calculated results and the experimental data

  20. The $\\alpha-\\alpha$ fishbone potential revisited

    CERN Document Server

    Day, J P; Elhanafy, M; Smith, E; Woodhouse, R; Papp, Z

    2011-01-01

    The fishbone potential of composite particles simulates the Pauli effect by nonlocal terms. We determine the $\\alpha-\\alpha$ fishbone potential by simultaneously fitting to two-$\\alpha$ resonance energies, experimental phase shifts and three-$\\alpha$ binding energies. We found that essentially a simple gaussian can provide a good description of two-$\\alpha$ and three-$\\alpha$ experimental data without invoking three-body potentials.

  1. The Use Of Optical Properties Of Cr-39 In Alpha Particle Equivalent Dose Measurements

    International Nuclear Information System (INIS)

    In this work, optical properties of alpha irradiated Cr-39 were measured as a function of optical photon wavelength from 200-1100 nm. Optical energy gap and optical absorption at finite wavelength was also calculated and correlated to alpha fluence and dose equivalent. Alpha doses were calculated from the corresponding irradiation fluence and specific energy loss using TRIM computer program. It was found that, the optical absorption of unattached Cr-39 was varied with alpha fluence and corresponding equivalent doses. Also the optical energy gab was varied with fluence and dose equivalent of alpha particles. This work introduces a reasonably simple method for the Rn dose equivalent calculation by Cr-39 track

  2. On surface clustering and Pauli principle effects in alpha decay

    International Nuclear Information System (INIS)

    The importance of the correct description of nuclear surface region in alpha decay calculations is pointed out. A model is proposed takinq into account explicitly surface clustering and Pauli principle effects which are essential in this region. A method for solving the main integrodifferential equation of the model by using the oscillator shell basis and the Collatz method is worked out. The first numerical results are obtained for nonlocal potential of the atpha particle-daughter nucleus interaction

  3. Differential superiority of heavy charged-particle irradiation to x-rays: Studies on biological effectivenes and side effect mechanisms in multicellular tumor and normal tissue models

    Directory of Open Access Journals (Sweden)

    Stefan eWalenta

    2016-02-01

    Full Text Available This review is focused on the radiobiology of carbon ions compared to x-rays using multicellular models of tumors and normal mucosa. The first part summarizes basic radiobiological effects, as observed in cancer cells. The second, more clinically oriented part of the review deals with radiation-induced cell migration and mucositis.Multicellular spheroids (MCS from V79 hamster cells were irradiated with x-rays or carbon ions under ambient or restricted oxygen supply conditions. Oxygen enhancement ratios (OER were 2.9, 2.8, and 1.4 for irradiation with photons, 12C+6 in the plateau region, and 12C+6 in the Bragg peak, respectively. A relative biological effectiveness (RBE of 4.3 and 2.1 for ambient pO2 and hypoxia was obtained, respectively. The high effectiveness of carbon ions was reflected by an enhanced accumulation of cells in G2/M, and a dose-dependent massive induction of apoptosis. Clinically relevant doses (3 Gy of x-rays induced an increase in migratory activity of U87 but not of LN229 or HCT116 tumor cells. Such an increase in cell motility following irradiation in situ could be the source of recurrence. In contrast, carbon ion treatment was associated with a dose-dependent decrease in migration with all cell lines and under all conditions investigated. The radiation-induced loss of cell motility was correlated, in most cases, with corresponding changes in 1 integrin expression. Unlike with particles, the photon-induced increase in cell migration was paralleled by an elevated phosphorylation status of the epidermal growth factor receptor (EGFR and AKT-ERK1/2 pathway. Comparing the gene toxicity of x-rays with that of particles using the gamma-H2AX technique in organotypic cultures of the oral mucosa, the superior effectiveness of heavy ions was confirmed by a two-fold higher number of foci per nucleus. Pro-inflammatory signs, however, were similar for both treatment modalities, e. g., the activation of NFkappaB, and the release of IL

  4. Relativistic effects in Lyman-alpha forest

    CERN Document Server

    Iršič, Vid; Viel, Matteo

    2015-01-01

    We present the calculation of the Lyman-alpha (Lyman-$\\alpha$) transmitted flux fluctuations with full relativistic corrections to the first order. Even though several studies exist on relativistic effects in galaxy clustering, this is the first study to extend the formalism to a different tracer of underlying matter at unique redshift range ($z = 2 - 5$). Furthermore, we show a comprehensive application of our calculations to the Quasar- Lyman-$\\alpha$ cross-correlation function. Our results indicate that the signal of relativistic effects can be as large as 30% at Baryonic Acoustic Oscillation (BAO) scale, which is much larger than anticipated and mainly due to the large differences in density bias factors of our tracers. We construct an observable, the anti-symmetric part of the cross- correlation function, that is dominated by the relativistic signal and offers a new way to measure the relativistic terms at relatively small scales. The analysis shows that relativistic effects are important when considerin...

  5. Gaseous swelling model in the alpha-particles straggling field

    International Nuclear Information System (INIS)

    In the work for the physical model the following key presuppositions were accepted: alpha particles Gauss distribution in the straggling field is expected; the helium embryo is the helium atom plus the two vacancies; gaseous pores coalescence is resulted their migration in the tension field and Brownian movement; the preservation of helium atoms in the coalescence process is expected; it consequence is swelling. At the initial stage the behavior of pores ensemble with taking into account of a point defects formation during irradiation process have been analyzed. It is expected, that development of this ensemble will be take place during the following annealing of the matrix. The main presuppositions on the this stage of calculation are as follows: there are the principal elements of the microstructure - are taking into account in the kinetic equations - implanted helium interstitials, vacancies, dislocation network, Frank loops, pores; it is excepted, that two interstitial helium atoms form the pore embryo; two interstitials Frank loops at distances between components equal to lattice constant; mechanisms of pores formation in the matrix and dislocation are expected different; the additional channel of pores growth is Frank loops dropping. The typical kinetic equation for interstitial from complete equation system is presented. The pores ensemble evolution for iron irradiated by helium ions with energy E=400 keV up to integral dose 101|7 ion/cm2 at 100 deg C temperature and following annealing at temperature 800 deg C is calculated. It is shown that pores distribution by sizes is shifting forward big sizes with increase of annealing time

  6. A cluster expansion for bound three-alpha particles as a three-body problem

    International Nuclear Information System (INIS)

    A three-body model is proposed to study the nuclear bound states. The nucleus is described as a bound state of three clusters. A cluster expansion is introduced for the three cluster bound state problem. The present integral equations are treated by simple approximate solutions, which lead to effective potentials by using the present cluster expansion. The 12C nucleus is described as a three-alpha particle bound state. The binding energy of 12C is calculated numerically using the present cluster expansion as bound three-alpha clusters. The present three-body cluster expansion calculations are very near to the exact three-body calculations using separable potentials. The present theoretical calculations are in good agreement with the experimental measurements. (author)

  7. The simulation of the response of superheated emulsion to alpha particles

    International Nuclear Information System (INIS)

    The response of superheated emulsion of liquid perfluorobutane (C4F10; b.p.:  −1.7o C) to alpha particle has been studied by performing the simulation using GEANT3.21 toolkit. The simulations have been performed to generate two different experimental situations. In one case, the alpha contamination is present only in polymer and in another case, the alpha contamination is present both in polymer and active liquid. The value of the nucleation parameter, k, for bubble nucleation induced by alpha particle in superheated emulsion detector is determined by comparing the simulated normalized count rates with the available experimental results. The results show that the nucleation parameter for alpha particle in C4F10 liquid is about 0.19. The energy and position of alpha particle are not able to change the response of the alpha particle in C4F10 liquid. The recoiling nuclei associated with the alpha decay chain are responsible for making the detector sensitive at lower threshold temperatures

  8. The simulation of the response of superheated emulsion to alpha particles

    Science.gov (United States)

    Seth, Susnata; Das, Mala

    2016-04-01

    The response of superheated emulsion of liquid perfluorobutane (C4F10; b.p.: ‑1.7o C) to alpha particle has been studied by performing the simulation using GEANT3.21 toolkit. The simulations have been performed to generate two different experimental situations. In one case, the alpha contamination is present only in polymer and in another case, the alpha contamination is present both in polymer and active liquid. The value of the nucleation parameter, k, for bubble nucleation induced by alpha particle in superheated emulsion detector is determined by comparing the simulated normalized count rates with the available experimental results. The results show that the nucleation parameter for alpha particle in C4F10 liquid is about 0.19. The energy and position of alpha particle are not able to change the response of the alpha particle in C4F10 liquid. The recoiling nuclei associated with the alpha decay chain are responsible for making the detector sensitive at lower threshold temperatures.

  9. [Obtaining and characteristics of domestic preparation interferon alpha-2b with prolonged effect].

    Science.gov (United States)

    Pokholenko, Ia A; Porubleva, L V; Dubeĭ, I Ia; Rebriev, A V; Sutugina, L P; Gromovoĭ, T Iu; Pokrovskiĭ, V A; Obolenskaia, M Iu; Chernykh, S I

    2008-01-01

    Pegylated interferon alpha-2b (PEG-IFN alpha-2b) is a domestic preparation of a modified recombinant interferon alpha-2b with prolonged effect. The preparation was obtained by N-terminal pegylation of IFN alpha-2b with polyethylene glycol (PEG). This paper presents the method of PEG-IFN alpha-2b synthesis and characteristics of the obtained product. PAAG electrophoresis, Western blot analysis and MALDI-TOF mass-spectrometry confirm that the preparation is an N-terminal pegylated IFN alpha-2b that contains no more than 10% of dipegylated IFN alpha-2b. The comparison of PEG-IFN alpha-2b with its foreign analogue has revealed the similarity of their biological activity and pharmacokinetic parameters. PMID:19351063

  10. Transport theory for energetic alpha particles in finite aspect ratio tokamaks with broken symmetry

    Science.gov (United States)

    Shaing, K. C.; Schlutt, M.; Lai, A. L.

    2016-02-01

    Transport theory for the energetic alpha particles in finite aspect ratio tokamaks with broken symmetry is developed for the case where the slowing down collision operator dominates. The transport fluxes in the 1 /ν and superbanana plateau regimes are derived. Here, ν is the typical collision frequency. They can be used in modeling the energy loss of the alpha particles in thermonuclear fusion reactors. Numerical realizations of the superbanana orbits of alpha particles in tokamaks with broken symmetry are also presented. The existence of the superbananas corroborates the predictions of the theories presented here and elsewhere.

  11. Experiments with nuclear track detectors for diagnostics of protons and alpha particles from fusion plasmas

    International Nuclear Information System (INIS)

    This report deals with the experimental development of a method of detecting charged particles from nuclear fusion plasmas by means of nuclear track detectors. The latter were bombarded with protons and alpha particles poduced with an accelerator from the fusion reactions D (3He, p) α and D (D, p) T. In the parameter range expected for the particles emitted from thermonuclearly burning plasma the detection probabilities of protons and alpha particles were determined as functions of the energy and angle of incidence, and also the crater radii and depths as functions of the particle species, particle energy and etching time. The following results were obtained: For alpha particles the detection probability in the entire energy range investigated and at angles of incidence between 00 and 700 to the foil normal is about 100%. The alpha particle energy can be approximately determined from the track depths. For protons, on the other hand, the detection probability already decreases monotonically at low energies as the energy increases, becoming zero at about Esub(p) = 7 MeV. Proton detection is only possible at angles of incidence between 00 and 300. The proton energy can be approximately determined from the track radii. The measured energy dependence of the track radii and depths of alpha particles and protons and their angular dependence can be explained with a simple model calculation in which it is assumed that the track etching rate decreases as the particle range in the material of the nuclear track foils increases. (orig.)

  12. Janus particles for biological imaging and sensing.

    Science.gov (United States)

    Yi, Yi; Sanchez, Lucero; Gao, Yuan; Yu, Yan

    2016-06-21

    Janus particles, named after the two-faced Roman god Janus, have different surface makeups, structures or compartments on two sides. This review highlights recent advances in employing Janus particles as novel analytical tools for live cell imaging and biosensing. Unlike conventional particles used in analytical science, two-faced Janus particles provide asymmetry and directionality, and can combine different or even incompatible properties within a single particle. The broken symmetry enables imaging and quantification of rotational dynamics, revealing information beyond what traditional measurements offer. The spatial segregation of molecules on the surface of a single particle also allows analytical functions that would otherwise interfere with each other to be decoupled, opening up opportunities for novel multimodal analytical methods. We summarize here the development of Janus particles, a few general methods for their fabrication and, more importantly, the emerging and novel applications of Janus particles as multi-functional imaging probes and sensors. PMID:27052001

  13. Biological properties of different type carbon particles in vitro study on primary culture of endothelial cells.

    Science.gov (United States)

    Czerniak-Reczulska, M; Niedzielski, P; Balcerczyk, A; Bartosz, G; Karowicz-Bilińska, A; Mitura, K

    2010-02-01

    Carbon powders have extended surface of carbon layers, which is of significant biomedical importance since the powders are employed to cover implants material. Carbon Powder Particles are produced by different methods: by a detonation method, by RF PACVD (Radio Frequency Plasma Activated Chemical Vapour Deposition) or MW/RF PCVD (Microwave/Radio Frequency Plasma Activated Chemical Vapour Deposition) and others. Our previous data showed that Carbon Powder Particles may act as antioxidant and/or anti-inflammatory factor. However the mechanism of such behavior has been not fully understood. The aim of the work was tested influence carbon powders manufactured by Radio Frequency Plasma Activated Chemical Vapour Deposition RFPACVD method and detonation method on selected parameters of human endothelial cells, which play a crucial role in the regulation of the circulation and vascular wall homeostasis. Graphite powder was used as a control substance. Endothelial cells are actively involved in a wide variety of processes e.g., inflammatory responses to a different type of stimuli (ILs, TNF-alpha) or regulating vasomotor tone via production of vasorelaxants and vasocontrictors. Biological activation is dependent on the type and quantity of chemical bonds on the surface of the powders. The effect of powders on the proliferation of HUVECs (Human Umbilical Vein Endothelial Cells) was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction assay. We found decreased cell proliferation after 72 h treatment with graphite as well as Carbon Powder Particles. PMID:20352757

  14. Cluster-shell competition in systems with a few alpha particles and valence neutrons

    International Nuclear Information System (INIS)

    We construct nuclear wave functions from alpha clusters and some additional valence nucleons, and allow the inter-cluster distance to change and one alpha to dissolve from the (0s)4 structure as a result of the nuclear interaction. The change of the inter-cluster distance and the dissolution of the alpha particle can be interpreted as resulting from the competition of the 'shell model' and 'cluster model'. We demonstrate this competition through a few parameters.

  15. Biological Effects of Ionizing Radiation

    Science.gov (United States)

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

  16. Laser heating of dielectric particles for medical and biological applications.

    Science.gov (United States)

    Tribelsky, Michael I; Fukumoto, Yasuhide

    2016-07-01

    We consider the general problem of laser pulse heating of a spherical dielectric particle embedded in a liquid. The discussed range of the problem parameters is typical for medical and biological applications. We focus on the case, when the heat diffusivity in the particle is of the same order of magnitude as that in the fluid. We perform quantitative analysis of the heat transfer equation based on interplay of four characteristic scales of the problem, namely the particle radius, the characteristic depth of light absorption in the material of the particle and the two heat diffusion lengths: in the particle and in the embedding liquid. A new quantitative characteristic of the laser action, that is the cooling time, describing the temporal scale of the cooling down of the particle after the laser pulse is over, is introduced and discussed. Simple analytical formulas for the temperature rise in the center of the particle and at its surface as well as for the cooling time are obtained. We show that at the appropriate choice of the problem parameters the cooling time may be by many orders of magnitude larger the laser pulse duration. It makes possible to minimize the undesirable damage of healthy tissues owing to the finite size of the laser beam and scattering of the laser radiation, simultaneously keeping the total hyperthermia period large enough to kill the pathogenic cells. An example of application of the developed approach to optimization of the therapeutic effect at the laser heating of particles for cancer therapy is presented. PMID:27446706

  17. Charge-exchange limits on low-energy alpha-particle fluxes in solar flares

    CERN Document Server

    Hudson, Hugh; MacKinnon, Alec; Woods, Tom

    2014-01-01

    This paper reports on a search for flare emission via charge-exchange radiation in the wings of the Lyman-alpha line of He ii at 304 A, as originally suggested for hydrogen by Orrall and Zirker. Via this mechanism a primary alpha particle that penetrates into the neutral chromosphere can pick up an atomic electron and emit in the He ii bound-bound spectrum before it stops. The Extreme-ultraviolet Variability Experiment (EVE) on board the Solar Dynamics Observatory (SDO) gives us our first chance to search for this effect systematically. The Orrall-Zirker mechanism has great importance for flare physics because of the essential roles that particle acceleration plays; this mechanism is one of the few proposed that would allow remote sensing of primary accelerated particles below a few MeV/nucleon. We study ten events in total, including the gamma-ray events SOL2010-06-12 (M2.0) and SOL2011-02-24 (M3.5) (the latter a limb flare), seven X-class flares, and one prominent M-class event that produced solar energetic...

  18. Cross sections of nuclear reactions induced by protons, deuterons, and alpha particles. Pt.6. Phosphorus

    International Nuclear Information System (INIS)

    Cross sections are reviewed for nuclear reactions induced by protons, deuterons, and alpha particles on phosphorus targets. When necessary, published experimental data are corrected, and, when possible, excitation functions are proposed

  19. Interaction of neutrons with alpha particles: A tribute to Heinz Barschall

    OpenAIRE

    Hoop, B. de

    2015-01-01

    As a tribute to our teacher and mentor on the occasion of his centennial celebration, we provide a brief historical overview and a summary of sustained interest in the topic of interaction of neutrons with alpha particles.

  20. Measurement of $\\alpha$-particle quenching in LAB based scintillator in independent small-scale experiments

    CERN Document Server

    von Krosigk, B; Hans, S; Junghans, A R; Kögler, T; Kraus, C; Kuckert, L; Liu, X; Nolte, R; O'Keeffe, H M; Tseung, H S Wan Chan; Wilson, J R; Wright, A; Yeh, M; Zuber, K

    2015-01-01

    The $\\alpha$-particle light response of liquid scintillators based on linear alkylbenzene (LAB) has been measured with three different experimental approaches. In the first approach, $\\alpha$-particles were produced in the scintillator via $^{12}$C($n$,$\\alpha$)$^9$Be reactions. In the second approach, the scintillator was loaded with 2% of $^{\\mathrm{nat}}$Sm providing an $\\alpha$-emitter, $^{147}$Sm, as an internal source. In the third approach, a scintillator flask was deployed into the water-filled SNO+ detector and the radioactive contaminants $^{222}$Rn, $^{218}$Po and $^{214}$Po provided the $\\alpha$-particle signal. The behavior of the observed $\\alpha$-particle light outputs are in agreement with each case successfully described by Birks' law. The resulting Birks parameter $kB$ ranges from $(0.0071\\pm0.0003)$ cm/MeV to $(0.0076\\pm0.0003)$ cm/MeV. In the first approach, the $\\alpha$-particle light response was measured simultaneously with the light response of recoil protons produced via neutron-proto...

  1. Feasibility of ion temperature measurement with a gyrotron scattering alpha particle diagnostic

    International Nuclear Information System (INIS)

    Collective Thomson scattering can be used to diagnose localized ion temperature as well as alpha particle velocity distribution and density in a D-T burning tokamak. With one diagnostic beam a simultaneous, but independent, measure of the bulk ion temperature and alpha particle parameters can be made. Use of a long pulse, millimeter-wave gyrotron offers a significant margin in signal to noise ratio capability (√Δftau > 1000) not previously possible with lasers. 9 refs., 2 figs

  2. Fokker Planck kinetic modeling of suprathermal alpha-particles in a fusion plasma

    OpenAIRE

    Peigney, Benjamin-Edouard; Larroche, Olivier; Tikhonchuk, Vladimir

    2014-01-01

    We present an ion kinetic model describing the ignition and burn of the deuterium-tritium fuel of inertial fusion targets. The analysis of the underlying physical model enables us to develop efficient numerical methods to simulate the creation, transport and collisional relaxation of fusion reaction products (alpha-particles) at a kinetic level. A two-energy-scale approach leads to a self-consistent modeling of the coupling between suprathermal alpha-particles and the thermal bulk of the impl...

  3. Effects of internally deposited alpha emitters

    International Nuclear Information System (INIS)

    This study seeks to identify and quantify the human health effects of occupational exposures to radium, use the health effects data from the radium study to predict responses to other alpha-emitting and/or bone-seeking radionuclides at occupational exposure levels and above, and predict the effects of these radionuclides, specifically environmental radium and its daughters, at nonoccupational exposure levels. 14 refs

  4. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles. Progress report, July 1, 1991--June 30, 1992

    Energy Technology Data Exchange (ETDEWEB)

    1992-04-01

    The objective of our research work is to provide -- with the aid of biophysical models of radiation action -- information on human risks following exposure to radon alpha particles. The approach proposed consists of (1) developing appropriate models (parametric and non-parametric) for alpha radiation induction of relevant end points (survival, cellular transformation), (2) providing an accurate physical characterization of the particle tracks in terms of nanodosimetric distributions, (3) supporting the models by detailed, molecular studies of the direct and indirect effects of alpha particles on DNA. Activities in the second year of this project are described.

  5. Development of the MICROMEGAS Detector for Measuring the Energy Spectrum of Alpha Particles by using a 241-Am Source

    CERN Document Server

    Kim, Do Yoon; Shin, Jae Won; Park, Tae-Sun; Hong, Seung-Woo; Andriamonje, Samuel; Kadi, Yacine; Tenreiro, Claudio

    2016-01-01

    We have developed MICROMEGAS (MICRO MEsh GASeous) detectors for detecting {\\alpha} particles emitted from an 241-Am standard source. The voltage applied to the ionization region of the detector is optimized for stable operation at room temperature and atmospheric pressure. The energy of {\\alpha} particles from the 241-Am source can be varied by changing the flight path of the {\\alpha} particle from the 241 Am source. The channel numbers of the experimentally-measured pulse peak positions for different energies of the {\\alpha} particles are associated with the energies deposited by the alpha particles in the ionization region of the detector as calculated by using GEANT4 simulations; thus, the energy calibration of the MICROMEGAS detector for {\\alpha} particles is done. For the energy calibration, the thickness of the ionization region is adjusted so that {\\alpha} particles may completely stop in the ionization region and their kinetic energies are fully deposited in the region. The efficiency of our MICROMEGA...

  6. Quantum Effects in Biology

    Science.gov (United States)

    Mohseni, Masoud; Omar, Yasser; Engel, Gregory S.; Plenio, Martin B.

    2014-08-01

    List of contributors; Preface; Part I. Introduction: 1. Quantum biology: introduction Graham R. Fleming and Gregory D. Scholes; 2. Open quantum system approaches to biological systems Alireza Shabani, Masoud Mohseni, Seogjoo Jang, Akihito Ishizaki, Martin Plenio, Patrick Rebentrost, Alàn Aspuru-Guzik, Jianshu Cao, Seth Lloyd and Robert Silbey; 3. Generalized Förster resonance energy transfer Seogjoo Jang, Hoda Hossein-Nejad and Gregory D. Scholes; 4. Multidimensional electronic spectroscopy Tomáš Mančal; Part II. Quantum Effects in Bacterial Photosynthetic Energy Transfer: 5. Structure, function, and quantum dynamics of pigment protein complexes Ioan Kosztin and Klaus Schulten; 6. Direct observation of quantum coherence Gregory S. Engel; 7. Environment-assisted quantum transport Masoud Mohseni, Alàn Aspuru-Guzik, Patrick Rebentrost, Alireza Shabani, Seth Lloyd, Susana F. Huelga and Martin B. Plenio; Part III. Quantum Effects in Higher Organisms and Applications: 8. Excitation energy transfer in higher plants Elisabet Romero, Vladimir I. Novoderezhkin and Rienk van Grondelle; 9. Electron transfer in proteins Spiros S. Skourtis; 10. A chemical compass for bird navigation Ilia A. Solov'yov, Thorsten Ritz, Klaus Schulten and Peter J. Hore; 11. Quantum biology of retinal Klaus Schulten and Shigehiko Hayashi; 12. Quantum vibrational effects on sense of smell A. M. Stoneham, L. Turin, J. C. Brookes and A. P. Horsfield; 13. A perspective on possible manifestations of entanglement in biological systems Hans J. Briegel and Sandu Popescu; 14. Design and applications of bio-inspired quantum materials Mohan Sarovar, Dörthe M. Eisele and K. Birgitta Whaley; 15. Coherent excitons in carbon nanotubes Leonas Valkunas and Darius Abramavicius; Glossary; References; Index.

  7. Coincidence techniques (time correlation) alpha-gamma particles associated experiments on PGFNAA

    International Nuclear Information System (INIS)

    PGFNAA (Prompt Gamma Fast Neutron Alpha Associated) techniques offers capabilities far beyond those of the conventional inspection system to detect hazardous materials such as explosives or drugs. This technique uses the time coincidence between alpha and gamma particles to reduce the background produced by fast neutron interactions not only with the objects but also with the surrounding material. This paper reports the experimental setup that have been conducted to capture coincident events between alpha and gamma particles. Although not perfect, but the reduction of the background almost 100 % had been obtained on the outside area of the spectrum energy interest for water and graphite samples. (author)

  8. Characterization of a alpha particle detector CR-39 exposed to a source of radium

    International Nuclear Information System (INIS)

    In this project, the main goal is the characterization of a alpha particle detector CR-39 exposed to a source of radio. Three detectors were exposed to a source of radium and then chemically treated for different periods. This way, we could analyze these samples and collect the information needed to verify that at least one of the chemical attack, there has been a separation of the energies alpha particles incident with distinct peaks, thus characterizing the CR-39 as alpha spectrometer in the range 2.5 to 6.3 MeV . (author)

  9. Biologically active monoiodinated alpha-MSH derivatives for receptor binding studies using human melanoma cells

    International Nuclear Information System (INIS)

    Three different monoiodinated radioligands of alpha-MSH (alpha-melanocyte-stimulating hormone) were compared in a binding assay with human D10 melanoma cells: [Tyr(125I)2]-alpha-MSH, [Tyr(125I)2,NIe4]-alpha-MSH, and [Tyr(125I)2,NIe4,D-Phe7]-alpha-MSH. They were prepared either by the classical chloramine T method or by the Enzymobead method. A simple and rapid purification scheme was developed consisting of a primary separation on reversed-phase C18 silica cartridges immediately after the iodination, followed by HPLC purification before each binding experiment. Biological testing of the three radioligands showed that they all retained high melanotropic activity in the B16 melanin assay and the Anolis melanophore assay. However, in human D10 melanoma cells, [Tyr(125I)2,NIe4]-alpha-MSH led to a high degree of non-specific binding to the cells which could not be displaced by excess alpha-MSH and only partially by [NIe4]-alpha-MSH. The [Tyr(125I)2,NIe4,D-Phe7]-alpha-MSH tracer gave similar results but with a much lower proportion of non-specific binding. On the other hand, [Tyr(125I)2]-alpha-MSH proved to be an excellent radioligand whose non-specific binding to the D10 cells was not higher than 20% of the total binding

  10. Calculations of alpha particle loss for reversed magnetic shear in the Tokamak Fusion Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Redi, M.H.; White, R.B.; Batha, S.H.; Levinton, F.M.; McCune, D.C.

    1997-03-01

    Hamiltonian coordinate, guiding center code calculations of the toroidal field ripple loss of alpha particles from a reversed shear plasma predict both total alpha losses and ripple diffusion losses to be greater than those from a comparable non-reversed magnetic shear plasma in the Tokamak Fusion Test Reactor (TFTR) [Fusion Technol. 21, 1324 (1992)]. High central q is found to increase alpha ripple losses as well as first orbit losses of alphas in the reversed shear simulations. A simple ripple loss model, benchmarked against the guiding center code, is found to work satisfactorily in transport analysis modelling of reversed and monotonic shear scenarios. Alpha ripple transport on TFTR affects ions within r/a=0.5, not at the plasma edge. The entire plasma is above threshold for stochastic ripple loss of alpha particles at birth energy in the reversed shear case simulated, so that all trapped 3.5 MeV alphas are lost stochastically or through prompt losses. The 40% alpha particle loss predictions for TFTR suggest that reduction of toroidal field ripple will be a critical issue in the design of a reversed shear fusion reactor.

  11. Downstream energetic proton and alpha particles during quasi-parallel interplanetary shock events

    Science.gov (United States)

    Tan, L. C.; Mason, G. M.; Gloeckler, G.; Ipavich, F. M.

    1988-01-01

    This paper considers the energetic particle populations in the downstream region of three quasi-parallel interplanetary shock events, which was explored using the ISEE 3 Ultra Low Energy Charge Analyzer sensor, which unambiguously identifies protons and alpha particles using the electrostatic deflection versus residual energy technique. The downstream particles were found to exhibit anisotropies due largely to convection in the solar wind. The spectral indices of the proton and the alpha-particle distribution functions were found to be remarkably constant during the downstream period, being generally insensitive to changes in particle flux levels, magnetic field direction, and solar wind densities. In two of the three events, the proton and the alpha spectra were the same throughout the entire downstream period, supporting the prediction of diffusive shock acceleration theory.

  12. Analysis of uncertainties in alpha-particle optical-potential assessment below the Coulomb barrier

    CERN Document Server

    Avrigeanu, V

    2016-01-01

    Background: Recent high-precision measurements of alpha-induced reaction data below the Coulomb barrier have pointed out questions of the alpha-particle optical-model potential (OMP) which are yet open within various mass ranges. Purpose: The applicability of a previous optical potential and eventual uncertainties and/or systematic errors of the OMP assessment at low energies can be further considered on this basis. Method: Nuclear model parameters based on the analysis of recent independent data, particularly gamma-ray strength functions, have been involved within statistical model calculation of the (alpha,x) reaction cross sections. Results: The above-mentioned potential provides a consistent description of the recent alpha-induced reaction data with no empirical rescaling factors of the and/or nucleon widths. Conclusions: A suitable assessment of alpha-particle optical potential below the Coulomb barrier should involve the statistical-model parameters beyond this potential on the basis of a former analysi...

  13. Targeted Cytoplasmic Irradiation with Alpha Particles Induces Mutations in Mammalian Cells

    Science.gov (United States)

    Wu, Li-Jun; Randers-Pehrson, Gerhard; Xu, An; Waldren, Charles A.; Geard, Charles R.; Yu, Zengliang; Hei, Tom K.

    1999-04-01

    Ever since x-rays were shown to induce mutation in Drosophila more than 70 years ago, prevailing dogma considered the genotoxic effects of ionizing radiation, such as mutations and carcinogenesis, as being due mostly to direct damage to the nucleus. Although there was indication that alpha particle traversal through cellular cytoplasm was innocuous, the full impact remained unknown. The availability of the microbeam at the Radiological Research Accelerator Facility of Columbia University made it possible to target and irradiate the cytoplasm of individual cells in a highly localized spatial region. By using dual fluorochrome dyes (Hoechst and Nile Red) to locate nucleus and cellular cytoplasm, respectively, thereby avoiding inadvertent traversal of nuclei, we show here that cytoplasmic irradiation is mutagenic at the CD59 (S1) locus of human-hamster hybrid (AL) cells, while inflicting minimal cytotoxicity. The principal class of mutations induced are similar to those of spontaneous origin and are entirely different from those of nuclear irradiation. Furthermore, experiments with radical scavenger and inhibitor of intracellular glutathione indicated that the mutagenicity of cytoplasmic irradiation depends on generation of reactive oxygen species. These findings suggest that cytoplasm is an important target for genotoxic effects of ionizing radiation, particularly radon, the second leading cause of lung cancer in the United States. In addition, cytoplasmic traversal by alpha particles may be more dangerous than nuclear traversal, because the mutagenicity is accomplished by little or no killing of the target cells.

  14. Study of radiation effects on the cell structure and evaluation of the dose delivered by x-ray and {alpha}-particles microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kosior, Ewelina; Cloetens, Peter [European Synchrotron Radiation Facility, F-38000 Grenoble (France); Deves, Guillaume; Ortega, Richard [Univ. Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Bohic, Sylvain [European Synchrotron Radiation Facility, 38000 Grenoble (France); INSERM U-836 (Team 6: Synchrotron Radiation and Medical Research), Grenoble Institut of Neuroscience, F-38000 Grenoble (France)

    2012-12-24

    Hard X-ray fluorescence microscopy and magnified phase contrast imaging are combined to study radiation effects on cells. Experiments were performed on freeze-dried cells at the nano-imaging station ID22NI of the European synchrotron radiation facility. Quantitative phase contrast imaging provides maps of the projected mass and is used to evaluate the structural changes due to irradiation during X-ray fluorescence experiments. Complementary to phase contrast imaging, scanning transmission ion microscopy is performed and doses of all the experiments are compared. We demonstrate the sensitivity of the proposed approach to study radiation-induced damage at the sub-cellular level.

  15. ICRF enhancement of fusion reactivity in the presence of alpha particles

    International Nuclear Information System (INIS)

    Absorption of ICRF (ion cyclotron range of frequency) waves by alpha particles and fusion reactivity enhancement due to the ICRF induced ion tail are investigated. The rate of linear absorption by alpha particles increases with the cyclotron harmonic number, and decreases with the ratio of the electron plasma frequency to the electron cyclotron frequency. The deformation of the distribution due to ICRF waves is also examined by using a solution to a Fokker-Planck equation combined with a quasi-linear RF (radiofrequency) diffusion term. It is found that second harmonic ICRF heating is comparatively applicable to the enhancement of the fusion power density even in the presence of alpha particles, while the efficiency of the enhancement is deteriorated markedly by wave deposition to alphas for higher harmonic ICRF heating in the high magnetic field. (author)

  16. Feasibility of alpha particle measurement by CO2 laser Thomson scattering

    International Nuclear Information System (INIS)

    The feasibility of CO2 laser Thomson scattering from a multi-component burning plasma has been evaluated for the measurement of the velocity distribution of D-T produced alpha particles. The density and velocity distribution of the alpha particles from their initial energy of 3.5 MeV down to near-thermal energies may be measured by small angle (0) Thomson scattering. A computer simulation of the experiment indicates that a 100 MW pulsed laser combined with a bank of heterodyne receivers will be able to measure a scattered signal from the alpha particles with a post-detection signal-to-noise ratio of 75 for an assumed alpha density of 7.5 x 1011 cm-3

  17. Nuclear structure and reaction mechanisms studied on alpha-particle transitions

    International Nuclear Information System (INIS)

    Since the observation of the natural alpha decay of atomic nuclei the alpha particle was and is considered as an important component of the nuclear matter. The modern studies of alpha-particle transfer reactions are devoted to the question on four-particle correlations (alpha-particle clusters) generally in nuclear matter or also on nuclear surfaces. Thereby one is today yet absolutely far away from a unified picture of the mechanism of the alpha transfer: It is shown that different reaction and nuclear models must be used with different success for the interpretation of the data. Theoretical and experimental determination of spectroscopic strength distribution were thereby developed mutually supportingly each other. On the experimental side the question of the reaction mechanism and the determination of its details is to be clarified. Here approaches were developed which lead to a unified description in the sd shell. Calculations in the formalism of the coupled channels with spectroscopic factors calculated in the framework of the shell model lead to convincing agreements between theoretical and experimental angular distributions regarding both their shape and their amplitude. Hereby it was shown that beside the determination of the potential parameters a two-stage reaction mechanism as in an alpha-particle transition after or before an inelastic excitation of the target or residual nucleus is of decicive importance. (HSI)

  18. Biological radiation effects

    International Nuclear Information System (INIS)

    The book covers all aspects of biological radiation effects and provides the fundamental basis for understanding the necessity of radiation protection as well as applications in radiotherapy. The physical basis is dealt with in some detail, and the effects at the subcellular and the cellular level are thoroughly discussed, taking into account modern developments and techniques. The effects on the human organism are reviewed, both from the point of view of applications in medicine as well as with regard to radiation hazards (teratogenic, gonadal and carcinogenic effects). It can be used by graduate students as an introduction and as a source book for all who want to become acquainted with this important field. It is an extended version of the original German book containing updated information and new material. (orig.) With 273 figs

  19. Controlling seepage in discrete particle simulations of biological systems.

    Science.gov (United States)

    Gardiner, Bruce S; Joldes, Grand R; Wong, Kelvin K L; Tan, Chin Wee; Smith, David W

    2016-08-01

    It is now commonplace to represent materials in a simulation using assemblies of discrete particles. Sometimes, one wishes to maintain the integrity of boundaries between particle types, for example, when modelling multiple tissue layers. However, as the particle assembly evolves during a simulation, particles may pass across interfaces. This behaviour is referred to as 'seepage'. The aims of this study were (i) to examine the conditions for seepage through a confining particle membrane and (ii) to define some simple rules that can be employed to control seepage. Based on the force-deformation response of spheres with various sizes and stiffness, we develop analytic expressions for the force required to move a 'probe particle' between confining 'membrane particles'. We analyse the influence that particle's size and stiffness have on the maximum force that can act on the probe particle before the onset of seepage. The theoretical results are applied in the simulation of a biological cell under unconfined compression. PMID:26629728

  20. Biological effects of neutrons

    International Nuclear Information System (INIS)

    Although the occasion to be exposed to neutrons is rare in our life, except for nuclear accidents like in the critical accident at Tokai-mura in 1999, countermeasures against accident should be always prepared. In the Tokai-mura accident, residents received less than 21 mSv of neutrons and gamma rays. The cancer risks and fetal effects of low doses of neutrons were matters of concern among residents. The purpose of this program is to investigate the relative biological effectiveness (RBE) for leukemias, and thereby to assess risks of neutrons. Animal experiments are planed to obtain the following RBEs: (1) RBE for the induction of leukemias in mice and (2) RBE for effects on fetuses. Cyclotron fast neutrons (10 MeV) and electrostatic accelerator-derived neutrons (2 MeV) are used for exposure in this program. Furthermore, cytological and cytogenetic analyses will be performed. (author)

  1. Effect of Pilates Training on Alpha Rhythm

    OpenAIRE

    Zhijie Bian; Hongmin Sun; Chengbiao Lu; Li Yao; Shengyong Chen; Xiaoli Li

    2013-01-01

    In this study, the effect of Pilates training on the brain function was investigated through five case studies. Alpha rhythm changes during the Pilates training over the different regions and the whole brain were mainly analyzed, including power spectral density and global synchronization index (GSI). It was found that the neural network of the brain was more active, and the synchronization strength reduced in the frontal and temporal regions due to the Pilates training. These results support...

  2. Alfven Eigenmode And Ion Bernstein Wave Studies For Controlling Fusion Alpha Particles

    CERN Document Server

    Franklin, F R

    1999-01-01

    In magnetic confinement fusion reactor plasmas, the charged fusion products (such as alpha particles in deuterium-tritium plasmas) will be the dominant power source, and by controlling these charged fusion products using wave-particle interactions the reactor performance could be optimized. This thesis studies two candidate waves: Mode- Converted Ion Bernstein Waves (MCIBWs) and Alfvé n Eigenmodes (AEs). Rates of MCIBW-driven losses of alpha-like fast deuterons, previously observed in the Tokamak Fusion Test Reactor (TFTR), are reproduced by a new model so that the wave-particle diffusion coefficient can be deduced. The MCIBW power in TFTR is found to be ∼ 1/3 that needed for collisionless alpha particle control...

  3. Cell survival following alpha particle irradiation: critical sites and implications for carcinogenesis

    International Nuclear Information System (INIS)

    In experiments in which mammalian cells were irradiated with 5.6 MeV alpha particles from a Tandem Van de Graaff machine we have confirmed the finding of others that the mean lethal dose (D0) is about 100 rad, but by measurements of the area of the cell nuclei as irradiated we found that this mean lethal dose corresponds not to 1, as expected, but to about 27 alpha particles per cell nucleus. (The exact number appears to change slightly with cell passage number.) This allows for the possibility that the direct action of alpha particles on the nucleus may be the important event in carcinogenesis, a theory which was previously difficult to accept if a single particle hitting the nucleus anywhere was considered to be lethal. Evidence is presented to implicate the nucleolus as a possible critical site for the inhibition of reproductive integrity of the cell

  4. Selective alpha-particle mediated depletion of tumor vasculature with vascular normalization.

    Directory of Open Access Journals (Sweden)

    Jaspreet Singh Jaggi

    Full Text Available BACKGROUND: Abnormal regulation of angiogenesis in tumors results in the formation of vessels that are necessary for tumor growth, but compromised in structure and function. Abnormal tumor vasculature impairs oxygen and drug delivery and results in radiotherapy and chemotherapy resistance, respectively. Alpha particles are extraordinarily potent, short-ranged radiations with geometry uniquely suitable for selectively killing neovasculature. METHODOLOGY AND PRINCIPAL FINDINGS: Actinium-225 ((225Ac-E4G10, an alpha-emitting antibody construct reactive with the unengaged form of vascular endothelial cadherin, is capable of potent, selective killing of tumor neovascular endothelium and late endothelial progenitors in bone-marrow and blood. No specific normal-tissue uptake of E4G10 was seen by imaging or post-mortem biodistribution studies in mice. In a mouse-model of prostatic carcinoma, (225Ac-E4G10 treatment resulted in inhibition of tumor growth, lower serum prostate specific antigen level and markedly prolonged survival, which was further enhanced by subsequent administration of paclitaxel. Immunohistochemistry revealed lower vessel density and enhanced tumor cell apoptosis in (225Ac-E4G10 treated tumors. Additionally, the residual tumor vasculature appeared normalized as evident by enhanced pericyte coverage following (225Ac-E4G10 therapy. However, no toxicity was observed in vascularized normal organs following (225Ac-E4G10 therapy. CONCLUSIONS: The data suggest that alpha-particle immunotherapy to neovasculature, alone or in combination with sequential chemotherapy, is an effective approach to cancer therapy.

  5. The Alpha Dynamo Effects in Laboratory Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hantao Ji; Stewart C. Prager

    2001-10-16

    A concise review of observations of the alpha dynamo effect in laboratory plasmas is given. Unlike many astrophysical systems, the laboratory pinch plasmas are driven magnetically. When the system is overdriven, the resultant instabilities cause magnetic and flow fields to fluctuate, and their correlation induces electromotive forces along the mean magnetic field. This alpha-effect drives mean parallel electric current, which, in turn, modifies the initial background mean magnetic structure towards the stable regime. This drive-and-relax cycle, or the so-called self-organization process, happens in magnetized plasmas in a timescale much shorter than resistive diffusion time, thus it is a fast and unquenched dynamo process. The observed alpha-effect redistributes magnetic helicity (a measure of twistedness and knottedness of magnetic field lines) but conserves its total value. It can be shown that fast and unquenched dynamos are natural consequences of a driven system where fluctuations are statistically either not stationary in time or not homogeneous in space, or both. Implications to astrophysical phenomena will be discussed.

  6. An alpha-omega-dynamo with an alpha-effect due to magnetostrophic waves

    Science.gov (United States)

    Schmitt, D.

    1987-03-01

    The effects of the latitude dependence of the dynamic alpha-effect on the solution of equations of alpha-omega-dynamos are investigated. The equations of kinematic rotationally symmetric alpha-omega-dynamos are evaluated using the spherical solar dynamo model of Deinzer and Stix (1971), in which the induction effects, differential rotation, and alpha-effect act in two separate infinitesimal thin shells. Butterfly diagrams are derived and analyzed. It is observed that the diagram has two branches: the ordinary sunspot branch, migrating from midlatitudes toward the equator during the cycle, and the polar branch, which migrates from the midlatitudes toward the pole. It is also found that, in order to obtain the correct propagation direction of the two dynamos, the alpha of the magnetostrophic waves requires a rotation decreasing with depth. The influence of various locations of the induction layers of alpha- and omega-effect are examined.

  7. Formulation of alpha-particle condensation in the macroscopic limit

    International Nuclear Information System (INIS)

    Following closely BCS theory for pairs, an eventually viable theory for α-particle condensation (quartetting) is sketched. In the final formula the quartet wave function is replaced by a Slater determinant projected on good total momentum. The only variational field is then the single particle 0S wave function. This should reduce the numerical complexity to solve the quartet equations considerably. (author)

  8. TCAD simulation for alpha-particle spectroscopy using SIC Schottky diode

    International Nuclear Information System (INIS)

    There is a growing requirement of alpha spectroscopy in the fields context of environmental radioactive contamination, nuclear waste management, site decommissioning and decontamination. Although silicon-based alpha-particle detection technology is mature, high leakage current, low displacement threshold and radiation hardness limits the operation of the detector in harsh environments. Silicon carbide (SiC) is considered to be excellent material for radiation detection application due to its high band gap, high displacement threshold and high thermal conductivity. In this report, an alpha-particle-induced electron-hole pair generation model for a reverse-biased n-type SiC Schottky diode has been proposed and verified using technology computer aided design (TCAD) simulations. First, the forward-biased I-V characteristics were studied to determine the diode ideality factor and compared with published experimental data. The ideality factor was found to be in the range of 1.4-1.7 for a corresponding temperature range of 300-500 K. Next, the energy-dependent, alpha-particle-induced EHP generation model parameters were optimised using transport of ions in matter (TRIM) simulation. Finally, the transient pulses generated due to alpha-particle bombardment were analysed for (1) different diode temperatures (300-500 K), (2) different incident alpha-particle energies (1-5 MeV), (3) different reverse bias voltages of the 4H-SiC-based Schottky diode (-50 to -250 V) and (4) different angles of incidence of the alpha particle (0 deg. -70 deg. ).The above model can be extended to other (wide band-gap semiconductor) device technologies useful for radiation-sensing application. (authors)

  9. Plasmon resonant particles for biological detection.

    Science.gov (United States)

    Schultz, David A

    2003-02-01

    Several recent advances in the optical observation, fabrication, and bioconjugation of nanometer-sized gold or silver colloids have produced a robust new class of label. These plasmon resonant particle (PRP) conjugates have several important advantages: they are ultra-bright, so the light scattered from the individual particles can be viewed using a simple optical microscope system with a white light illumination source; they do not photo-bleach; PRPs can be prepared that preferentially scatter light of a chosen color; and it is possible to prepare bioconjugated PRPs that are stable in solution. These properties, and the automation of PRP identification, discrimination, and counting, have enabled the development of ultrasensitive, multicolor, and multiplex applications in the life science field. PMID:12565997

  10. Low doses of alpha particles do not induce sister chromatid exchanges in bystander Chinese hamster cells defective in homologous recombination

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, H; Wilson, P F; Chen, D J; Thompson, L H; Bedford, J S; Little, J B

    2007-10-26

    We reported previously that the homologous recombinational repair (HRR)-deficient Chinese hamster mutant cell line irs3 (deficient in the Rad51 paralog Rad51C) showed only a 50% spontaneous frequency of sister chromatid exchange (SCE) as compared to parental wild-type V79 cells. Furthermore, when irradiated with very low doses of alpha particles, SCEs were not induced in irs3 cells, as compared to a prominent bystander effect observed in V79 cells (Nagasawa et al., Radiat. Res. 164, 141-147, 2005). In the present study, we examined additional Chinese hamster cell lines deficient in the Rad51 paralogs Rad51C, Rad51D, Xrcc2, and Xrcc3 as well as another essential HRR protein, Brca2. Spontaneous SCE frequencies in non-irradiated wild-type cell lines CHO, AA8 and V79 were 0.33 SCE/chromosome, whereas two Rad51C-deficient cell lines showed only 0.16 SCE/chromosome. Spontaneous SCE frequencies in cell lines defective in Rad51D, Xrcc2, Xrcc3, and Brca2 ranged from 0.23-0.33 SCE/chromosome, 0-30% lower than wild-type cells. SCEs were induced significantly 20-50% above spontaneous levels in wild-type cells exposed to a mean dose of 1.3 mGy of alpha particles (<1% of nuclei traversed by an alpha particle). However, induction of SCEs above spontaneous levels was minimal or absent after {alpha}-particle irradiation in all of the HRR-deficient cell lines. These data suggest that Brca2 and the Rad51 paralogs contribute to DNA damage repair processes induced in bystander cells (presumably oxidative damage repair in S-phase cells) following irradiation with very low doses of alpha particles.

  11. Two-photon excited fluorescence from biological aerosol particles

    International Nuclear Information System (INIS)

    We used a 40 MHz mode-locked 524 nm laser source to evaluate the utility of sub-picosecond excitation of fluorescence from 2-photon absorption in biological aerosols. Individual particles of biological composition, as well as other calibration particles, suspended in an inlet air flow were illuminated and measured as they passed through an optical chamber. To our knowledge, this was the first demonstration of 2-photon excited fluorescence from micron-sized particles composed of micro-organisms. We also observed a high fluorescence signal at visible wavelengths, which was not present with single-photon excitation.

  12. Alpha-particle emission probabilities in the decay of {sup 240}Pu

    Energy Technology Data Exchange (ETDEWEB)

    Sibbens, G., E-mail: goedele.sibbens@ec.europa.e [European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Pomme, S.; Altzitzoglou, T. [European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Garcia-Torano, E. [Laboratorio de Metrologia de Radiaciones Ionizantes, CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Janssen, H.; Dersch, R.; Ott, O. [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany); Martin Sanchez, A. [Departamento de Fisica, Universidad de Extremadura, Badajoz, E-06071 (Spain); Rubio Montero, M.P. [Departamento de Fisica Aplicada, Universidad de Extremadura, Merida, Badajoz, E-06800 (Spain); Loidl, M. [Laboratoire National Henri Becquerel, LNE/CEA-LIST, 91191 Gif-sur-Yvette (France); Coron, N.; Marcillac, P. de [Institut d' Astrophysique Spatiale, CNRS, 91405 Orsay Campus (France); Semkow, T.M. [Wadsworth Center, New York State Department of Health, Albany, NY 12201 (United States)

    2010-07-15

    Sources of enriched {sup 240}Pu were prepared by vacuum evaporation on quartz substrates. High-resolution alpha-particle spectrometry of {sup 240}Pu was performed with high statistical accuracy using silicon detectors and with low statistical accuracy using a bolometer. The alpha-particle emission probabilities of six transitions were derived from the spectra and compared with literature values. Additionally, some alpha-particle emission probabilities were derived from {gamma}-ray intensity measurements with a high-purity germanium detector. The alpha-particle emission probabilities of the three main transitions at 5168.1, 5123.6 and 5021.2 keV were derived from seven aggregate spectra analysed with five different fit functions and the results were compatible with evaluated data. Two additional weak peaks at 4863.5 and 4492.0 keV were fitted separately, using the exponential of a polynomial function to represent the underlying tailing of the larger peaks. The peak at 4655 keV could not be detected by alpha-particle spectrometry, while {gamma}-ray spectrometry confirms that its intensity is much lower than expected from literature.

  13. Nuclear transparency in {alpha}-particle scattering beyond the eikonal approach

    Energy Technology Data Exchange (ETDEWEB)

    Eliseev, S.M. [Bogoliubov Laboraroty of Theoretical Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Hanna, K.M. [Matematics and Theoretical Physics Departement, AtomyEnergy Authority, Cairo (Egypt)

    1999-08-01

    An independent, complementary, and unbiased study to calculate the transparency functions beyond the eikonal approach by adding the higher-order (up to the third-order term) non eikonal (Ne) corrections, in five different effective optical potentials all of them reproduce well the elastic scattering of intermediate energy {alpha}-particles ({epsilon}{sub {alpha}} 140-288 MeV) from the two neighborly nuclei {sup 48}Ti and {sup 58}Ni. The effects of switching (off/on) the Coulomb potential on the results are studied. The individual and the combined effects of the Ne corrections and Coulomb potential are explored in the transparency function for a wide range of the impact parameter 'b' from the nuclear surface towards the nuclear interior. No violation is detected in the flux conservation for the considered projectile incident energy and the impact parameter ranges. It is found that, in some cases, it is not necessarily true, as usually believed, that the Coulomb potential decreases the absorption (less transparency) in the central region of the nucleus, the phenomenon which can be explained by a modification of the balance between the nominal real and imaginary parts of some optical potential in the rather complicate transparency function.

  14. Collisional stochastic ripple diffusion of alpha particles and beam ions on TFTR

    International Nuclear Information System (INIS)

    Predictions for ripple loss of fast ions from TFTR are investigated with a guiding center code including both collisional and ripple effects. A synergistic enhancement of fast ion diffusion is found for toroidal field ripple with collisions. The total loss is calculated to be roughly twice the sum of ripple and collisional losses calculated separately. Discrepancies between measurements and calculations of plasma beta at low current and large major radius are resolved when both effects are included for neutral beam ions. A 20--30% reduction in alpha particle heating is predicted for qa = 6--14, R = 2.6 m DT plasmas on TFTR due to first orbit and collisional stochastic ripple diffusion

  15. Gas production due to alpha particle degradation of polyethylene and polyvinylchloride

    International Nuclear Information System (INIS)

    Alpha particle degradation experiments were performed on polyethylene (PE) and polyvinylchloride (PVC) plastic samples typical of Westinghouse Savannah River Company (WSRC) transuranic (TRU) waste. This was done to evaluate the effects of sealing TRU waste during shipment. Experiments were conducted at three temperatures using low dose rates. Predominant products from both plastics were hydrogen, carbon dioxide, and various organic species, with the addition of hydrochloric acid from PVC. In all experiments, the total pressure decreased. Irradiation at 30 and 60 C and at various dose rates caused small changes for both plastics, but at 100 C coupled thermal-radiolytic effects included discoloration of the material as well as large differences in the gas phase composition

  16. Review of alpha-particle spectrometric measurements of actinides

    International Nuclear Information System (INIS)

    At present the silicon surface-barrier detector is the most used α-particle detector mainly due to its high energy resolution, excellent stability, low background and low cost. In this presentation various parameters of importance for α-particle spectrometry are discussed, i.e. energy resolution and interval selection, energy calibration, background and peak tailing. Examples of α-particle spectra recorded from various actinides (Th, U, Np, Pu, Am, and Cm) separated from environmental samples are shown, and the choice of yield determinants is discussed for each case. (author)

  17. Alpha particles spectrometer with photodiode PIN; Espectrometro de particulas alfa con fotodiodo PIN

    Energy Technology Data Exchange (ETDEWEB)

    Chacon R, A.; Hernandez V, R.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidades Academicas de Estudios Nucleares e Ingenieria Electrica, Calle Cipres No. 10, Fracc. La Penuela, 09869 Zacatecas (Mexico); Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Direccion General de Innovacion y Tecnologia de Informacion, Av. Heroes de Nacozari Sur 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico)], e-mail: achruiz@hotmail.com

    2009-10-15

    The radiation propagates in form of electromagnetic waves or corpuscular radiation; if the radiation energy causes ionization in environment that crosses it is considered ionizing radiation. To detect radiation several detectors types are used, if the radiation are alpha particles are used detectors proportional type or trace elements. In this work the design results, construction and tests of an alpha particles spectrometer are presented, which was designed starting from a photodiode PIN type. The system design was simulated with a code for electronic circuits. With results of simulation phase was constructed the electronic phase that is coupled to a multichannel analyzer. The resulting electronic is evaluated analyzing the electronic circuit performance before an alphas triple source and alpha radiation that produce two smoke detectors of domestic use. On the tests phase we find that the system allows obtain, in a multichannel, the pulses height spectrum, with which we calibrate the system. (Author)

  18. Alpha-particle clustering in excited expanding self-conjugate nuclei

    CERN Document Server

    Borderie, B; Ademard, G; Rivet, M F; De Filippo, E; Geraci, E; Neindre, N Le; Cardella, G; Lanzalone, G; Lombardo, I; Lopez, O; Maiolino, C; Pagano, A; Pirrone, S; Politi, G; Rizzo, F; Russotto, P

    2016-01-01

    The fragmentation of quasi-projectiles from the nuclear reaction 40Ca + 12C at 25 MeV/nucleon was used to produce alpha-emission sources. From a careful selection of these sources provided by a complete detection and from comparisons with models of sequential and simultaneous decays, strong indications in favour of $\\alpha$-particle clustering in excited 16O, 20Ne and 24}Mg are reported.

  19. Radon exposure of the skin: I. Biological effects

    Energy Technology Data Exchange (ETDEWEB)

    Charles, M W [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2007-09-15

    Radon progeny can plate out on skin and give rise to exposure of the superficial epidermis from alpha emitters Po-218 (7.7 MeV, range {approx}66 {mu}m) and Po-214 (6 MeV, range {approx}44 {mu}m). Dose rates from beta/gamma emitters Pb-214 and Bi-214 are low and only predominate at depths in excess of the alpha range. This paper reviews the evidence for a causal link between exposure from radon and its progeny, and deterministic and stochastic biological effects in human skin. Radiation induced skin effects such as ulceration and dermal atrophy, which require irradiation of the dermis, are ruled out for alpha irradiation from radon progeny because the target cells are considerably deeper than the range of alpha particles. They have not been observed in man or animals. Effects such as erythema and acute epidermal necrosis have been observed in a few cases of very high dose alpha particle exposures in man and after acute high dose exposure in animals from low energy beta radiations with similar depth doses to radon progeny. The required skin surface absorbed doses are in excess of 100 Gy. Such effects would require extremely high levels of radon progeny. They would involve quite exceptional circumstances, way outside the normal range of radon exposures in man. There is no definitive identification of the target cells for skin cancer induction in animals or man. The stem cells in the basal layer which maintain the epidermis are the most plausible contenders for target cells. The majority of these cells are near the end of the range of radon progeny alpha particles, even on the thinnest body sites. The nominal depth of these cells, as recommended by the International Commission on Radiological Protection (ICRP), is 70 {mu}m. There is evidence however that some irradiation of the hair follicles and/or the deeper dermis, as well as the inter-follicular epidermis, is also necessary for skin cancer induction. Alpha irradiation of rodent skin that is restricted to the

  20. Radon exposure of the skin: I. Biological effects

    International Nuclear Information System (INIS)

    Radon progeny can plate out on skin and give rise to exposure of the superficial epidermis from alpha emitters Po-218 (7.7 MeV, range ∼66 μm) and Po-214 (6 MeV, range ∼44 μm). Dose rates from beta/gamma emitters Pb-214 and Bi-214 are low and only predominate at depths in excess of the alpha range. This paper reviews the evidence for a causal link between exposure from radon and its progeny, and deterministic and stochastic biological effects in human skin. Radiation induced skin effects such as ulceration and dermal atrophy, which require irradiation of the dermis, are ruled out for alpha irradiation from radon progeny because the target cells are considerably deeper than the range of alpha particles. They have not been observed in man or animals. Effects such as erythema and acute epidermal necrosis have been observed in a few cases of very high dose alpha particle exposures in man and after acute high dose exposure in animals from low energy beta radiations with similar depth doses to radon progeny. The required skin surface absorbed doses are in excess of 100 Gy. Such effects would require extremely high levels of radon progeny. They would involve quite exceptional circumstances, way outside the normal range of radon exposures in man. There is no definitive identification of the target cells for skin cancer induction in animals or man. The stem cells in the basal layer which maintain the epidermis are the most plausible contenders for target cells. The majority of these cells are near the end of the range of radon progeny alpha particles, even on the thinnest body sites. The nominal depth of these cells, as recommended by the International Commission on Radiological Protection (ICRP), is 70 μm. There is evidence however that some irradiation of the hair follicles and/or the deeper dermis, as well as the inter-follicular epidermis, is also necessary for skin cancer induction. Alpha irradiation of rodent skin that is restricted to the epidermis does not

  1. The 1997 IAEA intercomparison of commercially available PC-based software for alpha-particle spectrometry

    CERN Document Server

    Blaauw, M; Woods, S; Fazinic, S

    1999-01-01

    Four commercially available, PC-based analysis programs for alpha-particle spectrometry were compared using the 1997 IAEA test spectra, i.e. AlphaVision 1.20 (EG and G Ortec, USA), Alps 4.21 (Westmeier GmbH, Germany), Winner Alpha 4.0f5 (Eurisys Mesures, France) and Genie-2000 (Canberra Industries Inc., USA). A systematic statistical study of the analysis results was performed based on z-scores. The results indicate that the four programs leave room for substantial improvement.

  2. Emission of alpha particles and other light nuclei as a fission process

    International Nuclear Information System (INIS)

    The fission theory was successfully applied to the emission of alpha particles and other light nuclei from a heavy nucleus. Good agreement (within +-0.8 orders of magnitude) of the theoretical life times with experimental ones over a range of 24 orders of magnitude, was obtained. Three macroscopic models have been extended for the nuclear systems with different charge densities. A phenomenological shell correction was introduced. WKB approximation was used. By taking into account the nuclear deformation, the life-time of the alpha decay from a shape isomeric state was predicted. A new semiempirical relationship for the alpha decay life-time was derived. (author)

  3. Feasibility of alpha particle measurement in a magnetically confined plasma by CO2 laser Thomson scattering

    International Nuclear Information System (INIS)

    Fusion-product alpha particles will dominate the behavior of the next generation of ignited D-T fusion reactors. Advanced diagnostics will be required to characterize the energy deposition of these fast alpha particles in the magnetically confined plasma. For small-angle coherent Thomson scattering of a CO2 laser beam from such a plasma, a resonance in the scattered power occurs near 900 with respect to the magnetic field direction. This spatial concentration permits a simplified detection of the scattered laser power from the plasma using a heterodyne system. The signal produced by the presence of fusion-product alpha particles in an ignited plasma is calculated to be well above the noise level, which results from statistical variations of the background signal produced by scattering from free electrons. 7 refs

  4. An application of 222Rn alpha particle's tracks to uranium exploration

    International Nuclear Information System (INIS)

    The uranium exploration method is based on the register of 222Rn alpha particles; 222Rn gas is generated in the chain 238U desintegration. The detection of alpha particles was performed with cellulose nitrate films (NTC), located in a grid at the region in study. The alpha particles produce latent tracks in the NTC films; these tracks may be enlarged by chemical etching and are observed with an ordinary optic microscope, ninety seven NTC films were used, these were distributed in an area of approximately seventeen square kilometers, located in the municipalities of Granados and Huasabas in Sonora Mexico, the detectors remain in the ground for a thirty days mean period. The results obtained show an area with high 222Rn concentration, this can be related with an underground uranium ore deposit. The more important conclusion is that the results obtained in this work can be used as preliminary results for other prospection methods in this particular area. (author)

  5. High resolution alpha particle detectors based on 4H-SiC epitaxial layer

    International Nuclear Information System (INIS)

    We fabricated and characterized 4H-SiC Schottky diodes as a spectrometric detector of alpha particles. A thin blocking contact of Ni/Au (15 nm) was used to minimize the influence on alpha particles energy. Current-voltage characteristics of the detector were measured and a low current density below 0.3 nAcm−2 was observed at room temperature. 239Pu241Am244Cm was used as a source of alpha particles within the energy range between 5.1 MeV and 5.8 MeV for detector testing. The charge collection efficiency close to 100 % at reverse bias exceeding 50 V was determined. The best spectrometric performance shows a pulse height spectrum at a reverse bias of 200 V giving an energy resolution of 0.25 % in the full width and half maximum for 5.486 MeV of 241Am

  6. Intrinsic efficiency of LR-115 in alpha particles detection: simulations and experiments

    International Nuclear Information System (INIS)

    A numerical simulation is developed to characterize the response of the cellulose nitrate detector ''LR-115 type II'' to alpha particles of different incidence angles and energies. It permits to know whether an alpha particle at a given energy and direction is able to produce a visible etched track or not. For this purpose, a Vt-variable track etch rate model is used. We have considered that the track etch rate is a function of the ionization rate and the defect created by delta rays along the alpha particle trajectory. Validation of the model is presented in the form of comparisons between theoretically computed values of the sensitive energy range and the track diameters and experimentally determined ones

  7. Biological particles capable of triggering ice nucleation in the atmosphere

    Science.gov (United States)

    Felgitsch, Laura; Bichler, Magdalena; Vogel, André; Häusler, Thomas; Grothe, Hinrich

    2016-04-01

    Ice-nucleating particles (INPs) have a huge impact on atmospheric processes, since they can trigger ice cloud formation. In general, ice clouds interfere with the radiation balance of planet Earth effectively at high altitudes. Since ambient matter of biological origin tends to have rather large aerodynamic diameters, it exhibits a fast sinking velocity and can only reach limited altitudes. Therefore, research focused on materials found in higher quantities in the upper atmosphere. However, recent findings indicate that the role of biological INPs has been underestimated in the past. In 2012 Pummer and colleagues found that the INPs from birch pollen can be washed off and constitute of macromolecules in the size-range of a few nanometres. With such a small diameter, they show a much longer life span in the upper atmosphere than expected. Further, Huffman and colleagues showed in 2013 a burst of biological INPs over woodlands triggered by rain events, which matches the finding of Pummer et al. well. Plants originating from the northern timberline experience harsh conditions with night frost even during the warm seasons. To prevent frost damages, those plants developed coping mechanisms. Many plant species, which are domestic in cold weather zones, exhibit ice nucleation activity. Therefore, it is important to examine those plants to understand the scale at which biological INPs can be emitted. For the presented results we focus on two types of samples: Berries and tree pollen. Both belong to plants domestic at the northern timberline. With our results we are able to show that INPs are spread vastly throughout different species. Furthermore, all those INPs show certain similarities to each other, most importantly, all of the found INPs seem to be associated to macromolecules in the nano-particulate size range. We examined the INPs from birch pollen more closely. Results indicate that proteins play a major role. Pummer, B., Bauer, H., Bernardi, J., Bleicher, S

  8. Questions of the optical potential for alpha-particles at low energies

    International Nuclear Information System (INIS)

    Among the high-priority elements for the accelerator driven systems (ADS) and fusion-reactor projects are also Zr, Mo and Li, so that the corresponding nuclear data for nucleon-, deuteron-, and α-particle interactions are of actual interest for neutron production, activation, heating, shielding requirements, and material damage estimation as well as radioactive waste transmutation projects. By using advanced nuclear models that account for details of nuclear structure and the quantum nature of the nuclear scattering, significant gains in accuracy can be achieved below 150 MeV, where intranuclear cascade calculations become less accurate. It is why this work reports on the progress of the analysis of optical potentials for nucleons, deuterons and α-particles on isotopes of these elements, and corresponding reaction cross sections calculations. The elastic-scattering angular distributions measured at deuteron energies between 3 and 50 MeV on the target nucleus 6Li, and between 1 and 14.7 MeV for the target nucleus 7Li have been thus analyzed by using the computer codes SCAT2 for pure elastic scattering processes and FRESCO for the coupled reaction channels for taking into account the effects of the elastic and inelastic alpha transfer in the d+6Li interaction. The good overall agreement obtained with the experimental data for both 6,7Li target nuclei from 1 to 50 MeV has finally proved suitable optical model potentials (OMPs). Within the double folding formalism of the alpha-nucleus optical potential, used previously for a semi-microscopic analysis of the alpha-particle elastic scattering on A∼100 nuclei at energies below 32 MeV, effects due to changes of the nuclear density at a finite temperature are considered. Parameterizations of the double-folding (DF) real potential as well as of a regional phenomenological potential have been used in the study of the (n,α) reaction cross sections for the target nuclei 92,95,98,100Mo. Taking the microscopic DF potentials

  9. Alpha-particle confinement control of the geodesic winding of LHD-type fusion reactors

    International Nuclear Information System (INIS)

    It is calculated that the geodesic winding D-shaped helical magnetic field configuration can actively control the confinement and exhaust of alpha particles. A trapped particle orbit diagram (TPOD), which shows the presence of re-entering particles and specifies the loss-cone depth, is obtained from the deeply trapped particle orbits in a helical mirror magnetic field. The loss-cone depth becomes shallow when the magnetic axis is shifted to the inner side. On the other hand, the loss-cone depth can reach to the magnetic axis when the magnetic axis is shifted fairly to the outer side. Active control of the confinement and exhaust of 3.52 MeV alpha particles by controlling the magnetic axis position is also confirmed by collisionless orbit calculations. (author)

  10. Stochastic loss of alpha particles in a Helias reactor

    International Nuclear Information System (INIS)

    It is shown that collisionless orbit transformation of the locally trapped particles to the locally passing ones and vice versa in the Wendelstein-line optimized stellarators results in stochastic diffusion of energetic ions. This diffusion can lead to the loss of an essential fraction of energetic ion population from the region where the characteristic diffusion time is small compared to the slowing down time. The loss region and the magnitude of the loss can be minimized by shaping the plasma temperature and density profiles so that they satisfy certain requirements. The predictions of the developed theory are in agreement with the results of numerical modelling of confinement of α-particles in a Helias reactor, which was carried out in this work with the use of the orbit following code. The considered diffusion seems to represent the dominant mechanism of classical losses of α-particles in a Helias reactor. (author)

  11. Physical and biological changes of suspended particles in a free surface flow constructed wetland

    NARCIS (Netherlands)

    B.T.M. Mulling; R.M. van den Boomen; T.H.L. Claassen; H.G. van der Geest; J.W.N.M. Kappelhof; W. Admiraal

    2013-01-01

    Suspended particles are considered as contaminants in treated wastewater and can have profound effects on the biological, physical and chemical properties of receiving aquatic ecosystems, depending on the concentration, type and nature of the suspended particles. Constructed wetlands are known to su

  12. Applying alpha particle background ionization device in the development of pulsed nitrogen laser technology

    International Nuclear Information System (INIS)

    An investigation on the application of alpha particles in the induction of a bias ionized background plasma before, during and after the discharge of the N2 TE UV laser (337.1 nm), built in the LEL-IF/UFF is presented. The alpha particles are provided by Americium (241-Am) stripes placed inside the discharge channel of the laser device. The stimulated radiation output characteristics, in terms of gas pressure, charging voltage and pulse width, of a N2 TE UV laser (337.1 nm) circuit are presented. The increased laser yield is interpreted qualitatively through plasma impedance in the discharge circuit. (author)

  13. Applying alpha particle background ionization device in the development of pulsed nitrogen laser technology

    Energy Technology Data Exchange (ETDEWEB)

    Fellows, C.E.; Rodegheri, C.C.; Tauber, U. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Fisica. Lab. de Espectroscopia e Laser (LEL); Guterres, R.F. [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao de Instalacoes Radiativas]. E-mail: rgutterr@cnen.gov.br

    2005-11-15

    An investigation on the application of alpha particles in the induction of a bias ionized background plasma before, during and after the discharge of the N2 TE UV laser (337.1 nm), built in the LEL-IF/UFF is presented. The alpha particles are provided by Americium (241-Am) stripes placed inside the discharge channel of the laser device. The stimulated radiation output characteristics, in terms of gas pressure, charging voltage and pulse width, of a N2 TE UV laser (337.1 nm) circuit are presented. The increased laser yield is interpreted qualitatively through plasma impedance in the discharge circuit. (author)

  14. The threshold states in the frame of the model of binding alpha particles

    International Nuclear Information System (INIS)

    A model of nuclear matter built from alpha-particles is proposed. In this model, nuclei possess the molecular structure. Analyzing the numbers of bonds, one gets the formula for the binding energy of a nucleus. The structure is determined by the minimum of the total potential energy, where interaction between alpha-particles is pairwise. The calculated binding energies show a good agreement with experiment. According to this model we can estimate the energy of Bose-Condensation for the 4N nuclei

  15. Effects of $\\alpha$-cluster breaking on 3$\\alpha$ cluster structures in $^{12}$C

    OpenAIRE

    Suhara, Tadahiro; Kanada-En'yo, Yoshiko

    2014-01-01

    To clarify the effects of $\\alpha$-cluster breaking on 3$\\alpha$ cluster structures in $^{12}$C, we investigate $^{12}$C using a hybrid model that combines the Brink-Bloch cluster model with the $p_{3/2}$ subshell closure wave function. We have found that $\\alpha$-cluster breaking caused by spin-orbit force significantly changes cluster structures of excited $0^{+}$ states through orthogonality to lower states. Spatially developed cluster components of the $0^{+}_{2}$ state are reduced. The $...

  16. The biological effectiveness of antiproton irradiation

    DEFF Research Database (Denmark)

    Holzscheiter, Michael H.; Bassler, Niels; Agazaryan, Nzhde;

    2006-01-01

    Background and purpose: Antiprotons travel through tissue in a manner similar to that for protons until they reach the end of their range where they annihilate and deposit additional energy. This makes them potentially interesting for radiotherapy. The aim of this study was to conduct the first...... ever measurements of the biological effectiveness of antiprotons. Materials and methods: V79 cells were suspended in a semi-solid matrix and irradiated with 46.7 MeV antiprotons, 48 MeV protons, or 60Co c-rays. Clonogenic survival was determined as a function of depth along the particle beams. Dose and...... particle fluence response relationships were constructed from data in the plateau and Bragg peak regions of the beams and used to assess the biological effectiveness. Results: Due to uncertainties in antiproton dosimetry we defined a new term, called the biologically effective dose ratio (BEDR), which...

  17. Natural protection from zoonosis by alpha-gal epitopes on virus particles in xenotransmission.

    Science.gov (United States)

    Kim, Na Young; Jung, Woon-Won; Oh, Yu-Kyung; Chun, Taehoon; Park, Hong-Yang; Lee, Hoon-Taek; Han, In-Kwon; Yang, Jai Myung; Kim, Young Bong

    2007-03-01

    Clinical transplantation has become one of the preferred treatments for end-stage organ failure, and one of the novel approaches being pursued to overcome the limited supply of human organs involves the use of organs from other species. The pig appears to be a near ideal animal due to proximity to humans, domestication, and ability to procreate. The presence of Gal-alpha1,3-Gal residues on the surfaces of pig cells is a major immunological obstacle to xenotransplantation. Alpha1,3galactosyltransferase (alpha1,3GT) catalyzes the synthesis of Gal alpha 1-3Gal beta 1-4GlcNAc-R (alpha-gal epitope) on the glycoproteins and glycolipids of non-primate mammals, but this does not occur in humans. Moreover, the alpha-gal epitope causes hyperacute rejection of pig organs in humans, and thus, the elimination of this antigen from pig tissues is highly desirable. Recently, concerns have been raised that the risk of virus transmission from such pigs may be increased due to the absence of alpha-gal on their viral particles. In this study, transgenic cells expressing alpha1,3GT were selected using 1.25 mg/ml neomycin. The development of HeLa cells expressing alpha1,3GT now allows accurate studies to be conducted on the function of the alpha-gal epitope in xenotransmission. The expressions of alpha-gal epitopes on HeLa/alpha-gal cells were demonstrated by flow cytometry and confocal microscopy using cells stained with IB4-fluorescein isothiocyanate lectin. Vaccinia viruses propagated in HeLa/alpha-gal cells also expressed alpha-gal on their viral envelopes and were more sensitive to inactivation by human sera than vaccinia virus propagated in HeLa cells. Moreover, neutralization of vaccinia virus was inhibited in human serum by 10 mm ethylene glycol bis(beta-aminoethylether)tetraacetic acid (EDTA) treatment. Our data indicated that alpha-gal epitopes are one of the major barriers to zoonosis via xenotransmission. PMID:17381684

  18. Nucleon-alpha particle interactions from inversion of scattering phase shifts

    International Nuclear Information System (INIS)

    Scattering amplitudes have been extracted from (elastic scattering) neutron-alpha (n-α) differential cross sections below threshold using the constraint that the scattering function is unitary. Real phase shifts have been obtained therefrom. A modification to the Newton iteration method has been used to solve the nonlinear equation that specifies the phase of the scattering amplitude in terms of the complete (0 to 180 deg) cross section since the condition for a unique and convergent solution by an exact iterated fixed point method, the 'Martin' condition, is not satisfied. The results compare well with those found using standard optical model search procedures. Those optical model phase shifts, from both n - α and p - α (proton-alpha) calculations in which spin-orbit effects were included, were used in the second phase of this study, namely to determine the scattering potentials by inversion of that phase shift data. A modified Newton-Sabatier scheme to solve the inverse scattering problem has been used to obtain inversion potentials (both central and spin-orbit) for nucleon energies in the range 1 to 24 MeV. The inversion interactions differ noticeably from the Woods-Saxon forms used to give the input phase shifts. Not only do those inversion potentials when used in Schroedinger equations reproduce the starting phase shifts but they are also very smooth, decay rapidly, and are as feasible as the optical model potentials of others to be the local form for interactions deduced by folding realistic two-nucleon g matrices with the density matrix elements of the alpha particle. 23 refs., 8 tabs., 9 figs

  19. Real-time Measurements of Biological Particles at Several Continental Sites using the WIBS-4A

    Science.gov (United States)

    McMeeking, G. R.; Kok, G. L.; Petters, M. D.; Wright, T.; Hader, J.; Mccubbin, I. B.; Hallar, A. G.; Twohy, C. H.; Toohey, D. W.; DeMott, P. J.; McCluskey, C.; Baumgardner, D.

    2013-12-01

    Biological particles (bacteria, fungi/fungal spores, viruses, algae and fragments of biological material) may play a significant role in modifying cloud properties by acting as ice nuclei and thus have an indirect effect on climate forcing. Little is known, however, regarding the abundance and distribution of biological particles and their importance to cloud microphysics in different environments. On-line, continuous measurement systems offer the potential to measure biological systems at high time resolution and sensitivity, providing greater insight into their distribution in the atmosphere, dispersal mechanisms and potential soures. The WIBS-4A (Wideband Integrated Bioaerosol Sensor) detects fluorescent biological material in real-time associated with individual particles. It measures five properties: a) optical size via light scattering, b) fluorescent emissions in the wavelength range 310-400 following excitation by 280 nm light, c) fluorescent emissions in the wavelength range 420-650 following excitation by 280 nm light, d) fluorescent emissions in the wavelength range 420-650 following excitation by 370 nm light, and e) particle asymmetry factor based on intensities of forward scattered light onto a 4-element detector. Together, these properties aid the classification of sampled particles that contain biofluorophores such as tryptophan or NAD(P)H, which can be found in biological particles. Here we present results from a series of laboratory, ground- and aircraft-based measurements of biological particles using the WIBS-4A. The studies include airborne measurements over the United States, ground-based measurements at a coastal site, an urban site in the southeast US and a high alpine site, and laboratory measurements of a variety of biological and non-biological particles. Our analysis focused on both the characterization of the instrument response as well as an evaluation of its suitability for performing ambient measurements and potential artifacts. We

  20. Correlations of $\\alpha$-particles in splitting of $^{12}$C nuclei by neutrons of energy of 14.1 MeV

    CERN Document Server

    Kattabekov, R R; Artemenkov, D A; Bradnova, V; Zarubin, P I; Zarubina, I G; Majling, L; Rusakova, V V; Sadovsky, A B

    2014-01-01

    Correlations of $\\alpha$-particles are studied on statistics of 400 events of splitting $^{12}$C $\\rightarrow$ 3$\\alpha$ in nuclear track emulsion exposed to $14.1 MeV$ neutrons. The ranges and emission angles of the $\\alpha$-particles are measured. Distributions over energy of $\\alpha$-particle pairs and triples are obtained.

  1. Alpha-particle momentum distributions from 12C decaying resonances

    International Nuclear Information System (INIS)

    The computed α particle momentum distributions from the decay of low-lying 12C resonances are shown. The wave function of the decaying fragments is computed by means of the complex scaled hyperspherical adiabatic expansion method. The large-distance part of the wave functions is crucial and has to be accurately calculated. We discuss energy distributions, angular distributions and Dalitz plots for the 4+, 1+ and 4- states of 12C. (author)

  2. Alpha Particles Induce Apoptosis through the Sphingomyelin Pathway

    OpenAIRE

    Seideman, Jonathan H.; Stancevic, Branka; Rotolo, Jimmy A.; McDevitt, Michael R.; Howell, Roger W.; Kolesnick, Richard N; Scheinberg, David A.

    2011-01-01

    The sphingomyelin pathway involves the enzymatic cleavage of sphingomyelin to produce ceramide, a second messenger that serves as a key mediator in the rapid apoptotic response to various cell stressors. Low-linear energy transfer (LET) γ radiation can initiate this pathway, independent of DNA damage, via the cell membrane. Whether short-ranged, high-LET a particles, which are of interest as potent environmental carcinogens, radiotherapies and potential components of dirty bombs, can act thro...

  3. Heavy-ion radiobiology: new approaches to delineate mechanisms underlying enhanced biological effectiveness.

    Science.gov (United States)

    Blakely, E A; Kronenberg, A

    1998-11-01

    Shortly after the discovery of polonium and radium by Marie Curie and her husband and colleague, Pierre Curie, it was learned that exposure to these alpha-particle emitters produced deleterious biological effects. The mechanisms underlying the increased biological effectiveness of densely ionizing radiations, including alpha particles, neutrons and highly energetic heavy charged particles, remain an active area of investigation. In this paper, we review recent advances in several areas of the radiobiology of these densely ionizing radiations, also known as heavy ions. Advances are described in the areas of DNA damage and repair, chromosome aberrations, mutagenesis, neoplastic transformation in vitro, genomic instability, normal tissue radiobiology and carcinogenesis in vivo. We focus on technical innovations, including novel applications of pulsed-field gel electrophoresis, fluorescence in situ hybridization (FISH), linkage analysis, and studies of gene expression and protein expression. We also highlight the use of new cellular and animal systems, including those with defined DNA repair deficiencies, as well as epithelial cell model systems to assess neoplastic transformation both in vitro and in vivo. The studies reviewed herein have had a substantial impact on our understanding of the genotoxic effects of heavy ions as well as their distinct effects on tissue homeostasis. The use of these radiations in cancer therapy is also discussed. The use of both heavy-ion and proton therapy is on the upswing in several centers around the world, due to their unique energy deposition characteristics that enhance the therapeutic effect and help reduce damage to normal tissue. PMID:9806616

  4. Heavy-ion radiobiology: new approaches to delineate mechanisms underlying enhanced biological effectiveness

    Science.gov (United States)

    Blakely, E. A.; Kronenberg, A.; Chatterjee, A. (Principal Investigator)

    1998-01-01

    Shortly after the discovery of polonium and radium by Marie Curie and her husband and colleague, Pierre Curie, it was learned that exposure to these alpha-particle emitters produced deleterious biological effects. The mechanisms underlying the increased biological effectiveness of densely ionizing radiations, including alpha particles, neutrons and highly energetic heavy charged particles, remain an active area of investigation. In this paper, we review recent advances in several areas of the radiobiology of these densely ionizing radiations, also known as heavy ions. Advances are described in the areas of DNA damage and repair, chromosome aberrations, mutagenesis, neoplastic transformation in vitro, genomic instability, normal tissue radiobiology and carcinogenesis in vivo. We focus on technical innovations, including novel applications of pulsed-field gel electrophoresis, fluorescence in situ hybridization (FISH), linkage analysis, and studies of gene expression and protein expression. We also highlight the use of new cellular and animal systems, including those with defined DNA repair deficiencies, as well as epithelial cell model systems to assess neoplastic transformation both in vitro and in vivo. The studies reviewed herein have had a substantial impact on our understanding of the genotoxic effects of heavy ions as well as their distinct effects on tissue homeostasis. The use of these radiations in cancer therapy is also discussed. The use of both heavy-ion and proton therapy is on the upswing in several centers around the world, due to their unique energy deposition characteristics that enhance the therapeutic effect and help reduce damage to normal tissue.

  5. Effect of alpha-tocopherol and alpha-tocopheryl quinone on the radiosensitivity of thiol-depleted mammalian cells

    International Nuclear Information System (INIS)

    The effect of hypoxic cell radiosensitizers is increased when mammalian cells are depleted of endogenous glutathione by buthionine sulphoximine pre-treatment in vitro; a similar gain has not been observed in tumors in vivo despite evidence of glutathione depletion in vivo following buthionine sulphoximine treatment. However, concentrations of biological reducing agents other than glutathione were not measured in the in vivo experiments. Other reducing agents found in tumors include alpha-tocopherol, which reduces the sensitizing efficiency of nitro-aromatic sensitizers in thiol-depleted mammalian cells. These data suggest that the failure to observe large gains in misonidazole sensitizing efficiency in thiol-depleted tumors in vivo may be due, in part, to the presence of biological reducing agents such as alpha-tocopherol

  6. Effect of alpha-tocopherol and alpha-tocopheryl quinone on the radiosensitivity of thiol-depleted mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Hodgkiss, R.J.; Stratford, M.R.; Watfa, R.R.

    1989-05-01

    The effect of hypoxic cell radiosensitizers is increased when mammalian cells are depleted of endogenous glutathione by buthionine sulphoximine pre-treatment in vitro; a similar gain has not been observed in tumors in vivo despite evidence of glutathione depletion in vivo following buthionine sulphoximine treatment. However, concentrations of biological reducing agents other than glutathione were not measured in the in vivo experiments. Other reducing agents found in tumors include alpha-tocopherol, which reduces the sensitizing efficiency of nitro-aromatic sensitizers in thiol-depleted mammalian cells. These data suggest that the failure to observe large gains in misonidazole sensitizing efficiency in thiol-depleted tumors in vivo may be due, in part, to the presence of biological reducing agents such as alpha-tocopherol.

  7. Biological radiation effects

    International Nuclear Information System (INIS)

    This work examines ionizing radiations: what they are, where they come from, their actions and consequences, finally the norms and preventive measures necessary to avoid serious contamination, whether the individual or the population in general is involved. Man has always been exposed to natural irradiation, but owing to the growing use of ionizing radiations both in medicine and in industry, not to mention nuclear tests and their use as an argument of dissuasion, the irradiation of human beings is increasing daily. Radioactive contamination does remain latent, apart from acute cases, but this is where the danger lies since the consequences may not appear until long after the irradiation. Of all biological effects due to the action of radioelements the genetic risk is one of the most important, affecting the entire population and especially the generations to come. The risk of cancer and leukemia induction plays a substantial part also since a large number of people may be concerned, depending on the mode of contamination involved. All these long-term dangers do not of course exclude the various general or local effects to which the individual alone may be exposed and which sometimes constitute a threat to life. As a result the use of ionizing radiations must be limited and should only be involved if no other process can serve instead. The regulations governing radioelements must be stringent and their application strictly supervised for the better protection of man. This protection must be not only individual but also collective since pollution exists in air, water and land passes to plants and animals and finally reaches the last link in the food chain, man

  8. Study of the stopping power and straggling for alpha particles and protons in organic solids, liquids and gases

    International Nuclear Information System (INIS)

    The stopping power and straggling for 5.5 MeV alpha particles in liquid and vapour phases of water, methanol, ethanol, propanol, h-hexane, n-octane and cyclohexane, and those for low energy protons in ethylene, styrene and propylene and their polymers, have been measured. Range-energy data have been fitted with inverse stopping power functions to give the cross sections. In each case, five parameters have been adjusted to obtain the best fit. The value of chi-squared per degree of freedom has been calculated, together with the parameters. The theoretical stopping cross section has been considered employing the Bethe-Bloch expression together with various corrections (shell correction using Walske and Bichsel procedure, Z13 contribution according to Ashley and Bloch correction based on Lindhard formalism). The existence of a phase effect has been clearly demonstrated for the stopping of both alpha particles and protons. (author)

  9. Differential gene expression in human fibroblasts after alpha-particle emitter (211)At compared with (60)Co irradiation

    DEFF Research Database (Denmark)

    Danielsson, Anna; Claesson, Kristina; Parris, Toshima Z; Helou, Khalil; Nemes, Szilárd; Elmroth, Kecke; Elgqvist, Jörgen; Jensen, Holger; Hultborn, Ragnar

    2013-01-01

    Purpose: The aim of this study was to identify gene expression profiles distinguishing alpha-particle (211)At and (60)Co irradiation. Materials and methods: Gene expression microarray profiling was performed using total RNA from confluent human fibroblasts 5 hours after exposure to (211)At labeled...... trastuzumab monoclonal antibody (0.25, 0.5, and 1 Gy) and (60)Co (1, 2, and 3 Gy). Results: We report gene expression profiles that distinguish the effect different radiation qualities and absorbed doses have on cellular functions in human fibroblasts. In addition, we identified commonly expressed transcripts...... transcription, cell cycle regulation, and cell cycle arrest, whereas mitosis, spindle assembly checkpoint, and apoptotic chromosome condensation were uniquely enriched for alpha particle irradiation. Conclusions: LET-dependent transcriptional modulations were observed in human fibroblasts 5 hours after...

  10. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles. Final performance technical report

    International Nuclear Information System (INIS)

    The goal of this project was to develop theoretical/computational tools for evaluating the risks incurred by populations exposed to radon alpha particles. Topics of concern include the following: compound dual radiation action (general aspects); a mathematical formalism describing the yield of radiation induced single-and double-strand DNA breaks, and its dependence on radiation quality; a study of the excited states in cytosine and guanine stacks in the Hartree-Fock and exciton approximations; nanodosimetry of radon alpha particles; application of the HSEF to assessing radiation risks in the practice of radiation protection; carcinogenic risk coefficients at environmental levels of radon exposures: a microdosimetric approach; and hit-size effectiveness approach in radiation protection

  11. Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles. Final performance technical report

    Energy Technology Data Exchange (ETDEWEB)

    Zaider, M.

    1997-12-31

    The goal of this project was to develop theoretical/computational tools for evaluating the risks incurred by populations exposed to radon alpha particles. Topics of concern include the following: compound dual radiation action (general aspects); a mathematical formalism describing the yield of radiation induced single-and double-strand DNA breaks, and its dependence on radiation quality; a study of the excited states in cytosine and guanine stacks in the Hartree-Fock and exciton approximations; nanodosimetry of radon alpha particles; application of the HSEF to assessing radiation risks in the practice of radiation protection; carcinogenic risk coefficients at environmental levels of radon exposures: a microdosimetric approach; and hit-size effectiveness approach in radiation protection.

  12. Scanning of irradiated silicon detectors using $\\alpha$ particles and low energy protons

    CERN Document Server

    Casse, G L; Glaser, M; Kohout, Z; Konícek, J; Lemeilleur, F; Leroy, C; Linhart, V; Mares, J J; Pospísil, S; Roy, P; Sopko, B; Sinor, M; Svejda, J; Vorobel, V; Wilhelm, I

    1999-01-01

    In a spectroscopic study of non-irradiated and proton-irradiated silicon diodes, the detectors were illuminated from the front side and from the rear side by various alpha particle sources (mainly ThC') and by monoenergetic protons with energies from 1.0 to 2.5~MeV. Their response characteristics have been studied as a function of the incoming particle energy and the applied bias voltage. The charge collection efficiency was determined as a function of fluence

  13. Treatment of HER2-Expressing Breast Cancer and Ovarian Cancer Cells With Alpha Particle-Emitting 227Th-Trastuzumab

    International Nuclear Information System (INIS)

    Purpose: To evaluate the cytotoxic effects of low-dose-rate alpha particle-emitting radioimmunoconjugate 227Th-p-isothiocyanato-benzyl-DOTA-trastuzumab (227Th-trastuzumab [where DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]) internalized by breast and ovarian cancer cell lines in order to assess the potential of 227Th-trastuzumab as a therapeutic agent against metastatic cancers that overexpress the HER2 oncogene. Methods and Materials: Clonogenic survival and cell growth rates of breast cancer cells treated with 227Th-trastuzumab were compared with rates of cells treated with nonbinding 227Th-rituximab, cold trastuzumab, and X-radiation. Cell growth experiments were also performed with ovarian cancer cells. Cell-associated radioactivity was measured at several time points, and the mean radiation dose to cells was calculated. Results: SKBR-3 cells got 50% of the mean absorbed radiation dose from internalized activity and 50% from cell surface-bound activity, while BT-474 and SKOV-3 cells got 75% radiation dose from internalized activity and 25% from cell surface-bound activity. Incubation of breast cancer cells with 2.5 kBq/ml 227Th-trastuzumab for 1 h at 4oC, followed by washing, resulted in mean absorbed radiation doses of 2 to 2.5 Gy. A dose-dependent inhibition of cell growth and an increase in apoptosis were induced in all cell lines. Conclusions: Clinically relevant activity concentrations of 227Th-trastuzumab induced a specific cytotoxic effect in three HER2-expressing cell lines. The cytotoxic effect of 227Th-trastuzumab was higher than that of single-dose X-radiation (relative biological effectiveness = 1.2). These results warrant further studies of treatment of breast cancer and ovarian cancer with 227Th-trastuzumab.

  14. Alpha particle density and energy distributions in tandem mirrors using Monte-Carlo techniques

    International Nuclear Information System (INIS)

    We have simulated the alpha thermalization process using a Monte-Carlo technique, in which the alpha guiding center is followed between simulated collisions and Spitzer's collision model is used for the alpha-plasma interaction. Monte-Carlo techniques are used to determine the alpha radial birth position, the alpha particle position at a collision, and the angle scatter and dispersion at a collision. The plasma is modeled as a hot reacting core, surrounded by a cold halo plasma (T approx.50 eV). Alpha orbits that intersect the halo lose 90% of their energy to the halo electrons because of the halo drag, which is ten times greater than the drag in the core. The uneven drag across the alpha orbit also produces an outward, radial, guiding center drift. This drag drift is dependent on the plasma density and temperature radial profiles. We have modeled these profiles and have specifically studied a single-scale-length model, in which the density scale length (r/sub pD/) equals the temperature scale length (r/sub pT/), and a two-scale-length model, in which r/sub pD//r/sub pT/ = 1.1

  15. Biological effectiveness of antiproton annihilation

    DEFF Research Database (Denmark)

    Holzscheiter, M.H.; Agazaryan, N.; Bassler, Niels;

    2004-01-01

    We describe an experiment designed to determine whether or not the densely ionizing particles emanating from the annihilation of antiprotons produce an increase in ‘‘biological dose’’ in the vicinity of the narrow Bragg peak for antiprotons compared to protons. This experiment is the first direct...

  16. Alpha-particle emission from contaminants in counter materials

    International Nuclear Information System (INIS)

    Energy spectra of surface activities from thorium and uranium contaminants have been investigated for typical counter materials. Soft-tempered stainless steel with a rate of 1.2±0.1 α-particles emitted per 100 cm2 in one hour was found better than other stainless steel and far better than brass and aluminum. Energy spectra provide information about the contaminating activity and about its depth profile. Thorium, uranium and 210Pb contamination was also observed for thin sources of other materials including isotopically enriched materials. (orig.)

  17. Preequilibrium decay in alpha particle induced reactions in terbium

    International Nuclear Information System (INIS)

    The excitation functions of 159 Tb(α,n), (α,3 n), (α,4 n), (α,α3 n) reactions were measured using stacked foil activation technique and HPGe gamma ray spectroscopy method up to 50 MeV. The experimental results were compared with the theoretical predictions considering equilibrium as well as preequilibrium contributions using code ALICE/90. It was found that the initial exciton configuration n0 = 4(4p0h) that is pure particle state, appears to give good fit to the experimental data. (Authors)

  18. Production of $\\alpha$-particle condensate states in heavy-ion collisions

    CERN Document Server

    Raduta, Ad R; Geraci, E; Neindre, N Le; Napolitani, P; Rivet, M F; Alba, R; Amorini, F; Cardella, G; Chatterjee, M; De Filippo, E; Guinet, D; Lautesse, P; La Guidara, E; Lanzalone, G; Lanzano, G; Lombardo, I; Lopez, O; Maiolino, C; Pagano, A; Pirrone, S; Politi, G; Porto, F; Rizzo, F; Russotto, P; Wieleczko, J P

    2010-01-01

    The fragmentation of quasi-projectiles from the nuclear reaction $^{40}Ca$ + $^{12}C$ at 25 MeV/nucleon was used to produce excited states candidates to $\\alpha$-particle condensation. The experiment was performed at LNS-Catania using the CHIMERA multidetector. Accepting the emission simultaneity and equality among the $\\alpha$-particle kinetic energies as experimental criteria for deciding in favor of the condensate nature of an excited state, we analyze the $0_2^+$ and $2_2^+$ states of $^{12}$C and the $0_6^+$ state of $^{16}$O. A sub-class of events corresponding to the direct 3-$\\alpha$ decay of the Hoyle state is isolated.

  19. Collisionless Evolution of Isotropic Alpha-Particle Distribution in a Tokamak

    International Nuclear Information System (INIS)

    Full text: The density of the noninductive current generated due to collisionless motion of alpha-particles in the tokamak magnetic field is calculated. The analysis is based on fully three-dimensional calculations of charged particle trajectories without simplifying assumptions typical for drift and neoclassical approaches. The current is calculated over the entire cross section of the plasma column, including the magnetic axis. It is shown that the current density is not a function of a magnetic surface and is strongly polarized over the poloidal angle. The current density distribution in the tokamak poloidal cross section is obtained, and the current density as a function of the safety factor profile, the tokamak aspect ratio, and the ratio of the particle Larmor radius on the axis to the tokamak minor radius is determined. It is shown that, when the source of alpha-particles is spatially nonuniform, the current density in the center of the tokamak is nonzero due to asymmetry of the phase-space boundary between trapped and passing particles. The current density scaling in the tokamak center differs from the known approximations for the bootstrap current and is sensitive to the spatial distribution of alpha-particles. (author)

  20. A variational calculation of 12C in the alpha-particle model

    International Nuclear Information System (INIS)

    Some physical properties of three structureless alpha particles interacting through two-body potentials were discussed. Comparison between them and the corresponding experimental observations for the 12C nucleus is done. The wave function is expanded in terms of translationally invariant harmonic-oscillator states, the coefficients being variational parameters

  1. alpha-particle radioactivity from LR 115 by two methods of analysis

    CERN Document Server

    Azkour, K; Adloff, J C; Pape, A

    1999-01-01

    LR115 track detectors were exposed to samples of Moroccan phosphate and phosphogypsum to measure their alpha-particle radioactivity. Then two formalisms were used for the dosimetry: simulation by a Monte Carlo method and determination of concentrations from a numerically integrated track registration equation. The results were compared with those deduced gamma-ray spectrometry.

  2. Alpha and beta particle induced scintillations in liquid and solid neon

    CERN Document Server

    Michniak, R A; McKinsey, D N; Doyle, J M

    2002-01-01

    Scintillations induced by alpha and beta particles in liquid and solid neon are studied and their light yield measured. Charged particle scintillation in neon is primarily in the extreme ultraviolet (EUV). We detect this EUV light by converting it to blue using a wavelength shifting fluor and detecting the blue light with a photomultiplier tube. It is observed that liquid neon is a somewhat less-efficient scintillator than liquid helium for both alpha and beta radiation while the light yield in solid neon is greater than in liquid helium. Based on our measurements of the relative light yields of liquid and solid neon to liquid helium whose absolute light yield has previously been determined, we find that an alpha source in liquid neon produces up to 5900 photons per MeV while a beta source produces up to 7400 photons per MeV. In solid neon, we find that an alpha particle produces up to 9300 photons per MeV while a beta particle produces up to 17,000 photons per MeV. We observe a significant dependence of the ...

  3. RADON AND PROGENY ALPHA-PARTICLE ENERGY ANALYSIS USING NUCLEAR TRACK METHODOLOGY

    International Nuclear Information System (INIS)

    A preliminary procedure for alpha energy analysis of radon and progeny using Nuclear Track Methodology (NTM) is described in this paper. The method is based on the relationship between alpha-particle energies deposited in polycarbonate material (CR-39) and the track size developed after a well-established chemical etching process. Track geometry, defined by parameters such as major or minor diameters, track area and overall track length, is shown to correlate with alpha-particle energy over the range 6.00 MeV (218Po) to 7.69 MeV (214Po). Track features are measured and the data analyzed automatically using a digital imaging system and commercial PC software. Examination of particle track diameters in CR-39 exposed to environmental radon reveals a multi-modal distribution. Locations of the maxima in this distribution are highly correlated with alpha particle energies of radon daughters, and the distributions are sufficiently resolved to identify the radioisotopes. This method can be useful for estimating the radiation dose from indoor exposure to radon and its progeny.

  4. Cross section balance in the 14N+159Tb reaction and the origin of fast alpha particles

    International Nuclear Information System (INIS)

    Exclusive cross sections have been obtained from particle-K X-ray coincidence data measured at 236 MeV for ejectiles ranging from 4He to 15N. Production cross sections for primary fragments and alpha particle multiplicities associated with different channels have been deduced. The major fraction of the alpha particles appears to originate from inelastic (damped) processes in which only light particles with Z<=2 are emitted. (orig.)

  5. Fluctuating Nonlinear Spring Model of Mechanical Deformation of Biological Particles

    CERN Document Server

    Kononova, Olga; Marx, Kenneth A; Wuite, Gijs J L; Roos, Wouter H; Barsegov, Valeri

    2015-01-01

    We present a new theory for modeling forced indentation spectral lineshapes of biological particles, which considers non-linear Hertzian deformation due to an indenter-particle physical contact and bending deformations of curved beams modeling the particle structure. The bending of beams beyond the critical point triggers the particle dynamic transition to the collapsed state, an extreme event leading to the catastrophic force drop as observed in the force (F)-deformation (X) spectra. The theory interprets fine features of the spectra: the slope of the FX curves and the position of force-peak signal, in terms of mechanical characteristics --- the Young's moduli for Hertzian and bending deformations E_H and E_b, and the probability distribution of the maximum strength with the strength of the strongest beam F_b^* and the beams' failure rate m. The theory is applied to successfully characterize the $FX$ curves for spherical virus particles --- CCMV, TrV, and AdV.

  6. Production and consumption of biological particles in temperate tidal estuaries

    NARCIS (Netherlands)

    Heip, C.H.R.; Goosen, N.K.; Herman, P.M.J.; Kromkamp, J.C.; Middelburg, J.J.; Soetaert, K.E.R.

    1995-01-01

    The question is reviewed whether a balance exists between production and consumption of biological particles in temperate tidal estuaries and what the relationships are between the magnitude of production and consumption processes and system carbon metabolism. The production terms considered are pri

  7. Neutron activation analysis of several elements in the unicellular alga Cyanidium caldarium irradiated by. cap alpha. particles from neutron captured boron

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Shuho; Oota, Tadachika; Otani, Mayumi; Aso, Sueo (Tokyo Univ. of Agriculture (Japan))

    1984-02-01

    The TRIGA MARK 2 atomic reactor was used not only for instrumental neutron activation analysis (INAA) but also as the irradiation source of ..cap alpha.. particles derived from the /sup 10/B(n, ..cap alpha..)/sup 7/Li reaction for biological samples. The acidophilic and thermophilic unicellular alga (Cyanidium caldarium Geitler) was incubated for 20 hours after irradiation and then its elemental concentrations were analysed by INAA. An increase in the quantities of /sup 56/Mn, /sup 28/Al and /sup 38/Cl, and a decrease of /sup 27/Mg and /sup 42/K were detected in the irradiated cells in contrast to non-irradiated cells.

  8. Lung cancer risk from exposure to alpha particles and inhalation of other pollutants in rats

    Energy Technology Data Exchange (ETDEWEB)

    Burns, F.J.

    1990-01-01

    The goal of these experiments is to establish a quantitative correlation between early DNA damage and cancer incidence in a way that would be helpful for assessing the carcinogenic risk of radon alone or in combination with specific indoor pollutants. Rat tracheal epithelium has been exposed in vivo to {sup 210}Po alpha particles in the presence and absence of NO{sub 2} or cigarette smoke. The major accomplishments so far are: the design and implementation of a tracheal implant to simulate radon alpha particle exposure, the measurement of DNA breaks in a small 7.0 mm segment of the trachea exposed to external x-irradiation, the measurement of the rate of repair of the x-ray induced tracheal DNA strand breaks, the measurement of DNA strand breaks following inhalation of cigarette smoke or NO{sub 2}, the measurement of tracheal DNA stand breaks following exposure to high doses {sup 210}Po alpha particle radiation, the assessment of the amount of mucous in the goblet cells and in the underlying mucous glands. So far we have been unable to detect DNA strand breaks in the tracheal epithelium as a result of exposure to NO{sub 2} cigarette smoke or {sup 210}Po alpha particles. We have developed a simple artificial' trachea consisting of rat tracheal epithelial cells growing on a basement membrane coated millipore filter. Experiments are proposed to utilize these artificial tracheas to eliminate the potential interference of increased mucous secretion and/or inflammation that can significantly affect the radiation dose from the alpha particles. 61 refs., 17 figs.

  9. Dependence of alpha particle track diameter on the free volume holes size using positron annihilation lifetime technique

    Energy Technology Data Exchange (ETDEWEB)

    El-Gamal, S. [Physics Department, Faculty of Education, Ain Shams University, Roxy, 11711 Cairo (Egypt); Abdalla, Ayman M., E-mail: aymanabdalla62@hotmail.com [Physics Department, Faculty of Arts and Sciences, Najran University, Najran (Saudi Arabia); Centre for Advanced Materials and Nano-Engineering, Najran University, Najran 11001 (Saudi Arabia); Abdel-Hady, E.E. [Physics Department, Faculty of Science, Minia University, BO 61519, Minia (Egypt)

    2015-09-15

    The alpha particle track diameter dependence of the free volume holes size (V{sub f}) in DAM–ADC and CR-39 nuclear track detectors was investigated using positron annihilation lifetime technique. The effect of temperature on the alpha particle track diameter and free volume were also investigated in the T-range (RT-130 °C). The obtained results revealed that the values of ortho-positronium lifetime τ{sub 3} and V{sub f} increases while I{sub 3} slightly increases as T increases for the two detectors. The values of τ{sub 3}, V{sub f} and I{sub 3} are higher in CR-39 than DAM–ADC. The interpretation of obtained results is based on the fact that increasing T leads to significant enhancement of thermal expansion of the polymer matrix and consequently V{sub f} increases. The track diameter increases as T increases. This can be explained by the fact that the increase in T increases the crystal size and V{sub f} in the polymer. A relationship between V{sub f} and the alpha particle track diameter was obtained. Moreover results of detector irradiation, along with free volume evaluation are addressed and thoroughly discussed.

  10. Dependence of alpha particle track diameter on the free volume holes size using positron annihilation lifetime technique

    International Nuclear Information System (INIS)

    The alpha particle track diameter dependence of the free volume holes size (Vf) in DAM–ADC and CR-39 nuclear track detectors was investigated using positron annihilation lifetime technique. The effect of temperature on the alpha particle track diameter and free volume were also investigated in the T-range (RT-130 °C). The obtained results revealed that the values of ortho-positronium lifetime τ3 and Vf increases while I3 slightly increases as T increases for the two detectors. The values of τ3, Vf and I3 are higher in CR-39 than DAM–ADC. The interpretation of obtained results is based on the fact that increasing T leads to significant enhancement of thermal expansion of the polymer matrix and consequently Vf increases. The track diameter increases as T increases. This can be explained by the fact that the increase in T increases the crystal size and Vf in the polymer. A relationship between Vf and the alpha particle track diameter was obtained. Moreover results of detector irradiation, along with free volume evaluation are addressed and thoroughly discussed

  11. Alfvenic behavior of alpha particle driven ion cyclotron emission in TFTR

    International Nuclear Information System (INIS)

    Ion cyclotron emission (ICE) has been observed during D-T discharges in the Tokamak Fusion Test Reactor (TFTR), using rf probes located near the top and bottom of the vacuum vessel. Harmonics of the alpha cyclotron frequency (Ωα) evaluated at the outer midplane plasma edge are observed at the onset of the beam injection phase of TFTR supershots, and persist for approximately 100-250 ms. These results are in contrast with observations of ICE in JET, in which harmonics of Ωα evolve with the alpha population in the plasma edge. Such differences are believed to be due to the fact that newly-born fusion alpha particles are super-Alfvenic near the edge of JET plasmas, while they are sub-Alfvenic near the edge of TFTR supershot plasmas. In TFTR discharges with edge densities such that newly-born alpha particles are super-Alfvenic, alpha cyclotron harmonics are observed to persist. These results are in qualitative agreement with numerical calculations of growth rates due to the magnetoacoustic cyclotron instability

  12. Effect of Pilates Training on Alpha Rhythm

    Directory of Open Access Journals (Sweden)

    Zhijie Bian

    2013-01-01

    Full Text Available In this study, the effect of Pilates training on the brain function was investigated through five case studies. Alpha rhythm changes during the Pilates training over the different regions and the whole brain were mainly analyzed, including power spectral density and global synchronization index (GSI. It was found that the neural network of the brain was more active, and the synchronization strength reduced in the frontal and temporal regions due to the Pilates training. These results supported that the Pilates training is very beneficial for improving brain function or intelligence. These findings maybe give us some line evidence to suggest that the Pilates training is very helpful for the intervention of brain degenerative diseases and cogitative dysfunction rehabilitation.

  13. Quantum Effects in Biological Systems

    CERN Document Server

    2016-01-01

    Since the last decade the study of quantum mechanical phenomena in biological systems has become a vibrant field of research. Initially sparked by evidence of quantum effects in energy transport that is instrumental for photosynthesis, quantum biology asks the question of how methods and models from quantum theory can help us to understand fundamental mechanisms in living organisms. This approach entails a paradigm change challenging the related disciplines: The successful framework of quantum theory is taken out of its low-temperature, microscopic regimes and applied to hot and dense macroscopic environments, thereby extending the toolbox of biology and biochemistry at the same time. The Quantum Effects in Biological Systems conference is a platform for researchers from biology, chemistry and physics to present and discuss the latest developments in the field of quantum biology. After meetings in Lisbon (2009), Harvard (2010), Ulm (2011), Berkeley (2012), Vienna (2013), Singapore (2014) and Florence (2015),...

  14. A Further Measurement of the beta-Delayed alpha-Particle Emission of 16N

    CERN Document Server

    III, R H F; McDonald, J E; Wilds, E L

    2007-01-01

    We measured the beta-delayed alpha-particle emission spectrum of 16N with a sensitivity for beta-decay branching ratios of the order of 10-10. The 16N nuclei were produced using the d(15N,16N)p reaction with 70 MeV 15N beams and a deuterium gas target 7.5 cm long at a pressure of 1250 torr. The 16N nuclei were collected (over 10 s) using a thin aluminum foil with an areal density of 180 mu g/cm2 tilted at 7 Deg with respect to the beam. The activity was transferred to the counting area by means of a stepping motor in less than 3 s with the counting carried out over 8 s. The beta-delayed alpha-particles were measured using a time of flight method to achieve a sufficiently low background. Standard calibration sources (148Gd, 241Am, 208,209Po, and 227Ac) as well as alpha-particles and 7Li from the 10B(n,alpha)7Li reaction were used for an accurate energy calibration. The energy resolution of the catcher foil (180-220 keV) was calculated and the time of flight resolution (3-10 nsec) was measured using the beta-de...

  15. Track Reconstruction and Performance of DRIFT Directional Dark Matter Detectors using Alpha Particles

    CERN Document Server

    Burgos, S; Ghag, C; Gold, M; Kudryavtsev, V A; Lawson, T B; Loomba, D; Majewski, P; McMillan, J E; Muna, D; Murphy, A StJ; Nicklin, G G; Paling, S M; Petkov, A; Plank, S J S; Robinson, M; Sanghi, N; Smith, N J T; Snowden-Ifft, D P; Spooner, N J C; Sumner, T J; Turk, J; Tziaferi, T

    2007-01-01

    First results are presented from an analysis of data from the DRIFT-IIa and DRIFT-IIb directional dark matter detectors at Boulby Mine in which alpha particle tracks were reconstructed and used to characterise detector performance--an important step towards optimising directional technology. The drift velocity in DRIFT-IIa was [59.3 +/- 0.2 (stat) +/- 7.5 (sys)] m/s based on an analysis of naturally-occurring alpha-emitting background. The drift velocity in DRIFT-IIb was [57 +/- 1 (stat) +/- 3 (sys)] m/s determined by the analysis of alpha particle tracks from a Po-210 source. 3D range reconstruction and energy spectra were used to identify alpha particles from the decay of Rn-222, Po-218, Rn-220 and Po-216. This study found that (22 +/- 2)% of Po-218 progeny (from Rn-222 decay) are produced with no net charge in 40 Torr CS2. For Po-216 progeny (from Rn-220 decay) the uncharged fraction is (100 +0 -35)%.

  16. Registration of alpha particles in Makrofol-E nuclear track detectors

    Science.gov (United States)

    Rammah, Y. S.; Abdalla, Ayman M.; Ashraf, O.; Ashry, A. H.

    2016-06-01

    Fast detection of alpha particles in the range from 1 to 5 MeV in Makrofol-E polycarbonate nuclear track detectors (PCTDs) using a new chemical etchant was investigated. 252Cf and 241Am-thin open sources were used for irradiating Makrofol-E detectors with fission fragments and alpha particles in air at normal pressure and temperature (NPT). A chain of experimental work has been carried out using new etchants to register alpha particle in short time in Makrofol-E polycarbonate detectors. The etching efficiency were exhibited a clear dependence on the amount of methanol in the etching solution and etching time. The optimized chemical condition obtained at this stage of development for 200 μm Makrofol-E detectors are (8 ml of 10 N NaOH + 2 ml CH3OH) etching solutions at 60 °C for 3 h. In this study; it is possible to observe energy detection windows for Makrofol-E detectors according to applied etching duration. Makrofol-E introduced the characteristic Bragg peak, which indicates the advantages of this detector as alpha spectrometer. Consequently, the suggested new etchant can be developed for heavy ions detection and monitoring radon levels and its daughters.

  17. A new alpha particle diagnostic using knock-on ion tails

    International Nuclear Information System (INIS)

    We propose a new method of measuring the fast confined ct-particle distribution in a reacting plasma. The presence of ct-particles in a D-T plasma will create a high energy tail on the deuterium and tritium ion energy distributions. A 3.5 MeV alpha can transfer 3.4 MeV to a tritium ion in a single elastic scattering interaction. Calculations of the size of these knock-on tails in tokamaks such as TFTR, JET, and ITER show that it may be possible to measure these tails and provide information on the fast confined alphas. The knock-on tail ions will produce D-T neutrons with energies up to 20.7 MeV, so that D-T neutron spectroscopy can be used to monitor the alpha population. Neutron spectroscopy looks especially attractive for ITER. A collimated array of threshold neutron activation detectors could be used to deduce the confined alpha density profile. Tests of this diagnostic can also be done on TFTR and JET. Existing high energy neutral particle analyzers may allow observation of the ion tails directly via passive and/or active charge exchange

  18. Humidity influenced capacitance and resistance of an Al/DNA/Al Schottky diode irradiated by alpha particles

    Science.gov (United States)

    Al-Ta’Ii, Hassan Maktuff Jaber; Amin, Yusoff Mohd; Periasamy, Vengadesh

    2016-05-01

    Deoxyribonucleic acid or DNA based sensors, especially as humidity and alpha particle sensors have become quite popular in recent times due to flexible and highly optimizable nature of this fundamental biomaterial. Application of DNA electronics allow for more sensitive, accurate and effective sensors to be developed and fabricated. In this work, we examined the effect of different humidity conditions on the capacitive and resistive response of Aluminum (Al)/DNA/Al Schottky barrier structure when bombarded by time-dependent dosages of alpha particles. Based on current-voltage profiles, which demonstrated rectifying behaviours, Schottky diode parameters such as ideality factor, barrier height and series resistance was calculated. Results observed generally pointed towards a decrease in the resistance value from the pristine to the radiated structures. It was also demonstrated that under the effect of humidity, the capacitance of the DNA thin film increased from 0.05894 to 92.736 nF, with rising relative humidity level. We also observed the occurrence of the hypersensitivity phenomena after alpha irradiation between 2 to 4 min by observing a drop in the series resistance, crucial in the study of DNA damage and repair mechanisms. These observations may also suggest the exciting possibility of utilizing Al/DNA/Al Schottky diodes as potentially sensitive humidity sensors.

  19. Order (alpha^2 Gamma, alpha^3 Gamma) Binding Effects in Orthopositronium Decay

    OpenAIRE

    Hill, Richard J.; Lepage, G. Peter

    2000-01-01

    We present a new, simplified analysis of the low-energy electron-positron interaction, and use the resulting effective theory to calculate the binding effects that contribute to the decay rate, Gamma, of orthopositronium, through Order(alpha^3 ln(alpha) Gamma). We express the total decay rate in terms of the annihilation rate for a free electron and positron at threshold, which has just recently been computed to sufficient precision. Our result corrects errors in a previous analysis.

  20. Dissipative particle dynamics simulations for biological tissues: rheology and competition

    International Nuclear Information System (INIS)

    In this work, we model biological tissues using a simple, mechanistic simulation based on dissipative particle dynamics. We investigate the continuum behavior of the simulated tissue and determine its dependence on the properties of the individual cell. Cells in our simulation adhere to each other, expand in volume, divide after reaching a specific size checkpoint and undergo apoptosis at a constant rate, leading to a steady-state homeostatic pressure in the tissue. We measure the dependence of the homeostatic state on the microscopic parameters of our model and show that homeostatic pressure, rather than the unconfined rate of cell division, determines the outcome of tissue competitions. Simulated cell aggregates are cohesive and round up due to the effect of tissue surface tension, which we measure for different tissues. Furthermore, mixtures of different cells unmix according to their adhesive properties. Using a variety of shear and creep simulations, we study tissue rheology by measuring yield stresses, shear viscosities, complex viscosities as well as the loss tangents as a function of model parameters. We find that cell division and apoptosis lead to a vanishing yield stress and fluid-like tissues. The effects of different adhesion strengths and levels of noise on the rheology of the tissue are also measured. In addition, we find that the level of cell division and apoptosis drives the diffusion of cells in the tissue. Finally, we present a method for measuring the compressibility of the tissue and its response to external stress via cell division and apoptosis

  1. Alpha-emitting radioisotopes production for radioimmunotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Kwon Soo [Korea Institutet of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2007-02-15

    This review discusses the production of alpha-particle-emitting radionuclides in radioimmunotherapy. Radioimmunotherapy labeled with alpha-particle is expected to be very useful for the treatment of monocellular cancer (e.g. leukemia) and micrometastasis at an early stage, residual tumor remained in tissues after chemotherapy and tumor resection, due to the high linear energy transfer (LET) and the short path length in biological tissue of alpha particle. Despite of the expected effectiveness of alpha-particle in radioimmunotherapy, its clinical research has not been activated by the several reasons, shortage of a suitable a-particle development and a reliable radionuclide production and supply system, appropriate antibody and chelator development. Among them, the establishment of radionuclide development and supply system is a key factor to make an alpha-immunotherapy more popular in clinical trial. Alpha-emitter can be produced by several methods, natural radionuclides, reactor irradiation, cyclotron irradiation, generator system and elution. Due to the sharply increasing demand of {sup 213}Bi, which is a most promising radionuclide in radioimmunotherapy and now has been produced with reactor, the cyclotron production system should be developed urgently to meet the demand.

  2. DNA double strand breaks as predictor of efficacy of the alpha-particle emitter Ac-225 and the electron emitter Lu-177 for somatostatin receptor targeted radiotherapy.

    Directory of Open Access Journals (Sweden)

    Franziska Graf

    Full Text Available RATIONALE: Key biologic effects of the alpha-particle emitter Actinium-225 in comparison to the beta-particle emitter Lutetium-177 labeled somatostatin-analogue DOTATOC in vitro and in vivo were studied to evaluate the significance of γH2AX-foci formation. METHODS: To determine the relative biological effectiveness (RBE between the two isotopes (as - biological consequence of different ionisation-densities along a particle-track, somatostatin expressing AR42J cells were incubated with Ac-225-DOTATOC and Lu-177-DOTATOC up to 48 h and viability was analyzed using the MTT assay. DNA double strand breaks (DSB were quantified by immunofluorescence staining of γH2AX-foci. Cell cycle was analyzed by flow cytometry. In vivo uptake of both radiolabeled somatostatin-analogues into subcutaneously growing AR42J tumors and the number of cells displaying γH2AX-foci were measured. Therapeutic efficacy was assayed by monitoring tumor growth after treatment with activities estimated from in vitro cytotoxicity. RESULTS: Ac-225-DOTATOC resulted in ED50 values of 14 kBq/ml after 48 h, whereas Lu-177-DOTATOC displayed ED50 values of 10 MBq/ml. The number of DSB grew with increasing concentration of Ac-225-DOTATOC and similarly with Lu-177-DOTATOC when applying a factor of 700-fold higher activity compared to Ac-225. Already 24 h after incubation with 2.5-10 kBq/ml, Ac-225-DOTATOC cell-cycle studies showed up to a 60% increase in the percentage of tumor cells in G2/M phase. After 72 h an apoptotic subG1 peak was also detectable. Tumor uptake for both radio peptides at 48 h was identical (7.5%ID/g, though the overall number of cells with γH2AX-foci was higher in tumors treated with 48 kBq Ac-225-DOTATOC compared to tumors treated with 30 MBq Lu-177-DOTATOC (35% vs. 21%. Tumors with a volume of 0.34 ml reached delayed exponential tumor growth after 25 days (44 kBq Ac-225-DOTATOC and after 21 days (34 MBq Lu-177-DOTATOC. CONCLUSION: γH2AX-foci formation, triggered

  3. Dynamical Screening Effect on $\\alpha$-$\\alpha$ Resonant Scattering and Thermal Nuclear Scattering Rate

    CERN Document Server

    Yao, Xiaojun; Müller, Berndt

    2016-01-01

    We study the dynamical screening effect in the QED plasma on the $\\alpha$-$\\alpha$ scattering at the $^8$Be resonance. Dynamical screening leads to an imaginary part of the potential which results in a thermal width for the resonance and dominates over the previously considered static screening effect. As a result, both the resonance energy and width increase with the plasma temperature. Furthermore, dynamical screening can have a huge impact on the $\\alpha$-$\\alpha$ thermal nuclear scattering rate. For example, when the temperature is around $10$ keV, the rate is suppressed by a factor of about $900$. We expect similar thermal suppressions of nuclear reaction rates to occur in nuclear reactions dominated by an above threshold resonance with a thermal energy. Dynamical screening effects on nuclear reactions can be relevant to cosmology and astrophysics.

  4. Alfven Eigenmode And Ion Bernstein Wave Studies For Controlling Fusion Alpha Particles

    CERN Document Server

    Heeter, R F

    1999-01-01

    In magnetic confinement fusion reactor plasmas, the charged fusion products (such as alpha particles in deuterium-tritium plasmas) will be the dominant power source, and by controlling these charged fusion products using wave-particle interactions the reactor performance could be optimized. This thesis studies two candidate waves: Mode-Converted Ion Bernstein Waves (MCIBWs) and Alfvén Eigenmodes (AEs). Rates of MCIBW-driven losses of alpha-like fast deuterons, previously observed in the Tokamak Fusion Test Reactor (TFTR), are reproduced by a new model so that the wave-particle diffusion coefficient can be deduced. The MCIBW power in TFTR is found to be ∼ 1/3 that needed for collisionless alpha particle control. A reasonable reactor power scaling is derived. To study AEs, existing magnetic fluctuation probes at the Joint European Torus (JET) have been absolutely calibrated from 30–500 kHz for the first time, allowing fluctuation measurements with &vbm0;dBpol&vbm0;/B0&am...

  5. Photoluminescence detection of alpha particle using DAM-ADC nuclear detector

    Science.gov (United States)

    Abdalla, Ayman M.; Harraz, Farid A.; Ali, Atif M.; Al-Sayari, S. A.; Al-Hajry, A.

    2016-09-01

    The photoluminescence (PL) and UV-vis spectral analysis of DAM-ADC (diallyl maleate: DAM, polyallyl diglycol carbonate: ADC) nuclear detector are demonstrated for the first time. The DAM-ADC surfaces were exposed to thin 241Am disk source that emits alpha particles with activity 333 kBq. It is found that the track density of the irradiated samples remarkably influences the PL characteristics of the DAM-ADC detector. The spectral peak heights and the integrated intensities under the peaks exhibit linear correlations with correlation coefficient R2=0.9636 and 0.9806, respectively for different alpha particle fluences ranging from 8.16-40.82×107 particles/cm2. Additionally, a correlation coefficient R2=0.9734 was achieved for the UV-vis spectral analysis. The linear fitting functions, along with the corresponding fitting parameters were evaluated in each case. Both the PL and the UV-vis data of the irradiated DAM-ADC samples showed considerable spectral differences, and hence they would be used to offer sensitive approaches for alpha particle detection.

  6. Alpha particle response study of polycrstalline diamond radiation detector

    Science.gov (United States)

    Kumar, Amit; Topkar, Anita

    2016-05-01

    Chemical vapor deposition has opened the possibility to grow high purity synthetic diamond at relatively low cost. This has opened up uses of diamond based detectors for wide range of applications. These detectors are most suitable for harsh environments where standard semiconductor detectors cannot work. In this paper, we present the fabrication details and performance study of polycrystalline diamond based radiation detector. Effect of different operating parameters such as bias voltage and shaping time for charge collection on the performance of detector has been studied.

  7. Optimizing the Delivery of Short-Lived Alpha Particle-Emitting Isotopes to Solid Tumors

    International Nuclear Information System (INIS)

    The underlying hypothesis of this project was that optimal alpha emitter-based radioimmunotherapy (RAIT) could be achieved by pairing the physical half-life of the radioisotope to the biological half-life of the targeting vehicle. The project had two specific aims. The first aim was to create and optimize the therapeutic efficacy of 211At-SAPS-C6.5 diabody conjugates. The second aim was to develop bispecific-targeting strategies that increase the specificity and efficacy of alpha-emitter-based RAIT. In the performance of the first aim, we created 211At-SAPS-C6.5 diabody conjugates that specifically targeted the HER2 tumor associated antigen. In evaluating these immunoconjugates we determined that they were capable of efficient tumor targeting and therapeutic efficacy of established human tumor xenografts growing in immunodeficient mice. We also determined that therapeutic doses were associated with late renal toxicity, likely due to the role of the kidneys in the systemic elimination o f these agents. We are currently performing more studies focused on better understanding the observed toxicity. In the second aim, we successfully generated bispecific single-chain Fv (bs-scFv) molecules that co-targeted HER2 and HER3 or HER2 and HER4. The in vitro kinetics and in vivo tumor-targeting properties of these molecules were evaluated. These studies revealed that the bs-scFv molecules selectively localized in vitro on tumor cells that expressed both antigens and were capable of effective tumor localization in in vivo studies

  8. Optimizing the Delivery of Short-Lived Alpha Particle-Emitting Isotopes to Solid Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Gregory P.

    2004-11-24

    The underlying hypothesis of this project was that optimal alpha emitter-based radioimmunotherapy (RAIT) could be achieved by pairing the physical half-life of the radioisotope to the biological half-life of the targeting vehicle. The project had two specific aims. The first aim was to create and optimize the therapeutic efficacy of 211At-SAPS-C6.5 diabody conjugates. The second aim was to develop bispecific-targeting strategies that increase the specificity and efficacy of alpha-emitter-based RAIT. In the performance of the first aim, we created 211At-SAPS-C6.5 diabody conjugates that specifically targeted the HER2 tumor associated antigen. In evaluating these immunoconjugates we determined that they were capable of efficient tumor targeting and therapeutic efficacy of established human tumor xenografts growing in immunodeficient mice. We also determined that therapeutic doses were associated with late renal toxicity, likely due to the role of the kidneys in the systemic elimination o f these agents. We are currently performing more studies focused on better understanding the observed toxicity. In the second aim, we successfully generated bispecific single-chain Fv (bs-scFv) molecules that co-targeted HER2 and HER3 or HER2 and HER4. The in vitro kinetics and in vivo tumor-targeting properties of these molecules were evaluated. These studies revealed that the bs-scFv molecules selectively localized in vitro on tumor cells that expressed both antigens and were capable of effective tumor localization in in vivo studies.

  9. Factors affecting the energy resolution in alpha particle spectrometry with silicon diodes

    International Nuclear Information System (INIS)

    In this work are presented the studies about the response of a multi-structure guard rings silicon diode for detection and spectrometry of alpha particles. This ion-implanted diode (Al/p+/n/n+/Al) was processed out of 300 μm thick, n type substrate with a resistivity of 3 kΩ·cm and an active area of 4 mm2. In order to use this diode as a detector, the bias voltage was applied on the n+ side, the first guard ring was grounded and the electrical signals were readout from the p+ side. These signals were directly sent to a tailor made preamplifier, based on the hybrid circuit A250 (Amptek), followed by a conventional nuclear electronic. The results obtained with this system for the direct detection of alpha particles from 241Am showed an excellent response stability with a high detection efficiency (≅ 100 %). The performance of this diode for alpha particle spectrometry was studied and it was prioritized the influence of the polarization voltage, the electronic noise, the temperature and the source-diode distance on the energy resolution. The results showed that the major contribution for the deterioration of this parameter is due to the diode dead layer thickness (1 μm). However, even at room temperature, the energy resolution (FWHM = 18.8 keV) measured for the 5485.6 MeV alpha particles (241Am) is comparable to those obtained with ordinary silicon barrier detectors frequently used for these particles spectrometry. (author)

  10. Large angle scattering of {alpha}-particles from {sup 32}S

    Energy Technology Data Exchange (ETDEWEB)

    Coban, A.; Abdelmonem, M.S.; Khiari, F.Z.; Naqvi, A.A.; Aksoy, A

    1999-01-04

    The elastic scattering of {alpha}-particles from {sup 32}S was studied in the incident energy range between 4 and 8.9 MeV. In order to ascertain whether quasi-molecular states exist, as predicted in the {alpha}-{sup 32}S system, excitation functions were measured, and angular distribution measurements were carried out using targets with different thicknesses in the angular range from {theta}{sub lab} = 30 deg. to 175 deg. at each extreme in the excitation functions. The analysis of the angular distribution data at back angles was performed using the Regge-pole method. A resonance with J=3 was observed at 7.7 MeV in the {alpha}-{sup 32}S system. Evidence was also found for both a broad resonance which can be characterized by an angular momentum J=1, and for a narrow J=2 resonance.

  11. Geometrical parameters of tracks registered by collimated alpha particles on CR-39 detector

    International Nuclear Information System (INIS)

    The latent tracks formed on CR-39 solid state track detector on exposure of alpha radiations emanating from a collimated 241Am source were developed by a chemical etching method. Alpha track images were captured by an optical microscope and were processed by using Image Pro-Plus (6.0) software. GEANT4 simulations were carried out to obtain the angular and energy distribution profiles of the alpha particles. Apart from fluence, geometric parameters like aspect ratio (the ratio of the major to minor axis) and the depth profiles of etched tracks were measured experimentally and correlated with simulated angular and energy profile of incident radiations. Reasonable agreement was observed in the fluence and depth profile information obtained from experiments and simulations

  12. An ultra-thin Schottky diode as a transmission particle detector for biological microbeams

    International Nuclear Information System (INIS)

    We fabricated ultrathin metal-semiconductor Schottky diodes for use as transmission particle detectors in the biological microbeam at Columbia University's Radiological Research Accelerator Facility (RARAF). The RARAF microbeam can deliver a precise dose of ionizing radiation in cell nuclei with sub-micron precision. To ensure an accurate delivery of charged particles, the facility currently uses a commercial charged-particle detector placed after the sample. We present here a transmission detector that will be placed between the particle accelerator and the biological specimen, allowing the irradiation of samples that would otherwise block radiation from reaching a detector behind the sample. Four detectors were fabricated with co-planar gold and aluminum electrodes thermally evaporated onto etched n-type crystalline silicon substrates, with device thicknesses ranging from 8.5 μm - 13.5 μm. We show coincident detections and pulse-height distributions of charged particles in both the transmission detector and the commercial detector above it. Detections are demonstrated at a range of operating conditions, including incoming particle type, count rate, and beam location on the detectors. The 13.5 μm detector is shown to work best to detect 2.7 MeV protons (H+), and the 8.5 μm detector is shown to work best to detect 5.4 MeV alpha particles (4He++). The development of a transmission detector enables a range of new experiments to take place at RARAF on radiation-stopping samples such as thick tissues, targets that need immersion microscopy, and integrated microfluidic devices for handling larger quantities of cells and small organisms.

  13. Simulation study for high resolution alpha particle spectrometry with mesh type collimator

    International Nuclear Information System (INIS)

    An alpha particle spectrometry with a mesh type collimator plays a crucial role in identifying specific radionuclide in a radioactive source collected from the atmosphere or environment. The energy resolution is degraded without collimation because particles with a high angle have a longer path to travel in the air. Therefore, collision with the background increases. The collimator can cut out particles which traveling at a high angle. As a result, an energy distribution with high resolution can be obtained. Therefore, the mesh type collimator is simulated for high resolution alpha particle spectrometry. In conclusion, the collimator can improve resolution. With collimator, the collimator is a role of cutting out particles with a high angle, so, low energy tail and broadened energy distribution can be reduced. The mesh diameter is found out as an important factor to control resolution and counting efficiency. Therefore, a target particle, for example, 235U, can be distinguished by a detector with a collimator under a mixture of various nuclides, for example: 232U, 238U, and 232Th

  14. Alpha Particle Induced X-ray Emission in the Classroom

    International Nuclear Information System (INIS)

    We report on an experimental demonstration in an introductory modern physics course to elucidate the X-ray line spectra, and how they arise from transitions of electrons to inner shells. We seek to determine the effect of limited use of an interactive component as a supplement to a traditional lecture, and how it would improve the student achievement. In this preliminary study the students were exposed to traditional lectures on X-ray production and Bohr's model, they then were given a homework on the abc of X-ray spectra, after which they were given a pre-test on the materials, followed by an in-class demonstration, and a final post-exam. The gain, as measured from pre- to post-exams appears to remark the differences in how students approached the subject before and after the use of the demonstration. This initial study shows the validity of in-class demonstrations as teaching tools and opens a wide new area of research in modern physics teaching

  15. Characterization and remote sensing of biological particles using circular polarization

    CERN Document Server

    Nagdimunov, Lev; Mackowski, Daniel

    2014-01-01

    Biological molecules are characterized by an intrinsic asymmetry known as homochirality. The result is optical activity of biological materials and circular polarization in the light scattered by microorganisms, cells of living organisms, as well as molecules (e.g. amino acids) of biological origin. Lab measurements (Sparks et al. 2009a, b) have found that light scattered by certain biological systems, in particular photosynthetic organisms, is not only circular polarized but contains a characteristic spectral trend, showing a fast change and reversal of sign for circular polarization within absorption bands. Similar behavior can be expected for other biological and prebiological organics, especially amino acids. We begin our study by reproducing the laboratory measurements for photosynthetic organisms through modeling the biological material as aggregated structures and using the Multiple Sphere T-matrix (MSTM) code for light scattering calculations. We further study how the spectral effect described above d...

  16. The implications of particle energy and acidic media on gross alpha and gross beta determination using liquid scintillation

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Garcia, D. [Laboratori de Radiologia Ambiental (LRA), Departament de Quimica Analitica, Universitat de Barcelona, Marti i Franques, 1-11 Planta 3, E-08028 Barcelona (Spain); Llaurado, M., E-mail: montse.llaurado@ub.edu [Laboratori de Radiologia Ambiental (LRA), Departament de Quimica Analitica, Universitat de Barcelona, Marti i Franques, 1-11 Planta 3, E-08028 Barcelona (Spain); Rauret, G. [Laboratori de Radiologia Ambiental (LRA), Departament de Quimica Analitica, Universitat de Barcelona, Marti i Franques, 1-11 Planta 3, E-08028 Barcelona (Spain)

    2012-04-15

    The interaction of humans with radioactivity present in the environment from natural and artificial sources necessitates an evaluation of its risk on human health. Gross alpha and gross beta activities can provide a rapid evaluation of the radioactive content of a sample and can be simultaneously determined by using liquid scintillation counters. However, calibration of the liquid scintillation counter is required and is affected by many factors, such as particle energy and the acidity of the media. This study investigates what effect the particle energy used for calibration has on misclassification and how to account for this misclassification in routine measurements. The variability in measurement produced by the final pH, as well as any acids used in sample treatment, was also studied. These results showed that the most commonly used acid for these types of analyses, HNO{sub 3}, produced a high amount of misclassifications at very low pH. The results improved when HCl was used to adjust the sample to low pH. - Highlights: Black-Right-Pointing-Pointer We study the effect of alpha and beta energies on PSA optimisation. Black-Right-Pointing-Pointer The optimum PSA shifts to higher values as the alpha energy increases. Beta energies do not affect it. Black-Right-Pointing-Pointer We study the effect of pH on the simultaneous determination of gross alpha/beta activities. Black-Right-Pointing-Pointer HNO{sub 3} produces a high amount of misclassification at very low pH. Black-Right-Pointing-Pointer The results improve when HCl is used to adjust the sample to low pH.

  17. Survival of human osteosarcoma cells and normal human fibroblasts following alpha particle irradiation

    International Nuclear Information System (INIS)

    Cell survival of human osteosarcoma cells in culture following alpha particle irradiation is reported here for the first time. The osteosarcoma cell line (TE-85) is found to be less sensitive to inactivation by 5.6 MeV alpha particles (LET 86 keV/μm) than normal diploid human fibroblasts (NFS). Values for the mean lethal doses were estimated to be 103 rads for the TE-85 cells compared with 68 rads for the NFS cultures irradiated under identical conditions. It is postulated that the aneuploidy of the tumor cells with increased DNA chromosomal material may confer a selective advantage for the survival of tumor cells relative to normal cells with diploid chromosomes

  18. GAMCAT - a personal computer database on alpha particles and gamma rays from radioactive decay

    International Nuclear Information System (INIS)

    The GAMCAT database is a compilation of data describing the alpha particles and gamma rays that occur in the radioactive decay of all known nuclides, adapted for IBM Personal Computers and compatible systems. These compiled data have been previously published, and are now available as a compact database. Entries can be retrieved by defining the properties of the parent nuclei as well as alpha-particle and gamma-ray energies or any combination of these parameters. The system provides fast access to the data and has been completely written in C to run on an AT-compatible computer, with a hard disk and 640K of memory under DOS 2.11 or higher. GAMCAT is available from the Fachinformationszentrum Karlsruhe. (orig.)

  19. IAEA consultants' meeting on He-beam data base for alpha particle diagnostics of fusion plasmas

    International Nuclear Information System (INIS)

    The present Report contains the Summary of the IAEA Consultants' Meeting on ''He-Beam Data Base for Alpha Particle Diagnostics of Fusion Plasmas'' which was organized by the Atomic and Molecular Data Unit and held on June 3-5, 1991 at the IAEA Headquarters in Vienna, Austria. The Meeting Proceedings are briefly described and the reports of the Working Groups on the electron- and ion-impact processes are reproduced. A survey on the atomic data needs and required cross section accuracies for helium beam stopping calculations and alpha particle diagnostics of JET- and ITER-like plasmas is included. The conclusions and recommendations of the Meeting regarding the status of present data base (availability and quality) and the needs for its improvement are also given in this Summary Report. (author). Refs, figs and tabs

  20. Technique for measuring the losses of alpha particles to the wall in TFTR

    International Nuclear Information System (INIS)

    It is proposed to measure the losses of alpha particles to the wall in the Tokamak Fusion Test Reactor (TFTR) or any large deuterium-tritium (D-T) burning tokamak by a nuclear technique. For this purpose, a chamber containing a suitable fluid would be mounted near the wall of the tokamak. Alpha particles would enter the chamber through a thin window and cause nuclear reactions in the fluid. The material would then be transported through a tube to a remote, low-background location for measurement of the activity. The most favorable reaction suggested here is 10B(α,n)13N, although 14N(α,γ)18F and others may be possible. The system, the sensitivity, the probe design, and the sources of error are described

  1. Development of scintillator plates with high energy resolution for alpha particles made of GPS scintillator grains

    Science.gov (United States)

    Shimaoka, Takehiro; Kaneko, Junichi H.; Izaki, Kenji; Tsubota, Youichi; Higuchi, Mikio; Nishiyama, Shusuke

    2014-01-01

    A scintillator plate with high energy resolution was developed to produce an alpha particle monitor used in nuclear fuel reprocessing plants and mixed plutonium-uranium oxide (MOX) fuel plants. Grains of a Gd2Si2O7 (GPS) scintillator of several 10 to 550 μm were fixed on a glass substrate and were then mechanically polished. By increasing the size of scintillator grains and removing fine powders, the collected light yield and energy resolution for alpha particles were drastically improved. Energy resolution of 9.3% was achieved using average grain size of 91 μm. Furthermore, the ratios between counts in a peak and total counts were improved by more than 60% by the further increase of grain size and adoption of mechanically polished surfaces on both sides. Beta and gamma ray influences were suppressed sufficiently by the thin 100 μm scintillator plates.

  2. Conceptual design of confined alpha particle diagnostic system for ITER using an energetic He0 beam

    International Nuclear Information System (INIS)

    A conceptual design of an active-neutral-beam-probe-diagnostic-system for alpha particles produced by D-T nuclear reaction in a plasma confined by a magnetic fusion reactor has been examined. An energetic He0 beam plays an important role in the system. To detect a signal of neutralized alpha particles from the fusion plasma with enough S/N ratios, a high brightness He0 beam produced by spontaneous electron detachment from He- ions is required. A prototype of a He+ ion source has been designed and assembled to test the performance in producing a source beam for high intensity He- beam through a double-charge-exchange process in alkali metal vapor. (author)

  3. Biological radiation effects

    International Nuclear Information System (INIS)

    The stages of processes leading to radiation damage are studied, as well as, the direct and indirect mechanics of its production. The radiation effects on nucleic acid and protein macro moleculas are treated. The physical and chemical factors that modify radiosensibility are analysed, in particular the oxygen effects, the sensibilization by analogues of nitrogen bases, post-effects, chemical protection and inherent cell factors. Consideration is given to restoration processes by excision of injured fragments, the bloching of the excision restoration processes, the restoration of lesions caused by ionizing radiations and to the restoration by genetic recombination. Referring to somatic effects of radiation, the early ones and the acute syndrome of radiation are discussed. The difference of radiosensibility observed in mammalian cells and main observable alterations in tissues and organs are commented. Referring to delayed radiation effects, carcinogeneses, alterations of life span, effects on growth and development, as well as localized effects, are also discussed

  4. In-situ cross calibration method for alpha particle loss diagnostics at JET

    Czech Academy of Sciences Publication Activity Database

    Bonheure, G.; Perez Von Thun, Ch.; Reich, M.; Jachmich, S.; Murari, A.; Mlynář, Jan; Hult, M.; Arnold, D.; Dombrowski, T.; Laubenstein, M.; Wieslander, E.; Vidmar, T.; Vermaercke, P.; Cecil, F.E.; Cecconelo, M.; Craciunescu, T.; Darrow, D.; Lerche, E.; Tardocchi, M.; Van Eester, D.; Salmi, A.; Garcia-Munoz, M.; Yavorskij, V.; Popovichev, S.; Koslowski, H.R.; JET EFDA, Contributors.; Pinches, S.D.

    Vol. 33E. Sofia : European Physical Society, 2009 - (Mateev, M.; Benova, E.), P-2.145 ISBN 2-914771-61-4. - (Europhysics conference abstracts). [European Physical Society Conference on Plasma Physics /36th./. Sofia (BG), 29.06.2009-03.07.2009] Institutional research plan: CEZ:AV0Z20430508 Keywords : Tokamak * transport * tritium * in-situ * alpha particles Subject RIV: BL - Plasma and Gas Discharge Physics http://epsppd.epfl.ch/Sofia/pdf/P2_145.pdf

  5. Fission studies with 140 MeV $\\bm{\\alpha}$-Particles

    OpenAIRE

    Buttkewitz, A.; Duhm, H. H.; F. Goldenbaum(Forschungszentrum Jülich, Institut für Kernphysik, Jülich Germany); Machner, W.; Strauß, W.

    2009-01-01

    Binary fission induced by 140 MeV $\\alpha$-particles has been measured for $^{\\rm nat}$Ag, $^{139}$La, $^{165}$Ho and $^{197}$Au targets. The measured quantities are the total kinetic energies, fragment masses, and fission cross sections. The results are compared with other data and systematics. A minimum of the fission probability in the vicinity $Z^2/A=24$ is observed.

  6. Results of solid state nuclear track detector technique application in radon detection, by alpha particles tracks, for uranium prospecting in Caetite (BA-Brazil)

    International Nuclear Information System (INIS)

    The solid state nuclear track detector technique has been used in radon detection, by alpha particles tracks for uranium prospecting on the ground in Caetite city (Bahia-Brazil). The sensitive film to alpha particles used were CA 8015 exposed during 15 days and the results of three anomalies of this region are showed in a form of maps, made with the density of tracks obtained, and were compared with scintillation counter measurements. The technique showed to be simple and an effective auxiliary for the prospection of uranium ore bodies. The initial uranium exploration costs can be reduced by using this technique. (author)

  7. Nanometer fluorescent hybrid silica particle as ultrasensitive and photostable biological labels.

    Science.gov (United States)

    Yang, Huang-Hao; Qu, Hui-Ying; Lin, Peng; Li, Shun-Hua; Ding, Ma-Tai; Xu, Jin-Gou

    2003-05-01

    Nanometer-sized fluorescent hybrid silica (NFHS) particles were prepared for use as sensitive and photostable fluorescent probes in biological staining and diagnostics. The first step of the synthesis involves the covalent modification of 3-aminopropyltrimethoxysilane with an organic fluorophore, such as fluorescein isothiocyanate, under N2 atmosphere for getting a fluorescent silica precursor. Then the NFHS particles, with a diameter of well below 40 nm, were prepared by controlled hydrolysis of the fluorescent silica precursor with tetramethoxysilane (TMOS) using the reverse micelle technique. The fluorophores are dispersed homogeneously in the silica network of the NFHS particles and well protected from the environmental oxygen. Furthermore, since the fluorophores are covalently bound to the silica network, there is no migration, aggregation and leakage of the fluorophores. In comparison with common single organic fluorophores, these particle probes are brighter, more stable against photobleaching and do not suffer from intermittent on/off light emission (blinking). We have used these newly developed NFHS particles as a fluorescent marker to label antibodies, using silica immobilization method, for the immunoassay of human alpha-fetoprotein (AFP). The detection limit of this method was down to 0.05 ng mL(-1) under our current experimental conditions. We think this material would attract much attention and be applied widely in biotechnology. PMID:12790198

  8. Early and continuing effects of combined alpha and beta irradiation of the lung:

    Energy Technology Data Exchange (ETDEWEB)

    Scott, B.R.; Hahn, F.F.; Snipes, M.B.; Newton, G.J.; Eidson, A.F.; Mauderly, J.L.; Boecker, B.B.

    1988-03-01

    This report summarizes an inhalation exposure experiment that concerns early and continuing effects of combined alpha and beta irradiation of the lung of rats. Both morbidity at 18 months and mortality within 18 months after exposure were examined for rats exposed to the beta-emitter /sup 147/Pm, the alpha-emitter /sup 238/Pu, or both combined. The results were used to validate hazard-function models that were developed (1)for pulmonary functional morbidity at 18 months and (2) for lethality from radiation pneumonitis and pulmonary fibrosis within 18 months. Both models were found to adequately predict the experimental observations after combined chronic alpha and beta irradiation of the lung. A relative biological effectiveness of approximately 7 was obtained for /sup 238/Pu alpha radiation compared to /sup 147/Pm beta radiation for both pulmonary functional morbidity and lethality from radiation pneumonitis and pulmonary fibrosis. 12 refs., 16 figs., 11 tabs.

  9. Alpha particles energy estimation from track diameter development in a CR-39 detector.

    Science.gov (United States)

    Azooz, Aassim A; Al-Jubbori, Mushtaq A

    2016-09-01

    The slight nonlinearity in temporal development of tracks diameter in CR-39 nuclear track detectors is examined with the aim of attempting to find if such nonlinearity can be directly related to the charged particle energy. Narrowly spaced etching time-diameter experimental data for alpha particles at five energy values and for one additional energy value etched at five different temperatures are obtained. Initial results show good indication that measuring such time-diameter relationship can form a useful energy estimation tool. Good consistency with other independent published results is obtained. PMID:27341133

  10. Wurtzite Gallium Nitride as a scintillator detector for alpha particles (a Geant4 simulation)

    International Nuclear Information System (INIS)

    Gallium Nitride has become a very popular material in electronics and optoelectronics. Because of its interesting properties, it is suitable for a large range of applications. This material also shows very good scintillation properties that make it a possible candidate for use as a charged particles scintillator detector. In this work, we simulated the scintillation and optical properties of the gallium nitride in the presence of alpha particles using Geant4. The results show that gallium nitride can be an appropriate choice for this purpose

  11. Comparative analysis of inelastic interactions of protons, deuterons, and. cap alpha. particles with nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Barashenkov, V.S.; Zheregi, F.G.; Musul' manbekov, Z.Z.; Plyushchev, V.A.; Solov' eva, Z.I.

    1981-04-01

    Inelastic interactions of protons, deuterons, and ..cap alpha.. particles with emulsion nuclei at 3.6 Gev/nucleon are analyzed within the framework of the cascade-evaporation model. The model accounts well, within the limits of experimental error, for all the principal characteristics measured in experiment; in particular, it explains why the energy of the g protons emitted into the rear hemisphere is independent of the emission angle of these protons, of the mass of the primary particle, and of the degree of spallation of the target nucleus. Some discrepancy with experiment manifests itself only in the details.

  12. Characterization of actinide targets by low solid-angle alpha particle counting

    CERN Document Server

    Denecke, B; Pauwels, J; Robouch, P; Gilliam, D M; Hodge, P; Hutchinson, J M R; Nico, J S

    1999-01-01

    Actinide samples were characterized in an interlaboratory comparison between IRMM and NIST, including alpha-particle counting at defined low solid angle and counting in a 2 pi proportional gas counter. For this comparison, nine sup 2 sup 3 sup 3 UF sub 4 samples with high uniformity in the layer thickness were prepared at IRMM by deposition under vacuum. Polished silicon wafers were used as source substrates, and these were rotated during the deposition using a planetary rotation system. The estimated uncertainties for the defined low solid-angle methods were about 0.1% at both NIST and IRMM. The agreement of reported alpha-particle emission rates in the energy range 2.5-5.09 MeV was better than or equal to 0.02% for the defined solid-angle methods. When comparing total alpha-particle emission rates over the larger energy range 0-9 MeV (which includes all emissions from the daughter nuclides and the impurities), the agreement of the defined solid-angle methods was better than or equal to 0.05%. The 2 pi propo...

  13. Radon and progeny alpha-particle energy analysis using nuclear track methodology

    International Nuclear Information System (INIS)

    A preliminary procedure for alpha-energy analysis of radon and its progeny using nuclear track methodology (NTM) is described in this paper. The method is based on the relationship between alpha-particle energies deposited in polycarbonate material (CR-39) and the track size developed after a well-established chemical etching process. Track geometry, defined by parameters such as major or minor diameters, track area and overall track length, is shown to correlate with alpha-particle energy over the range 6.00 MeV (218Po) to 7.69 MeV (214Po). Track features are measured and the data analyzed automatically using a digital imaging system and commercial PC software. Examination of particle track diameters in CR-39 exposed to environmental radon reveals a multi-modal distribution. Locations of the maxima in this distribution are highly correlated with alphaparticle energies of radon daughters, and the distributions are sufficiently resolved to identify the radioisotopes. This method can be useful for estimating the radiation dose from indoor exposure to radon and its progeny. (author)

  14. Bismuth-212-labeled anti-Tac monoclonal antibody: alpha-particle-emitting radionuclides as modalities for radioimmunotherapy

    International Nuclear Information System (INIS)

    Anti-Tac, a monoclonal antibody directed to the human interleukin 2 (IL-2) receptor, has been successfully conjugated to the alpha-particle-emitting radionuclide bismuth-212 by use of a bifunctional ligand, the isobutylcarboxycarbonic anhydride of diethylenetriaminepentaacetic acid. The physical properties of 212Bi are appropriate for radioimmunotherapy in that it has a short half-life, deposits its high energy over a short distance, and can be obtained in large quantities from a radium generator. Antibody specific activities of 1-40 microCi/microgram (1 Ci = 37 GBq) were achieved. Specificity of the 212Bi-labeled anti-Tac was demonstrated for the IL-2 receptor-positive adult T-cell leukemia line HUT-102B2 by protein synthesis inhibition and clonogenic assays. Activity levels of 0.5 microCi or the equivalent of 12 rad/ml of alpha radiation targeted by anti-Tac eliminated greater than 98% the proliferative capabilities of HUT-102B2 cells with more modest effects on IL-2 receptor-negative cell lines. Specific cytotoxicity was blocked by excess unlabeled anti-Tac but not by human IgG. In addition, an irrelevant control monoclonal antibody of the same isotype labeled with 212Bi was unable to target alpha radiation to cell lines. Therefore, 212Bi-labeled anti-Tac is a potentially effective and specific immunocytotoxic reagent for the elimination of IL-2 receptor-positive cells. These experiments thus provide the scientific basis for use of alpha-particle-emitting radionuclides in immunotherapy

  15. The Alpha Particle X-Ray Spectrometer (APXS): Results from Gusev Crater and Calibration Report

    Science.gov (United States)

    Gellert, R.; Rieder, R.; Brueckner, J.; Clark, B.; Dreibus, G.; Klingelhoefer, G.; Lugmair, G.; Ming, D.; Waenke, H.; Yen, A.; Zipfel, J.; Squyres, S.

    2006-01-01

    The chemical composition of rocks and soils on Mars analyzed during the Mars Exploration Rover Spirit Mission was determined by X-ray analyses with the Alpha Particle X-Ray Spectrometer (APXS). Details of the data analysis method and the instrument calibration are presented. Measurements performed on Mars to address geometry effects and background contributions are shown. Cross calibration measurements among several instrument sensors and sources are discussed. An unintentional swap of the two flight instruments is evaluated. New concentration data acquired during the first 470 sols of rover Spirit in Gusev Crater are presented. There are two geological regions, the Gusev plains and the Columbia Hills. The plains contain soils that are very similar to previous landing sites on Mars. A meteoritic component in the soil is identified. Rocks in the plains revealed thin weathering rinds. The underlying abraded rock was classified as primitive basalt. One of these rocks contained significant Br that is probably associated with vein-filling material of different composition. One of the trenches showed large subsurface enrichments of Mg, S, and Br. Disturbed soils and rocks in the Columbia Hills revealed different elemental compositions. These rocks are significantly weathered and enriched in mobile elements, such as P, S, Cl, or Br. Even abraded rock surfaces have high Br concentrations. Thus, in contrast to the rocks and soils in the Gusev Plains, the Columbia Hills material shows more significant evidence of ancient aqueous alteration.

  16. Climatic and biological effects

    International Nuclear Information System (INIS)

    The ozone-climate problem has received considerable attention since concern was raised regarding possible threats to stratospheric ozone. Early climatic assessments of reduced ozone focused on the direct solar and longwave effects. Now a number of important feedback mechanisms are recognized as contributing significantly to indirect climatic effects. Although the focus in this chapter is on the climatic effect of reduced ozone, the discussion must include other trace gases as well. Many of the trace gases that interact photochemically to reduce ozone also have important radiative properties. Examples are chlorofluorocarbons (CFCl3 and CF2Cl2), nitrous oxide (N2O), and methane (CH4). Other gases, such as CO2, affect the temperature profile in the atmosphere, which can have an indirect effect on ozone through temperature-dependent reaction rates. The change in ozone, in turn, alters the change in temperature. The direct radiative effect of gases comes about through absorption of solar radiation and absorption and emission of longwave radiation (also referred to as thermal, terrestrial, or infrared radiation). The spectral distribution of solar and longwave radiation is shown. The principal gaseous absorbers of solar radiation are O2 and O3 in the stratosphere and H2O in the troposphere. As discussed in Chapter 2, ozone has absorption bands in the ultraviolet (uv) and visible regions of the solar spectrum. Water vapor absorbs primarily in the near-infrared spectral region

  17. Evidence of DNA double strand breaks formation in Escherichia coli bacteria exposed to alpha particles of different LET assessed by the SOS response

    International Nuclear Information System (INIS)

    Ionizing radiation produces a plethora of lesion upon DNA which sometimes is generated among a relatively small region due to clustered energy deposition events, the so called locally multiply damaged sites that could change to DSB. Such clustered damages are more likely to occur in high LET radiation exposures. The effect of alpha particles of different LET was evaluated on the bacterium Escherichia coli either by survival properties or the SOS response activity. Alpha radiation and LET distribution was controlled by means of Nuclear Track Detectors. The results suggest that alpha particles produce two types of lesion: lethal lesions and SOS inducing-mutagenic, a proportion that varies depending on the LET values. The SOS response as a sensitive parameter to assess RBE is mentioned. - Highlights: ► High LET radiation produce locally multiple damaged sites upon DNA. ► Bacteria were exposed to alpha particles of different LET. ► Results suggest that alpha particles produce lethal and SOS inducing/mutagenic. ► The proportion of such lesions varies depending on the LET values.

  18. Fluctuating Nonlinear Spring Model of Mechanical Deformation of Biological Particles.

    Directory of Open Access Journals (Sweden)

    Olga Kononova

    2016-01-01

    Full Text Available The mechanical properties of virus capsids correlate with local conformational dynamics in the capsid structure. They also reflect the required stability needed to withstand high internal pressures generated upon genome loading and contribute to the success of important events in viral infectivity, such as capsid maturation, genome uncoating and receptor binding. The mechanical properties of biological nanoparticles are often determined from monitoring their dynamic deformations in Atomic Force Microscopy nanoindentation experiments; but a comprehensive theory describing the full range of observed deformation behaviors has not previously been described. We present a new theory for modeling dynamic deformations of biological nanoparticles, which considers the non-linear Hertzian deformation, resulting from an indenter-particle physical contact, and the bending of curved elements (beams modeling the particle structure. The beams' deformation beyond the critical point triggers a dynamic transition of the particle to the collapsed state. This extreme event is accompanied by a catastrophic force drop as observed in the experimental or simulated force (F-deformation (X spectra. The theory interprets fine features of the spectra, including the nonlinear components of the FX-curves, in terms of the Young's moduli for Hertzian and bending deformations, and the structural damage dependent beams' survival probability, in terms of the maximum strength and the cooperativity parameter. The theory is exemplified by successfully describing the deformation dynamics of natural nanoparticles through comparing theoretical curves with experimental force-deformation spectra for several virus particles. This approach provides a comprehensive description of the dynamic structural transitions in biological and artificial nanoparticles, which is essential for their optimal use in nanotechnology and nanomedicine applications.

  19. Biological effects of inhaled radionuclides

    International Nuclear Information System (INIS)

    This report focuses on various types of radionuclides that may be inhaled and deposited in the respiratory tract. One of the primary goals of this ICRP Task Group is to assess specifically the biological implications of inhaled plutonium. Because other transuranics are becoming more abundant, information on americium, curium and einsteinium is included. Data are also included from studies of polonium and of several beta-gamma emitting isotopes. The Task Group evaluated most of the data on the biological effects of inhaled radionuclides in experimental animals to identify the tissues at risk and to assess possible dose-response relationships. Few data from human cases of inhaled radionuclides are available for this assessment. The biological effects of nonradioactive air pollutants were also considered to provide the perspective that all air pollutants can have a deleterious effect on human life and to emphasize the possibility for combined or synergistic effects of nonradioactive and radioactive substances on the respiratory tract. (orig./HP)

  20. Particle-in-cell simulations of the magnetoacoustic cyclotron instability of fusion-born alpha-particles in tokamak plasmas

    Science.gov (United States)

    Cook, J. W. S.; Dendy, R. O.; Chapman, S. C.

    2013-06-01

    Ion cyclotron emission (ICE) is the only collective radiative instability, driven by confined fusion-born alpha-particles, observed from deuterium-tritium (DT) plasmas in both JET and TFTR. Using first principles particle-in-cell simulations of the magnetoacoustic cyclotron instability (MCI), we elucidate some of the fully kinetic nonlinear processes that may underlie observations of ICE from fusion products in these large tokamaks. We find that the MCI is intrinsically self-limiting on very fast timescales, which may help explain the observed correlation between linear theory and observed ICE intensity. The simulations elaborate the nature of the excited electric and magnetic fluctuations, from first principles, confirming the dominant role of fast Alfvénic and electrostatic components which is assumed ab initio in analytical treatments.

  1. Biological radiation effects

    International Nuclear Information System (INIS)

    Everyone is exposed to a complex mix of electromagnetic fields (EMF) of different frequencies that permeate our environment. Exposures to these EMF are increasing significantly as technology advances unabated and new applications are found. Technological progress in the broadest sense of the word has always been associated with various hazards and risks, both perceived and real. The industrial, commercial and household application on EMF is no exception. Throughout the world, the general public is concerned that exposure to EMF from such sources as high voltage power lines, broadcasting networks, mobile telephones and their base stations could lead to adverse health consequences, especially in children. As a result, the construction of new power lines and broadcasting and mobile telephone network has met with considerable opposition in many countries. Public exposure to EMF is regulated by a variety of voluntary and legal limits, together with various national safety standards. Guidelines are designed to avoid all identified hazards, from short and long term exposure, recommended limits. The aim of this paper is to report the summary of the actual scientific knowledge about the potential health effects and hazards due to man made EMF and the new tendencies of the social and political choices

  2. Biological effects of mutagenic agents

    International Nuclear Information System (INIS)

    There is an increasing body of evidence that mutagenic agents (biological, chemical and physical) play an important role in the etiology of human diseases. Mutations may occur in the germinal as well as in the somatic cells. Mutations of the germ cells may result on infertility or fertilization of damaged cells, the later leading to abortion or birth of a malformed fetus. Somatic-cells mutations may have various biological effects, depending on the period of the human life at which the mutation occurs. If it occurs during the prenatal life, a teratogenic or carcinogenic effect will be observed. If the somatic cell is damaged during the postnatal life, this will lead to neoplastic transformation. Therefore it is extremely important to know the mutagenic, teratogenic and carcinogenic effects of various biological, chemical and physical agents in order to eliminate them from our environment. (author). 13 refs, 4 figs, 1 tab

  3. Virtual effects of Higgs particles

    Science.gov (United States)

    McWilliams, Bruce; Li, Ling-Fong

    1981-02-01

    The possibility of observing Higgs particles through virtual effects is considered in detail for a general gauge theory. The effect of charged Higgs particles on low-energy weak interaction processes, like muon decay, tau decay, nuclear beta decay, pion decay, and some higher-order processes is analyzed. The effect of flavor-changing neutral Higgs particles on rare decay modes of the muon and kaon, μe conversion, K o- overlineKo and D o- overlineDo mixing is also studied. We discuss constraints on possible extensions of the Weinberg-Salam model and experiments sensitive to their Higgs particles. In particular, we analyze the neutral Higgs which couple to fermions in the minimal SU(2) L×SU(2) R×U(1) model and find that they probably have mass greater than 100 GeV.

  4. Study of nanoscale structural biology using advanced particle beam microscopy

    Science.gov (United States)

    Boseman, Adam J.

    This work investigates developmental and structural biology at the nanoscale using current advancements in particle beam microscopy. Typically the examination of micro- and nanoscale features is performed using scanning electron microscopy (SEM), but in order to decrease surface charging, and increase resolution, an obscuring conductive layer is applied to the sample surface. As magnification increases, this layer begins to limit the ability to identify nanoscale surface structures. A new technology, Helium Ion Microscopy (HIM), is used to examine uncoated surface structures on the cuticle of wild type and mutant fruit flies. Corneal nanostructures observed with HIM are further investigated by FIB/SEM to provide detailed three dimensional information about internal events occurring during early structural development. These techniques are also used to reconstruct a mosquito germarium in order to characterize unknown events in early oogenesis. Findings from these studies, and many more like them, will soon unravel many of the mysteries surrounding the world of developmental biology.

  5. Health effects of exhaust particles

    Energy Technology Data Exchange (ETDEWEB)

    Pihlava, T.; Uuppo, M.; Niemi, S.

    2013-11-01

    This report introduces general information about diesel particles and their health effects. The purpose of this report is to introduce particulate matter pollution and present some recent studies made regarding the health effects of particulate matter. The aim is not to go very deeply into the science, but instead to keep the text understandable for the average layman. Particulate matter is a complex mixture of extremely small particles and liquid droplets. These small particles are made up of a number of components that include for example acids, such as nitrates and sulphates, as well as organic chemicals, metals and dust particles from the soil. Particulate matter comes from several sources, such as transportation emissions, industrial emissions, forest fires, cigarette smoke, volcanic ash and climate variations. Particles are divided into coarse particles with diameters less than 10 ..m, fine particles with diameters smaller than 2.5 ..m and ultra-fine particles with diameters less than 0.1 ..m. The particulate matter in diesel exhaust gas is a highly complex mixture of organic, inorganic, solid, volatile and partly volatile compounds. Many of these particles do not form until they reach the air. Many carcinogenic compounds have been found in diesel exhaust gas and it is considered carcinogenic to humans. Particulate matter can cause several health effects, such as premature death in persons with heart or lung disease, cancer, nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function and an increase in respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing. It is estimated that in Finland about 1300 people die prematurely due to particles and the economic loss in the EU due to the health effects of particles can be calculated in the billions. Ultra-fine particles are considered to be the most harmful to human health. Ultrafine particles usually make the most of their quantity and surface area

  6. Estimation of the {alpha} particles and neutron distribution generated during a fusion reaction; Evaluation de la distribution des particules {alpha} et des neutrons issus de la reaction de fusion

    Energy Technology Data Exchange (ETDEWEB)

    Dellacherie, S.

    1997-12-01

    The respective distributions (or density probabilities) of {alpha} particles and neutrons have been modeled using a Monte-Carlo method for the thermonuclear fusion reaction D + T {yields} {alpha} + n + 17.6 MeV. (N.T.).

  7. Response of Ni/4H-SiC Schottky barrier diodes to alpha-particle irradiation at different fluences

    Science.gov (United States)

    Omotoso, E.; Meyer, W. E.; Auret, F. D.; Diale, M.; Ngoepe, P. N. M.

    2016-01-01

    Irradiation experiments have been carried out on 1.9×1016 cm-3 nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.6×1010 to 9.2×1011 cm-2. Current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements have been carried out to study the change in characteristics of the devices and free carrier removal rate due to alpha-particle irradiation, respectively. As radiation fluence increases, the ideality factors increased from 1.20 to 1.85 but the Schottky barrier height (SBHI-V) decreased from 1.47 to 1.34 eV. Free carrier concentration, Nd decreased with increasing fluence from 1.7×1016 to 1.1×1016 cm-2 at approximately 0.70 μm depth. The reduction in Nd shows that defects were induced during the irradiation and have effect on compensating the free carrier. The free carrier removal rate was estimated to be 6480±70 cm-1. Alpha-particle irradiation introduced two electron traps (E0.39 and E0.62), with activation energies of 0.39±0.03 eV and 0.62±0.08 eV, respectively. The E0.39 as attribute related to silicon or carbon vacancy, while the E0.62 has the attribute of Z1/Z2.

  8. Effect of water alpha radiolysis on the spent nuclear fuel UO2 matrix alteration

    International Nuclear Information System (INIS)

    Leaching experiments with solution renewal were carried out on UO2 pellets doped with alpha emitters (238/239Pu) to quantify the impact of alpha irradiation on UO2 matrix alteration. Three batches of doped UO2 pellets with different alpha flux levels were studied as well as spent fuel fragments. Interim storage in air of UO2 pellets doped with alpha emitters results in variations of the UO2 surface reactivity, which depends on the alpha particle flux at the interface and on the interim storage duration. The variation in the surface reactivity and the greater uranium release following interim storage cannot be attributed to the effect of alpha radiolysis in aerated media since the uranium release tends toward the same value after several leaching cycles for the doped UO2 pellet batches and spent fuel. However, leaching experiments performed in deaerated media after annealing the samples and pre-leaching the surface suggest that alpha radiolysis does indeed affect the dissolution, which varies with the flux at the UO2/water interface. (authors)

  9. Disturbance from Am-241 Photons of the Cellular Dose by Am-241 Alpha Emissions: Am-241 as an alternative source of alpha particles to radon daughters

    International Nuclear Information System (INIS)

    The Radiation Bioengineering Laboratory (RadBio Lab) at Seoul National University (SNU) has built an Am-241 alpha particle irradiator for study of cellular responses to radiation from radon daughters. The radon daughters of concern that cause internal exposure from inhalation of radon-contaminated air are Po-218, Po-214 and Po-210. In their alpha decay schemes, the yields of photon emissions are negligible. Unfortunately, Am-241, the source of alpha irradiator in RadBio Lab, emits photons at every alpha decay while transforming to Np-237 of long half-life. Employing Am-241 as the source simulating radon daughters, therefore, requires that photon emissions from Am-241 be specified in term of dose contribution. In this study, Monte Carlo calculations have been made to characterize dose contributions of Am-241 photon emissions. This study confirms that disturbance from Am-241 photon emissions of the cellular dose by Am-241 alpha emissions is negligible. Dose contamination fraction from photon emissions was 8.02 .. 10-6 at 25 mm SSD at maximum. Also, note that LET in tissue-equivalent medium varies within about 20% for alpha particles at energies over 5 MeV

  10. Disturbance from Am-241 Photons of the Cellular Dose by Am-241 Alpha Emissions: Am-241 as an alternative source of alpha particles to radon daughters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ki-Man; Kim, Eun-Hee [Seoul National University, Seoul (Korea, Republic of)

    2015-05-15

    The Radiation Bioengineering Laboratory (RadBio Lab) at Seoul National University (SNU) has built an Am-241 alpha particle irradiator for study of cellular responses to radiation from radon daughters. The radon daughters of concern that cause internal exposure from inhalation of radon-contaminated air are Po-218, Po-214 and Po-210. In their alpha decay schemes, the yields of photon emissions are negligible. Unfortunately, Am-241, the source of alpha irradiator in RadBio Lab, emits photons at every alpha decay while transforming to Np-237 of long half-life. Employing Am-241 as the source simulating radon daughters, therefore, requires that photon emissions from Am-241 be specified in term of dose contribution. In this study, Monte Carlo calculations have been made to characterize dose contributions of Am-241 photon emissions. This study confirms that disturbance from Am-241 photon emissions of the cellular dose by Am-241 alpha emissions is negligible. Dose contamination fraction from photon emissions was 8.02 .. 10{sup -6} at 25 mm SSD at maximum. Also, note that LET in tissue-equivalent medium varies within about 20% for alpha particles at energies over 5 MeV.

  11. Immuno-vectorization of radioelements emitters of alpha particles: a new therapy in cancerology

    International Nuclear Information System (INIS)

    The radio-immunotherapy is an anti cancerous therapy which consists in vectorising with immuno-specific agents very radio toxic radioelements on tumors or in their environment to destroy them. The first part of this report presents the different characteristics of antibodies as well as their means of production under monoclonal shapes specifically steered against a tumoral antigen of interest. The second part of this report replaces the importance of the immunological vectors in the context of the nuclear medicine. It is notably described that the different methods which allow to radio-label the vector, as well as the different ways of optimization which were envisaged to improve the targeting of radioelements on a tumor. These different developments allow to define the potential place of the alpha radio-immunotherapy in treatments and so re-place the interest of the experimental part. If the radio-immunotherapy, using beta emitters isotopes as the 131iodine or the90yttrium, is today current in anti cancerous therapy, it finds limits because of the disintegration characteristics of the isotopes it uses. Indeed, compared with alpha particles, the beta particles deposit less energy by unit of length in the crossed material.The experimental part of this report aims at studying the feasibility of the coupling between an immunological vector and an alpha emitter isotope.The different tests led on the bismuth 213, the bismuth 212, the lead 212 and the astatine 211 demonstrated that the fixation of these radionuclides was possible. This research theme is strengthened by the construction in Nantes of a cyclotron with high energy ( A.R.R.O.N.A.X.) and the optimization of the obtained promising results should allow a therapeutic use in oncology of the alpha radio-immunotherapy. (N.C.)

  12. Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine

    Science.gov (United States)

    Rodríguez-Fernández, Luis

    2010-09-01

    Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.

  13. Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine

    International Nuclear Information System (INIS)

    Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.

  14. Investigation of double strand breaks induced by alpha particle irradiation using C.N.B.G. microbeam in human keratinocytes

    International Nuclear Information System (INIS)

    To understand the mechanisms of interaction of ionizing radiation with living tissues exposed to low and protracted doses remains a major issue for risk evaluation. The response cannot be found in epidemiological studies because the only available data concern accidental exposures to high doses of radiation. The natural exposure represents the main source of exposure in the daily life, just before the medical sources (radiology, radiotherapy). In addition, this kind of exposure is very difficult to reproduce in vitro by irradiating cell lines. The method per preference is based on random irradiation of cell populations. The mean number of particles having traversed cells is then calculated on the basis of Poisson statistics. In addition to inevitable multiple impacts, the numerous potential intracellular targets (nuclei, cytoplasm), the indirect effects induced by the impact of particles on neighbouring cells or simply the extracellular targets, constitute phenomena that make more complex the interpretation of experimental data. A charged particle microbeam was developed at C.E.N.B.G. to perform the targeted irradiation of individual cells with a targeting precision of a few microns. It is possible to deliver a counted number of alpha particles down to the ultimate dose of one alpha per cell, to target predetermined cells and then to observe the response of the neighbouring cells. This facility has been validated during this work on human keratinocyte cells expressing a recombinant nuclear fluorescent protein (histone H2B-GFP). The combination of ion micro-beams with confocal microscopy and numeric quantitative analysis allowed the measurement of DNA double strand breaks via the phosphorylation of the histone H2A.X in individual cells. The mechanisms of DNA reparation and apoptosis induction were also in the scope of those studies. The experimental results obtained during this thesis validate the methodology we have developed by demonstrating the targeting

  15. Modelling TF ripple loss of alpha particles in TFTR DT experiments

    International Nuclear Information System (INIS)

    Modelling of TF ripple loss of alphas in DT experiments on TFTR now includes neoclassical calculations of first orbit loss, stochastic ripple diffusion, ripple trapping and collisional effects. A rapid way to simulate experiment has been developed which uses a simple stochastic domain model for TF ripple loss within the TRANSP analysis code, with the ripple diffusion threshold evaluated by comparison with more accurate but computationally expensive Hamiltonian coordinate guiding center code simulations. Typical TF collisional ripple loss predictions are 6-10% loss of alphas for TFTR D-T experiments at Ip = 1.0-2.0 MA and R = 2.52 m

  16. Cranial nerve damage in patients after alpha (heavy)-particle radiation to the pituitary

    International Nuclear Information System (INIS)

    The records of 161 patients were reviewed to determine if radiation damage had occurred following cranial irradiation. All of these patients had received alpha-particle radiation to their pituitary glands during the period when this form of therapy was given for diabetic retinopathy. Extraocular muscle palsy developed in 11 of these patients, iridoplegia in six, and fifth nerve damage in six. All of the palsies developed within a short period following their irradiation, and a definite dose relationship was present. The dose rate was approximately 100 rads/min for all cases. Fractionation varied but it is known for all cases

  17. Cranial nerve damage in patients after alpha (heavy)-particle radiation to the pituitary

    International Nuclear Information System (INIS)

    The records of 161 patients were reviewed to determine if radiation damage had occurred following cranial irradiation. All of these patients had received alpha-particle radiation to their pituitary glands for diabetic retinopathy. Extraocular muscle palsy developed in 11 of these patients, iridoplegia in six, and fifth nerve damage in six. All of the palsies developed within a short period following their irradiation, and a definite dose relationship was present. The estimated doses to the third, fourth, fifth, and sixth cranial nerves was calculated at a saggital plane 13 to 15 mm from the pituitary by using computer-drawn dosimetry charts for the respective aperture size

  18. Selection of filter media used for monitoring airborne alpha-emitting particles in a radiological emergency

    International Nuclear Information System (INIS)

    We have developed on air monitor for alpha-emitting particles released to the atmosphere at an accident of nuclear reprocessing plant. Selection of a suitable filter for the monitor is considerably important in order to achieve the high-sensitive measurement of radioactive concentration. We have examined surface collection efficiencies and pressure drops for the various filters that are commercially available in Japan. It was found that the PTFE membrane filter with backing had superior performance to the others, that is, a high surface collection efficiency and low pressure drop. (author)

  19. Theoretical and empirical status of the two-deuteron-alpha-particle vertex

    International Nuclear Information System (INIS)

    The two-deuteron-alpha-particle overlap, including its D-wave component, is evaluated in the case of realistic two- and four-body wavefunctions. The deduced theoretical value is compared with improved empirical estimates based upon DWBA analyses of (d,α) reactions in the sd shell and which incorporate the best available shell-model information for the nuclear states involved. The theoretical and empirical values of this analysis are in agreement. The result differs substantially from other recent empirical estimates obtained from (d,α) reactions upon heavier target nuclei and from simple theoretical estimates which make use of a point-deuteron approximation. (author)

  20. Chemistry of Rocks and Soils in Gusev Crater from the Alpha Particle X-ray Spectrometer

    Science.gov (United States)

    Gellert, R.; Rieder, R.; Anderson, R. C.; Brueckner, J.; Clark, B. C.; Dreibus, G.; Economou, T.; Klingelhoefer, G.; Lugmair, G. W.; Ming, D. W.

    2005-01-01

    The alpha particle x-ray spectrometer on the Spirit rover determined major and minor elements of soils and rocks in Gusev crater in order to unravel the crustal evolution of planet Mars. The composition of soils is similar to those at previous landing sites, as a result of global mixing and distribution by dust storms. Rocks (fresh surfaces exposed by the rock abrasion tool) resemble volcanic rocks of primitive basaltic composition with low intrinsic potassium contents. High abundance of bromine (up to 170 parts per million) in rocks may indicate the alteration of surfaces formed during a past period of aqueous activity in Gusev crater.

  1. Study of compound nucleus formation via bremsstrahlung emission in proton $\\alpha$-particle scattering

    CERN Document Server

    Maydanyuk, Sergei P

    2016-01-01

    In this paper a role of many-nucleon dynamics in formation of the compound $^{5}{\\rm Li}$ nucleus in the scattering of protons off $\\alpha$-particles at the proton incident energies up to 20 MeV is investigated. We propose a bremsstrahlung model allowing to extract information about probabilities of formation of such nucleus on the basis of analysis of experimental cross-sections of the bremsstrahlung photons. In order to realize this approach, the model includes elements of microscopic theory and also probabilities of formation of the short-lived compound nucleus. Results of calculations of the bremsstrahlung spectra are in good agreement with the experimental cross-sections.

  2. Deuteron-and alpha particle-induced K-shell ionisation of W and Au atoms

    International Nuclear Information System (INIS)

    Deuteron - and alpha particle - induced K-shell ionisation cross sections for W and Au were obtained from thick-target measurements for low impact velocities. They were compared to proton-induced cross sections in the same range of velocities. Equal-velocity cross sections ratios are a very stringent test to the corrections incorporated to the PWBA calculations. The σd/σp data presented in this paper sheds some light on the Coulomb-deflection corrections discussed in the literature. The consequences of the inelastic character of the ionisation process are thoroughly examined. (Author)

  3. Sensitivity of alpha-particle-driven Alfven eigenmodes to q-profile variation in ITER scenarios

    CERN Document Server

    Rodrigues, P; Fazendeiro, L; Ferreira, J; Coelho, R; Nabais, F; Borba, D; Polevoi, N F Loureiro A R; Pinches, S D; Sharapov, S E

    2016-01-01

    An hybrid ideal-MHD/drift-kinetic approach to assess the stability of alpha-particle-driven Alfven eigenmodes in burning plasmas is used to show that certain foreseen ITER scenarios, namely the $I_\\mathrm{p} = 15$ MA baseline scenario with very low and broad core magnetic shear, are sensitive to small changes in the background magnetic equilibrium. Slight perturbations (of the order of 1%) in the total plasma current are seen to cause large variations in the growth rate, toroidal mode number, and radial location of the most unstable eigenmodes found. The observed sensitivity is shown to proceed from the very low magnetic shear values attained throughout the plasma core.

  4. Analysis of individual biological particles by mass spectrometry

    Science.gov (United States)

    Sinha, M. P.; Platz, R. M.; Vilker, V. L.; Friedlander, S. K.

    1984-01-01

    A method is developed for the detection and identification of biological particles introduced in aerosol form into a quadrupole mass spectrometer. The bacterial aerosol is generated by nebulizing an ethanol suspension. The particles are introduced into the ion source of the mass spectrometer in the form of a beam, where they are individually volatilized on a V-type rhenium filament and ionized by electron impaction. It is shown that the average intensity of a mass peak is obtained from the pulse height distribution of about a thousand ion pulses from different particles. Pseudomonas putida, Bacillus subtilis, and Bacillus cereus are used in the studies. Differences between the relative intensities of mass peaks in the spectra from P. putida and B. subtilis are found and may provide a method for differentiation of microorganisms. The results for the two species agree reasonably well with those reported by Kistemaker et al. (1975) and Schulten et al. (1973). However, there exist some differences between the two spectra in the high mass range due to the difference in the pyrolysis conditions.

  5. Nitric oxide mediated DNA double strand breaks induced in proliferating bystander cells after {alpha}-particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Han Wei [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Chen Shaopeng [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Yu, K.N., E-mail: peter.yu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Wu Lijun [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2010-02-03

    Low-dose {alpha}-particle exposures comprise 55% of the environmental dose to the human population and have been shown to induce bystander responses. Previous studies showed that bystander effect could induce stimulated cell growth or genotoxicity, such as excessive DNA double strand breaks (DSBs), micronuclei (MN), mutation and decreased cell viability, in the bystander cell population. In the present study, the stimulated cell growth, detected with flow cytometry (FCM), and the increased MN and DSB, detected with p53 binding protein 1 (53BP1) immunofluorescence, were observed simultaneously in the bystander cell population, which were co-cultured with cells irradiated by low-dose {alpha}-particles (1-10 cGy) in a mixed system. Further studies indicated that nitric oxide (NO) and transforming growth factor {beta}1 (TGF-{beta}1) played very important roles in mediating cell proliferation and inducing MN and DSB in the bystander population through treatments with NO scavenger and TGF-{beta}1 antibody. Low-concentrations of NO, generated by spermidine, were proved to induce cell proliferation, DSB and MN simultaneously. The proliferation or shortened cell cycle in bystander cells gave them insufficient time to repair DSBs. The increased cell division might increase the probability of carcinogenesis in bystander cells since cell proliferation increased the probability of mutation from the mis-repaired or un-repaired DSBs.

  6. The fine structure constant alpha: relevant for a model of a self-propelling photon and for particle masses

    Science.gov (United States)

    Greulich, Karl O.

    2015-09-01

    A model for a self propelling (i.e. massless) photon1 is based on oscillations of a pair of charges amounting to elementary charge divided by SQRT alpha, where alpha is the fine structure (Sommerfeld) constant. When one assumes a similar model for particles that do have rest mas (i.e. which are non- self propelling), alpha plays also a role in the rest masses of elementary particles. Indeed all fundamental elementary particle masses can be described by the alpha / beta rule2 --> m(particle) = alpha-n * betam* 27.2 eV /c2 where beta is the proton to electron mass ratio 183612 and n= 0….14, m= -1,0 or Thus, photons and particle masses are intimately related to the fine structure constant. If the latter would not have been strictly constant throughout all times, this would have had consequences for the nature of light and for all masses including those of elementary particles.

  7. The role of biological processes in the synthesis of plant origin of magnetic nano particles

    International Nuclear Information System (INIS)

    Full text:In recent years, in various spheres, particular in the use of medicine and the use of iron oxide (magnetit-Fe3O4, magemit Fe2O3) needed in the diagnostics the problems of synthesis of magnetic nano particles are in the centre of the focus of many scholars.The implementation of biological methods of synthesis of magnetic nano particles, it is very urgent clarification of the role of biological processes synthesis of nano particles. What is the role of biological processes in the synthesis of magnetic nano particles plant in order to clarify the model of the wheat (Triticum vulgare) and pea (Cicer arietinum L.) plants and seeds have been used. The study of the effects of radiation on organisms of different types of cell and chromosome levels of various radiation effects and radiation to understand the nature of the influence of the nature of the forecast allows you to substantiate. Chromosome aberation was has been taken in the cells of pea sprout exposures radiation rays as a criterion of cytogenetic effects. EPR studies of the pea and wheat seeds (control and radiations) were used. In accordance with the results of EPR experiments were carried out with pea seeds.

  8. The recovery of biological particles in high-speed continuous centrifuges with special reference to feed-zone break-up effects

    OpenAIRE

    Mannweiler, K.

    1989-01-01

    In the first part of this thesis the means are described by which an industrial disc stack centrifuge may be scaled-down to process in a meaningful fashion small volumes of particle suspensions. The centrifuge separation characteristics so measured were suitable for direct scale-up predictions of centrifuge performance. Experiments with a dye tracer and a reduced number of discs indicated that the flow through the disc centrifuge is influenced by the position of the separati...

  9. Radon as a medicine. Therapeutic effectiveness, biological mechanism and comparative risk assessment

    International Nuclear Information System (INIS)

    Proofs of the therapeutic efficiency of balneological radon applications administered to patients suffering from rheumatic diseases, investigations into the biological action mechanism associated with the alpha particles emitted by radon and its radioactive daughter products, and the comparative risk assessment of radon treatment and medicinal pain therapy have been the research projects whose results are summarized in this book. Controlled clinical studies, if possible performed as prospective, randomized and placebo-controlled double blind studies, have given evidence that the therapeutic effects of balneological radon applications - long-lasting pain reduction and reduced consumption of medicines compared with controls - are significantly persisting over many post-treatment months. The molecular and cellular mechanism of action underlying these long-lasting therapeutic effects has been identified as the down-regulation of cellular immune responses, initiated by cellular apoptosis sequential to low alpha particle doses and by the subsequent release of anti-inflammatory cytokines. The unwanted side-effects of non-steroidal anti-rheumatic drug treatments have to be compared with the absence of side effects from the balneological radon applications which merely involve radiation doses well below the mean value and the fluctuation width of the annual doses attributable to everybody's natural radiation exposure.

  10. Radon as a medicine. Therapeutic effectiveness, biological mechanism and comparative risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Deetjen, Peter; Falkenbach, Albrecht; Harder, Dietrich; Joeckel, Hans; Kaul, Alexander; Philipsborn, Henning von

    2014-07-01

    Proofs of the therapeutic efficiency of balneological radon applications administered to patients suffering from rheumatic diseases, investigations into the biological action mechanism associated with the alpha particles emitted by radon and its radioactive daughter products, and the comparative risk assessment of radon treatment and medicinal pain therapy have been the research projects whose results are summarized in this book. Controlled clinical studies, if possible performed as prospective, randomized and placebo-controlled double blind studies, have given evidence that the therapeutic effects of balneological radon applications - long-lasting pain reduction and reduced consumption of medicines compared with controls - are significantly persisting over many post-treatment months. The molecular and cellular mechanism of action underlying these long-lasting therapeutic effects has been identified as the down-regulation of cellular immune responses, initiated by cellular apoptosis sequential to low alpha particle doses and by the subsequent release of anti-inflammatory cytokines. The unwanted side-effects of non-steroidal anti-rheumatic drug treatments have to be compared with the absence of side effects from the balneological radon applications which merely involve radiation doses well below the mean value and the fluctuation width of the annual doses attributable to everybody's natural radiation exposure.

  11. The acute effects of alpha and beta irradiation of mouse skin and the factors affecting the response

    International Nuclear Information System (INIS)

    Several problems regarding acute effects of alpha and beta irradiation were investigated in order to clarify protection problems of localised doses to the skin. A study into the acute biological effects of different energy beta emitters and the effects of energy and area on the response showed direct relationships between these criteria for a range of different acute responses with different time courses. Three different types of acute response were found and these are described as 'moist desquamation', 'acute ulceration' and 'acute epidermal necrosis'. An unexpected finding was that the lower energy beta emitter 170Tm was as efficient at inducing scab formation as the higher energy 90Sr sources for the same area of exposure. Experiments using 2x4 cm2 exposures to 224Cm alpha particles showed that the response to this poorly penetrating radiation was minimal after doses as high as 180 Gy measured at 10 μm into the skin. In comparison, large area exposure to 170Tm produced areas of prolonged scabbing after doses up to 100 Gy. However, the intensity of the reaction varied between strains. (author)

  12. Physical consequences of the alpha/beta rule which accurately calculates particle masses

    International Nuclear Information System (INIS)

    Using the fine structure constant α (=1/137.036), the proton vs. electron mass ratio β (= 1836.2) and the integers m and n, the α/β rule: mparticle = α-n x β m x 27.2 eV/c2 allows almost exact calculation of particle masses. (K.O.Greulich, DPG Spring meeting 2014, Mainz, T99.4) With n=2, m=0 the electron mass becomes 510.79 keV/c2 (experimental 511 keV/c2) With n=2, m=1 the proton mass is 937.9 MeV/c2 (literature 938.3 MeV/c2). For n=3 and m=1 a particle with 128.6 GeV/c2 close to the reported Higgs mass, is expected. For n=14 and m=-1 the Planck mass results. The calculated masses for gauge bosons and for quarks have similar accuracy. All masses fit into the same scheme (the alpha/beta rule), indicating that non of these particle masses play an extraordinary role. Particularly, the Higgs Boson, often termed the *God particle* plays in this sense no extraordinary role. In addition, particle masses are intimately correlated with the fine structure constant α. If particle masses have been constant over all times, α must have been constant over these times. In addition, the ionization energy of the hydrogen atom (13.6 eV) needs to have been constant if particle masses have been unchanged or vice versa. In conclusion, the α/β rule needs to be taken into account when cosmological models are developed.

  13. Investigation of the performance of alpha particle counting and alpha-gamma discrimination by pulse shape with micro-pixel avalanche photodiode

    International Nuclear Information System (INIS)

    Being capable measuring small lights gives possibility to use micro-pixel avalanche photodiodes with scintillators. It is shown two prototypes to use micro-pixel avalanche photodiodes with and without scintillators as alpha and gamma counters in this paper. First prototype is to use two micro-pixel avalanche photodiodes. One for detecting alpha particles and closer to it, the second one with a thin plastic scintillator for detecting gamma rays. Second prototype is called two-layers configuration in which it is used only one micro-pixel avalanche photodiode, but two scntillators with different decay times. One can distinquish alpha particle and gamma ray events by using pulse shape discrimination techniques in the two-layer configuration. In this work an alpha particle and gamma ray counting performance of micro-pixel avalanche photodiodes without scintillators and its combination of plastic and BGO+ plastic scintillators was investigated. Obtained results showed the detection performance of the micro-pixel avalanche photodiodes in combination with plastic scintillator was about the same as conventional semiconductor detectors

  14. Etching characteristic studies for the detection of alpha particles in DAM–ADC nuclear track detector

    International Nuclear Information System (INIS)

    This study reports the characteristic studies for the detection of alpha particles in DAM–ADC nuclear track detector. Several important parameters that control the track formation such as, the bulk etch rate (VB), track etching rate (VT), dependence of VB and VT on etching concentration and temperature have been extensively studied. The activation energy (Eb) of the bulk etching rate for the DAM–ADC sheets has been calculated, the dependence of etching efficiency and sensitivity upon etchant concentrations and temperature has been investigated, registration efficiency of DAM–ADC detector etched at the optimum etching condition has been examined. The detailed studied results presented in this study provide various useful information about the mechanism of track formation in polymers. - Highlights: • Detection of alpha particles in DAM–ADC nuclear track detector. • The activation energy of the bulk etching rate for the DAM–ADC sheets. • The dependence of etching efficiency upon etchant concentrations • Registration efficiency of DAM–ADC detector

  15. An improved electrostatic integrating radon monitor with the CR-39 as alpha-particle detector

    International Nuclear Information System (INIS)

    In this study, based on the electrostatic integrating radon monitor (EIRM) developed by Iida et al., a new type of EIRM with the allyl glycol carbonate (CR-39) as alpha-particle detector was developed for outdoor radon measurements. Besides using the CR-39 to replace the cellulose nitrate film as alpha-particle detector, the electrode and the setting place of the CR-39 were also optimally designed based on the simulation results of the electric field and the detection efficiency. The calibration factor of the new EIRM was estimated to be 0.136±0.002 tracks cm-2 (Bq m-3 h)-1, with the lower detection limit of 0.6 Bq m-3 for a 2-month exposure. Furthermore, both the battery and the dry agent were also replaced to protect the environment. The results of intercomparison and field experiments showed that the performances of the new EIRM were much better than the original one. It suggests that the new type of ERIM is more suitable for large-scale and long-term outdoor radon surveys. (authors)

  16. Revisiting alpha decay-based near-light-speed particle propulsion.

    Science.gov (United States)

    Zhang, Wenwu; Liu, Zhen; Yang, Yang; Du, Shiyu

    2016-08-01

    Interplanet and interstellar travels require long-term propulsion of spacecrafts, whereas the conventional schemes of propulsion are limited by the velocity of the ejected mass. In this study, alpha particles released by nuclear decay are considered as a potential solution for long-time acceleration. The principle of near-light-speed particle propulsion (NcPP) was elucidated and the stopping and range of ions in matter (SRIM) was used to predict theoretical accelerations. The results show that NcPP by means of alpha decay is feasible for long-term spacecraft propulsion and posture adjustment in space. A practical NcPP sail can achieve a speed >150km/s and reach the brink of the solar system faster than a mass equivalent solar sail. Finally, to significantly improve the NcPP sail, the hypothesis of stimulated acceleration of nuclear decay (SAND) was proposed, which may shorten the travel time to Mars to within 20 days. PMID:27161512

  17. Project and construction of a spectrometer for alpha particles using surface barrier detectors

    International Nuclear Information System (INIS)

    The project, construction, tests and some applications of a system for alpha and beta spectrometry, using surface barrier detector are described. The device includes a solid state detector ORTEC-Series F coupled to a system for amplifying the charges produced by passage of an ionizing particle through the detector. The amplifying system is composed by a charge sensitive pre-amplifier, which employs an operational amplifier CA 3140, and a low noise linear amplifier, which is based on the operational amplifiers CA 3140 and LM 301. The pre-amplifier stage input impedance is on the order of TΩ and produces output pulses which heights are proportional to total charge produced by passage of particle through the detector sensitive volume. The main advantage to use charge sensitive system lies in obtention of independent pulse heights of the distributed capacity of connecting cable between the detector and the pre-amplifier. The total system amplification ca reach a maximum of 50.000 in the linear region. Pulses are analysed in a multichannel system ORTEC, model 6240. The amplifier system is easily constructed and low cost using components available in the national market, and it can be employed with ionization chambers, proportional counters, scitillation counters and semiconductor detectors. The results of spectrometer application for alpha spectrometry of AM241 source were compared to systems made with imported stages. (Author)

  18. Development of scintillator plates with high energy resolution for alpha particles made of GPS scintillator grains

    International Nuclear Information System (INIS)

    A scintillator plate with high energy resolution was developed to produce an alpha particle monitor used in nuclear fuel reprocessing plants and mixed plutonium-uranium oxide (MOX) fuel plants. Grains of a Gd2Si2O7 (GPS) scintillator of several 10 to 550 μm were fixed on a glass substrate and were then mechanically polished. By increasing the size of scintillator grains and removing fine powders, the collected light yield and energy resolution for alpha particles were drastically improved. Energy resolution of 9.3% was achieved using average grain size of 91 μm. Furthermore, the ratios between counts in a peak and total counts were improved by more than 60% by the further increase of grain size and adoption of mechanically polished surfaces on both sides. Beta and gamma ray influences were suppressed sufficiently by the thin 100 μm scintillator plates. -- Highlights: • A scintillator plate was fabricated using Gd2Si2O7 grains of several 10 to 550 μm. • Scintillator grains were fixed on a glass substrate and were mechanically polished. • Energy resolution of 9.3% was achieved using average grains size of 91 μm. • This technique has no limitation in area size. • Radiation background was eliminated by thin thickness of scintillator, i.e. 100 μm

  19. Activation cross sections of longer-lived radionuclides produced in germanium by alpha particle irradiation

    Science.gov (United States)

    Takács, S.; Takács, M. P.; Ditrói, F.; Aikawa, M.; Haba, H.; Komori, Y.

    2016-09-01

    The cross sections of alpha particles induced nuclear reactions on natural germanium were investigated by using the standard stacked foil target technique, the activation method and high resolution gamma spectrometry. Targets with thickness of about 1 μm were prepared from natural Ge by vacuum evaporation onto 25 μm thick polyimide (Kapton) backing foils. Stacks were composed of Kapton-Ge-Ge-Kapton sandwich target foils and additional titanium monitor foils with nominal thickness of 11 μm to monitor the beam parameters using the natTi(α,x)51Cr reaction. The irradiations were done with Eα = 20.7 and Eα = 51.25 MeV, Iα = 50 nA alpha particle beams for about 1 h. Direct or cumulative activation cross sections were determined for production of the 72,73,75Se, 71,72,74,76,78As, and 69Ge radionuclides. The obtained experimental cross sections were compared to the results of theoretical calculations taken from the TENDL data library based on the TALYS computer code. A comparison was made with available experimental data measured earlier. Thick target yields were deduced from the experimental cross sections and compared with the data published before.

  20. A new method for alpha-particle detection in a classroom experiment

    International Nuclear Information System (INIS)

    Complete text of publication follows. The World Year of Physics (WYP 2005) was a worldwide celebration of Physics and its importance in our everyday lives. In harmony with its aims, that is to raise the worldwide awareness of Physics and Physical Science, we introduced a novel lab work involving a new imaging and data evaluation method for alpha-particle detection, which can be easily implemented in a classroom environment. The target group of the experiments is mainly secondary school students (age between 16-18 years). Our aim is to motivate students to develop a better understanding of Physics, allowing them to experience for themselves something of its fascination. In order to increase their attractiveness, the experiments include using a CMOS video image sensor with a video output. The covering glass window of the sensor must be carefully removed in order to make it sensitive for alpha rays. The sensor is connected to a computer where the images are recorded as a short video clip. The recorded video is played back by frames. The resulted frames are then merged together into one image. On this image the student can count the number of spots, where each spot corresponds to a hit of an alpha particle. The experiment can also be visible on a TV screen even by a whole class, however the authors suggest implementing the following experiments as a practical work individually or in small groups. As students are familiar with modern information technology, we think that they will be highly motivated to make these experiments on their own. Acknowledgements. The development of the above experimental setup was funded by ATOMKI and it was presented to the interactive science centre 'Magic corner', Debrecen, Hungary at Christmas, 2005. (author)

  1. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    In this review radiation produced by the nuclear industry is placed into context with other sources of radiation in our world. Human health effects of radiation, derivation of standards and risk estimates are reviewed in this document. The implications of exposing the worker and the general population to radiation generated by nuclear power are assessed. Effects of radiation are also reviewed. Finally, gaps in our knowledge concerning radiation are identified and current research on biological effects, on environmental aspects, and on dosimetry of radiation within AECL and Canada is documented in this report. (author)

  2. Ab initio alpha-alpha scattering.

    Science.gov (United States)

    Elhatisari, Serdar; Lee, Dean; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A; Luu, Thomas; Meißner, Ulf-G

    2015-12-01

    Processes such as the scattering of alpha particles ((4)He), the triple-alpha reaction, and alpha capture play a major role in stellar nucleosynthesis. In particular, alpha capture on carbon determines the ratio of carbon to oxygen during helium burning, and affects subsequent carbon, neon, oxygen, and silicon burning stages. It also substantially affects models of thermonuclear type Ia supernovae, owing to carbon detonation in accreting carbon-oxygen white-dwarf stars. In these reactions, the accurate calculation of the elastic scattering of alpha particles and alpha-like nuclei--nuclei with even and equal numbers of protons and neutrons--is important for understanding background and resonant scattering contributions. First-principles calculations of processes involving alpha particles and alpha-like nuclei have so far been impractical, owing to the exponential growth of the number of computational operations with the number of particles. Here we describe an ab initio calculation of alpha-alpha scattering that uses lattice Monte Carlo simulations. We use lattice effective field theory to describe the low-energy interactions of protons and neutrons, and apply a technique called the 'adiabatic projection method' to reduce the eight-body system to a two-cluster system. We take advantage of the computational efficiency and the more favourable scaling with system size of auxiliary-field Monte Carlo simulations to compute an ab initio effective Hamiltonian for the two clusters. We find promising agreement between lattice results and experimental phase shifts for s-wave and d-wave scattering. The approximately quadratic scaling of computational operations with particle number suggests that it should be possible to compute alpha scattering and capture on carbon and oxygen in the near future. The methods described here can be applied to ultracold atomic few-body systems as well as to hadronic systems using lattice quantum chromodynamics to describe the interactions of

  3. Ab initio alpha-alpha scattering

    Science.gov (United States)

    Elhatisari, Serdar; Lee, Dean; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A.; Luu, Thomas; Meißner, Ulf-G.

    2015-12-01

    Processes such as the scattering of alpha particles (4He), the triple-alpha reaction, and alpha capture play a major role in stellar nucleosynthesis. In particular, alpha capture on carbon determines the ratio of carbon to oxygen during helium burning, and affects subsequent carbon, neon, oxygen, and silicon burning stages. It also substantially affects models of thermonuclear type Ia supernovae, owing to carbon detonation in accreting carbon-oxygen white-dwarf stars. In these reactions, the accurate calculation of the elastic scattering of alpha particles and alpha-like nuclei—nuclei with even and equal numbers of protons and neutrons—is important for understanding background and resonant scattering contributions. First-principles calculations of processes involving alpha particles and alpha-like nuclei have so far been impractical, owing to the exponential growth of the number of computational operations with the number of particles. Here we describe an ab initio calculation of alpha-alpha scattering that uses lattice Monte Carlo simulations. We use lattice effective field theory to describe the low-energy interactions of protons and neutrons, and apply a technique called the ‘adiabatic projection method’ to reduce the eight-body system to a two-cluster system. We take advantage of the computational efficiency and the more favourable scaling with system size of auxiliary-field Monte Carlo simulations to compute an ab initio effective Hamiltonian for the two clusters. We find promising agreement between lattice results and experimental phase shifts for s-wave and d-wave scattering. The approximately quadratic scaling of computational operations with particle number suggests that it should be possible to compute alpha scattering and capture on carbon and oxygen in the near future. The methods described here can be applied to ultracold atomic few-body systems as well as to hadronic systems using lattice quantum chromodynamics to describe the interactions of

  4. Effect of alpha1-blockers on stentless ureteroscopic lithotripsy

    Directory of Open Access Journals (Sweden)

    Jianguo Zhu

    2016-02-01

    Full Text Available ABSTRACT Objective To evaluate the clinical efficiency of alpha1-adrenergic antagonists on stentless ureteroscopic lithotripsy treating uncomplicated lower ureteral stones. Materials and Methods From January 2007 to January 2013, 84 patients who have uncomplicated lower ureteral stones treated by ureteroscopic intracorporeal lithotripsy with the holmium laser were analyzed. The patients were divided into two groups, group A (44 patients received indwelled double-J stents and group B (40 patients were treated by alpha1-adrenergic antagonists without stents. All cases of group B were treated with alpha1 blocker for 1 week. Results The mean operative time of group A was significantly longer than group B. The incidences of hematuria, flank/abdominal pain, frequency/urgency after surgery were statistically different between both groups. The stone-free rate of each group was 100%. Conclusions The effect of alpha1-adrenergic antagonists is more significant than indwelling stent after ureteroscopic lithotripsy in treating uncomplicated lower ureteral stones.

  5. Effective liquid drop description for alpha decay of atomic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, O.A.P.; Duarte, S.B. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Rodriguez, O.; Guzman, F. [Instituto Superior de Ciencia y Tecnologia Nuclear (ISCTN), La Habana (Cuba); Goncalves, M. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil); Garcia, F. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica

    1998-06-01

    Alpha decay half-lives are presented in the framework of an effective liquid drop model for different combination of mass transfer descriptions and inertia coefficients. Calculated half-life-values for ground-state to ground-state favoured alpha transitions are compared with available, updated experimental data. Results have shown that the present model is very suitable to treat the alpha decay process on equal foot as cluster radioactivity and cold fission processes. Better agreement with the data is found when the sub-set of even-even alpha emitters are considered in the calculation. (author) 44 refs., 5 figs., 3 tabs.; e-mail: telo at ird.gov.br

  6. Hazardous gas production by alpha particles in solid organic transuranic waste matrices. 1998 annual progress report

    International Nuclear Information System (INIS)

    'This project uses fundamental radiation chemical techniques to elucidate the basic processes occurring in the heavy-ion radiolysis of solid hydrocarbon matrices such as polymers and organic resins that are associated with many of the transuranic waste deposits or the transportation of these radionuclides. The environmental management of mixed waste containing transuranic radionuclides is difficult because these nuclides are alpha particle emitters and the energy deposited by the alpha particles causes chemical transformations in the matrices accompanying the waste. Most radiolysis programs focus on conventional radiation such as gamma rays, but the chemical changes induced by alpha particles and other heavy ions are typically very different and product yields can vary by more than an order of magnitude. The objective of this research is to measure the production of gases, especially molecular hydrogen, produced in the proton, helium ion, and carbon ion radiolysis of selected solid organic matrices in order to obtain fundamental mechanistic information on the radiolytic decomposition of these materials. This knowledge can also be used to directly give reasonable estimates of explosive or flammability hazards in the storage or transport of transuranic wastes in order to enhance the safety of DOE sites. This report summarizes the work after eight months of a three-year project on determining the production of hazardous gases in transuranic waste. The first stage of the project was to design and build an assembly to irradiate solid organic matrices using accelerated ion beams. It is necessary to measure absolute radiolytic yields, and simulate some of the conditions found in the field. A window assembly was constructed allowing the beam to pass consecutively through a collimator, a vacuum exit window and into the solid sample. The beam is stopped in the sample and the entire end of the assembly is a Faraday cup. Integration of the collected current, in conjunction

  7. Optical manipulation of biological particles using LP21 mode in fiber

    International Nuclear Information System (INIS)

    We demonstrate the optical manipulation of biological particles using a low-order LP21 fiber mode. The focused four-lobed LP21 mode distribution was theoretically and experimentally found to be effective in optical tweezer applications, including selective cellular pick-up, pairing, grouping or separation, as well as rotation of cell dimers and clusters. Our proposed theoretical model estimates both the translational dragging force and rotational torque in good accordance with experimental data. With a simple all-fiber configuration, and low peak irradiation to target bioparticles, the proposed LP21 ‘optical chuck’ system has great application potential in biological test systems. (paper)

  8. Quantum Effects in Biological Systems

    Science.gov (United States)

    Roy, Sisir

    2014-07-01

    The debates about the trivial and non-trivial effects in biological systems have drawn much attention during the last decade or so. What might these non-trivial sorts of quantum effects be? There is no consensus so far among the physicists and biologists regarding the meaning of "non-trivial quantum effects". However, there is no doubt about the implications of the challenging research into quantum effects relevant to biology such as coherent excitations of biomolecules and photosynthesis, quantum tunneling of protons, van der Waals forces, ultrafast dynamics through conical intersections, and phonon-assisted electron tunneling as the basis for our sense of smell, environment assisted transport of ions and entanglement in ion channels, role of quantum vacuum in consciousness. Several authors have discussed the non-trivial quantum effects and classified them into four broad categories: (a) Quantum life principle; (b) Quantum computing in the brain; (c) Quantum computing in genetics; and (d) Quantum consciousness. First, I will review the above developments. I will then discuss in detail the ion transport in the ion channel and the relevance of quantum theory in brain function. The ion transport in the ion channel plays a key role in information processing by the brain.

  9. Combustion synthesis and effects of processing parameters on physical properties of {alpha}-alumina

    Energy Technology Data Exchange (ETDEWEB)

    Collins, M.V.; Hirschfeld, D.A.; Shea, L.E.

    2000-01-04

    Fine particle porous {alpha}-alumina has been prepared by a wet chemical method of combustion synthesis using an aqueous precursor containing aluminum nitrate (oxidizer) and carbohydrazide, an organic fuel as starting materials. The aluminum nitrate and carbohydrazide were reacted exothermically at 400--600 C. The synthesis of {alpha}-alumina ({alpha}-Al{sub 2}O{sub 3}) was used as a model for understanding the effects of processing parameters on physical properties such as surface area, average pore size, and residual carbon content. The porous powders were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area analysis and elemental analysis. The decomposition of the starting materials was investigated using differential thermal and thermogravimetric analyses (DTA/TGA). It has been shown that the furnace temperature, fuel/oxidizer ratio, and precursor water content can be tailored to produce powders with different physical properties.

  10. Alpha process with biological elimination of nitrogen. Application of mathematical models; Proceso alpha con eliminacion biologica de nitrogeno. Aplicacion de modelos matematicos

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J. C.; Lopez-Carrasco, M. D.; Cortacans, J. A.; Larrea, L.; Larrea, A.

    1999-07-01

    This article illustrates the advantages of a step feed process for the biological elimination of nitrogen by presenting the experiments carried out by INFILCO at a pilot plant in San Sebastian. This arrangement, also known as the alpha (alternative phase step feed) process, reduces the volume of the biological reactor, eliminates the need for internal recycling and optimised the consumption of the organic matter used for denitrication. This article also demonstrates the possibility of employing a mathematical model as a tool in assessing, designing and operating full scale treatment plants for typically urban sewage. (Author) 6 refs.

  11. Coal fly ash- and copper smelter dust-induced modulation of ex vivo production of tumor necrosis factor-alpha by murine macrophages: effects of metals and overload

    Energy Technology Data Exchange (ETDEWEB)

    Broeckaert, F.; Buchet, J.P.; Delos, M.; Yager, J.W.; Lison, D. [Universite Catholique de Louvain, Brussels (Belgium). School of Public Health, Industrial Toxicology and Occupational Medicine Unit

    1999-03-12

    The paper assesses the effect of two arsenic-containing particles, coal fly ash (FA) and copper smelter dust (CU), on lung integrity and on the ex vivo release of tumor necrosis factor alpha (TNF-alpha) by alveolar phagocytes. The results show that coal fly ash and copper smelter dust bear distinct inflammatory properties. At the end of the observation period (d 120), the high CU dose produced a fibrotic reaction whereas the high dose of FA particles generated a delayed and persistent lung inflammatory reaction associated with lymphoid noduli. Marked differences in TNF-alpha production were observed within the CU and FA groups. CU particles, conceivably through their metal content, decreased TNF-alpha production by alveolar phagocytes. Due to their low arsenic content, considerably higher FA particle doses needed to be administered to produce an inhibition of TNF-alpha production.

  12. Deuterium effects in cancer biology

    International Nuclear Information System (INIS)

    Since its discovery many experiments were conducted for explaining the effects of deuterium on biological systems. It was observed, in many studies, that by increasing the deuterium concentration, structural, metabolic and functional alterations at different extents are produced, which can lead to organism's death. On the other hand effects of concentration reduction are much less studied. Existing data in literature, with regard to intrinsic deuterium reduction effects on different carcinomas are rather scarce. In vitro studies of deuterium level reduction has evidenced an inhibiting effect upon the cellular proliferation in different tumoral cellular lines: M14 cellular lines (human melanoma), PC3 (prostate cancer) and MCF7 (breast cancer). In vivo researches made on experimental tumours, have shown that the deuterium level reduction determines partial or complete regressions in xenotransplanted tumours, while in veterinary oncological clinic, partial or total tumoral regression were observed in different spontaneous tumours in dogs and cats. (authors)

  13. Effective particle magnetic moment of multi-core particles

    Energy Technology Data Exchange (ETDEWEB)

    Ahrentorp, Fredrik; Astalan, Andrea; Blomgren, Jakob; Jonasson, Christian [Acreo Swedish ICT AB, Arvid Hedvalls backe 4, SE-411 33 Göteborg (Sweden); Wetterskog, Erik; Svedlindh, Peter [Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Lak, Aidin; Ludwig, Frank [Institute of Electrical Measurement and Fundamental Electrical Engineering, TU Braunschweig, D‐38106 Braunschweig Germany (Germany); IJzendoorn, Leo J. van [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Westphal, Fritz; Grüttner, Cordula [Micromod Partikeltechnologie GmbH, D ‐18119 Rostock (Germany); Gehrke, Nicole [nanoPET Pharma GmbH, D ‐10115 Berlin Germany (Germany); Gustafsson, Stefan; Olsson, Eva [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Johansson, Christer, E-mail: christer.johansson@acreo.se [Acreo Swedish ICT AB, Arvid Hedvalls backe 4, SE-411 33 Göteborg (Sweden)

    2015-04-15

    In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems – BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm – and one single-core particle system – SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm.

  14. Effective particle magnetic moment of multi-core particles

    Science.gov (United States)

    Ahrentorp, Fredrik; Astalan, Andrea; Blomgren, Jakob; Jonasson, Christian; Wetterskog, Erik; Svedlindh, Peter; Lak, Aidin; Ludwig, Frank; van IJzendoorn, Leo J.; Westphal, Fritz; Grüttner, Cordula; Gehrke, Nicole; Gustafsson, Stefan; Olsson, Eva; Johansson, Christer

    2015-04-01

    In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems - BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm.

  15. Alpha radiation effects on weapons-grade plutonium encapsulating materials

    Science.gov (United States)

    Saglam, Mehmet

    The scientific understanding of material problems in the long-term storage of plutonium pits is investigated using experimental and theoretical models. The durability of the plutonium pit depends on the integrity of the metal cladding that encapsulates the plutonium. Given sufficient time, the energetic alpha particles (helium nuclei) produced by nuclear decay of the plutonium would degrade the mechanical strength of the metal cladding which could lead to cladding failure and dispersion of plutonium. It is shown that the long-term behavior of the encapsulating materials can be simulated by beam implantation and subsequent analysis using experimental techniques of Electron Microscopy and Neutron Depth Profiling (NDP). In addition computer simulations using the TRIM code were made in order to correlate the measurements to cladding damage. The Neutron Depth Profiling measurements done with samples that had 10 16 cm-2 3He beam implant dose showed no helium redistribution, indicating no microcracking between bubbles, for both beryllium and stainless steel, the pit cladding materials of interest. However, helium redistribution and significant helium loss were observed for samples with a beam implant dose of 1018 cm-2 , indicating microstructural damage. The SEM observations were consistent with the NDP measurements. The proper interpretation of the results rests on the realization that (i)the deleterious effects are related to helium concentration, not implant dose, and (ii)a specified maximum concentration of helium is achieved with a much smaller dose when monoenergetic ions are implanted using beam geometry than for the situation where Pu alphas stop in the pit cladding. Helium is distributed over a much smaller depth interval for beam implantation of monoenergetic ions as compared to the pit cladding implanted ions. Taking this effect into account and using the calculated pit implant dose gives a pit storage time for the 1016 cm-2 beam implant dose results equal to

  16. Bayesian analysis of nanodosimetric ionisation distributions due to alpha particles and protons.

    Science.gov (United States)

    De Nardo, L; Ferretti, A; Colautti, P; Grosswendt, B

    2011-02-01

    Track-nanodosimetry has the objective to investigate the stochastic aspect of ionisation events in particle tracks, by evaluating the probability distribution of the number of ionisations produced in a nanometric target volume positioned at distance d from a particle track. Such kind of measurements makes use of electron (or ion) gas detectors with detecting efficiencies non-uniformly distributed inside the target volume. This fact makes the reconstruction of true ionisation distributions, which correspond to an ideal efficiency of 100%, non-trivial. Bayesian unfolding has been applied to ionisation distributions produced by 5.4 MeV alpha particles and 20 MeV protons in cylindrical volumes of propane of 20 nm equivalent size, positioned at different impact parameters with respect to the primary beam. It will be shown that a Bayesian analysis performed by subdividing the target volume in sub-regions of different detection efficiencies is able to provide a good reconstruction of the true nanodosimetric ionisation distributions. PMID:21112893

  17. Particle entrapment as a feedback effect

    CERN Document Server

    Shklyaev, Sergey V

    2008-01-01

    We consider a suspension of polarizable particles under the action of traveling wave dielectrophoresis (DEP) and focus on particle induced effects. In a situation where the particles are driven by the DEP force, but no external forces are exerted on the fluid, the joint motion of the particles can induce a steady fluid flow, which leads to particle entrapment. This feedback effect is proven to be non-negligible even for small volume concentration of particles.

  18. Particle entrapment as a feedback effect

    OpenAIRE

    Shklyaev, Sergey V.; Straube, Arthur V.

    2007-01-01

    We consider a suspension of polarizable particles under the action of traveling wave dielectrophoresis (DEP) and focus on particle induced effects. In a situation where the particles are driven by the DEP force, but no external forces are exerted on the fluid, the joint motion of the particles can induce a steady fluid flow, which leads to particle entrapment. This feedback effect is proven to be non-negligible even for small volume concentration of particles.

  19. Biological effects of electromagnetic fields

    International Nuclear Information System (INIS)

    The effects of electromagnetic (em) fields on biological systems were first observed and exploited well over a century ago. Concern over the possible health hazards of human exposure to such fields developed much later. It is now well known that excessive exposure to em fields may have in undesirable biological consequences. Standards were introduced to determine what constitute an excessive exposure and how to avoid it. Current concern over the issue of hazards stems mainly from recent epidemiological studies of exposed populations and also from the results of laboratory experiments in which whole animals are exposed in vivo or tissue and cell cultures exposed in vitro to low levels of irradiation. The underlying fear is the possibility of a causal relationship between chronic exposure to low field levels and some forms of cancer. So far the evidence does not add up to a firm statement on the matter. At present it is not known how and at what level, if at all, can these exposure be harmful to human health. This state of affair does not provide a basis for incorporating the outcome of such research in exposure standards. This paper will give a brief overview of the research in this field and how it is evaluated for the purpose of producing scientifically based standards. The emphasis will be on the physical, biophysical and biological mechanisms implicated in the interaction between em fields and biological systems. Understanding such mechanisms leads not only to a more accurate evaluation of their health implications but also to their optimal utilization, under controlled conditions, in biomedical applications. (author)

  20. A synopsis of collective alpha effects and implications for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Sigmar, D.J.

    1990-10-01

    This paper discusses the following: Alpha Interaction with Toroidal Alfven Eigenmodes; Alpha Interaction with Ballooning Modes; Alpha Interaction with Fishbone Oscillations; and Implications for ITER.

  1. Partition of cross sections in asymmetric nucleus-nucleus reactions and the origin of fast alpha particles

    International Nuclear Information System (INIS)

    To investigate the mechanism of asymmetric nucleus-nucleus reactions from the Coulomb barrier to intermediate energies the 14N + 159Tb reaction was studied at five bombarding energies between 8 and 23 MeV/u via particle-particle correlations (at selected energies) and particle KX-ray coincidences to identify the specific reaction channels. With the KX-ray method partial cross sections for projectile-like fragments (PLF) as a function of the atomic number (Z/sub res/) of the residual nucleus can be determined. The charge balance yields the ''missing charge'' dZ = Z/sub proj/ + Z/sub targ/ - Z/sub PLF/ - Z/sub TLF/ that indicates whether, in addition to the PLF, other charged particles are emitted. A large fraction of the inclusive cross sections is found to originate from such channels with two or more fragments in the exit channel, and this fraction increases as the PLF is further removed in mass from the incident projectile, and with increasing bombarding energy. From the particle-particle correlation studies it is found that sequential decays of PLF's are dominant. ''Non-sequential'' processes, if present, are associated with inelastic reactions involving excitations of both projectile and target. The bulk of the large alpha-particle cross section at small angles is found to be associated with channels in which, in addition to the alpha particle, only nucleons and other alpha particles are emitted. From γ-ray multiplicity measurements and from the broad distribution of the strength with Z/sub res/ it is concluded that these alpha particles originate from inelastic (damped) processes. 27 refs., 10 figs

  2. Biological studies of radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, J.H.

    1949-11-16

    This paper discusses procedures for research on biological effects of radiation, using mouse tissue: activation trace analysis including methods and proceedures for handling samples before during and after irradiation; methods and procedures for ion exchange study; method of separation and recovery of copper, iron, zinc, cobalt, pubidium and cesium. Also included are studies of trace elements with radioactive isotopes: the distribution of cobalt 60, zinc 65, and copper 64 in the cytoplasm and nuclei of normal mice and those with tumors. 16 figs., 2 tabs.

  3. Low level radiation: biological effects

    International Nuclear Information System (INIS)

    It is imperative that physicians and scientists using radiations in health care delivery continue to assess the benefits derived, vs. potential risk, to patients and radiation workers being exposed to radiation in its various forms as part of our health delivery system. Insofar as possible we should assure our patients and ourselves that the benefits outweigh the potential hazards involved. Inferences as to the possible biological effects of low level radiation are generally based on extrapolations from those effects observed and measured following acute exposures to considerably higher doses of radiation. Thus, in order to shed light on the question of the possible biological effects of low level radiation, a wide variety of studies have been carried out using cells in culture and various species of plant and animal life. This manuscript makes reference to some of those studies with indications as to how and why the studies were done and the conclusions that might be drawn there from. In addition reference is made to the handling of this information by scientists, by environmentalists, and by the news media. Unfortunately, in many instances the public has been misled by what has been said and/or written. It is hoped that this presentation will provide an understandable and reasonable perspective on the various appropriate uses of radiation in our lives and how such uses do provide significant improvement in our health and in our quality of life

  4. Alpha effect due to buoyancy instability of a magnetic layer

    OpenAIRE

    Chatterjee, Piyali; Mitra, Dhrubaditya; Rheinhardt, Matthias; Brandenburg, Axel

    2010-01-01

    A strong toroidal field can exist in form of a magnetic layer in the overshoot region below the solar convection zone. This motivates a more detailed study of the magnetic buoyancy instability with rotation. We calculate the alpha effect due to helical motions caused by a disintegrating magnetic layer in a rotating density-stratified system with angular velocity Omega making an angle theta with the vertical. We also study the dependence of the alpha effect on theta and the strength of the ini...

  5. Poloidal drift enhancement for improved collisionless alpha particle confinement in stellarator configurations in the quasi-isodynamic category

    International Nuclear Information System (INIS)

    Poloidal closure of contours of the second adiabatic invariant has been reported to be an essential issue in the realization of good collisionless alpha particle confinement in stellarator configurations in the quasi-isodynamic category. This common feature is examined from a different aspect, that of the poloidal drift enhancement. This is realized by radial variation of the uniform magnetic field component with a diamagnetic effect for finite beta equilibria in the W7-X stellarator, which gives poloidal drift enhancement everywhere on a flux surface. On the other hand, the additional helicity introduced to the vacuum field in the quasi-isodynamic configuration can also enhance poloidal drift. The different methods for poloidal drift enhancement are clarified systematically on the basis of the magnetic field spectrum and the magnetic topography. (author)

  6. Properties of an $\\alpha$ particle in a Bohrium $270$ Nucleus under the Generalized Symmetric Woods-Saxon Potential

    CERN Document Server

    Lütfüoğlu, B C

    2016-01-01

    The energy eigenvalues and the wave functions of an $\\alpha$ particle in a Bohrium $270$ nucleus were calculated by solving Schr\\"odinger equation for Generalized Symmetric Woods-Saxon potential. Using the energy spectrum by excluding and including the quasi-bound eigenvalues, entropy, internal energy, Helmholtz energy, and specific heat, as functions of reduced temperature were calculated. Stability and emission characteristics are interpreted in terms of the wave and thermodynamic functions. The kinetic energy of a decayed $\\alpha$ particle was calculated using the quasi-bound states, which is found close to the experimental value.

  7. Internal dosimetry for alpha emitters radiopharmaceuticals in biological tissue studied with the FLUKA code 10

    International Nuclear Information System (INIS)

    Clinical practices for neoplastic disease diagnose and treatment are based on the incorporation of α, β and γ radiotracers and radiopharmaceuticals, which might be associated with potential damage. Thus, being necessary accurate dosimetry strategies. In vivo absorbed dose appears as an ideal solution. However, its implementation in clinics does not attain enough reliability. On the other hand, different approaches were proposed for internal dosimetry calculations. Some special analytical methodologies were developed by the Committee on Medical Internal Radiation Dose (MIRD) to assess organ level dose values in nuclear medicine. Improvements in informatics achieve better computation performance, but Monte Carlo approaches for patient-specific dosimetry are sometimes high time-consuming l imitating its use in routine clinical practices. Analytical approaches introduce kernel convolution techniques aimed to patient spe ci dosimetry. Although scattering effects are not accurately handled, these methods are capable of fast dosimetry computation based on photon Energy Deposition Kernel (EDK and particle Dose Point Kernel (DPK) assessed for radionuclides in order to perform further dosimetry calculations. EDK and DPK are obtained according to specific source emission. It was considered a point source isotropically emitting within an homogeneous medium, so that radiation transport is accounted as uniformly distributed over concentric spherical regions by shell tally. Dedicated Monte Carlo simulations were performed by a subroutine adapted from the FLUKA co se. In water EDK were evaluated at different photon energies and some typical γ-emitters radiopharmaceuticals; whereas DPK were obtained for both α and β emitters. Additionally, EDK and DPK were calculated for several biological tissues. Obtained results agree with energy loss from stopping power calculated by Bethe-Bark as- Bloch theory in the continuous slowing down approximation

  8. A route for polonium 210 production from alpha-particle irradiated bismuth-209 target

    International Nuclear Information System (INIS)

    A method is proposed for production of polonium-210 via the 209Bi(α,3n)210 At nuclear reaction. Bombardment of a bismuth-209 target was performed with a 37 MeV alpha-particle beam that leads to the production of astatine-210 (T1/2 = 8.1 h), which decays to polonium-210. It is purified from the bismuth target matrix by employing liquid-liquid extraction using tributyl phosphate (TBP) in para-xylene from 7 M hydrochloric acid. Back extraction of polonium-210 was performed by 9 M nitric acid. This method allows to purify a tracer amount of Po-210 (2.6 x 10-13 mol) from macroscopic amount of Bi (2.8 x 10-2 mol).

  9. Assessment of gamma, beta and alpha-particle-emitting nuclides in marine samples

    International Nuclear Information System (INIS)

    Depending on the physical properties of radionuclides different systems must be used for their measurement. Most convenient is if gamma spectrometry can be used by germanium, Silicon or Scintillation detectors (eg. NaI). If, however, the main emission consists of beta or alpha particles or low-energy photons as is the case for radionuclides decaying by electron capture, radiochemical separation and specific source preparations must be undertaken. In such cases also the radiochemical yield must be determined. The radiochemical part mainly follows the lines presented by prof. T. Jaakkola, Department of Radiochemistry, Helsinki, Finland, at a course in radioecology in Lurid, 1991. For very long-lived radionuclides other methods such as mass spectrometry are superior although often associated with sophisticated expensive instrumentation. (author)

  10. Ionization and scintillation response of high-pressure xenon gas to alpha particles

    CERN Document Server

    Álvarez, V; Cárcel, S; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Díaz, J; Egorov, M; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gehman, V M; Gil, A; Goldschmidt, A; Gómez, H; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Miller, T; Moiseenko, A; Monrabal, F; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot, M; Nygren, D; Oliveira, C A B; Palma, R; Pérez, J; Aparicio, J L Pérez; Renner, J; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; Segui, L; Serra, L; Shuman, D; Simón, A; Sofka, C; Sorel, M; Toledo, J F; Tomás, A; Torrent, J; Tsamalaidze, Z; Vázquez, D; Veloso, J F C A; Webb, R; White, J T; Yahlali, N

    2012-01-01

    High-pressure xenon gas is an attractive detection medium for a variety of applications in fundamental and applied physics. In this paper we study the transport properties of ionization electrons, and the mechanism of electron-ion recombination, in xenon gas at 10 bar pressure. For this purpose, we use a source of alpha particles in the NEXT-DEMO time projection chamber, the large scale prototype of the NEXT-100 neutrinoless double beta decay experiment, in three different drift electric field configurations. Our electron drift velocity and longitudinal diffusion results are similar to expectations based on available electron scattering cross sections on pure xenon, favoring low-diffusion models. In addition, two types of measurements addressing the connection between the ionization and scintillation yields were performed. On the one hand we observe, for the first time in xenon gas, large event-by-event correlated fluctuations between the ionization and scintillation signals, similarly to what has already bee...

  11. Is the first excited state of the $\\alpha$-particle a breathing mode?

    CERN Document Server

    Bacca, Sonia; Leidemann, Winfried; Orlandini, Giuseppina

    2014-01-01

    The isoscalar monopole excitation of 4He is studied within a few-body ab initio approach. We consider the transition density to the low-lying and narrow 0+ resonance, as well as various sum rules and the strength energy distribution itself at different momentum transfers q. Realistic nuclear forces of chiral and phenomenological nature are employed. Various indications for a collective breathing mode are found: i) the specific shape of the transition density, ii) the high degree of exhaustion of the non-energy-weighted sum rule at low q and iii) the complete dominance of the resonance peak in the excitation spectrum. For the incompressibility K of the alpha-particle values between 20 and 30 MeV are found.

  12. Specific features of reactor or cyclotron {alpha}-particles irradiated beryllium microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Khomutov, A.M. [A.A.Bochvar All-Russia Research Inst. of Inorganic Materials (VNIINM), Moscow (Russian Federation); Gromov, B.F.; Karabanov, V.N. [and others

    1998-01-01

    Studies were carried out into microstructure changes accompanying helium swelling of Be reactor neutron irradiated at 450degC or {alpha}-particles implanted in cyclotron to reach the same volume accumulation of He (6-8 ncm{sup 3} He/cm{sup 3} Be). The microstructures of reactor irradiated and implanted samples were compared after vacuum anneal at 600-800degC up to 50h. The irradiated samples revealed the etchability along the grain boundaries in zones formed by adequately large equilibrium helium pores. The width of the zones increased with the annealing time and after 50h reached 30{mu}. Depleted areas 2-3{mu} dia were observed in some regions of near grain boundary zones. The roles of grain boundaries and manufacturing pores as vacancies` sources and helium sinks are considered. (author)

  13. CO2 laser collective Thomson scattering for alpha-particle diagnostics

    International Nuclear Information System (INIS)

    In JT-60U (JAEA Tokamak 60 - Upgrade), a collective Thomson scattering (CTS) technique based on a CO2 laser is being developed in order to establish a diagnostic method of confined alpha-particles in burning plasmas. In order to the demonstrate feasibility of the CTS system, a new laser systems is being developed, with which improved signal-to-Noise (S/N) ratio of a detection signal and temporal resolution will be obtained. The laser has cavity length of ∼4 m and has high repetition rate (10 Hz). To improve the spectral purity of the laser, cavity length will be feedback-controlled and a spectral filter will be installed in the output of the laser. Numerical calculation shows that ion temperature will be evaluated from the scattered spectrum with the new CO2 laser. (author)

  14. Traversal of cells by radiation and absorbed fraction estimates for electrons and alpha particles

    International Nuclear Information System (INIS)

    Consideration of the pathlength which radiation traverses in a cell is central to algorithms for estimating energy deposition on a cellular level. Distinct pathlength distributions occur for radionuclides: (1) uniformly distributed in space about the cell (referred to as μ-randomness); (2) uniformly distributed on the surface of the cell (S-randomness); and (3) uniformly distributed within the cell volume (I-randomness). For a spherical cell of diameter d, the mean pathlengths are 2/3d, and 3/4d, respectively, for these distributions. Algorithms for simulating the path of radiation through a cell are presented and the absorbed fraction in the cell and its nucleus are tabulated for low energy electrons and alpha particles emitted on the surface of spherical cells. The algorithms and absorbed fraction data should be of interest to those concerned with the dosimetry of radionuclide-labeled monoclonal antibodies. 8 references, 3 figures, 2 tables

  15. Long-Range Alpha Particle Emission in the Fission of U235 by 3-MeV Neutrons

    International Nuclear Information System (INIS)

    The energy and angular distribution of long-range alpha particles emitted in the fission of U235 induced by 3-MeV neutrons have been measured. The alpha panicles were detected by solid-state detector and the fission fragments were detected by a gas scintillation counter. The neutrons were produced by the T (p, n) He3 reaction using a 5.5- MeV Van de Graaff accelerator. About 3000 fission events accompanied by the emission of a high-energy alpha panicle were recorded. The most probable energy of the alpha particles is between 15-16 MeV. and the energy distribution has a full width at half maximum of about D MeV, which is the same as observed in tliermal- neutron fission. The angular distribution of the long-range alpha panicles with respect to the incident neutron direction was found to be forward-peaked, in agreement with previous work on alpha emission in 14-MeV neutron-induced fission of LP. At angles of 0° and 90° with respect to the incident neutron direction the alpha panicles were detected with an angular spread of about ± 25°. The anisotropy [Nα(0°)/ Nα(90°)] was found to be 1.320 ± 0.12. This value is in agreement with the anisotropy calculated on the basis of statistical evaporation of panicles. The results of the present investigation are consistent with the hypothesis that the emission of long-range alpha panicles in fission is an evaporation process. The implications of the results of this work and of other recent investigations on long-range alpha emission are discussed. (author)

  16. The CRRES/SPACERAD heavy ion model of the environment (CHIME) for cosmic ray and solar particle effects on electronic and biological systems in space

    International Nuclear Information System (INIS)

    Accurate estimates of the frequency of single event effects require accurate models of the fluxes of heavy ions which cause them. These flux models must account for the multifarious temporal variations of ion flux intensity, and their significant energy- and species-dependencies. The authors present a new time-dependent model of the interplanetary heavy ion environment and a new set of software based on this model to calculate energy deposit (LET) spectra and resulting single event upset rates

  17. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    It has been emphasised the importance of DNA as the main target for ionizing radiation, that can induce damage by its direct action on this molecule or by an indirect effect mediated by free-radicals generated by water radiolysis. Biological effects of ionizing radiation are influenced not only by the dose but also by the dose-rate and the radiation quality. Radiation induced damage, mainly DNA single and double strand breaks, is detected by molecular sensors which in turn trigger signalling cascades leading to cell cycle arrest to allow DNA repair or programmed cell death (apoptosis). Those effects related with cell death, named deterministic, exhibits a dose-threshold below which they are not observed. Acute radiation syndrome and radiological burns are examples of this kind of effects. Other radiation induced effects, called stochastic, are the consequence of cell transformation and do not exhibit a dose-threshold. This is the case of cancer induction and hereditary effects. The aim of this presentation is briefly describe the main aspects of deterministic and stochastic effects from the point of view of radiobiology and radio pathology. (author)

  18. New features of nuclear excitation by {alpha} particles scattering; Nouveaux aspects de l'excitation nucleaire par diffusion de particules {alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Saudinos, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    Inelastic scattering of medium energy a particles by nuclei is known to excite preferentially levels of collective character. We have studied the scattering of isotopically enriched targets of Ca, Fe, Ni, Cu, Zn. In part I, we discuss the theoretical features of the interaction. In part II, we describe the experimental procedure. Results are presented and analysed in part III. {alpha} particles scattering by Ca{sup 40} is showed to excite preferentially odd parity levels. In odd nuclei we have observed multiplets due to the coupling of the odd nucleon with the even-even core vibrations. For even-even nuclei, a few levels are excited with lower cross-sections between the well-known first 2{sup +} and 3{sup -} states. Some could be members of the two phonon quadrupole excitation and involve a double nuclear excitation process. (author) [French] On sait que la diffusion inelastique des particules alpha de moyenne energie excite preferentiellement des niveaux de caractere collectif. Nous avons etudie la diffusion des particules alpha de 44 MeV du cyclotron de Saclay par des isotopes separes de Ca, Fe, Ni, Cu, Zn. Dans la premiere partie nous exposons les theories de cette interaction. Dans la seconde nous decrivons le systeme experimental. Les resultats sont donnes dans la troisieme partie. Nous montrons que les niveaux excites preferentiellement pour {sup 40}Ca par diffusion ({alpha},{alpha}') sont de parite negative. Dans les noyaux pair-impair nous avons observe des multiplets dus au couplage du nucleon celibataire avec les vibrations du coeur pair-pair. Pour les noyaux pair-pair nous avons pu etudier entre le premier niveau 2{sup +} et le niveau 3{sup -} deja bien connus certains etats plus faiblement excites. Il semble qu'ils sont dus a une excitation quadrupolaire a deux phonons et impliquent un processus de double excitation nucleaire. (auteur)

  19. Effect of chemicals on fungal alpha-amylase activity.

    Science.gov (United States)

    Ali, F S; Abdel-Moneim, A A

    1989-01-01

    The effect of 8 growth regulators at concentrations of 1,000, 5,000 and 10,000 ppm on the activity of fungal (Aspergillus flavus var. columnaris) alpha-amylase was studied. Indol acetic acid (IAA) and naphthalene acetic acid (NAA) inhibited alpha-amylase activity by 2% and 7% at 1,000 ppm. The other 6 growth regulators, indol butyric acid (IBA), gibberellic acid, cumarin, cycocel (CCC), atonik-G and kylar, did not inhibit but stimulated alpha-amylase activity (0 to 9%) at 1,000 ppm. All growth regulators studied inhibited alpha-amylase activity at 5,000 and 10,000 ppm concentration except kylar. The effect of organic acids and formaldehyde at 0.01, 0.005, and 0.001 M was studied. Acetic acid stimulated alpha-amylase at all concentrations, but formic acid, oxalic acid, lactic acid and citric acid inhibited alpha-amylase activity by 91, 100, 100 and 79%, respectively, at a concentration of 0.01 M, while by 31, 100, 15 and 20%, respectively, at 0.005 M. Formaldehyde induced 7, 3 and 2% inhibition at 0.01, 0.005 and 0.001 M, respectively. At 0.01 M either sorbitol or fructose inhibited alpha-amylase by 8%, Maltose 7%, sucrose 6%, phenol, glucose and galactose each by 5%, ethanol, glycerol, arabinose and sodium benzoate each by 4%, isopropanol and mannitol 1%, but methanol and ammonium citrate dibasic did not inhibit alpha-amylase. The results indicate that CuCl2, SnCl2, AgNO3 and Fe2(SO4)3 were the strongest inhibitors, followed by Cd(C2H3O2), HgCl2, Na2-EDTA, Na2HPO4, and CaCl2 in decreasing order. NaCl, NaBr and Mn SO4 did not inhibit alpha-amylase at concentrations from 10 mM to 0.01 mM. PMID:2515680

  20. Biological effects of space radiation and development of effective countermeasures

    Science.gov (United States)

    Kennedy, Ann R.

    2014-04-01

    As part of a program to assess the adverse biological effects expected from astronauts' exposure to space radiation, numerous different biological effects relating to astronauts' health have been evaluated. There has been major focus recently on the assessment of risks related to exposure to solar particle event (SPE) radiation. The effects related to various types of space radiation exposure that have been evaluated are: gene expression changes (primarily associated with programmed cell death and extracellular matrix (ECM) remodeling), oxidative stress, gastrointestinal tract bacterial translocation and immune system activation, peripheral hematopoietic cell counts, emesis, blood coagulation, skin, behavior/fatigue (including social exploration, submaximal exercise treadmill and spontaneous locomotor activity), heart functions, alterations in biological endpoints related to astronauts' vision problems (lumbar puncture/intracranial pressure, ocular ultrasound and histopathology studies), and survival, as well as long-term effects such as cancer and cataract development. A number of different countermeasures have been identified that can potentially mitigate or prevent the adverse biological effects resulting from exposure to space radiation.

  1. Biological Insights from Single-Particle Tracking in Living Cells

    OpenAIRE

    Sanamrad, Arash

    2014-01-01

    Single-particle tracking is a technique that allows for quantitative analysis of the localization and movement of particles. In this technique, trajectories are constructed by determining and connecting the positions of individual particles from consecutive images. Recent advances have made it possible to track hundreds of particles in an individual cell by labeling the particles of interest with photoactivatable or photoconvertible fluorescent proteins and tracking one or a few at a time. Si...

  2. Angular and velocity distributions of secondary particles emitted in interaction of 3. 6-GeV/nucleon. cap alpha. particles and lead nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Antonenko, V.G.; Vinogradov, A.A.; Galitskii, V.M.; Grigor' yan, Y.I.; Ippolitov, M.S.; Karadzhev, K.V.; Kuz' min, E.A.; Man' ko, V.I.; Ogloblin, A.A.; Paramonov, V.V.; Tsvetkov, A.A.

    1980-04-01

    The technique is described and results presented of measurements of the velocity and angular distributions of pions, protons, and deuterons, and tritons emitted in bombardment of lead nuclei by ..cap alpha.. particles with energy 3.6 GeV/nucleon.

  3. The alpha effectiveness of the dating ESR signal in barite

    International Nuclear Information System (INIS)

    The alpha effectiveness was investigated for an ESR signal due to SO3− in barite by comparing the dose responses of the signal for gamma irradiation and for He ion implantation with an energy of 4 MeV. The value was obtained to be 0.043 ± 0.018 for samples from Morocco and to be 0.0089 ± 0.0006 for Kanehira Mine. The dose response for He ion implantation for the latter sample better fits to a correlation line but the signal shape changes with gamma ray dose, indicating contribution from an unknown radiation sensitive signal, while the former sample shows the same signal shapes. A value of 0.043 ± 0.018 is adopted as the alpha effectiveness of SO3− signal in barite, which is used for ESR dating of submarine hydrothermal activity. - Highlights: ► The alpha effectiveness is one of the essential factors in ESR dating. ► The alpha effectiveness value was determined for barite. ► The dose responses for gamma and for He ion implantation were compared. ► A sample shows signal shape change by gamma ray irradiation.

  4. Damage radiation alpha effects in sintered waste form

    International Nuclear Information System (INIS)

    We have subjected the borosilicate glass to thermal neutron irradiation in a reactor, with an accumulated fluence equivalent to approximately E3, E4, E5, y E6 years of waste disposal. We considered the following potential effects of accumulated alpha decay: a) Changes in the density; b) Changes in the dissolution rates; c) Changes in the microstructure of the sintered glass. (author)

  5. Biological effect of fast neutrons

    International Nuclear Information System (INIS)

    The efficiency of fast neutrons of the energy range from 1.7 to 5 MeV in reducing the reticulocyte count and in diminishing the spleen weight was studied in male NMRI mice and compared with the effects of 250 kV X-rays. The neutron induced decrease of reticulocyte number in the peripheral blood is complete two days after irradiation. At this time even low doses cause a maximal effect. The relation between the rise of effect and the increase of exposure is great in the range of low doses and small in high doses. The relative biological effectiveness of neutrons in reducing the reticulocyte count is 2.5 after low doses and 1.2 after high doses. The spleen of irradiated mice shows a marked loss of weight, the lowest weight values are observed at the second day after irradiation. The relative effectiveness of neutrons in diminishing the spleen weight is 2.1 at low doses, the RBE decreases to 1.4 and rises again to 1.9 at higher doses. These results are compared with previous findings on mortality response and leucocyte and lymphocyte decrease in mice after neutron irradiation. Reticulocyte and lymphocyte count are found to be useful indicators for the detection and evaluation of neutron damage in the sublethal dose range. (orig.)

  6. Registration probability of alphas in cellulose nitrate

    International Nuclear Information System (INIS)

    Registration 'thresholds' of alpha particles in cellulose nitrate plastic present a statistical behaviour. The effect depends on etching conditions. It is particularly large in strong etching conditions, in which registration is transposed to high energies: up to 7.7 MeV for the conditions and energies studied. 'Registration probability' expresses more adequately the effect of registration constraints. The study of registration probability indicates that the 'target theory' can describe the effect. The parameters of target theory, m (number of targets) and D0 (the equivalent of biological dose D37) were found to be: m = 5 and D0 = 3 x 107 erg cm-3. Dose distribution around the trajectory of alphas of various energies is estimated. It is also deduced that track development takes place when the required dose for registration is deposited at a distance r >= 20 A from particle trajectory. (author)

  7. Astrophysics and particle physics in space with the Alpha Magnetic Spectrometer

    CERN Document Server

    Lamanna, G

    2003-01-01

    The Alpha Magnetic Spectrometer is a high energy particle physics experiment in space scheduled to be installed on the International Space Station (ISS) by 2006 for a three-year mission. After a precursor flight of a prototype detector on board of the NASA Space Shuttle in June 1998, the construction of the detector in its final configuration is started and it will be completed by 2004. The purpose of this experiment is to provide a high statistics measurement of charged particles and nuclei in rigidity range 0.5 GV to few TV and to explore the high-energy (>1 GeV) gamma-ray sky. In this paper we describe the detector layout and present an overview of the main scientific goals both in the domain of astrophysics: cosmic- ray origin, age and propagation and the exploration of the most energetic gamma-ray sources; and in the domain of astroparticle: the antimatter and the dark matter searches. (53 refs).

  8. Design of a preamplifier for an alpha particles spectrometer; Diseno de un preamplificador para un espectrometro de particulas alfa

    Energy Technology Data Exchange (ETDEWEB)

    Murillo O, R.; Hernandez D, V. M.; Chacon R, A.; Vega C, H. R., E-mail: fermineutron@yahoo.co [Universidad Autonoma de Zacatecas, Unidades Academicas de Estudios Nucleares e Ingenieria Electrica, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2010-09-15

    To detect radiation diverse detector types are used, when these are alpha particles proportional type detectors are used, semiconductor, of scintillation or traces. In this work the design results, the construction and the first tests of a spectrometer (preamplifier) are presented for alpha particles that was designed starting from a Pin type photodiode. The system was designed and simulated with a program for electronic circuits. With the results of the simulation phase was constructed the electronics that is coupled to a spectroscopic amplifier and a multichannel analyzer. The total of the system is evaluated analyzing its performance before a triple source of alphas and that they are produced by two smoke detectors of domestic use. Of the tests phase we find that the system allows to obtain in a multichannel, the pulses height spectrum, with which we calibrate the system. (Author)

  9. Production and immobilization of alpha amylase using biotechnology techniques for use in biological and medical applications

    International Nuclear Information System (INIS)

    The immobilized enzymes on polymeric supports are prepared for purpose of repeated use and the possibilities of continuous reaction system. One of the most important properties is the stability of proteins when they are used in some medical and industrial applications. The immobilization of the enzymes improves this property as well as many other properties.In this study, alpha amylase was purified and immobilized onto two different polymers. α- amylase was used in this study for its biological and industrial applications. It is used in paper textile, pharmaceutical applications, food, and detergent industries. α- amylase was found in plants, animals, and microorganisms. Purification of α-amylase from microorganisms is the main source of α-amylase because it was excreted from many bacteria and fungi. In this study, α-amylase was purified from Aspergillus niger. Fractional precipitation of the α- amylase produced by A. niger with 80% ammonium sulphate saturation. The crude enzyme was applied on column chromatography packed with Sephadex G 100 for purification. The active eluents containing partially purified enzyme were collected for further investigation. The specific activity of α-amylase was (34.9 U/mg) which was corresponding to 2.09 fold purification for the tested organism. The purified α-amylase was immobilized by entrapment method into two types of polymers. One of them was natural consist of chitosan and alginate. The other polymer was synthetic consist of N- isopropyl acrylamide and alginate. The temperature optimum and thermal inactivation showed a severe loss in the activity of the free enzymes, while the temperature profile of the immobilized enzymes was much broader at higher temperatures demonstrating the effectiveness of the polymer protecting the enzymes. Also, the immobilized enzymes (natural polymer and synthetic polymer) showed higher thermal stability. Optimum ph and stability showed that immobilization of enzymes resulted in more

  10. Biological Effects after Prenatal Irradiation

    International Nuclear Information System (INIS)

    A Task Group of the International Commission on Radiological Protection (ICRP) has finished a report Biological Effects after Prenatal Irradiation (Embryo and Fetus) which has been approved by the Main Commission and Will be Published. Some new important scientific data shall be discussed in this contribution. During the preimplantation period lethality of the mammalian embryo is the dominating radiation effect. However, in mouse strains with genetic predispositions it has been shown that also malformations can be caused. This effect is genetically determined and its mechanisms is different from the induction of malformations during major organogenesis. Radiation exposures during this prenatal period leads ato an increase of genomic instability of cells in the normal appearing fetuses. These radiation effects can be transmitted to the next generation. A renewed analysis of individuals with severe mental retardation after exposures during the 8th to 15th week post conception in Hiroshima and Nagasaki gives evidence that a threshold dose exists for this effect around 300 mGy. This is supported by a number of experimental animal data which have been obtained from cellular and molecular investigations during the brain development. The data show the high radiosensitivity of the developing brain but also the various compensatory mechanisms and the enormous plasticity of these processes. The radiosensitivity varies strongly during the prenatal development. The highest sensitivity is found during the early and mid fetal period which is coinciding with weeks 8-15 post conception in humans. The lowest doses causing persistent damage are in the range of 100 to 300 mGy. For intelligence quotient scores a linear dose response model provides a satisfactory fit. From the experimental data it can be concluded that the fetal stage is most sensitive to the carcinogenic effect in comparison to the other prenatal stages. Such as clear situation cannot be obtained from the

  11. Proton and alpha-particle capture reactions at sub-Coulomb energies relevant to the p process

    Energy Technology Data Exchange (ETDEWEB)

    Harissopulos, S [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Lagoyannis, A [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Spyrou, A [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Zarkadas, Ch [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Galanopoulos, S [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Perdikakis, G [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Becker, H-W [Dynamitron-Tandem-Laboratorium, Ruhr Universitaet Bochum, 44801 Bochum (Germany); Rolfs, C [Institut fuer Physik mit Ionenstrahlen, EP-II, Ruhr-Universitaet BochumI, 44801 Bochum (Germany); Strieder, F [Institut fuer Physik mit Ionenstrahlen, EP-II, Ruhr-Universitaet BochumI, 44801 Bochum (Germany); Kunz, R [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Fey, M [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Hammer, J W [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Dewald, A [Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Cologne (Germany); Zell, K-O [Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Cologne (Germany); Brentano, P von [Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Cologne (Germany); Julin, R [Department of Physics, University of Jyvaeskylae, 40014 Jyvaeskylae (Finland); Demetriou, P [Institut d' Astronomie et d' Astrophysique, Universite Libre de Bruxelles, CP226, 1050 Brussels (Belgium)

    2005-10-01

    Several cross-section measurements of proton as well as {alpha}-particle capture reactions in the Se-Sb region have been carried out at sub-Coulomb energies with the aim to obtain global input parameters for Hauser-Feshbach (HF) calculations. Some of the results are compared with HF calculations using various optical model potentials and nuclear level densities.

  12. AVERAGE REACTION CROSS-SECTIONS FOR 74-MEV TO 112-MEV ALPHA-PARTICLES ON I-127 AND CS-133

    NARCIS (Netherlands)

    WARNER, RE; WILSCHUT, HW; RULLA, WF; FELDER, GN

    1991-01-01

    The average reaction cross section for 74- to 112-MeV alpha particles on I-127 and Cs-133 was measured by a new method using a magnetic spectrograph and a CsI scintillation detector. The result, sigma-R = 2220+/-50 mb, is in good agreement with optical model calculations and finite-range microscopic

  13. Hauser-Feshbach cross-section calculations for elastic and inelastic scattering of alpha particles-program CORA

    International Nuclear Information System (INIS)

    The program CORA was prepared on the basis of Hauser and Feshbach compound reaction formalism. It allows the differential cross-section distributions for the elastic and inelastic scattering of alpha particles (via compound nucleus state) to be calculated. The transmission coefficients are calculated on the basis of a four parameter optical model. The search procedure is also included. (author)

  14. Biological radiation dose from secondary particles in a Milky Way gamma ray burst

    CERN Document Server

    Atri, Dimitra; Karam, Andrew

    2013-01-01

    Gamma ray bursts (GBRs) are a class of highly energetic explosions emitting radiation in a very short timescale of a few seconds and with a very narrow opening angle. Although, all GRBs observed so far are extragalactic in origin, there is a high probability of a GRB of galactic origin beaming towards the Earth in the past ~ 0.5 Gyr. Such an intense burst of gamma rays would ionize the atmosphere and deplete the ozone layer. With depleted ozone, there will be an increased flux of solar UVB on the Earth\\~Os surface with harmful biological effects. In addition to the atmospheric damage, secondary particles produced by gamma ray-induced showers will reach the surface. Amongst all secondary particles, muons dominate the ground-level secondary particle flux (99% of the total number of particles) and are potentially of biological significance. Using the Monte Carlo simulation code CORSIKA, we modeled the air showers produced by gamma ray primaries up to 100 GeV. We found that the number of muons produced by hypothe...

  15. Annealing effects on the charged particles registration characteristic of the CR-39 traces solid detector

    International Nuclear Information System (INIS)

    CR-39 trace solid detectors samples, previously exposed to alpha particles and fission fragments from a Cf-252 source, were submitted to a annealing treatment to study his effects on the characteristics of charged particle traces registration. (L.C.J.A.)

  16. Effects of charged particles on DNA

    International Nuclear Information System (INIS)

    It can be noted that it is not simple double strand breaks (dsb) but the non-reparable breaks that are associated with high biological effectiveness in the cell killing effect for high LET radiation. Here, we have examined the effectiveness of fast neutrons and low (initial energy = 12 MeV/u) or high (135 MeV/u) energy charged particles on cell death in 19 mammalian cell lines including radiosensitive mutants. Some of the radiosensitive lines were deficient in DNA dsb repair such as LX830, M10, V3, and L5178Y-S cells and showed lower values of relative biological effectiveness (RBE) for fast neutrons if compared with their parent cell lines. The other lines of human ataxia-telangiectasia fibroblasts, irs 1, irs 2, irs 3 and irs 1SF cells, which were also radiosensitive but known as proficient in dsb repair, showed moderate RBEs. Dsb repair deficient mutants showed low RBE values for heavy ions. These experimental findings suggest that the DNA repair system does not play a major role against the attack of high linear energy transfer (LET) radiations. Therefore, we hypothesize that a main cause of cell death induced by high LET radiations is due to non-reparable dsb, which are produced at a higher rate compared to low LET radiations. (author)

  17. Third workshop on heavy charged particles in biology and medicine

    International Nuclear Information System (INIS)

    The book of abstracts contains 67 papers presented at the workshop. Main topics are: Physics, chemistry, DNA, cell biology, cellular and molecular repair, space biology, tumor and tissue biology, predictive assays, cancer therapy, and new projects. Separate entries in the database are prepared for all of these papers. (MG)

  18. Influences of target geometry on the microdosimetry of alpha particles in water

    International Nuclear Information System (INIS)

    Application of microdosimetric concepts to radiation exposure situations requires knowledge of the single-event density function, f1 (z) , where z denotes specific energy imparted to target matter. Multiple-event density functions are calculated by taking convolutions of f1(z) with itself with the overall specific energy density function is then found by employing a compound Poisson process involving single and multiple-event spectra. The fl(z), depends strongly on the geometric details of a the source, target, and all intermediate matter. While most past applications of microdosimetry have been represented targets as spheres, may be better modeled as prolate or oblate spheroids. Using a ray-tracing technique coupled with a continuous-slowing-down approximation, methods are developed and presented for calculating single-event density functions for spheroidal targets irradiated by alpha-emitting point sources. Computational methods are incorporated into a fortran computer code entitled SEROID (single-event density functions for spheroids), which is listed in this paper. This was used to generate several single-event density functions, along with related means and standard deviations in specific energy, for spheroidal targets irradiated by alpha particles. Targets of varying shapes and orientations are examined. Results for non-spherical targets are compared to spherical targets of equal volume in order to assess influences which target geometry has on single-event quantities. From these comparisons it is found that both target shape and orientation are important in adequately characterizing the quantities examined in this study; over-simplifying the target geometry can lead to substantial error

  19. Tolerance and antiviral effects of high-dose interferon-alpha B/D in patients with chronic hepatitis B

    NARCIS (Netherlands)

    Rasch, MC; Schellekens, H; van Dijck, CMM; Haagsma, EB; Michielsen, PP; van Buuren, AHJAM; Stotter, H; van Hattum, J

    1998-01-01

    A novel recombinant interferon-alpha B/D hybrid was applied to assess tolerability, antiviral effect, and biological activity in chronic hepatitis B. The study was designed as an open nonrandomized trial. Treatment comprised a two-week run-in phase with 16 MU three times a week followed by 14 weeks

  20. Probability of bystander effect per mSv induced by α-particle radiation

    International Nuclear Information System (INIS)

    Radiation-induced bystander effect represents a paradigm shift in our understanding of the radiobiological effects of ionizing radiation in sense that they may also contribute to the final biological consequences of exposure to low doses of radiation. There exist the need to include the influence of the bystander effect in dosimetry of the human lung. The purpose of this work is to calculate the probability of bystander effect per one mSv, induced by α-particle radiation on sensitive cells of human lung. In this aim, a analytical model of cylinder bifurcation was created to simulate the geometry of human lung, with the distribution of cell in the airway wall of the tracheobronchial tree. This analytical model of the human tracheobronchial tree represents the extension of the ICRP66 model. Propagation of α-particle in human lung and airway tubes was simulated by Monte Carlo method. Calculations have been performed for the various source-target combinations. The results are given for two initial alpha particle energies (6 and 7.69 MeV) and two existing sources (fast and slow clearing mucus). (author)