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Sample records for alpha particle induced

  1. 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)

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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)

  7. 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...

  8. 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)

  9. Alpha particle induced gamma yields in uranium hexafluoride

    Science.gov (United States)

    Croft, Stephen; Swinhoe, Martyn T.; Miller, Karen A.

    2013-01-01

    Fluorine has a relatively large (α,n) production cross-section in the MeV range, the energy range of interest for special nuclear materials. In the uranium fuel cycle enriched UF6 in particular is a reasonably prolific source of (α,n) neutrons because along with 235U, 234U becomes enriched and it has a relatively short half-life. This enables the mass content of storage cylinders containing UF6 to be verified by neutron counting methods. In association with such measurements high resolution gamma-ray spectrometry (HRGS) measurements using a high-purity Ge detector are often undertaken to determine the 235U enrichment based off the intensity of the direct 186 keV line. The specific (α,n) neutron production, neutrons per second per gram of U, is sensitive to the relative isotopic composition, particularly the 234U concentration, and the traditional gross neutron counting approach is needed to quantitatively interpret the data. In addition to F(α,n) neutrons, α-induced reaction γ-rays are generated, notably at 110, 197, 582, 891, 1236 and 1275 keV. If one could observe 19F(α,xγ) gamma-lines in the HRGS spectra the thought was that perhaps the α-activity could be estimated directly, and in turn the 234U abundance obtained. For example, by utilizing the ratio of the detected 197-186 keV full energy peaks. However, until now there has been no readily available estimate of the expected strength of the reaction gamma-rays nor any serious consideration as to whether they might be diagnostic or not. In this work we compute the thick target yields of the chief reaction gamma-rays in UF6 using published thin target data. Comparisons are made to the neutron production rates to obtain γ/n estimates, and also to the 235U decay line at 186 keV which we take as a fiducial line. It is shown that the reaction gamma-rays are produced but are far too weak for practical safeguards purposes. Now that the underlying numerical data is readily available however, it can be used to

  10. 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 ...

  11. 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)

  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. 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

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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....

  4. 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.

  5. Interaction of the human cytomegalovirus particle with the host cell induces hypoxia-inducible factor 1 alpha

    International Nuclear Information System (INIS)

    The cellular protein hypoxia-inducible factor 1 alpha (HIF-1α) was induced after infection of human fibroblasts with human cytomegalovirus (HCMV). HCMV irradiated with ultraviolet light (uv-HCMV) also elicited the effect, demonstrating that the response was provoked by interaction of the infecting virion with the cell and that viral gene expression was not required. Although induction of HIF-1α was initiated by an early event, accumulation of the protein was not detected until 9 hours post infection, with levels increasing thereafter. Infection with uv-HCMV resulted in increased abundance of HIF-1α-specific RNA, indicating stimulation of transcription. In addition, greater phosphorylation of the protein kinase Akt was observed, and the activity of this enzyme was required for induction of HIF-1α to occur. HIF-1α controls the expression of many cellular gene products; therefore the findings reveal new ways in which interaction of the HCMV particle with the host cell may cause significant alterations to cellular physiology.

  6. 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.

  7. 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)

  8. The measurement and modeling of alpha-particle-induced charge collection in dynamic memories

    International Nuclear Information System (INIS)

    This thesis addresses the problem of α-particle-induced charge collection in high-density dynamic random access memories. A novel technique for the measurement of charge collection in high-density memory cells and bit lines due to α-particle strikes was developed. The technique involves D.C. tests on simple test structures with an α-particle source on the device package as a lid. The advantages of this new measurement technique are: the method allows for in-situ measurements of charge collection on both MOS capacitors and bit lines found in present-day memories; the on-chip measurement technique minimizes errors due to external probes loading the device under test; the measurements can be controlled by a personal computer, with the data being able to be reduced on the same machine. Results obtained using this new measurement technique show that the charge collection is found to depend upon test-structure size and the configuration of its neighbors. Results of two-dimensional simulations of charge flow along the surface of an MOS capacitor from current injection due to an α-particle strike indicate that a spatial potential variation of 0.5V may occur between the point of current injection and capacitor edge for a 1M dRAM capacitor

  9. 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

  10. 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

  11. 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)

  12. 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)

  13. On the decay of compound nuclei following alpha-particle and 12C induced reactions

    International Nuclear Information System (INIS)

    Multiple coincidence rates have been measured using a detector system consisting of a Ge(Li) spectrometer and eight NaI(Tl) or eight liquid scintillators. Reactions induced by α-particles with energies of 51-55 MeV and 118 MeV 12C ions are studied. The data are analysed to give the first and second central moments of the distribution of the number of γ-rays feeding individual levels in the final nuclei. When these numbers are compared to spin distributions calculated with the statistical model code GROGI the relative importance of dipole and quadrupole deexcitation modes can be ascertained. In particular, in the 122Te(α,4n)122Xe reaction the γ-decay prior to the entry into the ground band is well described as a statistical process proceeding to 50% by dipole and 50% by quadrupole radiation. In the 166Er(α,4n)166Yb and 192Os(α,4n)192Pt reactions the relative amount of quadrupole radiation is larger and it seems that the dipole and quadrupole decay takes place via separate cascades. In the 164Dy(12C,7-8n) reactions the average multiplicity is independent of spin, suggesting that the nucleus forgets the spin of the entry state before the process enters into the ground band. In the 176Yb(12C,8n)180Os reaction, finally, the nucleus difinitely retains memory of the entry state during the decay. In this last case the multiplicity measurement is combined with a γ-ray singles measurement to give an average excitation energy prior to the α-decay and the average moment of inertia characterising the decay of the high-spin states. (orig.)

  14. 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

  15. 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.

  16. 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.)

  17. 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.

  18. 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

  19. The severity of alpha-particle-induced DNA damage is revealed by exposure to cell-free extracts

    International Nuclear Information System (INIS)

    The rejoining of single-strand breaks induced by α-particle and γ irradiation in plasmid DNA under two scavenging conditions has been compared. At the two scavenger conditions has been compared. At the two scavenger capacities used of 1.5 x 107 and 3 x 108s-1 using Tris-HCl as the scavenger, the ratio of single- to double-strand breaks for α particles is fivefold less than the corresponding ratios for γ irradiation. The repair of such radiation-induced single-strand breaks has been examined using a cell-free system derived from human whole-cell extracts. We show that the rejoining of single-strand breaks for both α-particle- and γ-irradiated plasmid is dependent upon the scavenging capacity and that the efficiency of rejoining of α-particle-induced single-strand breaks is significantly less than that observed for γ-ray-induced breaks. In addition, for DNA that had been irradiated under conditions that mimic the cellular environment with respect to the radical scavenging capacity, 50 of α-particle-induced single-strand breaks are converted to double-strand breaks, in contrast with only ∼12% conversion of γ-ray-induced single-strand breaks, indicating that the initial damage caused by α particles is more severe. These studies provide experimental evidence for increased clustering of damage which may have important implications for the induction of cancer by low-level α-particle sources such as domestic radon. 37 refs., 5 figs., 1 tab

  20. 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.

  1. 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

  2. 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

  3. Relative efficiency of the radiothermoluminescence induced by 238Pu alpha-particles in LiF:Mg, Al2O3 and CaSO4:Dy

    International Nuclear Information System (INIS)

    This work represents a comparative study of the radiothermoluminescence (R.T.L.) induced by 60Co gamma rays and 238Pu alpha-particles in three R.T.L. materials: lithium fluoride, alumina and dysprosium activated calcium sulphate. The T.L. glow curves induced by the two radiations are very similar. However, for the same absorbed dose, different sensitivity is seen to each form of irradiation. Measurements of the relative R.T.L. efficiency, epsilon, were made in the linear zone (dose<1Gy). These response differences are attributed to the manner in which the energies of the two radiations are distributed in the detection material. Theoretical determination of epsilon can be carried out from calculation of the spatial distribution of the ionization energy density around the α-particle track

  4. 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.

  5. 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

  6. 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

  7. 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)

  8. 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.).

  9. Co-Cr-Mo Alloy Particles Induce Tumor Necrosis Factor Alpha Production in MLO-Y4 Osteocytes: A Role for Osteocytes in Particle Induced Inflammation

    OpenAIRE

    Kanaji, Arihiko; Caicedo, Marco S.; Virdi, Amarjit S.; Sumner, D. Rick; Hallab, Nadim J.; Sena, Kotaro

    2009-01-01

    Wear debris-induced osteolysis is purportedly the limiting problem affecting the long term results of joint arthroplasty. Pathogenic effects of wear debris in peri-implant cells such as macrophages, osteoblasts and osteoclasts have been well studied. In contrast, the affects of wear-debris on osteocytes, which make up over 90% of all bone cells, remains unknown. We hypothesized that metal implant debris can induce the proinflammatory response in osteocytes. This study demonstrated the effects...

  10. Understanding of the mechanical and structural changes induced by alpha particles and heavy ions in the French simulated nuclear waste glass

    Science.gov (United States)

    Karakurt, G.; Abdelouas, A.; Guin, J.-P.; Nivard, M.; Sauvage, T.; Paris, M.; Bardeau, J.-F.

    2016-07-01

    Borosilicate glasses are considered for the long-term confinement of high-level nuclear wastes. External irradiations with 1 MeV He+ ions and 7 MeV Au5+ ions were performed to simulate effects produced by alpha particles and by recoil nuclei in the simulated SON68 nuclear waste glass. To better understand the structural modifications, irradiations were also carried out on a 6-oxides borosilicate glass, a simplified version of the SON68 glass (ISG glass). The mechanical and macroscopic properties of the glasses were studied as function of the deposited electronic and nuclear energies. Alpha particles and gold ions induced a volume change up to -0.7% and -2.7%, respectively, depending on the glass composition. Nano-indentations tests were used to determine the mechanical properties of the irradiated glasses. A decrease of about -22% to -38% of the hardness and a decrease of the reduced Young's modulus by -8% were measured after irradiations. The evolution of the glass structure was studied by Raman spectroscopy, and also 11B and 27Al Nuclear Magnetic Resonance (MAS-NMR) on a 20 MeV Kr irradiated ISG glass powder. A decrease of the silica network connectivity after irradiation with alpha particles and gold ions is deduced from the structural changes observations. NMR spectra revealed a partial conversion of BO4 to BO3 units but also a formation of AlO5 and AlO6 species after irradiation with Kr ions. The relationships between the mechanical and structural changes are also discussed.

  11. Evaluation through comet assay of DNA damage induced in human lymphocytes by alpha particles. Comparison with protons and Co-60 gamma rays

    International Nuclear Information System (INIS)

    Several techniques with different sensitivity to single-strand breaks and/or double strand breaks were applied to detect DNA breaks generated by high LET particles. Tests that assess DNA damage in single cells might be the appropriate tool to estimate damage induced by particles, facilitating the assessment of heterogeneity of damage in a cell population. The microgel electrophoresis (comet) assay is a sensitive method for measuring DNA damage in single cells. The objective of this work was to evaluate the proficiency of comet assay to assess the effect of high LET radiation on peripheral blood lymphocytes, compared to protons and Co-60 gamma rays. Materials and methods: Irradiations of blood samples were performed at TANDAR laboratory (Argentina). Thin samples of human peripheral blood were irradiated with different doses (0-2.5 Gy) of 20.2 MeV helium-4 particles in the track segment mode, at nearly constant LET. Data obtained were compared with the effect induced by a MeV protons and Co-60 gamma rays. Alkaline comet assay was applied. Comets were quantified by the Olive tail moment. Distribution of the helium-4 particle and protons were evaluated considering Poisson distribution in lymphocyte nuclei. The mean dose per nucleus per particle result 0.053 Gy for protons and 0.178 Gy for helium-4 particles. When cells are exposed to a dose of 0.1 Gy, the hit probability model predicts that 43% of the nuclei should have experienced and alpha traversal while with protons, 85% of the nuclei should be hit. The experimental results show a biphasic response for helium-4 particles (0.1 Gy), indicating the existence of two subpopulations: unhit and hit. Distributions of tail moment as a function of fluence and experimental dose for comets induced by helium-4 particles, protons and Co-60 gamma rays were analyzed. With helium-4 irradiations, lymphocyte nuclei show an Olive tail moment distribution flattened to higher tail moments a dose increase. However, for irradiations with

  12. 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)

  13. 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)

  14. 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.)

  15. Analysis of carcinogenic mechanisms of liver cancers induced by chronic exposure to alpha-particles from internally deposited Thorotrast

    International Nuclear Information System (INIS)

    For the successful space traveling, the possibility for the detrimental effects on health including cancer caused by exposure to cosmic rays is a major concern. Thorotrast is a 25% colloidal solution of natural α-emitter, thorium dioxide used as a radiological contrast medium during World War II. It caused hepatic malignant tumors by the local exposure to α-particles decades after administration. Thorotrast-induced liver tumors consist of hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), and angiosarcoma (AS) at nearly the same instance. We analyzed mutations of the p53 and the K-ras genes, microsatellite instability (MSI), and loss of heterozygosity (LOH) in Thorotrast ICC. The major p53 mutation observed in Thorotrast ICC was the transition type, suggesting that reactive oxygen species are not likely involved in gene mutations of Thorotrast cancers. MSI frequency in Thorotrast ICC was significantly higher than that in non-Thorotrast ICC. MSI was partly attributed to the inactivation of the hMLH1 mismatch repair gene via methylation of the promoter region and to monoclonal expansion of cells with mutations. Thorotrast ICC shared LOH pattern with non-Thorotrast HCC and ICC. Furthermore, we could assess the distribution and the quantity of deposited thorium using an imaging plate and a BAS image analyzer. The distribution of thorium deposits was not always consistent with that of apoptotic cells. We conclude that Thorotrast ICC is developed through complex carcinogenic steps including genomic instability and mutations of crucial genes during remodeling of the liver architecture. We emphasize how pathological specimens from Thorotrast patients are valuable for assessing the relevance of long-term exposure to low dose α-particles to radiation carcinogenesis

  16. 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.

  17. Activation cross sections of $\\alpha$-particle induced nuclear reactions on hafnium and deuteron induced nuclear reaction on tantalum: production of $^{178}$W/$^{178m}$Ta generator

    CERN Document Server

    Tárk'anyi, F; Ditrói, F; Hermanne, A; Ignatyuk, A V; Uddin, M S

    2014-01-01

    In the frame of a systematic study of charged particle production routes of medically relevant radionuclei, the excitation function for indirect production of $^{178m}$Ta through $^{nat}$Hf($\\alpha$,xn)$^{178}$W-$^{178m}$Ta nuclear reaction was measured for the first time up to 40 MeV. In parallel, the side reactions $^{nat}$Hf($\\alpha$,x)$^{179,177,176,175}$W, $^{183,182,178g,177,176,175}$Ta, $^{179m,177m,175}$Hf were also assessed. Stacked foil irradiation technique and $\\gamma$-ray spectrometry were used. New experimental cross section data for the $^{nat}$Ta(d,xn)$^{178}$W reaction are also reported up to 40 MeV. The measured excitation functions are compared with the results of the ALICE-IPPE, and EMPIRE nuclear reaction model codes and with the TALYS 1.4 based data in the TENDL-2013 library. The thick target yields were deduced and compared with yields of other charged particle ((p,4n), (d,5n) and ($^3$He,x)) production routes for $^{178}$W.

  18. Abnormal promoter methylation of multiple genes in the malignant transformed PEP2D cells induced by alpha particles exposure

    Institute of Scientific and Technical Information of China (English)

    LiP; SuiJL

    2002-01-01

    The 5' promoter regions of some genes contain CpG-rich areas,known as CpG islands,Methylation of the cytosine in these dinuleotides has important regulatory effects on gene expression.The functional significance of promoter hypermethylation would play the same roles in carcinogenesis as gene mutations.The promoter methylations p14ARF,p16INK4a,MGMT,GSTP1,BUB3 and DAPK genes were analyzed with methylation specific PCR(MSP) in the transformed human bronchial epithelial cells(BEP2D) induced by α-particles.The results indicated that p14ARF gene was not methylated in BEP2D cells,but was methylated in the malignant transformed BERP35T-1 cells,and the level of its transcription was depressed remarkable in the latter.However p16INK4a gene,which shares two exons with p14ARF gene,was not methylated.MGMT gene was methylated in both BEP2D and BERP35T-1.DAPK gene was partially methylated in BEP2D cells and methylated completely in BERP35T1.GSTP1 was not methylated in BEP2D cells and was methylated partly in BERP35T-1.BUB3 gene was not methylated in BEP2D as well as BERP35T1 cells and was further proved by sequencing analysis.

  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 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

  1. 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)

  2. 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...

  3. 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

  4. 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

  5. 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

  6. 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

  7. Evaluation of nuclear reaction cross section data for the production of (87)Y and (88)Y via proton, deuteron and alpha-particle induced transmutations.

    Science.gov (United States)

    Zaneb, H; Hussain, M; Amjad, N; Qaim, S M

    2016-06-01

    Proton, deuteron and alpha-particle induced reactions on (87,88)Sr, (nat)Zr and (85)Rb targets were evaluated for the production of (87,88)Y. The literature data were compared with nuclear model calculations using the codes ALICE-IPPE, TALYS 1.6 and EMPIRE 3.2. The evaluated cross sections were generated; therefrom thick target yields of (87,88)Y were calculated. Analysis of radio-yttrium impurities and yield showed that the (87)Sr(p, n)(87)Y and (88)Sr(p, n)(88)Y reactions are the best routes for the production of (87)Y and (88)Y respectively. The calculated yield for the (87)Sr(p, n)(87)Y reaction is 104 MBq/μAh in the energy range of 14→2.7MeV. Similarly, the calculated yield for the (88)Sr(p, n)(88)Y reaction is 3.2 MBq/μAh in the energy range of 15→7MeV. PMID:27016709

  8. Simultaneous production and separation of no-carrier-added 111In, 109Cd from alpha particle induced silver target

    International Nuclear Information System (INIS)

    A natural silver foil was bombarded by 30 MeV α-particles which produced 111In, 109Cd and 106mAg in the target matrix. 111In and 109Cd were separated from the Ag target matrix employing ion-exchange chromatography and liquid-liquid extraction (LLX). In the chromatographic separation, the active solution containing the NCA products were adsorbed in the column containing Dowex 50 and were eluted with HNO3. Bulk silver and 109Cd were sequentially eluted with 1 M HNO3. After complete elution of 109Cd and the bulk, 111In was eluted with 1.5 M HNO3. In the LLX, the NCA 111In was extracted to 1 % HDEHP (di-2(ethylhexyl)phosphoric acid) from 10-2 M HNO3 solution, leaving cadmium and bulk silver quantitatively in the aqueous phase. The NCA 109Cd was separated from the bulk Ag by precipitating Ag as AgCl. NCA 111In was stripped back quantitatively from HDEHP phase using 8 M HNO3. (author)

  9. 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)

  10. 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

  11. 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.

  12. 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

  13. 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)

  14. 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

  15. 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)

  16. 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....

  17. 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

  18. 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

  19. Low-background spectrometer for the study of fast neutron-induced (n,alpha) reactions

    CERN Document Server

    Khriachkov, V A; Mitrofanov, V P; Semenova, N N

    2000-01-01

    An alpha-particle spectrometer based on an ionization chamber with Frisch grid and a waveform digitizer has been developed for studies of fast neutron-induced (n,alpha) reactions. The information on the energy of the alpha-particle and its emission angle can be obtained from the amplitude and rise time of the digitized anode signal. For a situation where both the solid target on the cathode of the ionization chamber and the working gas are the alpha-particle sources, a new method for the suppression of the neutron-induced background is proposed. The background due to gaseous alpha-particles was reduced by a factor of 30.

  20. 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

  1. Neutron-induced alpha radiography

    International Nuclear Information System (INIS)

    A new radiography technique to inspect thin samples was developed. Low energy alpha particles, generated by a boron based screen under thermal neutron irradiation, are used as penetrating radiation. The solid state nuclear track detector CR-39 has been used to register the image. The interaction of the α - particles with the CR-39 gives rise to damages which under an adequate chemical etching became tracks the basic units forming the image. A digital system was developed for data acquisition and data analysis as well as for image processing. The irradiation and etching conditions to obtain the best radiography are 1,3 hours and 25 minutes at 70 deg C respectively. For such conditions samples having 10 μm in thickness can be inspected with a spatial resolution of 32 μm. The use of the digital system has reduced the time spent for data acquisition and data analysis and has improved the radiography image visualization. Furthermore, by using the digital system, it was possible to study several new parameters regarding the tracks which are very important to understand and study the image formation theory in solid state nuclear track detectors, the one used in this thesis. Some radiography images are also shown which demonstrate the potential of the proposed radiography technique. When compared with the other radiography techniques already in use to inspect thin samples, the present one developed in the present paper allows a smaller time to obtain the image, it is not necessary to handle liquid radioactive substances, the detector is insensitive to β, γ, X-ray and visible light. (author)

  2. 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

  3. 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)

  4. 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

  5. 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.)

  6. L-shell X-ray production cross sections induced by protons and alpha-particles in the 0.7–2.0 MeV/amu range for Ru and Ag

    Energy Technology Data Exchange (ETDEWEB)

    Bertol, A.P.L., E-mail: anapaula.bertol@gmail.com [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Trincavelli, J. [Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba (Argentina); Instituto Enrique Gaviola, CONICET (Argentina); Hinrichs, R. [Instituto de Geociências, UFRGS, Porto Alegre, RS (Brazil); Vasconcellos, M.A.Z. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil)

    2014-01-01

    The X-ray emissions induced by protons and alpha-particles of the elements Ag and Ru were measured on mono-elemental thin films. L-shell X-ray production cross sections were obtained for the three L-subshells, considering absorption corrections. The Ag X-ray production cross sections agree with experimental data of other authors and with theoretical models, and were used to endorse the quality of the experimental values for Ru, that were not found in the literature.

  7. L-shell X-ray production cross sections induced by protons and alpha-particles in the 0.7-2.0 MeV/amu range for Ru and Ag

    Science.gov (United States)

    Bertol, A. P. L.; Trincavelli, J.; Hinrichs, R.; Vasconcellos, M. A. Z.

    2014-01-01

    The X-ray emissions induced by protons and alpha-particles of the elements Ag and Ru were measured on mono-elemental thin films. L-shell X-ray production cross sections were obtained for the three L-subshells, considering absorption corrections. The Ag X-ray production cross sections agree with experimental data of other authors and with theoretical models, and were used to endorse the quality of the experimental values for Ru, that were not found in the literature.

  8. 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)

  9. 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...

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. The sensitivity of the alkaline comet assay in detecting DNA lesions induced by X-rays, gamma rays and alpha particles

    International Nuclear Information System (INIS)

    Experiments were designed and performed in order to investigate whether or not the different cellular energy deposition patterns of photon radiation with different energies (29 kV, 220 kV X-rays; Co-60, Cs-137-γ-rays) and alpha-radiation from an Am-241 source differ in DNA damage induction capacity in human cells. For this purpose, the alkaline comet assay (single cell gel electrophoresis) was applied to measure the amount of DNA damage in relation to the dose received. The comet assay data for the parameters o/oo DNA in the tail' and 'tail moment' for human peripheral lymphocytes did not indicate any difference in the initial radiation damage produced by 29 kV X-rays relative to the reference radiations, 220 kV X-rays and the gamma rays, whether for the total mean dose range of 0-3 Gy nor in the low-dose range. In contrast, when the 'tail length' data were analysed saturation of the fitted dose response curve appeared for X-rays at about 1.5 Gy but was not apparent for gamma rays up to 3 Gy. Preliminary data for alpha exposures of HSC45-M2 cells showed a significant increase in DNA damage only at high doses (>2 Gy Am-241), but the damage at 2 Gy exceeded the damage induced at 2 Gy by Cs-137-γ-rays by a factor of 2.5. In contrast, other experiments involving different cell systems and DNA damage indicators such as chromosomal aberrations have detected a significant increase in DNA damage at much lower doses, that is at 0.02 Gy for Am-241 and depicted a higher biological effectiveness. These results indicate that differences in biological effects arise through downstream processing of complex DNA damage. (authors)

  16. 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.

  17. 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.

  18. 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)

  19. 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

  20. Alpha methyldopa induced hepatotoxicity in pregnancy

    Directory of Open Access Journals (Sweden)

    Padmasri Ramalingappa

    2014-06-01

    Full Text Available We report a case of gestational hepatitis due to alpha-methyldopa and briefly review the literature on alpha-methyldopa-induced hepatotoxicity in pregnancy. A 32 year old woman, primigravida with 34 weeks of gestation with pre eclampsia, presented with symptoms of nausea, dark coloured urine and jaundice. She was on alpha methyldopa (Aldomet 250 mg thrice a day since the last five weeks. Laboratory investigations revealed raised bilirubin, serum aspartate transaminases and serum alanine transaminases. Platelets were normal. Peripheral smear did not show haemolysis. With the exclusion of viral, haemolytic and obstructive causes, drug induced jaundice was considered as a differential diagnosis. Alpha methyldopa was withdrawn and replaced with nifedipine for her pre eclampsia treatment. Her repeat bilirubin level done two weeks later showed a drop. She went into labour at 38 weeks and delivered vaginally. In postpartum follow up her liver tests returned to normal in two weeks, about six weeks after stopping methyldopa. Hepatotoxicity should be considered as one of the adverse drug reaction of alpha methyldopa. It is not possible at present to predict which patients will develop liver disease following the administration of this drug. An awareness of the possibility of methyldopa induced hepatotoxicity should be present in the clinician's mind and liver function tests should be done at regular intervals. The occasional occurrence of this harmful side effect is not a contraindication to the use of this antihypertensive agent. [Int J Reprod Contracept Obstet Gynecol 2014; 3(3.000: 805-807

  1. 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)

  2. 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

  3. 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)

  4. 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.

  5. 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.

  6. 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)

  7. 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).

  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. 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

  10. 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

  11. 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)

  12. 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.

  13. Changes of gene methylation profile in malignant transformation of immortalized human bronchial epithelial cell line induced by alpha-particle irradiation

    International Nuclear Information System (INIS)

    Objective: To identify the changes of DNA methylation profile in the process of malignant transformation of BEP2D cell induced by α particles. Methods: The genomic DNAs were isolated from the malignant transformation BERP35T4 cells and immortalized human bronchial epithelial cell line BEP2D. Genomic DNAs were digested by MseI and ligated of PCR linkers. Methylated DNAs were digested by BstUI and amplified by PCR. The methylated DNA probes were prepared by labeling with Cy3 and Cy5 fluorescence dyes individually and hybridized to the methylation CpG-Island microarray. The hybridization results were scanned and analyzed. Intensity values were quality controlled and normalized. The normalized data were used to identify the differentially expressed genes based on a 1.5 fold difference of the expression level. Results: There were 16 genes which showed changes of methylation level in malignant transformation BERP35T4 cells, 9 of them were hyper methylation and 7 were hypo methylation. These genes were including the SKIP gene, PPP3CC gene, MAP2K6 gene, KIR2DL1 gene, KIR2DL4 gene, KIR3DP1 gene, ZNF493 gene, ZNF100 gene, NKX2-5 gene, TFAP2D gene, DR1 gene, KCNJ16 gene, CCDC18 gene, FNBP1L gene, IRX4 gene, EPB41L3 gene, TCP10 gene and so on. Conclusions: The DNA methylation might have effects on ionizing radiation derived tumorigenesis. (authors)

  14. 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

  15. 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)

  16. 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

  17. 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)

  18. 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)

  19. 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)

  20. 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)

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Investigation of double strand breaks induced by alpha particle irradiation using C.N.B.G. microbeam in human keratinocytes; Mise en evidence de cassures double brin de l'ADN induites par irradiation de keratinocytes humains en microfaisceau alpha

    Energy Technology Data Exchange (ETDEWEB)

    Pouthier, Th

    2006-12-15

    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

  6. 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...

  7. 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…

  8. Similarities between human ataxia fibroblasts and murine SCID cells: high sensitivity to [gamma] rays and high frequency of methotrexate-induced DHFR gene amplification, but normal radiosensitivity to densely ionizing [alpha] particles

    Energy Technology Data Exchange (ETDEWEB)

    Luecke-Huhle, C. (Kernforschungszentrum Karlsruhe, Inst. fuer Genetik (Germany))

    1994-07-01

    Two [gamma]-ray hypersensitive cell lines, human ataxia telangiectasia (AT) and murine severe combined immune deficiency (SCID) cells, proved to be very competent in amplifying their dihydrofolate reductase (DHFR) gene under methotrexate selection stress. Over a period of months, methotrexate-resistant clones were obtained which were able to grow in progressively increasing methotrexate concentrations up to 1 mM. By then methotrexate-resistant AT and SCID cells had amplified their DHFR gene 6- and 30-fold, respectively, and showed very high DHFR mRNA expression. In contrast, related cells with normal radiosensitivity (human GM637 and mouse BALB/c fibroblasts) did not show DHFR gene amplification under comparable conditions. This correlation of the capacity of DHFR gene amplification and [gamma]-ray hypersensitivity in AT and SCID cells suggests that gene amplification may have a mechanism(s) in common with those involved in repair of [gamma]-radiation-induced damage. No difference in cell killing could be observed following exposure to densely ionizing [alpha] particles: AT and SCID cells exhibited comparable survival rates to GM637 and BALB/c cells, respectively. (orig.)

  9. Ion-exchange separation of radioiodine and its application to production of 124I by alpha particle induced reactions on antimony

    International Nuclear Information System (INIS)

    The basic parameters related to radiochemical separation of iodine from tellurium and antimony by anion-exchange chromatography using the resin Amberlyst A26 were studied. The separation yield of 124I amounted to 96% and the decontamination factor from 121Te and 122Sb was > 104. The method was applied to the production of 124I via the 123Sb(α, 3n) reaction. In an irradiation of 110 mg of natSb2O3 (thickness ∝0.08 g/cm2) with 38 MeV α-particles at 1.2 μA beam current for 4 h, corresponding to the beam energy range of Eα = 37 → 27 MeV, the batch yield of 124I obtained was 12.42 MBq and the 125I and 126I impurities amounted to 3.8% and 0.7%, respectively. The experimental batch yield of 124I amounted to 80% of the theoretically calculated value but the level of the radionuclidic impurities were in agreement with the theoretical values. About 96% of the radioiodine was in the form of iodide and the inactive impurities (Te, Sb, Sn) were below the permissible level. Due to the relatively high level of radionuclidic impurity the 124I produced would possibly be useful only for restricted local consumption or for animal experiments.

  10. Ion-exchange separation of radioiodine and its application to production of {sup 124}I by alpha particle induced reactions on antimony

    Energy Technology Data Exchange (ETDEWEB)

    Shuza Uddin, Md. [Forschungszentrum Juelich (Germany). Inst. fuer Neurowissenschaften und Medizin, INM-5: Nuklearchemie; Atomic Energy Research Establishment, Inst. of Nuclear Science and Technology, Dhaka (Bangladesh); Qaim, Seyed M.; Spahn, Ingo; Spellerberg, Stefan; Scholten, Bernhard; Coenen, Heinz H. [Forschungszentrum Juelich (Germany). Inst. fuer Neurowissenschaften und Medizin, INM-5: Nuklearchemie; Hermanne, Alex [Vrije Univ. Brussel (Belgium). Cyclotron Lab.; Hossain, Syed Mohammod [Atomic Energy Research Establishment, Inst. of Nuclear Science and Technology, Dhaka (Bangladesh)

    2015-07-01

    The basic parameters related to radiochemical separation of iodine from tellurium and antimony by anion-exchange chromatography using the resin Amberlyst A26 were studied. The separation yield of {sup 124}I amounted to 96% and the decontamination factor from {sup 121}Te and {sup 122}Sb was > 10{sup 4}. The method was applied to the production of {sup 124}I via the {sup 123}Sb(α, 3n) reaction. In an irradiation of 110 mg of {sup nat}Sb{sub 2}O{sub 3} (thickness ∝0.08 g/cm{sup 2}) with 38 MeV α-particles at 1.2 μA beam current for 4 h, corresponding to the beam energy range of E{sub α} = 37 → 27 MeV, the batch yield of {sup 124}I obtained was 12.42 MBq and the {sup 125}I and {sup 126}I impurities amounted to 3.8% and 0.7%, respectively. The experimental batch yield of {sup 124}I amounted to 80% of the theoretically calculated value but the level of the radionuclidic impurities were in agreement with the theoretical values. About 96% of the radioiodine was in the form of iodide and the inactive impurities (Te, Sb, Sn) were below the permissible level. Due to the relatively high level of radionuclidic impurity the {sup 124}I produced would possibly be useful only for restricted local consumption or for animal experiments.

  11. 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.

  12. 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

  13. 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).

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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)

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. Variation of Fission-Fragment Kinetic Energy Distribution, Mass Distribution, and Yield of Long-Range Alpha Particles in the Resonance-Neutron-Induced Fission of U235 and Pu239

    International Nuclear Information System (INIS)

    These measurements were undertaken to obtain additional information on the fission process, and to investigate the application of this information to the assignment of J-values to resonance levels, as the usual methods of determining J-values are of limited applicability in the case of fissile isotopes. An earlier study of U235 showed that the fission-fragment kinetic energy and the alpha yield varied significantly from level to level, and fell into two groups suggestive of the two possible J-values. The present paper reports on measurements on Pu239. A study of 19 levels shows 15 levels with high average kinetic energy and 4 levels with low average kinetic energy, the former being assigned J -1 and the latter J = 0 on the basis of the expected ratio of population of the two spin states and also for maximum compatibility with other determinations. Some variation of relative alpha-particle yield was found. It is concluded that (1) there are definite variations of kinetic energy of the fragments from level to level; (2) the variation in the case of U235 is correlated with the relative yield of symmetric fission; (3) there is some indication in the case of Pu239 that the variation of fragment energy is correlated with the J-values; and (4) the relative yield of alpha particles varies in an expected fashion. (author)

  8. 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

  9. Cytokine vaccination: neutralising IL-1alpha autoantibodies induced by immunisation with homologous IL-1alpha

    DEFF Research Database (Denmark)

    Svenson, M; Hansen, M B; Thomsen, A R; Diamant, Marcus; Nansen, A; Rieneck, K; Otterness, I G; Bendtzen, K

    High-affinity IgG autoantibodies (aAb) to IL-1alpha are among the most frequently found aAb to cytokines in humans. To establish an animal model with aAb to IL-1alpha, we immunised mice with recombinant murine IL-1alpha. Unprimed and Bacille Calmette-Guérin (BCG)-primed BALB/cA mice were vaccinated...... with IL-1alpha coupled to purified protein derivative of tuberculin (PPD). Both unprimed and primed animals developed IgG aAb to IL-1alpha. These aAb persisted at high levels more than 100 days after vaccination and did not cross-react with murine IL-1beta. The induced anti-IL-1alpha aAb inhibited...... induced in mice by vaccination with recombinant murine IL-1alpha conjugated to PPD. Studies of the effects of IL-1alpha aAb in such animals may help clarify the importance of naturally occurring IL-1alpha aAb in humans and permit the evaluation of future therapies with cytokine aAb in patients with...

  10. Major vault protein forms complexes with hypoxia-inducible factor (HIF)-1alpha and reduces HIF-1alpha level in ACHN human renal adenocarcinoma cells.

    Science.gov (United States)

    Iwashita, Ken-ichi; Ikeda, Ryuji; Takeda, Yasuo; Sumizawa, Tomoyuki; Furukawa, Tatsuhiko; Yamaguchi, Tatsuya; Akiyama, Shin-ichi; Yamada, Katsushi

    2010-04-01

    Vaults are evolutionarily highly conserved ribonucleoprotein (RNP) particles with a hollow barrel-like structure. Although roles in multidrug resistance and innate immunity have been suggested, the physiological function of vaults remains unclear. Major vault protein (MVP), the main component of the vault particle, has been reported to be induced by hypoxia. However, there are no reports about the effect of vaults on cellular responses to hypoxia. We thus examined whether vaults are implicated in cellular responses to hypoxia. In this study, we focused on hypoxia-inducible factor-1alpha (HIF-1alpha), which is a master regulator of hypoxic responses, and found that: (i) MVP knockdown by RNA interference increases HIF-1alpha protein levels induced by hypoxia and hypoxia mimetics; (ii) MVP knockdown does not affect HIF-1alpha mRNA levels, but decreases the ubiquitination and degradation of HIF-1alpha protein; and (iii) vaults form complexes with HIF-1alpha, PHD2, and pVHL. Taken together, these results suggest that vaults function as scaffolds in HIF-1alpha degradation pathway and promote the ubiquitination and degradation of HIF-1alpha. PMID:20175781

  11. 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.

  12. 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

  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. 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. 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 ...

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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)

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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)

  9. 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)

  10. 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.

  11. 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.

  12. Parameterization of ionization induced in the atmosphere by precipitating particles

    Science.gov (United States)

    Artamonov, Anton; Usoskin, Ilya; Kovaltsov, Gennady

    We present a physical model to calculate ionization induced in the atmosphere by precipitating particles. This model is based on the Bethe-Bloch equation applied for precipitating particles such as: electrons, alpha-particles and protons. The energy range of precipitating particles is up to 5MeV and 80MeV/nuc respectively. This model provides an easy implementation with a robust realization of model calculations for a wide range of incident energies of precipitating particles. This method is limited to the upper-middle atmosphere. An ionization yield function [see, Usoskin and Kovaltsov, 2006; Usoskin, Kovaltsov, Mironova, 2010] can be also used in this model, making it possible to calculate the atmospheric ionization effect of precipitating particles for the entire atmosphere, dawn to the ground.

  13. 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.

  14. 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.)

  15. 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.)

  16. TRIASSIC: the Time-Resolved Industrial Alpha-Source Scanning Induced Current microscope

    Science.gov (United States)

    Pallone, Arthur

    Time-resolved ion beam induced current (TRIBIC) microscopy yields useful information such as carrier mobility and lifetimes in semiconductors and defect locations in devices; however, traditional TRIBIC uses large, expensive particle accelerators that require specialized training to operate and maintain. The time-resolved industrial alpha-source scanning induced current (TRIASSIC) microscope transforms TRIBIC by replacing the particle accelerator facility with an affordable, tabletop instrument suitable for use in research and education at smaller colleges and universities. I will discuss the development of, successes with, setbacks to and future directions for TRIASSIC.

  17. 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

  18. Structural and optical investigation on alpha particle irradiated CR-39 surface coated by MEH-PPV conducting polymer

    International Nuclear Information System (INIS)

    Highlights: • The CR-39 polymeric surface was exposed to alpha particles. • Dip coating of CR-39 surface was done using MEH-PPV conducting polymer. • FTIR is insensitive approach to detect the induced modifications in the irradiated surfaces. • Photoluminescence and UV–Vis responses exhibited remarkable spectral differences. • Both techniques could be used to provide sensitive methods for alpha particle detection. - Abstract: Photoluminescence and UV–Vis spectral evaluation of a poly allyl diglycol carbonate (CR-39) detector coated by poly(2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) conducting polymer are demonstrated. The CR-39 surfaces were exposed to thin 241Am disk source that emits alpha particles with activity 333 kBq. Surface modification of the detector by MEH-PPV was acquired by a simple dip coating process. Our findings revealed that the spectroscopic analysis using FTIR is insensitive approach to detect the induced modifications in the irradiated samples. Additionally, the track density of the irradiated samples affects significantly the photoluminescence and UV–Vis responses of the CR-39 samples. The spectral peak heights and the integrated intensities under the peaks exhibit linear correlations (correlation coefficient R2 = 0.9904 to 0.9968) with the fluence of alpha particles. The linear fitting functions together with the corresponding fitting parameters were evaluated. Both techniques exhibited remarkable spectral differences for the irradiated samples, and hence they could be employed to provide sensitive methods for alpha particle detection. Results of sample fabrication and modification, along with structural and optical evaluation are addressed and thoroughly discussed

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.)

  4. 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.

  5. Interferon-alpha induced depressive-like behavior in rats

    DEFF Research Database (Denmark)

    Fischer, C. W.; Liebenberg, N.; Elfving, B.;

    2013-01-01

    Background: A subpopulation of individuals with major depressive disorder (MDD) show increased levels of peripheral inflammatory biomarkers, indicating an association of MDD with a chronically activated immune system. Administration of the immune stimulating cytokine, interferon-alpha (IFN......-(alpha)), also used in the treatment of cancer and hepatitis, commonly leads to neuropsychiatric side effects with approximately 16- 45% of patients developing depressive-like symptoms during the course of therapy. Given that treatmentresistant depression has been associated with increased levels of inflammatory...... markers, the development of an inflammation-induced model of depression is highly relevant. Aim: The objective of this study was to investigate whether IFN-(alpha) can induce a chronic low-grade inflammatory state in rats, and whether this may lead to a depressive phenotype. Methods: Male Sprague...

  6. High efficiency charged-particle spectrometer using gridded ionization chamber for fast-neutron induced reactions

    International Nuclear Information System (INIS)

    A high efficiency charged particle spectrometer for fast neutron induced reactions has been developed using a gridded-ionization chamber taking advantage of its large solid angle and capability of energy-angle determination. It is characterized by high stopping-power and low background to be applicable for alpha-particles emitted by 15 MeV neutrons and protons for MeV incident neutrons. The spectrometer has been applied successfully for (n, alpha) and (n, p) reactions. (orig.)

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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.

  12. Differential inhibition of lipopolysaccharide-induced phenomena by anti-tumor necrosis factor alpha antibody.

    OpenAIRE

    Vogel, S N; Havell, E A

    1990-01-01

    Tumor necrosis factor alpha (TNF alpha) has been implicated as a major mediator of lipopolysaccharide (LPS)-induced phenomena. Administration to mice of a polyclonal, monospecific antibody prepared against recombinant murine TNF alpha abolished detection of LPS-induced TNF alpha activity and significantly reduced levels of LPS-induced colony-stimulating factor but failed to reduce the production of LPS-induced interferon, corticosterone, or LPS-induced hypoglycemia.

  13. 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...

  14. 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

  15. 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...

  16. 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

  17. 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...

  18. Fasting induces basolateral uptake transporters of the SLC family in the liver via HNF4alpha and PGC1alpha.

    Science.gov (United States)

    Dietrich, Christoph G; Martin, Ina V; Porn, Anne C; Voigt, Sebastian; Gartung, Carsten; Trautwein, Christian; Geier, Andreas

    2007-09-01

    Fasting induces numerous adaptive changes in metabolism by several central signaling pathways, the most important represented by the HNF4alpha/PGC-1alpha-pathway. Because HNF4alpha has been identified as central regulator of basolateral bile acid transporters and a previous study reports increased basolateral bile acid uptake into the liver during fasting, we hypothesized that HNF4alpha is involved in fasting-induced bile acid uptake via upregulation of basolateral bile acid transporters. In rats, mRNA of Ntcp, Oatp1, and Oatp2 were significantly increased after 48 h of fasting. Protein expression as determined by Western blot showed significant increases for all three transporters 72 h after the onset of fasting. Whereas binding activity of HNF1alpha in electrophoretic mobility shift assays remained unchanged, HNF4alpha binding activity to the Ntcp promoter was increased significantly. In line with this result, we found significantly increased mRNA expression of HNF4alpha and PGC-1alpha. Functional studies in HepG2 cells revealed an increased endogenous NTCP mRNA expression upon cotransfection with either HNF4alpha, PGC-1alpha, or a combination of both. We conclude that upregulation of the basolateral bile acid transporters Ntcp, Oatp1, and Oatp2 in fasted rats is mediated via the HNF4alpha/PGC-1alpha pathway. PMID:17640976

  19. 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)

  20. 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)

  1. 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.

  2. [Autoimmunization induced by interferon alpha therapy in chronic hepatitis C].

    Science.gov (United States)

    Rocca, Pierre; Codes, Liana; Chevallier, Michèle; Trépo, Christian; Zoulim, Fabien

    2004-11-01

    We report the case of a 56 year-old woman with post-transfusion chronic hepatitis C who presented with a severe ALT flare up associated with a rapid progression of liver fibrosis during interferon alpha 2b therapy. Several hypotheses were considered to explain the etiology of this ALT flare: there was no viral super infection by other hepatotropic viruses, no toxic hepatitis, no metabolic disease, and no other specific liver diseases could be identified. HLA typing showed a specific profile A1 B8 DR3 (risk factor of auto-immunization during interferon alpha therapy) with antinuclear antibodies and anti smooth muscle antibodies. This case suggests that auto-immunization induced by interferon alpha should be investigated in case of ALT flare that is not followed by an HCV breakthrough. PMID:15657545

  3. 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.

  4. 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

  5. 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

  6. 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)

  7. 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

  8. 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.

  9. Study of influence of catechins on bystander responses in alpha-particle radiobiological experiments using thin PADC films

    Energy Technology Data Exchange (ETDEWEB)

    Law, Y.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, 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

    In this study, Chinese hamster ovary (CHO) cells were cultured in custom-made petri dishes with thin PADC films as substrates. Alpha particles with energies of 5 MeV were then irradiated from the bottom of PADC films. The DNA strand breaks in the bystander cells induced by irradiation were quantified with the use of terminal dUTP transferase-mediated nick end-labeling (TUNEL) assay. To study the influence of catechins on the bystander responses, catechins were added into the medium before alpha-particle irradiation of the cells. Fewer DNA strand breaks in the bystander cells were observed. As catechins are ROS (reactive oxygen species)-scavengers, the studied bystander cells might have been protected from radiation through scavenging of ROS by catechins.

  10. 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)

  11. 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...

  12. 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

  13. 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

  14. 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.)

  15. 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

  16. 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)

  17. 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.

  18. The {alpha}-induced thick-target {gamma}-ray yield from light elements

    Energy Technology Data Exchange (ETDEWEB)

    Heaton, R.K. [Queen`s Univ., Kingston, ON (Canada). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

    1994-10-01

    The {alpha}-induced thick-target {gamma}-ray yield from light elements has been measured in the energy range 5.6 MeV {le} E{sub {alpha}} {le} 10 MeV. The {gamma}-ray yield for > 2.1 MeV from thick targets of beryllium, boron nitride, sodium fluoride, magnesium, aluminum and silicon were measured using the {alpha}-particle beam from the Lawrence Berkeley Laboratories 88 in. cyclotron. The elemental yields from this experiment were used to construct the {alpha}-induced direct production {gamma}-ray spectrum from materials in the SNO detector, a large volume ultra-low background neutrino detector located in the Creighton mine near Sudbury, Canada. This background source was an order of magnitude lower than predicted by previous calculations. These measurements are in good agreement with theoretical calculations of this spectrum based on a statistical nuclear model of the reaction, with the gross high energy spectrum structure being reproduced to within a factor of two. Detailed comparison of experimental and theoretical excitation population distribution of several residual nuclei indicate the same level of agreement within experimental uncertainties.

  19. 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)

  20. 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)

  1. 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.

  2. 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)

  3. 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.

  4. 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

  5. Particle-induced thermonuclear fusion

    International Nuclear Information System (INIS)

    A nuclear fusion process for igniting a nuclear fusion pellet in a manner similar to that proposed for laser beams uses, an array of pulsed high energy combined particle beams, focused to bombard the pellet for isentropically compressing it to a Fermi-degenerate state by thermal blow-off and balanced beam momentum transfer. (author)

  6. 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.

  7. 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)

  8. 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

  9. 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)

  10. 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)

  11. 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

  12. 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

  13. 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)

  14. Cobalt inhibits the interaction between hypoxia-inducible factor-alpha and von Hippel-Lindau protein by direct binding to hypoxia-inducible factor-alpha.

    Science.gov (United States)

    Yuan, Yong; Hilliard, George; Ferguson, Tsuneo; Millhorn, David E

    2003-05-01

    The hypoxia-inducible factor (HIF) activates the expression of genes that contain a hypoxia response element. The alpha-subunits of the HIF transcription factors are degraded by proteasomal pathways during normoxia but are stabilized under hypoxic conditions. The von Hippel-Lindau protein (pVHL) mediates the ubiquitination and rapid degradation of HIF-alpha (including HIF-1alpha and HIF-2alpha). Post-translational hydroxylation of a proline residue in the oxygen-dependent degradation (ODD) domain of HIF-alpha is required for the interaction between HIF and VHL. It has previously been established that cobalt mimics hypoxia and causes accumulation of HIF-1alpha and HIF-2alpha. However, little is known about the mechanism by which this occurs. In an earlier study, we demonstrated that cobalt binds directly to the ODD domain of HIF-2alpha. Here we provide the first evidence that cobalt inhibits pVHL binding to HIF-alpha even when HIF-alpha is hydroxylated. Deletion of 17 amino acids within the ODD domain of HIF-2alpha that are required for pVHL binding prevented the binding of cobalt and stabilized HIF-2alpha during normoxia. These findings show that cobalt mimics hypoxia, at least in part, by occupying the VHL-binding domain of HIF-alpha and thereby preventing the degradation of HIF-alpha. PMID:12606543

  15. 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.

  16. 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)

  17. 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)

  18. 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)

  19. 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

  20. 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.

  1. 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)

  2. 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.

  3. 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

  4. 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.

  5. 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)

  6. Single particle-induced latchup

    International Nuclear Information System (INIS)

    This paper presents an up-to-date overview of the single-event latchup (SEL) hard failure mode encountered in electronic device applications involving heavy ion environment. This phenomenon is specific to CMOS technology. Single-event latchup is discussed after a short description of the effects induced by the interaction of a heavy ion with silicon. Understanding these effects is necessary to understand the different failures. This paper includes a description of the latchup phenomenon and the different triggering modes, reviews of models and hardening solutions, and finally presents new developments in simulation approaches

  7. 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

  8. 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

  9. 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.)

  10. 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.

  11. 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

  12. 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.

  13. 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)

  14. 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

  15. 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)

  16. 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.

  17. 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.)

  18. 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.

  19. 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.)

  20. Neutron-Induced Charged Particle Studies at LANSCE

    Science.gov (United States)

    Lee, Hye Young; Haight, Robert C.

    2014-09-01

    Direct measurements on neutron-induced charged particle reactions are of interest for nuclear astrophysics and applied nuclear energy. LANSCE (Los Alamos Neutron Science Center) produces neutrons in energy of thermal to several hundreds MeV. There has been an effort at LANSCE to upgrade neutron-induced charged particle detection technique, which follows on (n,z) measurements made previously here and will have improved capabilities including larger solid angles, higher efficiency, and better signal to background ratios. For studying cross sections of low-energy neutron induced alpha reactions, Frisch-gridded ionization chamber is designed with segmented anodes for improving signal-to-noise ratio near reaction thresholds. Since double-differential cross sections on (n,p) and (n,a) reactions up to tens of MeV provide important information on deducing nuclear level density, the ionization chamber will be coupled with silicon strip detectors (DSSD) in order to stop energetic charged particles. In this paper, we will present the status of this development including the progress on detector design, calibrations and Monte Carlo simulations. This work is funded by the US Department of Energy - Los Alamos National Security, LLC under Contract DE-AC52-06NA25396.

  1. 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

  2. Hidden substances identification by detection of fast neutron induced γ rays using associated α particle technique

    International Nuclear Information System (INIS)

    Measurements have been made of characteristic gamma rays spectra from A(n,n'γ)A reactions induced by 14.1 MeV neutrons on bulk samples of different substances: C, H2O, SiO2, C3H6N6 and samples of soil. Background radiation was reduced by the associated alpha particle technique

  3. Cross sections of $\\alpha$-induced reactions for targets with masses $A \\approx 20-50$ at low energies

    CERN Document Server

    Mohr, Peter

    2015-01-01

    A simple reduction scheme using so-called reduced energies $E_{\\rm{red}}$ and reduced cross sections $\\sigma_{\\rm{red}}$ allows the comparison of heavy-ion induced reaction cross sections for a broad range of masses of projectile and target and over a wide energy range. A global behavior has been found for strongly bound projectiles whereas much larger reduced cross sections have been observed for weakly bound and halo projectiles. It has been shown that this simple reduction scheme works also well for $\\alpha$-particle induced reactions on heavy target nuclei, but very recently significant deviations have been seen for $\\alpha$+$^{33}$S and $\\alpha$+$^{23}$Na. Motivated by these unexpected discrepancies, the present study analyses $\\alpha$-induced reaction cross sections for targets with masses $A \\approx 20-50$. The study shows that the experimental data for $\\alpha$-induced reactions on nuclei with $A \\approx 20-50$ deviate slightly from the global behavior of reduced cross sections. However, in general th...

  4. 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

  5. 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.

  6. 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...

  7. 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.

  8. 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)%.

  9. 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.

  10. 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

  11. 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

  12. Interferon-alpha-induced deficits in novel object recognition are rescued by chronic exercise

    OpenAIRE

    Fahey, B.; Barlow, S; Day, J S; O Mara, S. M.

    2008-01-01

    The anti-viral drug interferon-alpha (IFN-alpha) is widely-known to induce psychiatric and cognitive effects in patients. Previous work has shown that physical exercise can have a positive effect against brain insult. We investigated the effects of a clinically-comparable treatment regime of IFN-alpha on cognitive function in male Wistar rats and assessed the impact of chronic treadmill running on the deficits generated by IFN-alpha. We found that IFN-alpha induced significant impairments in ...

  13. 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

  14. 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.

  15. Transforming growth factor alpha dramatically enhances oncogene-induced carcinogenesis in transgenic mouse pancreas and liver.

    OpenAIRE

    Sandgren, E P; Luetteke, N C; Qiu, T H; Palmiter, R D; Brinster, R L; Lee, D C

    1993-01-01

    To characterize the effect(s) of transforming growth factor alpha (TGF alpha) during multistage carcinogenesis, we examined tumor development in pancreas and liver of transgenic mice that coexpressed TGF alpha with either viral (simian virus 40 T antigens [TAg]) or cellular (c-myc) oncogenes. In pancreas, TGF alpha itself was not oncogenic, but it nevertheless dramatically accelerated growth of tumors induced by either oncogene alone, thereby reducing the host life span up to 60%. Coexpressio...

  16. 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...

  17. 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.

  18. 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.

  19. Investigation of electrically-active deep levels in single-crystalline diamond by particle-induced charge transient spectroscopy

    Science.gov (United States)

    Kada, W.; Kambayashi, Y.; Ando, Y.; Onoda, S.; Umezawa, H.; Mokuno, Y.; Shikata, S.; Makino, T.; Koka, M.; Hanaizumi, O.; Kamiya, T.; Ohshima, T.

    2016-04-01

    To investigate electrically-active deep levels in high-resistivity single-crystalline diamond, particle-induced charge transient spectroscopy (QTS) techniques were performed using 5.5 MeV alpha particles and 9 MeV carbon focused microprobes. For unintentionally-doped (UID) chemical vapor deposition (CVD) diamond, deep levels with activation energies of 0.35 eV and 0.43 eV were detected which correspond to the activation energy of boron acceptors in diamond. The results suggested that alpha particle and heavy ion induced QTS techniques are the promising candidate for in-situ investigation of deep levels in high-resistivity semiconductors.

  20. 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)

  1. Radiation induced structural changes in alpha-copper-zinc alloys

    International Nuclear Information System (INIS)

    During irradiation of alpha-copper-zinc alloys with high energy electrons and protons a decrease of the electrical resistivity due to an increase of the degree of short range order is observed through radiation enhanced diffusion followed by an increase of the electrical resistivity through the formation of radiation induced interstitial clusters. The initial formation rate of interstitial clusters increases about linearly with the displacement rate for electron and proton irradiation. The largest initial formation rate is found between 60 and 1300C becoming negligibly small above 1580C and decreases drastically below 600C. The dynamic steady state interstitial cluster concentration increases with decreasing irradiation temperature in the investigated temperature range between 158 and 400C. Above 1580C the formation rate of interstitial clusters is negligibly small. Thus the transition temperature for radiation induced interstitial cluster formation is 1580C, depending mainly on the migration activation energy of vacancies. The radiation induced interstitial clusters are precipitates in those alloys in which the diffusion rate of the undersized component atoms via an interstitialcy diffusion mechanism is larger than that of the other atoms

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. RAYLEIGH-TAYLOR STRENGTH EXPERIMENTS OF THE PRESSURE-INDUCED alpha->epsilon->alpha' PHASE TRANSITION IN IRON

    Energy Technology Data Exchange (ETDEWEB)

    Belof, J L; Cavallo, R M; Olson, R T; King, R S; Gray, G T; Holtkamp, D B; Chen, S R; Rudd, R E; Barton, N R; Arsenlis, A; Remington, B A; Park, H; Prisbrey, S T; Vitello, P A; Bazan, G; Mikaelian, K O; Comley, A J; Maddox, B R; May, M J

    2011-08-10

    We present here the first dynamic Rayleigh-Taylor (RT) strength measurement of a material undergoing solid-solid phase transition. Iron is quasi-isentropically driven across the pressure-induced bcc ({alpha}-Fe) {yields} hcp ({var_epsilon}-Fe) phase transition and the dynamic strength of the {alpha}, {var_epsilon} and reverted {alpha}{prime} phases have been determined via proton radiography of the resulting Rayleigh-Taylor unstable interface between the iron target and high-explosive products. Simultaneous velocimetry measurements of the iron free surface yield the phase transition dynamics and, in conjunction with detailed hydrodynamic simulations, allow for determination of the strength of the distinct phases of iron. Forward analysis of the experiment via hydrodynamic simulations reveals significant strength enhancement of the dynamically-generated {var_epsilon}-Fe and reverted {alpha}{prime}-Fe, comparable in magnitude to the strength of austenitic stainless steels.

  7. 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

  8. Cytokine vaccination: neutralising IL-1alpha autoantibodies induced by immunisation with homologous IL-1alpha

    DEFF Research Database (Denmark)

    Svenson, M; Hansen, M B; Thomsen, Allan Randrup; Diamant, M; Nansen, A; Rieneck, K; Otterness, I G; Bendtzen, K

    High-affinity IgG autoantibodies (aAb) to IL-1alpha are among the most frequently found aAb to cytokines in humans. To establish an animal model with aAb to IL-1alpha, we immunised mice with recombinant murine IL-1alpha. Unprimed and Bacille Calmette-Guérin (BCG)-primed BALB/cA mice were vaccinat...

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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)

  14. 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.)

  15. 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

  16. 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

  17. 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.

  18. 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)

  19. Alpha particle induced reactions on natCr up to 39 MeV: Experimental cross-sections, comparison with theoretical calculations and thick target yields for medically relevant 52gFe production

    International Nuclear Information System (INIS)

    Thin natCr targets were obtained by electroplating, using 23.75 μm Cu foils as backings. In five stacked foil irradiations, followed by high resolution gamma spectroscopy, the cross sections for production of 52gFe, 49,51cumCr, 52cum,54,56cumMn and 48cumV in Cr and 61Cu,68Ga in Cu were measured up to 39 MeV incident α-particle energy. Reduced uncertainty is obtained by simultaneous remeasurement of the natCu(α,x)67,66Ga monitor reactions over the whole energy range. Comparisons with the scarce literature values and results from the TENDL-2013 on-line library, based on the theoretical code family TALYS-1.6, were made. A discussion of the production routes for 52gFe with achievable yields and contamination rates was made

  20. 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.

  1. 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

  2. Particle induced X-ray emission

    International Nuclear Information System (INIS)

    The accelerator based ion beam technique of Particle Induced X-ray Emission (PIXE) is discussed in some detail. This report pulls together all major reviews and references over the last ten years and reports on PIXE in vacuum and using external beams. The advantages, limitations, costs and types of studies that may be undertaken using an accelerator based ion beam technique such as PIXE, are also discussed. 25 refs., 7 tabs., 40 figs

  3. 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

  4. 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

  5. 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.

  6. 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...

  7. 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)

  8. Measurement of the track etch rates along proton and alpha particle trajectories in CR-39 and calculation of the detection efficiency

    CERN Document Server

    Dörschel, B; Hermsdorf, D; Kadner, K; Kuehne, H

    1999-01-01

    Computation of the neutron response of CR-39 detectors needs to simulate the track formation by neutron induced charged particles taking into account the bulk etch rate and the track etch rate varying along the particle trajectories. The latter one was determined experimentally by track length measurement. The results allowed to derive the relationship between the track etch rate and the restricted energy loss of the charged particles. On this basis, the geometrical track parameters and track etch rates as well as the critical angle of particle incidence could be determined for protons and alpha particles in the energy range from 0.2 to 8.8 MeV. The energy dependence of the critical angle enabled to determine the detection efficiency for a charged particle of given energy and direction.

  9. Alpha particle induced reactions on {sup nat}Cr up to 39 MeV: Experimental cross-sections, comparison with theoretical calculations and thick target yields for medically relevant {sup 52g}Fe production

    Energy Technology Data Exchange (ETDEWEB)

    Hermanne, A.; Adam Rebeles, R. [Cyclotron Laboratory, Vrije Universiteit Brussel, Brussel 1090 (Belgium); Tárkányi, F.; Takács, S. [Institute of Nuclear Research, Hungarian Academy of Science, 4026 Debrecen (Hungary)

    2015-08-01

    Thin {sup nat}Cr targets were obtained by electroplating, using 23.75 μm Cu foils as backings. In five stacked foil irradiations, followed by high resolution gamma spectroscopy, the cross sections for production of {sup 52g}Fe, {sup 49,51cum}Cr, {sup 52cum,54,56cum}Mn and {sup 48cum}V in Cr and {sup 61}Cu,{sup 68}Ga in Cu were measured up to 39 MeV incident α-particle energy. Reduced uncertainty is obtained by simultaneous remeasurement of the {sup nat}Cu(α,x){sup 67,66}Ga monitor reactions over the whole energy range. Comparisons with the scarce literature values and results from the TENDL-2013 on-line library, based on the theoretical code family TALYS-1.6, were made. A discussion of the production routes for {sup 52g}Fe with achievable yields and contamination rates was made.

  10. Atomic force microscopic neutron-induced alpha-autoradiography for boron imaging in detailed cellular histology

    International Nuclear Information System (INIS)

    The information on subcellular microdistribution of 10B compounds a cell is significant to evaluate the efficacy of boron neutron capture therapy (BNCT) because the damage brought by the released alpha/lithium particles is highly localized along their path, and radiation sensitivity is quite different among each cell organelles. In neutron-induced alpha-autoradiography (NIAR) technique, 10B can be measured as tracks for the energetic charged particles from 10B(n, alpha)7Li reactions in solid state track detectors. To perform the NIAR at intracellular structure level for research of 10B uptake and/or microdosimetry in BNCT, we have developed high-resolution NIAR method with an atomic force microscope (AFM). AFM has been used for analyses of biological specimens such as proteins, DNAs and surface of living cells have, however, intracellular detailed histology of cells has been hardly resolved with AFM since flat surface of sectioned tissue has quite less topographical contrast among each organelle. In our new sample preparation method using UV processing, materials that absorb UV in a semi-thin section are selectively eroded and vaporized by UV exposure, and then fine relief for cellular organelles such as mitochondria, endoplasmic reticulum, filament structure and so on reveals on flat surface of the section, which can be observed with an AFM. The imaging resolution was comparable to TEM imaging of cells. This new method provides fast and cost-effective observation of histological sections with an AFM. Combining this method with NIAR technique, intracellular boron mapping would be possible. (author)

  11. Observation of alpha particle loss from JET plasmas during ion cyclotron resonance frequency heating using a thin foil Faraday cup detector array

    International Nuclear Information System (INIS)

    The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of ∼2 MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential.

  12. 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.

  13. Particle dynamics in asymmetry-induced transport

    International Nuclear Information System (INIS)

    The particle dynamics of asymmetry-induced transport are studied using a single-particle computer simulation. For the case of a helical asymmetry with axial and azimuthal wavenumbers (k,l) and with periodic boundary conditions, behaviors consistent with analytical theory are observed. For the typical experimental case of a standing wave asymmetry, the code reveals dynamical behaviors not included in the analytical theory of this transport. The resonances associated with the two constituent helical waves typically overlap and produce a region of stochastic motion. In addition, particles near the radius where the asymmetry frequency ω matches l times the ExB rotation frequency ωR can be trapped in the potential of the applied asymmetry and confined to one end of the device. Both behaviors are associated with large radial excursions and mainly affect particles with low velocities, i.e., vzT/k, where ωT is the trapping frequency. For the case of a helical asymmetry with specularly reflecting boundaries, large radial excursions are observed for all velocities near the radius, where ω=lωR. Minor modifications to these results are observed when the code is run with realistic end potentials

  14. 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)

  15. 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.).

  16. alpha-Amanitin induced apoptosis in primary cultured dog hepatocytes.

    Directory of Open Access Journals (Sweden)

    Adam Szelag

    2010-06-01

    Full Text Available Amatoxin poisoning is caused by mushroom species belonging to the genera Amanita, Galerina and Lepiota with the majority of lethal mushroom exposures attributable to Amanita phalloides. High mortality rate in intoxications with these mushrooms is principally a result of the acute liver failure following significant hepatocyte damage due to hepatocellular uptake of amatoxins. A wide variety of amatoxins have been isolated; however, alpha-amanitin (alpha-AMA appears to be the primary toxin. Studies in vitro and in vivo suggest that alpha-AMA does not only cause hepatocyte necrosis, but also may lead to apoptotic cell death. The objective of this study was to evaluate the complex hepatocyte apoptosis in alpha-AMA cytotoxicity. All experiments were performed on primary cultured canine hepatocytes. The cells were incubated for 12 h with alpha-AMA at a final concentration of 1, 5, 10 and 20 microM. Viability test (MTT assay, apoptosis evaluation (TUNEL reaction, detection of DNA laddering and electron microscopy were performed at 6 and 12 h of exposure to alpha-AMA. There was a clear correlation between hepatocyte viability, concentration of alpha-AMA and time of exposure to this toxin. The decline in cultured dog hepatocyte viability during the exposure to alpha-AMA is most likely preceded by enhanced cellular apoptosis. Our results demonstrate that apoptosis might contribute to pathogenesis of the severe liver injury in the course of amanitin intoxication, particularly during the early phase of poisoning.

  17. 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

  18. 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.

  19. 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)

  20. Mechanism of alpha-lipoic acid in attenuating kanamycin-induced ototoxicity☆

    OpenAIRE

    Wang, Aimei; Hou, Ning; Bao, Dongyan; Liu, Shuangyue; XU, TAO

    2012-01-01

    In view of the theory that alpha-lipoic acid effectively prevents cochlear cells from injury caused by various factors such as cisplatin and noise, this study examined whether alpha-lipoic acid can prevent kanamycin-induced ototoxicity. To this end, healthy BALB/c mice were injected subcutaneously with alpha-lipoic acid and kanamycin for 14 days. Auditory brainstem response test showed that increased auditory brainstem response threshold shifts caused by kanamycin were significantly inhibited...

  1. Particle-induced amorphization complex ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, R.C.; Wang, Lu-Min

    1996-02-16

    The presently funded three-year research program, supported by the Division of Materials Sciences of the Office of Basic Energy Sciences, was initiated on August 1, 1993; during the period in which the grant will have been active, $249,561 of support have been provided to date with an additional $79,723 to be spent during the third, final year (ending July 30, 1996). The primary purpose of the program is to develop an understanding of heavy-particle radiation effects -- {alpha}-recoil nuclei, fission fragments, ion-irradiations -- on ceramic materials and the thermal annealing mechanisms by which crystallinity might be restored. During the past two years, we have completed major studies on zircon (ZrSiO{sub 4}), olivine (Mg{sub 2}SiO{sub 4} and ten other compositions), spinel (MgAl{sub 2}O{sub 4} and four other compositions), and silica polymorphs (quartz, coesite and stishovite), as well as berlinite (AlPO{sub 4}) which is isomorphous with quartz. In addition, based on the above research, we propose the use of zircon as a host phase for the immobilization of plutonium resulting from weapons dismantlement.

  2. 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.)

  3. PGC-1alpha mediates exercise-induced skeletal muscle VEGF expression in mice

    DEFF Research Database (Denmark)

    Leick, Lotte; Hellsten, Ylva; Fentz, Joachim;

    2009-01-01

    littermate wild-type (WT) mice were submitted to either 1) 5 wk of exercise training, 2) lifelong (from 2 to 13 mo of age) exercise training in activity wheel, 3) a single exercise bout, or 4) 4 wk of daily subcutaneous AICAR or saline injections. In skeletal muscle of PGC-1alpha KO mice, VEGF protein...... skeletal muscle VEGF protein expression approximately 50% in WT mice but with no effect in PGC-1alpha KO mice. Furthermore, a training-induced prevention of an age-associated decline in VEGF protein content was observed in WT but not in PGC-1alpha KO muscles. In addition, repeated AICAR treatments...... increased skeletal muscle VEGF protein expression approximately 15% in WT but not in PGC-1alpha KO mice. This study shows that PGC-1alpha is essential for exercise-induced upregulation of skeletal muscle VEGF expression and for a training-induced prevention of an age-associated decline in VEGF protein...

  4. 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...

  5. 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

  6. 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

  7. 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

  8. 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)

  9. 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)

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Estimation of α-particle induced hot spot size in Nb film using Abrikosov vortices

    International Nuclear Information System (INIS)

    A new experimental method for estimation of alpha-particle induced hot spot size in Nb films is proposed. The method is based on the jump-like motion of Abrikosov vortices induced by the impact of a single alpha particle (241Am 5.5 MeV) on a superconducting film. Preliminary experiments were carried out on a high quality 'small' Nb-AlOx-Nb Josephson tunnel junction with circular geometry and area 2500 μm2 (length smaller than λj) at T = 4.2 K. A preliminary value of d* = 2.5 μm is obtained for the dimension of the hot spot region. (author)

  16. Light-particle emission in reactions induced with carbon and oxygen ions

    International Nuclear Information System (INIS)

    Preliminary results are presented from three different experiments in which light particles emitted during the course of heavy-ion-induced reactions have been studied. The common primary motivation for undertaking these studies was to determine the nature and extent of nonequilibrium particle emission. The three experiments involved measurements of energies, angular correlations, and multiplicities of neutrons or alpha particles emitted in coincidence with deeply inelastic products or with evaporation residues produced as follows: neutrons from reactions of 16O with 93Nb at 12.9 MeV/u; alphas produced in the same system; and neutrons produced in 12C reactions with 158Gd and in 13C reactions with 157Gd at about 12.4 MeV/u. 3 figures

  17. Neuroprotective Effects of Alpha Lipoic Acid on Haloperidol-Induced Oxidative Stress in the Rat Brain

    Directory of Open Access Journals (Sweden)

    Perera Joachim

    2011-03-01

    Full Text Available Abstract Haloperidol is an antipsychotic drug that exerts its' antipsychotic effects by inhibiting dopaminergic neurons. Although the exact pathophysiology of haloperidol extrapyramidal symptoms are not known, the role of reactive oxygen species in inducing oxidative stress has been proposed as one of the mechanisms of prolonged haloperidol-induced neurotoxicity. In the present study, we evaluate the protective effect of alpha lipoic acid against haloperidol-induced oxidative stress in the rat brain. Sprague Dawley rats were divided into control, alpha lipoic acid alone (100 mg/kg p.o for 21 days, haloperidol alone (2 mg/kg i.p for 21 days, and haloperidol with alpha lipoic acid groups (for 21 days. Haloperidol treatment significantly decreased levels of the brain antioxidant enzymes super oxide dismutase and glutathione peroxidase and concurrent treatment with alpha lipoic acid significantly reversed the oxidative effects of haloperidol. Histopathological changes revealed significant haloperidol-induced damage in the cerebral cortex, internal capsule, and substantia nigra. Alpha lipoic acid significantly reduced this damage and there were very little neuronal atrophy. Areas of angiogenesis were also seen in the alpha lipoic acid-treated group. In conclusion, the study proves that alpha lipoic acid treatment significantly reduces haloperidol-induced neuronal damage.

  18. 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.

  19. Study of the antioxidant effect of {alpha}-tocopherol on low-density lipoprotein peroxidation induced at low and high {gamma}-radiation dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, Abdelouahed [Research Centre on Aging and Department of Medicine, University of Sherbrooke, Sherbrooke, QC, J1H 4C4 (Canada)]. E-mail: abdelouahed.khalil@usherbrooke.ca; Milochevitch, Christelle [Research Centre on Aging and Department of Medicine, University of Sherbrooke, Sherbrooke, QC, J1H 4C4 (Canada)

    2005-02-01

    It is well known that vitamin E ({alpha}-tocopherol, {alpha}-toc) is a very efficient lipid soluble antioxidant and several studies showed its beneficial action in the prevention and reduction of atherosclerosis. However, some in vitro studies suggest a prooxidant role of vitamin E, which could occur under given circumstances. This study was thus designed to investigate the antioxidant vs. prooxidant effect of vitamin E with regards to LDL peroxidation induced under different oxidative stress conditions. LDL was enriched with {alpha}-tocopherol and different {alpha}-toc/LDL ratios were studied (8.0{+-}2.5, 14.3{+-}3.0, 33.3{+-}3.7, 42.7{+-}3.5 and 48.2{+-}4.5 molecules of {alpha}-toc/LDL particle). Enriched and control LDL were oxidized by action of {sup {center_dot}}OH and O{sub 2}{sup {center_dot}}{sup -} free radicals produced by {gamma}-radiolysis at different dose rates. Susceptibility of LDL to oxidation was examined by the measure of conjugated diene and TBARS formation as well as LDL endogenous {alpha}-toc disappearance. Increasing LDL {alpha}-toc concentration reduced the LDL susceptibility to oxidation and their oxidizability. {alpha}-toc disappearance rates were comprised between 43 and 8.3x10{sup -10} M s{sup -1} and decreased with the radiation dose rate. Our results support an antioxidant role for {alpha}-tocopherol at high and low oxidative stress conditions.

  20. Investigation of the α-particle induced nuclear reactions on natural molybdenum

    International Nuclear Information System (INIS)

    Highlights: ► Excitation function measurement of α-particle induced reactions on natural molybdenum up to 40 MeV. ► Model code calculations with EMPIRE-II, EMPIRE3.1, ALICE and TALYS. ► Integral production yield calculation. ► Comparison with deuteron and proton production. ► Monitor reactions for α-irradiations. - Abstract: Cross-sections of alpha particle induced nuclear reactions on natural molybdenum have been studied in the frame of a systematic investigation of charged particle induced nuclear reactions on metals for different applications. The excitation functions of 93mTc, 93gTc(m+), 94mTc, 94gTc, 95mTc, 95gTc, 96gTc(m+), 99mTc, 93mMo, 99Mo(cum), 90Nb(m+), 94Ru, 95Ru,97Ru, 103Ru and 88Zr were measured up to 40 MeV alpha energy by using a stacked foil technique and activation method. The main goals of this work were to get experimental data for accelerator technology, for monitoring of alpha beam, for thin layer activation technique and for testing nuclear reaction theories. The experimental data were compared with critically analyzed published data and with the results of model calculations, obtained by using the ALICE-IPPE, EMPIRE and TALYS codes (TENDL-2011).

  1. 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.

  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

    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.

  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

    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

  4. 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.

  5. 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

  6. 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

  7. 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)

  8. 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

  9. 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)

  10. 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

  11. 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)

  12. 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.

  13. Evaluation of (alpha,n) Induced Neutrons as a Background for Dark Matter Experiments

    OpenAIRE

    Mei, D.-M.; C. Zhang; Hime, A.

    2008-01-01

    Neutrons from ($\\alpha$,n) reactions through thorium and uranium decays are important sources of background for direct dark matter detection. The neutron yields and energy spectra from a range of materials that are used to build dark matter detectors are calculated and tabulated. In addition to thorium and uranium decays, we found that $\\alpha$ particles from samarium, often the dopant of the window materials of photomultiplier tubes (PMT), are also an important source of neutron yield. The r...

  14. Hypoxia-inducible factor 2alpha binds to cobalt in vitro.

    Science.gov (United States)

    Yuan, Y; Beitner-Johnson, D; Millhorn, D E

    2001-11-01

    The hypoxia-inducible factor (HIF) activates the expression of genes that contain a hypoxia response element (HRE). The alpha subunit of the HIF transcription factors is degraded by proteasome pathways during normoxia, but stabilized under hypoxic conditions. It has previously been established that cobalt causes accumulation of HIF-2alpha and HIF-1alpha. However, little is known about the mechanism by which cobalt mimics hypoxia and stabilizes these transcription factors. We show here that cobalt binds directly to HIF-2alpha in vitro with a high affinity and in an oxygen-dependent manner. We found that HIF-2alpha, which had been stabilized with a proteasome inhibitor, could bind to cobalt, whereas hypoxia-stabilized HIF-2alpha could not. Mutations within the oxygen-dependent degradation domain of HIF-2alpha prevented cobalt binding and led to accumulation of HIF-2alpha during normoxia. This suggests that transition metal such as iron may play a role in regulation of HIF-2alpha in vivo. PMID:11688986

  15. Alpha radiation-induced alterations of the proliferation kinetics, chromatin structure and gene expression in mammalian cells

    International Nuclear Information System (INIS)

    Exponentially growing mammalian cells were exposed to 3.4 MeV alpha particles. The chromatin of cells arrested in G2 by alpha irradiation was severely damaged, though all cells were still capable to condensate their chromatin after fusion with mitotic cells. In addition to the common types of aberrations (breaks, gaps, dicentrics and exchanges) cells were found possessing one or more chromosomes with long stretches of undercondensed chromatin. Repair of these lesions was indicated by site specific unscheduled DNA synthesis and by the observation that condensation of these regions improved during G2 arrest. Furthermore, during G2 arrest the synthesis of two cellular proteins was stimulated. This was studied by two-dimensional gel electrophoresis of 35S-methionine labeled cellular proteins. All these findings provided evidence that radiation-induced G2 arrest is caused by chromatin damage, which prevents regular chromosome condensation for mitosis. (orig./MG)

  16. alpha 1-Adrenoceptors modulate citalopram-induced serotonin release

    NARCIS (Netherlands)

    Rea, Kieran; Folgering, Joost; Westerink, Ben H. C.; Cremers, Thomas I. F. H.

    2010-01-01

    Previous studies suggest that noradrenaline may regulate serotonergic (5-HT) neurotransmission at the serotonin cell body and noradrenaline nerve terminal. Using microdialysis coupled to HPLC, we investigated the effects of alpha 1-adrenoceptor manipulation on extracellular serotonin levels in the v

  17. 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

  18. 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.

  19. 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

  20. 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

  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. 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.

  3. 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.

  4. Isotope production in light charged particle induced fission

    International Nuclear Information System (INIS)

    In this thesis the production of neutron-rich isotopes in the mass region A=96-120 has been studied. Their yields have been extensively studied with the IGISOL isotope separator in the 238U (p,f) reaction. Deuteron and alpha particle induced reactions have also been investigated. In connection with this work several new isotopes have been identified for the first time. Specifically, the decays of 110Tc and 112Tc are discussed. Cumulative mass distributions as well as independent isotopic distributions have been constructed. In the method used here the total kinetic energy of the fragments is integrated so that there is no energy selection and the yields are post-neutron emission values. A theoretical model described in one of the joined papers has been used to extract the preneutron emission yields. These results can be used for estimating the possibilities of production of new neutron-rich isotopes, e.g. at the IGISOL facility. In addition, they are necessary to help refining the existing fission models. (orig.) (50 refs., 9 figs.)

  5. 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

  6. 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).

  7. 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)

  8. 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...

  9. 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

  10. 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.

  11. 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)

  12. 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)

  13. 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

  14. IgE-mediated basophil tumour necrosis factor alpha induces matrix metalloproteinase-9 from monocytes

    DEFF Research Database (Denmark)

    Falkencrone, Sidsel; Poulsen, Lars K.; Bindslev-Jensen, Carsten; Andersen, Anders Woetmann; Ødum, Niels; Poulsen, Britta Cathrina; Blom, L.; Jensen, B. M.; Gibbs, B. F.; Yasinska, I. M.; Sumbayev, V. V.; Skov, P. S.

    2013-01-01

    IgE-mediated activation of mast cells has been reported to induce the release of tumour necrosis alpha (TNF-α), which may display autocrine effects on these cells by inducing the generation of the tissue remodelling protease matrix metalloproteinase-9 (MMP-9). While mast cells and basophils have...

  15. Physiological and morphological responses induced by α-particle radiation on Arabidopsis thaliana embryos.

    Science.gov (United States)

    Ren, J; Liu, L; Jin, X L; Fu, S L; Ding, Z C

    2014-01-01

    Alpha (α)-particle radiation has been thoroughly studied in the occupational and residential environments, but biological mechanisms induced by α-particle radiation on plants are not clearly understood. In this study, radiation effects were examined using different total doses (1, 10, 100 Gy, respectively) of 241Am, α-particle on Arabidopsis embryos. No significant difference in the germination percentage was observed between the 3 levels of doses and the control. Germination speed and root length were increased by treatment with the 1-Gy dose of a-particles, and decreased by treatment with 10- and 100-Gy doses. Moreover, the bending degree of roots increased with radiation dose, and the roots showed an "S" shape when treated with the 100-Gy dose. Root bending under the 100-Gy dose was inhibited by scavengers of reactive oxygen species (ROS). Root gravitropism and root length may respond to the consistency of ROS induced by irradiation. Further analysis of the physiological effects revealed that an increase in a-particle radiation intensity enhanced the activity of catalase and the content of malondialdehyde, but superoxide dismutase activity was reduced by treatment with 100-Gy radiation of a-particles, suggesting that the high linear energy transfer of a-particles may cause a relatively high level of membrane lipid preoxidation and high accumulation of ROS. ROS showed both physiological and morphological responses following exposure to α-particle radiation in Arabidopsis embryos. PMID:25501166

  16. The shear-induced alpha-effect and long-term variations in solar dynamo

    OpenAIRE

    Pipin, V. V.

    2007-01-01

    The consequences of the shear-induced alpha effect to the long-term modulation of magnetic activity are examined with the help of the axisymmetric numerical dynamo model that includes the self-consistent description of the angular momentum balance, heat transport and magnetic field generation in the spherical shell. We find that the shear contributions to alpha effect can complicate the long-term behaviour of the large-scale magnetic activity and differential rotation in nonlinear dynamo. Add...

  17. The Effect of Alpha-Lipoic Acid on Mitochondrial Superoxide and Glucocorticoid-Induced Hypertension

    OpenAIRE

    Sharon L. H. Ong; Harpreet Vohra; Yi Zhang; Matthew Sutton; Whitworth, Judith A

    2013-01-01

    Aims. To examine the effect of alpha-lipoic acid, an antioxidant with mitochondrial superoxide inhibitory properties, on adrenocorticotrophic hormone- (ACTH-HT) and dexamethasone-induced hypertensions (DEX-HT) in rats and if any antihypertensive effect is mediated via mitochondrial superoxide inhibition. Methods. In a prevention study, rats received ground food or alpha-lipoic-acid-laced food (10 mg/rat/day) for 15 nights. Saline, adrenocorticotrophic hormone (ACTH, 0.2 mg/kg/day), or dexamet...

  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. Proton and alpha evaporation spectra in low energy 12C and 16O induced reactions

    Indian Academy of Sciences (India)

    E T Mirgle; D R Chakrabarty; V M Datar; Suresh Kumar; A Mitra; H H Oza

    2006-08-01

    Proton and alpha particle spectra have been measured in the 12C+93Nb and 12C+58Ni reactions at E(12C) = 40 and 50 MeV and in the 16O+93Nb reaction at E(16O) = 75 MeV. The spectra are compared with the statistical model calculations. The shapes of the calculated spectra are in agreement with experimental data except for the alpha spectrum in the 12C+93Nb reaction at 40 MeV. The observed evaporation bump is at ∼ 2 MeV lower energy compared to the calculated one. This discrepancy could imply alpha particle emission from a deformed configuration before compound nucleus formation at this near Coulomb barrier beam energy.

  20. 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.

  1. 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.

  2. Dominant-negative CK2alpha induces potent effects on circadian rhythmicity.

    Directory of Open Access Journals (Sweden)

    Elaine M Smith

    2008-01-01

    Full Text Available Circadian clocks organize the precise timing of cellular and behavioral events. In Drosophila, circadian clocks consist of negative feedback loops in which the clock component PERIOD (PER represses its own transcription. PER phosphorylation is a critical step in timing the onset and termination of this feedback. The protein kinase CK2 has been linked to circadian timing, but the importance of this contribution is unclear; it is not certain where and when CK2 acts to regulate circadian rhythms. To determine its temporal and spatial functions, a dominant negative mutant of the catalytic alpha subunit, CK2alpha(Tik, was targeted to circadian neurons. Behaviorally, CK2alpha(Tik induces severe period lengthening (approximately 33 h, greater than nearly all known circadian mutant alleles, and abolishes detectable free-running behavioral rhythmicity at high levels of expression. CK2alpha(Tik, when targeted to a subset of pacemaker neurons, generates period splitting, resulting in flies exhibiting both long and near 24-h periods. These behavioral effects are evident even when CK2alpha(Tik expression is induced only during adulthood, implicating an acute role for CK2alpha function in circadian rhythms. CK2alpha(Tik expression results in reduced PER phosphorylation, delayed nuclear entry, and dampened cycling with elevated trough levels of PER. Heightened trough levels of per transcript accompany increased protein levels, suggesting that CK2alpha(Tik disturbs negative feedback of PER on its own transcription. Taken together, these in vivo data implicate a central role of CK2alpha function in timing PER negative feedback in adult circadian neurons.

  3. 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).

  4. Temperature dependence of alpha-induced scintillation in the 1,1,4,4-tetraphenyl-1,3-butadiene wavelength shifter

    CERN Document Server

    Veloce, L M; Di Stefano, P C F; Noble, A J; Boulay, M G; Nadeau, P; Pollmann, T; Clark, M; Piquemal, M; Schreiner, K

    2015-01-01

    Liquid noble gas based particle detectors often use the organic wavelength shifter 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) which shifts UV scintillation light to the visible regime, facilitating its detection, but which also can scintillate on its own. Dark matter searches based on this type of detector commonly rely on pulse-shape discrimination (PSD) for background mitigation. Alpha-induced scintillation therefore represents a possible background source in dark matter searches. The timing characteristics of this scintillation determine whether this background can be mitigated through PSD. We have therefore characterized the pulse shape and light yield of alpha induced TPB scintillation at temperatures ranging from 300 K down to 4 K, with special attention given to liquid noble temperatures. We find that the pulse shapes and light yield depend strongly on temperature. In addition, the significant contribution of long time constants above ~50 K provides an avenue for discrimination between alpha decay events ...

  5. Neuroprotective Effects of Alpha Lipoic Acid on Haloperidol-Induced Oxidative Stress in the Rat Brain

    OpenAIRE

    Perera Joachim; Tan Joon; Jeevathayaparan S; Chakravarthi Srikumar; Haleagrahara Nagaraja

    2011-01-01

    Abstract Haloperidol is an antipsychotic drug that exerts its' antipsychotic effects by inhibiting dopaminergic neurons. Although the exact pathophysiology of haloperidol extrapyramidal symptoms are not known, the role of reactive oxygen species in inducing oxidative stress has been proposed as one of the mechanisms of prolonged haloperidol-induced neurotoxicity. In the present study, we evaluate the protective effect of alpha lipoic acid against haloperidol-induced oxidative stress in the ra...

  6. 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)

  7. TCR-induced Akt serine 473 phosphorylation is regulated by protein kinase C-alpha

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lifen [Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan (China); Section of Nephrology, Department of Medicine, The University of Chicago, Chicago, IL 60637 (United States); The Committees on Immunology, The University of Chicago, Chicago, IL 60637 (United States); Qiao, Guilin; Ying, Haiyan [Section of Nephrology, Department of Medicine, The University of Chicago, Chicago, IL 60637 (United States); The Committees on Immunology, The University of Chicago, Chicago, IL 60637 (United States); Zhang, Jian, E-mail: jzhang@medicine.bsd.uchicago.edu [Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan (China); Section of Nephrology, Department of Medicine, The University of Chicago, Chicago, IL 60637 (United States); The Committees on Immunology, The University of Chicago, Chicago, IL 60637 (United States); The Committees on Molecular Medicine, The University of Chicago, Chicago, IL 60637 (United States); Yin, Fei, E-mail: yf2323@hotmail.com [Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan (China)

    2010-09-10

    Research highlights: {yields} Conventional PKC positively regulates TCR-induced phosphorylation of Akt. {yields} PKC-alpha is the PDK-2 responsible for phosphorylating Akt at Ser{sup 473} upon TCR stimulation. {yields} Knockdown of PKC-alpha decreases TCR-induced Akt phosphorylation. -- Abstract: Akt signaling plays a central role in T cell functions, such as proliferation, apoptosis, and regulatory T cell development. Phosphorylation at Ser{sup 473} in the hydrophobic motif, along with Thr{sup 308} in its activation loop, is considered necessary for Akt function. It is widely accepted that phosphoinositide-dependent kinase 1 (PDK-1) phosphorylates Akt at Thr{sup 308}, but the kinase(s) responsible for phosphorylating Akt at Ser{sup 473} (PDK-2) remains elusive. The existence of PDK-2 is considered to be specific to cell type and stimulus. PDK-2 in T cells in response to TCR stimulation has not been clearly defined. In this study, we found that conventional PKC positively regulated TCR-induced Akt Ser{sup 473} phosphorylation. PKC-alpha purified from T cells can phosphorylate Akt at Ser{sup 473} in vitro upon TCR stimulation. Knockdown of PKC-alpha in T-cell-line Jurkat cells reduced TCR-induced phosphorylation of Akt as well as its downstream targets. Thus our results suggest that PKC-alpha is a candidate for PDK-2 in T cells upon TCR stimulation.

  8. 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

  9. 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.

  10. 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

  11. 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)

  12. Investigation of the α-particle induced nuclear reactions on natural molybdenum

    International Nuclear Information System (INIS)

    Complete text of publication follows. Cross-sections of alpha particle induced nuclear reactions on natural molybdenum have been studied in the frame of a systematic investigation of charged particle induced nuclear reactions on metals for different applications. The excitation functions of 93mTc, 93gTc(m+), 94mTc, 94gTc, 95mTc, 95gTc, 96gTc(m+), 99mTc, 93mMo, 99Mo(cum), 90Nb(m+), 94Ru, 95Ru, 97Ru, 103Ru and 88Zr were measured up to 40 MeV alpha energy by using a stacked foil technique and activation method. The main goals of this work were to get experimental data for accelerator technology, for monitoring of alpha beam, for thin layer activation technique and for testing nuclear reaction theories. The experimental data were compared with critically analyzed published data and with the results of model calculations, obtained by using the ALICE-IPPE, EMPIRE and TALYS codes (TENDL-2011). Yield versus energy curves are calculated from the measured data (Figs. 1-4) for the radioisotopes having special importance in one of the application fields.

  13. 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

  14. 5-Azacytidine treatment of HA-A melanoma cells induces Sp1 activity and concomitant transforming growth factor alpha expression.

    OpenAIRE

    Shin, T H; Paterson, A. J.; Grant, J H; Meluch, A A; Kudlow, J E

    1992-01-01

    Evidence indicates DNA methylation as a part of the regulatory machinery controlling mammalian gene expression. The human melanoma cell line HA-A expresses low levels of transforming growth factor alpha (TGF-alpha). TGF-alpha mRNA accumulated, however, in response to DNA demethylation induced by a nucleoside analog, 5-azacytidine (5-azaC). The importance of DNA methylation in the TGF-alpha promoter region was examined by a transient transfection assay with luciferase reporter plasmids contain...

  15. Stability and {alpha}-particle confinement in the Sphellamak reactor concept

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, W. Anthony; Fischer, Olivier [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

    2000-10-01

    The Sphellamak is a coreless hybrid system with Tokamak, Stellarator and Spheromak features.The absence of a central conductor permits the realisation of a compact toroidal system, as internal shielding becomes un- necessary. With a peaked toroidal current profile, a sequence of reactor-sized Sphellamak equilibria is computed numerically in which the current in the helical coils I{sub hc} is varied while the toroidal plasma current I{sub p} = -30 MA and the volume average {beta} = 7.3% remain fixed. Ideal global external kink modes are weakly unstable but indicate stability for I{sub hc} > 138 MA. The local ideal magnetohydrodynamic stability criteria are satisfied in the range 42 MA < I{sub hc} < 122 MA. The peaked toroidal current generates local maximal of the modulus of the magnetic field strength in the central region of the plasma, which has very favourable implications for energetic and thermal particle confinement. This is confirmed through the computation of a very small {alpha}-particle guiding centre orbit loss fraction. (author) [French] Le Sphellamak est un systeme hybride sans noyau central compose par des elements de Tokamak, de Stellerateur et de Spheromak. L'absence de colonne centrale permet la realisation d 'un systeme toroidal compact puisque le manteau de protection interne ne devient plus necessaire. Avec un profil de courant pique, une sequence d 'equilibres Sphellamak de dimension reacteur est calculee numeriquement en variant le courant des bobines helicoidales I{sub hc} tout en fixant le courant toroidal du plasma I{sub p} = -30 MA ainsi que la moyenne volumique {beta} = 7.3%. Les modes globaux externes du type kink sont faiblement instables mais suffisent a garantir la stabilite pour I{sub hc} > 138 MA. Les criteres de stabilite magnetohydrodynamique ideale locale sont realises pour des courants de 42 MA < I{sub hc} < 122 MA. Le courant toroidal pique pro- duit localement des valeurs maximales pour le module du champs

  16. Evaluation of (alpha,n) Induced Neutrons as a Background for Dark Matter Experiments

    CERN Document Server

    Mei, D -M; Hime, A

    2008-01-01

    Neutrons from ($\\alpha$,n) reaction through thorium and uranium decays are important sources of background for direct dark matter detection. Neutron yield and energy spectrum from a range of materials that are used to build dark matter detectors are calculated and tabulated. In addition to thorium and uranium decays, we found that $\\alpha$ particles from samarium that is often doped in the window material of photomultiplier (PMT) are also an important source of neutron yield. The results in this paper can be used as the input in the Monte Carlo simulation for many materials that will be used for next generation experiments.

  17. Alpha spectrometric characterization of process-related particle size distributions from active particle sampling at the Los Alamos National Laboratory uranium foundry

    International Nuclear Information System (INIS)

    Uranium particles within the respirable size range pose a significant hazard to the health and safety of workers. Significant differences in the deposition and incorporation patterns of aerosols within the respirable range can be identified and integrated into sophisticated health physics models. Data characterizing the uranium particle size distribution resulting from specific foundry-related processes are needed. Using personal air sampling cascade impactors, particles collected from several foundry processes were sorted by activity median aerodynamic diameter onto various Marple substrates. After an initial gravimetric assessment of each impactor stage, the substrates were analyzed by alpha spectrometry to determine the uranium content of each stage. Alpha spectrometry provides rapid non-distructive isotopic data that can distinguish process uranium from natural sources and the degree of uranium contribution to the total accumulated particle load. In addition, the particle size bins utilized by the impactors provide adequate resolution to determine if a process particle size distribution is: lognormal, bimodal, or trimodal. Data on process uranium particle size values and distributions facilitate the development of more sophisticated and accurate models for internal dosimetry, resulting in an improved understanding of foundry worker health and safety.

  18. Computation of Cosmic Ray Ionization and Dose at Mars: a Comparison of HZETRN and Planetocosmics for Proton and Alpha Particles

    Science.gov (United States)

    Gronoff, Guillaume; Norman, Ryan B.; Mertens, Christopher J.

    2014-01-01

    The ability to evaluate the cosmic ray environment at Mars is of interest for future manned exploration. To support exploration, tools must be developed to accurately access the radiation environment in both free space and on planetary surfaces. The primary tool NASA uses to quantify radiation exposure behind shielding materials is the space radiation transport code, HZETRN. In order to build confidence in HZETRN, code benchmarking against Monte Carlo radiation transport codes is often used. This work compares the dose calculations at Mars by HZETRN and the Geant4 application Planetocosmics. The dose at ground and the energy deposited in the atmosphere by galactic cosmic ray protons and alpha particles has been calculated for the Curiosity landing conditions. In addition, this work has considered Solar Energetic Particle events, allowing for the comparison of varying input radiation environments. The results for protons and alpha particles show very good agreement between HZETRN and Planetocosmics.

  19. Development of thin foil Faraday collector as a lost alpha particle diagnostic for high yield D-T tokamak fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Van Belle, P.; Jarvis, O.N.; Sadler, G.J. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Cecil, F.E. [Colorado School of Mines, Golden, CO (United States)

    1994-07-01

    Alpha particle confinement is necessary for ignition of a D-T tokamak fusion plasma and for first wall protection. Due to high radiation backgrounds and temperatures, scintillators and semiconductor detectors may not be used to study alpha particles which are lost to the first wall during the D-T programs on JET and ITER. An alternative method of charged particle spectrometry capable of operation in these harsh environments, is proposed: it consists of thin foils of electrically isolated conductors with the flux of alpha particles determined by the positive current flowing from the foils. 2 refs., 3 figs.

  20. Bernal liquid drop - alpha particle models of some heavy magic number nuclides

    International Nuclear Information System (INIS)

    Full text: Models of the bond structures of nickel 56, strontium 88, tin 120, cerium 140, lead 208 and uranium 240 nuclides based on Bernal's models of dense liquid drops, show good agreement between the binding energy data and shell structures when alpha particles are considered to be the densely packed hard spheres, of Bernal's models. These models, of the time-averaged structures of several closed shell nuclides have been developed as pedagogical aids for conceptualising some of the major aspects of nuclear matter and energy. These concepts include nuclear shape, size, charge density, quadrupole moment, viscosity, binding energy, coulomb repulsion, energy levels, magic numbers, shells and subshells; nucleon separation, bonding, pairing and clustering; nucleosynthesis, radioactivity and fission. The models discussed are based on those proposed by Bernal to account for the properties of normal liquids. Bernal's models have also been extended by others to explain the nature of metallic glasses considered as super cooled liquids. In Bernal's tetrahedral model of a normal liquid drop, a hard sphere representing an atom, ion, or molecule is added at whatever available position is closed to the centre of the existing cluster of spheres so that the densest possible configuration is created. Accordingly, two spheres form a dumbbell, three spheres form a triangle and four spheres form a tetrahedron and so on

  1. 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.

  2. The blistering of 316L stainless steel irradiated with energetic alpha particles at 500 degrees C

    International Nuclear Information System (INIS)

    The physical process of blistering is investigated in the 316L stainless steel in both the solid solution and 20% cold-worked states. The material was irradiated with 1.8 MeV alpha particles to various fluences at 500deg C. There is a threshold fluence for blistering in the range of (0.869-1.346)x 1018 α/cm2. The microstructure, determined by TEM observation in the cross-section of irradiated samples, shows that the bubbles are accumulated at the surface layer. There is a bubble size and density distribution along the direction of depth. The bubble size and swelling increase progressively from the edge of the specimen to the damage peak region (DPR), then decrease. After 3 μm there are no bubbles. Due to bubble formation the thermal conductivity of the surface layer becomes lower and the temperature increases due to the irradiation energy deposited. Beyond the threshold fluence, the temperature of the surface layer is high, bubble coalescence at DPR becomes more serious and the bubble pressure becomes high enough that blistering occurs. (orig.)

  3. Metallothionein bioconjugates as delivery vehicles for bismuth-212 alpha particle therapy

    International Nuclear Information System (INIS)

    Metallothioneins (MTHs) are small cysteine-rich polypeptides that binds cationic metals at physiologic pH ranges through noncovalent -SH ligand interactions. Some leucine-rich renal MTHs have a particular avidity for bismuth. The authors have examined the ability of MTHs to selectively incorporate Bi-212, a short-lived high-energy alpha particle emitter currently under exploration as a potential therapeutic radiolabel for use in molecularly targeted cancer therapy. They find that under physiologic conditions, MTH will selectively incorporate Bi-212 after incubation with an equilibrium mixture of its upstream and downstream parents. The MTH moieties may be linked to tumor-binding macromolecules such as antibodies via thiolation reactions using SPDP, and the resultant Bismuth-avid molecules may be used either as primary delivery vehicles for the Bi-212 or as part of a 2-step release-and-catch isotope localization system in which the MTH-antibody conjugate is pre-localized at the tumor site and the radiometal is then administered and chelated in situ. They present the chemistry, dosimetry and potential clinical applications of this system

  4. Spatiotemporal kinetics of γ-H2AX protein on charged particles induced DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Niu, H., E-mail: hniu@mx.nthu.edu.tw [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan (China); Chang, H.C. [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan (China); Cho, I.C. [Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Taoyuan, Taiwan (China); Chen, C.H. [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan (China); Liu, C.S. [Cancer Center of Taipei Veterans General Hospital, Taipei, Taiwan (China); Chou, W.T. [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan (China)

    2014-08-15

    Highlights: • Charged particles can induce more complex DNA damages, and these complex damages have higher ability to cause the cell death or cell carcinogenesis. • In this study, we used γ-H2AX protein to investigate the spatiotemporal kinetics of DNA double strand breaks in particle irradiated HeLa cells. • The HeLa cells were irradiated by 400 keV alpha-particles in four different dosages. • The result shows that a good linear relationship can be observed between foci number and radiation dose. • The data shows that the dissolution rate of γ-H2AX foci agree with the two components DNA repairing model, and it was decreasing as the radiation dose increased. • These results suggest that charged particles can induce more complex DNA damages and causing the retardation of DNA repair. - Abstract: In several researches, it has been demonstrated that charged particles can induce more complex DNA damages. These complex damages have higher ability to cause the cell death or cell carcinogenesis. For this reason, clarifying the DNA repair mechanism after charged particle irradiation plays an important role in the development of charged particle therapy and space exploration. Unfortunately, the detail spatiotemporal kinetic of DNA damage repair is still unclear. In this study, we used γ-H2AX protein to investigate the spatiotemporal kinetics of DNA double strand breaks in alpha-particle irradiated HeLa cells. The result shows that the intensity of γ-H2AX foci increased gradually, and reached to its maximum at 30 min after irradiation. A good linear relationship can be observed between foci intensity and radiation dose. After 30 min, the γ-H2AX foci intensity was decreased with time passed, but remained a large portion (∼50%) at 48 h passed. The data show that the dissolution rate of γ-H2AX foci agreed with two components DNA repairing model. These results suggest that charged particles can induce more complex DNA damages and causing the retardation of DNA

  5. 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.

  6. Calcitonin substitution in calcitonin deficiency reduces particle-induced osteolysis

    Directory of Open Access Journals (Sweden)

    Grabellus Florian

    2011-08-01

    Full Text Available Abstract Background Periprosthetic osteolysis is a major cause of aseptic loosening in joint arthroplasty. This study investigates the impact of CT (calcitonin deficiency and CT substitution under in-vivo circumstances on particle-induced osteolysis in Calca -/- mice. Methods We used the murine calvarial osteolysis model based on ultra-high molecular weight polyethylene (UHMWPE particles in 10 C57BL/6J wild-type (WT mice and twenty Calca -/- mice. The mice were divided into six groups: WT without UHMWPE particles (Group 1, WT with UHMWPE particles (Group 2, Calca -/- mice without UHMWPE particles (Group 3, Calca -/- mice with UHMWPE particles (Group 4, Calca -/- mice without UHMWPE particles and calcitonin substitution (Group 5, and Calca -/- mice with UHMWPE particle implantation and calcitonin substitution (Group 6. Analytes were extracted from serum and urine. Bone resorption was measured by bone histomorphometry. The number of osteoclasts was determined by counting the tartrate-resistant acid phosphatase (TRACP + cells. Results Bone resorption was significantly increased in Calca -/- mice compared with their corresponding WT. The eroded surface in Calca -/- mice with particle implantation was reduced by 20.6% after CT substitution. Osteoclast numbers were significantly increased in Calca -/- mice after particle implantation. Serum OPG (osteoprotegerin increased significantly after CT substitution. Conclusions As anticipated, Calca -/- mice show extensive osteolysis compared with wild-type mice, and CT substitution reduces particle-induced osteolysis.

  7. Development of lymphoproliferative diseases by hypoxia inducible factor-1alpha is associated with prolonged lymphocyte survival.

    Directory of Open Access Journals (Sweden)

    Eisaburo Sueoka

    Full Text Available Hypoxia-inducible factor-1alpha (HIF-1 alpha plays an essential role in the regulation of various genes associated with low oxygen consumption. Elevated expression of HIF-1alpha has been reported to be associated with tumor progression, invasion and metastasis in many cancers. To investigate the role of HIF-1alpha in tumor development and metastasis, we established transgenic mice constitutively expressing HIF1A gene under regulation of the cytomegalovirus gene promoter. Although HIF-1alpha protein levels varied among organs, expression of HIF1A mRNA in most organs gradually increased in an age-dependent manner. The transgenic mice showed no gross morphological abnormality up to 8 weeks after birth, although they subsequently developed tumors in the lymphoid, lung, and breast; the most prominent tumor was lymphoma appearing in the intestinal mucosa and intra-mesenchymal tissues. The prevalence of tumors reached 80% in 13 months after birth. The constitution of lymphocyte populations in the transgenic mice did not differ from that in wild-type mice. However, lymphocytes of the transgenic mice revealed prolonged survival under long-term culture conditions and revealed increased resistance to cytotoxic etoposide. These results suggest that HIF-1alpha itself is not oncogenic but it may play an important role in lymphomagenesis mediated through the prolonged survival of lymphocytes in this transgenic mouse model.

  8. AlphaS1-casein deficiency recorded for defective genotypes induces a chronic ER stress and deep changes in milk composition, signing a singular secretion process in goats

    OpenAIRE

    Martin, Patrice; B. Badaoui; Barile, Daniela; Lahouassa, Hichem; Beauvallet, Christian; Cebo, Christelle; Leroux, Christine; Chanat, Eric

    2013-01-01

    The extensive polymorphism recorded at the CSN1S1 locus has been shown to influence goat milk composition and its technological properties. A deficit in alphaS1-casein is responsible for the accumulation of immature caseins in distended rough endoplasmic reticulum (ER) cisternae of mammary epithelial cells (MEC). This triggers a chronic ER stress which induces, in turn, an adaptive unfolded protein response (UPR). Our data strongly suggest: i) the existence of a membraneassociated form of alp...

  9. Shock-induced deformation in wetted particle beds

    International Nuclear Information System (INIS)

    The high-strain-rate response of granular media has received considerable attention due to increasing interest in granular penetration. In the present study, we investigate the response of wetted packed particle beds under varying flyer plate-induced shock loadings. We investigate the critical conditions for the onset of particle deformation in systems of spherical macroscopic glass beads. Resulting particle deformations from the shock compression are characterized using microscopy as well as particle size analysis, and the effects of shock strength are compared. A fracturing response with a bimodal particle distribution is observed, with an increasing shift to the lower particle size range as shock loading is initially increased. As the transmitted shock pressure exceeds 1 GPa, a significant decrease in the mean particle size is observed.

  10. Inhibition of HIF-1{alpha} activity by BP-1 ameliorates adjuvant induced arthritis in rats

    Energy Technology Data Exchange (ETDEWEB)

    Shankar, J. [Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago (United States); Thippegowda, P.B., E-mail: btprabha@uic.edu [Department of Pharmacology, (M/C 868), College of Medicine, University of Illinois at Chicago, 835 S. Wolcott Ave., Chicago, IL 60612 (United States); Kanum, S.A. [Department of Chemistry, Yuvaraj' s College, University of Mysore, Mysore (India)

    2009-09-18

    Rheumatoid arthritis (RA) is a chronic inflammatory, angiogenic disease. Inflamed synovitis is a hallmark of RA which is hypoxic in nature. Vascular endothelial growth factor (VEGF), one of the key regulators of angiogenesis, is overexpressed in the pathogenesis of RA. VEGF expression is regulated by hypoxia-inducible factor-1{alpha} (HIF-1{alpha}), a master regulator of homeostasis which plays a pivotal role in hypoxia-induced angiogenesis. In this study we show that synthetic benzophenone analogue, 2-benzoyl-phenoxy acetamide (BP-1) can act as a novel anti-arthritic agent in an experimental adjuvant induced arthritis (AIA) rat model by targeting VEGF and HIF-1{alpha}. BP-1 administered hypoxic endothelial cells and arthritic animals clearly showed down regulation of VEGF expression. Further, BP-1 inhibits nuclear translocation of HIF-1{alpha}, which in turn suppresses transcription of the VEGF gene. These results suggest a further possible clinical application of the BP-1 derivative as an anti-arthritic agent in association with conventional chemotherapeutic agents.

  11. Ion-induced nucleation of pure biogenic particles

    CERN Document Server

    Kirkby, Jasper; Sengupta, Kamalika; Frege, Carla; Gordon, Hamish; Williamson, Christina; Heinritzi, Martin; Simon, Mario; Yan, Chao; Almeida, João; Tröstl, Jasmin; Nieminen, Tuomo; Ortega, Ismael K; Wagner, Robert; Adamov, Alexey; Amorim, Antonio; Bernhammer, Anne-Kathrin; Bianchi, Federico; Breitenlechner, Martin; Brilke, Sophia; Chen, Xuemeng; Craven, Jill; Dias, antonio; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Fuchs, Claudia; Guida, Roberto; Hakala, Jani; Hoyle, Christopher R; Jokinen, Tuija; Junninen, Heikki; Kangasluoma, Juha; Kim, Jaeseok; Krapf, Manuel; Kürten, andreas; Laaksonen, Ari; Lehtipalo, Katrianne; Makhmutov, Vladimir; Mathot, Serge; Molteni, Ugo; Onnela, antti; Peräkylä, Otso; Piel, Felix; Petäjä, Tuukka; Praplan, Arnaud P; Pringle, Kirsty; Rap, Alexandru; Richards, Nigel A D; Riipinen, Ilona; Rissanen, Matti P; Rondo, Linda; Sarnela, Nina; Schobesberger, Siegfried; Scott, Catherine E; Seinfeld, John H; Sipilä, Mikko; Steiner, Gerhard; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Virtanen, Annele; Vogel, Alexander L; Wagner, Andrea C; Wagner, Paul E; Weingartner, Ernest; Wimmer, Daniela; Winkler, Paul M; Ye, Penglin; Zhang, Xuan; Hansel, Armin; Dommen, Josef; Donahue, Neil M; Worsnop, Douglas R; Baltensperger, Urs; Kulmala, Markku; Carslaw, Kenneth S; Curtius, Joachim

    2016-01-01

    Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of $\\alpha$-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported...

  12. 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)

  13. 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...

  14. Energetic resolution study on pure and CsBr doped CsI under gamma excitations and alpha particles

    International Nuclear Information System (INIS)

    Pure and doped CsI crystals were grown using the Bridgman technique. Bromine was the doping element which was studied in the range of 1.5x10-1 M to 10-2 M. The distribution of the doping element at crystalline volume was determined by neutron activation. Concerning gamma radiation response it was carried out measurements to evaluate the developed scintillators in the energy range of 350 keV to 1330 keV. For alpha particles measurements an 241Am source was used with 5.54 MeV energy. The resolution of 3.7% was obtained for the CsI:Br 10-2 M crystal, when excited with alpha particles from an 241Am source. For CsI:Br 10-1 M crystal 9.1% resolution was obtained when excited with gamma radiation from 22Na source, with 1275 keV energy. (author)

  15. Spatiotemporal kinetics of γ-H2AX protein on charged particles induced DNA damage

    Science.gov (United States)

    Niu, H.; Chang, H. C.; Cho, I. C.; Chen, C. H.; Liu, C. S.; Chou, W. T.

    2014-08-01

    In several researches, it has been demonstrated that charged particles can induce more complex DNA damages. These complex damages have higher ability to cause the cell death or cell carcinogenesis. For this reason, clarifying the DNA repair mechanism after charged particle irradiation plays an important role in the development of charged particle therapy and space exploration. Unfortunately, the detail spatiotemporal kinetic of DNA damage repair is still unclear. In this study, we used γ-H2AX protein to investigate the spatiotemporal kinetics of DNA double strand breaks in alpha-particle irradiated HeLa cells. The result shows that the intensity of γ-H2AX foci increased gradually, and reached to its maximum at 30 min after irradiation. A good linear relationship can be observed between foci intensity and radiation dose. After 30 min, the γ-H2AX foci intensity was decreased with time passed, but remained a large portion (∼50%) at 48 h passed. The data show that the dissolution rate of γ-H2AX foci agreed with two components DNA repairing model. These results suggest that charged particles can induce more complex DNA damages and causing the retardation of DNA repair.

  16. Aeolian Induced Erosion and Particle Entrainment

    Science.gov (United States)

    Saint, Brandon

    2007-01-01

    The Granular Physics Department at The Kennedy Space Center is addressing the problem of erosion on the lunar surface. The early stages of research required an instrument that would produce erosion at a specific rate with a specific sample variation. This paper focuses on the development and experimental procedures to measure and record erosion rates. This was done with the construction of an open air wind tunnel, and examining the relationship between airflow and particle motion.

  17. 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.

  18. Increase in the area of etched alpha-particle tracks in CR-39 plastic with increasing storage time under nitrogen

    CERN Document Server

    Bhakta, J R; Miles, J C H

    1999-01-01

    The area of etched tracks in CR-39 (polyallyl diglycol carbonate, PADC) exposed to alpha-particles from an americium-241 source has been investigated as a function of post-exposure storage time in a dry nitrogen atmosphere. Data were collected over 2.5 years and the results show that the nominal maximum area of the track area distribution increases with increasing storage time.

  19. Role and mechanism of uncoupling protein 2 on the fatty acid-induced dysfunction of pancreatic alpha cells in vitro

    Institute of Scientific and Technical Information of China (English)

    SU Jie-ying; LI Hong-liang; YANG Wen-ying; XIAO Jian-zhong; DU Rui-qin; SHEN Xiao-xia; CAI Zhe; ZHANG Lan; SHU Jun

    2010-01-01

    Background Uncoupling protein (UCP) 2 is related to the dysfunction of beta cells induced by fatty acids. However,whether UCP2 has similar effects on alpha cell is still not clear. This study aimed to investigate the effects of UCP2 and its possible mechanisms in lipotoxicity-induced dysfunction of pancreatic alpha cells.Methods The alpha TC1-6 cells were used in this study to evaluate the effects of palmitate and/or UCP2 inhibit factors on the glucagon secretory function, glucagon content, the glucagon mRNA level and the nitrotyrosine level in the supernatant. Meantime, the expression levels of UCP2 and peroxisome proliferator-activated receptor-γ coactivator-1 alpha (PGC-1 alpha) were measured by real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. Furthermore, the possible relationship between UCP2 and insulin signal transduction pathway was analyzed.Results Palmitate stimulated alpha cell glucagon secretion and the expression of UCP2 and PGC-1 alpha, which could be partially decreased by the inhibition of UCP2. Palmitate increased nitrotyrosine level and suppressed insulin signal transduction pathway in alpha cells. Inhibition of UCP2 influenced the effects of free fatty acid on alpha cells and may relate to glucagon secretion.Conclusion UCP2 played an important role on alpha cell dysfunction induced by free fatty acid in vitro, which may be related to its effects on oxidative stress and insulin signal transduction pathway.

  20. Scintillation response of CsI: Tl crystal under neutron, gamma, alpha particles and beta excitations

    International Nuclear Information System (INIS)

    Among the converters of X and gamma radiation in light photons, known as scintillators, the one which is the most efficient emits photons with a wavelength near 400 nm. Particularly, among them, the cesium iodine doped with thallium (CsI:Tl) crystal is that which matches better between the light emission spectrum (peak at 540 nm) and the quantum sensitivity curve of the photodiodes and CCD (Charge Coupled Device). This explains the renewed interest in using this crystal as scintillator. Although the CsI:Tl crystal is commercially available, its local development would give the possibility to obtain it in different geometric configurations and coupling. Moreover, there is a special interest in studying new conditions that will alter the properties of this crystal in order to achieve a optimal level of its functional characteristics. Having an efficient national scintillator with low cost is a strategic opportunity to study the response of a detector applied to different types of radiation. The crystal of cesium iodide activated with thallium (CsI:Tl) has a high gamma detection efficiency per unit volume. In this paper, the CsI:Tl crystal, grown by the vertical Bridgman technique in evacuated silica ampoules and with the purpose of use as radiation detectors, is described. To evaluate the scintillator, measures of the thallium distribution in the crystal volume were taken, with overall efficiency score. The scintillator response was studied through gamma radiation from sources of 137Cs, 60Co, 22Na, 54Mn, 131I and 99mTc; the beta radiation from source of 90Sr/90Y, alpha particles from 241Am source and the scintillator response to neutrons from Am/Be source. The energetic resolution for 137Cs gamma rays (662 keV) was 10%. The results showed the validity of using the CsI:Tl crystal developed in our laboratory, in many applications in the area of radiation detectors. (author)

  1. Production of helium and helium-hydrogen positive ion beams for the alpha particle measurement

    International Nuclear Information System (INIS)

    In order to produce diagnostic helium neutral beam for alpha particle measurement in nuclear fusion plant of deuterium-tritium reation, helium ion (He+) or helium-hydrogen ion (HeH+) beams of ∼20 keV have been considered as a primary beam. For He+ beam, it is important to produce focused high-current-density ion beam in order to pass through small apertures of alkali gas cell with an enough signal level. For HeH+ beam, conditions producing HeH+ has not been investigated in detail as yet. In order to extract these beams, focused high-current-density neutral beam system is applied. For He+ beam extraction of ∼22 kV, it is confirmed that current density of ∼86 mA/cm2 is achieved, whose value is close to necessary value in ITER. For HeH+ beam extraction in the case of ∼300 V acceleration, the production rate of HeH+ component increases with the increase of helium gas pressure ratio to hydrogen gas pressure when its value is > ∼75%. In the case of 25 kV acceleration, if 15% of total current (which includes H+, H2+, H3+, He+ and HeH+ components) is HeH+ component, current density of HeH+ is estimated as ∼13 mA/cm2, whose value is larger than necessary value in ITER. From melted traces of the target plate, it is estimated that the divergence angle is about ±0.8deg. (author)

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Alpha band cortico-muscular coherence occurs in healthy individuals during mechanically-induced tremor.

    Directory of Open Access Journals (Sweden)

    Francesco Budini

    Full Text Available The present work aimed at investigating the effects of mechanically amplified tremor on cortico-muscular coherence (CMC in the alpha band. The study of CMC in this specific band is of particular interest because this coherence is usually absent in healthy individuals and it is an aberrant feature in patients affected by pathological tremors; understanding its mechanisms is therefore important. Thirteen healthy volunteers (23±4 years performed elbow flexor sustained contractions both against a spring load and in isometric conditions at 20% of maximal voluntary isometric contraction (MVC. Spring stiffness was selected to induce instability in the stretch reflex servo loop. 64 EEG channels, surface EMG from the biceps brachii muscle and force were simultaneously recorded. Contractions against the spring resulted in greater fluctuations of the force signal and EMG amplitude compared to isometric conditions (p<.05. During isometric contractions CMC was systematically found in the beta band and sporadically observed in the alpha band. However, during the contractions against the spring load, CMC in the alpha band was observed in 12 out of 13 volunteers. Partial directed coherence (PDC revealed an increased information flow in the EMG to EEG direction in the alpha band (p<.05. Therefore, coherence in the alpha band between the sensory-motor cortex and the biceps brachii muscle can be systematically induced in healthy individuals by mechanically amplifying tremor. The increased information flow in the EMG to EEG direction may reflect enhanced afferent activity from the muscle spindles. These results may contribute to the understanding of the presence of alpha band CMC in tremor related pathologies by suggesting that the origin of this phenomenon may not only be at cortical level but may also be affected by spinal circuit loops.

  7. Intestinal ischemia/reperfusion induces bronchial hyperreactivity and increases serum TNF-alpha in rats

    Directory of Open Access Journals (Sweden)

    Arruda Marcio Jose Cristiano de

    2006-01-01

    Full Text Available INTRODUCTION: Intestinal or hepatic ischemia/reperfusion induces acute lung injury in animal models of multiple organ failure. Tumor necrosis factor (TNF- alpha is involved in the underlying inflammatory mechanism of acute respiratory distress syndrome. Although the inflammatory cascade leading to acute respiratory distress syndrome has been extensively investigated, the mechanical components of acute respiratory distress syndrome are not fully understood. Our hypothesis is that splanchnic ischemia/reperfusion increases airway reactivity and serum TNF-alpha levels. OBJECTIVE: To assess bronchial smooth muscle reactivity under methacholine stimulation, and to measure serum TNF-alpha levels following intestinal and/or hepatic ischemia/reperfusion in rats. METHOD: Rats were subjected to 45 minutes of intestinal ischemia, or 20 minutes of hepatic ischemia, or to both (double ischemia, or sham procedures (control, followed by 120 minutes of reperfusion. The animals were then sacrificed, and the bronchial response to increasing methacholine molar concentrations (10-7 to 3 x 10-4 was evaluated in an ex-vivo bronchial muscle preparation. Serum TNF-alpha was determined by the L929-cell bioassay. RESULTS: Bronchial response (g/100 mg tissue showed increased reactivity to increasing methacholine concentrations in the intestinal ischemia and double ischemia groups, but not in the hepatic ischemia group. Similarly, serum TNF-alpha (pg/mL concentration was increased in the intestinal ischemia and double ischemia groups, but not in the hepatic ischemia group. CONCLUSION: Intestinal ischemia, either isolated or associated with hepatic ischemia, increased bronchial smooth muscle reactivity, suggesting a possible role for bronchial constriction in respiratory dysfunction following splanchnic ischemia/reperfusion. This increase occurred in concomitance with serum TNF-alpha increase, but whether the increase in TNF-alpha caused this bronchial contractility remains

  8. 5-Azacytidine treatment of HA-A melanoma cells induces Sp1 activity and concomitant transforming growth factor alpha expression.

    Science.gov (United States)

    Shin, T H; Paterson, A J; Grant, J H; Meluch, A A; Kudlow, J E

    1992-01-01

    Evidence indicates DNA methylation as a part of the regulatory machinery controlling mammalian gene expression. The human melanoma cell line HA-A expresses low levels of transforming growth factor alpha (TGF-alpha). TGF-alpha mRNA accumulated, however, in response to DNA demethylation induced by a nucleoside analog, 5-azacytidine (5-azaC). The importance of DNA methylation in the TGF-alpha promoter region was examined by a transient transfection assay with luciferase reporter plasmids containing a portion of the TGF-alpha promoter. 5-azaC treatment of HA-A cells before the transfection caused a significant increase in the luciferase activity. Since input plasmids were confirmed to remain unmethylated, DNA demethylation of the TGF-alpha promoter itself does not account for the observed increase in TGF-alpha mRNA. Using an electrophoretic mobility shift assay, enhanced formation of protein-TGF-alpha promoter complex was detected in response to 5-azaC treatment. This 5-azaC-induced complex was shown to contain the transcription factor Sp1 by the following criteria: the protein-DNA complex formed on the TGF-alpha promoter contained immunoreactive Sp1; the mobility of the complex in an electrophoretic mobility shift assay was similar to that formed by recombinant Sp1; and DNase I footprinting analysis demonstrated that the 5-azaC-induced complex produced a footprint on the TGF-alpha promoter identical to that of authentic Sp1. These observations suggest that 5-azaC induces TGF-alpha expression by augmenting the Sp1 activity. However, neither the Sp1 mRNA nor its protein was induced by 5-azaC. These results suggest that in HA-A cells, TGF-alpha expression is down-modulated by DNA methylation. In addition, this process may involve the specific regulation of Sp1 activity without altering the amount of the transcription factor. Images PMID:1380648

  9. Calibration of a Thomson parabola ion spectrometer and Fujifilm imaging plate detectors for protons, deuterons, and alpha particles

    International Nuclear Information System (INIS)

    A Thomson parabola ion spectrometer has been designed for use at the Multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE) at University of Rochester. This device uses parallel electric and magnetic fields to deflect particles of a given mass-to-charge ratio onto parabolic curves on the detector plane. Once calibrated, the position of the ions on the detector plane can be used to determine the particle energy. The position dispersion of both the electric and magnetic fields of the Thomson parabola was measured using monoenergetic proton and alpha particle beams from the SUNY Geneseo 1.7 MV tandem Pelletron accelerator. The sensitivity of Fujifilm BAS-TR imaging plates, used as a detector in the Thomson parabola, was also measured as a function of the incident particle energy over the range from 0.6 MeV to 3.4 MeV for protons and deuterons and from 0.9 MeV to 5.4 MeV for alpha particles. The device was used to measure the energy spectrum of laser-produced protons at MTW.

  10. Calibration of a Thomson parabola ion spectrometer and Fujifilm imaging plate detectors for protons, deuterons, and alpha particles

    Science.gov (United States)

    Freeman, C. G.; Fiksel, G.; Stoeckl, C.; Sinenian, N.; Canfield, M. J.; Graeper, G. B.; Lombardo, A. T.; Stillman, C. R.; Padalino, S. J.; Mileham, C.; Sangster, T. C.; Frenje, J. A.

    2011-07-01

    A Thomson parabola ion spectrometer has been designed for use at the Multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE) at the University of Rochester. This device uses parallel electric and magnetic fields to deflect particles of a given mass-to-charge ratio onto parabolic curves on the detector plane. Once calibrated, the position of the ions on the detector plane can be used to determine the particle energy. The position dispersion of both the electric and magnetic fields of the Thomson parabola was measured using monoenergetic proton and alpha particle beams from the SUNY Geneseo 1.7 MV tandem Pelletron accelerator. The sensitivity of Fujifilm BAS-TR imaging plates, used as a detector in the Thomson parabola, was also measured as a function of the incident particle energy over the range from 0.6 MeV to 3.4 MeV for protons and deuterons and from 0.9 MeV to 5.4 MeV for alpha particles. The device was used to measure the energy spectrum of laser-produced protons at MTW.

  11. 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

  12. KNK437, abrogates hypoxia-induced radioresistance by dual targeting of the AKT and HIF-1{alpha} survival pathways

    Energy Technology Data Exchange (ETDEWEB)

    Oommen, Deepu, E-mail: oommen1978@gmail.com [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Prise, Kevin M. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom)

    2012-05-11

    Highlights: Black-Right-Pointing-Pointer KNK437, a benzylidene lactam compound, is a novel radiosensitizer. Black-Right-Pointing-Pointer KNK437 inhibits AKT signaling and abrogates the accumulation of HIF-1{alpha} under hypoxia. Black-Right-Pointing-Pointer KNK437 abrogates hypoxia induced resistance to radiation. -- Abstract: KNK437 is a benzylidene lactam compound known to inhibit stress-induced synthesis of heat shock proteins (HSPs). HSPs promote radioresistance and play a major role in stabilizing hypoxia inducible factor-1{alpha} (HIF-1{alpha}). HIF-1{alpha} is widely responsible for tumor resistance to radiation under hypoxic conditions. We hypothesized that KNK437 sensitizes cancer cells to radiation and overrides hypoxia-induced radioresistance via destabilizing HIF-1{alpha}. Treatment of human cancer cells MDA-MB-231 and T98G with KNK437 sensitized them to ionizing radiation (IR). Surprisingly, IR did not induce HSPs in these cell lines. As hypothesized, KNK437 abrogated the accumulation of HIF-1{alpha} in hypoxic cells. However, there was no induction of HSPs under hypoxic conditions. Moreover, the proteosome inhibitor MG132 did not restore HIF-1{alpha} levels in KNK437-treated cells. This suggested that the absence of HIF-1{alpha} in hypoxic cells was not due to the enhanced protein degradation. HIF-1{alpha} is mainly regulated at the level of post-transcription and AKT is known to modulate the translation of HIF-1{alpha} mRNA. Interestingly, pre-treatment of cells with KNK437 inhibited AKT signaling. Furthermore, down regulation of AKT by siRNA abrogated HIF-1{alpha} levels under hypoxia. Interestingly, KNK437 reduced cell survival in hypoxic conditions and inhibited hypoxia-induced resistance to radiation. Taken together, these data suggest that KNK437 is an effective radiosensitizer that targets multiple pro-survival stress response pathways.

  13. Track structure based modelling of chromosome aberrations after photon and alpha-particle irradiation.

    Science.gov (United States)

    Friedland, Werner; Kundrát, Pavel

    2013-08-30

    A computational model of radiation-induced chromosome aberrations in human cells within the PARTRAC Monte Carlo simulation framework is presented. The model starts from radiation-induced DNA damage assessed by overlapping radiation track structures with multi-scale DNA and chromatin models, ranging from DNA double-helix in atomic resolution to chromatin fibre loops, heterochromatic and euchromatic regions, and chromosome territories. The repair of DNA double-strand breaks via non-homologous end-joining is followed. Initial spatial distribution and complexity, diffusive motion, enzymatic processing, synapsis and ligation of individual DNA ends from the breaks are simulated. To enable scoring of different chromosome aberration types resulting from improper joining of DNA fragments, the repair module has been complemented by tracking the chromosome origin of the ligated fragments and the positions of centromeres. The modelled motion of DNA ends has sub-diffusive characteristics and corresponds to measured chromatin mobility within time-scales of a few hours. The calculated formation of dicentrics after photon and α-particle irradiation in human fibroblasts is compared to experimental data (Cornforth et al., 2002, Radiat Res 158, 43). The predicted yields of dicentrics overestimate the measurements by factors of five for γ-rays and two for α-particle irradiation. Nevertheless, the observed relative dependence on radiation dose is correctly reproduced. Calculated yields and size distributions of other aberration types are discussed. The present work represents a first mechanistic approach to chromosome aberrations and their kinetics, combining full track structure simulations with detailed models of chromatin and accounting for the kinetics of DNA repair. PMID:23811166

  14. Features of the gas discharge in the narrow gap micro-pattern gas detectors (MPGD) at a high level of alpha-particles background

    CERN Document Server

    Razin, V I

    2010-01-01

    In given article preliminary results of the research of the electron multiplication in MPGD are presented at a high level of alpha-particles background. This work has expanded borders of understanding of the streamer mode nature. It is seen as a complex from electrostatic and electromagnetic interactions which begin with appearance of the precursor in plasma state. In an inter-electrode gap the plasma oscillations occur, accompanied by longitudinal elastic waves of ionization, which can reach the cathode surface with induced negative charge. With the release of this charge due to previously established conducting channel there is a strong current pulse, accompanied by the emission due to recombination of positive and negative ions and a thin cord or streamer derive. In the aim of the MPGD protection from the spark breakdown at a high level of the alpha-particle background the next gas composition from a buffer, cooling and electronegative components are offered: 70% He +28% CF4 +2% SF6.

  15. Plasmin-induced migration requires signaling through protease-activated receptor 1 and integrin alpha(9)beta(1).

    Science.gov (United States)

    Majumdar, Mousumi; Tarui, Takehiko; Shi, Biao; Akakura, Nobuaki; Ruf, Wolfram; Takada, Yoshikazu

    2004-09-01

    Plasmin is a major extracellular protease that elicits intracellular signals to mediate platelet aggregation, chemotaxis of peripheral blood monocytes, and release of arachidonate and leukotriene from several cell types in a G protein-dependent manner. Angiostatin, a fragment of plasmin(ogen), is a ligand and an antagonist for integrin alpha(9)beta(1). Here we report that plasmin specifically interacts with alpha(9)beta(1) and that plasmin induces of cells expressing migration recombinant alpha(9)beta(1) (alpha(9)-Chinese hamster ovary (CHO) cells). Migration was dependent on an interaction of the kringle domains of plasmin with alpha(9)beta(1) as well as the catalytic activity of plasmin. Angiostatin, representing the kringle domains of plasmin, alone did not induce the migration of alpha(9)-CHO cells, but simultaneous activation of the G protein-coupled protease-activated receptor (PAR)-1 with an agonist peptide induced the migration on angiostatin, whereas PAR-2 or PAR-4 agonist peptides were without effect. Furthermore, a small chemical inhibitor of PAR-1 (RWJ 58259) and a palmitoylated PAR-1-blocking peptide inhibited plasmin-induced migration of alpha(9)-CHO cells. These results suggest that plasmin induces migration by kringle-mediated binding to alpha(9)beta(1) and simultaneous proteolytic activation of PAR-1. PMID:15247268

  16. Geodesic Acoustic Modes Induced by Energetic Particles

    Science.gov (United States)

    Zhou, Tianchun; Berk, Herbert

    2009-11-01

    A global geodesic acoustic mode driven by energetic particles (EGAM) has been observed in JET[1, 2] and DIII D[3, 4]. The mode is to be treated fully kinetically. The descriptions of the background electrons and ions are based on standard high and low bounce frequency expansion respectively with respect to the mode frequency. However, the energetic ions must be treated without any expansion of ratio between their bounce frequency and the mode frequency since they are comparable. Under electrostatic perturbation, we construct a quadratic form for the wave amplitude, from which an integro-differential equation is derived. In the limit where the drift orbit width is small comparison with the mode width, a differential equation for perturbed electrostatic field is obtained. Solution is obtained both analytically and numerically. We find that beam counterinjection enhances the instability of the mode. Landau damping due to thermal species is investigated.

  17. alpha-Galactosylceramide can act as a nasal vaccine adjuvant inducing protective immune responses against viral infection and tumor.

    Science.gov (United States)

    Ko, Sung-Youl; Ko, Hyun-Jeong; Chang, Woo-Sung; Park, Se-Ho; Kweon, Mi-Na; Kang, Chang-Yuil

    2005-09-01

    alpha-Galactosylceramide (alpha-GalCer) is a ligand of invariant Valpha14+ NKT cells and is presented by CD1d molecule on APC. NKT cells produce a large amount of Th1 and Th2 cytokines in response to alpha-GalCer-presented APC. In this study, we assessed whether alpha-GalCer could act as an effective nasal vaccine adjuvant for mucosal vaccine that would be capable of inducing systemic as well as mucosal immune responses. When alpha-GalCer was administered with OVA via the intranasal route to C57BL/6 and BALB/c mice, significant OVA-specific mucosal secretory IgA, systemic IgG, and CTL responses were induced with mixed Th1 and Th2 cytokine profiles seen in both strains of mice. Interestingly, as BALB/c mice were intranasally immunized with PR8 hemagglutinin Ag isolated from influenza virus A/PR/8/34 together with alpha-GalCer, significant protection was afforded against influenza viral infection. When alpha-GalCer was coimmunized with a replication-deficient live adenovirus to BALB/c mice, it significantly induced both humoral and cellular immune responses. In addition, intranasal administration of OVA with alpha-GalCer showed complete protection against EG7 tumor challenge in C57BL/6. The adjuvant effects induced by intranasal coadministration with alpha-GalCer were blocked in CD1d-/- mice, indicating that the immune responses were exclusively mediated by CD1d molecule on APC. Most interestingly, intranasally coadministered alpha-GalCer activated naive T cells and triggered them to differentiate into functional effector T cells when CFSE-labeled OT-1 cells were adoptively transferred into syngeneic mice. Overall, our results are the first to show that alpha-GalCer can act as a nasal vaccine adjuvant inducing protective immune responses against viral infections and tumors. PMID:16116223

  18. Partial deficiency of HIF-1 alpha stimulates pathological cardiac changes in streptozotocin-induced diabetic mice

    Czech Academy of Sciences Publication Activity Database

    Bohuslavová, Romana; Kolář, František; Sedmera, David; Škvorová, Lada; Papoušek, František; Neckář, Jan; Pavlínková, Gabriela

    2014-01-01

    Roč. 14, Feb 6 (2014). ISSN 1472-6823 R&D Projects: GA ČR GA301/09/0117; GA MŠk(CZ) ED1.1.00/02.0109 Institutional research plan: CEZ:AV0Z50520701 Institutional support: RVO:68378271 Keywords : Echocardiographic parameters * Hypoxia inducible factor 1 alpha * Diabetic cardiomyopathy Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 1.710, year: 2014

  19. Social disruption stress exacerbates alpha-galactosylceramide-induced hepatitis in mice

    OpenAIRE

    Sonoda, J.; Chida, Y; Sudo, N.; Kubo, C

    2005-01-01

    Objective: Psychosocial stress has been suggested as a possible aggravating factor in liver diseases, however, the underlying mechanism has yet to be clarified. Recently, our research revealed that electric foot-shock stress aggravated NK1.1 Ag+ T cell-dependent a-galactosylceramide (alpha-GalCer)-induced hepatitis in mice via a mechanism mediated by endogenous glucocorticoids. In this study, we examined whether or not such aggravation could be applied to a psychosocially stressful situation,...

  20. Studies of SSNTDs made from LR-115 in view of their applicability in radiobiological experiments with alpha particles

    Energy Technology Data Exchange (ETDEWEB)

    Doerschel, B. E-mail: doerschel@physik.tu-dresden.de; Hermsdorf, D.; Pieck, S.; Starke, S.; Thiele, H.; Weickert, F

    2003-06-01

    Radiobiological studies on cell monolayers irradiated by charged particles need to determine the number and position of particle traversals. Solid state nuclear track detectors used as basic substrate for the cell layers are in principle suitable for this purpose. The detector foils must be as thin as possible but still guaranteeing mechanical stability. Two types of LR-115, red coloured and colourless, were tested in the present work. The studies aimed at optimisation of the etching conditions and determination of the registration efficiency for alpha particles in a wide range of energies and angles of incidence. Specific requirements have to be fulfilled for application of the detector foils under the environmental conditions of radiobiological experiments. Most important are biocompatibility between detector and cells and registration properties insensible against special treatments, as UV sterilisation and cell plating prior to irradiation as well as cell incubation after the irradiation. The experimental studies performed with alpha particles showed that environmental conditions of radiobiological experiments do not change the registration properties of LR-115 detectors significantly.

  1. Calcitonin substitution in calcitonin deficiency reduces particle-induced osteolysis

    OpenAIRE

    Grabellus Florian; Hilken Gero; Broecker-Preuss Martina; Neuerburg Laura; Bachmann Hagen S; Kauther Max D; Koehler Gabriele; von Knoch Marius; Wedemeyer Christian

    2011-01-01

    Abstract Background Periprosthetic osteolysis is a major cause of aseptic loosening in joint arthroplasty. This study investigates the impact of CT (calcitonin) deficiency and CT substitution under in-vivo circumstances on particle-induced osteolysis in Calca -/- mice. Methods We used the murine calvarial osteolysis model based on ultra-high molecular weight polyethylene (UHMWPE) particles in 10 C57BL/6J wild-type (WT) mice and twenty Calca -/- mice. The mice were divided into six groups: WT ...

  2. Gravitationally induced particle production and its impact on structure formation

    CERN Document Server

    Nunes, Rafael C

    2016-01-01

    In this paper we investigate the influence of a continuous particles creation processes on the linear and nonlinear matter clustering, and its consequences on the weak lensing effect induced by structure formation. We study the line of sight behavior of the contribution to the bispectrum signal at a given angular multipole $l$, showing that the scale where the nonlinear growth overcomes the linear effect depends strongly of particles creation rate.

  3. Synthetic. cap alpha. subunit peptide 125-147 of human nicotinic acetylcholine receptor induces antibodies to native receptor

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, D.J.; Griesmann, G.E.; Huang, Z.; Lennon, V.A.

    1986-03-05

    A synthetic peptide corresponding to residues 125-147 of the Torpedo acetylcholine receptor (AChR) ..cap alpha.. subunit proved to be a major antigenic region of the AChR. Rats inoculated with 50 ..mu..g of peptide (T ..cap alpha.. 125-147) developed T cell immunity and antibodies to native AChR and signs of experimental autoimmune myasthenia gravis. They report the synthesis and preliminary testing of a disulfide-looped peptide comprising residues 125-147 of the human AChR ..cap alpha.. subunit. Peptide H ..cap alpha.. 125-147 differs from T ..cap alpha.. 125-147 at residues 139 (Glu for Gln) and 143 (Ser for Thr). In immunoprecipitation assays, antibodies to Torpedo AChR bound /sup 125/I-labelled H..cap alpha.. 125-147 antibody bound H..cap alpha.. 125-147, but monoclonal antibodies to an immunodominant region of native AChR bound neither H..cap alpha.. 125-147 nor T ..cap alpha.. 125-147. Rats immunized with H ..cap alpha.. 125-147 produced anti-mammalian muscle AChR antibodies that induced modulation of AChRs from cultured human myotubes. Thus, region 125-147 of the human AChR ..cap alpha.. subunit is extracellular in muscle, and is both antigenic and immunogenic. It remains to be determined whether or not autoantibodies to this region may in part cause the weakness or myasthenia gravis in man.

  4. RNF4 and VHL regulate the proteasomal degradation of SUMO-conjugated Hypoxia-Inducible Factor-2alpha.

    Science.gov (United States)

    van Hagen, Martijn; Overmeer, René M; Abolvardi, Sharareh S; Vertegaal, Alfred C O

    2010-04-01

    Hypoxia-inducible factors (HIFs) are critical transcription factors that mediate cell survival during reduced oxygen conditions (hypoxia). At regular oxygen conditions (normoxia), HIF-1alpha and HIF-2alpha are continuously synthesized in cells and degraded via the ubiquitin-proteasome pathway. During hypoxia, these proteins are stabilized and translocate to the nucleus to activate transcription of target genes that enable cell survival at reduced oxygen levels. HIF proteins are tightly regulated via post-translational modifications including phosphorylation, acetylation, prolyl-hydroxylation and ubiquitination. Here we show for the first time that exogenous and endogenous HIF-2alpha are also regulated via the ubiquitin-like modifier small ubiquitin-like modifiers (SUMO). Using mutational analysis, we found that K394, which is situated in the sumoylation consensus site LKEE, is the major SUMO acceptor site in HIF-2alpha. Functionally, sumoylation reduced the transcriptional activity of HIF-2alpha. Similar to HIF-1alpha, HIF-2alpha is regulated by the SUMO protease SENP1. The proteasome inhibitor MG132 strongly stabilized SUMO-2-conjugated HIF-2alpha during hypoxia but did not affect the total level of HIF-2alpha. The ubiquitin E3 ligases von Hippel-Lindau and RNF4 control the levels of sumoylated HIF-2alpha, indicating that sumoylated HIF-2alpha is degraded via SUMO-targeted ubiquitin ligases. PMID:20026589

  5. Lactobacillus casei secreting alpha-MSH induces the therapeutic effect on DSS-induced acute colitis in Balb/c Mice.

    Science.gov (United States)

    Yoon, Sun-Woo; Lee, Chul-Ho; Kim, Jeong-Yoon; Kim, Jie-Youn; Sung, Moon-Hee; Poo, Haryoung

    2008-12-01

    The neuropeptide alpha-melanocyte-stimulating hormone (alpha- MSH) has anti-inflammatory property by downregulating the expressions of proinflammatory cytokines. Because alpha-MSH elicits the anti-inflammatory effect in various inflammatory disease models, we examined the therapeutic effect of oral administration of recombinant Lactobacillus casei, which secretes alpha-MSH (L. casei-alpha-MSH), on dextran sulfate sodium (DSS)-induced colitis in Balb/c mice. Thus, we constructed the alpha-MSH-secreting Lactobacillus casei by the basic plasmid, pLUAT-ss, which was composed of a PldhUTLS promoter and alpha-amylase signal sequence from Streptococcus bovis strain. Acute colitis was induced by oral administration of 5% DSS in drinking water for 7 days. To investigate the effect of L. casei-alpha-MSH on the colitis, L. casei or L. casei-alpha-MSH was orally administered for 7 days and their effects on body weight, mortality rate, cytokine production, and tissue myeloperoxidase (MPO) activity were observed. Administration of L. casei-alpha-MSH reduced the symptom of acute colitis as assessed by body weight loss (DSS alone: 14.45+/-0. 2 g; L. casei-alpha- MSH: 18.2+/-0.12 g), colitis score (DSS alone: 3.6+/-0.4; L. casei-alpha-MSH: 1.4+/-0.6), MPO activity (DSS alone: 42.7+/-4.5 U/g; L. casei-alpha-MSH: 10.25+/-0.5 U/g), survival rate, and histological damage compared with the DSS alone mice. L. casei-alpha-MSH-administered entire colon showed reduced in vitro production of proinflammatory cytokines and NF-kappaB activation. The alpha-MSH-secreting recombinant L. casei showed significant anti-inflammatory effects in the murine model of acute colitis and suggests a potential therapeutic role for this agent in clinical inflammatory bowel diseases. PMID:19131702

  6. Alpha particle energy response of 1-mm-thick polycarbonate track detectors by 50 Hz-HV electrochemical etching method

    International Nuclear Information System (INIS)

    The electrochemical etching (ECE) method enlarges charged particle tracks to enhance its applications in particular in health physics and radiation dosimetry. The ECE method is usually based on using a high frequency-high voltage (HF-HV) generator with 250-μm-thick polycarbonate track detectors (PCTDs). The authors' recent studies on nitrogen and helium ions and alpha tracks in 1-mm-thick large-size PCTDs under a 50 Hz-HV ECE process provided promising results. In this study, alpha track efficiency and mean track diameter versus energy responses and registration energy range as well as alpha and background track shapes under three sets of 50 Hz-4, 5 and 6 kV applied field conditions have been studied and are reported. The efficiency versus alpha energy has a Bragg-type response from ∼15 keV to ∼4.5 MeV for the field conditions applied with an efficiency value of 40-50 % at the Bragg peak. The results are presented and discussed. (authors)

  7. Alpha band cortico-muscular coherence occurs in healthy individuals during mechanically-induced tremor.

    Science.gov (United States)

    Budini, Francesco; McManus, Lara M; Berchicci, Marika; Menotti, Federica; Macaluso, Andrea; Di Russo, Francesco; Lowery, Madeleine M; De Vito, Giuseppe

    2014-01-01

    The present work aimed at investigating the effects of mechanically amplified tremor on cortico-muscular coherence (CMC) in the alpha band. The study of CMC in this specific band is of particular interest because this coherence is usually absent in healthy individuals and it is an aberrant feature in patients affected by pathological tremors; understanding its mechanisms is therefore important. Thirteen healthy volunteers (23±4 years) performed elbow flexor sustained contractions both against a spring load and in isometric conditions at 20% of maximal voluntary isometric contraction (MVC). Spring stiffness was selected to induce instability in the stretch reflex servo loop. 64 EEG channels, surface EMG from the biceps brachii muscle and force were simultaneously recorded. Contractions against the spring resulted in greater fluctuations of the force signal and EMG amplitude compared to isometric conditions (pspring load, CMC in the alpha band was observed in 12 out of 13 volunteers. Partial directed coherence (PDC) revealed an increased information flow in the EMG to EEG direction in the alpha band (p<.05). Therefore, coherence in the alpha band between the sensory-motor cortex and the biceps brachii muscle can be systematically induced in healthy individuals by mechanically amplifying tremor. The increased information flow in the EMG to EEG direction may reflect enhanced afferent activity from the muscle spindles. These results may contribute to the understanding of the presence of alpha band CMC in tremor related pathologies by suggesting that the origin of this phenomenon may not only be at cortical level but may also be affected by spinal circuit loops. PMID:25514444

  8. Brain-computer interfacing using modulations of alpha activity induced by covert shifts of attention

    Directory of Open Access Journals (Sweden)

    Schmidt Nico M

    2011-05-01

    Full Text Available Abstract Background Visual brain-computer interfaces (BCIs often yield high performance only when targets are fixated with the eyes. Furthermore, many paradigms use intense visual stimulation, which can be irritating especially in long BCI sessions. However, BCIs can more directly directly tap the neural processes underlying visual attention. Covert shifts of visual attention induce changes in oscillatory alpha activity in posterior cortex, even in the absence of visual stimulation. The aim was to investigate whether different pairs of directions of attention shifts can be reliably differentiated based on the electroencephalogram. To this end, healthy participants (N = 8 had to strictly fixate a central dot and covertly shift visual attention to one out of six cued directions. Results Covert attention shifts induced a prolonged alpha synchronization over posterior electrode sites (PO and O electrodes. Spectral changes had specific topographies so that different pairs of directions could be differentiated. There was substantial variation across participants with respect to the direction pairs that could be reliably classified. Mean accuracy for the best-classifiable pair amounted to 74.6%. Furthermore, an alpha power index obtained during a relaxation measurement showed to be predictive of peak BCI performance (r = .66. Conclusions Results confirm posterior alpha power modulations as a viable input modality for gaze-independent EEG-based BCIs. The pair of directions yielding optimal performance varies across participants. Consequently, participants with low control for standard directions such as left-right might resort to other pairs of directions including top and bottom. Additionally, a simple alpha index was shown to predict prospective BCI performance.

  9. 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

  10. 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.

  11. The emission probabilities of long range alpha particles from even-even 244-252Cm isotopes

    CERN Document Server

    Santhosh, K P; Priyanka, B

    2014-01-01

    The alpha accompanied cold ternary fission of even-even 244Cm, 246Cm, 248Cm, 250Cm and 252Cm isotopes have been studied by taking the interacting barrier as the sum of Coulomb and proximity potential with the fragments in equatorial configuration. The favorable fragment combinations are obtained from the cold reaction valley plot and by calculating the relative yield for the charge minimized fragments. In the alpha accompanied ternary fission of 244Cm isotope, the highest yield is found for the fragment combination 110Ru+4He+130Sn, which possess near doubly magic nuclei 130Sn. For the ternary fission of 246Cm, 248Cm, 250Cm and 252Cm isotopes with 4He as light charged particle, the highest yield is obtained for the fragment combination with doubly magic nuclei 132Sn as the heavier fragment. The emission probabilities and kinetic energies of long range alpha particle have been computed for the 242,244,246,248Cm isotopes and are found to be in good agreement with the experimental data. The relative yields for th...

  12. An octahedral deformation with six alpha particles at the Z = 12 system, Mg nuclides: Third nucleons, Alpharons

    CERN Document Server

    Moon, Chang-Bum

    2016-01-01

    We suggest that the emergence of a large deformation in the magnesium, Mg, nuclides, especially at the Z = 12, N = 12, should be associated with an octahedral deformed shape. Within the framework of molecular geometrical symmetry, we find a possibility that the Z = 12, N = 12 system would form an octahedral structure consisting of six points of alpha(4He) particles, yielding the ground collectivity. With this point of view, we draw the following serial molecular structures; the Z = 10, N = 10, 20Ne, corresponds to a hexahedral, the Z = 8, N = 8, 16O, does to a tetrahedral, and the Z = 6, N = 6, 12C, does to a trigonal symmetry. Moreover, the Z = 2, N = 2, 4He(alpha), fits into a tetrahedral symmetry with four points of nucleons; two protons and two neutrons. The enhanced deformation at Z = 12 with N > 20 would be explained by a deformed shape related to an Ethene(Ethylene)-like skeleton with six alpha particles. The deformation at Z = 10, with N = 10 and 12, can be interpreted as being attributed to a hexahed...

  13. Aerosol nucleation induced by a high energy particle beam

    DEFF Research Database (Denmark)

    Enghoff, Martin Andreas Bødker; Pedersen, Jens Olaf Pepke; Uggerhøj, Ulrik I.;

    2011-01-01

    We have studied sulfuric acid aerosol nucleation in an atmospheric pressure reaction chamber using a 580 MeV electron beam to ionize the volume of the reaction chamber. We find a clear contribution from ion-induced nucleation and consider this to be the first unambiguous observation of the ion-effect...... on aerosol nucleation using a particle beam under conditions that resemble the Earth's atmosphere. By comparison with ionization using a gamma source we further show that the nature of the ionizing particles is not important for the ion-induced component of the nucleation. This implies that...

  14. Light emission from particle beam induced plasma - An overview

    CERN Document Server

    Ulrich, A

    2015-01-01

    Experiments to study the light emission from plasma produced by particle beams are presented. Fundamental aspects in comparison with discharge plasma formation are discussed. It is shown that the formation of excimer molecules is an important process. This paper summarizes various studies of particle beam induced light emission and presents first results of a direct comparison of light emission induced by electron- and ion beam excitation. Both high energy heavy ion beam and low energy electron beam experiments are described and an overview over applications in the form of light sources, lasers, and ionization devices is given.

  15. Alpha-particle emitting 213Bi-anti-EGFR immunoconjugates eradicate tumor cells independent of oxygenation.

    Directory of Open Access Journals (Sweden)

    Christian Wulbrand

    Full Text Available Hypoxia is a central problem in tumor treatment because hypoxic cells are less sensitive to chemo- and radiotherapy than normoxic cells. Radioresistance of hypoxic tumor cells is due to reduced sensitivity towards low Linear Energy Transfer (LET radiation. High LET α-emitters are thought to eradicate tumor cells independent of cellular oxygenation. Therefore, the aim of this study was to demonstrate that cell-bound α-particle emitting (213Bi immunoconjugates kill hypoxic and normoxic CAL33 tumor cells with identical efficiency. For that purpose CAL33 cells were incubated with (213Bi-anti-EGFR-MAb or irradiated with photons with a nominal energy of 6 MeV both under hypoxic and normoxic conditions. Oxygenation of cells was checked via the hypoxia-associated marker HIF-1α. Survival of cells was analysed using the clonogenic assay. Cell viability was monitored with the WST colorimetric assay. Results were evaluated statistically using a t-test and a Generalized Linear Mixed Model (GLMM. Survival and viability of CAL33 cells decreased both after incubation with increasing (213Bi-anti-EGFR-MAb activity concentrations (9.25 kBq/ml-1.48 MBq/ml and irradiation with increasing doses of photons (0.5-12 Gy. Following photon irradiation survival and viability of normoxic cells were significantly lower than those of hypoxic cells at all doses analysed. In contrast, cell death induced by (213Bi-anti-EGFR-MAb turned out to be independent of cellular oxygenation. These results demonstrate that α-particle emitting (213Bi-immunoconjugates eradicate hypoxic tumor cells as effective as normoxic cells. Therefore, (213Bi-radioimmunotherapy seems to be an appropriate strategy for treatment of hypoxic tumors.

  16. Regular endurance training reduces the exercise induced HIF-1alpha and HIF-2alpha mRNA expression in human skeletal muscle in normoxic conditions

    DEFF Research Database (Denmark)

    Lundby, Carsten; Gassmann, Max; Pilegaard, Henriette

    2005-01-01

    single exercise bout, and that this response is blunted with training. We obtained muscle biopsies from a trained (5 days/week during 4 weeks) and untrained leg from the same human subject before, immediately after, and during the recovery from a 3 h two-legged knee extensor exercise bout, where the two...... legs exercised at the same absolute workload. In the untrained leg, the exercise bout induced an increase (P<0.05) in HIF-1alpha fold and HIF-2alpha fold mRNA at 6 h of recovery. In contrast, HIF-1alpha and HIF-2alpha mRNA levels were not altered at any time point in the trained leg. Obviously, HIF-1......alpha and HIF-2alpha mRNA levels are transiently increased in untrained human skeletal muscle in response to an acute exercise bout, but this response is blunted after exercise training. We propose that HIFs expression is upregulated with exercise and that it may be an important transcription factor...

  17. Therapy with interferon-alpha plus ribavirin for membranoproliferative glomerulonephritis induced by hepatitis C virus

    Directory of Open Access Journals (Sweden)

    Edmundo P.A. Lopes

    2003-10-01

    Full Text Available We describe a treatment made with interferon-alpha (IFN-alpha plus ribavirin of two patients with membranoproliferative glomerulonephritis (MPGN induced by hepatitis C virus (HCV: Case 1 was a 22-year-old woman with leg and facial edema, hypertension and proteinuria, whose liver biopsy revealed chronic active hepatitis; and Case 2 was a 42-year-old man with anasarca, hypertension and proteinuria, whose liver biopsy indicated cirrhosis. Both had anti-HCV, HCV-RNA and cryoglobulins. IFN-alpha (3 million units (MU, 3 times/week and ribavirin (1 g/day were administered for 12 months. The drugs were well tolerated by both patients. Serum alanine aminotransferase (ALT levels normalized and HCV-RNA became negative. Cryoglobulins disappeared and an improvement in renal disease was seen after 6 months of therapy. However, after 9 months, Case 2 presented ALT elevation, and proteinuria was detected. Two years after the end of therapy, both patients were negative in repeated HCV-RNA and cryoglobulin tests. Case 1 was asymptomatic, with normal liver and renal tests, and Case 2 had normal blood pressure, with mild edema of the ankles. Based on the evolution of these two cases, the association of IFN-alpha and ribavirin may be a therapeutic option for patients with MPGN related to HCV.

  18. 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.

  19. 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

  20. 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)

  1. Expression of transforming growth factor alpha in plutonium-239-induced lung neoplasms in dogs: investigations of autocrine mechanisms of growth

    International Nuclear Information System (INIS)

    We have previously shown that 47% of radiation-induced lung neoplasms in dogs exhibit increased expression of epidermal growth factor receptor (EGFR). In this study, we investigated the expression of transforming growth factor alpha (TGF-alpha), a ligand for EGFR, to determine if an autocrine mechanism for growth stimulation was present in these tumors. As determined by immunohistochemistry, 59% (26/44) of the lung neoplasms examined had increased expression of TGF-alpha. Expression of TGF-alpha was not related to the etiology of the tumor, e.g., spontaneous or plutonium-induced; however, it was related to the phenotype of the tumor. Statistical analysis of the correlation of EGFR and TGF-alpha expression within the same tumor did not show a positive association; however, specific phenotypes did have statistically significant expression of EGFR or TGF-alpha, suggesting that overexpression of either the ligand or its receptor conferred a growth advantage to the neoplasm. Twenty-seven percent (32/117) of radiation-induced proliferative epithelial foci expressed TGF-alpha, and a portion of those foci (8/32) expressed both EGFR and TGF-alpha. This supports the hypothesis that these foci represent preneoplastic lesions, and suggests that those foci exhibiting increased expression of the growth factor or its receptor are at greater risk for progressing to neoplasia

  2. Do gamma rays and alpha particles cause different types of lung cancer? A comparison between atomic bomb survivors and uranium miners

    International Nuclear Information System (INIS)

    Excess lung cancer risk has been associated with exposure to alpha particle radiation from inhaled radon daughter products among uranium miners in Czechoslovakia, Canada, the United States, and elsewhere, and with exposure to gamma rays and neutrons from the atomic bombings of Hiroshima and Nagasaki, Japan. Differences in distribution by histological type, as well as certain epidemiological differences, suggest the possibility of differences in the causation of radiation-induced lung cancer. An epidemiological analysis is summarised of results from a blind pathology panel review of tissue slides from lung cancer cases diagnosed in 108 Japanese A bomb survivors and 92 American uranium miners selected on the basis of radiation exposure, smoking history, sex, age, and source and quality of pathology material. Consensus diagnoses were obtained with respect to principal sub-type, including squamous cell cancer, small cell cancer, adenocarcinoma, and less frequent sub-types. The results were analysed in terms of population, radiation dose, and smoking history. As expected, the proportion of squamous cell cancer was positively related to smoking history in both populations. The relative frequencies of small cell cancer and adenocarcinoma were very different in the two populations, but this difference was adequately accounted for by differences in radiation dose (more specifically, dose-based relative risk estimates based on published risk coefficients). Data for the two populations conformed to a common pattern, in which radiation-induced cancers appeared more likely to be of the small-cell sub-type, and less likely to be adenocarcinomas. No additional explanation in terms of radiation quality (alpha particles or gamma rays), uniform or local irradiation, inhaled as against external radiation source, or other population differences, appeared to be required. (author)

  3. Final Report (1994 to 1996) Diagnostic of the Spatial and Velocity Distribution of Alpha Particles in Tokamak Fusion Reactor using Beat-wave Generated Lower Hybrid Wave

    International Nuclear Information System (INIS)

    The alpha particles in a fusion reactor play a key role in the sustaining the fusion reaction. It is the heating provided by the alpha particles that help a fusion reactor operating in the ignition regime. It is, therefore, essential to understand the behavior of the alpha population both in real space and velocity space in order to design the optimal confinement device for fusion application. Moreover, the alphas represent a strong source of free energy that may generate plasma instabilities. Theoretical studies has identified the Toroidal Alfven Eigenmode (TAE) as an instability that can be excited by the alpha population in a toroidal device. Since the alpha has an energy of 3.5 MeV, a good confinement device will retain it in the interior of the plasma. Therefore, alpha measurement system need to probe the interior of a high density plasma. Due to the conducting nature of a plasma, wave with frequencies below the plasma frequency can not penetrate into the interior of the plasma where the alphas reside. This project uses a wave that can interact with the perpendicular motion of the alphas to probe its characteristics. However, this wave (the lower hybrid wave) is below the plasma frequency and can not be directly launched from the plasma edge. This project was designed to non-linearly excite the lower hybrid in the interior of a magnetized plasma and measure its interaction with a fast ion population

  4. Jet and inclusive particle production in photon induced collisions

    OpenAIRE

    Chyla, Jiri

    2005-01-01

    Recent progress in application of higher order QCD calculations to jet and inclusive particle production in photon induced collisions is reviewed. Attention is paid to theoretical uncertainties of such calculations, particularly those coming from the choice of renormalization and factorization scales.

  5. Dissipative Particle Dynamics of tension-induced membrane fusion

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2009-01-01

    Recent studies of tension-induced membrane fusion using dissipative particle dynamics (DPD) simulations are briefly reviewed. The stochastic nature of the fusion process makes it necessary to simulate a large number of fusion attempts in order to obtain reliable fusion statistics and to extract...

  6. 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

  7. 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.

  8. Fever and acute phase response induced in dwarf goats by endotoxin and bovine and human recombinant tumour necrosis factor alpha.

    Science.gov (United States)

    van Miert, A S; van Duin, C T; Wensing, T

    1992-12-01

    Tumour necrosis factor (TNF), a polypeptide produced by mononuclear phagocytes, has been implicated as an important mediator of inflammatory processes and of clinical manifestations in acute infectious diseases. To study further the potential role of TNF in infectious diseases, recombinant Escherichia coli (E. coli) derived human (r.HuTNF-alpha) and bovine TNF (r.BoTNF-alpha) were intravenously (i.v.) administered in dwarf goats. Rectal temperature, heart rate, rumen motility, plasma zinc and iron concentrations, and certain other blood biochemical and haematological values were studied and compared with the changes seen after E. coli endotoxin (LPS) was administered (dose: 0.1 microgram/kg i.v.). Following a single injection of 4 micrograms/kg of r.BoTNF-alpha, shivering and biphasic febrile response were observed, accompanied by tachycardia, inhibition of rumen contractions, drop in plasma zinc and iron concentrations, lymphopenia, and neutropenia followed by neutrophilia. The i.v. administration of a single injection of 4 micrograms/kg r.HuTNF-alpha induced shivering and biphasic febrile responses, accompanied by anorexia and a similar drop in plasma trace metal concentrations when compared with r.BoTNF-alpha-treated goats. The TNF-alpha-induced symptoms were essentially the same as those that occurred after LPS administration. However, the time of onset of these changes after the injection of TNF-alpha was significantly shorter than after LPS. Moreover, the r.BoTNF-alpha induced a longer lasting neutrophilic leucopenia, less neutrophilia, and a more persistent lymphopenia than after LPS injection. Neither r.BoTNF-alpha nor LPS caused severe haemo-concentration. Furthermore, no cross-tolerance between r.BoTNF-alpha and LPS could be demonstrated. We conclude that both r.BoTNF-alpha and r.HuTNF-alpha induce many of the physiologic, haematologic and metabolic changes that characterize the acute phase response to LPS. The overlapping biological activities of r.BoTNF-alpha

  9. 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.

  10. 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.

  11. The protective antibodies induced by a novel epitope of human TNF-alpha could suppress the development of collagen-induced arthritis.

    Directory of Open Access Journals (Sweden)

    Jie Dong

    Full Text Available Tumor necrosis factor alpha (TNF-alpha is a major inflammatory mediator that exhibits actions leading to tissue destruction and hampering recovery from damage. At present, two antibodies against human TNF-alpha (hTNF-alpha are available, which are widely used for the clinic treatment of certain inflammatory diseases. This work was undertaken to identify a novel functional epitope of hTNF-alpha. We performed screening peptide library against anti-hTNF-alpha antibodies, ELISA and competitive ELISA to obtain the epitope of hTNF-alpha. The key residues of the epitope were identified by means of combinatorial alanine scanning and site-specific mutagenesis. The N terminus (80-91 aa of hTNF-alpha proved to be a novel epitope (YG1. The two amino acids of YG1, proline and valine, were identified as the key residues, which were important for hTNF-alpha biological function. Furthermore, the function of the epitope was addressed on an animal model of collagen-induced arthritis (CIA. CIA could be suppressed in an animal model by prevaccination with the derivative peptides of YG1. The antibodies of YG1 could also inhibit the cytotoxicity of hTNF-alpha. These results demonstrate that YG1 is a novel epitope associated with the biological function of hTNF-alpha and the antibodies against YG1 can inhibit the development of CIA in animal model, so it would be a potential target of new therapeutic antibodies.

  12. Studies on alpha-amylase induced degradation of binary polymeric blends of crosslinked starch and pectin.

    Science.gov (United States)

    Bajpai, A K; Shrivastava, Jyoti

    2007-05-01

    A blend matrix of crosslinked starch and pectin was prepared and characterized by infra-red (IR) spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The prepared blends were investigated kinetically for water sorption studies and alpha-amylase induced degradation adopting a gravimetric procedure. Based on the experimental findings, a plausible mechanism including both diffusion and surface enhanced degradation was suggested and degradation profiles were interpreted. The influence of various factors such as chemical architecture of the blend, pH and temperature of alpha-amylase solution were examined for the swelling and degradation kinetics of crosslinked starch-pectin blends. The effect of concentration of enzyme solution was also studied on the degradation profile of the blends. A correlation was established between the extent of degradation and water imbibing capacity of the degrading blends. PMID:17143735

  13. Detection of Alpha Particles and Low Energy Gamma Rays by Thermo-Bonded Micromegas in Xenon Gas

    CERN Document Server

    Wei, Yuehuan; Zhang, Zhiyong; Lin, Qing; Wang, Xiaolian; Ni, Kaixuan; Zhao, Tianchi

    2013-01-01

    Micromegas is a type of micro-pattern gaseous detector currently under R&D for applications in rare event search experiments. Here we report the performance of a Micromegas structure constructed with a micromesh thermo-bonded to a readout plane, motivated by its potential application in two-phase xenon detectors for dark matter and neutrinoless double beta decay experiments. The study is carried out in pure xenon at room temperature. Measurements with alpha particles from the Americium-241 source showed that gas gains larger than 200 can be obtained at xenon pressure up to 3 atm. Gamma rays down to 8 keV were observed with such a device.

  14. Diffraction scattering of alpha particles on C, Al, Cu and Pb at 17.9 GeV/c

    International Nuclear Information System (INIS)

    New data on the diffraction scattering of relativistic alpha particles on C, Al, Cu and Pb targets at incident momentum of 17.9 GeV/c are presented. Differential cross sections at four-momentum transfers squared |t| ranging from 0.038 (GeV/c)2 up to 0.55 (GeV/c)2 have been measured with an accuracy of 3% of the absolute normalization. These data are compared with the predictions of the Glauber-Sitenko multiple scattering theory. (author)

  15. Attempt of analysis of the elastic scattering of 44 MeV alpha particles using a phase shift parameterization

    International Nuclear Information System (INIS)

    In order to ease the resolution of the problem of interaction of an alpha particle with a nucleus, and determine simpler hypotheses which enable the analysis of experimental results, this research thesis reports the use of a parameterization of phase shifts to reduce ambiguities and the number of parameters. After general remarks, a description of the Hamiltonian and a formulation of phase shifts, the author presents experimental data and the analytical method. Analysis is then performed for two-, three-, four- or five-parameter formulations. Efficient cross sections are then studied

  16. Gravitationally Induced Particle Production: Thermodynamics and Kinetic Theory

    CERN Document Server

    Lima, J A S

    2014-01-01

    A relativistic kinetic description for the irreversible thermodynamic process of gravitationally induced particle production is proposed in the context of an expanding Friedmann-Robertson-Walker (FRW) geometry. We show that the covariant thermodynamic treatment referred to as "adiabatic" particle production provoked by the cosmic time-varying gravitational field has a consistent kinetic counterpart. The variation of the distribution function is associated to a non-collisional kinetic term of quantum-gravitational origin which is proportional to the ratio $\\Gamma/H$, where $\\Gamma$ is the gravitational particle production rate and H is the Hubble parameter. For $\\Gamma << H$ the process is negligible and as should be expected it also vanishes (regardless of the value of $\\Gamma$) in the absence of gravitation. The resulting non-equilibrium distribution function has the same functional form of equilibrium with the evolution laws corrected by the particle production process. The macroscopic temperature evo...

  17. 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)

  18. Very High Efficiency, Miniaturized, Long-Lived Alpha Particle Power Source Using Diamond Devices for Extreme Space Environments

    Science.gov (United States)

    Kolawa, Elizabeth A. (Inventor); Patel, Jagdishbhai U. (Inventor); Fleurial, Jean-Pierre (Inventor)

    2004-01-01

    A power source that converts a-particle energy into electricity by coulomb collision in doped diamond films is described. Alpha particle decay from curium-244 creates electron-hole pairs by free- ing electrons and holes inside the crystal lattice in N- and P-doped diamond films. Ohmic contacts provide electrical connection to an electronic device. Due to the built-in electric field at the rectifying junction across the hT- and P-doped diamond films, the free electrons are constrained to traveling in generally one direction. This one direction then supplies electrons in a manner similar to that of a battery. The radioactive curium layer may be disposed on diamond films for even distribution of a-particle radiation. The resulting power source may be mounted on a diamond substrate that serves to insulate structures below the diamond substrate from a-particle emission. Additional insulation or isolation may be provided in order to prevent damage from a-particle collision. N-doped silicon may be used instead of N-doped diamond.

  19. 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.

  20. Backangle anomaly in scattering of {alpha} -particles from {sup 28} Si at low energies[25.55.Ci; 25.70.Ef; Nuclear reactions 28 Si( {alpha},{alpha})28 Si; E{alpha}=3.0 -7.8 MeV; Measured {sigma}(E{alpha},{theta}); {theta}lab=30 deg. -175 deg.; Deduced Regge-pole parameters; Natural target

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-09-25

    In order to resolve the differences in the literature on the existence of quasi-molecular states in the {alpha} -{sup 28} Si system, excitation functions were measured for the scattering of {alpha} -particles from {sup 28} Si in the incident energy range E{sub lab}=3 -7.8 MeV. An angular distribution measurement was carried out in the angular range {theta}{sub lab}=30 deg. -174.5 deg. for every potential resonance observed in the excitation functions. Data was analysed using a Regge-pole formalism by coherently adding specific resonances to an underlying diffraction term calculated by a strong absorption model. Furthermore, the usual compound elastic contribution was incoherently added to the direct interaction part of the cross section. The 6.8 MeV resonance was confirmed with J=3 and some evidence was observed for a J=1 resonance around 6.0 MeV.

  1. Ultrastructure of rat sciatic nerve at the streptozotocin-induced neuropathy conditions under administration of alpha-lipoic acid preparations

    Directory of Open Access Journals (Sweden)

    Dronov S.M.

    2014-09-01

    Full Text Available Dronov S.M. Ultrastructure of rat sciatic nerve at the streptozotocin-induced neuropathy conditions under administration of alpha-lipoic acid preparations. ABSTRACT. Background. Diabetic polyneuropathy is one of the most common long-term complications of diabetes. Hyperglycemias caused by ischemia and peroxidation of lipids are the presumed cause of diabetic neuropathy. Appointment of alpha-lipoic acid can restore the function of peripheral nerves, preventing the development of autonomic and trophic disorders. Objective. To determine the extent of changes in the ultrastructure of the sciatic nerve in rats with streptozotocin-induced simulated peripheral neuropathy in experimental therapy with α-lipoic acid. Methods. The research was conducted on 22 white rats divided randomly in 3 groups: group 1 – intact animals; group 2 – rats with streptozotocin-induced neuropathy; group 3 – rats with streptozotocin neuropathy + alpha-lipoic acid. Diabetes mellitus was induced in rats by a single intraperitoneal injection of streptozotocin (50 mg/kg. Alpha-lipoic acid was administered intraperitoneally and intragastrically once per day during 40 days from the 56th day after streptozotocin injection. Transmission electron microscopy was performed on the 40th day of alpha-lipoic acid administration. Results. Administration of alpha-lipoic acid activates compensatory-adaptive processes in neuronal cells, reduces the severity of violations in the composition of myelinated nerve fibers, contributes to a distinct axonal spruting, causes the reduction of asymmetrically distributed electron density in the lamellar structure of myelin, indicating an increase in the insulation of axons of the sciatic nerve fibers of rats. Conclusion. Experimental studies confirm high neuroprotective potential of alpha-lipoic acid in streptozotocin-induced neuropathy. Citation: Dronov SM. [Ultrastructure of rat sciatic nerve at the streptozotocin-induced neuropathy conditions

  2. Regional deposition of particles in human lung after induced bronchoconstriction.

    Science.gov (United States)

    Svartengren, M; Philipson, K; Linnman, L; Camner, P

    1986-01-01

    The percentage 24-hr lung retention (Ret24), a measure of penetration to the aveoli, of 4 micron monodispersed Teflon particles, aerodynamic diameter 6 micron, was studied in 8 healthy nonsmokers. The particles were inhaled at 0.2 1/sec with maximally deep breaths. Bronchoconstriction was induced by inhalation of a methacholinebromide aerosol for one exposure before and for one exposure after inhalation of the Teflon particles. Airway resistance (Raw) was measured using a whole body pletysmograph before and after the induction of bronchoconstriction and increased on an average by a factor 2-3. Ret24 was significantly lower when the Teflon particles were inhaled during bronchoconstriction than when bronchoconstriction was induced after inhalation of the Teflon particles, 26 +/- 12% and 48 +/- 6% (mean +/- SD), respectively. These experimental data agree fairly well with data on deposition due to impaction and sedimentation using a lung model where the diameters of the airways were varied so that an increase in airway resistance occurs similar to that produced in our experimental subjects. However, the experimental data tended to be lower than the theoretical ones when the particles were inhaled during the induced bronchoconstriction. In this study, where the mucociliary transport system was stimulated by methacholinebromide, the percentage 3-hr retention (Ret3) was highly correlated with Ret24, r = 0.97, i.e., Ret3 can be used instead of the Ret24. This implies that radionuclides with shorter half-lives which give lower radiation doses, can be used, and that subjects can be studied within shorter periods of time. PMID:3516667

  3. Peroxidation of the dried thin film of lipid by high-energy alpha particles from a cyclotron

    International Nuclear Information System (INIS)

    High-energy α particles produced a dose-dependent linear increase in different lipid peroxidation products (e.g., malondialdehyde (MDA), conjugated dienes, and hydroperoxides) in the dried thin film state. An inverse dose-rate effect was observed when the dose rate was varied by changing either the α-particle fluence rate or the α-particle energy. The antioxidants α-tocopherol and butylated hydroxytoluene (BHT) suppressed the α-particle-induced lipid peroxidation in the dried thin film state, and in this respect α-tocopherol was found superior to BHT. It was found that α-tocopherol was equally efficient in inhibiting lipid peroxidations by α particles and ultraviolet light

  4. Choline kinase alpha expression during RA-induced neuronal differentiation: role of C/EBPβ.

    Science.gov (United States)

    Domizi, Pablo; Aoyama, Chieko; Banchio, Claudia

    2014-04-01

    Neuronal differentiation is a complex process characterized by a halt in proliferation and extension of neurites from the cell body. This process is accompanied by changes in gene expression that mediate the redirection leading to neurite formation and function. Acceleration of membrane phospholipids synthesis is associated with neurite elongation, and phosphatidylcholine (PtdCho) is the major membrane phospholipid in mammalian cells. The transcription of two genes in particular encoding key enzymes in the CDP-choline pathway for PtdCho biosynthesis are stimulated; the Chka gene for choline kinase (CK) alpha isoform and the Pcyt1a gene for the CTP:phosphocholine cytidylyltransferase (CCT) alpha isoform. We report that the stimulation of CKα expression during retinoic acid (RA) induced differentiation depends on a promoter region that contains two CCAAT/Enhancer-binding Protein-β (C/EBPβ) sites. We demonstrate that during neuronal differentiation of Neuro-2a cells, RA induces Chka expression by a mechanism that involves ERK1/2 activation which triggers C/EBPβ expression. Elevated levels of C/EBPβ bind to the Chka proximal promoter (Box1) inducing CKα expression. In addition we identified a downstream sequence named Box2 which together with Box1 is required for the promoter to reach the full induction. This is the first elucidation of the mechanism by which the expression of Chka is coordinately regulated during neuronal differentiation. PMID:24440820

  5. Comprehensive evaluation of the linear stability of Alfv\\'en eigenmodes driven by alpha particles in an ITER baseline scenario

    CERN Document Server

    Figueiredo, A C A; Borba, D; Coelho, R; Fazendeiro, L; Ferreira, J; Loureiro, N F; Nabais, F; Pinches, S D; Polevoi, A R; Sharapov, S E

    2016-01-01

    The linear stability of Alfv\\'en eigenmodes in the presence of fusion-born alpha particles is thoroughly assessed for two variants of an ITER baseline scenario, which differ significantly in their core and pedestal temperatures. A systematic approach is used that considers all possible eigenmodes for a given magnetic equilibrium and determines their growth rates due to alpha-particle drive and Landau damping on fuel ions, helium ashes and electrons. This extensive stability study is efficiently conducted through the use of a specialized workflow that profits from the performance of the hybrid MHD drift-kinetic code $\\mbox{CASTOR-K}$ (Borba D. and Kerner W. 1999 J. Comput. Phys. ${\\bf 153}$ 101; Nabais F. ${\\it et\\,al}$ 2015 Plasma Sci. Technol. ${\\bf 17}$ 89), which can rapidly evaluate the linear growth rate of an eigenmode. It is found that the fastest growing instabilities in the aforementioned ITER scenario are core-localized, low-shear toroidal Alfv\\'en eigenmodes. The largest growth-rates occur in the s...

  6. 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

  7. Exercise and IL-6 infusion inhibit endotoxin-induced TNF-alpha production in humans

    DEFF Research Database (Denmark)

    Starkie, Rebecca; Ostrowski, Sisse Rye; Jauffred, Sune;

    2003-01-01

    and atherosclerosis. To test this hypothesis, we performed three experiments in which eight healthy males either rested (CON), rode a bicycle for 3 h (EX), or were infused with recombinant human IL-6 (rhIL-6) for 3 h while they rested. After 2.5 h, the volunteers received a bolus of Escherichia coli...... exercise and rhIL-6 infusion at physiological concentrations inhibit endotoxin-induced TNF-alpha production in humans. Hence, these data provide the first experimental evidence that physical activity mediates antiinflammatory activity and suggest that the mechanism include IL-6, which is produced...

  8. Lung cancer induced in hamsters by low doses of alpha radiation from 210Po

    International Nuclear Information System (INIS)

    Lung cancers have been induced in 9 to 53 percent of hamsters given multiple intratracheal instillations of polonium-210 in amounts yielding lifetime exposures of 15 to 300 rads to the lungs. Cigarette smokers have previously been estimated to receive 20 rads to areas of the bronchial epithelium from deposited polonium-210. This finding thus supports the hypothesis that alpha radiation resulting from the polonium-210 or lead-210 present in cigarette smoke may be a significant causative factor in human lung cancer. (U.S.)

  9. Alpha particle interactions with nuclei at 12 A GeV/c

    International Nuclear Information System (INIS)

    Pseudo-rapidity density distributions of shower particles from 12 A GeV/c α-emulsion interactions are presented. As compaerd to extrapolations from p-nucleus data, the central α+(Ag,Br) interactions exhibit an excess of particles in the mid pseudo-rapidity region. The correlation between and -1 are understood within a wounded nucleon model. (Author)

  10. 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

  11. 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

  12. Charged particle induced prompt nuclear reaction and its applications

    International Nuclear Information System (INIS)

    Charged particle induced prompt nuclear reaction analysis (PNR) not only can analyze the content and concentration of elements in sample sensitively and accurately, but also can measure the distributions of elements with depth in surface and near surface layer. And the method is very simple, rapid and nondestructive, and has good depth resolution. So the PNR is very widely used in many modern science and technique field such as solid state physics, surface physics, electrochemistry, metallurgy and material science and so on. This paper deals with the principle, method and the features of the nuclear reaction analysis induced by charged particle. Especially, the distribution analysis of impurities in sample with depth and the improvement of the depth resolution are discussed in detail. Some actual examples of its application are given

  13. Dissipative Particle Dynamics of Tension-induced Membrane Fusion

    OpenAIRE

    Grafmueller, Andrea; Lipowsky, Reinhard; Shillcock, Julian C.

    2009-01-01

    Abstract Recent studies of tension-induced membrane fusion using dissipative particle dynamics (DPD) simulations are briefly reviewed. The stochastic nature of the fusion process makes it necessary to simulate a large number of fusion attempts in order to obtain reliable fusion statistics and to extract meaningful values for the fusion probability and the average fusion times. All successful fusion events follow the same pathway. In this fusion pathway, configurations of individual...

  14. Inhibiting wear particles-induced osteolysis with doxycycline

    Institute of Scientific and Technical Information of China (English)

    Chao ZHANG; Ting-ting TANG; Wei-ping REN; Xiao-ling ZHANG; Ke-rong DAI

    2007-01-01

    Aim: To study the effect of doxycycline (DOX) on osteoclastogenesis, mature osteoclast fate and function, wear particles-induced osteoeolysis, and to provide some foundation for treating aseptic loosening and osteolysis after joint arthroplasty. Methods: Osteoclasts were generated from mouse bone marrow monocytes with the receptor activator of NF-κB ligand and the macrophage colony stimulating factor. DOX at a concentration of 5, 10, 15, and 20 μg/mL was respectively added to the medium. Seven days later, the osteoclasts were determined through tartrate-resistant acid phosphatase (TRAP) staining. Mature osteoclasts were isolated from newborn rabbits and cultured for 3 d in 24-well plates or on bone slices. DOX at a concentration of 5, 10, 15, and 20 μg/mL was respectively added to the medium. After TRAP staining, the osteoclasts were counted, resorption on bone slices was quantified, and the area was calculated after to luidine blue and Mayer-hematoxylin staining. Polymethyl methacrylate (PMMA) or ultra-high molecular weight polyethylene (UHMWPE) particles were implanted on the calvariae of C57BL/J6 mice. DOX, at a dose of 2 and 10 mg-kg-1.d-1, was respectively given in traperitoneally for 7 d. Seven days later, the calvariae were removed and processed for pathological analysis. Results: DOX treatment effectively inhibited in vitro osteoclastogenesis, affected the fate of mature osteoclasts, and inhibited mature osteoclasts, causing bone resorption. In vivo data indicated that DOX strongly inhibited PMMA or UHMWPE-induced osteolysis and osteoclastogenesis. Conclusion: DOX can effectively inhibit osteoclastogenesis and affect mature osteoclast fate and suppress wear particles induced by osteoly-sis and osteoclastogenesis. DOX might be useful in the treatment or prevention of wear particles-induced osteolysis and aseptic loosening for its effect on osteoclast generation and mature osteoclast fate and function.

  15. ICRH induced particle losses in Wendelstein 7-X

    Science.gov (United States)

    Faustin, J. M.; Cooper, W. A.; Graves, J. P.; Pfefferlé, D.; Geiger, J.

    2016-07-01

    Fast ions in W7-X will be produced either by neutral beam injection (NBI) or by ion-cyclotron resonant heating (ICRH). The latter presents the advantage of depositing power locally and does not suffer from core accessibility issues (Drevlak et al 2014 Nucl. Fusion 54 073002). This work assesses the possibility of using ICRH as a fast ion source in W7-X relevant conditions. The SCENIC package is used to resolve the full wave propagation and absorption in a three-dimensional plasma equilibrium. The source of the ion-cyclotron range of frequency (ICRF) wave is modelled in this work by an antenna formulation allowing its localisation in both the poloidal and toroidal directions. The actual antenna dimension and localization is therefore approximated with good agreement. The local wave deposition breaks the five-fold periodicity of W7-X. It appears that generation of fast ions is hindered by high collisionality and significant particle losses. The particle trapping mechanism induced by ICRH is found to enhance drift induced losses caused by the finite orbit width of trapped particles. The inclusion of a neoclassically resolved radial electric field is also investigated and shows a significant reduction of particle losses.

  16. Long-term therapy of interferon-alpha induced pulmonary arterial hypertension with different PDE-5 inhibitors: a case report

    Directory of Open Access Journals (Sweden)

    Baumann Gert

    2005-09-01

    Full Text Available Abstract background Interferon alpha2 is widely used in hepatitis and high-risk melanoma. Interferon-induced pulmonary arterial hypertension as a side effect is rare. Case presentation We describe a melanoma patient who developed severe pulmonary arterial hypertension 30 months after initiation of adjuvant interferon alpha2b therapy. Discontinuation of interferon did not improve pulmonary arterial hypertension. This patient could be treated successfully with phosphodiesterase-5 inhibitor therapy. Conclusion This is only the 5th case of interferon-induced pulmonary arterial hypertension and the first documented case where pulmonary arterial hypertension was not reversible after termination of interferon alpha2 therapy. If interferon alpha2 treated patients develop respiratory symptoms, pulmonary arterial hypertension should be considered in the differential diagnosis. For these patients phosphodiesterase-5 inhibitors, e.g. sildenafil or vardenafil, could be an effective therapeutic approach.

  17. Radiation-induced peroxidation of lipid dissolved in organic solvent and its inhibition by alpha-tocopherol and cepharanthine

    International Nuclear Information System (INIS)

    Effects of cepharanthine and alpha-tocopherol on radiation-induced peroxidation of lipids dissolved in methanol(MeOH)-chloroform (CHCl3)-H2O(v/v, 2/1/0.8) were examined. alpha-Tocopherol strongly inhibited radiation-induced peroxidation of lipids dissolved in MeOH-CHCl3-H2O. However, cepharanthine exhibited a weak inhibitory action in this system. The change in the absorption spectrum of alpha-tocopherol and cepharanthine by X-irradiation was measured. The reagents were dissolved in 95% EtOH acidified with 20 mM HCl and in MeOH-CHCl3-H2O. alpha-Tocopherol exhibited the change in its absorption spectrum in both systems, and seemed to be oxidized at a high rate by free radicals. However, cepharanthine slightly exhibited the change in its spectrum in MeOH-CHCl3-H2O, but not in acidified EtOH

  18. Radiation-induced peroxidation of lipid dissolved in organic solvent and its inhibition by alpha-tocopherol and cepharanthine

    Energy Technology Data Exchange (ETDEWEB)

    Shiraishi, N.; Joja, I.; Kuroda, M.; Fujishima, M.; Miyake, M.; Aono, K.

    1985-01-01

    Effects of cepharanthine and alpha-tocopherol on radiation-induced peroxidation of lipids dissolved in methanol(MeOH)-chloroform (CHCl3)-H2O(v/v, 2/1/0.8) were examined. alpha-Tocopherol strongly inhibited radiation-induced peroxidation of lipids dissolved in MeOH-CHCl3-H2O. However, cepharanthine exhibited a weak inhibitory action in this system. The change in the absorption spectrum of alpha-tocopherol and cepharanthine by X-irradiation was measured. The reagents were dissolved in 95% EtOH acidified with 20 mM HCl and in MeOH-CHCl3-H2O. alpha-Tocopherol exhibited the change in its absorption spectrum in both systems, and seemed to be oxidized at a high rate by free radicals. However, cepharanthine slightly exhibited the change in its spectrum in MeOH-CHCl3-H2O, but not in acidified EtOH.

  19. Simulated ablation of carbon wall by alpha particles for a laser fusion reactor

    International Nuclear Information System (INIS)

    Thermal reactions of materials heated by charged particles may lead to serious damage in a laser fusion reactor. When charged particles irradiate and heat the wall material with high intensity like at above 109 W/cm2, the material can be ablated. Once the wall is ablated, expanding gas or plasma can disturb the propagation of laser light irradiating the fuel target if it stagnates long enough for next laser shot. In order to understand the ablation dynamics in detail, we have performed 1-D hydro simulation to evaluate this ablation. As a new feature, we introduce the calculation of energy deposition by charged particles focusing on the interaction between ablated material and charged particles

  20. Energy resolution for alpha particles in liquid argon doped with allene

    International Nuclear Information System (INIS)

    The charge response of liquid argon doped with small quantities of allene (C3H4) to α-particles has been studied. The addition of allene increased the amount of collected charge through photoionization and greatly improved the energy resolution of the incident α-particles. The noise subtracted resolution was 1.4% FWHM at the best with 4 ppm allene doped liquid argon. (orig.)