Science.gov

Sample records for delayed alpha particles

  1. Further measurement of the {beta}-delayed {alpha}-particle emission of {sup 16}N

    SciTech Connect

    France III, R. H.; Wilds, E. L.; McDonald, J. E.; Gai, M.

    2007-06-15

    We measured the {beta}-delayed {alpha}-particle emission spectrum of {sup 16}N with a sensitivity for {beta}-decay branching ratios of the order of 10{sup -10}. The {sup 16}N nuclei were produced using the d({sup 15}N,{sup 16}N)p reaction with 70 MeV {sup 15}N beams and a deuterium gas target 7.5 cm long at a pressure of 1250 torr. The {sup 16}N nuclei were collected (over 10 s) using a thin aluminum foil with an areal density of 180 {mu}g/cm{sup 2} 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 ({sup 148}Gd, {sup 241}Am, {sup 208,209}Po, and {sup 227}Ac) as well as {alpha} particles and {sup 7}Li from the {sup 10}B(n,{alpha}){sup 7}Li 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}-delayed {alpha}-particle emission from {sup 8}Li that was produced using the d({sup 7}Li,{sup 8}Li)p reaction with the same setup. The line shape was corrected to account for the variation in the energy and time resolution and a high statistics spectrum of the {beta}-delayed {alpha}-particle emission of {sup 16}N is reported. However, our data (as well as earlier Mainz data and unpublished Seattle data) do not agree with an earlier measurement of the {beta}-delayed {alpha}-particle emission of {sup 16}N taken at TRIUMF after averaging over the energy resolution of our collection system. This disagreement, among other issues, prohibits accurate inclusion of the f-wave component in the R-matrix analysis.

  2. Radiation-induced genomic instability: delayed mutagenic and cytogenetic effects of X rays and alpha particles.

    PubMed

    Little, J B; Nagasawa, H; Pfenning, T; Vetrovs, H

    1997-10-01

    The frequency of mutations at the Hprt locus was measured in clonal populations of Chinese hamster ovary cells derived from single cells surviving exposure to 0-12 Gy of X rays or 2 Gy of alpha particles. Approximately 8-9% of 446 clonal populations examined 23 population doublings after irradiation showed high frequencies of late-arising mutations as indicated by mutant fractions 10(2)-10(4)-fold above background. The frequency with which such clones occurred was similar for alpha-particle irradiation and X irradiation, with no apparent dose dependence for X irradiation over the range of 4-12 Gy. The molecular structure of Hprt mutations was determined by analysis by multiplex polymerase chain reaction of all nine exons. Of mutations induced directly after exposure to X rays, 75% involved partial or total gene deletions. Only 19-23% of late-arising (delayed) mutations were associated with deletions, the preponderance of these being partial deletions involving one or two exons. This spectrum was very similar to that for spontaneously arising mutations. To determine whether delayed mutations were non-clonal, the spectrum of exons deleted was examined among 29 mutants with partial deletions derived from a single clonal population. The results indicated that at least 15 of these mutants arose independently. To examine the relationship between the occurrence of delayed mutations and chromosomal instability, 60 Hprt mutant subclones isolated from a clonal population showing a high frequency of delayed mutations were serially cultivated in vitro. Of these, 14 showed a slow-growth phenotype with a high frequency of polyploid cells (10-38%) and a markedly enhanced frequency of non-clonal chromosomal rearrangements including both chromosome-type and chromatid-type aberrations. These clones also showed a 3- to 30-fold increase in the frequency of ouabain-resistant mutations; no ouabain-resistant mutants were induced directly by X irradiation. These results suggest that among

  3. Imaging alpha particle detector

    DOEpatents

    Anderson, David F.

    1985-01-01

    A method and apparatus for detecting and imaging alpha particles sources is described. A conducting coated high voltage electrode (1) and a tungsten wire grid (2) 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 (3) to be quantitatively or qualitatively analyzed. A thin polyester film window (4) 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.

  4. Imaging alpha particle detector

    DOEpatents

    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.

  5. Alpha-particle diagnostics

    SciTech Connect

    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.

  6. Alpha Particle Diagnostic

    SciTech Connect

    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.

  7. Summary of Alpha Particle Transport

    SciTech Connect

    Medley, S.S.; White, R.B.; Zweben, S.J.

    1998-08-19

    This paper summarizes the talks on alpha particle transport which were presented at the 5th International Atomic Energy Agency's Technical Committee Meeting on "Alpha Particles in Fusion Research" held at the Joint European Torus, England in September 1997.

  8. Alpha-particle microdosimetry.

    PubMed

    Chouin, Nicolas; Bardies, Manuel

    2011-07-01

    With the increasing availability of alpha emitters, targeted α-particle therapy has emerged as a solution of choice to treat haematological cancers and micrometastatic and minimal residual diseases. Alpha-particles are highly cytotoxic because of their high linear energy transfer (LET) and have a short range of a few cell diameters in tissue, assuring good treatment specificity. These radiologic features make conventional dosimetry less relevant for that context. Stochastic variations in the energy deposited in cell nuclei are important because of the microscopic target size, low number of α- particle traversals, and variation in LET along the α-particle track. Microdosimetry provides a conceptual framework that aims at a systematic analysis of the stochastic distribution of energy deposits in irradiated matter. The different quantities of microdosimetry and the different methods of microdosimetric calculations were described in the early eighties. Since then, numerous models have been published through the years and applied to analyse experimental data or to model realistic therapeutic situations. Major results have been an accurate description of the high toxicity of α-particles, and the description of the predominant effect of activity distribution at the cellular scale on toxicity or efficacy of potential targeted α-particle therapies. This last factor represents a major limitation to the use of microdosimetry in vivo because determination of the source - target distribution is complicated. The future contributions of microdosimetry in targeted α-particle therapy research will certainly depend on the ability to develop high-resolution detectors and on the implementation of pharmaco-kinetic models at the tumour microenvironment scale.

  9. Long range alpha particle detector

    DOEpatents

    MacArthur, D.W.; Wolf, M.A.; McAtee, J.L.; Unruh, W.P.; Cucchiara, A.L.; Huchton, R.L.

    1993-02-02

    An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

  10. Alpha particle emitters in medicine

    SciTech Connect

    Fisher, D.R.

    1989-09-01

    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 ({sup 211}At) and natural bismuth-212 ({sup 212}Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 ({sup 223}Ra) 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.

  11. Alpha-particle spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.; Bjorkholm, P.

    1972-01-01

    Mapping the radon emanation of the moon was studied to find potential areas of high activity by detection of radon isotopes and their daughter products. It was felt that based on observation of regions overflown by Apollo spacecraft and within the field of view of the alpha-particle spectrometer, a radon map could be constructed, identifying and locating lunar areas of outgassing. The basic theory of radon migration from natural concentrations of uranium and thorium is discussed in terms of radon decay and the production of alpha particles. The preliminary analysis of the results indicates no significant alpha emission.

  12. Prospects for alpha particle studies on TFTR

    SciTech Connect

    Zweben, S.J.

    1987-05-01

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

  13. Radioimmunotherapy with alpha-particle emitting radionuclides.

    PubMed

    Zalutsky, M R; Pozzi, O R

    2004-12-01

    An important consideration in the development of effective strategies for radioimmunotherapy is the nature of the radiation emitted by the radionuclide. Radionuclides decaying by the emission of alpha-particles offer the possibility of matching the cell specific reactivity of monoclonal antibodies with radiation with a range of only a few cell diameters. Furthermore, alpha-particles have important biological advantages compared with external beam radiation and beta-particles including a higher biological effectiveness, which is nearly independent of oxygen concentration, dose rate and cell cycle position. In this review, the clinical settings most likely to benefit from alpha-particle radioimmunotherapy will be discussed. The current status of preclinical and clinical research with antibodies labeled with 3 promising alpha-particle emitting radionuclides - (213)Bi, (225)Ac, and (211)At - also will be summarized.

  14. Alpha-particles for targeted therapy.

    PubMed

    Sgouros, George

    2008-09-01

    Alpha-particles are helium nuclei that deposit DNA damaging energy along their track that is 100 to 1000 times greater than that of conventionally used beta-particle emitting radionuclides for targeted therapy; the damage caused by alpha-particles is predominately double-stranded DNA breaks severe enough so as to be almost completely irreparable. This means that a small number of tracks through a cell nucleus can sterilize a cell and that, because the damage is largely irreparable, alpha-particle radiation is not susceptible to resistance as seen with external radiotherapy (e.g., in hypoxic tissue). The ability of a single track to influence biological outcome and the stochastic nature of alpha-particle decay require statistical or microdosimetric techniques to properly reflect likely biological outcome when the biologically relevant target is small or when a low number of radionuclide decays have occurred. In therapeutic implementations, microdosimetry is typically not required and the average absorbed dose over a target volume is typically calculated. Animal and cell culture studies have shown that, per unit absorbed dose, the acute biological effects of alpha-particles are 3 to 7 times greater than the damage caused by external beam or beta-particle radiation. Over the past ten to 15 years, alpha-particle emitting radionuclides have been investigated as a possible new class of radionuclides for targeted therapy. Results from the small number of clinical trials reported to date have shown efficacy without significant toxicity.

  15. Nuclear diagnostic for fast alpha particles

    DOEpatents

    Grisham, L.R.; Post, D.E. Jr.; Dawson, J.M.

    1983-11-23

    This invention relates generally to high energy confined plasmas and more particularly is directed to measuring the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a confined energetic plasma.

  16. Alpha particle spectrometry using superconducting microcalorimeters

    NASA Astrophysics Data System (ADS)

    Horansky, Robert; Ullom, Joel; Beall, James; Hilton, Gene; Stiehl, Gregory; Irwin, Kent; Plionis, Alexander; Lamont, Stephen; Rudy, Clifford; Rabin, Michael

    2009-03-01

    Alpha spectrometry is the preferred technique for analyzing trace samples of radioactive material because the alpha particle flux can be significantly higher than the gamma-ray flux from nuclear materials of interest. Traditionally, alpha spectrometry is performed with Si detectors whose resolution is at best 8 keV FWHM. Here, we describe the design and operation of a microcalorimeter alpha detector with an energy resolution of 1.06 keV FWHM at 5 MeV. We demonstrate the ability of the microcalorimeter to clearly resolve the alpha particles from Pu-239 and Pu-240, whose ratio differentiates reactor-grade Pu from weapons-grade. We also show the first direct observation of the decay of Po-209 to the ground state of Pb-205 which has traditionally been obscured by a much stronger alpha line 2 keV away. Finally, the 1.06 keV resolution observed for alpha particles is far worse than the 0.12 keV resolution predicted from thermal fluctuations and measurement of gamma-rays. The cause of the resolution degradation may be ion damage in the tin. Hence, alpha particle microcalorimeters may provide a novel tool for studying ion damage and lattice displacement energies in bulk materials.

  17. Alpha-particle fluence in radiobiological experiments.

    PubMed

    Nikezic, Dragoslav; Yu, Kwan Ngok

    2016-11-03

    Two methods were proposed for determining alpha-particle fluence for radiobiological experiments. The first involved calculating the probabilities of hitting the target for alpha particles emitted from a source through Monte Carlo simulations, which when multiplied by the activity of the source gave the fluence at the target. The second relied on the number of chemically etched alpha-particle tracks developed on a solid-state nuclear track detector (SSNTD) that was irradiated by an alpha-particle source. The etching efficiencies (defined as percentages of latent tracks created by alpha particles from the source that could develop to become visible tracks upon chemical etching) were computed through Monte Carlo simulations, which when multiplied by the experimentally counted number of visible tracks would also give the fluence at the target. We studied alpha particles with an energy of 5.486 MeV emitted from an (241)Am source, and considered the alpha-particle tracks developed on polyallyldiglycol carbonate film, which is a common SSNTD. Our results showed that the etching efficiencies were equal to one for source-film distances of from 0.6 to 3.5 cm for a circular film of radius of 1 cm, and for source-film distances of from 1 to 3 cm for circular film of radius of 2 cm. For circular film with a radius of 3 cm, the etching efficiencies never reached 1. On the other hand, the hit probability decreased monotonically with increase in the source-target distance, and fell to zero when the source-target distance was larger than the particle range in air.

  18. Alpha particles in effective field theory

    SciTech Connect

    Caniu, C.

    2014-11-11

    Using an effective field theory for alpha (α) particles at non-relativistic energies, we calculate the strong scattering amplitude modified by Coulomb corrections for a system of two αs. For the strong interaction, we consider a momentum-dependent interaction which, in contrast to an energy dependent interaction alone [1], could be more useful in extending the theory to systems with more than two α particles. We will present preliminary results of our EFT calculations for systems with two alpha particles.

  19. Alpha-particle sensitive test SRAMs

    NASA Technical Reports Server (NTRS)

    Buehler, M. G.; Blaes, B. R.

    1990-01-01

    A bench-level test is being developed to evaluate memory-cell upsets in a test SRAM designed with a cell offset voltage. This offset voltage controls the critical charge needed to upset the cell. The effect is demonstrated using a specially designed 2-micron n-well CMOS 4-kb test SRAM and a Po-208 5.1-MeV 0.61-LET alpha-particle source. This test SRAM has been made sensitive to alpha particles through the use of a cell offset voltage, and this has allowed a bench-level characterization in a laboratory setting. The experimental data are linked to a alpha-particle interaction physics and to SPICE circuit simulations through the alpha-particle collection depth. The collection depth is determined by two methods and found to be about 7 micron. In addition, alpha particles that struck outside the bloated drain were able to flip the SRAM cells. This lateral charge collection was observed to be more than 6 micron.

  20. The status of alpha-particle diagnostics

    SciTech Connect

    Young, K.M.; Johnson, D.W.

    1992-08-01

    There is a flurry of activity to complete alpha-particle diagnostics so that they can undergo some experimental testing in DT plasmas on JET or TFTR prior to implementation on ITER. Successful measurements of escaping charged fusion products have been made in DD plasmas, and the {alpha}-particle source can be well characterized by neutron profile measurement. These methods can be extrapolated to DT plasmas. Measurement of the confined {alpha}-particles requires a new technique. Collective Thomson scattering, methods involving charge-exchange interactions and nuclear reactions with impurities will be discussed. Some assessment is given of the capabilities of these techniques, bearing in mind the potential for their use in the physics phase of the ITER program.

  1. Alternating current long range alpha particle detector

    DOEpatents

    MacArthur, Duncan W.; McAtee, James L.

    1993-01-01

    An alpha particle detector, utilizing alternating currents, whcih is capable of detecting alpha particles from distinct sources. The use of alternating currents allows use of simpler ac circuits which, in turn, are not susceptible to dc error components. It also allows the benefit of gas gain, if desired. In the invention, a voltage source creates an electric field between two conductive grids, and between the grids and a conductive enclosure. Air containing air ions created by collision with alpha particles is drawn into the enclosure and detected. In some embodiments, the air flow into the enclosure is interrupted, creating an alternating flow of ions. In another embodiment, a modulated voltage is applied to the grid, also modulating the detection of ions.

  2. Alternating current long range alpha particle detector

    DOEpatents

    MacArthur, D.W.; McAtee, J.L.

    1993-02-16

    An alpha particle detector, utilizing alternating currents, which is capable of detecting alpha particles from distinct sources. The use of alternating currents allows use of simpler ac circuits which, in turn, are not susceptible to dc error components. It also allows the benefit of gas gain, if desired. In the invention, a voltage source creates an electric field between two conductive grids, and between the grids and a conductive enclosure. Air containing air ions created by collision with alpha particles is drawn into the enclosure and detected. In some embodiments, the air flow into the enclosure is interrupted, creating an alternating flow of ions. In another embodiment, a modulated voltage is applied to the grid, also modulating the detection of ions.

  3. Beta delayed alpha emission from the neutron deficient rare earth isotopes {sup 152}Tm and {sup 150}Ho

    SciTech Connect

    Nacher, E.; Tain, J. L.; Rubio, B.; Algora, A.; Estevez Aguado, M. E.; Gadea, A.; Batist, L.; Briz, J. A.; Cano-Ott, D.; Doering, J.; Mukha, I.; Plettner, C.; Roeckl, E.; Gierlik, M.; Janas, Z.

    2011-11-30

    The study of beta-delayed proton emission is a well known method to aid the determination of the beta strength distribution in nuclei far from the stability line. At the neutron deficient side of the nuclear chart the process of proton or alpha emission from excited states is energetically allowed when one goes far enough from stability. However, beta-delayed alphas have seldom been measured for nuclei heavier than A = 20. Here we present a study of the beta-delayed alpha-particle emission from {sup 152}Tm and {sup 150}Ho and their importance in the full B(GT) distribution.

  4. Lunar surface outgassing and alpha particle measurements

    SciTech Connect

    Lawson, S. L.; Feldman, W. C.; Lawrence, David J. ,; Moore, K. R.; Elphic, R. C.; Maurice, S.; Belian, Richard D.; Binder, Alan B.

    2002-01-01

    The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particle?; produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-2 18 (6.0 MeV, 3 minute half-life), and solid polonium-210 (5.3 MeV, 138 day half-life, but held up in production by the 21 year half-life of lead-210). These three nuclides are radioactive daughters from the decay of uranium-238.

  5. Alpha particles diffusion due to charge changes

    SciTech Connect

    Clauser, C. F. Farengo, R.

    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.

  6. Michrochannel plate for position sensitive alpha particle detection

    SciTech Connect

    Paul Hurley and James Tinsley

    2007-08-31

    This paper will describe the use of a microchannel plate (MCP) as the associated particle detector on a sealed tube neutron generator. The generator produces neutrons and associated alpha particles for use as a probe to locate and identify hidden explosives in associated particle imaging (API). The MCP measures the position in two dimensions and precise timing of the incident alpha particle, information which is then used to calculate the emission time and direction of the corresponding neutron. The MCP replaces the position-sensitive photomultipler tube (PSPMT) which, until recently, had been the only detector available for measuring position and timing for alpha particles in neutron generator applications. Where the PSPMT uses charge division for generating position information, a process that requires a first order correction to each pulse, the MCP uses delay-line timing, which requires no correction. The result is a device with an order of magnitude improvement in both position resolution and timing compared to the PSPMT. Hardware and software development and the measurements made to characterize the MCP for API applications are described.

  7. Nuclear diagnostic for fast alpha particles

    DOEpatents

    Grisham, Larry R.; Post Jr., Douglass E.; Dawson, John M.

    1986-06-03

    Measurement of the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a magnetically contained plasma is provided. The fusion plasma is seeded with energetic boron neutrals for producing, by means of the reaction .sup.10 B (.alpha.,n) .sup.13 N reaction, radioactive nitrogen nuclei which are then collected by a probe. The radioactivity of the probe is then measured by conventional techniques in determining the energy distribution of the alpha particles in the plasma. In a preferred embodiment, diborane gas (B.sub.2 H.sub.6) is the source of the boron neutrals to produce .sup.13 N which decays almost exclusively by positron emission with a convenient half-life of 10 minutes.

  8. Nuclear diagnostic for fast alpha particles

    DOEpatents

    Grisham, Larry R.; Post, Jr., Douglass E.; Dawson, John M.

    1986-01-01

    Measurement of the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a magnetically contained plasma is provided. The fusion plasma is seeded with energetic boron neutrals for producing, by means of the reaction .sup.10 B (.alpha.,n) .sup.13 N reaction, radioactive nitrogen nuclei which are then collected by a probe. The radioactivity of the probe is then measured by conventional techniques in determining the energy distribution of the alpha particles in the plasma. In a preferred embodiment, diborane gas (B.sub.2 H.sub.6) is the source of the boron neutrals to produce .sup.13 N which decays almost exclusively by positron emission with a convenient half-life of 10 minutes.

  9. Evolution of the alpha particle driven toroidicity induced Alfven mode

    SciTech Connect

    Wu, Y.; White, R.B.; Cheng, C.Z.

    1994-04-01

    The interaction of alpha particles with a toroidicity induced Alfven eigenmode is investigated self-consistently by using a kinetic dispersion relation. All important poloidal harmonics and their radial mode profiles are included. A Hamiltonian guiding center code is used to simulate the alpha particle motion. The simulations include particle orbit width, nonlinear particle dynamics and the effects of the modes on the particles. Modification of the particle distribution leading to mode saturation is observed. There is no significant alpha particle loss.

  10. Alpha-irradiation-induced G2 delay: a period of cell recovery

    SciTech Connect

    Lucke-Huhle, C.

    1982-02-01

    Exponentially growing Chinese hamster V79 cells were delayed in G2 very efficiently by 3.4-MeV ..cap alpha.. particles. In comparison with the effect caused by sparsely ionizing /sup 60/Co ..gamma.. rays, G2 delay after ..cap alpha.. irradiation was greater by a factor of 6.7 and 4.2 for doses <0.5 Gy and >0.5 Gy, respectively, if the slopes of the dose-effect curves are compared. While at low doses (0.03-0.5 Gy) G2 arrest was reversible within 10 hr, increasing doses (0.5-4.38 Gy) of ..cap alpha.. irradiation blocked increasing fractions of cells for more than 16 hr, as determined by flow cytometry, and only some of these were able to complete mitosis. Addition of caffeine, however, reduced G2 arrest considerably if given directly after irradiation and reversed G2 arrest if added 8 hr after 4.38 Gy of ..cap alpha.. particles, a time when most of the cells already had accumulated in G2, caffeine treatment during G2 decreased survival after ..cap alpha.. irradiation by factors of 1.3 and 1.7 for 1 and 2 mM caffeine, respectively.

  11. Radioimmunotherapy with alpha-particle-emitting immunoconjugates

    SciTech Connect

    Macklis, R.M.; Kinsey, B.M.; Kassis, A.L.; Ferrara, J.L.M.; Atcher, R.W.; Hines, J.J.; Coleman, C.N.; Adelstein, S.J.; Burakoff, S.J.

    1988-05-20

    Alpha particles are energetic short-range ions whose higher linear energy transfer produces extreme cytotoxicity. An ..cap alpha..-particle-emitting radioimmunoconjugate consisting of a bismuth-212-labeled monoclonal immunoglobulin M specific for the murine T cell/neuroectodermal surface antigen Thy 1.2 was prepared. Analysis in vitro showed that the radioimmunoconjugate was selectively cytotoxic to a Thy 1.2/sup +/ EL-4 murine tumor cell line. Approximately three bismuth-212-labeled immunoconjugates per target cell reduced the uptake of (/sup 3/H)thymidine by the EL-4 target cells to background levels. Mice inoculated intraperitoneally with EL-4 cells were cured of their ascites after intraperitoneal injection of 150 microcuries of the antigen-specific radioimmunoconjugate, suggesting a possible role for such conjugates in intracavitary cancer therapy. 18 references, 3 figures.

  12. Diamond detector for alpha-particle spectrometry.

    PubMed

    Dueñas, J A; de la Torre Pérez, J; Martín Sánchez, A; Martel, I

    2014-08-01

    An artificially grown high purity diamond was used as a detector for alpha-particle spectrometry. Diamond detectors can match the performance of silicon detectors employed in standard continuous air monitoring systems. Its radiation hardness and electronic properties make them ideal to work under extreme condition such as high temperature and ambient lights. A 50 μm thickness single-crystal diamond detector has been compared with a 300 μm passivated implanted planar silicon detector, under ambient conditions.

  13. Lunar Surface Outgassing and Alpha Particle Measurements

    NASA Astrophysics Data System (ADS)

    Lawson, S. L.; Feldman, W. C.; Lawrence, D. J.; Moore, K. R.; Elphic, R. C.; Maurice, S.; Belian, R. D.; Binder, A. B.

    2002-01-01

    The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-218 (6.0 MeV, 3 minute half-life), and solid polonium-210 (5.3 MeV, 138 day half-life, but held up in production by the 21 year half-life of lead-210). These three nuclides are radioactive daughters from the decay of uranium-238. Radon reaches the lunar surface either at areas of high soil porosity or where fissures release the trapped gases in which radon is entrained. Once released, the radon spreads out by "bouncing" across the surface on ballistic trajectories in a randomwalk process. The half-life of radon-222 allows the gas to spread out by several 100 km before it decays (depositing approximately half of the polonium-218 recoil nuclides on the lunar surface) and allows the APS to detect gas release events up to several days after they occur. The long residence time of the lead-210 precursor to polonium-210 allows the mapping of gas vents which have been active over the last approximately 60 years. Because radon and polonium are daughter products of the decay of uranium, the background level of alpha particle activity is a function of the lunar crustal uranium distribution.

  14. Alpha particle collective Thomson scattering in TFTR

    SciTech Connect

    Machuzak, J.S.; Woskov, P.P.; Rhee, D.Y.; Gilmore, J.; Bretz, N.L.; Park, H.K.; Aamodt, R.E.; Cheung, P.Y.; Russell, D.A.; Bindslev, H.

    1993-11-01

    A collective Thomson scattering diagnostic is being implemented on TFTR to measure alpha particle, energetic and thermal ion densities and velocity distributions. A 60 GHz, 0.1-1 kW gyrotron will be used as the transmitter source, and the scattering geometry will be perpendicular to the magnetic field in the extraordinary mode polarization. An enhanced scattered signal is anticipated from fluctuations in the lower hybrid frequency range with this scattering geometry. Millimeter wave collective Thomson scattering diagnostics have the advantage of larger scattering angles to decrease the amount of stray light, and long, high power, modulated pulses to obtain improved signal to noise through synchronous detection techniques.

  15. Targeted alpha particle immunotherapy for myeloid leukemia.

    PubMed

    Jurcic, Joseph G; Larson, Steven M; Sgouros, George; McDevitt, Michael R; Finn, Ronald D; Divgi, Chaitanya R; Ballangrud, Ase M; Hamacher, Klaus A; Ma, Dangshe; Humm, John L; Brechbiel, Martin W; Molinet, Roger; Scheinberg, David A

    2002-08-15

    Unlike beta particle-emitting isotopes, alpha emitters can selectively kill individual cancer cells with a single atomic decay. HuM195, a humanized anti-CD33 monoclonal antibody, specifically targets myeloid leukemia cells and has activity against minimal disease. When labeled with the beta-emitters (131)I and (90)Y, HuM195 can eliminate large leukemic burdens in patients, but it produces prolonged myelosuppression requiring hematopoietic stem cell transplantation at high doses. To enhance the potency of native HuM195 yet avoid the nonspecific cytotoxicity of beta-emitting constructs, the alpha-emitting isotope (213)Bi was conjugated to HuM195. Eighteen patients with relapsed and refractory acute myelogenous leukemia or chronic myelomonocytic leukemia were treated with 10.36 to 37.0 MBq/kg (213)Bi-HuM195. No significant extramedullary toxicity was seen. All 17 evaluable patients developed myelosuppression, with a median time to recovery of 22 days. Nearly all the (213)Bi-HuM195 rapidly localized to and was retained in areas of leukemic involvement, including the bone marrow, liver, and spleen. Absorbed dose ratios between these sites and the whole body were 1000-fold greater than those seen with beta-emitting constructs in this antigen system and patient population. Fourteen (93%) of 15 evaluable patients had reductions in circulating blasts, and 14 (78%) of 18 patients had reductions in the percentage of bone marrow blasts. This study demonstrates the safety, feasibility, and antileukemic effects of (213)Bi-HuM195, and it is the first proof-of-concept for systemic targeted alpha particle immunotherapy in humans.

  16. Turbulent transport of alpha particles in reactor plasmas

    SciTech Connect

    Estrada-Mila, C.; Candy, J.; Waltz, R. E.

    2006-11-15

    A systematic study of the behavior of energetic ions in reactor plasmas is presented. Using self-consistent gyrokinetic simulations, in concert with an analytic asymptotic theory, it is found that alpha particles can interact significantly with core ion-temperature-gradient turbulence. Specifically, the per-particle flux of energetic alphas is comparable to the per-particle flux of thermal species (deuterium or helium ash). This finding opposes the conventional wisdom that energetic ions, because of their large gyroradii, do not interact with the turbulence. For the parameters studied, a turbulent modification of the alpha-particle density profile appears to be stronger than turbulent modification of the alpha-particle pressure profile. Crude estimates indicate that the alpha density modification, which is directly proportional to the core turbulence intensity, could be in the range of 15% at midradius in a reactor. The corresponding modification of the alpha-particle pressure profile is predicted to be smaller (in the 1% range)

  17. Alpha particle effects on the internal kink and fishbone modes

    SciTech Connect

    Wu, Y.; Cheng, C.Z.; White, R.B. )

    1994-10-01

    The effects of alpha particles on the internal kink and fishbone modes are studied analytically. The nonadiabatic contribution from untrapped alpha particles is negligible. Finite inverse aspect ratio, plasma [beta], and plasma shaping effects can significantly enhance the trapped particle drift reversal domain in the pitch angle space and reduce the bounce-averaged magnetic drift frequency. The decrease of the drift magnitude and drift reversal effects on the ideal kink mode is small, but the [beta][sub [alpha

  18. SOURCES 4A: A Code for Calculating (alpha,n), Spontaneous Fission, and Delayed Neutron Sources and Spectra

    SciTech Connect

    Madland, D.G.; Arthur, E.D.; Estes, G.P.; Stewart, J.E.; Bozoian, M.; Perry, R.T.; Parish, T.A.; Brown, T.H.; England, T.R.; Wilson, W.B.; Charlton, W.S.

    1999-09-01

    SOURCES 4A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an analysis of the contributions to that source by each nuclide in the problem.

  19. Delayed puberty from partial 17-alpha hydroxylase enzyme deficiency.

    PubMed

    Croxson, Michael; Ogilvie, C Megan; Milsom, Stella; Lewis, John; Davidson, James; Rumsby, Gill

    2012-05-25

    An 18-year-old woman with primary amenorrhoea and pubertal delay was investigated for mild labile hypertension and secondary hypogonadism. Low renin and normal aldosterone levels combined with evidence of primary adrenal insufficiency suggested partial 17-alpha hydroxylase enzyme deficiency. The diagnosis was confirmed by measurement of 24-hour urine steroid metabolites and whole gene sequencing of CYP17A1 that demonstrated c.160_162delTTC (p.Phe54del) homozygous mutation. Ultrasound showed bilateral small ovaries with multiple cysts. The serum anti-mullerian hormone concentration was unremarkable at 6.6 (normal <12.6 ng/ml) but the outlook for her future ovulatory potential is uncertain. Dexamethasone 0.25 mg pre-bed and hydrocortisone 5 mg on waking normalised her hormonal profile and her blood pressure without side-effects.

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

    SciTech Connect

    Cheng, C.Z.

    1990-10-01

    The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped {alpha}-particles through the wave-particle resonances. Satisfying the resonance condition requires that the {alpha}-particle birth speed v{sub {alpha}} {ge} v{sub A}/2{vert bar}m-nq{vert bar}, where v{sub A} 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 {alpha}-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the {alpha}-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 {alpha}-particle beta {beta}{sub {alpha}}, {alpha}-particle pressure gradient parameter ({omega}{sub {asterisk}}/{omega}{sub A}) ({omega}{sub {asterisk}} is the {alpha}-particle diamagnetic drift frequency), and (v{sub {alpha}}/v{sub A}) parameters will be presented for TFTR, CIT, and ITER tokamaks. The volume averaged {alpha}-particle beta threshold for TAE instability also depends sensitively on the core electron and ion temperature. Typically the volume averaged {alpha}-particle beta threshold is in the order of 10{sup {minus}4}. Typical growth rates of the n=1 TAE mode can be in the order of 10{sup {minus}2}{omega}{sub A}, where {omega}{sub A}=v{sub A}/qR. Other types of global Alfven waves are stable in D-T tokamaks due to toroidal coupling effects.

  1. SOURCES 4C : a code for calculating ([alpha],n), spontaneous fission, and delayed neutron sources and spectra.

    SciTech Connect

    Wilson, W. B.; Perry, R. T.; Shores, E. F.; Charlton, W. S.; Parish, Theodore A.; Estes, G. P.; Brown, T. H.; Arthur, Edward D. ,; Bozoian, Michael; England, T. R.; Madland, D. G.; Stewart, J. E.

    2002-01-01

    SOURCES 4C is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to radionuclide decay. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., an intimate mixture of a-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 44 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 107 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code provides the magnitude and spectra, if desired, of the resultant neutron source in addition to an analysis of the'contributions by each nuclide in the problem. LASTCALL, a graphical user interface, is included in the code package.

  2. Genotoxicity of alpha particles in human embryonic skin fibroblasts

    SciTech Connect

    Chen, D.J.; Strniste, G.F.; Tokita, N.

    1984-11-01

    Cell inactivation and induced mutation frequencies at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus have been measured in cultured human fibroblasts (GM10) exposed to ..cap alpha.. particles from /sup 238/ Pu and 250 kVp X rays. The survival curves resulting from exposure to ..cap alpha.. particles are exponential. The mean lethal dose, D/sub 0/, is approximately 1.3 Gy for X rays and 0.25 Gy for ..cap alpha.. particles. As a function of radiation dose, mutation induction at the HGPRT locus was linear for ..cap alpha.. particles whereas the X-ray-induced mutation data were better fitted by a quadratic function. When mutation frequencies were plotted against the log of survival, mutation frequency at a given survival level was greater in cells exposed to ..cap alpha.. particles than to X rays.

  3. [alpha]-particle transport-driven current in tokamaks

    SciTech Connect

    Heikkinen, J.A. ); Sipilae, S.K. )

    1995-03-01

    It is shown that the radial transport of fusion-born energetic [alpha] particles, induced by electrostatic waves traveling in one poloidal direction, is directly connected to a net momentum of [alpha] particles in the toroidal direction in tokamaks. Because the momentum change is almost independent of toroidal velocity, the energy required for the momentum generation remains small on an [alpha]-particle population sustained by an isotropic time-independent source. By numerical toroidal Monte Carlo calculations it is shown that the current carried by [alpha] particles in the presence of intense well penetrated waves can reach several mega-amperes in reactor-sized tokamaks. The current obtained can greatly exceed the neoclassical bootstrap current of the [alpha] particles.

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

    SciTech Connect

    Herrmann, Hans 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 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° 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.

  5. Combined effects of alpha particles and depleted uranium on Zebrafish (Danio rerio) embryos

    PubMed Central

    Ng, Candy Y.P.; Pereira, Sandrine; Cheng, Shuk Han; Adam-Guillermin, Christelle; Garnier-Laplace, Jacqueline; Yu, Kwan Ngok

    2016-01-01

    The combined effects of low-dose or high-dose alpha particles and depleted uranium (DU) in Zebrafish (Danio rerio) embryos were studied. Three schemes were examined—(i) [ILUL]: 0.44 mGy alpha-particle dose + 10 µg/l DU exposure, (ii) [IHUH]: 4.4 mGy alpha-particle dose + 100 µg/l DU exposure and (iii) [IHUL]: 4.4 mGy alpha-particle dose + 10 µg/l DU exposure—in which Zebrafish embryos were irradiated with alpha particles at 5 h post fertilization (hpf) and/or exposed to uranium at 5–6 hpf. The results were also compared with our previous work, which studied the effects of [ILUH]: 0.44 mGy alpha-particle dose + 100 µg/l DU exposure. When the Zebrafish embryos developed to 24 hpf, the apoptotic signals in the entire embryos, used as the biological endpoint for this study, were quantified. Our results showed that [ILUL] and [IHUL] led to antagonistic effects, whereas [IHUH] led to an additive effect. The effect found for the previously studied case of [ILUH] was difficult to define because it was synergistic with reference to the 100 µg/l DU exposure, but it was antagonistic with reference to the 0.44 mGy alpha-particle dose. All the findings regarding the four different schemes showed that the combined effects critically depended on the dose response to each individual stressor. We also qualitatively explained these findings in terms of promotion of early death of cells predisposed to spontaneous transformation by alpha particles, interacting with the delay in cell death resulting from various concentrations of DU exposure. PMID:26937024

  6. Alpha particle effects on the internal kink and fishbone modes

    SciTech Connect

    Wu, Y.; Cheng, C.Z.; White, R.B.

    1994-06-01

    The effects of alpha particles on the internal kink and fishbone modes are studied analytically. The nonadiabatic contribution from untrapped alpha particles is negligible. Finite inverse aspect ratio, plasma {beta} and plasma shaping effects can significantly enhance the trapped particle drift reversal domain in the pitch angle space and reduce the bounce-averaged magnetic drift frequency. The drift reversal effect on the ideal kink mode is small, but the {beta}{sub {alpha}} threshold for the fishbone mode can be much lower than previously predicted. Moreover, the fishbone mode could be excited by alpha particles even when the plasma is stable in the ideal MHD limit. In addition, the ion diamagnetic drift frequency (finite ion Larmor radius effect) has a strong destabilizing effect on the fishbone mode when it is comparable with the trapped alpha averaged precessional drift frequency, even though it stabilizes the plasma in the ideal MHD limit.

  7. SOURCES-3A: A code for calculating ({alpha}, n), spontaneous fission, and delayed neutron sources and spectra

    SciTech Connect

    Perry, R.T.; Wilson, W.B.; Charlton, W.S.

    1998-04-01

    In many systems, it is imperative to have accurate knowledge of all significant sources of neutrons due to the decay of radionuclides. These sources can include neutrons resulting from the spontaneous fission of actinides, the interaction of actinide decay {alpha}-particles in ({alpha},n) reactions with low- or medium-Z nuclides, and/or delayed neutrons from the fission products of actinides. Numerous systems exist in which these neutron sources could be important. These include, but are not limited to, clean and spent nuclear fuel (UO{sub 2}, ThO{sub 2}, MOX, etc.), enrichment plant operations (UF{sub 6}, PuF{sub 4}, etc.), waste tank studies, waste products in borosilicate glass or glass-ceramic mixtures, and weapons-grade plutonium in storage containers. SOURCES-3A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides in homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material) and in interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material). The code is also capable of calculating the neutron production rates due to ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude

  8. Contemporary Issues in Ultra-Low Alpha Particle Counting

    NASA Astrophysics Data System (ADS)

    Gordon, Michael

    Single-Event Upsets (SEU) in CMOS devices are caused by the passage of ionizing radiation either from terrestrial neutrons or from the natural alpha particle radiation within the materials surrounding the transistors. Interactions of the neutrons with the silicon cause spallation reactions which emit energetic highly ionizing elements. Alpha particles, on the other hand, can upset the devices through direct ionization rather than through a nuclear reaction as in the case of the neutrons. In order to minimize the alpha-particle component of SEU, the radiation from the materials within a distance 100 μm of the transistors, currently needs to have an alpha particle emissivity of less than 2 alpha particles per khr per square centimeter. Many alpha particle detectors have background levels that are larger than this, which can make these measurements inaccurate and time consuming. This talk will discuss what is involved in making alpha particle emissivity measurements of materials used in the semiconductor industry using an ultra-low background commercially-available ionization detector. Detector calibration and efficiency, radon adsorption on the samples, and the effect of surface charge on electrically insulating samples will be discussed.

  9. Effect of alpha particles on Toroidal Alfven Eigenmodes

    SciTech Connect

    Berk, H.L.

    1992-11-01

    An overview is given of the analytic structure for the linear theory of the Toroidal Alfven Eigenmode (TAE), where multiple gap structures occur. A discussion is given of the alpha particle drive and the various dissipation mechanisms that can stabilize the system. A self-consistent calculation of the TAE mode, for a low-beta high-aspect-ratio plasma, indicates that though the alpha particle drive is comparable to the dissipation mechanisms, overall stability is still achieved for ignited ITER-like plasma. A brief discussion is given of the nonlinear theory for the TAE mode and how nonlinear alpha particle dynamics can be treated by mapping methods.

  10. Preliminary Results from the Lunar Prospector Alpha Particle Spectrometer

    NASA Astrophysics Data System (ADS)

    Lawson, S. L.; Feldman, W. C.; Moore, K. R.; Lawrence, D. J.; Maurice, S.; Belian, R. D.; Binder, A. B.

    2001-03-01

    Data measured using the Lunar Prospector Alpha Particle Spectrometer were surveyed to search for surface deposits of polonium-210. Preliminary results show that a marginal, yet statistically-significant signal was indeed detected on the lunar front side.

  11. Alpha particle nonionizing energy loss (NIEL) for device applications

    NASA Technical Reports Server (NTRS)

    Jun, Insoo; Xapsos, Michael A.; Messenger, Scott R.; Burke, Edward A.; Walters, Robert J.; Summers, Geoff; Jordan, Thomas

    2004-01-01

    A method developed for the proton NIEL calculation previously is extended to incident alpha particles in this study: ZBL screened potential for Coulomb interactions and MCNPX 'thin target approximation' for nuclear interactions.

  12. Alpha-particle effects on ballooning flute modes in tokamaks

    SciTech Connect

    Andrushchenko, Z.N.; Bijko, A.Y.; Cheremnykh, O.K. )

    1990-11-01

    In this paper a more accurate dispersion equation for ideal ballooning flute modes in a plasma with alpha particles is obtained. It is shown that circulating and trapped alpha particles generate the eigenbranches of the mode oscillations with frequencies {omega} {approx lt} {omega}{sub *i}, where {omega}{sub *i}, is the ion drift frequency. The relevant growth rates and frequencies are found. It is ascertained that in the frequency range {omega}{sub *i} {lt} {omega} {lt} {bar {omega}{sub Db}}, where {bar {omega}{sub Db}} is the magnetic drift frequency average over a bounce period, trapped alpha particles may generate forced oscillations that influence the ideal ballooning flute mode stability boundary. It is shown that the stability may be improved for certain plasma parameters and trapped alpha-particle pressures.

  13. Measurement of alpha particle energy using windowless electret ion chambers.

    PubMed

    Dua, S K; Kotrappa, P; Srivastava, R; Ebadian, M A; Stieff, L R

    2002-10-01

    Electret ion chambers are inexpensive, lightweight, robust, commercially available, passive, charge-integrating devices for accurate measurement of different ionizing radiations. In an earlier work a chamber of dimensions larger than the range of alpha particles having aluminized Mylar windows of different thickness was used for measurement of alpha radiation. Correlation between electret mid-point voltage, alpha particle energy, and response was developed and it was shown that this chamber could be used for estimating the effective energy of an unknown alpha source. In the present study, the electret ion chamber is used in the windowless mode so that the alpha particles dissipate their entire energy inside the volume, and the alpha particle energy is determined from the first principles. This requires that alpha disintegration rate be accurately known or measured by an alternate method. The measured energies were within 1 to 4% of the true values for different sources (230Th, 237Np, 239Pu, 241Am, and 224Cm). This method finds application in quantitative determination of alpha energy absorbed in thin membrane and, hence, the absorbed dose.

  14. The promise of targeted {alpha}-particle therapy.

    PubMed

    Mulford, Deborah A; Scheinberg, David A; Jurcic, Joseph G

    2005-01-01

    The use of monoclonal antibodies to deliver radioisotopes directly to tumor cells has become a promising strategy to enhance the antitumor effects of native antibodies. Since the alpha- and beta-particles emitted during the decay of radioisotopes differ in significant ways, proper selection of isotope and antibody combinations is crucial to making radioimmunotherapy a standard therapeutic modality. Because of the short pathlength (50-80 microm) and high linear energy transfer ( approximately 100 keV/microm) of alpha-emitting radioisotopes, targeted alpha-particle therapy offers the potential for more specific tumor cell killing with less damage to surrounding normal tissues than beta-emitters. These properties make targeted alpha-particle therapy ideal for the elimination of minimal residual or micrometastatic disease. Radioimmunotherapy using alpha-emitters such as (213)Bi, (211)At, and (225)Ac has shown activity in several in vitro and in vivo experimental models. Clinical trials have demonstrated the safety, feasibility, and activity of targeted alpha-particle therapy in the treatment of small-volume and cytoreduced disease. Further advances will require investigation of more potent isotopes, new sources and methods of isotope production, improved chelation techniques, better methods for pharmacokinetic and dosimetric modeling, and new methods of isotope delivery such as pretargeting. Treatment of patients with less-advanced disease and, ultimately, randomized trials comparing targeted alpha-particle therapy with standard approaches will be required to determine the clinical utility of this approach.

  15. Shielding of manned space vehicles against protons and alpha particles

    NASA Technical Reports Server (NTRS)

    Alsmiller, R. G., Jr.; Santoro, R. T.; Barish, J.; Claiborne, H. C.

    1972-01-01

    The available information on the shielding of manned space vehicles against protons and alpha particles is summarized. The emphasis is placed on shielding against Van Allen belt protons and against solar-flare protons and alpha particles, but information on shielding against galactic cosmic rays is also presented. The approximation methods for use by nonexperts in the space shielding field are those that are standard in the space shielding literature.

  16. Alpha particle effects on the internal kink modes

    SciTech Connect

    Wu, Yanlin; Cheng, C.Z.

    1994-08-01

    The {alpha}-particle effects on the internal kink mode stability are studied. Finite Grad-Shafranov Shift, plasma {beta}, and plasma shape can significantly enhance the trapped particle drift reversal domain in pitch angle space and reduce average magnetic drift frequency. The drift reversal effect on the ideal kink mode is small, but the {beta}{sub {alpha}} threshold for the fishbone mode can be much lower than previously predicted. In addition, the ion diamagnetic drift has a stronger destabilizing effect.

  17. Actinium-225 in targeted alpha-particle therapeutic applications.

    PubMed

    Scheinberg, David A; McDevitt, Michael R

    2011-10-01

    Alpha particle-emitting isotopes are being investigated in radioimmunotherapeutic applications because of their unparalleled cytotoxicity when targeted to cancer and their relative lack of toxicity towards untargeted normal tissue. Actinium- 225 has been developed into potent targeting drug constructs and is in clinical use against acute myelogenous leukemia. The key properties of the alpha particles generated by 225Ac are the following: i) limited range in tissue of a few cell diameters; ii) high linear energy transfer leading to dense radiation damage along each alpha track; iii) a 10 day halflife; and iv) four net alpha particles emitted per decay. Targeting 225Ac-drug constructs have potential in the treatment of cancer.

  18. Alpha particle backscattering measurements used for chemical analysis of surfaces

    NASA Technical Reports Server (NTRS)

    Patterson, J. H.

    1967-01-01

    Alpha particle backscattering performs a chemical analysis of surfaces. The apparatus uses a curium source and a semiconductor detector to determine the energy spectrum of the particles. This in turn determines the chemical composition of the surface after calibration to known samples.

  19. The energetic alpha particle transport method EATM

    SciTech Connect

    Kirkpatrick, R.C.

    1998-02-01

    The EATM method is an evolving attempt to find an efficient method of treating the transport of energetic charged particles in a dynamic magnetized (MHD) plasma for which the mean free path of the particles and the Larmor radius may be long compared to the gradient lengths in the plasma. The intent is to span the range of parameter space with the efficiency and accuracy thought necessary for experimental analysis and design of magnetized fusion targets.

  20. Targeted alpha-particle immunotherapy for acute myeloid leukemia.

    PubMed

    Jurcic, Joseph G; Rosenblat, Todd L

    2014-01-01

    Because alpha-particles have a shorter range and a higher linear energy transfer (LET) compared with beta-particles, targeted alpha-particle immunotherapy offers the potential for more efficient tumor cell killing while sparing surrounding normal cells. To date, clinical studies of alpha-particle immunotherapy for acute myeloid leukemia (AML) have focused on the myeloid cell surface antigen CD33 as a target using the humanized monoclonal antibody lintuzumab. An initial phase I study demonstrated the safety, feasibility, and antileukemic effects of bismuth-213 ((213)Bi)-labeled lintuzumab. In a subsequent study, (213)Bi-lintuzumab produced remissions in some patients with AML after partial cytoreduction with cytarabine, suggesting the utility of targeted alpha-particle therapy for small-volume disease. The widespread use of (213)Bi, however, is limited by its short half-life. Therefore, a second-generation construct containing actinium-225 ((225)Ac), a radiometal that generates four alpha-particle emissions, was developed. A phase I trial demonstrated that (225)Ac-lintuzumab is safe at doses of 3 μCi/kg or less and has antileukemic activity across all dose levels studied. Fractionated-dose (225)Ac-lintuzumab in combination with low-dose cytarabine (LDAC) is now under investigation for the management of older patients with untreated AML in a multicenter trial. Preclinical studies using (213)Bi- and astatine-211 ((211)At)-labeled anti-CD45 antibodies have shown that alpha-particle immunotherapy may be useful as part conditioning before hematopoietic cell transplantation. The use of novel pretargeting strategies may further improve target-to-normal organ dose ratios.

  1. Selective flow path alpha particle detector and method of use

    DOEpatents

    Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore

    2002-01-01

    A method and apparatus for monitoring alpha contamination are provided in which ions generated in the air surrounding the item, by the passage of alpha particles, are moved to a distant detector location. The parts of the item from which ions are withdrawn can be controlled by restricting the air flow over different portions of the apparatus. In this way, detection of internal and external surfaces separately, for instance, can be provided. The apparatus and method are particularly suited for use in undertaking alpha contamination measurements during the commissioning operations.

  2. FIRE HOSE INSTABILITY DRIVEN BY ALPHA PARTICLE TEMPERATURE ANISOTROPY

    SciTech Connect

    Matteini, L.; Schwartz, S. J.; Hellinger, P.; Landi, S.

    2015-10-10

    We investigate properties of a solar wind-like plasma, including a secondary alpha particle population exhibiting a parallel temperature anisotropy with respect to the background magnetic field, using linear and quasi-linear predictions and by means of one-dimensional hybrid simulations. We show that anisotropic alpha particles can drive a parallel fire hose instability analogous to that generated by protons, but that, remarkably, can also be triggered when the parallel plasma beta of alpha particles is below unity. The wave activity generated by the alpha anisotropy affects the evolution of the more abundant protons, leading to their anisotropic heating. When both ion species have sufficient parallel anisotropies, both of them can drive the instability, and we observe the generation of two distinct peaks in the spectra of the fluctuations, with longer wavelengths associated to alphas and shorter ones to protons. If a non-zero relative drift is present, the unstable modes propagate preferentially in the direction of the drift associated with the unstable species. The generated waves scatter particles and reduce their temperature anisotropy to a marginally stable state, and, moreover, they significantly reduce the relative drift between the two ion populations. The coexistence of modes excited by both species leads to saturation of the plasma in distinct regions of the beta/anisotropy parameter space for protons and alpha particles, in good agreement with in situ solar wind observations. Our results confirm that fire hose instabilities are likely at work in the solar wind and limit the anisotropy of different ion species in the plasma.

  3. Absorbed fractions for alpha particles in ellipsoidal volumes

    NASA Astrophysics Data System (ADS)

    Amato, Ernesto; Italiano, Antonio; Baldari, Sergio

    2013-08-01

    Internal dosimetry of alpha particles is gaining attention due to the increasing applications in cancer treatment and also for the assessment of environmental contamination from radionuclides. We developed a Monte Carlo simulation in GEANT4 in order to calculate the absorbed fractions for monoenergetic alpha particles in the energy interval between 0.1 and 10 MeV, uniformly distributed in ellipsoids made of soft tissue. For each volume, we simulated a spherical shape, three oblate and three prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a ‘generalized radius’ was found; and the dependence of the fit parameters on the alpha energy is discussed and fitted by parametric functions. With the proposed formulation, the absorbed fraction for alpha particles in the energy range explored can be calculated for volumes and for ellipsoidal shapes of practical interest. This method can be applied to the evaluation of absorbed fraction from alpha-emitting radionuclides. The contribution to the deposited energy coming from electron and photon emissions can be accounted for exploiting the specific formulations previously introduced. As an example of application, the dosimetry of 213Bi and its decay chain in ellipsoids is reported.

  4. TF ripple loss of alpha particles in TFTR DT experiments

    SciTech Connect

    Redi, M.H.; Budny, R.V.; Darrow, D.S.

    1995-08-01

    Quantitative evaluation of TF ripple loss of DT alpha particles is a central issue for reactor design because of potentially severe first wall heat load problems. DT experiments on TFTR allow experimental measurements to be compared to modeling of the underlying alpha physics, with code validation an important goal. Modeling of TF ripple loss of alphas in TFTR now includes neoclassical calculations of alpha losses arising from first orbit loss, stochastic ripple diffusion, ripple trapping and collisional effects. Recent Hamiltonian coordinate guiding center code (ORBIT) simulations for TFTR have shown that collisions enhance the stochastic TF ripple losses at TFTR. A faster way to simulate experiment has been developed and is discussed here which uses a simple stochastic domain model for TF ripple loss within the TRANSP analysis code.

  5. Alpha particle radioimmunotherapy: Animal models and clinical prospects

    SciTech Connect

    Macklis, R.M.; Kaplan, W.D.; Ferrara, J.L.; Atcher, R.W.; Hines, J.J.; Burakoff, S.J.; Coleman, C.N. )

    1989-06-01

    Short-lived isotopes that emit alpha particles have a number of physical characteristics which make them attractive candidates for radioimmunotherapy. Among these characteristics are high linear energy transfer and correspondingly high cytotoxicity; particle range limited to several cell diameters from the parent atom; low potential for repair of alpha-induced DNA damage; and low dependence on dose rate and oxygen enhancement effects. This report reviews the synthesis, testing and use in animal models of an alpha particle emitting radioimmunoconjugate constructed via the noncovalent chelation of Bismuth-212 to a monoclonal IgM antibody specific for the murine T cells/neuroectodermal surface antigen, Thy 1.2. These {sup 212}Bi-anti-Thy 1.2 immunoconjugates are capable of extraordinary cytotoxicity in vitro, requiring approximately three {sup 212}Bi-labeled conjugates per target cell to suppress {sup 3}H-thymidine incorporation to background levels. The antigen specificity afforded by the monoclonal antibody contributes a factor of approximately 40 to the radiotoxicity of the immunoconjugate. Animals inoculated with a Thy 1.2+ malignant ascites were cured of their tumor in an antigen-specific fashion by intraperitoneal doses of approximately 200 microCi per mouse. Alpha particle emitting radioimmunoconjugates show great potential for regional and intracavitary molecular radiotherapy.

  6. 226Ra determination in phosphogypsum by alpha-particle spectrometry

    NASA Astrophysics Data System (ADS)

    Aguado, J. L.; Bolívar, J. P.; García-Tenorio, R.

    1999-01-01

    A radiochemical method for226Ra 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 to226Ra behaviour in phosphogypsum (the main by-product of producing phosphoric acid from phosphate rocks).

  7. Alpha particle heating at comet-solar wind interaction regions

    NASA Technical Reports Server (NTRS)

    Sharma, A. S.; Papadopoulos, K.

    1995-01-01

    The satellite observations at comet Halley have shown strong heating of solar wind alpha particles over an extended region dominated by high-intensity, low-frequency turbulence. These waves are excited by the water group pickup ions and can energize the solar wind plasma by different heating processes. The alpha particle heating by the Landau damping of kinetic Alfven waves and the transit time damping of low-frequency hydromagnetic waves in this region of high plasma beta are studied in this paper. The Alfven wave heating was shown to be the dominant mechanism for the observed proton heating, but it is found to be insufficient to account for the observed alpha particle heating. The transit time damping due to the interaction of the ions with the electric fields associated with the magnetic field compressions of magnetohydrodynamic waves is found to heat the alpha particles preferentially over the protons. Comparison of the calculated heating times for the transit time damping with the observations from comet Halley shows good agreement. These processes contribute to the thermalization of the solar wind by the conversion of its directed energy into the thermal energy in the transition region at comet-solar wind interaction.

  8. Optical and THz investigations of mid-IR materials exposed to alpha particle irradiation

    NASA Astrophysics Data System (ADS)

    Sporea, Dan; Mihai, Laura; Sporea, Adelina; Vâţã, Ion

    2017-01-01

    The paper is the first comprehensive study on alpha particle irradiation effects on four mid-IR materials: CaF2, BaF2, Al2O3 (sapphire) and ZnSe. The measurements of the optical spectral transmittance, spectral diffuse reflectance, radioluminescent emission, terahertz (THz) spectral response, transmittance, absorbance, refractive index, real and imaginary parts of the dielectric constant and THz imaging are used as complementary investigations to evaluate these effects. The simulations were run to estimate: (i) the penetration depth, (ii) the scattering of alpha particle beam, (iii) the amount of material affected by this interaction, and (iv) the number of vacancies produced by the radiation exposure for each type of material. The simulation results are compared to the off-line measurement outcomes. The delay and spectral composition change of the reflected THz signal highlight the modification induced in the tested materials by the irradiation process.

  9. Optical and THz investigations of mid-IR materials exposed to alpha particle irradiation

    PubMed Central

    Sporea, Dan; Mihai, Laura; Sporea, Adelina; Vâţã, Ion

    2017-01-01

    The paper is the first comprehensive study on alpha particle irradiation effects on four mid-IR materials: CaF2, BaF2, Al2O3 (sapphire) and ZnSe. The measurements of the optical spectral transmittance, spectral diffuse reflectance, radioluminescent emission, terahertz (THz) spectral response, transmittance, absorbance, refractive index, real and imaginary parts of the dielectric constant and THz imaging are used as complementary investigations to evaluate these effects. The simulations were run to estimate: (i) the penetration depth, (ii) the scattering of alpha particle beam, (iii) the amount of material affected by this interaction, and (iv) the number of vacancies produced by the radiation exposure for each type of material. The simulation results are compared to the off-line measurement outcomes. The delay and spectral composition change of the reflected THz signal highlight the modification induced in the tested materials by the irradiation process. PMID:28067289

  10. Bacteria Delay the Jamming of Particles at Microchannel Bottlenecks

    NASA Astrophysics Data System (ADS)

    Sendekie, Zenamarkos Bantie; Gaveau, Arthur; Lammertink, Rob G. H.; Bacchin, Patrice

    2016-08-01

    Clogging of channels by complex systems such as mixtures of colloidal and biological particles is commonly encountered in different applications. In this work, we analyze and compare the clogging mechanisms and dynamics by pure and mixture suspensions of polystyrene latex particles and Escherichia coli by coupling fluorescent microscopic observation and dynamic permeability measurements in microfluidic filters. Pure particles filtration leads to arches and deposit formation in the upstream side of the microfilter while pure bacteria form streamers in the downstream zone. When mixing particle and bacteria, an unexpected phenomenon occurs: the clogging dynamics is significantly delayed. This phenomenon is related to apparent “slippery” interactions between the particles and the bacteria. These interactions limit the arches formation at the channels entrances and favour the formation of dendritic structures on the pillars between the channels. When these dendrites are eroded by the flow, fragments of the deposit are dragged towards the channels entrances. However, these bacteria/particles clusters being lubricated by the slippery interactions are deformed and stretched by the shear thus facilitating their passage through the microchannels.

  11. Bacteria Delay the Jamming of Particles at Microchannel Bottlenecks

    PubMed Central

    Sendekie, Zenamarkos Bantie; Gaveau, Arthur; Lammertink, Rob G. H.; Bacchin, Patrice

    2016-01-01

    Clogging of channels by complex systems such as mixtures of colloidal and biological particles is commonly encountered in different applications. In this work, we analyze and compare the clogging mechanisms and dynamics by pure and mixture suspensions of polystyrene latex particles and Escherichia coli by coupling fluorescent microscopic observation and dynamic permeability measurements in microfluidic filters. Pure particles filtration leads to arches and deposit formation in the upstream side of the microfilter while pure bacteria form streamers in the downstream zone. When mixing particle and bacteria, an unexpected phenomenon occurs: the clogging dynamics is significantly delayed. This phenomenon is related to apparent “slippery” interactions between the particles and the bacteria. These interactions limit the arches formation at the channels entrances and favour the formation of dendritic structures on the pillars between the channels. When these dendrites are eroded by the flow, fragments of the deposit are dragged towards the channels entrances. However, these bacteria/particles clusters being lubricated by the slippery interactions are deformed and stretched by the shear thus facilitating their passage through the microchannels. PMID:27510611

  12. Production of medical Sc radioisotopes with an alpha particle beam.

    PubMed

    Szkliniarz, Katarzyna; Sitarz, Mateusz; Walczak, Rafał; Jastrzębski, Jerzy; Bilewicz, Aleksander; Choiński, Jarosław; Jakubowski, Andrzej; Majkowska, Agnieszka; Stolarz, Anna; Trzcińska, Agnieszka; Zipper, Wiktor

    2016-12-01

    The internal α-particle beam of the Warsaw Heavy Ion Cyclotron was used to produce research quantities of the medically interesting Sc radioisotopes from natural Ca and K and isotopically enriched (42)Ca targets. The targets were made of metallic calcium, calcium carbonate and potassium chloride. New data on the production yields and impurities generated during the target irradiations are presented for the positron emitters (43)Sc, (44g)Sc and (44m)Sc. The different paths for the production of the long lived (44m)Sc/(44g)Sc in vivo generator, proposed by the ARRONAX team, using proton and deuteron beams as well as alpha-particle beams are discussed. Due to the larger angular momentum transfer in the formation of the compound nucleus in the case of the alpha particle induced reactions, the isomeric ratio of (44m)Sc/(44g)Sc at a bombarding energy of 29MeV is five times larger than previously determined for a deuteron beam and twenty times larger than for proton induced reactions on enriched CaCO3 targets. Therefore, formation of this generator via the alpha-particle route seems a very attractive way to form these isotopes. The experimental data presented here are compared with theoretical predictions made using the EMPIRE evaporation code. Reasonable agreement is generally observed.

  13. Targeting Prostate Cancer Stem Cells with Alpha-Particle Therapy.

    PubMed

    Ceder, Jens; Elgqvist, Jörgen

    2016-01-01

    Modern molecular and radiopharmaceutical development has brought the promise of tumor-selective delivery of antibody-drug conjugates to tumor cells for the diagnosis and treatment of primary and disseminated tumor disease. The classical mode of discourse regarding targeted therapy has been that the antigen targeted must be highly and homogenously expressed in the tumor cell population, and at the same time exhibit low expression in healthy tissue. However, there is increasing evidence that the reason cancer patients are not cured by current protocols is that there exist subpopulations of cancer cells that are resistant to conventional therapy including radioresistance and that these cells express other target antigens than the bulk of the tumor cells. These types of cells are often referred to as cancer stem cells (CSCs). The CSCs are tumorigenic and have the ability to give rise to all types of cells found in a cancerous disease through the processes of self-renewal and differentiation. If the CSCs are not eradicated, the cancer is likely to recur after therapy. Due to some of the characteristics of alpha particles, such as short path length and high density of energy depositions per distance traveled in tissue, they are especially well suited for use in targeted therapies against microscopic cancerous disease. The characteristics of alpha particles further make it possible to minimize the irradiation of non-targeted surrounding healthy tissue, but most importantly, make it possible to deliver high-absorbed doses locally and therefore eradicating small tumor cell clusters on the submillimeter level, or even single tumor cells. When alpha particles pass through a cell, they cause severe damage to the cell membrane, cytoplasm, and nucleus, including double-strand breaks of DNA that are very difficult to repair for the cell. This means that very few hits to a cell by alpha particles are needed in order to cause cell death, enabling killing of cells, such as CSCs

  14. Targeting Prostate Cancer Stem Cells with Alpha-Particle Therapy

    PubMed Central

    Ceder, Jens; Elgqvist, Jörgen

    2017-01-01

    Modern molecular and radiopharmaceutical development has brought the promise of tumor-selective delivery of antibody–drug conjugates to tumor cells for the diagnosis and treatment of primary and disseminated tumor disease. The classical mode of discourse regarding targeted therapy has been that the antigen targeted must be highly and homogenously expressed in the tumor cell population, and at the same time exhibit low expression in healthy tissue. However, there is increasing evidence that the reason cancer patients are not cured by current protocols is that there exist subpopulations of cancer cells that are resistant to conventional therapy including radioresistance and that these cells express other target antigens than the bulk of the tumor cells. These types of cells are often referred to as cancer stem cells (CSCs). The CSCs are tumorigenic and have the ability to give rise to all types of cells found in a cancerous disease through the processes of self-renewal and differentiation. If the CSCs are not eradicated, the cancer is likely to recur after therapy. Due to some of the characteristics of alpha particles, such as short path length and high density of energy depositions per distance traveled in tissue, they are especially well suited for use in targeted therapies against microscopic cancerous disease. The characteristics of alpha particles further make it possible to minimize the irradiation of non-targeted surrounding healthy tissue, but most importantly, make it possible to deliver high-absorbed doses locally and therefore eradicating small tumor cell clusters on the submillimeter level, or even single tumor cells. When alpha particles pass through a cell, they cause severe damage to the cell membrane, cytoplasm, and nucleus, including double-strand breaks of DNA that are very difficult to repair for the cell. This means that very few hits to a cell by alpha particles are needed in order to cause cell death, enabling killing of cells, such as CSCs

  15. Quality factors for alpha particles emitted in tissue

    NASA Technical Reports Server (NTRS)

    Borak, Thomas B.; Chatterjee, A. (Principal Investigator)

    2002-01-01

    A concept of a mean or dose averaged quality factor was defined in ICRP Publication 26 using relationships for quality factor as a function of LET. The concept of radiation weighting factors, wR, was introduced in ICRP Publication 60 in 1990. These are meant to be generalized factors that modify absorbed dose to reflect the risk of stochastic effects as a function of the quality of the radiation incident on the body or emitted by radioactivity within the body. The values of wr are equal to 20 for all alpha particles externally or internally emitted. This note compares the dose averaged quality factor for alpha particles originating in tissue using the old and revised recommendations for quality factor as a function of LET. The dose averaged quality factor never exceeds 20 using the old recommendations and is never less than 20 with the revised recommendations.

  16. Fission studies with 140 MeV {alpha} particles

    SciTech Connect

    Buttkewitz, A.; Duhm, H. H.; Strauss, W.; Goldenbaum, F.; Machner, H.

    2009-09-15

    Binary fission induced by 140 MeV {alpha} particles has been measured for {sup nat}Ag, {sup 139}La, {sup 165}Ho, and {sup 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{sup 2}/A=24 is observed.

  17. {alpha} particle preformation in heavy nuclei and penetration probability

    SciTech Connect

    Zhang, H. F.; Royer, G.

    2008-05-15

    The {alpha} particle preformation in the even-even nuclei from {sup 108}Te to {sup 294}118 and the penetration probability have been studied. The isotopes from Pb to U have been firstly investigated since the experimental data allow us to extract the microscopic features for each element. The assault frequency has been estimated using classical methods and the penetration probability from tunneling through the Generalized Liquid Drop Model (GLDM) potential barrier. The preformation factor has been extracted from experimental {alpha} decay energies and half-lives. The shell closure effects play the key role in the {alpha} preformation. The more the nucleon number is close to the magic numbers, the more the formation of {alpha} cluster is difficult inside the mother nucleus. The penetration probabilities reflect that 126 is a neutron magic number. The penetration probability range is very large compared to that of the preformation factor. The penetration probability determines mainly the {alpha} decay half-life while the preformation factor allows us to obtain information on the nuclear structure. The study has been extended to the newly observed heaviest nuclei.

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

    ERIC Educational Resources Information Center

    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…

  19. An alpha particle instrument with alpha, proton, and X-ray modes for planetary chemical analyses

    NASA Technical Reports Server (NTRS)

    Economou, T. E.; Turkevich, A. L.

    1976-01-01

    The interaction of alpha particles with matter is employed in a compact instrument that could provide rather complete in-situ chemical analyses of surfaces and thin atmospheres of extraterrestrial bodies. The instrument is a miniaturized and improved version of the Surveyor lunar instrument. The backscattering of alpha particles and (alpha, p) reactions provide analytical data on the light elements (carbon-iron). An X-ray mode that detects the photons produced by the alpha sources provides sensitivity and resolution for the chemical elements heavier than about silicon. The X-rays are detected by semiconductor detectors having a resolution between 150 and 250 eV at 5.9 keV. Such an instrument can identify and determine with good accuracy 99 percent of the atoms (except hydrogen) in rocks. For many trace elements, the detecting sensitivity is a few ppm. Auxiliary sources could be used to enhance the sensitivities for elements of special interest. The instrument could probably withstand the acceleration involved in semi-hard landings.

  20. Alpha particle spectra and microdosimetry of radon daughters

    SciTech Connect

    Caswell, R.S.; Coyne, J.J.

    1992-12-31

    We are interested in understanding the physics of the process by which radon-daughter alpha particles irradiate cells, leading to the induction of cancer. We are focusing initially on two aspects: the alpha spectra incident upon cells, which are needed for input to biophysical models of cancer induction; and microdosimetric spectra and parameters which give information on radiation quality. Adapting an analytical method previously developed for neutron radiation, we have calculated the alpha-particle slowing-down spectra (the spectra incident upon cells) and, subsequently, the microdosimetric spectra and parameters for various cell nuclei or site diameters. Results will be presented from three modes of program operation. MODE 1 is for the thin, plane source of radon-daughter activity adjacent to the epithelium. MODE 2 is for the thick source layer (the mucous-serous layer) adjacent to the epithelium. MODE4 is for cylindrical airways of various radii, lined by the mucous-serous layer. MODE 1 is most useful for understanding the problem; MODE 4 is most anatomically relevant. MODE 3 is not discussed in this paper. Alpha-particle spectra and microdosimetric spectra and parameters are studied as a function of cell depth, {sup 218}Po/{sup 214}Po ratio, airway radius, and cell nucleus or the site size. Also available from the calculation is mean dose as a function of depth below the airway surface. The results described here are available on personal computer diskettes. We are beginning to compare our studies with the calculations of other workers and plan to extend the calculations to the nanometer target level.

  1. Effect of alpha particles on the shock structure

    NASA Astrophysics Data System (ADS)

    Gedalin, Michael

    2017-01-01

    The magnetic profile of a collisionless shock is shaped by ions. Dynamics of the ions is governed by the fields in the shock front. Species with different charge-to-mass ratio have different gyroradii; thus, their distributions upon crossing the shock became substantially different. Accordingly, the dependencies of the density and temperature on the coordinate along the shock normal should differ. In a stable one-dimensional stationary shock the total pressure must remain constant throughout. Therefore, the magnetic pressure should anticorrelate with the particle pressure. Since the particle pressure is not uniform, downstream spatial magnetic oscillations should arise. Each of the species results in its own dependence of the pressure on the coordinate along the shock normal; therefore, the oscillations are not spatially periodic. The magnetic compression in the shocks with alpha particles is higher than the magnetic compression in purely proton shocks, while the amplitude of the downstream magnetic oscillations is lower.

  2. Alpha-particle Measurements Needed for Burning Plasma Experiments

    SciTech Connect

    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.

  3. Cytotoxicity of alpha-particle-emitting astatine-211-labelled antibody in tumour spheroids: no effect of hyperthermia.

    PubMed

    Hauck, M L; Larsen, R H; Welsh, P C; Zalutsky, M R

    1998-03-01

    The high linear energy transfer, alpha-particle-emitting radionuclide astatine-211 (211At) is of interest for certain therapeutic applications; however, because of the 55- to 70-microm path length of its alpha-particles, achieving homogeneous tracer distribution is critical. Hyperthermia may enhance the therapeutic efficacy of alpha-particle endoradiotherapy if it can improve tracer distribution. In this study, we have investigated whether hyperthermia increased the cytotoxicity of an 211At-labelled monoclonal antibody (MAb) in tumour spheroids with a radius (approximately 100 microm) greater than the range of 211At alpha-particles. Hyperthermia for 1 h at 42 degrees C was used because this treatment itself resulted in no regrowth delay. Radiolabelled chimeric MAb 81C6 reactive with the extracellular matrix antigen tenascin was added to spheroids grown from the D-247 MG human glioma cell line at activity concentrations ranging from 0.125 to 250 kBq ml(-1). A significant regrowth delay was observed at 125 and 250 kBq ml(-1) in both hyperthermia-treated and untreated spheroids. For groups receiving hyperthermia, no increase in cytotoxicity was seen compared with normothermic controls at any activity concentration. These results and those from autoradiographs indicate that hyperthermia at 42 degrees C for 1 h had no significant effect on the uptake or distribution of this antitenascin MAb in D-247 MG spheroids.

  4. Cytotoxicity of alpha-particle-emitting astatine-211-labelled antibody in tumour spheroids: no effect of hyperthermia.

    PubMed Central

    Hauck, M. L.; Larsen, R. H.; Welsh, P. C.; Zalutsky, M. R.

    1998-01-01

    The high linear energy transfer, alpha-particle-emitting radionuclide astatine-211 (211At) is of interest for certain therapeutic applications; however, because of the 55- to 70-microm path length of its alpha-particles, achieving homogeneous tracer distribution is critical. Hyperthermia may enhance the therapeutic efficacy of alpha-particle endoradiotherapy if it can improve tracer distribution. In this study, we have investigated whether hyperthermia increased the cytotoxicity of an 211At-labelled monoclonal antibody (MAb) in tumour spheroids with a radius (approximately 100 microm) greater than the range of 211At alpha-particles. Hyperthermia for 1 h at 42 degrees C was used because this treatment itself resulted in no regrowth delay. Radiolabelled chimeric MAb 81C6 reactive with the extracellular matrix antigen tenascin was added to spheroids grown from the D-247 MG human glioma cell line at activity concentrations ranging from 0.125 to 250 kBq ml(-1). A significant regrowth delay was observed at 125 and 250 kBq ml(-1) in both hyperthermia-treated and untreated spheroids. For groups receiving hyperthermia, no increase in cytotoxicity was seen compared with normothermic controls at any activity concentration. These results and those from autoradiographs indicate that hyperthermia at 42 degrees C for 1 h had no significant effect on the uptake or distribution of this antitenascin MAb in D-247 MG spheroids. Images Figure 4 Figure 5 PMID:9514054

  5. Alpha-particle activity of apollo 11 samples.

    PubMed

    Richardson, K A; McCkay, D S; Greenwood, W R; Foss, T H

    1970-01-30

    Nine polishled thin sectionis have been exposed to nulclear track plates, three have been counted by alplia-particle spectrometry, and one has been examined by electron mocroprobe. Interpretation of the results is in a preliminary stage. Alpha track distribiutioni in the autoradiograph of a breccia forms a network that appears related to the rims of accretionary lapilli comiiposinig the breccia. Thorium in a coarse-grained crystalline rock is concenitrated in micron-sized, zirconium-rich crystals. Alplia count rates agree with what would be predicted from previously reported thorium and uranium contents of the same rocks, suggesting secular equilibriunm for the thorium and uranium decay series.

  6. Protons and alpha particles in the solar wind

    NASA Astrophysics Data System (ADS)

    Hellinger, Petr; Travnicek, Pavel M.; Passot, Thierry; Sulem, Pierre-Louis; Matteini, Lorenzo; Landi, Simone

    2014-05-01

    We investigate energetic consequences of ion kinetic instabilitities in the solar wind connected with beam and core protons and alpha particles drifting with respect to each other. We compare theoretical predictions, simulations and observation results. For theoretical prediction we assume drifting bi-Maxwellian ion populations and we calculate theoretical quasilinear heating rates (Hellinger et al., 2013b). The nonlinear evolution of beam-core protons, and alpha particles in the expanding solar wind we investigate using hybrid expanding box system (Hellinger and Travnicek, 2013). The expansion leads to many different kinetic instabilities. In the simulation the beam protons and alpha particles are decelerated with respect to the core protons and all the populations are cooled in the parallel direction and heated in the perpendicular one in agreement with theoretical expectations. On the macroscopic level the kinetic instabilities cause large departures of the system evolution from the double adiabatic prediction and lead to a perpendicular heating and parallel cooling rates. The simulated heating rates are comparable to the heating rates estimated from the Helios observations (Hellinger et al., 2013a); furthermore, the differential velocity between core and beam protons observed by Ulysses exhibits apparent bounds which are compatible with the theoretical constaints imposed by the linear theory for the magnetosonic instability driven by beam-core differential velocity (Matteini et al., 2013). References Hellinger, P., P. M. Travnicek, S. Stverak, L. Matteini, and M. Velli (2013a), Proton thermal energetics in the solar wind: Helios reloaded, J. Geophys. Res., 118, 1351-1365, doi:10.1002/jgra.50107. Hellinger, P., T. Passot, P.-L. Sulem, and P. M. Travnicek (2013b), Quasi-linear heating and acceleration in bi-Maxwellian plasmas, Phys. Plasmas, 20, 122306. Hellinger, P., and P. M. Travnicek (2013), Protons and alpha particles in the expanding solar wind: Hybrid

  7. Direct high-resolution alpha spectrometry from nuclear fuel particles in an outdoor air sample.

    PubMed

    Pöllänen, R; Siiskonen, T

    2008-01-01

    The potential use of direct high-resolution alpha spectrometry to identify the presence of transactinium elements in air samples is illustrated in the case when alpha-particle-emitting radionuclides are incorporated in nuclear fuel particles. Alpha particle energy spectra are generated through Monte Carlo simulations assuming a nuclide composition similar to RBMK (Chernobyl) nuclear fuel. The major alpha-particle-emitting radionuclides, in terms of activity, are 242Cm, 239Pu and 240Pu. The characteristics of the alpha peaks are determined by fuel particle properties as well as the type of the air filter. It is shown that direct alpha spectrometry can be readily applied to membrane filter samples containing nuclear fuel particles when rapid nuclide identification is of relevance. However, the development of a novel spectrum analysis code is a prerequisite for unfolding complex alpha spectra.

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

    SciTech Connect

    Al-Ta'ii, Hassan Maktuff Jaber E-mail: vengadeshp@um.edu.my; Periasamy, Vengadesh E-mail: vengadeshp@um.edu.my; Amin, Yusoff Mohd

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Preliminary results from the lunar prospector alpha particle spectrometer

    SciTech Connect

    Lawson, S. L.

    2001-01-01

    The Lunar Prospector Alpha Particle Spectrometer (LP APS) builds on Apollo heritage and maps the distribution of outgassing sites on the Moon. The APS searches for lunar surface gas release events and maps their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life) and solid polonium-210 (5.3 MeV, 138 day half-life, but remains on the surface with a 21 year half-life as lead-210), which are radioactive daughters from the decay of uranium-238. Radon is in such small quantities that it is not released directly from the lunar interior, rather it is entrained in a stream of gases and serves as a tracer for such gases. Once released, the radon spreads out by 'bouncing' across the surface on ballistic trajectories in a random-walk process. The 3.8 day half-life of radon-222 allows the gas to spread out by several 100 km before it decays and allows the APS to detect gas release events up to a few days after they occur. The long residence time (10s of years) of the lead-210 precursor to the polonium-210 allows the mapping of gas vents which have been active over the last approximately 50 years. Because radon and polonium are daughter products of the decay of uranium, the background level of alpha particle activity is a function of the lunar crustal uranium distribution. Using radioactive radon and polonium as tracers, the Apollo 15 and 16 Command Module orbital alpha particle experiments obtained evidence for the release of gases at several sites beneath the orbit tracks, especially over the Aristarchus Plateau and Mare Fecunditatis [1]. Aristarchus crater had previously been identified by ground-based observers as the site of transient optical events [2]. The Apollo 17 surface mass spectrometer showed that argon-40 is released from the lunar interior every few months, apparently in concert with some of the shallow moonquakes that are believed to be of tectonic origin [3]. The latter tectonic events could be

  11. Sawtooth mixing of alpha particles in TFTR D-T plasmas

    SciTech Connect

    Petrov, M.P.; Budny, R.V.; Chang, Z.

    1996-12-31

    Radially resolved confined alpha particle energy and density distributions are routinely measured on TFTR using two diagnostics: PCX and {alpha}-CHERS. The Pellet Charge-eXchange (PCX) diagnostic uses the ablation cloud formed by an impurity pellet (Li or B) for neutralization of the alphas followed by analysis of the escaping helium neutrals. PCX detects deeply trapped alpha particles in the energy range 0.5 - 3.8 MeV. The {alpha}-CHERS technique, were the alpha signal is excited by charge-exchange between alphas and the deuterium atoms of one of the heating beams and appears as a wing on the He{sup +} 468.6 nm line, detects mainly passing alphas in the range of 0.15 - 0.7 MeV. Studies of alpha losses during DT experiments on TFTR have also been conducted using lost alpha detectors located on the walls of the plasma chamber. All of these diagnostics were used for investigating the influence of sawtooth crashes on alphas in high power D-T discharges in TFTR. Both PCX and {alpha}-CHERS measurements show a strong depletion of the alpha core density and transport of trapped alphas radially outwards well beyond q = 1 surface after a sawtooth crash. Lost alpha detectors measure bursts of alpha loss of the previously confined alphas (<1%). Thus, a sawtooth crash leads mainly to radial redistribution of the alphas rather than losses. For modeling of alpha sawtooth mixing, a code is used which is based on the conventional model of magnetic reconnection and the conservation of particles, energy and magnetic flux. The effect of the particle orbit averaged toroidal drift in a perturbed helical electric field generated by the crash has also been included in the code. It is shown that mixing of the passing alphas is dominated by the magnetic reconnection whereas trapped alphas are affected mainly by ExB drift.

  12. INSTABILITIES DRIVEN BY THE DRIFT AND TEMPERATURE ANISOTROPY OF ALPHA PARTICLES IN THE SOLAR WIND

    SciTech Connect

    Verscharen, Daniel; Bourouaine, Sofiane; Chandran, Benjamin D. G. E-mail: s.bourouaine@unh.edu

    2013-08-20

    We investigate the conditions under which parallel-propagating Alfven/ion-cyclotron (A/IC) waves and fast-magnetosonic/whistler (FM/W) waves are driven unstable by the differential flow and temperature anisotropy of alpha particles in the solar wind. We focus on the limit in which w{sub Parallel-To {alpha}} {approx}> 0.25v{sub A}, where w{sub Parallel-To {alpha}} is the parallel alpha-particle thermal speed and v{sub A} is the Alfven speed. We derive analytic expressions for the instability thresholds of these waves, which show, e.g., how the minimum unstable alpha-particle beam speed depends upon w{sub Parallel-To {alpha}}/v{sub A}, the degree of alpha-particle temperature anisotropy, and the alpha-to-proton temperature ratio. We validate our analytical results using numerical solutions to the full hot-plasma dispersion relation. Consistent with previous work, we find that temperature anisotropy allows A/IC waves and FM/W waves to become unstable at significantly lower values of the alpha-particle beam speed U{sub {alpha}} than in the isotropic-temperature case. Likewise, differential flow lowers the minimum temperature anisotropy needed to excite A/IC or FM/W waves relative to the case in which U{sub {alpha}} = 0. We discuss the relevance of our results to alpha particles in the solar wind near 1 AU.

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

    SciTech Connect

    Darrow, D.S.; Zweben, S.J.; Batha, S.

    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.

  14. Enhanced production of low energy electrons by alpha particle impact.

    PubMed

    Kim, Hong-Keun; Titze, Jasmin; Schöffler, Markus; Trinter, Florian; Waitz, Markus; Voigtsberger, Jörg; Sann, Hendrik; Meckel, Moritz; Stuck, Christian; Lenz, Ute; Odenweller, Matthias; Neumann, Nadine; Schössler, Sven; Ullmann-Pfleger, Klaus; Ulrich, Birte; Fraga, Rui Costa; Petridis, Nikos; Metz, Daniel; Jung, Annika; Grisenti, Robert; Czasch, Achim; Jagutzki, Ottmar; Schmidt, Lothar; Jahnke, Till; Schmidt-Böcking, Horst; Dörner, Reinhard

    2011-07-19

    Radiation damage to living tissue stems not only from primary ionizing particles but to a substantial fraction from the dissociative attachment of secondary electrons with energies below the ionization threshold. We show that the emission yield of those low energy electrons increases dramatically in ion-atom collisions depending on whether or not the target atoms are isolated or embedded in an environment. Only when the atom that has been ionized and excited by the primary particle impact is in immediate proximity of another atom is a fragmentation route known as interatomic Coulombic decay (ICD) enabled. This leads to the emission of a low energy electron. Over the past decade ICD was explored in several experiments following photoionization. Most recent results show its observation even in water clusters. Here we show the quantitative role of ICD for the production of low energy electrons by ion impact, thus approaching a scenario closer to that of radiation damage by alpha particles: We choose ion energies on the maximum of the Bragg peak where energy is most efficiently deposited in tissue. We compare the electron production after colliding He(+) ions on isolated Ne atoms and on Ne dimers (Ne(2)). In the latter case the Ne atom impacted is surrounded by a most simple environment already opening ICD as a deexcitation channel. As a consequence, we find a dramatically enhanced low energy electron yield. The results suggest that ICD may have a significant influence on cell survival after exposure to ionizing radiation.

  15. A self-consistent theory of collective alpha particle losses induced by Alfvenic turbulence

    SciTech Connect

    Biglari, H. . Plasma Physics Lab.); Diamond, P.H. . Dept. of Physics)

    1992-01-01

    The nonlinear dynamics of kinetic Alfven waves, resonantly excited by energetic ions/alpha particles, is investigated. It is shown that {alpha}-particles govern both linear instability and nonlinear saturation dynamics, while the background MHD turbulence results only in a nonlinear real frequency shift. The most efficient saturation mechanism is found to be self-induced profile modification. Expressions for the fluctuation amplitudes and the {alpha}-particle radial flux are self-consistently derived. The work represents the first self-consistent, turbulent treatment of collective {alpha}-particle losses by Alfvenic fluctuations.

  16. Self-consistent study of the alpha particle driven TAE mode

    SciTech Connect

    Wu, Y.; White, R.B.

    1994-04-01

    The interaction of high energy particles with an Alfven eigenmode is investigated self-consistently by using a realistic kinetic dispersion relation. All important poloidal mode numbers and their radial mode profiles as calculated with the NOVA-K code are included. A Hamiltonian guiding center code is used to simulate the alpha particle motion. The numerical simulations include particle orbit width, nonlinear particle dynamics and the effects of the modes on the particles. Modification of the particle distribution leading to mode saturation is observed. Particle loss is limited to devices in which the alpha particle gyro radius is a significant fraction of the minor radius.

  17. The Delay of Low-energy Particle Populations in Association with Large Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Al-Dayeh, M.; Desai, M. I.; Dwyer, J. R.; Rassoul, H. K.; Mason, G.; Mazur, J.

    2008-05-01

    Using ~0.045-10 MeV/nucleon ion data from ACE/ULEIS, we have found that a substantial number of shock- associated solar energetic particle events (~20 events) have significant delays in the arrival of the low- energy component beyond what is expected from the travel time of energetic particles from the sun to the earth at 1 AU. Indeed, for some events, after correcting for the velocity dispersion, the low energy component (~sub- MeV/nucleon) is almost completely absent while the high-energy component (E > 1 MeV/nucleon) has very large enhancements. SEP events with the most dramatic initial depletion of low-energy particles are accompanied by large proton fluxes and have large enhancements of the low-energy particles later, in coincidence with the arrival of the interplanetary shock, a day or two after the start of the event. In addition, these events show Fe/O enhancements during the periods in which the low-energy component is depleted and lower Fe/O values once the shock arrives. These new observations appear to be explained by the trapping of particles with low energy-to-charge (E/Q) ratios in the vicinity of the shock by magnetohydrodynamic waves, possibly generated by high energy protons streaming along the magnetic field lines.

  18. Development of an optical lens based alpha-particle imaging system using position sensitive photomultiplier tube

    NASA Astrophysics Data System (ADS)

    Ando, Koki; Oka, Miki; Yamamoto, Seiichi

    2017-02-01

    We developed an optical lens based alpha-particle imaging system using position sensitive photomultiplier tube (PSPMT). The alpha-particle imaging system consists of an optical lens, an extension tube and a 1 in. square high quantum efficiency (HQE) type PSPMT. After a ZnS(Ag) is attached to subject, the scintillation image of ZnS(Ag) is focused on the photocathode of the PSPMT by the use of the optical lens. With this configuration we could image the alpha particle distribution with energy information without contacting to the subject. The spatial resolution and energy resolution were 0.8 mm FWHM and 50% FWHM at 5 mm from the optical lens, respectively. We could successfully image the alpha particle distribution in uranium ore. The developed alpha-particle imaging system will be a new tool for imaging alpha emitters with energy information without contacting the subject.

  19. Realizing the potential of the Actinium-225 radionuclide generator in targeted alpha-particle therapy applications

    PubMed Central

    Miederer, Matthias; Scheinberg, David A.; McDevitt, Michael R.

    2013-01-01

    Alpha particle-emitting isotopes have been proposed as novel cytotoxic agents for augmenting targeted therapy. Properties of alpha particle radiation such as their limited range in tissue of a few cell diameters and their high linear energy transfer leading to dense radiation damage along each alpha track are promising in the treatment of cancer, especially when single cells or clusters of tumor cells are targeted. Actinium-225 (225Ac) is an alpha particle-emitting radionuclide that generates 4 net alpha particle isotopes in a short decay chain to stable 209Bi, and as such can be described as an alpha particle nanogenerator. This article reviews the literature pertaining to the research, development, and utilization of targeted 225Ac to potently and specifically affect cancer. PMID:18514364

  20. Realizing the potential of the Actinium-225 radionuclide generator in targeted alpha particle therapy applications.

    PubMed

    Miederer, Matthias; Scheinberg, David A; McDevitt, Michael R

    2008-09-01

    Alpha particle-emitting isotopes have been proposed as novel cytotoxic agents for augmenting targeted therapy. Properties of alpha particle radiation such as their limited range in tissue of a few cell diameters and their high linear energy transfer leading to dense radiation damage along each alpha track are promising in the treatment of cancer, especially when single cells or clusters of tumor cells are targeted. Actinium-225 (225 Ac) is an alpha particle-emitting radionuclide that generates 4 net alpha particle isotopes in a short decay chain to stable 209 Bi, and as such can be described as an alpha particle nanogenerator. This article reviews the literature pertaining to the research, development, and utilization of targeted 225 Ac to potently and specifically affect cancer.

  1. Excitation of high-n toroidicity-induced shear Alfven eigenmodes by energetic particles and fusion alpha particles in tokamaks

    SciTech Connect

    Fu, G.Y.; Cheng, C.Z.

    1992-07-01

    The stability of high-n toroidicity-induced shear Alfven eigenmodes (TAE) in the presence of fusion alpha particles or energetic ions in tokamaks is investigated. The TAE modes are discrete in nature and thus can easily tap the free energy associated with energetic particle pressure gradient through wave particle resonant interaction. A quadratic form is derived for the high-n TAE modes using gyro-kinetic equation. The kinetic effects of energetic particles are calculated perturbatively using the ideal MHD solution as the lowest order eigenfunction. The finite Larmor radius (FLR) effects and the finite drift orbit width (FDW) effects are included for both circulating and trapped energetic particles. It is shown that, for circulating particles, FLR and FDW effects have two opposite influences on the stability of the high-n TAE modes. First, they have the usual stabilizing effects by reducing the wave particle interaction strength. Second, they also have destabilizing effects by allowing more particles to resonate with the TAE modes. It is found that the growth rate induced by the circulating alpha particles increase linearly with toroidal mode number n for small {kappa}{sub {theta}}{rho}{sub {alpha}}, and decreases as 1/n for {kappa}{sub {theta}}{rho}{sub {alpha}} {much_gt} 1. The maximum growth rate is obtained at {kappa}{sub {theta}}{rho}{sub {alpha}} on the order of unity and is nearly constant for the range of 0.7 < {upsilon}{sub {alpha}}/{upsilon}{sub A} < 2.5. On the other hand, the trapped particle response is dominated by the precessional drift resonance. The bounce resonant contribution is negligible. The growth rate peaks sharply at the value of {kappa}{sub {theta}}{rho}{sub {alpha}} such that the precessional drift resonance occurs for the most energetic trapped particles. The maximum growth rate due to the energetic trapped particles is comparable to that of circulating particles.

  2. Excitation of high-n toroidicity-induced shear Alfven eigenmodes by energetic particles and fusion alpha particles in tokamaks

    SciTech Connect

    Fu, G.Y.; Cheng, C.Z.

    1992-07-01

    The stability of high-n toroidicity-induced shear Alfven eigenmodes (TAE) in the presence of fusion alpha particles or energetic ions in tokamaks is investigated. The TAE modes are discrete in nature and thus can easily tap the free energy associated with energetic particle pressure gradient through wave particle resonant interaction. A quadratic form is derived for the high-n TAE modes using gyro-kinetic equation. The kinetic effects of energetic particles are calculated perturbatively using the ideal MHD solution as the lowest order eigenfunction. The finite Larmor radius (FLR) effects and the finite drift orbit width (FDW) effects are included for both circulating and trapped energetic particles. It is shown that, for circulating particles, FLR and FDW effects have two opposite influences on the stability of the high-n TAE modes. First, they have the usual stabilizing effects by reducing the wave particle interaction strength. Second, they also have destabilizing effects by allowing more particles to resonate with the TAE modes. It is found that the growth rate induced by the circulating alpha particles increase linearly with toroidal mode number n for small {kappa}{sub {theta}}{rho}{sub {alpha}}, and decreases as 1/n for {kappa}{sub {theta}}{rho}{sub {alpha}} {much gt} 1. The maximum growth rate is obtained at {kappa}{sub {theta}}{rho}{sub {alpha}} on the order of unity and is nearly constant for the range of 0.7 < {upsilon}{sub {alpha}}/{upsilon}{sub A} < 2.5. On the other hand, the trapped particle response is dominated by the precessional drift resonance. The bounce resonant contribution is negligible. The growth rate peaks sharply at the value of {kappa}{sub {theta}}{rho}{sub {alpha}} such that the precessional drift resonance occurs for the most energetic trapped particles. The maximum growth rate due to the energetic trapped particles is comparable to that of circulating particles.

  3. Enhanced homologous recombination is induced by alpha-particle radiation in somatic cells of Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Bian, Po; Liu, Ping; Wu, Yuejin

    Almost 9 percent of cosmic rays which strike the earth's atmosphere are alpha particles. As one of the ionizing radiations (IR), its biological effects have been widely studied. However, the plant genomic instability induced by alpha-particle radiation was not largely known. In this research, the Arabidopsis thaliana transgenic for GUS recombination substrate was used to evaluate the genomic instability induced by alpha-particle radiation (3.3MeV). The pronounced effects of systemic exposure to alpha-particle radiation on the somatic homologous recombination frequency (HRF) were found at different doses. The 10Gy dose of radiation induced the maximal HRF which was 1.9-fold higher than the control. The local radiation of alpha-particle (10Gy) on root also resulted in a 2.5-fold increase of somatic HRF in non-radiated aerial plant, indicating that the signal(s) of genomic instability was transferred to non-radiated parts and initiated their genomic instability. Concurrent treatment of seedlings of Arabidopsis thaliana with alpha-particle and DMSO(ROS scavenger) both in systemic and local radiation signifi- cantly suppressed the somatic HR, indicating that the free radicals produced by alpha-particle radiation took part in the production of signal of genomic instability rather than the signal transfer. Key words: alpha-particle radiation, somatic homologous recombination, genomic instability

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

    SciTech Connect

    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.

  5. Experimental Study of the Cross Sections of {alpha}-Particle Induced Reactions on 209Bi

    SciTech Connect

    Hermanne, A.; Tarkanyi, F.; Takacs, S.; Szucs, Z.

    2005-05-24

    Alpha particle induced reactions for generation of 211At used in therapeutic nuclear medicine and possible contaminants were investigated with the stacked foil activation technique on natural bismuth targets up to E{alpha}=39 MeV. Excitation functions for the reactions 209Bi({alpha},2n)211At, 209Bi({alpha},3n)210At, 209Bi({alpha},x) 210Po obtained from direct alpha emission measurements and gamma spectra from decay products are compared with earlier literature values. Thick target yields have been deduced from the experimental cross sections.

  6. Time delay can facilitate coherence in self-driven interacting-particle systems

    NASA Astrophysics Data System (ADS)

    Sun, Yongzheng; Lin, Wei; Erban, Radek

    2014-12-01

    Directional switching in a self-propelled particle model with delayed interactions is investigated. It is shown that the average switching time is an increasing function of time delay. The presented results are applied to studying collective animal behavior. It is argued that self-propelled particle models with time delays can explain the state-dependent diffusion coefficient measured in experiments with locust groups. The theory is further generalized to heterogeneous groups where each individual can respond to its environment with a different time delay.

  7. Alpha particle clusters and their condensation in nuclear systems

    NASA Astrophysics Data System (ADS)

    Schuck, Peter; Funaki, Yasuro; Horiuchi, Hisashi; Röpke, Gerd; Tohsaki, Akihiro; Yamada, Taiichi

    2016-12-01

    In this article we review the present status of α clustering in nuclear systems. First of all, an important aspect is condensation in nuclear matter. Like for pairing, quartetting in matter is at the root of similar phenomena in finite nuclei. Cluster approaches for finite nuclei are shortly recapitulated in historical order. The α container model, recently been proposed by Tohsaki-Horiuchi-Schuck-Röpke (THSR), will be outlined and the ensuing condensate aspect of the Hoyle state at 7.65 MeV in 12C is investigated in some detail. A special case will be made with respect to the very accurate reproduction of the inelastic form factor from the ground to Hoyle state with the THSR description. The extended volume will be deduced. New developments concerning excitations of the Hoyle state will be discussed. After 15 years since the proposal of the α condensation concept a critical assessment of this idea will be given. Alpha gas states in other nuclei like 16O and 13C will be considered. An important aspect is the experimental evidence, both present and future ones. The THSR wave function can also describe configurations of one α particle on top of a doubly magic core. The cases of 20Ne and 212Po will be investigated.

  8. The Rosetta Alpha Particle X-Ray Spectrometer (APXS)

    NASA Astrophysics Data System (ADS)

    Klingelhöfer, G.; Brückner, J.; D'Uston, C.; Gellert, R.; Rieder, R.

    2007-02-01

    The Alpha Particle X-Ray Spectrometer (APXS) is a small instrument to determine the elemental composition of a given sample. For the ESA Rosetta mission, the periodical comet 67P/Churyumov-Gerasimenko was selected as the target comet, where the lander PHILAE (after landing) will carry out in-situ observations. One of the instruments onboard is the APXS to make measurements on the landing site. The APXS science goal is to provide basic compositional data of the comet surface. As comets consist of a mixture of ice and dust, the dust component can be characterized and compared with known meteoritic compositions. Various element ratios can be used to evaluate whether chemical fractionations occurred in cometary material by comparing them with known chondritic material. To enable observations of the local environment, APXS measurements of several spots on the surface and one spot as function of temperature can be made. Repetitive measurements as function of heliocentric distance can elucidate thermal processes at work. By measuring samples that were obtained by drilling subsurface material can be analyzed. The accumulated APXS data can be used to shed light on state, evolution, and origin of 67P/Churyumov- Gerasimenko.

  9. Relative biological effectiveness of alpha-particle emitters in vivo at low doses.

    PubMed

    Howell, R W; Azure, M T; Narra, V R; Rao, D V

    1994-03-01

    The therapeutic potential of radionuclides that emit alpha particles, as well as their associated health hazards, have attracted considerable attention. The 224Ra daughters 212Pb and 212Bi, by virtue of their radiation properties which involve emission of alpha and beta particles in their decay to stable 208Pb, have been proposed as candidates for radioimmunotherapy. Using mouse testes as the experimental model and testicular spermhead survival as the biological end point, the present work examines the radiotoxicity of 212Pb and its daughters. When 212Pb, in equilibrium with its daughters 212Bi, 212Po and 208Tl, was administered directly into the testis, the dose required to achieve 37% survival (D37) was 0.143 +/- 0.014 Gy and the corresponding RBE of the mixed radiation field was 4.7 when compared to the D37 for acute external 120 kVp X rays. This datum, in conjunction with our earlier results for 210Po, was used to obtain an RBE-LET relationship for alpha particles emitted by tissue-incorporated radionuclides: RBE alpha = 4.8 - 6.1 x 10(-2) LET + 1.0 x 10(-3) LET2. Similarly, the dependence of RBE on alpha-particle energy E alpha was given by RBE alpha = 22 E(-0.73) alpha. These relationships, based on in vivo experimental data, may be valuable in predicting biological effects of alpha-particle emitters.

  10. Angular distribution of {alpha} particles from oriented {sup 253,254}Es and {sup 255}Fm nuclei

    SciTech Connect

    Severijns, N.; Golovko, V.V.; Kraev, I.S.; Phalet, T.; Belyaev, A.A.; Lukhanin, A.A.; Noga, V.I.; Erzinkyan, A.L.; Parfenova, V.P.; Eversheim, P.-D.; Herzog, P.; Tramm, C.; Filimonov, V.T.; Toporov, Yu.G.; Zotov, E.; Gurevich, G.M.; Rusakov, A.V.; Vyachin, V.N.; Zakoucky, D.

    2005-04-01

    The anisotropy in the angular distribution of {alpha} particles from oriented {sup 253,254}Es and {sup 255}Fm nuclei, which are among the strongest deformed {alpha} emitters, was measured. Large {alpha} anisotropies have been observed for all three nuclei. The results are compared with calculations based on {alpha}-particle tunneling through a deformed Coulomb barrier.

  11. Treatment with interferon-alpha delays disease in swine infected with a highly virulent CSFV strain.

    PubMed

    Fernandez-Sainz, I; Ramanathan, P; O'Donnell, V; Diaz-San Segundo, F; Velazquez-Salinas, L; Sturza, D F; Zhu, J; de los Santos, T; Borca, M V

    2015-09-01

    Interferon-alpha (IFNα) can effectively inhibit or abort a viral infection within the host. It has been reported that IFN induction and production is hindered during classical swine fever virus (CSFV) infection. Most of those studies have been performed in vitro, making it difficult to elucidate the actual role of IFNs during CSFV infection in swine. Here, we report the effect of IFNα treatment (delivered by a replication defective recombinant human adenovirus type 5, Ad5) in swine experimentally infected with highly virulent CSFV strain Brescia. Treatment with two different subtypes of IFNα delayed the appearance of CSF-related clinical signs and virus replication although it did not prevent lethal disease. This is the first report describing the effect of IFNα treatment during CSFV infection in swine.

  12. The effect of inelastic collisions on the transport of alpha particles in ITER-like plasmas

    NASA Astrophysics Data System (ADS)

    Clauser, C. F.; Farengo, R.

    2017-04-01

    The effect of charge changes on the transport of alpha particles in ITER-like plasmas is studied with a numerical code that follows the exact particle trajectories and includes the effect of elastic and inelastic collisions. It is shown that charge changing processes can produce significant changes in the transport of alpha particles in the edge-SOL region. The addition of inelastic collisions actually reduces the alpha particle loss rate below the level obtained when only elastic (Coulomb) collisions are included. This is due to the inward flux produced by the neutral density gradient. Power losses, on the other hand, remain at approximately the same level because the average energy of the lost particles is higher when inelastic collisions are included. Finally, the spatial distribution of the lost particles changes significantly when inelastic collisions are added, with a larger fraction of the lost particles reaching the wall.

  13. Measurements of alpha particle energy using nuclear tracks in solids methodology.

    PubMed

    Espinosa, G; Amero, C; Gammage, R B

    2002-01-01

    In this paper we present a method for the measurement of alpha particle energy using polycarbonate materials as nuclear track detectors (NTDs). This method is based on the interaction of the radiation with the solid-state materials, using the relationship between the energy deposited in the material by the ionising particle and the track developed after an established chemical process. The determination of the geometrical parameters of the formed track, such as major axis, minor axis and overall track length, permit determination of the energy of the alpha particle. The track analysis is performed automatically using a digital image system, and the data are processed in a PC with commercial software. In this experiment 148Gd, 238U, 230Th, 239Pu and 244Cm alpha particle emitters were used. The values for alpha particle energy resolution, the linear response to energy, the confidence in the results and the automatisation of the procedure make this method a promising analysis system.

  14. Method for characterizing the upset response of CMOS circuits using alpha-particle sensitive test circuits

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G. (Inventor); Blaes, Brent R. (Inventor); Nixon, Robert H. (Inventor); Soli, George A. (Inventor)

    1995-01-01

    A method for predicting the SEU susceptibility of a standard-cell D-latch using an alpha-particle sensitive SRAM, SPICE critical charge simulation results, and alpha-particle interaction physics. A technique utilizing test structures to quickly and inexpensively characterize the SEU sensitivity of standard cell latches intended for use in a space environment. This bench-level approach utilizes alpha particles to induce upsets in a low LET sensitive 4-k bit test SRAM. This SRAM consists of cells that employ an offset voltage to adjust their upset sensitivity and an enlarged sensitive drain junction to enhance the cell's upset rate.

  15. On the approximations of the distribution function of fusion alpha particles

    SciTech Connect

    Bilato, R. Brambilla, M.; Poli, E.

    2014-10-15

    The solution of the drift-kinetic equation for fusion-born alpha particles is derived in the limit of dominant parallel streaming, and it is related to the usual slowing-down distribution function. The typical approximations of the fast tail of fusion-born alpha particles are briefly compared and discussed. In particular, approximating the distribution function of fast-alpha particles with an “equivalent” Maxwellian is inaccurate to describe absorption of radio-frequency waves in the ion-cyclotron range of frequencies.

  16. MIRD Pamphlet No. 22 (Unabridged): Radiobiology and Dosimetry of alpha-Particle Emitters for Targeted Radionuclide Therapy

    SciTech Connect

    Sgouros, George; Roeske, John C.; McDevitt, Michael S.; Palm, Stig; Allen, Barry J.; Fisher, Darrell R.; Brill, Bertrand A.; Song, Hong; Howell, R. W.; Akabani, Gamal

    2010-02-28

    The potential of alpha-particle emitters to treat cancer has been recognized since the early 1900s. Advances in the targeted delivery of radionuclides, in radionuclide conjugation chemistry, and in the increased availability of alpha-emitters appropriate for clinical use have recently led to patient trials of alpha-particle-emitter labeled radiopharmaceuticals. Although alpha-emitters have been studied for many decades, their current use in humans for targeted therapy is an important milestone. The objective of this work is to review those aspects of the field that are pertinent to targeted alpha-particle-emitter therapy and to provide guidance and recommendations for human alpha-particle-emitter dosimetry.

  17. MIRD Pamphlet No. 22 (abridged): radiobiology and dosimetry of alpha-particle emitters for targeted radionuclide therapy.

    PubMed

    Sgouros, George; Roeske, John C; McDevitt, Michael R; Palm, Stig; Allen, Barry J; Fisher, Darrell R; Brill, A Bertrand; Song, Hong; Howell, Roger W; Akabani, Gamal; Bolch, Wesley E; Brill, A Bertrand; Fisher, Darrell R; Howell, Roger W; Meredith, Ruby F; Sgouros, George; Wessels, Barry W; Zanzonico, Pat B

    2010-02-01

    The potential of alpha-particle emitters to treat cancer has been recognized since the early 1900s. Advances in the targeted delivery of radionuclides and radionuclide conjugation chemistry, and the increased availability of alpha-emitters appropriate for clinical use, have recently led to patient trials of radiopharmaceuticals labeled with alpha-particle emitters. Although alpha-emitters have been studied for many decades, their current use in humans for targeted therapy is an important milestone. The objective of this work is to review those aspects of the field that are pertinent to targeted alpha-particle emitter therapy and to provide guidance and recommendations for human alpha-particle emitter dosimetry.

  18. Delay of diabetic cataract in rats by the antiglycating potential of cumin through modulation of alpha-crystallin chaperone activity.

    PubMed

    Kumar, Pasupulati Anil; Reddy, Paduru Yadagiri; Srinivas, P N B S; Reddy, Geereddy Bhanuprakash

    2009-07-01

    alpha-Crystallin, a molecular chaperone of the eye lens, plays an important role in maintaining the transparency of the lens by preventing the aggregation/inactivation of several proteins and enzymes in addition to its structural role. alpha-Crystallin is a long-lived protein and is susceptible to several posttranslational modifications during aging, more so in certain clinical conditions such as diabetes. Nonenzymatic glycation of lens proteins and decline in the chaperone-like function of alpha-crystallin have been reported in diabetic conditions. Therefore, inhibitors of nonenzymatic protein glycation appear to be a potential target to preserve the chaperone activity of alpha-crystallin and to combat cataract under hyperglycemic conditions. In this study, we investigated the antiglycating potential of cumin in vitro and its ability to modulate the chaperone-like activity of alpha-crystallin vis-à-vis the progression of diabetic cataract in vivo. Aqueous extract of cumin was tested for its antiglycating ability against fructose-induced glycation of goat lens total soluble protein (TSP), alpha-crystallin from goat lens and a nonlenticular protein bovine serum albumin (BSA). The antiglycating potential of cumin was also investigated by feeding streptozotocin (STZ)-induced diabetic rats with diet containing 0.5% cumin powder. The aqueous extract of cumin prevented in vitro glycation of TSP, alpha-crystallin and BSA. Slit lamp examination revealed that supplementation of cumin delayed progression and maturation of STZ-induced cataract in rats. Cumin was effective in preventing glycation of TSP and alpha-crystallin in diabetic lens. Interestingly, feeding of cumin to diabetic rats not only prevented loss of chaperone activity but also attenuated the structural changes of alpha-crystallin in lens. These results indicated that cumin has antiglycating properties that may be attributed to the modulation of chaperone activity of alpha-crystallin, thus delaying cataract in

  19. Feasibility studies of colorless LR 115 SSNTD for alpha-particle radiobiological experiments

    NASA Astrophysics Data System (ADS)

    Chan, K. F.; Tse, A. K. W.; Fong, W. F.; Yu, K. N.

    2006-06-01

    The feasibility of using the active layer of the colorless LR 115 SSNTD for alpha-particle radiobiological experiments was studied. The track revelation time on the bottom side (the side attached to the polyester base) was much longer than that on the top side (the side not attached to the polyester base) of the active layer so track formation on the top side was more desirable. In relation to this, culture of HeLa cells on the bottom side of the active layer was found feasible although the cultured cell number was relatively smaller. The feasibility of using this SSNTD for alpha-particle radiobiological experiments was demonstrated by culturing cells on the bottom side while performing alpha-particle irradiation and chemical etching on the top side, and by taking photographs of the cells and alpha-particle tracks together under the optical microscope.

  20. Alpha particles in solar cosmic rays over the last 80,000 years.

    NASA Technical Reports Server (NTRS)

    Lanzerotti, L. J.; Reedy, R. C.; Arnold, J. R.

    1973-01-01

    Present-day (1967 to 1969) fluxes of alpha particles from solar cosmic rays, determined from satellite measurements, were used to calculate the production rates of cobalt-57, cobalt-58, and nickel-59 in lunar surface samples. Comparisons with the activities of nickel-59 (half-life, 80,000 years) measured in lunar samples indicate that the long-term and present-day fluxes of solar alpha particles are comparable within a factor of approximately 4.

  1. Bose-Einstein condensation of {alpha} particles and Airy structure in nuclear rainbow scattering

    SciTech Connect

    Ohkubo, S.; Hirabayashi, Y.

    2004-10-01

    It is shown that the dilute density distribution of {alpha} particles in nuclei can be observed in the Airy structure in nuclear rainbow scattering. We have analyzed {alpha}+{sup 12}C rainbow scattering to the 0{sub 2}{sup +} (7.65 MeV) state of {sup 12}C in a coupled-channel method with the precise wave functions for {sup 12}C. It is found that the enhanced Airy oscillations in the experimental angular distributions for the 0{sub 2}{sup +} state is caused by the dilute density distribution of this state in agreement for the idea of Bose-Einstein condensation of the three alpha particles.

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

    SciTech Connect

    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.

  3. Superconducting calorimetric alpha particle sensors for nuclear nonproliferation applications

    SciTech Connect

    Horansky, Robert D.; Ullom, Joel N.; Beall, James A.; Hilton, Gene C.; Irwin, Kent D.; Dry, Donald E.; Hastings, Elizabeth P.; Lamont, Stephen P.; Rudy, Clifford R.; Rabin, Michael W.

    2008-09-22

    Identification of trace nuclear materials is usually accomplished by alpha spectrometry. Current detectors cannot distinguish critical elements and isotopes. We have developed a detector called a microcalorimeter, which achieves a resolution of 1.06 keV for 5.3 MeV alphas, the highest resolving power of any energy dispersive measurement. With this exquisite resolution, we can unambiguously identify the {sup 240}Pu/{sup 239}Pu ratio in Pu, a critical measurement for ascertaining the intended use of nuclear material. Furthermore, we have made a direct measurement of the {sup 209}Po ground state decay.

  4. Intense alpha-particle emitting crystallites in uranium mill wastes

    USGS Publications Warehouse

    Landa, E.R.; Stieff, L.R.; Germani, M.S.; Tanner, A.B.; Evans, J.R.

    1994-01-01

    Nuclear emulsion microscopy has demonstrated the presence of small, intense ??-particle emitting crystallites in laboratory-produced tailings derived from the sulfuric acid milling of uranium ores. The ??-particle activity is associated with the isotope pair 210Pb 210Po, and the host mineral appears to be PbSO4 occurring as inclusions in gypsum laths. These particles represent potential inhalation hazards at uranium mill tailings disposal areas. ?? 1994.

  5. Absorbed fractions for alpha-particles in tissues of cortical bone

    NASA Astrophysics Data System (ADS)

    Watchman, Christopher J.; Bolch, Wesley E.

    2009-10-01

    Bone-seeking alpha-particle emitting radionuclides are common health physics hazards. Additionally, they are under consideration as an option for therapeutic molecular radiotherapy applications. Current dose models do not account for energy or bone-site dependence as shown by alpha-particle absorbed fractions given in ICRP Publication 30. Energy-dependent, yet bone-site independent, alpha-particle absorbed fractions have been presented by the models of Stabin and Siegel (2003 Health Phys. 85 294-310). In this work, a chord-based computational model of alpha-particle transport in cortical bone has been developed that explicitly accounts for both the bone-site and particle-energy dependence of alpha-particle absorbed fractions in this region of the skeleton. The model accounts for energy deposition to three targets: cortical endosteum, haversian space tissues and cortical bone. Path length distributions for cortical bone given in Beddoe (1977 Phys. Med. Biol. 22 298-308) provided additional transport regions in the absorbed fraction calculation. Significant variations in absorbed fractions between different skeletal sites were observed. Differences were observed between this model and the absorbed fractions given in ICRP Publication 30, which varied by as much as a factor of 2.1 for a cortical bone surface source irradiating cortical endosteum.

  6. Use of .sup.3 He.sup.30 + ICRF minority heating to simulate alpha particle heating

    DOEpatents

    Post, Jr., Douglass E.; Hwang, David Q.; Hovey, Jane

    1986-04-22

    Neutron activation due to high levels of neutron production in a first heated deuterium-tritium plasma is substantially reduced by using Ion Cyclotron Resonance Frequency (ICRF) heating of energetic .sup.3 He.sup.++ ions in a second deuterium-.sup.3 He.sup.++ plasma which exhibit an energy distribution and density similar to that of alpha particles in fusion reactor experiments to simulate fusion alpha particle heating in the first plasma. The majority of the fast .sup.3 He.sup.++ ions and their slowing down spectrum can be studied using either a modulated hydrogen beam source for producing excited states of He.sup.+ in combination with spectrometers or double charge exchange with a high energy neutral lithium beam and charged particle detectors at the plasma edge. The maintenance problems thus associated with neutron activation are substantially reduced permitting energetic alpha particle behavior to be studied in near term large fusion experiments.

  7. Gamma-H2AX foci in cells exposed to a mixed beam of X-rays and alpha particles

    PubMed Central

    2012-01-01

    Background Little is known about the cellular effects of exposure to mixed beams of high and low linear energy transfer radiation. So far, the effects of combined exposures have mainly been assessed with clonogenic survival or cytogenetic methods, and the results are contradictory. The gamma-H2AX assay has up to now not been applied in this context, and it is a promising tool for investigating the early cellular response to mixed beam irradiation. Purpose To determine the dose response and repair kinetics of gamma-H2AX ionizing radiation-induced foci in VH10 human fibroblasts exposed to mixed beams of 241Am alpha particles and X-rays. Results VH10 human fibroblasts were irradiated with each radiation type individually or both in combination at 37°C. Foci were scored for repair kinetics 0.5, 1, 3 and 24 h after irradiation (one dose per irradiation type), and for dose response at the 1 h time point. The dose response effect of mixed beam was additive, and the relative biological effectiveness for alpha particles (as compared to X-rays) was of 0.76 ± 0.52 for the total number of foci, and 2.54 ± 1.11 for large foci. The repair kinetics for total number of foci in cells exposed to mixed beam irradiation was intermediate to that of cells exposed to alpha particles and X-rays. However, for mixed beam-irradiated cells the frequency and area of large foci were initially lower than predicted and increased during the first 3 hours of repair (while the predicted number and area did not). Conclusions The repair kinetics of large foci after mixed beam exposure was significantly different from predicted based on the effect of the single dose components. The formation of large foci was delayed and they did not reach their maximum area until 1 h after irradiation. We hypothesize that the presence of low X-ray-induced damage engages the DNA repair machinery leading to a delayed DNA damage response to the more complex DNA damage induced by alpha particles. PMID:23121736

  8. Simple experimental method for alpha particle range determination in lead iodide films

    SciTech Connect

    Dmitriev, Yuri; Bennett, Paul R.; Cirignano, Leonard J.; Klugerman, Mikhail; Shah, Kanai S.

    2007-05-15

    An experimental method for determining the range of alpha particles in films based on I-V{sub s} analysis has been suggested. The range of 5.5 MeV alpha particles in PbI{sub 2} films determined by this technique is 30{+-}5 {mu}m, and this value is in agreement with the value calculated by SRIM (the stopping and range of ions in matter), r=24 {mu}m in PbI{sub 2}. More than 100 I-V{sub s} of PbI{sub 2} films with different thicknesses and quality have been analyzed, and the influence of alpha particle radiation on PbI{sub 2} I-V{sub s} curves has been studied. Developed analytical methods (dependence of current density on electric field and conception of surface defects) were used, and the method limitations are discussed. It was shown that I-V{sub s} demonstrate the tendency to obey Ohm's law under alpha radiation. On the other hand, dark conductivity of the lead iodide films shows a typical impure character that can lead to an overestimation of the alpha particles' range in PbI{sub 2} films. After films were exposed to alpha radiation, the dark resistivity and I-V shape of some films improved. Also, a weak decrease of the charge carrier concentration, due to a decrease of the ''surface defect'' concentration (''surface refining''), was registered after successive measurements of I-V{sub s}.

  9. A comparison of different peak shapes for deconvolution of alpha-particle spectra

    NASA Astrophysics Data System (ADS)

    Marzo, Giuseppe A.

    2016-10-01

    Alpha-particle spectrometry is a standard technique for assessing the sample content in terms of alpha-decaying isotopes. A comparison of spectral deconvolutions performed adopting different peak shape functions has been carried out and a sensitivity analysis has been performed to test for the robustness of the results. As previously observed, there is evidence that the alpha peaks are well reproduced by a Gaussian modified by a function which takes into account the prominent tailing that an alpha-particle spectrum measured by means of a silicon detector exhibits. Among the different peak shape functions considered, that proposed by G. Bortels and P. Collaers, Int. J. Rad. Appl. Instrum. A 38, pp. 831-837 (1987) is the function which provides more accurate and more robust results when the spectral resolution is high enough to make such tailing significant. Otherwise, in the case of lower resolution alpha-particle spectra, simpler peak shape functions which are characterized by a lower number of fitting parameters provide adequate results. The proposed comparison can be useful for selecting the most appropriate peak shape function when accurate spectral deconvolution of alpha-particle spectra is sought.

  10. Effects of alpha-particles on survival and chromosomal aberrations in human mammary epithelial cells

    NASA Technical Reports Server (NTRS)

    Durante, M.; Grossi, G. F.; Gialanella, G.; Pugliese, M.; Nappo, M.; Yang, T. C.

    1995-01-01

    We have studied the radiation responses of a human mammary epithelial cell line, H184B5 F5-1 M/10. This cell line was derived from primary mammary cells after treatment with chemicals and heavy ions. The F5-1 M/10 cells are immortal, density-inhibited in growth, and non-tumorigenic in athymic nude mice and represent an in vitro model of the human epithelium for radiation studies. Because epithelial cells are the target of alpha-particles emitted from radon daughters, we concentrated our studies on the efficiency of alpha-particles. Confluent cultures of M/10 cells were exposed to accelerated alpha-particles [beam energy incident at the cell monolayer = 3.85 MeV, incident linear energy transfer (LET) in cell = 109 keV/microns] and, for comparison, to 80 kVp x-rays. The following endpoints were studied: (1) survival, (2) chromosome aberrations at the first postirradiation mitosis, and (3) chromosome alterations at later passages following irradiation. The survival curve was exponential for alpha-particles (D0 = 0.73 +/- 0.04 Gy), while a shoulder was observed for x-rays (alpha/beta = 2.9 Gy; D0 = 2.5 Gy, extrapolation number 1.6). The relative biological effectiveness (RBE) of high-LET alpha-particles for human epithelial cell killing was 3.3 at 37% survival. Dose-response curves for the induction of chromosome aberrations were linear for alpha-particles and linearquadratic for x-rays. The RBE for the induction of chromosome aberrations varied with the type of aberration scored and was high (about 5) for chromosome breaks and low (about 2) for chromosome exchanges.(ABSTRACT TRUNCATED AT 250 WORDS).

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

    PubMed

    Das, Achintya; Duttagupta, Siddhartha P

    2015-12-01

    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°-70°).The above model can be extended to other (wide band-gap semiconductor) device technologies useful for radiation-sensing application.

  12. Fusion alpha-particle diagnostics for DT experiments on the joint European torus

    SciTech Connect

    Kiptily, V. G.; Beaumont, P.; Syme, D. B.; Cecil, F. E.; Riva, M.; Conroy, S.; Ericsson, G.; Craciunescu, T.; Garcia-Munoz, M.; Curuia, M.; Soare, S.; Darrow, D.; Fernandes, A. M.; Pereira, R. C.; Sousa, J.; Gorini,; Nocente, M.; and others

    2014-08-21

    JET equipped with ITER-like wall (a beryllium wall and a tungsten divertor) can provide auxiliary heating with power up to 35MW, producing a significant population of α-particles in DT operation. The direct measurements of alphas are very difficult and α-particle studies require a significant development of dedicated diagnostics. JET now has an excellent set of confined and lost fast particle diagnostics for measuring the α-particle source and its evolution in space and time, α-particle energy distribution, and α-particle losses. This paper describes how the above mentioned JET diagnostic systems could be used for α-particle measurements, and what options exist for keeping the essential α-particle diagnostics functioning well in the presence of intense DT neutron flux. Also, α-particle diagnostics for ITER are discussed.

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

    SciTech Connect

    England, A.C.

    1984-03-01

    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 /sup 10/B(..cap alpha..,n)/sup 13/N, although /sup 14/N(..cap alpha..,..gamma..)/sup 18/F and others may be possible. The system, the sensitivity, the probe design, and the sources of error are described.

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

    SciTech Connect

    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.

  15. Alpha particle condensation in {sup 12}C and nuclear rainbow scattering

    SciTech Connect

    Ohkubo, S.; Hirabayashi, Y.

    2008-05-12

    It is shown that the large radius of the Hoyle state of {sup 12}C with a dilute density distribution in an {alpha} particle condensate can be clearly seen in the shift of the rainbow angle (therefore the Airy minimum) to a larger angle in {alpha}+{sup 12}C rainbow scattering at the high energy region and prerainbow oscillations in {sup 3}He+{sup 12}C scattering at the lower energy region.

  16. Turbulent transport of alpha particles in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Croitoru, A.; Palade, D. I.; Vlad, M.; Spineanu, F.

    2017-03-01

    We investigate the \\boldsymbol{E}× \\boldsymbol{B} diffusion of fusion born α 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 mode (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 α particles. According to our results, significant turbulent transport of the α particles can appear only at energies of the order of 100 KeV. We determine the corresponding conditions.

  17. Alpha particles induce apoptosis through the sphingomyelin pathway.

    PubMed

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

    2011-10-01

    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 α particles, which are of interest as potent environmental carcinogens, radiotherapies and potential components of dirty bombs, can act through this mechanism to signal apoptosis is unknown. Here we show that irradiation of Jurkat cells with α particles emitted by the ²²⁵Ac-DOTA-anti-CD3 IgG antibody construct results in dose-dependent apoptosis. This apoptosis was significantly reduced by pretreating cells with cholesterol-depleting nystatin, a reagent known to inhibit ceramide signaling by interfering with membrane raft coalescence and ceramide-rich platform generation. The effects of nystatin on α-particle-induced apoptosis were related to disruption of the ceramide pathway and not to microdosimetry alterations, because similar results were obtained after external irradiation of the cells with a broad beam of collimated α particles using a planar ²⁴¹Am source. External irradiation allowed for more precise control of the dosimetry and geometry of the irradiation, independent of antibody binding or cell internalization kinetics. Mechanistically consistent with these findings, Jurkat cells rapidly increased membrane concentrations of ceramide after external irradiation with an average of five α-particle traversals per cell. These data indicate that α particles can activate the sphingomyelin pathway to induce apoptosis.

  18. Fluorescent detection of single tracks of alpha particles using lithium fluoride crystals

    NASA Astrophysics Data System (ADS)

    Bilski, P.; Marczewska, B.

    2017-02-01

    Lithium fluoride single crystals were successfully used for fluorescent imaging of single tracks of alpha particles. This was realized with a standard wide-field fluorescent microscope equipped with a 100× objective. Alpha particles create F2 and F3+ color centers in LiF crystals. The subsequent illumination with the blue light (wavelength around 445 nm), excites these centers and produces fluorescence with a broad band peaked at 670 nm. The observed tracks of alpha particles have diameter of about 500 nm. Focusing of the microscope at different depths in a LiF crystal, enables imaging changes of shape and position of tracks, allowing for visualization of their paths. These encouraging results are the first step towards practical application of LiF as fluorescent nuclear track detectors.

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

    NASA Astrophysics Data System (ADS)

    Zat'ko, B.; Dubecký, F.; Šagátová, A.; Sedlačová, K.; Ryć, L.

    2015-04-01

    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.

  20. Directionality of Flare-Accelerated Alpha Particles at the Sun

    DTIC Science & Technology

    2003-01-01

    Directionality of Flare-Accelerated α Particles at the Sun Gerald H. Share, Ronald J. Murphy E.O. Hulburt Center for Space Research, Naval Research...2003 2. REPORT TYPE 3. DATES COVERED 00-00-2003 to 00-00-2003 4. TITLE AND SUBTITLE Directionality of Flare-Accelerated a Particles at the Sun 5a...one which is isotropic in the hemisphere towards the solar surface and has no component away from the Sun ) exhibits a broad struc- – 4 – ture from

  1. Alpha particle heating in hot diamagnetic cavities. [in solar wind near earth's bow shock

    NASA Technical Reports Server (NTRS)

    Galvez, Miguel; Fuselier, Stephen A.; Gary, S. Peter; Thomsen, Michelle F.; Winske, Dan

    1990-01-01

    Observational data from ISEE 1 are analyzed and a one-dimensional electromagnetic hybrid computer simulation is conducted for the heating of solar wind alpha particles in hot diamagnetic cavities (HDCs). In the simulation, which envisions alpha heating by ion-ion instabilities, low beam densities excite the proton/proton right-hand resonant instability that then pitch-angle scatters the beam without significantly heating the alphas. At greater beam densities, the proton/proton nonresonant instability undergoes saturation through a trapping of all three ion components. These results support the Thomsen et al. (1988) hypothesis that the nonresonant instability is the primary source of ion heating in hot diamagnetic cavities.

  2. FEF-Controlled Alpha Delay Activity Precedes Stimulus-Induced Gamma-Band Activity in Visual Cortex.

    PubMed

    Popov, Tzvetan; Kastner, Sabine; Jensen, Ole

    2017-04-12

    Recent findings in the visual system of nonhuman primates have demonstrated an important role of gamma-band activity (40-100 Hz) in the feedforward flow of sensory information, whereas feedback control appears to be established dynamically by oscillations in the alpha (8-13 Hz) and beta (13-18 Hz) bands (van Kerkoerle et al., 2014; Bastos et al., 2015). It is not clear, however, how alpha oscillations are controlled and how they interact with the flow of visual information mediated by gamma-band activity. Using noninvasive human MEG recordings in subjects performing a visuospatial attention task, we show that fluctuations in alpha power during a delay period in a spatial attention task preceded subsequent stimulus-driven gamma-band activity. Importantly, these interactions correlated with behavioral performance. Using Granger analysis, we further show that the right frontal-eye field (rFEF) exerted feedback control of the visual alpha oscillations. Our findings suggest that alpha oscillations controlled by the FEF route cortical information flow by modulating gamma-band activity.SIGNIFICANCE STATEMENT Visual perception relies on a feedforward flow of information from sensory regions, which is modulated by a feedback drive. We have identified the neuronal dynamics supporting integration of the feedforward and feedback information. Alpha oscillations in early visual regions reflect feedback control when spatial attention is allocated and this control is exercised by the right frontal eye field. Importantly, the alpha-band activity predicted both performance and activity in the gamma band. In particular, gamma activity was modulated by the phase of the alpha oscillations. These findings provide novel insight into how the brain operates as a network and suggest that the integration of feedforward and feedback information is implemented by cross-frequency interactions between slow and fast neuronal oscillations.

  3. Enhanced retention of the alpha-particle-emitting daughters of Actinium-225 by liposome carriers.

    PubMed

    Sofou, Stavroula; Kappel, Barry J; Jaggi, Jaspreet S; McDevitt, Michael R; Scheinberg, David A; Sgouros, George

    2007-01-01

    Targeted alpha-particle emitters hold great promise as therapeutics for micrometastatic disease. Because of their high energy deposition and short range, tumor targeted alpha-particles can result in high cancer-cell killing with minimal normal-tissue irradiation. Actinium-225 is a potential generator for alpha-particle therapy: it decays with a 10-day half-life and generates three alpha-particle-emitting daughters. Retention of (225)Ac daughters at the target increases efficacy; escape and distribution throughout the body increases toxicity. During circulation, molecular carriers conjugated to (225)Ac cannot retain any of the daughters. We previously proposed liposomal encapsulation of (225)Ac to retain the daughters, whose retention was shown to be liposome-size dependent. However, daughter retention was lower than expected: 22% of theoretical maximum decreasing to 14%, partially due to the binding of (225)Ac to the phospholipid membrane. In this study, Multivesicular liposomes (MUVELs) composed of different phospholipids were developed to increase daughter retention. MUVELs are large liposomes with entrapped smaller lipid-vesicles containing (225)Ac. PEGylated MUVELs stably retained over time 98% of encapsulated (225)Ac. Retention of (213)Bi, the last daughter, was 31% of the theoretical maximum retention of (213)Bi for the liposome sizes studied. MUVELs were conjugated to an anti-HER2/neu antibody (immunolabeled MUVELs) and were evaluated in vitro with SKOV3-NMP2 ovarian cancer cells, exhibiting significant cellular internalization (83%). This work demonstrates that immunolabeled MUVELs might be able to deliver higher fractions of generated alpha-particles per targeted (225)Ac compared to the relative fractions of alpha-particles delivered by (225)Ac-labeled molecular carriers.

  4. Prediction of Lung Cells Oncogenic Transformation for Induced Radon Progeny Alpha Particles Using Sugarscape Cellular Automata

    PubMed Central

    Baradaran, Samaneh; Maleknasr, Niaz; Setayeshi, Saeed; Akbari, Mohammad Esmaeil

    2014-01-01

    Background Alpha particle irradiation from radon progeny is one of the major natural sources of effective dose in the public population. Oncogenic transformation is a biological effectiveness of radon progeny alpha particle hits. The biological effects which has caused by exposure to radon, were the main result of a complex series of physical, chemical, biological and physiological interactions. The cellular and molecular mechanisms for radon-induced carcinogenesis have not been clear yet. Methods Various biological models, including cultured cells and animals, have been found useful for studying the carcinogenesis effects of radon progeny alpha particles. In this paper, sugars cape cellular automata have been presented for computational study of complex biological effect of radon progeny alpha particles in lung bronchial airways. The model has included mechanism of DNA damage, which has been induced alpha particles hits, and then formation of transformation in the lung cells. Biomarkers were an objective measure or evaluation of normal or abnormal biological processes. In the model, the metabolism rate of infected cell has been induced alpha particles traversals, as a biomarker, has been followed to reach oncogenic transformation. Results The model results have successfully validated in comparison with “in vitro oncogenic transformation data” for C3H 10T1/2 cells. This model has provided an opportunity to study the cellular and molecular changes, at the various stages in radiation carcinogenesis, involving human cells. Conclusion It has become well known that simulation could be used to investigate complex biomedical systems, in situations where traditional methodologies were difficult or too costly to employ. PMID:25250147

  5. Alpha-particle-induced p53 protein expression in a rat lung epithelial cell strain.

    PubMed

    Hickman, A W; Jaramillo, R J; Lechner, J F; Johnson, N F

    1994-11-15

    Other investigators have shown that both sparsely ionizing and UV radiation cause cell cycle arrest that is associated with increased expression of wild-type p53 protein. The effect of exposure to alpha-particles from 238Pu on the induction of the p53 protein has now been examined in cultured lung epithelial cells derived from male F344 rats. The number of cells having increased levels of p53 protein was determined by flow cytometry after the cells had been stained with a monoclonal antibody to p53. alpha-Particle irradiation caused a dose-dependent increase in p53 protein levels detectable at doses as low as 0.6 cGy, with no evidence of a threshold. An increase in p53 protein also occurred in X-irradiated cells. However, no increase was seen in cells exposed to less than 10 cGy of X-rays, indicating the existence of a relatively higher DNA damage threshold for sparsely ionizing radiation. In addition, more cells exposed to low doses of alpha radiation had increased p53 protein levels than would be predicted based on the number of nuclei expected to be traversed by an alpha-particle, suggesting that alpha-particles cause genetic damage by mechanisms in addition to direct interactions with DNA.

  6. Energy and frequency dependence of the alpha particle redistribution produced by internal kink modes

    SciTech Connect

    Farengo, R.; Ferrari, H. E.; Garcia-Martinez, P. L.; Firpo, M.-C.; Ettoumi, W.; Lifschitz, A. F.

    2014-08-15

    The redistribution of alpha particles due to internal kink modes is studied. The exact particle trajectories in the total fields, equilibrium plus perturbation, are calculated. The equilibrium has circular cross section and the plasma parameters are similar to those expected in ITER. The alpha particles are initially distributed according to a slowing down distribution function and have energies between 18 keV and 3.5 MeV. The (1, 1), (2, 2), and (2, 1) modes are included and the effect of changing their amplitude and frequency is studied. When only the (1, 1) mode is included, the spreading of high energy (E≳1 MeV) alpha particles increases slowly with the energy and mode frequency. At lower energies, the redistribution is more sensitive to the mode frequency and particle energy. When a (2, 1) mode is added, the spreading increases significantly and particles can reach the edge of the plasma. Trapped particles are the most affected and the redistribution parameter can have maxima above 1 MeV, depending on the mode frequency. These results can have important implications for ash removal.

  7. Nuclear reactions induced by high-energy alpha particles

    NASA Technical Reports Server (NTRS)

    Shen, B. S. P.

    1974-01-01

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

  8. Therapy of Ovarian Carcinoma by Targeted Delivery of Alpha-Particles Using Immunoliposomes Capable of Retaining Alpha-Emitting Daughters

    DTIC Science & Technology

    2005-10-01

    potent alpha-particle emitter actinium -225 in order to retain daughter emissions at the targeted site. In this grant we proposed to coat the liposomes...initial activity, and 1% actinium overall entrapment efficacy, we can achieve one encapsulated 225Ac nuclide per 8.7 MUVELs (assuming 4x1012 liposomes...with a mean diameter of 750nm). Increase of the initial activity to 10 mCi 225Ac should result in one actinium nuclide per MUVEL and two actinium

  9. Remodelling the vascular microenvironment of glioblastoma with alpha-particles

    PubMed Central

    Behling, Katja; Maguire, William F.; Di Gialleonardo, Valentina; Heeb, Lukas E.M.; Hassan, Iman F.; Veach, Darren R.; Keshari, Kayvan R.; Gutin, Philip H.; Scheinberg, David A.; McDevitt, Michael R.

    2016-01-01

    Rationale Tumors escape anti-angiogenic therapy by activation of pro-angiogenic signaling pathways. Bevacizumab is approved for the treatment of recurrent glioblastoma, but patients inevitably develop resistance to this angiogenic inhibitor. We investigated targeted α-particle therapy with 225Ac-E4G10 as an anti-vascular approach and previously showed increased survival and tumor control in a high-grade transgenic orthotopic glioblastoma model. Here we investigate changes in tumor-vascular morphology and functionality caused by 225Ac-E4G10. Methods We investigated remodeling of tumor microenvironment in transgenic Ntva glioblastoma mice using a therapeutic 7.4 kBq dose of 225Ac-E4G10. Immunofluorescence and immunohistochemical analyses imaged morphological changes in the tumor blood brain barrier microenvironment. Multi-color flow cytometry quantified the endothelial progenitor cell population in the bone marrow. Diffusion-weighted magnetic resonance imaged functional changes of the tumor vascular network. Results The mechanism of drug action is a combination of glioblastoma vascular microenvironment remodeling, edema relief, and depletion of regulatory T and endothelial progenitor cells. The primary remodeling event is the reduction of both endothelial and perivascular cell populations. Tumor-associated edema and necrosis was lessened and resulted in increased perfusion and reduced diffusion. Pharmacological uptake of dasatinib into tumor was enhanced following α-particle therapy. Conclusion Targeted anti-vascular α-particle radiation remodels the glioblastoma vascular microenvironment via a multimodal mechanism of action and provides insight into the vascular architecture of Platelet-derived growth factor driven glioblastoma. PMID:27261519

  10. Fast detection of alpha particles in DAM-ADC nuclear track detectors

    NASA Astrophysics Data System (ADS)

    Rammah, Y. S.; Ashraf, O.; Abdalla, A. M.; Eisa, M.; Ashry, A. H.; Tsuruta, T.

    2015-02-01

    Fast detection of alpha particles in DAM-ADC nuclear track detectors using a new chemical etchant was investigated. 252Cf and 241Am sources were used for irradiating samples of DAM-ADC SSNTDs with fission fragments and alpha particles in air at normal temperature and pressure. A series of experimental chemical etching are carried out using new etching solution (8 ml of 10 N NaOH+ 1 ml CH3OH) at 60 °C to detect alpha particle in short time in DAM-ADC detectors. Suitable analyzing software has been used to analyze experimental data. From fission and alpha track diameters, the value of bulk etching rate is equal to 8.52 μm/h. Both of the sensitivity and etching efficiency were found to vary with the amount of methanol in the etching solution and etching time. The DAM-ADC detectors represent the best efficiency applicable in detectors in the entire range of alpha energies (from 1 to 5 MeV). The activation energies of this etchant have been calculated; track activation energy, ET, has been found to be lower than the bulk activation energy, EB, for the DAM-ADC nuclear track detectors. These results are in more agreement with the previous work.

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

    SciTech Connect

    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.

  12. H{alpha} measurements and neutral particle transport in Heliotron J

    SciTech Connect

    Kobayashi, S.; Yabutani, H.; Nakashima, Y.; Higashizono, Y.; Nagasaki, K.; Mizuuchi, T.; Okada, H.; Sano, F.; Cappa, A.; Kondo, K.; Nakamura, Y.; Suzuki, Y.

    2006-10-15

    A multichannel system of the H{alpha}-line emission detector is developed in order to investigate the neutral particle transport in the Heliotron J plasma. The application of a multianode photomultiplier tube to the filter measurement system enables us to observe the H{alpha} emission profile with 32 chords. The absolute calibration with a standard lamp is performed and the cross-talk between each of the adjoining channels is evaluated to be less than 6%, while the photomultiplier tube has a typical cross-talk of 3% in nominal value. The temporal and spatial profiles of the H{alpha} emission are measured in detail in the plasma breakdown by electron cyclotron heating (ECH). The H{alpha} emission profile in the ECH plasma is calculated by the Monte Carlo simulation using a three-dimensional mesh model. The fueling rates of the wall recycling and the gas puffing are estimated by means of the simulation and the measurement.

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

    SciTech Connect

    Espinosa Garcia, Guillermo; Golzarri y Moreno, Dr. Jose Ignacio; Bogard, James S

    2008-01-01

    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.

  14. A Strange Box and a Stubborn Brit: Rutherford's Experiments with Alpha Particles.

    ERIC Educational Resources Information Center

    Digilov, M.

    1991-01-01

    Discusses 5 innovative experiments conducted by Rutherford in early 1900s utilizing the 30 milligrams of radium salt he personally carried from Europe to Canada in 1903. Traces his work with alpha particles from his original results which determined their nature, charge, and mass, to his technique of backscattering which helped to advance…

  15. Nucleon-Alpha Particle Disequilibrium and Short-Lived r-Process Radioactivities

    NASA Technical Reports Server (NTRS)

    Meyer, B. S.; Clayton, D. D.; Chellapilla, S.; The, L.-S.

    2002-01-01

    r-Process yields can be extremely sensitive to expansion parameters when a persistent disequilibrium between free nucleons and alpha particles is present. This may provide a natural scenario for understanding the variation of heavy and light r-process isotopes in different r-process events. Additional information is contained in the original extended abstract.

  16. Fine structural features in {alpha}-silicon nitride powder particles and their implications

    SciTech Connect

    Wang, C.M.

    1995-12-01

    Commercial Si{sub 3}N{sub 4} powder particles have been studied with transmission electron microscopy. A vacancy type of dislocation loop is revealed to be a typical feature of as-grown {alpha}-Si{sub 3}N{sub 4} particles fabricated through the imide decomposition method. As a result of vacancy agglomeration on the (0001) plane, a stacking fault which is distinctively situated in the very middle of an individual particle with respect to the c-axis can be seen within some particles. In combination with three other recent publications reporting dislocation loops in {alpha}-Si{sub 3}N{sub 4} but produced by different methods, it seems that dislocation loops are a common feature of as-grown {alpha}-Si{sub 3}N{sub 4} even produced by distinctively different methods. Of the most relevance to the present observation, the controversy over the structural nature of {alpha}-Si{sub 3}N{sub 4} is discussed.

  17. Sufficient condition for velocity-space stability of the alpha particle distribution in a tokamak reactor

    SciTech Connect

    Cordey, J.G.; Goldston, R.J.; Mikkelsen, D.R.

    1980-08-01

    A condition is derived for the velocity-space distribution of suprathermal alpha particles to be monotonically decreasing with energy - and hence stable to homogeneous plasma instabilities - during the heating phase of a tokamak reactor. This stability condition is easily satisfied for presently envisaged neutral injection heating of reactors, but may be violated in strong heating of smaller plasmas or during fast compressional heating.

  18. Can Bose condensation of alpha particles be observed in heavy ion collisions?

    NASA Technical Reports Server (NTRS)

    Tripathi, Ram K.; Townsend, Lawrence W.

    1993-01-01

    Using a fully self-consistent quantum statistical model, we demonstrate the possibility of Bose condensation of alpha particles with a concomitant phase transition in heavy ion collisions. Suggestions for the experimental observation of the signature of the onset of this phenomenon are made.

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

    SciTech Connect

    Kerns, J.A.

    1986-05-01

    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.

  20. Production of actinium-225 for alpha particle mediated radioimmunotherapy.

    PubMed

    Boll, Rose A; Malkemus, Dairin; Mirzadeh, Saed

    2005-05-01

    The initial clinical trials for treatment of acute myeloid leukemia have demonstrated the effectiveness of the alpha emitter (213)Bi in killing cancer cells. Bismuth-213 is obtained from a radionuclide generator system from decay of 10-days (225)Ac parent. Recent pre-clinical studies have also shown the potential application of both (213)Bi, and the (225)Ac parent radionuclide in a variety of cancer systems and targeted radiotherapy. This paper describes our five years of experience in production of (225)Ac in partial support of the on-going clinical trials. A four-step chemical process, consisting of both anion and cation exchange chromatography, is utilized for routine separation of carrier-free (225)Ac from a mixture of (228)Th, (229)Th and (232)Th. The separation of Ra and Ac from Th is achieved using the marcoporous anion exchange resin MP1 in 8M HNO(3) media. Two sequential MP1/NO(3) columns provide a separation factor of approximately 10(6) for Ra and Ac from Th. The separation of Ac from Ra is accomplished on a low cross-linking cation exchange resin AG50-X4 using 1.2M HNO(3) as eluant. Two sequential AG50/NO(3) columns provide a separation factor of approximately 10(2) for Ac from Ra. A 60-day processing schedule has been adopted in order to reduce the processing cost and to provide the highest levels of (225)Ac possible. Over an 8-week campaign, a total of approximately 100 mCi of (225)Ac (approximately 80% of the theoretical yield) is shipped in 5-6 batches, with the first batch typically consisting of approximately 50 mCi. After the initial separation and purification of Ac, the Ra pool is re-processed on a bi-weekly schedule or as needed to provide smaller batches of (225)Ac. The averaged radioisotopic purity of the (225)Ac was 99.6 +/- 0.7% with a (225)Ra content of < or =0.6%, and an average (229)Th content of (4(-4)(+5)) x 10(-5)%.

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

    SciTech Connect

    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.

  2. Effect of Photon Hormesis on Dose Responses to Alpha Particles in Zebrafish Embryos

    PubMed Central

    Ng, Candy Yuen Ping; Cheng, Shuk Han; Yu, Kwan Ngok

    2017-01-01

    Photon hormesis refers to the phenomenon where the biological effect of ionizing radiation with a high linear energy transfer (LET) value is diminished by photons with a low LET value. The present paper studied the effect of photon hormesis from X-rays on dose responses to alpha particles using embryos of the zebrafish (Danio rerio) as the in vivo vertebrate model. The toxicity of these ionizing radiations in the zebrafish embryos was assessed using the apoptotic counts at 20, 24, or 30 h post fertilization (hpf) revealed through acridine orange (AO) staining. For alpha-particle doses ≥ 4.4 mGy, the additional X-ray dose of 10 mGy significantly reduced the number of apoptotic cells at 24 hpf, which proved the presence of photon hormesis. Smaller alpha-particle doses might not have inflicted sufficient aggregate damages to trigger photon hormesis. The time gap T between the X-ray (10 mGy) and alpha-particle (4.4 mGy) exposures was also studied. Photon hormesis was present when T ≤ 30 min, but was absent when T = 60 min, at which time repair of damage induced by alpha particles would have completed to prevent their interactions with those induced by X-rays. Finally, the drop in the apoptotic counts at 24 hpf due to photon hormesis was explained by bringing the apoptotic events earlier to 20 hpf, which strongly supported the removal of aberrant cells through apoptosis as an underlying mechanism for photon hormesis. PMID:28208665

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

    PubMed

    Lyckesvärd, Madeleine Nordén; Delle, Ulla; Kahu, Helena; Lindegren, Sture; Jensen, Holger; Bäck, Tom; Swanpalmer, John; Elmroth, Kecke

    2014-07-01

    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 mechanism as (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 ((60)Co) and alpha particles from (211)At in normal primary thyrocytes of different cell cycle status. For both radiation qualities the intensity 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. Increasing ratios of micronuclei per cell nuclei were seen up to 1Gy (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 effectiveness of alpha particles.

  4. Delay coordinates: a sensitive indicator of nonlinear dynamics in single charged particle motion in magnetic reversals

    NASA Astrophysics Data System (ADS)

    Chapman, Sandra C.; Watkins, Nicholas W.

    1995-08-01

    The delay coordinate technique is examined as an indicator of the regime of particle dynamics for the system of single charged particle motion in magnetic reversals. Examples of numerically integrated trajectories in both static (zero electric field) and time dependent (corresponding nonzero induction electric field) simple models for magnetic reversals are considered. In the static case, the dynamics can in principle be directly classified by constructing Poincaré surfaces of section; here we demonstrate that whilst the Poincaré surface contains the relevant information to classify the dynamics, the corresponding delay coordinate plot can provide a far more sensitive indication of the onset of nonregular behaviour. In the case of nonperiodic time dependence considered here Poincaré plots cannot in general be constructed directly. Nevertheless, delay coordinate plots can still reveal details of the phase space portrait of the system, and here are shown to indicate whether segments of stochastic motion exist in a given trajectory. It is anticipated that the delay coordinate plot technique as realized here will be a valuable tool in characterizing the behaviour in large numbers of trajectories that are evolved in time-dependent systems, thereby giving us insight into the evolution of the distribution function as a whole, either in prescribed fields or in self-consistent numerical simulations.

  5. Variation of the track etch rates of alpha-particle trajectory in PADC

    NASA Astrophysics Data System (ADS)

    Zaki, M. F.; Hegazy, T. M.; Seddik, U.; Morsy, A. A.

    2005-01-01

    The formation of etched tracks in solid-state nuclear track detectors is usually described by assuming an unequivocal correlation of the etch-rate ratio with the energy loss of charged particles. For alpha particles, this assumption could be verified within the scatter of the experimental data. In this article, the dependence of the depth (x) on the track etch rate (V-T) was determined experimentally by track length measurement. It is found that the track etch rate as a function of the depth within the detector follows the Bragg curve. The track etch rate has been found to be described by a generalization of the restricted energy loss, in good approximation along the trajectories of alpha particles.

  6. Transition delay and its implications for drag reduction in particle-laden channel flow

    NASA Astrophysics Data System (ADS)

    Sardina, G.; Brandt, L.

    2015-12-01

    Direct numerical simulations of a two-way coupled particle-laden channel flow are performed in the transitional and turbulent regime. Our aim is to investigate whether particles, assumed solid, spherical and heavy delay transition and diminish drag in wall bounded flows. We consider that the only interaction between the carrier and dispersed phase is due to the Stokes drag. The simulations have been performed with a pseudo-spectral solver for the incompressible Navier-Stokes equations while the particle equations are solved in a Lagrangian formulation. In the transitional regime, we study the evolution of disturbances added to a plane Poiseuille base flow with Reynolds number 2000, based on the channel half-height and centerline velocity. By fixing the Reynolds number, the only two free parameters are the particle Stokes number St and the particle mass fraction f. Two different scenarios are considered depending on the initial condition of the velocity field. The first scenario consists of counter-rotating streamwise vortices and one three-dimensional mode while the second is a nonlinear interaction of two symmetric oblique waves. The effects of the particles on the flow transition depend on the particle mass fraction. In particular, at lower concentrations, the transition is facilitated by the presence of the particles, conversely at higher mass fractions the particles tend to stabilize the flow. The results indicate that the particle can play an important role by influencing secondary instabilities and streaks breakdown. These effects can be linked to the reduced drag observed in turbulent channel flow laden with heavy particles and specific simulations in the turbulent regime have been performed.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Track reconstruction and performance of DRIFT directional dark matter detectors using alpha particles

    NASA Astrophysics Data System (ADS)

    Burgos, S.; Forbes, J.; Ghag, C.; Gold, M.; Kudryavtsev, V. A.; Lawson, T. B.; Loomba, D.; Majewski, P.; 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, E.

    2008-01-01

    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) ms-1 based on an analysis of naturally occurring alpha-emitting background. The drift velocity in DRIFT-IIb was 57±1 (stat)±3 (sys) ms-1 determined by the analysis of alpha particle tracks from a 210Po source. Three-dimensional range reconstruction and range spectra were used to identify alpha particles from the decay of 222Rn, 218Po, 220Rn and 216Po. This study found that (22±2)% of 218Po progeny (from 222Rn decay) did not plate out and remained suspended in the 40 Torr CS 2 gas fill until they decayed. A likely explanation for this is that some of the polonium progeny are produced in an uncharged state. For 216Po progeny (from 220Rn decay) the undeposited fraction was apparently much higher at (100-35+0)% most likely due to a shorter lifetime, causing a larger fraction of the progeny to decay whilst drifting to the cathode plane. This explanation implies a much slower drift time for positively charged polonium progeny compared to CS2- ions.

  9. Lost alpha-particle diagnostics from a D-T plasma by using nuclear reactions

    SciTech Connect

    Sasao, Mamiko; Wada, Motoi; Isobe, Mitsutaka

    2014-08-21

    Among various methods proposed for alpha-particles loss measurement, we studied on those by measuring gamma rays of three cases, from (1) nuclear reactions induced by alpha particles, (2) those from short-life-time activities and (3) those from long-life-time activities induced by alpha particles. The time evolution of local alpha flux may possibly be measured by using the {sup 9}Be (a, n) {sup 12}C reaction (1). Using the same system, but with a target set up close to the first wall, activation measurement on site right after turning-off the discharge is possible (2). Nuclear reaction, {sup 25}Mg (a, p) {sup 28}Al, that produce radioisotopes of short lifetime of 2.2 minutes in one of the best candidates. As to the activation to a long lifetime (3), it is predicted that the gamma ray yield from {sup 19}F (a, n) {sup 22}Na reaction is enough for the measurement at the reactor site.

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

    SciTech Connect

    Fisher, R.K.; Parks, P.B.; McChesney, J.M.; Rosenbluth, M.N.

    1994-06-01

    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. Alpha-particle emissivity screening of materials used for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Gordon, Michael; Rodbell, Kenneth

    2015-03-01

    Single-Event Upsets (SEU's) in semiconductor memory and logic devices continue to be a reliability issue in modern CMOS devices. SEU's result from deposited charge in the Si devices caused by the passage of ionizing radiation. With technology scaling, the device area decreases, but the critical charge required to flip bits decreases as well. The interplay between both determines how the SEU rate scales with shrinking device geometries and dimensions. In order to minimize the alpha-particle component of SEU, the radiation in the device environment has to be at the Ultra-Low Alpha (ULA) activity levels, e.g. less than 2 α/khr-cm2. Most detectors have background levels that are significantly larger than that level which makes making these measurements difficult and time consuming. A new class of alpha particle detector, utilizing pulse shape discrimination, is now available which allows one to make measurements quickly with ultra-low detector background. This talk will discuss what is involved in making alpha particle measurements of materials in the ULA activity levels, in terms of calibration, radon adsorption mitigation, the time required for obtaining reasonable statistics and comparisons to other detectors.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26007733

  13. Alpha-Particle Angular Distributions of At and Rn Isotopes and Their Relation to Nuclear Structure

    SciTech Connect

    NICOLE Collaboration and ISOLDE Collaboration

    1996-12-01

    We report on an extensive on-line nuclear orientation study of the angular distribution of {alpha} particles emitted in the favored decay of neutron deficient At and Rn nuclei near the {ital N}=126 shell closure. Surprisingly large anisotropies were observed, showing pronounced changes from one isotope to another. Comparing these data with several theoretical models shows that anisotropic {alpha} emission in favored decays from near-spherical nuclei can well be explained within the shell model, implying that it is mainly determined by the structure of the decaying nucleus. {copyright} {ital 1996 The American Physical Society.}

  14. Bulk GaN alpha-particle detector with large depletion region and improved energy resolution

    NASA Astrophysics Data System (ADS)

    Xu, Qiang; Mulligan, Padhraic; Wang, Jinghui; Chuirazzi, William; Cao, Lei

    2017-03-01

    An alpha-particle detector was fabricated using a freestanding n-type bulk GaN wafer with a Au/Ni/GaN sandwich Schottky structure. Current-voltage measurements at room temperature revealed a Schottky contact with a leakage current of 7.53±0.3 nA at a reverse bias of 200 V. The detector had a large depletion depth that can capture much of the energy from 5.486 MeV alpha particles emitted from a 241Am source. The resolution of its alpha-particle energy spectrum was improved to 2.2±0.2% at 5.486 MeV under a bias of 550 V. This superior resolution was attributed to the shortening of the carrier transit time and the large energy deposition within the large depletion depth, i.e., 27 μm at -550 V, which all resulted in a more complete charge collection. A model developed using the ATLAS simulation framework from Silvaco Inc. was employed to study the charge collection process. The simulation results were found to agree closely with the experimental results. This detector will be beneficial for research at neutron scattering facilities, the International Thermonuclear Experimental Reactor, and the Large Hadron Collider, among other institutions, where the Si-based charged particle detectors could be quickly degraded in an intense radiation field.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Alpha-particle-induced luminescence of rare-earth-doped Y 2O 3 nanophosphors

    NASA Astrophysics Data System (ADS)

    Cress, Cory D.; Redino, Christopher S.; Landi, Brian J.; Raffaelle, Ryne P.

    2008-08-01

    The feasibility of utilizing Y 2O 3:Tb 3+ and Y 2O 3:Eu 3+ as radioluminescent nanophosphors under alpha-particle excitation is investigated. Materials synthesized by the urea homogeneous precipitation method were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The XRD analysis of as-produced precipitates and nanophosphors fired at temperatures ranging from 950 to 1100 °C indicated the presence of highly crystalline cubic Y 2O 3 with crystallite sizes of ˜40 nm. SEM and TEM analysis revealed that particles with average diameters of ˜200 nm and comprised of ˜40 nm grains were obtained. High-resolution radioluminescence and photoluminescence spectra were used to investigate the unwanted radioluminescence saturation effects associated with the high ionization rate of alpha-particles. Additionally, the radioluminescence intensity as a function of rare-earth ion dopant concentration is investigated for these materials under alpha-particle excitation. The prospect for utilizing these materials as intermediate absorbers in indirect-conversion radioisotope batteries is discussed.

  18. Ionization-cluster distributions of alpha-particles in nanometric volumes of propane: measurement and calculation.

    PubMed

    De Nardo, L; Colautti, P; Conte, V; Baek, W Y; Grosswendt, B; Tornielli, G

    2002-12-01

    The probability of the formation of ionization clusters by primary alpha-particles at 5.4 MeV in nanometric volumes of propane was studied experimentally and by Monte Carlo simulation, as a function of the distance between the center line of the particle beam and the center of the target volume. The volumes were of cylindrical shape, 3.7 mm in diameter and height. As the investigations were performed at gas pressures of 300 Pa and 350 Pa, the dimensions of the target volume were equivalent to 20.6 nm or 24.0 nm in a material of density 1.0 g/cm(3). The dependence of ionization-cluster formation on distance was studied up to values equivalent to about 70 nm. To validate the measurements, a Monte Carlo model was developed which allows the experimental arrangement and the interactions of alpha-particles and secondary electrons in the counter gas to be properly simulated. This model is supplemented by a mathematical formulation of cluster size formation in nanometric targets. The main results of our study are (i) that the mean ionization-cluster size in the delta-electron cloud of an alpha-particle track segment, decreases as a function of the distance between the center line of the alpha-particle beam and the center of the sensitive target volume to the power of 2.6, and (ii) that the mean cluster size in critical volumes and the relative variance of mean cluster size due to delta-electrons are invariant at distances greater than about 20 nm. We could imagine that the ionization-cluster formation in nanometric volumes might in future provide the physical basis for a redefinition of radiation quality.

  19. A Nonlinear Framework of Delayed Particle Smoothing Method for Vehicle Localization under Non-Gaussian Environment

    PubMed Central

    Xiao, Zhu; Havyarimana, Vincent; Li, Tong; Wang, Dong

    2016-01-01

    In this paper, a novel nonlinear framework of smoothing method, non-Gaussian delayed particle smoother (nGDPS), is proposed, which enables vehicle state estimation (VSE) with high accuracy taking into account the non-Gaussianity of the measurement and process noises. Within the proposed method, the multivariate Student’s t-distribution is adopted in order to compute the probability distribution function (PDF) related to the process and measurement noises, which are assumed to be non-Gaussian distributed. A computation approach based on Ensemble Kalman Filter (EnKF) is designed to cope with the mean and the covariance matrix of the proposal non-Gaussian distribution. A delayed Gibbs sampling algorithm, which incorporates smoothing of the sampled trajectories over a fixed-delay, is proposed to deal with the sample degeneracy of particles. The performance is investigated based on the real-world data, which is collected by low-cost on-board vehicle sensors. The comparison study based on the real-world experiments and the statistical analysis demonstrates that the proposed nGDPS has significant improvement on the vehicle state accuracy and outperforms the existing filtering and smoothing methods. PMID:27187405

  20. Cryogenic microcalorimeter system for ultra-high resolution alpha-particle spectrometry

    SciTech Connect

    Rabin, Michael W; Hoover, Andrew S; Bacrania, Mnesh K; Croce, Mark P; Hoteling, N J; Lamont, S P; Plionis, A A; Dry, D E; Ullom, J N; Bennett, D A; Horansky, R; Kotsubo, V; Cantor, R

    2009-01-01

    Microcalorimeters have been shown to yield unsurpassed energy resolution for alpha spectrometry, up to 1.06 keV FWHM at 5.3 MeV. These detectors use a superconducting transition-edge sensor (TES) to measure the temperature change in an absorber from energy deposited by an interacting alpha particle. Our system has four independent detectors mounted inside a liquid nitrogen/liquid helium cryostat. An adiabatic demagnetization refrigerator (ADR) cools the detector stage to its operating temperature of 80 mK. Temperature regulation with {approx}15 uK peak-to-peak variation is achieved by PID control of the ADR. The detectors are voltage-biased, and the current signal is amplified by a commercial SQUID readout system and digitized for further analysis, This paper will discuss design and operation of our microcalorimeter alpha spectrometer, and will show recent results.

  1. /sup 212/Bismuth linked to an antipancreatic carcinoma antibody: model for alpha-particle-emitter radioimmunotherapy

    SciTech Connect

    Kurtzman, S.H.; Russo, A.; Mitchell, J.B.; DeGraff, W.; Sindelar, W.F.; Brechbiel, M.W.; Gansow, O.A.; Friedman, A.M.; Hines, J.J.; Gamson, J.

    1988-05-18

    For comparison of cytotoxicity from alpha-particle irradiation with that from conventional x-irradiation, /sup 212/Bi, an alpha-emitting radionuclide, was attached to a monoclonal antibody that recognizes a cell surface antigen on human pancreatic carcinoma cells. For a given level of survival, the /sup 212/Bi-antibody complex was found to be approximately 20 times more efficient in cell killing than x-irradiation and 5 times more cytotoxic when compared with the cytotoxicity of an antigen-negative cell line or an isotype-matched control antibody. High linear energy transfer radioimmunotherapy using alpha emitters linked to monoclonal antibodies may be useful in vivo and in vitro for selectively killing target cell populations, especially those resistant to other forms of treatment.

  2. Targeted alpha-particle radiotherapy with 211At-labeled monoclonal antibodies.

    PubMed

    Zalutsky, Michael R; Reardon, David A; Pozzi, Oscar R; Vaidyanathan, Ganesan; Bigner, Darell D

    2007-10-01

    An attractive feature of targeted radionuclide therapy is the ability to select radionuclides and targeting vehicles with characteristics that are best suited for a particular clinical application. One combination that has been receiving increasing attention is the use of monoclonal antibodies (mAbs) specifically reactive to receptors and antigens that are expressed in tumor cells to selectively deliver the alpha-particle-emitting radiohalogen astatine-211 (211At) to malignant cell populations. Promising results have been obtained in preclinical models with multiple 211At-labeled mAbs; however, translation of the concept to the clinic has been slow. Impediments to this process include limited radionuclide availability, the need for suitable radiochemistry methods operant at high activity levels and lack of data concerning the toxicity of alpha-particle emitters in humans. Nonetheless, two clinical trials have been initiated to date with 211At-labeled mAbs, and others are planned for the near future.

  3. New measurements of W-values for protons and alpha particles.

    PubMed

    Giesen, U; Beck, J

    2014-10-01

    The increasing importance of ion beams in cancer therapy and the lack of experimental data for W-values for protons and heavy ions in air require new measurements. A new experimental set-up was developed at PTB and consistent measurements of W-values in argon, nitrogen and air for protons and alpha particles with energies from 0.7 to 3.5 MeV u(-1) at PTB, and for carbon ions between 3.6 and 7.0 MeV u(-1) at GSI were carried out. This publication concentrates on the measurements with protons and alpha particles at PTB. The experimental methods and the determination of corrections for recombination effects, beam-induced background radiation and additional effects are presented.

  4. Preferential Heating and Acceleration of {alpha} Particles by Alfven-Cyclotron Waves

    SciTech Connect

    Araneda, J. A.; Maneva, Y.; Marsch, E.

    2009-05-01

    Preferential heating and acceleration of heavy ions in the solar wind and corona represent a long-standing theoretical problem in space physics, and are distinct experimental signatures of kinetic processes occurring in collisionless plasmas. We show that fast and slow ion-acoustic waves (IAW) and transverse waves, driven by Alfven-cyclotron wave parametric instabilities can selectively destroy the coherent fluid motion of different ion species and, in this way lead to their differential heating and acceleration. Trapping of the more abundant protons by the fast IAW generates a proton beam with drift speed of about the Alfven speed. Because of their larger mass, {alpha} particles do not become significantly trapped and start, by conservation of total ion momentum, drifting relative to the receding bulk protons. Thus the resulting core protons and the {alpha} particles are differentially heated via pitch-angle scattering.

  5. Revisiting alpha decay-based near-light-speed particle propulsion.

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. An experimental quantification of the NOX production efficiency of energetic alpha particles in air

    NASA Astrophysics Data System (ADS)

    Rahman, Mahbubur; Cooray, Vernon; Possnert, Göran; Nyberg, Johan

    2006-07-01

    An experimental study on the production of NOX by alpha particles impact in air at atmospheric pressure is presented. A mixed radioactive source of 208Po and 209Po with an integrated activity of 9.6 MBq over a solid angle of 2π and an average alpha particle energy of 4.5 MeV was used for ionization of atmospheric air in an airtight chamber and the NOX production was measured by the chemiluminescence method. The NOX production rate is found to be about 1.2 NOX molecules per ion-pair. The NOX production efficiency per Joule of dissipated energy is calculated to be 20×1016 NOX molecules per Joule. This efficiency is comparable to that of hot laboratory sparks discharges.

  8. Effects of magnetic ripple on 3D equilibrium and alpha particle confinement in the European DEMO

    NASA Astrophysics Data System (ADS)

    Pfefferlé, D.; Cooper, W. A.; Fasoli, A.; Graves, J. P.

    2016-11-01

    An assessment of alpha particle confinement is performed in the European DEMO reference design. 3D MHD equilibria with nested flux-surfaces and single magnetic axis are obtained with the VMEC free-boundary code, thereby including the plasma response to the magnetic ripple created by the finite number of TF coils. Populations of fusion alphas that are consistent with the equilibrium profiles are evolved until slowing-down with the VENUS-LEVIS orbit code in the guiding-centre approximation. Fast ion losses through the last-closed flux-surface are numerically evaluated with two ripple models: (1) using the 3D equilibrium and (2) algebraically adding the non-axisymmetric ripple perturbation to the 2D equilibrium. By virtue of the small ripple field and its non-resonant nature, both models quantitatively agree. Differences are however noted in the toroidal location of particles losses on the last-closed flux-surface, which in the first case is 3D and in the second not. Superbanana transport, i.e. ripple-well trapping and separatrix crossing, is expected to be the dominant loss mechanism, the strongest effect on alphas being between 100-200 KeV. Above this, stochastic ripple diffusion is responsible for a rather weak loss rate, as the stochastisation threshold is observed numerically to be higher than analytic estimates. The level of ripple in the current 18 TF coil design of the European DEMO is not found to be detrimental to fusion alpha confinement.

  9. Mutagenic effects of a single and an exact number of alpha particles in mammalian cells

    NASA Technical Reports Server (NTRS)

    Hei, T. K.; Wu, L. J.; Liu, S. X.; Vannais, D.; Waldren, C. A.; Randers-Pehrson, G.

    1997-01-01

    One of the main uncertainties in risk estimation for environmental radon exposure using lung cancer data from underground miners is the extrapolation from high- to low-dose exposure where multiple traversal is extremely rare. The biological effects of a single alpha particle are currently unknown. Using the recently available microbeam source at the Radiological Research Accelerator Facility at Columbia University, we examined the frequencies and molecular spectrum of S1- mutants induced in human-hamster hybrid (A(L)) cells by either a single or an exact number of alpha particles. Exponentially growing cells were stained briefly with a nontoxic concentration of Hoechst dye for image analysis, and the location of individual cells was computer-monitored. The nucleus of each cell was irradiated with either 1,2,4, or 8 alpha particles at a linear energy transfer of 90 keV/microm consistent with the energy spectrum of domestic radon exposure. Although single-particle traversal was only slightly cytotoxic to A(L) cells (survival fraction approximately 0.82), it was highly mutagenic, and the induced mutant fraction averaged 110 mutants per 10(5) survivors. In addition, both toxicity and mutant induction were dose-dependent. Multiplex PCR analysis of mutant DNA showed that the proportion of mutants with multilocus deletions increased with the number of particle traversals. These data provide direct evidence that a single a particle traversing a nucleus will have a high probability of resulting in a mutation and highlight the need for radiation protection at low doses.

  10. Alpha particle spectra in coincidence with normal and superdeformed states in {sup 150}Tb

    SciTech Connect

    Viesti, G.; Lunardon, M.; Bazzacco, D. |

    1996-12-31

    The study of correlations between particle evaporation from highly excited compound nuclei at large angular momenta and the states in the final evaporation residues (ER) is a field of investigation which has been opened, in the last years, with the advent of the new large {gamma}-ray arrays. It is now possible to correlate the evaporation spectra to various bands with shapes ranging from spherical to superdeformed (SD) in the same final nucleus. It is generally accepted that the particle evaporation from the compound nucleus is chaotic and that only in the near-yrast {gamma} cascade, where the feeding of different classes of states takes place, the ordered motion is restored. The sensitivity of the particle spectra on the feeding of specific states in the residual nuclei can be taken as an indication that additional degrees of freedom might be important in the evaporation process or that particular regions of the phase space open to the decay populate preferentially some selected structures in the final cold nucleus. This latter point is important for the understanding of the feeding mechanism of SD states. Several experiments performed so far did not find a clear dependence of the shapes of the particle spectra on the excited states having different deformations in the ER. For example, the proton spectra in coincidence with transitions in the SD bands of {sup 133}Nd and {sup 152}Dy nuclei were found to be similar to those in coincidence with transitions in the normal deformed (ND) bands. Alpha particles have been proposed since long as a sensitive probe of the deformation of the emitting nucleus. Results are presented here of an experiment in which the authors have measured the energy spectra of alpha particles associated with different classes of states (ND and SD) in the {sup 150}Tb nucleus populated in the reaction {sup 37}Cl({sup 120}Sn, {alpha}3n{gamma}){sup 150}Tb.

  11. Mutagenic effects of a single and an exact number of alpha particles in mammalian cells.

    PubMed

    Hei, T K; Wu, L J; Liu, S X; Vannais, D; Waldren, C A; Randers-Pehrson, G

    1997-04-15

    One of the main uncertainties in risk estimation for environmental radon exposure using lung cancer data from underground miners is the extrapolation from high- to low-dose exposure where multiple traversal is extremely rare. The biological effects of a single alpha particle are currently unknown. Using the recently available microbeam source at the Radiological Research Accelerator Facility at Columbia University, we examined the frequencies and molecular spectrum of S1- mutants induced in human-hamster hybrid (A(L)) cells by either a single or an exact number of alpha particles. Exponentially growing cells were stained briefly with a nontoxic concentration of Hoechst dye for image analysis, and the location of individual cells was computer-monitored. The nucleus of each cell was irradiated with either 1,2,4, or 8 alpha particles at a linear energy transfer of 90 keV/microm consistent with the energy spectrum of domestic radon exposure. Although single-particle traversal was only slightly cytotoxic to A(L) cells (survival fraction approximately 0.82), it was highly mutagenic, and the induced mutant fraction averaged 110 mutants per 10(5) survivors. In addition, both toxicity and mutant induction were dose-dependent. Multiplex PCR analysis of mutant DNA showed that the proportion of mutants with multilocus deletions increased with the number of particle traversals. These data provide direct evidence that a single a particle traversing a nucleus will have a high probability of resulting in a mutation and highlight the need for radiation protection at low doses.

  12. Results from the Lunar Prospector Alpha Particle Spectrometer: Detection of Radon-222 Over Craters Aristarchus and Kepler

    NASA Astrophysics Data System (ADS)

    Lawson, S. L.; Feldman, W. C.; Lawrence, D. J.; Moore, K. R.; Belian, R. D.; Maurice, S.; Binder, A. B.

    2001-11-01

    The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-218 (6.0 MeV, 3 minute half-life), and solid polonium-210 (5.3 MeV, 138 day half-life, but held up in production by the 21 year half-life of lead-210). These three nuclides are radioactive daughters from the decay of uranium-238. Radon reaches the lunar surface either at areas of high soil porosity or where fissures release the trapped gases in which radon is entrained. We have examined APS data within +/- 45 degrees of the equator acquired during periods of low interplanetary alpha particle flux. The spectra were summed over all LP mapping cycles when the instrument was turned on (approximately 229 days over 16 months). To yield lunar alpha particle maps, we summed over a 0.2 MeV energy range centered on each of the three alpha particle energies noted above. The LP APS found only a faint indication of alpha particles resulting from the decay of polonium-218 and only a marginal detection of alpha particles from polonium-210. However, our radon-222 alpha particle map indicates that radon gas is presently emanating from the vicinity of craters Aristarchus and Kepler. The LP gamma-ray spectrometer, which effectively has significantly higher spatial resolution than the APS, identified thorium enrichments at these two craters. Thorium and uranium are both incompatible elements whose lunar surface abundances are highly correlated; thus, it is likely that the radon-222 alpha particles measured using the LP APS originate from Kepler and Aristarchus. Our detection of radon over Aristarchus is consistent with the results of the Apollo 15 APS.

  13. Reaction cross sections of intermediate energy {alpha} particles within a relativistic optical model

    SciTech Connect

    Ait-Tahar, S.; Nedjadi, Y.

    1995-07-01

    The suggestion made recently by H. Abele {ital et} {ital al}. that relativistic effects in the interaction of alpha particles with various nuclei at intermediate energies may remove the existing discrepancy between the theoretical predictions and the experimental data for the reaction cross section is investigated. We use a relativistic model based on the Kemmer-Duffin-Petiau equation and find that relativistic effects do not lead to a reduction in the reaction cross section within the present approach. Alternative explanations are discussed.

  14. Fusion alpha-particle losses in a high-beta rippled tokamak

    SciTech Connect

    Bunno, M.; Nakamura, Y.; Suzuki, Y.; Shinohara, K.; Matsunaga, G.; Tani, K.

    2013-08-15

    In tokamak plasmas, the confinement of energetic ions depends on the magnetic field structure. If the plasma pressure is finite, the equilibrium current (i.e., the Pfirsch-Schlüter current and diamagnetic current) flows in the plasma to maintain the magnetohydrodynamic (MHD) equilibrium. These plasma currents generate poloidal and toroidal magnetic field and alter the field structure. Moreover, if we consider the non-axisymmetry of magnetic field structures such as toroidal field (TF) ripples, the non-axisymmetric component of the equilibrium current can alter TF ripples themselves. When the plasma beta becomes high, the changes in the field structure due to the equilibrium current might affect the confinement of energetic ions significantly. We intend to clarify how these currents alter the field structure and affect the confinement of alpha particles in high-beta plasma. The MHD equilibrium is calculated using VMEC and the orbits of fusion alpha particles are followed by using the fully three-dimensional magnetic field orbit-following Monte Carlo code. In relatively low-beta plasma (e.g., the volume-averaged beta value <β>≤2%), the changes in the magnetic field component due to the plasma current negligibly affect the confinement of alpha particles except for the Shafranov shift effect. However, for <β>≥3%, the diamagnetic effect reduces the magnetic field strength and significantly increases alpha-particle losses. In these high-beta cases, the non-axisymmetric field component generated by the equilibrium current also increases these losses, but not as effectively as compared to the diamagnetic effect.

  15. A CAM (continuous air monitor) sampler for collecting and assessing alpha-emitting aerosol particles

    SciTech Connect

    McFarland, A.R.; Bethel, E.L.; Ortiz, C.A.; Stanke, J.G. )

    1991-07-01

    A new continuous air monitor (CAM) sampler for assessing alpha-emitting transuranic aerosol particles has been developed. The system has been designed to permit collection of particles that can potentially penetrate into the thoracic region of the human respiratory system. Wind tunnel testing of the sampler has been used to characterize the penetration of aerosol to the collection filter. Results show that greater than or equal to 50% of 10-micrograms aerodynamic equivalent diameter (AED) particles are collected by the filter at wind speeds of 0.3 to 2 m s-1 and at sampling flow rates of 28 to 113 L min-1 (1 to 4 cfm). The deposition of 10-microns AED particles takes place primarily in the center of the filter, where the counting efficiency of the detector is highest.

  16. Alpha particle transport in the presence of ballooning type electrostatic driftwaves

    NASA Astrophysics Data System (ADS)

    Nishimura, Y.; Huang, B.; Cheng, C. Z.

    2015-07-01

    Employing Hamiltonian mechanics, the transport of fusion born alpha particles in the presence of driftwave turbulence is investigated. An analytical turbulence model based on the toroidal drift eigenmode is employed for guiding center orbit-following calculations. It is shown that high energy particles are less susceptible to driftwave turbulence. The passing particle transport is due to overlapping of guiding center electric islands whose widths are inversely proportional to the square root of the parallel velocity. For trapped particles, through a coordinate transformation from the poloidal angle and the parallel velocity to the action-angle variables, the resonance between the bounce motion and the toroidal precession motion, which can cause secondary island formation in the phase space, is demonstrated.

  17. Critical temperature for {alpha}-particle condensation within a momentum-projected mean-field approach

    SciTech Connect

    Sogo, T.; Roepke, G.; Lazauskas, R.

    2009-05-15

    {alpha}-particle (quartet) condensation in homogeneous spin-isospin symmetric nuclear matter is investigated. The usual Thouless criterion for the critical temperature is extended to the quartet case. The in-medium four-body problem is strongly simplified by the use of a momentum-projected mean-field ansatz for the quartet. The self-consistent single-particle wave functions are shown and discussed for various values of the density at the critical temperature. Excellent agreement of the critical temperature with a numerical solution of the Faddeev-Yakubovsky equation is obtained.

  18. Acceleration of low-energy protons and alpha particles at interplanetary shock waves

    NASA Technical Reports Server (NTRS)

    Scholer, M.; Hovestadt, D.; Ipavich, F. M.; Gloeckler, G.

    1983-01-01

    The low-energy protons and alpha particles in the energy range 30 keV/charge to 150 keV/charge associated with three different interplanetary shock waves in the immediate preshock and postshock region are studied using data obtained by the ISEE 3. The spatial distributions in the preshock and postshock medium are presented, and the dependence of the phase space density at different energies on the distance from the shock and on the form of the distribution function of both species immediately at the shock is examined. It is found that in the preshock region the particles are flowing in the solar wind frame of reference away from the shock and in the postshock medium the distribution is more or less isotropic in this frame of reference. The distribution function in the postshock region can be represented by a power law in energy which has the same spectral exponent for both protons and alpha particles. It is concluded that the first-order Fermi acceleration process can consistently explain the data, although the spectra of diffuse bow shock associated particles are different from the spectra of the interplanetary shock-associated particles in the immediate vicinity of the shock. In addition, the mean free path of the low energy ions in the preshock medium is found to be considerably smaller than the mean free path determined by the turbulence of the background interplanetary medium.

  19. Energy loss of proton, alpha particle, and electron beams in hafnium dioxide films

    SciTech Connect

    Behar, Moni; Fadanelli, Raul C.; Nagamine, Luiz C. C. M.; Abril, Isabel; Denton, Cristian D.; Garcia-Molina, Rafael; Arista, Nestor R.

    2009-12-15

    The electronic stopping power, S, of HfO{sub 2} films for proton and alpha particle beams has been measured and calculated. The experimental data have been obtained by the Rutherford backscattering technique and cover the range of 120-900 and 120-3000 keV for proton and alpha particle beams, respectively. Theoretical calculations of the energy loss for the same projectiles have been done by means of the dielectric formalism using the Mermin energy loss function--generalized oscillator strength (MELF-GOS) model for a proper description of the HfO{sub 2} target on the whole momentum-energy excitation spectrum. At low projectile energies, a nonlinear theory based on the extended Friedel sum rule has been employed. The calculations and experimental measurements show good agreement for protons and a quite good one for alpha particles. In particular, the experimental maximums of both stopping curves (around 120 and 800 keV, respectively) are well reproduced. On the basis of this good agreement, we have also calculated the inelastic mean-free path (IMFP) and the stopping power for electrons in HfO{sub 2} films. Our results predict a minimum value of the IMFP and a maximum value of the S for electrons with energies around 120 and 190 eV, respectively.

  20. Inertially confined fusion plasmas dominated by alpha-particle self-heating

    NASA Astrophysics Data System (ADS)

    Hurricane, O. A.; Callahan, D. A.; Casey, D. T.; Dewald, E. L.; Dittrich, T. R.; Döppner, T.; Haan, S.; Hinkel, D. E.; Berzak Hopkins, L. F.; Jones, O.; Kritcher, A. L.; Le Pape, S.; Ma, T.; Macphee, A. G.; Milovich, J. L.; Moody, J.; Pak, A.; Park, H.-S.; Patel, P. K.; Ralph, J. E.; Robey, H. F.; Ross, J. S.; Salmonson, J. D.; Spears, B. K.; Springer, P. T.; Tommasini, R.; Albert, F.; Benedetti, L. R.; Bionta, R.; Bond, E.; Bradley, D. K.; Caggiano, J.; Celliers, P. M.; Cerjan, C.; Church, J. A.; Dylla-Spears, R.; Edgell, D.; Edwards, M. J.; Fittinghoff, D.; Barrios Garcia, M. A.; Hamza, A.; Hatarik, R.; Herrmann, H.; Hohenberger, M.; Hoover, D.; Kline, J. L.; Kyrala, G.; Kozioziemski, B.; Grim, G.; Field, J. E.; Frenje, J.; Izumi, N.; Gatu Johnson, M.; Khan, S. F.; Knauer, J.; Kohut, T.; Landen, O.; Merrill, F.; Michel, P.; Moore, A.; Nagel, S. R.; Nikroo, A.; Parham, T.; Rygg, R. R.; Sayre, D.; Schneider, M.; Shaughnessy, D.; Strozzi, D.; Town, R. P. J.; Turnbull, D.; Volegov, P.; Wan, A.; Widmann, K.; Wilde, C.; Yeamans, C.

    2016-08-01

    Alpha-particle self-heating, the process of deuterium-tritium fusion reaction products depositing their kinetic energy locally within a fusion reaction region and thus increasing the temperature in the reacting region, is essential for achieving ignition in a fusion system. Here, we report new inertial confinement fusion experiments where the alpha-particle heating of the plasma is dominant with the fusion yield produced exceeding the fusion yield from the work done on the fuel (pressure times volume change) by a factor of two or more. These experiments have achieved the highest yield (26 +/- 0.5 kJ) and stagnation pressures (≍220 +/- 40 Gbar) of any facility-based inertial confinement fusion experiments, although they are still short of the pressures required for ignition on the National Ignition Facility (~300-400 Gbar). These experiments put us in a new part of parameter space that has not been extensively studied so far because it lies between the no-alpha-particle-deposition regime and ignition.

  1. Distributions and thermalization of protons and alpha particles at collisionless quasi-parallel shocks.

    NASA Astrophysics Data System (ADS)

    Trattner, K. J.; Scholer, M.

    1993-09-01

    The dissipation processes of protons and a minor ion component, alpha particles, at quasi-parallel supercritical collisionless shocks are investigated by one-dimensional hybrid simulations. For both ion components the dissipation at these shocks is due to two different mechanisms: Heating is either caused by the nonadiabatic transition of the ions through the shock ramp where ions move through the region of the sharp jump in the magnetic field magnitude and direction, or by a mechanism which involves the occurrence of specularly reflected ions and subsequent shock reformation. In the latter case, reflected ions form a counterstreaming beam and lead to re-formation of the shock at the leading edge of the reflected ion beam. The region between the re-formed and the old shock, where the initial solar wind and the reflected beam have not completely merged, exhibits a sharp increase of the total pressure. The authors have also investigated the dependence of the downstream alpha particle to proton temperature ratio as a function of the upstream density, the plasma beta and the Alfvén Mach number of the shock. Quasi-parallel collisionless shock heating of alpha particles is more efficient than heating of protons. The downstream temperature ratio is higher than the upstream solar wind temperature ratio.

  2. Radioluminescence of solid neodymium-doped laser materials excited by {alpha}-particles and fission fragments

    SciTech Connect

    Seregina, E A; Seregin, A A

    2013-02-28

    The characteristics of radioluminescence of Nd{sup 3+} : Y{sub 3}Al{sub 5}O{sub 12} crystals and laser glasses under excitation by plutonium-239 ({sup 239}Pu) {alpha}-particles, as well as by {alpha}-particles and spontaneous fission fragments of californium-252 ({sup 252}Cf), are studied. The radioluminescence branching ratios {beta}{sub ij} for the transition from the {sup 2}F2{sub 5/2} level to the {sup 2S+1}L{sub J} levels in Nd{sup 3+} : Y{sub 3}Al{sub 5}O{sub 12} crystals are measured. Radioluminescence from the {sup 2}P{sub 3/2} level to low-lying levels is observed. The {beta}{sub ij} ratios for transitions from the high-lying {sup 2}F2{sub 5/2}, {sup 4}D{sub 3/2}, and {sup 2}P{sub 3/2} levels are theoretically calculated. The lifetimes of metastable levels of Nd{sup 3+} excited by {sup 252}Cf fission fragments are measured. The efficiency of the conversion of energy of {alpha}-particles and fission fragments to the energy of optical radiation of Nd{sup 3+} : Y{sub 3}Al{sub 5}O{sub 12} crystals and laser glasses is determined. (active media)

  3. The local skin dose conversion coefficients of electrons, protons and alpha particles calculated using the Geant4 code.

    PubMed

    Zhang, Bintuan; Dang, Bingrong; Wang, Zhuanzi; Wei, Wei; Li, Wenjian

    2013-10-01

    The skin tissue-equivalent slab reported in the International Commission on Radiological Protection (ICRP) Publication 116 to calculate the localised skin dose conversion coefficients (LSDCCs) was adopted into the Monte Carlo transport code Geant4. The Geant4 code was then utilised for computation of LSDCCs due to a circular parallel beam of monoenergetic electrons, protons and alpha particles <10 MeV. The computed LSDCCs for both electrons and alpha particles are found to be in good agreement with the results using the MCNPX code of ICRP 116 data. The present work thus validates the LSDCC values for both electrons and alpha particles using the Geant4 code.

  4. Targeted alpha therapy using short-lived alpha-particles and the promise of nanobodies as targeting vehicle

    PubMed Central

    Dekempeneer, Yana; Keyaerts, Marleen; Krasniqi, Ahmet; Puttemans, Janik; Muyldermans, Serge; Lahoutte, Tony; D’huyvetter, Matthias; Devoogdt, Nick

    2016-01-01

    ABSTRACT Introduction: The combination of a targeted biomolecule that specifically defines the target and a radionuclide that delivers a cytotoxic payload offers a specific way to destroy cancer cells. Targeted radionuclide therapy (TRNT) aims to deliver cytotoxic radiation to cancer cells and causes minimal toxicity to surrounding healthy tissues. Recent advances using α-particle radiation emphasizes their potential to generate radiation in a highly localized and toxic manner because of their high level of ionization and short range in tissue. Areas covered: We review the importance of targeted alpha therapy (TAT) and focus on nanobodies as potential beneficial vehicles. In recent years, nanobodies have been evaluated intensively as unique antigen-specific vehicles for molecular imaging and TRNT. Expert opinion: We expect that the efficient targeting capacity and fast clearance of nanobodies offer a high potential for TAT. More particularly, we argue that the nanobodies’ pharmacokinetic properties match perfectly with the interesting decay properties of the short-lived α-particle emitting radionuclides Astatine-211 and Bismuth-213 and offer an interesting treatment option particularly for micrometastatic cancer and residual disease. PMID:27145158

  5. A model for thin layer formation by delayed particle settling at sharp density gradients

    NASA Astrophysics Data System (ADS)

    Prairie, Jennifer C.; White, Brian L.

    2017-02-01

    Thin layers - regions where plankton or particles accumulate vertically on scales of a few meters or less - are common in coastal waters, and have important implications for both trophic dynamics and carbon cycling. These features can form by a variety of biological and physical mechanisms, including localized growth, shear-thinning, and directed swimming. An additional mechanism may result in the formation of thin layers of marine aggregates, which have been shown to decrease their settling velocity when passing through sharp density gradients, a behavior termed delayed settling. Here, we apply a simple vertical advection-diffusion model to predict the properties of aggregate thin layers formed by this process. We assume a constant vertical flux of particles from the surface, which is parameterized by observations from laboratory experiments with marine aggregates. The formation, maintenance, and shape of the layers are described in relation to non-dimensional numbers that depend on environmental conditions and particle settling properties. In particular, model results demonstrate layer intensity and sharpness both increase with higher Péclet number (Pe), that is, under conditions with weaker mixing relative to layer formation. Similarly, more intense and sharper layers are found when the delayed settling behavior of aggregates is characterized by a lower velocity minimum. The model also predicts layers that are vertically asymmetric and highly "peaky" when compared with a Gaussian distribution, features often seen in thin layers in natural environments. Lastly, by comparing model predictions with observations of thin layers in the field, we are able to gain some insight into the applicability of delayed settling as a thin layer formation mechanism in different environmental conditions.

  6. Alpha particles induce pan-nuclear phosphorylation of H2AX in primary human lymphocytes mediated through ATM.

    PubMed

    Horn, Simon; Brady, Darren; Prise, Kevin

    2015-10-01

    The use of high linear energy transfer radiations in the form of carbon ions in heavy ion beam lines or alpha particles in new radionuclide treatments has increased substantially over the past decade and will continue to do so due to the favourable dose distributions they can offer versus conventional therapies. Previously it has been shown that exposure to heavy ions induces pan-nuclear phosphorylation of several DNA repair proteins such as H2AX and ATM in vitro. Here we describe similar effects of alpha particles on ex vivo irradiated primary human peripheral blood lymphocytes. Following alpha particle irradiation pan-nuclear phosphorylation of H2AX and ATM, but not DNA-PK and 53BP1, was observed throughout the nucleus. Inhibition of ATM, but not DNA-PK, resulted in the loss of pan-nuclear phosphorylation of H2AX in alpha particle irradiated lymphocytes. Pan-nuclear gamma-H2AX signal was rapidly lost over 24h at a much greater rate than foci loss. Surprisingly, pan-nuclear gamma-H2AX intensity was not dependent on the number of alpha particle induced double strand breaks, rather the number of alpha particles which had traversed the cell nucleus. This distinct fluence dependent damage signature of particle radiation is important in both the fields of radioprotection and clinical oncology in determining radionuclide biological dosimetry and may be indicative of patient response to new radionuclide cancer therapies.

  7. Quality assurance of alpha-particle dosimetry using peeled-off Gafchromic EBT3® film

    NASA Astrophysics Data System (ADS)

    Ng, C. Y. P.; Chun, S. L.; Yu, K. N.

    2016-08-01

    A novel alpha-particle dosimetry technique using Gafchromic EBT3 film has recently been proposed for calibrating the activity of alpha-emitting radiopharmaceuticals. In the present paper, we outlined four measures which could further help assure the quality of the method. First, we suggested an alternative method in fabricating the peeled-off EBT3 film. Films with a chosen size were cut from the original films and all the edges were sealed with silicone. These were immersed into deionized water for 19 d and the polyester covers of the EBT3 films could then be easily peeled off. The active layers in these peeled-off EBT3 films remained intact, and these films could be prepared reproducibly with ease. Second, we proposed a check on the integrity of the peeled-off film by comparing the responses of the pristine and peeled-off EBT3 films to the same X-ray irradiation. Third, we highlighted the importance of scanning directions of the films. The "landscape" and "portrait" scanning directions were defined as the scanning directions perpendicular and parallel to the long edge of the original EBT3 films, respectively. Our results showed that the responses were different for different scanning directions. As such, the same scanning direction should be used every time. Finally, we cautioned the need to confirm the uniformity of the alpha-particle source used for calibration. Radiochromic films are well known for their capability of providing two-dimensional dosimetric information. As such, EBT3 films could also be conveniently used to check the uniformity of the alpha-particle source.

  8. Identification of gene-based responses in human blood cells exposed to alpha particle radiation

    PubMed Central

    2014-01-01

    Background The threat of a terrorist-precipitated nuclear event places humans at danger for radiological exposures. Isotopes which emit alpha (α)-particle radiation pose the highest risk. Currently, gene expression signatures are being developed for radiation biodosimetry and triage with respect to ionizing photon radiation. This study was designed to determine if similar gene expression profiles are obtained after exposures involving α-particles. Methods Peripheral blood mononuclear cells (PBMCs) were used to identify sensitive and robust gene-based biomarkers of α-particle radiation exposure. Cells were isolated from healthy individuals and were irradiated at doses ranging from 0-1.5 Gy. Microarray technology was employed to identify transcripts that were differentially expressed relative to unirradiated cells 24 hours post-exposure. Statistical analysis identified modulated genes at each of the individual doses. Results Twenty-nine genes were common to all doses with expression levels ranging from 2-10 fold relative to control treatment group. This subset of genes was further assessed in independent complete white blood cell (WBC) populations exposed to either α-particles or X-rays using quantitative real-time PCR. This 29 gene panel was responsive in the α-particle exposed WBCs and was shown to exhibit differential fold-changes compared to X-irradiated cells, though no α-particle specific transcripts were identified. Conclusion Current gene panels for photon radiation may also be applicable for use in α-particle radiation biodosimetry. PMID:25017500

  9. Collision efficiency factor of bubble and particle (alpha bp) in DAF: theory and experimental verification.

    PubMed

    Han, M; Kim, W; Dockko, S

    2001-01-01

    The collision efficiency factor of bubble and particle (alpha bp) in dissolved air flotation (DAF) can be calculated theoretically by trajectory analysis, which takes into account both hydrodynamics and interparticle forces. To determine the theoretically optimum particle size for any given bubble size, a collision efficiency diagram for DAF was developed where collision efficiency is contoured on a plane of particle and bubble sizes for different conditions of particle zeta potential. A set of experiments tested the validity of the suggested collision efficiency diagram, and examined whether pretreatment is important and why slight coagulant overdosing and shorter flocculation times are generally preferred in DAF, both current accepted practice. Batch DAF reactors were used and kaolin samples were prepared from jar tests using different alum dosages and flocculation times. The particle size distribution, particle zeta potential, and turbidity removal in each experiment were measured, as were bubble size and zeta potential. The results agreed well with the predictions of the collision efficiency diagram and explained current practices. A collision efficiency diagram identifies the pretreatment goal, i.e., tailoring of the optimum characteristics required of particles (zeta potential and size) under existing operational bubble characteristic.

  10. CHARGE-EXCHANGE LIMITS ON LOW-ENERGY {alpha}-PARTICLE FLUXES IN SOLAR FLARES

    SciTech Connect

    Hudson, H. S.; Fletcher, L.; MacKinnon, A. L.; Woods, T. N.

    2012-06-20

    This paper reports on a search for flare emission via charge-exchange radiation in the wings of the Ly{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 on board the Solar Dynamics Observatory 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{sup -1}. We study 10 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 particles. The absence of charge-exchange line wings may point to a need for more complete theoretical work. Some of the events do have broadband signatures, which could correspond to continua from other origins, but these do not have the spectral signatures expected from the Orrall-Zirker mechanism.

  11. Quantitative autoradiography of alpha particle emission in geo-materials using the Beaver™ system

    NASA Astrophysics Data System (ADS)

    Sardini, Paul; Angileri, Axel; Descostes, Michael; Duval, Samuel; Oger, Tugdual; Patrier, Patricia; Rividi, Nicolas; Siitari-Kauppi, Marja; Toubon, Hervé; Donnard, Jérôme

    2016-10-01

    In rocks or artificial geo-materials, radioactive isotopes emitting alpha particles are dispersed according to the mineralogy. At hand specimen scale, the achievement of quantitative chemical mapping of these isotopes takes on a specific importance. Knowledge of the distribution of the uranium and thorium series radionuclides is of prime interest to several disciplines, from the geochemistry of uranium deposits, to the dispersion of uranium mill tailings in the biosphere. The disequilibrium of these disintegration chains is also commonly used for dating. However, some prime importance isotopes, such as 226Ra, are complicated to localize in geo-materials. Because of its high specific activity, 226Ra is found in very low concentrations ( ppq), preventing its accurate localization in rock forming minerals. This paper formulates a quantitative answer to the following question: at hand specimen scale, how can alpha emitters in geo-materials be mapped quantitatively? In this study, we tested a new digital autoradiographic method (called the Beaver™) based on a Micro Patterned Gaseous Detector (MPGD) in order to quantitatively map alpha emission at the centimeter scale rock section. Firstly, for two thin sections containing U-bearing minerals at secular equilibrium, we compared the experimental and theoretical alpha count rates, measured by the Beaver™ and calculated from the uranium content, respectively. We found that they are very similar. Secondly, for a set of eight homemade standards made up of a mixture of inactive sand and low-radioactivity mud, we compared the count rates obtained by the Beaver™ and by an alpha spectrometer. The results indicate (i) a linearity between both count rates, and (ii) that the count obtained by the Beaver™ can be estimated from the count obtained by the alpha spectrometry using a factor of 0.82.

  12. Electron Microscopy Study of Stainless Steel Radiation Damage Due to Long-Term Irradation by Alpha Particles Emitted From Plutonium

    SciTech Connect

    Unlu, Kenan; Rios-Martinez, Carlos; Saglam, Mehmet; Hart, Ron R.; Shipp, John D.; Rennie, John

    1998-04-16

    Radiation damage and associated surface and microstructural changes produced in stainless steel encapsulation by high-fluence alpha particle irradiations from weapons-grade plutonium of 316-stainless steel are being investigated.

  13. Time and Temperature Dependent Surface Stiffness of Poly(alpha-methylstyrene)(PAMS) through Particle Embedment

    NASA Astrophysics Data System (ADS)

    Karim, Taskin; McKenna, Gregory

    2012-02-01

    In the present work, we have used the particle embedment technique with sub-micron particles to study the time dependence surface modulus of poly(alpha-methylstyrene)(PAMS) at different temperature ranging from room temperature to 1.1Tg of PAMS. The surface was found softer at room temperature and at 1.02Tg compared to the bulk film while at 1.1Tg the surface was found stiffer compared to the macroscopic modulus measured for the same PAMS. The embedment of the particle is determined from atomic force microscope measurements and the modulus was determined using the elastic analysis of Johnson, Kendall and Roberts (JKR) with surface energy estimates of the work of adhesion as the driving force for embedment. REFERENCES 1. K. L. Johnson, K. Kendall and A. D. Roberts, P. Royal Society of Lonodon A, 324, 301-313 (1971). 2. J. H. Teichroeb and J. A. Forrest, Physical Review Letter, 91, 016104 (2003).

  14. Induction of a bystander mutagenic effect of alpha particles in mammalian cells

    NASA Technical Reports Server (NTRS)

    Zhou, H.; Randers-Pehrson, G.; Waldren, C. A.; Vannais, D.; Hall, E. J.; Hei, T. K.; Chatterjee, A. (Principal Investigator)

    2000-01-01

    Ever since the discovery of X-rays was made by Rontgen more than a hundred years ago, it has always been accepted that the deleterious effects of ionizing radiation such as mutation and carcinogenesis are attributable mainly to direct damage to DNA. Although evidence based on microdosimetric estimation in support of a bystander effect appears to be consistent, direct proof of such extranuclear/extracellular effects are limited. Using a precision charged particle microbeam, we show here that irradiation of 20% of randomly selected A(L) cells with 20 alpha particles each results in a mutant fraction that is 3-fold higher than expected, assuming no bystander modulation effect. Furthermore, analysis by multiplex PCR shows that the types of mutants induced are significantly different from those of spontaneous origin. Pretreatment of cells with the radical scavenger DMSO had no effect on the mutagenic incidence. In contrast, cells pretreated with a 40 microM dose of lindane, which inhibits cell-cell communication, significantly decreased the mutant yield. The doses of DMSO and lindane used in these experiments are nontoxic and nonmutagenic. We further examined the mutagenic yield when 5-10% of randomly selected cells were irradiated with 20 alpha particles each. Results showed, likewise, a higher mutant yield than expected assuming no bystander effects. Our studies provide clear evidence that irradiated cells can induce a bystander mutagenic response in neighboring cells not directly traversed by alpha particles and that cell-cell communication process play a critical role in mediating the bystander phenomenon.

  15. SILICON DIODE AS AN ALPHA PARTICLE DETECTOR AND SPECTROMETER FOR DIRECT FIELD MEASUREMENTS.

    PubMed

    Ören, Ünal; Nilsson, Jonas; Herrnsdorf, Lars; Rääf, Christopher L; Mattsson, Sören

    2016-09-01

    A windowless silicon (Si) diode (4 mm(2)) was evaluated as alpha particle detector and spectrometer for field measurements. It was irradiated with alpha particles from a (241)Am (2.3 kBq) and a (210)Po (9 kBq) source at source-detector distances (SDD) of 0.5, 1.0 and 1.8 cm. The energy resolution in terms of full width at half maximum was 281, 148 and 113 keV for SDD of 0.5, 1.0 and 1.8 cm, respectively. The minimum detectable activity increased from 0.08 to 0.83 Bq when the SDD increased from 0.5 to 1.8 cm. The detector has the potential for several alpha spectrometric applications, such as monitoring for wound, skin and surface contamination at nuclear fuel facilities, nuclear power plants and facilities handling radioactive waste. Other areas are environmental surveys following releases of actinides at accidents in nuclear power plants and in connection with other radiological or nuclear scenarios.

  16. Experimental detection of alpha-particles from the radioactive decay of natural bismuth.

    PubMed

    de Marcillac, Pierre; Coron, Noël; Dambier, Gérard; Leblanc, Jacques; Moalic, Jean-Pierre

    2003-04-24

    The only naturally occurring isotope of bismuth, 209Bi, is commonly regarded as the heaviest stable isotope. But like most other heavy nuclei abundant in nature and characterized by an exceptionally long lifetime, it is metastable with respect to alpha-decay. However, the decay usually evades observation because the nuclear structure of 209Bi gives rise to an extremely low decay probability and, moreover, generates low-energy alpha-particles difficult to detect. Indeed, dedicated experiments attempting to record the alpha-decay of 209Bi in nuclear emulsions failed. However, scintillating bolometers operated at temperatures below 100 mK offer improved detection efficiency and sensitivity, whereas a broad palette of targets could be available. Here we report the successful use of this method for the unambiguous detection of 209Bi alpha-decay in bismuth germanate detectors cooled to 20 mK. We measure an energy release of 3,137 +/- 1 (statistical) +/- 2 (systematic) keV and a half-life of (1.9 +/- 0.2) x 10(19) yr, which are in agreement with expected values.

  17. Is delayed genomic instability specifically induced by high-LET particles?

    NASA Astrophysics Data System (ADS)

    Testard, Isabelle; Sabatier, Laure

    1998-12-01

    Ionizing radiation can induce a large variety of damages in the DNA. The processing or repair of this damage occurs in the first minutes up to several hours after irradiation. Afterwhile the remaining lesions are fixed in an irreparable state. However, in recent years, data have accumulated to suggest that genomic instability can manifest in the progeny of irradiated cells leading to accumulation of damage through cell generations. Different biological endpoints were described: delayed cell death, delayed mutations, de novo chromosomal instability. The question regarding the ability of sparsely ionizing X-or γ-rays to induce such phenomenon is still unclear for normal cells. In most of the reports, high linear energy transfer (LET) particles are able to induce genomic instability but not low-LET particles. The mechanisms underlying this phenomenon are still unknown. In human fibroblasts irradiated by heavy ions in a large range of LETs, we showed that the chromosomal instability is characterized by telomeric associations (TAS) involving specific chromosomes. The same instability is observed during the senescence process and during the first passages after viral transfection. The specific chromosomal instability that we observed after irradiation would not be a direct consequence of irradiation but would be a natural phenomenon occurring after many cell divisions. The effect of the irradiation would lie on the bypass of the senescence process that would permit cells with end to end fusions to survive and be transmitted through cell generations, accumulating chromosome rearrangements and chromosome imbalances. Research on molecular mechanisms of chromosomal instability is focused on the role of telomeres in end to end fusions. Such observations could contribute to understand why chromosomal instability is not a dose dependant phenomenon. Why high-LET particles would be so potent in inducing delayed instability? The answer might lie in the study of primary effects of

  18. Crosschecking of alpha particle monitor reactions up to 50 MeV

    NASA Astrophysics Data System (ADS)

    Takács, S.; Ditrói, F.; Szűcs, Z.; Haba, H.; Komori, Y.; Aikawa, M.; Saito, M.

    2017-04-01

    Selected reactions with well-defined excitation functions can be used to monitor the parameters of charged particle beams. The frequently used reactions for monitoring alpha particle beams are the 27Al(α,x)22,24Na, natTi(α,x)51Cr, natCu(α,x)66,67Ga and natCu(α,x)65Zn reactions. The excitation functions for these reactions were studied using the activation method and stacked target irradiation technique to crosscheck and to compare the above six reactions. Thin metallic foils with natural isotopic composition and well defined thickness were stacked together in sandwich targets and were irradiated at the AVF cyclotron of RIKEN with an alpha particle beam of 51.2 MeV. The activity of the target foils were assessed by using high-resolution gamma spectrometers of high purity Ge detectors. The data sets of the six processes were crosschecked with each other to provide consistent, cross-linked numerical cross section data.

  19. Optical Model Potentials for {alpha}-Particles Scattering around the Coulomb Barrier on Medium-Mass Nuclei

    SciTech Connect

    Avrigeanu, M.; Roman, F.L.; Avrigeanu, V.

    2005-05-24

    Following a semi-microscopic and phenomenological analyses of {alpha}-particle elastic scattering on A{approx}100 nuclei at energies below 32 MeV, a regional optical potential is involved in (n,{alpha}) reaction cross-sections analysis for the stable Mo isotopes. Focus on the uncertainties in the OMP parameters found to describe the {alpha}-particle emission from excited compound residual nuclei is thus obtained, looking for understanding of the related questions on the basis of microscopic models.

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

    SciTech Connect

    Bourouaine, Sofiane; Marsch, Eckart; Neubauer, Fritz M.

    2011-02-10

    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, T{sub {alpha}}/T{sub p} , anti-correlates with the helium ion abundance. Despite a relatively high collisional age and small wave power, the ratio T{sub {alpha}}/T{sub p} 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 T{sub {alpha}} {approx_equal} T{sub p} . This is a hint that the local wave heating process is acting on a timescale shorter than the collision time.

  1. Evaluate an impact of incident alpha particle and gamma ray on human blood components: A comparison study

    SciTech Connect

    Ismail, Asaad H.; Yaba, Sardar P.; Ismail, Haider J.

    2015-07-01

    An impact of alpha and gamma irradiation on human blood components have been evaluated and compared for healthy blood samples (male and females). Irradiation dose and time of irradiation calibrated and considered as a main comparison factors. Density of blood components measured for each in vitro irradiation before and after irradiation for males and females. Survey radiation dosimeter (Inspector Exp) and nuclear track detectors type CR-39 used to evaluate exposure dose rate and incident density of alpha particles, respectively. Experiment results verified that the irradiation of blood makes ionizing of blood components, either alpha or gamma irradiation dose, and the impacts of ionizing radiation were relativity for WBC, RBC, and PLT. Limited irradiation doses of 1-5 μSv/hr considered as a low radiation dose of alpha and gamma radiation sources ({sup 226}Ra, and {sup 137}Cs). Density of alpha particles accumulated on the blood surface was 34 (alpha particle/cm{sup 2}) for selected dose of incident alpha particle. Optimum value of irradiation dose and time of irradiation were 5 μSv/hr and 4 second for males and females. On the other hands, the values of irradiation dose and time of irradiation were 2.1 μSv/hr and 2 second for males and females for gamma irradiation. Thus, present results demonstrated that densities of RBC and WBC cells are capable of inducing reproduction in vitro for both type of irradiation. (authors)

  2. Differential Velocity between Solar Wind Protons and Alpha Particles in Pressure Balance Structures

    NASA Technical Reports Server (NTRS)

    Yamauchi, Yohei; Suess, Steven T.; Steinberg, John T.; Sakurai, Takashi

    2004-01-01

    Pressure balance structures (PBSs) are a common high-plasma beta feature in high-latitude, high-speed solar wind. They have been proposed as remnants of coronal plumes. If true, they should reflect the observation that plumes are rooted in unipolar magnetic flux concentrations in the photosphere and are heated as oppositely directed flux is advected into and reconnects with the flux concentration. A minimum variance analysis (MVA) of magnetic discontinuities in PBSs showed there is a larger proportion of tangential discontinuities than in the surrounding high-speed wind, supporting the hypothesis that plasmoids or extended current sheets are formed during reconnection at the base of plumes. To further evaluate the character of magnetic field discontinuities in PBSs, differential streaming between alpha particles and protons is analyzed here for the same sample of PBSs used in the MVA. Alpha particles in high-speed wind generally have a higher radial flow speed than protons. However, if the magnetic field is folded back on itself, as in a large-amplitude Alfven wave, alpha particles will locally have a radial flow speed less than protons. This characteristic is used here to distinguish between folded back magnetic fields (which would contain rotational discontinuities) and tangential discontinuities using Ulysses high-latitude, high-speed solar wind data. The analysis indicates that almost all reversals in the radial magnetic field in PBSs are folded back field lines. This is found to also be true outside PBSs, supporting existing results for typical high-speed, high-latitude wind. There remains a small number of cases that appear not to be folds in the magnetic field and which may be flux tubes with both ends rooted in the Sun. The distinct difference in MVA results inside and outside PBSs remains unexplained.

  3. Irradiation of Mesenchymal Stromal Cells with Low and High Doses of Alpha Particles Induces Senescence and/or Apoptosis.

    PubMed

    Alessio, Nicola; Esposito, Giuseppe; Galano, Giovanni; De Rosa, Roberto; Anello, Pasquale; Peluso, Gianfranco; Tabocchini, Maria Antonella; Galderisi, Umberto

    2017-03-02

    The use of high-linear energy transfer charged particles is gaining attention as a medical tool because of the emission of radiations with an efficient cell-killing ability. Considerable interest has developed in the use of targeted alpha-particle therapy for the treatment of micrometastases. Moreover, the use of helium beams is gaining momentum, especially for treating pediatric tumors. We analyzed the effects of alpha particles on bone marrow mesenchymal stromal cells (MSCs), which have a subpopulation of stem cells capable of generating adipocytes, chondrocytes, and osteocytes. Further, these cells contribute toward maintenance of homeostasis in the body. MSCs were irradiated with low and high doses of alpha particles or X-rays and a comparative biological analysis was performed. At a low dose (40 mGy), alpha particles exhibited a limited negative effect on the biology of MSCs compared with X-rays. No significant perturbation of cell cycle was observed, and a minimal increase in apoptosis or senescence was detected. Self-renewal was preserved as revealed by the CFU assay. On the contrary, with 2000 mGy alpha particles we observed adverse effects on the vitality, functionality, and stemness of MSCs. These results are the consequence of different proportion of cells targeted by alpha particles or X-rays and the quality of induced DNA damage. The present study suggests that radiotherapy with alpha particles may spare healthy stem cells more efficaciously than X-ray treatments, an observation that should be taken into consideration by physicians while planning irradiation of tumor areas close to stem cell niches, such as bone marrow. This article is protected by copyright. All rights reserved.

  4. Chemistry of Rocks and Soils in Gusev Crater from the Alpha Particle X-ray Spectrometer

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  6. Anomalous effect of trench-oxide depth on alpha-particle-induced charge collection

    SciTech Connect

    Shin, H.; Kim, N.M.

    1999-06-01

    The effect of trench-oxide depth on the alpha-particle-induced charge collection is analyzed for the first time. From the simulation results, it was found that the depth of trench oxide has a considerable influence on the amount of collected charge. The confining of generated charge by the trench oxide was identified as a cause of this anomalous effect. Therefore, the tradeoff between soft error rate and cell to cell isolation characteristics should be considered in optimizing the depth of trench oxide.

  7. Generation of volatile organic compounds by alpha particle degradation of WIPP plastic and rubber material

    SciTech Connect

    Reed, D.T.; Molecke, M.A.

    1993-12-31

    The generation of volatile organic compounds (VOCs), hydrogen, and carbon oxides due to alpha particle irradiation of polyethylene, polyvinylchloride, hypalon, and neoprene, is being investigated. A wide diversity of VOCs was found including alkenes, alkanes, alcohols, ketones, benzene derivatives, and nitro compounds. Their yields however, were quite low. The relative amounts of these compounds depended on the material, atmosphere present, and the absorbed dose. This investigation will help evaluate the effect of ionizing radiation on the long-term performance assessment and regulatory compliance issues related to the Waste Isolation Pilot Plant (WIPP).

  8. Photon hormesis deactivates alpha-particle induced bystander effects between zebrafish embryos

    NASA Astrophysics Data System (ADS)

    Ng, C. Y. P.; Cheng, S. H.; Yu, K. N.

    2017-04-01

    In the present work, we studied the effects of low-dose X-ray photons on the alpha-particle induced bystander effects between embryos of the zebrafish, Danio rerio. The effects on the naive whole embryos were studied through quantification of apoptotic signals (amounts of cells undergoing apoptosis) at 24 h post fertilization (hpf) using vital dye acridine orange staining, followed by counting the stained cells under a fluorescent microscope. We report data showing that embryos at 5 hpf subjected to a 4.4 mGy alpha-particle irradiation could release a stress signal into the medium, which could induce bystander effect in partnered naive embryos sharing the same medium. We also report that the bystander effect was deactivated when the irradiated embryos were subjected to a concomitant irradiation of 10 or 14 mGy of X-rays, but no such deactivation was achieved if the concomitant X-ray dose dropped to 2.5 or 5 mGy. In the present study, the significant drop in the amount of apoptotic signals on the embryos having received 4.4 mGy alpha particles together X-rays irradiation from 2.5 or 5 mGy to 10 or 14 mGy, together with the deactivation of RIBE with concomitant irradiation of 10 or 14 mGy of X-rays supported the participation of photon hormesis with an onset dose between 5 and 10 mGy, which might lead to removal of aberrant cells through early apoptosis or induction of high-fidelity DNA repair. As we found that photons and alpha particles could have opposite biological effects when these were simultaneously irradiated onto living organisms, these ionizing radiations could be viewed as two different environmental stressors, and the resultant effects could be regarded as multiple stressor effects. The present work presented the first study on a multiple stressor effect which occurred on bystander organisms. In other words, this was a non-targeted multiple stressor effect. The photon hormesis could also explain some failed attempts to observe neutron-induced bystander

  9. Current-drive by lower hybrid waves in the presence of energetic alpha-particles

    SciTech Connect

    Fisch, N.J.; Rax, J.M.

    1991-10-01

    Many experiments have now proved the effectiveness of lower hybrid waves for driving toroidal current in tokamaks. The use of these waves, however, to provide all the current in a reactor is thought to be uncertain because the waves may not penetrate the center of the more energetic reactor plasma, and, if they did, the wave power may be absorbed by alpha particles rather than by electrons. This paper explores the conditions under which lower-hybrid waves might actually drive all the current. 26 refs.

  10. The instrumental blank of the Mars Science Laboratory alpha particle X-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Campbell, J. L.

    2012-10-01

    The alpha particle X-ray spectrometers on the Mars exploration rovers Spirit and Opportunity accomplished extensive elemental analysis of the Martian surface through a combination of XRF and PIXE. An advanced APXS is now part of the Mars Science Laboratory's Curiosity rover. APXS spectra contain contributions which enhance elemental peak areas but which do not arise from these elements within the sample under study, thereby introducing error into derived concentrations. A detailed examination of these effects in the MSL APXS enables us to test two schemes for making the necessary corrections.

  11. Chemistry of rocks and soils in Gusev Crater from the alpha particle x-ray spectrometer.

    PubMed

    Gellert, R; Rieder, R; Anderson, R C; Brückner, J; Clark, B C; Dreibus, G; Economou, T; Klingelhöfer, G; Lugmair, G W; Ming, D W; Squyres, S W; D'Uston, C; Wänke, H; Yen, A; Zipfel, J

    2004-08-06

    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.

  12. Chemistry of rocks and soils at Meridiani Planum from the Alpha Particle X-ray Spectrometer.

    PubMed

    Rieder, R; Gellert, R; Anderson, R C; Brückner, J; Clark, B C; Dreibus, G; Economou, T; Klingelhöfer, G; Lugmair, G W; Ming, D W; Squyres, S W; d'Uston, C; Wänke, H; Yen, A; Zipfel, J

    2004-12-03

    The Alpha Particle X-ray Spectrometer on the Opportunity rover determined major and minor elements of soils and rocks in Meridiani Planum. Chemical compositions differentiate between basaltic rocks, evaporite-rich rocks, basaltic soils, and hematite-rich soils. Although soils are compositionally similar to those at previous landing sites, differences in iron and some minor element concentrations signify the addition of local components. Rocky outcrops are rich in sulfur and variably enriched in bromine relative to chlorine. The interaction with water in the past is indicated by the chemical features in rocks and soils at this site.

  13. Quenching factor for alpha particles in ZnSe scintillating bolometers

    NASA Astrophysics Data System (ADS)

    Nagorny, S.; Cardani, L.; Casali, N.; Dafinei, I.; Pagnanini, L.; Pattavina, L.; Pirro, S.; Schaeffner, K.

    2017-02-01

    In the framework of the CUPID-0 experiment, a numbers of ZnSe single crystals were produced and subjected to different thermal treatments, and later tested as cryogenic scintillating bolometers. We have found that a specific thermal treatment (24 hours under argon atmosphere at 900 °C) has a strong impact on some properties of ZnSe crystals (amplitude of signal, light yield, specific resistivity) and most interestingly, changes the quenching factor for alpha particles from values > 1 to values < 1. Thus such thermal treatment opens the possibility to modify this experimental parameter for a various applications.

  14. Alpha particles are extremely damaging to developing hemopoiesis compared to gamma irradiation

    SciTech Connect

    Tie-Nan Jiang ); Lord, B.I.; Hendry, J.H. )

    1994-03-01

    Estimates of risk of stochastic effects from contamination with [alpha]-particle-emitting radionuclides are based on equivalent doses which take into account the RBE of the high-LET radiation. It is assumed that the RBEs for deterministic effects are considerably less than those for stochastic effects. However, the offspring of mice injected with 30 Bq g[sup [minus]1] [sup 239]Pu at 13 days gestation develop a persistent deficit in hemopoietic stem cells which is primarily the result of damage to their regulatory microenvironment. Their spatial distribution in the marrow is also perturbed, and recent observations on those mice suggested a considerably higher factor than 20. To define a more realistic RBE for hemopoiesis, the effects of external [gamma] irradiation during the fetal development period have been compared directly with those of [sup 239]Pu incorporated via placental transfer on the development of hemopoietic tissue. Pregnant mice were irradiated with [sup 60]Co [gamma] rays (a) continuously from day 13 of gestation to birth at 0.15 or 0.6 Gy/day; (b) six repeated acute doses (0.6 Gy/min) at 0.1 or 0.3 Gy from day 13 of gestation; (c) one acute dose of 0.6 or 1.8 Gy on day 15 of gestation. The spatial distribution of hemopoietic stem cells in 8-week-old offspring was then determined and compared to that resulting from [alpha]-particle irradiation. In each case, the higher dose was required to match the results for [alpha] particles, suggesting an RBE for developing hemopoiesis of 250-360 compared to a continuous [gamma]-ray dose and a rather lower value of 130-180 compared to a single acute dose of [gamma] rays. This contrasts greatly to values for direct irradiation of the stem cells but argues that the effective RBE, measured for long-term effects in vivo, is the more realistic. It is concluded that an all-embracing factor can be grossly misleading and can greatly underestimate the risks of exposure to [alpha] particles. 21 refs., 3 figs., 1 tab.

  15. The comparative effects of gamma radiation and in situ alpha particles on five strong-base anion exchange resins

    SciTech Connect

    Marsh, S.F.

    1991-01-01

    The effects of external gamma radiation and in situ alpha particles were measured on a recently available, macroporous, strong-base polyvinylpyridine resin and on four strong-base polystyrene anion exchange resins. Each resin was irradiated in 7 M nitric acid to 1--10 megaGray of gamma radiation from external {sup 60}Co, or to 5--14 megaGray of alpha particles from sorbed {sup 238}Pu. Each irradiated resin was measured for changes in dry weight, wet volume, weak-base and strong-base chloride exchange capacities, and exchange capacities for Pu(4) from nitric acid. Alpha-induced resin damage was significantly less than that caused by an equivalent dose of gamma radiation. The polyvinylpyridine resin offers the greatest resistance to damage from gamma radiation and from alpha particles. 5 refs., 1 figs. 5 tabs.

  16. Salivary Alpha Amylase and Cortisol Levels in Children with Global Developmental Delay and Their Relation with the Expectation of Dental Care and Behavior during the Intervention

    ERIC Educational Resources Information Center

    dos Santos, Marcio Jose Possari; Bernabe, Daniel Galera; Nakamune, Ana Claudia de Melo Stevanato; Perri, Silvia Helena Venturoli; de Aguiar, Sandra Maria Herondina Coelho Avila; de Oliveira, Sandra Helena Penha

    2012-01-01

    The purpose of this study was to analyze the alpha-amylase (sAA) and cortisol levels in children with Global developmental delay (GDD) before and after dental treatment and its association with the children's behavior during treatment. The morning salivary cortisol levels and activity of sAA of 33 children with GDD were evaluated before and after…

  17. Delayed diagnosis of alpha-1-antitrypsin deficiency following post-hepatectomy liver failure: A case report

    PubMed Central

    Norton, Benjamin; Denson, Jemimah; Briggs, Christopher; Bowles, Matthew; Stell, David; Aroori, Somaiah

    2016-01-01

    Post-hepatectomy liver failure (PHLF) is a leading cause of morbidity and mortality following major liver resection. The development of PHLF is dependent on the volume of the remaining liver tissue and hepatocyte function. Without effective pre-operative assessment, patients with undiagnosed liver disease could be at increased risk of PHLF. We report a case of a 60-year-old male patient with PHLF secondary to undiagnosed alpha-1-antitrypsin deficiency (AATD) following major liver resection. He initially presented with acute large bowel obstruction secondary to a colorectal adenocarcinoma, which had metastasized to the liver. There was no significant past medical history apart from mild chronic obstructive pulmonary disease. After colonic surgery and liver directed neo-adjuvant chemotherapy, he underwent a laparoscopic partially extended right hepatectomy and radio-frequency ablation. Post-operatively he developed PHLF. The cause of PHLF remained unknown, prompting re-analysis of the histology, which showed evidence of AATD. He subsequently developed progressive liver dysfunction, portal hypertension, and eventually an extensive parastomal bleed, which led to his death; this was ultimately due to a combination of AATD and chemotherapy. This case highlights that formal testing for AATD in all patients with a known history of chronic obstructive pulmonary disease, heavy smoking, or strong family history could help prevent the development of PHLF in patients undergoing major liver resection. PMID:27004008

  18. β-particle energy-summing correction for β-delayed proton emission measurements

    NASA Astrophysics Data System (ADS)

    Meisel, Z.; del Santo, M.; Crawford, H. L.; Cyburt, R. H.; Grinyer, G. F.; Langer, C.; Montes, F.; Schatz, H.; Smith, K.

    2017-02-01

    A common approach to studying β-delayed proton emission is to measure the energy of the emitted proton and corresponding nuclear recoil in a double-sided silicon-strip detector (DSSD) after implanting the β-delayed proton-emitting (βp) nucleus. However, in order to extract the proton-decay energy, the measured energy must be corrected for the additional energy implanted in the DSSD by the β-particle emitted from the βp nucleus, an effect referred to here as β-summing. We present an approach to determine an accurate correction for β-summing. Our method relies on the determination of the mean implantation depth of the βp nucleus within the DSSD by analyzing the shape of the total (proton + recoil + β) decay energy distribution shape. We validate this approach with other mean implantation depth measurement techniques that take advantage of energy deposition within DSSDs upstream and downstream of the implantation DSSD.

  19. THE ROLE OF ALPHA PARTICLES IN THE EVOLUTION OF THE SOLAR-WIND TURBULENCE TOWARD SHORT SPATIAL SCALES

    SciTech Connect

    Perrone, D.; Valentini, F.; Veltri, P.

    2011-11-01

    We present a numerical study of the kinetic dynamics of protons and alpha particles during the evolution of the solar-wind turbulent cascade, in which the energy injected in large-scale slab-type Alfvenic fluctuations is transferred toward short spatial scale lengths, across the proton skin depth. We make use of a hybrid Vlasov-Maxwell code that integrates numerically the Vlasov equation for both the ion species, while the electrons are considered as a fluid. The system evolution is investigated in terms of different values of the electron to proton and alpha particle to proton temperature ratios. The numerical results show that the previously studied kinetic dynamics of protons is not strongly affected by the presence of alpha particles, at least when they are present in low concentration. Our simulations not only provide a physical explanation for the generation of beams of accelerated particles along the direction of the ambient magnetic field for both protons and alpha particles, but also show that this mechanism is more efficient for protons than for alpha particles, in agreement with recent solar-wind data analyses.

  20. Measurement of ion cascade energies through resolution degradation of alpha particle microcalorimeters

    SciTech Connect

    Horansky, Robert D.; Stiehl, Gregory M.; Beall, James A.; Irwin, Kent D.; Ullom, Joel N.; Plionis, Alexander A.; Rabin, Michael W.

    2010-02-15

    Atomic cascades caused by ions impinging on bulk materials have remained of interest to the scientific community since their discovery by Goldstein in 1902. While considerable effort has been spent describing and, more recently, simulating these cascades, tools that can study individual events are lacking and several aspects of cascade behavior remain poorly known. These aspects include the material energies that determine cascade magnitude and the variation between cascades produced by monoenergetic ions. We have recently developed an alpha particle detector with a thermodynamic resolution near 100 eV full-width-at-half-maximum (FWHM) and an achieved resolution of 1.06 keV FWHM for 5.3 MeV particles. The detector relies on the absorption of particles by a bulk material and a thermal change in a superconducting thermometer. The achieved resolution of this detector provides the highest resolving power of any energy dispersive technique and a factor of 8 improvement over semiconductor detectors. The exquisite resolution can be directly applied to improved measurements of fundamental nuclear decays and nuclear forensics. In addition, we propose that the discrepancy between the thermodynamic and achieved resolution is due to fluctuations in lattice damage caused by ion-induced cascades in the absorber. Hence, this new detector is capable of measuring the kinetic energy converted to lattice damage in individual atomic cascades. This capability allows new measurements of cascade dynamics; for example, we find that the ubiquitous modeling program, SRIM, significantly underestimates the lattice damage caused in bulk tin by 5.3 MeV alpha particles.

  1. Results of the Alpha-Particle-X-Ray Spectrometer on Board of the Mars Exploration Rovers

    NASA Technical Reports Server (NTRS)

    Geller, R.; Zipfel, J.; Brueckner, J.; Dreibus, G.; Lugmair, G.; Rieder, R.; Waenke, H.; Klingelhoefer, G.; Clark, B. C.; Ming, D. W.

    2005-01-01

    The Mars Exploration Rovers Spirit and Opportunity landed at Gusev crater and Meridiani Planum. The Alpha Particle X-ray Spectrometer (APXS) is part of the instrument suite on both rovers. It is equipped with six 244Cm sources which provide x-ray excitation with alpha-particles (PIXE) and x-ray radiation (XRF). This combination allows x-ray spectroscopy of elements from Na to Br in the energy range of 0.9 to 16 keV. X-ray detectors with a high energy resolution of 160 eV at Fe K allow us to separate even closely spaced energy peaks, such as Na, Mg, Al and Si. The APXS is attached to the rover s arm and provides in-situ measurements of the chemical composition of soils, surfaces of rocks and outcrops and their abraded surfaces. This abstract gives an overview of APXS results obtained during the first year of operation on both landing sites.

  2. Observation of lunar radon emanation with the Apollo 15 alpha particle spectrometer.

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.; Bjorkholm, P.

    1972-01-01

    The alpha particle spectrometer, a component of the orbital Sim Bay group of 'geochemistry' experiments on Apollo 15, was designed to detect alpha particles emitted during the decay of isotopes of radon gas and her daughter products. The purpose was to measure the gross activity of radon on the lunar surface and to find possible regions of increased local activity. Results are presented from a partial analysis of Apollo 15 data. For the moon as a whole, Rn220 was not observed and the upper limit on its decay rate above the lunar surface is 0.00038 disintegrations/sq cm-sec. Rn222 was marginally observed. Possible variations of radon activity on the lunar surface are being investigated. Po210 (a daughter product of Rn222) has been detected in a broad region from west of Mare Crisium to the Van de Graaff-Orlov region. The observed count rate is (4.6 plus or minus 1.4) x 0.001 disintegrations/sq cm-sec. The observed level of Po210 activity is in excess of the amount that would be in equilibrium with Rn222 by about an order of magnitude. This implies that larger levels of radon emanation have occurred on the moon within a time scale of 10 to 100 years.

  3. Plutonium-catalyzed oxidative DNA damage in the absence of significant alpha-particle decay

    SciTech Connect

    Claycamp, H.G.; Luo, D.

    1994-01-01

    Plutonium is considered to be a carcinogen because it emits {alpha} particles that may result in the irradiation of stem cell population. In the present study we show that plutonium can also catalyze reactions that induce hydroxyl radicals in the absence of significant {alpha}-particle irradiation. Using the low specific activity isotope, {sup 242}Pu, experiments were performed under conditions in which chemical generation of hydroxyl radicals was expected to exceed the radiolytic generation by 10{sup 5}-fold. The results showed that markers of oxidative DNA base damage, thymine glycol and 8-oxoguanine could be induced from plutonium-catalyzed reactions of hydrogen peroxide and ascorbate similarly to those occurring in the presence of iron catalysts. Plutonium-242, as a neutralized nitrate in phosphate buffer, was 4.8-fold more efficient than iron at catalyzing the oxidation of ascorbate at pH 7. The results suggest that plutonium complexes could participate in reactions at pH 7 that induce oxidative stress - a significant tumor-promoting factor in generally accepted models of carcinogenesis. 16 refs., 3 figs.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. An improved electrostatic integrating radon monitor with the CR-39 as alpha-particle detector.

    PubMed

    Fan, D; Zhuo, W; Chen, B; Zhao, C; Yi, Y; Zhang, Y

    2015-11-01

    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.

  6. Activation cross sections of longer-lived radionuclides produced in germanium by alpha particle irradiation

    NASA Astrophysics Data System (ADS)

    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.

  7. Assessing the SEU resistance of CMOS latches using alpha-particle sensitive test circuits

    NASA Technical Reports Server (NTRS)

    Buehler, M.; Blaes, B.; Nixon, R.

    1990-01-01

    The importance of Cosmic Rays on the performance of integrated circuits (IC's) in a space environment is evident in the upset rate of the Tracking and Data Relay Satellite (TDRS) launched in Apr. 1983. This satellite experiences a single-event-upset (SEU) per day which must be corrected from the ground. Such experience caused a redesign of the Galileo spacecraft with SEU resistant IC's. The solution to the SEU problem continues to be important as the complexity of spacecraft grows, the feature size of IC's decreases, and as space systems are designed with circuits fabricated at non-radiation hardened foundries. This paper describes an approach for verifying the susceptibility of CMOS latches to heavy-ion induced state changes. The approach utilizes alpha particles to induce the upsets in test circuits. These test circuits are standard cells that have offset voltages which sensitize the circuits to upsets. These results are then used to calculate the upsetability at operating voltages. In this study results are presented for the alpha particle upset of a six-transistor static random access memory (SRAM) cell. Then a methodology is described for the analysis of a standard-cell inverter latch.

  8. Calibration of the Mars Science Laboratory Alpha Particle X-Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Perrett, G. M.; Campbell, J. L.; Gellert, R.; King, P. L.; Maxwell, J. A.; Andrushenko, S. M.

    2011-12-01

    We have used a suite of over 60 geochemical reference standards for the calibration of the Mars Science Laboratory (MSL) Alpha Particle X-ray Spectrometer (APXS). For the elements P, S, Cl and Br we have supplemented this suite by adding various amounts of relevant chemical compounds to a powdered basalt standard. Special attention has been paid to include phyllosilicates, sulphates and a broad selection of igneous basalts as these are predicted key deposits at the MSL landing site, Gale Crater. The calibration is performed from first principles using x-ray excitation cross sections for the alpha particle and x-ray radiation source and an assumed homogeneous sample matrix. Remaining deviations indicate significant influences of mineral phases especially for light elements in basalts, ultra-mafic rocks and trachytes. Supporting x-ray diffraction work has helped to derive empirical, iterative corrections for distinct rock types, based on the first APXS analysis, assuming a homogeneous sample. These corrections have the potential to significantly improve the accuracy of APXS analyses, especially when other MSL instrument results, such as x-ray diffraction data from ChemMin, are included in the overall analysis process.

  9. Selective Alpha-Particle Mediated Depletion of Tumor Vasculature with Vascular Normalization

    PubMed Central

    Seshan, Surya V.; Kappel, Barry J.; Chattopadhyay, Debjit; May, Chad; McDevitt, Michael R.; Nolan, Daniel; Mittal, Vivek; Benezra, Robert; Scheinberg, David A.

    2007-01-01

    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. PMID:17342201

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Brief (<1 sec) delays to particle activation, and their influence on deposition patterns in the respiratory system

    NASA Astrophysics Data System (ADS)

    Ruehl, C. R.; Kleeman, M. J.; Chuang, P. Y.; Nenes, A.

    2010-12-01

    Recent field measurements have demonstrated that some ambient particles can act as cloud condensation nuclei (CCN) when exposed to water vapor supersaturations only after delays on the order of several seconds. It is therefore plausible that other CCN experience even shorter delays (i.e. one second or less) before activation. Such brief delays could prevent activation in two situations: in cases when maximum supersaturation in an updraft is brief, which might be expected in a polluted cloud, and in the human respiratory system, in which supersaturation can occur during inhalation. The latter situation is relevant because such a delay could allow particles to penetrate more deeply into the lungs and thus may enhance any health effects associated with the particles. We modified a lung deposition model to account for particle hygroscopicity to determine the size and composition ranges of particles that might have their deposition patterns affected by such delays. We also made measurements of the CCN activity of particles sampled in Davis, CA, during July 2010 at a site approximately one km from interstate 80. We used a continuous-flow thermal gradient chamber that had been modified to produce high supersaturations for approximately one second or less, and compared the concentration of CCN produced during a “slow” (~1 s) exposure and a “fast” (<0.5 sec) exposure. [CCN]fast was equal to 850 +/- 850 cm-3, while [CCN]slow was 1610 +/- 1190 cm-3, suggesting that approximately half of ambient CCN experience brief delays to activation. The [CCN]fast:[CCN]slow ratio ranged from approximately 0.2 to 1, with lower values typically in the morning and higher values in the late afternoon/evening. The [CCN]fast:[CCN]slow ratio for ammonium sulfate calibration aerosol was 1.10 +/- 0.30. Analysis of the diameter distributions of the resulting droplets supports the hypothesis that variation in this ratio is due to brief kinetic delays. We use these inferred delays in our lung

  12. Adsorption of barium and calcium chloride onto negatively charged alpha-Fe(2)O(3) particles.

    PubMed

    Pochard, Isabelle; Denoyel, Renaud; Couchot, Pierre; Foissy, Alain

    2002-11-01

    Adsorption of cations (Na(+), Ca(2+), Ba(2+)) onto negatively charged (pH 10.4) hematite (alpha-Fe(2)O(3)) particles has been studied. The oxide material was carefully prepared in order to obtain monodisperse suspensions of well-crystallized, quasi-spherical particles (50 nm in diameter). The isoelectric point (IEP) is located at pH 8.5. Adsorption of barium ions onto oxide particles was carried out and the electrophoretic mobility was measured throughout the adsorption experiment. Comparison with calcium adsorption at full coverage reveals a higher uptake of Ba(2+). In both cases it shows also that chloride ions coadsorb with M(2) ions. Simultaneous uptake of the positive and negative ions explains why the electrophoretic mobility does not reverse to cationic migration. A theoretical study of the surface speciation has been carried out, using the MuSiC model. It reveals the presence of negative as well as positive sites on both sides of the point of zero charge (PZC) of the hematite particles, which may explain the coadsorption of Ba(2+) and Cl(-) at pH 10.4. The effective charge of the oxide particles, calculated from the electrophoretic mobility, is in very good agreement with the results found with the MuSiC modelization and the chloride/barium adsorption ratio. It also verifies the theory of ionic condensation. Calorimetric measurements gave a negative heat for the overall reaction occurring when Ba(2+)/Cl(-) ions adsorb onto hematite. Despite the fact that anions (Cl(-) and OH(-)) adsorption onto mineral oxides is an exothermic phenomenon, it is likely that barium and calcium adsorption is endothermic, denoting the formation of an inner-sphere complex as reported in the literature.

  13. Transcriptional and Secretomic Profiling of Epidermal Cells Exposed to Alpha Particle Radiation

    PubMed Central

    Chauhan, Vinita; Howland, Matthew; Greene, Hillary Boulay; Wilkins, Ruth C

    2012-01-01

    Alpha (α)-particle emitters are probable isotopes to be used in a terrorist attack. The development of biological assessment tools to identify those who have handled these difficult to detect materials would be an asset to our current forensic capacity. In this study, for the purposes of biomarker discovery, human keratinocytes were exposed to α-particle and X-radiation (0.98 Gy/h at 0, 0.5, 1.0, 1.5 Gy) and assessed for differential gene and protein expression using microarray and Bio-Plex technology, respectively. Secretomic analysis of supernatants showed expression of two pro-inflammatory cytokines (IL-13 and PDGF-bb) to be exclusively affected in α-particle exposed cells. The highest dose of α-particle radiation modulated a total of 67 transcripts (fold change>|1.5|, (False discovery rate) FDR<0.05) in exposed cells. Several genes which responded with high expression levels (>2 fold) included KIF20A, NEFM, C7orf10, HIST1H2BD, BMP6, and HIST1H2AC. Among the high expressing genes, five (CCNB2, BUB1, NEK2, CDC20, AURKA) were also differentially expressed at the medium (1.0 Gy) dose however, these genes were unmodulated following exposure to X-irradiation. Networks of these genes clustered around tumor protein-53 and transforming growth factor-beta signaling. This study has identified some potential gene /protein responses and networks that may be validated further to confirm their specificity and potential to be signature biomarkers of α-particle exposure. PMID:23002402

  14. Vascular-targeted radioimmunotherapy with the alpha-particle emitter 211At.

    PubMed

    Kennel, S J; Mirzadeh, S; Eckelman, W C; Waldmann, T A; Garmestani, K; Yordanov, A T; Stabin, M G; Brechbiel, M W

    2002-06-01

    Astatine-211, an alpha-particle emitter, was employed in a model system for vascular-targeted radioimmunotherapy of small tumors in mouse lung to compare its performance relative to other radioisotopes in the same system. Astatine-211 was coupled to the lung blood vessel-targeting monoclonal antibody 201B with N-succinimidyl N-(4-[211At]astatophenethyl) succinamate linker. Biodistribution data showed that the conjugate delivered 211At to the lung (260-418% ID/g), where it remained with a biological half-time of about 30 h. BALB/c mice bearing about 100 lung tumor colonies of EMT-6 cells, each about 2000 cells in size, were treated with 211At-labeled monoclonal antibody 201B. The administered activity of 185 kBq per animal extended the life span of treated mice over untreated controls. Injections of 370 kBq, corresponding to an absorbed dose of 25-40 Gy, were necessary to eradicate all of the lung tumors. Mice receiving 740 kBq of 211At-labeled monoclonal antibody 201B developed pulmonary fibrosis 3-4 months after treatment, as did mice treated with 3700 kBq of the alpha-particle emitter 213Bi-labeled monoclonal antibody 201B in previous work. Animals that were injected with 211At bound to untargeted IgG or to glycine, as control agents, also demonstrated therapeutic effects relative to untreated controls. Control groups that received untargeted 211At required about twice as much administered activity for effective therapy as did groups with lung-targeted radioisotope. These results were not consistent with radioisotope biodistribution and dosimetry calculations that indicated that lung-targeted 211At should be at least 10-fold more efficient for lung colony therapy than 211At bound to nontargeting controls. The data showed that 211At is useful for vascular-targeted radioimmunotherapy because lung tumor colonies were eradicated in the mice. Work in this model system demonstrates that vascular targeting of alpha-particle emitters is an efficient therapy for small

  15. Feasibility of alpha particle measurement in a magnetically confined plasma by CO/sub 2/ laser Thomson scattering

    SciTech Connect

    Richards, R.K.; Vander Sluis, K.L.; Hutchinson, D.P.

    1987-08-01

    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 CO/sub 2/ laser beam from such a plasma, a resonance in the scattered power occurs near 90/sup 0/ 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.

  16. Bench-level characterization of a CMOS standard-cell D-latch using alpha-particle sensitive test circuits

    NASA Technical Reports Server (NTRS)

    Blaes, B. R.; Soli, G. A.; Buehler, M. G.

    1991-01-01

    A methodology is described for predicting the SEU susceptibility of a standard-cell D-latch using an alpha-particle sensitive SRAM, SPICE critical charge simulation results, and alpha-particle interaction physics. Measurements were made on a 1.6-micron n-well CMOS 4-kb test SRAM irradiated with an Am-241 alpha-particle source. A collection depth of 6.09 micron was determined using these results and TRIM computer code. Using this collection depth and SPICE derived critical charge results on the latch design, an LET threshold of 34 MeV sq cm/mg was predicted. Heavy ion tests were then performed on the latch and an LET threshold of 41 MeV sq cm/mg was determined.

  17. Complementary optical-potential analysis of {alpha}-particle elastic scattering and induced reactions at low energies

    SciTech Connect

    Avrigeanu, M. Obreja, A.C.; Roman, F.L.; Avrigeanu, V.; Oertzen, W. von

    2009-07-15

    A previously derived semi-microscopic analysis based on the Double Folding Model, for {alpha}-particle elastic scattering on A{approx}100 nuclei at energies below 32 MeV, is extended to medium mass A{approx}50-120 nuclei and energies from {approx}13 to 50 MeV. The energy-dependent phenomenological imaginary part for this semi-microscopic optical model potential was obtained including the dispersive correction to the microscopic real potential, and used within a concurrent phenomenological analysis of the same data basis. A regional parameter set for low-energy {alpha}-particles entirely based on elastic scattering data analysis was also obtained for nuclei within the above mentioned mass and energy ranges. Then, an ultimate assessment of ({alpha},{gamma}), ({alpha},n), and ({alpha},p) reaction cross sections considered target nuclei from {sup 45}Sc to {sup 118}Sn and incident energies below {approx}12 MeV. The former diffuseness of the real part of optical potential as well as the surface imaginary potential depth have been found to be responsible for the actual difficulties in the description of these data, and modified in order to obtain an optical potential which describes equally well both the low-energy elastic scattering and induced reaction data for {alpha}-particles.

  18. Study of the absorption coefficient of alpha particles to lower hybrid waves in tokamak

    SciTech Connect

    Wang, Jianbing Zhang, Xianmei Yu, Limin Zhao, Xiang

    2014-02-12

    Part of the energy of the Lower Hybrid (LH) waves may be absorbed by the α particles via the so-called perpendicular landau damping mechanism, which depends on various parameters of fusion reactors and the LH waves. In this article, we calculate the absorption coefficient γ{sub α} of LH waves due to α particles. Results show that, the γ{sub α} increases with the parallel refraction index n{sub ∥} while deceases with increasing the frequency of LH waves ω{sub LH} over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of γ{sub α} when n{sub e}≈8×10{sup 19}m{sup −3} for ITER-like scenario. The thermal corrections to the cold plasma dispersion relation will change the damping rate to a certain extent under some specific conditions. We have also evaluated the fraction of LH power absorbed by the alpha particles, η ≈ 0.47% and 4.1% for an LH frequency of 5 GHz and 3.7 GHz respectively for ITER-like scenario. This work gives the effective reference for the choice of parameters of future fusion reactors.

  19. Characterization of Delayed-Particle Emission Signatures for Pyroprocessing. Part 1: ABTR Fuel Assembly.

    SciTech Connect

    Durkee, Jr., Joe W.

    2015-06-19

    A three-part study is conducted using the MCNP6 Monte Carlo radiation-transport code to calculate delayed-neutron (DN) and delayed-gamma (DG) emission signatures for nondestructive assay (NDA) metal-fuel pyroprocessing. In Part 1, MCNP6 is used to produce irradiation-induced used nuclear fuel (UNF) isotopic inventories for an Argonne National Laboratory (ANL) Advanced Burner Test Reactor (ABTR) preconceptual design fuel assembly (FA) model. The initial fuel inventory consists of uranium mixed with light-water-reactor transuranic (TRU) waste and 10 wt% zirconium (U-LWR-SFTRU-10%Zr). To facilitate understanding, parametric evaluation is done using models for 3% and 5% initial 235U a% enrichments, burnups of 5, 10, 15, 20, 30, …, 120 GWd/MTIHM, and 3-, 5-, 10-, 20-, and 30- year cooling times. Detailed delayed-particle radioisotope source terms for the irradiate FA are created using BAMF-DRT and SOURCES3A. Using simulation tallies, DG activity ratios (DGARs) are developed for 134Cs/137Cs 134Cs/154Eu, and 154Eu/137Cs markers as a function of (1) burnup and (2) actinide mass, including elemental uranium, neptunium, plutonium, americium, and curium. Spectral-integrated DN emission is also tallied. The study reveals a rich assortment of DGAR behavior as a function of DGAR type, enrichment, burnup, and cooling time. Similarly, DN emission plots show variation as a function of burnup and of actinide mass. Sensitivity of DGAR and DN signatures to initial 235U enrichment, burnup, and cooling time is evident. Comparisons of the ABTR radiation signatures and radiation signatures previously reported for a generic Westinghouse oxide-fuel assembly indicate that there are pronounced differences in the ABTR and Westinghouse oxide-fuel DN and DG signatures. These differences are largely attributable to the initial TRU inventory in the ABTR fuel. The actinide and nonactinide inventories for the

  20. Pulse-shape discrimination and energy quenching of alpha particles in Cs2LiLaBr6:Ce3+

    NASA Astrophysics Data System (ADS)

    Mesick, K. E.; Coupland, D. D. S.; Stonehill, L. C.

    2017-01-01

    Cs2LiLaBr6:Ce3+(CLLB) is an elpasolite scintillator that offers excellent linearity and gamma-ray energy resolution and sensitivity to thermal neutrons with the ability to perform pulse-shape discrimination (PSD) to distinguish gammas and neutrons. Our investigation of CLLB has indicated the presence of intrinsic radioactive alpha background that we have determined to be from actinium contamination of the lanthanum component. We measured the pulse shapes for gamma, thermal neutron, and alpha events and determined that PSD can be performed to separate the alpha background with a moderate figure of merit of 0.98. We also measured the electron-equivalent-energy of the alpha particles in CLLB and simulated the intrinsic alpha background from 227Ac to determine the quenching factor of the alphas. A linear quenching relationship Lα =Eα × q +L0 was found at alpha particle energies above 5 MeV, with a quenching factor q = 0.71 MeVee / MeV and an offset L0 = - 1.19 MeVee .

  1. Effect of crystal thickness and geometry on the alpha-particle resolution of CsI (Tl)

    USGS Publications Warehouse

    Martinez, P.; Senftle, F.E.

    1960-01-01

    The resolution of CsI(Tl) for Po210 alpha particles has been measured as a function of crystal thickness. The best resolution of a 12;-in. diam cylindrical crystal was obtained for a thickness of 0.38 mm, and the effect of thickness on the resolution is discussed. Based on the proposed model, a conical crystal was designed, which yielded a line width of 1.8% for Po 210 alpha particles with a selected photomultiplier tube. ?? 1960 The American Institute of Physics.

  2. Traversal of cells by radiation and absorbed fraction estimates for electrons and alpha particles

    SciTech Connect

    Eckerman, K.F.; Ryman, J.C.; Taner, A.C.; Kerr, G.D.

    1985-01-01

    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 -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, 1/2d, 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 refs., 3 figs., 2 tabs.

  3. An alpha particle measurement system using an energetic neutral helium beam in ITER (invited)

    SciTech Connect

    Sasao, M.; Tanaka, N.; Terai, K.; Kaneko, O.; Kisaki, M.; Kobuchi, T.; Tsumori, K.; Okamoto, A.; Kitajima, S.; Shinto, K.; Wada, M.

    2012-02-15

    An energetic helium neutral beam is involved in the beam neutralization measurement system of alpha particles confined in a DT fusion plasma. A full size strong-focusing He{sup +} ion source (2 A, the beam radius of 11.3 mm, the beam energy less than 20 keV). Present strong-focusing He{sup +} ion source shows an emittance diagram separated for each beamlet of multiple apertures without phase space mixing, despite the space charge of a beamlet is asymmetric and the beam flow is non-laminar. The emittance of beamlets in the peripheral region was larger than that of center. The heat load to the plasma electrode was studied to estimate the duty factor for the ITER application.

  4. Characterization of coal and charcoal by alpha-particle and gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Carrasco Lourtau, A. M.; Rubio Montero, M. P.; Jurado Vargas, M.

    2015-11-01

    Although coal and charcoal have similar physical and chemical characteristics, there are several crystallographic procedures used to distinguish and characterize them. But if the matrix is crushed, there is no standard procedure to distinguish coal from charcoal. In this work, a procedure to characterize coal and charcoal samples based on the radioactive content is proposed. The first assay is by gamma-ray spectrometry, which allows a part of the radioactive content to be determined rapidly and non-destructively. Then, alpha-particle spectrometry is applied to assay the content of those radionuclides which are difficult to determine precisely by gamma-ray spectrometry. This second technique requires prior chemical purification of the carbon sample in order to separate the corresponding radionuclides of interest.

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

    SciTech Connect

    Reed, D.T.; Hoh, J.; Emery, J.; Okajima, S.; Krause, T.

    1998-07-01

    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.

  6. An alpha particle experiment for chemical analysis of the Martian surface and atmosphere.

    NASA Technical Reports Server (NTRS)

    Economou, T. E.; Turkevich, A. L.; Patterson, J. H.

    1973-01-01

    An alpha particle experiment similar to the one performed successfully on the Surveyor lunar missions is described. It is designed to provide a chemical analysis of the Martian surface and atmosphere. Analyses of rocks of known and unknown compositions have been made under simulated Martian conditions. The accuracies attained are generally comparable to those of the Surveyor lunar analyses. Improvements have been achieved in determining carbon and oxygen, so that a few per cent of water or carbonates in rocks can be detected. Some aspects of the integration of such an experiment with the spacecraft, a possible mission profile, and some other problems associated with a soft-landing mission to Mars are discussed. The importance of such a chemical analysis experiment in answering current questions about the nature and history of Martian surface material and its suitability for life processes is presented.

  7. [Temperature effect correction for Chang'E-3 alpha particle X-ray spectrometer].

    PubMed

    Wu, Ming-Ye; Wang, Huan-Yu; Peng, Wen-Xi; Zhang, Cheng-Mo; Zhang, Jia-Yu; Cui, Xing-Zhu; Liang, Xiao-Hua; Wang, Jin-Zhou; Yang, Jia-Wei; Fan, Rui-Rui; Liu, Ya-Qing; Dong, Yi-Fan; Wu, Feng; Zhao, Xiao-Yun

    2012-07-01

    Alpha particle X-ray spectrometer (APXS) is one of the payloads of Chang'E-3 lunar rover of China's Lunar Exploration Project. The present paper introduces briefly the components of APXS, how it works and its working environment on the lunar surface. The environmental temperature effect has been studied with simulations and experiments, and the results show that the temperature of the APXS sensor will be varying during the measuring on the lunar surface. And another experiment reveals that the energy resolution becomes worse if the sensor's temperature is varying. In this paper, a correction method based on Pearson's chi-squared test is presented. The method can improve the energy resolution when the sensor's temperature is varying. We have tested the method with the spectra acquired by APXS in the temperature varying period of Temperature Cycling Test, and the results show that the method is efficient and reliable.

  8. Alpha Particle X-Ray Spectrometer (APXS) on-board Chandrayaan-2 rover

    NASA Astrophysics Data System (ADS)

    Shanmugam, M.; Murty, S. V. S.; Acharya, Y. B.; Goyal, S. K.; Patel, Arpit R.; Shah, Bhumi; Hait, A. K.; Patinge, Aditya; Subrahmanyam, D.

    2014-11-01

    Alpha Particle X-ray Spectrometer (APXS) payload configuration for Chandrayaan-2 rover has been completed recently and fabrication of mechanical assembly, PCB layout design and fabrication are in progress. Here we present the design and performance evaluation of various subsystems developed for APXS payload. The low energy threshold of <1 keV and the energy resolution of ∼150 eV at 5.9 keV, for the Silicon Drift Detector (SDD), as measured from the developed APXS electronics is comparable to the standard spectrometers available off-the-shelf. We have also carried out experiments for measuring fluorescent X-ray spectrum from various standard samples from the USGS catalog irradiated by the laboratory X-ray source 241Am with 1 mCi activity. It is shown that intensities of various characteristic X-ray lines are well correlated with the respective elemental concentrations.

  9. [Near infrared distance sensing method for Chang'e-3 alpha particle X-ray spectrometer].

    PubMed

    Liang, Xiao-Hua; Wu, Ming-Ye; Wang, Huan-Yu; Peng, Wen-Xi; Zhang, Cheng-Mo; Cui, Xing-Zhu; Wang, Jin-Zhou; Zhang, Jia-Yu; Yang, Jia-Wei; Fan, Rui-Rui; Gao, Min; Liu, Ya-Qing; Zhang, Fei; Dong, Yi-Fan; Guo, Dong-Ya

    2013-05-01

    Alpha particle X-ray spectrometer (APXS) is one of the payloads of Chang'E-3 lunar rover, the scientific objective of which is in-situ observation and off-line analysis of lunar regolith and rock. Distance measurement is one of the important functions for APXS to perform effective detection on the moon. The present paper will first give a brief introduction to APXS, and then analyze the specific requirements and constraints to realize distance measurement, at last present a new near infrared distance sensing algorithm by using the inflection point of response curve. The theoretical analysis and the experiment results verify the feasibility of this algorithm. Although the theoretical analysis shows that this method is not sensitive to the operating temperature and reflectance of the lunar surface, the solar infrared radiant intensity may make photosensor saturation. The solutions are reducing the gain of device and avoiding direct exposure to sun light.

  10. Etching characteristic studies for the detection of alpha particles in DAM-ADC nuclear track detector

    NASA Astrophysics Data System (ADS)

    El-Samman, H.; Ashry, A. H.; Arafa, W.; Abou-leila, M.; Abdalla, A. M.; Tsuruta, T.

    2014-09-01

    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.

  11. Astatine-211-labeled radiotherapeutics: an emerging approach to targeted alpha-particle radiotherapy.

    PubMed

    Zalutsky, M R; Vaidyanathan, G

    2000-09-01

    Targeted radiotherapy or endoradiotherapy is an appealing approach to cancer treatment because of the potential for delivering curative doses of radiation to tumor while sparing normal tissues. Radionuclides that decay by the emission of alpha-particles such as the heavy halogen astatine-211 (211At) offer the exciting prospect of combining cell-specific molecular targets with radiation having a range in tissue of only a few cell diameters. Herein, the radiobiological advantages of alpha-particle targeted radiotherapy will be reviewed, and the rationale for using 211At for this purpose will be described. The chemistry of astatine is similar to that of iodine; however, there are important differences which make the synthesis and evaluation of 211At-labeled compounds more challenging. Perhaps the most successful approach that has been developed involves the astatodemetallation of tin, silicon or mercury precursors. Astatine-211 labeled agents that have been investigated for targeted radiotherapy include [211At]astatide, 211At- labeled particulates, 211At-labeled naphthoquinone derivatives, 211At-labeled methylene blue, 211At-labeled DNA precursors, meta-[211At]astatobenzylguanidine, 211At-labeled biotin conjugates, 211At-labeled bisphosphonates, and 211At-labeled antibodies and antibody fragments. The status of these 211At-labeled compounds will be discussed in terms of their labeling chemistry, cytotoxicity in cell culture, as well as their tissue distribution and therapeutic efficacy in animal models of human cancers. Finally, an update on the status of the first clinical trial with an 211At-labeled targeted therapeutic, 211At-labeled chimeric anti-tenascin antibody 81C6, will be provided.

  12. Mitigation of radiation nephropathy after internal {alpha}-particle irradiation of kidneys

    SciTech Connect

    Jaggi, Jaspreet Singh; Seshan, Surya V.; McDevitt, Michael R.; Sgouros, George; Hyjek, Elizabeth; Scheinberg, David A. . E-mail: d-scheinberg@ski.mskcc.org

    2006-04-01

    Purpose: Internal irradiation of kidneys as a consequence of radioimmunotherapy, radiation accidents, or nuclear terrorism can result in radiation nephropathy. We attempted to modify pharmacologically, the functional and morphologic changes in mouse kidneys after injection with the actinium ({sup 225}Ac) nanogenerator, an in vivo generator of {alpha}- and {beta}-particle emitting elements. Methods and Materials: The animals were injected with 0.35 {mu}Ci of the {sup 225}Ac nanogenerator, which delivers a dose of 27.6 Gy to the kidneys. Then, they were randomized to receive captopril (angiotensin-converting enzyme inhibitor), L-158,809 (angiotensin II receptor-1 blocker), spironolactone (aldosterone receptor antagonist), or a placebo. Results: Forty weeks after the {sup 225}Ac injection, the placebo-control mice showed a significant increase in blood urea nitrogen (BUN) (87.6 {+-} 6.9 mg/dL), dilated Bowman spaces, and tubulolysis with basement membrane thickening. Captopril treatment accentuated the functional (BUN 119.0 {+-} 4.0 mg/dL; p <0.01 vs. placebo controls) and histopathologic damage. In contrast, L-158,809 offered moderate protection (BUN 66.6 {+-} 3.9 mg/dL; p = 0.02 vs. placebo controls). Spironolactone treatment, however, significantly prevented the development of histopathologic and functional changes (BUN 31.2 {+-} 2.5 mg/dL; p <0.001 vs. placebo controls). Conclusions: Low-dose spironolactone and, to a lesser extent, angiotensin receptor-1 blockade can offer renal protection in a mouse model of internal {alpha}-particle irradiation.

  13. Renal tubulointerstitial changes after internal irradiation with alpha-particle-emitting actinium daughters.

    PubMed

    Jaggi, Jaspreet Singh; Seshan, Surya V; McDevitt, Michael R; LaPerle, Krista; Sgouros, George; Scheinberg, David A

    2005-09-01

    The effect of external gamma irradiation on the kidneys is well described. However, the mechanisms of radiation nephropathy as a consequence of targeted radionuclide therapies are poorly understood. The functional and morphologic changes were studied chronologically (from 10 to 40 wk) in mouse kidneys after injection with an actinium-225 (225Ac) nanogenerator, a molecular-sized, antibody-targeted, in vivo generator of alpha-particle-emitting elements. Renal irradiation from free, radioactive daughters of 225Ac led to time-dependent reduction in renal function manifesting as increase in blood urea nitrogen. The histopathologic changes corresponded with the decline in renal function. Glomerular, tubular, and endothelial cell nuclear pleomorphism and focal tubular cell injury, lysis, and karyorrhexis were observed as early as 10 wk. Progressive thinning of the cortex as a result of widespread tubulolysis, collapsed tubules, glomerular crowding, decrease in glomerular cellularity, interstitial inflammation, and an elevated juxtaglomerular cell count were noted at 20 to 30 wk after treatment. By 35 to 40 wk, regeneration of simplified tubules with tubular atrophy and loss with focal, mild interstitial fibrosis had occurred. A lower juxtaglomerular cell count with focal cytoplasmic vacuolization, suggesting increased degranulation, was also observed in this period. A focal increase in tubular and interstitial cell TGF-beta1 expression starting at 20 wk, peaking at 25 wk, and later declining in intensity with mild increase in the extracellular matrix deposition was noticed. These findings suggest that internally delivered alpha-particle irradiation-induced loss of tubular epithelial cells triggers a chain of adaptive changes that result in progressive renal parenchymal damage accompanied by a loss of renal function. These findings are dissimilar to those seen after gamma or beta irradiation of kidneys.

  14. Radiation risk to low fluences of alpha particles may be greater than we thought.

    PubMed

    Zhou, H; Suzuki, M; Randers-Pehrson, G; Vannais, D; Chen, G; Trosko, J E; Waldren, C A; Hei, T K

    2001-12-04

    Based principally on the cancer incidence found in survivors of the atomic bombs dropped in Hiroshima and Nagasaki, the International Commission on Radiation Protection (ICRP) and the United States National Council on Radiation Protection and Measurements (NCRP) have recommended that estimates of cancer risk for low dose exposure be extrapolated from higher doses by using a linear, no-threshold model. This recommendation is based on the dogma that the DNA of the nucleus is the main target for radiation-induced genotoxicity and, as fewer cells are directly damaged, the deleterious effects of radiation proportionally decline. In this paper, we used a precision microbeam to target an exact fraction (either 100% or < or =20%) of the cells in a confluent population and irradiated their nuclei with exactly one alpha particle each. We found that the frequencies of induced mutations and chromosomal changes in populations where some known fractions of nuclei were hit are consistent with non-hit cells contributing significantly to the response. In fact, irradiation of 10% of a confluent mammalian cell population with a single alpha particle per cell results in a mutant yield similar to that observed when all of the cells in the population are irradiated. This effect was significantly eliminated in cells pretreated with a 1 mM dose of octanol, which inhibits gap junction-mediated intercellular communication, or in cells carrying a dominant negative connexin 43 vector. The data imply that the relevant target for radiation mutagenesis is larger than an individual cell and suggest a need to reconsider the validity of the linear extrapolation in making risk estimates for low dose, high linear-energy-transfer (LET) radiation exposure.

  15. Fabrication, characterization and simulation of 4H-SiC Schottky diode alpha particle detectors for pyroprocessing actinide monitoring

    NASA Astrophysics Data System (ADS)

    Garcia, Timothy Richard

    Pyroprocessing is a method of using high-temperature molten salts and electric fields to separate and collect fuel isotopes of used nuclear fuel. It has been has been tested in the U.S. at Idaho National Laboratory as a key step in closing the nuclear fuel cycle. One technical problem with the pyroprocessing method is a lack of knowledge regarding the actinide concentrations in the salt bath during operation, since on-line techniques for measuring these concentrations are not presently available. 4H-SiC Schottky diode detectors can potentially fulfill this need. Such detectors would operate in contact with the molten salt, and measure concentrations via alpha-particle spectroscopy. This work seeks to fabricate and characterize 4H-SiC Schottky diode detectors at high temperature, model the alpha particle spectrum expected in a molten salt, and model the operation of the detectors to confirm the physics of operation is as expected. In this work, 4H-SiC Schottky diode detectors were fabricated at OSU Nanotech West. After fabrication, these detectors were characterized using both I-V curves and Am-241 alpha-particle energy spectra. All measurements were made as a function of temperature, from room temperature up to 500°C. The average energy required to create an electron-hole pair was observed to decrease with an increase of temperature, due to a decrease of both the 4H-SiC bandgap and non-linear energy loss terms. Furthermore, the FWHM of the spectra was observed to be dependent on the leakage current at a certain temperature, and not dependent on the temperature itself. Secondly, the alpha particle energy spectrum in the pyroprocessing environment was modeled using SRIM. The molten salt was modeled in 3 different geometries, with or without a protective cover material on top of the detector. Due to the loss of alpha-particle energy in the molten salt itself, a high-energy alpha emitter may completely cover the spectrum from a lower-energy alpha emitter. Each of the

  16. Effects of clinically relevant alumina ceramic wear particles on TNF-alpha production by human peripheral blood mononuclear phagocytes.

    PubMed

    Hatton, A; Nevelos, J E; Matthews, J B; Fisher, J; Ingham, E

    2003-03-01

    The recent introduction of microseparation of the components of ceramic-on-ceramic hip prostheses during hip simulations has produced clinically relevant wear rates, wear patterns and wear particles. This provided an opportunity to determine the response of primary human peripheral blood mononuclear cells to clinically relevant alumina ceramic wear particles in vitro. Alumina ceramic wear particles were generated in a hip joint simulator under microseparation conditions. The particles showed a bi-modal size distribution with nanometer sized (5-20nm) and larger particles (0.2->10 micrometer). The particles were cultured with human peripheral blood mononuclear cells obtained from six different donors at particle volume to cell number ratios of 1, 10, 100 and 500 micrometer(3). After 24h incubation the viability of the cells and the levels of TNF-alpha were determined. The response to the microseparation wear particles was compared to that of commercially available alumina powder with a uniform morphology and mean size of 0.5 micrometer. All six Donors PBMNC produced significantly elevated levels of TNF-alpha when stimulated with 100 micrometer(3) of the alumina powder per cell. Volumetric concentrations of 10 and 1.0 micrometer(3) per cell failed to stimulate a significant response by the cells from any of the six donors. Three of the six Donors PBMNC secreted significantly elevated levels of TNF-alpha when stimulated with 100 micrometer(3) of the microseparation wear particles, whereas the other three failed to respond to the wear debris at this concentration. All of the Donors PBMNC produced significantly elevated levels of TNF-alpha when stimulated with 500 micrometer(3) of the microseparation wear particles per cell. Thus, a greater volume of the microseparation wear particles was required to activate the PBMNC than the alumina powder. This was probably due to the microseparation wear particles having fewer particles in the critical size range (0.1-1 micrometer

  17. Potentiation of tumor necrosis factor-induced NF-kappa B activation by deacetylase inhibitors is associated with a delayed cytoplasmic reappearance of I kappa B alpha.

    PubMed

    Adam, Emmanuelle; Quivy, Vincent; Bex, Françoise; Chariot, Alain; Collette, Yves; Vanhulle, Caroline; Schoonbroodt, Sonia; Goffin, Véronique; Nguyên, Thi Liên-Anh; Gloire, Geoffrey; Carrard, Géraldine; Friguet, Bertrand; De Launoit, Yvan; Burny, Arsène; Bours, Vincent; Piette, Jacques; Van Lint, Carine

    2003-09-01

    Previous studies have implicated acetylases and deacetylases in regulating the transcriptional activity of NF-kappa B. Here, we show that inhibitors of deacetylases such as trichostatin A (TSA) and sodium butyrate (NaBut) potentiated TNF-induced expression of several natural NF-kappa B-driven promoters. This transcriptional synergism observed between TNF and TSA (or NaBut) required intact kappa B sites in all promoters tested and was biologically relevant as demonstrated by RNase protection on two instances of endogenous NF-kappa B-regulated gene transcription. Importantly, TSA prolonged both TNF-induced DNA-binding activity and the presence of NF-kappa B in the nucleus. We showed that the p65 subunit of NF-kappa B was acetylated in vivo. However, this acetylation was weak, suggesting that other mechanisms could be implicated in the potentiated binding and transactivation activities of NF-kappa B after TNF plus TSA versus TNF treatment. Western blot and immunofluorescence confocal microscopy experiments revealed a delay in the cytoplasmic reappearance of the I kappa B alpha inhibitor that correlated temporally with the prolonged intranuclear binding and presence of NF-kappa B. This delay was due neither to a defect in I kappa B alpha mRNA production nor to a nuclear retention of I kappa B alpha but was rather due to a persistent proteasome-mediated degradation of I kappa B alpha. A prolongation of I kappa B kinase activity could explain, at least partially, the delayed I kappa B alpha cytoplasmic reappearance observed in presence of TNF plus TSA.

  18. Cytotoxicity of alpha-particle-emitting m-[211At]astatobenzylguanidine on human neuroblastoma cells.

    PubMed

    Strickland, D K; Vaidyanathan, G; Zalutsky, M R

    1994-10-15

    Radioiodinated m-iodobenzylguanidine (MIBG) has been used with only limited success for the treatment of neural crest tumors including neuroblastoma. Use of an MIBG analogue labeled with 211At could be advantageous because of the shorter range and higher linear energy transfer of its alpha-particle emissions compared with the beta-particles emitted by 131I. The potential utility of m-[211At]astatobenzylguanidine for the treatment of neuroblastoma was investigated in vitro using 3 human neuroblastoma cell lines known to take up MIBG [SK-N-SH, SK-N-BE(2C), and SK-SY5Y] and a control line lacking MIBG uptake (SK-N-MC). Maximum binding of m-[211At]astatobenzylguanidine ([211At] MABG) to 5 x 10(5) cells after a 2-h incubation ranged from 61% for SK-N-SH to 1% for SK-N-MC. Using a limiting dilution clonogenic assay, the cytotoxicity for SK-N-SH cells of [211At]MABG was compared with [211At]astatide and no-carrier-added [131I]MIBG. A D0 of 5.8 nCi/ml was calculated for [211At]MABG compared with 482 nCi/ml for [211At] astatide, indicating a more than 80-fold enhanced cytotoxicity for the specifically targeted alpha-particles of [211At]MABG. For [211At]MABG, the D0 corresponded to only 6.4 211At atoms bound/cell compared with 9000 atoms/cell for no-carrier-added [131I]MIBG. The D0 values measured for [211At]MABG treatment of SK-SY5Y, SK-N-BE(2C), and SK-N-MC cells were 50, 5.8, and 11,043 nCi/ml, respectively, corresponding to 7.04, 6.46, and 171.79 211At atoms bound/cell. In conclusion, these results have demonstrated that [211At]MABG is considerably more cytotoxic than [131I]MIBG and that [211At]MABG could have great potential as a radiotherapeutic agent for the treatment of neuroblastoma.

  19. Micronuclei in human peripheral blood lymphocytes exposed to mixed beams of X-rays and alpha particles.

    PubMed

    Staaf, Elina; Brehwens, Karl; Haghdoost, Siamak; Nievaart, Sander; Pachnerova-Brabcova, Katerina; Czub, Joanna; Braziewicz, Janusz; Wojcik, Andrzej

    2012-08-01

    The purpose of this study was to analyse the cytogenetic effect of exposing human peripheral blood lymphocytes (PBL) to a mixed beam of alpha particles and X-rays. Whole blood collected from one donor was exposed to different doses of alpha particles ((241)Am), X-rays and a combination of both. All exposures were carried out at 37 °C. Three independent experiments were performed. Micronuclei (MN) in binucleated PBL were scored as the endpoint. Moreover, the size of MN was measured. The results show that exposure of PBL to a mixed beam of high and low linear energy transfer radiation led to significantly higher than expected frequencies of MN. The measurement of MN size did not reveal any differences between the effect of alpha particles and mixed beam. In conclusion, a combined exposure of PBL to alpha particles and X-rays leads to a synergistic effect as measured by the frequency of MN. From the analysis of MN distributions, we conclude that the increase was due to an impaired repair of X-ray-induced DNA damage.

  20. Lower hybrid instability driven by mono-energy {alpha}-particles with finite pitch angle spread in a plasma

    SciTech Connect

    Kumar, Pawan; Singh, Vishwesh; Tripathi, V. K.

    2013-02-15

    A kinetic formalism of lower hybrid wave instability, driven by mono-energy {alpha}-particles with finite pitch angle spread, is developed. The instability arises through cyclotron resonance interaction with high cyclotron harmonics of {alpha}-particles. The {alpha}-particles produced in D-T fusion reactions have huge Larmor radii ({approx}10 cm) as compared to the wavelength of the lower hybrid wave, whereas their speed is an order of magnitude smaller than the speed of light in vacuum. As a result, large parallel phase velocity lower hybrid waves, suitable for current drive in tokamak, are driven unstable via coupling to high cyclotron harmonics. The growth rate decreases with increase in pitch angle spread of the beam. At typical electron density of {approx}10{sup 19} m{sup -3}, magnetic field {approx}4 Tesla and {alpha}-particle concentration {approx}0.1%, the large parallel phase velocity lower hybrid wave grows on the time scale of 20 ion cyclotron periods. The growth rate decreases with plasma density.

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

    SciTech Connect

    Plionis, Alexander A; Peterson, Dominic S; Tandon, Lav; Lamont, Stephen P

    2009-01-01

    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 nondestructive 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.

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

    SciTech Connect

    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.

  3. EFFECT OF DIFFERENTIAL FLOW OF ALPHA PARTICLES ON PROTON PRESSURE ANISOTROPY INSTABILITIES IN THE SOLAR WIND

    SciTech Connect

    Podesta, John J.; Gary, S. Peter

    2011-11-20

    In the solar wind, when the effects of proton-proton Coulomb collisions are negligible, alpha particles usually flow faster than the protons in such a way that the differential alpha-proton flow velocity V{sub d} = V{sub {alpha}} - V{sub p} is on the order of the Alfven speed, is directed away from the Sun, and is nearly aligned with the local mean magnetic field. When this differential flow is taken into account, solutions of the hot plasma dispersion relation show that for the parallel propagating electromagnetic ion cyclotron (EMIC) instability driven by the proton temperature anisotropy T{sub perpendicularp} > T{sub ||p}, the maximum growth rate occurs in the + V{sub d} direction and for the parallel firehose instability driven by the opposite proton temperature anisotropy T{sub ||p} > T{sub perpendicularp}, the maximum growth rate occurs in the - V{sub d} direction. Thus, the EMIC instability preferentially generates left circularly polarized Alfven-ion-cyclotron waves propagating away from the Sun and the parallel firehose instability preferentially generates right circularly polarized magnetosonic-whistler waves propagating toward the Sun with the maximum growth rates occurring for frequencies on the order of the proton cyclotron frequency and wavenumbers on the order of the proton inertial length. Because of the Doppler shift caused by the motion of the solar wind, both types of waves are left circularly polarized in the spacecraft frame for observations taken when the local mean magnetic field is collinear with the solar wind flow velocity. Theoretical investigation of these instabilities also shows that regions of parameter space exist where the unstable waves are generated propagating unidirectionally such as, for the EMIC instability for example, when the temperature anisotropy is small |(T{sub perpendicular{sub p}}/T{sub ||{sub p}}) - 1| < 1. Taken together, the above properties can explain the origin of parallel propagating electromagnetic waves

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

    NASA Technical Reports Server (NTRS)

    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.

  5. The effects of intense gamma-irradiation on the alpha-particle response of silicon carbide semiconductor radiation detectors

    NASA Astrophysics Data System (ADS)

    Ruddy, Frank H.; Seidel, John G.

    2007-10-01

    Silicon Carbide (SiC) semiconductor radiation detectors are being developed for alpha-particle, X-ray and Gamma-ray, and fast-neutron energy spectrometry. SiC detectors have been operated at temperatures up to 306 °C and have also been found to be highly resistant to the radiation effects of fast-neutron and charged-particle bombardments. In the present work, the alpha-particle response of a SiC detector based on a Schottky diode design has been carefully monitored as a function of 137Cs gamma-ray exposure. The changes in response have been found to be negligible for gamma exposures up to and including 5.4 MGy, and irradiations to higher doses are in progress.

  6. An investigation of alpha-like particles in the DIII-D tokamak using fusion-product diagnostics

    SciTech Connect

    Duong, H.H.

    1993-01-01

    Two important issues associated with alpha physics, the single-particle behavior and the effect of collective fast-ion-driven instabilities on fast-ion confinement, have been studied in the DIII-D tokamak using fusion product diagnostics. The single-particle behavior of alpha-like tritons and [sup 3]He ions produced in deuterium-deuterium fusion reactions is studied using the d(t,n)[alpha] and d([sup 3]he,p)[alpha] fusion reactions. Fusion-produced MeV ions exhibit classical behavior in high field (B[sub T] [ge] 1.0 T) DIII-D discharges, including the new class of [open quotes]very high[close quotes] confinement plasmas. However, discharges with strong sawtooth, fishbone, or TAE activity exhibit anomalous fusion product losses. For the high field discharges without strong MHD activity, the data imply an effective diffusion coefficient smaller than [approximately]0.1 m[sup 2]/s, but in the presence of strong MHD activity, the effective diffusion of the MeV ions exceeds 1.0 m[sup 2]/s. Collective alpha particle processes are simulated by means of neutral beam injected energetic ion minorities. Toroidicity-induced Alfven Eigenmodes (TAE) are observed in DIII-D when energetic beam ions ([approximately]75 keV) are used to destabilize the mode. Measurements of the neutron emission indicate that up to 70% of the injected power is lost during strong TAE activity. Measurements of the poloidal distribution of fast-ion losses suggest that the losses are greatest near the vessel midplane. Fast-ion losses in discharges with combined fishbones and TAE bursts are 1.5 to 2 times greater than losses in fishbone discharges without TAE activity. The scaling of fast ion losses with MHD mode amplitude exhibits no threshold in the mode amplitude, suggesting that mode-particle pumping is the dominant loss mechanism.

  7. Profiling Cesium Iodide Detectors and Using Pulse Shape Discrimination to Identify Alpha Particles, Neutrons, and Gamma Rays

    NASA Astrophysics Data System (ADS)

    Hudson, Emily; Rogachev, Grigory; Hooker, Joshua; Salyer, Kaitlin

    2016-09-01

    The purpose of this research was to investigate the properties of detectors that are to be used in future experiments. First, we investigated the properties of a cesium iodide detector. We placed a mask over the detector's face and used an alpha source to measure the detector's resolution on different areas of the detector. In the second part, we investigated the pulse shape discrimination capabilities of a plastic scintillator. We used the scintillator to detect alpha particles, neutrons, and gamma rays and applied various analysis techniques to identify the waveforms of each type. Texas A&M, NSF.

  8. How delays matter in an oscillatory whole-brain spiking-neuron network model for MEG alpha-rhythms at rest.

    PubMed

    Nakagawa, Tristan T; Woolrich, Mark; Luckhoo, Henry; Joensson, Morten; Mohseni, Hamid; Kringelbach, Morten L; Jirsa, Viktor; Deco, Gustavo

    2014-02-15

    In recent years the study of the intrinsic brain dynamics in a relaxed awake state in the absence of any specific task has gained increasing attention, as spontaneous neural activity has been found to be highly structured at a large scale. This so called resting-state activity has been found to be comprised by nonrandom spatiotemporal patterns and fluctuations, and several Resting-State Networks (RSN) have been found in BOLD-fMRI as well as in MEG signal power envelope correlations. The underlying anatomical connectivity structure between areas of the brain has been identified as being a key to the observed functional network connectivity, but the mechanisms behind this are still underdetermined. Theoretical large-scale brain models for fMRI data have corroborated the importance of the connectome in shaping network dynamics, while the importance of delays and noise differ between studies and depend on the models' specific dynamics. In the current study, we present a spiking neuron network model that is able to produce noisy, distributed alpha-oscillations, matching the power peak in the spectrum of group resting-state MEG recordings. We studied how well the model captured the inter-node correlation structure of the alpha-band power envelopes for different delays between brain areas, and found that the model performs best for propagation delays inside the physiological range (5-10 m/s). Delays also shift the transition from noisy to bursting oscillations to higher global coupling values in the model. Thus, in contrast to the asynchronous fMRI state, delays are important to consider in the presence of oscillation.

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

    SciTech Connect

    McFarlane, Steven; Nicholl, Mary Jane; Sutherland, Jane S.; Preston, Chris M.

    2011-05-25

    The cellular protein hypoxia-inducible factor 1 alpha (HIF-1{alpha}) 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-1{alpha} 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-1{alpha}-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-1{alpha} to occur. HIF-1{alpha} 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.

  10. The Alpha Particle X-Ray Spectrometer (APXS): Results from Gusev Crater and Calibration Report

    NASA Technical Reports Server (NTRS)

    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.

  11. Thorium and actinium polyphosphonate compounds as bone-seeking alpha particle-emitting agents.

    PubMed

    Henriksen, Gjermund; Bruland, Oyvind S; Larsen, Roy H

    2004-01-01

    The present study explores the use of alpha-particle-emitting, bone-seeking agents as candidates for targeted radiotherapy. Actinium and thorium 1,4,7,10 tetraazacyclododecane N,N',N'',N''' 1,4,7,10-tetra(methylene) phosphonic acid (DOTMP) and thorium-diethylene triamine N,N',N'' penta(methylene) phosphonic acid (DTMP) were prepared and their biodistribution evaluated in conventional Balb/C mice at four hours after injection. All three bone-seeking agents showed a high uptake in bone and a low uptake in soft tissues. Among the soft tissue organs, only kidney had a relatively high uptake. The femur/kidney ratios for 227Th-DTMP, 228-Ac-DOTMP and 227Th-DOTMP were 14.2, 7.6 and 6.0, respectively. A higher liver uptake of 228Ac-DOTMP was seen than for 227Th-DTMP and 227Th-DOTMP. This suggests that some demetallation of the 228Ac-DOTMP complex had occurred. The results indicate that 225Ac-DOTMP, 227Th-DOTMP and 227Th-DTMP have promising properties as potential therapeutic bone-seeking agents.

  12. Nanocrystalline particle coatings on alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route.

    PubMed

    Kim, Sang Woo; Jung, Young Mi

    2007-11-01

    We have suggested ultrafine particle coating processes for preparing nanocrystalline particle coated alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route, which is environmentally friendly. The nanometric ammonium aluminum carbonate hydroxide (AACH) as a precursor for coating of alumina was produced from precipitation reaction of ammonium aluminum sulfate and ammonium hydrogen carbonate. The synthetic crystalline size and morphology were greatly dependent on pH and temperature. By adding ammonium aluminum sulfate solution dispersed the alpha-alumina core particle in the ammonium hydrogen carbonate aqueous solution, nanometric AACH with a size of 5 nm was tightly bonded and uniformly coated on the core powder due to formation of surface complexes by the adsorption of carbonates, hydroxyl and ammonia groups on the surface of aluminum oxide. The synthetic precursor rapidly converted to amorphous- and y-alumina phase without significant change in the morphological features through decomposition of surface complexes and thermal-assisted phase transformation. As a result, the nanocrystalline polymorphic particle coated alpha-alumina core powders with highly uniform distribution were prepared from the route of carbonate precipitation and thermal-assisted combustion.

  13. Calculation of the Physical and Microdosimetric Parameters of Electron and Alpha-Particle Radiation Using Monte Carlo Simulations

    NASA Astrophysics Data System (ADS)

    Geng, Jin-Peng; Cao, Tian-Guang; Li, Duo-Fang; An, Hai-Long; Han, Ying-Rong; Li, Jin; Hu, Jin-Shan; Li, Nan-Nan; Zhan, Yong

    2014-03-01

    Various ionizing radiations, such as electrons and alpha particles, transfer their energy to media by produced secondary electrons and induce double- or single-strand break of DNA, which result in variable effects. To understand how the ionizing radiations interact with DNA and break it, several models have been developed, most of them consider the water as a vapor state. Actually, the ionizing particles interact with DNA which is solved in liquid water. To compare the difference of vapor and liquid water models, we calculate the stopping power, continuous slowing down approximation (CSDA) range and S value of electrons and alpha particles at cellular scale in liquid and vapor by Monte Carlo simulations, respectively. Our data show that the stopping power and CSDA range are different in liquid and vapor water in a special energy range. For many S values, the liquid model is better than the vapor model when the energy of the electrons is higher than 100 keV and the vapor model is higher than the liquid model for the 1 MeV alpha particles.

  14. Alpha-thalassemia is associated with a decreased occurrence and a delayed age-at-onset of albuminuria in sickle cell anemia patients.

    PubMed

    Nebor, Danitza; Broquere, Cédric; Brudey, Karine; Mougenel, Danielle; Tarer, Vanessa; Connes, Philippe; Elion, Jacques; Romana, Marc

    2010-08-15

    The aim of this study was to identify possible risk factors for albuminuria, an early marker of sickle cell anemia (SCA) glomerulopathy, in a cohort of 189 SCA adult patients followed at the Sickle Cell Center of Guadeloupe, a French Caribbean island. Biological parameters obtained at baseline, alpha-globin gene status, and beta(S) haplotypes were compared in patients stratified accordingly to graded albuminuria. Abnormal albumin excretion rate was detected in half of the studied adult patients and macroalbuminuria occurred in 21.6%. Graded albuminuria was associated with advanced age (p=0.006), systolic blood pressure (p=0.031), and worsened anemia, i.e. low hemoglobin rate (p<0.0001) and red blood cell count (p<0.0001). Alpha-thalassemia frequency was lower in microalbuminuric and macroalbuminuric patients than in normoalbuminuric patients, 12.5%, 13.75% and 26%, respectively (p=0.0057). Comparison of albuminuria-free survival curves in SCA patients without and with alpha-thalassemia showed that the median time of albuminuria onset was delayed in the later ones (p=0.021). In contrast, no association of albuminuria was detected with the Bantou beta(S) haplotype. Our results strongly suggest a protective effect of alpha-thalassemia against glomerulopathy in SCA adult patients which could be related to a decreased hemolytic rate.

  15. Relationship Between Subjective Preference and the Alpha-Brain Wave in Relation to the Initial Time Delay Gap with Vocal Music

    NASA Astrophysics Data System (ADS)

    MOURI, K.; AKIYAMA, K.; ANDO, Y.

    2000-04-01

    Previously, it was reported that the most preferred initial time delay gap [Δt1]pand subsequent reverberation time are described by the minimum value of the effective duration (τe)minof the running autocorrelation function (ACF) of music signals (2 T=2·0 s) (Y. ANDO et al. 1989 Journal of Acoustical Society of America86, 644-649). This paper shows whether this result is supported or not by use of the electro-physiological method. Experiments were performed for sound fields changing the initial time delay gapΔt1 of a single reflection with vocal music as a source signal, which has large changes in runningτe . The results at the time interval when (τe)minof the music is observed reveal that the scale value of subjective preference is closely related to the value of τeof the alpha wave obtained from the left heimsphere.

  16. The induction of chromosome aberrations in human lymphocytes by in vitro irradiation with alpha-particles from plutonium-239.

    PubMed

    Purrott, R J; Edwards, A A; Lloyd, D C; Stather, J W

    1980-09-01

    The yields of unstable chromosome aberrations induced in human lymphocytes by alpha-particles from plutonium-239 have been measured. Plutonium citrate solution was mixed with heparinized blood so that doses of 13--160 rad were delivered in 24 hours. Dicentric aberration yields (Y) fitted best to the linear expression Y = 3 . 72 +/- 0 . 23 x 10(-3) rad-1. Inclusion of a 6 . 5 rad point resulting from a 1 . 7 hour irradiation raised the yield coefficient insignificantly to 3 . 75 +/- 0 . 24 x 10(-3). The aberration yields are in good agreement with data from curium-242 alpha-particles obtained in this laboratory but they are much lower than those obtained in two other laboratories. Reasons for this disagreement are examined.

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

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Krishnan, Sreejith; Priyanka, B.

    2014-10-01

    The alpha accompanied cold ternary fission of even-even 244Cm, 246Cm, 248Cm, 250Cm and 252Cm isotopes has been studied by taking the interacting barrier as the sum of the 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 the 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 the 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 particles 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 the 4He accompanied ternary fission (equatorial and collinear) of 242-252Cm isotopes are compared with the corresponding yield for binary fission. The effect of deformation and orientation of fragments in the 4He accompanied ternary fission of 244-252Cm isotopes are studied. Our study reveals that the ground state deformation has as an important role in the alpha accompanied ternary fission as that of the shell effect.

  18. Optical Model Potential Parameters for p, d, {sup 3}He and Alpha-Particle Scattering on Lithium Nuclei

    SciTech Connect

    Burtebayev, N.; Nassurlla, Marzhan; Nassurlla, Maulen; Kerimkulov, Zh. K.; Sakuta, S. B.

    2008-11-11

    Analysis of the p, d, {sup 3}He and {alpha}-particles elastic scattering on the {sup 6}Li and {sup 7}Li nuclei has been done in the framework of the optical model at the beam energies up to 72 MeV. It was shown that the account of the cluster exchange mechanism together with the potential scattering allow reproducing the experimental cross-sections in the whole angular range.

  19. Automated Grouping of Opportunity Rover Alpha Particle X-Ray Spectrometer Compositional Data

    NASA Technical Reports Server (NTRS)

    VanBommel, S. J.; Gellert, R.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. W.; Schroder, C.; Yen, A. S.

    2016-01-01

    The Alpha Particle X-ray Spectrometer (APXS) conducts high-precision in situ measurements of rocks and soils on both active NASA Mars rovers. Since 2004 the rover Opportunity has acquired around 440 unique APXS measurements, including a wide variety of compositions, during its 42+ kilometers traverse across several geological formations. Here we discuss an analytical comparison algorithm providing a means to cluster samples due to compositional similarity and the resulting automated classification scheme. Due to the inherent variance of elements in the APXS data set, each element has an associated weight that is inversely proportional to the variance. Thus, the more consistent the abundance of an element in the data set, the more it contributes to the classification. All 16 elements standard to the APXS data set are considered. Careful attention is also given to the errors associated with the composition measured by the APXS - larger uncertainties reduce the weighting of the element accordingly. The comparison of two targets, i and j, generates a similarity score, S(sub ij). This score is immediately comparable to an average ratio across all elements if one assumes standard weighted uncertainty. The algorithm facilitates the classification of APXS targets by chemistry alone - independent of target appearance and geological context which can be added later as a consistency check. For the N targets considered, a N by N hollow matrix, S, is generated where S = S(sup T). The average relation score, S(sub av), for target N(sub i) is simply the average of column i of S. A large S(sub av) is indicative of a unique sample. In such an instance any targets with a low comparison score can be classified alike. The threshold between classes requires careful consideration. Applying the algorithm to recent Marathon Valley targets indicates similarities with Burns formation and average-Mars-like rocks encountered earlier at Endeavour Crater as well as a new class of felsic rocks.

  20. Construction of an Alpha Particle Spark Detector and Fusor for research in plasma physics and radiation detection

    NASA Astrophysics Data System (ADS)

    Akinsulire, Olorunsola; Fils-Aime, Fabrice; Hecla, Jake; Short, Michael; White, Anne

    2016-10-01

    This project delves into the realms of plasma physics and nuclear engineering by exploring systems used to generate plasmas and detect radiation. Basic plasma processes can be explored using inertial electrostatic confinement, in a device commonly called a ``fusor''. The fusor will generate neutrons and x-rays. The breakdown of air within a spark gap can be achieved with alpha particles and the avalanche effect; and constitutes an Alpha Particle Spark Detector (APSD), relevant for studies of basic nuclear processes and detectors. In the fusor, preliminary data was collected on breakdown voltage versus pressure in an air plasma to see how well the current system and geometry match up with expectations for the Paschen curve. A stable plasma was observed, at voltages roughly consistent with expectations, and it was concluded that a more controlled gas introduction system is needed to maintain a steady plasma over wider pressure ranges, and will allow for introduction of D2 gas for the study of neutron and x-ray producing plasmas. This poster will discuss the design, construction, and initial operation of the Alpha Particle Spark Detector and the fusor as part of an Undergraduate Research Opportunity (UROP) project. MIT UROP Program and the NSE department.

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

    NASA Astrophysics Data System (ADS)

    El-Gamal, S.; Abdalla, Ayman M.; Abdel-Hady, E. E.

    2015-09-01

    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.

  2. Development of the MICROMEGAS detector for measuring the energy spectrum of alpha particles by using a 241Am source

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    We have developed MICROMEGAS (MICRO MEsh GASeous) detectors for detecting a particles emitted from an 241Am 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 a particles from the 241Am source can be varied by changing the flight path of the a particle from the 241Am source. The channel numbers of the experimentally-measured pulse peak positions for different energies of the a 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 a particles is done. For the energy calibration, the thickness of the ionization region is adjusted so that a particles may completely stop in the ionization region and their kinetic energies are fully deposited in the region. The efficiency of our MICROMEGAS detector for a particles under the present conditions is found to be ~97.3%.

  3. UCTM2: An updated User friendly Configurable Trigger, scaler and delay Module for nuclear and particle physics

    NASA Astrophysics Data System (ADS)

    Bourrion, O.; Boyer, B.; Derome, L.; Pignol, G.

    2016-06-01

    We developed a highly integrated and versatile electronic module to equip small nuclear physics experiments and lab teaching classes: the User friendly Configurable Trigger, scaler and delay Module for nuclear and particle physics (UCTM). It is configurable through a Graphical User Interface (GUI) and provides a large number of possible trigger conditions without any Hardware Description Language (HDL) required knowledge. This new version significantly enhances the previous capabilities by providing two additional features: signal digitization and time measurements. The design, performances and a typical application are presented.

  4. Initial evaluation of (227)Th-p-benzyl-DOTA-rituximab for low-dose rate alpha-particle radioimmunotherapy.

    PubMed

    Dahle, Jostein; Borrebaek, Jørgen; Melhus, Katrine B; Bruland, Oyvind S; Salberg, Gro; Olsen, Dag Rune; Larsen, Roy H

    2006-02-01

    Radioimmunotherapy has proven clinically effective in patients with non-Hodgkin's lymphoma. Radioimmunotherapy trials have so far been performed with beta-emitting isotopes. In contrast to beta-emitters, the shorter range and high linear energy transfer (LET) of alpha particles allow for more efficient and selective killing of individually targeted tumor cells. However, there are several obstacles to the use of alpha-particle immunotherapy, including problems with chelation chemistry and nontarget tissue toxicity. The alpha-emitting radioimmunoconjugate (227)Th-DOTA-p-benzyl-rituximab is a new potential anti-lymphoma agent that might overcome some of these difficulties. The present study explores the immunoreactivity, in vivo stability and biodistribution, as well as the effect on in vitro cell growth, of this novel radioimmunoconjugate. To evaluate in vivo stability, uptake in balb/c mice of the alpha-particle-emitting nuclide (227)Th alone, the chelated form, (227)Th-p-nitrobenzyl-DOTA and the radioimmunoconjugate (227)Th-DOTA-p-benzyl-rituximab was compared in a range of organs at increasing time points after injection. The immunoreactive fraction of (227)Th-DOTA-p-benzyl-rituximab was 56-65%. During the 28 days after injection of radioimmunoconjugate only, very modest amounts of the (227)Th had detached from DOTA-p-benzyl-rituximab, indicating a relevant stability in vivo. The half-life of (227)Th-DOTA-p-benzyl-rituximab in blood was 7.4 days. Incubation of lymphoma cells with (227)Th-DOTA-p-benzyl-rituximab resulted in a significant antigen-dependent inhibition of cell growth. The data presented here warrant further studies of (227)Th-DOTA-p-benzyl-rituximab.

  5. Cobalt chloride induces delayed cardiac preconditioning in mice through selective activation of HIF-1alpha and AP-1 and iNOS signaling.

    PubMed

    Xi, Lei; Taher, Mohiuddin; Yin, Chang; Salloum, Fadi; Kukreja, Rakesh C

    2004-12-01

    Acute systemic hypoxia induces delayed cardioprotection against ischemia (I)-reperfusion (R) injury via inducible nitric oxide synthase (iNOS)-dependent mechanism. Because CoCl2 is known to elicit hypoxia-like responses, we hypothesized that this chemical would mimic the delayed preconditioning effect in the heart. Adult male mice were pretreated with CoCl2 or saline. The hearts were isolated 24 h later and subjected to 20 min of global I and 30 min of R in Langendorff mode. Myocardial infarct size (% of risk area; mean +/- SE, n=6-8/group) was reduced in mice pretreated with 30 mg/kg CoCl2 (16.1 +/- 3.1% vs. 27.6 +/- 3.3% with saline control; P <0.05) without compromising postischemic cardiac function. Higher doses of CoCl2 failed to induce similar protection. Electrophoretic mobility gel shift assay demonstrated significant enhancement in DNA binding activity of hypoxia-inducible factor 1alpha (HIF-1alpha) and activator protein 1 (AP-1) in nuclear extracts from CoCl2-treated hearts. Activation of HIF-1alpha and AP-1 was evident at 30 min and sustained for the next 4 h after CoCl2 injection. In contrast, CoCl2-induced protection was independent of NF-kappaB activation because no DNA binding or p65 translocation was observed in nuclear extracts. Also, CoCl2-induced cardioprotection was preserved in p50 subunit NF-kappaB-knockout (KO) mice (11.1 +/- 3.0% vs. 25.1 +/- 5.0% in saline-treated p50-KO mice; P <0.05). The infarct-limiting effect of CoCl2 was absent in iNOS-KO mice (20.9 +/- 3.0%). We conclude that in vivo administration of CoCl2 preconditions the heart against I/R injury. The delayed protective effect of CoCl2 is achieved through a distinctive signaling mechanism involving HIF-1alpha, AP-1, and iNOS but independent of NF-kappaB activation.

  6. Effects of the dark energy and flat rotation curve on the gravitational time delay of particle with non-zero mass

    NASA Astrophysics Data System (ADS)

    Sarkar, Tamal; Ghosh, Shubhrangshu; Bhadra, Arunava

    2016-07-01

    The effects of several dark energy models on gravitational time delay of particles with non-zero mass are investigated and analytical expressions for the same are obtained at the first order accuracy. Also the expression for gravitational time delay under the influence of conformal gravity potential that well describes the flat rotation curve of spiral galaxies is derived. The findings suggest that (i) the conformal gravity description of dark matter reduces the net time delay in contrast to the effect of normal dark matter, and therefore in principle the models can be discriminated using gravitational time delay observations, and (ii) the effect of dark energy/flat rotation curve may be revealed from high-precision measurements of gravitational time delay of particles involving the megaparsec and beyond distance scale.

  7. Detection of Special Nuclear Material from Delayed Neutron Emission Induced by a Dual-Particle Monoenergetic Source

    SciTech Connect

    Mayer, Michael F.; Nattress, J.; Jovanovic, I

    2016-06-30

    Detection of unique signatures of special nuclear materials is critical for their interdiction in a variety of nuclear security and nonproliferation scenarios. We report on the observation of delayed neutrons from fission of uranium induced in dual-particle active interrogation based on the 11B(d,n gamma)12C nuclear reaction. Majority of the fissions are attributed to fast fission induced by the incident quasi-monoenergetic neutrons. A Li-doped glass–polymer composite scintillation neutron detector, which displays excellent neutron/γ discrimination at low energies, was used in the measurements, along with a recoil-based liquid scintillation detector. Time- dependent buildup and decay of delayed neutron emission from 238U were measured between the interrogating beam pulses and after the interrogating beam was turned off, respectively. Characteristic buildup and decay time profiles were compared to the common parametrization into six delayed neutron groups, finding a good agreement between the measurement and nuclear data. This method is promising for detecting fissile and fissionable materials in cargo scanning applications and can be readily integrated with transmission radiography using low-energy nuclear reaction sources.

  8. Detection of special nuclear material from delayed neutron emission induced by a dual-particle monoenergetic source

    NASA Astrophysics Data System (ADS)

    Mayer, M.; Nattress, J.; Jovanovic, I.

    2016-06-01

    Detection of unique signatures of special nuclear materials is critical for their interdiction in a variety of nuclear security and nonproliferation scenarios. We report on the observation of delayed neutrons from fission of uranium induced in dual-particle active interrogation based on the 11B(d,n γ)12C nuclear reaction. Majority of the fissions are attributed to fast fission induced by the incident quasi-monoenergetic neutrons. A Li-doped glass-polymer composite scintillation neutron detector, which displays excellent neutron/γ discrimination at low energies, was used in the measurements, along with a recoil-based liquid scintillation detector. Time-dependent buildup and decay of delayed neutron emission from 238U were measured between the interrogating beam pulses and after the interrogating beam was turned off, respectively. Characteristic buildup and decay time profiles were compared to the common parametrization into six delayed neutron groups, finding a good agreement between the measurement and nuclear data. This method is promising for detecting fissile and fissionable materials in cargo scanning applications and can be readily integrated with transmission radiography using low-energy nuclear reaction sources.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27160654

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

    NASA Astrophysics Data System (ADS)

    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. Improve the catalytic activity of {alpha}-Fe{sub 2}O{sub 3} particles in decomposition of ammonium perchlorate by coating amorphous carbon on their surface

    SciTech Connect

    Zhang Yifu; Liu Xinghai; Nie Jiaorong; Yu Lei; Zhong Yalan; Huang Chi

    2011-02-15

    Sphere- and pod-like {alpha}-Fe{sub 2}O{sub 3} particles have been selectively synthesized using NH{sub 3}.H{sub 2}O and NaOH solution to adjust the pH value of the designed synthetic system, respectively. The sphere-like {alpha}-Fe{sub 2}O{sub 3} particles with diameter about 25 nm on average were encapsulated into carbon shells to fabricate a novel core-shell composite ({alpha}-Fe{sub 2}O{sub 3}-C) through the coating experiments. The catalytic performance of the products on the thermal decomposition of ammonium perchlorate (AP) was investigated by thermal gravimetric analyzer (TG) and differential thermal analysis (DTA). The thermal decomposition temperatures of AP in the presence of pod-like {alpha}-Fe{sub 2}O{sub 3}, sphere-like {alpha}-Fe{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3}-C are reduced by 72, 81 and 109 {sup o}C, respectively, which show that {alpha}-Fe{sub 2}O{sub 3}-C core-shell composites have higher catalytic activity than that of {alpha}-Fe{sub 2}O{sub 3}. -- Graphical abstract: The catalytic performance of pod-like {alpha}-Fe{sub 2}O{sub 3}, sphere-like {alpha}-Fe{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3}-C on the thermal decomposition of ammonium perchlorate (AP). Display Omitted Research highlights: {yields} Sphere- and pod-like {alpha}-Fe{sub 2}O{sub 3} particles have been selectively synthesized using NH{sub 3}.H{sub 2}O and NaOH solution to adjust the pH value. {yields} A novel core-shell composite ({alpha}-Fe{sub 2}O{sub 3}-C core-shell structured composite) has been successfully synthesized using sphere-like {alpha}-Fe{sub 2}O{sub 3} particles as the cores and glucose as the source of carbon. {yields} The thermal decomposition temperatures of AP in the presence of pod-like {alpha}-Fe{sub 2}O{sub 3}, sphere-like {alpha}-Fe{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3}-C are reduced by 72, 81 and 109 {sup o}C, respectively, which shows that these materials have high catalytic activity.

  12. Relative toxicity of chronic irradiation by 45Ca beta particles and 242Cm alpha particles with respect to the production of lung tumors in CBA/Ca mice.

    PubMed

    Priest, N D; Hoel, D G; Brooks, P N

    2006-11-01

    Approximately 1800 female CBA/Ca mice were exposed by inhalation at three dose levels to beta particles from (45)Ca-labeled fused aluminosilicate particles (FAP), to alpha particles from (242)Cm-labeled FAP, or to carrier control FAP. Another group of mice inhaled no FAP and were designated as untreated cage controls. The FAP in combination with these radionuclides was used to achieve the same spatial and temporal distribution of alpha- and beta-particle dose within the irradiated mice. Some mice were killed to determine the clearance of radiolabeled FAP from their lungs, and the remainder were allocated to a life-span study. All animals were subjected to a detailed necropsy. To facilitate the identification of small tumors, the lungs were rendered transparent in methyl salicylate and examined under back illumination for the presence of lesions. Lung nodules and other microscopic lesions were excised for histological examination. The median survival of mice in all groups was approximately 910 days. The control animals lived longer than those that were irradiated, but it was difficult to determine a dose-response relationship for survival among the exposed mice. Benign adenomas and, less frequently, malignant adenocarcinomas were identified in all animal groups. The prevalence of these tumors was approximately 28.8% in the control mice, which is consistent with the results of other studies using the same strain of mouse. After exposure to radionuclide-labeled FAP, there was a significant dose-related increase in the prevalence of lung tumors in (242)Cm- (peak prevalence 55%) and (45)Ca-exposed (peak prevalence 48.6%) mice. The prevalence of tumors in the mice that received (242)Cm-labeled FAP was approximately twice that in the mice that inhaled (45)Ca-labeled FAP within the range of doses employed (0.55-4.69 Gy). Using the ratio of the slope of the linear component of the dose-response curves, the toxicity of the alpha particles relative to the beta particles was 1

  13. Bismuth-212-labeled anti-Tac monoclonal antibody: alpha-particle-emitting radionuclides as modalities for radioimmunotherapy

    SciTech Connect

    Kozak, R.W.; Atcher, R.W.; Gansow, O.A.; Friedman, A.M.; Hines, J.J.; Waldmann, T.A.

    1986-01-01

    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.

  14. Induction of mutations by bismuth-212 alpha particles at two genetic loci in human B-lymphoblasts.

    PubMed

    Metting, N F; Palayoor, S T; Macklis, R M; Atcher, R W; Liber, H L; Little, J B

    1992-12-01

    The human lymphoblast cell line TK6 was exposed to the alpha-particle-emitting radon daughter 212Bi by adding DTPA-chelated 212Bi directly to the cell suspension. Cytotoxicity and mutagenicity at two genetic loci were measured, and the molecular nature of mutant clones was studied by Southern blot analysis. Induced mutant fractions were 2.5 x 10(-5)/Gy at the hprt locus and 3.75 x 10(-5)/Gy at the tk locus. Molecular analysis of HPRT- mutant DNAs showed a high frequency (69%) of clones with partial or full deletions of the hprt gene among radiation-induced mutants compared with spontaneous mutants (31%). Chi-squared analyses of mutational spectra show a significant difference (P < or = 0.005) between spontaneous mutants and alpha-particle-induced mutants. Comparison with published studies of accelerator-produced heavy-ion exposures of TK6 cells indicates that the induction of mutations at the hprt locus, and perhaps a subset of mutations at the tk locus, is a simple linear function of particle fluence regardless of the ion species or its LET.

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

    NASA Astrophysics Data System (ADS)

    Shinohara, K.; Kurki-Suonio, T.; Spong, D.; Asunta, O.; Tani, K.; Strumberger, E.; Briguglio, S.; Koskela, T.; Vlad, G.; Günter, S.; Kramer, G.; Putvinski, S.; Hamamatsu, K.; ITPA Topical Group on Energetic Particles

    2011-06-01

    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.

  16. Radioimmunotherapy of breast cancer metastases with alpha-particle emitter 225Ac: comparing efficacy with 213Bi and 90Y.

    PubMed

    Song, Hong; Hobbs, Robert F; Vajravelu, Ravy; Huso, David L; Esaias, Caroline; Apostolidis, Christos; Morgenstern, Alfred; Sgouros, George

    2009-12-01

    alpha-Particles are suitable to treat cancer micrometastases because of their short range and very high linear energy transfer. alpha-Particle emitter (213)Bi-based radioimmunotherapy has shown efficacy in a variety of metastatic animal cancer models, such as breast, ovarian, and prostate cancers. Its clinical implementation, however, is challenging due to the limited supply of (225)Ac, high technical requirement to prepare radioimmunoconjugate with very short half-life (T(1/2) = 45.6 min) on site, and prohibitive cost. In this study, we investigated the efficacy of the alpha-particle emitter (225)Ac, parent of (213)Bi, in a mouse model of breast cancer metastases. A single administration of (225)Ac (400 nCi)-labeled anti-rat HER-2/neu monoclonal antibody (7.16.4) completely eradicated breast cancer lung micrometastases in approximately 67% of HER-2/neu transgenic mice and led to long-term survival of these mice for up to 1 year. Treatment with (225)Ac-7.16.4 is significantly more effective than (213)Bi-7.16.4 (120 microCi; median survival, 61 days; P = 0.001) and (90)Y-7.16.4 (120 microCi; median survival, 50 days; P < 0.001) as well as untreated control (median survival, 41 days; P < 0.0001). Dosimetric analysis showed that (225)Ac-treated metastases received a total dose of 9.6 Gy, significantly higher than 2.0 Gy from (213)Bi and 2.4 Gy from (90)Y. Biodistribution studies revealed that (225)Ac daughters, (221)Fr and (213)Bi, accumulated in kidneys and probably contributed to the long-term renal toxicity observed in surviving mice. These data suggest (225)Ac-labeled anti-HER-2/neu monoclonal antibody could significantly prolong survival in HER-2/neu-positive metastatic breast cancer patients.

  17. Induction of single- and double-strand breaks in plasmid DNA by monoenergetic alpha-particles with energies below the Bragg-maximum.

    PubMed

    Scholz, V; Weidner, J; Köhnlein, W; Frekers, D; Wörtche, H J

    1997-01-01

    The yield of single-strand breaks (ssb) and double-strand breaks (dsb) produced by alpha-particles at the end of their track in DNA-films was determined experimentally. Helium nuclei were accelerated to 600 keV in the 400 kV ion accelerator and scattered at a carbon target. The elastically scattered alpha-particles with energies of 344 keV and 485 keV were used to irradiate supercircular plasmid DNA in vacuo. For the dosimetry of the alpha-particles a surface barrier detector was used and the energy distribution of the alpha-particles determined. The energy loss of the particles in the DNA-layer was calculated. DNA samples were separated into the three conformational isomers using agarose gel electrophoresis. After fluorochromation the number of ssb and dsb per plasmid DNA molecule was established from the band intensities assuming the validity of Poisson statistics. Linear dose effect correlations were found for ssb and dsb per plasmid molecule. In the case of 344 keV-alpha-particles the yield of dsb was (8.6 +/- 0.9) x 10(-11) breaks/Gy x dalton. The ratio of ssb/dsb was 0.5 +/- 0.2. This is at least a factor of six larger than the ratio found in experiments with higher energy alpha-particles and from model calculations. Similar experiments with protons yielded a relative biological effectiveness (rbe) value of 2.8 for the induction of double-strand breaks by track end alpha-particles.

  18. New interpretation of alpha-particle-driven instabilities in deuterium-tritium experiments on the Tokamak Fusion Test Reactor.

    PubMed

    Nazikian, R; Kramer, G J; Cheng, C Z; Gorelenkov, N N; Berk, H L; Sharapov, S E

    2003-09-19

    The original description of alpha particle driven instabilities in the Tokamak Fusion Test Reactor in terms of toroidal Alfvén eigenmodes (TAEs) remained inconsistent with three fundamental characteristics of the observations: (i) the variation of the mode frequency with toroidal mode number, (ii) the chirping of the mode frequency for a given toroidal mode number, and (iii) the antiballooning density perturbation of the modes. It is now shown that these characteristics can be explained by observing that cylindrical-like modes can exist in the weak magnetic shear region of the plasma that then make a transition to TAEs as the central safety factor decreases in time.

  19. 1.5D Quasilinear Model for Alpha Particle-TAE Interaction in ARIES ACT-I

    SciTech Connect

    K. Ghantous, N.N. Gorelenkov, C. Kessel, F. Poli

    2013-01-30

    We study the TAE interaction with alpha particle fusion products in ARIES ACT-I using the 1.5D quasilinear model. 1.5D uses linear analytic expressions for growth and damping rates of TAE modes evaluated using TRANSP pro les to calculates the relaxation of pressure pro les. NOVA- K simulations are conducted to validate the analytic dependancies of the rates, and to normalize their absolute value. The low dimensionality of the model permits calculating loss diagrams in large parameter spaces.

  20. The role of nuclear reactions and {alpha}-particle transport in the dynamics of inertial confinement fusion capsules

    SciTech Connect

    Garnier, Josselin; Cherfils-Clerouin, Catherine

    2008-10-15

    This paper is devoted to the study of the deceleration phase of inertial confinement capsules. The purpose is to obtain a zero-dimensional model that has the form of a closed system of ordinary differential equations for the main hydrodynamic quantities. The model takes into account the energy released by nuclear reactions, a nonlocal model for the {alpha}-particle energy deposition process, and radiation loss by electron bremsstrahlung. The asymptotic analysis is performed in the case of a strong temperature dependence of the thermal conductivity. We finally study the beginning of the expansion phase after stagnation to derive an ignition criterion.

  1. Simulation of the alpha particle heating and the helium ash source in an International Thermonuclear Experimental Reactor-like tokamak with an internal transport barrier

    SciTech Connect

    Ye, Lei Guo, Wenfeng; Xiao, Xiaotao; Dai, Zongliang; Wang, Shaojie

    2014-12-15

    A guiding center orbit following code, which incorporates a set of non-singular coordinates for orbit integration, was developed and applied to investigate the alpha particle heating in an ITER-like tokamak with an internal transport barrier. It is found that a relatively large q (safety factor) value can significantly broaden the alpha heating profile in comparison with the local heating approximation; this broadening is due to the finite orbit width effects; when the orbit width is much smaller than the scale length of the alpha particle source profile, the heating profile agrees with the source profile, otherwise, the heating profile can be significantly broadened. It is also found that the stagnation particles move to the magnetic axis during the slowing-down process, thus the effect of stagnation orbits is not beneficial to the helium ash removal. The source profile of helium ash is broadened in comparison with the alpha source profile, which is similar to the heating profile.

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

    PubMed Central

    Chauhan, Vinita; Howland, Matthew; Wilkins, Ruth

    2012-01-01

    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. PMID:22619631

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

    NASA Technical Reports Server (NTRS)

    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.

  4. A comparitive assessement of cytokine expression in human-derived cell lines exposed to alpha particles and X-rays.

    PubMed

    Chauhan, Vinita; Howland, Matthew; Wilkins, Ruth

    2012-01-01

    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.

  5. Characteristics of neutrons from Be targets bombarded with protons, deuterons and alpha particles

    NASA Astrophysics Data System (ADS)

    Lone, M. A.; Ferguson, A. J.; Robertson, B. C.

    1981-10-01

    Thick-target yields and average energies of neutrons emitted at 0° from bombardment of Be with protons and deuterons at energies below 50 MeV and alphas at energies below 30 MeV are given. The minimum projectile energy and current needed to satisfy the requirements of neutron sources for cancer therapy are discussed.

  6. Experimental investigations of electron capture from atomic hydrogen and deuterium by alpha particles

    SciTech Connect

    Not Available

    1990-01-01

    We have undertaken a program at the University of Missouri-Rolla to experimentally determine cross sections for ion-atom collisions of interest in fusion reactor development. During the last grant period, we have made measurements of total and singly-differential cross sections for the alpha double-capture reaction. He{sup ++} + He(ls{sup 2}) {yields} He({Sigma}n,{ell}) + He{sup ++}. Collisions of this type have been discussed as a basis for diagnostics in which alphas are neutralized in a single collisions either by a HeI beam or by the ablative cloud from mechanically introduced impurity pellets. We are now finishing measurements of cross sections for the alpha single capture reaction He{sup ++} + He(1s{sup 2}) {yields} He{sup +}(n) + He{sup +}(1s), and propose to study He{sup ++} + H(1s) {yields} He{sup +}(n) + H{sup +} during next year. Accurate knowledge of these cross sections is fundamental for modeling of neutral-hydrogen beam penetration in fusion plasmas as well as for spectroscopic diagnostics of alpha densities and velocity distributions, especially for the case of capture into the n = 4 state of the projectile He{sup +}. Our measurements are made using a unique collision spectrometer discussed in this paper.

  7. Pulse-shape discrimination and energy quenching of alpha particles in Cs2LiLaBr6:Ce3+

    SciTech Connect

    Mesick, Katherine Elizabeth; Coupland, Daniel David S.; Stonehill, Laura Catherine

    2016-10-19

    Cs2LiLaBr6:Ce3+ (CLLB) is an elpasolite scintillator that offers excellent linearity and gamma-ray energy resolution and sensitivity to thermal neutrons with the ability to perform pulse-shape discrimination (PSD) to distinguish gammas and neutrons. Our investigation of CLLB has indicated the presence of intrinsic radioactive alpha background that we have determined to be from actinium contamination of the lanthanum component. We measured the pulse shapes for gamma, thermal neutron, and alpha events and determined that PSD can be performed to separate the alpha background with a moderate figure of merit of 0.98. Here, we also measured the electron-equivalent-energy of the alpha particles in CLLB and simulated the intrinsic alpha background from 227Ac to determine the quenching factor of the alphas.

  8. Determination of the area density and composition of alloy film using dual alpha particle energy loss

    NASA Astrophysics Data System (ADS)

    Ma, Xiaojun; Li, Bo; Gao, Dangzhong; Xu, Jiayun; Tang, Yongjian

    2017-02-01

    A novel method based on dual α-particles energy loss (DAEL) is proposed for measuring the area density and composition of binary alloy films. In order to obtain a dual-energy α-particles source, an ingenious design that utilizes the transmitted α-particles traveling the thin film as a new α-particles source is presented. Using the DAEL technique, the area density and composition of Au/Cu film are determined accurately with an uncertainty of better than 10%. Finally, some measures for improving the combined uncertainty are discussed.

  9. Gene amplification and microsatellite instability induced in tumorigenic human bronchial epithelial cells by alpha particles and heavy ions

    NASA Technical Reports Server (NTRS)

    Piao, C. Q.; Hei, T. K.; Hall, E. J. (Principal Investigator)

    2001-01-01

    Gene amplification and microsatellite alteration are useful markers of genomic instability in tumor and transformed cell lines. It has been suggested that genomic instability contributes to the progression of tumorigenesis by accumulating genetic changes. In this study, amplification of the carbamyl-P-synthetase, aspartate transcarbamylase, dihydro-orotase (CAD) gene in transformed and tumorigenic human bronchial epithelial (BEP2D) cells induced by either alpha particles or (56)Fe ions was assessed by measuring resistance to N-(phosphonacetyl)-l-aspartate (PALA). In addition, alterations of microsatellite loci located on chromosomes 3p and 18q were analyzed in a series of primary and secondary tumor cell lines generated in nude mice. The frequency of PALA-resistant colonies was 1-3 x 10(-3) in tumor cell lines, 5-8 x 10(-5) in transformed cells prior to inoculation into nude mice, and less than 10(-7) in control BEP2D cells. Microsatellite alterations were detected in all 11 tumor cell lines examined at the following loci: D18S34, D18S363, D18S877, D3S1038 and D3S1607. No significant difference in either PALA resistance or microsatellite instability was found in tumor cell lines that were induced by alpha particles compared to those induced by (56)Fe ions.

  10. Characterisation of a setup for mixed beam exposures of cells to 241Am alpha particles and X-rays.

    PubMed

    Staaf, Elina; Brehwens, Karl; Haghdoost, Siamak; Pachnerová-Brabcová, Katerina; Czub, Joanna; Braziewicz, Janusz; Nievaart, Sander; Wojcik, Andrzej

    2012-09-01

    Exposure of humans to mixed fields of high- and low-linear energy transfer (LET) radiation occurs in many situations-for example, in urban areas with high levels of indoor radon as well as background gamma radiation, during airplane flights or certain forms of radiation therapy. From the perspective of health risk associated with exposure to mixed fields, it is important to understand the interactions between different radiation types. In most cellular investigations on mixed beams, two types of irradiations have been applied sequentially. Simultaneous irradiation is the desirable scenario but requires a dedicated irradiation facility. The authors have constructed a facility where cells can be simultaneously exposed to (241)Am alpha particles and 190-kV X-rays at 37°C. This study presents the technical details and the dosimetry of the setup, as well as validates the performance of the setup for clonogenic survival in AA8 Chinese hamster ovary cells. No significant synergistic effect was observed. The relative biological effectiveness of the alpha particles was 2.56 for 37 % and 1.90 for 10 % clonogenic survival.

  11. Delayed secondary glucocorticoid response elements. Unusual nucleotide motifs specify glucocorticoid receptor binding to transcribed regions of alpha 2u-globulin DNA.

    PubMed

    Chan, G C; Hess, P; Meenakshi, T; Carlstedt-Duke, J; Gustafsson, J A; Payvar, F

    1991-11-25

    Glucocorticoids stimulate the transcription of rat alpha 2u-globulin (RUG) genes. Because this induction occurs after a time lag of several hours and is blocked by inhibitors of protein synthesis, it exemplifies a delayed secondary response to steroid hormones. In this report, we show that a region of RUG-transcribed DNA (approximately +1800 to +2174) contains multiple footprint sites for glucocorticoid receptor that are, apparently, organized into at least three independent binding clusters. The DNA sequences bound by the receptor and the location of binding sites were determined. A family of sequences related to half-sites of the consensus primary glucocorticoid response element (GRE) is discernible at each cluster of sites. Compared to the consensus GRE, which contains two pseudo-palindromic hexanucleotides arranged in a tail-to-tail fashion and separated by three bases, the arrangements of hexanucleotides within this segment of RUG DNA are unusual and heterogeneous. Methylation interference of a binding cluster containing three receptor footprints demonstrates that certain guanines of the GRE-like hexanucleotides are essential for efficient receptor binding. A synthetic 29-base pair (bp) RUG element, containing one receptor footprint from this cluster, selectively binds the receptor. Within this 29-bp element, six nucleotides separate two directly repeated copies of GRE-like hexanucleotides. RUG DNA fragments containing all or part of the three binding clusters, including the 29-bp element, confer a delayed secondary hormone responsiveness upon a linked heterologous promoter and reporter gene in stably transfected cell lines. We speculate that the unusual DNA sequence motifs of the receptor-binding sites are crucial for the generation of certain delayed secondary responses.

  12. About the effectiveness of spectrometry in alpha-activity monitoring of industrial air-borne particles.

    PubMed

    Domnikov, V N; Saltykov, L S; Slusarenko, L I; Shevchenko, S V

    2001-10-01

    The maximum-likelihood method (MLM) is applied for the analysis of the background compensation problem when using alpha-spectrometry to measure the transuranium radionuclide (TRU) content in thick aerosol samples. It is shown, that the uncertainty of the measurement results has a rather small dependence on the digit capacity of the analog to digital converter (ADC). For the total TRU alpha-activity measurement a 7-bit conversion in the energy range up to 9-10 MeV is sufficient to evaluate the background parameters in the energy region of interest (ROI). Background compensation is also made by subtraction of the estimated total background from the sum of counts measured in the ROI.

  13. Screening materials with the XIA UltraLo alpha particle counter at Southern Methodist University

    SciTech Connect

    Nakib, M. Z.; Cooley, J.; Kara, B.; Qiu, H.; Scorza, S.; Guiseppe, V. E.; Rielage, K.; Schnee, R. W.

    2013-08-08

    Southern Methodist University houses one of five existing commercially available UltraLo 1800 production model alpha counters made by XIA LLC. The instrument has an electron drift chamber with a 707 cm{sup 2} or 1800 cm{sup 2} counting region which is determined by selecting the inner electrode size. The SMU team operating this device is part of the SuperCDMS screening working group, and uses the alpha counter to study the background rates from the decay of radon in materials used to construct the SuperCDMS experiment. We have studied four acrylic samples obtained from the MiniCLEAN direct dark matter search with the XIA instrument demonstrating its utility in low background experiments by investigating the plate-out of {sup 210}Pb and comparing the effectiveness of cleaning procedures in removing {sup 222}Rn progenies from the samples.

  14. Alpha-particle radiotherapy: For large solid tumors diffusion trumps targeting.

    PubMed

    Zhu, Charles; Sempkowski, Michelle; Holleran, Timothy; Linz, Thomas; Bertalan, Thomas; Josefsson, Anders; Bruchertseifer, Frank; Morgenstern, Alfred; Sofou, Stavroula

    2017-06-01

    Diffusion limitations on the penetration of nanocarriers in solid tumors hamper their therapeutic use when labeled with α-particle emitters. This is mostly due to the α-particles' relatively short range (≤100 μm) resulting in partial tumor irradiation and limited killing. To utilize the high therapeutic potential of α-particles against solid tumors, we designed non-targeted, non-internalizing nanometer-sized tunable carriers (pH-tunable liposomes) that are triggered to release, within the slightly acidic tumor interstitium, highly-diffusive forms of the encapsulated α-particle generator Actinium-225 ((225)Ac) resulting in more homogeneous distributions of the α-particle emitters, improving uniformity in tumor irradiation and increasing killing efficacies. On large multicellular spheroids (400 μm-in-diameter), used as surrogates of the avascular areas of solid tumors, interstitially-releasing liposomes resulted in best growth control independent of HER2 expression followed in performance by (a) the HER2-targeting radiolabeled antibody or (b) the non-responsive liposomes. In an orthotopic human HER2-negative mouse model, interstitially-releasing (225)Ac-loaded liposomes resulted in the longest overall and median survival. This study demonstrates the therapeutic potential of a general strategy to bypass the diffusion-limited transport of radionuclide carriers in solid tumors enabling interstitial release from non-internalizing nanocarriers of highly-diffusing and deeper tumor-penetrating molecular forms of α-particle emitters, independent of cell-targeting.

  15. ROLES OF EPIDERMAL GROWTH FACTOR (EGF) AND TRANSFORMING GROWTH FACTOR-ALPHA (TGF-A) IN MEDIATION OF DIOXIN (TCDD)-INDUCED DELAYS IN DEVELOPMENT OF THE MOUSE MAMMARY GLAND

    EPA Science Inventory

    Roles of Epidermal Growth Factor (EGF) and Transforming Growth Factor-alpha (TGF-a) in Mediation of Dioxin (TCDD)-Induced Delays in Development of the Mouse Mammary Gland.
    Suzanne E. Fenton, Barbara Abbott, Lamont Bryant, and Angela Buckalew. U.S. EPA, NHEERL, Reproductive Tox...

  16. Biogenesis of lysosomal enzymes in the alpha-glucosidase II-deficient modA mutant of Dictyostelium discoideum: retention of alpha-1,3-linked glucose on N-linked oligosaccharides delays intracellular transport but does not alter sorting of alpha-mannosidase or beta-glucosidase.

    PubMed

    Ebert, D L; Bush, J M; Dimond, R L; Cardelli, J A

    1989-09-01

    The endoplasmic reticulum-localized enzyme alpha-glucosidase II is responsible for removing the two alpha-1,3-linked glucose residues from N-linked oligosaccharides of glycoproteins. This activity is missing in the modA mutant strain, M31, of Dictyostelium discoideum. Results from both radiolabeled pulse-chase and subcellular fractionation experiments indicate that this deficiency did not prevent intracellular transport and proteolytic processing of the lysosomal enzymes, alpha-mannosidase and beta-glucosidase. However, the rate at which the glucosylated precursors left the rough endoplasmic reticulum was several-fold slower than the rate at which the wild-type precursors left this compartment. Retention of glucose residues did not disrupt the binding of the precursor forms of the enzymes with intracellular membranes, indicating that the delay in movement of proteins from the ER did not result from lack of association with membranes. However, the mutant alpha-mannosidase precursor contained more trypsin-sensitive sites than did the wild-type precursor, suggesting that improper folding of precursor molecules might account for the slow rate of transport to the Golgi complex. Percoll density gradient fractionation of extracts prepared from M31 cells indicated that the proteolytically processed mature forms of alpha-mannosidase and beta-glucosidase were localized to lysosomes. Finally, the mutation in M31 may have other, more dramatic, effects on the lysosomal system since two enzymes, N-acetylglucosaminidase and acid phosphatase, were secreted much less efficiently from lysosomal compartments by the mutant strain.

  17. Redefining relative biological effectiveness in the context of the EQDX formalism: implications for alpha-particle emitter therapy.

    PubMed

    Hobbs, Robert F; Howell, Roger W; Song, Hong; Baechler, Sébastien; Sgouros, George

    2014-01-01

    Alpha-particle radiopharmaceutical therapy (αRPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, αRPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of α-particle emissions, a dosimetric methodology that accurately predicts the thresholds for organ toxicity has not been reported. This is in part due to the fact that the biological effects caused by α-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or β-particle emitting radiopharmaceuticals. The concept of relative biological effectiveness (RBE) is used to quantify the ratio of absorbed doses required to achieve a given biological response with alpha particles versus a reference radiation (typically a beta emitter or external beam radiation). However, as conventionally defined, the RBE varies as a function of absorbed dose and therefore a single RBE value is limited in its utility because it cannot be used to predict response over a wide range of absorbed doses. Therefore, efforts are underway to standardize bioeffect modeling for different fractionation schemes and dose rates for both nuclear medicine and external beam radiotherapy. Given the preponderant use of external beams of radiation compared to nuclear medicine in cancer therapy, the more clinically relevant quantity, the 2 Gy equieffective dose, EQD2(α/β), has recently been proposed by the ICRU. In concert with EQD2(α/β), we introduce a new, redefined RBE quantity, named RBE2(α/β), as the ratio of the two linear coefficients that characterize the α particle absorbed dose-response curve and the low-LET megavoltage photon 2 Gy fraction equieffective dose-response curve. The theoretical framework for the proposed new formalism is presented along with its application to experimental data obtained from

  18. Redefining Relative Biological Effectiveness in the Context of the EQDX Formalism: Implications for Alpha-Particle Emitter Therapy.

    PubMed

    Hobbs, Robert F; Howell, Roger W; Song, Hong; Baechler, Sébastien; Sgouros, George

    2013-12-30

    Alpha-particle radiopharmaceutical therapy (αRPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, αRPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of α-particle emissions, a dosimetric methodology that accurately predicts the thresholds for organ toxicity has not been reported. This is in part due to the fact that the biological effects caused by α-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or β-particle emitting radiopharmaceuticals. The concept of relative biological effectiveness (RBE) is used to quantify the ratio of absorbed doses required to achieve a given biological response with alpha particles versus a reference radiation (typically a beta emitter or external beam radiation). However, as conventionally defined, the RBE varies as a function of absorbed dose and therefore a single RBE value is limited in its utility because it cannot be used to predict response over a wide range of absorbed doses. Therefore, efforts are underway to standardize bioeffect modeling for different fractionation schemes and dose rates for both nuclear medicine and external beam radiotherapy. Given the preponderant use of external beams of radiation compared to nuclear medicine in cancer therapy, the more clinically relevant quantity, the 2 Gy equieffective dose, EQD2(α/β), has recently been proposed by the ICRU. In concert with EQD2(α/β), we introduce a new, redefined RBE quantity, named RBE2(α/β), as the ratio of the two linear coefficients that characterize the α particle absorbed dose-response curve and the low-LET megavoltage photon 2 Gy fraction equieffective dose-response curve. The theoretical framework for the proposed new formalism is presented along with its application to experimental data obtained from

  19. Genomic Profiling of a Human Leukemic Monocytic Cell-Line (THP-1) Exposed to Alpha Particle Radiation

    PubMed Central

    Chauhan, Vinita; Howland, Matthew

    2012-01-01

    This study examined alpha (α-) particle radiation effects on global changes in gene expression in human leukemic monocytic cells (THP-1) for the purposes of mining for candidate biomarkers that could be used for the development of a biological assessment tool. THP-1 cells were exposed to α-particle radiation at a dose range of 0 to 1.5 Gy. Twenty-four hours and three days after exposure gene expression was monitored using microarray technology. A total of 16 genes were dose responsive and classified as early onset due to their expression 24 h after exposure. Forty-eight transcripts were dose responsive and classified as late-onset as they were expressed 72 h after exposure. Among these genes, 6 genes were time and dose responsive and validated further using alternate technology. These transcripts were upregulated and associated with biological processes related to immune function, organelle stability and cell signalling/communication. This panel of genes merits further validation to determine if they are strong candidate biomarkers indicative of α-particle exposure. PMID:23097634

  20. Influence of plasma parameters on the absorption coefficient of alpha particles to lower hybrid waves in tokamaks

    SciTech Connect

    Wang, J.; Zhang, X. Yu, L.; Zhao, X.

    2014-12-15

    In tokamaks, fusion generated α particles may absorb lower hybrid (LH) wave energy, thus reducing the LH current drive efficiency. The absorption coefficient γ{sub α} of LH waves due to α particles changing with some typical parameters is calculated in this paper. Results show that γ{sub α} increases with the parallel refraction index n{sub ‖}, while decreases with the frequency of LH waves ω over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption. The absorption coefficient γ{sub α} increases with n{sub e} when n{sub e} ≤ 8 × 10{sup 19} m{sup −3}, while decreases with n{sub e} when n{sub e} becomes larger, and there is a peak value of γ{sub α} when n{sub e} ≈ 8 × 10{sup 19} m{sup −1} for the ITER-like scenario. The influence of spectral broadening in parametric decay instabilities on the absorption coefficient is evaluated. The value of γ{sub α} with n{sub ‖} being 2.5 is almost two times larger than that with n{sub ‖} being 2.0 and is even lager in the case of 2.9, which will obviously increase the absorption of the LH power by alpha particles.

  1. Novel co-axial prilling technique for the development of core-shell particles as delayed drug delivery systems.

    PubMed

    Del Gaudio, Pasquale; Auriemma, Giulia; Russo, Paola; Mencherini, Teresa; Campiglia, Pietro; Stigliani, Mariateresa; Aquino, Rita Patrizia

    2014-08-01

    In this study, biocompatible double layered beads consisting of pectin core and alginate shell were prepared through a single step manufacturing process based on prilling apparatus equipped with co-axial nozzles. The core was loaded with piroxicam (PRX) as model non-steroidal anti-inflammatory drug (NSAID). Morphology, size distribution and shape of the double layered beads varied depending on the operative conditions and polymer concentrations. Co-axial nozzles size, applied vibration frequency, gelling conditions and, mainly, polymers mass ratio were identified as critical variables. Particularly, the relative viscosity of polymeric feed solutions inside the nozzle was the key parameter to obtain homogeneous and well-formed coated particles. The produced beads were investigated for the release kinetic in different media. Once PRX was encapsulated within the pectin core, a controlled release pattern was observed. Particularly, beads produced with 4:1 core/shell ratio (F4) released less than 30% of PRX in simulated gastric fluid (SGF) while total liberation of the drug was achieved during the next 3h in simulated intestinal fluid (SIF). More interesting, F4 tested in SIF was able to release drug in a delayed and sustained manner at established time points (2h_8.2%, 3h_32.2%, 4h_70.1% and 5h_about 100%). Based on the above results, co-axial prilling approach is expected to provide success in manufacturing systems with delayed drug release profiles. Such systems may be potentially useful in targeting diseases which are affected by the circadian rhythm, such as chronic inflammation.

  2. Effect of low-energy alpha-particles irradiation on surface structure and physical-mechanical properties of high-purity tungsten

    NASA Astrophysics Data System (ADS)

    Aldabergenova, T. M.; Kislitsin, S. B.; Larionov, A. S.; Yar-Mukhamedova, G. S.

    2016-11-01

    Effect of radiation by low-energy alpha-particles on the surface structure and physical-mechanical properties of high-purity tungsten was studied. Samples of tungsten were irradiated by 4He+2 ions with the energy of 45 keV at low-energy channel of accelerator DC-60 in Astana branch of Institute Nuclear Physics. Irradiation fluence was 1.5 × 1018 cm-2, irradiation temperature was 150°C. Experimentally found that irradiation with low-energy alpha particles results in formation of helium filled bubbles in the straggling region.

  3. Hit rates and radiation doses to nuclei of bone lining cells from alpha-particle-emitting radionuclides

    NASA Technical Reports Server (NTRS)

    Polig, E.; Jee, W. S.; Kruglikov, I. L.

    1992-01-01

    Factors relating the local concentration of a bone-seeking alpha-particle emitter to the mean hit rate have been determined for nuclei of bone lining cells using a Monte Carlo procedure. Cell nuclei were approximated by oblate spheroids with dimensions and location taken from a previous histomorphometric study. The Monte Carlo simulation is applicable for planar and diffuse labels at plane or cylindrical bone surfaces. Additionally, the mean nuclear dose per hit, the dose mean per hit, the mean track segment length and its second moment, the percentage of stoppers, and the frequency distribution of the dose have been determined. Some basic features of the hit statistics for bone lining cells have been outlined, and the consequences of existing standards of radiation protection with regard to the hit frequency to cell nuclei are discussed.

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

    SciTech Connect

    Adams, Gregory P.

    2004-11-24

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

  5. Complex aberrations in lymphocytes exposed to mixed beams of (241)Am alpha particles and X-rays.

    PubMed

    Staaf, Elina; Deperas-Kaminska, Marta; Brehwens, Karl; Haghdoost, Siamak; Czub, Joanna; Wojcik, Andrzej

    2013-08-30

    Modern radiotherapy treatment modalities are associated with undesired out-of-field exposure to complex mixed beams of high and low energy transfer (LET) radiation that can give rise to secondary cancers. The biological effectiveness of mixed beams is not known. The aim of the investigation was the analysis of chromosomal damage in human peripheral blood lymphocytes (PBL) exposed to a mixed beam of X-rays and alpha particles. Using a dedicated exposure facility PBL were exposed to increasing doses of alpha particles (from (241)Am), X-rays and a mixture of both. Chromosomal aberrations were analysed in chromosomes 2, 8 and 14 using fluorescence in situ hybridisation. The found and expected frequencies of simple and complex aberrations were compared. Simple aberrations showed linear dose-response relationships with doses. A higher than expected frequency of simple aberrations was only observed after the highest mixed beam dose. A linear-quadratic dose response curve for complex aberrations was observed after mixed-beam exposure. Higher than expected frequencies of complex aberrations were observed for the two highest doses. Both the linear-quadratic dose-response relationship and the calculation of expected frequencies show that exposure of PBL to mixed beams of high and low LET radiation leads to a higher than expected frequency of complex-type aberrations. Because chromosomal changes are associated with cancer induction this result may imply that the cancer risk of exposure to mixed beams in radiation oncology may be higher than expected based on the additive action of the individual dose components.

  6. Evaluation of Melt-Grown, ZnO Single Crystals for Use as Alpha-Particle Detectors

    SciTech Connect

    Neal, John S; Giles, N. C.; Yang, Xiaocheng; Wall, R. Andrew; Ucer, Burak; Williams, Richard T.; Wisniewski, Dariusz J; Boatner, Lynn A; Rengarajan, Varatharajan; Nause, Jeff E; Nemeth, Bell

    2008-01-01

    As part of an ongoing investigation of the scintillation properties of zinc-oxide-based scintillators, several melt-grown, ZnO single crystals have been characterized using -particle excitation, infrared reflectance, and room temperature photoluminescence. The crystals, grown by Cermet, Inc. using a pressurized melt growth process, were doped with Group 1 elements (Li), Group 2 elements (Mg), Group 3 elements (Ga, In) and Lanthanides (Gd, Er, Tm). The goals of these studies are to better understand the scintillation mechanisms associated with various members of the ZnO scintillator family and to then use this knowledge to improve the radiation detection capabilities of ZnO-based scintillators. One application for which ZnO is particularly well suited as a scintillator is as the associated particle detector in a deuterium-tritium (D-T) neutron generator. Application requirements include the exclusion of organic materials, outstanding timing resolution, and high radiation resistance. ZnO(Ga) and ZnO(In) have demonstrated fast (sub-nanosecond) decay times with relatively low light yields, and ZnO(Ga) has been used in a powder form as the associated particle detector for a D-T neutron generator. Four promising candidate materials, ZnO, ZnO:Ga, ZnO:In,Li, and ZnO:Er,Li, were identified in this study. These four samples demonstrated sub-nanosecond decay times and alpha particle excited luminescence comparable to BC-400 fast plastic scintillator. The ZnO:Mg,Ga, ZnO:Gd, and ZnO:Li samples demonstrated appreciable slow (microsecond) decay components that would be incompatible with high-counting-rate applications.

  7. BJT detector with FPGA-based read-out for alpha particle monitoring

    NASA Astrophysics Data System (ADS)

    Tyzhnevyi, V.; Dalla Betta, G.-F.; Rovati, L.; Verzellesi, G.; Zorzi, N.

    2011-01-01

    In this work we introduce a new prototype of readout electronics (ALPHADET), which was designed for an α-particle detection system based on a bipolar junction transistor (BJT) detector. The system uses an FPGA, which provides many advantages at the stage of prototyping and testing the detector. The main design and electrical features of the board are discussed in this paper, along with selected results from the characterization of ALPHADET coupled to BJT detectors.

  8. Nanoconjugation of PSMA-targeting ligands enhances perinuclear localization and improves efficacy of delivered alpha-particle emitters against tumor endothelial analogues

    PubMed Central

    Sempkowski, Michelle; Banerjee, Sangeeta Ray; Pomper, Martin G.; Bruchertseifer, Frank; Morgenstern, Alfred; Sofou, Stavroula

    2015-01-01

    This study aims to evaluate the effect on killing efficacy of the intracellular trafficking patterns of alpha-particle emitters by using different radionuclide carriers in the setting of targeted antivascular alpha-radiotherapy. Nanocarriers (lipid vesicles) targeted to the prostate-specific-membrane-antigen (PSMA), which is unique to human neovasculature for a variety of solid tumors, were loaded with the alpha-particle generator actinium-225 and were compared to a PSMA-targeted radiolabeled antibody. Actinium-225 emits a total of four alpha-particles per decay, providing highly lethal and localized irradiation of targeted cells with minimal exposure to surrounding healthy tissues. Lipid vesicles were derivatized with two types of PSMA-targeting ligands: a fully human PSMA antibody (mAb), and a urea-based, low-molecular-weight agent. Target selectivity and extent of internalization were evaluated on monolayers of human endothelial cells (HUVEC) induced to express PSMA in static incubation conditions and in a flow field. Both types of radiolabeled PSMA-targeted vesicles exhibit similar killing efficacy, which is greater than the efficacy of the radiolabeled control mAb when compared on the basis of delivered radioactivity per cell. Fluorescence confocal microscopy demonstrates that targeted vesicles localize closer to the nucleus, unlike antibodies which localize near the plasma membrane. In addition, targeted vesicles cause larger numbers of DNA double strand breaks per nucleus of treated cells compared to the radiolabeled mAb. These findings demonstrate that radionuclide carriers, such as PSMA-targeted lipid-nanocarriers, which localize close to the nucleus increase the probability of alpha-particle trajectories crossing the nuclei, and, therefore, enhance the killing efficacy of alpha-particle emitters. PMID:26586724

  9. RADIOACTIVE POSITRON EMITTER PRODUCTION BY ENERGETIC ALPHA PARTICLES IN SOLAR FLARES

    SciTech Connect

    Murphy, R. J.; Kozlovsky, B.; Share, G. H. E-mail: benz@wise.tau.ac.il

    2015-01-01

    Measurements of the 0.511 MeV positron-annihilation line from solar flares are used to explore the flare process in general and ion acceleration in particular. In flares, positrons are produced primarily by the decay of radioactive positron-emitting isotopes resulting from nuclear interactions of flare-accelerated ions with ambient solar material. Kozlovsky et al. provided ion-energy-dependent production cross sections for 67 positron emitters evaluated from their threshold energies (some <1 MeV nucleon{sup –1}) to a GeV nucleon{sup –1}, incorporating them into a computer code for calculating positron-emitter production. Adequate cross-section measurements were available for proton reactions, but not for α-particle reactions where only crude estimates were possible. Here we re-evaluate the α-particle cross sections using new measurements and nuclear reaction codes. In typical large gamma-ray line flares, proton reactions dominate positron production, but α-particle reactions will dominate for steeper accelerated-ion spectra because of their relatively low threshold energies. With the accelerated-{sup 3}He reactions added previously, the code is now reliable for calculating positron production from any distribution of accelerated-ion energies, not just those of typical flares. We have made the code available in the online version of the Journal. We investigate which reactions, projectiles, and ion energies contribute to positron production. We calculate ratios of the annihilation-line fluence to fluences of other gamma-ray lines. Such ratios can be used in interpreting flare data and in determining which nuclear radiation is most sensitive for revealing acceleration of low-energy ions at the Sun.

  10. Microdosimetry of alpha particles for simple and 3D voxelised geometries using MCNPX and Geant4 Monte Carlo codes.

    PubMed

    Elbast, M; Saudo, A; Franck, D; Petitot, F; Desbrée, A

    2012-07-01

    Microdosimetry using Monte Carlo simulation is a suitable technique to describe the stochastic nature of energy deposition by alpha particle at cellular level. Because of its short range, the energy imparted by this particle to the targets is highly non-uniform. Thus, to achieve accurate dosimetric results, the modelling of the geometry should be as realistic as possible. The objectives of the present study were to validate the use of the MCNPX and Geant4 Monte Carlo codes for microdosimetric studies using simple and three-dimensional voxelised geometry and to study their limit of validity in this last case. To that aim, the specific energy (z) deposited in the cell nucleus, the single-hit density of specific energy f(1)(z) and the mean-specific energy were calculated. Results show a good agreement when compared with the literature using simple geometry. The maximum percentage difference found is <6 %. For voxelised phantom, the study of the voxel size highlighted that the shape of the curve f(1)(z) obtained with MCNPX for <1 µm voxel size presents a significant difference with the shape of non-voxelised geometry. When using Geant4, little differences are observed whatever the voxel size is. Below 1 µm, the use of Geant4 is required. However, the calculation time is 10 times higher with Geant4 than MCNPX code in the same conditions.

  11. High field side lower hybrid launch leads to wave amplification on alpha particles

    NASA Astrophysics Data System (ADS)

    Ochs, Ian; Bertelli, Nicola; Fisch, Nathaniel

    2015-11-01

    Although lower hybrid waves have been shown to be effective in driving plasma current in present-day tokamaks, they are predicted to strongly interact with the energetic α particles born from fusion reactions in eventual tokamak reactors. However, in the presence of the expected steep α particle birth gradient, this interaction can produce wave amplification rather than wave damping. Here, we identify the flexibilities in achieving this amplification effect through a consideration of symmetries in the channeling interaction, in the wave propagation, and in the tokamak field configuration. Interestingly, for current drive that supports the poloidal magnetic field, we find that wave amplification through α channeling is fundamentally coupled to the elusive | kl | upshift. In so doing, we show that wave launch from the tokamak high-field side is favorable both for α-channeling and for achieving the | kl | upshift. We then present a simple linear model to calculate the required radial gradients to achieve amplification. Combining this model with ray tracing simulations, we demonstrate the potential for substantial wave amplification in a regime consistent with a hot-ion-mode fusion reactor.

  12. Evidence of DNA double strand breaks formation in Escherichia coli bacteria exposed to alpha particles of different LET assessed by the SOS response.

    PubMed

    Serment-Guerrero, Jorge; Breña-Valle, Matilde; Aguilar-Moreno, Magdalena; Balcázar, Miguel

    2012-12-01

    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.

  13. TASTRAK spectroscopy of polonium-210 alpha-particle activity at bone surfaces: Evidence for a concentrated surface deposit less than 3 {mu}m deep

    SciTech Connect

    Salmon, P.L.; Henshaw, D.L.; Keitch, P.A.; Allen, J.E.; Fews, A.P.

    1994-10-01

    The technique of {alpha}-particle spectroscopy by CR-39 type TASTRAK plastic has been used to study the depth distribution of natural {alpha}-particle emitters at the surface of human bone. The predominant component of this {alpha}-particle activity was {sup 210}Po supported by {sup 210}Pb, although a smaller activity of {sup 226}Ra was also detected. Autopsy samples of human femur and cranium were obtained from subjects age 63 to 86. Both cortical and trabecular surfaces were analyzed. The results indicate that {sup 210}Pb-supported {sup 210}Po is concentrated at the surfaces of human bone from elderly subjects, in a narrow band 3 {mu}m deep or less, by a factor of about four. As a result, the {alpha}-particle dose to the nuclei of cells lining bone surfaces is around 1.8 times greater than that calculated for a uniform volume distribution. Polonium-210 activity indicates the distribution of {sup 210}Pb, and of stable lead, received by continuous intake throughout life at a very low level. A persistent bone surface concentration of lead and other osteotropic metals may be associated with the hypermineralized layer about 1 {mu}m thick which occurs at the surface of resting bone mineral. 31 refs., 9 figs., 3 tabs.

  14. Frequencies of complex chromosome exchange aberrations induced by 238Pu alpha-particles and detected by fluorescence in situ hybridization using single chromosome-specific probes.

    PubMed

    Griffin, C S; Marsden, S J; Stevens, D L; Simpson, P; Savage, J R

    1995-04-01

    We undertook an analysis of chromosome-type exchange aberrations induced by alpha-particles using fluorescence in situ hybridization (FISH) with whole chromosome-specific probes for human chromosomes 1 or 4, together with a pan-centromeric probe. Contact-inhibited primary human fibroblasts (in G1) were irradiated with 0.41-1.00 Gy 238Pu alpha-particles and aberrations were analysed at the next mitosis following a single chromosome paint. Exchange and aberration painting patterns were classified according to Savage and Simpson (1994a). Of exchange aberrations, 38-47% were found to be complex derived, i.e. resulting from three or more breaks in two or more chromosomes, and the variation with dose was minimal. The class of complex aberrations most frequently observed were insertions, derived from a minimum of three breaks in two chromosomes. There was also an elevated frequency of rings. The high level of complex aberrations observed after alpha-particle irradiation indicates that, when chromosome domains are traversed by high linear energy transfer alpha-particle tracks, there is an enhanced probability of production of multiple localized double-strand breaks leading to more complicated interactions.

  15. X-ray production cross-sections measurements for high-energy alpha particle beams: New dedicated set-up and first results with aluminum

    NASA Astrophysics Data System (ADS)

    Dupuis, T.; Chêne, G.; Mathis, F.; Marchal, A.; Garnir, H.-P.; Strivay, D.

    2011-12-01

    The "IPNAS" laboratory, in collaboration with the "Centre Européen d'Archéométrie" is partly focused on material analysis by means of IBA techniques: PIXE, PIGE and RBS. A new transport beam line has been developed at our CGR-520 MeV cyclotron to analyze Cultural Heritage objects using these techniques. This facility allows us to produce proton and alpha particle beams with energies up to 20 MeV. A vacuum chamber dedicated to X-ray production and Non-Rutherford cross-section measurements has been recently constructed. After determination of the chamber's geometry for X-ray detection using thin foils of several elements (11 ⩽ Z ⩽ 82) and 3 MeV proton beams, the measurement of the X-ray production cross-sections in the 6-12 MeV energy range has started using alpha particle beams on light element targets. These experiments contribute to the filling a serious lack of experimental values for alpha particles of this particular energy range in databases. The recent decision to focus our work on the alpha particle interaction with light elements was taken because of the high interest of the low Z elements in the field of archaeometry.

  16. Applications of 211At and 223Ra in targeted alpha-particle radiotherapy.

    PubMed

    Vaidyanathan, Ganesan; Zalutsky, Michael R

    2011-10-01

    Targeted radiotherapy using agents tagged with α-emitting radionuclides is gaining traction with several clinical trials already undertaken or ongoing, and others in the advanced planning stage. The most commonly used α-emitting radionuclides are 213Bi, 211At, 223Ra and 225Ac. While each one of these has pros and cons, it can be argued that 211At probably is the most versatile based on its half life, decay scheme and chemistry. On the other hand, for targeting bone metastases, 223Ra is the ideal radionuclide because simple cationic radium can be used for this purpose. In this review, we will discuss the recent developments taken place in the application of 211At-labeled radiopharmaceuticals and give an overview of the current status of 223Ra for targeted α-particle radiotherapy.

  17. Alpha-Particle Emitting 213Bi-Anti-EGFR Immunoconjugates Eradicate Tumor Cells Independent of Oxygenation

    PubMed Central

    Gaertner, Florian C.; Bruchertseifer, Frank; Morgenstern, Alfred; Essler, Markus; Senekowitsch-Schmidtke, Reingard

    2013-01-01

    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. PMID:23724085

  18. Improvement of Makrofol® De 7-2 polycarbonate optical properties by thermal annealing for the registration of alpha particles

    NASA Astrophysics Data System (ADS)

    El Ghazaly, M.; Aydarous, Abdilkadir

    Translucent Makrofol® DE 7-2 polycarbonate samples are thermally-annealed at 200 °C for different durations in the air. UV-Vis spectra of the thermally-annealed Makrofol® DE 7-2 were measured. The results reveal that the light absorbance by thermally-annealed Makrofol® DE 7-2 is significantly minimized which enhances the visualization of the charged particle track registered on it. Both direct and indirect band gaps show pronounced stability over all thermal annealing durations; the same behavior was observed to Urbach's energy and the number of carbon atoms per cluster where no reasonable alteration was observed. The thermally-annealed Makrofol® DE 7-2 was irradiated with 3 MeV alpha particles and etched for different durations in 75% 6 N KOH + 25% C2H5OH at 50 °C. Alpha particle track diameter is found to be linearly correlated with the etching time up to 3 h before the Bragg peak. The chemical etching efficiency of alpha particle tracks ranges from 0.22 to 0.26. The current new findings indicate the possibility to improve the optical properties of translucent Makrofol® DE 7-2 by a thermal annealing for its utilization in charged particle registration.

  19. Monte Carlo particle-trajectory models for neutral cometary gases. I - Models and equations. II - The spatial morphology of the Lyman-alpha coma

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.; Smyth, William H.

    1988-01-01

    The mathematical derivations of various methods employed in the Monte Carlo particle-trajectory model (MCPTM) are presented, and the application of the MCPTM to the calculation of the photochemical heating of the inner coma through the partial thermalization of cometary hydrogen atoms produced by the photodissociation of water is discussed. This model is then used to explain the observed morphology of the spatially extended Ly-alpha comas of comets. The rocket and Skylab images of the Ly-alpha coma of Comet Kohoutek are examined.

  20. Design of a neutron-TPC prototype and its performance evaluation based on an alpha-particle test

    NASA Astrophysics Data System (ADS)

    Huang, Meng; Li, Yu-Lan; Niu, Li-Bo; Li, Jin; Deng, Zhi; He, Li; Zhang, Hong-Yan; Cheng, Xiao-Lei; Fu, Jian-Qiang; Li, Yuan-Jing

    2015-08-01

    A neutron-TPC (nTPC) is being developed for use as a fast neutron spectrometer in the fields of nuclear physics, nuclear reactor operation monitoring, and thermo-nuclear fusion plasma diagnostics. An nTPC prototype based on a GEM-TPC (Time Projection Chamber with Gas Electron Multiplier amplification) has been assembled and tested using argon-hydrocarbon mixture as the working gas. By measuring the energy deposition of the recoil proton in the sensitive volume and the angle of the proton track, the incident neutron energy can be deduced. A Monte Carlo simulation was carried out to analyze the parameters affecting the energy resolution of the nTPC, and gave an optimized resolution under ideal conditions. An alpha particle experiment was performed to verify its feasibility, and to characterize its performance, including energy resolution and spatial resolution. Based on the experimental measurement and analysis, the energy resolution (FWHM) of the nTPC prototype is predicted to be better than 3.2% for 5 MeV incident neutrons, meeting the performance requirement (FWHM<5%) for the nTPC prototype.

  1. Cell Cycle Checkpoint Proteins p21 and Hus1 Regulating Intercellular Signaling Induced By Alpha Particle Irradiation

    NASA Astrophysics Data System (ADS)

    Wu, Lijun; Zhao, Ye; Wang, Jun; Hang, Haiying

    In recent years, the attentions for radiation induced bystander effects (RIBE) have been paid on the intercellular signaling events connecting the irradiated and non-irradiated cells. p21 is a member of the Cip/Kip family and plays essential roles in cell cycle progression arrest after cellular irradiation. DNA damage checkpoint protein Hus1 is a member of the Rad9-Rad1-Hus1 complex and functions as scaffold at the damage sites to facilitate the activation of downstream effectors. Using the medium trasfer method and the cells of MEF, MEF (p21-/-), MEF (p21-/-Hus1-/-) as either medium donor or receptor cells, it was found that with 5cGy alpha particle irradiation, the bystander cells showed a significant induction of -H2AX for normal MEFs (p¡0.05). However, the absence of p21 resulted in deficiency in inducing bystander effects. Further results indicated p21 affected the intercellular DNA damage signaling mainly through disrupting the production or release of the damage signals from irradiated cells. When Hus1 and p21 were both knocked out, an obvious induction of -H2AX recurred in bystander cells and the induction of -H2AX was GJIC (gap junction-mediated intercellular communication) dependent, indicating the interrelationship between p21 and Hus1 regulated the production and relay of DNA damage signals from irradiated cells to non-irradiated bystander cells.

  2. Cell growth kinetics of the human cell line Colo-205 irradiated with photons and astatine-211 alpha-particles.

    PubMed

    Palm, S; Andersson, H; Bäck, T; Claesson, I; Delle, U; Hultborn, R; Jacobsson, L; Köpf, I; Lindegren, S

    2000-01-01

    Cell growth kinetics following Astatine-211 (211At, alpha-particle emitter) and photon irradiation were studied for the human colorectal cell line Colo-205. A growth assay using 96-well plates was chosen. The growth kinetics could be simulated by assuming certain fractions of cells with various proliferative capacities, i.e. from none up to 5 cell doublings, in addition to the defined survivors with remaining unlimited clonogenic capacity. No significant difference in cell growth characteristics was seen between 211At and photon irradiation. The cell doubling time, as calculated from the increment in optical density, was compared with the results from BrdU experiments in the early phases of growth (Tpot = 18.5 +/- 0.6 h for LDR (low dose rate) photon irradiated and 20.3 +/- 0.8 hours for sham-irradiated cells 40-45 hours post-irradiation) confirming the transient accelerated growth of irradiated cells. No statistically significant difference in growth was found between LDR, MDR (medium dose rate) and HDR (high dose rate) photon irradiation.

  3. Characteristics and mechanisms of the bystander response in monolayer cell cultures exposed to very low fluences of alpha particles

    NASA Astrophysics Data System (ADS)

    Little, John B.; Azzam, Edouard I.; de Toledo, Sonia M.; Nagasawa, Hatsumi

    2005-02-01

    When confluent cultures of mammalian cells are irradiated with very low fluences of alpha particles whereby only occasional cells receive any radiation exposure, genetic changes are observed in the non-irradiated ("bystander") cells. Upregulation of the p53 damage-response pathway as well as activation of proteins in the MAPK family occurred in bystander cells; p53 was phosphorylated on the serine 15 residue suggesting that the upregulation of p53 was a consequence of DNA damage. Damage signals were transmitted to bystander cells through gap junctions, as confirmed by the use of genetically manipulated cells including connexin43 knockouts. Expression of connexin43 was markedly enhanced by irradiation. A moderate bystander effect was observed for specific gene mutations and chromosomal aberrations. This effect was markedly enhanced in cells defective in the non-homologous end joining DNA repair pathway. Finally, an upregulation of oxidative metabolism occurred in bystander cells; the increased levels of reactive oxygen species appeared to be derived from flavine-containing oxidase enzymes. We hypothesize that genetic effects observed in non-irradiated bystander cells are a consequence of oxidative base damage; >90% of mutations in bystander cells were point mutations. When bystander cells cannot repair DNA double strand breaks, they become much more sensitive to the induction of chromosomal aberrations and mutations, the latter consisting primarily of deletion mutants. While we propose that the genetic effects occurring in bystander cells are a consequence of oxidative stress, the nature of the signal that initiates this process remains to be determined.

  4. A global Mars dust composition refined by the Alpha-Particle X-ray Spectrometer in Gale Crater

    NASA Astrophysics Data System (ADS)

    Berger, Jeff A.; Schmidt, Mariek E.; Gellert, Ralf; Campbell, John L.; King, Penelope L.; Flemming, Roberta L.; Ming, Douglas W.; Clark, Benton C.; Pradler, Irina; VanBommel, Scott J. V.; Minitti, Michelle E.; Fairén, Alberto G.; Boyd, Nicholas I.; Thompson, Lucy M.; Perrett, Glynis M.; Elliott, Beverley E.; Desouza, Elstan

    2016-01-01

    Modern Martian dust is similar in composition to the global soil unit and bulk basaltic Mars crust, but it is enriched in S and Cl. The Alpha Particle X-ray Spectrometer (APXS) on the Mars Science Laboratory Curiosity rover analyzed air fall dust on the science observation tray (o-tray) in Gale Crater to determine dust oxide compositions. The o-tray dust has the highest concentrations of SO3 and Cl measured in Mars dust (SO3 8.3%; Cl 1.1 wt %). The molar S/Cl in the dust (3.35 ± 0.34) is consistent with previous studies of Martian dust and soils (S/Cl = 3.7 ± 0.7). Fe is also elevated ~25% over average Mars soils and the bulk crust. These enrichments link air fall dust with the S-, Cl-, and Fe-rich X-ray amorphous component of Gale Crater soil. Dust and soil have the same S/Cl, constraining the surface concentrations of S and Cl on a global scale.

  5. Particle size and interfacial effects on thermo-physical and heat transfer characteristics of water-based alpha-SiC nanofluids.

    PubMed

    Timofeeva, Elena V; Smith, David S; Yu, Wenhua; France, David M; Singh, Dileep; Routbort, Jules L

    2010-05-28

    The effect of average particle sizes on basic macroscopic properties and heat transfer performance of alpha-SiC/water nanofluids was investigated. The average particle sizes, calculated from the specific surface area of nanoparticles, were varied from 16 to 90 nm. Nanofluids with larger particles of the same material and volume concentration provide higher thermal conductivity and lower viscosity increases than those with smaller particles because of the smaller solid/liquid interfacial area of larger particles. It was also demonstrated that the viscosity of water-based nanofluids can be significantly decreased by pH of the suspension independently from the thermal conductivity. Heat transfer coefficients were measured and compared to the performance of base fluids as well as to nanofluids reported in the literature. Criteria for evaluation of the heat transfer performance of nanofluids are discussed and optimum directions in nanofluid development are suggested.

  6. Calculation of effective atomic number and electron density of essential biomolecules for electron, proton, alpha particle and multi-energetic photon interactions

    NASA Astrophysics Data System (ADS)

    Kurudirek, Murat; Onaran, Tayfur

    2015-07-01

    Effective atomic numbers (Zeff) and electron densities (Ne) of some essential biomolecules have been calculated for total electron interaction, total proton interaction and total alpha particle interaction using an interpolation method in the energy region 10 keV-1 GeV. Also, the spectrum weighted Zeff for multi-energetic photons has been calculated using Auto-Zeff program. Biomolecules consist of fatty acids, amino acids, carbohydrates and basic nucleotides of DNA and RNA. Variations of Zeff and Ne with kinetic energy of ionizing charged particles and effective photon energies of heterogeneous sources have been studied for the given materials. Significant variations in Zeff and Ne have been observed through the entire energy region for electron, proton and alpha particle interactions. Non-uniform variation has been observed for protons and alpha particles in low and intermediate energy regions, respectively. The maximum values of Zeff have found to be in higher energies for total electron interaction whereas maximum values have found to be in relatively low energies for total proton and total alpha particle interactions. When it comes to the multi-energetic photon sources, it has to be noted that the highest Zeff values were found at low energy region where photoelectric absorption is the pre-dominant interaction process. The lowest values of Zeff have been shown in biomolecules such as stearic acid, leucine, mannitol and thymine, which have highest H content in their groups. Variation in Ne seems to be more or less the same with the variation in Zeff for the given materials as expected.

  7. 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

    PubMed Central

    Riquier, Hélène; Abel, Denis; Wera, Anne-Catherine; Heuskin, Anne-Catherine; Genard, Géraldine; Lucas, Stéphane; Michiels, Carine

    2015-01-01

    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. PMID:25794049

  8. Pulse-shape discrimination and energy quenching of alpha particles in Cs2LiLaBr6:Ce3+

    DOE PAGES

    Mesick, Katherine Elizabeth; Coupland, Daniel David S.; Stonehill, Laura Catherine

    2016-10-19

    Cs2LiLaBr6:Ce3+ (CLLB) is an elpasolite scintillator that offers excellent linearity and gamma-ray energy resolution and sensitivity to thermal neutrons with the ability to perform pulse-shape discrimination (PSD) to distinguish gammas and neutrons. Our investigation of CLLB has indicated the presence of intrinsic radioactive alpha background that we have determined to be from actinium contamination of the lanthanum component. We measured the pulse shapes for gamma, thermal neutron, and alpha events and determined that PSD can be performed to separate the alpha background with a moderate figure of merit of 0.98. Here, we also measured the electron-equivalent-energy of the alpha particlesmore » in CLLB and simulated the intrinsic alpha background from 227Ac to determine the quenching factor of the alphas.« less

  9. Combined application of alpha-track and fission-track techniques for detection of plutonium particles in environmental samples prior to isotopic measurement using thermo-ionization mass spectrometry.

    PubMed

    Lee, Chi-Gyu; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki; Kimura, Takaumi

    2011-07-15

    The fission track technique is a sensitive detection method for particles which contain radio-nuclides like (235)U or (239)Pu. However, when the sample is a mixture of plutonium and uranium, discrimination between uranium particles and plutonium particles is difficult using this technique. In this study, we developed a method for detecting plutonium particles in a sample mixture of plutonium and uranium particles using alpha track and fission track techniques. The specific radioactivity (Bq/g) for alpha decay of plutonium is several orders of magnitude higher than that of uranium, indicating that the formation of the alpha track due to alpha decay of uranium can be disregarded under suitable conditions. While alpha tracks in addition to fission tracks were detected in a plutonium particle, only fission tracks were detected in a uranium particle, thereby making the alpha tracks an indicator for detecting particles containing plutonium. In addition, it was confirmed that there is a linear relationship between the numbers of alpha tracks produced by plutonium particles made of plutonium certified standard material and the ion intensities of the various plutonium isotopes measured by thermo-ionization mass spectrometry. Using this correlation, the accuracy in isotope ratios, signal intensity and measurement errors is presumable from the number of alpha tracks prior to the isotope ratio measurements by thermal ionization mass spectrometry. It is expected that this method will become an effective tool for plutonium particle analysis. The particles used in this study had sizes between 0.3 and 2.0 μm.

  10. ITER Plasma at Ion Cyclotron Frequency Domain: The Fusion Alpha Particles Diagnostics Based on the Stimulated Raman Scattering of Fast Magnetosonic Wave off High Harmonic Ion Bernstein Modes

    NASA Astrophysics Data System (ADS)

    Stefan, V. Alexander

    2014-10-01

    A novel method for alpha particle diagnostics is proposed. The theory of stimulated Raman scattering, SRS, of the fast wave and ion Bernstein mode, IBM, turbulence in multi-ion species plasmas, (Stefan University Press, La Jolla, CA, 2008). is utilized for the diagnostics of fast ions, (4)He (+2), in ITER plasmas. Nonlinear Landau damping of the IBM on fast ions near the plasma edge leads to the space-time changes in the turbulence level, (inverse alpha particle channeling). The space-time monitoring of the IBM turbulence via the SRS techniques may prove efficient for the real time study of the fast ion velocity distribution function, spatial distribution, and transport. Supported by Nikola Tesla Labs., La Jolla, CA 92037.

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

    PubMed

    Darrow, D S; Cecil, F E; Kiptily, V; Fullard, K; Horton, A; Murari, A

    2010-10-01

    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. Determination of primary energy in nucleus-nucleus collisions and the high P(sub)T tail of alpha-particles

    NASA Technical Reports Server (NTRS)

    Freier, P. S.; Atwater, T. W.

    1985-01-01

    A determination of primary energy is required in order to study the energy dependence of meson multiplicity in A-A collisions in cosmic rays. Various procedures which estimate the energy of a primary nucleus from its interaction were investigated. An average of two methods were used, one using the pions and wounded protons and the other using spectator protons and alpha particles. The high P sub T tail observed for Z = 2 fragments requires a modification of the latter method.

  13. Electrical characterization of deep levels created by bombarding nitrogen-doped 4H-SiC with alpha-particle irradiation

    NASA Astrophysics Data System (ADS)

    Omotoso, Ezekiel; Meyer, Walter E.; Auret, F. Danie; Paradzah, Alexander T.; Legodi, Matshisa J.

    2016-03-01

    Deep-level transient spectroscopy (DLTS) and Laplace-DLTS were used to investigate the effect of alpha-particle irradiation on the electrical properties of nitrogen-doped 4H-SiC. The samples were bombarded with alpha-particles at room temperature (300 K) using an americium-241 (241Am) radionuclide source. DLTS revealed the presence of four deep levels in the as-grown samples, E0.09, E0.11, E0.16 and E0.65. After irradiation with a fluence of 4.1 × 1010 alpha-particles-cm-2, DLTS measurements indicated the presence of two new deep levels, E0.39 and E0.62 with energy levels, EC - 0.39 eV and EC - 0.62 eV, with an apparent capture cross sections of 2 × 10-16 and 2 × 10-14 cm2, respectively. Furthermore, irradiation with fluence of 8.9 × 1010 alpha-particles-cm-2 resulted in the disappearance of shallow defects due to a lowering of the Fermi level. These defects re-appeared after annealing at 300 °C for 20 min. Defects, E0.39 and E0.42 with close emission rates were attributed to silicon or carbon vacancy and could only be separated by using high resolution Laplace-DLTS. The DLTS peaks at EC - (0.55-0.70) eV (known as Z1/Z2) were attributed to an isolated carbon vacancy (VC).

  14. Engineered Modular Recombinant Transporters: Application of New Platform for Targeted Radiotherapeutic Agents to {alpha}-Particle Emitting {sup 211}At

    SciTech Connect

    Rosenkranz, Andrey A.; Vaidyanathan, Ganesan; Pozzi, Oscar R.; Lunin, Vladimir G.; Zalutsky, Michael R. Sobolev, Alexander S.

    2008-09-01

    Purpose: To generate and evaluate a modular recombinant transporter (MRT) for targeting {sup 211}At to cancer cells overexpressing the epidermal growth factor receptor (EGFR). Methods and Materials: The MRT was produced with four functional modules: (1) human epidermal growth factor as the internalizable ligand, (2) the optimized nuclear localization sequence of simian vacuolating virus 40 (SV40) large T-antigen, (3) a translocation domain of diphtheria toxin as an endosomolytic module, and (4) the Escherichia coli hemoglobin-like protein (HMP) as a carrier module. MRT was labeled using N-succinimidyl 3-[{sup 211}At]astato-5-guanidinomethylbenzoate (SAGMB), its {sup 125}I analogue SGMIB, or with {sup 131}I using Iodogen. Binding, internalization, and clonogenic assays were performed with EGFR-expressing A431, D247 MG, and U87MG.wtEGFR human cancer cell lines. Results: The affinity of SGMIB-MRT binding to A431 cells, determined by Scatchard analysis, was 22 nM, comparable to that measured before labeling. The binding of SGMIB-MRT and its internalization by A431 cancer cells was 96% and 99% EGFR specific, respectively. Paired label assays demonstrated that compared with Iodogen-labeled MRT, SGMIB-MRT and SAGMB-MRT exhibited more than threefold greater peak levels and durations of intracellular retention of activity. SAGMB-MRT was 10-20 times more cytotoxic than [{sup 211}At]astatide for all three cell lines. Conclusion: The results of this study have demonstrated the initial proof of principle for the MRT approach for designing targeted {alpha}-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this {sup 211}At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor.

  15. The thermoluminescence response of doped SiO2 optical fibres subjected to alpha-particle irradiation.

    PubMed

    Ramli, Ahmad Termizi; Bradley, D A; Hashim, Suhairul; Wagiran, Husin

    2009-03-01

    Ion beams are used in radiotherapy to deliver a more precise dose to the target volume while minimizing dose to the surrounding healthy tissue. For optimum dose monitoring in ion-beam therapy, it is essential to be able to measure the delivered dose with a sensitivity, spatial resolution and dynamic range that is sufficient to meet the demands of the various therapy situations. Optical fibres have been demonstrated by this group to show promising thermoluminescence properties with respect to photon, electron and proton irradiation. In particular, and also given the flexibility and small size of optical fibre cores, for example 125.0+/-0.1 microm for the Al- and Ge-doped fibres used in this study, these fibres have the potential to fulfill the above requirements. This study investigates the thermoluminescence dosimetric characteristics of variously doped SiO(2) optical fibres irradiated with alpha particles from (241)Am. Following subtraction of the gamma contribution from the above source, the thermoluminescence characteristics of variously doped SiO(2) optical fibres have been compared with that of TLD-100 rods. The irradiations were performed in a bell jar. Of related potential significance is the effective atomic number, Z(eff) of the fibre, modifying measured dose from that deposited in tissues; in the present work, a scanning electron microscope and associated energy dispersive X-ray spectroscopy facility have been used to provide evaluation of Z(eff). For Ge-doped fibres, the effective atomic numbers value was 11.4, the equivalent value for Al-doped fibres was 12.3. This paper further presents results on dose response and the glow curves obtained. The results obtained indicate there to be good potential for use of variously doped SiO(2) optical fibres in measuring ion-beam doses in radiotherapeutic applications.

  16. Numerical investigation on the stabilization of the deceleration phase Rayleigh-Taylor instability due to alpha particle heating in ignition target

    NASA Astrophysics Data System (ADS)

    Fan, Zhengfeng; Zhu, Shaoping; Pei, Wenbing; Ye, Wenhua; Li, Meng; Xu, Xiaowen; Wu, Junfeng; Dai, Zhensheng; Wang, Lifeng

    2012-09-01

    Tritium-hydrogen-deuterium (THD) target is adopted in order to experimentally diagnose the properties of the ignition hot spot and the highly compressed main fusion fuel (Edwards M. J. et al., Phys. Plasmas, 18 (2011) 051003). As compared with deuterium-tritium (DT) target, the thermonuclear alpha particles which are needed to heat the fusion fuel, are much less in the THD target. In the present paper, the effect of alpha particle heating on the deceleration phase Rayleigh-Taylor instability (dp-RTI), which is one of the key problems in hot spot formation, is investigated systematically through numerical simulations. It is found that the mass ablation at the hot spot boundary is greatly increased due to the direct alpha particle heating. As a result, the dp-RTI growth rates are greatly reduced and the cut-off mode number decreases greatly from about 33 to 17. This explains why the hydrodynamic instability in the THD target grows more severely than in the DT ignition target.

  17. Predictive nonlinear studies of TAE-induced alpha-particle transport in the Q  =  10 ITER baseline scenario

    NASA Astrophysics Data System (ADS)

    Fitzgerald, M.; Sharapov, S. E.; Rodrigues, P.; Borba, D.

    2016-11-01

    We use the HAGIS code to compute the nonlinear stability of the Q  =  10 ITER baseline scenario to toroidal Alfvén eigenmodes (TAE) and the subsequent effects of these modes on fusion alpha-particle redistribution. Our calculations build upon an earlier linear stability survey (Rodrigues et al 2015 Nucl. Fusion 55 083003) which provides accurate values of bulk ion, impurity ion and electron thermal Landau damping for our HAGIS calculations. Nonlinear calculations of up to 129 coupled TAEs with toroidal mode numbers in the range n  =  1-35 have been performed. The effects of frequency sweeping were also included to examine possible phase space hole and clump convective transport. We find that even parity core localised modes are dominant (expected from linear theory), and that linearly stable global modes are destabilised nonlinearly. Landau damping is found to be important in reducing saturation amplitudes of coupled modes to below δ {{B}r}/{{B}0}˜ 3× {{10}-4} . For these amplitudes, stochastic transport of alpha-particles occurs in a narrow region where predominantly core localised modes are found, implying the formation of a transport barrier at r/a≈ 0.5 , beyond which, the weakly driven global modes are found. We find that for flat q profiles in this baseline scenario, alpha particle transport losses and redistribution by TAEs is minimal.

  18. Elemental Analysis of the Surface of Comet 67p/Churyumov-Gerasimenko with the Alpha Particle X-Ray Spectrometer APXS on the Rosetta Lander Philae: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Klingelhoefer, G.; Schmanke, D.; Girones-Lopez, J.; Brueckner, J.; d'Uston, C.; Economou, T.; Gellert, R.; Markovski, C.

    2014-12-01

    After a 10 years cruise the Rosetta probe has reached its final target, the comet 67P/Churyumov-Gerasimenko. The main objectives of the mission are to gain more knowledge of the composition, the origin and formation of comets and the solar system. After extensive remote exploration of the comet the lander Philae will be separated to land on the comet surface, starting immediately examining its landing site with its scientific payload. Part of this payload is the APXS (Alpha Particle X-Ray Spectrometer). It will measure in situ the chemical composition of the comet's surface and it's changes during the journey of the comet towards the sun. APXS is a combination of two spectrometers in one single instrument. It will irradiate the comet surface using Curium 244 sources, which are emitting alpha-particle and X-rays. In the alpha-mode the instrument uses alpha backscattering spectroscopy to detect lower Z elements like C, N and O and groups of elements with higher Z. In the X-ray mode alpha particle / X-ray induced X-ray spectroscopy (XRF) will allow the detection of most of the higher Z elements from Na up to Ni and above. Both modes will be always run in parallel allowing to determine lower and higher Z elements simultaneously. For 3 years the solar powered Rosetta probe had to pass a hibernation phase because of a long passage far away to the sun. After wakeup in January 2014 an extensive test phase of all instruments and subsystems has been performed, including the APXS. After landing on the comet an intense initial measurement phase of all instruments is planned, the First Science Sequence (FSS). It will be followed by a long term science phase (LTS). As long as possible APXS and the other instruments will continue to measure and monitor the changes and increasing activity of the comet during its journey towards the inner region of the solar system.The project is funded by the German Space Agency DLR under contracts 50 QP 0404 and 50 QP 0902. References: G

  19. Benchmarking the Geant4 full system simulation of an associated alpha-particle detector for use in a D-T neutron generator.

    PubMed

    Zhang, Xiaodong; Hayward, Jason P; Cates, Joshua W; Hausladen, Paul A; Laubach, Mitchell A; Sparger, Johnathan E; Donnald, Samuel B

    2012-08-01

    The position-sensitive alpha-particle detector used to provide the starting time and initial direction of D-T neutrons in a fast-neutron imaging system was simulated with a Geant4-based Monte Carlo program. The whole detector system, which consists of a YAP:Ce scintillator, a fiber-optic faceplate, a light guide, and a position-sensitive photo-multiplier tube (PSPMT), was modeled, starting with incident D-T alphas. The scintillation photons, whose starting time follows the distribution of a scintillation decay curve, were produced and emitted uniformly into a solid angle of 4π along the track segments of the alpha and its secondaries. Through tracking all photons and taking into account the quantum efficiency of the photocathode, the number of photoelectrons and their time and position distributions were obtained. Using a four-corner data reconstruction formula, the flood images of the alpha detector with and without optical grease between the YAP scintillator and the fiber-optic faceplate were obtained, which show agreement with the experimental results. The reconstructed position uncertainties of incident alpha particles for both cases are 1.198 mm and 0.998 mm respectively across the sensitive area of the detector. Simulation results also show that comparing with other faceplates composed of 500 μm, 300 μm, and 100 μm fibers, the 10-μm-fiber faceplate is the best choice to build the detector for better position performance. In addition, the study of the background originating inside the D-T generator suggests that for 500-μm-thick YAP:Ce coated with 1-μm-thick aluminum, and very good signal-to-noise ratio can be expected through application of a simple threshold.

  20. Analysis of alpha particles spectra of the Radon and Thoron progenies generated by an electrostatic collection detector using new software.

    PubMed

    Sabbarese, C; Ambrosino, F; Buompane, R; Pugliese, M; Roca, V

    2017-04-01

    A complete and detailed analysis of alpha spectra from the (222)Rn and (220)Rn progenies was performed by newly developed software. The software identifies the alpha peaks, performs appropriate fits and calculates the net area and its uncertainty, considering the entire background. The deconvolution of the overlapped peaks of (218)Po and (212)Bi allows us also to evaluate their minimum detectable area. The efficiency of the electrostatic detection method was recalculated and new useful considerations on the collected alpha emitters were made.

  1. Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation.

    PubMed

    Pignol, J P; Slabbert, J

    2001-02-01

    Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,alpha) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends.

  2. Comparison of cytotoxic and genotoxic effects of plutonium-239 alpha particles and mobile phone GSM 900 radiation in the Allium cepa test.

    PubMed

    Pesnya, Dmitry S; Romanovsky, Anton V

    2013-01-20

    The goal of this study was to compare the cytotoxic and genotoxic effects of plutonium-239 alpha particles and GSM 900 modulated mobile phone (model Sony Ericsson K550i) radiation in the Allium cepa test. Three groups of bulbs were exposed to mobile phone radiation during 0 (sham), 3 and 9h. A positive control group was treated during 20min with plutonium-239 alpha-radiation. Mitotic abnormalities, chromosome aberrations, micronuclei and mitotic index were analyzed. Exposure to alpha-radiation from plutonium-239 and exposure to modulated radiation from mobile phone during 3 and 9h significantly increased the mitotic index. GSM 900 mobile phone radiation as well as alpha-radiation from plutonium-239 induced both clastogenic and aneugenic effects. However, the aneugenic activity of mobile phone radiation was more pronounced. After 9h of exposure to mobile phone radiation, polyploid cells, three-groups metaphases, amitoses and some unspecified abnormalities were detected, which were not registered in the other experimental groups. Importantly, GSM 900 mobile phone radiation increased the mitotic index, the frequency of mitotic and chromosome abnormalities, and the micronucleus frequency in a time-dependent manner. Due to its sensitivity, the A. cepa test can be recommended as a useful cytogenetic assay to assess cytotoxic and genotoxic effects of radiofrequency electromagnetic fields.

  3. Reexamination of the {alpha}-{alpha}''fishbone'' potential

    SciTech Connect

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

    2011-09-15

    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.

  4. Poly(styrene/alpha-tert-butoxy-omega-vinylbenzylpolyglycidol) microspheres for immunodiagnostics. Principle of a novel latex test based on combined electrophoretic mobility and particle aggregation measurements.

    PubMed

    Radomska-Galant, Izabela; Basinska, Teresa

    2003-01-01

    The principle of a novel latex agglutination test based on combined results of electrophoretic mobility and particle aggregation measurements is described. Poly(styrene/alpha-tert-butoxy-omega-vinylbenzylpolyglycidol) (P(S/PGL)) microspheres were synthesized by a one step soap-free emulsion copolymerization of styrene and alpha-tert-butoxy-omega-vinylbenzylpolyglycidol macromonomer with number average molecular weight Mn = 2700 (polydispersity [Mw]/[Mn] = 1.10). Particles with monomodal size distribution (number average diameter Dn = 220 nm) and surface fraction of polyglycidol equal to f = 0.42 mol % were obtained. Human serum albumin (HSA) was covalently bound onto the surface of P(S/PGL) microspheres activated with 1,3,5-trichlorotriazine. In a model immunodiagnostic assay for anti-HSA, in which P(S/PGL) particles with covalently bound HSA have been used, the electrophoretic mobility and aggregation of microspheres were measured simultaneously. This approach allowed detection of anti-HSA in the serum in the range of anti-HSA concentrations from 0.1 to 150 microg/mL. The highest changes in electrophoretic mobility were registered for microspheres with surface concentration of immobilized HSA equal to Gamma = 9.2 x 10(-4) g/m2.

  5. The Alpha Particle X-Ray Spectrometer APXS on the Rosetta lander Philae to explore the surface of comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Girones-Lopez, Jordi; Schmanke, Dirk; Klingelhoefer, Goestar; Maul, Jasmine; Brueckner, Johannes; Duston, Claude; Gellert, Ralf; Klingelhöfer, Göstar

    The Rosetta Mission was launched in 2004 with the main objectives to gain a better under-standing of the origin and formation of comets and the solar system. After 10 years of cruise the comet 67P/Churyumov-Gerasimenko will be reached in 2014 and the lander Philae will be deployed on the surface. As a part of the lander payload the APXS will measure in situ the chemical composition of the comet's surface and it's changes during the journey of the comet towards the sun. APXS combines an alpha mode for alpha backscattering spectroscopy and an x-ray mode for alpha particle/x-ray induced x-ray spectroscopy (XRF) in one single instrument, being low in mass and power consumption. The comet surface will be irradiated by a Curium 244 source exciting characteristic x-rays of the elements present in the surface material. The alpha mode will allow detection of elements like C and O and groups of elements with higher Z. The x-ray-SD-detector will allow the detection of most of the elements from Na up to Ni and above. During the long duration travel to the comet checkouts and software updates of the Rosetta probe and its payload are performed at regular intervals. These are used to opti-mise and improve the quality of the x-ray and alpha-spectra of the APXS. Soon the Rosetta probe will go into a 3 year long hibernation mode. It will awake when approaching it's target, providing us with new exiting data that will shed light on state, evolution and origin of comets and the solar system. Acknowledgements: This project is funded by the German Space Agency DLR under contracts 50 QP 0404 and 50 QP 0902. References: G. Klingelhüfer, J. Brückner, C. d'Uston, R. Gellert, and R. Rieder, The Rosetta Alpha Particle X-ray Spectrometer (APXS), Space Science Reviews, Vol.128 (2007) 383-396; doi:10.1007/s11214-006-9137-3

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Role of exchange effects in elastic scattering of. cap alpha. particles and /sup 3/He ions by /sup 6/Li nuclei

    SciTech Connect

    Bragin, V.N.; Burtebaev, N.T.; Dui-brevesebaev, A.D.; Ivanov, G.N.; Sakuta, S.B.; Chuev, V.I.; Chulkov, L.V.

    1986-08-01

    Measurements in the entire angular range are carried out for elastic scattering of ..cap alpha.. particles with energies 36.6 and 50.5 MeV and /sup 3/He ions with energies 34, 50, 60, and 72 MeV by /sup 6/Li nuclei. The experimental data obtained have been analyzed within the framework of the optical model. The contribution to the scattering of the mechanism of elastic transfer of clusters was calculated by the distorted-wave method with a finite interaction radius.

  8. Ab initio alpha-alpha scattering.

    PubMed

    Elhatisari, Serdar; Lee, Dean; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A; Luu, Thomas; Meißner, Ulf-G

    2015-12-03

    Processes such as the scattering of alpha particles ((4)He), the triple-alpha reaction, and alpha capture play a major role in stellar nucleosynthesis. In particular, alpha capture on carbon determines the ratio of carbon to oxygen during helium burning, and affects subsequent carbon, neon, oxygen, and silicon burning stages. It also substantially affects models of thermonuclear type Ia supernovae, owing to carbon detonation in accreting carbon-oxygen white-dwarf stars. In these reactions, the accurate calculation of the elastic scattering of alpha particles and alpha-like nuclei--nuclei with even and equal numbers of protons and neutrons--is important for understanding background and resonant scattering contributions. First-principles calculations of processes involving alpha particles and alpha-like nuclei have so far been impractical, owing to the exponential growth of the number of computational operations with the number of particles. Here we describe an ab initio calculation of alpha-alpha scattering that uses lattice Monte Carlo simulations. We use lattice effective field theory to describe the low-energy interactions of protons and neutrons, and apply a technique called the 'adiabatic projection method' to reduce the eight-body system to a two-cluster system. We take advantage of the computational efficiency and the more favourable scaling with system size of auxiliary-field Monte Carlo simulations to compute an ab initio effective Hamiltonian for the two clusters. We find promising agreement between lattice results and experimental phase shifts for s-wave and d-wave scattering. The approximately quadratic scaling of computational operations with particle number suggests that it should be possible to compute alpha scattering and capture on carbon and oxygen in the near future. The methods described here can be applied to ultracold atomic few-body systems as well as to hadronic systems using lattice quantum chromodynamics to describe the interactions of

  9. Ab initio alpha-alpha scattering

    NASA Astrophysics Data System (ADS)

    Elhatisari, Serdar; Lee, Dean; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A.; Luu, Thomas; Meißner, Ulf-G.

    2015-12-01

    Processes such as the scattering of alpha particles (4He), the triple-alpha reaction, and alpha capture play a major role in stellar nucleosynthesis. In particular, alpha capture on carbon determines the ratio of carbon to oxygen during helium burning, and affects subsequent carbon, neon, oxygen, and silicon burning stages. It also substantially affects models of thermonuclear type Ia supernovae, owing to carbon detonation in accreting carbon-oxygen white-dwarf stars. In these reactions, the accurate calculation of the elastic scattering of alpha particles and alpha-like nuclei—nuclei with even and equal numbers of protons and neutrons—is important for understanding background and resonant scattering contributions. First-principles calculations of processes involving alpha particles and alpha-like nuclei have so far been impractical, owing to the exponential growth of the number of computational operations with the number of particles. Here we describe an ab initio calculation of alpha-alpha scattering that uses lattice Monte Carlo simulations. We use lattice effective field theory to describe the low-energy interactions of protons and neutrons, and apply a technique called the ‘adiabatic projection method’ to reduce the eight-body system to a two-cluster system. We take advantage of the computational efficiency and the more favourable scaling with system size of auxiliary-field Monte Carlo simulations to compute an ab initio effective Hamiltonian for the two clusters. We find promising agreement between lattice results and experimental phase shifts for s-wave and d-wave scattering. The approximately quadratic scaling of computational operations with particle number suggests that it should be possible to compute alpha scattering and capture on carbon and oxygen in the near future. The methods described here can be applied to ultracold atomic few-body systems as well as to hadronic systems using lattice quantum chromodynamics to describe the interactions of

  10. DISSIPATION OF PARALLEL AND OBLIQUE ALFVÉN-CYCLOTRON WAVES—IMPLICATIONS FOR HEATING OF ALPHA PARTICLES IN THE SOLAR WIND

    SciTech Connect

    Maneva, Y. G.; Poedts, Stefaan; Viñas, Adolfo F.; Moya, Pablo S.; Wicks, Robert T.

    2015-11-20

    We perform 2.5D hybrid simulations with massless fluid electrons and kinetic particle-in-cell ions to study the temporal evolution of ion temperatures, temperature anisotropies, and velocity distribution functions in relation to the dissipation and turbulent evolution of a broadband spectrum of parallel and obliquely propagating Alfvén-cyclotron waves. The purpose of this paper is to study the relative role of parallel versus oblique Alfvén-cyclotron waves in the observed heating and acceleration of alpha particles in the fast solar wind. We consider collisionless homogeneous multi-species plasma, consisting of isothermal electrons, isotropic protons, and a minor component of drifting α particles in a finite-β fast stream near the Earth. The kinetic ions are modeled by initially isotropic Maxwellian velocity distribution functions, which develop nonthermal features and temperature anisotropies when a broadband spectrum of low-frequency nonresonant, ω ≤ 0.34 Ω{sub p}, Alfvén-cyclotron waves is imposed at the beginning of the simulations. The initial plasma parameter values, such as ion density, temperatures, and relative drift speeds, are supplied by fast solar wind observations made by the Wind spacecraft at 1 AU. The imposed broadband wave spectra are left-hand polarized and resemble Wind measurements of Alfvénic turbulence in the solar wind. The imposed magnetic field fluctuations for all cases are within the inertial range of the solar wind turbulence and have a Kraichnan-type spectral slope α = −3/2. We vary the propagation angle from θ = 0° to θ = 30° and θ = 60°, and find that the heating of alpha particles is most efficient for the highly oblique waves propagating at 60°, whereas the protons exhibit perpendicular cooling at all propagation angles.

  11. ß-delayed γ-proton decay in ⁵⁶Zn: Analysis of the charged-particle spectrum

    SciTech Connect

    Orrigo, S. E.A.; Rubio, B.; Fujita, Y.; Blank, B.; Agramunt, J.; Algora, A.; Ascher, P.; Cáceres, L.; Cakirli, R. B.; Fujita, H.; Ganioğlu, E.; Gerbaux, M.; Kozer, H. C.; Kucuk, L.; Kurtukian-Nieto, T.; Popescu, L.; Rogers, A. M.; Susoy, G.; Stodel, C.; Suzuki, T.; Tamii, A.; Thomas, J. C.

    2015-01-01

    A study of the β decay of the proton-rich Tz = –2 nucleus ⁵⁶Zn has been reported in a recent publication. A rare and exotic decay mode, β-de-layed γ-proton decay, has been observed there for the first time in the fp shell. Here, we expand on some of the details of the data analysis, focusing on the charged particle spectrum.

  12. ß-delayed γ-proton decay in ⁵⁶Zn: Analysis of the charged-particle spectrum

    DOE PAGES

    Orrigo, S. E.A.; Rubio, B.; Fujita, Y.; ...

    2015-01-01

    A study of the β decay of the proton-rich Tz = –2 nucleus ⁵⁶Zn has been reported in a recent publication. A rare and exotic decay mode, β-de-layed γ-proton decay, has been observed there for the first time in the fp shell. Here, we expand on some of the details of the data analysis, focusing on the charged particle spectrum.

  13. Forecasting of DST index from auroral electrojet indices using time-delay neural network + particle swarm optimization

    NASA Astrophysics Data System (ADS)

    Lazzús, J. A.; López-Caraballo, C. H.; Rojas, P.; Salfate, I.; Rivera, M.; Palma-Chilla, L.

    2016-05-01

    In this study, an artificial neural network was optimized with particle swarm algorithm and trained to predict the geomagmetic DST index one hour ahead using the past values of DST and auroral electrojet indices. The results show that the proposed neural network model can be properly trained for predicting of DST(t + 1) with acceptable accuracy, and that the geomagnetic indices used have influential effects on the good training and predicting capabilities of the chosen network.

  14. Elementary Analysis of a Cometary Surface - the Alpha Particle X-Ray Spectrometer APXS on the Rosetta Mission to Comet 67P/CHURYUMOV-GERASIMENKO

    NASA Astrophysics Data System (ADS)

    Schmanke, Dirk; Economou, Thanasis; Brueckner, Johannes; Gellert, Ralf; Rodionov, Daniel; Klingelhoefer, Goestar; Girones Lopez, Jordi; Uston, Lionel D.

    After a 10 years cruise the Rosetta probe will reach its final target in the middle of this year, the comet 67P/Churyumov-Gerasimenko. The main objectives of the mission are to gain more knowledge of the composition, the origin and formation of comets and the solar system. After extensive remote examination of the comet the lander Philae will be separated to land on the comet surface. It will start immediately examining the landing site with its scientific payload. A part of this payload is the APXS (Alpha Particle X-Ray Spectrometer), it will measure in situ the chemical composition of the comet's surface and its changes during the journey of the comet towards the sun. APXS is a combination of two spectrometers in one single instrument, being low in mass and power consumption. It will irradiate the cometary surface with Curium 244 sources, which are emitting alpha-particle and X-rays. In the alpha-mode the instrument uses alpha backscattering spectroscopy to detect lower Z elements like C, N and O and groups of elements with higher Z. In the X-ray mode alpha particle/X-ray induced X-ray spectroscopy (XRF) will allow the detection of most of the higher Z elements from Na up to Ni and above. Both modes will be always run in parallel allowing to determine lower and higher Z elements simultaneously. During the long duration travel to the comet checkouts and software updates of the Rosetta probe and its payload were performed at regular intervals. In recent 3 years the solar powered Rosetta probe had to pass a hibernation phase because of a long passage far away from the sun. After the successful wakeup in January 2014 an extensive test phase of all instruments and subsystems has to be performed, including the APXS. After the landing on the comet an intense long measurement phase of all instruments is planned, the First Science Sequence (FSS). It will be followed by a long term science phase (LTS), determined by periodical changes between measurements and forced breaks

  15. A DLTS and RBS analysis of the angular dependence of defects introduced in Si during ion beam channelling using 435keV alpha-particles

    NASA Astrophysics Data System (ADS)

    Deenapanray, P. N. K.; Ridgway, M. C.; Auret, F. D.; Friedland, E.

    1998-03-01

    It is generally assumed that ion beams (IBs) used during channelling experiments create little damage when incident along a direction of low crystallographic index of a crystal lattice. We have employed deep level transient spectroscopy (DLTS) to characterise the defects produced by 435 keV alpha-particles in a Si lattice incident along the <1 0 0> axis ( α = 0°) as well as at small angles ( α ≤ 7°) with respect to this direction. The commonly observed high energy (MeV) alpha-particle-induced point defects (VO and VSb pairs and the two charge states of the divacancy, V 2) could be observed for angles of incidence as small as 0.35°. The concentration of the primary defects was observed to decrease for α ≥ 2.45°. Furthermore, isochronal annealing experiments showed that a DLTS defect peak which is superimposed on the V2{=}/{-}, and observed predominantly for α ≥ 2.45°, could be a V-related defect. Current-voltage ( I- V) and capacitance-voltage ( C- V) measurements also showed that Schottky barrier diodes (SBDs) fabricated on the exposed samples became less rectifying with increasing angle of incidence.

  16. Non-linearity issues and multiple ionization satellites in the PIXE portion of spectra from the Mars alpha particle X-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Campbell, John L.; Heirwegh, Christopher M.; Ganly, Brianna

    2016-09-01

    Spectra from the laboratory and flight versions of the Curiosity rover's alpha particle X-ray spectrometer were fitted with an in-house version of GUPIX, revealing departures from linear behavior of the energy-channel relationships in the low X-ray energy region where alpha particle PIXE is the dominant excitation mechanism. The apparent energy shifts for the lightest elements present were attributed in part to multiple ionization satellites and in part to issues within the detector and/or the pulse processing chain. No specific issue was identified, but the second of these options was considered to be the more probable. Approximate corrections were derived and then applied within the GUAPX code which is designed specifically for quantitative evaluation of APXS spectra. The quality of fit was significantly improved. The peak areas of the light elements Na, Mg, Al and Si were changed by only a few percent in most spectra. The changes for elements with higher atomic number were generally smaller, with a few exceptions. Overall, the percentage peak area changes are much smaller than the overall uncertainties in derived concentrations, which are largely attributable to the effects of rock heterogeneity. The magnitude of the satellite contributions suggests the need to incorporate these routinely in accelerator-based PIXE using helium beams.

  17. Do the various radiations present in BNCT act synergistically? Cell survival experiments in mixed alpha-particle and gamma-ray fields.

    PubMed

    Phoenix, Ben; Green, Stuart; Hill, Mark A; Jones, Bleddyn; Mill, Andrew; Stevens, David L

    2009-07-01

    In many radiotherapy situations patients are exposed to mixed field radiation. In particular in BNCT, as with all neutron beam exposures, a significant fraction of the dose is contributed by low LET gamma ray photons. The components of such a mixed field may show a synergistic interaction and produce a greater cell kill effect than would be anticipated from the independent action of the different radiation types. Such a synergy would have important implications for treatment planning and in the interpretation of clinical results. An irradiation setup has been created at the Medical Research Council in Harwell to allow simultaneous irradiation of cells by cobalt-60 gamma rays and plutonium-238 alpha-particles. The setup allows for variation of dose and dose rates for both sources along with variation of the alpha particle energy. A series of cell survival assays for this mixed field have been carried out using V79-4 cells and compared to exposures to the individual components of the field under identical conditions. In the experimental setup described no significant synergistic effect was observed.

  18. Gas-saturated solution process to obtain microcomposite particles of alpha lipoic acid/hydrogenated colza oil in supercritical carbon dioxide.

    PubMed

    Mishima, Kenji; Honjo, Masatoshi; Sharmin, Tanjina; Ito, Shota; Kawakami, Ryo; Kato, Takafumi; Misumi, Makoto; Suetsugu, Tadashi; Orii, Hideaki; Kawano, Hiroyuki; Irie, Keiichi; Sano, Kazunori; Mishima, Kenichi; Harada, Takunori; Ouchi, Mikio

    2016-09-01

    Alpha lipoic acid (ALA), an active substance in anti-aging products and dietary supplements, need to be masked with an edible polymer to obscure its unpleasant taste. However, the high viscosity of the ALA molecules prevents them from forming microcomposites with masking materials even in supercritical carbon dioxide (scCO2). Therefore, the purpose of this study was to investigate and develop a novel production method for microcomposite particles for ALA in hydrogenated colza oil (HCO). Microcomposite particles of ALA/HCO were prepared by using a novel gas-saturated solution (PGSS) process in which the solid-dispersion method is used along with stepwise temperature control (PGSS-STC). Its high viscosity prevents the formation of microcomposites in the conventional PGSS process even under strong agitation. Here, we disperse the solid particles of ALA and HCO in scCO2 at low temperatures and change the temperature stepwise in order to mix the melted ALA and HCO in scCO2. As a result, a homogeneous dispersion of the droplets of ALA in melted HCO saturated with CO2 is obtained at high temperatures. After the rapid expansion of the saturated solution through a nozzle, microcomposite particles of ALA/HCO several micrometers in diameter are obtained.

  19. Synthesis of single phase. alpha. -Fe, Fe sub 3 C and Fe sub 7 C sub 3 nano-particles by CO sub 2 laser pyrolysis technique

    SciTech Connect

    Eklund, P.C.; Bi, X.X.

    1992-01-01

    Iron-containing catalysts have been known to be useful in assisting the Fischer-Tropsch (FT) reaction for synthesizing hydrocarbons. However, it has been well recognized that iron catalyst are not stable during the reaction but converted into iron carbides. It is thus important to understand the role of the iron carbides in the catalytic reaction of the FT-synthesis. It has been found difficult to produce iron carbide nano-particles as a single phase, because iron carbide phases are only metastable under 1 atm pressure. Iron carbide bulk particles prepared so far are often contaminated with metallic iron, iron oxides and free carbon. In this study, we investigate the synthesis of iron carbide nano-particles using CO{sub 2} laser pyrolysis technique. We show that this technique is successful in synthesizing {alpha}-Fe, Fe{sub 3}C and Fe{sub 7}C{sub 3} nano-particles in their single phase with sizes in the range of 5--20nm. In particular, we have produced for the first time the Fe{sub 7}C{sub 3} which has been known to exist but unable to be produced as a single phase. Furthermore, it is interesting that Fe{sub 5}C{sub 2} which has carbon and iron ratio between Fe{sub 3}C and Fe{sub 7}C{sub 3}, is not seen in any run of our synthesis.

  20. Measurement of the OXYGEN-17(PROTON, Alpha Particle) Nitrogen -14 Cross Section at Stellar Energies (proton Energies, Resonant Reaction)

    NASA Astrophysics Data System (ADS)

    Blackmon, Jeffery Curtis

    The isotopic abundance ratio 16O/17O has been shown to be a good probe of mass flow and mixing in stars. This ratio is sensitive to the depth of convective mixing which occurs on the giant branch and to the amount of nonconvective mixing occurring on the main sequence. The interpretation of recent observations of this ratio in red giants is limited by a large uncertainty in the value of the 17O(p, alpha)14N reaction rate. This reaction rate is dominated at stellar energies by a resonance at E_{rm x} = 5673 keV in the compound nucleus 18 F, whose strength was previously uncertain. We have carried out a measurement of the ^ {17}O(p,alpha)^{14 }N cross section at proton energies of 75 keV and 65 keV. Thick, high-purity rm Ta_2O _5 targets enriched to 77% ^ {17}O were used in conjunction with beam currents of 0.45 mA and large-solid-angle detectors. The background for the experiment was measured using targets of natural isotopic composition. The resonance peak was observed in the data collected at 75 keV, and we determined the proton width of the 5673 keV state to be 22 +/- 4 neV. This implies a rate for the 17O(p,alpha)^ {14}N reaction that is ten times greater than the typical rates used previously in stellar models.

  1. Attenuation of the slow component of delayed rectification, action potential prolongation, and triggered activity in mice expressing a dominant-negative Kv2 alpha subunit.

    PubMed

    Xu, H; Barry, D M; Li, H; Brunet, S; Guo, W; Nerbonne, J M

    1999-10-01

    An in vivo experimental strategy, involving cardiac-specific expression of a mutant Kv 2.1 subunit that functions as a dominant negative, was exploited in studies focused on exploring the role of members of the Kv2 subfamily of pore-forming (alpha) subunits in the generation of functional voltage-gated K(+) channels in the mammalian heart. A mutant Kv2.1 alpha subunit (Kv2.1N216) was designed to produce a truncated protein containing the intracellular N terminus, the S1 membrane-spanning domain, and a portion of the S1/S2 loop. The truncated Kv2.1N216 was epitope tagged at the C terminus with the 8-amino acid FLAG peptide to generate Kv2. 1N216FLAG. No ionic currents are detected on expression of Kv2. 1N216FLAG in HEK-293 cells, although coexpression of this construct with wild-type Kv2.1 markedly reduced the amplitudes of Kv2. 1-induced currents. Using the alpha-myosin heavy chain promoter to direct cardiac specific expression of the transgene, 2 lines of Kv2. 1N216FLAG-expressing transgenic mice were generated. Electrophysiological recordings from ventricular myocytes isolated from these animals revealed that I(K, slow) is selectively reduced. The attenuation of I(K, slow) is accompanied by marked action potential prolongation, and, occasionally, spontaneous triggered activity (apparently induced by early afterdepolarizations) is observed. The time constant of inactivation of I(K, slow) in Kv2. 1N216FLAG-expressing cells (mean+/-SEM=830+/-103 ms; n=17) is accelerated compared with the time constant of I(K, slow) inactivation (mean+/-SEM=1147+/-57 ms; n=25) in nontransgenic cells. In addition, unlike I(K, slow) in wild-type cells, the component of I(K, slow) remaining in the Kv2.1N216FLAG-expressing cells is insensitive to 25 mmol/L tetraethylammonium. Taken together, these observations suggest that there are 2 distinct components of I(K, slow) in mouse ventricular myocytes and that Kv2 alpha subunits underlie the more slowly inactivating, tetraethylammonium

  2. The variation of protons, alpha particles, and the magnetic field across the bow shock of Comet Halley

    NASA Technical Reports Server (NTRS)

    Neugebauer, M.; Goldstein, B. E.; Goldstein, R.; Neubauer, F. M.; Balsiger, H.; Fuselier, S. A.

    1987-01-01

    Data from the Ion Mass Spectrometer and the magnetometer on the Giotto spacecraft are used to examine the structure of the inbound crossing of the Comet Halley bow shock on March 13, 1986. It is found that the velocity decrease, the field strength increase, and the heating of picked up cometary protons occurred over a broad region corresponding to several heavy-ion gyroradii. The solar-wind protons and alphas, on the other hand, were compressed and heated at a narrow structure on the leading edge of the broad shock region.

  3. Relating particle formation to salt- and pH-dependent phase separation of non-native aggregates of alpha-chymotrypsinogen A.

    PubMed

    Kroetsch, Andrew M; Sahin, Erinc; Wang, Hsiang-yun; Krizman, Sintia; Roberts, Christopher J

    2012-10-01

    Visible and subvisible particle formation during the storage of protein solutions is of increasing concern for pharmaceutical products. Previous work (Li Y, Ogunnaike BA, Roberts CJ. 2010. J Pharm Sci 99:645-662) showed that the model protein, alpha-chymotrypsinogen A (aCgn), forms non-native aggregates under accelerated (heated) conditions, but the size and morphology of the resulting aggregates depended sensitively on pH and NaCl. Here, it is shown that aggregates created as high-molecular-weight soluble aggregates undergo a pH- and salt-dependent reversible phase transition to a condensed or insoluble phase of suspended microparticles, whereas monomers remain completely soluble in the same regime. The location of the phase boundary is quantitatively consistent with the different regimes of kinetic behavior observed previously for aCgn. This suggests that the while kinetics is important for controlling the rates of monomer loss during non-native aggregation, it may be possible to tune solution thermodynamics and phase behavior to suppress otherwise soluble aggregates from propagating to form visible or large subvisible particles. Interestingly, the aggregate phase boundary is sensitive to the identity of salt anions in solution, highlighting the importance of electrostatics and preferential salt interactions in mediating aggregate condensation and particle formation.

  4. The alpha channeling effect

    SciTech Connect

    Fisch, N. J.

    2015-12-10

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

  5. Measurement and Modeling of Resistivity as a Microscale Tool to Quantify the Volume Fraction of Lenticular (alpha)' Particles in a Partially Transformed (delta)-phase Pu-Ga Matrix

    SciTech Connect

    Haslam, J J; Wall, M A; Johnson, D L; Mayhall, D J; Schwartz, A J

    2005-07-13

    We have measured and modeled the change in electrical resistivity due to partial transformation to the martensitic {alpha}{prime}-phase in a {delta}-phase Pu-Ga matrix. The primary objective is to relate the change in resistance, measured with a 4-probe technique during the transformation, to the volume fraction of the {alpha}{prime} phase created in the microstructure. Analysis by finite element methods suggests that considerable differences in the resistivity may be anticipated depending on the orientational and morphological configurations of the {alpha}{prime} particles. Finite element analysis of the computed resistance of an assembly of lenticular shaped particles indicates that series resistor or parallel resistor approximations are inaccurate and can lead to an underestimation of the predicted amount of {alpha}{prime} in the sample by 15% or more. Comparison of the resistivity of a simulated network of partially transformed grains or portions of grains suggests that a correction to the measured resistivity allows quantification of the amount of {alpha}{prime} phase in the microstructure with minimal consideration of how the {alpha}{prime} morphology may evolve. It is found that the average of the series and parallel resistor approximations provide the most accurate relationship between the measured resistivity and the amount of {alpha}{prime} phase. The methods described here are applicable to any evolving two-phase microstructure in which the resistance difference between the two phases is measurable.

  6. Scaling of cross sections for K-electron capture by high-energy protons and alpha-particles from the multielectron atoms

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1979-01-01

    Electron capture by protons from H, He, and the K shell of Ar, and electron capture by alpha particles from He are considered. Using the experimental data, a function of the capture cross section is formed. It is shown that when this function is plotted versus the inverse of the collision energies, at high energies a straight line is obtained. At lower energies the line is concave up or down, depending on the charge of the projectile and/or the effective charge and the ionization potential of the electron that is being captured. The plot can be used to predict cross sections where experimental data are not available, and as a guide in future experiments. High-energy scaling formulas for K-electron capture by low-charge projectiles are given.

  7. Scaling of cross sections for K-electron capture by high-energy protons and alpha-particles from the multielectron atoms

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1976-01-01

    Electron capture by protons from H, He, and the K-shell of Ar, and alpha particles from He are considered. It is shown that when a certain function of the experimental cross sections is plotted versus the inverse of the collision energy, at high energies the function falls on a straight line. At lower energies the function concaves up or down, depending on the charge of the projectile, the effective charge and the ionization potential of the electron that is being captured. The plot can be used to predict cross sections where experimental data are not available, and as a guide in future experiments. High energy scaling formulas for K-electron capture by low-charge projectiles are given.

  8. Two Years of Chemical Sampling on Meridiani Planum by the Alpha Particle X-Ray Spectrometer Onboard the Mars Exploration Rover Opportunity

    NASA Technical Reports Server (NTRS)

    Bruckner, J.; Gellert, R.; Clark, B.C.; Dreibus, G.; Rieder, R.; Wanke, H.; d'Uston, C.; Economou, T.; Klingelhofer, G.; Lugmair, G.; Ming, D.W.; Squyres, S.W.; Yen, A.; Zipfel, J.

    2006-01-01

    For over two terrestrial years, the Mars Exploration Rover Opportunity has been exploring the martian surface at Meridiani Planum using the Athena instrument payload [1], including the Alpha Particle X-Ray Spectrometer (APXS). The APXS has a small sensor head that is mounted on the robotic arm of the rover. The chemistry, mineralogy and morphology of selected samples were investigated by the APXS along with the Moessbauer Spectrometer (MB) and the Microscopic Imager (MI). The Rock Abrasion Tool (RAT) provided the possibility to dust and/or abrade rock surfaces down to several millimeters to expose fresh material for analysis. We report here on APXS data gathered along the nearly 6-kilometers long traverse in craters and plains of Meridiani.

  9. Study of LiOH etching of polyethyleneterephtalate irradiated with 11.4 MeV/amu Pb ions by neutron depth profiling and alpha particle transmission

    NASA Astrophysics Data System (ADS)

    Vacík, J.; Červená, J.; Hnatowicz, V.; Fink, D.; Strauss, P.

    1998-12-01

    Polyethyleneterephtalate (PETP) foils, 23 μm thick, irradiated with 11.4 MeV/amu Pb ions to the fluence of about 1 × 107 cm-2 were etched in 5M LiOH solution at the temperature of 40°C for 30-570 min and the etching process kinetics was examined by combined alpha particle transmission (APT) and neutron depth profiling (NDP) techniques. The etching process was visualized from very initial stages up to the breakthrough and the appearance of first openings after about 300 min of etching. Several parameters characterizing the etching process were determined and the pore internal profile was determined by comparing the measured APT spectra with those simulated by Monte-Carlo method.

  10. Tissue distribution and radiation dosimetry of astatine-211-labeled chimeric 81C6, an alpha-particle-emitting immunoconjugate.

    PubMed

    Zalutsky, M R; Stabin, M G; Larsen, R H; Bigner, D D

    1997-04-01

    A paired-label study was performed in athymic mice bearing subcutaneous D-54 MG human glioma xenografts to compare the localization of human/mouse anti-tenascin chimeric antibody 81C6 labeled by reaction with N-succinimidyl 3-[211At]astatobenzoate and N-succinimidyl 3-[131I]iodobenzoate. Over the 48-h observation period, the distribution of 211At- and 131I-labeled antibody were quite similar in tumor and normal tissues except stomach. These data were used to calculate human radiation doses for both intravenously and intrathecal administered 211At-labeled chimeric 81C6 using a quality factor of 5 for alpha-emissions.

  11. Downhole delay assembly for blasting with series delay

    DOEpatents

    Ricketts, Thomas E.

    1982-01-01

    A downhole delay assembly is provided which can be placed into a blasthole for initiation of explosive in the blasthole. The downhole delay assembly includes at least two detonating time delay devices in series in order to effect a time delay of longer than about 200 milliseconds in a round of explosions. The downhole delay assembly provides a protective housing to prevent detonation of explosive in the blasthole in response to the detonation of the first detonating time delay device. There is further provided a connection between the first and second time delay devices. The connection is responsive to the detonation of the first detonating time delay device and initiates the second detonating time delay device. A plurality of such downhole delay assemblies are placed downhole in unfragmented formation and are initiated simultaneously for providing a round of explosive expansions. The explosive expansions can be used to form an in situ oil shale retort containing a fragmented permeable mass of formation particles.

  12. Evaluation of internal alpha-particle radiation exposure and subsequent fertility among a cohort of women formerly employed in the radium dial industry

    SciTech Connect

    Schieve, L.A.; Davis, F.; Freels, S.

    1997-02-01

    This study examined the effect of internal exposure to {alpha}-particle radiation on subsequent fertility among women employed in radium dial industry prior to 1930, when appreciable amounts of radium were often ingested through the practice of pointing the paint brush with the lips. The analysis was limited to women for whom a radium body burden measurement had been obtained and who were married prior to age 45 (n = 603). Internal radiation dose to the ovary was calculated based on initial intakes of radium-226 and radium-228, average ovarian mass, number and energy of {alpha} particles emitted, fraction of energy absorbed within the ovary, effective retention integrals and estimated photon irradiation. Time between marriage and pregnancy, number of pregnancies and number of live births served as surrogates for fertility. Radiation appeared to have no effect on fertility at estimated cumulative ovarian dose equivalents below 5 Sv; above this dose, however, statistically significant declines in both number of pregnancies and live births were observed. These trends persisted after multivariable adjustment for potential confounding variables and after exclusion of subjects contributing a potential classification or selection bias to the study. Additionally, the high-dose group experienced fewer live births than would have been expected based on population rates. There were no differences in time to first pregnancy between high- and low-dose groups. These results are consistent with earlier studies of {gamma}-ray exposures and suggest that exposure to high doses of radiation from internally deposited radium reduces fertility rather than inducing sterility. 42 refs., 5 tabs.

  13. Delayed ejaculation

    MedlinePlus

    Ejaculatory incompetence; Sex - delayed ejaculation; Retarded ejaculation; Anejaculation; Infertility - delayed ejaculation ... include: Religious background that makes the person view sex as sinful Lack of attraction for a partner ...

  14. ALPHA CONTAMINATION MONITORING

    DTIC Science & Technology

    This project was conducted to determine the alpha hazard existing in the vicinity of the missile launch pad following the destruction of a missile ...were used for plutonium particle collection. Because all warhead-carrying missiles were properly launched after Project 2.3 was approved, no alpha contamination data was obtained.

  15. Particle impact location detector

    NASA Technical Reports Server (NTRS)

    Auer, S. O.

    1974-01-01

    Detector includes delay lines connected to each detector surface strip. When several particles strike different strips simultaneously, pulses generated by each strip are time delayed by certain intervals. Delay time for each strip is known. By observing time delay in pulse, it is possible to locate strip that is struck by particle.

  16. The Alpha Particle X-Ray Spectrometer APXS on the Rosetta lander Philae to explore the surface of comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Klingelhoefer, Goestar; Girones Lopez, Jordi; Schmanke, Dirk; Markovski, Cristina; Brückner, Johannes; d'Uston, Claude; Economu, Tom; Gellert, Ralf

    2015-04-01

    The Rosetta Mission was launched in 2004 with the main objectives to gain a better understanding of the origin and formation of comets and the solar system. After 10 years of cruise Rosetta rendevouded with the comet 67P/Churyumov-Gerasimenko in 2014 to study the nucleus of the comet and its environment. Rosetta consists of an orbiter and a lander (Philae) with 11 and 9 scientific experiments respectively. It did what has never been attempted before, orbiting and landing on a comet. After orbit insertion in August 2014, the main spacecraft will follow the comet for several months to investigate its surface. Subsequently, Philae has been deployed for a safe landing. As part of the lander payload the APXS will measure in situ the chemical composition of the comet's surface and it's changes during the journey of the comet around the sun. The data obtained with the APXS will be used to characterize the surface of the comet, to determine the chemical composition of the dust component, and to compare the dust with known meteorite types. APXS combines an alpha mode for alpha backscattering spectroscopy and an x-ray mode for alpha particle/x-ray induced x-ray spectroscopy (XRF) in one single instrument, being low in mass (640g) and power consumption (1.5 W in operating mode) [4]. The comet surface will be irradiated by a Curium 244 source exciting characteristic x-rays of the elements present in the surface material. The alpha mode will allow detection of elements like C and O and groups of elements with a higher Z. The x-ray-SD-detector will allow the detection of most of the elements from Na up to Ni and above. The design of the Rosetta APX spectrometer is based on the experience gained with the APXS built for Russian and American Mars missions: Mars 96 spacecraft and Mars Pathfinder, MPF [1]. Two APXS were also built for the Mars Exploration Rovers mission of the NASA, MER [2-3]. Acknowledgements This project is funded by the German Space Agency DLR under contracts 50

  17. First In Vivo Evaluation of Liposome-encapsulated 223Ra as a Potential Alpha-particle-emitting Cancer Therapeutic Agent

    SciTech Connect

    Jonasdottir, Thora J.; Fisher, Darrell R.; Borrebaek, Jorgen; Bruland, Oyvind S.; Larsen, Roy H.

    2006-09-13

    Liposomes carrying chemotherapeutics have had some success in cancer treatment and may be suitable carriers for therapeutic radionuclides. This study was designed to evaluate the biodistribution of and to estimate the radiation doses from the alpha emitter 223Ra loaded into pegylated liposomes in selected tissues. 223Ra was encapsulated in pegylated liposomal doxorubicin by ionophore-mediated loading. The biodistribution of liposomal 223Ra was compared to free cationic 223Ra in Balb/C mice. We showed that liposomal 223 Ra circulated in the blood with an initial half-time in excess of 24 hours, which agreed well with that reported for liposomal doxorubicin in rodents, while the blood half-time of cationic 223Ra was considerably less than one hour. When liposomal 223 Ra was catabolized, the released 223Ra was either excreted or taken up in the skeleton. This skeletal uptake increased up to 14 days after treatment, but did not reach the level seen with free 223Ra. Pre-treatment with non-radioactive liposomal doxorubicin 4 days in advance lessened the liver uptake of liposomal 223 Ra. Dose estimates showed that the spleen, followed by bone surfaces, received the highest absorbed doses. Liposomal 223 Ra was relatively stable in vivo and may have potential for radionuclide therapy and combination therapy with chemotherapeutic agents.

  18. Preparation and optimization of CdWO4-polymer nano-composite film as an alpha particle counter

    NASA Astrophysics Data System (ADS)

    Ziluei, Hossein; Azimirad, Rouhollah; Mojtahedzadeh Larijani, Majid; Ziaie, Farhoud

    2017-04-01

    In this research work, CdWO4/polymer composite films with different thicknesses were prepared using Poly-methyl acrylate polymer and synthesized CdWO4 powder. The CdWO4 powder was synthesized by a simple co-precipitation method in the laboratory. X-ray diffraction, photoluminescence, Fourier transformed infrared spectroscopy and energy-dispersive X-ray spectroscopy proved that the CdWO4 powder was successfully prepared. Moreover, photoluminescence analysis showed that adding polymer does not change the emission peak of CdWO4. Also, the responses of all samples were measured using an 241Am alpha source with 1860 Bq activity. Results showed that the sample having thickness of 177 mg/cm2 has the best counting efficiency (over 2π geometry) among the others. The efficiency measurement was further evaluated using a 230Th source whose activity is 190.7 Bq. It revealed that the counting efficiency of this sample for both 241Am and 230Th was nearly equal.

  19. Properties of poly(styrene/alpha-tert-butoxy-omega-vinylbenzyl-polyglycidol) microspheres suspended in water. Effect of sodium chloride and temperature on particle diameters and electrophoretic mobility.

    PubMed

    Basinska, Teresa; Slomkowski, Stanislaw; Kazmierski, Slawomir; Chehimi, Mohamed M

    2008-08-19

    Hydrodynamic and electrophoretic properties of core-shell poly(styrene/alpha- tert-butoxy-omega-vinylbenzyl-polyglycidol) (P(S/PGL)) microspheres suspended in water are described. The microspheres were obtained by surfactant-free emulsion copolymerization of styrene and alpha- tert-butoxy-omega-vinylbenzyl-polyglycidol macromonomer ( M n = 2800, M w/ M n = 1.05). The process yielded microspheres with number average diameter D n = 270 nm and with low diameter dispersity index D w/ D n = 1.01. Shells of P(S/PGL) microspheres were enriched in polyglycidol. Molar fraction of polyglycidol monomeric units in the shells (determined by X-ray photoelectron spectroscopy) was equal to 0.34, which is much higher than the average molar fraction of polyglycidol monomeric units in whole particles of 0.048. Influences of NaCl concentration and temperature on P(S/PGL) microsphere diameters and on their electrophoretic mobility were investigated. It was found that hydrodynamic diameter of P(S/PGL) microspheres, determined by photon correlation spectroscopy, decreased significantly when temperature did exceed a certain value (transition temperature, T t). It has been found that the decrease is more pronounced for higher concentrations of NaCl in the medium. For microspheres suspended in 10 (-1) M NaCl, the hydrodynamic diameter decreased by 8% whereas for the same particles in pure water the diameter decreased by 5.2%. The process of shrinkage was fully reversible. Values of T t for P(S/PGL) microspheres were lower for higher concentrations of NaCl. Adjustment of salt concentration allowed controlling T t in a range from 44.4 to 49.9 degrees C. 13C NMR relaxation time measurements (T 1) for carbon atoms in polyglycidol macromonomer revealed that T 1 did increase with increasing temperature (in temperature range from 25 to 75 degrees C) indicating higher motion of chains at higher temperature. Addition of NaCl did not induce a substantial change of T 1 in the mentioned temperature

  20. Determination of the uniformity of uranium fission deposits using Rutherford backscattering spectrometry and alpha-particle scanning

    NASA Astrophysics Data System (ADS)

    Wasson, O. A.; Schrack, R. A.

    1989-10-01

    The uniformity of the areal density of uranium deposits used in neutron induced fission cross-section measurements has been measured using Rutherford backscattering spectrometry of 1-MeV He + ions as well as by scanning the natural α-particle decay of the uranium. The measurements used the 3-MV positive-ion accelerator at the National Institute of Standards and Technology along with a versatile scattering chamber with numerous ports, five-axis goniometer, target ladder, and solid state detector. The variation in areal density of a 265- μg/cm 3 UO 2 deposit with a diameter of 89 mm was measured using the 1-MeV He + beam. The results are in excellent agreement with those obtained from α-particle activity measurements. However, the Rutherford backscattering data provide better definition of the uniformity near the edge of the deposits. Our experience indicates that the backscatter technique is useful for measuring variations of 1% in areal densities but is less sensitive to the absolute areal density. The stoichiometry of the deposit was additionally measured with X-ray diffraction.

  1. Alpha-Lipoic Acid Reduces LDL-Particle Number and PCSK9 Concentrations in High-Fat Fed Obese Zucker Rats

    PubMed Central

    Carrier, Bradley; Wen, Shin; Zigouras, Sophia; Browne, Richard W.; Li, Zhuyun; Patel, Mulchand S.; Williamson, David L.; Rideout, Todd C.

    2014-01-01

    We characterized the hypolipidemic effects of alpha-lipoic acid (LA, R-form) and examined the associated molecular mechanisms in a high fat fed Zucker rat model. Rats (n = 8) were assigned to a high fat (HF) diet or the HF diet with 0.25% LA (HF-LA) for 30 days and pair fed to remove confounding effects associated with the anorectic properties of LA. Compared with the HF controls, the HF-LA group was protected against diet-induced obesity (102.5±3.1 vs. 121.5±3.6,% change BW) and hypercholesterolemia with a reduction in total-C (−21%), non-HDL-C (−25%), LDL-C (−16%), and total LDL particle number (−46%) and an increase in total HDL particles (∼22%). This cholesterol-lowering response was associated with a reduction in plasma PCSK9 concentration (−70%) and an increase in hepatic LDLr receptor protein abundance (2 fold of HF). Compared with the HF-fed animals, livers of LA-supplemented animals were protected against TG accumulation (−46%), likely through multiple mechanisms including: a suppressed lipogenic response (down-regulation of hepatic acetyl-CoA carboxylase and fatty acid synthase expression); enhanced hepatic fat oxidation (increased carnitine palmitoyltransferase Iα expression); and enhanced VLDL export (increased hepatic diacylglycerol acyltransferase and microsomal triglyceride transfer protein expression and elevated plasma VLDL particle number). Study results also support an enhanced fatty acid uptake (2.8 fold increase in total lipase activity) and oxidation (increased CPT1β protein abundance) in muscle tissue in LA-supplemented animals compared with the HF group. In summary, in the absence of a change in caloric intake, LA was effective in protecting against hypercholesterolemia and hepatic fat accumulation under conditions of strong genetic and dietary predisposition toward obesity and dyslipidemia. PMID:24595397

  2. Viva Delay.

    PubMed

    Yahaghi, Hossein; Sorooshian, Shahryar; Yahaghi, Javad

    2016-06-28

    The time delay between submission of a thesis and Viva Voce is intolerable for students. This letter tries to draw the readers' attention to the effect of choosing the right examiner, in order to reduce the Viva Voce delay.

  3. On the features of bursts of neutrons, hard x-rays and alpha-particles in the pulse vacuum discharge with a virtual cathode and self-organization

    NASA Astrophysics Data System (ADS)

    Kurilenkov, Yu K.; Tarakanov, V. P.; Gus'kov, S. Yu; Samoylov, I. S.; Ostashev, V. E.

    2015-11-01

    In this paper, we continue the discussion of the experimental results on the yield of DD neutrons and hard x-rays in the nanosecond vacuum discharge (NVD) with a virtual cathode, which was started in the previous article of this issue, and previously (Kurilenkov Y K et al 2006 J. Phys. A: Math. Gen. 39 4375). We have considered here the regimes of very dense interelectrode aerosol ensembles, in which diffusion of even hard x-rays is found. The yield of DD neutrons in these regimes is conditioned not only by the head-on deuteron-deuteron collisions in the potential well of virtual cathode, but also by the channel of “deuteron-deuterium cluster” reaction, which exceeds overall yield of neutrons per a shot by more than an order of magnitude, bringing it up to ∼ 107/(4π). Very bright bursts of hard x-rays are also represented and discussed here. Presumably, their nature may be associated with the appearance in the NVD of some properties of random laser in the x-ray spectrum. Good preceding agreeing of the experiment on the DD fusion in the NVD with its particle-in-cell (PIC) simulations provides a basis to begin consideration of nuclear burning “proton-boron” in the NVD, which will be accompanied by the release of alpha particles only. With this objective in view, there has been started the PIC-simulation of aneutronic burning of p-B11, and its preliminary results are presented.

  4. Evidence of extranuclear cell sensitivity to alpha-particle radiation using a microdosimetric model. I. Presentation and validation of a microdosimetric model.

    PubMed

    Chouin, N; Bernardeau, K; Davodeau, F; Chérel, M; Faivre-Chauvet, A; Bourgeois, M; Apostolidis, C; Morgenstern, A; Lisbona, A; Bardiès, M

    2009-06-01

    A microdosimetric model that makes it possible to consider the numerous biological and physical parameters of cellular alpha-particle irradiation by radiolabeled mAbs was developed. It allows for the calculation of single-hit and multi-hit distributions of specific energy within a cell nucleus or a whole cell in any irradiation configuration. Cells are considered either to be isolated or to be packed in a monolayer or a spheroid. The method of calculating energy deposits is analytical and is based on the continuous-slowing-down approximation. A model of cell survival, calculated from the microdosimetric spectra and the microdosimetric radiosensitivity, z(0), was also developed. The algorithm of calculations was validated by comparison with two general Monte Carlo codes: MCNPX and Geant4. Microdosimetric spectra determined by these three codes showed good agreement for numerous geometrical configurations. The analytical method was far more efficient in terms of calculation time: A gain of more than 1000 was observed when using our model compared with Monte Carlo calculations. Good agreements were also observed with previously published results.

  5. Excitation function of the alpha particle induced nuclear reactions on enriched 116Cd, production of the theranostic isotope 117mSn

    NASA Astrophysics Data System (ADS)

    Ditrói, F.; Takács, S.; Haba, H.; Komori, Y.; Aikawa, M.; Szűcs, Z.; Saito, M.

    2016-10-01

    117mSn is one of the radioisotopes can be beneficially produced through alpha particle irradiation. The targets were prepared by deposition of 116Cd metal onto high purity 12 μm thick Cu backing. The average deposited thickness was 21.9 μm. The beam energy was thoroughly measured by Time of Flight (TOF) methods and proved to be 51.2 MeV. For the experiment the well-established stacked foil technique was used. In addition to the Cd targets, Ti foils were also inserted into the stacks for energy and intensity monitoring. The Cu backings were also used for monitoring and as recoil catcher of the reaction products from the cadmium layer. The activities of the irradiated foils were measured with HPGe detector for gamma-ray spectrometry and cross section values were determined. As a result excitation functions for the formation of 117mSn, 117m,gIn, 116mIn, 115mIn and 115m,gCd from enriched 116Cd were deduced and compared with the available literature data and with the results of the nuclear reaction model code calculations EMPIRE 3.2 and TALYS 1.8. Yield curves were also deduced for the measured nuclear reactions and compared with the literature.

  6. Overview of Mars surface geochemical diversity through Alpha Particle X-Ray Spectrometer data multidimensional analysis: First attempt at modeling rock alteration

    NASA Astrophysics Data System (ADS)

    Tréguier, Erwan; d'Uston, Claude; Pinet, Patrick C.; Berger, Gilles; Toplis, Michael J.; McCoy, Timothy J.; Gellert, Ralf; Brückner, Johannes

    2008-11-01

    Principal component analysis and a hierarchical clustering method have been employed to describe and quantify the compositional variability of Martian rocks and soils measured by the Alpha Particle X-Ray Spectrometers onboard the Mars Exploration Rovers. A robust classification of samples emerges which defines distinct rock classes and sheds light on the petrogenetic relationships between rocks. This is particularly useful in the case of rocks from Gusev Crater, where significant chemical diversity is observed. This approach also highlights that compositional variability of rocks at Meridiani is dominated by variations in sulfur content; the relative proportions of other elements remaining approximately constant. For soils, variations in Fe concentration dominate because of the presence of hematite-rich ``berry''-bearing samples. On the basis of this observation, a simple geochemical model of acid fog alteration of Martian basalts has been tested, assuming either equivalent alteration of all phases or preferential alteration of certain phases (thus taking into account kinetic considerations). The results show that for certain ranges of SO3/basalt, many of the compositional and mineralogical features measured at both sites may be explained. The secondary mineralogy and bulk rock compositions predicted by the model are broadly consistent with rock and soil compositions from Gusev and Meridiani, especially if the role of brine circulation and evaporation are considered. Although agreement is not perfect, comparison of observations and models argues in favor of variable interaction of the Martian surface with sour gas, explaining the high local abundance of sulfates, for example.

  7. Membrane-Dependent Bystander Effect Contributes to Amplification of the Response to Alpha-Particle Irradiation in Targeted and Nontargeted Cells

    SciTech Connect

    Hanot, Maite; Hoarau, Jim; Carriere, Marie; Angulo, Jaime F.; Khodja, Hicham

    2009-11-15

    Purpose: Free radicals are believed to play an active role in the bystander response. This study investigated their origin as well as their temporal and spatial impacts in the bystander effect. Methods and Materials: We employed a precise alpha-particle microbeam to target a small fraction of subconfluent osteoblastic cells (MC3T3-E1). gammaH2AX-53BP1 foci, oxidative metabolism changes, and micronuclei induction in targeted and bystander cells were assessed. Results: Cellular membranes and mitochondria were identified as two distinct reactive oxygen species producers. The global oxidative stress observed after irradiation was significantly attenuated after cells were treated with filipin, evidence for the primal role of membrane in the bystander effect. To determine the membrane's impact at a cellular level, micronuclei yield was measured when various fractions of the cell population were individually targeted while the dose per cell remained constant. Induction of micronuclei increased in bystander cells as well as in targeted cells and was attenuated by filipin treatment, demonstrating a role for bystander signals between irradiated cells in an autocrine/paracrine manner. Conclusions: A complex interaction of direct irradiation and bystander signals leads to a membrane-dependent amplification of cell responses that could influence therapeutic outcomes in tissues exposed to low doses or to environmental exposure.

  8. The relationship between internally deposited alpha-particle radiation and subsite-specific liver cancer and liver cirrhosis: an analysis of published data.

    PubMed

    Sharp, Gerald B

    2002-12-01

    Chronic exposure to high LET radiation has been shown to cause liver cancer in humans based on studies of patients who received Thorotrast, a colloidal suspension of thorium dioxide formerly used as a radiological contrast agent, and on studies of Russian nuclear weapons workers exposed to internally ingested plutonium. Risk estimates for these exposures and specific subtypes of liver cancer have not been previously reported. Combining published data with tumor registry data pertinent to the Thorotrast cohorts in Germany, Denmark, Portugal, and Japan and to Russian workers, we generally found significantly elevated risks of three major histologic types of liver tumors: hepatocellular carcinoma (HCC), cholangiocarcinoma (CC), and hemangiosarcoma (HS) for Thorotrast exposures. In contrast, HS was the only liver tumor significantly associated with the lower alpha-particle doses experienced by the Russian workers. Excess cases per 1,000 persons exposed to Thorotrast were similar for the three liver cancer subtypes but lower for plutonium exposure. Odds ratios (OR) of HS and CC for Thorotrast were from 26 to 789 and from 1 to 31 times higher than those for HCC, respectively. ORs of liver cirrhosis for Thorotrast exposure ranged from 2.7 (95% confidence interval (CI): 2.2-3.4) to 6.7 (5.1-8.7).

  9. Coulomb-nuclear interference with {alpha} particles in the excitation of the 2{sup +}{sub 1} states in {sup 100,102,104}Ru

    SciTech Connect

    Gomes, L.C.; Horodynski-Matsushigue, L.B.; Borello-Lewin, T.; Duarte, J.L.; Hirata, J.H.; Salem-Vasconcelos, S.; Dietzsch, O.

    1996-11-01

    Coulomb-nuclear interference data for incident energies between 9 and 17 MeV were obtained in the form of elastic and inelastic (to the 2{sup +}{sub 1} states) excitation functions of backscattered ({theta}{approx_equal}172.8{degree}) alpha particles on {sup 100,102,104}Ru. The analysis was done in a distorted-wave Born approximation within a deformed optical model approach. {ital B}({ital E}2) values, obtained from the charge deformation lengths {delta}{sup {ital C}} extracted from the low energy data, are compatible for the three isotopes within {approximately} 2{sigma} with published values. The nuclear quadrupolar deformation lengths {delta}{sup {ital N}}, obtained from the analysis of the interference region of the excitation functions, and also of one angular distribution at 22 MeV measured for {sup 100}Ru are generally lower than the corresponding charge deformation lengths, the difference increasing with increasing {ital A} of the isotope, {delta}{sup {ital N}} being 18{percent} lower than {delta}{sup {ital C}} for {sup 104}Ru (2{sup +}{sub 1}). Nuclear deformation lengths associated with the 3{sub 1}{sup {minus}} states of {sup 100,102,104}Ru and with the 4{sup +}{sub 2} state of {sup 100}Ru at 2.367 MeV were also obtained as a by-product of the present work. {copyright} {ital 1996 The American Physical Society.}

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

    PubMed

    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.

  11. Geochemical properties of rocks and soils in Gusev Crater, Mars: Results of the Alpha Particle X-Ray Spectrometer from Cumberland Ridge to Home Plate

    NASA Astrophysics Data System (ADS)

    Ming, D. W.; Gellert, R.; Morris, R. V.; Arvidson, R. E.; Brückner, J.; Clark, B. C.; Cohen, B. A.; d'Uston, C.; Economou, T.; Fleischer, I.; Klingelhöfer, G.; McCoy, T. J.; Mittlefehldt, D. W.; Schmidt, M. E.; Schröder, C.; Squyres, S. W.; Tréguier, E.; Yen, A. S.; Zipfel, J.

    2008-12-01

    Geochemical diversity of rocks and soils has been discovered by the Alpha Particle X-Ray Spectrometer (APXS) during Spirit's journey over Husband Hill and down into the Inner Basin from sol 470 to 1368. The APXS continues to operate nominally with no changes in calibration or spectral degradation over the course of the mission. Germanium has been added to the Spirit APXS data set with the confirmation that it occurs at elevated levels in many rocks and soils around Home Plate. Twelve new rock classes and two new soil classes have been identified at the Spirit landing site since sol 470 on the basis of the diversity in APXS geochemistry. The new rock classes are Irvine (alkaline basalt), Independence (low Fe outcrop), Descartes (outcrop similar to Independence with higher Fe and Mn), Algonquin (mafic-ultramafic igneous sequence), Barnhill (volcaniclastic sediments enriched in Zn, Cl, and Ge), Fuzzy Smith (high Si and Ti rock), Elizabeth Mahon (high Si, Ni, and Zn outcrop and rock), Halley (hematite-rich outcrop and rock), Montalva (high K, hematite-rich rock), Everett (high Mg, magnetite-rich rock), Good Question (high Si, low Mn rock), and Torquas (high K, Zn, and Ni magnetite-rich rock). New soil classes are Gertrude Weise (very high Si soil) and Eileen Dean (high Mg, magnetite-rich soil). Aqueous processes have played a major role in the formation and alteration of rocks and soils on Husband Hill and in the Inner Basin.

  12. Refinement of the Compton-Rayleigh scatter ratio method for use on the Mars Science Laboratory alpha particle X-ray spectrometer: II - Extraction of invisible element content

    NASA Astrophysics Data System (ADS)

    Perrett, Glynis M.; Campbell, John L.; Gellert, Ralf; King, Penelope L.; Nield, Emily; O'Meara, Joanne M.; Pradler, Irina

    2016-02-01

    The intensity ratio C/R between Compton and Rayleigh scatter peaks of the exciting Pu L X-rays in the alpha particle X-ray spectrometer (APXS) is strongly affected by the presence of very light elements such as oxygen which cannot be detected directly by the APXS. C/R values are determined along with element concentrations by fitting APXS spectra of geochemical reference materials (GRMs) with the GUAPX code. A quantity K is defined as the ratio between the C/R value determined by Monte Carlo simulation based on the measured element concentrations and the fitted C/R value from the spectrum. To ensure optimally accurate K values, the choice of appropriate GRMs is explored in detail, with attention paid to Rb and Sr, whose characteristic Kα X-ray peaks overlap the Pu Lα scatter peaks. The resulting relationship between the ratio K and the overall oxygen fraction is linear. This provides a calibration from which the concentration of additional light invisible constituents (ALICs) such as water may be estimated in unknown rock and conglomerate samples. Several GRMs are used as 'unknowns' in order to evaluate the accuracy of ALIC concentrations derived in this manner.

  13. Refinement of the Compton-Rayleigh scatter ratio method for use on the Mars Science Laboratory alpha particle X-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Campbell, J. L.; Perrett, G. M.; Maxwell, J. A.; Nield, E.; Gellert, R.; King, P. L.; Lee, M.; O'Meara, J. M.; Pradler, I.

    2013-05-01

    Spectra from the Mars rover alpha particle X-ray spectrometers contain the elastic and inelastic scatter peaks of the plutonium L X-rays emitted by the instrument's 244Cm source. Various spectrum fitting approaches are tested using the terrestrial twin of the APXS instrument on the Mars Science Laboratory Curiosity rover, in order to provide accurate extraction of the Lα and Lβ Compton/Rayleigh intensity ratios, which can provide information about light "invisible" constituents such as water in geological samples. A well-defined dependence of C/R ratios upon mean sample atomic number is established using a large and varied set of geochemical reference materials, and the accuracy of this calibration is examined. Detailed attention is paid to the influence of the rubidium and strontium peaks which overlap the Lα scatter peaks. Our Monte Carlo simulation code for prediction of C/R ratios from element concentrations is updated. The ratio between measured and simulated C/R ratios provides a second means of calibration.

  14. Labeling monoclonal antibodies and F(ab')2 fragments with the alpha-particle-emitting nuclide astatine-211: preservation of immunoreactivity and in vivo localizing capacity.

    PubMed Central

    Zalutsky, M R; Garg, P K; Friedman, H S; Bigner, D D

    1989-01-01

    alpha-Particles such as those emitted by 211At may be advantageous for radioimmunotherapy since they are radiation of high linear energy transfer, depositing high energy over a short distance. Here we describe a strategy for labeling monoclonal antibodies and F(ab')2 fragments with 211At by means of the bifunctional reagent N-succinimidyl 3-(trimethylstannyl)benzoate. An intact antibody, 81C6, and the F(ab')2 fragment of Me1-14 (both reactive with human gliomas) were labeled with 211At in high yield and with a specific activity of up to 4 mCi/mg in a time frame compatible with the 7.2-hr half-life of 211At. Quantitative in vivo binding assays demonstrated that radioastatination was accomplished with maintenance of high specific binding and affinity. Comparison of the biodistribution of 211At-labeled Me1-14 F(ab')2 to that of a nonspecific antibody fragment labeled with 211At and 131I in athymic mice bearing D-54 MG human glioma xenografts demonstrated selective and specific targeting of 211At-labeled antibody in this human tumor model. PMID:2476813

  15. Analysis of plutonium isotope ratios including (238)Pu/(239)Pu in individual U-Pu mixed oxide particles by means of a combination of alpha spectrometry and ICP-MS.

    PubMed

    Esaka, Fumitaka; Yasuda, Kenichiro; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki

    2017-04-01

    Isotope ratio analysis of individual uranium-plutonium (U-Pu) mixed oxide particles contained within environmental samples taken from nuclear facilities is proving to be increasingly important in the field of nuclear safeguards. However, isobaric interferences, such as (238)U with (238)Pu and (241)Am with (241)Pu, make it difficult to determine plutonium isotope ratios in mass spectrometric measurements. In the present study, the isotope ratios of (238)Pu/(239)Pu, (240)Pu/(239)Pu, (241)Pu/(239)Pu, and (242)Pu/(239)Pu were measured for individual Pu and U-Pu mixed oxide particles by a combination of alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). As a consequence, we were able to determine the (240)Pu/(239)Pu, (241)Pu/(239)Pu, and (242)Pu/(239)Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of plutonium with UTEVA resins. Furthermore, (238)Pu/(239)Pu isotope ratios were able to be calculated by using both the (238)Pu/((239)Pu+(240)Pu) activity ratios that had been measured through alpha spectrometry and the (240)Pu/(239)Pu isotope ratios determined through ICP-MS. Therefore, the combined use of alpha spectrometry and ICP-MS is useful in determining plutonium isotope ratios, including (238)Pu/(239)Pu, in individual U-Pu mixed oxide particles.

  16. Alpha voltaic batteries and methods thereof

    NASA Technical Reports Server (NTRS)

    Raffaelle, Ryne P. (Inventor); Jenkins, Phillip (Inventor); Wilt, David (Inventor); Scheiman, David (Inventor); Chubb, Donald (Inventor); Castro, Stephanie (Inventor)

    2011-01-01

    An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material.

  17. Improvements to the on-line mass separator, RAMA, and the beta-delayed charged-particle emission of proton-rich sd shell nuclei

    SciTech Connect

    Ognibene, Theodore Joseph

    1996-03-01

    To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of 31Cl, 27P and 28P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas ΔE-gas ΔE-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in 31Cl and 27P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of 31Cl were shown to be from the decay of 25Si. In 27P, two proton groups at 459 ± 14 keV and 610 ± 11 keV, with intensities of 7 ± 3% and 92 ± 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the β-decay of 28P, at 1,444 ± 12 keV with a 1.7 ± 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, 17Ne and 33Ar, were studied. A new proton group with energy 729 ± 15 keV was observed following the beta-decay of 17Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from 17Ne and 33Ar were resolved.

  18. Interpretation of cytogenetic damage induced in the germ line of male mice exposed for over 1 year to /sup 239/Pu alpha particles, fission neutrons, or /sup 60/Co gamma rays

    SciTech Connect

    Grahn, D.; Lee, C.H.; Farrington, B.F.

    1983-09-01

    The relative biological effectiveness (RBE) of /sup 239/Pu alpha particles, fission neutrons (0.85 MeV), and /sup 60/Co gamma rays has been evaluated for the induction of reciprocal chromosome translocations in spermatogonia and of chromosome/chromatid fragments and chromatid rearrangements in the primary spermatocyte of adult male B6CF1 mice. Age concurrency was maintained for both internal and external radiations which were delivered at about 1 rad/week for /sup 239/Pu (single intravenous dose of 10 microCi/kg), 0.67, 1.67, and 2.67 rad/week for neutrons, and 6.95, 17.4, and 32 rad/week for gamma rays for at least 60 weeks. In terms of frequency of translocations, the response to the alpha emitter was nonlinear (concave downward) with little dose-response predictability; to cumulative neutron exposures the response was linear, without evidence of a dose-rate effect; and to gamma radiation the responses were linear, and a significant dose-rate effect was seen. RBE estimates are variable. For translocations, the n/gamma ratio is between 10 and 24, depending upon weekly dose level, and the ratio is 1 or less for the alpha particle relative to the neutron. For fragments, the n/gamma ratio is 18 to 22, depending upon age factors, and alpha/n is 1.5. For chromatid rearrangements, n/gamma is 7 and alpha/n is essentially indeterminate, but much below one. The overall response to the alpha emitter is interpreted to be a complex function of (a) microdosimetric heterogeneity, (b) a nearly invariant deposition pattern in the gonad, (c) the high sensitivity of differentiating spermatogonia to cell killing, and (d) the capacity of stem cells in relatively radiation-free areas to progressively assume the major spermatogenic role.

  19. Event counting alpha detector

    DOEpatents

    Bolton, Richard D.; MacArthur, Duncan W.

    1996-01-01

    An electrostatic detector for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure.

  20. Event counting alpha detector

    DOEpatents

    Bolton, R.D.; MacArthur, D.W.

    1996-08-27

    An electrostatic detector is disclosed for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure. 6 figs.

  1. [Delayed puberty].

    PubMed

    Edouard, T; Tauber, M

    2010-02-01

    Delayed puberty is defined in girls by the absence of breast development beyond 13 years old and in boys by the absence of testicular enlargement (< 4 ml) beyond 14 years old. Simple investigations lead to the diagnosis of central or peripheral hypogonadism and constitutional delay of puberty. In girls, delayed puberty is rare and often organic, and then Turner syndrome should be systematically suspected. In boys, delayed puberty is often constitutional and functional. Treatment is etiologic when possible, hormonal replacement therapy (oestrogen in girls and testosterone in boys) and psychological management.

  2. Treatment of HER2-Expressing Breast Cancer and Ovarian Cancer Cells With Alpha Particle-Emitting {sup 227}Th-Trastuzumab

    SciTech Connect

    Heyerdahl, Helen; Krogh, Cecilie; Borrebaek, Jorgen; Larsen, Asmund; Dahle, Jostein

    2011-02-01

    Purpose: To evaluate the cytotoxic effects of low-dose-rate alpha particle-emitting radioimmunoconjugate {sup 227}Th-p-isothiocyanato-benzyl-DOTA-trastuzumab ({sup 227}Th-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 {sup 227}Th-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 {sup 227}Th-trastuzumab were compared with rates of cells treated with nonbinding {sup 227}Th-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 {sup 227}Th-trastuzumab for 1 h at 4{sup o}C, 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 {sup 227}Th-trastuzumab induced a specific cytotoxic effect in three HER2-expressing cell lines. The cytotoxic effect of {sup 227}Th-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 {sup 227}Th-trastuzumab.

  3. Efficient one-step radiolabeling of monoclonal antibodies to high specific activity with Actinium-225 for alpha-particle radioimmunotherapy of cancer

    PubMed Central

    Maguire, William F.; McDevitt, Michael R.; Smith-Jones, Peter M.; Scheinberg, David A.

    2015-01-01

    Targeted alpha-particle radiation using the radioisotope 225Actinium (225Ac) is a promising form of therapy for various types of cancer. Historical obstacles to the use of 225Ac have been the difficulty in finding suitable chelators to stably attach it to targeting vehicles such as peptides and monoclonal antibodies, the low specific activities of the products, and the lack of cost-effective radiolabeling procedures. We initially solved the first problem with a procedure involving two chemical steps that has been used as a standard in preclinical and clinical studies. However, this procedure involves the loss of 90% of the input 225Ac. A more efficient, economical process is needed to facilitate the more widespread use of 225Ac. Methods We conjugated representative antibodies with two forms of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), as well as other chelators as controls. We developed conditions to radiolabel these constructs in one chemical step and characterized their stability, immunoreactivity, biodistribution, and therapeutic efficacy in healthy and tumor-bearing mice. Results DOTA- antibody constructs were labeled to a wide range of specific activities in one chemical step at 37 °C. Radiochemical yields were approximately 10-fold higher and specific activities were up to 30-fold higher than with the previous approach. The products retained immunoreactivity and were stable to serum challenge in vitro and in mice. Labeling kinetics of DOTA- antibody constructs linked through a benzyl isothiocyanate linkage were more favorable than those linked through a N-hydroxysuccinimide linkage. Tissue distribution was similar but not identical between the constructs. The constructs produced specific therapeutic responses in a mouse model of acute myeloid leukemia. Conclusion We have characterized an efficient, one-step radiolabeling method that produces stable, therapeutically active conjugates of antibodies with 225Ac at high specific activity

  4. Oncogenic transformation of C3H 10T1/2 cells exposed to alpha particles: Sensitivity through the cell cycle

    SciTech Connect

    Bettega, D.; Calzolari, P.; Chiorda, G.N.

    1995-06-01

    Oncogenic transformation of synchronized C3H 10T1/2 cells was determined after exposure to 4.3 MeV {alpha} particles (LET = 101 keV/{mu}m). Two synchronization techniques were tested using basic and modified protocols: one based on the release of cells from contact inhibition and the second on the mitotic shake-off method. Progression of cells through the cycle was followed as a function of time by flow cytometric analysis, DNA labeling for passage through S phase, the growth curve for the cell number and mitotic index measurements. The conclusion is that, although the release of cells from confluence provides higher yields of synchronized cells, mitotic shake-off proved to be the best way of collecting a synchronized population of minimally perturbed cells. Cells synchronized by mitotic shake-off were irradiated with 0.30 Gy in the interval between 2 and 10 h corresponding to G{sub 1} and early S phases. For comparison asynchronous populations were irradiated in parallel. Oncogenic transformation frequency, corrected for background, in mid-G{sub 1} phase was (18 {+-} 4) x 10{sup {minus}5} (average values of frequencies at 4 and 6 h) compared with the value of (8 {+-} 4) x 10{sup {minus}5} for the asynchronous population. While these data are suggestive of a trend toward a slightly increased sensitivity in mid-G{sub 1} phase, it is not statistically significant. The surviving fraction is constant in G{sub 1} phase. 14 refs., 2 figs., 2 tabs.

  5. Alpha-particle spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.; Bjorkholm, P.

    1972-01-01

    Observation of lunar radon emanation during the Apollo 15 and 16 missions shows the existence of areas with locally high emanation rates. The most conspicuous Rn-222 feature found in the data analysis is a region that includes Aristarchus Crater. The excess emanating power of the Aristarchus region may be an indication of internal activity at that site. There are regions with anomalously high rates of Po-210 activity, which indicates transient phenomena involving the release of Rn-222 gas from certain areas of the moon.

  6. The Apollo Alpha Spectrometer.

    NASA Technical Reports Server (NTRS)

    Jagoda, N.; Kubierschky, K.; Frank, R.; Carroll, J.

    1973-01-01

    Located in the Science Instrument Module of Apollo 15 and 16, the Alpha Particle Spectrometer was designed to detect and measure the energy of alpha particles emitted by the radon isotopes and their daughter products. The spectrometer sensor consisted of an array of totally depleted silicon surface barrier detectors. Biased amplifier and linear gate techniques were utilized to reduce resolution degradation, thereby permitting the use of a single 512 channel PHA. Sensor identification and in-flight radioactive calibration were incorporated to enhance data reduction.

  7. Determination of isoprene and alpha-/beta-pinene oxidation products in boreal forest aerosols from Hyytiälä, Finland: diel variations and possible link with particle formation events.

    PubMed

    Kourtchev, I; Ruuskanen, T M; Keronen, P; Sogacheva, L; Dal Maso, M; Reissell, A; Chi, X; Vermeylen, R; Kulmala, M; Maenhaut, W; Claeys, M

    2008-01-01

    Biogenic volatile organic compounds (VOCs), such as isoprene and alpha-/beta-pinene, are photo-oxidized in the atmosphere to non-volatile species resulting in secondary organic aerosol (SOA). The goal of this study was to examine time trends and diel variations of oxidation products of isoprene and alpha-/beta-pinene in order to investigate whether they are linked with meteorological parameters or trace gases. Separate day-night aerosol samples (PM(1)) were collected in a Scots pine dominated forest in southern Finland during 28 July-11 August 2005 and analyzed with gas chromatography/mass spectrometry (GC/MS). In addition, inorganic trace gases (SO(2), CO, NO(x), and O(3)), meteorological parameters, and the particle number concentration were monitored. The median total concentration of terpenoic acids (i.e., pinic acid, norpinic acid, and two novel compounds, 3-hydroxyglutaric acid and 2-hydroxy-4-isopropyladipic acid) was 65 ng m(-3), while that of isoprene oxidation products (i.e., 2-methyltetrols and C(5) alkene triols) was 17.2 ng m(-3). The 2-methyltetrols exhibited day/night variations with maxima during day-time, while alpha-/beta-pinene oxidation products did not show any diel variation. The sampling period was marked by a relatively high condensation sink, caused by pre-existing aerosol particles, and no nucleation events. In general, the concentration trends of the SOA compounds reflected those of the inorganic trace gases, meteorological parameters, and condensation sink. Both the isoprene and alpha-/beta-pinene SOA products were strongly influenced by SO(2), which is consistent with earlier reports that acidity plays a role in SOA formation. The results support previous proposals that oxygenated VOCs contribute to particle growth processes above boreal forest.

  8. Millimeter-Scale Chemistry of Observable Endmembers with the Mars Science Laboratory Alpha Particle X-Ray Spectrometer and Mars Hand Lens Imager

    NASA Astrophysics Data System (ADS)

    VanBommel, Scott; Gellert, Ralf; Thompson, Lucy; Berger, Jeff; Campbell, Iain; Edgett, Ken; McBride, Marie; Minitti, Michelle; Desouza, Elstan; Boyd, Nick

    2016-04-01

    The Alpha Particle X-ray Spectrometer (APXS) is a bulk chemistry instrument conducting high-precision in-situ measurements of Martian rocks and soils onboard both active NASA rovers [1]. Mounted at the end of the Curiosity rover arm, the APXS can conduct multi-spot (raster) investigations in a single morning or evening. Combining APXS raster spectra and Mars Hand Lens Imager (MAHLI) images, a modeled terrain is developed in which the positions of APXS field of views (FOV) can be localized, thereby mitigating arm placement uncertainty. An acquired APXS spectrum is the result of the weighted sum of the signals from within the FOV. The spatial sensitivity of the APXS consists of an off-nadir contribution in addition to a vertical separation (standoff with respect to the APXS detector) contribution [2, 3]. MAHLI images and focus merge (MFM) products facilitate a 3D surface model of the target [4] compensating for the effects of sample relief in an APXS spectrum. Employing a MFM relief map, APXS placement is modeled in three-dimensions, permitting variable APXS docking (standoff, deployment angle). Through minimization, we arrive at millimeter-scale chemistry of veins, diagenetic features and dust-free rock endmembers of Martian targets. Several rasters have been conducted with Curiosity's APXS on Mars including a study of the Garden City outcrop. The area is characterized by its contrasting light and dark veins of cm-scale surface relief. Three-dimensional localization and minimization indicated calcium sulfate as the major component of the light vein while the dark vein is enriched in CaO (without accompanying SO3), MnO, Ni and Zn, with respect to average Mars composition. References: [1] Gellert et al. (2014), LPSC XLV, #1876. [2] VanBommel et al. (2015), LPSC XLVI, #2049. [3] VanBommel et al. (2016), XRS #2681. [4] Edgett et al. (2015), MAHLI Tech Rept 0001. Acknowledgements: The MSL APXS is financed and managed by the Canadian Space Agency (CSA) with Mac

  9. A chimeric 18L1-45RG1 virus-like particle vaccine cross-protects against oncogenic alpha-7 human papillomavirus types.

    PubMed

    Huber, Bettina; Schellenbacher, Christina; Jindra, Christoph; Fink, Dieter; Shafti-Keramat, Saeed; Kirnbauer, Reinhard

    2015-01-01

    Persistent infection with oncogenic human papillomaviruses (HPV) types causes all cervical and a subset of other anogenital and oropharyngeal carcinomas. Four high-risk (hr) mucosal types HPV16, 18, 45, or 59 cause almost all cervical adenocarcinomas (AC), a subset of cervical cancer (CxC). Although the incidence of cervical squamous cell carcinoma (SCC) has dramatically decreased following introduction of Papanicolaou (PAP) screening, the proportion of AC has relatively increased. Cervical SCC arise mainly from the ectocervix, whereas AC originate primarily from the endocervical canal, which is less accessible to obtain viable PAP smears. Licensed (bivalent and quadrivalent) HPV vaccines comprise virus-like particles (VLP) of the most important hr HPV16 and 18, self-assembled from the major capsid protein L1. Due to mainly type-restricted efficacy, both vaccines do not target 13 additional hr mucosal types causing 30% of CxC. The papillomavirus genus alpha species 7 (α7) includes a group of hr types of which HPV18, 45, 59 are proportionally overrepresented in cervical AC and only partially (HPV18) targeted by current vaccines. To target these types, we generated a chimeric vaccine antigen that consists of a cross-neutralizing epitope (homologue of HPV16 RG1) of the L2 minor capsid protein of HPV45 genetically inserted into a surface loop of HPV18 L1 VLP (18L1-45RG1). Vaccination of NZW rabbits with 18L1-45RG1 VLP plus alum-MPL adjuvant induced high-titer neutralizing antibodies against homologous HPV18, that cross-neutralized non-cognate hr α7 types HPV39, 45, 68, but not HPV59, and low risk HPV70 in vitro, and induced a robust L1-specific cellular immune response. Passive immunization protected mice against experimental vaginal challenge with pseudovirions of HPV18, 39, 45 and 68, but not HPV59 or the distantly related α9 type HPV16. 18L1-45RG1 VLP might be combined with our previously described 16L1-16RG1 VLP to develop a second generation bivalent vaccine

  10. Alpha Magnetic Spectrometer (AMS) Overview

    NASA Video Gallery

    The Alpha Magnetic Spectrometer (AMS) is flying to the station on STS-134. The AMS experiment is a state-of-the-art particle physics detector being operated by an international team composed of 60 ...

  11. Detection of alpha radiation in a beta radiation field

    DOEpatents

    Mohagheghi, Amir H.; Reese, Robert P.

    2001-01-01

    An apparatus and method for detecting alpha particles in the presence of high activities of beta particles utilizing an alpha spectrometer. The apparatus of the present invention utilizes a magnetic field applied around the sample in an alpha spectrometer to deflect the beta particles from the sample prior to reaching the detector, thus permitting detection of low concentrations of alpha particles. In the method of the invention, the strength of magnetic field required to adequately deflect the beta particles and permit alpha particle detection is given by an algorithm that controls the field strength as a function of sample beta energy and the distance of the sample to the detector.

  12. Diesel exhaust particles induce the over expression of tumor necrosis factor-alpha (TNF-alpha) gene in alvelor machrophage and failed to induce apoptosis through activation of nuclear factor-kappaB (NF-kappaB)

    EPA Science Inventory

    Exposure to particulate matter (PM2.5-10), including diesel exhaust particles (DEP) has been reported to induce lung injury and exacerbation of asthma and chronic obstructive pulmonary disease. Alveolar macrophages play a major role in the lung's response to inhaled particles and...

  13. Experimental Identification of Spin-Parities and Single-Particle Configurations in {sup 257}No and Its {alpha}-Decay Daughter {sup 253}Fm

    SciTech Connect

    Asai, M.; Tsukada, K.; Ichikawa, S.; Nagame, Y.; Nishinaka, I.; Akiyama, K.; Sakama, M.; Ishii, T.; Osa, A.; Oura, Y.; Sueki, K.; Shibata, M.

    2005-09-02

    {alpha}-{gamma} and {alpha}-electron coincidence spectroscopy for a short-lived heavy actinide nucleus {sup 257}No (T{sub 1/2}=24.5 s) has been performed using a gas-jet transport system and an on-line isotope separator. Spin-parities of excited states in {sup 253}Fm fed by the {alpha} decay of {sup 257}No have been identified on the basis of the measured internal conversion coefficients. The {nu}3/2{sup +}[622] configuration has been assigned to the ground state of {sup 257}No as well as to the 124.1 keV level in {sup 253}Fm. It was found that the ground-state configuration of {sup 257}No is different from that of lighter N=155 isotones.

  14. Delayed puberty.

    PubMed

    Traggiai, Cristina; Stanhope, Richard

    2002-03-01

    Puberty is the acquisition of secondary sexual characteristics associated with a growth spurt and resulting in the attainment of reproductive function. Delayed puberty is diagnosed when there is no breast development by 13.4 years of age in a girl and no testicular enlargement by 14.0 years in a boy. The aetiologies are: (i) pubertal delay, either with constitutional delay of growth and puberty or secondary to chronic illness, and (ii) pubertal failure, with hypogonadotrophic (defect in the hypothalamo-pituitary region) or hypergonadotrophic (secondary to gonadal failure) hypogonadism, or both (secondary to radio/chemotherapy). The investigation includes: history, auxological data and pubertal development examination. Boys usually require treatment and, if they do not respond, investigation. In girls it is appropriate to measure the thyroid function and karyotype first and, if necessary, to offer treatment. If they present with dysmorphic features, or positive familial history, an assessment is required before treatment.

  15. Theoretical substantiation of biological efficacy enhancement for β-delayed particle decay {sup 9}C beam: A Monte Carlo study in combination with analysis with the local effect model approach

    SciTech Connect

    Tian, Liheng; Yan, Yuanlin; Ma, Yuanyuan; Huang, Qiyan; Li, Qiang Liu, Xinguo; Dai, Zhongying; Fu, Tingyan; He, Pengbo

    2016-03-15

    Purpose: To improve the efficacy of heavy ion therapy, β-delayed particle decay {sup 9}C beam as a double irradiation source for cancer therapy has been proposed. The authors’ previous experiment showed that relative biological effectiveness (RBE) values at the depths around the Bragg peak of a {sup 9}C beam were enhanced and compared to its stable counterpart {sup 12}C beam. The purpose of this study was to explore the nature of the biological efficacy enhancement theoretically. Methods: A Monte Carlo simulation study was conducted in this study. First a simplified cell model was established so as to form a tumor tissue. Subsequently, the tumor tissue was imported into the Monte Carlo simulation software package GATE and then the tumor cells were virtually irradiated with comparable {sup 9}C and {sup 12}C beams, respectively, in the simulations. The transportation and particle deposition data of the {sup 9}C and {sup 12}C beams, derived from the GATE simulations, were analyzed with the authors’ local effect model implementation so as to deduce cell survival fractions. Results: The particles emitted from the decay process of deposited {sup 9}C particles around a cell nucleus increased the dose delivered to the nucleus and elicited clustered damages around the secondary particles’ trajectories. Therefore, compared to the {sup 12}C beam, the RBE value of the {sup 9}C beam increased at the depths around their Bragg peaks. Conclusions: Collectively, the increased local doses and clustered damages due to the decayed particles emitted from deposited {sup 9}C particles led to the RBE enhancement in contrast with the {sup 12}C beam. Thus, the enhanced RBE effect of a {sup 9}C beam for a simplified tumor model was shown theoretically in this study.

  16. Diverse delayed effects in human lymphoblastoid cells surviving exposure to high-LET (56)Fe particles or low-LET (137)Cs gamma radiation

    NASA Technical Reports Server (NTRS)

    Evans, H. H.; Horng, M. F.; Ricanati, M.; Diaz-Insua, M.; Jordan, R.; Schwartz, J. L.

    2001-01-01

    To obtain information on the origin of radiation-induced genomic instability, we characterized a total of 166 clones that survived exposure to (56)Fe particles or (137)Cs gamma radiation, isolated approximately 36 generations after exposure, along with their respective control clones. Cytogenetic aberrations, growth alterations, responses to a second irradiation, and mutant frequencies at the Na(+)/K(+) ATPase and thymidine kinase loci were determined. A greater percentage of clones that survived exposure to (56)Fe particles exhibited instability (defined as clones showing one or more outlying characteristics) than in the case of those that survived gamma irradiation. The phenotypes of the unstable clones that survived exposure to (56)Fe particles were also qualitatively different from those of the clones that survived gamma irradiation. A greater percentage (20%) of the unstable clones that survived gamma irradiation than those that survived exposure to (56)Fe particles (4%) showed an altered response to the second irradiation, while an increase in the percentage of clones that had an outlying frequency of ouabain-resistant and thymidine kinase mutants was more evident in the clones exposed to (56)Fe particles than in those exposed to gamma rays. Growth alterations and increases in dicentric chromosomes were found only in clones with more than one alteration. These results underscore the complex nature of genomic instability and the likelihood that radiation-induced genomic instability arises from different original events.

  17. Interferometric Propagation Delay

    NASA Technical Reports Server (NTRS)

    Goldstein, Richard

    1999-01-01

    Radar interferometry based on (near) exact repeat passes has lately been used by many groups of scientists, worldwide, to achieve state of the art measurements of topography, glacier and ice stream motion, earthquake displacements, oil field subsidence, lava flows, crop-induced surface decorrelation, and other effects. Variations of tropospheric and ionospheric propagation delays limit the accuracy of all such measurements. We are investigating the extent of this limitation, using data from the Shuttle radar flight, SIR-C, which is sensitive to the troposphere, and the Earth Resources Satellites, ERS-1/2, which are sensitive to both the troposphere and the ionosphere. We are presently gathering statistics of the delay variations over selected, diverse areas to determine the best accuracy possible for repeat track interferometry. The phases of an interferogram depend on both the topography of the scene and variations in propagation delay. The delay variations can be caused by movement of elements in the scene, by changes in tropospheric water vapor and by changes of the charge concentrations in the ionosphere. We plan to separate these causes by using the data from a third satellite visit (three-pass interferometry). The figure gives the geometry of the three-pass observations. The page of the figure is taken to be perpendicular to the spacecraft orbits. The three observational locations are marked on the figure, giving baselines B-12 and B-13, separated by the angle alpha. These parameters are almost constant over the whole scene. However, each pixel has an individual look angle, theta, which is related to the topography, rho is the slant range. A possible spurious time delay is shown. Additional information is contained in the original.

  18. MODELING AEROSOL FORMATION FROM ALPHA-PINENE + NOX IN THE PRESENCE OF NATURAL SUNLIGHT USING GAS PHASE KINETICS AND GAS-PARTICLE PARTITIONING THEORY. (R826771)

    EPA Science Inventory

    A kinetic mechanism was used to link and model the gas-phase reactions and
    aerosol accumulation resulting from src="/ncer/pubs/images/alpha.gif">-pinene reactions in the presence of sunlight,
    ozone (O3), and oxides of nitrogen
    (NO

  19. Targeted alpha therapy: part I.

    PubMed

    Elgqvist, Jorgen

    2011-07-01

    The possibility of pinpointing biological targets, and thereby potentially targeting and eradicating small tumors or even single cancer cells, is a tantalizing concept that has been discussed since the magic-bullet concept was first presented by Paul Erlich in the beginning of the 20th century in connection with his work on tissue staining for histological examinations and the work by Kohler and Milstein on antibody production published in 1975. This concept now seems feasible through the use of highly specific targeting constructs, chemical labeling of radioactive substances to these targeting constructs that results in high specific activities, radioimmunocomplexes with good stability even after injection, and the use of radionuclides emitting alpha( α)-particles having exceedingly high ionizing density and, therefore, a high probability of killing cells along its track in tissue. The short range of the emitted α-particles makes them even more interesting by minimizing unwanted irradiation of normal tissue surrounding the targeted cancer cells of interest, assuming high specificity of the targeting construct and good stability of the chemical bonds between the targeting construct and the α-particle emitter. Targeted Alpha Therapy (TAT), in which an α-particle emitting radionuclide is specifically directed to the biological target, is gaining more attention as new targets, targeting constructs, chemical labeling techniques, and α-particle emitters are, respectively, identified, constructed, developed, and made available. Results and improvements are now being published at an increasing rate and the number of conceivable applications is expanding, especially in the field of cancer treatment. Therefore, it is of utmost importance to provide an overview of the overall progress in the research field of TAT on a regular basis. However, problems such as limited or delayed diffusion of the α-radioimmunocomplex and inhomogeneous activity distributions in the

  20. Delayed puberty.

    PubMed

    Fenichel, Patrick

    2012-01-01

    Since puberty is a long ongoing developmental process with significant individual and population differences in timing, the definition of delayed puberty for a given individual needs to rest on simple, though arbitrary criteria based on epidemiological data. Although several genes involved in the hypothalamic-pituitary-gonadal maturation cascade have been characterized recently from familial or sporadic cases of primitive isolated hypogonadotropic hypogonadism, many genes regulating puberty onset remain undetermined. In case of delayed puberty and/or primary amenorrhea, a complete clinical examination including a detailed past history will evaluate the development of secondary sex characteristics, verify the association with a growth delay and look for specific indicative features pertaining to the etiological diagnosis. This clinical check-up completed if necessary with biological, ultrasonographic, radiological and genetic investigations will try to determine which girls will have a permanent sexual infantilism of gonadal, hypophyseal or hypothalamic origin, which girls will undergo spontaneous but delayed puberty and which girls have primary amenorrhea with developed secondary sex characteristics. Therapeutic attitude will have to integrate etiological factors, statural prognosis, bone mass preservation and psychological factors.

  1. Alpha Channeling in Rotating Plasma with Stationary Waves

    SciTech Connect

    A. Fetterman and N.J. Fisch

    2010-02-15

    An extension of the alpha channeling effect to supersonically rotating mirrors shows that the rotation itself can be driven using alpha particle energy. Alpha channeling uses radiofrequency waves to remove alpha particles collisionlessly at low energy. We show that stationary magnetic fields with high nθ can be used for this purpose, and simulations show that a large fraction of the alpha energy can be converted to rotation energy.

  2. Interpretation of cytogenetic damage induced in the germ line of male mice exposed for over 1 year to /sup 239/Pu alpha particles, fission neutrons, or /sup 60/Co gamma rays

    SciTech Connect

    Grahn, D.; Lee, C.H.; Farrington, B.F.

    1983-09-01

    The relative biological effectiveness (RBE) of /sup 239/Pu ..cap alpha.. particles, fission neutrons (0.85 MeV), and /sup 60/Co ..gamma.. rays has been evaluated for the induction of reciprocal chromosome translocations in spermatogonia and of chromosome/chromatid fragments and chromatid rearrangements in the primary spermatocyte of adult male B6CF/sub 1/ mice. Age concurrency was maintained for both internal and external radiations which were delivered at about 1 rad/week for /sup 239/Pu (single intravenous dose of 10 ..mu..Ci/kg), 0.67, 1.67, and 2.67 rad/week for neutrons, and 6.95, 17.4, and 32 rad/week for ..gamma.. rays for at least 60 weeks. In terms of frequency of translocations, the response to the alpha emitter was nonlinear (concave downward) with little dose-response predictability; to cumulative neutron exposures the response was linear, without evidence of a dose-rate effect; and to ..gamma.. radiation the responses were linear, and a significant dose-rate effect was seen. RBE estimates are variable. The overall response to the ..cap alpha.. emitter is interpreted to be a complex function of (a) microdosimetric heterogeneity, (b) a nearly invariant deposition pattern in the gonad, (c) the high sensitivity of differentiating spermatogonia to cell killing, and (d) the capacity of stem cells in relatively radiation-free areas to progressively assume the major spermatogenic role.

  3. Investigation of the effective atomic numbers of dosimetric materials for electrons, protons and alpha particles using a direct method in the energy region 10 keV-1 GeV: a comparative study.

    PubMed

    Kurudirek, Murat; Aksakal, Oğuz; Akkuş, Tuba

    2015-11-01

    A direct method has been used for the first time, to compute effective atomic numbers (Z eff) of water, air, human tissues, and some organic and inorganic compounds, for total electron proton and alpha particle interaction in the energy region 10 keV-1 GeV. The obtained values for Z eff were then compared to those obtained using an interpolation procedure. In general, good agreement has been observed for electrons, and the difference (%) in Z eff between the results of the direct and the interpolation method was found to be <10 % for all materials, in the energy range from 10 keV to 1 MeV. More specifically, results of the two methods were found to agree well (Dif. <10 %) for air, calcium fluoride, kapton polyimide film, paraffin wax and plastic scintillator in the entire energy region with respect to the total electron interaction. On the other hand, values for Z eff calculated using both methods for protons and alpha particles generally agree with each other in the high-energy region above 10 MeV.

  4. An analytical approach for the prediction of gamma-to-alpha phase transformation of aluminum oxide (Al2O3) particles in the Space Shuttle ASRM and RSRM exhausts

    NASA Astrophysics Data System (ADS)

    Oliver, S. M.; Moylan, B. E.

    1992-07-01

    The analytical approach developed here utilizes the flow-field output from industry standard nozzle and plume codes as input into a particle phase conversion code which predicts the amount of gamma-to-alpha conversion in SRM exhausts. Sixty different cases were considered which varied such parameters as particle size, degree of undercooling, motor type, and altitude. On-centerline calculations were made for both the ASRM and RSRM at an altitude of 100,000 feet with particle sizes varying from 3.5 to 9.1 micron radius and undercooling varying from 0 to 20 percent. Additional calculations were made for the ASRM at 100,000 feet off centerline and at an altitude of 60,000 feet on centerline. The results indicate that significant amounts of metastable alumina will be present in ASRM and RSRM exhausts. Though not significant to motor performance, this may be important in such issues as environmental effects of rocket exhausts, plume radiative heating predictions, and particle size determination by laser scattering.

  5. Synthesis of single phase {alpha}-Fe, Fe{sub 3}C and Fe{sub 7}C{sub 3} nano-particles by CO{sub 2} laser pyrolysis technique. Quarterly progress report, January--March, 1992

    SciTech Connect

    Eklund, P.C.; Bi, X.X.

    1992-07-01

    Iron-containing catalysts have been known to be useful in assisting the Fischer-Tropsch (FT) reaction for synthesizing hydrocarbons. However, it has been well recognized that iron catalyst are not stable during the reaction but converted into iron carbides. It is thus important to understand the role of the iron carbides in the catalytic reaction of the FT-synthesis. It has been found difficult to produce iron carbide nano-particles as a single phase, because iron carbide phases are only metastable under 1 atm pressure. Iron carbide bulk particles prepared so far are often contaminated with metallic iron, iron oxides and free carbon. In this study, we investigate the synthesis of iron carbide nano-particles using CO{sub 2} laser pyrolysis technique. We show that this technique is successful in synthesizing {alpha}-Fe, Fe{sub 3}C and Fe{sub 7}C{sub 3} nano-particles in their single phase with sizes in the range of 5--20nm. In particular, we have produced for the first time the Fe{sub 7}C{sub 3} which has been known to exist but unable to be produced as a single phase. Furthermore, it is interesting that Fe{sub 5}C{sub 2} which has carbon and iron ratio between Fe{sub 3}C and Fe{sub 7}C{sub 3}, is not seen in any run of our synthesis.

  6. Delayed puberty.

    PubMed

    Reiter, Edward O; Lee, Peter A

    2002-02-01

    Normal puberty is a time of life and a process of development that results in full adult maturity of growth, sexual development, and psychosocial achievement. Delayed puberty describes the clinical condition in which the pubertal events start late (usually > +2.5 SD later than the mean) or are attenuated in progression. The differential diagnosis includes syndromes of low gonadotropin production, usually constitutional delay of growth and maturation associated with chronic disease, but also an array of gene-mediated disorders, and syndromes of primary gonadal dysfunction with hypergonadotropic hypogonadism, including Turner and Klinefelter syndromes, and a group of acquired and genetic abnormalities. Diagnostic assessment and varied therapeutic modalities are discussed. The issues of androgen or estrogen therapy are important to assess, and growth hormone treatment remains a difficult dilemma.

  7. H Ly-alpha transmittance of thin foils of C, Si/C, and Al/C for keV particle detectors

    NASA Technical Reports Server (NTRS)

    Drake, V. A.; Sandel, B. R.; Jenkins, D. G.; Hsieh, K. C.

    1992-01-01

    A class of instruments designed for remote sensing of space plasmas by measuring energetic neutral atoms (ENA) uses a thin foil as both a signal generator and a light shield. An ENA imager must look directly at the ENA source region, which is also usually an intense source of H Ly-alpha (1216 A) photons. It is desirable to minimize the energy threshold for ENA detectors, at the same time maximizing the blocking of H Ly-alpha. Optimizing filter design to meet these two contrary requirements has led us to measure the transmittance of thin C, Si/C, and Al/C foils at H Ly-alpha. Our results indicate that (1) transmittance of less than 0.0007 can be achieved with 7 micro-g/sq cm Si on 1.7 micro-g/sq cm C; (2) an Si/C composite foil with a thin carbon layer is more effective in blocking UV radiation while having the lowest energy threshold of all the foils measured; and (3) transmittance of Si/C foils of known Si and C thicknesses cannot be accurately predicted, but must be measured.

  8. Alpha particles as radiopharmaceuticals in the treatment of bone metastases: mechanism of action of radium-223 chloride (Alpharadin) and radiation protection.

    PubMed

    Cheetham, Philippa J; Petrylak, Daniel P

    2012-04-01

    Approximately 85% to 90% of men with castration-resistant prostate cancer (CRPC) have radiological evidence of bone metastases. To date, however, therapies to manage bone metastases have been primarily palliative. Among CRPC patients with bone metastases, there is a significant unmet need for active antitumor treatment options that are highly efficacious and have a favorable safety profile. This article will present current information about alpha-pharmaceuticals, a new class of targeted cancer therapy for the treatment of patients with CRPC and bone metastases. It will review preclinical and clinical studies of the experimental radiopharmaceutical radium-223 chloride (Alpharadin), a first-in-class, highly targeted and well-tolerated alpha-pharmaceutical under development to improve survival in patients with bone metastases from advanced prostate cancer. Alpharadin kills cancer cells via alpha radiation from the decay of radium-223, a calcium mimetic that naturally self-targets to bone metastases. The mechanism of action of Alpharadin and specifics of administration, radiation protection, and patient management will be discussed.

  9. The Substitution of a Super Black Fixed Micro-Object for an Optical Microcavity in a Delayed Choice Experiment to Send Information Immediately Between 2 Paired Particles: Simplifying the Experiment

    NASA Astrophysics Data System (ADS)

    Snyder, Douglas

    2015-04-01

    An experiment has been described that relies on a delayed choice for an idler photon that immediately affects the signal photon with which it is at least initially entangled and for which the idler photon provides which-way information. The delayed choice concerns whether to maintain or eliminate the entanglement before any measurements are made. In one option of the delayed choice, the entanglement can be eliminated because the relevant state of the idler photon related to its entanglement is eliminated when the idler photon enters an optical microcavity filled with photons with the same mode as the incoming idler photon. The microcavity is located at the crossroads of two possible idler photon paths. The relevant state of the idler photon characterizes the particular path taken by the photon and this information is eliminated when the particle enters the cavity. Over a number of runs with this choice, the distribution of the paired signal photons shows interference. If the entanglement is maintained, the distribution of the paired signal photons shows which-way information. This experiment can be simplified by using a super black material (e.g., Vantablack) affixed to a fixed micro-object located at the crossroads of the two possible idler photon paths instead of the optical microcavity. The photon would be absorbed by the material and there would be no way to detect from which direction it came. Objects such as fixed mirrors in a Mach Zehnder interferometer do not provide ww information. The super black fixed micro-object should not either.

  10. Alpha-Particle-Induced Complex Chromosome Exchanges Transmitted through Extra-Thymic Lymphopoiesis In Vitro Show Evidence of Emerging Genomic Instability

    PubMed Central

    Sumption, Natalia; Goodhead, Dudley T.; Anderson, Rhona M.

    2015-01-01

    Human exposure to high-linear energy transfer α-particles includes environmental (e.g. radon gas and its decay progeny), medical (e.g. radiopharmaceuticals) and occupational (nuclear industry) sources. The associated health risks of α-particle exposure for lung cancer are well documented however the risk estimates for leukaemia remain uncertain. To further our understanding of α-particle effects in target cells for leukaemogenesis and also to seek general markers of individual exposure to α-particles, this study assessed the transmission of chromosomal damage initially-induced in human haemopoietic stem and progenitor cells after exposure to high-LET α-particles. Cells surviving exposure were differentiated into mature T-cells by extra-thymic T-cell differentiation in vitro. Multiplex fluorescence in situ hybridisation (M-FISH) analysis of naïve T-cell populations showed the occurrence of stable (clonal) complex chromosome aberrations consistent with those that are characteristically induced in spherical cells by the traversal of a single α-particle track. Additionally, complex chromosome exchanges were observed in the progeny of irradiated mature T-cell populations. In addition to this, newly arising de novo chromosome aberrations were detected in cells which possessed clonal markers of α-particle exposure and also in cells which did not show any evidence of previous exposure, suggesting ongoing genomic instability in these populations. Our findings support the usefulness and reliability of employing complex chromosome exchanges as indicators of past or ongoing exposure to high-LET radiation and demonstrate the potential applicability to evaluate health risks associated with α-particle exposure. PMID:26252014

  11. The ALPHA Magnetic Spectrometer

    NASA Astrophysics Data System (ADS)

    Viertel, G. M.; Capell, M.

    1998-12-01

    The ALPHA Magnetic Spectrometer (AMS) will be the first large magnetic spectrometer in space. It is scheduled to be installed on the future International Space Station ALPHA (ISSA) in the year 2002 to perform measurements of the charged particle composition to answer fundamental questions in particle physics and astrophysics. Before installation on ISSA, AMS will fly on the shuttle DISCOVERY for a period of 10 days starting in May 1998. This will enable AMS to perform a test of the apparatus and first measurements. The AMS detector has five major components: A permanent NdFeB magnet, six planes of Silicon double-sided microstrip detectors, a plastic scintillator time of flight hodoscope, a plastic scintillator anticoincidence counter and an Aerogel Cherenkov threshold counter. In addition, there are electronics, support infrastructure and interfaces.

  12. Alpha Blockers

    MedlinePlus

    ... conditions such as high blood pressure and benign prostatic hyperplasia. Find out more about this class of medication. ... these conditions: High blood pressure Enlarged prostate (benign prostatic hyperplasia) Though alpha blockers are commonly used to treat ...

  13. Alpha fetoprotein

    MedlinePlus

    ... Alpha fetoprotein - series References Cunningham FG, Leveno KJ, Bloom SL, et al. Prenatal diagnosis and fetal therapy. In: Cunningham FG, Leveno KJ, Bloom SL, et al, eds. Williams Obstetrics . 23rd ed. ...

  14. Alpha Thalassemia

    MedlinePlus

    ... an apparently normal individual has a child with hemoglobin H disease or alpha thalassemia minor. It can ... gene on one chromosome 25% 25% 25% 25% hemoglobin H disease there is a 25% chance with ...

  15. Thermoluminescence Response of CaF2:Mn, CaFz:Dy and CaSO4:Tm to Protons and Alpha-Particles,

    DTIC Science & Technology

    1987-06-01

    linear energy tranfer (LET), which is the average stopping power over the ion range, is also shown as it is expected that the response ratio may be LET...were used for the CaSO4 :Tm and CaF 2 :Mn powders, respectively. Small samples of the powders were spread over the heating planchet to avoid self...absorption during reading. A different procedure was required for the alphas. A relatively thick layer of powder was packed onto the heating planchet

  16. Study of Low-Temperature Oxidation in Au/Si and Cu/Si Systems by 7-MeV Alpha Particle Backscattering Analysis

    NASA Astrophysics Data System (ADS)

    Li, Jian; Yonezawa, Hiroki; Shigematsu, Toshio

    1992-03-01

    Low-temperature oxidation kinetics in the Au/Si and Cu/Si systems was measured by a 7-MeV alpha backscattering technique. The formation of a Si oxide layer near the surface in the Au/Si system is mainly controlled by intermixing between the Au and Si substrates. The formation of thick SiO2 in the Cu-Si interface at room temperature is a catalytic process due to the presence of a Cu3Si compound.

  17. Dosimetry of a 238Pu-based alpha-particle irradiator and its biological application in a study of the bystander effect.

    PubMed

    Dahle, Jostein; Kalanxhi, Erta; Tisnek, Nikolai

    2011-06-01

    A better understanding of the non-targeted (bystander) effects of radiation may have important implications with regards to radiation risk assessment, radiation protection, and targeted cancer therapy. In the present study, the direct and bystander effects of α-particle irradiation in immortalized human fibroblasts (F11hTERT) and breast cancer cells (MCF-7) was investigated. To ensure a more accurate dose delivery to these different cell lines, an existing 238Pu α-particle irradiator was improved by the addition of a collimator and the development of an analytical equation for calculation of the radiation dose to cells. The mean dose rate and α-particle fluence were calculated for each cell line by taking into consideration the size of their nuclei. Bystander effect experiments were performed by transferring medium from irradiated to unirradiated cells and by measuring micronucleus formation in the cells. Both the immortalized human fibroblasts and the breast cancer cells displayed a bystander effect. In conclusion, the broad-beam α-particle irradiator improved in this study represents a useful tool in the investigation of direct and non-targeted effects of α-particle radiation.

  18. Nanoconjugation of PSMA-Targeting Ligands Enhances Perinuclear Localization and Improves Efficacy of Delivered Alpha-Particle Emitters against Tumor Endothelial Analogues.

    PubMed

    Zhu, Charles; Bandekar, Amey; Sempkowski, Michelle; Banerjee, Sangeeta Ray; Pomper, Martin G; Bruchertseifer, Frank; Morgenstern, Alfred; Sofou, Stavroula

    2016-01-01

    This study aims to evaluate the effect on killing efficacy of the intracellular trafficking patterns of α-particle emitters by using different radionuclide carriers in the setting of targeted antivascular α-radiotherapy. Nanocarriers (lipid vesicles) targeted to the prostate-specific membrane antigen (PSMA), which is unique to human neovasculature for a variety of solid tumors, were loaded with the α-particle generator actinium-225 and were compared with a PSMA-targeted radiolabeled antibody. Actinium-225 emits a total of four α-particles per decay, providing highly lethal and localized irradiation of targeted cells with minimal exposure to surrounding healthy tissues. Lipid vesicles were derivatized with two types of PSMA-targeting ligands: a fully human PSMA antibody (mAb) and a urea-based, low-molecular-weight agent. Target selectivity and extent of internalization were evaluated on monolayers of human endothelial cells (HUVEC) induced to express PSMA in static incubation conditions and in a flow field. Both types of radiolabeled PSMA-targeted vesicles exhibit similar killing efficacy, which is greater than the efficacy of the radiolabeled control mAb when compared on the basis of delivered radioactivity per cell. Fluorescence confocal microscopy demonstrates that targeted vesicles localize closer to the nucleus, unlike antibodies which localize near the plasma membrane. In addition, targeted vesicles cause larger numbers of dsDNAs per nucleus of treated cells compared with the radiolabeled mAb. These findings demonstrate that radionuclide carriers, such as PSMA-targeted lipid-nanocarriers, which localize close to the nucleus, increase the probability of α-particle trajectories crossing the nuclei, and, therefore, enhance the killing efficacy of α-particle emitters.

  19. Alpha particles at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, effective dose, and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.A.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-03-01

    Conversion coefficients have been calculated for fluence to absorbed dose, fluence to effective dose and fluence to gray equivalent, for isotropic exposure to alpha particles in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for effective dose are within 30 % of those calculated using ICRP 1990 recommendations.

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

    SciTech Connect

    Little, John B.

    2013-09-17

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

  1. Reviews Book: Marie Curie and Her Daughters Resource: Cumulus Equipment: Alpha Particle Scattering Apparatus Equipment: 3D Magnetic Tube Equipment: National Grid Transmission Model Book: Einstein's Physics Equipment: Barton's Pendulums Equipment: Weather Station Web Watch

    NASA Astrophysics Data System (ADS)

    2013-09-01

    WE RECOMMEND Marie Curie and Her Daughters An insightful study of a resilient and ingenious family and their achievements Cumulus Simple to install and operate and with obvious teaching applications, this weather station 'donationware' is as easy to recommend as it is to use Alpha Particle Scattering Apparatus Good design and construction make for good results National Grid Transmission Model Despite its expense, this resource offers excellent value Einstein's Physics A vivid, accurate, compelling and rigorous treatment, but requiring an investment of time and thought WORTH A LOOK 3D Magnetic Tube Magnetic fields in three dimensions at a low cost Barton's Pendulums A neat, well-made and handy variant, but not a replacement for the more traditional version Weather Station Though not as robust or substantial as hoped for, this can be put to good use with the right software WEB WATCH An online experiment and worksheet are useful for teaching motor efficiency, a glance at CERN, and NASA's interesting information on the alpha-magnetic spectrometer and climate change

  2. NACA Physicist Studying Alpha Rays

    NASA Technical Reports Server (NTRS)

    1957-01-01

    NACA Physicits studying Alpha Rays in a continuous cloud chamber. A cloud chamber is used by Lewis scientists to obtain information aimed at minimizing undesirable effects of radiation on nuclear-powered aircraft components. Here, alpha particles from a polonium source emit in a flower-like pattern at the cloud chamber's center. The particles are made visible by means of alcohol vapor diffusing from an area at room temperature to an area at minus -78 deg. Centigrade. Nuclear-powered aircraft were never developed and aircraft nuclear propulsion systems were canceled in the early 1960s.

  3. A catalogue of normalized intensity functions and polarization from a cloud of particles with a size distribution of alpha to the minus 4th power

    NASA Technical Reports Server (NTRS)

    Craven, P. D.; Gary, G. A.

    1972-01-01

    The Mie theory of light scattering by spheres was used to calculate the scattered intensity functions resulting from single scattering in a polydispersed collection of spheres. The distribution used behaves according to the inverse fourth power law; graphs and tables for the angular dependence of the intensity and polarization for this law are given. The effects of the particle size range and the integration increment are investigated.

  4. Dynamic radioactive particle source

    DOEpatents

    Moore, Murray E; Gauss, Adam Benjamin; Justus, Alan Lawrence

    2012-06-26

    A method and apparatus for providing a timed, synchronized dynamic alpha or beta particle source for testing the response of continuous air monitors (CAMs) for airborne alpha or beta emitters is provided. The method includes providing a radioactive source; placing the radioactive source inside the detection volume of a CAM; and introducing an alpha or beta-emitting isotope while the CAM is in a normal functioning mode.

  5. Effective treatment of ductal carcinoma in situ with a HER-2- targeted alpha-particle emitting radionuclide in a preclinical model of human breast cancer.

    PubMed

    Yoshida, Takahiro; Jin, Kideok; Song, Hong; Park, Sunju; Huso, David L; Zhang, Zhe; Liangfeng, Han; Zhu, Charles; Bruchertseifer, Frank; Morgenstern, Alfred; Sgouros, George; Sukumar, Saraswati

    2016-05-31

    The standard treatment for ductal carcinoma in situ (DCIS) of the breast is surgical resection, followed by radiation. Here, we tested localized therapy of DCIS in mice using the immunoconjugate 225Ac linked-trastuzumab delivered through the intraductal (i.duc) route. Trastuzumab targets HER-2/neu, while the alpha-emitter 225Ac (half-life, 10 days) delivers highly cytotoxic, focused doses of radiation to tumors. Systemic 225Ac, however, elicits hematologic toxicity and at high doses free 213Bi, generated by its decay, causes renal toxicity. I.duc delivery of the radioimmunoconjugate could bypass its systemic toxicity. Bioluminescent imaging showed that the therapeutic efficacy of intraductal 225Ac-trastuzumab (10-40 nCi per mammary gland; 30-120 nCi per mouse) in a DCIS model of human SUM225 cancer cells in NSG mice was significantly higher (p<0.0003) than intravenous (120 nCi per mouse) administration, with no kidney toxicity or loss of body weight. Our findings suggest that i.duc radioimmunotherapy using 225Ac-trastuzumab deserves greater attention for future clinical development as a treatment modality for early breast cancer.

  6. Effective treatment of ductal carcinoma in situ with a HER-2-targeted alpha-particle emitting radionuclide in a preclinical model of human breast cancer

    PubMed Central

    Song, Hong; Park, Sunju; Zhang, Zhe; Liangfeng, Han; Zhu, Charles; Bruchertseifer, Frank; Morgenstern, Alfred; Sgouros, George; Sukumar, Saraswati

    2016-01-01

    The standard treatment for ductal carcinoma in situ (DCIS) of the breast is surgical resection, followed by radiation. Here, we tested localized therapy of DCIS in mice using the immunoconjugate 225Ac linked-trastuzumab delivered through the intraductal (i.duc) route. Trastuzumab targets HER-2/neu, while the alpha-emitter 225Ac (half-life, 10 days) delivers highly cytotoxic, focused doses of radiation to tumors. Systemic 225Ac, however, elicits hematologic toxicity and at high doses free 213Bi, generated by its decay, causes renal toxicity. I.duc delivery of the radioimmunoconjugate could bypass its systemic toxicity. Bioluminescent imaging showed that the therapeutic efficacy of intraductal 225Ac-trastuzumab (10-40 nCi per mammary gland; 30-120 nCi per mouse) in a DCIS model of human SUM225 cancer cells in NSG mice was significantly higher (p<0.0003) than intravenous (120 nCi per mouse) administration, with no kidney toxicity or loss of body weight. Our findings suggest that i.duc radioimmunotherapy using 225Ac-trastuzumab deserves greater attention for future clinical development as a treatment modality for early breast cancer. PMID:27119227

  7. Biological Effect of Lead-212 Localized in the Nucleus of Mammalian Cells: Role of Recoil Energy in the Radiotoxicity of Internal Alpha-Particle Emitters1

    PubMed Central

    Azure, Michael T.; Archer, Ronald D.; Sastry, Kandula S. R.; Rao, Dandamudi V.; Howell, Roger W.

    2012-01-01

    The radiochemical dipyrrolidinedithiocarbamato-212Pb(II) [212Pb(PDC)2] is synthesized and its effects on colony formation in cultured Chinese hamster V79 cells are investigated. The cellular uptake, biological retention, subcellular distribution and cytotoxicity of the radiocompound are determined. The 212Pb is taken up quickly by the cells, reaching saturation levels in 1.25 h. When the cells are washed, the intracellular activity is retained with a biological half-life of 11.6 h. Gamma-ray spectroscopy indicates that the 212Pb daughters (212Bi, 212Po and 208Tl) are in secular equilibrium within the cell. About 72% of the cellular activity localizes in the cell nucleus, of which 35% is bound specifically to nuclear DNA. The mean cellular uptake required to achieve 37% survival is 0.35 mBq of 212Pb per cell, which delivers a dose of 1.0 Gy to the cell nucleus when the recoil energy of 212Bi and 212Po decays is ignored and 1.7 Gy when recoil is included. The corresponding RBE values compared to acute external 137Cs γ rays at 37% survival are 4.0 and 2.3, respectively. The chemical Pb(PDC)2 is not chemotoxic at the concentrations used in this study. Because the β-particle emitter 212Pb decays to the α-particle-emitting daughters 212Bi and 212Po, these studies provide information on the biological effects of α-particle decays that occur in the cell nucleus. Our earlier studies with cells of the same cell line using 210Po (emits 5.3 MeV α particle) localized predominantly in the cytoplasm resulted in an RBE of 6. These earlier results for 210Po, along with the present results for 212Pb, suggest that the recoil energy associated with the 212Bi and 212Po daughter nuclei plays little or no role in imparting biological damage to critical targets in the cell nucleus. PMID:7938477

  8. UAVs and Control Delays

    DTIC Science & Technology

    2005-09-01

    Transport Delay itI tl2 s2+(tl +t2tI2)s+ 1 Delay Figure 17 A Matlab Simulink model used to compare a simple delayed system , in this case an integrator...23 3 Control of tim e-delay system s...discuss the various sources of delays, leading to an assessment of typical delays to be expected in a few example systems . Sources of delay that will

  9. Differential radiosensitivity phenotypes of DNA-PKcs mutations affecting NHEJ and HRR systems following irradiation with gamma-rays or very low fluences of alpha particles.

    PubMed

    Lin, Yu-Fen; Nagasawa, Hatsumi; Little, John B; Kato, Takamitsu A; Shih, Hung-Ying; Xie, Xian-Jin; Wilson, Paul F; Brogan, John R; Kurimasa, Akihiro; Chen, David J; Bedford, Joel S; Chen, Benjamin P C

    2014-01-01

    We have examined cell-cycle dependence of chromosomal aberration induction and cell killing after high or low dose-rate γ irradiation in cells bearing DNA-PKcs mutations in the S2056 cluster, the T2609 cluster, or the kinase domain. We also compared sister chromatid exchanges (SCE) production by very low fluences of α-particles in DNA-PKcs mutant cells, and in homologous recombination repair (HRR) mutant cells including Rad51C, Rad51D, and Fancg/xrcc9. Generally, chromosomal aberrations and cell killing by γ-rays were similarly affected by mutations in DNA-PKcs, and these mutant cells were more sensitive in G1 than in S/G2 phase. In G1-irradiated DNA-PKcs mutant cells, both chromosome- and chromatid-type breaks and exchanges were in excess than wild-type cells. For cells irradiated in late S/G2 phase, mutant cells showed very high yields of chromatid breaks compared to wild-type cells. Few exchanges were seen in DNA-PKcs-null, Ku80-null, or DNA-PKcs kinase dead mutants, but exchanges in excess were detected in the S2506 or T2609 cluster mutants. SCE induction by very low doses of α-particles is resulted from bystander effects in cells not traversed by α-particles. SCE seen in wild-type cells was completely abolished in Rad51C- or Rad51D-deficient cells, but near normal in Fancg/xrcc9 cells. In marked contrast, very high levels of SCEs were observed in DNA-PKcs-null, DNA-PKcs kinase-dead and Ku80-null mutants. SCE induction was also abolished in T2609 cluster mutant cells, but was only slightly reduced in the S2056 cluster mutant cells. Since both non-homologous end-joining (NHEJ) and HRR systems utilize initial DNA lesions as a substrate, these results suggest the possibility of a competitive interference phenomenon operating between NHEJ and at least the Rad51C/D components of HRR; the level of interaction between damaged DNA and a particular DNA-PK component may determine the level of interaction of such DNA with a relevant HRR component.

  10. Radioimmunotherapy with alpha-emitting nuclides.

    PubMed

    McDevitt, M R; Sgouros, G; Finn, R D; Humm, J L; Jurcic, J G; Larson, S M; Scheinberg, D A

    1998-09-01

    This review discusses the application of alpha particle-emitting radionuclides in targeted radioimmunotherapy. It will outline the production and chemistry of astatine-211, bismuth-212, lead-212, actinium-225, bismuth-213, fermium-255, radium-223 and terbium-149, which at present are the most promising alpha-emitting isotopes available for human clinical use. The selective cytotoxicity offered by alpha particle-emitting radioimmunoconstructs is due to the high linear energy transfer and short particle path length of these radionuclides. Based upon the pharmacokinetics of alpha particle-emitting radioimmunoconstructs, both stochastic and conventional dosimetric methodology is discussed, as is the preclinical and initial clinical use of these radionuclides conjugated to monoclonal antibodies for the treatment of human neoplasia.

  11. Elementary Processes Underlying Alpha Channeling in Tokamaks

    SciTech Connect

    NM.J. Fisch

    2012-06-15

    Alpha channeling in tokamaks is speculative, but also extraordinarily attractive. Waves that can accomplish this effect have been identified. Key aspects of the theory now enjoy experimental confirmation. This paper will review the elementary processes of wave-particle interactions in plasma that underlie the alpha channeling effect

  12. Delayed childbearing.

    PubMed

    Francis, H H

    1985-06-01

    In many Western nations, including England and Wales, Sweden, and the US, there is a current trend towards delayed childbearing because of women's pursuit of a career, later marriage, a longer interval between marriage and the 1st birth, and the increasing number of divorcees having children in a 2nd marriage. Wives of men in social classes I and II in England and Wales are, on average, having their 1st child at 27.9 years, 1.6 years later than in 1973, and in social classes IV and V, 1.0 years later than in 1973, at a mean age of 23.7 years. Consequently, the total period fertility rate for British women aged 30-34 years, 35-39 years, and 40 and over increased by 4%, 2%, and 4%, respectively, between 1982-83, in contrast to reductions of 2% and 3%, respectively, in the 15-19 year and 20-24 year age groups, with the 25-29-year-olds remaining static. The average maternal mortality for all parties in England and Wales during 1976-78 was 106/million for adolescents, 70.4/million for 20-24 year-olds, and 1162/million for those aged 40 years and older. The specific obstetric and allied conditions which increase with age are the hypertensive diseases of pregnancy, hemorrhage, pulmonary embolism, abortion, cardiac disease, caesarean section, ruptured uterus, and amniotic fluid embolism. The Swedish Medical Birth Registry of all live births and perinatal deaths since 1973 has shown that the risk of late fetal death is significantly greater in women aged 30-39 years than in those of the same parity and gravidity aged 20-24 years. The risk of giving birth to low birth weight babies preterm and at term and of premature labor are similarly increased. The early neonatal death rate also was increased for primigravidas and nulliparas in the 30-39 year age group but not in parous women. This is, in part, due to the rise in incidence of fetal abnormalities with advancing maternal age because of chromosomal and nonchromosomal anomalies. These also appear to be the cause of the

  13. Quantum design using a multiple internal reflections method in a study of fusion processes in the capture of alpha-particles by nuclei

    NASA Astrophysics Data System (ADS)

    Maydanyuk, Sergei P.; Zhang, Peng-Ming; Belchikov, Sergei V.

    2015-08-01

    A high precision method to determine fusion in the capture of α-particles by nuclei is presented. For α-capture by 40Ca and 44Ca, such an approach gives (1) the parameters of the α-nucleus potential and (2) fusion probabilities. This method found new parametrization and fusion probabilities and decreased the error by 41.72 times for α +40Ca and 34.06 times for α +44Ca in a description of experimental data in comparison with existing results. We show that the sharp angular momentum cutoff proposed by Glas and Mosel is a rough approximation, Wong's formula and the Hill-Wheeler approach determine the penetrability of the barrier without a correct consideration of the barrier shape, and the WKB approach gives reduced fusion probabilities. Based on our fusion probability formula, we explain the difference between experimental cross-sections for α +40Ca and α +44Ca, which is connected with the theory of coexistence of the spherical and deformed shapes in the ground state for nuclei near the neutron magic shell N = 20. To provide deeper insight into the physics of nuclei with the new magic number N = 26, the cross-section for α +46Ca is predicted for future experimental tests. The role of nuclear deformations in calculations of the fusion probabilities is analyzed.

  14. Track-hole formation of alpha-particle and recoil nuclei in an LR-115 nuclear track detector exposed to neutrons

    NASA Astrophysics Data System (ADS)

    Hafez, A. F.; Khalil, G. I.

    1994-10-01

    The response function V(REL) of an LR-115 polymeric nuclear track detector has been used to determine the V( R) sensitivity functions for recoil nuclei which are produced by the interactions of fast neutrons with the detector material. For an external radiator placed in close contact with the LR-115 detector, the sensitivity functions have also been determined for the generated nuclei from the (n, α) reaction of thermal neutrons with the radiator material. The REL and the range for the studied nuclei as a function of their energies were calculated by using the BASIC-E version of Henke and Benton's programme. The theory of etch-track kinetics which depends on the V( R) function is used to predict the residual thickness necessary for track-hole formation of a charged particle at different angles by normally incident neutrons. The theoretical treatments were found to be in fair agreement with the previously obtained data for other cellulose nitrate track detectors.

  15. Coordination of the Ser2056 and Thr2609 Clusters of DNA-PKcs in Regulating Gamma Rays and Extremely Low Fluencies of Alpha-Particle Irradiation to G0/G1 Phase Cells

    PubMed Central

    Nagasawa, Hatsumi; Lin, Yu-Fen; Kato, Takamitsu A.; Brogan, John R.; Shih, Hung-Ying; Kurimasa, Akihiro; Bedford, Joel S.; Chen, Benjamin P. C.; Little, John B.

    2017-01-01

    The catalytic subunit of DNA dependent protein kinase (DNA-PKcs) and its kinase activity are critical for mediation of non-homologous end-joining (NHEJ) of DNA double-strand breaks (DSB) in mammalian cells after gamma-ray irradiation. Additionally, DNA-PKcs phosphorylations at the T2609 cluster and the S2056 cluster also affect DSB repair and cellular sensitivity to gamma radiation. Previously we reported that phosphorylations within these two regions affect not only NHEJ but also homologous recombination repair (HRR) dependent DSB repair. In this study, we further examine phenotypic effects on cells bearing various combinations of mutations within either or both regions. Effects studied included cell killing as well as chromosomal aberration induction after 0.5–8 Gy gamma-ray irradiation delivered to synchronized cells during the G0/G1 phase of the cell cycle. Blocking phosphorylation within the T2609 cluster was most critical regarding sensitization and depended on the number of available phosphorylation sites. It was also especially interesting that only one substitution of alanine in each of the two clusters separately abolished the restoration of wild-type sensitivity by DNA-PKcs. Similar patterns were seen for induction of chromosomal aberrations, reflecting their connection to cell killing. To study possible change in coordination between HRR and NHEJ directed repair in these DNA-PKcs mutant cell lines, we compared the induction of sister chromatid exchanges (SCEs) by very low fluencies of alpha particles with mutant cells defective in the HRR pathway that is required for induction of SCEs. Levels of true SCEs induced by very low fluence of alpha-particle irradiation normally seen in wild-type cells were only slightly decreased in the S2056 cluster mutants, but were completely abolished in the T2609 cluster mutants and were indistinguishable from levels seen in HRR deficient cells. Again, a single substitution in the S2056 together with a single

  16. Isomeric cross-section ratio for the formation of 58Com,g in neutron, proton, deuteron, and alpha-particle induced reactions in the energy region up to 25 MeV

    NASA Astrophysics Data System (ADS)

    Sudár, S.; Qaim, S. M.

    1996-06-01

    Excitation functions were determined for 58Fe(p,n)58Com, natFe(d,xn)58Com, 55Mn(α,n)58Com, and 59Co(n,2n)58Com reactions from the respective thresholds to 14.12 MeV in work with protons, 12.97 MeV with deuterons, 13 MeV with neutrons, and 25.52 MeV with alpha particles. The radioactivity of the activation product 58Com(T1/2=9.15 h) was determined by high resolution γ-ray and x-ray spectrometry. Using the present σm results and the (σm+σg) data reported earlier, the isomeric cross-section ratio σm/(σm+σg) was determined for each reaction. Statistical model calculations taking into account the precompound effects were performed for the above-mentioned four reactions as well as for the 58Ni(n,p)58Com,g process. A consistent set of model parameters was used. The isomeric cross-section ratio for the pair 58Com,g strongly depends on the level scheme and branching ratios of the known levels of 58Co. Different reactions produced different angular momentum distributions of the compound nucleus, resulting in different isomeric cross-section ratio at the same excitation of the compound nucleus. The ratio was found to be relatively high for target nuclei with high spin values.

  17. The RBE of 3.4 MeV alpha-particles and 0.565 MeV neutrons relative to 60Co gamma-rays for neoplastic transformation of human hybrid cells and the impact of culture conditions.

    PubMed

    Frankenberg-Schwager, M; Spieren, S; Pralle, E; Giesen, U; Brede, H J; Thiemig, M; Frankenberg, D

    2010-01-01

    The neoplastic transformation of human hybrid CGL1 cells is affected by perturbations from external influences such as serum batch and concentration, the number of medium changes during the 21-day expression period and cell seeding density. Nevertheless, for doses up to 1.5 Gy, published transformation frequencies for low linear energy transfer (LET) radiations (gamma-rays, MeV electrons or photons) are in good agreement, whereas for higher doses larger variations are reported. The (60)Co gamma-ray data here for doses up to 1.5 Gy, using a low-yield serum batch and only one medium change, are in agreement with published frequencies of neoplastic transformation of human hybrid cells. For 3.4 MeV alpha-particles (LET = 124 keV/mum) and 0.565 MeV monoenergetic neutrons relative to low doses of (60)Co gamma-rays, a maximum relative biological effectiveness (RBE(M)) of 2.8 +/- 0.2 and 1.5 +/- 0.2, respectively, was calculated. Surprisingly, at higher doses of (60)Co gamma-rays lower frequencies of neoplastic transformation were observed. This non-monotonic dose relationship for neoplastic transformation by (60)Co gamma-rays is likely due to the lack of a G2/M arrest observed at low doses resulting in higher transformation frequencies per dose, whereas the lower frequencies per dose observed for higher doses are likely related to the induction of a G2/M arrest.

  18. Monitoring pipes for residual alpha contamination

    SciTech Connect

    MacArthur, D.; Rawool-Sullivan, M.; Dockray, T.

    1996-09-01

    The sensitivity and application of traditional alpha monitors is limited by the short range of alpha particles in air and in solid materials. Detecting small amounts of alpha-emitting contamination inside pipes presents particular problems. The alpha particle cannot penetrate the walls of the pipe. Associated gamma-ray detection and active neutron interrogation is often used to detect large amounts of radioactive material in pipes, but these methods are of limited use for detecting small amounts of contamination. Insertion of a traditional alpha probes works well in large diameter straight pipes, but is increasingly difficult as the pipe network becomes smaller in diameter and more complex. Monitors based on long-range alpha detection (LRAD) detect ionization of the ambient air rather than the alpha particles themselves. A small fan draws the ions into an externally mounted ion detector. Thus, the air in the pipe serves as both the detector gas and the mechanism for transporting the alpha-induced ions to a detection grid outside the pipe. All of the ions created by all of the contamination in the pipe can be measured in a single detector. Since ambient air serves as the probe, crushed or twisted sections of pipe can be monitored almost as effectively as straight sections. The pipe monitoring system described in the paper was tested both at LANL and BNFL`s Sellafield reprocessing facility in the UK. In this paper, we report on the first field tests of the pipe monitoring system.

  19. Bremsstrahlung in {alpha} Decay Reexamined

    SciTech Connect

    Boie, H.; Scheit, H.; Jentschura, U. D.; Koeck, F.; Lauer, M.; Schwalm, D.; Milstein, A. I.; Terekhov, I. S.

    2007-07-13

    A high-statistics measurement of bremsstrahlung emitted in the {alpha} decay of {sup 210}Po has been performed, which allows us to follow the photon spectra up to energies of {approx}500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the {alpha} particle and the emitted photon.

  20. TFTR alpha extraction and measurement: Development and testing of advanced alpha detectors: Final report

    SciTech Connect

    Wehring, B.W.

    1988-02-15

    Advanced alpha-particle detectors made of heavy elements were investigated as alternatives to silicon surface-barrier detectors for the ''foil-neutralization technique'' of alpha-particle diagnostics in fusion reactors with high neutron backgrounds. From an extensive literature review, it was decided that HgI/sub 2/ would make a more suitable detector for alpha-particle diagnostics than other heavy element detectors such as CdTe. Thus, HgI/sub 2/ detectors were designed and fabricated. Experimental tests were performed to determine detector characteristics and detector responses to alpha particles. Radiation noise measurements were also performed using the North Carolina State University PULSTAR nuclear reactor for both the HgI/sub 2/ detectors and commercial Si(Au) surface barrier detectors. 15 refs., 1 fig.