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Sample records for recoil alpha particle

  1. In situ production of alpha particles and alpha recoil particles in quartz applied to ESR studies of oxygen vacancies

    NASA Astrophysics Data System (ADS)

    Toyoda, S.; Rink, W. J.; Yonezawa, C.; Matsue, H.; Kagami, T.

    2001-12-01

    The intensity of an ESR signal associated with oxygen vacancies in quartz (E 1' center and heat-treated E 1' center) are correlated with the radiometric age of their host rocks. Two natural processes are responsible for the production of oxygen vacancies (1) lattice damage along alpha recoil and alpha particle tracks and (2) randomly distributed ionization damage from energetic electrons (beta particles) and gamma photons. The aim of this paper was to determine whether the track damage process is dominant relative to the ionization processes. Heat-treated E 1' centers are considered a proxy measure of the oxygen vacancy concentration. In situ alpha irradiation of quartz was accomplished by neutron irradiation of lithium and boron-bearing quartz. We found that the oxygen vacancy population measured by ESR was a factor of 2 higher than estimated from calculations of the damage using Ziegler's TRIM software. Considering the uncertainties in absolute determinations of spin concentration from ESR signals, the agreement is very good and supports the theory that alpha particle damage is largely responsible for oxygen vacancy production during natural irradiation of quartz over intervals of hundreds of millions of years.

  2. Transport of Radioactive Material by Alpha Recoil

    SciTech Connect

    Icenhour, A.S.

    2005-05-19

    The movement of high-specific-activity radioactive particles (i.e., alpha recoil) has been observed and studied since the early 1900s. These studies have been motivated by concerns about containment of radioactivity and the protection of human health. Additionally, studies have investigated the potential advantage of alpha recoil to effect separations of various isotopes. This report provides a review of the observations and results of a number of the studies.

  3. Biological effect of lead-212 localized in the nucleus of mammalian cells: role of recoil energy in the radiotoxicity of internal alpha-particle emitters.

    PubMed

    Azure, M T; Archer, R D; Sastry, K S; Rao, D V; Howell, R W

    1994-11-01

    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 gamma 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 beta-particle emitter 212Pb decays to the alpha-particle-emitting daughters 212Bi and 212Po, these studies provide information on the biological effects of alpha-particle decays that occur in the cell nucleus. Our earlier studies with cells of the same cell line using 210Po (emits 5.3 MeV alpha 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

  4. Alpha Particle

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Term that is sometimes used to describe a helium nucleus, a positively charged particle that consists of two protons and two neutrons, bound together. Alpha particles, which were discovered by Ernest Rutherford (1871-1937) in 1898, are emitted by atomic nuclei that are undergoing alpha radioactivity. During this process, an unstable heavy nucleus spontaneously emits an alpha particle and transmut...

  5. Exerpts from the history of alpha recoils.

    PubMed

    Samuelsson, Christer

    2011-05-01

    Any confined air volume holding radon ((222)Rn) gas bears a memory of past radon concentrations due to (210)Pb (T(1/2) = 22 y) and its progenies entrapped in all solid objects in the volume. The efforts of quantifying past radon exposures by means of the left-behind long-lived radon progenies started in 1987 with this author's unsuccessful trials of removing (214)Po from radon exposed glass objects. In this contribution the history and different techniques of assessing radon exposure to man in retrospect will be overviewed. The main focus will be on the implantation of alpha recoils into glass surfaces, but also potential traps in radon dwellings will be discussed. It is concluded that for a successful retrospective application, three crucial imperatives must be met, i.e. firstly, the object must persistently store a certain fraction of the created (210)Pb atoms, secondly, be resistant over decades towards disturbances from the outside and thirdly, all (210)Pb atoms analysed must originate from airborne radon only. For large-scale radon epidemiological studies, non-destructive and inexpensive measurement techniques are essential. Large-scale studies cannot be based on objects rarely found in dwellings or not available for measurements. PMID:21306801

  6. Isotopic disequilibrium of uranium: alpha-recoil damage and preferential solution effects

    SciTech Connect

    Fleischer, R.L.

    1980-02-29

    Preferential loss of uranium-234 relative to uranium-238 from rocks into solutions has long been attributed to recoiling alpha-emitting nuclei. Direct evidence has been obtained for two mechanisms, first, recoil ejection from grains, and now release by natural etching of alpha-recoil tracks. The observations have implications for radon emanation and for the storage of alpha-emitting radioactive waste.

  7. 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. PMID:11233567

  8. Isotopic disequilibrium of uranium: alpha-recoil damage and preferential solution effects.

    PubMed

    Fleischer, R L

    1980-02-29

    Preferential loss of uranium-234 relative to uranium-238 from rocks into solutions has long been attributed to recoiling alpha-emitting nuclei. Direct evidence has been obtained for two mechanisms, first, recoil ejection from grains, and now release by natural etching of alpha-recoil tracks. The observations have implications for radon emanation and for the storage of alpha-emitting radioactive waste. PMID:17830457

  9. Recoil range distributions of residues from. cap alpha. + /sup 59/Co reactions

    SciTech Connect

    Gadioli, E.; Gadioli Erba, E.; Parker, D.J.; Asher, J.

    1985-10-01

    The recoil range distributions of /sup 61/Cu, /sup 60/Cu, /sup 58/Co, /sup 57/Co, /sup 56/Co, /sup 54/Mn, and /sup 52/Mn residual nuclei produced in ..cap alpha.. particle bombardment of /sup 59/Co at 38, 50, 65, and 85 MeV have been measured and analyzed. Analysis of these measurements, as well as other recently published measurements of longitudinal linear momentum transfer to residue isobars at energies extending up to roughly-equal200 MeV, in the same reaction, shows that calculations based on the exciton model and a realistic description of the ..cap alpha..-nucleus interaction allow a quantitatively correct description of ..cap alpha..-induced reactions. Contrary to recent suggestions, data of this kind do not seem to indicate a change in the general character of the ..cap alpha..-nucleus interaction for incident energies below roughly-equal50 MeV/nucleon.

  10. Alpha-recoil thorium-234: dissolution into water and the uranium-234/uranium-238 disequilibrium in nature.

    PubMed

    Kigoshi, K

    1971-07-01

    The rate of ejection of alpha-recoil thorium-234 into solution from the surface of zircon sand gives an alpha-recoil range of 550 angstroms. The alpha-recoil thorium-234 atoms ejected into the groundwater may supply excess uranium-234. In pelagic sediments, ejected alpha-recoil thorium-234 may contribute to the supply of mobile uranium-234 in the sedimentary column. PMID:17747313

  11. A Critical Review of Alpha Radionuclide Therapy-How to Deal with Recoiling Daughters?

    PubMed

    de Kruijff, Robin M; Wolterbeek, Hubert T; Denkova, Antonia G

    2015-01-01

    This review presents an overview of the successes and challenges currently faced in alpha radionuclide therapy. Alpha particles have an advantage in killing tumour cells as compared to beta or gamma radiation due to their short penetration depth and high linear energy transfer (LET). Touching briefly on the clinical successes of radionuclides emitting only one alpha particle, the main focus of this article lies on those alpha-emitting radionuclides with multiple alpha-emitting daughters in their decay chain. While having the advantage of longer half-lives, the recoiled daughters of radionuclides like 224Ra (radium), 223Ra, and 225Ac (actinium) can do significant damage to healthy tissue when not retained at the tumour site. Three different approaches to deal with this problem are discussed: encapsulation in a nano-carrier, fast uptake of the alpha emitting radionuclides in tumour cells, and local administration. Each approach has been shown to have its advantages and disadvantages, but when larger activities need to be used clinically, nano-carriers appear to be the most promising solution for reducing toxic effects, provided there is no accumulation in healthy tissue. PMID:26066613

  12. A Critical Review of Alpha Radionuclide Therapy—How to Deal with Recoiling Daughters?

    PubMed Central

    de Kruijff, Robin M.; Wolterbeek, Hubert T.; Denkova, Antonia G.

    2015-01-01

    This review presents an overview of the successes and challenges currently faced in alpha radionuclide therapy. Alpha particles have an advantage in killing tumour cells as compared to beta or gamma radiation due to their short penetration depth and high linear energy transfer (LET). Touching briefly on the clinical successes of radionuclides emitting only one alpha particle, the main focus of this article lies on those alpha-emitting radionuclides with multiple alpha-emitting daughters in their decay chain. While having the advantage of longer half-lives, the recoiled daughters of radionuclides like 224Ra (radium), 223Ra, and 225Ac (actinium) can do significant damage to healthy tissue when not retained at the tumour site. Three different approaches to deal with this problem are discussed: encapsulation in a nano-carrier, fast uptake of the alpha emitting radionuclides in tumour cells, and local administration. Each approach has been shown to have its advantages and disadvantages, but when larger activities need to be used clinically, nano-carriers appear to be the most promising solution for reducing toxic effects, provided there is no accumulation in healthy tissue. PMID:26066613

  13. 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.

  14. 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.

  15. Digital characterization of recoil charged-particle tracks for neutron measurements

    SciTech Connect

    Turner, J.E.; Hunter, S.R.; Hamm, R.N.; Wright, H.A.; Hurst, G.S.; Gibson, W.A.

    1988-01-01

    We are developing a new optical ionization detector for imaging the track of a charged neutron-recoil particle in a gas. Electrons produced in the path of the recoil particle are excited by an external, high-voltage, RF, electric field of short duration. Their oscillatory motion causes ionization and excitation of nearby gas molecules, which then emit light in subsequent de-excitation. Two digital cameras image the optical radiation across two perpendicular planes and analyze it for the numbers of electrons in various volume elements along the track. These numbers constitute the digital characterization of the track. This information can then be used to infer the energy deposited in the track and the track LET in the gas. We have now observed alpha-particle tracks in a chamber utilizing these principles. The application of such a device for neutron dosimetry and neutron spectrometry will be described. 4 refs., 3 figs.

  16. 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.

  17. Treatment of solid tumors by interstitial release of recoiling short-lived alpha emitters

    NASA Astrophysics Data System (ADS)

    Arazi, L.; Cooks, T.; Schmidt, M.; Keisari, Y.; Kelson, I.

    2007-08-01

    A new method utilizing alpha particles to treat solid tumors is presented. Tumors are treated with interstitial radioactive sources which continually release short-lived alpha emitting atoms from their surface. The atoms disperse inside the tumor, delivering a high dose through their alpha decays. We implement this scheme using thin wire sources impregnated with 224Ra, which release by recoil 220Rn, 216Po and 212Pb atoms. This work aims to demonstrate the feasibility of our method by measuring the activity patterns of the released radionuclides in experimental tumors. Sources carrying 224Ra activities in the range 10-130 kBq were used in experiments on murine squamous cell carcinoma tumors. These included gamma spectroscopy of the dissected tumors and major organs, Fuji-plate autoradiography of histological tumor sections and tissue damage detection by Hematoxylin-Eosin staining. The measurements focused on 212Pb and 212Bi. The 220Rn/216Po distribution was treated theoretically using a simple diffusion model. A simplified scheme was used to convert measured 212Pb activities to absorbed dose estimates. Both physical and histological measurements confirmed the formation of a 5-7 mm diameter necrotic region receiving a therapeutic alpha-particle dose around the source. The necrotic regions shape closely corresponded to the measured activity patterns. 212Pb was found to leave the tumor through the blood at a rate which decreased with tumor mass. Our results suggest that the proposed method, termed DART (diffusing alpha-emitters radiation therapy), may potentially be useful for the treatment of human patients.

  18. 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.

  19. 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.

  20. Alpha-recoil damage: Relation to isotopic disequilibrium and leaching of radionuclides

    SciTech Connect

    Fleischer, R.L. )

    1988-06-01

    The observation by Raabe et al. (1973) of large differences between the solubilities of isotopically different plutonium dioxides, has led to the recognition of preferential etching of recoil damage as a widespread phenomenon for alpha-active radionuclides. The associated preferential solubility of the products of alpha decay, along with direct recoil ejection, are the two specific microscopic mechanisms that are documented as causes of isotopic disequilibrium in the U and Th decay series. Similarly, leaching plays a significant role in releasing {sup 222}Rn from natural substances, {sup 222}Rn being the alpha-decay product of {sup 226}Ra. The average annealing time in nature of the damage sites can be inferred from the extent of isotopic disequilibrium for different isotopic pairs in the Th and U decay chains.

  1. Long range alpha particle detector

    DOEpatents

    MacArthur, Duncan W.; Wolf, Michael A.; McAtee, James L.; Unruh, Wesley P.; Cucchiara, Alfred L.; Huchton, Roger L.

    1993-01-01

    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.

  2. 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.

  3. Elution behaviour of alpha-recoil atoms into etchant and ovservation of their tracks on the mica surface

    NASA Astrophysics Data System (ADS)

    Hashimoto, Tetsuo; Komatsu, Shigemi; Kido, Kazuo; Sotobayashi, Takeshi

    1980-12-01

    Muscovite samples, which were irradiated with alpha-recoil atoms emitted from a thinly electrodeposited 232U-source in a vacuum chamber of about 10 -2 Torr, were subjected to a chemical etching treatment with a hydrofluoric acid solution to develop alpha-recoil tracks. The transferred alpha-activities of 224Ra and 212Po, supported by 212Pb, on the mica surface were repeatedly measured after every etching treatment. The results showed that the 224Ra could be rapidly eluted out at earlier etching stages, in contrast to appreciably delayed elution of 212Po. These findings, along with annealing experiments on mica, imply that the recoil range of 224Ra, originated from the parent 228Th by a single decay process, is shorter than the total recoil range of 212Po, which can penetrate partially into inner mica layers through its preceding multiple alpha-decay processes after injection of its precursors into the mica. Scanning electron and phase-contrast microscopic observation of the etched mica surfaces indicated an apparent dependence of the recoil-track etch pit size on the number of succesive alpha-decays.

  4. 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.

  5. 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.

  6. 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.

  7. Alpha particle confinement in tandem mirrors

    SciTech Connect

    Devoto, R.S.; Ohnishi, M.; Kerns, J.; Woo, J.T.

    1980-10-10

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

  8. 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. PMID:15640792

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Seth, Susnata; Das, Mala

    2016-04-01

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

  12. 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.

  13. High resolution alpha particle spectrometry through collimation

    NASA Astrophysics Data System (ADS)

    Park, Seunghoon; Kwak, Sung-Woo; Kang, Han-Byeol

    2015-06-01

    Alpha particle spectrometry with collimation is a useful method for identifying nuclear materials among various nuclides. A mesh type collimator reduces the low energy tail and broadened energy distribution by cutting off particles with a low incidence angle. The relation between the resolution and the counting efficiency can be investigated by changing a ratio of the mesh hole diameter and the collimator thickness. Through collimation, a target particle can be distinguished by a PIPS® detector under a mixture of various nuclides.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. The status of alpha-particle diagnostics

    SciTech Connect

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

    1992-01-01

    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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Potential effects of alpha-recoil on uranium-series dating of calcrete

    USGS Publications Warehouse

    Neymark, L.A.

    2011-01-01

    Evaluation of paleosol ages in the vicinity of Yucca Mountain, Nevada, at the time the site of a proposed high-level nuclear waste repository, is important for fault-displacement hazard assessment. Uranium-series isotope data were obtained for surface and subsurface calcrete samples from trenches and boreholes in Midway Valley, Nevada, adjacent to Yucca Mountain. 230Th/U ages of 33 surface samples range from 1.3 to 423 thousand years (ka) and the back-calculated 234U/238U initial activity ratios (AR) are relatively constant with a mean value of 1.54 ± 0.15 (1σ), which is consistent with the closed-system behavior. Subsurface calcrete samples are too old to be dated by the 230Th/U method. U-Pb data for post-pedogenic botryoidal opal from a subsurface calcrete sample show that these subsurface calcrete samples are older than ~ 1.65 million years (Ma), old enough to have attained secular equilibrium had their U-Th systems remained closed. However, subsurface calcrete samples show U-series disequilibrium indicating open-system behavior of 238U daughter isotopes, in contrast with the surface calcrete, where open-system behavior is not evident. Data for 21 subsurface calcrete samples yielded calculable 234U/238U model ages ranging from 130 to 1875 ka (assuming an initial AR of 1.54 ± 0.15, the mean value calculated for the surface calcrete samples). A simple model describing continuous α-recoil loss predicts that the 234U/238U and 230Th/238U ARs reach steady-state values ~ 2 Ma after calcrete formation. Potential effects of open-system behavior on 230Th/U ages and initial 234U/238U ARs for younger surface calcrete were estimated using data for old subsurface calcrete samples with the 234U loss and assuming that the total time of water-rock interaction is the only difference between these soils. The difference between the conventional closed-system and open-system ages may exceed errors of the calculated conventional ages for samples older than ~ 250 ka, but is

  4. 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.

  5. Thermal recrystallization of alpha-recoil damaged minerals of the pyrochlore structure type

    SciTech Connect

    Lumpkin, G.R.; Ewing, R.C.; Foltyn, E.M.

    1985-10-01

    Thermal recrystallization effects (heat of recrystallization and identification of phases formed), have been determined for naturally occurring members of the pyrochlore group which have received alpha doses of up to 4 X 10{sup 16} alphas/mg. The heats of recrystallization, E{sub t}, range from 125 to 210 J/g. Release of energy decreases as a function of crystallinity (estimated on the basis of the intensity of x-ray diffraction maxima), with the fully-metamict samples approaching 210 J/g. Lower measured values (40-125 J/g) are the result of alteration of the pyrochlores. Other metamict, complex oxides with stoichiometries of ABO{sub 4} and AB{sub 2}O{sub 6} have lower heats of recrystallization (40-85 J/g), and are easily distinguished from pyrochlore group minerals. Activation energies of recrystallization, E{sub a}, range between values of 0.29 to 0.97 eV, less than those measured for Pu-doped, synthetic zirconolites.

  6. Alpha particle analysis using PEARLS spectrometry

    SciTech Connect

    McKlveen, J.W.; Klingler, G.W.; McDowell, W.J.; Case, G.N.

    1984-01-01

    Alpha particle assay by conventional plate-counting methods is difficult because chemical separation, tracer techniques, and/or self-absorption losses in the final sample may cause either non-reproducible results or create unacceptable errors. PEARLS (Photon-Electron Rejecting Alpha Liquid Scintillation) Spectrometry is an attractive alternative since radionuclides may be extracted into a scintillator in which there would be no self-absorption or geometry problems and in which up to 100% chemical recovery and counting efficiency is possible. Sample preparation may include extraction of the alpha emitter of interest by a specific organic-phase-soluble compound directly into the liquid scintillator. Detection electronics use energy and pulse-shape discrimination to provide discrete alpha spectra and virtual absence of beta and gamma backgrounds. Backgrounds on the order of 0.01 cpm are readily achievable. Accuracy and reproducibility are typically in the 100 +-1% range. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium, and polonium assay. This paper will review liquid scintillation alpha counting methods and reference some of the specific applications. 8 refs., 1 fig.

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

    PubMed

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

    2016-09-01

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

  8. Recoil Separators for Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Blackmon, J. C.

    2004-10-01

    Hydrogen and helium capture reactions are important in many astrophysical environments. Measurements in inverse kinematics using recoil separators have demonstrated a particularly sensitive technique for studying low-yield capture reactions.(M. S. Smith, C. E. Rolfs, and C. A. Barnes, Nucl. Instrum. Meth. Phys. Res. A306) (1991) 233. This approach allows a low background rate to be achieved with a high detection efficiency (about 50%) for the particles of interest using a device with only modest acceptance. Recoil separators using a variety of ion-optic configurations have been installed at numerous accelerator facilities in the past decade and have been used to measure, for example, alpha capture reactions using stable beams(D. Rogalla et al.), Eur. Phys. J. 6 (1999) 471. and proton capture reactions using radioactive ion beams.(S. Bishop et al.), Phys. Rev. Lett. 90 (2003) 162501. Measurements in inverse kinematics are the only viable means for studying reactions on short-lived nuclei that are crucial for understanding stellar explosions, and a recoil separator optimized for the measurement of capture reactions with radioactive ion beams figures prominently into the design of the low energy experimental area at the Rare Isotope Accelerator (RIA). The operational requirements for such a device will be outlined, and recoil separator designs and characteristics will be presented.

  9. Alpha Particle Physics Experiments in the Tokamak Fusion Test Reactor

    SciTech Connect

    Budny, R.V.; Darrow, D.S.; Medley, S.S.; Nazikian, R.; Zweben, S.J.; et al.

    1998-12-14

    Alpha particle physics experiments were done on the Tokamak Fusion Test Reactor (TFTR) during its deuterium-tritium (DT) run from 1993-1997. These experiments utilized several new alpha particle diagnostics and hundreds of DT discharges to characterize the alpha particle confinement and wave-particle interactions. In general, the results from the alpha particle diagnostics agreed with the classical single-particle confinement model in magnetohydrodynamic (MHD) quiescent discharges. Also, the observed alpha particle interactions with sawteeth, toroidal Alfvén eigenmodes (TAE), and ion cyclotron resonant frequency (ICRF) waves were roughly consistent with theoretical modeling. This paper reviews what was learned and identifies what remains to be understood.

  10. Evaluation of ZnO(Ga)Coatings as Alpha Particle Transducers Within a Neutron Generator

    SciTech Connect

    Mihalczo, J. T.; Neal, J. S.; Cooper, J. C.; Koltick, D. S.

    2002-05-02

    We report investigations and preliminary results from efforts to develop a recoil alpha particle detector for use in a portable neutron generator. The associated particle sealed tube neutron generator (APSTNG) will be used as an interrogation source for the Nuclear Materials Identification System (NMIS). With the emission of 14.1 MeV neutrons produced by the D-T reaction, associated 3.5 MeV alpha particles are emitted. These neutrons and alphas may then be correlated in time and direction, thus effectively ''tagging'' the neutrons of interest for subsequent use as an active nuclear materials interrogation source. The alpha particle detector uses a ZnO(Ga) scintillator coating applied to a fiber optic face plate. Gallium-doped zinc oxide is a fast (1.5 ns decay time), inorganic scintillator with a high melting point (1975C) and an absolute light yield of 1.5% of NaI(Tl). The scintillator is coated with a thin layer of nickel in order to screen out light produced in the tube and scattered deuterons and tritons. This coating also serves to prevent the buildup of charge on the detector surface. Results to date indicate promise as an effective alpha particle detector for the APSTNG for future use in the NMIS.

  11. Recoil-Implantation Of Multiple Radioisotopes Towards Wear Rate Measurements And Particle Tracing In Prosthetic Joints

    SciTech Connect

    Warner, Jacob A.; Timmers, Heiko; Smith, Paul N.; Scarvell, Jennifer M.; Gladkis, Laura

    2011-06-01

    This study demonstrates a new method of radioisotope labeling of ultra-high molecular weight polyethylene inserts in prosthetic joints for wear studies. The radioisotopes {sup 97}Ru, {sup 100}Pd, {sup 100}Rh, and {sup 101m}Rh are produced in fusion evaporation reactions induced by {sup 12}C ions in a {sup 92}Zr target foil. The fusion products recoil-implant into ultra-high molecular weight polyethylene plugs, machined to fit into the surface of the inserts. During laboratory simulations of the joint motion, a wear rate of the labeled polyethylene may be measured and the pathways of wear debris particles can be traced by detecting characteristic gamma-rays. The concentration profiles of the radioisotopes extend effectively uniformly from the polyethylene surface to a depth of about 4 {mu}m. The multiplicity of labeling and the use of several gamma-ray lines aids with avoiding systematic measurement uncertainties. Two polyethylene plugs were labeled and one was fitted into the surface of the tibial insert of a knee prosthesis, which had been worn in. Actuation over close to 100,000 cycles with a 900 N axial load and a 24 deg. flexion angle removed (14{+-}1)% of the gamma-ray activity from the plug. Most of this activity dispersed into the serum lubricant identifying this as the important debris pathway. Less than 1% activity was transferred to the femoral component of the prosthesis and the measured activity on the tibial tray was insignificant. Assuming uniform wear across the superior surface of the insert, a wear rate of (12{+-}3) mm{sup 3}/Megacycle was determined. This is consistent with wear rate measurements under similar conditions using other techniques.

  12. Evidence for alpha-particle chain configurations in sup 24 Mg

    SciTech Connect

    Wuosmaa, A.H.; Betts, R.R.; Back, B.B.; Freer, M.; Glagola, B.G.; Happ, T.; Henderson, D.J.; Wilt, P. ); Bearden, I.G. )

    1992-03-02

    We have observed a strong peak in the excitation function for the inelastic scattering reaction {sup 12}C({sup 12}C,{sup 12}C(0{sub 2}{sup +})){sup 12}C(0{sub 2}{sup +}) at an energy of {ital E}{sub c.m.}=32.5 MeV. A recoil coincidence arrangement between two double-sided silicon strip detectors was used to detect the {alpha} particles from the decaying {sup 12}C nuclei, and the reconstructed reaction kinematics were used to calculate the two-body scattering {ital Q} value. This excitation-function structure may be interpreted as arising from very highly deformed {alpha}-particle chain configurations in the nucleus {sup 24}Mg.

  13. Molecular modeling of the effects of 40Ar recoil in illite particles on their K-Ar isotope dating

    NASA Astrophysics Data System (ADS)

    Szczerba, Marek; Derkowski, Arkadiusz; Kalinichev, Andrey G.; Środoń, Jan

    2015-06-01

    The radioactive decay of 40K to 40Ar is the basis of isotope age determination of micaceous clay minerals formed during diagenesis. The difference in K-Ar ages between fine and coarse grained illite particles has been interpreted using detrital-authigenic components system, its crystallization history or post-crystallization diffusion. Yet another mechanism should also be considered: natural 40Ar recoil. Whether this recoil mechanism can result in a significant enough loss of 40Ar to provide observable decrease of K-Ar age of the finest illite crystallites at diagenetic temperatures - is the primary objective of this study which is based on molecular dynamics (MD) computer simulations. All the simulations were performed for the same kinetic energy (initial velocity) of the 40Ar atom, but for varying recoil angles that cover the entire range of their possible values. The results show that 40Ar recoil can lead to various deformations of the illite structure, often accompanied by the displacement of OH groups or breaking of the Si-O bonds. Depending on the recoil angle, there are four possible final positions of the 40Ar atom with respect to the 2:1 layer at the end of the simulation: it can remain in the interlayer space or end up in the closest tetrahedral, octahedral or the opposite tetrahedral sheet. No simulation angles were found for which the 40Ar atom after recoil passes completely through the 2:1 layer. The energy barrier for 40Ar passing through the hexagonal cavity from the tetrahedral sheet into the interlayer was calculated to be 17 kcal/mol. This reaction is strongly exothermic, therefore there is almost no possibility for 40Ar to remain in the tetrahedral sheet of the 2:1 layer over geological time periods. It will either leave the crystal, if close enough to the edge, or return to the interlayer space. On the other hand, if 40Ar ends up in the octahedral sheet after recoil, a substantially higher energy barrier of 55 kcal/mol prevents it from leaving

  14. Track nanodosimetry of an alpha particle.

    PubMed

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

    2002-01-01

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

  15. 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.

  16. Recent outgassing from the lunar surface: The Lunar Prospector Alpha Particle Spectrometer

    NASA Astrophysics Data System (ADS)

    Lawson, Stefanie L.; Feldman, William C.; Lawrence, David J.; Moore, Kurt R.; Elphic, Richard C.; Belian, Richard D.; Maurice, Sylvestre

    2005-09-01

    The Lunar Prospector Alpha Particle Spectrometer (APS) was designed to detect characteristic-energy alpha particles from the decay of Rn-222, Po-218, and Po-210 and to therefore map sites of radon release on the lunar surface. These three nuclides are radioactive daughters from the decay of U-238 hence the background level of alpha particle activity is a function of the lunar crustal uranium distribution. 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 random-walk process. The half-life of Rn-222 allows the gas to spread out by several hundred kilometers before it decays (depositing approximately half of the Po-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 Pb-210 precursor to Po-210 allows the mapping of gas vents which have been active over the last approximately 60 years. The APS found only a faint indication of Po-218 alpha particles. However, the Rn-222 alpha particle map shows that radon gas was emanating from the vicinity of craters Aristarchus and Kepler at the time of Lunar Prospector. The Po-210 alpha particle distribution reveals a variability in time and space of lunar gas release events. Po-210 and Rn-222 detections are associated with both thorium enhancements and lunar pyroclastic deposits.

  17. 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)

  18. Alpha particle loss in the TFTR DT experiments

    SciTech Connect

    Zweben, S.J.; Darrow, D.S.; Herrmann, H.W.

    1995-01-01

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

  19. Alpha-Particle Gas-Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Buehler, M. C.; Bell, L. D.; Hecht, M. H.

    1996-01-01

    An approximate model was developed to establish design curves for the saturation region and a more complete model developed to characterize the current-voltage curves for an alpha-particle pressure sensor. A simple two-parameter current-voltage expression was developed to describe the dependence of the ion current on pressure. The parameters are the saturation-current pressure coefficient and mu/D, the ion mobility/diffusion coefficient. The sensor is useful in the pressure range between 0.1 and 1000 mb using a 1 - mu Ci(241) Am source. Experimental results, taken between 1 and up to 200 mb, show the sensor operates with an anode voltage of 5 V and a sensitivity of 20 fA/mb in nitrogen.

  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. Analytic expressions for {alpha} particle preformation in heavy nuclei

    SciTech Connect

    Zhang, H. F.; Wang, Y. J.; Dong, J. M.; Royer, G.

    2009-11-15

    Experimental {alpha} decay energies and half-lives are investigated systematically to extract {alpha} particle preformation in heavy nuclei. Formulas for the preformation factors are proposed that can be used to guide microscopic studies on preformation factors and perform accurate calculations of the {alpha} decay half-lives. There is little evidence for the existence of an island of long stability of superheavy nuclei.

  2. Dosimetry and radiobiological studies of automated alpha-particle irradiator.

    PubMed

    M V, Jyothish Babu; Shinde, Sanjay G; S, Sunil Kumar; Ali, Manjoor; Vasumathy, R; Kumar, Amit; Kolekar, R; Kumar, Manish; Nema, P; Bhagwat, P V; Pandey, Badri N

    2013-01-01

    Understanding the effect of alpha radiation on biological systems is an important component of radiation risk assessment and associated health consequences. However, due to the short path length of alpha radiation in the atmosphere, in vitro radiobiological experiments cannot be performed with accuracy in terms of dose and specified exposure time. The present paper describes the design and dosimetry of an automated alpha-particle irradiator named 'BARC BioAlpha', which is suitable for in vitro radiobiological studies. Compared to alpha irradiators developed in other laboratories, BARC BioAlpha has integrated computer-controlled movement of the alpha-particle source, collimator, and electronic shutter. The diaphragm blades of the electronic shutter can control the area (diameter) of irradiation without any additional shielding, which is suitable for radiobiological bystander studies. To avoid irradiation with incorrect parameters, a software interlock is provided to prevent shutter opening, unless the user-specified speed of the source and collimator are achieved. The dosimetry of the alpha irradiator using CR-39 and silicon surface barrier detectors showed that ~4 MeV energy of the alpha particle reached the cells on the irradiation dish. The alpha irradiation was also demonstrated by the evaluation of DNA double-strand breaks in human cells. In conclusion, 'BARC BioAlpha' provides a user-friendly alpha irradiation system for radiobiological experiments with a novel automation mechanism for better accuracy of dose and exposure time. PMID:24266413

  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. 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.

  5. High acceptance recoil polarimeter

    SciTech Connect

    The HARP Collaboration

    1992-12-05

    In order to detect neutrons and protons in the 50 to 600 MeV energy range and measure their polarization, an efficient, low-noise, self-calibrating device is being designed. This detector, known as the High Acceptance Recoil Polarimeter (HARP), is based on the recoil principle of proton detection from np[r arrow]n[prime]p[prime] or pp[r arrow]p[prime]p[prime] scattering (detected particles are underlined) which intrinsically yields polarization information on the incoming particle. HARP will be commissioned to carry out experiments in 1994.

  6. 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.

  7. The HERMES recoil detector

    NASA Astrophysics Data System (ADS)

    Airapetian, A.; Aschenauer, E. C.; Belostotski, S.; Borisenko, A.; Bowles, J.; Brodski, I.; Bryzgalov, V.; Burns, J.; Capitani, G. P.; Carassiti, V.; Ciullo, G.; Clarkson, A.; Contalbrigo, M.; De Leo, R.; De Sanctis, E.; Diefenthaler, M.; Di Nezza, P.; Düren, M.; Ehrenfried, M.; Guler, H.; Gregor, I. M.; Hartig, M.; Hill, G.; Hoek, M.; Holler, Y.; Hristova, I.; Jo, H. S.; Kaiser, R.; Keri, T.; Kisselev, A.; Krause, B.; Krauss, B.; Lagamba, L.; Lehmann, I.; Lenisa, P.; Lu, S.; Lu, X.-G.; Lumsden, S.; Mahon, D.; Martinez de la Ossa, A.; Murray, M.; Mussgiller, A.; Nowak, W.-D.; Naryshkin, Y.; Osborne, A.; Pappalardo, L. L.; Perez-Benito, R.; Petrov, A.; Pickert, N.; Prahl, V.; Protopopescu, D.; Reinecke, M.; Riedl, C.; Rith, K.; Rosner, G.; Rubacek, L.; Ryckbosch, D.; Salomatin, Y.; Schnell, G.; Seitz, B.; Shearer, C.; Shutov, V.; Statera, M.; Steijger, J. J. M.; Stenzel, H.; Stewart, J.; Stinzing, F.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; Van Haarlem, Y.; Van Hulse, C.; Varanda, M.; Veretennikov, D.; Vilardi, I.; Vikhrov, V.; Vogel, C.; Yaschenko, S.; Ye, Z.; Yu, W.; Zeiler, D.; Zihlmann, B.

    2013-05-01

    For the final running period of HERA, a recoil detector was installed at the HERMES experiment to improve measurements of hard exclusive processes in charged-lepton nucleon scattering. Here, deeply virtual Compton scattering is of particular interest as this process provides constraints on generalised parton distributions that give access to the total angular momenta of quarks within the nucleon. The HERMES recoil detector was designed to improve the selection of exclusive events by a direct measurement of the four-momentum of the recoiling particle. It consisted of three components: two layers of double-sided silicon strip sensors inside the HERA beam vacuum, a two-barrel scintillating fibre tracker, and a photon detector. All sub-detectors were located inside a solenoidal magnetic field with a field strength of 1T. The recoil detector was installed in late 2005. After the commissioning of all components was finished in September 2006, it operated stably until the end of data taking at HERA end of June 2007. The present paper gives a brief overview of the physics processes of interest and the general detector design. The recoil detector components, their calibration, the momentum reconstruction of charged particles, and the event selection are described in detail. The paper closes with a summary of the performance of the detection system.

  8. 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.

  9. Recoil Based Fuel Breeding Fuel Structure

    SciTech Connect

    Popa-Simil, Liviu

    2008-07-01

    Nuclear transmutation reactions are based on the absorption of a smaller particle as neutron, proton, deuteron, alpha, etc. The resulting compound nucleus gets out of its initial lattice mainly by taking the recoil, also with help from its sudden change in chemical properties. The recoil implantation is used in correlation with thin and ultra thin materials mainly for producing radiopharmaceuticals and ultra-thin layer radioactive tracers. In nuclear reactors, the use of nano-particulate pellets could facilitate the recoil implantation for breeding, transmutation and partitioning purposes. Using enriched {sup 238}U or {sup 232}Th leads to {sup 239}Pu and {sup 233}U production while using other actinides as {sup 240}Pu, {sup 241}Am etc. leads to actinide burning. When such a lattice is immersed into a radiation resistant fluid (water, methanol, etc.), the recoiled product is transferred into the flowing fluid and removed from the hot area using a concentrator/purifier, preventing the occurrence of secondary transmutation reactions. The simulation of nuclear collision and energy transfer shows that the impacted nucleus recoils in the interstitial space creating a defect or lives small lattices. The defect diffuses, and if no recombination occurs it stops at the lattices boundaries. The nano-grains are coated in thin layer to get a hydrophilic shell to be washed by the collection liquid the particle is immersed in. The efficiency of collection depends on particle magnitude and nuclear reaction channel parameters. For {sup 239}Pu the direct recoil extraction rate is about 70% for {sup 238}UO{sub 2} grains of 5 nm diameters and is brought up to 95% by diffusion due to {sup 239}Neptunium incompatibility with Uranium dioxide lattice. Particles of 5 nm are hard to produce so a structure using particles of 100 nm have been tested. The particles were obtained by plasma sputtering in oxygen atmosphere. A novel effect as nano-cluster radiation damage robustness and cluster

  10. 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.

  11. 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.

  12. Full orbit calculation for lost alpha particle measurement on ITER

    SciTech Connect

    Funaki, D.; Isobe, M.; Nishiura, M.; Sato, Y.; Okamoto, A.; Kobuchi, T.; Kitajima, S.; Sasao, M.

    2008-10-15

    An orbit following calculation code with full gyromotion under the ITER magnetic field configuration has been developed to investigate escaping alpha particle orbits in ITER and to determine the geometrical arrangement for alpha particle detection. The code contained the full geometrical information of the first wall panels. It was carefully investigated whether an alpha particle escaping from the plasma through the last closed flux surface does not touch or intersect the first wall boundary before reaching the detection point. Candidates of blanket module modification have been studied to achieve effective measurement geometry for escaping alpha particle detection. The calculations showed that direct orbit loss and banana diffusion can be detected with a probe head recessed from the first wall surface.

  13. 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.

  14. 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.

  15. Elastic recoil detection

    NASA Astrophysics Data System (ADS)

    Bik, W. M. A.; Habraken, F. H. P. M.

    1993-07-01

    In elastic recoil detection (ERD) one determines the yield and energy of particles ejected out of the surface region of samples under MeV ion bombardment. By application of this surface and thin film analysis technique one can obtain quantitative information concerning the depth distribution of light elements in a sample to be analysed. The quantitativity and the depth resolving power are based on knowledge of the recoil cross section and the stopping power of high-energy ions in matter. This paper reviews the fundamentals of this technique and the various experimental methods for recoil identification. Furthermore, important features for material analysis, such as detection limits, depth resolution and elemental range are discussed. Some emphasis is put on the conversion of the spectral contribution of the elements to atomic concentrations in the films for several representative cases. Throughout the review numerous examples are given to illustrate the features of ERD and to demonstrate empirically the accuracy of the quantification method.

  16. Alpha and recoil track detection in poly(methyl methacrylate) (PMMA)—Towards a method for in vitro assessment of radiopharmaceuticals internalized in cancer cells

    SciTech Connect

    Myhra, S. Chakalova, R.; Falzone, N.

    2014-03-15

    A method for detection and characterization of single MeV α-particle and recoil tracks in PMMA photoresist by atomic force microscopy (AFM) analysis has been demonstrated. The energy deposition along the track is shown to lead to a latent pattern in the resist due to contrast reversal. It has been shown that the pattern, consisting of conical spikes, can be developed by conventional processing as a result of the dissolution rate of poly(methyl methacrylate) (PMMA) being greater than that for the modified material in the cylindrical volume of the track core. The spikes can be imaged and counted by routine AFM analysis. Investigations by angular-resolved near-grazing incidence reveal additional tracks that correspond to recoil tracks. The observations have been correlated with modelling, and shown to be in qualitative agreement with prevailing descriptions of collision cascades. The results may be relevant to technologies that are based on detection and characterization of single energetic ions. In particular, the direct visualization of the collision cascade may allow more accurate estimates of the actual interaction volume, which in turn will permit more precise assessment of dose distribution of α-emitting radionuclides used for targeted radiotherapy. The results could also be relevant to other diagnostic or process technologies based on interaction of energetic ions with matter.

  17. Luminescence imaging of water during alpha particle irradiation

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  18. 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. PMID:22202153

  19. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  2. Utility of extracting {alpha}-particle energy by waves

    SciTech Connect

    Fisch, N.J.; Herrmann, M.C.

    1994-05-01

    The utility of extracting {alpha}-particle power, and then diverting this power to fast fuel ions, is investigated. As power is diverted to fast ions and then to ions, a number of effects come into play, as the relative amounts of pressure taken up by electrons, fuel ions, and fast {alpha}-particles shift. In addition, if the {alpha}-particle power is diverted to fast fuel ions, there is an enhanced fusion reactivity because of the nonthermal component of the ion distribution. Some useful expressions for describing these effects are derived, and it is shown that fusion reactors with power density about twice what otherwise might be obtained can be contemplated, so long as a substantial amount of the {alpha}-particle power can be diverted. Interestingly, in this mode of operation, once the electron heat is sufficiently confined, further improvement in confinement is actually not desirable. A similar improvement in fusion power density can be obtained for advanced fuel mixtures such as D-He{sup 3}, where the power of both the energetic {alpha}-particles and the energetic protons might be diverted advantageously.

  3. 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. PMID:24857092

  4. 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.

  5. Continuous air monitor for alpha-emitting aerosol particles

    SciTech Connect

    McFarland, A.R.; Ortiz, C.A. . Dept. of Mechanical Engineering); Rodgers, J.C.; Nelson, D.C. )

    1990-01-01

    A new alpha Continuous Air Monitor (CAM) sampler is being developed for use in detecting the presence of alpha-emitting aerosol particles. The effort involves design, fabrication and evaluation of systems for the collection of aerosol and for the processing of data to speciate and quantify the alpha emitters of interest. At the present time we have a prototype of the aerosol sampling system and we have performed wind tunnel tests to characterize the performance of the device for different particle sizes, wind speeds, flow rates and internal design parameters. The results presented herein deal with the aerosol sampling aspects of the new CAM sampler. Work on the data processing, display and alarm functions is being done in parallel with the particle sampling work and will be reported separately at a later date. 17 refs., 5 figs., 3 tabs.

  6. Solar wind alpha particle capture at Mars and Venus

    NASA Astrophysics Data System (ADS)

    Stenberg, Gabriella; Barabash, Stas; Nilsson, Hans; Fedorov, Andrei; Brain, Dave

    2010-05-01

    Helium is detected in the atmospheres of both Mars and Venus. It is believed that radioactive decay of uranium and thorium in the interior of the planets' is not sufficient to account for the abundance of helium observed. Alpha particles in the solar wind are suggested to be an additional source of helium, especially at Mars. Recent hybrid simulations show that as much as 30% of the alpha particles can be lost from the solar wind due to charge-exchange processes associated with the Mars/solar wind interaction. We use ion data from the ASPERA-3 and ASPERA-4 instruments on Mars and Venus Express to estimate how efficient solar wind alpha particles are captured in the atmospheres of the two planets.

  7. Quantum dot solar cell tolerance to alpha-particle irradiation

    SciTech Connect

    Cress, Cory D.; Hubbard, Seth M.; Landi, Brian J.; Raffaelle, Ryne P.; Wilt, David M.

    2007-10-29

    The effects of alpha-particle irradiation on an InAs quantum dot (QD) array and GaAs-based InAs QD solar cells were investigated. Using photoluminescence (PL) mapping, the PL intensity at 872 and 1120 nm, corresponding to bulk GaAs and InAs QD emissions, respectively, were measured for a five-layer InAs QD array which had a spatially varying total alpha-particle dose. The spectral response and normalized current-voltage parameters of the solar cells, measured as a function of alpha-particle fluence, were used to investigate the change in device performance between GaAs solar cells with and without InAs QDs.

  8. Performance comparison of scintillators for alpha particle detectors

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  9. Mutagenic effects of alpha particles in normal human skin fibroblasts

    SciTech Connect

    Chen, D.J.; Carpenter, S.; Hanks, T.

    1992-12-31

    Alpha-irradiation to the bronchial airways from inhaled radon progeny increases the risk of developing lung cancer. The molecular mechanism of radon-induced lung cancer is not clear, but one of the most important genetic effects of ionizing radiation is the induction of gene mutation. Mutations, especially those associated with visible chromosome abnormalities in humans, have been associated with cancer. Therefore, our objective is to use a well-defined model system to determine the mutagenic potential of alpha particles in normal human skin cells and to define this action at the molecular level. Normal human skin fibroblasts were irradiated with alpha particles (3.59 MeV, LET 115 keV {mu}m{sup {minus}1}) emitted from the decay of {sup 238}Pu. Mutagenicity was determined at the X-linked hypoxanthine guanine phosphoribosyl transferase (HPRT) locus. Results from this study indicate that beta particles were more efficient in mutation induction than gamma rays. Based on the initial slopes of the dose-response curves, the RBE for mutation is about 8 for alpha particles. HPRT-deficient mutants which are resistant to 6-thioguanine have been isolated and analyzed by the Southern blot technique. To date, we have characterized 69 gamma-ray-induced and 195 alpha-particle-induced HPRT-deficient mutants. Our data indicate that more than 50% of all gamma-ray-induced mutants have band patterns identical to that observed for the normal structural HPRT gene, whereas the remaining mutants (45%) contain either a rearrangement, partial deletion, or total deletion of the HPRT gene. In contrast, only 30% of alpha-particle-induced human HPRT mutants contain a normal Southern blot pattern, and about 50% indicate total deletion of the HPRT gene. Our results support the notion that high-LET radiation produces more unrepaired or misrepaired DNA damage than do gamma rays.

  10. Solar wind alpha particle capture at Mars and Venus

    NASA Astrophysics Data System (ADS)

    Stenberg, Gabriella; Barabash, Stas; Nilsson, Hans; Fedorov, A.; Brain, David; André, Mats

    Helium is detected in the atmospheres of both Mars and Venus. It is believed that radioactive decay of uranium and thorium in the interior of the planets' is not sufficient to account for the abundance of helium observed. Alpha particles in the solar wind are suggested to be an additional source of helium, especially at Mars. Recent hybrid simulations show that as much as 30We use ion data from the ASPERA-3 and ASPERA-4 instruments on Mars and Venus Express to estimate how efficient solar wind alpha particles are captured in the atmospheres of the two planets.

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

    NASA Astrophysics Data System (ADS)

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

    2000-11-01

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

  12. The effect of alpha particles on bacteriophage T4Br+.

    PubMed

    Leont'eva, G A; Akoev, I G; Grigor'ev, A E

    1983-01-01

    It is generally accepted that heavy charged particles play an important part in generating the secondary flux of nuclear particles formed by the interaction of space hadrons with nuclei. It is assumed that these particles are responsible for the high biological efficiency of space hadrons in causing cellular damage by their strong interactions. To examine this assumption we investigated the effects of 5.3 MeV alpha particles on bacteriophage T4. This energy provides a LET value of 88.6 KeV/micrometer lying in the range of the highest biological efficiency. PMID:11542756

  13. Transport of Fusion Alpha Particles in ITER Scenarios

    NASA Astrophysics Data System (ADS)

    Bass, E. M.; Waltz, R. E.

    2014-10-01

    We predict the fusion-born alpha particle density in steady-state and hybrid (reverse shear) ITER scenarios with an integrated 1D transport model. The model combines ``stiff'' critical gradient alpha-driven Alfvén eigenmode (AE) transport with a quasilinear approximation of microturbulent transport. In an ITER baseline case, AE transport is found to redistribute alphas within the core but not propagate to the loss boundary. The remaining microturbulence at the edge causes negligible alpha-channel energy flux there (neglecting ripple loss). We set the AE stiff transport critical gradient threshold at gAE =gITG , below which microturbulence can nonlinearly suppress AE transport, and the more stringent condition gAE = 0 . Work supported in part by the US DOE under GA-Grant No. DE-FG02-95ER54309 and SciDAC-GSEP Grant No DE-FC02-08ER54977.

  14. MHD-Induced Alpha Particle Loss in TFTR

    SciTech Connect

    Darrow, D.S.; Fredrickson, E.D.; Taylor, G.; White, R.B.; Zweben, S.J.; von Goeler, S.

    1999-03-01

    MHD-induced increases in alpha particle loss to the wall were observed for both coherent modes and transient reconnection events using an array of scintillator detectors near the wall of Tokamak Fusion Test Reactor (TFTR). The magnitude of the coherent MHD-induced alpha loss as seen by these detectors was normally comparable to the MHD-quiescent first-orbit or toroidal-field ripple loss, but the magnitude of the alpha loss during reconnection events was up to 1000 times higher than this for a short time. Modeling suggest that the coherent MHD loss mechanism will be even less significant for future reactor-scale deuterium-tritium tokamaks due to the smaller ratio of the alpha gyroradius to minor radius.

  15. 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.

  16. 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.

  17. Alpha-particle losses in compact torsatron reactors

    SciTech Connect

    Painter, S.L.; Lyon, J.F.

    1989-01-01

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

  18. 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.

  19. 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.

  20. 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…

  1. 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.

  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. Model for alpha particle induced nuclear reactions: /sup 93/Nb(. cap alpha. ,x. cap alpha. ypzn) from 40--140 MeV

    SciTech Connect

    Gadioli, E.; Gadioli-Erba, E.; Hogan, J.J.; Jacak, B.V.

    1984-01-01

    A comprehensive model is introduced for alpha particle induced nuclear reactions. Five different mechanisms are examined and discussed. These include inelastic scattering of the incident alpha particle, nucleon pickup, binary fragmentation, dissolution of the alpha in the nuclear field, and preequilibrium processes initiated by alpha-nucleon collisions. A series of experiments was performed to measure the excitation functions of many nuclides produced from the irradiation of /sup 93/Nb by 40--140 MeV alpha particles. Together with alpha particle and proton spectra measured by other authors, these data form the basis of a test of the model introduced. A detailed analysis of the comparison between the calculated and experimental results, with particular emphasis on the interpretation of breakup processes, leads to the conclusion that breakup to four nucleons is preferred to the more commonly assumed binary fragmentation in that a much broader range of experimental data may be reproduced.

  4. Accounting for Recoil Effects in Geochronometers: A New Model Approach

    NASA Astrophysics Data System (ADS)

    Lee, V. E.; Huber, C.

    2012-12-01

    A number of geologically important chronometers are affected by, or owe their utility to, the "recoil effect". This effect describes the physical displacement of a nuclide due to energetic nuclear processes such as radioactive alpha decay (as in the case of various parent-daughter pairs in the uranium-series decay chains, and Sm-Nd), as well as neutron irradiation (in the case of the methodology for the 40Ar/39Ar dating method). The broad range of affected geochronometers means that the recoil effect can impact a wide range of dating method applications in the geosciences, including but not limited to: Earth surface processes, paleoclimate, volcanic processes, and cosmochemistry and planetary evolution. In particular, the recoil effect can have a notable impact on the use of fine grains (silt- and clay-sized particles) for geochronometric dating purposes. This is because recoil-induced loss of a nuclide from the surfaces of a grain can create an isotopically-depleted outer rind, and for small grains, this depleted rind can be volumetrically significant. When this recoil loss is measurable and occurs in a known time-dependent fashion, it can usefully serve as the basis for chronometers (such as the U-series comminution age method); in other cases recoil loss from fine particles creates an unwanted deviation from expected isotope values (such as for the Ar-Ar method). To improve both the accuracy and precision of ages inferred from geochronometric systems that involve the recoil of a key nuclide from small domains, it is necessary to quantify the magnitude of the recoil loss of that particular nuclide. It is also necessary to quantitatively describe the effect of geological processes that can alter the outer surface of grains, and hence the isotopically-depleted rind. Here we present a new mathematical and numerical model that includes two main features that enable enhanced accuracy and precision of ages determined from geochronometers. Since the surface area of the

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

    SciTech Connect

    Zweben, S.J.; Darrow, D.S.; Herrmann, H.W.; Redi, M.H.; Schivell, J.; White, R.B.

    1995-07-01

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

  6. Radiolytic gas production in the alpha particle degradation of plastics

    SciTech Connect

    Reed, D.T.; Hoh, J.; Emery, J.; Hobbs, D.

    1992-05-01

    Net gas generation due to alpha particle irradiation of polyethylene and polyvinyl chloride was investigated. Experiments were performed in an air environment at 30, 60, and 100{degree}C. The predominant radiolytic degradation products of polyethylene were hydrogen and carbon dioxide with a wide variety of trace organic species noted. Irradiation of polyvinyl chloride resulted in the formation of HCl in addition to the products observed for polyethylene. For both plastic materials, a strong enhancement of net yields was noted at 100{degree}C.

  7. Thick Source Alpha Particle Spectroscopy: Possibilities And Prospects

    NASA Astrophysics Data System (ADS)

    Michael, C. T.; Zacharias, N.; Hein, A.

    The new technique for the calculation of U and Th concentration which is based on the alpha particle spectrum taken from a thick sample by using a silicon detector is briefly described. Within the present study two major advantages of the technique will also be presented: the potentiality for detecting and providing an estimation of disequilibrium in the U and Th series -when present- for especially young sediments, and the potential use of the technique as a new method for isotopic dating of speleothems and other materials. Also the validity of the basic equation and the accuracy of this technique is tested.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

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

    SciTech Connect

    Biglari, H.; Diamond, P.H.

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

    SciTech Connect

    Herrmann, H.W.

    1997-09-01

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

  17. 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. PMID:18514364

  18. 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

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

    SciTech Connect

    Herrmann, Hans W.

    1997-06-01

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

  20. 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.

  1. 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

  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. 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.

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

    DOEpatents

    Post, D.E. Jr.; Hwang, D.Q.; Hovey, J.

    1983-11-16

    It is an object of the present invention to provide a better understanding of alpha particle behavior in a magnetically confined, energetic plasma. Another object of the present invention is to provide an improved means and method for studying and measuring the energy distribution of heated alpha particles in a confined plasma. Yet another object of the present invention is to permit detailed analysis of energetic alpha particle behavior in a magnetically confined plasma for use in near term fusion reactor experiments. A still further object of the present invention is to simulate energetic alpha particle behavior in a deuterium-tritium plasma confined in a fusion reactor without producing the neutron activation associated with the thus produced alpha particles.

  6. 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. PMID:8146279

  7. 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.

  8. Measurement of the Internal Magnetic Field of Plasmas using an Alpha Particle Source

    SciTech Connect

    S.J. Zweben; D.S. Darrow; P.W. Ross; J.L. Lowrance; G. Renda

    2004-05-13

    The internal magnetic fields of plasmas can be measured under certain conditions from the integrated v x B deflection of MeV alpha particles emitted by a small radioactive source. This alpha source and large-area alpha particle detector would be located inside the vacuum vessel but outside the plasma. Alphas with a typical energy of 5.5 MeV (241Am) can reach the center of almost all laboratory plasmas and magnetic fusion devices, so this method can potentially determine the q(r) profile of tokamaks or STs. Orbit calculations, background evaluations, and conceptual designs for such a vxB (or ''AVB'') detector are described.

  9. Observation of sawtooth redistribution of nonthermal, confined alpha particles in TFTR D-T discharges

    SciTech Connect

    Stratton, B.; Budny, R.; Chang, Z.; Fonck, R.; Wising, F.; Odblom, A.

    1996-05-01

    Radial profiles of the density of confined alpha particles with energies in the 0.15-0.6 MeV range are spectroscopically observed before and after a sawtooth crash in a TFTR D-T plasma. A large drop in the core alpha density is seen indicating expulsion of alphas from the core to the plasma periphery. The measured changes in the alpha density profiles are consistent with predictions based on the Kolesnichenko sawtooth model, indicating that it may be used to reliably predict the effect of sawteeth on fusion-produced alphas.

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

    SciTech Connect

    Rewoldt, G.

    1988-06-01

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

  11. 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. PMID:12382812

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

    NASA Astrophysics Data System (ADS)

    Gormley, Robert P.

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

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  15. 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.

  16. Alpha-particle scattering from sup 6 Li near the. alpha. - d breakup threshold

    SciTech Connect

    Samanta, C.; Ghosh, S.; Lahiri, M. ); Ray, S. ); Banerjee, S.R. )

    1992-04-01

    The {sup 6}Li({alpha},{alpha}{prime}) reaction was studied at {ital E}{sub {alpha}}=50 MeV. The angular distribution of the continuum region near the {sup 6}Li{r arrow}{alpha}+{ital d} breakup threshold (1.475 MeV) was measured for {theta}{sub lab}=7{degree}--40{degree}. The data were analyzed in terms of plane-wave and distorted-wave impulse approximation calculations. To study the possible effects of recombination of the breakup clusters in the exit channel, distorted-wave Born approximation calculations were also performed.

  17. Instabilities Driven by the Drift and Temperature Anisotropy of Alpha Particles in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Verscharen, Daniel; Bourouaine, Sofiane; Chandran, Benjamin D. G.

    2013-08-01

    We investigate the conditions under which parallel-propagating Alfvén/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 ∥α >~ 0.25v A, where w ∥α is the parallel alpha-particle thermal speed and v A is the Alfvén 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 ∥α/v 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 α 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 α = 0. We discuss the relevance of our results to alpha particles in the solar wind near 1 AU.

  18. Present status of alpha-particle condensed states in 4n self-conjugate nuclei

    SciTech Connect

    Funaki, Y.; Yamada, T.; Horiuchi, H.; Tohsaki, A.; Roepke, G.; Schuck, P.

    2010-05-12

    Low density states near the 3alpha and 4alpha breakup threshold in {sup 12}C and {sup 16}O, respectively, are discussed in terms of the alpha-particle condensation. Calculations are performed in OCM (Orthogonality Condition Model) and THSR (Tohsaki-Horiuchi-Schuck-Roepke) approaches. The 0{sub 2}{sup +} state in {sup 12}C and the 0{sub 6}{sup +} state in {sup 16}O are shown to have dilute density structures and give strong enhancement of the occupation of the S-state c.o.m. orbital of the alpha-particles. The possibility of the existence of alpha-particle condensed states in heavier nalpha nuclei is also discussed.

  19. 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.

  20. LIMITS ON ALPHA PARTICLE TEMPERATURE ANISOTROPY AND DIFFERENTIAL FLOW FROM KINETIC INSTABILITIES: SOLAR WIND OBSERVATIONS

    SciTech Connect

    Bourouaine, Sofiane; Verscharen, Daniel; Chandran, Benjamin D. G.; Maruca, Bennett A.; Kasper, Justin C.

    2013-11-01

    Previous studies have shown that the observed temperature anisotropies of protons and alpha particles in the solar wind are constrained by theoretical thresholds for pressure and anisotropy driven instabilities such as the Alfvén/ion-cyclotron (A/IC) and fast-magnetosonic/whistler (FM/W) instabilities. In this Letter, we use a long period of in situ measurements provided by the Wind spacecraft's Faraday cups to investigate the combined constraint on the alpha proton differential flow velocity and the alpha particle temperature anisotropy due to A/IC and FM/W instabilities. We show that the majority of the data are constrained to lie within the region of parameter space in which A/IC and FM/W waves are either stable or have extremely low growth rates. In the minority of observed cases in which the growth rate of the A/IC (FM/W) instability is comparatively large, we find relatively higher values of T {sub α}/T {sub p} (T {sub ∥α}/T {sub ∥p}) when the alpha proton differential flow velocity is small, where T {sub α} and T {sub p} (T {sub ∥α} and T {sub ∥p}) are the perpendicular (parallel) temperatures of alpha particles and protons. We conjecture that this observed feature might arise from preferential alpha particle heating which can drive the alpha particles beyond the instability thresholds.

  1. 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

  2. Influence of source composition and particle energy on the determination of gross alpha activity.

    PubMed

    Timón, A Fernández; Vargas, M Jurado; Sánchez, A B Ruano; Pérez, J de la Torre; Sánchez, A Martín

    2013-12-01

    The influence of different source compositions and α-particle energies on the detection efficiency of a gas-flow proportional counter was examined using experimental measurements and Monte Carlo simulations. Efficiency variation with alpha-particle energy was very marked, being less significant with the substrate composition. These results show that the determination of gross alpha activity in an unknown sample must be carried out very carefully in order to give a correct estimation of its activity. PMID:24184741

  3. 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.

  4. An alpha particle diagnostic based on measurements of lower hybrid wave fluctuations

    SciTech Connect

    Wong, K.L.

    1989-07-01

    It is shown that the one-dimensional alpha particle velocity distribution function can be determined from the fluctuation- dissipation theorem based on measurements of lower hybrid wave fluctuations in an equilibrium plasma. This method uses collective Thomson scattering data with large signal-to-noise ratio, but it is applicable only when the alpha particles have an isotropic velocity distribution. 16 refs., 1 fig.

  5. {alpha}-particle optical potentials for nuclear astrophysics (NA) and nuclear technology (NT)

    SciTech Connect

    Avrigeanu, V.; Avrigeanu, M.

    2012-11-20

    The high precision of recent measurements for low-energy {alpha}-particle elastic-scattering as well as induced-reaction data makes possible the understanding of actual limits and possible improvement of the global optical model potentials parameters. Involvement of recent optical potentials for reliable description of both the elastic scattering and emission of {alpha}-particles, of equal interest for nuclear astrophysics (NA) and nuclear technology (NT) for fusion devices, is discussed in the present work.

  6. Recombination in liquid xenon for low-energy recoils

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Mei, Dongming; Cubed Collaboration

    2014-09-01

    Detector response to low-energy recoils in sub-keV region is critical to detection of low-mass dark matter particles-WIMPS (Weakly interacting massive particles). The role of electron-ion recombination is important to the interpretation of the relation between ionization yield and scintillation yield, which are in general anti-correlated. Recent experimental results show that ionization yield increases down to keV range. This phenomenon contradicts general understanding for low energy recoils in the keV range in which direct excitation dominates. The explanation is that recombination becomes much less efficient when the track length is smaller than the thermalization distance of electrons. However, recombination rate is also proportional to ionization density, which is very high for keV recoils. To understand how recombination rate behaves for keV recoils, we calculated both initial recombination rate and volume recombination rate for keV recoils in liquid xenon. In this paper, we show the results of the calculated recombination rate as a function of recoil energy for both electronic recoils and nuclear recoils. Detector response to low-energy recoils in sub-keV region is critical to detection of low-mass dark matter particles-WIMPS (Weakly interacting massive particles). The role of electron-ion recombination is important to the interpretation of the relation between ionization yield and scintillation yield, which are in general anti-correlated. Recent experimental results show that ionization yield increases down to keV range. This phenomenon contradicts general understanding for low energy recoils in the keV range in which direct excitation dominates. The explanation is that recombination becomes much less efficient when the track length is smaller than the thermalization distance of electrons. However, recombination rate is also proportional to ionization density, which is very high for keV recoils. To understand how recombination rate behaves for keV recoils

  7. 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.

  8. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  10. Measurement of the internal magnetic field of plasmas using an alpha particle source

    SciTech Connect

    Zweben, S.J.; Darrow, D.S.; Ross, P.W.; Lowrance, J.L.; Renda, G.

    2004-10-01

    The internal magnetic fields of plasmas can be measured under certain conditions from the integrated vxB deflection of MeV alpha particles emitted by a small radioactive source. The alpha source and large-area alpha particle detector would be located inside the vacuum vessel but outside the plasma. Alphas with a typical energy of 5.5 MeV ({sup 241}Am) can reach the center of almost all laboratory plasmas and magnetic fusion devices, so this method can potentially determine the q(r) profile of tokamaks or spherical toris (STs). Orbit calculations, background evaluations, and conceptual designs for such {alpha} vxB (or 'AVB') detector are described.

  11. 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.

  12. Simulation of {alpha}-particle redistribution due to sawteeth on TFTR

    SciTech Connect

    Yi Zhao; White, R.B.

    1996-12-31

    In recent Deuterium-Tritium experiments on the Tokamak Fusion Test Reactor (TFTR), both the Pellet Charge Exchange (PCX) and the alpha Charge Exchange Recombination Spectroscopy ({alpha}-CHERS) diagnostics indicate that sawtooth oscillations can cause significant broadening of the fusion alpha radial density profile. The authors investigate this sawtooth mixing phenomenon by applying a Hamiltonian guiding center approach. A model of time evolution of the Kadomtsev-type sawtooth is constructed. The presence of more than one mode in the nonlinear stage of the sawtooth crash is necessary to cause significant broadening of the alpha density profile. Use of numerical equilibria allows us to perform detailed comparisons with TFTR experimental data. The results are in reasonable agreement with {alpha}-CHERS and show a broadening of alpha particles similar to that seen in PCX measurements.

  13. The HERMES Recoil Detector

    SciTech Connect

    Kaiser, R.

    2006-07-11

    The HERMES Collaboration is installing a new Recoil Detector to upgrade the spectrometer for measurements of hard exclusive electron/positron scattering reactions, in particular deeply virtual Compton scattering. These measurements will provide access to generalised parton distributions and hence to the localisation of quarks inside hadrons and to their orbital angular momentum. The HERMES Recoil Detector consists of three active components: a silicon detector surrounding the target cell inside the beam vacuum, a scintillating fibre tracker and a photon detector consisting of three layers of tungsten/scintillator. All three detectors are located inside a solenoidal magnetic field of 1 Tesla. The Recoil Detector was extensively tested with cosmic muons over the summer of 2005 and is being installed in the winter of 2005/6 for data taking until summer 2007.

  14. 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.

  15. 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.

  16. Modelling NPA measurements of alpha-particle distributions in JET and TFTR

    NASA Astrophysics Data System (ADS)

    McClements, K. G.; Dendy, R. O.; Gondhalekar, A.

    1997-11-01

    Neutral particle analyser (NPA) measurements of the DT fusion alpha-particle energy distribution function are simulated by geometrically weighted spatial line integrals of the time-evolving population. The latter is modelled semi-analytically using a simplified Fokker-Planck equation, where the alpha-particle source term is derived from measured fusion reactivity, and plasma collisionality from measured electron density and temperature profiles. This model [1] is benchmarked by zero-free-parameters agreement with TFTR tritium beam blip results [2]. We can thus quantify the differences between the measured NPA spectrum and the local alpha-particle distribution in the plasma core. [1] K G McClements et al, JET Report JET-R(97)02. [2] S S Medley et al, Plasma Phys Contr Fusion 38, 1779 (1996). This work was supported in part by the UK Department of Trade and Industry and Euratom

  17. 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}.

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

    PubMed

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

    2007-05-01

    An experimental method for determining the range of alpha particles in films based on I-V(s) analysis has been suggested. The range of 5.5 MeV alpha particles in PbI(2) films determined by this technique is 30+/-5 microm, and this value is in agreement with the value calculated by SRIM (the stopping and range of ions in matter), r=24 microm in PbI(2). More than 100 I-V(s) of PbI(2) films with different thicknesses and quality have been analyzed, and the influence of alpha particle radiation on PbI(2) I-V(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(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(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(s). PMID:17552841

  19. Determination of neutron-induced alpha-particle cross sections on carbon using the response of a liquid scintillation detector

    SciTech Connect

    Brede, H.J.; Dietze, G.; Klein, H.; Schoelermann, H. )

    1991-01-01

    This paper presents the sums of the cross section {sup 12}C(n, {alpha}{sub 0}) {sup 9}Be and {sup 12}C(n, N{prime}3{alpha}) determined in the neutron energy range between 7.4 and 11 MeV. An NE-213 scintillation detector is simultaneously used as a carbon target, an alpha-particle detector, and a neutron fluence monitor. By comparing the measured and calculated response spectra, the neutron-induced alpha-particle events in the scintillation volume are separated and the cross sections {sigma}{sub n,{alpha}0} + {sigma}{sub n,n{prime}3{alpha}} are determined relative to the n-p scattering cross section. The pulse-height distribution due to alpha particles allows the angular distribution to be extracted on the basis of the reaction kinematics and an accurately determined light output function for alpha particles in the NE-213 detector.

  20. 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).

  1. 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. PMID:25634901

  2. 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.

  3. Alpha-particle emission probabilities in the decay of 240Pu.

    PubMed

    Sibbens, G; Pommé, S; Altzitzoglou, T; García-Toraño, E; Janssen, H; Dersch, R; Ott, O; Sánchez, A Martín; Montero, M P Rubio; Loidl, M; Coron, N; de Marcillac, P; Semkow, T M

    2010-01-01

    Sources of enriched (240)Pu were prepared by vacuum evaporation on quartz substrates. High-resolution alpha-particle spectrometry of (240)Pu was performed with high statistical accuracy using silicon detectors and with low statistical accuracy using a bolometer. The alpha-particle emission probabilities of six transitions were derived from the spectra and compared with literature values. Additionally, some alpha-particle emission probabilities were derived from gamma-ray intensity measurements with a high-purity germanium detector. The alpha-particle emission probabilities of the three main transitions at 5168.1, 5123.6 and 5021.2 keV were derived from seven aggregate spectra analysed with five different fit functions and the results were compatible with evaluated data. Two additional weak peaks at 4863.5 and 4492.0 keV were fitted separately, using the exponential of a polynomial function to represent the underlying tailing of the larger peaks. The peak at 4655 keV could not be detected by alpha-particle spectrometry, while gamma-ray spectrometry confirms that its intensity is much lower than expected from literature. PMID:20106670

  4. 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.

  5. 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.

  6. 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.

  7. 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. PMID:17935286

  8. Alpha Particles Induce Apoptosis through the Sphingomyelin Pathway

    PubMed Central

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

    2011-01-01

    The sphingomyelin pathway involves the enzymatic cleavage of sphingomyelin to produce ceramide, a second messenger that serves as a key mediator in the rapid apoptotic response to various cell stressors. Low-linear energy transfer (LET) γ radiation can initiate this pathway, independent of DNA damage, via the cell membrane. Whether short-ranged, high-LET a particles, which are of interest as potent environmental carcinogens, radiotherapies and potential components of dirty bombs, can act through this mechanism to signal apoptosis is unknown. Here we show that irradiation of Jurkat cells with a 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 a 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 a particles can activate the sphingomyelin pathway to induce apoptosis. PMID:21631289

  9. 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. PMID:21631289

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

    PubMed

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

    2007-03-01

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

  11. 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.

  12. Theory of energetic/alpha particle effects on magnetohydrodynamic modes in tokamaks

    SciTech Connect

    Chen, L.; White, R.B.; Rewoldt, G.; Colestock, P.; Rutherford, P.H.; Chen, Y.P.; Ke, F.J.; Tsai, S.T.; Bussac, M.N.

    1989-01-01

    The presence of energetic particles is shown to qualitatively modify the stability properties of ideal as well as resistive magnetohydrodynamic (MHD) modes in tokamaks. Specifically, we demonstrate that, consistent with highpower ICRF heating experiments in JET, high energy trapped particles can effectively stabilize the sawtooth mode, providing a possible route to stable high current tokamak operation. An alternative stabilization scheme employing barely circulating energetic particles is also proposed. Finally, we present analytical and numerical studies on the excitations of high-n MHD modes via transit resonances with circulating alpha particles. 14 refs., 3 figs.

  13. Gene expression profile of human lymphocytes exposed to (211)At alpha particles.

    PubMed

    Turtoi, A; Brown, I; Schläger, M; Schneeweiss, F H A

    2010-08-01

    In this study, the Whole Human Genome 44K DNA microarray assay was used for the first time to obtain gene expression profiles in human peripheral blood lymphocytes 2 h after exposure (in suspension) to 6.78 MeV mean energy alpha particles from extracellular (211)At. Lymphocytes were exposed to fluences of 0.3-9.6 x 10(6) alpha particles/cm(2) [corresponding to mean absorbed alpha-particle doses (D(alpha)) of 0.05-1.60 Gy] over 30 min. Significantly modulated expression was identified in 338 early-response genes. Up-regulated expression was evident in 183 early-response genes, while the remaining 155 were down-regulated. Over half of the up-regulated genes and 40% of the down-regulated genes had a known biological process related primarily to cell growth and maintenance and cell communication. Genes associated with cell death were found only in the up-regulated genes and those with development only in the down-regulated genes. Eight selected early-response genes that displayed a sustained up- or down-regulation (CD36, HSPA2, MS4A6A, NFIL3, IL1F9, IRX5, RASL11B and SULT1B1) were further validated in alpha-particle-irradiated lymphocytes of two human individuals using the TaqMan(R) RT-qPCR technique. The results confirmed the observed microarray gene expression patterns. The expression modulation profiles of IL1F9, IRX5, RASL11B and SULT1B1 genes demonstrated similar trends in the two individuals studied. However, no significant linear correlation between increasing relative gene expression and the alpha-particle dose was evident. The results suggest the possibility that a panel of genes that react to alpha-particle radiation does exist and that they merit further study in a greater number of individuals to determine their possible value regarding alpha-particle biodosimetry. PMID:20681779

  14. 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.

  15. 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.

  16. Cryogenic Microcalorimeter System for Ultra-High Resolution Alpha-Particle Spectrometry

    NASA Astrophysics Data System (ADS)

    Croce, M. P.; Bacrania, M. K.; Hoover, A. S.; Rabin, M. W.; Hoteling, N. J.; LaMont, S. P.; Plionis, A. A.; Dry, D. E.; Ullom, J. N.; Bennett, D. A.; Horansky, R. D.; Kotsubo, V.; Cantor, R.

    2009-12-01

    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 ˜15-μK 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-particle spectrometer, and will show recent results.

  17. 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.

  18. Distributions of Alpha Particles Escaping to the Wall because of Sawtooth Oscillations in TFTR

    SciTech Connect

    Kolesnichenko, Ya.I.; Lutsenko, V.V.; White, R.B.; Yakovenko, Yu.V., Zweben, S.J.

    1998-11-01

    It has been observed experimentally in deuterium-tritium shots of the Tokamak Fusion Test Reactor (TFTR) that crashes of sawtooth oscillations may result in very inhomogeneous flux of alpha particles to the wall. Namely, measurements with four detectors installed at the wall at 20°, 45°, 60°, and 90° below the midplane of the torus have shown that the alpha flux to the wall is strongly peaked at the 20° and 90° detectors and on the noise level at the 45° detector. To explain this phenomenon, both theoretical analysis and numerical simulation have been carried out. It is concluded that the "crash-induced prompt loss," i.e., the orbital loss of marginally trapped particles arising because of the crash-induced orbit transformation of circulating particles, is responsible for the flux to the 90° and 60° detectors, whereas the crash-induced stochastic diffusion of moderately trapped particles explains the large signal at the 20° detector. The calculated poloidal distributions of the integral alpha flux are in reasonable agreement with experimental data. In addition to the integral flux, the flux of particles with given energy was calculated. The energy spectrum of the escaping particles has also been calculated, which can be used for diagnostics of the crash type.

  19. 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.

  20. Alpha Particle Effects as a Test Domain for PAP, a Plasma Apprentice Program

    NASA Astrophysics Data System (ADS)

    Mynick, Harry E.

    1987-01-01

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

  1. 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.

  2. 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.

  3. 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…

  4. 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)%. PMID:15763472

  5. Alpha-particle capture reactions in inverse kinematics relevant to p-process nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Ujić, P.; Lagoyannis, A.; Mertzimekis, T. J.; de Oliveira Santos, F.; Harissopulos, S.; Demetriou, P.; Perrot, L.; Stodel, Ch.; Saint-Laurent, M.-G.; Kamalou, O.; Lefebvre-Schuhl, A.; Spyrou, A.; Amthor, M. A.; Grevy, S.; Caceres, L.; Koivisto, H.; Laitinen, M.; Uusitalo, J.; Julin, R.

    2011-10-01

    The first feasibility study of an α-particle capture reaction in inverse kinematics at energies relevant to the p process was performed at the Wien Filter of the LISE spectrometer at GANIL. Hereby, the 4He(78Kr,γ)82Sr reaction was investigated using as target an 4He-implanted thin Al foil. The analysis of the data has shown that the determination of (α,γ) reaction cross sections at rather low energies around 2 MeV/u in inverse kinematics is indeed feasible regarding the high rejection rate of the primary beam, which in the present work was better than a factor of 109. However, the expected position of the recoils of interest was completely masked by particles of currently unknown origin that could hardly be attributed to scattering of the primary beam. The most probable explanation for the origin of these "pollutants" could be microscopic dust particles of 10 μm diameter and less, that are extremely difficult to avoid in standard experimental conditions. Hence, the use of a gas-jet target instead of a solid one is compulsory.

  6. 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.

  7. 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. PMID:24769180

  8. Neoclassical simulations of fusion alpha particles in pellet charge exchange experiments on the Tokamak Fusion Test Reactor

    SciTech Connect

    Redi, M.H.; Batha, S.H.; Budny, R.V.; Darrow, D.S.; Levinton, F.M.; McCune, D.C.; Medley, S.S.; Petrov, M.P.; von Goeler, S.; White, R.B.; Zarnstorff, M.C.; Zweben, S.J.; TFTR Team

    1999-07-01

    Neoclassical simulations of alpha particle density profiles in high fusion power plasmas on the Tokamak Fusion Test Reactor [Phys. Plasmas {bold 5}, 1577 (1998)] are found to be in good agreement with measurements of the alpha distribution function made with a sensitive active neutral particle diagnostic. The calculations are carried out in Hamiltonian magnetic coordinates with a fast, particle-following Monte Carlo code which includes the neoclassical transport processes, a recent first-principles model for stochastic ripple loss and collisional effects. New calculations show that monotonic shear alpha particles are virtually unaffected by toroidal field ripple. The calculations show that in reversed shear the confinement domain is not empty for trapped alphas at birth and allow an estimate of the actual alpha particle densities measured with the pellet charge exchange diagnostic. {copyright} {ital 1999 American Institute of Physics.}

  9. 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.

  10. Cavity cooling below the recoil limit.

    PubMed

    Wolke, Matthias; Klinner, Julian; Keßler, Hans; Hemmerich, Andreas

    2012-07-01

    Conventional laser cooling relies on repeated electronic excitations by near-resonant light, which constrains its area of application to a selected number of atomic species prepared at moderate particle densities. Optical cavities with sufficiently large Purcell factors allow for laser cooling schemes, avoiding these limitations. Here, we report on an atom-cavity system, combining a Purcell factor above 40 with a cavity bandwidth below the recoil frequency associated with the kinetic energy transfer in a single photon scattering event. This lets us access a yet-unexplored regime of atom-cavity interactions, in which the atomic motion can be manipulated by targeted dissipation with sub-recoil resolution. We demonstrate cavity-induced heating of a Bose-Einstein condensate and subsequent cooling at particle densities and temperatures incompatible with conventional laser cooling. PMID:22767925

  11. 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.

  12. 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.

  13. 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

  14. Evidence for alpha-particle chain configurations in {sup 24}Mg

    SciTech Connect

    Wuosmaa, A.H.; Back, B.B.; Betts, R.R.; Ferre, M.; Gehring, J.; Glagola, P.G.; Happ, Th.; Henderson, D.J.; Wilt, P.; Bearden, I.G.

    1992-09-01

    Many theoretical models have been employed to described the structure of the nucleus {sup 24}Mg. Among these are the Cranked Shell model (CSM), the Cranked Cluster Model (CCM), and calculations have also been performed using the Hartree-Fock formalism. One very striking prediction of these calculations is that in this nucleus there exist very unusual configurations, with structures reminiscent of linear chains of alpha particles. In the CSM, for instance, such a configuration is identified with a pronounced minimum in the potential energy energy at very large prolate deformation. In the CCM, several very different alpha-particle duster configurations are identified, many having rather large deformations. These cluster configurations can be associated with the different potential-energy minima obtained in the CSM results. In the case of the CCM, a 6{alpha} chain-like configuration is predicted to occur at excitation energies between 40 and 50 MeV, with predicted rotational spacing given by {Dirac_h}{sup 2}/2I=22 keV. At this excitation energy, such a chain configuration would lie well above the threshold for the decay of {sup 24}Mg into 6 alpha particles, and its identification poses a difficult experimental challenge. This report discusses this challenge.

  15. Evidence for alpha-particle chain configurations in sup 24 Mg

    SciTech Connect

    Wuosmaa, A.H.; Back, B.B.; Betts, R.R.; Ferre, M.; Gehring, J.; Glagola, P.G.; Happ, Th.; Henderson, D.J.; Wilt, P. ); Bearden, I.G. . Dept. of Physics)

    1992-01-01

    Many theoretical models have been employed to described the structure of the nucleus {sup 24}Mg. Among these are the Cranked Shell model (CSM), the Cranked Cluster Model (CCM), and calculations have also been performed using the Hartree-Fock formalism. One very striking prediction of these calculations is that in this nucleus there exist very unusual configurations, with structures reminiscent of linear chains of alpha particles. In the CSM, for instance, such a configuration is identified with a pronounced minimum in the potential energy energy at very large prolate deformation. In the CCM, several very different alpha-particle duster configurations are identified, many having rather large deformations. These cluster configurations can be associated with the different potential-energy minima obtained in the CSM results. In the case of the CCM, a 6{alpha} chain-like configuration is predicted to occur at excitation energies between 40 and 50 MeV, with predicted rotational spacing given by {Dirac h}{sup 2}/2I=22 keV. At this excitation energy, such a chain configuration would lie well above the threshold for the decay of {sup 24}Mg into 6 alpha particles, and its identification poses a difficult experimental challenge. This report discusses this challenge.

  16. 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.

  17. 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.

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

    PubMed

    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

  19. Neoclassical Simulations of Fusion Alpha Particles in Pellet Charge Exchange Experiments on the Tokamak Fusion Test Reactor

    SciTech Connect

    Batha, S.H.; Budny, R.V.; Darrow, D.S.; Levinton, F.M.; Redi, M.H.; et al

    1999-02-01

    Neoclassical simulations of alpha particle density profiles in high fusion power plasmas on the Tokamak Fusion Test Reactor (TFTR) [Phys. Plasmas 5 (1998) 1577] are found to be in good agreement with measurements of the alpha distribution function made with a sensitive active neutral particle diagnostic. The calculations are carried out in Hamiltonian magnetic coordinates with a fast, particle-following Monte Carlo code which includes the neoclassical transport processes, a recent first-principles model for stochastic ripple loss and collisional effects. New global loss and confinement domain calculations allow an estimate of the actual alpha particle densities measured with the pellet charge exchange diagnostic.

  20. 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.}

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

    NASA Astrophysics Data System (ADS)

    Watchman, Christopher J.

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

  2. 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.

  3. 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.

  4. Neutron production in the lunar subsurface from alpha particles in galactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Ota, Shuya; Kobayashi, Shingo; Sihver, Lembit; Yamashita, Naoyuki; Hasebe, Nobuyuki

    2011-01-01

    The neutron production from alpha particles in galactic cosmic rays (GCR) in the lunar subsurface has not been estimated with reliable precision despite its importance for lunar nuclear spectroscopy and space dosimetry. Here, we report our estimation of neutron production from GCR nuclei (protons and alpha particles) with the Particle and Heavy Ion Transport code System (PHITS), which includes several heavy ion interaction models. PHITS simulations of the equilibrium neutron density profiles in the lunar subsurface are compared with experimental data obtained in the Apollo 17 Lunar Neutron Probe Experiment. Our calculations successfully reproduced the data within an experimental error of 15%. Our estimation of neutron production from GCR nuclei, estimated by scaling that from protons by a factor of 1.27, is in good agreement within an error of 1% with the calculations using two different alpha particle interaction models in PHITS during a period of average activity of the solar cycle. However, we show that the factor depends on the incident GCR spectrum model used in the simulation. Therefore, we conclude that the use of heavy ion interaction models is important for estimating neutron production in the lunar subsurface.

  5. 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.

  6. Interpreting Recoil for Undergraduate Students

    ERIC Educational Resources Information Center

    Elsayed, Tarek A.

    2012-01-01

    The phenomenon of recoil is usually explained to students in the context of Newton's third law. Typically, when a projectile is fired, the recoil of the launch mechanism is interpreted as a reaction to the ejection of the smaller projectile. The same phenomenon is also interpreted in the context of the conservation of linear momentum, which is…

  7. Sequential determination of 210Po and uranium radioisotopes in drinking water by alpha-particle spectrometry.

    PubMed

    Benedik, L; Vasile, M; Spasova, Y; Wätjen, U

    2009-05-01

    Procedures for the sequential determination of low level (210)Po and uranium radioisotopes in drinking water by alpha-particle spectrometry are presented. After addition of (208)Po and (232)U tracers, the radionuclides were preconcentrated from water samples by co-precipitation on Fe(OH)(3) or MnO(2) at pH 9 using ammonia solution. The (210)Po source was prepared by spontaneous deposition onto a copper disc either before or after uranium separation. The uranium source for alpha-particle counting was prepared by micro co-precipitation with CeF(3). The procedures were tested on mineral water and the results obtained are compared. PMID:19231220

  8. 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. PMID:17921029

  9. 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.

  10. 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. PMID:9108052

  11. 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.

  12. 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.

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

    SciTech Connect

    Zaider, M.

    1992-01-01

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

  14. Accuracy testing using thick source alpha-particle spectroscopy for the U and Th series estimations.

    PubMed

    Michael, C T; Zacharias, N; Hein, A

    2010-01-01

    The new technique for the calculation of U and Th based on the alpha particle spectrum taken from a thick sample by using a silicon detector (PIPS) is tested and some technical problems are encountered and also some notifications for better accuracy are addressed. This technique which is mainly developed to be used for dose rate determination in TL, OSL and ESR dating applications, gives also the possibility for detecting and estimating possible disequilibrium in U and Th series. PMID:19900816

  15. 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.

  16. 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

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

    PubMed

    Azooz, Aassim A; Al-Jubbori, Mushtaq A

    2016-09-01

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

  19. Destabilization of the shear Alfven mode by alpha particles and other high energy ions

    NASA Astrophysics Data System (ADS)

    Belikov, V. S.; Kolesnichenko, Ya. I.; Silivra, O. A.

    1992-08-01

    Toroidal Alfven eigenmode (TAE) and elliptical Alfven eigenmode (EAE) instabilities in plasmas with high energy ions are considered in the context of local theory. The instability growth rate is found for cases when waves are excited by alpha particles or by ions produced as a result of neutral injection or RF heating. Electron and ion Landau damping due to the toroidal sideband wave-particle interaction is also calculated. The electron damping rate is shown to be much lower than the generally accepted value. The TAE instability observed in the experiment with neutral beam injection on TFTR is analysed and the principal experimental features of TAE instability are explained

  20. 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)

  1. 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.

  2. Electrostatic ion-acoustic-like instabilities in the solar wind with a backstreaming alpha particle beam

    SciTech Connect

    Gomberoff, L.; Gomberoff, K.; Deutsch, A.

    2010-06-15

    Nonlinear electrostatic instabilities have been shown to occur frequently and under very different conditions in plasma with two ion beams such as the fast solar wind. These instabilities can be triggered when the phase velocity of electrostatic ion-acoustic waves propagating forward and backward relative to the interplanetary magnetic field overlaps due to the presence of a finite amplitude of circularly polarized wave. The instabilities can be triggered by waves supported by the same ion component, or by waves supported by different ion components. By assuming a beam of alpha particles moving backward relative to the external magnetic field, as observed in some events in the fast solar wind, it is shown that a very small negative drift velocity of the alpha particle beam relative to the core plasma--a few percent of the local Alfven velocity--can trigger a very rich variety of nonlinear electrostatic acousticlike instabilities. Their growth rates can be rather large and they persist for larger negative alpha particles drift velocities and temperatures.

  3. Coinhibition of viral interferon induction by Benzo(. alpha. )pyrene in association with occupation-related particles

    SciTech Connect

    Hahon, N. West Virginia Univ., Morgantown ); Booth, J.A. ); Flowers, L. )

    1990-06-01

    Benzo({alpha})pyrene (B(a)P) in combination with coal, asbestos, silicate, or metal particles was studied for its inhibitory effects on interferon-{alpha}/{beta} induction by influenza virus in rhesus monkey kidney (LLC-MK{sub 2}) cell monolayers. B(a)P per se had no adverse effect on the induction process. However, when cell cultures were pretreated with B(a)P that was bioactivated by rat liver S9 homogenate, from 52 to 65% inhibition of interferon induction occurred. Significantly greater depression (coinhibition) of viral interferon induction (>83%) resulted when bioactivated B(a)P was incorporated with coal particles representative of coal rank (anthracite, bituminous, lignite, peat). Coinhibition affected by bioactivated B(a)P was coal rank-independent but any interferon inhibitory activity affected by coal particles per se was coal rank-independent. When metals (aluminum, aluminum oxide, ferric oxide, nickel, or chromium) or asbestos fibers were individually mixed with bioactivated B(a)P, coinhibition of cellular interferon synthesis also resulted which was significantly greater than that manifested by bioactivated B(a)P or particles per se. Coinhibition of interferon induction by silicates and the bioactivated hydrocarbon was not in evidence although some silicates alone partially inhibited the induction process. Viral interferon induction was inhibited in a dose-response manner by B(a)P ({+-}S9) in combination with selected particles.

  4. 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.

  5. Kinetic theory of alpha particles production in a dense and strongly magnetized plasma

    NASA Astrophysics Data System (ADS)

    Cereceda, Carlo; Deutsch, Claude; De Peretti, Michel; Sabatier, Michel; Basko, Mikhail M.; Kemp, Andreas; Meyer-ter-Vehn, Jurgend

    2000-11-01

    In connection with fundamental issues relevant to magnetized target fusion, the distribution function of thermonuclear alpha particles produced in situ in a dense, hot, and strongly magnetized hydrogenic plasma considered fully ionized in a cylindrical geometry is investigated. The latter is assumed in local thermodynamic equilibrium with Maxwellian charged particles. The approach is based on the Fokker-Planck equation with isotropic source S and loss s terms, which may be taken arbitrarily under the proviso that they remain compatible with a steady state. A novel and general expression is then proposed for the isotropic and stationary distribution f(v). Its time-dependent extension is worked out numerically. The solutions are valid for any particle velocity v and plasma temperature T. Higher order magnetic and collisional corrections are also obtained for electron gyroradius larger than Debye length. f(v) moments provide particle diffusion coefficient and heat thermal conductivity. Their scaling on collision time departs from Braginski's.

  6. Retention studies of recoiling daughter nuclides of 225Ac in polymer vesicles.

    PubMed

    Wang, G; de Kruijff, R M; Rol, A; Thijssen, L; Mendes, E; Morgenstern, A; Bruchertseifer, F; Stuart, M C A; Wolterbeek, H T; Denkova, A G

    2014-02-01

    Alpha radionuclide therapy is steadily gaining importance and a large number of pre-clinical and clinical studies have been carried out. However, due to the recoil effects the daughter recoil atoms, most of which are alpha emitters as well, receive energies that are much higher than the energies of chemical bonds resulting in decoupling of the radionuclide from common targeting agents. Here, we demonstrate that polymer vesicles (i.e. polymersomes) can retain recoiling daughter nuclei based on an experimental study examining the retention of (221)Fr and (213)Bi when encapsulating (225)Ac. PMID:24374072

  7. Radiotoxicity of gadolinium-148 and radium-223 in mouse testes: relative biological effectiveness of alpha-particle emitters in vivo.

    PubMed

    Howell, R W; Goddu, S M; Narra, V R; Fisher, D R; Schenter, R E; Rao, D V

    1997-03-01

    The biological effects of radionuclides that emit alpha particles are of considerable interest in view of their potential for therapy and their presence in the environment. The present work is a continuation of our ongoing effort to study the radiotoxicity of alpha-particle emitters in vivo using the survival of murine testicular sperm heads as the biological end point. Specifically, the relative biological effectiveness (RBE) of very low-energy alpha particles (3.2 MeV) emitted by 148Gd is investigated and determined to be 7.4 +/- 2.4 when compared to the effects of acute external 120 kVp X rays. This datum, in conjunction with our earlier results for 210Po and 212Pb in equilibrium with its daughters, is used to revise and extend the range of validity of our previous RBE-energy relationship for alpha particles emitted by tissue-incorporated radionuclides. The new empirical relationship is given by RBE alpha = 9.14 - 0.510 E alpha where 3 < E alpha < 9 MeV. The validity of this empirical relationship is tested by determining the RBE of the prolific alpha-particle emitter 223Ra (in equilibrium with its daughters) experimentally in the same biological model and comparing the value obtained experimentally with the predicted value. The resulting RBE values are 5.4 +/- 0.9 and 5.6, respectively. This close agreement strongly supports the adequacy of the empirical RBE-E alpha relationship to predict the biological effects of alpha-particle emitters in vivo. PMID:9052681

  8. 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.

  9. 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.

  10. Particle-in-cell simulations of the magnetoacoustic cyclotron instability of fusion-born alpha-particles in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Cook, J. W. S.; Dendy, R. O.; Chapman, S. C.

    2013-06-01

    Ion cyclotron emission (ICE) is the only collective radiative instability, driven by confined fusion-born alpha-particles, observed from deuterium-tritium (DT) plasmas in both JET and TFTR. Using first principles particle-in-cell simulations of the magnetoacoustic cyclotron instability (MCI), we elucidate some of the fully kinetic nonlinear processes that may underlie observations of ICE from fusion products in these large tokamaks. We find that the MCI is intrinsically self-limiting on very fast timescales, which may help explain the observed correlation between linear theory and observed ICE intensity. The simulations elaborate the nature of the excited electric and magnetic fluctuations, from first principles, confirming the dominant role of fast Alfvénic and electrostatic components which is assumed ab initio in analytical treatments.

  11. An Experiment to Measure Range, Range Straggling, Stopping Power, and Energy Straggling of Alpha Particles in Air

    ERIC Educational Resources Information Center

    Ouseph, P. J.; Mostovych, Andrew

    1978-01-01

    Experiments to measure range, range straggling, stopping power, and energy straggling of alpha particles are discussed in this article. Commercially available equipment with simple modifications is used for these measurements. (Author/GA)

  12. 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. PMID:11394266

  13. 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

  14. Sizing alpha emitting particles of aged plutonium on personal air sampler filters using CR-39 autoradiography.

    PubMed

    Richardson, R B; Hegyi, G; Starling, S C

    2003-01-01

    Methods have been developed to assess the size distribution of alpha emitting particles of reactor fuel of known composition captured on air sampler filters. The sizes of uranium oxide and plutonium oxide particles were determined using a system based on CR-39 solid-state nuclear track detectors. The CR-39 plastic was exposed to the deposited particles across a 400 microm airgap. The exposed CR-39 was chemically etched to reveal clusters of tracks radially dispersed from central points. The number and location of the tracks were determined using an optical microscope with an XY motorised table and image analysis software. The sample mounting arrangement allowed individual particles to be simultaneously viewed with their respective track cluster. The predicted diameters correlated with the actual particle diameters, as measured using the optical microscope. The efficacy of the technique was demonstrated with particles of natural uranium oxide (natUO2) of known size, ranging from 4 to 150 microm in diameter. Two personal air sampler (PAS) filters contaminated with actinide particles were placed against CR-39 and estimated to have size distributions of 0.8 and 1.0 microm activity median aerodynamic diameter (AMAD). PMID:14526944

  15. 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.

  16. Orbit-averaged drift kinetic equation for the study of alpha-particle transport in tokamaks

    SciTech Connect

    Sager, G.T.; Miley, G.H. . Fusion Studies Lab.); Burrell, K.H. )

    1990-11-01

    Neoclassical transport of minority suprathermal alpha particles is investigated. This paper departs from previous investigations in that (a) the banana-width ordering parameter {rho}{sub {theta}}/L is not formally restricted to be a small parameter and (b) a linearized collision operator that retains the effects of pitch-angle scattering, electron and ion drag, and speed diffusion is used. A step model approximation for the large-aspect-ratio, circular-cross-section tokamak magnetic field is adopted to simplify the orbit-averaging procedure. Assuming that the suprathermal alphas are in the banana regime, an asymptotic expansion in {tau}{sub B}/{tau}{sub S} {much lt} l is carried out.

  17. Further insight into gravitational recoil

    SciTech Connect

    Lousto, Carlos O.; Zlochower, Yosef

    2008-02-15

    We test the accuracy of our recently proposed empirical formula to model the recoil velocity imparted to the merger remnant of spinning, unequal-mass black-hole binaries. We study three families of black-hole binary configurations, all with mass ratio q=3/8 (to nearly maximize the unequal-mass contribution to the kick) and spins aligned (or counter-aligned) with the orbital angular momentum, two with spin configurations chosen to minimize the spin-induced tangential and radial accelerations of the trajectories, respectively, and a third family where the trajectories are significantly altered by spin-orbit coupling. We find good agreement between the measured and predicted recoil velocities for the first two families, and reasonable agreement for the third. We also reexamine our original generic binary configuration that led to the discovery of extremely large spin-driven recoil velocities and inspired our empirical formula, and find rough agreement between the predicted and measured recoil speeds.

  18. 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.

  19. Beams of protons and alpha particles greater than approximately 30 keV/charge from the earth's bow shock

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    Two beamlike particle events (30 keV/charge to 160 keV/charge) upstream of the earth's bow shock have been investigated with the Max-Planck-Institut/University of Maryland ultralow energy and charge analyzer on ISEE 1. These beams consist of protons as well as of alpha particles, and the spectra are generally steep and are decreasing with increasing energy. During one event the spectra of both protons and alpha particles have a maximum at approximately 65 keV/charge. During these events, the interplanetary magnetic field through the satellite position was almost tangent to the bow shock, and application of the theory of acceleration predicts acceleration of a solar wind particle up to 60 keV/nucleon in a single reflection. The observation of reflected protons as well as alpha particles has implications for the physical reflection process usually not discussed in acceleration theories.

  20. How to produce high specific activity tin-117m using alpha particle beam.

    PubMed

    Duchemin, C; Essayan, M; Guertin, A; Haddad, F; Michel, N; Métivier, V

    2016-09-01

    Tin-117m is an interesting radionuclide for both diagnosis and therapy, thanks to the gamma-ray and electron emissions, respectively, resulting from its decay to tin-117g. The high specific activity of tin-117m is required in many medical applications, and it can be obtained using a high energy alpha particle beam and a cadmium target. The experiments performed at the ARRONAX cyclotron (Nantes, France) using an alpha particle beam delivered at 67.4MeV provide a measurement of the excitation function of the Cd-nat(α,x)Sn-117m reaction and the produced contaminants. The Cd-116(α,3n)Sn-117m production cross section has been deduced from these experimental results using natural cadmium. Both production yield and specific activity as a function of the projectile energy have been calculated. These informations help to optimize the irradiation conditions to produce tin-117m with the required specific activity using α particles with a cadmium target. PMID:27344526

  1. 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.

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

    NASA Technical Reports Server (NTRS)

    Yamauchi, Y.; Suess, S. T.; Steinberg, J. T.; Sakurai, T.

    2003-01-01

    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. Secondary ion mass spectrometry combined with alpha track detection for isotope abundance ratio analysis of individual uranium-bearing particles.

    PubMed

    Esaka, Fumitaka; Magara, Masaaki

    2014-03-01

    Secondary ion mass spectrometry (SIMS) was used in combination with alpha track detection for the efficient analysis of uranium-bearing particles with higher (235)U abundances in environmental samples. A polycarbonate film containing particles was prepared and placed in contact with a CR-39 plastic detector. After exposure for 28 days, the detector was etched in a NaOH solution and each uranium-bearing particle was identified through observation of the alpha tracks recorded in the detector. A portion of the film containing each uranium-bearing particle was cut out and put onto a glassy carbon planchet. The films on the planchet were decomposed through plasma ashing for subsequent uranium abundance ratio analysis with SIMS. The alpha track-SIMS analysis of 10 uranium-bearing particles in a sample taken from a nuclear facility enabled n((235)U)/n((238)U) abundance ratios in the range 0.0072-0.25 to be detected, which were significantly higher than those obtained by SIMS without alpha track detection. The duration of the whole analytical process for analysis of 10 particles was about 32 days. The detection efficiency was calculated to be 27.1±6.5%, based on the analysis of the particles in uranium reference materials. The detection limits, defined as the diameter of the particle which produces alpha tracks more than one for a 28-days exposure, were estimated to be 0.8, 0.9, 1.1, 2.1 and 3.0 μm for the particles having the same uranium abundance ratios with NBL CRM U850, U500, U350, U050 and U010 reference materials, respectively. The use of alpha track detection for subsequent SIMS analysis is an inexpensive and an efficient way to measure uranium-bearing particles with higher (235)U abundances. PMID:24468381

  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. 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).

  7. 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

    2004-08-01

    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. PMID:15297665

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

    SciTech Connect

    Wang, S. |; Zweben, S.J.

    1996-05-01

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

  9. Measurement of the spectra of doubly charged particles emitted in bombardment of lead nuclei by. cap alpha. particles with energy 3. 6 GeV/nucleon

    SciTech Connect

    Ad'yasevich, B.P.; Antonenko, V.G.; Vinogradov, A.A.; Grigor'yan, Y.I.; Dukhanov, V.I.; Ippolitov, M.S.; Karadzhev, K.V.; Lebedev, A.L.; Man'ko, V.I.; Nikolaev, S.A.; Polunin, Y.P.; Tsvetkov, A.A.

    1983-12-01

    We have measured the spectra of double charged particles emitted in interaction of 3.6 GeV/nucleon ..cap alpha.. particles with lead nuclei. Spectra were measured at emission angles from 10 to 95/sup 0/ in the range of secondary-particle velocities 0.37<..beta..<0.55. Angular distributions were obtained, the total cross section for emission of doubly charged particles was evaluated, and the ratios of the contributions of doubly and singly charged particles were determined. The rapidity distributions of the invariant cross sections for production of doubly charged particles reveal maxima at a rapidity yroughly-equal0.15--0.20.

  10. The fine structure constant alpha: relevant for a model of a self-propelling photon and for particle masses

    NASA Astrophysics Data System (ADS)

    Greulich, Karl O.

    2015-09-01

    A model for a self propelling (i.e. massless) photon1 is based on oscillations of a pair of charges amounting to elementary charge divided by SQRT alpha, where alpha is the fine structure (Sommerfeld) constant. When one assumes a similar model for particles that do have rest mas (i.e. which are non- self propelling), alpha plays also a role in the rest masses of elementary particles. Indeed all fundamental elementary particle masses can be described by the alpha / beta rule2 --> m(particle) = alpha-n * betam* 27.2 eV /c2 where beta is the proton to electron mass ratio 183612 and n= 0….14, m= -1,0 or Thus, photons and particle masses are intimately related to the fine structure constant. If the latter would not have been strictly constant throughout all times, this would have had consequences for the nature of light and for all masses including those of elementary particles.

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

    SciTech Connect

    Hodgkins, P.S.; O`Neill, P.; Stevens, D.; Fairman, M.P.

    1996-12-01

    The rejoining of single-strand breaks induced by {alpha}-particle and {gamma} irradiation in plasmid DNA under two scavenging conditions has been compared. At the two scavenger conditions has been compared. At the two scavenger capacities used of 1.5 {times} 10{sup 7} and 3 {times} 10{sup 8}s{sup {minus}1} using Tris-HCl as the scavenger, the ratio of single- to double-strand breaks for {alpha} particles is fivefold less than the corresponding ratios for {gamma} irradiation. The repair of such radiation-induced single-strand breaks has been examined using a cell-free system derived from human whole-cell extracts. We show that the rejoining of single-strand breaks for both {alpha}-particle- and {gamma}-irradiated plasmid is dependent upon the scavenging capacity and that the efficiency of rejoining of {alpha}-particle-induced single-strand breaks is significantly less than that observed for {gamma}-ray-induced breaks. In addition, for DNA that had been irradiated under conditions that mimic the cellular environment with respect to the radical scavenging capacity, 50 of {alpha}-particle-induced single-strand breaks are converted to double-strand breaks, in contrast with only {approximately}12% conversion of {gamma}-ray-induced single-strand breaks, indicating that the initial damage caused by {alpha} particles is more severe. These studies provide experimental evidence for increased clustering of damage which may have important implications for the induction of cancer by low-level {alpha}-particle sources such as domestic radon. 37 refs., 5 figs., 1 tab.

  12. Relative biological effectiveness of the alpha-particle emitter (211)At for double-strand break induction in human fibroblasts.

    PubMed

    Claesson, Anna Kristina; Stenerlöw, Bo; Jacobsson, Lars; Elmroth, Kecke

    2007-03-01

    The purpose of this study was to quantify and to determine the distribution of DNA double-strand breaks (DSBs) in human cells irradiated in vitro and to evaluate the relative biological effectiveness (RBE) of the alpha-particle emitter (211)At for DSB induction. The influence of the irradiation temperature on the induction of DSBs was also investigated. Human fibroblasts were irradiated as intact cells with alpha particles from (211)At, (60)Co gamma rays and X rays. The numbers and distributions of DSBs were determined by pulsed-field gel electrophoresis with fragment analysis for separation of DNA fragments in sizes 10 kbp-5.7 Mbp. A non-random distribution was found for DSB induction after irradiation with alpha particles from (211)At, while irradiation with low-LET radiation led to more random distributions. The RBEs for DSB induction were 2.1 and 3.1 for (60)Co gamma rays and X rays as the reference radiation, respectively. In the experiments studying temperature effects, nuclear monolayers were irradiated with (211)At alpha particles or (60)Co gamma rays at 2 degrees C or 37 degrees C and intact cells were irradiated with (211)At alpha particles at the same temperatures. The dose-modifying factor (DMF(temp)) for irradiation of nuclear monolayers at 37 degrees C compared with 2 degrees C was 1.7 for (211)At alpha particles and 1.6 for (60)Co gamma rays. No temperature effect was observed for intact cells irradiated with (211)At. In conclusion, irradiation with alpha particles from (211)At induced two to three times more DSB than gamma rays and X rays. PMID:17316073

  13. A study of the scintillation light induced in liquid xenon by electrons and alpha particles

    NASA Technical Reports Server (NTRS)

    Aprile, Elena; Mukherjee, Reshmi; Suzuki, Masayo

    1990-01-01

    The time dependence and the intensity of the primary scintillation light in liquid Xe excited by Am-241 alpha particles and Bi-207 internal-conversion electrons were measured at different electric-field strengths. High-purity liquid Xe was used to fill a parallel-plate ionization chamber equipped with a CaF2 window coupled to a UV-sensitive photomultiplier tube. The effect of the specific ionization density on the scintillation light and the time correlation between the light signal and the charge signal is reported. It is demonstrated that the fast scintillation signal produced in liquid Xe by an ionizing particle provides an ideal trigger in a detector aiming at a complete three-dimensional event reconstruction with an excellent background rejection capability.

  14. 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.

  15. Code System for Analyzing Ge and Alpha-Particle Detector Spectra.

    Energy Science and Technology Software Center (ESTSC)

    1992-06-29

    Version 00 GRPANL (GRouP ANaLysis) is a suite of programs which analyzes and interprets regions of germanium and alpha-particle detector pulse-height spectra. GRPANL is the main peak-fitting program; the other programs included are used in conjunction with GRPANL. GRPANL is particularly useful for accurately deconvoluting and interpreting complex clusters of peaks in a spectrum. GRPANL fits peaks in specified regions of a gamma-ray, x-ray, or alpha-particle spectrum, calculates their energies and intensities, and optionally calculatesmore » the photon emission rates for the sample from which they were emitted. It can also identify and measure isotopes in a sample. GRPANL output can be immediately analyzed for quantitative isotopic assays or stored in an intermediate data file. The other programs are EDIGRP, LIBRY, and GEVAL. EDISRP (EDIt GRouP) creates and edits an analysis control file that contains input parameters and analysis options for spectral regions analyzed by GRPANL; users can repeat or modify an analysis without retyping input. LIBRY (LIBRarY) assembles and cross references selected nuclear decay scheme data and stores it in decay scheme data files for use by GRPANL and GEVAL. GEVAL (Gamma ray EVALuation) uses these data files along with GRPANL intermediate results to identify isotopes, calculate their abundance in a sample, and print the corresponding disintegration rates and abundances at counting and zero times.« less

  16. 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.

  17. 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. PMID:27161512

  18. 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.

  19. 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.

  20. Detailed 8-transistor SRAM cell analysis for improved alpha particle radiation hardening in nanometer technologies

    NASA Astrophysics Data System (ADS)

    Bota, Sebastià A.; Torrens, Gabriel; Verd, Jaume; Segura, Jaume

    2015-09-01

    Eight-transistor (8T) cells were introduced to improve variability tolerance, cell stability and low-voltage operation in high-speed SRAM caches by decoupling the read and write design requirements. Altogether, 8T-SRAM can be designed without significant area penalty over 6T-SRAM. Ionizing radiation effects are nowadays a major concern for reliability and dependability of emerging electronic SRAM devices, even for sea-level applications. In this paper we demonstrate from experimental results that the 8T-SRAM also exhibits an enhanced overall intrinsic tolerance to alpha particle radiation even though its critical charge values are smaller than conventional 6T cells. We have experimentally found that the soft error rate measured in accelerated experiments with alpha particles in SRAM devices implemented in a 65 nm CMOS is 56% better for 8T cells with respect to standard 6T-cells. Even more, we show that this value can be increased up to a 200% through transistor sizing optimization.

  1. 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.

  2. Protons and alpha particles in the expanding solar wind: Hybrid simulations

    NASA Astrophysics Data System (ADS)

    Hellinger, Petr; Trávníček, Pavel M.

    2013-09-01

    We present results of a two‒dimensional hybrid expanding box simulation of a plasma system with three ion populations, beam and core protons, and alpha particles (and fluid electrons), drifting with respect to each other. The expansion with a strictly radial magnetic field leads to a decrease of the ion perpendicular to parallel temperature ratios as well as to an increase of the ratio between the ion relative velocities and the local Alfvén velocity creating a free energy for many different instabilities. The system is most of the time marginally stable with respect to kinetic instabilities mainly due to the ion relative velocities; these instabilities determine the system evolution counteracting some effects of the expansion. Nonlinear evolution of these instabilities leads to large modifications of the ion velocity distribution functions. 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. On the macroscopic level, the kinetic instabilities cause large departures of the system evolution from the double adiabatic prediction and lead to perpendicular heating and parallel cooling rates which are comparable to the heating rates estimated from the Helios observations.

  3. Monte-Carlo dosimetry on a realistic cell monolayer geometry exposed to alpha particles

    NASA Astrophysics Data System (ADS)

    Barberet, Ph; Vianna, F.; Karamitros, M.; Brun, T.; Gordillo, N.; Moretto, Ph; Incerti, S.; Seznec, H.

    2012-04-01

    The energy and specific energy absorbed in the main cell compartments (nucleus and cytoplasm) in typical radiobiology experiments are usually estimated by calculations as they are not accessible for a direct measurement. In most of the work, the cell geometry is modelled using the combination of simple mathematical volumes. We propose a method based on high resolution confocal imaging and ion beam analysis (IBA) in order to import realistic cell nuclei geometries in Monte-Carlo simulations and thus take into account the variety of different geometries encountered in a typical cell population. Seventy-six cell nuclei have been imaged using confocal microscopy and their chemical composition has been measured using IBA. A cellular phantom was created from these data using the ImageJ image analysis software and imported in the Geant4 Monte-Carlo simulation toolkit. Total energy and specific energy distributions in the 76 cell nuclei have been calculated for two types of irradiation protocols: a 3 MeV alpha particle microbeam used for targeted irradiation and a 239Pu alpha source used for large angle random irradiation. Qualitative images of the energy deposited along the particle tracks have been produced and show good agreement with images of DNA double strand break signalling proteins obtained experimentally. The methodology presented in this paper provides microdosimetric quantities calculated from realistic cellular volumes. It is based on open-source oriented software that is publicly available.

  4. Thermal and suprathermal protons and alpha particles in the earth's plasma sheet

    SciTech Connect

    Ipavich, F.M.; Scholer, M.

    1983-01-01

    We have investigated thermal and suprathermal protons (from approx.13 keV to approx.1 MeV) and alpha particles (from approx.30 keV/Q to 130 keV/Q) in the quasi-stable plasma sheet near local midnight at geocentric distances of approx.12--20 R/sub E/. The data, obtained during five different plasma sheet penetrations with the Max-Planck-Institut/University of Maryland sensor system on ISEE 1, represent the first measurements of plasma sheet ion composition in this energy range. Below approx.16 keV the proton spectra can be represented by a Maxwellian distribution. Above approx.16 keV we find a suprathermal tail which cannot be represented by a single power law. In some cases the suprathermal population consists of two distinct components: a low-energy component falling off sharply at approx.100 keV and a high-energy component extending up to approx.1 MeV. The high-energy component often decays with time during expansion of the plasma sheet. Alpha particle to proton ratios average approx.3% and are observed to be constant at either equal energy per nucleon or energy per charge.

  5. 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.

  6. Monte-Carlo dosimetry on a realistic cell monolayer geometry exposed to alpha particles.

    PubMed

    Barberet, Ph; Vianna, F; Karamitros, M; Brun, T; Gordillo, N; Moretto, Ph; Incerti, S; Seznec, H

    2012-04-21

    The energy and specific energy absorbed in the main cell compartments (nucleus and cytoplasm) in typical radiobiology experiments are usually estimated by calculations as they are not accessible for a direct measurement. In most of the work, the cell geometry is modelled using the combination of simple mathematical volumes. We propose a method based on high resolution confocal imaging and ion beam analysis (IBA) in order to import realistic cell nuclei geometries in Monte-Carlo simulations and thus take into account the variety of different geometries encountered in a typical cell population. Seventy-six cell nuclei have been imaged using confocal microscopy and their chemical composition has been measured using IBA. A cellular phantom was created from these data using the ImageJ image analysis software and imported in the Geant4 Monte-Carlo simulation toolkit. Total energy and specific energy distributions in the 76 cell nuclei have been calculated for two types of irradiation protocols: a 3 MeV alpha particle microbeam used for targeted irradiation and a ²³⁹Pu alpha source used for large angle random irradiation. Qualitative images of the energy deposited along the particle tracks have been produced and show good agreement with images of DNA double strand break signalling proteins obtained experimentally. The methodology presented in this paper provides microdosimetric quantities calculated from realistic cellular volumes. It is based on open-source oriented software that is publicly available. PMID:22456322

  7. DYNAMICS OF A SPHERICAL ACCRETION SHOCK WITH NEUTRINO HEATING AND ALPHA-PARTICLE RECOMBINATION

    SciTech Connect

    Fernandez, Rodrigo; Thompson, Christopher

    2009-10-01

    We investigate the effects of neutrino heating and alpha-particle recombination on the hydrodynamics of core-collapse supernovae. Our focus is on the nonlinear dynamics of the shock wave that forms in the collapse and the assembly of positive energy material below it. To this end, we perform time-dependent hydrodynamic simulations with FLASH2.5 in spherical and axial symmetry. These generalize our previous calculations by allowing for bulk neutrino heating and for nuclear statistical equilibrium between n, p, and alpha. The heating rate is freely tunable, as is the starting radius of the shock relative to the recombination radius of alpha-particles. An explosion in spherical symmetry involves the excitation of an overstable mode, which may be viewed as the l = 0 version of the 'Standing Accretion Shock Instability'. In two-dimensional simulations, nonspherical deformations of the shock are driven by plumes of material with positive Bernoulli parameter, which are concentrated well outside the zone of strong neutrino heating. The nonspherical modes of the shock reach a large amplitude only when the heating rate is also high enough to excite convection below the shock. The critical heating rate that causes an explosion depends sensitively on the initial position of the shock relative to the recombination radius. Weaker heating is required to drive an explosion in two dimensions than in one, but the difference also depends on the size of the shock. Forcing the infalling heavy nuclei to break up into n and p below the shock only causes a slight increase in the critical heating rate, except when the shock starts out at a large radius. This shows that heating by neutrinos (or some other mechanism) must play a significant role in pushing the shock far enough out that recombination heating takes over.

  8. 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

  9. TEST PROCEDURE FOR GROSS ALPHA PARTICLE ACTIVITY IN DRINKING WATER: INTERLABORATORY COLLABORATIVE STUDY

    EPA Science Inventory

    Gross alpha activity values were calculated with four different alpha emitting radionuclide standard counting efficiencies to see which standard was best for gross alpha activity determinations. Thorium-230, a pure alpha emitter, appeared to be the best standard for gross alpha c...

  10. Scattering of 42 MeV alpha particles from copper-65

    NASA Technical Reports Server (NTRS)

    Stewart, W. M.; Seth, K. K.

    1973-01-01

    Beams of 42-MeV alpha particles were elastically and inelastically scattered from Cu-65 in an attempt to excite states which may be described in terms of an excited core model. Angular distributions were measured for 17 excited states. Seven of the excited states had angular distributions similar to a core quadrupole excitation and eight of the excited states had angular distributions similar to a core octupole excitation. The excited state at 2.858 MeV had an angular distribution which suggests that it may have results from the particle coupling to a two-phonon core state. An extended particle-core coupling calculation was performed and the predicted energy levels and reduced transition probabilities compared to the experimental data. The low lying levels are described quite well and the wavefunctions of these states explain the large spectroscopic factors measured in stripping reactions. For Cu-65 the coupling of the particle to the core is no larger weak as in the simpler model, and configuration mixing results.

  11. Differential Effects of Alpha-Particle Radiation and X-Irradiation on Genes Associated with Apoptosis

    PubMed Central

    Chauhan, Vinita; Howland, Matthew; Chen, Jeremy; Kutzner, Barbara; Wilkins, Ruth C.

    2011-01-01

    This study examined differential effects of alpha-(α-) particle radiation and X-rays on apoptosis and associated changes in gene expression. Human monocytic cells were exposed to α-particle radiation and X-rays from 0 to 1.5 Gy. Four days postexposure, cell death was measured by flow cytometry and 84 genes related to apoptosis were analyzed using real-time PCR. On average, 33% of the cells were apoptotic at 1.5 Gy of α-particle radiation. Transcript profiling showed statistical expression of 15 genes at all three doses tested. Cells exposed to X-rays were <5% apoptotic at ~1.5 Gy and induced less than a 2-fold expression in 6 apoptotic genes at the higher doses of radiation. Among these 6 genes, Fas and TNF-α were common to the α-irradiated cells. This data suggests that α-particle radiation initiates cell death by TNF-α and Fas activation and through intermediate signalling mediators that are distinct from X-irradiated cells. PMID:22091383

  12. Ionic recoil energies in the Coulomb explosion of metal clusters

    NASA Astrophysics Data System (ADS)

    Teuber, S.; Döppner, T.; Fennel, T.; Tiggesbäumker, J.; Meiwes-Broer, K. H.

    The photoionization of metal clusters in intense femtosecond laser fields has been studied. In contrast to an experiment on atoms, the interaction in this case leads to a very efficient and high charging of the particle where tens of electrons per atom are ejected from the cluster. The recoil energy distribution of the atomic fragment ions was measured which in the case of lead clusters exceeds 180 keV. Enhanced charging efficiency which we observed earlier for specific pulse conditions is not reflected in the recoil energy spectra. Both the average and the maximum energies decrease with increasing laser pulse width. This is in good agreement with molecular dynamics calculations.

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

    SciTech Connect

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

    1991-12-01

    This paper describes a methodology 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-{mu}m n-well CMOS 4k-bit test SRAM irradiated with an Am-241 alpha-particle source. A collection depth of 6.09 {mu}m 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 cm{sup 2}/mg was predicted. Heavy ion tests were then performed on the latch and an LET threshold of 41 MeV cm{sup 2}/mg was determined.

  14. 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.

  15. 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

  16. 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

  17. Bayesian analysis of nanodosimetric ionisation distributions due to alpha particles and protons.

    PubMed

    De Nardo, L; Ferretti, A; Colautti, P; Grosswendt, B

    2011-02-01

    Track-nanodosimetry has the objective to investigate the stochastic aspect of ionisation events in particle tracks, by evaluating the probability distribution of the number of ionisations produced in a nanometric target volume positioned at distance d from a particle track. Such kind of measurements makes use of electron (or ion) gas detectors with detecting efficiencies non-uniformly distributed inside the target volume. This fact makes the reconstruction of true ionisation distributions, which correspond to an ideal efficiency of 100%, non-trivial. Bayesian unfolding has been applied to ionisation distributions produced by 5.4 MeV alpha particles and 20 MeV protons in cylindrical volumes of propane of 20 nm equivalent size, positioned at different impact parameters with respect to the primary beam. It will be shown that a Bayesian analysis performed by subdividing the target volume in sub-regions of different detection efficiencies is able to provide a good reconstruction of the true nanodosimetric ionisation distributions. PMID:21112893

  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. A study of intrinsic statistical variation for low-energy nuclear recoils in liquid xenon detector for dark matter searches

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Wei, Wenzhao; Mei, Dongming; Cubed Collaboration

    2015-10-01

    Noble liquid xenon experiments, such as XENON100, LUX, XENON 1-Ton, and LZ are large dark matter experiments directly searches for weakly interacting massive particles (WIMPs). One of the most important features is to discriminate nuclear recoils from electronic recoils. Detector response is generally calibrated with different radioactive sources including 83mKr, tritiated methane, 241AmBe, 252Cf, and DD-neutrons. The electronic recoil and nuclear recoil bands have been determined by these calibrations. However, the width of nuclear recoil band needs to be fully understood. We derive a theoretical model to understand the correlation of the width of nuclear recoil band and intrinsic statistical variation. In addition, we conduct experiments to validate the theoretical model. In this paper, we present the study of intrinsic statistical variation contributing to the width of nuclear recoil band. DE-FG02-10ER46709 and the state of South Dakota.

  20. Nuclear Recoil Calibration of DarkSide-50

    NASA Astrophysics Data System (ADS)

    Edkins, Erin; DarkSide Collaboration

    2016-03-01

    DarkSide-50 dark matter experiment is a liquid argon time projection chamber (TPC) surrounded by a liquid scintillator active neutron veto, designed for the direct detection of Weakly Interacting Massive Particles (WIMPs). The success of such an experiment is dependent upon a detailed understanding of both the expected signal and backgrounds, achieved using radioactive calibration sources of known energies. Nuclear recoils provide a measurement of both the expected signal and the most dangerous background, as nuclear recoils from neutrons cannot be distinguished from a dark matter signal on an event-by-event basis in the TPC. In this talk, I will present the DS-50 calibration system, and analysis of the results of the calibration of DarkSide-50 to nuclear recoils using radioactive neutron sources. See also the DS-50 presentations by X. Xiang and G. Koh.

  1. Fission product release from nuclear fuel by recoil and knockout

    NASA Astrophysics Data System (ADS)

    Lewis, B. J.

    1987-03-01

    An analytical model has been developed to describe the fission product release from nuclear fuel arising from the surface-fission release mechanisms of recoil and knockout. Release expressions are evaluated and compared to the short-lived activity measurements from in-reactor experiments with intact operating fuel. Recoil is shown to be an important process for releasing fission products from free UO 2 surfaces into the fuel-to-sheath gap. The model is also applied to tramp uranium in a power reactor primary heat transport circuit where it is demonstrated that recoil is the dominant release mechanism for small particles of fuel which are deposited on in-core surfaces. A methodology is established whereby release from surface contamination can be distinguished from that of fuel pin failure.

  2. Median recoil direction as a WIMP directional detection signal

    NASA Astrophysics Data System (ADS)

    Green, Anne M.; Morgan, Ben

    2010-03-01

    Direct detection experiments have reached the sensitivity to detect dark matter weakly interacting massive particles (WIMPs). Demonstrating that a putative signal is due to WIMPs, and not backgrounds, is a major challenge, however. The direction dependence of the WIMP scattering rate provides a potential WIMP “smoking gun.” If the WIMP distribution is predominantly smooth, the Galactic recoil distribution is peaked in the direction opposite to the direction of Solar motion. Previous studies have found that, for an ideal detector, of order 10 WIMP events would be sufficient to reject isotropy, and rule out an isotropic background. We examine how the median recoil direction could be used to confirm the WIMP origin of an anisotropic recoil signal. Specifically, we determine the number of events required to confirm the direction of solar motion as the median inverse recoil direction at 95% confidence. We find that for zero background 31 events are required, a factor of ˜2 more than are required to simply reject isotropy. We also investigate the effect of a nonzero isotropic background. As the background rate is increased the number of events required increases, initially fairly gradually and then more rapidly, once the signal becomes subdominant. We also discuss the effect of features in the speed distribution at large speeds, as found in recent high resolution simulations, on the median recoil direction.

  3. Median recoil direction as a WIMP directional detection signal

    SciTech Connect

    Green, Anne M.; Morgan, Ben

    2010-03-15

    Direct detection experiments have reached the sensitivity to detect dark matter weakly interacting massive particles (WIMPs). Demonstrating that a putative signal is due to WIMPs, and not backgrounds, is a major challenge, however. The direction dependence of the WIMP scattering rate provides a potential WIMP 'smoking gun'. If the WIMP distribution is predominantly smooth, the Galactic recoil distribution is peaked in the direction opposite to the direction of Solar motion. Previous studies have found that, for an ideal detector, of order 10 WIMP events would be sufficient to reject isotropy, and rule out an isotropic background. We examine how the median recoil direction could be used to confirm the WIMP origin of an anisotropic recoil signal. Specifically, we determine the number of events required to confirm the direction of solar motion as the median inverse recoil direction at 95% confidence. We find that for zero background 31 events are required, a factor of {approx}2 more than are required to simply reject isotropy. We also investigate the effect of a nonzero isotropic background. As the background rate is increased the number of events required increases, initially fairly gradually and then more rapidly, once the signal becomes subdominant. We also discuss the effect of features in the speed distribution at large speeds, as found in recent high resolution simulations, on the median recoil direction.

  4. 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.

  5. Vascular targeted radioimmunotherapy with 213Bi--an alpha-particle emitter.

    PubMed

    Kennel, S J; Mirzadeh, S

    1998-04-01

    To destroy both tumor blood vessels and adjacent tumor cells, an alpha-particle emitter, 213Bi, has been targeted with a monoclonal antibody (MAb) to vessels that feed lung tumors in mice. Animals, bearing approximately 100 EMT-6 carcinomas each of 50-400 cells in size in the lung, that were treated with 120 muCi of 213Bi-MAb 201B were all cured of their disease. Animals treated when tumors were larger (10(3)-10(4) cells) had extended life spans, but a small number of residual tumors eventually killed the animals. Significant extension of life span was also induced with another tumor model-rat tracheal carcinoma growing in the lungs of SCID mice that were then treated with 136 muCi 213Bi-MAb 201B. These studies indicate that attack of both blood vessels and tumor cells simultaneously is an effective mode of cancer treatment. PMID:9620629

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

    SciTech Connect

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

    1995-07-01

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

  7. 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.

  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. PMID:23905352

  10. Electron correlations in single-electron capture from helium by fast protons and {alpha} particles

    SciTech Connect

    Mancev, Ivan; Milojevic, Nenad

    2010-02-15

    Single-electron capture from heliumlike atomic systems by bare projectiles is investigated by means of the four-body boundary-corrected first Born approximation (CB1-4B). The effect of the dynamic electron correlation is explicitly taken into account through the complete perturbation potential. The quantum-mechanical post and prior transition amplitudes for single charge exchange encompassing symmetric and/or asymmetric collisions are derived in terms of two-dimensional real integrals in the case of the prior form and five-dimensional quadratures for the post form. An illustrative computation is performed for single-electron capture from helium by protons and {alpha} particles at intermediate and high impact energies. The role of dynamic correlations is examined as a function of increased projectile energy. The validity and utility of the proposed CB1-4B method is critically assessed in comparison with the existing experimental data for total cross sections, and excellent agreement is obtained.

  11. 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.

  12. 212Bi-DOTMP: an alpha particle emitting bone-seeking agent for targeted radiotherapy.

    PubMed

    Hassfjell, S P; Bruland, O S; Hoff, P

    1997-04-01

    The synthesis and in vivo stability of the bone-seeking alpha-particle emitting compounds 212Bi-DOTMP and 212Pb/212Bi-DOTMP are described. 212Bi-DOTMP, injected i.v. into Balb/c mice, showed prominent bone localization and a rapid clearance from blood and other organs. Femur/blood ratios increased from 13 at 15 min up to 490 at 2.0 h postinjection. Enhanced uptake of 212Bi-DOTMP was demonstrated in regions with high bone turnover. A comparison between 212Bi-DOTMP and [153Sm]Sm-EDTMP showed essentially no differences in biodistribution. 212Pb/212Bi-DOTMP followed a similar biodistribution, except for slightly elevated levels of 212Bi in the kidneys. The present study has shown 212Bi-DOTMP to be an in vivo stable bone-seeking radiopharmaceutical with promising biological properties for the treatment of sclerotic metastases and osteoblastic osteosarcoma. PMID:9228657

  13. 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.

  14. Alpha particle vascular brachytherapy in the treatment of in-stent Restenosis.

    PubMed

    Mehdizadeh, Alireza; Fazelzadeh, Afsoon; Karimi, Hamed

    2009-08-14

    In-stent Restenosis (ISR) is the Achilles heel for using of stent. Vascular brachytherapy (VBT) has been the principal scientifically investigated local therapy for coronary artery ISR. In our suggested method, a new type of stent, which is coated with Boron ((10)B) compound, is used. The coating layer of the stent consists of stable isotype of (10)B. Boron Neutron Capture Therapy produced alpha particle has enough energy to kill the cells adjacent to the stent, which is the site of boron deposition. It would prevent from ISR and intimal proliferation. After percutaneous coronary intervention (PCI) and insertion of stent, follow-up should be done continuously, and if ISR is detected, BNCT will be used to treat the recurrence. Using this modality of VBT would help us to overcome the pitfalls in en vogue radiotherapy methods. PMID:18625530

  15. 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.

  16. Alpha-particles as probes of nuclear shape and structure effects in proton evaporation spectra

    SciTech Connect

    Sarantites, D.G.; Nicolis, N.G.; Abenante, V.; Majka, Z.; Semkow, T.M. ); Baktash, C.; Beene, J.R.; Garcia-Bermudez, G.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Virtanen, A. ); Griffin, H.C. )

    1990-01-01

    The emission barriers and subbarrier anisotropies in the alpha-particle decay with respect to the spin direction on Sn and rare earth compound nuclei are examined in the light of recent calculations incorporating deformation effects in the decay process. For the Sn systems the spectral shapes and anisotropies can be examined without involving deformation. For the rare earth systems deformation which increases with spin is necessary to explain the data. Energy spectra and angular correlations of evaporated protons from the {sup 52}Cr ({sup 34}S, 2p2n){sup 82}Sr reaction were measured in coincidence with discrete transitions. Large shifts in proton spectra were observed when high spin states in different rotational bands are populated. These effects cannot be explained by statistical model calculations that do not include explicitly nuclear structure effects in the deexcitation process. They are interpreted as due to near-yrast stretched proton emission, which preferentially populates the yrast band by subbarrier protons.

  17. Phase and structural transformations in metallic iron under the action of heavy ions and recoil nuclei.

    PubMed

    Alekseev, I; Novikov, D

    2014-02-01

    By the use of various modes of Mössbauer spectroscopy after effects of irradiation of metal iron with (12)C(4+) and (14)N(5+) ions of medium energies, and alpha-particles and the (208)Tl, (208,212)Pb, and (216)Po recoil from a (228)Th-source have been studied. The experimental data obtained in the study enabled various types of external and internal radiation to be compared in regard to the damage they cause, as well as to their effect on the structure-, phase composition- and corrosion resistance properties of metallic iron. Irradiation with (12)C(4+) and (14)N(5+) ions is accompanied by both structural disordering of the α-Fe lattice, and the appearance of γ-phase in the bulk metal. This is indicated by a single line which is 2 to 3-fold broadened (as compared to the lines of the magnetic sextet). This is a result of a strong local heating of the lattice in the thermal spike area with a subsequent instant cooling-down and recrystallization of this "molted" area. Irradiation of iron foils with (12)C(4+)- and (14)N(5+) ions and with recoil nuclei does provoke corrosion processes (the formation of γ-FeOOH) and is accompanied by an intensive oxidation of the metal. PMID:24378918

  18. 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

    2001-12-01

    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. PMID:11734643

  19. 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.

  20. 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. PMID:15987754

  1. Discovery of the alpha decay of 109I

    NASA Astrophysics Data System (ADS)

    Mazzocchi, C.; Grzywacz, R.; Bingham, C. R.; Simpson, D.; Gross, C. J.; Rykaczewski, K. P.; Batchelder, J. C.; Liddick, S. N.; Page, R. D.; Korgul, A.; Krolas, W.; Ilyushkin, S.; Winger, J. A.; Hamilton, J. H.; Hwang, J. K.; Li, K.

    2006-10-01

    Alpha emission is a rich source for nuclear-structure information [1]. The alpha-particle energies Eα, corrected for the recoil effect, yield the difference between the ground-state masses of parent and daughter nuclides (Qα). Far from stability the determination of Qα often represents the only way to determine the masses of ground and isomeric states. The evolution of Qα values along an alpha-decay chain are also a probe for shell effects. In the region above ^100Sn an alpha-decay island occurs, its presence is related to the strong Z=50, N=50 double shell-closure. In an experiment performed at the Recoil Mass Separator of the HRIBF at Oak Ridge National Laboratory, the first evidence for the alpha-decay branch of the proton-emitter ^109I was obtained. The results and the consequences for nuclear masses in this region will be discussed. [1] E. Roeckl, Alpha decay, in: Nuclear Decay Modes, ed. D.N. Poenaru, IoP Publishing, 1996, p. 237.

  2. High-energy recoil-ion emission in keV heavy-ion surface collisions

    NASA Astrophysics Data System (ADS)

    van Someren, B.; Rudolph, H.; Urazgil'din, I. F.; van Emmichoven, P. A. Zeijlmans; Niehaus, A.

    1997-11-01

    For keV Xe +, Kr + and Ar + ions incident at 30° on Cu(110) we have observed the emission of negatively charged particles with energies up to about 40% of the primary energy. By time-of-flight techniques we have found that electrons are emitted with energies up to 80 eV, whereas the negatively charged high-energy particles are Cu - recoil ions. High-energy Cu + ions have also been found. Simple energy and momentum conservation arguments show that such high recoil energies are indeed possible for multiple collision events in which the primary recoil ion scatters off one or more Cu atoms.

  3. Angular and velocity distributions of secondary particles emitted in interaction of 3. 6-GeV/nucleon. cap alpha. particles and lead nuclei

    SciTech Connect

    Antonenko, V.G.; Vinogradov, A.A.; Galitskii, V.M.; Grigor'yan, Y.I.; Ippolitov, M.S.; Karadzhev, K.V.; Kuz'min, E.A.; Man'ko, V.I.; Ogloblin, A.A.; Paramonov, V.V.; Tsvetkov, A.A.

    1980-04-01

    The technique is described and results presented of measurements of the velocity and angular distributions of pions, protons, and deuterons, and tritons emitted in bombardment of lead nuclei by ..cap alpha.. particles with energy 3.6 GeV/nucleon.

  4. Alpha-quartz-induced chemokine expression by rat lung epithelial cells: effects of in vivo and in vitro particle exposure.

    PubMed

    Driscoll, K E; Howard, B W; Carter, J M; Asquith, T; Johnston, C; Detilleux, P; Kunkel, S L; Isfort, R J

    1996-11-01

    Chemokines are chemotactic cytokines that can play a key role in leukocyte recruitment to sites of tissue injury or infection. Previous studies have demonstrated that exposure to alpha-quartz as well as other noxious particles increases chemokine gene expression in rat lung, although the cells responsible for chemokine expression and the mechanisms underlying this response have remained unclear. The present studies demonstrate that exposure of rats to alpha-quartz induced expression of mRNA for the chemokine macrophage-inflammatory protein (MIP)-2 in epithelial cells lining the terminal bronchioles and alveolar ducts as well as macrophages and alveolar type II cells in the more distal lung. Treatment of rats with an anti-MIP-2 antiserum before alpha-quartz exposure markedly attenuated neutrophilic infiltration of the lungs demonstrating an important role for MIP-2 in alpha-quartz-induced pulmonary inflammation. In vitro exposure of primary cultures of rat alveolar type II cells or the rat alveolar type II cell line RLE-6TN to tumor necrosis factor-alpha, endotoxin, or alpha-quartz increased mRNA for MIP-2 as well as the structurally and functionally similar chemokine cytokine-induced neutrophil chemoattractant but not the chemokine MIP-1 alpha. The alpha-quartz-induced increase in epithelial MIP-2 mRNA resulted, at least in part, from increased gene transcription and was associated with the release of active MIP-2 protein. Induction of RLE-6TN MIP-2 and cytokine-induced neutrophil chemoattractant mRNA expression was not unique to alpha-quartz, being also increased by crocidolite asbestus fibers but not by titanium dioxide or MMVF-10 glass fibers. These findings indicate that epithelial cells contribute to chemokine expression in rat lung after exposure to alpha-quartz and potentially other noxious particles and suggest that alpha-quartz-activated MIP-2 expression in vivo results, at least in part, from a direct action of the particles on the lung epithelium. PMID

  5. Diffusion studies of Ra and Pb in GaAs by the alpha-particle energy loss method

    NASA Astrophysics Data System (ADS)

    Adamcyk, M.; Beaudoin, M.; Kelson, I.; Levy, Y.; Tiedje, T.

    1998-12-01

    The temperature dependence of the diffusion of lead in GaAs is determined by measuring the modification to the energy spectrum of emitted alpha particles from the decay chain of implanted 212Pb atoms. Diffusion rates are measured for temperatures up to 900 °C. Higher rates are observed for the diffusion in silicon-doped GaAs than in semi-insulating GaAs. An upper limit for the diffusion of radium in GaAs is similarly obtained from the decay of the 224Ra isotope. Implications for the use of implanted alpha sources for thickness monitoring during epitaxial film growth by the alpha-particle energy loss method are discussed.

  6. Energy and Mass Dependences of the Parameters of the Semimicroscopic Folding Model for Alpha Particles at Low and Intermediate Energies

    SciTech Connect

    Kuterbekov, K.A.; Zholdybayev, T.K.; Kukhtina, I.N.; Penionzhkevich, Yu.E.

    2005-06-01

    The energy and mass dependences of the parameters of the semimicroscopic alpha-particle potential are investigated for the first time in the region of low and intermediate energies. Within the semimicroscopic folding model, both elastic and inelastic differential and total cross sections for reactions on various nuclei are well described by using global parameters obtained in this study.

  7. Distributions of cell populations within. cap alpha. -particle range of plutonium deposits in the rat and beagle testis

    SciTech Connect

    Miller, S.C.; Rowland, H.G.; Bowman, B.M.

    1985-01-01

    Plutonium is not uniformly distributed in testicular tissues; thus some cell populations may receive larger or smaller radiation exposures than would be expected if the nuclide were uniformly distributed. The distributions of cell populations within ..cap alpha..-particle range of Pu deposits in rat and beagle testes were determined. The data were collected from autoradiographs of testicular tissues containing /sup 241/Pu. A cell distribution factor (CDF) was determined for each cell population and is defined as the average number of each cell type within ..cap alpha..-particle range of each observed Pu deposit relative to the number of each cell type that would be expected within ..cap alpha..-particle range of each Pu deposit, if the deposits were distributed uniformly. In addition, the percentage of the spermatogonial stem cell population within ..cap alpha..-particle range of Pu deposits was determined. The largest CDFs seen in both species were in the interstitial tissues, particulary for Leydig cells. Because the organization of testicular tissues in the beagle is quite different from rodents but more similar to human, the results from this study suggest that extrapolations from rodents to humans may tend to overestimate the potential for radiation exposure to spermatogonial stem cells as well as the fraction of the spermatogonial stem cell population at risk to exposure from internally deposited /sup 239/Pu.

  8. 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.

  9. Electron recombination in low-energy nuclear recoils tracks in liquid argon

    NASA Astrophysics Data System (ADS)

    Wojcik, M.

    2016-02-01

    This paper presents an analysis of electron-ion recombination processes in ionization tracks of recoiled atoms in liquid argon (LAr) detectors. The analysis is based on the results of computer simulations which use realistic models of electron transport and reactions. The calculations reproduce the recent experimental results of the ionization yield from 6.7 keV nuclear recoils in LAr. The statistical distribution of the number of electrons that escape recombination is found to deviate from the binomial distribution, and estimates of recombination fluctuations for nuclear recoils tracks are obtained. A study of the recombination kinetics shows that a significant part of electrons undergo very fast static recombination, an effect that may be responsible for the weak drift-field dependence of the ionization yield from nuclear recoils in some noble liquids. The obtained results can be useful in the search for hypothetical dark matter particles and in other studies that involve detection of recoiled nuclei.

  10. The {alpha}-particle imaging of a compressed core of microtargets in a pinhole camera with a regular multi-pinhole diaphragm

    SciTech Connect

    Suslov, N A

    2000-08-31

    The {alpha}-particle imaging of a compressed core of microtargets using a multi-pinhole regular diaphragm is proposed. The image reconstruction technique is described. The results of the {alpha}-particle imaging of a compressed core of microtargets obtained at the 'Iskra-4' laser facility are reported. (interaction of laser radiation with matter. laser plasma)

  11. 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.

  12. First measurement of the ionization yield of nuclear recoils in liquid argon

    SciTech Connect

    Joshi, T.; Sangiorgio, Samuele; Bernstein, A.; Foxe, Michael P.; Hagmann, Chris; Jovanovic, Igor; Kazkaz, K.; Mozin, Vladimir V.; Norman, E. B.; Pereverzev, S. V.; Rebassoo, Finn O.; Sorensen, Peter F.

    2014-05-01

    Liquid phase argon has long been used as a target medium for particle detection via scintillation light. Recently there has been considerable interest in direct detection of both hypothetical darkmatter particles and coherent elastic neutrino nucleus scattering. These as-yet unobserved neutral particle interactions are expected to result in a recoiling argon atom O(keV), generally referred to in the literature as a nuclear recoil. This prompts the question of the available electromagnetic signal in a liquid argon detector. In this Letter we report the first measurement of the ionization yield (Qy), detected electrons per unit energy, resulting from nuclear recoils in liquid argon, measured at 6.7 keV. This is also the lowest energy measurement of nuclear recoils in liquid argon.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    Plionis, A. A.; Peterson, D. S.; Tandon, L.; LaMont, S. P.

    2010-03-01

    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 non-distructive isotopic data that can distinguish process uranium from natural sources and the degree of uranium contribution to the total accumulated particle load. In addition, the particle size bins utilized by the impactors provide adequate resolution to determine if a process particle size distribution is: lognormal, bimodal, or trimodal. Data on process uranium particle size values and distributions facilitate the development of more sophisticated and accurate models for internal dosimetry, resulting in an improved understanding of foundry worker health and safety.

  15. 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.

  16. First observation of alpha particle loss induced by kinetic ballooning modes in TFTR deuterium-tritium experiments

    SciTech Connect

    Chang, Z.; Budny, R.V.; Chen, L.; Darrow, D.; Fredrickson, E.D.; Janos, A.; Mansfield, D.; Mazzucato, E.; McGuire, K.M.; Nazikian, R.; Rewoldt, G.; Strachan, J.D.; Tang, W.M.; Taylor, G.; White, R.B.; Zweben, S. |; TFTR group

    1996-02-01

    A correlation between the measured alpha particle loss and high frequency ({approximately}100{endash}200 kHz) magnetohydrodynamic (MHD) modes has been observed in some high {beta} (= plasma pressure/magnetic pressure) DT plasmas in TFTR. These modes are localized around the peak plasma pressure gradient and have ballooning characteristics. Particle simulation shows that the loss is due to wave-particle resonances. Linear instability analysis indicates that the plasma is unstable to the kinetic MHD ballooning modes driven by strong local pressure gradients. {copyright} {ital 1996 The American Physical Society.}

  17. Alpha-Particle/Proton Differential Flow in the Solar Wind: Implications for Plasma Heating, Azimuthal Flow, and the Parker Spiral Magnetic Field

    NASA Astrophysics Data System (ADS)

    Verscharen, D.; Bourouaine, S.; Chandran, B. D. G.

    2014-12-01

    Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including temperature anisotropies and relative drifts along the direction of the background magnetic field. Two mechanisms have been proposed for limiting differential flow between alpha particles and protons: plasma instabilities and the rotational force. Both mechanisms decelerate the alpha particles - for example, the Alfvén/ion-cyclotron and fast-magnetosonic/whistler instabilities limit the drift velocity to a value comparable to the Alfvén speed, which decreases with increasing heliocentric distance r. However, while plasma instabilities transform bulk-flow kinetic energy into heat and plasma waves, the rotational force does not. We present an analytic expression for the rate Qflow at which energy is released when alpha particles are decelerated by instabilities. We find that Qflow becomes zero at a critical radius r=rcrit, where rcrit is between 1.5 AU and 2 AU in the fast solar wind in the ecliptic plane, and rcrit increases with increasing heliographic latitude. We show that instabilities control the deceleration of alpha particles at ralpha particles at r>rcrit. We compare the value of Qflow at ralpha particles deduced from in-situ measurements of fast-wind streams from the Helios and Ulysses spacecraft. We find that Qflow exceeds the empirical heating rate for alpha particles at r<1 AU. We conclude that the continuous energy input from alpha-particle deceleration at ralpha-particle drift for the azimuthal flow velocities of the ions and for the Parker spiral magnetic field.

  18. 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.

  19. Alpha decay of {sup 181}Pb

    SciTech Connect

    Davids, C.N.; Henderson, D.J.; Hermann, R.

    1995-08-01

    The {alpha}-decay energy of {sup 181}Pb was measured as 7211(10) keV and 7044(15). In the first study the isotope was produced in {sup 90}Zr bombardments of {sup 94}Mo and, after traversing a velocity filter, implanted in a position-sensitive Si detector; no half life for {sup 181}Pb was reported. In the second study the isotope was produced in {sup 40}Ca bombardments of {sup 144}Sm and transported to a position in front of a Si(Au) surface barrier detector with a fast He-gas-jet capillary system; an estimate of 50 ms was determined for the {sup 181}Pb half life. Recently we investigated {sup 181}Pb {alpha} decay at ATLAS as part of a survey experiment in which a l-pnA beam of 400-MeV {sup 92}Mo was used to irradiate targets of {sup 89}Y, {sup 90,92,94}Zr, and {sup 92}Mo to examine yields for one- and two-nucleon evaporation products from symmetric cold-fusion reactions. Recoiling nuclei of interest were passed through the Fragment Mass Analyzer and implanted in a double-sided silicon strip detector for {alpha}-particle assay. With the {sup 90}Zr target we observed a group at 7065(20) keV which was correlated with A = 181 recoils and had a half life of 45(20) ms. Our new results for {sup 181}Pb therefore agreed with those of the second study. There was no indication in the {sup 90}Zr + {sup 92}Mo data of the 7211(10)-keV {alpha} particles seen by Keller et al. The interested reader is referred to the 1993 atomic mass evaluation wherein the input {alpha}-decay energies and resultant masses of the light Pb isotopes (including {sup 181}Pb) are discussed.

  20. 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.

  1. Calibration of the Mars Science Laboratory Alpha Particle X-ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Campbell, John L.; Perrett, Glynis M.; Gellert, Ralf; Andrushenko, Stefan M.; Boyd, Nicholas I.; Maxwell, John A.; King, Penelope L.; Schofield, Céleste D. M.

    2012-09-01

    The alpha-particle X-ray spectrometer (APXS) for the Mars Science Laboratory (MSL) mission was calibrated for routine analysis of: Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Zn, Br, Rb, Sr, and Y. The following elements were also calibrated, but may be too low to be measured (10s-100s ppm) for their usual abundance on Mars: V, Cu, Ga, As, Se and W. An extensive suite of geological reference materials, supplemented by pure chemical elements and compounds was used. Special attention was paid to include phyllosilicates, sulfates and a broad selection of basalts as these are predicted minerals and rocks at the Gale Crater landing site. The calibration approach is from first principles, using fundamental physics parameters and an assumed homogeneous sample matrix to calculate expected elemental signals for a given instrument setup and sample composition. Resulting concentrations for most elements accord with expected values. Deviations in elements of lower atomic number (Na, Mg, Al) indicate significant influences of mineral phases, especially in basalts, ultramafic rocks and trachytes. The systematics of these deviations help us to derive empirical, iterative corrections for different rock groups, based on a preliminary APXS analysis which assumes a homogeneous sample. These corrections have the potential to significantly improve the accuracy of APXS analyses, especially when other MSL instrument results, such as the X-ray diffraction data from CheMin, are included in the overall analysis process.

  2. Prompt detection of alpha particles from 210Po: another clue to the origin of rock varnish?

    PubMed

    Hodge, Vernon F; Farmer, Dennis E; Diaz, Tammy; Orndorff, Richard L

    2005-01-01

    Alpha particles have been measured coming from the surfaces of rocks covered with dark red-brown rock varnish, as well as rocks that appear to have little, if any, varnish. A pronounced peak at 5.3 MeV indicates the presence of 210Po, a short-lived natural-radioactive element. Surface activities for 33 samples range from 0.008 Bq/cm2 to 0.065 Bq/cm2. It is estimated that this nuclide is concentrated 10(11) times in these paper-thin coatings above its concentration in ground-level air. Gamma rays from the decay of 137Cs, a product of testing nuclear weapons some 50 years ago, were also detected. Analysis of samples of varnish stripped from the rock revealed traces of 239,240Pu and 238Pu. The presence of all of these isotopes strongly supports the theory that varnish films derive their building blocks from the atmosphere and, with time, all rocks in arid environments will become coated. PMID:15511566

  3. Radiation damage induced by MeV alpha particles in polycrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Gonon, P.; Prawer, S.; Nugent, K. W.; Jamieson, D. N.

    1996-11-01

    Radiation damage induced by 2 MeV alpha particles in polycrystalline diamond films has been studied as a function of the irradiation dose D (1012≤D≤1017 cm-2). The films were characterized using Raman/photoluminescence spectroscopy and I(V,T) measurements. The results can be summarized as follows. In undoped samples the H3 luminescent center (N-V-N) is observed for D≥1014 cm-2. The Raman diamond peak is broadened and shifted to lower frequencies for D≳1015 cm-2. No new graphitic component is detected after irradiation. On the contrary graphitic sp2 defects are annealed by irradiation. For D=3×1016 cm-2 new Raman defect peaks are detected at 1496 and 1635 cm-1. I(V,T) characteristics remain unaffected for D≤1016 cm-2. An increase in the conductivity is observed for D=3×1016 cm-2. At this dose we observe an activation energy of 0.4 eV and thermally stimulated currents related to defect levels at about 0.3 eV. A boron-doped sample (100 Ω cm) has been irradiated at 1017 cm-2 for comparison. After irradiation the conductivity of this sample is reduced and the activation energy of the conductivity is also reduced. Less damage is detected by Raman spectroscopy in the B-doped material.

  4. Log Normal Distribution of Cellular Uptake of Radioactivity: Statistical Analysis of Alpha Particle Track Autoradiography

    PubMed Central

    Neti, Prasad V.S.V.; Howell, Roger W.

    2008-01-01

    Recently, the distribution of radioactivity among a population of cells labeled with 210Po was shown to be well described by a log normal distribution function (J Nucl Med 47, 6 (2006) 1049-1058) with the aid of an autoradiographic approach. To ascertain the influence of Poisson statistics on the interpretation of the autoradiographic data, the present work reports on a detailed statistical analyses of these data. Methods The measured distributions of alpha particle tracks per cell were subjected to statistical tests with Poisson (P), log normal (LN), and Poisson – log normal (P – LN) models. Results The LN distribution function best describes the distribution of radioactivity among cell populations exposed to 0.52 and 3.8 kBq/mL 210Po-citrate. When cells were exposed to 67 kBq/mL, the P – LN distribution function gave a better fit, however, the underlying activity distribution remained log normal. Conclusions The present analysis generally provides further support for the use of LN distributions to describe the cellular uptake of radioactivity. Care should be exercised when analyzing autoradiographic data on activity distributions to ensure that Poisson processes do not distort the underlying LN distribution. PMID:16741316

  5. 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. PMID:15015582

  6. Particle Leaking, Cross-Section Ratio 10B(n,{alpha})/238U(n,fission), and Excitation Function of the Reaction 10B(n,{alpha})7Li at MeV Energies

    SciTech Connect

    Giorginis, Georgios; Khryachkov, Vitali

    2005-05-24

    The 10B(n,{alpha})7Li reaction was studied in the energy range between 1.5 MeV and 5.6 MeV at the 7-MV Van de Graaff accelerator of IRMM by using a gridded ionisation chamber, signal digitisation, and an intrinsic 238U neutron monitor. The aim was to obtain accurate data for the IAEA Coordinated Research Project (CRP) on the improvement of standard cross sections for light elements. The effect of particle leaking was discovered and its implications investigated. The determination of the cross section {sigma}({alpha}0+{alpha}1) strongly benefits from it but measurements of angular distributions, individual cross sections {sigma}({alpha}0) and {sigma}({alpha}1), and the branching ratio {alpha}0/{alpha}1 are negatively affected. The correct number of reaction events was obtained by identification of unknown particle signatures in the energy spectra as 10B(n,{alpha})7Li events in the form of quasi 7Li+{alpha} particles created by particle leaking. The cross-section ratio 10B(n,{alpha})7Li/238U(n,fission) was measured and the excitation function of 10B(n,{alpha})7Li determined by simultaneously detecting the charged particles from the boron disintegration in the forward hemisphere and the 238U fission fragments in the backward hemisphere. The IRMM cross sections are compared to experimental data of other groups and to predictions of the ENDF/B-VI.8, JENDL-3.3, and JEF-2.2 evaluations.

  7. ''Magic'' Energies for Detecting Light Elements with Resonant Alpha Particle Backscattering

    SciTech Connect

    Wetteland, C.J.; Maggiore, C.J.; Tesmer, J.R.; He, X-M.; Lee, D-H.

    1998-11-04

    Resonant backscattering is widely used to improve the detection limit of the light elements such as B, C, N and O. One disadvantage, however, is that several incident energies are normally needed if the sample contains a number of the light elements. There are ''magic'' energies at which several light elements can be detected simultaneously with suitable sensitivities. When these energies are used along with the elastic recoil detection of hydrogen, multiple elements can be detected without changing the beam energy, and the analysis time is greatly reduced. These reactions along with examples will be discussed.

  8. Particle size and interfacial effects on heat transfer characteristics of water and {alpha}-SiC nanofluids.

    SciTech Connect

    Timofeeva, E.; Smith, D. S.; Yu, W.; France, D. M.; Singh, D.; Routbort, J. L.

    2010-01-01

    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.

  9. 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. PMID:18047085

  10. Direct Measurement of Photon Recoil from a Levitated Nanoparticle

    NASA Astrophysics Data System (ADS)

    Jain, Vijay; Gieseler, Jan; Moritz, Clemens; Dellago, Christoph; Quidant, Romain; Novotny, Lukas

    2016-06-01

    The momentum transfer between a photon and an object defines a fundamental limit for the precision with which the object can be measured. If the object oscillates at a frequency Ω0 , this measurement backaction adds quanta ℏΩ0 to the oscillator's energy at a rate Γrecoil, a process called photon recoil heating, and sets bounds to coherence times in cavity optomechanical systems. Here, we use an optically levitated nanoparticle in ultrahigh vacuum to directly measure Γrecoil. By means of a phase-sensitive feedback scheme, we cool the harmonic motion of the nanoparticle from ambient to microkelvin temperatures and measure its reheating rate under the influence of the radiation field. The recoil heating rate is measured for different particle sizes and for different excitation powers, without the need for cavity optics or cryogenic environments. The measurements are in quantitative agreement with theoretical predictions and provide valuable guidance for the realization of quantum ground-state cooling protocols and the measurement of ultrasmall forces.

  11. Direct Measurement of Photon Recoil from a Levitated Nanoparticle.

    PubMed

    Jain, Vijay; Gieseler, Jan; Moritz, Clemens; Dellago, Christoph; Quidant, Romain; Novotny, Lukas

    2016-06-17

    The momentum transfer between a photon and an object defines a fundamental limit for the precision with which the object can be measured. If the object oscillates at a frequency Ω_{0}, this measurement backaction adds quanta ℏΩ_{0} to the oscillator's energy at a rate Γ_{recoil}, a process called photon recoil heating, and sets bounds to coherence times in cavity optomechanical systems. Here, we use an optically levitated nanoparticle in ultrahigh vacuum to directly measure Γ_{recoil}. By means of a phase-sensitive feedback scheme, we cool the harmonic motion of the nanoparticle from ambient to microkelvin temperatures and measure its reheating rate under the influence of the radiation field. The recoil heating rate is measured for different particle sizes and for different excitation powers, without the need for cavity optics or cryogenic environments. The measurements are in quantitative agreement with theoretical predictions and provide valuable guidance for the realization of quantum ground-state cooling protocols and the measurement of ultrasmall forces. PMID:27367388

  12. Characterization of the CRESST detectors by neutron induced nuclear recoils

    NASA Astrophysics Data System (ADS)

    Coppi, C.; Ciemniak, C.; von Feilitzsch, F.; Gütlein, A.; Hagn, H.; Isaila, C.; Jochum, J.; Kimmerle, M.; Lanfranchi, J.-C.; Pfister, S.; Potzel, W.; Rau, W.; Roth, S.; Rottler, K.; Sailer, C.; Scholl, S.; Usherov, I.; Westphal, W.

    CRESST is an experiment for the direct detection of dark matter particles via nuclear recoils. The CRESST detectors, based on CaWO4 scintillating crystals, are able to discriminate γ and β background by simultaneously measuring the light and phonon signals produced by particle interactions. The discrimination of the background is possible because of the different light output (Quenching Factor, QF) for nuclear and electron recoils. In this article a measurement is shown, aimed at the determination of the QFs of the different nuclei (O, Ca, W) of the detector crystal at 40-60 mK using an 11 MeV neutron beam produced at the Maier-Leibnitz-Laboratorium in Garching (MLL).

  13. Measurement of Nuclear Recoils in the CDMS II Dark Matter Search

    NASA Astrophysics Data System (ADS)

    Fallows, Scott M.

    The Cryogenic Dark Matter Search (CDMS) experiment is designed to directly detect elastic scatters of weakly-interacting massive dark matter particles (WIMPs), on target nuclei in semiconductor crystals composed of Si and Ge. These scatters would occur very rarely, in an overwhelming background composed primarily of electron recoils from photons and electrons, as well as a smaller but non-negligible background of WIMP-like nuclear recoils from neutrons. The CDMS~II generation of detectors simultaneously measure ionization and athermal phonon signals from each scatter, allowing discrimination against virtually all electron recoils in the detector bulk. Pulse-shape timing analysis allows discrimination against nearly all remaining electron recoils taking place near detector surfaces. Along with carefully limited neutron backgrounds, this experimental program allowed for "background-free'' operation of CDMS~II at Soudan, with less than one background event expected in each WIMP-search analysis. As a result, exclusionary upper-limits on WIMP-nucleon interaction cross section were placed over a wide range of candidate WIMP masses, ruling out large new regions of parameter space. These results, like any others, are subject to a variety of systematic effects that may alter their final interpretations. A primary focus of this dissertation will be difficulties in precisely calibrating the energy scale for nuclear recoil events like those from WIMPs. Nuclear recoils have suppressed ionization signals relative to electron recoils of the same recoil energy, so the response of the detectors is calibrated differently for each recoil type. The overall normalization and linearity of the energy scale for electron recoils in CDMS~II detectors is clearly established by peaks of known gamma energy in the ionization spectrum of calibration data from a 133Ba source. This electron-equivalent keVee) energy scale enables calibration of the total phonon signal (keVt) by enforcing unity

  14. The energy spectra of protons and alpha particles above 300 keV/nucleon during quiet times

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.; Hovestadt, D.; Klecker, B.; Vollmer, O.; Fan, C. Y.

    1975-01-01

    An unusual spectral feature and anomalously large abundance of helium between 0.6 and about 2 MeV/nucleon observed during the most quiet time periods in 1974 indicate the presence of low energy helium of an unknown origin. During these same quiet periods protons below 1.5 MeV and alphas below 0.6 MeV/nucleon have a power law energy spectrum with an index of -1.8 and the proton to alpha ratio is about 30. From these results and the measured anisotropy of these particles we conclude that the sun emits less than about 1 MeV particles continuously even during its most inactive periods.

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

    SciTech Connect

    Zaider, M.

    1992-12-31

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

  16. 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.

  17. Energy loss straggling of low energy alpha particles in a medium composed of polyatomic and diatomic molecules

    NASA Astrophysics Data System (ADS)

    Milošević, Z.; Novković, D.; Subotić, K.

    1996-08-01

    The results of the measurement of the energy straggling of low energy alpha particles in the polyatomic and diatomic molecule media are reported. A general analytical formula for straggling widths of light ions, obtained by solving Symon's equation for the second and third order central moments of the straggling distributions in non-relativistic approximation, has shown remarkably good agreement with experimental data at energy losses less than 70% of the initial projectile energies.

  18. First evidence of collective alpha particle effect on toroidal Alfv{acute e}n eigenmodes in the TFTR D-T experiment

    SciTech Connect

    Wong, K.L.; Schmidt, G.L.; Batha, S.H.; Bell, R.; Chang, Z.; Chen, L.; Darrow, D.S.; Duong, H.H.; Fu, G.Y.; Hammett, G.W.; Levinton, F.; Majeski, R.; Mazzucato, E.; Nazikian, R.; Owens, D.K.; Petrov, M.; Rogers, J.H.; Schilling, G.; Wilson, J.R.

    1996-03-01

    The alpha particle effect on the excitation of toroidal Alfv{acute e}n eigenmodes (TAE) was investigated in deuterium-titrium (D-T) plasmas in the Tokamak Fusion Test Reactor. rf power was used to position the plasma near the instability threshold, and the alpha particle effect was inferred from the reduction of rf power threshold for TAE instability in D-T plasmas. Initial calculations indicate that the alpha particles contribute 10{percent}{endash}30{percent} of the total drive in a D-T plasma with 3 MW of peak fusion power. {copyright} {ital 1996 The American Physical Society.}

  19. 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.

  20. Distributions of alpha particles escaping to the wall during sawtooth oscillations in the Tokamak Fusion Test Reactor

    SciTech Connect

    Kolesnichenko, Y.I.; Lutsenko, V.V.; White, R.B.; Yakovenko, Y.V.; Zweben, S.J.

    1999-04-01

    It has been observed experimentally in deuterium{endash}tritium shots of the Tokamak Fusion Test Reactor (TFTR) [D. J. Grove and D. M. Meade, Nucl. Fusion {bold 25}, 1167 (1985)] that crashes of sawtooth oscillations may result in very inhomogeneous flux of alpha particles to the wall. To explain this phenomenon, both theoretical analysis and numerical simulation have been carried out. It is concluded that the {open_quotes}crash-induced prompt loss,{close_quotes} i.e., the orbital loss of marginally trapped particles arising because of the crash-induced orbit transformation of circulating particles, is responsible for the flux near the bottom of the vessel, whereas the crash-induced stochastic diffusion of moderately trapped particles explains the large signal near the equatorial plane of the torus. The calculated poloidal distributions of the integral alpha flux are in reasonable agreement with experimental data. The energy spectrum of the escaping particles has also been calculated, which can be used for diagnostics of the crash type. {copyright} {ital 1999 American Institute of Physics.} thinsp

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

    PubMed

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

    2011-07-01

    A Thomson parabola ion spectrometer has been designed for use at the Multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE) at the University of Rochester. This device uses parallel electric and magnetic fields to deflect particles of a given mass-to-charge ratio onto parabolic curves on the detector plane. Once calibrated, the position of the ions on the detector plane can be used to determine the particle energy. The position dispersion of both the electric and magnetic fields of the Thomson parabola was measured using monoenergetic proton and alpha particle beams from the SUNY Geneseo 1.7 MV tandem Pelletron accelerator. The sensitivity of Fujifilm BAS-TR imaging plates, used as a detector in the Thomson parabola, was also measured as a function of the incident particle energy over the range from 0.6 MeV to 3.4 MeV for protons and deuterons and from 0.9 MeV to 5.4 MeV for alpha particles. The device was used to measure the energy spectrum of laser-produced protons at MTW. PMID:21806176

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  3. Angular Momentum Ejection and Recoil*

    NASA Astrophysics Data System (ADS)

    Ohia, O.; Coppi, B.

    2009-11-01

    The spontaneous rotation phenomenon observed in axisymmetric magnetically confined plasmas has been explained by the ``accretion theory'' [1] that considers the plasma angular momentum as gained from its interaction with the magnetic field and the surrounding material wall. The ejection of angular momentum to the wall, and the consequent recoil are attributed to modes excited at the edge while the transport of the (recoil) angular momentum from the edge toward the center is attributed to a different kind of mode. The toroidal phase velocity of the edge mode, to which the sign of the ejected angular momentum is related, is considered to change its direction in the transition from the H-regime to the L-regime. For the latter case, edge modes with phase velocity in the direction of vdi are driven by the temperature gradient of a cold ion population at the edge and damped on the ``hot'' ion population. The ``balanced'' double interaction [2] of the mode with the two populations, corresponding to a condition of marginal stability, leads to ejection of hot ions and loss of angular momentum in the direction of vdi while the cold population acquires angular momentum in the opposite direction. In the H-regime resistive ballooning modes with phase velocities in the direction of vde are viewed as the best candidates for the excited edge modes. *Sponsored in part by the U.S. DOE. [1] B. Coppi, Nucl. Fusion 42, 1 (2002) [2] B. Coppi and F. Pegoraro, Nucl. Fusion 17, 969 (1977)

  4. 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%.

  5. A recoil separator for nuclear astrophysics SECAR

    NASA Astrophysics Data System (ADS)

    Berg, G. P. A.; Bardayan, D. W.; Blackmon, J. C.; Chipps, K. A.; Couder, M.; Greife, U.; Hager, U.; Montes, F.; Rehm, K. E.; Schatz, H.; Smith, M. S.; Wiescher, M.; Wrede, C.; Zeller, A.

    2016-06-01

    A recoil separator SECAR has been designed to study radiative capture reactions relevant for the astrophysical rp-process in inverse kinematics for the Facility for Rare Isotope Beams (FRIB). We describe the design, layout, and ion optics of the recoil separator and present the status of the project.

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

    NASA Astrophysics Data System (ADS)

    Dörschel, B.; Hermsdorf, D.; Pieck, S.; Starke, S.; Thiele, H.; Weickert, F.

    2003-06-01

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

  7. Toward a theory of the initiation of cancer by ionizing radiation: track structure analysis for electrons and alpha particles in water

    SciTech Connect

    Pagnamenta, A.; Marshall, J.H.

    1980-01-01

    Following a method of Kim differential cross sections have been constructed in analytical form for the ionization of water by electrons and alpha particles. By generalizing Wideroe's bookkeeping mmethod the number of higher order delta rays were found. (ACR)

  8. 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.

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

    PubMed

    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. 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

  12. 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.

  13. 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. PMID:1475356

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

    SciTech Connect

    Hwang, D.Q.; Horton, R.D.; Evans, R.W.

    1999-06-03

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

  15. Modelling TF ripple loss of alpha particles in TFTR DT experiments

    SciTech Connect

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

    1995-07-01

    Modelling of TF ripple loss of alphas in DT experiments on TFTR now includes neoclassical calculations of first orbit loss, stochastic ripple diffusion, ripple trapping and collisional effects. A rapid way to simulate experiment has been developed which uses a simple stochastic domain model for TF ripple loss within the TRANSP analysis code, with the ripple diffusion threshold evaluated by comparison with more accurate but computationally expensive Hamiltonian coordinate guiding center code simulations. Typical TF collisional ripple loss predictions are 6-10% loss of alphas for TFTR D-T experiments at I{sub p} = 1.0-2.0 MA and R = 2.52 m.

  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. PMID:19920193

  17. Response of Ni/4H-SiC Schottky barrier diodes to alpha-particle irradiation at different fluences

    NASA Astrophysics Data System (ADS)

    Omotoso, E.; Meyer, W. E.; Auret, F. D.; Diale, M.; Ngoepe, P. N. M.

    2016-01-01

    Irradiation experiments have been carried out on 1.9×1016 cm-3 nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.6×1010 to 9.2×1011 cm-2. Current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements have been carried out to study the change in characteristics of the devices and free carrier removal rate due to alpha-particle irradiation, respectively. As radiation fluence increases, the ideality factors increased from 1.20 to 1.85 but the Schottky barrier height (SBHI-V) decreased from 1.47 to 1.34 eV. Free carrier concentration, Nd decreased with increasing fluence from 1.7×1016 to 1.1×1016 cm-2 at approximately 0.70 μm depth. The reduction in Nd shows that defects were induced during the irradiation and have effect on compensating the free carrier. The free carrier removal rate was estimated to be 6480±70 cm-1. Alpha-particle irradiation introduced two electron traps (E0.39 and E0.62), with activation energies of 0.39±0.03 eV and 0.62±0.08 eV, respectively. The E0.39 as attribute related to silicon or carbon vacancy, while the E0.62 has the attribute of Z1/Z2.

  18. 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. PMID:9232893

  19. 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.

  20. Gas powered fluid gun with recoil mitigation

    DOEpatents

    Grubelich, Mark C.; Yonas, Gerold

    2016-03-01

    A gas powered fluid gun for propelling a stream or slug of a fluid at high velocity toward a target. Recoil mitigation is provided that reduces or eliminates the associated recoil forces, with minimal or no backwash. By launching a quantity of water in the opposite direction, net momentum forces are reduced or eliminated. Examples of recoil mitigation devices include a cone for making a conical fluid sheet, a device forming multiple impinging streams of fluid, a cavitating venturi, one or more spinning vanes, or an annular tangential entry/exit.

  1. Gas powered fluid gun with recoil mitigation

    DOEpatents

    Grubelich, Mark C; Yonas, Gerold

    2013-11-12

    A gas powered fluid gun for propelling a stream or slug of a fluid at high velocity toward a target. Recoil mitigation is provided that reduces or eliminates the associated recoil forces, with minimal or no backwash. By launching a quantity of water in the opposite direction, net momentum forces are reduced or eliminated. Examples of recoil mitigation devices include a cone for making a conical fluid sheet, a device forming multiple impinging streams of fluid, a cavitating venturi, one or more spinning vanes, or an annular tangential entry/exit.

  2. 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. PMID:14525368

  3. A New Interpretation of Alpha-particle-driven Instabilities in Deuterium-Tritium Experiments on the Tokamak Fusion Test Reactor

    SciTech Connect

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

    2003-03-26

    The original description of alpha-particle-driven instabilities in the Tokamak Fusion Test Reactor (TFTR) in terms of Toroidal Alfvin 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 anti-ballooning 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.

  4. 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.

  5. 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

  6. Nickel-59 in Surface Layers of Lunar Basalt 74275: Implications for the Solar Alpha Particle Flux

    NASA Technical Reports Server (NTRS)

    Schnabel, C.; Xue, S.; Ma, P.; Herzog, G. F.; Fifield, K.; Cresswell, R. G.; diTada, M. L.; Hausladen, Paul; Reedy, R. C.

    2000-01-01

    By using AMS we have profiled 59 Ni/Ni ratios in lunar basalt 74275. Activities (dpm 59 Ni/[kg Fe]) range from 120 to 10 at depths (mg/cm 2) from about 30 to 650. Modeling results hint at higher solar alpha fluxes during the last about 0.5 My than during the last approximately 1 My.

  7. 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.

  8. 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

  9. Transcriptional Response of Human Cells to Microbeam Irradiation with 2.1 MeV Alpha Particles

    NASA Astrophysics Data System (ADS)

    Hellweg, C. E.; Bogner, S.; Spitta, L.; Arenz, A.; Baumstark-Khan, C.; Greif, K. D.; Giesen, U.

    Within the next decades an increasing number of human beings in space will be simultaneously exposed to different stimuli especially microgravity and radiation To assess the risks for humans during long-duration space missions the complex interplay of these parameters at the cellular level must be understood Cellular stress protection responses lead to increased transcription of several genes via modulation of transcription factors Activation of the Nuclear Factor kappa B NF- kappa B pathway as a possible anti-apoptotic route represents such an important cellular stress response A screening assay for detection of NF- kappa B-dependent gene activation using the destabilized variant of Enhanced Green Fluorescent Protein d2EGFP as reporter protein had been developed It consists of Human Embryonic Kidney HEK 293 Cells stably transfected with a receptor-reporter-construct carrying d2EGFP under the control of a NF- kappa B response element Clones positive for Tumor Necrosis Factor alpha TNF- alpha inducible d2EGFP expression were selected as cellular reporters Irradiation was performed either with X-rays 150 kV 19 mA at DLR Cologne or with 2 1 MeV alpha particles LET sim 160 keV mu m at PTB Braunschweig After irradiation the following biological endpoints were determined i cell survival via the colony forming ability test ii time-dependent activation of NF- kappa B dependent d2EGFP gene expression using flow cytometry iii quantitative RT-PCR

  10. Use of 4.7 MeV alpha particles in elemental analysis and fusion reactor materials studies

    NASA Astrophysics Data System (ADS)

    Constantinescu, B.; Dima, S.; Florescu, V.; Ivanov, E. A.; Ploştinaru, D.; Sârbu, C.

    1986-07-01

    The possibilities for using 4.7 MeV alpha particles produced at the U-120 CIP Cyclotron for charged particle induced X- and gamma-ray emission applications (PIXE and PIGE, respectively) and for fast neutron radiation damage simulation are presented. The combined analysis using PIGE and PIXE methods either separately or simultaneously is an excellent means of determining the relative abundances of lighter elements with gamma-ray spectra and of heavier elements ( Z ⩾ 16) with X-ray spectra. Some aspects of surface deformation effects by neutrons were simulated by means of medium-energy helium ions. An investigation of three types of commercial stainless steel (Romanian W 4016, Soviet 12KH18N10T and Japanese W 4541) was started using 3.0 [1], 4.7 and 6.8 MeV helium ions. The main post-irradiation effects observed are discussed.

  11. Deceleration of Alpha Particles in the Solar Wind by Instabilities and the Rotational Force: Implications for Heating, Azimuthal Flow, and the Parker Spiral Magnetic Field

    NASA Astrophysics Data System (ADS)

    Verscharen, Daniel; Chandran, Benjamin D. G.; Bourouaine, Sofiane; Hollweg, Joseph V.

    2015-06-01

    Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including relative drifts between particle species. Two non-collisional mechanisms have been proposed for limiting differential flow between alpha particles and protons: plasma instabilities and the rotational force. Both mechanisms decelerate the alpha particles. In this paper, we derive an analytic expression for the rate {Q}{flow} at which energy is released by alpha-particle deceleration, accounting for azimuthal flow and conservation of total momentum. We show that instabilities control the deceleration of alpha particles at r\\lt {r}{crit}, and the rotational force controls the deceleration of alpha particles at r\\gt {r}{crit}, where {r}{crit}≃ 2.5 {AU} in the fast solar wind in the ecliptic plane. We find that {Q}{flow} is positive at r\\lt {r}{crit} and {Q}{flow}=0 at r≥slant {r}{crit}, consistent with the previous finding that the rotational force does not lead to a release of energy. We compare the value of {Q}{flow} at r\\lt {r}{crit} with empirical heating rates for protons and alpha particles, denoted {Q}p and {Q}α , deduced from in situ measurements of fast-wind streams from the Helios and Ulysses spacecraft. We find that {Q}{flow} exceeds {Q}α at r\\lt 1 {AU}, and that {Q}{flow}/{Q}p decreases with increasing distance from the Sun from a value of about one at r = 0.29–0.42 AU to about 1/4 at 1 AU. We conclude that the continuous energy input from alpha-particle deceleration at r\\lt {r}{crit} makes an important contribution to the heating of the fast solar wind. We also discuss the implications of the alpha-particle drift for the azimuthal flow velocities of the ions and for the Parker spiral magnetic field.

  12. Imprints of recoiling massive black holes on the hot gas of early-type galaxies

    NASA Astrophysics Data System (ADS)

    Devecchi, B.; Rasia, E.; Dotti, M.; Volonteri, M.; Colpi, M.

    2009-04-01

    Anisotropic gravitational radiation from a coalescing black hole (BH) binary is known to impart recoil velocities of up to ~1000kms-1 to the remnant BH. In this context, we study the motion of a recoiling BH inside a galaxy modelled as a Hernquist sphere, and the signature that the hole imprints on the hot gas, using N-body/smoothed particle hydrodynamics simulations. Ejection of the BH results in a sudden expansion of the gas ending with the formation of a gaseous core, similarly to what is seen for the stars. A cometary tail of particles bound to the BH is initially released along its trail. As the BH moves on a return orbit, a nearly spherical swarm of hot gaseous particles forms at every apocentre: this feature can live up to ~108 years. If the recoil velocity exceeds the sound speed initially, the BH shocks the gas in the form of a Mach cone in density near each supersonic pericentric passage. We find that the X-ray fingerprint of a recoiling BH can be detected in Chandra X-ray maps out to a distance of Virgo. For exceptionally massive BHs, the Mach cone and the wakes can be observed out to a few hundred of milliparsec. The detection of the Mach cone is of twofold importance as it can be a probe of high-velocity recoils, and an assessment of the scatter of the MBH - Mbulge relation at large BH masses.

  13. Preliminary calculations of expected signal levels of a thin Faraday foil lost alpha particle diagnostic for International Thermonuclear Experimental Reactor

    SciTech Connect

    Cecil, F.E.; Darrow, D.S.; Budny, R.V.

    2004-10-01

    Thin Faraday collectors are being considered as a diagnostic of lost alpha particles on International Thermonuclear Experimental Reactor (ITER). In an effort to evaluate the viability of this diagnostic, we are undertaking a series of calculations of the signal levels (A/cm{sup 2}) for such devices. Preliminary results assuming a model high yield ITER plasma have been obtained for locations near the outer wall assuming a toroidally symmetric vacuum vessel. We find signal levels to be a strong function of foil location and orientation. Specifically the signal level will be optimized at a vertical location 0.5 m above the machine midplane and with the normal to the foil directed in the lower, radially outward, toroidally counterclockwise octant. A foil thus oriented at a radial distance of 15 cm from the vessel wall at a height of 0.583 m above the machine midplane will have an efficiency of 3.5x10{sup -8}/cm{sup 2} for alpha particles which undergo classic loss during the first ten revolutions around the torus during this model plasma. For the assumed D-T fusion power of this model plasma of 410 MW, this calculated efficiency will correspond to a measured current in the Faraday foil of 1.7 {mu}A/cm{sup 2}. Future, more realistic calculations must incorporate the effects of an asymmetrical vessel and of toroidal field ripple.

  14. 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.

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

    PubMed

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

    2010-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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 cm2 or 1800 cm2 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 210Pb and comparing the effectiveness of cleaning procedures in removing 222Rn progenies from the samples.

  17. 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.

  18. Accounting for long alpha-particle stopping distances in (U-Th-Sm)/He geochronology: Refinement of the baseline case

    NASA Astrophysics Data System (ADS)

    Ketcham, Richard A.; Gautheron, Cécile; Tassan-Got, Laurent

    2011-12-01

    This contribution proposes a number of methodological refinements for accounting for ejection of energetic particles, most particularly in the case of long alpha-particle stopping distance effects in (U-Th-Sm)/He thermochronometry. Recent stopping-distance estimates for minerals commonly used for thermochronometry are up to 1.5 μm shorter than previously thought, which directly affects the magnitude of the ejection correction parameter FT. The revision in stopping distances necessitates re-fitting the empirical polynomials that have been used to calculate FT corrections for various crystal forms. Reformulation and re-parameterization of these polynomials enables them to account for present and any future change in stopping distances without needing to be recalibrated. The library of shapes described with these polynomials to accommodate habits is expanded for all crystal systems and also ellipsoids, thus covering all minerals currently used and under development for (U-Th-Sm)/He thermochronometry. In addition, the inaccuracy caused by characterizing a set of alpha particles from a decay chain with a single mean stopping distance is examined, and a simple method for compensation is recommended. A new method of using FT parameters to calculate corrected ages by applying them to parents instead of daughters or age is presented, which maximizes accuracy for old specimens such as meteorites. Altogether, the refinements proposed will affect (U-Th-Sm)/He ages by ˜1-5%, depending on size and age. Finally, the concept of an FT-equivalent sphere is introduced as a sphere with the same effective FT value as a given mineral grain. Testing indicates that the FT-equivalent sphere is of comparable or superior accuracy to a sphere of the same surface to volume ratio for diffusion modeling. This finding greatly facilitates utilization of (U-Th-Sm)/He data from standard data tables for forward and inverse modeling.

  19. Alpha particles accompanying the weak decay of {sub {lambda}}{sup 10}Be and {sub {lambda}}{sup 10}B hypernuclei

    SciTech Connect

    Majling, L. Kuzmin, V. A. Tetereva, T. V.

    2006-05-15

    The possibility of a detailed investigation of weak {lambda}N interaction in the {sub {lambda}}{sup 10}Be and {sub {lambda}}{sub /10}B hypernuclei, which stand out owing to their {alpha}{alpha}N{lambda} cluster structure, is discussed. The detection of a few groups of correlated {alpha}{alpha} pairs will furnish information about decays to specific states of product nuclei ({sup 8}Be*, {sup 8}Li, {sup 8}B), thereby paving the way to a phenomenological analysis of the weak decays of p-shell hypernuclei. The ratios of the intensities of individual alpha-particle groups to be measured in experiments at the cyclotron of the Joint Institute for Nuclear Research (JINR, Dubna) will provide a useful criterion for choosing an appropriate model of weak {lambda}N interaction. The current state of hypernuclear physics is briefly reviewed.

  20. Trojan horse particle invariance studied with the {sup 6}Li(d,{alpha}){sup 4}He and {sup 7}Li(p,{alpha}){sup 4}He reactions

    SciTech Connect

    Pizzone, R. G.; Spitaleri, C.; Lamia, L.; Cherubini, S.; La Cognata, M.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Bertulani, C.; Mukhamedzhanov, A.; Blokhintsev, L.; Burjan, V.; Hons, Z.; Kroha, V.; Mrazek, J.; Piskor, S.; Kiss, G. G.; Li, C.; Tumino, A.

    2011-04-15

    The Trojan horse nucleus invariance for the binary reaction cross section extracted from the Trojan horse reaction was tested using the quasifree {sup 3}He({sup 6}Li,{alpha}{alpha})H and {sup 3}He({sup 7}Li,{alpha}{alpha}){sup 2}H reactions. The cross sections for the {sup 6}Li(d,{alpha}){sup 4}He and {sup 7}Li(p,{alpha}){sup 4}He binary processes were extracted in the framework of the plane wave approximation. They are compared with direct behaviors as well as with cross sections extracted from previous indirect investigations of the same binary reactions using deuteron as the Trojan horse nucleus instead of {sup 3}He. The very good agreement confirms the applicability of the plane wave approximation which suggests the independence of the binary indirect cross section on the chosen Trojan horse nucleus, at least for the investigated cases.

  1. First detection and energy measurement of recoil ions following beta decay in a Penning trap with the WITCH experiment

    NASA Astrophysics Data System (ADS)

    Beck, M.; Coeck, S.; Kozlov, V. Yu.; Breitenfeldt, M.; Delahaye, P.; Friedag, P.; Glück, F.; Herbane, M.; Herlert, A.; Kraev, I. S.; Mader, J.; Tandecki, M.; Van Gorp, S.; Wauters, F.; Weinheimer, Ch.; Wenander, F.; Severijns, N.

    2011-03-01

    The WITCH experiment (Weak Interaction Trap for CHarged particles) will search for exotic interactions by investigating the β - ν angular correlation via the measurement of the recoil energy spectrum after β -decay. As a first step the recoil ions from the β-_{} -decay of 124In stored in a Penning trap have been detected. The evidence for the detection of recoil ions is shown and the properties of the ion cloud that forms the radioactive source for the experiment in the Penning trap are presented.

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

    PubMed Central

    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

  3. An experimental analysis of the contribution of 224Ra and 226Ra and progeny to the gross alpha-particle activity of water samples.

    PubMed

    Arndt, Michael F; West, Lynn E

    2008-05-01

    The gross alpha-particle activity of water samples analyzed by EPA Method 900.0 is investigated as a function of residue mass and geometry, time between sample collection and analysis, and time between sample preparation and analysis for samples containing 224Ra, 212Pb, and 226Ra. It is shown that the gross alpha-particle activity due to 224Ra and its progeny can be up to 10 times the 224Ra activity at collection time and that due to 212Pb progeny can be up to 3 times the 212Pb activity at collection time. In samples with roughly equal activities of 224Ra and 226Ra analyzed soon after collection, it is shown that the gross alpha-particle activity is approximately constant with time because the decay of 224Ra and its progeny is offset by the ingrowth of 226Ra progeny. PMID:18403967

  4. Improvements of the DRAGON recoil separator at ISAC

    NASA Astrophysics Data System (ADS)

    Vockenhuber, C.; Buchmann, L.; Caggiano, J.; Chen, A. A.; D'Auria, J. M.; Davis, C. A.; Greife, U.; Hussein, A.; Hutcheon, D. A.; Ottewell, D.; Ouellet, C. O.; Parikh, A.; Pearson, J.; Ruiz, C.; Ruprecht, G.; Trinczek, M.; Zylberberg, J.

    2008-10-01

    The DRAGON (Detector of Recoils And Gammas Of Nuclear reactions) is used to measure radiative proton and alpha capture reaction rates involving both stable and radioactive, heavy-ion reactants at the TRIUMF-ISAC high intensity radioactive beam facility. Completed in 2001 it has been used for several challenging studies for nuclear astrophysics, e.g. 12C(α, γ)16O, 21Na(p, γ)22Mg, 26gAl(p, γ)27Si and 40Ca(α, γ)44Ti. Since initial operation, a number of improvements have been incorporated which are described here. These include a beam centering monitor based on a CCD camera, a mechanical iris to skim of beam halo, a solid state stripper acting as a charge state booster for beams with A ≳ 30, beta and gamma detectors to monitor beam intensity and to determine beam contamination in experiments with radioactive beam and the ionization chamber for both recoil identification and isobar separation.

  5. Relative Biological Effectiveness of Alpha-Particle Emitters In Vivo at Low Doses

    PubMed Central

    Howell, Roger W.; Azure, Michael T.; Narra, Venkat R.; Rao, Dandamudi V.

    2012-01-01

    The therapeutic potential of radionuclides that emit α 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 α and β 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 α particles emitted by tissue-incorporated radionuclides: RBEα = 4.8 − 6.1 × 10−2 LET + 1.0 × 10−3 LET2. Similarly, the dependence of RBE on α-particle energy Eα was given by RBEα=22Eα−0.73. These relationships, based on in vivo experimental data, may be valuable in predicting biological effects of α-particle emitters. PMID:8146279

  6. 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.

  7. 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

  8. Elastic recoil changes in early emphysema.

    PubMed Central

    Silvers, G W; Petty, T L; Stanford, R E

    1980-01-01

    An attempt was made to determine if emphysema and static lung recoil were related in a group of 65 excised human lungs. We studied 23 normal lungs, 24 lungs with an emphysema score of 5 or less, and 18 lungs with an emphysema score greater than 5. A comparison of the percentage of predicted elastic recoil revealed that both emphysema groups were significantly different from normal lungs. In addition, the total lung capacities were significantly different between the three groups. In the group with an emphysema score greater than 5 we found a linear negative correlation between the extent of emphysema and percent of predicted elastic recoil at 90% total lung capacity (r = -0.696, p < 0.01). We found a negative correlation between the percentage of predicted elastic recoil and the lung volume (r = -0.612, p < 0.01). We conclude that a significant loss of elastic recoil and a significant increase in total lung capacity occurs in the early stages of emphysema. PMID:7434309

  9. Basic principles approach for studying nonlinear Alfven wave-alpha particle dynamics

    SciTech Connect

    Berk, H.L.; Breizman, B.N.; Pekker, M.

    1994-01-01

    An analytical model and a numerical procedure are presented which give a kinetic nonlinear description of the Alfven-wave instabilities driven by the source of energetic particles in a plasma. The steady-state and bursting nonlinear scenarios predicted by the analytical theory are verified in the test numerical simulation of the bump-on-tail instability. A mathematical similarity between the bump-on-tail problem for plasma waves and the Alfven wave problem gives a guideline for the interpretation of the bursts in the wave energy and fast particle losses observed in the tokamak experiments with neutral beam injection.

  10. Channel coupling and exchange of an alpha-particle cluster in deuteron scattering on {sup 6}Li nuclei

    SciTech Connect

    Sakuta, S. B.; Burtebaev, N.; Artemov, S. V.; Yarmukhamedov, R.

    2012-07-15

    Existing experimental data on elastic and inelastic deuteron scattering on {sup 6}Li nuclei in the energy range from 8 to 50 MeV were analyzed within the approach of coupled reaction channels. The coupling of elastic scattering and inelastic scattering accompanied by the transition to the 3{sup +} state at E{sub x} 2.186 MeV and the mechanism involving the exchange of an alpha-particle cluster were taken into account in respective calculations. The phenomenological potentials obtained from the present analysis describe well experimental angular distributions at all energies and in full angular ranges. The depths of the real and imaginary parts of the potentials in question depend smoothly on energy at fixed values of the remaining parameters. The energy dependence of relevant volume integrals agrees well with similar data for the p + {sup 6}Li, {alpha} + {sup 6}Li, and {sup 12}C + {sup 12}C systems and with the predictions of a microscopic theory.

  11. Development of a strongly focusing high-intensity He(+) ion source for a confined alpha particle measurement at ITER.

    PubMed

    Kisaki, M; Shinto, K; Kobuchi, T; Okamoto, A; Kitajima, S; Sasao, M; Tsumori, K; Nishiura, M; Kaneko, O; Matsuda, Y; Wada, M; Sakakita, H; Kiyama, S; Hirano, Y

    2008-02-01

    A strongly focusing high-intensity He(+) ion source has been designed and constructed as a beam source for a high-energy He(0) beam probe system for diagnosis of fusion produced alpha particles in the thermonuclear fusion plasmas. The He(+) beam was extracted from the ion source at an acceleration voltage of 18-35 kV. Temperature distributions of the beam target were observed with an IR camera. The 1/e-holding beam profile half-width was about 15 mm at optimum perveance (Perv) of 0.03 (I(beam)=2.4 A). A beam current about 3 A was achieved at an acceleration voltage of 26.7 kV with an arc power of 10 kW (Perv=0.023). PMID:18315239

  12. 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.

  13. Role of channel coupling and deuteron-exchange mechanisms in anomalous alpha-particle scattering on {sup 6}Li

    SciTech Connect

    Sakuta, S. B.; Artemov, S.V.; Burtebaev, N.; Kerimkulov, Zh.; Novatsky, B. G.; Stepanov, D.N.; Yarmukhamedov, R.

    2009-12-15

    A unified description of existing experimental data on alpha-particle scattering by {sup 6}Li over the broad energy range from 18 to 166 MeV was obtained with allowance for channel-coupling effects and mechanisms involving the exchange of a deuteron cluster. Angular distributions were analyzed on the basis of the optical model and the coupled reaction channels method. It was shown that the inclusion of channel coupling and the contributions from one- and two-step exchangemechanismsmakes it possible to describe special features of the behavior of differential cross sections for both elastic and inelastic scattering in a full energy range. Optimum values found for the parameters of optical potentials agree with the parameters of the global potential proposed previously for nuclei in the mass region A > 12.

  14. Determination of oxygen in silicon and carbide by activation with 27.2 meV alpha particles

    NASA Technical Reports Server (NTRS)

    Dolgolenko, A. P.; Kornienko, N. D.; Lithovchenko, P. G.

    1978-01-01

    The Si sample was polished on one side, and on the other side Ni was applied chemically and soldered with Pb to a water cooled Cu substrate. Optical quartz standard was fixed from the other side. Si carbide samples were soldered to a substrated with In. The prepared samples were irradiated in a cyclotron with a 27.2 MeV alpha particle beam. The layers were removed from the Si and Si carbide samples by grinding and the positron activity of F-18(t sub 1/2 110 min) was measured by using a gamma, gamma coincidence spectrometer with two NaI(TI) crystals. For analysis of Si carbide, the activity decay curve of the samples was recorded to find the contribution of the positron activity of Cu-65(t sub 1/2 12.9 hr) which formed from Ni impurity on irradiation.

  15. 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.

  16. Disruption of prion rods generates 10-nm spherical particles having high alpha-helical content and lacking scrapie infectivity.

    PubMed Central

    Riesner, D; Kellings, K; Post, K; Wille, H; Serban, H; Groth, D; Baldwin, M A; Prusiner, S B

    1996-01-01

    An abnormal isoform of the prion protein (PrP) designated PrPSc is the major, or possibly the only, component of infectious prions. Structural studies of PrPSc have been impeded by its lack of solubility under conditions in which infectivity is retained. Among the many detergents examined, only treatment with the ionic detergent sodium dodecyl sulfate (SDS) or Sarkosyl followed by sonication dispersed prion rods which are composed of PrP 27-30, an N-terminally truncated form of PrPSc. After ultracentrifugation at 100,000 x g for 1 h, approximately 30% of the PrP 27-30 and scrapie infectivity were found in the supernatant, which was fractionated by sedimentation through 5 to 20% sucrose gradients. Near the top of the gradient, spherical particles with an observed sedimentation coefficient of approximately 6S, approximately 10 mm in diameter and composed of four to six PrP 27-30 molecules, were found. The spheres could be digested with proteinase K and exhibited little, if any, scrapie infectivity. When the prion rods were disrupted in SDS and the entire sample was fractionated by sucrose gradient centrifugation, a lipid-rich fraction at the meniscus composed of fragments of rods and heterogeneous particles containing high levels of prion infectivity was found. Fractions adjacent to the meniscus also contained spherical particles. Circular dichroism of the spheres revealed 60% alpha-helical content; addition of 25% acetonitrile induced aggregates high in beta sheet but remaining devoid of infectivity. Although the highly purified spherical oligomers of PrP 27-30 lack infectivity, they may provide an excellent substrate for determining conditions of renaturation under which prion particles regain infectivity. PMID:8627692

  17. Scenarios for the nonlinear evolution of alpha particle induced Alfven wave instability

    SciTech Connect

    Berk, H.L.; Breizman, B.N.; Ye, Huanchun.

    1992-03-01

    Various nonlinear scenarios are given for the evolution of energetic particles that are slowing down in a background plasma and simultaneously causing instability of the background plasma waves. If the background damping is sufficiently weak, a steady-state wave is established as described by Berk and Breizman. For larger background damping rate pulsations develop. Saturation occurs when the wave amplitude rises to where the wave trapping frequency equals the growth rate. The wave then damps due to the small background dissipation present and a relatively long quiet interval exists between bursts while the free energy of the distribution is refilled by classical transport. In this scenario the anomalous energy loss of energetic particles due to diffusion is small compared to the classical collisional energy exchange with the background plasma. However, if at the trapping frequency, the wave amplitude is large enough to cause orbit stochasticity, a phase space explosion'' occurs where the wave amplitudes rise to higher levels which leads to rapid loss of energetic particles.

  18. Scenarios for the nonlinear evolution of alpha particle induced Alfven wave instability

    SciTech Connect

    Berk, H.L.; Breizman, B.N.; Ye, Huanchun

    1992-03-01

    Various nonlinear scenarios are given for the evolution of energetic particles that are slowing down in a background plasma and simultaneously causing instability of the background plasma waves. If the background damping is sufficiently weak, a steady-state wave is established as described by Berk and Breizman. For larger background damping rate pulsations develop. Saturation occurs when the wave amplitude rises to where the wave trapping frequency equals the growth rate. The wave then damps due to the small background dissipation present and a relatively long quiet interval exists between bursts while the free energy of the distribution is refilled by classical transport. In this scenario the anomalous energy loss of energetic particles due to diffusion is small compared to the classical collisional energy exchange with the background plasma. However, if at the trapping frequency, the wave amplitude is large enough to cause orbit stochasticity, a phase space ``explosion`` occurs where the wave amplitudes rise to higher levels which leads to rapid loss of energetic particles.

  19. A new real-time method for determining particles' sphericity and density: application to secondary organic aerosol formed by ozonolysis of alpha-pinene.

    PubMed

    Zelenyuk, Alla; Yang, Juan; Song, Chen; Zaveri, Rahul A; Imre, Dan

    2008-11-01

    Particle volumes are most often obtained by measuring particle mobility size distributions and assuming that the particles are spherical. Particle volumes are then converted to mass loads by using particle densities that are commonly estimated from measured mobility and vacuum aerodynamic diameters, assuming that the particles are spherical. For aspherical particles, these assumptions can introduce significant errors. We present in this work a new method that can be applied to any particle system to determine in real time whether the particles are spherical or not. We use our second-generation single particle mass spectrometer (SPLAT II) to measure with extremely high precision the vacuum aerodynamic size distributions of particles that are classified by differential mobility analyzer and demonstrate that the line shape of these vacuum aerodynamic size distributions provide a way to unambiguously distinguish between spherical and aspherical particles. Moreover, the very same experimental system is used to obtain the size, density, composition, and dynamic shape factors of individual particles. We present an application of this method to secondary organic aerosols that are formed as a result of ozonolysis of alpha-pinene in the presence and absence of an OH scavenger and find these particles to be spherical with densities of 1.198 +/- 0.004 and 1.213 +/- 0.003 g cm(-3), respectively. PMID:19031898

  20. Targeting Aberrant DNA double strand break repair in triple negative breast cancer with alpha particle emitter radiolabeled anti-EGFR antibody

    PubMed Central

    Song, Hong; Hedayati, Mohammad; Hobbs, Robert F.; Shao, Chunbo; Bruchertseifer, Frank; Morgenstern, Alfred; DeWeese, Theodore L.; Sgouros, George

    2013-01-01

    The higher potential efficacy of alpha-particle radiopharmaceutical therapy lies in the 3 to 8-fold greater biological effectiveness (RBE) of alpha particles relative to photon or beta-particle radiation. This greater RBE, however, also applies to normal tissue, thereby reducing the potential advantage of high RBE. Since alpha particles typically cause DNA double strand breaks (DSBs), targeting tumors that are defective in DSB repair effectively increases the RBE, yielding a secondary, RBE-based differentiation between tumor and normal tissue that is complementary to conventional, receptor-mediated tumor targeting. In some triple negative breast cancers (TNBC, ER−/PR−/HER-2−), germline mutation in BRCA-1, a key gene in homologous recombination (HR) DSB repair, predisposes patients to early onset of breast cancer. These patients have few treatment options once the cancer has metastasized. In this study, we investigated the efficacy of alpha particle emitter, 213Bi labeled anti-EGFR antibody, Cetuximab, in BRCA-1 defective TNBC. 213Bi-Cetuximab was found to be significantly more effective in the BRCA-1 mutated TNBC cell line HCC1937 than BRCA-1 competent TNBC cell MDA-MB-231. siRNA knockdown of BRCA-1 or DNA-PKcs, a key gene in non-homologous end joining (NHEJ) DSB repair pathway, also sensitized TNBC cells to 213Bi-Cetuximab. Furthermore, the small molecule inhibitor of DNA-PKcs, NU7441, sensitized BRCA-1 competent TNBC cells to alpha particle radiation. Immunofluorescent staining of γH2AX foci and comet assay confirmed that enhanced RBE is caused by impaired DSB repair. These data offer a novel strategy for enhancing conventional receptor-mediated targeting with an additional, potentially synergistic radiobiological targeting that could be applied to TNBC. PMID:23873849

  1. 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.

  2. Experimental Concept for a Precision Measurement of Nuclear Recoil Ionization Yields for Low Mass WIMP Searches

    NASA Astrophysics Data System (ADS)

    Saab, T.; Figueroa-Feliciano, E.

    2016-07-01

    Understanding the response of dark matter detectors at the lowest recoil energies is important for correctly interpreting data from current experiments or predicting the sensitivity of future experiments to low mass weakly interacting massive particles. In particular, the ionization yield is essential for determining the correct recoil energy of candidate nuclear recoil events; however, few measurements in cryogenic crystals exist below 1 keV. Using the voltage-assisted calorimetric ionization detection technique with a mono-energetic neutron source, we show that it is possible to determine the ionization yield in cryogenic crystals down to an energy to 100 eV. This measurement will also determine the statistics of ionization production at these low energies.

  3. Mitochondrial alteration in malignantly transformed human small airway epithelial cells induced by alpha particles

    PubMed Central

    Zhang, Suping; Wen, Gengyun; Huang, Sarah XL; Wang, Jianrong; Tong, Jian; Hei, Tom K.

    2012-01-01

    Human small airway epithelial cells (SAECs) immortalized with human telomerase reverse transcriptase (h-TERT) were exposed to either a single or multiple doses of α particles. Irradiated cells showed a dose-dependent cytotoxicity and progressive neoplastic transformation phenotype. These included an increase in saturation density of growth, a greater resistance to PALA, faster anchorage-independent growth, reinforced cell invasion and c-Myc expression. In addition, the transformed cells formed progressively growing tumors upon inoculation into athymic nude mice. Specifically, α-irradiation induced damage to both mitochondrial DNA (mtDNA) and mitochondrial functions in transformed cells as evidenced by increased mtDNA copy number and common deletion, decreased oxidative phosphorylation (OXPHOS) activity as measured by cytochrome C oxidase (COX) activity and oxygen consumption. There was a linear correlation between mtDNA copy number, common deletion, COX activity and cellular transformation represented by soft agar colony formation and c-Myc expression. These results suggest that mitochondria are associated with neoplastic transformation of SAEC cells induced by α particles, and that the oncogenesis process may depend not only on the genomes inside the nucleus, but also on the mitochondrial DNA outside the nucleus. PMID:22644783

  4. Nuclear sizes of /sup 40,42,44,48/Ca from elastic scattering of 104 MeV alpha particles. I. Experimental results and optical potentials

    SciTech Connect

    Gils, H.J.; Friedman, E.; Rebel, H.; Buschmann, J.; Zagromski, S.; Klewe-Nebenius, H.; Neumann, B.; Pesl, R.; Bechtold, G.

    1980-04-01

    Differential cross sections for elastic scattering of 104 MeV ..cap alpha.. particles from /sup 40,42,44,48/Ca have been measured with high angular accuracy over a wide angular range. Optical model analysis based on a Fourier-Bessel description of the real potential reveals isotopic differences which, in particular for /sup 48/Ca, indicate a small neutron skin.

  5. Detectors for alpha particles and X-rays operating in ambient air in pulse counting mode or/and with gas amplification

    NASA Astrophysics Data System (ADS)

    Charpak, G.; Benaben, P.; Breuil, P.; Peskov, V.

    2008-02-01

    Ionization chambers working in ambient air in current detection mode are attractive due to their simplicity and low cost and are widely used in several applications such as smoke detection, dosimetry, therapeutic beam monitoring and so on. The aim of this work was to investigate if gaseous detectors can operate in ambient air in pulse counting mode as well as with gas amplification which potentially offers the highest possible sensitivity in applications like alpha particle detection or high energy X-ray photon or electron detection. To investigate the feasibility of this method two types of open- end gaseous detectors were build and successfully tested. The first one was a single wire or multiwire cylindrical geometry detector operating in pulse mode at a gas gain of one (pulse ionization chamber). This detector was readout by a custom made wide -band charge sensitive amplifier able to deal with slow induced signals generated by slow motion of negative and positive ions. The multiwire detector was able to detect alpha particles with an efficiency close to 22%. The second type of an alpha detector was an innovative GEM-like detector with resistive electrodes operating in air in avalanche mode at high gas gains (up to 104). This detector can also operate in a cascaded mode or being combined with other detectors, for example with MICROMEGAS. This detector was readout by a conventional charge -sensitive amplifier and was able to detect alpha particles with 100% efficiency. This detector could also detect X-ray photons or fast electrons. A detailed comparison between these two detectors is given as well as a comparison with commercially available alpha detectors. The main advantages of gaseous detectors operating in air in a pulse detection mode are their simplicity, low cost and high sensitivity. One of the possible applications of these new detectors is alpha particle background monitors which, due to their low cost can find wide application not only in houses, but

  6. LET-Dependent Bystander Effects Caused by Irradiation of Human Prostate Carcinoma Cells with X Rays or Alpha Particles

    PubMed Central

    Anzenberg, Vered; Chandiramani, Sarika; Coderre, Jeffrey A.

    2014-01-01

    Radiation-induced bystander effects have been demonstrated in both normal and tumor cells using a variety of different radiation qualities. Literature reports are contradictory, however, on whether there is an LET dependence of the bystander effect. This study investigated the ability of DU-145 human prostate carcinoma cells irradiated with either α particles or 250 kVp X rays to cause medium-mediated bystander effects in unirradiated populations of DU-145 cells or in AG01522 human fibroblasts. The end points measured in both of the bystander cell lines were micronucleus formation, γ-H2AX focus induction, and the surviving fraction. The incidence of micronuclei increased 1.5–2.0-fold in both tumor and fibroblast bystander cells after 4 h of co-culture with DU-145 tumor cells that had been directly irradiated with either α particles or X rays. Only the AG01522 fibroblasts showed bystander effects for the γ-H2AX focus (a 1.5-fold increase) and surviving fraction (a decrease to 0.8) end points when co-cultured with X-irradiated tumor cells. Alpha-particle irradiation of DU-145 tumor cells produced no decrease in the surviving fraction and no increase in γ-H2AX focus induction in co-cultured bystander cells of either cell line. These results indicate that there are LET-dependent differences in the signal released from DU-145 human prostate carcinoma cells and that, for some end points, bystander AG01522 fibroblasts and bystander DU-145 prostate carcinoma cells respond differently to the same medium-mediated signal. PMID:19024654

  7. Proton recoil scintillator neutron rem meter

    DOEpatents

    Olsher, Richard H.; Seagraves, David T.

    2003-01-01

    A neutron rem meter utilizing proton recoil and thermal neutron scintillators to provide neutron detection and dose measurement. In using both fast scintillators and a thermal neutron scintillator the meter provides a wide range of sensitivity, uniform directional response, and uniform dose response. The scintillators output light to a photomultiplier tube that produces an electrical signal to an external neutron counter.

  8. {alpha}-decay properties of the new neutron deficient isotope {sup 212}Pa

    SciTech Connect

    Mitsuoka, S.; Ikezoe, H.; Ikuta, T.; Nagame, Y.; Tsukada, K.; Nishinaka, I.; Oura, Y.; Zhao, Y.L.

    1997-03-01

    The new neutron deficient isotope {sup 212}Pa has been produced in the {sup 182}W({sup 35}Cl,5n) reaction at a beam energy of 182.5 MeV. Evaporation residues have been separated with the JAERI recoil mass separator and identified on the basis of time- and position-correlated {alpha}-decay chains. The {alpha} decay from the ground state of {sup 212}Pa has been observed with an {alpha}-particle energy of 8.270(30) MeV and a half-life of 5.1{sub {minus}1.9}{sup +6.1} ms. {copyright} {ital 1997} {ital The American Physical Society}

  9. Applications of 211At and 223Ra in Targeted Alpha-Particle Radiotherapy

    PubMed Central

    Vaidyanathan, Ganesan; Zalutsky, Michael R.

    2012-01-01

    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. PMID:22202151

  10. 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. PMID:22202151

  11. Readout cross-talk for alpha-particle measurements in a pixelated sensor system

    NASA Astrophysics Data System (ADS)

    Norlin, B.; Reza, S.; Krapohl, D.; Fröjdh, E.; Thungström, G.

    2015-05-01

    Simulations in Medici are performed to quantify crosstalk and charge sharing in a hybrid pixelated silicon detector. Crosstalk and charge sharing degrades the spatial and spectral resolution of single photon processing X-ray imaging systems. For typical medical X-ray imaging applications, the process is dominated by charge sharing between the pixels in the sensor. For heavier particles each impact generates a large amount of charge and the simulation seems to over predict the charge collection efficiency. This indicates that some type of non modelled degradation of the charge transport efficiency exists, like the plasma effect where the plasma might shield the generated charges from the electric field and hence distorts the charge transport process. Based on the simulations it can be reasoned that saturation of the amplifiers in the Timepix system might generate crosstalk that increases the charge spread measured from ion impact on the sensor.

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

    PubMed

    Friedland, Werner; Kundrát, Pavel

    2013-08-30

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

  13. 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

  14. Gold Coated Lanthanide Phosphate Nanoparticles for Targeted Alpha Generator Radiotherapy

    SciTech Connect

    McLaughlin, Mark F; Woodward, Jonathan; Boll, Rose Ann; Wall, Jonathan; Rondinone, Adam Justin; Kennel, Steve J; Mirzadeh, Saed; Robertson, David J.

    2013-01-01

    Targeted radiotherapies maximize cytotoxicty to cancer cells. In vivo generators such as 225Ac, which emits four particles in its decay chain, can significantly amplify the radiation dose delivered to the target site. However, renal dose from unbound 213Bi escaping during the decay process limits the dose of 225Ac that can be administered. Traditional chelating moieties are unable to sequester the radioactive daughters because of the high recoil energy from alpha particle emission. To counter this, we demonstrate that an engineered multilayered nanoparticle-antibody conjugate can both deliver radiation and contain the decay daughters of the in vivo -generator 225Ac while targeting biologically relevant receptors. These multi-shell nanoparticles combine the radiation resistance of crystalline lanthanide phosphate to encapsulate and contain 225Ac and its radioactive decay daughters, the magnetic properties of gadolinium phosphate for easy separation, and established surface chemistry of gold for attachment of nanoparticles to targeting antibodies.

  15. Design of the recoil mass separator St. George

    NASA Astrophysics Data System (ADS)

    Couder, M.; Berg, G. P. A.; Görres, J.; LeBlanc, P. J.; Lamm, L. O.; Stech, E.; Wiescher, M.; Hinnefeld, J.

    2008-03-01

    A recoil mass separator has been designed for the purpose of studying low energy (α,γ) reactions in inverse kinematics for beam masses up to about A=40. Their reaction rates are of importance for our understanding of energy production and nucleosynthesis during stellar and explosive helium burning. The reactions take place in a windowless He gas target at the beginning of the separator which consists of three sections. The first section selects the most abundant charge state. The Wien filter in the second section efficiently separates the intense beam from the few reaction products. In the last section the reaction products are focused into a detector system consisting of time pickup and energy detectors. In order to accept the complete kinematic cone of recoil particles for energies as low as reasonably possible we specified a large circular angular acceptance of ±40 mrad. This requires a careful minimization of higher-order aberrations. The present system has been designed to allow for a future upgrade to extend the experimental program to the analysis of (p,γ) reactions.

  16. Computation of cosmic ray ionization and dose at Mars. I: A comparison of HZETRN and Planetocosmics for proton and alpha particles

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  17. Cavitation Bubble Nucleation by Energetic Particles

    SciTech Connect

    West, C.D.

    1998-12-01

    In the early sixties, experimental measurements using a bubble chamber confirmed quantitatively the thermal spike theory of bubble nucleation by energetic particles: the energy of the slow, heavy alpha decay recoils used in those experiments matched the calculated bubble nucleation energy to within a few percent. It was a triumph, but was soon to be followed by a puzzle. Within a couple of years, experiments on similar liquids, but well below their normal boiling points, placed under tensile stress showed that the calculated bubble nucleation energy was an order of magnitude less than the recoil energy. Why should the theory work so well in the one case and so badly in the other? How did the liquid, or the recoil particle, "know" the difference between the two experiments? Another mathematical model of the same physical process, introduced in 1967, showed qualitatively why different analyses would be needed for liquids with high and low vapor pressures under positive or negative pressures. But, the quantitative agreement between the calculated nucleation energy and the recoil energy was still poor--the former being smaller by a factor of two to three. In this report, the 1967 analysis is extended and refined: the qualitative understanding of the difference between positive and negative pressure nucleation, "boiling" and "cavitation" respectively, is retained, and agreement between the negative pressure calculated to be needed for nucleation and the energy calculated to be available is much improved. A plot of the calculated negative pressure needed to induce bubble formation against the measured value now has a slope of 1.0, although there is still considerable scatter in the individual points.

  18. Radon and lung carcinogenesis: mutability of p53 codons 249 and 250 to 238Pu alpha-particles in human bronchial epithelial cells.

    PubMed

    Hussain, S P; Kennedy, C H; Amstad, P; Lui, H; Lechner, J F; Harris, C C

    1997-01-01

    Radon-222, a decay product of uranium-238 and a source of high linear energy transfer (LET) alpha-particles, has been implicated in the increased risk of lung cancer in uranium miners as well as non-miners. p53 mutation spectrum studies of radon-associated lung cancer have failed to show any specific mutational hot spot with the exception of a single study in which 31% of squamous cell and large cell lung cancers from uranium miners showed a p53 codon 249 AGGarg --> ATGmet mutation. Although the results of laboratory studies indicate that double-strand breaks and deletions are the principal genetic alterations caused by alpha-particles, uncertainty still prevails in the description of DNA damage in radon-associated human lung cancer. In the present study, we have evaluated the mutability of p53 codons 249 and 250 to alpha-particles in normal human bronchial epithelial (NHBE) cells using a highly sensitive genotypic mutation assay. Exposure of NHBE cells to a total dose of 4 Gy (equivalent to approximately 1460 working level months in uranium mining) of high LET alpha-radiation induced codon 249 AGG --> AAG transitions and codon 250 CCC --> ACC transversions with absolute mutation frequencies of 3.6 x 10(-7) and 3.8 x 10(-7) respectively. This mutation spectrum is consistent with our previous report of radon-associated human lung cancer. PMID:9054598

  19. Ionization and scintillation of nuclear recoils in gaseous xenon

    NASA Astrophysics Data System (ADS)

    Renner, J.; Gehman, V. M.; Goldschmidt, A.; Matis, H. S.; Miller, T.; Nakajima, Y.; Nygren, D.; Oliveira, C. A. B.; Shuman, D.; Álvarez, V.; Borges, F. I. G.; Cárcel, S.; Castel, J.; Cebrián, S.; Cervera, A.; Conde, C. A. N.; Dafni, T.; Dias, T. H. V. T.; Díaz, J.; Esteve, R.; Evtoukhovitch, P.; Fernandes, L. M. P.; Ferrario, P.; Ferreira, A. L.; Freitas, E. D. C.; Gil, A.; Gómez, H.; Gómez-Cadenas, J. J.; González-Díaz, D.; Gutiérrez, R. M.; Hauptman, J.; Hernando Morata, J. A.; Herrera, D. C.; Iguaz, F. J.; Irastorza, I. G.; Jinete, M. A.; Labarga, L.; Laing, A.; Liubarsky, I.; Lopes, J. A. M.; Lorca, D.; Losada, M.; Luzón, G.; Marí, A.; Martín-Albo, J.; Martínez, A.; Moiseenko, A.; Monrabal, F.; Monserrate, M.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Muñoz Vidal, J.; Natal da Luz, H.; Navarro, G.; Nebot-Guinot, M.; Palma, R.; Pérez, J.; Pérez Aparicio, J. L.; Ripoll, L.; Rodríguez, A.; Rodríguez, J.; Santos, F. P.; dos Santos, J. M. F.; Seguí, L.; Serra, L.; Simón, A.; Sofka, C.; Sorel, M.; Toledo, J. F.; Tomás, A.; Torrent, J.; Tsamalaidze, Z.; Veloso, J. F. C. A.; Villar, J. A.; Webb, R. C.; White, J.; Yahlali, N.

    2015-09-01

    Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope α-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

  20. Calibration of a Thomson parabola ion spectrometer and Fujifilm imaging plates for energetic protons, deuterons, and alpha particles

    NASA Astrophysics Data System (ADS)

    Freeman, Charles; Canfield, Michael; Graeper, Gavin; Lombardo, Andrew; Stillman, Collin; Fiksel, Gennady; Stoeckl, Christian; Sinenian, Nareg

    2010-11-01

    A Thomson parabola ion spectrometer (TPIS) has been designed and built to study energetic ions accelerated from the rear surface of targets irradiated by ultra-intense laser light from the Multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE). The device uses a permanent magnet and a pair of electrostatic deflector plates to produce parallel magnetic and electric fields, which cause ions of a given charge-to-mass ratio to be deflected onto parabolic curves on the detector plane. The position of the ion along the parabola can be used to determine its energy. Fujifilm imaging plates (IP) are placed in the rear of the device and are used to detect the incident ions. The energy dispersion of the spectrometer has been calibrated using monoenergetic ion beams from the SUNY Geneseo 1.7 MV pelletron accelerator. The IP sensitivity has been measured for protons and deuterons with energies between 0.6 MeV and 3.4 MeV, and for alpha particles with energies between 1.5 MeV and 5.1 MeV.

  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. 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.

  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. Alpha-particle and proton probes of nuclear shapes in the rare earth and mass 80 regions

    SciTech Connect

    Sarantites, D.G.; Nicolis, N.G.; Abenante, V.; Majka, Z.; Semkow, T.M.; Baktash, C.; Beene, J.R.; Garcia-Bermudez, G.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Virtanen, A.; Griffin, H.C.; Oak Ridge National Lab., TN; Michigan Univ., Ann Arbor, MI )

    1989-01-01

    Low emission barriers and large subbarrier anisotropies in the alpha-particle decay with respect to the spin direction, of Sn and rare earth compound nuclei, are examined in the light of recent calculations incorporating deformation. To explore the possibility of a correlation between the proton emission barriers and nuclear deformation, we studied proton spectra from the {sup 52}Cr({sup 34}S,2p2n){sup 82}Sr reaction. The proton spectra were observed with the Dwarf-Ball 4{pi} CsI(Tl) array, in coincidence with 18 Compton suppressed Ge detectors operated in conjunction with the Spin Spectrometer, a 4{pi} NaI(Tl) array. We found significant changes and shifts in the proton energy spectra as we selected gating transitions from bands of different moments of inertia or transitions from states of different spin in the same band. Substantial differences were also seen as a function of the {gamma}-ray multiplicity. These results are discussed in terms of statistical model calculations incorporating deformation and structure effects of the emitting system. 20 refs., 9 figs.

  5. Low energy nuclear recoils study in noble liquids for low-mass WIMPs

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Mei, Dongming

    2014-03-01

    Detector response to low-energy nuclear recoils is critical to the detection of low-mass dark matter particles-WIMPs (Weakly interacting massive particles). Although the detector response to the processes of low-energy nuclear recoils is subtle and direct experimental calibration is rather difficult, many studies have been performed for noble liquids, NEST is a good example. However, the response of low-energy nuclear recoils, as a critical issue, needs more experimental data, in particular, with presence of electric field. We present a new design using time of flight to calibrate the large-volume xenon detector, such as LUX-Zeplin (LZ) and Xenon1T, energy scale for low-energy nuclear recoils. The calculation and physics models will be discussed based on the available data to predict the performance of the calibration device and set up criteria for the design of the device. A small test bench is built to verify the concepts at The University of South Dakota. This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota.

  6. Development of bubble chambers with enhanced stability and sensitivity to low-energy nuclear recoils

    SciTech Connect

    Bolte, W.J.; Collar, Juan I.; Crisler, M.; Hall, J.; Holmgren, D.; Nakazawa, D.; Odom, B.; O'Sullivan, K.; Plunkett, R.; Ramberg, E.; Raskin, A.; Sonnenschein, A.; Vieira, J.D.; /Chicago U., EFI /KICP, Chicago /Fermilab

    2005-03-01

    The viability of using a Bubble Chamber for rare event searches and in particular for the detection of dark matter particle candidates is considered. Techniques leading to the deactivation of inhomogeneous nucleation centers and subsequent enhanced stability in such a detector are described. Results from prototype trials indicate that sensitivity to low-energy nuclear recoils like those expected from Weakly Interacting Massive Particles can be obtained in conditions of near total insensitivity to minimum ionizing backgrounds. An understanding of the response of superheated heavy refrigerants to these recoils is demonstrated within the context of existing theoretical models. We comment on the prospects for the detection of supersymmetric dark matter particles with a large CF{sub 3}I chamber.

  7. 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.

  8. Einstein-Bohr recoiling double-slit gedanken experiment performed at the molecular level

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Jing; Miao, Quan; Gel'Mukhanov, Faris; Patanen, Minna; Travnikova, Oksana; Nicolas, Christophe; Ågren, Hans; Ueda, Kiyoshi; Miron, Catalin

    2015-02-01

    Double-slit experiments illustrate the quintessential proof for wave-particle complementarity. If information is missing about which slit the particle has traversed, the particle, behaving as a wave, passes simultaneously through both slits. This wave-like behaviour and corresponding interference is absent if ‘which-slit’ information exists. The essence of Einstein-Bohr's debate about wave-particle duality was whether the momentum transfer between a particle and a recoiling slit could mark the path, thus destroying the interference. To measure the recoil of a slit, the slits should move independently. We showcase a materialization of this recoiling double-slit gedanken experiment by resonant X-ray photoemission from molecular oxygen for geometries near equilibrium (coupled slits) and in a dissociative state far away from equilibrium (decoupled slits). Interference is observed in the former case, while the electron momentum transfer quenches the interference in the latter case owing to Doppler labelling of the counter-propagating atomic slits, in full agreement with Bohr's complementarity.

  9. 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.

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

    SciTech Connect

    Darrow, D. S.; Cecil, F. E.; Kiptily, V.; Fullard, K.; Horton, A.; Collaboration: JET EFDA Contributors

    2010-10-15

    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 {approx}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.

  11. Measurements of nuclear {gamma}-ray line emission in interactions of protons and {alpha} particles with N, O, Ne, and Si

    SciTech Connect

    Benhabiles-Mezhoud, H.; Kiener, J.; Thibaud, J.-P.; Tatischeff, V.; Deloncle, I.; Coc, A.; Duprat, J.; Hamadache, C.; Lefebvre-Schuhl, A.; Dalouzy, J.-C.; Grancey, F. de; Oliveira, F. de; Dayras, F.; Sereville, N. de; Pellegriti, M.-G.; Lamia, L.; Ouichaoui, S.

    2011-02-15

    {gamma}-ray production cross sections have been measured in proton irradiations of N, Ne, and Si and {alpha}-particle irradiations of N and Ne. In the same experiment we extracted also line shapes for strong {gamma}-ray lines of {sup 16}O produced in proton and {alpha}-particle irradiations of O. For the measurements gas targets were used for N, O, and Ne and a thick foil for Si. All targets were of natural isotopic composition. Beams in the energy range up to 26 MeV for protons and 39 MeV for {alpha} particles were delivered by the Institut de Physique Nucleaire-Orsay tandem accelerator. The {gamma} rays were detected with four high-purity Ge detectors in the angular range 30 deg. to 135 deg. We extracted 36 cross-section excitation functions for proton reactions and 14 for {alpha}-particle reactions. For the majority of the excitation functions no other data exist to our knowledge. Where comparison with existing data was possible, usually a very good agreement was found. It is shown that these data are very interesting for constraining nuclear reaction models. In particular, the agreement of cross section calculations in the nuclear reaction code talys with the measured data could be improved by adjusting the coupling schemes of collective levels in the target nuclei {sup 14}N, {sup 20,22}Ne, and {sup 28}Si. The importance of these results for the modeling of nuclear {gamma}-ray line emission in astrophysical sites is discussed.

  12. 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).

  13. 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.

  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. Monte Carlo Simulation of the DRAGON Recoil Mass Spectrometer End Detectors

    NASA Astrophysics Data System (ADS)

    Veloce, Laurelle; Fallis, J.; Ruiz, C.; Reeve, S.

    2010-11-01

    DRAGON (Detector of Recoils And Gammas Of Nuclear reactions), located at TRIUMF in Vancouver, BC, is designed to study radiative capture reactions relevant in astrophysical nucleosynthesis processes. These types of reactions help us understand the production of heavy elements in the Universe. An accelerated beam of a given isotope is sent through a gas target where the reactions take place. Magnetic and electrostatic dipoles separate the recoils from the original beam particles, selecting particles according to charge and mass. The products of the nuclear reactions are then detected at the end of DRAGON by heavy ion detectors, which constitute two micro channel plate (MCP) detectors for time of flight measurements, used in conjunction with a Double Sided Silicon Strip Detector (DSSSD) or an ionization chamber (IC). The DSSSD gives information on number of counts, total energy deposited, and position while the IC measures the number of counts and the energy deposited as the particle travels through the chamber. In order to determine which set up is ideal for a given reaction and energy range, we have developed a Monte Carlo simulation of these end detectors. The program simulates both recoil and beam particles, and takes into account effects such as straggling and pulse height defect. Reaction kinematics in the gas target are also considered. Comparisons to recent experimental data will be discussed.

  16. The atmosphere of comet 67P/Churyumov-Gerasimenko diagnosed by charge-exchanged solar wind alpha particles

    NASA Astrophysics Data System (ADS)

    Simon Wedlund, C.; Kallio, E.; Alho, M.; Nilsson, H.; Stenberg Wieser, G.; Gunell, H.; Behar, E.; Pusa, J.; Gronoff, G.

    2016-03-01

    Context. The ESA/Rosetta mission has been orbiting comet 67P/Churyumov-Gerasimenko since August 2014, measuring its dayside plasma environment. The ion spectrometer onboard Rosetta has detected two ion populations, one energetic with a solar wind origin (H+, He2+, He+), the other at lower energies with a cometary origin (water group ions such as H2O+). He+ ions arise mainly from charge-exchange between solar wind alpha particles and cometary neutrals such as H2O. Aims: The He+ and He2+ ion fluxes measured by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA) give insight into the composition of the dayside neutral coma, into the importance of charge-exchange processes between the solar wind and cometary neutrals, and into the way these evolve when the comet draws closer to the Sun. Methods: We combine observations by the ion spectrometer RPC-ICA onboard Rosetta with calculations from an analytical model based on a collisionless neutral Haser atmosphere and nearly undisturbed solar wind conditions. Results: Equivalent neutral outgassing rates Q can be derived using the observed RPC-ICA He+/He2+ particle flux ratios as input into the analytical model in inverse mode. A revised dependence of Q on heliocentric distance Rh in AU is found to be Rh-7.06 between 1.8 and 3.3 AU, suggesting that the activity in 2015 differed from that of the 2008 perihelion passage. Conversely, using an outgassing rate determined from optical remote sensing measurements from Earth, the forward analytical model results are in relatively good agreement with the measured RPC-ICA flux ratios. Modelled ratios in a 2D spherically-symmetric plane are also presented, showing that charge exchange is most efficient with solar wind protons. Detailed cometocentric profiles of these ratios are also presented. Conclusions: In conclusion, we show that, with the help of a simple analytical model of charge-exchange processes, a mass-capable ion spectrometer such as RPC-ICA can be used as a

  17. Analysis of the miRNA-mRNA networks in malignant transformation BEAS-2B cells induced by alpha-particles.

    PubMed

    Nie, Ji-Hua; Chen, Zhi-Hai; Shao, Chun-Lin; Pei, Wei-Wei; Zhang, Jie; Zhang, Shu-Yu; Jiao, Yang; Tong, Jian

    2016-01-01

    The aim of this study was to determine the toxicity induced by irradiation with alpha-particles on malignant transformation of immortalized human bronchial epithelial cells (BEAS-2B) using miRNA-mRNA networks. The expression of BEAS-2B cells was determined by measuring colony formation, mtDNA, mitochondrial membrane potential (MMP), and ROS levels. Changes in BEAS-2B cell gene expression were observed and quantified using microarrays that included an increase in 157 mRNA and 20 miRNA expression and a decrease in 77 mRNA and 48 miRNA. Bioinformatic software was used to analyze these different mRNA and miRNA, which indicated that miR-107 and miR-494 play an important role in alpha-particles-mediated cellular malignant transformation processes. The pathways related to systemic lupus erythematosus, cytokine-cytokine receptor interaction, MAPK signaling pathway, regulation of actin cytoskeleton, and cell adhesion molecules (CAMs) were stimulated, while those of ribosome, transforming growth factor (TGF)-beta signaling pathway, and metabolic pathways were inhibited. Data suggest that miRNA and mRNA play a crucial role in alpha-particles-mediated malignant transformation processes. It is worth noting that three target genes associated with lung cancer were identified and upregulated PEG 10 (paternally expressed gene 10), ARHGAP26, and IRS1. PMID:27267825

  18. Comprehensive evaluation of the linear stability of Alfvén eigenmodes driven by alpha particles in an ITER baseline scenario

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    The linear stability of Alfvén eigenmodes in the presence of fusion-born alpha particles is thoroughly assessed for two variants of an ITER baseline scenario, which differ significantly in their core and pedestal temperatures. A systematic approach based on CASTOR-K (Borba and Kerner 1999 J. Comput. Phys. 153 101; Nabais et al 2015 Plasma Sci. Technol. 17 89) is used that considers all possible eigenmodes for a given magnetic equilibrium and determines their growth rates due to alpha-particle drive and Landau damping on fuel ions, helium ashes and electrons. It is found that the fastest growing instabilities in the aforementioned ITER scenario are core-localized, low-shear toroidal Alfvén eigenmodes. The largest growth-rates occur in the scenario variant with higher core temperatures, which has the highest alpha-particle density and density gradient, for eigenmodes with toroidal mode numbers n≈ 30 . Although these eigenmodes suffer significant radiative damping, which is also evaluated, their growth rates remain larger than those of the most unstable eigenmodes found in the variant of the ITER baseline scenario with lower core temperatures, which have n≈ 15 and are not affected by radiative damping.

  19. Utilization of wavelength-shifting fibers coupled to ZnS(Ag) and plastic scintillator for simultaneous detection of alpha/beta particles

    NASA Astrophysics Data System (ADS)

    Ifergan, Y.; Dadon, S.; Israelashvili, I.; Osovizky, A.; Gonen, E.; Yehuda-Zada, Y.; Smadja, D.; Knafo, Y.; Ginzburg, D.; Kadmon, Y.; Cohen, Y.; Mazor, T.

    2015-06-01

    Low level radioactive surface contamination measurements require lightweight, large area and high efficiency detector. In most existing scintillation detectors there is a tradeoff between effective area and scintillation light collection. By using wavelength shifting (WLS) fibers the scintillation light may be collected efficiently also in a large area detector. In this study, WLS fibers were coupled to a beta sensitive plastic scintillator layer and to a alpha sensitive silver-activated zinc sulfide ZnS(Ag) layer for detecting both alpha and beta particles. The WLS fibers collect the scintillation light from the whole detector and transfer it to a single PMT. This first prototype unique configuration enables monitoring radioactive contaminated surfaces by both sides of the detector and provides high gamma rejection. In this paper, the detector structure, as well as the detector's measured linear response, will be described. The measured detection efficiency of 238Pu alpha particles (5.5 MeV) is ~63%. The measured detection efficiency for beta particles is ~89% for 90Sr-90Y (average energy of 195.8 keV, 934.8 keV), ~50% for 36Cl (average energy of 251.3 keV), and 35% for 137Cs (average energy of 156.8 keV).

  20. 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

  1. Measurement of Nuclear Recoils in the CDMS II Dark Matter Search

    SciTech Connect

    Fallows, Scott Mathew

    2014-12-01

    The Cryogenic Dark Matter Search (CDMS) experiment is designed to directly detect elastic scatters of weakly-interacting massive dark matter particles (WIMPs), on target nuclei in semiconductor crystals composed of Si and Ge. These scatters would occur very rarely, in an overwhelming background composed primarily of electron recoils from photons and electrons, as well as a smaller but non-negligible background of WIMP-like nuclear recoils from neutrons. The CDMS II generation of detectors simultaneously measure ionization and athermal phonon signals from each scatter, allowing discrimination against virtually all electron recoils in the detector bulk. Pulse-shape timing analysis allows discrimination against nearly all remaining electron recoils taking place near detector surfaces. Along with carefully limited neutron backgrounds, this experimental program allowed for \\background- free" operation of CDMS II at Soudan, with less than one background event expected in each WIMP-search analysis. As a result, exclusionary upper-limits on WIMP-nucleon interaction cross section were placed over a wide range of candidate WIMP masses, ruling out large new regions of parameter space.

  2. 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. PMID:22728838

  3. Alpha-physics and measurement requirements for ITER

    SciTech Connect

    Zweben, S.J.; Young, K.M.; Putvinski, S.; Petrov, M.P.; Sadler, G.; Tobita, K.

    1995-12-31

    This paper reviews alpha particle physics issues in ITER and their implications for alpha particle measurements. A comparison is made between alpha heating in ITER and NBI and ICRH heating systems in present tokamaks, and alpha particle issues in ITER are discussed in three physics areas: `single particle` alpha effects, `collective` alpha effects, and RF interactions with alpha particles. 29 refs., 4 figs., 4 tabs.

  4. Thermal recoil force, telemetry, and the Pioneer anomaly

    SciTech Connect

    Toth, Viktor T.; Turyshev, Slava G.

    2009-02-15

    Precision navigation of spacecraft requires accurate knowledge of small forces, including the recoil force due to anisotropies of thermal radiation emitted by spacecraft systems. We develop a formalism to derive the thermal recoil force from the basic principles of radiative heat exchange and energy-momentum conservation. The thermal power emitted by the spacecraft can be computed from engineering data obtained from flight telemetry, which yields a practical approach to incorporate the thermal recoil force into precision spacecraft navigation. Alternatively, orbit determination can be used to estimate the contribution of the thermal recoil force. We apply this approach to the Pioneer anomaly using a simulated Pioneer 10 Doppler data set.

  5. Variation in RBE for Survival of V79-4 Cells as a Function of Alpha-Particle (Helium Ion) Energy.

    PubMed

    Tracy, Bliss L; Stevens, David L; Goodhead, Dudley T; Hill, Mark A

    2015-07-01

    High linear energy transfer (LET) α particles are important with respect to the carcinogenic risk associated with human exposure to ionizing radiation, most notably to radon and its progeny. Additionally, the potential use of alpha-particle-emitting radionuclides in radiotherapy is increasingly being explored. Within the body the emitted alpha particles slow down, traversing a number of cells with a range of energies and therefore with varying efficiencies at inducing biological response. The LET of the particle typically rises from between ~70-90 keV μm(-1) at the start of the track (depending on initial energy) to a peak of ~237 keV μm(-1) towards the end of the track, before falling again at the very end of its range. To investigate the variation in biological response with incident energy, a plutonium-238 alpha-particle irradiator was calibrated to enable studies with incident energies ranging from 4.0 MeV down to 1.1 MeV. The variation in clonogenic survival of V79-4 cells was determined as a function of incident energy, along with the relative variation in the initial yields of DNA double-strand breaks (DSB) measured using the FAR assay. The clonogenic survival data also extends previously published data obtained at the Medical Research Council (MRC), Harwell using the same cells irradiated with helium ions, with energies ranging from 34.9 MeV to 5.85 MeV. These studies were performed in conjunction with cell morphology measurements on live cells enabling the determination of absorbed dose and calculation of the average LET in the cell. The results show an increase in relative biological effectiveness (RBE) for cell inactivation with decreasing helium ion energy (increasing LET), reaching a maximum for incident energies of ~3.2 MeV and corresponding average LET of 131 keV μm(-1), above which the RBE is observed to fall at lower energies (higher LETs). The effectiveness of single alpha-particle traversals (relevant to low-dose exposure) at inducing cell

  6. Moving towards first science with the St. George recoil separator

    NASA Astrophysics Data System (ADS)

    Meisel, Zachary; Berg, G. P. A.; Gilardy, G.; Moran, M.; Schmitt, J.; Seymour, C.; Stech, E.; Couder, M.

    2015-10-01

    The St. George recoil mass separator has recently been coupled to the 5MV St. Ana accelerator at the University of Notre Dame's Nuclear Science Lab. St. George is a unique tool designed to measure radiative alpha-capture reactions for nuclei up to A = 40 in inverse kinematics in order to directly obtain cross sections required for astrophysical models of stellar and explosive helium burning. Commissioning of St. George is presently taking place with primary beams of hydrogen, helium, and oxygen. In this presentation, results will be shown for the measured energy acceptance of St. George, which compare favorably to COSY results when employing the calculated optimal ion-optical settings. Additionally, future plans will be discussed, such as assessing the angular acceptance of St. George and the re-integration of HiPPO at the separator target position to provide a dense, windowless helium gas-jet target. The material presented in this work is partially supported by the National Science Foundation Grant No. 1419765.

  7. Isotopic and isotonic differences between. cap alpha. particle optical potentials and nuclear densities of 1f/sub 7/2/ nuclei

    SciTech Connect

    Gils, H.J.; Rebel, H.; Friedman, E.

    1984-04-01

    The elastic scattering of 104 MeV ..cap alpha.. particles by /sup 40,42,43,44,48/Ca, /sup 50/Ti, /sup 51/V, and /sup 52/Cr has been analyzed by phenomenological and semimicroscopic optical potentials in order to get information on isotopic and isotonic differences of the ..cap alpha.. particle optical potentials and of nuclear matter densities. The phenomenological optical potentials based on a Fourier-Bessel description of the real part reveal different behavior in size and shape for the isotonic chain as compared to the isotopic chain. Odd-even effects are also indicated to be different for isotones and isotopes. The semimicroscopic analyses use a single-folding model with a density-dependent effective ..cap alpha..N interaction including a realistic local density approximation. The calculated potentials are fully consistent with the phenomenological ones. Isotopic and isotonic differences of the nuclear matter densities obtained from the folding model in general show a similar behavior as the optical potential differences. The results on matter densities are compared to other investigations.

  8. 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

  9. Ab initio alpha-alpha scattering.

    PubMed

    Elhatisari, Serdar; Lee, Dean; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A; Luu, Thomas; Meißner, Ulf-G

    2015-12-01

    Processes such as the scattering of alpha particles ((4)He), the triple-alpha reaction, and alpha capture play a major role in stellar nucleosynthesis. In particular, alpha capture on carbon determines the ratio of carbon to oxygen during helium burning, and affects subsequent carbon, neon, oxygen, and silicon burning stages. It also substantially affects models of thermonuclear type Ia supernovae, owing to carbon detonation in accreting carbon-oxygen white-dwarf stars. In these reactions, the accurate calculation of the elastic scattering of alpha particles and alpha-like nuclei--nuclei with even and equal numbers of protons and neutrons--is important for understanding background and resonant scattering contributions. First-principles calculations of processes involving alpha particles and alpha-like nuclei have so far been impractical, owing to the exponential growth of the number of computational operations with the number of particles. Here we describe an ab initio calculation of alpha-alpha scattering that uses lattice Monte Carlo simulations. We use lattice effective field theory to describe the low-energy interactions of protons and neutrons, and apply a technique called the 'adiabatic projection method' to reduce the eight-body system to a two-cluster system. We take advantage of the computational efficiency and the more favourable scaling with system size of auxiliary-field Monte Carlo simulations to compute an ab initio effective Hamiltonian for the two clusters. We find promising agreement between lattice results and experimental phase shifts for s-wave and d-wave scattering. The approximately quadratic scaling of computational operations with particle number suggests that it should be possible to compute alpha scattering and capture on carbon and oxygen in the near future. The methods described here can be applied to ultracold atomic few-body systems as well as to hadronic systems using lattice quantum chromodynamics to describe the interactions of

  10. Neutron star recoils from anisotropic supernovae.

    NASA Astrophysics Data System (ADS)

    Janka, H.-T.; Mueller, E.

    1994-10-01

    Refering to recent hydrodynamical computations (Herant et al. 1992; Janka & Mueller 1993a) it is argued that neutron star kicks up to a few hundred km/s might be caused by a turbulent overturn of the matter between proto-neutron star and supernova shock during the early phase of the supernova explosion. These recoil speeds ("kick velocities") may be of the right size to explain the measured proper motions of most pulsars and do not require the presence of magnetic fields in the star. It is also possible that anisotropic neutrino emission associated with convective processes in the surface layers of the nascent neutron star (Burrows & Fryxell 1992; Janka & Mueller 1993b; Mueller 1993) provides an acceleration mechanism (Woosley 1987), although our estimates indicate that the maximum attainable velocities are around 200km/s. Yet, it turns out to be very unlikely that the considered stochastic asymmetries of supernova explosions are able to produce large enough recoils to account for pulsar velocities in excess of about 500km/s, which can be found in the samples of Harrison et al. (1993) and Taylor et al. (1993). It is concluded that other acceleration mechanisms have to be devised to explain the fast motion of PSR 2224+65 (transverse speed >=800km/s Cordes et al. 1993) and the high-velocities deduced from associations between supernova remnants and nearby young pulsars (e.g., Frail & Kulkarni 1991; Stewart et al. 1993; Caraveo 1993).

  11. Nuclear astrophysics studies by recoil mass separators.

    NASA Astrophysics Data System (ADS)

    Gialanella, L.; Brand, K.; Campajola, L.; D'Onofrio, A.; Greife, U.; Morone, M. C.; Oliviero, G.; Ordine, A.; Roca, V.; Rolfs, C.; Romano, M.; Romoli, M.; Schmidt, S.; Schulte, W. H.; Strieder, F.; Terrasi, F.; Trautvetter, H. P.; Zahnow, D.

    1997-11-01

    It has been recently demonstrated that an accelerator mass spectrometry (AMS) system, used as a recoil separator in conjunction with a windowless gas target, can yield the high suppression factor needed to dispersively analyze radiative capture residues, with the aim of measuring cross sections in the sub-microbarn range. An experiment is underway utilizing a radioactive 7Be beam for the measurement of the cross section of the astrophysically important reaction 7Be(p, γ)8B at a center of mass energy ECM = 1 MeV. Preliminary results of this experiment are presented. The extension of the method to another reaction playing a key role in stellar evolution, i.e. 12C(α, γ)16O, requires an improvement of the angle- and momentum-acceptance of the recoil separator, the use of a jet gas target and of a specially designed low-threshold detector. The solutions proposed by a joint Italian-German project are discussed.

  12. Formation of the isomeric pair {sup 194}Ir{sup m,g} in interactions of {alpha} particles with {sup 192}Os

    SciTech Connect

    Uddin, M. S.; Qaim, S. M.; Sudar, S.

    2011-08-15

    Cross sections were measured by the activation technique for the nuclear processes {sup 192}Os({alpha},d+pn+np){sup 194}Ir{sup m,g} up to {alpha}-particle energies of 39 MeV. From the measured data the isomeric cross-section ratio was deduced as a function of projectile energy. The present experimental data as well as those for the {sup 194}Pt(n,p){sup 194}Ir{sup m,g} reaction, given in the literature, were compared with the results of nuclear model calculations using the code talys, which combines the statistical, precompound, and direct interactions. In general, the experimental data were reproduced well by the model calculations, which were done using relatively low values of {eta} (i.e., {Theta}{sub eff}/{Theta}{sub rigid}). The results provide more evidence for the mass dependence of {eta}. The level density parameter for {sup 194}Ir was determined unambiguously.

  13. A gas ionisation detector in the axial (Bragg) geometry used for the time-of-flight elastic recoil detection analysis

    SciTech Connect

    Siketić, Zdravko; Skukan, Natko; Bogdanović Radović, Iva

    2015-08-15

    In this paper, time-of-flight elastic recoil detection analysis spectrometer with a newly constructed gas ionization detector for energy detection is presented. The detector is designed in the axial (Bragg) geometry with a 3 × 3 array of 50 nm thick Si{sub 3}N{sub 4} membranes as an entrance window. 40 mbar isobutane gas was sufficient to stop a 30 MeV primary iodine beam as well as all recoils in the detector volume. Spectrometer and detector performances were determined showing significant improvement in the mass and energy resolution, respectively, comparing to the spectrometer with a standard silicon particle detector for an energy measurement.

  14. 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

  15. Superconducting Nuclear Recoil Sensor for Directional Dark Matter Detection

    NASA Astrophysics Data System (ADS)

    Junghans, Ann; Baldwin, Kevin; Hehlen, Markus; Lafler, Randy; Loomba, Dinesh; Phan, Nguyen; Weisse-Bernstein, Nina

    The Universe consists of 72% dark energy, 23% dark matter and only 5% of ordinary matter. One of the greatest challenges of the scientific community is to understand the nature of dark matter. Current models suggest that dark matter is made up of slowly moving, weakly interacting massive particles (WIMPs). But detecting WIMPs is challenging, as their expected signals are small and rare compared to the large background that can mimic the signal. The largest and most robust unique signature that sets them apart from other particles is the day-night variation of the directionality of dark matter on Earth. This modulation could be observed with a direction-sensitive detector and hence, would provide an unambiguous signature for the galactic origin of WIMPs. There are many studies underway to attempt to detect WIMPs both directly and indirectly, but solid-state WIMP detectors are widely unexplored although they would present many advantages to prevalent detectors that use large volumes of low pressure gas. We present first results of a novel multi-layered architecture, in which WIMPs would interact primarily with solid layers to produce nuclear recoils that then induce measureable voltage pulses in adjacent superconductor layers. This work was supported by the U.S. Department of Energy through the LANL Laboratory Directed Research and Development Program.

  16. Stopping powers of havar for 0.63 5.9 MeV protons and 2.6 24 MeV alpha particles

    NASA Astrophysics Data System (ADS)

    Porter, L. E.; Trzaska, W. H.; Räisänen, J.; Lyapin, V.

    2004-11-01

    A transmission experiment utilizing thin foil targets has been conducted in order to establish the stopping powers of the cobalt-base alloy, havar, for 0.6-5.9 MeV protons and 2.6-24 MeV alpha particles. The basic technique of the novel experimental method used was to record both the projectile energy and the time of flight while alternating measurements with and without the target in place. The uncertainties of the proton and alpha particle data sets ranged from 1.4 to 2.3% and 1.1 to 1.5%, respectively. Modified Bethe-Bloch theory was applied to the measurements in order to ascertain values of the target mean excitation energy (I) and Barkas-effect parameter (b) for each projectile. The extracted values were I = 304.3 ± 2.4 eV and b = 1.37 ± 0.04 for the case of protons, and I = 306.3 ± 2.3 eV and b = 1.47 ± 0.03 for the case of alpha particles. The I-values are somewhat higher than the additivity-based expectation of 295.7 eV, whereas the b-values are clearly consistent with the expected range of 1.4 ± 0.1. The parameter values extracted from the measurements are appraised for compatibility with recently observed trends in values of I and of b with increasing projectile atomic number.

  17. Cell detection in phase-contrast images used for alpha-particle track-etch dosimetry: a semi-automated approach

    NASA Astrophysics Data System (ADS)

    Altman, Michael B.; Wang, Steven J.; Whitlock, Jenny L.; Roeske, John C.

    2005-01-01

    A novel alpha-particle irradiator has recently been developed that provides the ability to characterize cell response. The irradiator is comprised of a collimated, planar alpha-particle source which, from below, irradiates cells cultured on a track-etch material. Cells are imaged using phase-contrast microscopy before and following irradiation to obtain geometric information and survival rates; these can be used with data from alpha-particle track images to assess cell response. A key step in this process is determining cell location within the pre-irradiation images. Although this can be done completely by a human observer, the number of images requiring analysis makes the process time-consuming and tedious. To reduce the potential human error and decrease user interaction time, a semi-automated, computer-aided method of cell detection has been developed. The method employs a two-level adaptive thresholding technique to obtain size and position information about potential cell cytoplasms and nuclei. Proximity and geometry-based thresholds are then used to mark structures as cells. False-positive detections from the automated algorithm are due mostly to imperfections in the track-etch background, camera effects and cellular residue. To correct for these, a human observer reviews all detected structures, discarding false positives. When analysing two randomly selected cell dish image databases, the semi-automated method detected 92-94% of all cells and 94-97% of cells with a well-defined cytoplasm and nucleus while reducing human workload by 32-83%.

  18. Nuclear sizes of /sup 40,42,44,48/Ca from elastic scattering of 104 MeV alpha particles. II. Nuclear density distributions

    SciTech Connect

    Gils, H.J.; Friedman, E.; Majka, Z.; Rebel, H.

    1980-04-01

    The elastic scattering of 104 MeV ..cap alpha.. particles from /sup 40,42,44,48/Ca has been analyzed by a single-folding model with a density-dependent effective interaction. Nuclear density distributions have been extracted using various descriptions including Fourier-Bessel series which distinctly reduces the model dependence of the results and enables realistic estimates of errors. Differences of the density shapes of the Ca isotopes are well determined showing evidence for a neutron skin in /sup 48/Ca. The resulting root mean square radii are compared to the results obtained from other methods. The sensitivity and limitations of various methods are discussed.

  19. The use of alpha particle tagged neutrons for the inspection of objects on the sea floor for the presence of explosives

    NASA Astrophysics Data System (ADS)

    Valkovic, V.; Sudac, D.; Obhodas, J.; Eleon, C.; Perot, B.; Carasco, C.; Sannié, G.; Boudergui, K.; Kondrasovs, V.; Corre, G.; Normand, S.; Woo, R.; Bourbotte, J. M.

    2013-03-01

    A system using a neutron sensor installed within a Remotely Operated Vehicle (ROV) for underwater inspection has been developed. The system can inspect objects for the presence of threat materials, such as explosives and chemical agents, by using alpha particle tagged neutrons from a sealed tube d+t neutron generator to produce characteristic gamma rays within the interrogated object. Here we show that the measured gamma spectra for commonly found ammunition charged with TNT explosives are dominated by C, O and Fe peaks enabling the underwater determination of explosives inside an ammunition shell.

  20. A predictive theory for elastic scattering and recoil of protons from 4He

    DOE PAGESBeta

    Hupin, Guillaume; Quaglioni, Sofia; Navratil, Petr

    2014-12-08

    Low-energy cross sections for elastic scattering and recoil of protons from 4He nuclei (also known as α particles) are calculated directly by solving the Schrodinger equation for five nucleons interacting through accurate two- and three-nucleon forces derived within the framework of chiral effective field theory. Precise knowledge of these processes at various proton backscattering/recoil angles and energies is needed for the ion-beam analysis of numerous materials, from the surface layers of solids, to thin films, to fusion-reactor materials. Indeed, the same elastic scattering process, in two different kinematic configurations, can be used to probe the concentrations and depth profiles ofmore » either hydrogen or helium. Furthermore, we compare our results to available experimental data and show that direct calculations with modern nuclear potentials can help to resolve remaining inconsistencies among data sets and can be used to predict these cross sections when measurements are not available.« less

  1. Predictive theory for elastic scattering and recoil of protons from 4He

    NASA Astrophysics Data System (ADS)

    Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr

    2014-12-01

    Low-energy cross sections for elastic scattering and recoil of protons from 4He nuclei (also known as α particles) are calculated directly by solving the Schrödinger equation for five nucleons interacting through accurate two- and three-nucleon forces derived within the framework of chiral effective field theory. Precise knowledge of these processes at various proton backscattering/recoil angles and energies is needed for the ion-beam analysis of numerous materials, from the surface layers of solids, to thin films, to fusion-reactor materials. Indeed, the same elastic scattering process, in two different kinematic configurations, can be used to probe the concentrations and depth profiles of either hydrogen or helium. We compare our results to available experimental data and show that direct calculations with modern nuclear potentials can help to resolve remaining inconsistencies among data sets and can be used to predict these cross sections when measurements are not available.

  2. A predictive theory for elastic scattering and recoil of protons from 4He

    SciTech Connect

    Hupin, Guillaume; Quaglioni, Sofia; Navratil, Petr

    2014-12-08

    Low-energy cross sections for elastic scattering and recoil of protons from 4He nuclei (also known as α particles) are calculated directly by solving the Schrodinger equation for five nucleons interacting through accurate two- and three-nucleon forces derived within the framework of chiral effective field theory. Precise knowledge of these processes at various proton backscattering/recoil angles and energies is needed for the ion-beam analysis of numerous materials, from the surface layers of solids, to thin films, to fusion-reactor materials. Indeed, the same elastic scattering process, in two different kinematic configurations, can be used to probe the concentrations and depth profiles of either hydrogen or helium. Furthermore, we compare our results to available experimental data and show that direct calculations with modern nuclear potentials can help to resolve remaining inconsistencies among data sets and can be used to predict these cross sections when measurements are not available.

  3. A coherent understanding of low-energy nuclear recoils in liquid xenon

    SciTech Connect

    Sorensen, Peter

    2010-09-01

    Liquid xenon detectors such as XENON10 and XENON100 obtain a significant fraction of their sensitivity to light (∼<10 GeV) particle dark matter by looking for nuclear recoils of only a few keV, just above the detector threshold. Yet in this energy regime a correct treatment of the detector threshold and resolution remains unclear. The energy dependence of the scintillation yield of liquid xenon for nuclear recoils also bears heavily on detector sensitivity, yet numerous measurements have not succeeded in obtaining concordant results. In this article we show that the ratio of detected ionization to scintillation can be leveraged to constrain the scintillation yield. We also present a rigorous treatment of liquid xenon detector threshold and energy resolution. Notably, the effective energy resolution differs significantly from a simple Poisson distribution. We conclude with a calculation of dark matter exclusion limits, and show that existing data from liquid xenon detectors strongly constrain recent interpretations of light dark matter.

  4. Alpha Condensates in Atomic Nuclei

    SciTech Connect

    Suzuki, Y.; Matsumura, H.

    2005-11-21

    Recent issues on Bose-Einstein condensation (BEC) of {alpha}-particles in nuclei are reviewed. A candidate of condensates is discussed for some states in 12C and 16O by defining the amount of {alpha} condensation.

  5. Experimental data on inclusive spectra of protons in interaction of 3. 6-GeV/nucleon. cap alpha. particles with Cu and Sn nuclei

    SciTech Connect

    Ad'yasevich, B.P.; Antonenko, V.G.; Vinogradov, A.A.; Grigor'yan, Y.I.; Dukhanov, V.I.; Ippolitov, M.S.; Karadzhev, K.V.; Lebedev, A.L.; Man'ko, V.I.; Nikolaev, S.A.

    1983-07-01

    Results are reported on the study of inclusive spectra of protons emitted in interaction of 3.6-GeV/nucleon ..cap alpha.. particles with Cu and Sn nuclei. Proton angular distributions are given for three intervals of velocities: 0.325< or approx. =..beta..< or approx. =0.425, 0.425< or approx. =..beta..< or approx. =0.525, and 0.525< or approx. =..beta..< or approx. =0.625. The nature of the angular distributions is practically independent of the combination of colliding nuclei but is substantially different for different velocity intervals. Total cross sections and average charged-particle multiplicities are found in the velocity interval ..beta..> or approx. =0.32. Rapidity distributions are obtained for the invariant cross sections for proton production in the rapidity range -0.2< or approx. =Y< or approx. =0.6 for 0.35< or approx. =p/sub perpendicular//mc< or approx. =0.7.

  6. Treatment of lung tumor colonies with 90Y targeted to blood vessels: comparison with the alpha-particle emitter 213Bi.

    PubMed

    Kennel, S J; Stabin, M; Yoriyaz, H; Brechbiel, M; Mirzadeh, S

    1999-01-01

    An in vivo lung tumor model system for radioimmunotherapy of lung metastases was used to test the relative effectiveness of the vascular- targeted beta-particle emitter 90Y, and alpha-particle emitter, 213Bi. Yttrium-90 was shown to be stably bound by CHXa" DTPA-MAb 201B conjugates and delivered efficiently to lung tumor blood vessels. Dosimetry calculations indicated that the lung received 16.2 Gy/MBq from treatment with 90Y MAb 201B, which was a sevenfold greater absorbed dose than any other organ examined. Therapy was optimal for 90Y with 3 MBq injected. Bismuth-213 MAb 201B also delivered a similar absorbed dose (15Gy/MBq) to the lung. Yttrium-90 was found to be slightly more effective against larger tumors than 213Bi, consistent with the larger range of 2 MeV beta particles from 90Y than the 8 MeV alpha particles from 213Bi. Treatment of EMT-6 tumors growing in immunodeficient SCID mice with 90Y or 213Bi MAb 201 resulted in significant destruction of tumor colonies; however, 90Y MAb 201B was toxic for the SCID mice, inflicting acute lung damage. In another tumor model, IC-12 rat tracheal carcinoma growing in SCID mouse lungs, 90Y therapy was more effective than 213Bi at destroying lung tumors. However, 90Y MAb 201B toxicity for the lung limited any therapeutic effect. We conclude that, although vascular-targeted 90Y MAb can be an effective therapeutic agent, particularly for larger tumors, in this model system, acute damage to the lung may limit its application. PMID:10096515

  7. Dissipation of Parallel and Oblique Alfvén-Cyclotron Waves—Implications for Heating of Alpha Particles in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Maneva, Y. G.; Viñas, Adolfo F.; Moya, Pablo S.; Wicks, Robert T.; Poedts, Stefaan

    2015-11-01

    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 Ωp, 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.

  8. 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

  9. A gun recoil system employing a magnetorheological fluid damper

    NASA Astrophysics Data System (ADS)

    Li, Z. C.; Wang, J.

    2012-10-01

    This research aims to design and control a full scale gun recoil buffering system which works under real firing impact loading conditions. A conventional gun recoil absorber is replaced with a controllable magnetorheological (MR) fluid damper. Through dynamic analysis of the gun recoil system, a theoretical model for optimal design and control of the MR fluid damper for impact loadings is derived. The optimal displacement, velocity and optimal design rules are obtained. By applying the optimal design theory to protect against impact loadings, an MR fluid damper for a full scale gun recoil system is designed and manufactured. An experimental study is carried out on a firing test rig which consists of a 30 mm caliber, multi-action automatic gun with an MR damper mounted to the fixed base through a sliding guide. Experimental buffering results under passive control and optimal control are obtained. By comparison, optimal control is better than passive control, because it produces smaller variation in the recoil force while achieving less displacement of the recoil body. The optimal control strategy presented in this paper is open-loop with no feedback system needed. This means that the control process is sensor-free. This is a great benefit for a buffering system under impact loading, especially for a gun recoil system which usually works in a harsh environment.

  10. Acoustic studies for alpha background rejection in dark matter bubble chamber detectors

    SciTech Connect

    Bou-Cabo, M.; Felis, I.; Ardid, M.; Collaboration: COUPP Collaboration

    2013-08-08

    COUPP (Chicagoland Observatory for Underground Particle Physics) is an experiment with bubble chambers able to detect dark matter directly either with Spin-Dependent or with Spin-Independent interactions. The target material is a superheated liquid (usually CF3I) that can be bubble nucleated due to nuclear recoils produced by elastic collisions of dark matter particles. The bubble growth inside the chamber is accompanied with an acoustic signature. The acoustic technique has been successfully used to have a good alpha discrimination (about 99%). In this paper, we present different studies and results related with the characterization of the acoustic properties of the detector and the different phenomena involved in the acoustic measurements of the bubble growth, such as sound generation, sound transmission and optimization of piezoelectric transducers.

  11. 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.

  12. {gamma}-ray production by proton and {alpha}-particle induced reactions on {sup 12}C, {sup 16}O, {sup 24}Mg, and Fe

    SciTech Connect

    Belhout, A.; Kiener, J.; Coc, A.; Duprat, J.; Engrand, C.; Fitoussi, C.; Gounelle, M.; Lefebvre-Schuhl, A.; Sereville, N. de; Tatischeff, V.; Thibaud, J.-P.; Chabot, M.; Hammache, F.; Benhabiles-Mezhoud, H.

    2007-09-15

    {gamma}-ray production cross sections for proton and {alpha}-particle interactions with {sup 12}C, {sup 16}O, {sup 24}Mg, and Fe have been measured in the energy range 5-25 MeV with proton beams and 5-40 MeV with {alpha}-particle beams. Isotopically pure foils of {sup 24}Mg and foils of natural isotopical composition of C, MgO, and Fe have been used. {gamma}-ray angular distributions were obtained with five high-purity Ge detectors with bismuth germanate Compton shields placed at angles of 45 deg. to 157.5 deg. Cross sections for more than 50 different {gamma}-ray transitions were extracted, and for many of them no data have been published before. Comparison of present data with data available in the literature shows mostly good to excellent agreement. In addition to the production cross sections, high-statistics, low-background line shapes of the 4.438 MeV {sup 12}C {gamma} ray from inelastic scattering off {sup 12}C and spallation of {sup 16}O were obtained. Comparison with nuclear reaction calculations shows that these data place interesting constraints on nuclear reaction models.

  13. Role of low-level impurities and intercalated molecular gases in the {alpha} particle radiolysis of polytetrafluoroethylene examined by static time-of-flight secondary-ion-mass spectrometery

    SciTech Connect

    Fisher, Gregory L.; Szakal, Christopher; Wetteland, Christopher J.; Winograd, Nicholas

    2006-07-15

    The structural degradation of polytetrafluoroethylene (PTFE) upon irradiation with MeV alpha ({alpha}) particles is accompanied by the proliferation of hydrogenated and oxygen-functionalized fluorocarbon species. In this article, we explore the origin of monoxide- and dioxide-functionalized fluorocarbon species that emerge upon {alpha} particle irradiation of PTFE. Samples of neat PTFE were irradiated to {alpha} doses in the range of 10{sup 7}-5x10{sup 10} rad using 5.5 MeV {sup 4}He{sup 2+} ions produced in a tandem accelerator. Static time-of-flight secondary-ion-mass spectrometry (TOF-SIMS), using a 20 keV C{sub 60}{sup +} source, was employed to probe chemical changes as a function of {alpha} particle irradiation. Chemical images and high-resolution mass spectra were collected in both the positive and negative polarities. Residual gas analysis, utilized to monitor the liberation of molecular gases during {alpha} particle irradiation of the PTFE in vacuum, is discussed in relationship to the TOF-SIMS data.

  14. 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.

  15. Difference between a Photon's Momentum and an Atom's Recoil

    SciTech Connect

    Gibble, Kurt

    2006-08-18

    When an atom absorbs a photon from a laser beam that is not an infinite plane wave, the atom's recoil is less than ({Dirac_h}/2{pi})k in the propagation direction. We show that the recoils in the transverse directions produce a lensing of the atomic wave functions, which leads to a frequency shift that is not discrete but varies linearly with the field amplitude and strongly depends on the atomic state detection. The same lensing effect is also important for microwave atomic clocks. The frequency shifts are of the order of the naive recoil shift for the transverse wave vector of the photons.

  16. 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. PMID:26024240

  17. 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.

  18. Scintillation Efficiency of Liquid Xenon for Low Energy Nuclear Recoils

    NASA Astrophysics Data System (ADS)

    Wongjirad, Taritree; Ni, Kaixuan; Manzur, Angel; Kastens, Louis; McKinsey, Daniel

    2008-04-01

    In early 2006, the XENON and ZEPLIN collaborations announced highly stringent upper limits on the WIMP-nucleon cross-section. However, the dominant systematic uncertainty in these limits is due to the uncertainty in the nuclear recoil scintillation efficiency (NRSE) for liquid xenon. The NRSE is defined as the amount of scintillation produced by nuclear recoils, divided by the amount of scintillation produced by electron recoils, per unit energy. Though the NRSE has been measured by several groups, its value at the low energies most important for the liquid xenon WIMP searches has a large uncertainty. Furthermore, the NRSE may vary with the strength of the electric field in the liquid xenon. In an attempt to reduce these uncertainties, we have measured the NRSE down to 5 keV nuclear recoil energy for various electric fields.

  19. Recoil splitting of x-ray-induced optical fluorescence

    SciTech Connect

    Gavrilyuk, S.; Aagren, H.; Gel'mukhanov, F.; Sun, Y.-P.; Levin, S.

    2010-03-15

    We show that the anisotropy of the recoil velocity distribution of x-ray-ionized atoms or molecules leads to observable splittings in subsequent optical fluorescence or absorption when the polarization vector of the x rays is parallel to the momentum of the fluorescent photons. The order of the magnitude of the recoil-induced splitting is about 10 {mu}eV, which can be observed using Fourier or laser-absorption spectroscopic techniques.

  20. RECOILING SUPERMASSIVE BLACK HOLES IN SPIN-FLIP RADIO GALAXIES

    SciTech Connect

    Liu, F. K.; Wang Dong; Chen Xian

    2012-02-20

    Numerical relativity simulations predict that coalescence of supermassive black hole (SMBH) binaries leads not only to a spin flip but also to a recoiling of the merger remnant SMBHs. In the literature, X-shaped radio sources are popularly suggested to be candidates for SMBH mergers with spin flip of jet-ejecting SMBHs. Here we investigate the spectral and spatial observational signatures of the recoiling SMBHs in radio sources undergoing black hole spin flip. Our results show that SMBHs in most spin-flip radio sources have mass ratio q {approx}> 0.3 with a minimum possible value q{sub min} {approx_equal} 0.05. For major mergers, the remnant SMBHs can get a kick velocity as high as 2100 km s{sup -1} in the direction within an angle {approx}< 40 Degree-Sign relative to the spin axes of remnant SMBHs, implying that recoiling quasars are biased to be with high Doppler-shifted broad emission lines while recoiling radio galaxies are biased to large apparent spatial off-center displacements. We also calculate the distribution functions of line-of-sight velocity and apparent spatial off-center displacements for spin-flip radio sources with different apparent jet reorientation angles. Our results show that the larger the apparent jet reorientation angle is, the larger the Doppler-shifting recoiling velocity and apparent spatial off-center displacement will be. We investigate the effects of recoiling velocity on the dust torus in spin-flip radio sources and suggest that recoiling of SMBHs would lead to 'dust-poor' active galactic nuclei. Finally, we collect a sample of 19 X-shaped radio objects and for each object give the probability of detecting the predicted signatures of recoiling SMBH.

  1. 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.

  2. Analysis of accelerator based neutron spectra for BNCT using proton recoil spectroscopy

    SciTech Connect

    Wielopolski, L.; Ludewig, H.; Powell, J.R.; Raparia, D.; Alessi, J.G.; Lowenstein, D.I.

    1999-03-01

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase 1/2 clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra, alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark

  3. ANALYSIS OF ACCELERATOR BASED NEUTRON SPECTRA FOR BNCT USING PROTON RECOIL SPECTROSCOPY

    SciTech Connect

    WIELOPOLSKI,L.; LUDEWIG,H.; POWELL,J.R.; RAPARIA,D.; ALESSI,J.G.; LOWENSTEIN,D.I.

    1998-11-06

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase I/II clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark

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

    SciTech Connect

    Breus, Dimitry E.

    2005-05-16

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

  5. 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.

  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.

    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.

  7. Alpha-particles as probes of nuclear shape in the rare earths and structure effects on proton emission in the mass 80 region

    SciTech Connect

    Sarantites, D.G.; Nicolis, N.G.; Abenante, V.; Majka, Z.; Semkow, T.M. . Dept. of Internal Medicine); Baktash, C.; Beene, J.R.; Garcia-Bermudez, G.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Virtanen, A. ); Griffin, H.C. )

    1989-01-01

    Low emission barriers and large subbarrier anisotropies in the alpha-particle decay with respect to the spin direction, of Sn and rare earth compound nuclei, are examined in the light of recent calculations incorporating deformation. For the rare earth systems deformation which increases with spin is necessary to explain the data. Energy spectra and angular correlations of evaporated protons from the {sup 52}Cr({sup 34}S, 2p2n){sup 82}Sr reaction were measured in coincidence with discrete transition. Large changes in the shape of the proton spectra were observed when high spin states in different rotation al bands are populated. These effects cannot be explained by phase space arguments in the deexcitation process. They are interpreted as due to near-yrast to near-yrast stretched proton emission, which preferentially populates the yrast band by subbarrier protons. 20 refs., 8 figs.

  8. Recoil-α-fission and recoil-α-α-fission events observed in the reaction 48Ca + 243Am

    NASA Astrophysics Data System (ADS)

    Forsberg, U.; Rudolph, D.; Andersson, L.-L.; Di Nitto, A.; Düllmann, Ch. E.; Fahlander, C.; Gates, J. M.; Golubev, P.; Gregorich, K. E.; Gross, C. J.; Herzberg, R.-D.; Heßberger, F. P.; Khuyagbaatar, J.; Kratz, J. V.; Rykaczewski, K.; Sarmiento, L. G.; Schädel, M.; Yakushev, A.; Åberg, S.; Ackermann, D.; Block, M.; Brand, H.; Carlsson, B. G.; Cox, D.; Derkx, X.; Dobaczewski, J.; Eberhardt, K.; Even, J.; Gerl, J.; Jäger, E.; Kindler, B.; Krier, J.; Kojouharov, I.; Kurz, N.; Lommel, B.; Mistry, A.; Mokry, C.; Nazarewicz, W.; Nitsche, H.; Omtvedt, J. P.; Papadakis, P.; Ragnarsson, I.; Runke, J.; Schaffner, H.; Schausten, B.; Shi, Yue; Thörle-Pospiech, P.; Torres, T.; Traut, T.; Trautmann, N.; Türler, A.; Ward, A.; Ward, D. E.; Wiehl, N.

    2016-09-01

    Products of the fusion-evaporation reaction 48Ca + 243Am were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. Amongst the detected thirty correlated α-decay chains associated with the production of element Z = 115, two recoil-α-fission and five recoil- α- α-fission events were observed. The latter five chains are similar to four such events reported from experiments performed at the Dubna gas-filled separator, and three such events reported from an experiment at the Berkeley gas-filled separator. The four chains observed at the Dubna gas-filled separator were assigned to start from the 2n-evaporation channel 289115 due to the fact that these recoil- α- α-fission events were observed only at low excitation energies. Contrary to this interpretation, we suggest that some of these recoil- α- α-fission decay chains, as well as some of the recoil- α- α-fission and recoil-α-fission decay chains reported from Berkeley and in this article, start from the 3n-evaporation channel 288115.

  9. 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.

  10. Evaluation of internal alpha-particle radiation exposure and subsequent fertility among a cohort of women formerly employed in the radium dial industry.

    PubMed

    Schieve, L A; Davis, F; Roeske, J; Handler, A; Freels, S; Stinchcomb, T; Keane, A

    1997-02-01

    This study examined the effect of internal exposure to alpha-particle radiation on subsequent fertility among women employed in the 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. PMID:9008216

  11. 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

  12. Measured Nuclear Recoil Discrimination for HPGS, a Proposed Ton-Scale Dark Matte r Search in Room Temperature Gas

    NASA Astrophysics Data System (ADS)

    Martin, C.; Barton, D.; Dion, M. P.; Esterline, J. H.; Howell, C. R.; Martoff, C. J.; Smith, P. F.; Tornow, W.

    2009-05-01

    The HPGS dark matter proposal is for a simple, room-temperature, ton-scale, 5-10 bar gas scintillation array with nuclear recoil discrimination by pulse-shape, aided by electric fields to suppress wall events. The first experimental confirmation of nuclear recoil discrimination by Xe gas scintillation pulse shape is reported here. Pulse shapes for γ- and x-rays, neutrons, and α particles were measured using highly purified Xe gas at 1-6 bar with a UV-sensitive photomultiplier. Nuclear recoil and α pulses were dominated by recombination scintillation with time constant 250 ns, while gamma and x-ray scintillation was completely contained within 15 ns. We will present detailed comparison of our nuclear recoil pulse shape discrimination to liquid Xe, and discuss the outlook for simpler and lower cost room temperature ton-scale dark matter detectors. (We heartily thank A. Bolotnikov for access to high-purity Xe in his lab at Brookhaven National Laboratory.)

  13. 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.

  14. Alpha channeling in a rotating plasma.

    PubMed

    Fetterman, Abraham J; Fisch, Nathaniel J

    2008-11-14

    The wave-particle alpha-channeling effect is generalized to include rotating plasma. Specifically, radio frequency waves can resonate with alpha particles in a mirror machine with ExB rotation to diffuse the alpha particles along constrained paths in phase space. Of major interest is that the alpha-particle energy, in addition to amplifying the rf waves, can directly enhance the rotation energy which in turn provides additional plasma confinement in centrifugal fusion reactors. An ancillary benefit is the rapid removal of alpha particles, which increases the fusion reactivity. PMID:19113347

  15. Generation of temperature anisotropy for alpha particle velocity distributions in solar wind at 0.3 AU: Vlasov simulations and Helios observations

    NASA Astrophysics Data System (ADS)

    Perrone, D.; Bourouaine, S.; Valentini, F.; Marsch, E.; Veltri, P.

    2014-04-01

    Solar wind "in situ" measurements from the Helios spacecraft in regions of the Heliosphere close to the Sun (˜0.3 AU), at which typical values of the proton plasma beta are observed to be lower than unity, show that the alpha particle distribution functions depart from the equilibrium Maxwellian configuration, displaying significant elongations in the direction perpendicular to the background magnetic field. In the present work, we made use of multi-ion hybrid Vlasov-Maxwell simulations to provide theoretical support and interpretation to the empirical evidences above. Our numerical results show that, at variance with the case of βp≃1 discussed in Perrone et al. (2011), for βp=0.1 the turbulent cascade in the direction parallel to the ambient magnetic field is not efficient in transferring energy toward scales shorter than the proton inertial length. Moreover, our numerical analysis provides new insights for the theoretical interpretation of the empirical evidences obtained from the Helios spacecraft, concerning the generation of temperature anisotropy in the particle velocity distributions.

  16. Calculation of recoil implantation profiles using known range statistics

    NASA Technical Reports Server (NTRS)

    Fung, C. D.; Avila, R. E.

    1985-01-01

    A method has been developed to calculate the depth distribution of recoil atoms that result from ion implantation onto a substrate covered with a thin surface layer. The calculation includes first order recoils considering projected range straggles, and lateral straggles of recoils but neglecting lateral straggles of projectiles. Projectile range distributions at intermediate energies in the surface layer are deduced from look-up tables of known range statistics. A great saving of computing time and human effort is thus attained in comparison with existing procedures. The method is used to calculate recoil profiles of oxygen from implantation of arsenic through SiO2 and of nitrogen from implantation of phosphorus through Si3N4 films on silicon. The calculated recoil profiles are in good agreement with results obtained by other investigators using the Boltzmann transport equation and they also compare very well with available experimental results in the literature. The deviation between calculated and experimental results is discussed in relation to lateral straggles. From this discussion, a range of surface layer thickness for which the method applies is recommended.

  17. Stimulated Rayleigh resonances and recoil-induced effects

    SciTech Connect

    Courtois, J.Y.; Grynberg, G.

    1996-12-31

    The organization of this paper is as follows. We present in Section II the basic ideas about stimulated Rayleigh scattering by considering more particularly the situation where it arises from a relaxation process going on in the material system, and we describe a few experimental observations made in atomic and molecular physics. We then consider the case of nonstationary two-level atoms, and we derive the shape and characteristics of the recoil-induced resonances (Section III). In particular, we show that these resonances can be interpreted either as originating from a stimulated Rayleigh effect or as a stimulated Raman phenomena between atomic energy-momentum states having different momenta. Finally, to make a clear distinction between the physical phenomena that pertain directly to recoil-induced processes (i.e., that actually permit the measurement of the photon recoil) and those for which the introduction of the recoil constitutes a mere physical convenience, we review in Section IV some indisputable manifestations of the photon recoil in atomic and molecular physics. 92 refs., 22 figs.

  18. DNA Double Strand Breaks as Predictor of Efficacy of the Alpha-Particle Emitter Ac-225 and the Electron Emitter Lu-177 for Somatostatin Receptor Targeted Radiotherapy

    PubMed Central

    Graf, Franziska; Fahrer, Jörg; Maus, Stephan; Morgenstern, Alfred; Bruchertseifer, Frank; Venkatachalam, Senthil; Fottner, Christian; Weber, Matthias M.; Huelsenbeck, Johannes; Schreckenberger, Mathias; Kaina, Bernd; Miederer, Matthias

    2014-01-01

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

  19. 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

  20. Rupture and recoil of bent-core liquid crystal filaments.

    PubMed

    Salili, S M; Ostapenko, T; Kress, O; Bailey, C; Weissflog, W; Harth, K; Eremin, A; Stannarius, R; Jákli, A

    2016-05-25

    The recoil process of free-standing liquid crystal filaments is investigated experimentally and theoretically. We focus on two aspects, the contraction speed of the filament and a spontaneously formed undulation instability. At the moment of rupture, the filaments buckle similarly to the classical Euler buckling of elastic rods. The tip velocity decays with decreasing filament length. The wavelength of buckling affinely decreases with the retracting filament tip. The energy gain related to the decrease of the total length and surface area of the filaments is mainly dissipated by layer rearrangements during thickening of the fibre. A flow back into the meniscus is relevant only in the final stage of the recoil process. We introduce a model for the quantitative description of the filament retraction speed. The dynamics of this recoil behaviour may find relevance as a model for biology-related filaments. PMID:27140824