Science.gov

Sample records for alpha particle energy

  1. 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...

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

    PubMed Central

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

    2011-01-01

    Radiation damage to living tissue stems not only from primary ionizing particles but to a substantial fraction from the dissociative attachment of secondary electrons with energies below the ionization threshold. We show that the emission yield of those low energy electrons increases dramatically in ionatom collisions depending on whether or not the target atoms are isolated or embedded in an environment. Only when the atom that has been ionized and excited by the primary particle impact is in immediate proximity of another atom is a fragmentation route known as interatomic Coulombic decay (ICD) enabled. This leads to the emission of a low energy electron. Over the past decade ICD was explored in several experiments following photoionization. Most recent results show its observation even in water clusters. Here we show the quantitative role of ICD for the production of low energy electrons by ion impact, thus approaching a scenario closer to that of radiation damage by alpha particles: We choose ion energies on the maximum of the Bragg peak where energy is most efficiently deposited in tissue. We compare the electron production after colliding He+ ions on isolated Ne atoms and on Ne dimers (Ne2). In the latter case the Ne atom impacted is surrounded by a most simple environment already opening ICD as a deexcitation channel. As a consequence, we find a dramatically enhanced low energy electron yield. The results suggest that ICD may have a significant influence on cell survival after exposure to ionizing radiation. PMID:21730184

  3. 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.

  4. 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.

  5. 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.

  6. Alpha Particle Diagnostic

    SciTech Connect

    Fisher, Ray, K.

    2009-05-13

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

  7. Nuclear reactions induced by high-energy alpha particles

    NASA Technical Reports Server (NTRS)

    Shen, B. S. P.

    1974-01-01

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

  8. Enhancement in the energy resolution of cellulose nitrate track detectors for alpha particles

    NASA Astrophysics Data System (ADS)

    Hussain, Gulzar; Khan, Hameed Ahmed

    1980-06-01

    Different irradiation and etching modes have been investigated to improve the energy resolution properties of cellulose nitrate track detectors when used as alpha particle spectrometer. In this connection CA80-15 and LR-115 plastics were employed for the separation of alpha particle peaks from 239Pu and 238U sources. Enhancement in the energy resolution has been observed when the detectors are etched from the reverse side, or if some degrading foils of optimum thickness are interposed between the source and the detector surface to be analysed. In both the above mentioned modes of enhancement in energy resolution, the regions of maximum damage (the Bragg peaks) occuring along the particle trajectories are attacked immediately with the starting of the etching process. The peaks in the Bragg curve occur at different places when different energy alpha particles pass through the detector. Drastically different rates of energy losses at these places are responsible for the diametric separation of the damage trails.

  9. Modeling of MeV alpha particle energy transfer to lower hybrid waves

    SciTech Connect

    Schivell, J.; Monticello, D.A.; Fisch, N.; Rax, J.M.

    1993-10-01

    The interaction between a lower hybrid wave and a fusion alpha particle displaces the alpha particle simultaneously in space and energy. This results in coupled diffusion. Diffusion of alphas down the density gradient could lead to their transferring energy to the wave. This could, in turn, put energy into current drive. An initial analytic study was done by Fisch and Rax. Here the authors calculate numerical solutions for the alpha energy transfer and study a range of conditions that are favorable for wave amplification from alpha energy. They find that it is possible for fusion alpha particles to transfer a large fraction of their energy to the lower hybrid wave. The numerical calculation shows that the net energy transfer is not sensitive to the value of the diffusion coefficient over a wide range of practical values. An extension of this idea, the use of a lossy boundary to enhance the energy transfer, is investigated. This technique is shown to offer a large potential benefit.

  10. 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.

  11. 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.

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

    SciTech Connect

    Agarwal, S.; Chatterjee, S.N.

    1984-11-01

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

  13. 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.

  14. 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.

  15. Low-energy electron spectrum of a copper target bombarded by {alpha}-particles of {sup 238}Pu

    SciTech Connect

    Kupryashkin, V. T. Sidorenko, L. P.; Feoktistov, A. I.; Rovenskykh, E. P.

    2011-04-15

    The ({alpha}e) time coincidence method is applied to study the low-energy electron spectrum of a copper target bombarded by {alpha}-particles of {sup 238}Pu. Ionization of atoms bombarded by charged particles is considered as the shaking of electrons into the continuous spectrum due to a sudden perturbation by a flying particle. A comparison of experimental and calculated distributions showed good agreement, which confirms the accuracy of the ionization description as a result of the shaking effect.

  16. 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.

  17. 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.

  18. Integrodifferential equation approach. I. Triton and. alpha. -particle binding energies

    SciTech Connect

    Oehm, W.; Sofianos, S.A.; Fiedeldey, H. Physics Department, University of South Africa, Pretoria ); Fabre de la Ripelle, M. Physics Department, University of South Africa, Pretoria )

    1990-12-01

    A single integrodifferential equation in two variables, valid for {ital A} nucleons interacting by pure Wigner forces, which has previously only been solved in the extreme and uncoupled adiabatic approximations, is now solved exactly for three- and four-nucleon systems. The results are in good agreement with the values obtained for the binding energies by means of an empirical interpolation formula. This validates all our previous conclusions, in particular that the omission of higher (than two) order correlations in our four-body equation only produces a rather small underbinding. The integrodifferential equation approach is here also extended to spin-dependent forces of the Malfliet-Tjon type, resulting in two coupled integrodifferential equations in two variables. The exact solution and the interpolated adiabatic approximation are again in good agreement. The inclusion of the hypercentral part of the two-body interaction in the definition of the Faddeev-type components again leads to substantial improvement for fully local potentials, acting in all partial waves.

  19. 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.

  20. 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)

  1. Absolute determination of the energies of alpha particles emitted by 236Pu

    NASA Astrophysics Data System (ADS)

    Rytz, A.; Wiltshire, R. A. P.

    1984-06-01

    The only two previous measurements of the energies of alpha particles emitted by 236Pu were relative determinations. They were in fair agreement with each other, except for the intensity ratios of the two strong lines. We now report an absolute energy measurement which was carried out using the 180 uniform-field magnetic spectrometer at BIPM on four sources prepared at AERE, Harwell with material formed by the reaction 238U( p, 3 n) 236Np236Np236Pu . The alpha particles were detected with aid of Kodak LR 115 (Type 2) cellulose-nitrate films which had considerable advantages over nuclear-track plates. Etching for seven hours in dilute NaOH at 40C produced only weak and sufficiently reproducible distortions of the films reducing uncertainties to at most 50 eV. From six spectra the following mean values of particle energy E? and relative intensity I? were obtained: E? = (5767.660.08) keV, I? = (69.260.45) %; E? = (57210000.10) keV, I? = (30.560.45) %.

  2. Final state interaction effects at higher energies in the photodisintegration of the {alpha}-particle

    SciTech Connect

    Fiedeldey, H.; Sofianos, S.A.; Ellerkmann, G. |

    1995-05-10

    Final State Interaction (FSI) effects are included in the photodisintegration of the {alpha}-particle by means of effective nucleon-trinucleon interactions constructed by inversion of the phase-shifts at energies 50--200 MeV. We show that the use of the Born approximation is justified and that the photonuclear cross sections are sensitive to the details of the bound state wave functions of the {sup 3}He and {sup 4}He. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  3. 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.

  4. Behavior of low-energy protons and alpha particles during a disturbed time period

    NASA Technical Reports Server (NTRS)

    Ipavich, F. M.; Gloeckler, G.; Fan, C. Y.; Hovestadt, D.

    1976-01-01

    The paper presents observations of 130- to 1200-keV protons and 40- to 420-keV/nucleon alpha particles made on the earth-orbiting spacecraft Imp 8 and Imp 7 during an active solar period in September 1974, concentrating, in particular, on an energetic storm particle (ESP) event observed in association with an interplanetary shock wave on September 21. It is found that the observed variations in the proton-to-alpha particle ratios and spectral indices can be explained either by 'pileup' or by acceleration models of ESP events. Several instances of local acceleration of particles in the near-earth environment are also discussed.

  5. 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.

  6. Long range alpha particle detector

    DOEpatents

    MacArthur, Duncan W. (Los Alamos, NM); Wolf, Michael A. (Los Alamos, NM); McAtee, James L. (Los Alamos, NM); Unruh, Wesley P. (Los Alamos, NM); Cucchiara, Alfred L. (Los Alamos, NM); Huchton, Roger L. (Los Alamos, NM)

    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.

  7. 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.

  8. 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.

  9. Alpha particle confinement in tokamaks

    SciTech Connect

    White, R.B.; Mynick, H.E.

    1988-11-01

    An assessment of diffusive tokamak transport mechanisms of concern for alpha particles indicates that the ''stochastic regime'' is the only one which appears to pose a real danger for adequate alpha confinement. This fact, in conjunction with the threshold character of that mechanism, allows one to decide whether an alpha born at a given location will be lost or confined, according to a very simple criterion. Implementing this criterion numerically results in a new code for the assessment of alpha confinement, which is orders of magnitude faster than earlier codes used for this purpose. 13 refs., 3 figs., 1 tab.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. {alpha}-particle optical potential tests below the Coulomb barrier

    SciTech Connect

    Avrigeanu, M.; Avrigeanu, V.

    2009-02-15

    The results of two recent papers concerning ({alpha},{gamma}) and ({alpha},n) reaction cross sections close to the reaction thresholds are discussed with regard to predictions of a recent {alpha}-particle regional optical potential. It is found that the new measured cross sections are rather well described especially for the dominant reaction channels. Particular features of the {alpha}-particle optical potential at energies below the Coulomb barrier explain the failure of a former regional potential obtained by analysis of {alpha}-particle elastic scattering alone at higher energies. Additional limitations of statistical model calculations for minor reaction channels are also discussed.

  16. Nuclear diagnostic for fast alpha particles

    DOEpatents

    Grisham, Larry R. (Lawrence Township, Mercer County, NJ); Post, Jr., Douglass E. (Belle Mead, NJ); Dawson, John M. (Pacific Palisades, CA)

    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.

  17. Alpha Schottky junction energy source

    NASA Astrophysics Data System (ADS)

    Litz, Marc S.; Fan, Zhaoyang; Carroll, James J.; Bayne, Stephen

    2012-06-01

    Isotope batteries offer solutions for long-lived low-power sensor requirements. Alpha emitting isotopes have energy per decay 103 times that of beta emitters. Alpha particles are absorbed within 20 ?m of most materials reducing shielding mitigation. However, damage to materials from the alphas limits their practical use. A Schottky Barrier Diode (SBD) geometry is considered with an alpha emitting contact-layer on a diamond-like crystal semiconductor region. The radiation tolerance of diamond, the safety of alpha particles, combined with the internal field of the SBD is expected to generate current useful for low-power electronic devices over decades. Device design parameters and calculations of the expected current are described.

  18. Characterization of alpha-particle tracks in cellulose nitrate LR-115 detectors at various incident energies and angles.

    PubMed

    Mheemeed, A K; Hussein, A Kh; Kheder, R B

    2013-09-01

    Cellulose nitrate LR-115 detectors were irradiated with alpha particles in the energy range from 1 to 5 MeV at incident angles from 20 to 90, using an (241)Am source. After etching in a 2.5 N NaOH solution kept at 60 C for various periods, the diameters of the major and minor axes of the track openings, track growing rate, track etch rate, etching ratio, and track length were found as a function of energies and incident angles. The measured track parameters were compared to calculated values, and the etching ratio was formulated as a Durrani-Green's function of the incident energy and angle. PMID:23727556

  19. 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.

  20. 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; Khnlein, W; Frekers, D; Wrtche, 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

  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. Shape of the distribution in transverse momentum of relativistic. cap alpha. particles in nucleus-nucleus collisions at high energy

    SciTech Connect

    Abdurazakova, U.A.; Bengus, L.E.; Bondarenko, A.I.; Kholmatova, R.U.; Chernov, G.M.

    1988-05-01

    The spectra of spectator ..cap alpha.. fragments of relativistic projectile nuclei (from /sup 12/C to /sup 56/Fe) which have undergone inelastic interaction are discussed. It is shown by a correlation analysis that the nonstatistical excess of ..cap alpha.. particles with large transverse momenta cannot be treated as the direct product of decay of the residual fragmenting nucleus. A qualitative analysis is carried out of possible mechanisms of production of ..cap alpha.. particles with large transverse momenta, and a method is formulated for extraction of the true characteristics (in the rest system of the fragmenting system) of the fragmentation products of nuclei.

  3. 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.

  4. {alpha}-particle spectrum in the reaction p + {sup 11}B {yields} {alpha} + {sup 8}Be* {yields} 3{alpha}

    SciTech Connect

    Dmitriev, V. F.

    2009-07-15

    Using a simple phenomenological parametrization of the reaction amplitude we calculated {alpha}-particle spectrumin the reaction p + {sup 11}B {yields} {alpha} + {sup 8}Be* {yields} 3{alpha} at the resonance proton energy of 675 keV. The parametrization includes Breit-Wigner factor with an energy-dependent width for intermediate {sup 8}Be* state and the Coulomb and the centrifugal factors in {alpha}-particle-emission vertices. The shape of the spectrum consists of a well-defined peak corresponding to emission of the primary {alpha} and a flat shoulder going down to very low energy. We found that below 1.5MeV there are 17.5% of {alpha}'s and below 1MeV there are 11% of them.

  5. 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.

  6. [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.

  7. 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.

  8. ''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.

  9. The angular sensitivity of kodak LR-film to alpha particles

    NASA Astrophysics Data System (ADS)

    Jnsson, Gilbert

    Kodak LR 115-II film is exposed to low energy alpha particles ( E? ? 4 MeV) in a study of the angular sensitivity of the cellulose nitrate film to alpha particles. The result shows that there is a cut off in the detection over a certain angle of incidence of the alpha particles. The cut off value is compared with values predicted from calculations based on relations between etch velocity and residual range for alpha particles. A comparison is made between the range of the alpha particles in the film calculated from different available formulas. In addition the energy limits for detection of alpha particles in the film are discussed.

  10. Additional {alpha}-particle optical potential tests below the Coulomb barrier

    SciTech Connect

    Avrigeanu, M.; Avrigeanu, V.

    2010-03-15

    New results of ({alpha},{gamma}) and ({alpha},n) reaction cross section measurements close to the reaction thresholds support the setting up of recent parameters of the {alpha}-particle optical model potential (OMP) below the Coulomb barrier. Particular features of the {alpha}-particle optical potential at energies below the Coulomb barrier explain the failure of using the OMP parameters obtained by analysis of only {alpha}-particle elastic scattering at higher energies.

  11. The mutagenicity of. cap alpha. particles from plutonium-238

    SciTech Connect

    Thacker, J.; Stretch, A.; Goodhead, D.T.

    1982-11-01

    Cell killing and the frequency of mutation to thioguanine resistance (HGPRT enzyme deficiency) were measured after irradiation of cultured hamster cells with 250-kV X rays and with /sup 238/Pu ..cap alpha.. particles. The frequency of mutants induced by these ..cap alpha.. particles, for a given level of cell killing, was approximately twice that induced by X rays. This agrees with expectations from our previously published data on mutation induction by radiations of high linear energy transfer, but disagrees with another recently published report of the relative mutagenicity of /sup 238/Pu ..cap alpha.. particles. Possible reasons for this discrepancy are discussed.

  12. 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

  13. A High-Throughput Screen for Alpha Particle Radiation Protectants

    PubMed Central

    Seideman, Jonathan H.; Shum, David; Djaballah, Hakim

    2010-01-01

    Abstract Alpha-particle-emitting elements are of increasing importance as environmental and occupational carcinogens, toxic components of radiation dispersal devices and accidents, and potent therapeutics in oncology. Alpha particle radiation differs from radiations of lower linear energy transfer in that it predominantly damages DNA via direct action. Because of this, radical scavengers effective for other radiations have had only limited effect in mitigating alpha particle toxicity. We describe here a simple assay and a pilot screen of 3,119 compounds in a high-throughput screen (HTS), using the alpha-particle-emitting isotope, 225Ac, for the discovery of compounds that might protect mammalian cells from alpha particles through novel mechanisms. The assay, which monitored the viability of a myeloid leukemic cell line upon alpha particle exposure, was robust and reproducible, yielding a Z' factor of 0.66 and a signal-to-noise ratio of nearly 10 to 1. Surprisingly, 1 compound emerged from this screen, epoxy-4,5-?-dihydroxysantonin (EDHS), that showed considerable protective activity. While the value of EDHS remains to be determined, its discovery is a proof of concept and validation of the utility of this HTS methodology. Further application of the described assay could yield compounds useful in minimizing the toxicity and carcinogenesis associated with alpha particle exposure. PMID:20658946

  14. 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.

  15. 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.

  16. 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) ? 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 ?m(-1) at the start of the track (depending on initial energy) to a peak of ~237 keV ?m(-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 ?m(-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 inactivation was observed to increase with decreasing energy to a peak of ~68% survival probability for incident energies of ~1.8 MeV (average LET of 190 keV ?m(-1)) producing ~0.39 lethal lesions per track. However, the efficiency of a single traversal will also vary significantly with cell morphology and angle of incidence, as well as cell type. PMID:26121227

  17. 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.

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

    ERIC Educational Resources Information Center

    Andrews, D. G. H.

    2008-01-01

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

  19. 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…

  20. Design of an alpha-particle counting system at a defined solid angle at Turkish atomic energy authority-Sarayky nuclear research and training center (TAEK-SANAEM)

    NASA Astrophysics Data System (ADS)

    Seferino?lu, Meryem; Yeltepe, Emin

    2015-12-01

    The design details of an alpha-particle counting set-up at a defined solid angle (ACS-DSA) constructed in Radionuclide Metrology Department at TAEK-SANAEM for use in the primary standardization of radioactive solutions and determination of nuclear decay data of alpha-particle emitters is presented. The counting system is designed such that the solid angle is very well-defined and directly traceable to the national standards. The design involves mechanical construction of different parts like the source chamber, various coaxial flanges, and circular diaphragms in front of the passivated implanted planar silicon (PIPS) detector, distance tubes, a digital caliper and a sliding piston to allow for different measurement configurations. All geometric configurations are easily changeable and characterisable with high accuracy which facilitates the solid angle calculation. A mixed alpha source was counted to check performance of assembled ACS-DSA system and good energy resolution and low peak tailing in the alpha energy spectrum was observed for small diaphragm apertures and far source-to-detector geometries.

  1. 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.

  2. 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

  3. Alternating current long range alpha particle detector

    DOEpatents

    MacArthur, Duncan W. (Los Alamos, NM); McAtee, James L. (Los Alamos, NM)

    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.

  4. 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.

  5. 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.

  6. 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.

  7. Nuclear Alpha-Particle Condensates

    NASA Astrophysics Data System (ADS)

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

    The ?-particle condensate in nuclei is a novel state described by a product state of ?'s, all with their c.o.m. in the lowest 0S orbit. We demonstrate that a typical ?-particle condensate is the Hoyle state (Ex=7.65 MeV,0^+_2 state in ^{12}C), which plays a crucial role for the synthesis of ^{12}C in the universe. The influence of antisymmentrization in the Hoyle state on the bosonic character of the ? particle is discussed in detail. It is shown to be weak. The bosonic aspects in the Hoyle state, therefore, are predominant. It is conjectured that ?-particle condensate states also exist in heavier n? nuclei, like ^{16}O,^{20}Ne, etc. For instance the 0^+_6 state of ^{16}O at Ex=15.1 MeV is identified from a theoretical analysis as being a strong candidate of a 4? condensate. The calculated small width (140 keV) of 0^+_6, consistent with data, lends credit to the existence of heavier Hoyle-analogue states. In non-self-conjugated nuclei such as ^{11} B and ^{13} C, we discuss candidates for the product states of clusters, composed of ?'s, triton's, and neutrons etc. The relationship of ?-particle condensation in finite nuclei to quartetting in symmetric nuclear matter is investigated with the help of an in-medium modified four-nucleon equation. A nonlinear order parameter equation for quartet condensation is derived and solved for ? particle condensation in infinite nuclear matter. The strong qualitative difference with the pairing case is pointed out.

  8. 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.

  9. Alpha particles diffusion due to charge changes

    NASA Astrophysics Data System (ADS)

    Clauser, C. F.; Farengo, R.

    2015-12-01

    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.

  10. {alpha}-particle production in {sup 6}He+{sup 120}Sn collisions

    SciTech Connect

    Faria, P. N. de; Lichtenthaeler, R.; Pires, K. C. C.; Lepine-Szily, A.; Guimaraes, V.; Mendes, D. R. Jr.; Barioni, A.; Morcelle, V.; Morais, M. C.; Moro, A. M.; Arazi, A.

    2010-09-15

    The collision {sup 6}He+{sup 120}Sn has been investigated at four energies near the Coulomb barrier. A large yield of {alpha} particles has been detected, with energies around the energy of the scattered {sup 6}He beam. The energy and angular distributions of the {alpha} particles have been analyzed and compared with breakup and neutron transfer calculations.

  11. 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

  12. Validating modeling assumptions of alpha particles in electrostatic turbulence

    NASA Astrophysics Data System (ADS)

    Wilkie, G. J.; Abel, I. G.; Highcock, E. G.; Dorland, W.

    2015-06-01

    To rigorously model fast ions in fusion plasmas, a non-Maxwellian equilibrium distribution must be used. In this work, the response of high-energy alpha particles to electrostatic turbulence has been analyzed for several different tokamak parameters. Our results are consistent with known scalings and experimental evidence that alpha particles are generally well confined: on the order of several seconds. It is also confirmed that the effect of alphas on the turbulence is negligible at realistically low concentrations, consistent with linear theory. It is demonstrated that the usual practice of using a high-temperature Maxwellian, while previously shown to give an adequate order-of-magnitude estimate of the diffusion coefficient, gives incorrect estimates for the radial alpha particle flux, and a method of correcting it in general is provided. Furthermore, we see that the timescales associated with collisions and transport compete at moderate energies, calling into question the assumption that alpha particles remain confined to a flux surface that is used in the derivation of the slowing-down distribution.

  13. 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.

  14. Calculation of the {alpha}-particle ground state

    SciTech Connect

    M. Viviani; A. Kievsky; S. Rosati

    1994-10-01

    The Correlated Hyperspherical Harmonic expansion method is used to calculate alpha-particle properties with a realistic hamiltonian consisting of the Argonne V14 two nucleon and Urbana model VIII three nucleon potentials. The calculated binding energy, mass radius and wave percentages are close to the corresponding quantities obtained with Green's Function Monte Carlo and Faddeev-Yakubovsky techniques.

  15. Scaling of cross sections for K-electron capture by high-energy protons and alpha-particles from the multielectron atoms

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1979-01-01

    Electron capture by protons from H, He, and the K shell of Ar, and electron capture by alpha particles from He are considered. Using the experimental data, a function of the capture cross section is formed. It is shown that when this function is plotted versus the inverse of the collision energies, at high energies a straight line is obtained. At lower energies the line is concave up or down, depending on the charge of the projectile and/or the effective charge and the ionization potential of the electron that is being captured. The plot can be used to predict cross sections where experimental data are not available, and as a guide in future experiments. High-energy scaling formulas for K-electron capture by low-charge projectiles are given.

  16. 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.

  17. 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 ?Ci/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

  18. 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 Alfvn 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.

  19. 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

  20. 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.

  1. 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.

  2. High-resolution alpha-particle spectrometry of ?U.

    PubMed

    Pomm, S; Garca-Torao, E; Marouli, M; Crespo, M T; Jobbgy, V; Van Ammel, R; Paepen, J; Stroh, H

    2014-05-01

    The alpha-particle emission probabilities associated with the three main alpha transitions of (238)U were measured by high-resolution alpha-particle spectrometry. Highly enriched (238)U material was used and its isotopic composition characterised by mass spectrometry. Source production through electrodeposition was optimised to reconcile conflicting demands for good spectral resolution and statistical precision. Measurements were performed at IRMM and CIEMAT for 1-2 years in three different set-ups. A new magnet system was put into use to largely eliminate true coincidence effects with low-energy conversion electrons. Finally the accuracy and precision of the relative emission probabilities for the three transitions - 77.01 (10)%, 22.92 (10)% and 0.068 (10)%, respectively - have been improved significantly. PMID:24355304

  3. 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.

  4. 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.

  5. Alpha particle radioimmunotherapy: Animal models and clinical prospects

    SciTech Connect

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

    1989-06-01

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

  6. 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.

  7. Bootstrap current induced by fusion born alpha particles

    SciTech Connect

    Hsu, C.T.; Shaing, K.C.; Gormley, R.P.; Sigmar, D.J. )

    1992-12-01

    The bootstrap current produced by fusion born alpha particles is obtained, retaining effects of slowing down drag, pitch angle scattering, and arbitrary aspect ratio. The result is presented both as a summation of a rapidly converging series and a simple Pade approximation good for arbitrary aspect ratio. Quantitative results are derived using the International Thermonuclear Experimental Reactor (ITER) (Plasma Phys. Controlled Nucl. Fusion Res. (International Atomic Energy Agency, Vienna, 1989), Vol. 3, p. 214) parameters.

  8. Fission studies with 140 MeV {alpha} particles

    SciTech Connect

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

    2009-09-15

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

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

    SciTech Connect

    Wu, Y.; White, R.B.

    1994-04-01

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

  10. 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.

  11. 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

  12. 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

  13. 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)

  14. Light charged-particle production from proton- and {alpha}-induced reactions on natSi at energies from 25 to 65 MeV

    SciTech Connect

    Demetriou, P.; Dufauquez, Ch.; El Masri, Y.; Koning, A. J.

    2006-04-26

    A series of in-beam experiments using proton and {alpha}-particle projectiles on natSi target has been performed at the Louvain-la-Neuve Cyclotron facility. Inclusive data of double-differential and differential cross sections, as well as total cross sections of all possible light charged particles emitted (p, d, t, 3He, {alpha}) were measured. The data are compared with the predictions of the nuclear-reaction code TALYS. A detailed discussion of the model calculations and the modifications required to improve the description of the data is presented.

  15. 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.

  16. 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.

  17. 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.

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

    SciTech Connect

    Zhang, H. F.; Royer, G.

    2008-05-15

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

  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 passing/trapped boundary was observed to occur between inward and outward shifts at an intermediate value of plasma current (1.4 MA). This anomalous loss feature is not yet understood.

  20. Method for determining fast-alpha-particle confinement in tokamak plasmas using resonant nuclear reactors

    SciTech Connect

    Cecil, F.E.; Zweben, S.J.; Medley, S.S.

    1986-03-01

    The resonant nuclear reactions D(..cap alpha..,..gamma..)/sup 6/Li, /sup 6/Li(..cap alpha..,..gamma..)/sup 10/B, and /sup 7/Li(..cap alpha..,..gamma..)/sup 11/B are examined as diagnostics of fast-alpha-particle confinement in tokamak plasmas. Gamma rays from these resonant reactions with energies from 2.1 MeV to 9.2 MeV may be used to infer the alpha-particle population between energies of 0.4 MeV and 2.6 MeV. The ratio of these alpha-burnup reactions to the reactions T(D,..gamma..)/sup 5/He and /sup 3/He(D,..gamma..)/sup 5/Li provides a technique for the measurement of alpha confinement.

  1. Alpha-particle Monte Carlo simulation for microdosimetric calculations using a commercial spreadsheet.

    PubMed

    Roeske, John C; Hoggarth, Mark

    2007-04-01

    Alpha-particle emitters are currently being evaluated in the treatment of cancer. Because of the short range and high linear energy transfer (LET) of most therapeutic alpha-particle emitters, there are significant stochastic variations in the energy deposited within the cellular nucleus. Hence microdosimetric spectra are often necessary to interpret biological endpoints. However, alpha-particle microdosimetric codes are not readily available. In this paper, we describe how a commercial spreadsheet may be used to perform a Monte Carlo simulation of alpha-particle transport. Subsequently, this information is used to determine the distribution of path lengths, energy deposited, and specific energy for a single alpha-particle traversal through the cell nucleus. These data may then be used to determine microdosimetric parameters for multiple alpha-particle emissions. In our analysis, comparison of the first and second moments of the single-event spectra with previously published data show agreement on the order of a few per cent. These small discrepancies are due to differences in interpolation of stopping powers between the various algorithms. Thus, the spreadsheet Monte Carlo method represents a simple and efficient method to calculate single-event spectra for alpha-particle emitters. Copies of the spreadsheet are available from the corresponding author upon request. PMID:17374919

  2. 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.

  3. Energetic alpha particle deposition in a magnetized plasma

    SciTech Connect

    Smitherman, D.P.; Kirkpatrick, R.C.

    1991-01-01

    The problem of energetic alpha particle deposition in a dense, magnetized deuterium-tritium (DT) thermonuclear fuel has been studied numerically for the case of coulomb interactions in cylindrical geometry. This was done by following the particle trajectories initiated at various radii and in different directions through the plasma and its imposed field until they had either left the plasma or deposited all their energy. The resulting complex particle trajectories in the static magnetized fuel make a detailed treatment of the problem computationally intensive. Therefore, we have attempted to use detailed modeling to produce a data base for a neural nets algorithm for incorporation in an ignition critical profile code. While the accuracy of the neutral net in reproducing the detailed calculational results is not high, it is approximately 6000 times faster. 7 refs., 1 fig.

  4. Complex-Energy Shell-Model Description of Alpha Decay

    SciTech Connect

    Id Betan, R.; Nazarewicz, Witold

    2011-01-01

    In his pioneering work of alpha decay, Gamow assumed that the alpha particle formed inside the nucleus tunnels through the barrier of the alpha-daughter potential. The corresponding metastable state can be viewed as a complex-energy solution of the time-independent Schroedinger equation with the outgoing boundary condition. The formation of the alpha cluster, missing in the original Gamow formulation, can be described within the R-matrix theory in terms of the formation amplitude. In this work, the alpha decay process is described by computing the formation amplitude and barrier penetrability in a large complex-energy configuration space spanned by the complex-energy eigenstates of the finite Woods-Saxon (WS) potential. The proper normalization of the decay channel is essential as it strongly modifies the alpha-decay spectroscopic factor. The test calculations are carried out for the ^{212}Po alpha decay.

  5. 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.

  6. 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.

  7. Alpha particle detector based on micropixel avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Ahmadov, F.; Abdinov, O.; Ahmadov, G.; Anfimov, N.; Garibov, A.; Guliyev, E.; Krumshtein, Z.; Madatov, R.; Olshevski, A.; Shvetsov, V.; Sadigov, A.; Sadygov, Z.; Titov, A.; Zhezher, V.

    2013-12-01

    The main goal of this work is to study the possibility of detecting alpha particles with a micropixel avalanche photodiode (MAPD) in combination with Lutetium Fine Silicate (LFS) scintillators (500 ?m thick). The results show that alpha detectors based on the MAPD are expected to be useful in many applications: public security (associated particle imaging for explosives and drugs detection), radioactive contamination monitoring in various environments, and detection of charged particles from nuclear reactions.

  8. 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.

  9. Measurement of alpha particles on PLT

    SciTech Connect

    Murphy, T.J.; Strachan, J.D.

    1984-12-01

    The radial emission profile of the d(/sup 3/He,p)..cap alpha.. fusion reaction was measured on PLT by pitch angle resolution of the escaping 3.7-MeV alphas. The d-/sup 3/He reactions were produced by /sup 3/He minority ICRF and the emission was strongly peaked at the ICRF resonance layer.

  10. {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.

  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. Depth Measurements Using Alpha Particles and Upsettable SRAMs

    NASA Technical Reports Server (NTRS)

    Buehler, M. G.; Reier, M.; Soli, G. A.

    1995-01-01

    A custom designed SRAM was used to measure the thickness of integrated circuit over layers and the epi-layer thickness using alpha particles and a test SRAM. The over layer consists of oxide, nitride, metal, and junction regions.

  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. Modification of alpha-particle emission spectrum in beam-injected deuterium-tritium plasmas

    SciTech Connect

    Matsuura, H.; Nakao, Y.

    2009-04-15

    The alpha ({alpha})-particle and neutron emission spectra in a deuterium-tritium plasma accompanied with neutral-beam-injection (NBI) heating are evaluated in a consistent way by solving the Boltzmann-Fokker-Planck equations for deuteron, triton, and {alpha}-particle simultaneously. It is shown that owing to the existence of non-Maxwellian tail component in fuel-ion distribution function due to NBI and/or nuclear elastic scattering, the generation rate of the energetic ({>=}4 MeV) {alpha}-particle increases significantly. When 20 MW intense deuterium beam with 1 MeV beam-injection energy is injected into an 800 m{sup 3} plasma (T{sub e}=10 keV, n{sub e}=6.2x10{sup 19} m{sup -3}), the enhancement of the fraction of the power carried by {alpha}-particles with energy above 4 (3.9) MeV to total {alpha}-particle power is almost twice (1.5 times) as much from the value for Gaussian distribution. A verification scenario for the modification of the emission spectrum by using the gamma ({gamma})-ray-generating {sup 9}Be({alpha},n{gamma}){sup 12}C reaction is also presented.

  16. Design of an alpha-particle counting system at a defined solid angle at Turkish atomic energy authority-Sarayköy nuclear research and training center (TAEK-SANAEM)

    NASA Astrophysics Data System (ADS)

    Seferinoğlu, Meryem; Yeltepe, Emin

    2015-12-01

    The design details of an alpha-particle counting set-up at a defined solid angle (ACS-DSA) constructed in Radionuclide Metrology Department at TAEK-SANAEM for use in the primary standardization of radioactive solutions and determination of nuclear decay data of alpha-particle emitters is presented. The counting system is designed such that the solid angle is very well-defined and directly traceable to the national standards. The design involves mechanical construction of different parts like the source chamber, various coaxial flanges, and circular diaphragms in front of the passivated implanted planar silicon (PIPS®) detector, distance tubes, a digital caliper and a sliding piston to allow for different measurement configurations. All geometric configurations are easily changeable and characterisable with high accuracy which facilitates the solid angle calculation. A mixed alpha source was counted to check performance of assembled ACS-DSA system and good energy resolution and low peak tailing in the alpha energy spectrum was observed for small diaphragm apertures and far source-to-detector geometries.

  17. A history of nuclear transmutations by natural alpha particles

    NASA Astrophysics Data System (ADS)

    Leone, Matteo

    2005-11-01

    A systematic account of the use of alpha particles up to the 1930s for promoting the disintegration of atoms is here provided. As will be shown, a number of different radium family alpha sources were used in the experiments that led to the discoveries of the proton (Rutherford E 1919 Phil. Mag. 37 581-7) and neutron (Chadwick J 1932 Nature 129 312). The reasons leading to the employment of a particular alpha particle source, as well as the relationship between these sources and the available methods of recording, will be closely addressed.

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

    DOEpatents

    Post, Jr., Douglass E. (Belle Mead, NJ); Hwang, David Q. (Lawrencevill, NJ); Hovey, Jane (Plainsboro, NJ)

    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.

  19. {alpha} particles and the ''pasta'' phase in nuclear matter

    SciTech Connect

    Avancini, S. S.; Barros, C. C. Jr.; Menezes, D. P.; Providencia, C.

    2010-08-15

    The effects of the {alpha} particles in nuclear matter at low densities are investigated within three different parametrizations of relativistic models at finite temperature. Both homogeneous and inhomogeneous matter (pasta phase) are described for neutral nuclear matter with fixed proton fractions and stellar matter subject to {beta} equilibrium and trapped neutrinos. In homogeneous matter, {alpha} particles are present only at densities below 0.02 fm{sup -3} and their presence decreases with increase of the temperature and, for a fixed temperature, the {alpha} particle fraction decreases for smaller proton fractions. A repulsive interaction is important to mimic the dissolution of the clusters in homogeneous matter. The effect of the {alpha} particles on the pasta structure is very small except close to the critical temperatures and/or proton fractions, when it may still predict a pasta phase while no pasta phase would occur in the absence of light clusters. It is shown that for densities above 0.01 fm{sup 3} the {alpha}-particle fraction in the pasta phase is much larger than that in homogeneous matter.

  20. Breakup of {sup 12}C resonances into three alpha particles

    SciTech Connect

    Kirsebom, O. S.; Fynbo, H. O. U.; Hyldegaard, S.; Riisager, K.; Alcorta, M.; Borge, M. J. G.; Cubero, M.; Dominguez-Reyes, R.; Madurga, M.; Perea, A.; Tengblad, O.; Diget, C. A.; Fulton, B. R.; Fraile, L. M.; Jonson, B.; Nilsson, T.; Nyman, G.; Munoz Martin, A.

    2010-06-15

    The reaction {sup 3}He+{sup 11}B->d+{sup 12}C* has been used to populate resonances in {sup 12}C up to an excitation energy of 15 MeV. The subsequent breakup to three alpha particles has been measured in complete kinematics. Dalitz plots are used to visualize and analyze the data. The Dalitz plot intensity distribution exhibits zero points characteristic of the total spin and parity of the 3alpha system allowing us to determine the spin and parity of a state in {sup 12}C at 13.35 MeV whose quantum numbers were hitherto not well established. The Dalitz plot intensity distributions of the 2{sup -} state at 11.83 MeV and the 1{sup +} state at 12.71 MeV are compared with the predictions of a recent three-body calculation as well as with simpler models. All are able to reproduce the gross structures seen in the Dalitz plot, but none give an accurate description of the detailed profile of the distributions.

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

    NASA Astrophysics Data System (ADS)

    Zat'ko, B.; Dubeck, F.; agtov, A.; Sedla?ov, K.; Ry?, L.

    2015-04-01

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

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

    SciTech Connect

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

    1997-03-01

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

  3. Alpha particle evaporation as a probe for dynamical deformations

    NASA Astrophysics Data System (ADS)

    1999-09-01

    Evaporation of alpha particles in heavy ion reactions followed by fusion has proved to be a powerful probe for the properties of emitting nuclei. Detailed experimental data and different model calculations allow us to probe whether the foundation of the statistical model holds for the compound nucleus populated in these reactions. It has been observed that in the case of composite nuclei at moderate energies and angular momenta, evaporation spectra are well explained in terms of the standard statistical model CASCADE code employing optical model transmission coefficients in the description of particle evaporation. However, it has been observed that experimental particle spectra from heavy ion induced fusion reactions are no longer consistent with the predictions of such models. It has been predicted by some authors that in these systems the emission barriers are lower than those expected from optical model transmission coefficients calculated for the respective inverse absorption channels. Some authors claim that these spectra may be well explained in terms of the statistical model incorporating only spin dependent level density and without lowering the emission barriers. The field is not yet free from the controversies. Furthermore, the assumption of the very short formation time in statistical model analysis is one extreme of the general evolution process which in fact is a continuous relaxation process, leading to the composite system from the entrance channel to the equilibrated configuration. Recent dynamical description of heavy ion collisions do not support this assumption in many cases. In symmetric entrance channels and for collisions where centre of mass energy is well above the Coulomb barrier, formation time can be even larger than decay time of the resulting composite system. In such cases realistic approach will be to couple the dynamical evolution of the intrinsic excitation of the composite system to a time dependent statistical model calculation. The above question has been addressed in the light of the alpha particle spectra taken in coincidence with the evaporation residues for the asymmetric 28Si +51V and the symmetric 28Si +27 Al systems. The experimental data have been interpreted in the framework of dynamical trajectory model calculations.

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

    DOEpatents

    Orr, Christopher Henry (Sellafield, Seascale, Cumbria, GB); Luff, Craig Janson (Sellafield, Seascale, Cumbria, GB); Dockray, Thomas (Sellafield, Seascale, Cumbria, GB); Macarthur, Duncan Whittemore (P.O. Box 1663, Los Alamos, NM 87545)

    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. Isotopic distributions of Rb, In, and Cs produced in interactions of high-energy protons, deuterons, and. cap alpha. particles with Ta

    SciTech Connect

    Avdeev, S.P.; Karnaukhov, V.A.; Korovich, G.Y.; Kuznetsov, V.D.; Nagy, T.; Petrov, L.A.

    1982-02-01

    With the aid of off-line mass-separation distributions were measured for Rb, In, and Cs isotopes produced in the interactions of 8-GeV protons and deuterons and 15.2-GeV ..cap alpha.. particles with Ta. It was found that neither the position of the maximum nor the shape of the isotopic distribution curve changed significantly with the type of projectile used in the bombardment. In all cases the relative behavior of the distribution was in qualitative agreement with calculations using the semiempirical Rudstam formula. For In, measurements were also made with a 0.66-GeV proton beam. Here the shape of the isotopic distribution distribution was found to be influenced by the fission process.

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

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

    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 1120nm, 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.

  7. High energy particle astronomy.

    NASA Technical Reports Server (NTRS)

    Buffington, A.; Muller, R. A.; Smith, L. H.; Smoot, G. F.

    1972-01-01

    Discussion of techniques currently used in high energy particle astronomy for measuring charged and neutral cosmic rays and their isotope and momentum distribution. Derived from methods developed for accelerator experiments in particle physics, these techniques help perform important particle astronomy experiments pertaining to nuclear cosmic ray and gamma ray research, electron and position probes, and antimatter searches.

  8. Investigation of the effective atomic numbers of dosimetric materials for electrons, protons and alpha particles using a direct method in the energy region 10 keV-1 GeV: a comparative study.

    PubMed

    Kurudirek, Murat; Aksakal, O?uz; Akku?, Tuba

    2015-11-01

    A direct method has been used for the first time, to compute effective atomic numbers (Z eff) of water, air, human tissues, and some organic and inorganic compounds, for total electron proton and alpha particle interaction in the energy region 10 keV-1 GeV. The obtained values for Z eff were then compared to those obtained using an interpolation procedure. In general, good agreement has been observed for electrons, and the difference (%) in Z eff between the results of the direct and the interpolation method was found to be <10 % for all materials, in the energy range from 10 keV to 1 MeV. More specifically, results of the two methods were found to agree well (Dif. <10 %) for air, calcium fluoride, kapton polyimide film, paraffin wax and plastic scintillator in the entire energy region with respect to the total electron interaction. On the other hand, values for Z eff calculated using both methods for protons and alpha particles generally agree with each other in the high-energy region above 10 MeV. PMID:26082026

  9. Fire Hose Instability Driven by Alpha Particle Temperature Anisotropy

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  10. Alpha Particles Play a Relatively Minor Role in Magnetized Target Fusion Systems

    SciTech Connect

    Ryutov, D.D.

    2002-03-15

    Two problems related to alpha particle physics in magnetized target fusion (MTF) systems are briefly discussed. First, we evaluate the pressure and density of alpha particles under the assumption that they are perfectly confined and have a classical slowing-down distribution. It turns out that because of a comparatively low plasma temperature in MTF systems, the relative pressure and density of alpha particles are more than an order of magnitude less than in fusion reactors based on ITER-type tokamaks. Therefore, one may expect that even in the extreme case of a perfect confinement of alpha particles, their presence will have a much weaker (than in the case of tokamaks) effect on plasma stability and transport. Second, we discuss the kinetics of plasma burn under the opposite extreme assumption that all the alpha particles are instantaneously lost, without leaving any energy in a plasma. It turns out that even in this case, the plasma energy yield in batch-burn systems is only weakly affected by burnout effects.

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

    PubMed

    Das, Achintya; Duttagupta, Siddhartha P

    2015-12-01

    There is a growing requirement of alpha spectroscopy in the fields context of environmental radioactive contamination, nuclear waste management, site decommissioning and decontamination. Although silicon-based alpha-particle detection technology is mature, high leakage current, low displacement threshold and radiation hardness limits the operation of the detector in harsh environments. Silicon carbide (SiC) is considered to be excellent material for radiation detection application due to its high band gap, high displacement threshold and high thermal conductivity. In this report, an alpha-particle-induced electron-hole pair generation model for a reverse-biased n-type SiC Schottky diode has been proposed and verified using technology computer aided design (TCAD) simulations. First, the forward-biased I-V characteristics were studied to determine the diode ideality factor and compared with published experimental data. The ideality factor was found to be in the range of 1.4-1.7 for a corresponding temperature range of 300-500 K. Next, the energy-dependent, alpha-particle-induced EHP generation model parameters were optimised using transport of ions in matter (TRIM) simulation. Finally, the transient pulses generated due to alpha-particle bombardment were analysed for (1) different diode temperatures (300-500 K), (2) different incident alpha-particle energies (1-5 MeV), (3) different reverse bias voltages of the 4H-SiC-based Schottky diode (-50 to -250 V) and (4) different angles of incidence of the alpha particle (0-70).The above model can be extended to other (wide band-gap semiconductor) device technologies useful for radiation-sensing application. PMID:25634901

  12. 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).

  13. 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.

  14. 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.

  15. Modelling and Dosimetry for Alpha-Particle Therapy

    PubMed Central

    Sgouros, George; Hobbs, Robert F.; Song, Hong

    2015-01-01

    As a consequence of the high potency and short range of alpha-particles, radiopharmaceutical therapy with alpha-particle emitting radionuclides is a promising treatment approach that is under active pre-clinical and clinical investigation. To understand and predict the biological effects of alpha-particle radiopharmaceuticals, dosimetry is required at the micro or multi-cellular scale level. At such a scale, highly non-uniform irradiation of the target volume may be expected and the utility of a single absorbed dose value to predict biological effects comes into question. It is not currently possible to measure the pharmacokinetic input required for micro scale dosimetry in humans. Accordingly, pre-clinical studies are required to provide the pharmacokinetic data for dosimetry calculations. The translation of animal data to the human requires a pharmacokinetic model that links macro- and micro-scale pharmacokinetics thereby enabling the extrapolation of micro-scale kinetics from macroscopic measurements. These considerations along with a discussion of the appropriate physical quantity and related units for alpha-particle radiopharmaceutical therapy are examined in this review. PMID:22201712

  16. Making A D-Latch Sensitive To Alpha Particles

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G.; Blaes, Brent R.; Nixon, Robert H.

    1994-01-01

    Standard complementary metal oxide/semiconductor (CMOS) D-latch integrated circuit modified to increase susceptibility to single-event upsets (SEU's) (changes in logic state) caused by impacts of energetic alpha particles. Suitable for use in relatively inexpensive bench-scale SEU tests of itself and of related integrated circuits like static random-access memories.

  17. 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 ?-particles in DT operation. The direct measurements of alphas are very difficult and ?-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 ?-particle source and its evolution in space and time, ?-particle energy distribution, and ?-particle losses. This paper describes how the above mentioned JET diagnostic systems could be used for ?-particle measurements, and what options exist for keeping the essential ?-particle diagnostics functioning well in the presence of intense DT neutron flux. Also, ?-particle diagnostics for ITER are discussed.

  18. Alpha particle emission in the interaction of 12C with 59Co and 93Nb at incident energies of 300 and 400 MeV

    NASA Astrophysics Data System (ADS)

    Gadioli, E.; Cavinato, M.; Fabrici, E.; Gadioli Erba, E.; Birattari, C.; Mica, I.; Solia, S.; Steyn, G. F.; Frtsch, S. V.; Lawrie, J. J.; Nortier, F. M.; Stevens, T. G.; Connell, S. H.; Sellschop, J. P. F.; Cowley, A. A.

    1999-08-01

    The results of measured inclusive double differential cross section of ? particles emitted in the interaction of 12C ions with 59Co and 93Nb at incident energies of 300 and 400 MeV are presented. The analysis of these data allows us to isolate the contributions of the different reaction mechanisms, thereby confirming previous conclusions of a comprehensive analysis of a large number of excitation function, forward recoil ranges and angular distributions of residues produced in the interaction of 12C with a target nucleus in the same mass range. In particular, the probabilities associated with ?-particle reemission following incomplete fussion processes have been reaffirmed. Several refinements to the theoretical model proposed in earlier studies of the interaction of 12C with nuclei are presented.

  19. Alpha Decay in the Complex-Energy Shell Model

    SciTech Connect

    Betan, R. Id

    2012-01-01

    Background: Alpha emission from a nucleus is a fundamental decay process in which the alpha particle formed inside the nucleus tunnels out through the potential barrier. Purpose: We describe alpha decay of 212Po and 104Te by means of the configuration interaction approach. Method: To compute the preformation factor and penetrability, we use the complex-energy shell model with a separable T = 1 interaction. The single-particle space is expanded in a Woods-Saxon basis that consists of bound and unbound resonant states. Special attention is paid to the treatment of the norm kernel appearing in the definition of the formation amplitude that guarantees the normalization of the channel function. Results: Without explicitly considering the alpha-cluster component in the wave function of the parent nucleus, we reproduce the experimental alpha-decay width of 212Po and predict an upper limit of T1/2 = 5.5 10 7 sec for the half-life of 104Te. Conclusions: The complex-energy shell model in a large valence configuration space is capable of providing a microscopic description of the alpha decay of heavy nuclei having two valence protons and two valence neutrons outside the doubly magic core. The inclusion of proton-neutron interaction between the valence nucleons is likely to shorten the predicted half-live of 104Te.

  20. Ultra-high resolution alpha particle spectroscopy using cryogenic microcalorimeters

    NASA Astrophysics Data System (ADS)

    Horansky, R. D.; Ullom, J. N.; Beall, J. B.; Doriese, W. B.; Duncan, W. D.; Ferreira, L.; Hilton, G. C.; Irwin, K. D.; Reintsema, C. D.; Vale, L.; Rabin, M. W.; Hoover, A. S.; Lamont, S. P.; Rudy, C. R.

    2007-03-01

    We have built a novel alpha particle detector using a transition edge sensor (TES) thermometer attached to a bulk superconducting absorber and have measured < 2.5 keV resolution at 5.3 MeV . We have used the microcalorimeter to measure a mixture of Pu isotopes and are able to individually resolve peaks corresponding to ^239Pu and ^240Pu which are separated by 12.9 keV. The ^240Pu/^239Pu activity ratio is a key parameter for determining whether a plutonium sample is weapons or reactor grade. Conventional silicon based detectors achieve resolutions no better than 10 keV, severely limiting current actinide assays. In addition, the microcalorimeter alpha detector has shown significantly better resolution for gamma rays. The origin of the resolution difference for gamma and alpha interactions may be due to lattice damage and is currently under study.

  1. 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.

  2. 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

  3. TFTR 60 GHz alpha particle collective Thomson Scattering diagnostic

    SciTech Connect

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

    1995-03-01

    A 60 GHz gyrotron collective Thomson Scattering alpha particle diagnostic has been implemented for the D-T period on TFM. Gyrotron power of 0.1-1 kW in pulses of up to 1 second can be launched in X-mode. Efficient corrugated waveguides are used with antennaes and vacuum windows of the TFTR Microwave Scattering system. A multichannel synchronous detector receiver system and spectrum analyzer acquire the scattered signals. A 200 Megasample/sec digitizer is used to resolve fine structure in the frequency spectrum. By scattering nearly perpendicular to the magnetic field, this experiment will take advantage of an enhancement of the scattered signal which results from the interaction of the alpha particles with plasma resonances in the lower hybrid frequency range. Significant enhancements are expected, which will make these measurements possible with gyrotron power less than 1 kW, while maintaining an acceptable signal to noise ratio. We hope to extract alpha particle density and velocity distribution functions from the data. The D and T fuel densities and temperatures may also be obtainable by measurement of the respective ion cyclotron harmonic frequencies.

  4. Nonlinear Simulations of Alpha-Particle-Driven TAE

    NASA Astrophysics Data System (ADS)

    Todo, Yasushi; Park, Hyoung-Bin

    2000-10-01

    Alpha-particle-driven toroidicity-induced Alfven eigenmodes (TAEs) were first observed in the Tokamak Fusion Test Reactor (TFTR) [Phys. Rev. Lett. 78, 2976 (1997)]. It should be noted that the estimated amplitudes of the TAEs were very small, and they persisted much longer than the typical damping time. We carry out five dimensional Fokker-Planck simulation of the alpha-particle-driven n=4 TAE in TFTR shot #103101. The parameters and the initial alpha-paritcle distribution are taken to be consistent with the experiment. The simulation is carried out with realistic collisional rates, the pitch-angle scattering rate of 1.0 [1/s] and the slowing-down rate of 2.8 [1/s]. The mode damping rate is chosen to be half of the linear growth rate. The linear growth rate is in good agreement with the NOVA-K analysis result [Phys. Plasmas 5, 4284 (1998)]. We confirm that the distribution function in the linear growth stage is consistent with the side-band resonance condition. In the simulation results the amplitude decreases monotonically after saturation. The TAE never stays at steady amplitude. This is inconsistent with the experimental results and the particle simulation results [Phys. Plasmas 6, 226 (1999)]. The reason of this discrepancy is discussed.

  5. Alpha particle transport in the presence of toroidal driftwaves

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    Transport of fusion born α particles is investigated in the presence of poloidally mode coupled ballooning type driftwaves. The onset of orbit stochasticity is understood as an overlapping of electric islands produced by the driftwaves, whose overlapping threshold is lower for the thermal particles than for the α particles (high energy particles). For the trapped particles, transport is determined by the particles' sensitive response to the fluctuation at the banana tip where the parallel velocity decreases drastically. Time dependent turbulent signals (finite ω* effects) give rise to the shift of the resonant radial locations, which again is larger for the thermal particles than the high energy particles. The transport process is influenced by the microscopic structure of the islands, which deviates from the Gaussian process. This work is supported by National Science Council of Taiwan, NSC 100-2112-M-006-021-MY3 and NCKU Top University Project.

  6. 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.

  7. 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.

  8. 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.

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

    PubMed

    Turtoi, A; Brown, I; Schlger, 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

  11. Experimental setup for studying the effects of alpha particles on zebrafish embryos

    NASA Astrophysics Data System (ADS)

    Yum, E. H. W.; Ng, C. K. M.; Lin, A. C. C.; Cheng, S. H.; Yu, K. N.

    2007-11-01

    In the present work, we have studied the feasibility to use an experimental setup based on polyallyldiglycol-carbonate (PADC) films to study effects of alpha particles on dechorionated zebrafish embryos. Thin PADC films with a thickness of 16 ?m were prepared from commercially available CR-39 films by chemical etching and used as support substrates for holding zebrafish embryos for alpha-particle irradiation. These films recorded alpha-particle hit positions, quantified the number and energy of alpha particles actually incident on the embryo cells, and thus enabled the calculation of the dose absorbed by the embryo cells. Irradiation was made at 4 h post fertilization (hpf) with absorbed doses up to 2.3 mGy. Images of the embryos at 48 hpf were examined for identification of morphologic abnormalities. The preliminary results showed that absorbed doses corresponding to the abnormally developed embryos ranged from 0.41 to 2.3 mGy, which was equivalent to 0.21-1.2 mGy in human.

  12. 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.

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Joshirao, Pranav M.; Shin, Jae Won; Kim, Do Yoon; Hong, Seung-Woo; Kolekar, Rajesh V.; Manchanda, Vijay Kumar

    2015-05-01

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

  16. The efficiency and angular sensitivity of the LR-115 nuclear track detector to alpha particles

    NASA Astrophysics Data System (ADS)

    Planini?, J.

    1992-07-01

    The LR-115 detector sensitivity coefficient was calibrated ( k = 0.0343 tr cm -2 d -1 per Bq m -3 = 0.40 cm) and detection threshold energies were determined ( E1 = 0.7 MeV, Eu = 3.86 MeV). Measurements of the alpha particle diameter ( d) showed a parabolic dependence on the incident particle energy ( E). Relationship between the detection efficiency, critical detection angle, k, d and E were derived. The emperical effective value of the critical angle was 59.

  17. Theoretical description of Long Range Alpha particles emitted during spontaneous fission

    NASA Astrophysics Data System (ADS)

    Serot, O.; Wagemans, C.; Carjan, N.

    1998-10-01

    An interpretation of the experimental data concerning the emission of Long Range Alpha (LRA) particles emitted during spontaneous fission of 238,240,242,244Pu isotopes is given. In particular, we show that the LRA emission process is strongly influenced by the spectroscopic factor (related to the ?-cluster preformation probability) and by the fission mode components of each nucleus. Furthermore, the energy transfer probability between the available deformation energy of the scissioning nucleus and the ?-particle is calculated from a sudden approximation model. Lastly, a comparison between our theoretical prediction and the experimental data allowed a determination of the Q?-value at the scission point.

  18. Preliminary experiments: High-energy alpha PIXE in archaeometry

    NASA Astrophysics Data System (ADS)

    Dupuis, Thomas; Chêne, G.; Mathis, F.; Marchal, A.; Philippe, M.; Garnir, H.-P.; Strivay, D.

    2010-06-01

    This paper describes the work realized at the "Centre Européen d'Archéométrie" to highlight the utility of high-energy alpha PIXE in the particular field of archaeometry and to introduce the developments done and to be done to complete the knowledge of high-energy alpha PIXE. It starts with the comparison of the yield and the noise background between several alpha particle beams and the comparison between alpha particle and proton beams on different thick and thin references. After, this paper depicts the developments done at the "Institut de Physique Nucléaire, Atomique et Spectroscopie" to perform such high-energy experiments, first on standards and later on cultural heritage objects. Moreover, it introduces the problematics of such beams for the quantification in PIXE by the intermediary of the knowledge of the ionization and X-ray production cross-sections and also the developments done to answer to this serious lack in the databases.

  19. Low energy particle composition. [energy spectra, particle emission - solar flares

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.

    1975-01-01

    The energy spectra and composition of the steady or 'quiet-time' particle flux, whose origin is unknown was studied. Particles and photons which are associated with solar flares or active regions on the sun were also studied. Various detection techniques used to measure the composition and energy spectra of low energy particles are discussed. Graphs of elemental abundance and energy spectra are given.

  20. 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.

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

    PubMed

    Horn, Simon; Brady, Darren; Prise, Kevin

    2015-10-01

    The use of high linear energy transfer radiations in the form of carbon ions in heavy ion beam lines or alpha particles in new radionuclide treatments has increased substantially over the past decade and will continue to do so due to the favourable dose distributions they can offer versus conventional therapies. Previously it has been shown that exposure to heavy ions induces pan-nuclear phosphorylation of several DNA repair proteins such as H2AX and ATM in vitro. Here we describe similar effects of alpha particles on ex vivo irradiated primary human peripheral blood lymphocytes. Following alpha particle irradiation pan-nuclear phosphorylation of H2AX and ATM, but not DNA-PK and 53BP1, was observed throughout the nucleus. Inhibition of ATM, but not DNA-PK, resulted in the loss of pan-nuclear phosphorylation of H2AX in alpha particle irradiated lymphocytes. Pan-nuclear gamma-H2AX signal was rapidly lost over 24h at a much greater rate than foci loss. Surprisingly, pan-nuclear gamma-H2AX intensity was not dependent on the number of alpha particle induced double strand breaks, rather the number of alpha particles which had traversed the cell nucleus. This distinct fluence dependent damage signature of particle radiation is important in both the fields of radioprotection and clinical oncology in determining radionuclide biological dosimetry and may be indicative of patient response to new radionuclide cancer therapies. PMID:26116906

  2. Angular Momentum Transport and Proton-Alpha-Particle Differential Streaming in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Li, Bo; Habbal, Shadia Rifai; Li, Xing

    2007-05-01

    The interplay between the proton-alpha-particle differential flow speed, v?p, and angular momentum transport in the solar wind is explored by using a three-fluid model. The force introduced by the azimuthal components is found to play an important role in the force balance for ions in interplanetary space, bringing the radial flow speeds of protons and alpha particles closer to each other. For the fast solar wind, the model cannot account for the decrease of v?p observed by Helios between 0.3 and 1 AU. However, it can reproduce the v?p profile measured by Ulysses beyond 2 AU, if the right value for v?p is imposed at that distance. In the slow wind, the effect of solar rotation is more pronounced if one starts with the value measured by Helios at 0.3 AU: a relative change of 10%-16% is introduced in the radial speed of the alpha particles between 1 and 4 AU. The model calculations show that, although alpha particles consume only a small fraction of the energy and linear momentum fluxes of protons, they cannot be neglected when considering the proton angular momentum flux Lp. In most examples, it is found that Lp is determined by v?p for both the fast and the slow wind. In the slow solar wind, the proton and alpha particle angular momentum fluxes Lp and L? can be several times larger in magnitude than the flux carried by the magnetic stresses LM. While the sum LP=Lp+L? is smaller than LM, for the modeled fast and slow wind alike, this result is at variance with the Helios measurements.

  3. 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.

  4. 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 associated with very young scarps identified in the lunar highlands [4] and are believed to indicate continued global contraction. Such quakes could open fissures leading to the release of gases that are trapped below the surface. The detection of radon-222 outgassing events at the margins of Fecunditatis basin was surprising because the observed surface distribution of uranium and thorium do not extend sufficiently eastward to cover Fecunditatis. If the Apollo detections prove sound, then those alpha particle emissions indicate substantial subsurface concentrations of uranium-238 within Fecunditatis. A primary goal of the APS was to map gas-release events, thus allowing both an appraisal of the current level of tectonic activity on the Moon and providing a probe of subsurface uranium concentrations.

  5. Ultrahigh-energy particles from cosmic strings

    SciTech Connect

    Bhattacharjee, P. . Astronomy and Astrophysics Center Fermi National Accelerator Lab., Batavia, IL )

    1991-02-01

    The idea of production of ultrahigh-energy particles in the present universe due to annihilation or collapse of topological defects is discussed. Topological defects, formed in symmetry-breaking phase transitions in the early universe, can survive till today owing to their topological stability. However, under certain circumstances, topological defects may be physically destroyed. When topological defects are destroyed, the energy contained in the defects can be released in the form of massive gauge- and Higgs bosons of the underlying spontaneously broken gauge theory. Subsequent decay of these massive particles can give rise to energetic particles ranging up to an energy on the order of the mass of the original particles released from the defects. This may give us a natural'' mechanism of production of extremely energetic cosmic ray particles in the universe today, without the need for any acceleration mechanism. To illustrate this idea, I describe in detail the calculation of the expected ultrahigh-energy proton spectrum due to a specific process which involves collapse or multiple self-intersections of a class of closed cosmic string loops formed in a phase transition at a grand unification energy scale. I discuss the possibility that some of the highest-energy cosmic ray particles are of this origin. By comparing with the observational results on the ultrahigh-energy cosmic rays, we derive an upper limit to the average fraction of the total energy in all primary'' cosmic string loops that may be released in the form of particles due to collapse or multiple self-intersections of these loops. No nuclei such as {alpha}'s or Fe's are in the spectrum. 43 refs., 3 figs.

  6. 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.

  7. 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.

  8. Alpha Particle Scintillation Analysis in High Pressure Argon Using Photomultiplier Tubes

    NASA Astrophysics Data System (ADS)

    Saenz, Daniel

    2007-10-01

    We may very likely discover dark matter by studying what it is not rather than what it is. By better understanding how ordinary matter interacts with other ordinary matter, dark matter interactions should stand out. That's why physicists such as my mentor, Dr. James White, are studying the affects of scintillation events due to ionizing high pressure noble gasses with gamma rays, alpha particles, neutrons, and electrons. My project has been using photomultiplier tubes and a high pressure pure argon gas chamber to study scintillation events. We have focused mainly on alpha particles (as well as gamma rays from decaying Cobalt-57 and neutrons from a 4-MeV proton accelerator). The resulting shape of the events, the ratios of secondary to primary scintillation, and the ratios of triplet state to singlet state decay energies helps catalog ordinary matter interactions.

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

    PubMed

    Giesen, U; Beck, J

    2014-10-01

    The increasing importance of ion beams in cancer therapy and the lack of experimental data for W-values for protons and heavy ions in air require new measurements. A new experimental set-up was developed at PTB and consistent measurements of W-values in argon, nitrogen and air for protons and alpha particles with energies from 0.7 to 3.5 MeV u(-1) at PTB, and for carbon ions between 3.6 and 7.0 MeV u(-1) at GSI were carried out. This publication concentrates on the measurements with protons and alpha particles at PTB. The experimental methods and the determination of corrections for recombination effects, beam-induced background radiation and additional effects are presented. PMID:24262925

  10. 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)

  11. 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 induction of bone cancer. In addition, new data are presented on the location of bone-marrow stem cells within the marrow cavities of trabecular bone of the pelvis. All results presented in this work may be applied to occupational exposures, but their greatest utility lies in dose assessments for alpha-emitters in molecular radiotherapy.

  12. 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

  13. 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.

  14. Determination of the absolute alpha-particle emission probabilities of 237Np

    PubMed

    Sibbens; Denecke

    2000-03-01

    In the framework of the EUROMET project No. 416, decay scheme data of 237Np were measured by alpha-particle spectrometry. Emission probabilities of alpha-particles and gamma-rays were determined in the past at IRMM. After improvements of the detector system and the electron bending magnet the alpha-particle measurements have been repeated. As a result, the absolute emission probabilities of 20 alpha-particle transitions were obtained with a significant lower uncertainty. Among those transitions already known, five new were found. PMID:10724391

  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. Detection of lost alpha particle by concealed lost ion probe

    SciTech Connect

    Okamoto, A.; Kitajima, S.; Sasao, M.; Isobe, M.

    2010-10-15

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

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

    SciTech Connect

    Cheng, C.Z.; Budny, R.; Chen, L.

    1995-01-01

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

  18. Observation of the production of 8Li fragments in alpha-particle interaction with photoemulsion nuclei

    NASA Astrophysics Data System (ADS)

    Dubinina, V. V.; Egorenkova, N. P.; Pozharova, E. A.; Smirnitsky, V. A.

    2015-11-01

    About 37 × 103 events of alpha-particle interaction with photoemulsion nuclei were scanned. Among them, 339 events involving the production of a 8Li fragment and the decay 8Li →8 Be → 2α were found. Over the region extending up to 60 MeV, the energy spectrum of 8Li is consistent with the mechanism of fragment evaporation from an excited nucleus. At 8Li energies in excess of 70 MeV, the existence of a 8Li fragment in target nuclei before their interaction with a projectile is possibly observed with a probability of about 10-5.

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

    SciTech Connect

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

    2011-11-01

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

  20. Characterization of an alpha-particle irradiator for individual cell dosimetry measurements.

    PubMed

    Wang, Steven J; Whitlock, Jenny L; Soyland, Christina; Hassfjell, Sindre P; Stinchcomb, Thomas G; Rotmensch, Jacob; Reba, Richard C; Roeske, John C

    2003-06-01

    A computer-controlled, alpha-particle irradiator is described that allows for the measurement of the number and location of alpha-particle hits to individual cell nuclei, and subsequent scoring of cell survival. Cells are grown on a track-etch material (LR 115) and images are obtained of the cells prior to irradiation. The cells are then irradiated from below by a planar, collimated Am-241 source. The exposure time is varied so that the average number of hits to cell nuclei ranges from 0 to 3. After cell survival has been scored, images of the etched material are obtained and spatially registered to the original cell images. The etched images and cellular images are superimposed allowing for the determination of the number and position of hits to individual cell nuclei. This paper characterizes the irradiator including the energy and fluence of the incident alpha particles. Additionally, we describe the sources of uncertainty associated with this experiment, including the cell dish repositioning and cell migration during scanning and irradiation. PMID:12954131

  1. 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) ? radiation can initiate this pathway, independent of DNA damage, via the cell membrane. Whether short-ranged, high-LET ? 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 ? particles emitted by the ?Ac-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 ?-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 ? particles using a planar ?Am 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 ?-particle traversals per cell. These data indicate that ? particles can activate the sphingomyelin pathway to induce apoptosis. PMID:21631289

  2. 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.

  3. Search for {alpha}-states in {sup 13}C via elastic resonant scattering of {alpha} particles on {sup 9}Be

    SciTech Connect

    Lombardo, I.; Campajola, L.; Rosato, E.; Spadaccini, G.; Vigilante, M.

    2013-07-18

    We will discuss new experimental data concerning the elastic resonant scattering of {alpha}-particles on {sup 9}Be nuclei at bombarding energies from 3.5 MeV up to 9.9 MeV. Several excitation functions have been obtained at different polar angles, mainly in the backward hemisphere in the centre of mass frame. Excitation functions show various anomalies that can be linked to the presence of various excited states in the {sup 13}C compound nucleus. In the literature, some of these states have been proposed to belong to rotational bands built on deformed a-cluster excited state. Unfortunately, up to date the spin-parity assignment of many of these states is doubtful. The set of excitation functions we obtained from the present experiment can contribute to improve spectroscopy of highling excited states of {sup 13}C.

  4. 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.

  5. 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

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

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

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

  7. TECHNICAL DESIGN NOTE: A very low-cost alpha-particle spectrometer

    NASA Astrophysics Data System (ADS)

    Drndarevi?, Vujo

    2008-05-01

    In this note a novel, very low-cost alpha-particle spectrometer has been described. The spectrometer's design is based on the concept of virtual instrumentation. It consists of a self-contained alpha probe connected to a PC through the USB bus and of PC application software. The probe uses a new arrangement of a large-area standard PIN photodiode and commercial off-the-shelf electronic components. The spectrometer has an energy resolution of 56 keV (239Pu) and a throughput of 103 cps. Due to its low-power consumptionnot exceeding 200 mWit can be used with laptop or palmtop computers as a portable spectrometer for field measurements.

  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) ? 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 ?-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 ?-particle traversals per cell. These data indicate that a particles can activate the sphingomyelin pathway to induce apoptosis. PMID:21631289

  9. Alpha particle detection with GaN Schottky diodes

    SciTech Connect

    Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Markov, A. V.; Kozhukhova, E. A.; Gazizov, I. M.; Kolin, N. G.; Merkurisov, D. I.; Boiko, V. M.; Korulin, A. V.; Zalyetin, V. M.; Pearton, S. J.; Lee, I.-H.; Dabiran, A. M.; Chow, P. P.

    2009-11-15

    Ni/GaN Schottky diode radiation detectors were fabricated on 3-mum-thick unintentionally doped n-GaN films grown by molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) and on 12-mum-thick undoped n-GaN layers prepared by epitaxial lateral overgrowth (ELOG). The reverse current of all detector structures was <10{sup -9} A for bias voltages necessary for detector operation, with the level of background donor doping of <10{sup 15} cm{sup -3}. With this doping level the space charge region of the Schottky diode could be extended to the entire thickness of the films. The charge collection efficiency of the detectors was close to 100% for MOCVD and ELOG detectors for alpha-particles with range comparable to the thickness of the layer. Electrical properties and deep trap spectra were also studied. The collection efficiency decreased when the concentra-tion of deep electron traps, particularly E{sub c}-0.6 eV traps, increased in MBE grown films.

  10. Fission time scale from prescission neutron, proton, and {alpha} particle multiplicities in {sup 28}Si+{sup 175}Lu

    SciTech Connect

    Ramachandran, K.; Chatterjee, A.; Navin, A.; Mahata, K.; Shrivastava, A.; Tripathi, V.; Kailas, S.; Saxena, A.; Thomas, R.G.; Kumar, Suresh; Sahu, P.K.; Nanal, V.; Pillay, R.G.

    2006-06-15

    Prescission neutron, proton, and {alpha}-particle multiplicities for the reaction {sup 28}Si+{sup 175}Lu at 159 MeV were measured simultaneously. The multiplicity data were analyzed using deformation dependent particle transmission coefficients, binding energies, and level densities to extract fission time scales and the mean deformation of the saddle-to-scission emitter. The neutron and charged particle data could be explained consistently, a better fit being obtained by considering the emission of neutrons to be favored toward larger deformation as compared to charged particles. The total fission time scale is deduced as 36-41x10{sup -21}s.

  11. 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.

  12. 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.

  13. Modification of alpha-particle emission spectrum in beam-injected deuterium-tritium plasmas

    NASA Astrophysics Data System (ADS)

    Matsuura, H.; Nakao, Y.

    2009-04-01

    The alpha (?)-particle and neutron emission spectra in a deuterium-tritium plasma accompanied with neutral-beam-injection (NBI) heating are evaluated in a consistent way by solving the Boltzmann-Fokker-Planck equations for deuteron, triton, and ?-particle simultaneously. It is shown that owing to the existence of non-Maxwellian tail component in fuel-ion distribution function due to NBI and/or nuclear elastic scattering, the generation rate of the energetic (?4 MeV) ?-particle increases significantly. When 20 MW intense deuterium beam with 1 MeV beam-injection energy is injected into an 800 m3 plasma (Te=10 keV, ne=6.21019 m-3), the enhancement of the fraction of the power carried by ?-particles with energy above 4 (3.9) MeV to total ?-particle power is almost twice (1.5 times) as much from the value for Gaussian distribution. A verification scenario for the modification of the emission spectrum by using the gamma (?)-ray-generating B9e(? ,n?)C12 reaction is also presented.

  14. A study of the effects of MeV alpha particles in PE and PVDC

    NASA Astrophysics Data System (ADS)

    Evelyn, A. L.; Ila, D.; Zimmerman, R. L.; Bhat, K.; Poker, D. B.; Hensley, D. K.

    1997-02-01

    We have mapped and studied the effects of MeV alpha-particle bombardment in polyvinylidene chloride (PVDC) and polyethylene (PE). We used 3.5 and 5.0 MeV alpha-particle incident beams and stacked polymer films to separate the contributing effects of the electronic (ɛe) and nuclear (ɛn) stopping powers. The electrical conductance and change in the chemical structures were measured by direct resistivity measurement, Raman microprobe, RBS and FTIR. The results indicate significant differences in the (ɛe) and (ɛn) effects at higher alpha-particle bombardment fluences.

  15. WIND measurements of proton and alpha particle flow and number density

    NASA Technical Reports Server (NTRS)

    Steinberg, J. T.; Lazarus, A. J.; Ogilvie, J. T.; Lepping, R.; Byrnes, J.; Chornay, D.; Keller, J.; Torbert, R. B.; Bodet, D.; Needell, G. J.

    1995-01-01

    We propose to review measurements of the solar wind proton and alpha particle flow velocities and densities made since launch with the WIND SWE instrument. The SWE Faraday cup ion sensors are designed to be able to determine accurately flow vector directions, and thus can be used to detect proton-alpha particle differential flow. Instances of differential flow, and the solar wind features with which they are associated will be discussed. Additionally, the variability of the percentage of alpha particles as a fraction of the total solar wind ion density will be presented.

  16. 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.

  17. 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.

  18. FISSION OF {sup 238}U INDUCED BY INELASTIC SCATTERING OF 120 MeV {alpha}-PARTICLES

    SciTech Connect

    Back, B.B.; Shotter, A.C.; Symons, T.J.M.; Bice, A.; Gelbke, C.K.; Awes, T.C.; Scott, D.K.

    1980-09-01

    The fission decay of {sup 238}U has been measured as function of excitation energy in inelastic scattering of 120 MeV {alpha}-particles. Total kinetic energies and masses of fission fragments were measured by the double energy method. It is observed that the total kinetic energy E{sub K} decreases and that the valley in the mass distribution is reduced when the excitation energy of the system is increased. No indication of anomalous total kinetic energy release in the region of the giant quadrupole resonance has been found. A qualitative interpretation of the data is given on the basis of a static scission point model.

  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. A continuous sampler with background suppression for monitoring alpha-emitting aerosol particles.

    PubMed

    McFarland, A R; Rodgers, J C; Ortiz, C A; Moore, M E

    1992-05-01

    A continuous air monitor has been developed that includes provisions for improving the detection of alpha-emitting aerosol particles in the presence of radon/thoron progeny that are unattached to ambient aerosol particles. Wind tunnel tests show that 80% of 10-microns aerodynamic equivalent diameter particles penetrate the flow system from the ambient air to the collection filter when the flow rate is 57 L min-1 (2 cfm) and the wind speed is 1 m s-1. Uniformity of aerosol collection on the filter, as characterized by the coefficient of variation of the areal density deposits, is less than 15% for 10-microns aerodynamic-equivalent-diameter aerosol particles. Tests with unattached radon daughters in a flow-through chamber showed that approximately 99% of the 218Po was removed by an inlet screen that is designed to collect radon daughters that are in the size range of molecular clusters. The inlet screen offers the opportunity to improve the signal-to-noise ratio of energy spectra in the regions of interest (subranges of the energy spectrum) of transuranic elements and thereby enhance the performance of background compensation algorithms. PMID:1559808

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

    SciTech Connect

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

    1992-11-01

    The stability of high-[ital 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-[ital n] TAE modes using gyrokinetic equation. The kinetic effects of energetic particles are calculated perturbatively using the ideal magnetohydrodynamic (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-[ital 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 increases linearly with the toroidal mode number [ital n] for small [ital k][sub [theta

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

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

  3. Efficiency estimation for detecting U alpha particles in solid-state nuclear track detectors.

    PubMed

    Uda, T; Iba, H

    1985-09-01

    The detection efficiencies of solid-state nuclear track detectors, made with cellulose nitrate materials (LR-115 II) or allyl diglycol carbonate (CR-39) were investigated. Detection efficiency for a surface alpha source was experimentally obtained by changing the dimensions between the detector and the source, while alpha-particle incident efficiency was calculated. The ratio of the detection efficiency to the incident efficiency was then determined. It was confirmed that the ratio for LR-115 II was dependent on energy, but for CR-39 the ratio showed almost no dependency. Considering the relationship between solid absorber thickness and detection efficiency of the surface alpha source, detection efficiencies of U in various metals were estimated. The efficiency for U contained in Al and Fe was proposed as 16% for LR-115 II and 22% for CR-39. Using these efficiencies, amounts of U in some Al and Fe ingots were determined. These agreed with concentrations obtained by neutron-activation analysis with deviations of less than 15%. PMID:4030336

  4. 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 Alfvn/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 ?}/T {sub p} (T {sub ??}/T {sub ?p}) when the alpha proton differential flow velocity is small, where T {sub ?} and T {sub p} (T {sub ??} 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.

  5. Coaxial charged particle energy analyzer

    NASA Technical Reports Server (NTRS)

    Kelly, Michael A. (Inventor); Bryson, III, Charles E. (Inventor); Wu, Warren (Inventor)

    2011-01-01

    A non-dispersive electrostatic energy analyzer for electrons and other charged particles having a generally coaxial structure of a sequentially arranged sections of an electrostatic lens to focus the beam through an iris and preferably including an ellipsoidally shaped input grid for collimating a wide acceptance beam from a charged-particle source, an electrostatic high-pass filter including a planar exit grid, and an electrostatic low-pass filter. The low-pass filter is configured to reflect low-energy particles back towards a charged particle detector located within the low-pass filter. Each section comprises multiple tubular or conical electrodes arranged about the central axis. The voltages on the lens are scanned to place a selected energy band of the accepted beam at a selected energy at the iris. Voltages on the high-pass and low-pass filters remain substantially fixed during the scan.

  6. 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.

  7. 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.

  8. Alpha-Particle Decay Measurements for Very Long - Quasi-Stable Isotopes of Neodymium, Platinum, Samarium and Uranium.

    NASA Astrophysics Data System (ADS)

    Al-Bataina, Barakat Atwan Mofaddi

    Half lives and alpha-particle energies of very long-lived (10('9) - 10('16) years) quasi-stable nuclei with A > 140 have been measured using a cylindrical gas -flow proportional counter. The source materials were deposited on the inner surface of the cathode cylinder over an area of about 1700 cm('2). Low-level counting techniques were developed with emphasis on the reduction of background from external and internal sources. External background can be reduced by shielding and rise-time discrimination. Internal background from (alpha)-contaminants in the counter materials and the source materials was a major source of background and was studied in detail. Stainless steel was found to be superior to brass and aluminum. Ultrapure source materials had to be superior to brass and aluminum. Ultrapure source materials had to be used. Half lives and energies were measured for ('144)Nd, ('147)Sm, ('190)Pt, ('234)U, ('235)U, ('238)U, and lower limit was obtained for ('148)Sm. Reduced alpha widths which describe the preformation of (alpha)-clusters in the nuclear surface were obtained for the entire region N > 82 to Z (LESSTHEQ) 84 from all available data. Systematic trends which reflect upon the nuclear structure of these nuclei make it possible to predict new short-lived proton-rich alpha emitters as well as additional very long-lived quasi-stable alpha emitters.

  9. 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.

  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. A new method for evaluating radon and thoron alpha-activities per unit volume inside and outside various natural material samples by calculating SSNTD detection efficiencies for the emitted alpha-particles and measuring the resulting track densities.

    PubMed

    Misdaq, M A; Aitnouh, F; Khajmi, H; Ezzahery, H; Berrazzouk, S

    2001-08-01

    A Monte Carlo computer code for determining detection efficiencies of the CR-39 and LR-115 II solid-state nuclear track detectors (SSNTD) for alpha-particles emitted by the uranium and thorium series inside different natural material samples was developed. The influence of the alpha-particle initial energy on the SSNTD detection efficiencies was investigated. Radon (222Rn) and thoron (220Rn) alpha-activities per unit volume were evaluated inside and outside the natural material samples by exploiting data obtained for the detection efficiencies of the SSNTD utilized for the emitted alpha-particles, and measuring the resulting track densities. Results obtained were compared to those obtained by other methods. Radon emanation coefficients have been determined for some of the considered material samples. PMID:11393761

  12. The continuum and the alpha-particle formation

    NASA Astrophysics Data System (ADS)

    Dodig-Crnkovic, Gordana; Janouch, F. A.; Liotta, R. J.; Xiaolin, Zhao

    1988-04-01

    The absolute ?-decay width of 212Po is calculated within a harmonic oscillator representation. Clustering features induced by the nuclear interaction appear by considering a large configuration space. The role of the neutronproton interaction is analysed and a reasonable account of the experimental alpha-decay width is given.

  13. Reexamination of the {alpha}-{alpha}''fishbone'' potential

    SciTech Connect

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

    2011-09-15

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

  14. The optical, wettability and hardness properties of polyethylene improved by alpha particle irradiations.

    PubMed

    Zaki, M F

    2015-12-01

    In this work, the optical, chemical and morphological changes of alpha irradiated low-density polyethylene (LDPE) were investigated using UV/Vis spectroscopy, Fourier transform infrared spectrometer (FTIR) and scanning electron microscope (SEM). In addition to, the wettability and Vicker's Micro-Hardness have been studied using the contact angle measurements and Vicker's Micro-Hardness tester. The polymer samples are irradiated with different times of alpha particles. UV/Vis spectra show that the absorbance increases with increase in the irradiation time and the absorption edge shifts toward the higher wavelength. This indicates to a decrease in the optical band gap energy and an increase in number of carbon clusters. FTIR analysis reveals that the formation of CH groups and O-H has been observed and also indicated the presence of unsaturations due to vinyl end groups in the irradiated samples. Noticeable decreases in the contact angle of irradiated samples were observed. This decrease reflects the increase in the wettability and consequently the surface free energy. This behavior is due to the formation of oxidized layer on the irradiated surface polymer. Induced increasing in the Vicker's hardness in the irradiated polymers was observed, that can be attributed to crosslinking effects in the chain of the polymers. PMID:26184467

  15. 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.

  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. Charge exchange recombination spectroscopy for {alpha} particles colliding with hydrogen atoms

    SciTech Connect

    Liu, X. J.; Xiao, B. J.; Liu, L.; Wang, J. G.; Qu, Y. Z.

    2011-10-15

    The intensities of charge exchange recombination spectroscopy (CXRS) of {alpha} particles colliding with the hydrogen atoms in the neutral beam injection (NBI) are calculated by solving the rate equations including electron collision processes in the quasi-static state approximation. The effects of electron collision processes on the CXRS signals for He{sup +}(n=4{yields}3) at {lambda}=468.6nm in various plasma conditions are discussed, and it is found that these effects can increase the CXRS signals by 50% for electron density n{sub e}{>=}10{sup 15}cm{sup -3}. However, their importance decreases with the increasing of NBI energy. For the short pulse of NBI, the influences of electron collision processes can be neglected for n{sub e}{<=}10{sup 14}cm{sup -3}. Furthermore, the spectra of He{sup +}(n{yields}n') are present for the plasma conditions of HT-7 tokamak.

  18. 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.

  19. The track interaction model for alpha particle induced thermoluminescence supralinearity: dependence of the supralinearity on the vector properties of the alpha particle radiation field

    NASA Astrophysics Data System (ADS)

    Horowitz, Y. S.; Rosenkrantz, M.; Mahajna, S.; Yossian, D.

    1996-01-01

    Thermoluminescence (TL) - fluence response characteristics for peaks 5, 7, 8 and 9 in LiF:Mg,Ti (TLD-100; Harshaw/Bicron) were measured for 5 MeV alpha particles, in both `non-parallel' and `near-parallel' geometries,and for 1 MeV alpha particles in `near-parallel' geometry. The onset of supralinearity in the non-parallel configuration is always at a significantly lower fluence (by approximately a factor of five) than in the nearly parallel configuration. This dependence of the onset of supralinearity on the vector properties of the alpha particle radiation field is interpreted as `proof positive' of the dominant importance of track interaction effects in the linear/supralinear behaviour of the glow peaks of TLD-100. A mathematical expression for the linear/supralinear behaviour for heavy charged particles in near-parallel geometry has been developed and fitted to the TL - fluence response curves. The model incorporates both possibilities of electron and hole diffusion in the glow curve heating stage as well as the contribution to the supralinearity of all the participating nearest-neighbour track interactions. The model is capable of yielding excellent fits to the experimental data; the inclusion of hole diffusion and retrapping is preferred to predict the very abrupt transition from linear to supralinear behaviour for the high-temperature peaks.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    Part of the energy of the Lower Hybrid (LH) waves may be absorbed by the ? 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 ?? of LH waves due to ? particles. Results show that, the ?? increases with the parallel refraction index n? while deceases with increasing the frequency of LH waves ?LH over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of ?? when ne?81019m-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, ? ? 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.

  1. 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 ? 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 ?{sub ?} of LH waves due to ? particles. Results show that, the ?{sub ?} increases with the parallel refraction index n{sub ?} while deceases with increasing the frequency of LH waves ?{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 ?{sub ?} when n{sub e}?810{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, ? ? 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.

  2. 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.

  3. 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.

  4. Monte Carlo study of alpha (?) particles transport in nanoscale gallium arsenide semiconductor materials

    NASA Astrophysics Data System (ADS)

    Amir, Haider F. Abdul; Chee, Fuei Pien

    2012-09-01

    Space and ground level electronic equipment with semiconductor devices are always subjected to the deleterious effects by radiation. The study of ion-solid interaction can show the radiation effects of scattering and stopping of high speed atomic particles when passing through matter. This study had been of theoretical interest and of practical important in these recent years, driven by the need to control material properties at nanoscale. This paper is attempted to present the calculations of final 3D distribution of the ions and all kinetic phenomena associated with the ion's energy loss: target damage, sputtering, ionization, and phonon production of alpha (?) particle in Gallium Arsenide(GaAs) material. This calculation is being simulated using the Monte Carlo simulation, SRIM (Stopping and Range of Ions in Matter). The comparison of radiation tolerance between the conventional scale and nanoscale GaAs layer will be discussed as well. From the findings, it is observed that most of the damage formed in the GaAs layer induced by the production of lattice defects in the form of vacancies, defect clusters and dislocations. However, when the GaAs layer is scaled down (nanoscaling), it is found that the GaAs layer can withstand higher radiation energy, in term of displacement damage.

  5. Tetraethyl ammonium hydroxide (TEAH) as etchant of CR-39 for the determination of fluence of alpha particles

    NASA Astrophysics Data System (ADS)

    Joshirao, Pranav M.; Vyas, Chirag K.; Eappen, K. P.; Shin, Jae Won; Hong, Seung-Woo; Manchanda, Vijay K.

    2014-04-01

    Choice of chemical etchant and temperature are pivotal to the successful employment of organic/polymeric solid state nuclear track detectors for determining the fluence of charged particles like protons, alpha and other heavy ions. Poly(diethyleneglycol-bis-(allylcarbonate)) (CR-39) is one of the most sensitive detectors for monitoring the alpha particles but suffers from the drawback of long etching period. An attempt has been made in the present work to investigate a mixture, 20% (v/v) tetraethylammonium hydroxide (40%) - 80% NaOH (6 M) (TEAH-NaOH) at varying temperature as an alternate etchant. It was found that bulk/track etch rate increased and as a consequence etching time decreased significantly (about 10 times) when the mixture was used at 80 C. Mechanistically, improved efficiency of TEAH-NaOH was attributed to its larger organophilicity and lower etching activation energy as compared to NaOH.

  6. Fire hose instability driven by alpha particles in the solar wind

    NASA Astrophysics Data System (ADS)

    Matteini, Lorenzo; Hellinger, Petr; Schwartz, Steven J.; Landi, Simone

    2015-04-01

    We discuss the dynamics of fire hose parallel instability driven by anisotropic alpha particles in a plasma with typical solar wind composition (n? = 5%ne). We show, for the first time, the liner and nonlinear dynamics of the instability by means of hybrid numeric simulations, highlighting its dependence on the main plasma parameters, including the relative drift between the alphas and the main proton population. Our results confirm that the parallel fire hose instability can be efficiently excited by anisotropic distribution of the less abundant alpha particles, even when the rest of the plasma (electrons and protons) is Maxwellian. Moreover, our finding suggest that the dynamics driven by the alphas can also influence the properties of the protons. In particular the instability is found to significantly affect the evolution of the alpha-proton drift, constraining its final intensity to values smaller than the local Alfvn speed, as observed in the solar wind far from the Sun. When simulations with both species initially anisotropic are performed, we find a coexistence of the fire hose wave activity excited by both ions, leading to final stable configurations which reflect the marginal stability state of each species. As a consequence, when observed in the commonly used (?||,T?/T||) plane, alpha particles and protons are seen to saturate in different regions of the parameter space. This property is in very good agreement with recent solar wind in situ observations and strongly suggests that those instabilities play a role in regulating the anisotropy solar wind ions.

  7. A study of the effects of MeV alpha particles in PE and PVDC

    SciTech Connect

    Evelyn, A.L.; Ila, D.; Zimmerman, R.L.; Bhat, K.; Poker, D.B.; Hensley, D.K.

    1997-02-01

    We have mapped and studied the effects of MeV alpha-particle bombardment in polyvinylidene chloride (PVDC) and polyethylene (PE). We used 3.5 and 5.0 MeV alpha-particle incident beams and stacked polymer films to separate the contributing effects of the electronic ({var_epsilon}{sub e}) and nuclear ({var_epsilon}{sub n}) stopping powers. The electrical conductance and change in the chemical structures were measured by direct resistivity measurement, Raman microprobe, RBS and FTIR. The results indicate significant differences in the ({var_epsilon}{sub e}) and ({var_epsilon}{sub n}) effects at higher alpha-particle bombardment fluences. {copyright} {ital 1997 American Institute of Physics.}

  8. 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.

  9. Particle Production at Collider Energies

    NASA Astrophysics Data System (ADS)

    Geich-Gimbel, Christoph

    High energy particle physics, which has been trying to understand and to devise new laws governing nature at per particle energies far beyond everyday energies, has entered a new episode. Having surpassed the low energy regime, where (s channel) resonance production dominantly projects onto the final state, very interesting features of the strong interaction arose at c.m. energies in the tens of GEV range, as found at the CERN Intersecting Storage Rings (ISR). One recalls the onset of hard scattering processes, which was understood as a scattering between constituents of the nucleon, hence supporting the Quark Parton Model (QPM). Surprisingly enough the total cross section started to rise again, when it was initially believed to have reached a constant value, suggesting an asymptotia. Furthermore correlations among the final state particles produced were observed, and especially long range correlations, which must reflect dynamical laws. The advent of the CERN pbar p Collider, with c.m. energies up to 900 GeV, representing a step of more than an order of magnitude in the energy available, puts one into a position to test more directly many of these new things and to prove the existence of the elusive intermediate vector bosons W and Z, thus unifying weak and electromagnetic interactions. Finally a bridge to cosmic ray results at extreme energies may be provided. Naturally quite a lot of new unanswered questions will emerge in the investigations of Collider data, since new regions bring new surprises, but this possibility should be regarded as a means of gaining new insights, rather than as a disturbance of hitherto believed regularities, of which some inevitably fail. In this spirit the following article is written.

  10. Measurements of thoron progeny concentration using apotential alpha-energy monitor in Japan

    SciTech Connect

    Yamasaki, T.; Iida, T.

    1995-06-01

    It is reported that thoron concentration in Japanese dwellings may be higher than in other dwellings. Therefore, in order to assess the risk for indoor thoron progeny, the portable potential alpha-energy monitor has been developed. The monitor detects alpha-particles from the {sup 212}Po collected on the filter using a piece of cellulose nitrate film. The detection efficiency of the alpha-particles has been estimated by Monte Carlo calculation. From the results of measurements, the mean indoor thoron progeny concentration in the dwellings was 1.5 Bq m{sup -3} (EC{sub Tn}), and ranged from 0.04 to 8.2 Bq m{sup -3}. The effects of three typical interior walls (soil-based plaster, concrete, and modern materials) on the thoron progeny supply were considered. The mean annual effective dose equivalent was 0.45 mSv. 13 refs., 5 figs., 1 tab.

  11. Charged-particle mutagenesis 2. Mutagenic effects of high energy charged particles in normal human fibroblasts

    NASA Technical Reports Server (NTRS)

    Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

    1994-01-01

    The biological effects of high Linear Energy Transfer (LET) charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 sq micrometer and 0.09 to 5.56 x 10(exp -3) sq micrometer respectively. The maximum values were obtained by Fe-56 with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(exp -5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

  12. 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.

  13. 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

  14. Cancer incidence and lifespan vs. alpha-particle dose in beagles

    SciTech Connect

    Mays, C.W.; Lloyd, R.D.; Taylor, G.N.; Wrenn, M.E.

    1987-05-01

    Young adult beagles were injected with graded activities of /sup 239/Pu, /sup 241/Am, /sup 228/Th, /sup 228/Ra or /sup 226/Ra and observed throughout their lifespans. The vast majority of the dose was from alpha particles. The lifetime incidence of bone sarcoma increased with average skeletal dose, more or less linearly up to high incidence for /sup 239/Pu, /sup 241/Am, /sup 228/Th and /sup 226/Ra, but sigmoid fashion for /sup 228/Ra. Based on average skeletal dose, the toxicity of the emitters relative to /sup 226/Ra = 1.0 was /sup 239/Pu = 16.6 +/- 4.5, /sup 241/Am = 5.4 +/- 1.6, /sup 228/Th = 8.5 +/- 2.3 and /sup 228/Ra = 2.0 +/- 0.5. At the lowest doses, the average lifespans were 97% +/- 3% of that in the controls. If beneficial effects occurred, they may have been overwhelmed by the destructiveness of the densely ionizing alpha particles. A cell nucleus 5 micron in diameter receives a mean dose of about 1 Gy (100 rad) when traversed by a single alpha particle. We found no evidence that alpha-particle doses suppressed cancer or lengthened lifespan in beagles.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  16. 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

  17. 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.

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

    PubMed

    Lyckesvrd, Madeleine Nordn; Delle, Ulla; Kahu, Helena; Lindegren, Sture; Jensen, Holger; Bck, 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 ?H2AX 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

  19. Giant multipole resonances from inelastic scattering of 152-MeV alpha particles

    SciTech Connect

    Bertrand, F.E.; Satchler, G.R.; Horen, D.J.; Wu, J.R.; Bacher, A.D.; Emery, G.T.; Jones, W.P.; Miller, D.W.; van der Woude, A.

    1980-11-01

    Giant resonance spectra have been measured for /sup 208/Pb, /sup 120/Sn, /sup 90/Zr, /sup 58/Ni, and /sup 46/Ti, using inelastic scattering of 152-MeV alpha particles. In addition to some low-lying states, the spectra were analyzed to yield separate peaks for the giant quadrupole resonance and giant monopole resonance, except in /sup 46/Ti, where no evidence was found for a giant monopole resonance. The results for the monopole resonance when compared to distorted-wave Born-approximation calculations show that approx.100% ( +- 20%) of the T=0, L=0 energy weighted sum rule is depleted for nuclei with A>90. For /sup 58/Ni only 40% of the monopole sum rule is found. The excitation energy of the giant monopole resonance follows the systematic trend approx.80 A/sup -1/3/ MeV. The data are also compared with folding model calculations using Tassie transition densities and an effective interaction derived from elastic data. Good agreement was obtained for low-lying quadrupole and octopole excitations, but this model yields considerably too little cross section for the monopole resonance. This probably indicates a deficiency in the Tassie model breathing mode transition density.

  20. Charged-particle mutagenesis II. Mutagenic effects of high energy charged particles in normal human fibroblasts

    NASA Technical Reports Server (NTRS)

    Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

    1994-01-01

    The biological effects of high LET charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 micrometer2 and 0.09 to 5.56 x 10(-3) micrometer2, respectively. The maximum values were obtained by 56Fe with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(-5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

  1. Map model for nonlinear alpha particle interaction with toroidal Alfven waves

    SciTech Connect

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

    1992-09-01

    A map model has been developed for studying the nonlinear interaction of alpha particles with the toroidal Alfven eigenmodes. The map is constructed by assuming a linear interaction during a single poloidal transit, which allows the study of the nonlinear interaction over many transits. By using this map, analytic expressions are obtained for the particle nonlinear bounce frequency, and the wave amplitude threshold for the onset of particle orbit stochasticity. The map model can also facilitate self-consistent simulations which incorporate the time variation of the waves.

  2. Confined alpha particle diagnostic system using an energetic He{sup 0} beam for ITER

    SciTech Connect

    Sasao, M.; Shinto, K.; Isobe, M.; Nishiura, M.; Kaneko, O.; Wada, M.; Walker, C. I.; Kitajima, S.; Okamoto, A.; Sugawara, H.; Takeuchi, S.; Tanaka, N.; Aoyama, H.; Kisaki, M.

    2006-10-15

    The beam neutralization system for measurement of the spatial and velocity distributions of alpha particles of ITER plasmas was studied. As forward angle detection against the beam injection direction is required for effective neutralization, arrangement of the measurement system using possible ports in ITER configuration is proposed. The count rate of neutralized alpha particles produced by the double charge exchange interaction with energetic He{sup 0} beam particles injected is estimated. The ratios of signal to neutron-induced noise are evaluated. When a He{sup 0} beam produced by autodetachment from a 1-1.5 MeV He{sup -} beam of 10 mA is injected, the signal to noise ratio becomes greater than 1 at {rho}<0.4, even without beam modulation. Usage of a lock-in technique at the frequency of radio-frequency quadrapole accelerator will make measurement at the outer region possible.

  3. Analysis of {sup 90}Sr and alpha-particle emitters on air filters and swipe samples using a liquid scintillation counter with alpha/beta discrimination

    SciTech Connect

    Cooper, E.L.; Cox, J.M.; Workman, W.J.

    1998-12-31

    The capabilities of a Quantulus{trademark} model 1220 Liquid Scintillation Counter (LSC) for rapidly analyzing alpha-particle emitters and {sup 90}Sr on air filters and swipe samples have been studied. Counting conditions were established and the instrument was calibrated using quench standards of {sup 90}Sr/Y and {sup 241}Am prepared on membrane filters. A LOTUS{trademark} template was developed to analyze the spectra. The data were used to develop a method for estimating the optimum pulse-shape analysis parameter based on linear fits to the quench parameter. Linear fits were also used to estimate window settings for {sup 90}Sr and {sup 90}Y, the Sr/Y ratio and the counting efficiencies. The linear fits have been incorporated into the template so that they are all done automatically when the quench parameter is entered. Analysis of the spectra from a sample can be done in a matter of minutes. Sample preparation simply involves transferring the filter to a scintillation vial and adding cocktail. Since the counting efficiencies of the LSC are high, counting times of an hour or less can be employed. The study showed that the method produces results that are sufficiently reliable for air filters and swipe samples. This methodology was used to analyze swipe samples from CANDU{reg_sign} nuclear stations. The results revealed complex beta-particle spectra with a number of components present. However, {sup 90}Y could be estimated from the high-energy component, which was less abundant than the low and intermediate energy components. The swipe samples contained much less alpha- than beta-particle activity.

  4. The alpha channeling effect

    NASA Astrophysics Data System (ADS)

    Fisch, N. J.

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Drschel, 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.

  6. 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 ?/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.

  7. 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

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

    PubMed Central

    Al-Taii, 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 (020 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 Cheungs 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 Cheungs 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

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

    SciTech Connect

    Sasao, Mamiko; Wada, Motoi; Isobe, Mitsutaka

    2014-08-21

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

  10. 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.}

  11. Upgrades to the Tri Alpha Energy Neutron Detector System [1

    NASA Astrophysics Data System (ADS)

    Garate, Eusebio; Allfrey, Ian; Valentine, Travis; Patel, Vijay; Smirnov, Artem; Korepanov, Sergey; Clary, Ryan; Thompson, Matthew

    2012-10-01

    We are implementing additional scintillator based neutron detectors on the Tri-Alpha Energy C2 system. The current He3 and scintillator detectors are used to estimate the total neutron emission from C2 and the corresponding ion temperature. The new detectors consist of BC-408 scintillator rod directly coupled to a Hamamatsu fine mesh PMT which can be placed in a magnetic field up to 1.5T with little loss in gain. The photocathode of the PMT is gated in order to avoid saturation effects due to high neutron flux during the collision of the compact toroids that form the C2 field reversed configuration. The detectors will be used to observe deuterium beam slowing down times in the C2 target plasma and to correlate neutron detection with C2's neutral particle analyzers, bolometers and fast magnetic probes. We will present a schematic of the detectors and preliminary results. [4pt] [1] E. Ruskov, et al., TAE neutron detectors and some physics results, Bull. Am. Phys. Soc. 55, 15, GP9.00103 (2010).

  12. Alpha particle induced gamma yields in uranium hexafluoride

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  13. High-repetition CO{sub 2} laser for collective Thomson scattering diagnostic of {alpha} particles in burning plasmas

    SciTech Connect

    Kondoh, T.; Hayashi, T.; Kawano, Y.; Kusama, Y.; Sugie, T.; Miura, Y.; Koseki, R.; Kawahara, Y.

    2006-10-15

    A high-repetition and high-energy transversely excited atmospheric carbon dioxide (CO{sub 2}) laser for a collective Thomson scattering (CTS) diagnostic has been developed to establish a diagnostic method of confined {alpha} particles in burning plasmas. To excite a single-transverse and single-longitudinal mode, a continuous wave seed laser was injected to an unstable resonator with a cavity length of {approx}4.4 m. Pulse energy of 10 J with a repetition rate of 10 Hz has been achieved in the single-mode operation. Pulse energies of 18 J with a repetition rate of 10 Hz and 36 J with single shot operation have also been achieved in the multimode operation. These results give a prospect for the CTS diagnostic on International Thermonuclear Experimental Reactor (ITER), which requires single-mode energy of 20 J with repetition rate of 40 Hz.

  14. 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.

  15. Preferential heating and acceleration of alpha particles by Alfvn-cyclotron waves.

    PubMed

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

    2009-05-01

    Preferential heating and acceleration of heavy ions in the solar wind and corona represent a long-standing theoretical problem in space physics, and are distinct experimental signatures of kinetic processes occurring in collisionless plasmas. We show that fast and slow ion-acoustic waves (IAW) and transverse waves, driven by Alfvn-cyclotron wave parametric instabilities can selectively destroy the coherent fluid motion of different ion species and, in this way lead to their differential heating and acceleration. Trapping of the more abundant protons by the fast IAW generates a proton beam with drift speed of about the Alfvn speed. Because of their larger mass, alpha particles do not become significantly trapped and start, by conservation of total ion momentum, drifting relative to the receding bulk protons. Thus the resulting core protons and the alpha particles are differentially heated via pitch-angle scattering. PMID:19518788

  16. Survival and yields of chromosome aberrations in hamster and human lung cells irradiated by alpha particles

    SciTech Connect

    Simmons, J.A.; Cohn, P.; Min, T.

    1996-02-01

    The effects of {alpha}-particle irradiation on hamster and human lung cells have been studied. In both cases two end points were taken, cell death and the induction of chromosome aberrations. The hamster cells were common stock V79 cells; the human ones were freshly derived from fetal material. For both types of cells, the survival curves could be described by straight lines in the conventional exponential plot, with values of D{sub 0} of 0.78 and 0.37 Gy for the hamster and human cells, respectively. The rate of induction of chromosome aberrations could also be described by straight lines with slopes of 0.30 and 0.62 aberration per cell per gray. Thus, for this second end point also, it appears that human cells are twice as sensitive to the effects of {alpha}-particle irradiation as hamster cells. 30 refs., 3 figs., 2 tabs.

  17. Internal Measurements Of Alpha Particle Driven Toroidal Alfvn Eigenmodes in TFTR

    NASA Astrophysics Data System (ADS)

    Nazikian, Raffi

    1997-11-01

    Alpha-particle-driven Toroidal Alfvn Eigenmodes (?-TAEs) have routinely been observed in TFTR DT plasmas with reduced central magnetic shear and elevated central safety factor [q(0)>1]. [R. Nazikian et al., Phys. Rev. Lett., 78 (1997) 2976] These results are important for benchmarking theory used to extrapolate to reactor relevant conditions. However until recently, detailed comparison of theory and experiment was not possible due to inadequate information on the equillibrium profiles, mode location and energetic particle distribution. In a recent set of experiments on TFTR we have obtained the first internal measurements of the radial structure of ?-TAEs, together with the plasma equillibrium and energetic particle distributions. Measurements indicate that ?-TAEs with toroidal mode numbers n=1-6 occur in the region 0.2alpha particles induced by ?-TAEs, although there is no indication of alpha loss. [M.P. Petrov et al., DPP77] Guide center simulations including the effects of toroidal field ripple, pitch angle scattering, particle slowing down and TAE mode-particle interactions are used to explore the dominant mechanisms for the redistribution. [R.B. White et al., Phys. Plasmas 2 (1996) 3043; M. Redi et al., EPS, Berchtesgaden, O18 (1997)

  18. 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

  19. 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-Schlter 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 ?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 ?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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Image processing tools for alpha-particle track-etch dosimetry.

    PubMed

    Roeske, John C; Soyland, Christina; Wang, Steven J; Stinchcomb, Thomas G; Hassfjell, Sindre P; Whitlock, Jenny L; Reba, Richard C; Rotmensch, Jacob

    2003-06-01

    In cases where both the source and cell geometry are well known, track-etch dosimetry allows the potential for individual cell dosimetry. However, analysis of track-etch images is both tedious and time-consuming. We describe here several image processing tools that we are using in conjunction with a track-etch based irradiator. Briefly, cells grown on LR 115 (a track-etch material) are irradiated from below by a collimated, planar alpha-particle source. Prior to irradiation, images of the cells are obtained. A computer program reads each image and automatically determines the location of individual cells. Next, the algorithm automatically identifies the cellular and nuclear boundaries. Following irradiation, and after the cells have reached their biological endpoint (e.g., cell survival), the cell dish is etched and images are obtained of alpha-particle tracks. Using the characteristic background pattern in the LR 115, the etched images are spatially registered to the original images. These two sets of images are then superimposed to create a composite image of the cells and associated alpha-particle tracks. Incorporating this tool into our irradiation scheme will enable more efficient analysis of the large amounts of data that are essential in assessing biological endpoints. PMID:12954129

  5. The calibration of photographic and spectroscopic films: The response of 2aO film to small dosages of alpha particles from 3/10th's rad to 8 rads at energy levels 153 MeV, 79 MeV and 47 MeV

    NASA Technical Reports Server (NTRS)

    Hammond, E. C., Jr.; Peters, Kevin; Stober, AL

    1984-01-01

    The 2aO film, pre-exposed to a series of neutral density filters which on development under standard conditions will produce the standard H-D curve for that film, were then exposed to Alpha paricles with a dose range of 3/10ths rads to 8 rads while varying the energy of the particles using 153 MeV, 70 MeV, and 47 MeV, respectively. An analysis of the film shows that the 3/10th rad dose produces the lowest optical density changes at 70 MeV and 47 MeV. While the optical density readings for the darker patterns seem to oscillate and decrease when exposed to radiation dosages of 3/10th rads to 8 rads.

  6. Alpha Channeling in Rotating Plasma with Stationary Waves

    SciTech Connect

    A. Fetterman and N.J. Fisch

    2010-02-15

    An extension of the alpha channeling effect to supersonically rotating mirrors shows that the rotation itself can be driven using alpha particle energy. Alpha channeling uses radiofrequency waves to remove alpha particles collisionlessly at low energy. We show that stationary magnetic fields with high n? can be used for this purpose, and simulations show that a large fraction of the alpha energy can be converted to rotation energy.

  7. 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

  8. 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 1.91016 cm-3 nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.61010 to 9.21011 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 1.71016 to 1.11016 cm-2 at approximately 0.70 ?m 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 648070 cm-1. Alpha-particle irradiation introduced two electron traps (E0.39 and E0.62), with activation energies of 0.390.03 eV and 0.620.08 eV, respectively. The E0.39 as attribute related to silicon or carbon vacancy, while the E0.62 has the attribute of Z1/Z2.

  9. 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.

  10. Interaction of alpha particle beams with Fe-based and FeNi-based glassy ferromagnets

    SciTech Connect

    Sorescu, M.; Barb, D.

    1996-12-31

    Samples of Fe{sub 78}B{sub 13}Si{sub 9} and Fe{sub 40}Ni{sub 38}Mo{sub 4}B{sub 18} metallic glasses were irradiated with alpha particle beams (W = 2.8 MeV) using radiation doses of 10{sup 16} and 10{sup 17} cm{sup {minus}2}. Irradiation-induced effects on the magnetic texture and phase composition of alloy samples were studied by Moessbauer spectroscopy. Related morphological changes and resultant crystalline precipitates were characterized by scanning electron microscopy. The evolution of phases and microstructure during the radiation-induced amorphous-to-crystalline transformation was found to depend on the particle flux and sample composition. The lowest radiation dose employed was found to be more effective in inducing amorphous-to-crystalline transformations in both ferromagnetic alloys studied. In addition, the FeNi-based amorphous system investigated was found to be more stale than the Fe-based metallic glass, exposed to the same particle-beam irradiation conditions. By stimulating unconventional pathways for the crystallization process, the interaction of alpha particle beams with glassy ferromagnets offers unique opportunities to understand the fundamentals of nucleation and growth in amorphous magnets.

  11. 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 (?)-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 ?-particles. Methods Peripheral blood mononuclear cells (PBMCs) were used to identify sensitive and robust gene-based biomarkers of ?-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 ?-particles or X-rays using quantitative real-time PCR. This 29 gene panel was responsive in the ?-particle exposed WBCs and was shown to exhibit differential fold-changes compared to X-irradiated cells, though no ?-particle specific transcripts were identified. Conclusion Current gene panels for photon radiation may also be applicable for use in ?-particle radiation biodosimetry. PMID:25017500

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

    SciTech Connect

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

    1998-04-16

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

  13. 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

  14. The new Athena alpha particle X-ray spectrometer for the Mars Exploration Rovers

    NASA Astrophysics Data System (ADS)

    Rieder, R.; Gellert, R.; Brckner, J.; Klingelhfer, G.; Dreibus, G.; Yen, A.; Squyres, S. W.

    2003-11-01

    The new alpha particle X-ray spectrometer (APXS) is part of the Athena payload of the two Mars Exploration Rovers (MER). The APXS sensor head is attached to the turret of the instrument deployment device (IDD) of the rover. The APXS is a very light-weight instrument for determining the major and minor elemental composition of Martian soils, rocks, and other geological materials at the MER landing sites. The sensor head has simply to be docked by the IDD on the surface of the selected sample. X-ray radiation, excited by alpha particles and X rays of the radioactive sources, is recorded by a high-resolution X-ray detector. The X-ray spectra show elements starting from sodium up to yttrium, depending on their concentrations. The backscattered alpha spectra, measured by a ring of detectors, provide additional data on carbon and oxygen. By means of a proper calibration, the elemental concentrations are derived. Together with data from the two other Athena instruments mounted on the IDD, the samples under investigation can be fully characterized. Key APXS objectives are the determination of the chemistry of crustal rocks and soils and the examination of water-related deposits, sediments, or evaporates. Using the rock abrasion tool attached to the IDD, issues of weathering can be addressed by measuring natural and abraded surfaces of rocks.

  15. Subunit exchange of lens alpha-crystallin: a fluorescence energy transfer study with the fluorescent labeled alphaA-crystallin mutant W9F as a probe.

    PubMed

    Sun, T X; Akhtar, N J; Liang, J J

    1998-07-01

    A Trp-free alphaA-crystallin mutant (W9F) was prepared by site-directed mutation. This mutant appears to be identical to the wild-type in terms of conformation (secondary and tertiary structures). W9F was labeled with a sulfhydryl-specific fluorescent probe, 2-(4'-maleimidylanilino) naphthalene-6-sulfonate (MIANS), and used in a subunit exchange between alphaA- and alphaA-crystallins as well as between alphaA- and alphaB-crystallins, studied by measurement of fluorescence resonance energy transfer. Energy transfer was observed between Trp (donor, with emission maximum at 336 nm) of wild-type alphaA- or alphaB-crystallin and MIANS (acceptor, with absorption maximum at 313 nm) of labeled W9F when subunit exchange occurred. Time-dependent decrease of Trp and increase of MIANS fluorescence were recorded. The exchange was faster at 37 degrees C than at 25 degrees C. The energy transfer efficiency was greater between homogeneous subunits (alphaA-alphaA) than between heterogeneous subunits (alphaA-alphaB). A previous exchange study with isoelectric focusing indicated a complete but slow exchange between alphaA and alphaB subunits. The present study showed that the exchange was a fast process, and the different energy transfer efficiencies between alphaA-alphaA and alphaA-alphaB indicated that alphaA- and alphaB-crystallins were not necessarily structurally equivalent. PMID:9688580

  16. 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.

  17. A new mechanism for DNA alterations induced by alpha particles such as those emitted by radon and radon progeny.

    PubMed Central

    Lehnert, B E; Goodwin, E H

    1997-01-01

    The mechanism(s) by which alpha (alpha) particles like those emitted from inhaled radon and radon progeny cause their carcinogenic effects in the lung remains unclear. Although direct nuclear traversals by alpha-particles may be involved in mediating these outcomes, increasing evidence indicates that a particles can cause alterations in DNA in the absence of direct hits to cell nuclei. Using the occurrence of excessive sister chromatid exchanges (SCE) as an index of DNA damage in human lung fibroblasts, we investigated the hypothesis that alpha-particles may induce DNA damage through the generation of extracellular factors. We have found that a relatively low dose of alpha-particles can result in the generation of extracellular factors, which, upon transfer to unexposed normal human cells, can cause excessive SCE to an extent equivalent to that observed when the cells are directly irradiated with the same irradiation dose. A short-lived, SCE-inducing factor(s) is generated in alpha-irradiated culture medium containing serum in the absence of cells. A more persistent SCE-inducing factor(s), which can survive freeze-thaw and is heat labile is produced by fibroblasts after exposure to the alpha-particles. These results indicate that the initiating target for alpha-particle-induced genetic changes can be larger than a cell's nucleus or even a whole cell. How transmissible factors like those observed here in vitro may extend to the in vivo condition in the context of a-particle-induced carcinogenesis in the respiratory tract remains to be determined. PMID:9400706

  18. 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.

  19. Electron capture by alpha particles from helium atoms in a Coulomb-Born distorted-wave approximation

    NASA Astrophysics Data System (ADS)

    Ghanbari-Adivi, E.; Ghavaminia, H.

    2012-12-01

    A three-body Coulomb-Born continuum distorted-wave approximation is applied to calculate the differential and total cross sections for single-electron exchange in the collision of fast alpha particles with helium atoms in their ground states. The applied first-order distorted wave theory satisfies correct Coulomb boundary conditions. Both post and prior forms of the transition amplitude are calculated. The nuclear-screening effect of the passive electron on the differential and total cross sections is investigated. The results are compared with those of other theories and with the available experimental data. For differential cross sections, the comparisons show a reasonable agreement with empirical measurements at higher impact energies. The agreement between experimental data and the present calculations for total cross sections with the average of the post and prior forms of the transition amplitude is reasonable at all the specified energies.

  20. Novel Equipment for In Situ Alpha Spectrometry with Good Energy Resolution.

    PubMed

    Pllnen, Roy; Turunen, Jani; Karhunen, Tero; Perjrvi, Kari; Siiskonen, Teemu; Wirta, Markus; Turunen, Asko

    2015-12-01

    An approach for in situ alpha spectrometry that allows one to measure the spectra with good energy resolution at ambient air pressure has been developed recently. Here, novel equipment is introduced for in situ measurements. Neither vacuum pumps nor radiochemical sample processing are necessary. Flat and smooth surfaces are ideal sources provided that the radionuclide contamination represents a thin layer on the surface. Other sources, such as air filters or evaporation residues, are also possible. Alpha particle collimation is used to obtain good energy resolution, but the equipment can also be used without collimation. An estimation of the detection efficiency with and without collimation is given using an extended area source containing 241Am. PMID:26509627

  1. 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.

  2. 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.

  3. Monopole Interaction and Single-Particle Energies

    SciTech Connect

    Umeya, A.; Kaneko, G.; Muto, K.

    2009-08-26

    We derived an expression of single-particle energies, and it is expressed in terms of monopole strengths and number operators. The monopole component of NN interaction, which is defined as the lowest-order terms of multipole expansion, is well renormalized into the single-particle energies.

  4. An analysis of 25Al energy levels observed in the 28Si(p,alpha)25Al reaction

    SciTech Connect

    Pittman, S. T.; Bardayan, Daniel W; Blackmon, Jeff C; Kozub, R. L.; Smith, Michael Scott

    2009-01-01

    The level structure of {sup 25}Al has been studied at the ORNL Holifield Radioactive Ion Beam Facility (HRIBF) by measuring the angular and energy distributions of alpha particles from the {sup 28}Si(p,{alpha}){sup 25}Al reaction. Proton beams ({approx}10 nA) at laboratory energies of 40- and 42-MeV were generated by the 25 MV tandem accelerator and bombarded a natural silicon target (50 {micro}g/cm{sup 2}). Alpha particles were detected and identified in the Silicon Detector Array (SIDAR) in the 'telescope' configuration [1]. Eighteen levels have been observed and spins for several have been constrained through a distorted-wave Born approximation (DWBA) analysis of the angular distributions.

  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 in public areas: airports, railway station and so on.

  6. 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.

  7. 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

  8. A double electron capture by alpha particles in collisions with hydrogen molecules in low temperature plasma

    NASA Astrophysics Data System (ADS)

    Oda, T.; Sato, K.; Namba, S.; Kusakabe, S.; Takahara, K.; Tawara, H.; Katsuta, T.; Takiyama, K.; Furukane, U.

    1997-02-01

    Spectroscopic study has been made of double electron capture process by alpha particles, He 2+, when helium plasmas contact with cold hydrogen molecules. Fast enhancements of HeIn = 2, 4 and 5 as well as of HeIn = 3 level populations due to the selective double electron capture have been found at the early period of hydrogen gas injection into the helium plasmas. Large population inversion resulting from these enhancements has been also observed between n = 2 and 3 levels. Numerical calculation based on a collisional-radiative model has revealed the enhancement mechanism.

  9. 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.

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

    SciTech Connect

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

    1994-03-01

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

  11. 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.

  12. Development of a He{sup 0} Source for Confined Alpha Particle Measurement

    SciTech Connect

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

    2008-03-12

    A probing He{sup 0} beam for confined alpha particle measurement using a double charge exchange process is now under development. A proof of principle experiment for ground-state He{sup 0} beam production will be performed on a test stand. Several methods are developed to measure the metastable fraction of a He{sup 0} beam. A full-size strong-focusing He{sup +} source has been constructed and sufficient beam current was achieved with a beam size tolerable to be used on ITER.

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

    SciTech Connect

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

    1991-10-01

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

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

    SciTech Connect

    Shin, H.; Kim, N.M.

    1999-06-01

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

  15. 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.

  16. 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).

  17. Matrix Characterization of Plutonium Residues by Alpha-Particle Self-Interrogation

    SciTech Connect

    Prettyman, T.H.; Foster, L.A.; Staples, P.

    1998-07-26

    Legacy plutonium residues often have inadequate item descriptions. Nondestructive characterization can help segregate these items for reprocessing or provide information needed for disposal or storage. Alpha particle-induced gamma-ray spectra contain a wealth of information that can be used for matrix characterization. We demonstrate how this information can be used for item identification. Gamma-ray spectra were recorded at the Los Alamos Plutonium Facility from a variety of legacy, plutonium-processing residues and product materials. The comparison and analysis of these spectra are presented.

  18. Alfven waves, alpha particles, and pickup ions in the solar wind

    NASA Technical Reports Server (NTRS)

    Goldstein, B. E.; Neugebauer, M.; Smith, E. J.

    1995-01-01

    Past studies of the properties of Alfven waves in the solar wind have indicated that (1) the amplitude of the velocity fluctuations is almost always smaller than expected on the basis of the amplitude of the field fluctuations, even when the anisotropy of the plasma is taken into account, and (2) the alpha particles do not participate in the wave motions because they 'surf' on the waves carried by the proton fluid. Ulysses data are used to demonstrate that (1) the discrepancy between the velocity and field fluctuations is greater at high heliographic latitudes than in the ecliptic plane, and (2) the alphas do participate in the waves, being either in phase or out of phase with the proton motions depending on whether the differential flow speed between the alphas and protons is greater than or less than the 'observed' wave speed, B(sub o)(delta v squared / delta B squared)exp 1/2, as determined from the ratio of the amplitudes of the velocity and magnetic fluctuations. It is proposed that the modification of Alfven wave propagation speed is due to pressure anisotropies resulting from asymmetric distributions of interstellar pickup ions. If the proposed explanation is correct, it indicates that scattering of pickup ions onto a (bi)spherical shell may not be as complete as generally supposed.

  19. 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.

  20. 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.

  1. Analysis of {sup 25}Al energy levels observed in the {sup 28}Si(p,{alpha}){sup 25}Al reaction

    SciTech Connect

    Pittman, S. T.; Bardayan, D. W.; Smith, M. S.; Blackmon, J. C.; Kozub, R. L.

    2009-09-15

    The level structure of {sup 25}Al has been studied at the ORNL Holifield Radioactive Ion Beam Facility by measuring the angular and energy distributions of {alpha} particles from the {sup 28}Si(p,{alpha}){sup 25}Al reaction. Proton beams ({approx}10 nA) at laboratory energies of 40 and 42 MeV were generated by the 25 MV tandem accelerator and bombarded a natural silicon target (50 {mu}g/cm{sup 2}). Seventeen levels were observed and spins for several were constrained through a distorted-wave Born approximation analysis of the angular distributions.

  2. Partition of thorium between organs of monkeys injected with thorotrast: implications for alpha-particle dosimetry.

    PubMed

    Ishikawa, Y; Humphreys, J A; Wesch, H; Priest, N D

    1998-09-01

    Risk estimates for alpha-particle-induced malignancies have been based mainly on studies of Thorotrast patients, but certain aspects of its deposition in the body have been at issue: the partition between the liver, spleen and red bone marrow, and the deposition at lower concentrations in other organs, such as muscle and fat, which may contribute to the risk. To supplement the existing data for humans, thorium concentrations were measured in the organs of two female monkeys 3-4 years after injection with Thorotrast. Relative deposits (liver:spleen:red bone marrow) were 54:6:41 and 75:4:21, in better agreement with the most recent observations in Thorotrast patients than with previous reports. Whereas the human testis had ranked among intermediate-level organs such as the adrenal glands and pancreas, the ovary of the monkey was among the organs with the lowest concentrations. The data suggest that risk factors for induction of malignancies by alpha-particle irradiation should be re-examined. PMID:9728666

  3. 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.

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

    PubMed

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

    2015-11-01

    In this study, based on the electrostatic integrating radon monitor (EIRM) developed by Iida et al., a new type of EIRM with the allyl glycol carbonate (CR-39) as alpha-particle detector was developed for outdoor radon measurements. Besides using the CR-39 to replace the cellulose nitrate film as alpha-particle detector, the electrode and the setting place of the CR-39 were also optimally designed based on the simulation results of the electric field and the detection efficiency. The calibration factor of the new EIRM was estimated to be 0.136±0.002 tracks cm(-2) (Bq m(-3) h)(-1), with the lower detection limit of 0.6 Bq m(-3) for a 2-month exposure. Furthermore, both the battery and the dry agent were also replaced to protect the environment. The results of intercomparison and field experiments showed that the performances of the new EIRM were much better than the original one. It suggests that the new type of ERIM is more suitable for large-scale and long-term outdoor radon surveys. PMID:25920784

  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. Targeted cytoplasmic irradiation with alpha particles induces mutations in mammalian cells.

    PubMed

    Wu, L J; Randers-Pehrson, G; Xu, A; Waldren, C A; Geard, C R; Yu, Z; Hei, T K

    1999-04-27

    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. PMID:10220401

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

    NASA Astrophysics Data System (ADS)

    Bota, Sebasti 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.

  8. 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).

  9. A Revisit of the Mainz Data on the Beta-Delayed Alpha-Particle Emission of ^16N

    NASA Astrophysics Data System (ADS)

    Gai, Moshe; France, Ralph H., III

    1998-10-01

    Very recently the TRIUMF collaboration [1] published a recalibration and thus alteration of the beta-delayed alpha-particle spectrum of ^16N measured at Mainz [2,3]. We show that this recalibration carries a substantial systematic uncertainty and in fact the original calibration (of the Mainz group) cannot be refuted as suggested in [1]. We demonstrate the validity of the Mainz spectrum and suggest that contrary to previous claims [1], it is very likely to be the best measured over that energy range, and thus should not be neglected in R-matrix analyses of the ^12C(?,?)^16O reaction. [1] R.E. Azuma et al. Phys. Rev. C50(1997)ER1655. [2] F.C. Barker, Private Communication. [3] H. Hattig, K. Hunchen, P. Roth, and H. Waffler; Nucl. Phys. A137(1969)144.

  10. 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 quarks and gluons. PMID:26632590

  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-(?-) particle radiation and X-rays on apoptosis and associated changes in gene expression. Human monocytic cells were exposed to ?-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 ?-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-? were common to the ?-irradiated cells. This data suggests that ?-particle radiation initiates cell death by TNF-? and Fas activation and through intermediate signalling mediators that are distinct from X-irradiated cells. PMID:22091383

  12. 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...

  13. Alpha-Channeling with Plasma Waves in Mirror Plasmas

    NASA Astrophysics Data System (ADS)

    Zhmoginov, Andrey; Fisch, Nathaniel

    2008-11-01

    The alpha-channeling effect can be obtained by coupling waves resonating with alpha particles in mirror machines. Modes suitable for alpha-channeling implementation in mirror machines are identified and the achievable efficiency of alpha particle energy extraction is estimated. Methods of coupling external energy sources to the identified plasma modes are proposed. The feasibility of implementing alpha-channeling concept in existing mirror machines including Gamma 10 and AMBAL-M is discussed.

  14. 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.

  15. Alpha voltaic batteries and methods thereof

    NASA Technical Reports Server (NTRS)

    Raffaelle, Ryne P. (Inventor); Jenkins, Phillip (Inventor); Wilt, David (Inventor); Scheiman, David (Inventor); Chubb, Donald (Inventor); Castro, Stephanie (Inventor)

    2011-01-01

    An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material.

  16. Design of a neutron-TPC prototype and its performance evaluation based on an alpha-particle test

    NASA Astrophysics Data System (ADS)

    Huang, Meng; Li, Yu-Lan; Niu, Li-Bo; Li, Jin; Deng, Zhi; He, Li; Zhang, Hong-Yan; Cheng, Xiao-Lei; Fu, Jian-Qiang; Li, Yuan-Jing

    2015-08-01

    A neutron-TPC (nTPC) is being developed for use as a fast neutron spectrometer in the fields of nuclear physics, nuclear reactor operation monitoring, and thermo-nuclear fusion plasma diagnostics. An nTPC prototype based on a GEM-TPC (Time Projection Chamber with Gas Electron Multiplier amplification) has been assembled and tested using argon-hydrocarbon mixture as the working gas. By measuring the energy deposition of the recoil proton in the sensitive volume and the angle of the proton track, the incident neutron energy can be deduced. A Monte Carlo simulation was carried out to analyze the parameters affecting the energy resolution of the nTPC, and gave an optimized resolution under ideal conditions. An alpha particle experiment was performed to verify its feasibility, and to characterize its performance, including energy resolution and spatial resolution. Based on the experimental measurement and analysis, the energy resolution (FWHM) of the nTPC prototype is predicted to be better than 3.2% for 5 MeV incident neutrons, meeting the performance requirement (FWHM<5%) for the nTPC prototype.

  17. Dissipative particle dynamics with energy conservation

    NASA Astrophysics Data System (ADS)

    Bonet Avalos, J.; Mackie, A. D.

    1997-10-01

    The stochastic differential equations for a model of dissipative particle dynamics with both total energy and total momentum conservation in the particle-particle interactions are presented. The corresponding Fokker-Planck equation for the evolution of the probability distribution for the system is deduced together with the corresponding fluctuation-dissipation theorems ensuring that the ab initio chosen equilibrium probability distribution for the relevant variables is a stationary solution. When energy conservation is included, the system can sustain temperature gradients and heat flow can be modeled.

  18. 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.

  19. 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.

  20. Transcriptional and secretomic profiling of epidermal cells exposed to alpha particle radiation.

    PubMed

    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

  1. 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 (?)-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 ?-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 ?-particle exposed cells. The highest dose of ?-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 ?-particle exposure. PMID:23002402

  2. Gene expression responses in human lung fibroblasts exposed to alpha particle radiation.

    PubMed

    Chauhan, Vinita; Howland, Matthew

    2014-10-01

    This study examined alpha (?-) particle radiation effects on global changes in gene expression for the purposes of identifying potential signaling pathways that may be involved in Radon ((222)Rn) gas exposure and lung carcinogenesis. Human lung fibroblast cells were exposed to ?-particle radiation at a dose range of 0-1.5Gy. Twenty-four hours post-exposure, transcript modulations were monitored using microarray technology. A total of 208 genes were shown to be dose-responsive (FDR adjusted p<0.05, Fold change>|2|) of which 32% were upregulated and 68% downregulated. Fourteen of the high expressing genes (>|4| fold) were further validated using alternate technology and among these genes, GDF15 and FGF2 were assessed at the protein level. GDF15, a known marker of lung injury, had expression levels 3-fold higher in exposed cell culture media, 24h post-irradiation as detected by ELISA. Further, pathway analysis of the dose-responsive transcripts showed them to be involved in biological processes related to cell cycle control/mitosis, chromosome instability and cell differentiation. This panel of genes with particular focus on GDF15 may merit further analysis to determine their specific role in mechanisms leading to ?-particle induced lung carcinogenesis. PMID:24945610

  3. Particle production at AGS energies

    SciTech Connect

    Steadman, S.G.; Rothschild, P.J.; Sung, T.W.; Zachary, D.

    1995-03-01

    The authors discuss particle production from 14.6 A{center_dot}GeV/c Si and 11.6 A{center_dot}GeV/c Au projectiles on Al and Au targets. The second-level trigger utilized by E859 allows high precision measurements of K{sup {minus}}, {bar p}, {Lambda} and {bar {Lambda}}. The {bar {Lambda}} yield is larger than expected, and a surprisingly large fraction of the {bar p}`s are observed to arise from the decay of {bar {Lambda}}.

  4. Correlation between {alpha}-Decay Energies of Superheavy Nuclei Involving the Effects of Symmetry Energy

    SciTech Connect

    Dong Jianmin; Zuo Wei; Scheid, Werner

    2011-07-01

    A formula for the relationship between the {alpha}-decay energies (Q values) of superheavy nuclei (SHN) is presented, which is composed of the effects of Coulomb energy and symmetry energy. It can be employed not only to validate the experimental observations and measurements to a large extent, but also to predict the Q values of heaviest SHN with a high accuracy generally which will be very useful for future experiments. Furthermore, the shell closures in superheavy region and the effect of the symmetry energy on the stability of SHN against {alpha} decay are discussed with the help of this formula.

  5. 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.

  6. 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.

  7. 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.

  8. Evaluation of uncertainty components associated with alpha-particle spectrometric measurements of uranium isotopes in water.

    PubMed

    Seferinoğlu, Meryem; Dirican, Abdullah; Esra Erden, Pınar; Erçin, Demet

    2014-12-01

    Qualifications of uncertainties associated with the measurement of specific activity concentration of uranium radioisotope ((238)U) in water samples by alpha-particle spectrometry are presented. Possible sources of uncertainty are identified and quantified in the activity concentration measurements of (238)U isotope; the major source being the statistical counting uncertainty as expected. The combined relative standard uncertainty [Formula: see text] of the measurement was calculated as 1.4Bq kg(-1) (7.9%) for the investigated NPL sample. The accuracy and precision of recommended procedure were checked analysing six spiked water samples supplied from IAEA-proficiency test exercises. The results were evaluated in terms of relative bias, z-score, u-score, trueness and precision. These results show that the activity values and their uncertainties are in good agreement with recommended values. PMID:25306402

  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. Cross-sections for Balmer-alpha excitation in heavy-particle collisions

    SciTech Connect

    Bae, Y.K.

    1982-08-01

    Doppler shifted and unshifted Balmer-alpha radiation has been observed in the absolute sense for energetic H/sup +/, H/sub 2//sup +/ and H/sub 3//sup +/ ions incident on molecular hydrogen by the method of decay inside the target within the energy range of 20 keV to 150 keV. Most of the measurements were based on single-collision conditions, but a simple thick-target experiment has been tried for the case of dissociative excitation of the target molecules by H atoms.

  11. 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.

  12. 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

  13. Detection of alpha radiation in a beta radiation field

    DOEpatents

    Mohagheghi, Amir H. (Albuquerque, NM); Reese, Robert P. (Edgewood, NM)

    2001-01-01

    An apparatus and method for detecting alpha particles in the presence of high activities of beta particles utilizing an alpha spectrometer. The apparatus of the present invention utilizes a magnetic field applied around the sample in an alpha spectrometer to deflect the beta particles from the sample prior to reaching the detector, thus permitting detection of low concentrations of alpha particles. In the method of the invention, the strength of magnetic field required to adequately deflect the beta particles and permit alpha particle detection is given by an algorithm that controls the field strength as a function of sample beta energy and the distance of the sample to the detector.

  14. Varying ghost dark energy and particle creation

    NASA Astrophysics Data System (ADS)

    Khurshudyan, M.

    2016-02-01

    One of the models of dark energy is the ghost dark energy, which has a geometrical origin. Recently, a certain type of phenomenological modification of ghost dark energy has been suggested which motivated us for this work. The goal of this paper is twofold. First, we would like to study the cosmological scenario involving interacting varying ghost dark energy. A cosmographic analysis of a non-interacting model is also performed. Then, we study the particle creation following the straight analogy between quantization in Minkowski background and canonical quantization of a scalar field in curved dynamical backgrounds. Particular attention will be paid to massless-particle production from a radiation-dominated universe (according to our toy model) which evolves to our large-scale universe. Constraints on the parameters of the models obtained during the cosmographic analysis did allow to demonstrate the possibility of a massless-particle creation in a radiation-dominated universe.

  15. Self-consistent calculations of alpha-decay energies

    SciTech Connect

    Tolokonnikov, S. V.; Lutostansky, Yu. S.; Saperstein, E. E.

    2013-06-15

    On the basis of the self-consistent theory of finite Fermi systems, the energies of alphadecay chains were calculated for several new superheavy nuclei discovered recently in experiments of the Dubna-Livermore Collaboration headed by Yu.Ts. Oganessian. The approach in question is implemented on the basis of the generalized method of the density functional proposed by Fayans and his coauthors. The version used here relies on the functional DF3-a proposed recently for describing a wide array of nuclear data, including data on superheavy nuclei. A detailed comparison of the results obtained on this basis with the predictions of different approaches, including the self-consistent Skyrme-Hartree-Fock method, the micro-macro method in the version developed by Sobiczewski and his coauthors, and the phenomenological method of Liran and his coauthors, is performed. The resulting alpha-decay energies are used to calculate respective lifetimes with the aid of the phenomenological Parkhomenko-Sobiczewski formula.

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

    PubMed Central

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

    1996-01-01

    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. Images Figure 1 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8 PMID:8909252

  17. The highest energy particles in the Universe

    NASA Astrophysics Data System (ADS)

    Wilczy?ski, H.

    2005-09-01

    The energy spectrum of cosmic rays extends beyond 1020 eV, i.e., to energies eight orders of magnitude higher than the highest energies attained so far at terrestrial particle accelerators. The origin of these particles remains unknown: neither their sources nor the underlying physical process of their emission and acceleration have been identified. Although many models of cosmic-ray origin have been proposed, a conclusive verification of them has not been possible so far due to the limited statistics of the available experimental data on the cosmic-ray energy spectrum and composition at the highest energies. The current experimental data are reviewed in this paper. The prospects of gathering sufficiently large statistics in the near future, especially from the Pierre Auger Observatory, are discussed.

  18. High energy particles and quanta in astrophysics

    NASA Technical Reports Server (NTRS)

    Mcdonald, F. B. (Editor); Fichtel, C. E.

    1974-01-01

    The various subdisciplines of high-energy astrophysics are surveyed in a series of articles which attempt to give an overall view of the subject as a whole by emphasizing the basic physics common to all fields in which high-energy particles and quanta play a role. Successive chapters cover cosmic ray experimental observations, the abundances of nuclei in the cosmic radiation, cosmic electrons, solar modulation, solar particles (observation, relationship to the sun acceleration, interplanetary medium), radio astronomy, galactic X-ray sources, the cosmic X-ray background, and gamma ray astronomy. Individual items are announced in this issue.

  19. 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.

  20. High energy neutrinos from big bang particles

    NASA Astrophysics Data System (ADS)

    Berezinsky, V. S.

    1993-04-01

    The production of high energy neutrinos by big bang particles is reviewed. The big bang particles are divided into two categories: dark matter particles (DMP), i.e. those with the critical mass density (?X = ?c) at present, and the exotic relics whose mass density can be smaller than the critical one. For the case of DMP the neutralino and the gravitino are considered. High energy neutrinos can be produced due to the capture of the neutralinos in the earth and the sun, with the subsequent annihilation of these particles there. If R-parity is weakly violated, the neutralino decay can be a source of high energy neutrinos. The gravitino as DMP is unobservable directly, unless R-parity is violated and the gravitino decays. For thermal exotic relics a very general conclusion is reached: the detectable neutrino flux can be produced only by long-lived particles with ?X > to, where to is the age of the Universe (the exceptional case is the decay only to the neutrinos). Very large neutrino fluxes can be produced by superheavy (up to ~ 1018 GeV) metastable relics in the particular cosmological scenario where the violent entropy production occurs.

  1. Initial observations of low energy charged particles near the earth's bow shock on ISEE-1

    NASA Technical Reports Server (NTRS)

    Ipavich, F. M.; Gloeckler, G.; Fan, C. Y.; Fisk, L. A.; Hovestadt, D.; Klecker, B.; Scholer, M.; Ogallagher, J. J.

    1979-01-01

    Initial measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE 1 are reported. ULECA is an electrostatic deflection - total energy sensor consisting of a collimator, a deflection analyzer, and an array of solid-state detectors. The position of a given detector, which determines the energy per charge of an incident particle, together with the measured energy, determines the particle's charge state. It is found that a rich variety of phenomena are operative in the transthermal energy regime (about 10 keV/Q to 100 keV/Q) covered by ULECA. Specifically, observations are presented of locally accelerated protons, alpha particles, and heavier ions in the magnetosheath and upstream of earth's bow shock. Preliminary analysis indicates that the behavior of these locally accelerated particles is most similar at the same energy per charge.

  2. 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.

  3. Studies of High Energy Particle Astrophysics

    SciTech Connect

    Nitz, David F; Fick, Brian E

    2014-07-30

    This report covers the progress of the Michigan Technological University particle astrophysics group during the period April 15th, 2011 through April 30th, 2014. The principal investigator is Professor David Nitz. Professor Brian Fick is the Co-PI. The focus of the group is the study of the highest energy cosmic rays using the Pierre Auger Observatory. The major goals of the Pierre Auger Observatory are to discover and understand the source or sources of cosmic rays with energies exceeding 10**19 eV, to identify the particle type(s), and to investigate the interactions of those cosmic particles both in space and in the Earth's atmosphere. The Pierre Auger Observatory in Argentina was completed in June 2008 with 1660 surface detector stations and 24 fluorescence telescopes arranged in 4 stations. It has a collecting area of 3,000 square km, yielding an aperture of 7,000 km**2 sr.

  4. Power Supplies for High Energy Particle Accelerators

    NASA Astrophysics Data System (ADS)

    Dey, Pranab Kumar

    2015-05-01

    The on-going research and the development projects with Large Hadron Collider at CERN, Geneva, Switzerland has generated enormous enthusiasm and interest amongst all to know about the ultimate findings on `God's Particle'. This paper has made an attempt to unfold the power supply requirements and the methodology adopted to provide the stringent demand of such high energy particle accelerators during the initial stages of the search for the ultimate particles. An attempt has also been made to highlight the present status on the requirement of power supplies in some high energy accelerators with a view that, precautionary measures can be drawn during design and development from earlier experience which will be of help for the proposed third generation synchrotron to be installed in India at a huge cost.

  5. High-energy particles. [in Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Schardt, A. W.; Goertz, C. K.

    1983-01-01

    It is pointed out that the magnetosphere of Jupiter is in many respects quite different from that of the earth. The energy required to drive the Jovian magnetosphere is apparently extracted from Jupiter's rotational energy rather than from the solar wind. Jupiter is a strong source of energetic charged particles which can be detected as far away as the orbit of Mercury. The structure and dynamics of the energetic particle distribution in the inner magnetosphere is discussed, taking into account observations, transport and losses in the inner magnetosphere, satellite interactions, and electron synchrotron radiation. The subsolar hemisphere is considered, giving attention to particle fluxes in the subsolar magnetosphere, conditions in the middle magnetosphere, and the characteristics of the outer magnetosphere. A description of the predawn magnetosphere is also provided.

  6. Chinese high energy cosmic particle explorer (DAMPE)

    NASA Astrophysics Data System (ADS)

    Chang, Jin; Hu, Yiming; Wu, Jian

    The first Chinese high energy cosmic particle explorer (DArk Matter Particle Explorer-DAMPE) aims to detect electron/gamma at the range between 5GeV and 10TeV in space. DAMPE would be on the lookout for gamma rays produced when dark matter particles annihilate each other. The craft would also tune in to a high-energy electron spectrum that may shed light on the mysterious propagation and acceleration of cosmic rays.DAMPE is composed of four major payloads from top to bottom:The plastic scintillator detector,The silicon tracker,The BGO calorimeter and The neutron detector. Under CASs new Innovation 2020 program, the qualification model of DAMPE has already been done, and the flight model will be done by the end of year 2014.

  7. Radioactive Positron Emitter Production by Energetic Alpha Particles in Solar Flares

    NASA Astrophysics Data System (ADS)

    Murphy, R. J.; Kozlovsky, B.; Share, G. H.

    2014-12-01

    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-1) to a GeV nucleon-1, incorporating them into a computer code for calculating positron-emitter production. Adequate cross-section measurements were available for proton reactions, but not for ?-particle reactions where only crude estimates were possible. Here we re-evaluate the ?-particle cross sections using new measurements and nuclear reaction codes. In typical large gamma-ray line flares, proton reactions dominate positron production, but ?-particle reactions will dominate for steeper accelerated-ion spectra because of their relatively low threshold energies. With the accelerated-3He 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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, Cleste 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.

  14. 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.

  15. Linewidth measurements of the JET energetic ion and alpha particle collective Thomson scattering diagnostic gyrotron

    NASA Astrophysics Data System (ADS)

    Machuzak, John S.; Woskov, Paul P.; Fessey, John A.; Hoekzema, J. A.; Egedal, Jan; Bindslev, Henrik; Roberts, Peter; Stevens, Andrew; Davies, Paul; Gatcombe, Christopher; Hughes, Thomas P.

    1999-01-01

    Spectral purity of the transmitter source of a collective Thomson scattering (CTS) system is vitally important to insure that measured signals only originate from the plasma and not from stray source light. A number of high power (up to 500 kW), 140 GHz gyrotron tubes used with the Joint European Torus (JET) CTS system have been found to have one or more spurious modes and many harmonics in the output spectrum. The CTS diagnostic receiver system was used to make measurements of the gyrotron spectrum. It was comprised of a homodyne part from MIT for frequency sidebands <500 MHz, and a heterodyne part constructed at JET for frequency sidebands from 0.1 to 6 GHz. One tube at high power produced a strong 25 MHz mode and its harmonics to large frequency offsets, unsuitable for CTS measurements. Only at reduced power of approximately 100 kW was this tube's spectrum sufficiently clean for CTS. Another tube at JET operated at 500 kW output power with only low level parasitic modes, indicating that higher power gyrotrons may be available for future alpha particle measurements. The main receiver was tested with a low power test setup which simulated the gyrotron stray source light, the thermal ion feature and plasma electron cyclotron emission.

  16. 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

  17. Negative energy particle as an expanding wormhole

    NASA Astrophysics Data System (ADS)

    Culetu, Hristu

    2015-03-01

    The properties of a dynamic wormhole are investigated. Using a particular equation of state for the fluid on the wormhole throat, we reached an equation of motion for the throat (a hyperbola) that leads to a negative surface energy density σ. The throat expands with the same acceleration 2π|σ| as the Ipser-Sikivie domain wall. We found the Lagrangian leading to the above equation of motion of the throat. The associated Hamiltonian corresponds to a relativistic free particle of a time-dependent negative energy -ℏc/R, where R is the throat radius, similar in form with the Casimir energy inside an expanding spherical box.

  18. 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.

  19. Critical rate of energy loss for registration of charged particles in cellulose nitrate

    NASA Astrophysics Data System (ADS)

    Knfel, T. M. J.; Sachett, I. A.; Marques, A.; Martins, J. B.; Tavares, O. A. P.

    1980-04-01

    Cellulose nitrate films LR-115 type II (Kodak-Path) have been exposed, at right angles, to alpha-particle beams in the energy range 2.5-5.5 MeV. From measurements of both through-etched track diameter and through-etched track density, a critical rate of energy loss for track registration of (0.85 0.05) MeV cm 2 mg -1 has been derived, which corresponds to a critical alpha-particle energy of (4.6 0.4) MeV. These results are compatible with those obtained by other authors whenever similar etching conditions have been used. The concepts of a threshold rate of energy loss and a threshold energy for etched-track formation are introduced, and their values are obtained from the experiment as being (0.80 0.05) MeV cm 2 mg -1 and (5.1 0.4) MeV, respectively. In addition, the present work provides a suitable set of useful reference data for further applications of such plastic nuclear track detector in problems concerned with the detection of low-energy alpha particles.

  20. Operant responding following exposure to HZE particles and its relationship to particle energy and LET

    Technology Transfer Automated Retrieval System (TEKTRAN)

    On exploratory class missions astronauts will be exposed to range of heavy particles which differ in terms of particle energy and particle linear energy transfer. The present experiments were designed to evaluate how these physical characteristics of different particles affect cognitive performance...

  1. Cosmic absorption of ultra high energy particles

    NASA Astrophysics Data System (ADS)

    Ruffini, R.; Vereshchagin, G. V.; Xue, S.-S.

    2016-02-01

    This paper summarizes the limits on propagation of ultra high energy particles in the Universe, set up by their interactions with cosmic background of photons and neutrinos. By taking into account cosmic evolution of these backgrounds and considering appropriate interactions we derive the mean free path for ultra high energy photons, protons and neutrinos. For photons the relevant processes are the Breit-Wheeler process as well as the double pair production process. For protons the relevant reactions are the photopion production and the Bethe-Heitler process. We discuss the interplay between the energy loss length and mean free path for the Bethe-Heitler process. Neutrino opacity is determined by its scattering off the cosmic background neutrino. We compute for the first time the high energy neutrino horizon as a function of its energy.

  2. Review of lattice results concerning low-energy particle physics

    SciTech Connect

    Aoki, S.; Aoki, Y.; Bernard, C.; Blum, T.; Colangelo, G.; Della Morte, M.; Dürr, S.; El-Khadra, A. X.; Fukaya, H.; Horsley, R.; Jüttner, A.; Kaneko, T.; Laiho, J.; Lellouch, L.; Leutwyler, H.; Lubicz, V.; Lunghi, E.; Necco, S.; Onogi, T.; Pena, C.; Sachrajda, C. T.; Sharpe, S. R.; Simula, S.; Sommer, R.; Van de Water, R. S.; Vladikas, A.; Wenger, U.; Wittig, H.

    2014-09-01

    We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination of the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.

  3. High energy proton and alpha radiation effects on GaAs/AlGaAs quantum well infrared photodetectors

    SciTech Connect

    Khanna, S.M.; Liu, H.C.; Wilson, P.H.; Li, L.; Buchanan, M.

    1996-12-01

    Gallium arsenide quantum well infrared photodetectors (QWIPs) are ideally suited for infrared imagery due to their detection capability over a wide infrared wavelength region and the feasibility of fabrication of monolithic two-dimensional arrays of such detectors. This paper reports on the effects of high energy proton and alpha particle radiations on the performance of these devices. The particle energies ranged from 0.8 MeV to 10.0 MeV and the fluences used in this work ranged from 10{sup 11} to 10{sup 16}cm{sup {minus}2}. The dark current and spectral response of these radiated devices were measured at different fluence levels. Using the spectral response as a measure of device performance, it is concluded that the device performance decreases with fluence and the degradation due to alpha particles is greater than for protons of the same energy. Further, the damage to device performance decreases with the increase in the energy of both types of these radiations. From prior work, it was expected that these devices would be sensitive to permanent radiation damage. The extent of damage, however, could not be pre-judged due to the device complexity. These are the first reported measurements of radiation hardness of QWIPs.

  4. Energy-based analysis of milling alpha-lactose monohydrate.

    PubMed

    Chen, Y; Ding, Y; Papadopoulos, D G; Ghadiri, M

    2004-04-01

    Some observations on the milling of alpha-lactose monohydrate with a Retsch single-ball mill are reported. The effects of mill loading and frequency of the mill motion were investigated. At a given frequency, a lower mill loading showed a higher milling efficiency. For a given mill loading, size reduction rate increased exponentially with frequency. The milling behavior was analyzed with three energy-based models; namely, Rittinger's, Kick's, and Bond's models. The results suggest that Rittinger's model best describes the milling behavior for low mill loadings at high frequencies, whereas the data for high loading milling at low frequencies fit Kick's model better. The results also indicate that attrition and/or chipping is the dominant mechanism for milling at low frequencies with high loadings because of the shear action of the milling ball rolling on the powder bed. Also, as a result of impact of the milling ball on the two ends of the milling jar, fragmentation is responsible for size reduction at high frequencies with low loadings. PMID:14999726

  5. 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.

  6. Summary of the IEA Workshop on Alpha Physics and Tritium Issues in Large Tokamaks

    SciTech Connect

    Cheng, C.Z.; Stratton, B.; Zweben, S.J.; Pitcher, C.S.

    1993-11-01

    A brief summary is presented of the talks given during this meeting, which was held at PPPL and sponsored by the IEA (International Energy Agency) as part of the Large Tokamak collaboration. These talks are summarized into four sessions: tritium issues in large tokamaks, alpha particle simulation experiments, alpha particle theory, and alpha particle diagnostics.

  7. 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 ?3 and Vf increases while I3 slightly increases as T increases for the two detectors. The values of ?3, 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.

  8. Designing experimental setup and procedures for studying alpha-particle-induced adaptive response in zebrafish embryos in vivo

    NASA Astrophysics Data System (ADS)

    Choi, V. W. Y.; Lam, R. K. K.; Chong, E. Y. W.; Cheng, S. H.; Yu, K. N.

    2010-03-01

    The present work was devoted to designing the experimental setup and the associated procedures for alpha-particle-induced adaptive response in zebrafish embryos in vivo. Thin PADC films with a thickness of 16 μm were fabricated and employed as support substrates for holding dechorionated zebrafish embryos for alpha-particle irradiation from the bottom through the films. Embryos were collected within 15 min when the light photoperiod began, which were then incubated and dechorionated at 4 h post fertilization (hpf). They were then irradiated at 5 hpf by alpha particles using a planar 241Am source with an activity of 0.1151 μCi for 24 s (priming dose), and subsequently at 10 hpf using the same source for 240 s (challenging dose). The levels of apoptosis in irradiated zebrafish embryos at 24 hpf were quantified through staining with the vital dye acridine orange, followed by counting the stained cells under a florescent microscope. The results revealed the presence of the adaptive response in zebrafish embryos in vivo, and demonstrated the feasibility of the adopted experimental setup and procedures.

  9. Cross sections for {alpha}-particle induced reactions on {sup 115,116}Sn around the Coulomb barrier

    SciTech Connect

    Filipescu, D.; Avrigeanu, V.; Glodariu, T.; Mihai, C.; Bucurescu, D.; Ivascu, M.; Cata-Danil, I.; Stroe, L.; Deleanu, D.; Ghita, D. G.; Marginean, N.; Marginean, R.; Negret, A.; Pascu, S.; Sava, T.; Suliman, G.; Zamfir, N. V.; Sima, O.; Cata-Danil, G.

    2011-06-15

    The cross sections of the {sup 115}Sn({alpha},{gamma}){sup 119}Te, {sup 115}Sn({alpha},n){sup 118}Te, and {sup 116}Sn({alpha},n){sup 119}Te reactions (both on ground and isomeric states) have been measured at effective center-of-mass energies from 9.3 to 14.8 MeV. During a first experiment, enriched self-supporting {sup 115}Sn (51.2%) + {sup 116}Sn (24.4%) foils were bombarded with an {alpha} beam delivered by the Bucharest IFIN-HH Tandem Accelerator. In a second experiment, a highly enriched {sup 116}Sn target was irradiated in order to disentangle the experimental cross section contributions due to {sup 115}Sn({alpha},{gamma}){sup 119}Te and {sup 115}Sn({alpha},n){sup 118}Te reactions obtained in the first measurement. The beam-induced activity was measured with two large volume HPGe detectors in close geometry. The experimental results were compared with theoretical predictions obtained in the framework of the statistical model.

  10. Design of a compact, low-energy-charged-particle-spectrometer for stellar nucleosynthesis experiments at OMEGA and the NIF

    NASA Astrophysics Data System (ADS)

    Armstrong, E.; Frenje, J.; Gatu Johnson, M.; Li, C. K.; Rinderknecht, H.; Rosenberg, M.; Seguin, F. H.; Sio, H.; Zylstra, A.; Petrasso, R. D.

    2014-10-01

    A compact ``Orange'' Spectrometer is being designed for measurements of alpha and proton spectra in the range of ~ 1-5 MeV, produced in low-yield 3He3He experiments at the OMEGA laser and at the National Ignition Facility (NIF). Particle ray-tracing through magnetic fields, modeled by COMSOL, were conducted with the code Python. The goal is to identify an optimal setup for a spectrometer to measure alpha particles at relatively low energies and at low yield. Ability to study the alpha particles in addition to the protons is essential for understanding the nuclear physics governing the final-state interactions between pairs of particles in the three-body final state. This work was supported in part by the U.S. DOE and NLUF.

  11. {alpha}-decay energy formula for superheavy nuclei based on the liquid-drop model

    SciTech Connect

    Dong Tiekuang; Ren Zhongzhou

    2010-09-15

    A formula of {alpha}-decay energy for superheavy nuclei based on the method of macroscopic model plus shell corrections is proposed. The macroscopic part of this formula is derived from the Bethe-Weizsaecker binding energy formula, and the shell corrections at N=152 and N=162 are expressed by the Mexican hat wavelet functions. The parameters of this formula are obtained through fitting to 170 {alpha}-decay energies for nuclei ranging from Z=90 to Z=118 with N{>=}140. Numerical results show that 170 existing {alpha}-decay energies can be reproduced very well; the average and standard deviations between theoretical results and experimental data are 0.177 and 0.226 MeV, respectively. The {alpha}-decay energies of newly synthesized nuclei {sup 293,294}117 and their {alpha}-decay products are also reproduced very well. In addition, the {alpha}-decay energies for nuclei with Z=110-120 are predicted and compared with the results calculated by the macroscopic-microscopic model. Great differences are found for nuclei with Z{>=}116 and N{>=}176 due to the shell effects near the hypothetical doubly magic nucleus {sup 298}114{sub 184} in the macroscopic-microscopic model. Therefore, by comparing experimental {alpha}-decay energies measured in the future with the ones predicted by these two methods, one can obtain useful information about the next proton and neutron magic numbers.

  12. Alpha-induced reaction studies using low-energy RI beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Kahl, D.; Hu, J.; Kubono, S.; Hayakawa, S.; Hashimoto, T.

    2012-11-12

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Studies on proton and alpha resonance scatterings, ({alpha}, p) reactions, and other types of measurements ({beta}-decay lifetimes etc.) have been performed using RI beams at CRIB, motivated by interests on astrophysical reactions and exotic nuclear structure. Among the studies at CRIB, the measurement of {sup 7}Li+{alpha}/{sup 7}Be+{alpha} resonant scatterings are presented.

  13. Microwave and particle beam sources and directed energy concepts

    SciTech Connect

    Brandt, H.E. )

    1989-01-01

    This book containing the proceedings of the SPIE on microwave and particle beam sources and directed energy concepts. Topics covered include: High power microwave sources, Direct energy concepts, Advanced accelerators, and Particle beams.

  14. Effects of corotating interaction regions on Ulysses high energy particles

    SciTech Connect

    Droege, W.; Kunow, H.; Heber, B.; Mueller-Mellin, R.; Sierks, H.; Wibberenz, G.; Raviart, A.; Ducros, R.; Ferrando, P.; Rastoin, C.; Paizis, C.; Gosling, J. T.

    1996-07-20

    We investigate the intensity variation of low energy ({approx}6-23 MeV/N) heliospheric ions and of galactic protons (250-2200 MeV) observed by the Kiel Electron Telescope onboard the Ulysses spacecraft associated with Corotating Interaction Regions (CIR) from mid-1992 to end of June 1995. This period covers Ulysses' transit to high southern latitudes, the south polar pass, return to the solar equator and ascent to the north pole up to 70 deg. We find that the flux of high energy protons exhibits a periodicity of about 26 days with a relative intensity variation of 10%. At latitudes below {approx}50 deg. the recurrent variations of galactic protons are in coincidence with the passage of CIRs and enhancements of low energies protons and alpha particles which are accelerated at the shocks of the CIRs. The modulation of galactic protons is observed up to high southern latitudes, where the signatures of a CIR are no longer visible in plasma or magnetic field data. The periodicity does not depend on latitude and its phase apparently remains constant during Ulysses' pass over the south pole as well as through the solar equator.

  15. Effects of corotating interaction regions on Ulysses high energy particles

    SciTech Connect

    Droege, W.; Kunow, H.; Heber, B.; Mueller-Mellin, R.; Sierks, H.; Wibberenz, G.; Raviart, A.; Ducros, R.; Ferrando, P.; Rastoin, C.; Gosling, J.T.

    1996-07-01

    We investigate the intensity variation of low energy ({approximately}6{endash}23MeV/N) heliospheric ions and of galactic protons (250{endash}2200 MeV) observed by the Kiel Electron Telescope onboard the Ulysses spacecraft associated with Corotating Interaction Regions (CIR) from mid-1992 to end of June 1995. This period covers Ulysses{close_quote} transit to high southern latitudes, the south polar pass, return to the solar equator and ascent to the north pole up to 70{degree}. We find that the flux of high energy protons exhibits a periodicity of about 26 days with a relative intensity variation of 10{percent}. At latitudes below {approximately}50{degree} the recurrent variations of galactic protons are in coincidence with the passage of CIRs and enhancements of low energies protons and alpha particles which are accelerated at the shocks of the CIRs. The modulation of galactic protons is observed up to high southern latitudes, where the signatures of a CIR are no longer visible in plasma or magnetic field data. The periodicity does not depend on latitude and its phase apparently remains constant during Ulysses{close_quote} pass over the south pole as well as through the solar equator. {copyright} {ital 1996 American Institute of Physics.}

  16. Method and apparatus for generating low energy nuclear particles

    DOEpatents

    Powell, James R.; Reich, Morris; Ludewig, Hans; Todosow, Michael

    1999-02-09

    A particle accelerator (12) generates an input particle beam having an initial energy level above a threshold for generating secondary nuclear particles. A thin target (14) is rotated in the path of the input beam for undergoing nuclear reactions to generate the secondary particles and correspondingly decrease energy of the input beam to about the threshold. The target (14) produces low energy secondary particles and is effectively cooled by radiation and conduction. A neutron scatterer (44) and a neutron filter (42) are also used for preferentially degrading the secondary particles into a lower energy range if desired.

  17. Method and apparatus for generating low energy nuclear particles

    DOEpatents

    Powell, J.R.; Reich, M.; Ludewig, H.; Todosow, M.

    1999-02-09

    A particle accelerator generates an input particle beam having an initial energy level above a threshold for generating secondary nuclear particles. A thin target is rotated in the path of the input beam for undergoing nuclear reactions to generate the secondary particles and correspondingly decrease energy of the input beam to about the threshold. The target produces low energy secondary particles and is effectively cooled by radiation and conduction. A neutron scatterer and a neutron filter are also used for preferentially degrading the secondary particles into a lower energy range if desired. 18 figs.

  18. Calculating alpha Eigenvalues in a Continuous-Energy Infinite Medium with Monte Carlo

    SciTech Connect

    Betzler, Benjamin R.; Kiedrowski, Brian C.; Brown, Forrest B.; Martin, William R.

    2012-09-04

    The {alpha} eigenvalue has implications for time-dependent problems where the system is sub- or supercritical. We present methods and results from calculating the {alpha}-eigenvalue spectrum for a continuous-energy infinite medium with a simplified Monte Carlo transport code. We formulate the {alpha}-eigenvalue problem, detail the Monte Carlo code physics, and provide verification and results. We have a method for calculating the {alpha}-eigenvalue spectrum in a continuous-energy infinite-medium. The continuous-time Markov process described by the transition rate matrix provides a way of obtaining the {alpha}-eigenvalue spectrum and kinetic modes. These are useful for the approximation of the time dependence of the system.

  19. 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 ?-emitters are thought to eradicate tumor cells independent of cellular oxygenation. Therefore, the aim of this study was to demonstrate that cell-bound ?-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-1?. 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/ml1.48 MBq/ml) and irradiation with increasing doses of photons (0.512 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 ?-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

  20. The Apollo Alpha Spectrometer.

    NASA Technical Reports Server (NTRS)

    Jagoda, N.; Kubierschky, K.; Frank, R.; Carroll, J.

    1973-01-01

    Located in the Science Instrument Module of Apollo 15 and 16, the Alpha Particle Spectrometer was designed to detect and measure the energy of alpha particles emitted by the radon isotopes and their daughter products. The spectrometer sensor consisted of an array of totally depleted silicon surface barrier detectors. Biased amplifier and linear gate techniques were utilized to reduce resolution degradation, thereby permitting the use of a single 512 channel PHA. Sensor identification and in-flight radioactive calibration were incorporated to enhance data reduction.

  1. Effect of composition and radiation on the Hertzian indentation behavior of nuclear waste glasses. [77-MeV alpha particles

    SciTech Connect

    Matzke, H.; Kahl, L.; Routbort, J.L.; Saidl, J.

    1983-01-01

    The Hertzian indentation technique has been used to determine the fracture toughness, K/sub Ic/ of two borosilicate glasses developed to contain high-level nuclear waste. For the product VG 98/12, adding selected groups of fission products leaves K/sub Ic/ unchanged, but addition of Pb lowers K/sub Ic/ by approx. 20%. Radiation with 77 MeV ..cap alpha..-particles to a dose of approx. 10/sup 15/ ..cap alpha../cm/sup 2/ increases K/sub Ic/ by approx. 75%. For the product SM 58 LW 11, the fracture toughness was measured on pieces taken from different parts of a large cylinder to investigate the effects of segregation phenomena and of partial crystallization and formation of small cristobalite inclusions which decrease K/sub Ic/ by approx. 25%.

  2. Confined energy distribution for charged particle beams

    DOEpatents

    Jason, Andrew J.; Blind, Barbara

    1990-01-01

    A charged particle beam is formed to a relatively larger area beam which is well-contained and has a beam area which relatively uniformly deposits energy over a beam target. Linear optics receive an accelerator beam and output a first beam with a first waist defined by a relatively small size in a first dimension normal to a second dimension. Nonlinear optics, such as an octupole magnet, are located about the first waist and output a second beam having a phase-space distribution which folds the beam edges along the second dimension toward the beam core to develop a well-contained beam and a relatively uniform particle intensity across the beam core. The beam may then be expanded along the second dimension to form the uniform ribbon beam at a selected distance from the nonlinear optics. Alternately, the beam may be passed through a second set of nonlinear optics to fold the beam edges in the first dimension. The beam may then be uniformly expanded along the first and second dimensions to form a well-contained, two-dimensional beam for illuminating a two-dimensional target with a relatively uniform energy deposition.

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

    NASA Astrophysics Data System (ADS)

    Wedlund, C. Simon; 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 "remote-sensing" instrument for the neutral cometary atmosphere.

  4. Overview of the first workshop on alpha particle physics in TFTR

    SciTech Connect

    Zweben, S.J.; Biglari, H.

    1991-07-01

    The First Workshop on Alpha Physics in TFTR'' was held at the Princeton Plasma Physics Lab March 28--29, 1991. The motivation for this meeting was to clarify and strengthen the TFTR alpha physics program, and to increase the involvement of the fusion community outside PPPL in the TFTR D-T experiments. Therefore the meeting was sharply focused on alpha physics relevant to the upcoming TFTR D-T simulation, and was asked to devote half of his talk to specific TFTR issues. The Workshop consisted of 27 talks on: (1) experimental possibilities; (2) theoretical possibilities; (3) diagnostic possibilities; (4) relevance for future machines; and (5) discussion/summary session. This summary contains a brief sampling of the new results and ideas brought out by these talks, followed by two more general overviews of the status of experiment and theory.

  5. 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

  6. 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.

  7. R-matrix description of particle energy spectra produced by low-energy 3H + 3H reactions

    DOE PAGESBeta

    Brune, C. R.; Caggiano, J. A.; Sayre, D. B.; Bacher, A. D.; Hale, G. M.; Paris, M. W.

    2015-07-20

    An R-matrix model for three-body final states is presented and applied to a recent measurement of the neutron energy spectrum from the 3H + 3H→ 2n + α reaction. The calculation includes the n alpha and n n interactions in the final state, angular momentum conservation, antisymmetrization, and the interference between different channels. A good fit to the measured spectrum is obtained, where clear evidence for the 5He ground state is observed. The model is also used to predict the alpha-particle spectrum from 3H + 3H as well as particle spectra from 3He + 3He. The R-matrix approach presented heremore » is very general, and can be adapted to a wide variety of problems with three-body final states.« less

  8. 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.

  9. 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.

  10. 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.

  11. Monte Carlo charged-particle tracking and energy deposition on a Lagrangian mesh

    SciTech Connect

    Yuan, J.; Moses, G.A.; McKenty, P.W.

    2005-10-01

    A Monte Carlo algorithm for alpha particle tracking and energy deposition on a RZ cylindrical computational mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of 'Monte Carlo particles' which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted mesh cells, particle relocation on the moving mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about 30 picosecond earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.

  12. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons. Specifically, SiC radiation detectors with larger areas and 100-micrometer thick active regions have been designed and manufactured according to detector-design specifications. Detectors based on a Schottky diode design were specified in order to minimize the effects of the detector entrance window on alpha particle measurements. During manufacture of the Schottky diodes, the manufacturer also provided a set of large-volume SiC p-i-n diodes for testing Extensive alpha particle measurements have been carried out to test and quantify the response of the SiC Schottky diodes. Exposures to 148-Gd, 213-Po, 217-At, 221-Fr, 225-Ac, 237-Np, 238-Pu, 240-Pu, and 242-Pu sources were used to obtain detailed alpha response data in the alpha energy range from 3182.787 keV to 8375.9 keV. The 148-Gd, 213-Po, 217-At, and 221-Fr sources provide energy-separated, mono-energetic alpha particle peaks which can be analyzed to provide detailed information on the energy response characteristics of the detectors.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. A neutral-beam diagnostic for fast confined alpha particles in a burning plasma: Application on CIT (Compact Ignition Tokamak)

    SciTech Connect

    Schlachter, A.S.; Stearns, J.W.; Cooper, W.S.

    1987-10-01

    Diagnostic methods for fast confined alpha particles are essential for a burning-plasma experiment. We review one- and two-electron-capture methods using energetic neutral beams, and provide quantitative estimates of signal level for a two-electron-capture method applicable to CIT. The best probe is a ground-state helium-atom beam because of its relatively good penetration into a CIT plasma and the large cross section for two-electron capture; it can be produced in useful quantities from HeH/sup +/. We calculate a signal level of the order of 10/sup 7/ counts/s for 100 mA of accelerated HeH/sup +/, which is sufficient to allow time-resolved measurements of the alpha-particle velocity distribution. Limited position information could be obtained for appropriate access port geometry. This diagnostic is feasible, and we recommend further research and development leading to implementation on CIT. 39 refs., 16 figs., 5 tabs.

  19. Localized cyclotron mode driven by fast alpha particles under a nonuniform magnetic field.

    PubMed

    Chen, K R; Tsai, T H; Chen, L

    2010-02-01

    Resonance requires precise synchronization. Surprisingly, relativistic cyclotron instability can survive under a magnetic field with its nonuniformity larger than the requirement of synchronism. Localized eigenmode observed in a hybrid simulation is found to be consistent with that predicted by an analytical theory including both profile and eigenvalue. Half of the spatial area of the wave profile is located where the frequency mismatch is negative as against to the positive requirement generally believed. The consequence on the alpha dynamics is also demonstrated. PMID:20365662

  20. Review of lattice results concerning low-energy particle physics

    DOE PAGESBeta

    Aoki, S.; Aoki, Y.; Bernard, C.; Blum, T.; Colangelo, G.; Della Morte, M.; Dürr, S.; El-Khadra, A. X.; Fukaya, H.; Horsley, R.; et al

    2014-09-01

    We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination ofmore » the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.« less

  1. Development of a strongly focusing high-intensity He{sup +} ion source for a confined alpha particle measurement at ITER

    SciTech Connect

    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.

    2008-02-15

    A strongly focusing high-intensity He{sup +} ion source has been designed and constructed as a beam source for a high-energy He{sup 0} beam probe system for diagnosis of fusion produced alpha particles in the thermonuclear fusion plasmas. The He{sup +} 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{sub 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)

  2. Single-electron-capture cross sections by alpha-particles from ground state K(4s) and Rb(5s): A molecular-state approach

    SciTech Connect

    Kumar, A.; Saha, B.C.; Weatherford, C.A.

    1998-11-01

    Cross sections for single-electron capture by {alpha}-particles from ground state K and Rb were calculated in the low-to-intermediate energy region by employing the molecular expansion method in the framework of impact parameter formulation. The colliding partners are treated as a pseudo-one-electron system and the technique of the pseudopotential is used to account for their mutual interactions. The molecular wave function of the quasimolecule formed during the collision is expanded in terms of basis sets of atomic orbitals on two centers. The resulting coupled equations are solved semiclassically where a straight-line trajectory describes the relative motion of the two nuclei. The effect of electron translation is also suitably incorporated. The calculated cross sections, both total and partial, are presented and compared with the available experimental measurements.

  3. Use of incomplete energy recovery for the energy compression of large energy spread charged particle beams

    DOEpatents

    Douglas, David R.; Benson, Stephen V.

    2007-01-23

    A method of energy recovery for RF-base linear charged particle accelerators that allows energy recovery without large relative momentum spread of the particle beam involving first accelerating a waveform particle beam having a crest and a centroid with an injection energy E.sub.o with the centroid of the particle beam at a phase offset f.sub.o from the crest of the accelerating waveform to an energy E.sub.full and then recovering the beam energy centroid a phase f.sub.o+Df relative to the crest of the waveform particle beam such that (E.sub.full-E.sub.o)(1+cos(f.sub.o+Df))>dE/2 wherein dE=the full energy spread, dE/2=the full energy half spread and Df=the wave form phase distance.

  4. 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.

  5. 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, Ccile; 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 ?m 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.

  6. 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.

  7. 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 theory is augmented to include multiple-chance emission and tested on experimental data to yield positive results.

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

    PubMed

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

    2013-12-30

    Alpha-particle radiopharmaceutical therapy (?RPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, ?RPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of ?-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 ?-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or ?-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(?/?), has recently been proposed by the ICRU. In concert with EQD2(?/?), we introduce a new, redefined RBE quantity, named RBE2(?/?), as the ratio of the two linear coefficients that characterize the ? 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 irradiation of a breast cancer cell line. Radiobiological parameters are obtained using the linear quadratic model to fit cell survival data for MDA-MB-231 human breast cancer cells that were irradiated with either ? particles or a single fraction of low-LET (137)Cs ? rays. From these, the linear coefficient for both the biologically effective dose (BED) and the EQD2(?/?) response lines were derived for fractionated irradiation. The standard RBE calculation, using the traditional single fraction reference radiation, gave RBE values that ranged from 2.4 for a surviving fraction of 0.82-6.0 for a surviving fraction of 0.02, while the dose-independent RBE2(4.6) value was 4.5 for all surviving fraction values. Furthermore, bioeffect modeling with RBE2(?/?) and EQD2(?/?) demonstrated the capacity to predict the surviving fraction of cells irradiated with acute and fractionated low-LET radiation, ? particles and chronic exponentially decreasing dose rates of low-LET radiation. RBE2(?/?) is independent of absorbed dose for ?-particle emitters and it provides a more logical framework for data reporting and conversion to equieffective dose than the conventional dose-dependent definition of RBE. Moreover, it provides a much needed foundation for the ongoing development of an ?-particle dosimetry paradigm and will facilitate the use of tolerance dose data available from external beam radiation therapy, thereby helping to develop ?RPT as a single modality as well as for combination therapies. PMID:24377718

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

    PubMed

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

    2014-01-01

    Alpha-particle radiopharmaceutical therapy (?RPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, ?RPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of ?-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 ?-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or ?-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(?/?), has recently been proposed by the ICRU. In concert with EQD2(?/?), we introduce a new, redefined RBE quantity, named RBE2(?/?), as the ratio of the two linear coefficients that characterize the ? 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 irradiation of a breast cancer cell line. Radiobiological parameters are obtained using the linear quadratic model to fit cell survival data for MDA-MB-231 human breast cancer cells that were irradiated with either ? particles or a single fraction of low-LET (137)Cs ? rays. From these, the linear coefficient for both the biologically effective dose (BED) and the EQD2(?/?) response lines were derived for fractionated irradiation. The standard RBE calculation, using the traditional single fraction reference radiation, gave RBE values that ranged from 2.4 for a surviving fraction of 0.82-6.0 for a surviving fraction of 0.02, while the dose-independent RBE2(4.6) value was 4.5 for all surviving fraction values. Furthermore, bioeffect modeling with RBE2(?/?) and EQD2(?/?) demonstrated the capacity to predict the surviving fraction of cells irradiated with acute and fractionated low-LET radiation, ? particles and chronic exponentially decreasing dose rates of low-LET radiation. RBE2(?/?) is independent of absorbed dose for ?-particle emitters and it provides a more logical framework for data reporting and conversion to equieffective dose than the conventional dose-dependent definition of RBE. Moreover, it provides a much needed foundation for the ongoing development of an ?-particle dosimetry paradigm and will facilitate the use of tolerance dose data available from external beam radiation therapy, thereby helping to develop ?RPT as a single modality as well as for combination therapies. PMID:24502376

  10. 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, Sbastien; Sgouros, George

    2014-01-01

    Alpha-particle radiopharmaceutical therapy (?RPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, ?RPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of ?-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 ?-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or ?-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(?/?), has recently been proposed by the ICRU. In concert with EQD2(?/?), we introduce a new, redefined RBE quantity, named RBE2(?/?), as the ratio of the two linear coefficients that characterize the ? 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 irradiation of a breast cancer cell line. Radiobiological parameters are obtained using the linear quadratic model to fit cell survival data for MDA-MB-231 human breast cancer cells that were irradiated with either ? particles or a single fraction of low-LET 137Cs ? rays. From these, the linear coefficient for both the biologically effective dose (BED) and the EQD2(?/?) response lines were derived for fractionated irradiation. The standard RBE calculation, using the traditional single fraction reference radiation, gave RBE values that ranged from 2.4 for a surviving fraction of 0.826.0 for a surviving fraction of 0.02, while the dose-independent RBE2(4.6) value was 4.5 for all surviving fraction values. Furthermore, bioeffect modeling with RBE2(?/?) and EQD2(?/?) demonstrated the capacity to predict the surviving fraction of cells irradiated with acute and fractionated low-LET radiation, ? particles and chronic exponentially decreasing dose rates of low-LET radiation. RBE2(?/?) is independent of absorbed dose for ?-particle emitters and it provides a more logical framework for data reporting and conversion to equieffective dose than the conventional dose-dependent definition of RBE. Moreover, it provides a much needed foundation for the ongoing development of an ?-particle dosimetry paradigm and will facilitate the use of tolerance dose data available from external beam radiation therapy, thereby helping to develop ?RPT as a single modality as well as for combination therapies. PMID:24502376

  11. Elastic alpha scattering experiments and the alpha-nucleus optical potential at low energies

    SciTech Connect

    Mohr, P.; Kiss, G.G.; Flp, Zs.; Galaviz, D.; Gyrky, Gy.; Somorjai, E.

    2013-11-15

    High precision angular distribution data of (?,?) elastic scattering are presented for the nuclei {sup 89}Y, {sup 92}Mo, {sup 106,110,116}Cd, {sup 112,124}Sn, and {sup 144}Sm at energies around the Coulomb barrier. Such data with small experimental uncertainties over the full angular range (20170) are the indispensable prerequisite for the extraction of local optical potentials and for the determination of the total reaction cross section ?{sub reac}. A systematic fitting procedure was applied to the experimental scattering data presented to obtain comprehensive local potential parameter sets that are composed of a real folding potential and an imaginary potential of WoodsSaxon surface type. The potential parameters obtained were used in turn to construct a new systematic ?-nucleus potential with very few parameters. Although this new potential cannot reproduce the angular distributions with the same small deviations as the local potential, the new potential is able to predict the total reaction cross sections for all cases under study.

  12. 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 (?-) 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 ?-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 ?-particle exposure. PMID:23097634

  13. Enhancement of particle-wave energy exchange by resonance sweeping

    SciTech Connect

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

    1996-01-01

    When the resonance condition of the particle-wave interaction is varied adiabatically, the particles trapped in a wave are found to form phase space holes or clumps that enhance the particle-wave energy exchange. This mechanism can cause increased saturation levels of instabilities and even allow the free energy associated with instability to be tapped in a system in which background dissipation suppresses linear instability.

  14. Enhancement of particle-wave energy exchange by resonance sweeping

    SciTech Connect

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

    1995-10-01

    It is shown that as the resonance condition of the particle-wave interaction is varied adiabatically, that the particles trapped in the wave will form phase space holes or clumps that can enhance the particle-wave energy exchange. This mechanism can cause much larger saturation levels of instabilities, and even allow the free energy associated with instability, to be tapped in a system that is linearly stable due to background dissipation.

  15. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, Robert A. (Palo Alto, CA); Mendez, Victor P. (Berkeley, CA); Kaplan, Selig N. (El Cerrito, CA)

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  16. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, R.A.; Mendez, V.P.; Kaplan, S.N.

    1988-11-15

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation. 15 figs.

  17. 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.

  18. On resonant destabilization of toroidal Alfven eigenmodes by circulating and trapped energetic ions/alpha particles in tokamaks

    SciTech Connect

    Biglari, H.; Zonca, F.; Chen, L.

    1991-10-01

    Toroidal Alfven eigenmodes are shown to be resonantly destabilized by both circulating and trapped energetic ions/alpha particles. In particular, the energetic circulating ions are shown to resonate with the mode not only at the Alfven speed ({upsilon}{sub A}), but also one-third of this speed, while resonances exist between trapped energetic ions and the wave when {upsilon} = {upsilon}{sub A}/21{epsilon}{sup {1/2}} (l=integer, {epsilon}=r/R is the local inverse aspect ratio), although the instability becomes weaker for resonances other than the fundamental. The oft-quoted criterion that instability requires super-Alfvenic ion velocities is thus sufficient but not necessary. 14 refs.

  19. 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.

  20. 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.

  1. Performance of an in-situ alpha spectrometer.

    PubMed

    Pöllänen, R

    2016-03-01

    Equipment was recently developed for detecting alpha particles from flat and smooth surfaces with good energy resolution at ambient air pressure. In this work, the detection efficiencies were determined using different extended-area sources emitting alpha and beta radiation and a mixed nuclide point source emitting alpha radiation. Beta particles are of importance because they can also be detected. Counts originating from alpha and beta particles are mainly at different energies, which make their separation possible. An efficiency of 0.14 was determined for an extended-area (>30cm(2)) homogeneous source emitting alpha radiation at the energy of 5-6MeV, whereas for the beta emitters the efficiencies were 0.07-0.19 depending on the beta-particle emission energies. The use of a collimator reduces the detection efficiencies by a factor of up to ten. PMID:26688356

  2. A novel zirconium K{alpha} imager for high energy density physics research

    SciTech Connect

    Akli, K. U.; Jiang, S.; Storm, M. S.; Krygier, A.; Freeman, R. R.; Sanchez del Rio, M.; Stephens, R. B.; Pereira, N. R.; Baronova, E. O.; Theobald, W.; Ping, Y.; McLean, H. S.; Patel, P. K.; Key, M. H.

    2011-12-15

    We report on the development and characterization of a zirconium K{alpha} imager for high energy density physics research. The imager consists of a spherically bent quartz crystal operating at 15.7 keV photon energy. We compare the performance of the imager in terms of integrated reflectivity (R{sub int}) and temperature dependent collection efficiency ({eta}{sub Te}) to that of the widely used Cu K{alpha} imager. Our collisional-radiative simulations show that the new imager can be reliably used up to 250 eV plasma temperature. Monte Carlo simulations show that for a 25 {mu}m thick tracer layer of zirconium, the contribution to K{alpha} production from photo-pumping is only 2%. We present, for the first time, 2D spatially resolved images of zirconium plasmas generated by a high intensity short pulse laser interacting with Zr solid targets.

  3. Evaluation of Melt-Grown, ZnO Single Crystals for Use as Alpha-Particle Detectors

    SciTech Connect

    Neal, John S; Giles, N. C.; Yang, Xiaocheng; Wall, R. Andrew; Ucer, Burak; Williams, Richard T.; Wisniewski, Dariusz J; Boatner, Lynn A; Rengarajan, Varatharajan; Nause, Jeff E; Nemeth, Bell

    2008-01-01

    As part of an ongoing investigation of the scintillation properties of zinc-oxide-based scintillators, several melt-grown, ZnO single crystals have been characterized using -particle excitation, infrared reflectance, and room temperature photoluminescence. The crystals, grown by Cermet, Inc. using a pressurized melt growth process, were doped with Group 1 elements (Li), Group 2 elements (Mg), Group 3 elements (Ga, In) and Lanthanides (Gd, Er, Tm). The goals of these studies are to better understand the scintillation mechanisms associated with various members of the ZnO scintillator family and to then use this knowledge to improve the radiation detection capabilities of ZnO-based scintillators. One application for which ZnO is particularly well suited as a scintillator is as the associated particle detector in a deuterium-tritium (D-T) neutron generator. Application requirements include the exclusion of organic materials, outstanding timing resolution, and high radiation resistance. ZnO(Ga) and ZnO(In) have demonstrated fast (sub-nanosecond) decay times with relatively low light yields, and ZnO(Ga) has been used in a powder form as the associated particle detector for a D-T neutron generator. Four promising candidate materials, ZnO, ZnO:Ga, ZnO:In,Li, and ZnO:Er,Li, were identified in this study. These four samples demonstrated sub-nanosecond decay times and alpha particle excited luminescence comparable to BC-400 fast plastic scintillator. The ZnO:Mg,Ga, ZnO:Gd, and ZnO:Li samples demonstrated appreciable slow (microsecond) decay components that would be incompatible with high-counting-rate applications.

  4. Micronucleus induction in human lymphocytes: Comparative effects of x rays, alpha particles, beta particles and neutrons and implications for biological dosimetry

    SciTech Connect

    Wells, A.J.; Wells, J.; Hall, S.C.; Butler, A.

    1996-05-01

    The cytokinesis-block micronucleus assay in peripheral blood lymphocytes has the potential for being a simple and rapid method for biological dosimetry. This technique has been used to study the induction of micronuclei in the blood from 12 donors after exposure to a range or radiations with track-averaged LET values ranging from 0.26 to 4 keV {mu}m{sup {minus}1}. Data based on the average response of the 12 individuals for 250 kVp X rays were found to agree well with results published previously from other laboratories using similar techniques. Low dose-limiting RBE values relative to 250 kVp X rays for the radiations studied were found to be 0.50 for strontium/yttrium-90 {Beta} particles, 6.9 for 20-23 keV {mu}m{sup {minus}1} {alpha} particles and 17 for 24 keV neutrons. The pattern of the variation of individual radiosensitivity was found to be complex and dependent on dose, and the evaluation of individual radiosensitivity based on the response at one dose only can be misleading. it is concluded that, although the cytokinesis-block micronucleus assay in blood lymphocytes is a radiobiologically appropriate technique to use for biological dosimetry, its practical implementation may be limited by a need to perform individual pre-exposure calibrations. 33 refs., 9 figs., 5 tabs.

  5. Symplectic Simulation of Fast Alpha Particle Radial Transport in Tokamaks in the Presence of TF Ripples and a Neoclassical Tearing Mode

    NASA Astrophysics Data System (ADS)

    Khan, M.; Schoepf, K.; Goloborod'ko, V.; Yavorskij, V.

    2012-12-01

    A Hamiltonian guiding centre drift orbit code based on a symplectic integration algorithm, which enables the efficient calculation of particle trajectories and diffusion coefficients, is applied to fast alpha particle motion in magnetically perturbed tokamak plasmas. In particular, fast ion drift motion is examined in the presence of a stationary, low mode-number MHD magnetic perturbation in a toroidally rippled tokamak with circular flux surface. The main focus of our study is to investigate the dependence of the radial diffusion coefficient of energetic ions on their energy, on the perturbation strength and the localization of the perturbation. As expected, the resonance between bounce motion and toroidal field ripples plays a significant role in this context. For an ensemble of fast ions uniformly distributed in toroidal angle but with a given poloidal starting position their radial transport coefficient takes on higher values in the neighbourhood of resonance speeds and can exhibit there local minima, i.e. it shows an M-shaped speed dependence around resonances for sufficiently strong ripple perturbations. Expectedly, the addition of a modelled low-mode number neoclassical tearing mode perturbation will modify the pure ripple resonance structure of the radial diffusion coefficient. Depending on the strength and localization of the MHD mode it can cause enhancement or degradation of the radial ripple diffusion coefficient.

  6. Improving Alpha Spectrometry Energy Resolution by Ion Implantation with ICP-MS

    SciTech Connect

    Dion, Michael P.; Liezers, Martin; Farmer, Orville T.; Miller, Brian W.; Morley, Shannon M.; Barinaga, Charles J.; Eiden, Gregory C.

    2015-01-01

    We report results of a novel technique using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) as a method of source preparation for alpha spectrometry. This method produced thin, contaminant free 241Am samples which yielded extraordinary energy resolution which appear to be at the lower limit of the detection technology used in this research.

  7. Double strand break rejoining after irradiation of human fibroblasts with X rays or alpha particles: PFGE studies and numerical models.

    PubMed

    Pinto, M; Prise, K M; Michael, B D

    2002-01-01

    When a charged-particle track intercepts the chromatin fibre in DNA of mammalian cells, clustered damage is induced depending on the DNA conformation, local environment and track structure. Intra-track correlated DNA damage may have a higher probability of being mis-repaired or left un-repaired. Fragment size-distributions of DNA double strand breaks (DSBs) induced in primary human fibroblasts by 240 kVp X rays and 238Pu alpha particles (110 keV.micron-1) were resolved using pulsed-field gel electrophoresis (PFGE). By monitoring DSB rejoining kinetics and changes in the fragment size distribution with repair time, the relevance of spatial association of DSBs in determining rejoining kinetics was investigated. Rejoining kinetics appeared bi-phasic and independent of the size of the DNA fragments for both radiation qualities, with high LET radiation-induced DSBs repairing more slowly. Results suggest that local complexity of individual DSBs, rather than spatial association with other breaks is more significant in the determination of rejoining kinetics. PMID:12194265

  8. Structural basis of calcification inhibition by alpha 2-HS glycoprotein/fetuin-A. Formation of colloidal calciprotein particles.

    PubMed

    Heiss, Alexander; DuChesne, Alexander; Denecke, Bernd; Grtzinger, Joachim; Yamamoto, Kazuhiko; Renn, Thomas; Jahnen-Dechent, Willi

    2003-04-11

    Genetic evidence from mutant mice suggests that alpha(2)-HS glycoprotein/fetuin-A (Ahsg) is a systemic inhibitor of precipitation of basic calcium phosphate preventing unwanted calcification. Using electron microscopy and dynamic light scattering, we demonstrate that precipitation inhibition by Ahsg is caused by the transient formation of soluble, colloidal spheres, containing Ahsg, calcium, and phosphate. These "calciprotein particles" of 30-150 nm in diameter are initially amorphous and soluble but turn progressively more crystalline and insoluble in a time- and temperature-dependent fashion. Solubilization in Ahsg-containing calciprotein particles provides a novel conceptual framework to explain how insoluble calcium precipitates may be transported and removed in the bodies of mammals. Mutational analysis showed that the basic calcium phosphate precipitation inhibition activity resides in the amino-terminal cystatin-like domain D1 of Ahsg. A structure-function analysis of wild type and mutant forms of cystatin-like domains from Ahsg, full-length fetuin-B, histidine-rich glycoprotein, and kininogen demonstrated that Ahsg domain D1 is most efficient in inhibiting basic calcium phosphate precipitation. The computer-modeled domain structures suggest that a dense array of acidic residues on an extended beta-sheet of the cystatin-like domain Ahsg-D1 mediates efficient inhibition. PMID:12556469

  9. 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 ?H2AX 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

  10. EDITORIAL: Focus on High Energy Particle Astronomy FOCUS ON HIGH ENERGY PARTICLE ASTRONOMY

    NASA Astrophysics Data System (ADS)

    Ong, Rene A.; Covault, Corbin E.

    2009-05-01

    Astrophysics as a sub-discipline provides both unique opportunities and unique challenges relative to other fields of physics. On the one hand, the scope of astrophysics is literally universal, and we are free to examine the most interesting and exotic phenomena to be found anywhere. On the other hand, our access to the universe is limited to only those bits of information that nature happens to provide to us here on Earth. As astrophysicists, we have no direct control over our subject of study. We cannot conduct experiments to arrange stars in galaxies to our liking. We cannot initiate supernovas at specific times and places just to test our hypotheses. What we can do is to squeeze whatever information possible out of the the tiny particles that have traveled across vast distances to act as messengers to Earth from space. Fortunately, we are getting quite good at building a picture of the universe from the available astrophysical information. Nearly a decade into the millennium, scientists have deployed an impressive collection of sensitive observatories that are especially capable of unlocking the secrets of some of the most persistent astrophysical puzzles. In particular, in the fields of high-energy astrophysics corresponding to gamma-ray, cosmic ray and neutrino detection, we are moving to a new generation of experimental techniques that are dramatically more sensitive than prior efforts. These new instruments have two key properties: (1) increased collection area, which is critical for the low fluxes corresponding to high-energy messenger particles, and (2) precision directional reconstructions which allow observers to trace back the paths of these messengers to the originating astrophysical objects. Furthermore, as observational techniques mature, results from these complementary instruments provide an increasingly comprehensive picture of some of the more elusive astrophysical subjects. Each photon, cosmic ray, and neutrino result reported represents another clue to understanding the nature of high-energy objects both within and outside our galaxy. And yet, along with new understandings, we are also faced with new puzzles. Each of the papers in this focus issue presents the field of high-energy particle astronomy from the perspective of a given instrumental approach, corresponding to the current state-of-the-art for a particular class of messenger particle in a given energy range. For gamma-ray astronomy, we have a excellent report by R Johnson and R Mukherjee on results from space-borne telescopes, first from the Compton Gamma Ray Observatory and then from the recently commissioned Fermi Gamma-Ray Space Telescope. The detailed paper by J Hinton describes a wealth of results from several ground-based gamma-ray telescopes using the atmospheric Cherenokov technique. Gamma-ray results and the prospects from air-shower detectors which can provide all-sky monitoring are very well described in a paper by G Sinnis. Larger plans for the future of ground-based gamma-ray astronomy are summarized in a paper by F Krennrich (in preparation). We also include two papers for 'non-photon' particle detection, a summary of the exciting new results for cosmic ray physics by P Sommers and S Westerhoff and an article by K Hoffman describing the astrophysics and capabilities of truly remarkable, large-volume neutrino detectors. For both cosmic rays and neutrinos, the fields seem to be on the threshold of doing astronomythat is, associating specific detected particles with particular astrophysical objects. Together, the fully operational space- and ground-based gamma-ray observatories and the new large-area experiments for cosmic ray and neutrino detection represent a new era in astronomy. We can be confident that the field of high-energy particle astronomy will continue to rapidly develop as more exciting results from these instruments are reported in the future. Focus on High Energy Particle Astronomy Contents Gamma ray astronomy with atmospheric Cherenkov telescopes: the future Frank Krennrich GeV telescopes: results and prospects

  11. 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

  12. The problem of low energy particle measurements in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Whipple, E. C., Jr.

    1978-01-01

    The accurate measurement of low energy (less than 100 eV) particle properties in the magnetosphere has been difficult, partly because of the low density of such particles, but more particularly because of spacecraft interference effects. Some early examples of how these phenomena have affected particle measurements on an OGO spacecraft are presented. Data obtained with the UCSD particle detectors on ATS-6 are then presented showing how some of these difficulties have been partially overcome. Future measurements of low energy particles in the magnetosphere can be improved by: (1) improving the low energy resolution of detectors; (2) building electrostatically clean spacecraft; (3) controlling spacecraft potential; and (4) using auxiliary measurements, particularly wave data.

  13. High energy collision of two particles in wormhole spacetimes

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Naoki; Bambi, Cosimo

    2015-04-01

    We study the collision of two particles in the Teo wormhole spacetime, in which the wormhole is stationary and axisymmetric. We show that a nonrotating Teo wormhole cannot be a high energy particle collider, while a rotating Teo wormhole can be used to accelerate particles and create high energy collisions because of the deep effective potential of the colliding particles. The process is different from that in the vicinity of a near-extremal black hole, since here there is no event horizon. This is the first example of particle collision with high center-of-mass energy in a spacetime with no event horizon and no naked singularity and not being extremal in a clear sense. The process can unlikely have direct implications for astrophysical observations, but it is interesting as a tool to investigate wormhole instabilities.

  14. 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 ?-emitting radionuclides is gaining traction with several clinical trials already undertaken or ongoing, and others in the advanced planning stage. The most commonly used ?-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 ?-particle radiotherapy. PMID:22202151

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

    NASA Astrophysics Data System (ADS)

    Norlin, B.; Reza, S.; Krapohl, D.; Frjdh, E.; Thungstrm, 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.

  16. Applications of 211At and 223Ra in targeted alpha-particle radiotherapy.

    PubMed

    Vaidyanathan, Ganesan; Zalutsky, Michael R

    2011-10-01

    Targeted radiotherapy using agents tagged with ?-emitting radionuclides is gaining traction with several clinical trials already undertaken or ongoing, and others in the advanced planning stage. The most commonly used ?-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 ?-particle radiotherapy. PMID:22202151

  17. 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

  18. Energy distributions and absolute yields of the charged light particles emitted during the thermal neutron induced ternary fission of 235U

    NASA Astrophysics Data System (ADS)

    D'hondt, P.; Wagemans, C.; Declercq, A.; Barreau, G.; Deruytter, A.

    1980-09-01

    The energy distributions and the yields of the main charged light particles emitted during the thermal neutron induced ternary fission of 235U were studied using a very pure neutron beam of the Grenoble high-flux reactor. All the measured energy distributions except that of the ?-particles are compatible with a gaussian shape. Explanations for this phenomenon are presented. For the main ternary particles following absolute yields were determined: protons 0.016 10 -3, tritons 0.106 10 -3, alphas 1.696 10 -3 and 6He 0.029 10 -3 particles per fission reaction. These results are discussed and compared with other data.

  19. TFTR alpha extraction and measurement project

    NASA Astrophysics Data System (ADS)

    Gerdin, G. A.; Wehring, B. W.

    1983-09-01

    A passive approach to the extraction and measurement of alpha particles from Tokamak fusion reactors is analyzed and the construction and preliminary results of a fast data-acquisition system are described. The passive approach is the converter foil concept whereby alphas leaving the plasma on large banana orbits strike carbon foils which slow down to around 0.5 MeV. At this energy a sizeable fraction of the alphas are neutral and hence can be analyzed by methods similar to those used in charge-exchange neutral detectors. Alpha loss orbits in TFTR, the thermal and particle flux to the foil on the TFTR edge, and the limitations in detector location caused by radiation are analyzed. The fast data-acquisition system, which operates in the pulse-height-analysis (PHA) mode to discriminate against low-energy background radiation, consists of an alpha detector, a commercial preamplifier, a fast PHA module (built-in house) and an inexpensive microcomputer.

  20. Labeling monoclonal antibodies and F(ab')2 fragments with the alpha-particle-emitting nuclide astatine-211: preservation of immunoreactivity and in vivo localizing capacity.

    PubMed Central

    Zalutsky, M R; Garg, P K; Friedman, H S; Bigner, D D

    1989-01-01

    alpha-Particles such as those emitted by 211At may be advantageous for radioimmunotherapy since they are radiation of high linear energy transfer, depositing high energy over a short distance. Here we describe a strategy for labeling monoclonal antibodies and F(ab')2 fragments with 211At by means of the bifunctional reagent N-succinimidyl 3-(trimethylstannyl)benzoate. An intact antibody, 81C6, and the F(ab')2 fragment of Me1-14 (both reactive with human gliomas) were labeled with 211At in high yield and with a specific activity of up to 4 mCi/mg in a time frame compatible with the 7.2-hr half-life of 211At. Quantitative in vivo binding assays demonstrated that radioastatination was accomplished with maintenance of high specific binding and affinity. Comparison of the biodistribution of 211At-labeled Me1-14 F(ab')2 to that of a nonspecific antibody fragment labeled with 211At and 131I in athymic mice bearing D-54 MG human glioma xenografts demonstrated selective and specific targeting of 211At-labeled antibody in this human tumor model. PMID:2476813

  1. Energy conservation potential of Portland cement particle size distribution control

    SciTech Connect

    Tresouthick, S.W.; Weiss, S.J.

    1986-01-01

    The main objective of Phase 3 is to develop practical economic methods of controlling the particles size distribution of portland cements using existing or modified mill circuits with the principal aim of reducing electrical energy requirements for cement manufacturing.

  2. Radioimmunotherapy with alpha-emitting nuclides.

    PubMed

    McDevitt, M R; Sgouros, G; Finn, R D; Humm, J L; Jurcic, J G; Larson, S M; Scheinberg, D A

    1998-09-01

    This review discusses the application of alpha particle-emitting radionuclides in targeted radioimmunotherapy. It will outline the production and chemistry of astatine-211, bismuth-212, lead-212, actinium-225, bismuth-213, fermium-255, radium-223 and terbium-149, which at present are the most promising alpha-emitting isotopes available for human clinical use. The selective cytotoxicity offered by alpha particle-emitting radioimmunoconstructs is due to the high linear energy transfer and short particle path length of these radionuclides. Based upon the pharmacokinetics of alpha particle-emitting radioimmunoconstructs, both stochastic and conventional dosimetric methodology is discussed, as is the preclinical and initial clinical use of these radionuclides conjugated to monoclonal antibodies for the treatment of human neoplasia. PMID:9724387

  3. Integro-differential equation approach. II. Triton and. alpha. -particle wave functions, graphical plots

    SciTech Connect

    Oehm, W.; Sofianos, S.A.; Fiedeldey, H. Physics Department, University of South Africa, Pretoria 0001 ); Fabre de la Ripelle, M. Physics Department, University of South Africa, Pretoria 0001 )

    1991-01-01

    Three- and four-nucleon ground-state wave functions are displayed graphically in coordinate space as well as the Faddeev amplitudes from which they are constructed. In the four-body case only two-particle correlations are taken into account in the integro-differential equation approach, which consequently allows us to make a direct comparison between the Faddeev amplitudes for three and four nucleons and to demonstrate their high degree of similarity in shape. We also investigate the effect of the inclusion of the hypercentral potential in the definition of the (modified) Faddeev amplitudes. It is shown that the Faddeev-type components calculated in the adiabatic approximation are rather similar in shape to those calculated by means of the exact solution of the system of coupled integro-differential equations in two variables. The mixed symmetry component of the Faddeev-type amplitudes show the greatest sensitivity to the number of nucleons, the inclusion of the hypercentral potential, and to the adiabatic approximation.

  4. Giant Resonances in the Alpha-Nucleus Interaction

    SciTech Connect

    Karpeshin, F. F.

    2010-04-30

    Tunneling of alpha particles through the Coulomb barrier for the source {sup 135}Pr nucleus is consecutively considered. The effect of sharp peaks arising in the case of coincidence of the alpha energy with that of a quasistationary state within the barrier is elucidated. Peaks' energy depend on the alpha-nucleus potential. They can give rise to 'anomalous' properties of some neutron resonances. The peaks can also be observed in the incoming alpha-nucleus channel. The method can be applied for solution of the reverse problem of the alpha-nucleus scattering.

  5. Alpha-particle emission as a probe of nuclear shapes and structure effects in proton evaporation spectra

    SciTech Connect

    Nicolis, N.G.; Sarantites, D.G.; Abenante, V.; Adler, L.A.; Dilmanian, F.A.; Majka, Z.; Semkow, T.M.; Stracener, D.W. . Dept. of Chemistry); 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. . Dep

    1990-01-01

    Emission barriers and subbarrier anisotropies from {alpha} decay of Sn* and Yb* compound nuclei are examined in the light of calculations incorporating deformation effects in the decay process. For the Yb* systems deformation which increases with spin is necessary to explain the data. For the Sn* systems the spectral shapes and anisotropies can be explained without deformation. For systems lighter than Sn this probe is not sensitive to the deformation. Energy spectra and angular correlations of evaporated protons from the {sup 52}Cr({sup 34}S, 2n2p){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. They are interpreted as due to near-yrast stretched proton emission preferentially populating the yrast band by subbarrier protons. Simulations show that channel selected proton spectra cannot be used as probes of deformation.

  6. STRV RADMON: An integrated high-energy particle detector

    NASA Technical Reports Server (NTRS)

    Buehler, Martin; Soli, George; Blaes, Brent; Tardio, Gemma

    1993-01-01

    The RADMON (Radiation Monitor) was developed as a compact device with a 4-kbit SRAM particle detector and two p-FET total dose monitors. Thus it can be used as a spacecraft radiation alarm and in situ total dose monitor. This paper discusses the design and calibration of the SRAM for proton, alpha, and heavy ion detection. Upset rates for the RADMON, based on a newly developed space particle flux algorithm, are shown to vary over eight orders of magnitude. On the STRV (Space Technology Research Vehicle) the RADMON's SRAM will be used to detect trapped protons, solar flares, and cosmic rays and to evaluate our ability to predict space results from ground tests.

  7. Microstructures for high-energy x-ray and particle-imaging applications

    SciTech Connect

    Ceglio, N.M.; Stone, G.F.; Hawryluk, A.M.

    1981-05-01

    Coded imaging techniques using thick, micro-Fresnel zone plates as coded apertures have been used to image x-ray emissions (2-20 keV) and 3.5 MeV Alpha particle emissions from laser driven micro-implosions. Image resolution in these experiments was 3-8 ..mu..m. Extension of this coded imaging capability to higher energy x-rays (approx. 100 keV) and more penetrating charged particles (e.g. approx. 15 MeV protons) requires the fabrication of very thick (50-200 ..mu..m), high aspect ratio (10:1), gold Fresnel zone plates with narrow linewidths (5-25 ..mu..m) for use as coded aperatures. A reactive ion etch technique in oxygen has been used to produce thick zone plate patterns in polymer films. The polymer patterns serve as electroplating molds for the subsequent fabrication of the free-standing gold zone plate structures.

  8. Activation measurement of the 3He(alpha,gamma)7Be cross section at low energy.

    PubMed

    Bemmerer, D; Confortola, F; Costantini, H; Formicola, A; Gyürky, Gy; Bonetti, R; Broggini, C; Corvisiero, P; Elekes, Z; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Imbriani, G; Junker, M; Laubenstein, M; Lemut, A; Limata, B; Lozza, V; Marta, M; Menegazzo, R; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Straniero, O; Strieder, F; Terrasi, F; Trautvetter, H P

    2006-09-22

    The nuclear physics input from the 3He(alpha,gamma)7Be cross section is a major uncertainty in the fluxes of 7Be and 8B neutrinos from the Sun predicted by solar models and in the 7Li abundance obtained in big-bang nucleosynthesis calculations. The present work reports on a new precision experiment using the activation technique at energies directly relevant to big-bang nucleosynthesis. Previously such low energies had been reached experimentally only by the prompt-gamma technique and with inferior precision. Using a windowless gas target, high beam intensity, and low background gamma-counting facilities, the 3He(alpha,gamma)7Be cross section has been determined at 127, 148, and 169 keV center-of-mass energy with a total uncertainty of 4%. The sources of systematic uncertainty are discussed in detail. The present data can be used in big-bang nucleosynthesis calculations and to constrain the extrapolation of the 3He(alpha,gamma)7Be astrophysical S factor to solar energies. PMID:17025958

  9. Monte Carlo particle-trajectory models for neutral cometary gases. I - Models and equations. II - The spatial morphology of the Lyman-alpha coma

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.; Smyth, William H.

    1988-01-01

    The mathematical derivations of various methods employed in the Monte Carlo particle-trajectory model (MCPTM) are presented, and the application of the MCPTM to the calculation of the photochemical heating of the inner coma through the partial thermalization of cometary hydrogen atoms produced by the photodissociation of water is discussed. This model is then used to explain the observed morphology of the spatially extended Ly-alpha comas of comets. The rocket and Skylab images of the Ly-alpha coma of Comet Kohoutek are examined.

  10. Monte Carlo particle-trajectory models for neutral cometary gases. I. Models and equations. II. The spatial morphology of the Lyman-alpha coma

    SciTech Connect

    Combi, M.R.; Smyth, W.H.

    1988-04-01

    The mathematical derivations of various methods employed in the Monte Carlo particle-trajectory model (MCPTM) are presented, and the application of the MCPTM to the calculation of the photochemical heating of the inner coma through the partial thermalization of cometary hydrogen atoms produced by the photodissociation of water is discussed. This model is then used to explain the observed morphology of the spatially extended Ly-alpha comas of comets. The rocket and Skylab images of the Ly-alpha coma of Comet Kohoutek are examined. 90 references.

  11. Model for radial dependence of frequency distributions for energy imparted in nanometer volumes from HZE particles

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Nikjoo, H.; Goodhead, D. T.; Decillo, J. F. (Principal Investigator)

    2000-01-01

    This paper develops a deterministic model of frequency distributions for energy imparted (total energy deposition) in small volumes similar to DNA molecules from high-energy ions of interest for space radiation protection and cancer therapy. Frequency distributions for energy imparted are useful for considering radiation quality and for modeling biological damage produced by ionizing radiation. For high-energy ions, secondary electron (delta-ray) tracks originating from a primary ion track make dominant contributions to energy deposition events in small volumes. Our method uses the distribution of electrons produced about an ion's path and incorporates results from Monte Carlo simulation of electron tracks to predict frequency distributions for ions, including their dependence on radial distance. The contribution from primary ion events is treated using an impact parameter formalism of spatially restricted linear energy transfer (LET) and energy-transfer straggling. We validate our model by comparing it directly to results from Monte Carlo simulations for proton and alpha-particle tracks. We show for the first time frequency distributions of energy imparted in DNA structures by several high-energy ions such as cosmic-ray iron ions. Our comparison with results from Monte Carlo simulations at low energies indicates the accuracy of the method.

  12. 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 (p0.05). 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.

  13. 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.

  14. 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.

  15. Energy Conversion and Particle Acceleration during Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Li, X.; Guo, F.; Daughton, W. S.; Li, H.; Li, S.; Liu, Y. H.; Li, G.

    2014-12-01

    We study energy conversion and particle acceleration during magnetic reconnection starting from a force-free current layer using two-dimensional particle-in-cell (PIC) simulations and high-Lundquist-number MHD simulations. In PIC simulations of collisionless magnetic reconnection, pressure anisotropy develops and is found to be stronger for particles with higher energies. When an external guide field is added, the pressure anisotropy is stronger with the magnitude of guide field. The energy conversion and particle acceleration through particle guiding center drifts, magnetization current, and parallel electric field are quantitatively evaluated and compared for a range of guide fields. The results are then explained using an electric current description associated with pressure anisotropy. This description is further used to study energy conversion during reconnection in high-Lundquist-number MHD simulations, where plasma pressure is assumed to be isotropic, and energy conversion is from compressional and Ohmic heating. These results demonstrate the importance of considering the influence of anisotropic velocity distributions on particle acceleration during magnetic reconnection.

  16. Cross-Section Measurements of alpha-particle Capture Reactions Relevant to the P Process: The Case of {sup 65}Cu({alpha},{gamma}){sup 69}Ga

    SciTech Connect

    Lagoyannis, A.; Konstantinopoulos, T.; Demetriou, P.; Harissopulos, S.; Becker, H.-W.

    2008-05-12

    The cross sections of the {sup 65}Cu({alpha},{gamma}){sup 69}Ga reaction were measured using the 4{pi} {gamma}-summing method. Angle-integrated {gamma}-fluxes were measured with a large volume NaI(Tl) detector. Statistical model calculations were performed using the MOST code. A very good agreement between theory and experiment was found.

  17. Analyzing power and cross section distributions of the {sup 12}C(p,p{alpha}){sup 8}Be cluster knockout reaction at an incident energy of 100 MeV

    SciTech Connect

    Mabiala, J.; Cowley, A. A.; Foertsch, S. V.; Buthelezi, E. Z.; Neveling, R.; Smit, F. D.; Steyn, G. F.; Van Zyl, J. J.

    2009-05-15

    The (p,p{alpha}) reaction on {sup 12}C was investigated experimentally using polarized incident protons of 100 MeV. The scattered proton and {alpha} particle, from the knockout reaction, were detected in coincidence. Coincident data, which were obtained at ten quasifree angle pairs for proton angles ranging from 25 deg. to 110 deg., were analyzed in terms of the distorted-wave impulse approximation (DWIA). Calculated energy-sharing cross section and analyzing power distributions reproduce the data reasonably well, indicating that a quasifree knockout mechanism dominates the reaction. Since measurements of analyzing powers were made, spin-orbit distortions were included in the DWIA calculations. The effects of this were found to be very small near zero recoil momentum and did not destroy the validity of the factorization approximation where the two-body p-{alpha} cross section enters as a multiplicative factor in the three-body (p,p{alpha}) cross section expression. Spectroscopic factors derived from the data are consistent with theoretical predictions. Analyzing power data also follow the trend of free p-{sup 4}He scattering data, and comparisons with DWIA predictions are in reasonable agreement. Because the two-body interaction response between the projectile and the {alpha} cluster was found to resemble the scattering of protons from a free {alpha} particle to a remarkable degree, the present results would strongly imply the existence of preformed {alpha} clusters in {sup 12}C.

  18. Elementary particle physics and high energy phenomena

    SciTech Connect

    Barker, A.R.; Cumalat, J.P.; de Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.

    1992-06-01

    This report discusses the following research in high energy physics: the properties of the z neutral boson with the SLD detector; the research and development program for the SDC muon detector; the fixed-target k-decay experiments; the Rocky Mountain Consortium for HEP; high energy photoproduction of states containing heavy quarks; and electron-positron physics with the CLEO II and Mark II detectors. (LSP).

  19. Calculation of the quasi-energies and resonances behavior of the hydrogen Lyman-alpha problem

    NASA Technical Reports Server (NTRS)

    Ruyten, Wilhelmus M.

    1992-01-01

    Recently, Bakshi and Kalman presented numerical results for the quasi-energies of the n = 2 multiplet in the hydrogen Lyman-alpha transition for a plasma in which both strong static and oscillating electric fields are present. Recent work on related magnetic and optical resonance problems provides a simplified mathematical treatment, as well as greater insight into the complex resonance behavior of this interaction.

  20. Calculation of the quasi-energies and resonances behavior of the hydrogen Lyman-alpha problem

    NASA Astrophysics Data System (ADS)

    Ruyten, Wilhelmus M.

    1992-03-01

    Recently, Bakshi and Kalman presented numerical results for the quasi-energies of the n = 2 multiplet in the hydrogen Lyman-alpha transition for a plasma in which both strong static and oscillating electric fields are present. Recent work on related magnetic and optical resonance problems provides a simplified mathematical treatment, as well as greater insight into the complex resonance behavior of this interaction.

  1. Search for Evidence of Alpha-Particle Beams during a Solar Flare Observed by the Coronal Diagnostic Spectrometer aboard the Solar and Heliospheric Observatory

    NASA Astrophysics Data System (ADS)

    Brosius, Jeffrey W.

    2001-07-01

    We observed NOAA Active Region 9090 (N13, W39) with the Coronal Diagnostic Spectrometer (CDS) and the Extreme-Ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory spacecraft between 18:17 and 21:09 UT on 2000 July 24 to search for evidence of alpha-particle beams during solar flares. Theoretically, an alpha-particle beam will manifest itself during the impulsive phase of a flare through an enhancement in the red wing of the He II Ly? (?303.782) emission line without a corresponding blue wing enhancement. This enhancement is due to downstreaming nonthermal alpha particles undergoing charge-exchange with chromospheric neutral hydrogen atoms to form downstreaming nonthermal He II ions. Ly? radiation emitted from these downstreaming ions is Doppler-shifted into the red wing of the Ly? line. Our CDS observing program acquired high time resolution (9.7 s) 4''4' slit spectra between 590 and 630 , where we observed He II Ly? in second order (?607.564). The CDS and EIT observations reveal that AR 9090 underwent significant intensity fluctuations prior to a sudden drastic increase (impulsive phase) around 20:00 UT. The GOES satellite reports a C3.8 event in this region from 19:57 to 20:05 UT. We fitted the spectral background and emission-line profiles for each CDS spectrum in our observed sequence. Density- and temperature-insensitive intensity ratios of O IV and Mg X lines generally agree with their theoretical values before and after the sudden intensity increase, which supports a reliable relative radiometric calibration for CDS, but differ significantly from their theoretical values during the flare impulsive phase. This may indicate line blending with unknown components, line blending with second-order C IV and Fe XV lines, or loss of ionization equilibrium. Most important, however, we find that although the red and blue wing backgrounds for He II Ly? remain relatively constant during most of our observation, the blue wing undergoes a more significant enhancement during the impulsive phase than does the red wing. This effect is opposite to that expected in the presence of an alpha-particle beam. Furthermore, blended spectral line features that mimic the expected nonthermal redshifted He II Ly? beam signal are understood in terms of well-known emission-line components. Thus, we find no evidence for the presence of alpha-particle beams in our observations. We estimate an upper limit of ~250 ergs cm-2 s-1 sr-1 -1 for the nonthermal redshifted peak spectral intensity due to an alpha-particle beam prior to the impulsive phase.

  2. Alpha-cluster description of excitation energies in 12C(12C,3 alpha)X at 2.1A GeV.

    PubMed

    Cucinotta, F A; Dubey, R R

    1994-08-01

    An alpha-cluster expansion of the Glauber multiple scattering [correction of scatteirng] series is used to calculate the energy transfer spectrum to the 12C projectile in the 12C(12C,3 alpha)X reaction at 2.1A GeV. Cluster-abrasion response functions are defined in terms of alpha-cluster wave function and the collision dynamics appropriate for heavy-ion reactions. Comparisons are made to recent quasiexclusive experimental data with good agreement found. Calculations indicate that substructures in a 12C projectile are likely to be true spectators in fragmentation, however, with virtual states of excitation in the projectile ground state making a significant contribution to the fragmentation cross section. PMID:9969752

  3. (Medium energy particle physics): Annual progress report

    SciTech Connect

    Nefkens, B.M.K.

    1985-10-01

    Investigations currently carried out by the UCLA Particle Physics Research Group can be arranged into four programs: Pion-Nucleon Scattering; Tests of Charge Symmetry and Isospin Invariance; Light Nuclei (Strong Form Factors of /sup 3/H, /sup 3/He, /sup 4/He; Detailed Balance in pd /r reversible/ /gamma//sup 3/H; Interaction Dynamics); and Search for the Rare Decay /Mu//sup +/ /yields/ e/sup +/ + /gamma/ (MEGA). The general considerations which led to the choice of physics problems investigated by our group are given in the next section. We also outline the scope of the research being done which includes over a dozen experiments. The main body of this report details the research carried out in the past year, the status of various experiments, and new projects.

  4. High-Energy Particles from ?-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Waxman, Eli

    The widely accepted interpretation of the phenomenology of ?-ray bursts (GRBs), bursts of 0.1 MeV-1 MeV photons lasting for a few seconds (see [1] for a review), is that the observable effects are due to the dissipation of the kinetic energy of a relativistically expanding wind, a "fireball", whose primal cause is not yet known (see [2,3] for reviews). The recent detection of "afterglows", delayed low energy (X-ray to radio) emission of GRBs (see [4] for review), confirmed the cosmological origin of the bursts, through the redshift determination of several GRB host-galaxies, and confirmed standard model predictions of afterglows that result from the collision of an expanding fireball with its surrounding medium (see [5] for review). In this review, the production in GRB fireballs of ?-rays, high-energy cosmic-rays and neutrinos is discussed in the light of recent GRB and ultra-high-energy cosmic-ray observations.Based on lectures given at the ICTP Summer School on Astroparticle Physics and Cosmology (ICTP, Trieste Italy, June 2000), and at the VI Gleb Wataghin School on High Energy Phenomenology (UNICAMP, Campinas Brazil, July 2000).

  5. Confinement of high energy trapped particles in tokamaks

    SciTech Connect

    Goldston, R.J.; White, R.B.; Boozer, A.H.

    1981-04-01

    The banana orbits of high energy trapped particles in tokamaks are found to diffuse rapidly in the radial direction if the toroidal ripple exceeds a low critical value. During this diffusion the energy, the magnetic moment, and the value of the magnetic field strength at the banana tips are conserved.

  6. Confinement of high-energy trapped particles in tokamaks

    SciTech Connect

    Goldston, R.J.; White, R.B.; Boozer, A.H.

    1981-08-31

    The banana orbits of high-energy trapped particles in tokamaks are found to diffuse rapidly in the radial direction if the toroidal ripple exceeds a low critical value. During this diffusion the energy, the magnetic moment, and the value of the magnetic field strength at the banana tips are conserved.

  7. Particle Energy Spectrum, Revisited from a Counting Statistics Perspective

    SciTech Connect

    2012-07-28

    In nuclear science, gamma and neutron spectra are counted energy by energy, and then particle by particle. Until recently, few studies have been performed on how exactly those energy spectra are counted, or how those counts are correlated. Because of lack of investigation, cross section covariance and correlation matrices are usually estimated using perturbation method. We will discuss a statistical counting scheme that shall mimic the gamma and neutron counting process used in nuclear science. From this counting scheme, the cross section covariance and correlation can be statistically derived.

  8. EDITORIAL: Focus on high energy particles and atmospheric processes

    NASA Astrophysics Data System (ADS)

    Harrison, R. Giles; Nicoll, Keri; Takahashi, Yukihiro; Yair, Yoav

    2015-10-01

    The letters published in the Focus issue on high energy particles and atmospheric processes serve to broaden the discussion about the influence of high energy particles on the atmosphere beyond their possible effects on clouds and climate. These letters link climate and meteorological processes with atmospheric electricity, atmospheric chemistry, high energy physics and aerosol science from the smallest molecular cluster ions through to liquid droplets. Progress in such a disparate and complex topic is very likely to benefit from continued interdisciplinary interactions between traditionally distinct science areas.

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

    PubMed Central

    Riquier, Hlne; Abel, Denis; Wera, Anne-Catherine; Heuskin, Anne-Catherine; Genard, Graldine; Lucas, Stphane; Michiels, Carine

    2015-01-01

    Background: High-LET ion irradiation is being more and more often used to control tumors in patients. Given that tumors are now considered as complex organs composed of multiple cell types that can influence radiosensitivity, we investigated the effects of proton and alpha particle irradiation on the possible radioprotective cross-talk between cancer and endothelial cells. Materials and Methods: We designed new irradiation chambers that allow co-culture study of cells irradiated with a particle beam. A549 lung carcinoma cells and endothelial cells (EC) were exposed to 1.5 Gy of proton beam or 1 and 2 Gy of alpha particles. Cell responses were studied by clonogenic assays and cell cycle was analyzed by flow cytometry. Gene expression studies were performed using Taqman low density array and by RT-qPCR. Results: A549 cells and EC displayed similar survival fraction and they had similar cell cycle distribution when irradiated alone or in co-culture. Both types of irradiation induced the overexpression of genes involved in cell growth, inflammation and angiogenesis. Conclusions: We set up new irradiation chamber in which two cell types were irradiated together with a particle beam. We could not show that tumor cells and endothelial cells were able to protect each other from particle irradiation. Gene expression changes were observed after particle irradiation that could suggest a possible radioprotective inter-cellular communication between the two cell types but further investigations are needed to confirm these results. PMID:25794049

  10. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons. Specifically, SiC radiation detectors with larger areas and 100-micrometer thick active regions have been designed and manufactured according to detector-design specifications. Detectors based on a Schottky diode design were specified in order to minimize the effects of the detector entrance window on alpha particle measurements. During manufacture of the Schottky diodes, the manufacturer also provided a set of large-volume SiC p-i-n diodes for testing Extensive alpha particle measurements have been carried out to test and quantify the response of the SiC Schottky diodes. Exposures to 148-Gd, 213-Po, 217-At, 221-Fr, 225-Ac, 237-Np, 238-Pu, 240-Pu, and 242-Pu sources were used to obtain detailed alpha response data in the alpha energy range from 3182.787 keV to 8375.9 keV. The 148-Gd, 213-Po, 217-At, and 221-Fr sources provide energy-separated, mono-energetic alpha particle peaks which can be analyzed to provide detailed information on the energy response characteristics of the detectors. As was reported last year, a highly linear response was obtained between observed pulse height and alpha-particle energy over the entire energy range. Detailed full width at half maximum (FWHM) measurements were made for each of five mono-energetic peaks. The FWHM values ranged from 41.5 keV for 3182.787-keV 148-Gd (1.3% energy resolution) to 55.4 keV for 8379.5-keV 213-Po (0.66% energy resolution). Although these energy resolution values are comparable to those obtainable with silicon alpha-particle spectrometers and surpass the best values reported previously for SiC detectors, other factors in addition to the inherent SiC energy resolution contribute to the observed values and were evaluated. Details of the energy deposition processes that contribute to the FWHM were modeled with calculations using the SRIM-2003.26 code developed by Ziegler and Beirsack. Electronic and statistical broadening of the FWHM were also evaluated in order to isolate the component of the FWHM that is inherent to SiC semiconductor. It was found that the SRIM calculations systematically overestimated the range straggling component of the FWHM leading to calculated values that exceeded the measured total FWHM values. It is believed that the overestimates are a result of inherent limitations of the SRIM code. The range-straggling component of the measured energy resolution results primarily from energy-loss processes in the detector entrance window, which consists of thin layers of Au, Pt, and Ti. Therefore, it was decided to perform measurements to evaluate the range straggling component directly. For this purpose, a high-resolution (15 keV FWHM) Si alpha spectrometer was obtained.

  11. A Multi-port Low-Fluence Alpha-Particle Irradiator: Fabrication, Testing and Benchmark Radiobiological Studies

    PubMed Central

    Neti, Prasad V. S. V.; de Toledo, Sonia M.; Perumal, Venkatachalam; Azzam, Edouard I.; Howell, Roger W.

    2011-01-01

    A new multi-port irradiator, designed to facilitate the study of the effects of low fluences of α particles on monolayer cultures, has been developed. The irradiator consists of four individual planar 241Am α-particle sources that are housed inside a helium-filled Lucite chamber. Three of the radioactive sources consist of 20 MBq of 241Am dioxide foil. The fourth source, used to produce higher dose rates, has an activity of 500 MBq. The four sources are mounted on rotating turntables parallel to their respective 1.5-μm-thick Mylar exit windows. A stainless steel honeycomb collimator is placed between the four sources and their exit windows by a cantilever attachment to the platform of an orbital shaker that moves its table in an orbit of 2 cm. Each exit window is equipped with a beam delimiter to optimize the uniformity of the beam and with a high-precision electronic shutter. Opening and closing of the shutters is controlled with a high-precision timer. Custom-designed stainless steel Mylar-bottomed culture dishes are placed on an adapter on the shutter. The α particles that strike the cells have a mean energy of 2.9 MeV. The corresponding LET distribution of the particles has a mean value of 132 keV/μm. Clonogenic cell survival experiments with AG1522 human fibroblasts indicate that the RBE of the α particles compared to 137Cs γ rays is about 7.6 for this biological end point. PMID:15161346

  12. First Experimental Measurement of the {sup 18}O(p,{alpha}){sup 15}N Reaction at Astrophysical Energies

    SciTech Connect

    La Cognata, M.; Sergi, M. L.; Spitaleri, C.; Cherubini, S.; Gulino, M.; Kiss, G.; Lamia, L.; Pizzone, R. G.; Romano, S.; Mukhamedzhanov, A.; Goldberg, V.; Tribble, R.; Coc, A.; Hammache, F.; Sereville, N. de; Tumino, A.

    2010-11-24

    The {sup 18}O(p,{alpha}){sup 15}N and {sup 17}O(p,{alpha}){sup 14}N reactions are of primary importance in several as-trophysical scenarios, including nucleosynthesis inside Asymptotic Giant Branch stars and oxygen and nitrogen isotopic ratios in meteorite grains. They are also key reactions to understand exotic systems such as R-Coronae Borealis stars and novae. Thus, the measurement of their cross sections in the low energy region can be crucial to reduce the nuclear uncertainty on theoretical predictions, because the resonance parameters are poorly determined. The Trojan Horse Method, in its newly developed form particularly suited to investigate low-energy resonances, has been applied to the {sup 2}H({sup 18}O,{alpha}{sup 15}N)n and {sup 2}H({sup 17}O,{alpha}{sup 14}N)n reactions to deduce the {sup 18}O(p,{alpha}){sup 15}N and {sup 17}O(p,{alpha}){sup 14}N cross sections at low energies. Resonances in the {sup 18}O(p,{alpha}){sup 15}N and {sup 17}O(p,{alpha}){sup 14}N excitation functions have been studied and the resonance parameters deduced.

  13. Numerical evaluation of high energy particle effects in magnetohydrodynamics

    SciTech Connect

    White, R.B.; Wu, Y.

    1994-03-01

    The interaction of high energy ions with magnetohydrodynamic modes is analyzed. A numerical code is developed which evaluates the contribution of the high energy particles to mode stability using orbit averaging of motion in either analytic or numerically generated equilibria through Hamiltonian guiding center equations. A dispersion relation is then used to evaluate the effect of the particles on the linear mode. Generic behavior of the solutions of the dispersion relation is discussed and dominant contributions of different components of the particle distribution function are identified. Numerical convergence of Monte-Carlo simulations is analyzed. The resulting code ORBIT provides an accurate means of comparing experimental results with the predictions of kinetic magnetohydrodynamics. The method can be extended to include self consistent modification of the particle orbits by the mode, and hence the full nonlinear dynamics of the coupled system.

  14. Improved peak shape fitting in alpha spectra.

    PubMed

    Pomm, S; Caro Marroyo, B

    2015-02-01

    Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution. PMID:25497323

  15. Alpha Channeling in a Rotating Plasma

    SciTech Connect

    Abraham J. Fetterman and Nathaniel J. Fisch

    2008-09-23

    The wave-particle ?-channeling effect is generalized to include rotating plasma. Specifically, radio frequency waves can resonate with ? particles in a mirror machine with E B rotation to diffuse the ? particles along constrained paths in phase space. Of major interest is that the ?-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.

  16. Using energy peaks to measure new particle masses

    NASA Astrophysics Data System (ADS)

    Agashe, Kaustubh; Franceschini, Roberto; Kim, Doojin

    2014-11-01

    We discussed in arXiv:1209.0772 that the laboratory frame distribution of the energy of a massless particle from a two-body decay at a hadron collider has a peak whose location is identical to the value of this daughter's (fixed) energy in the rest frame of the corresponding mother particle. For that result to hold we assumed that the mother is unpolarized and has a generic boost distribution in the laboratory frame. In this work we discuss how this observation can be applied for determination of masses of new particles, with out requiring a full reconstruction of their decay chains or information about the rest of the event. We focus on a two-step cascade decay of a massive particle that has one invisible particle in the final state: C → Bb → Aab, where C, B and A are new particles of which A is invisible and a, b are visible particles. Combining the measurements of the peaks of energy distributions of a and b with that of the edge in their invariant mass distribution, we demonstrate that it is in principle possible to determine separately all three masses of the new particles, in particular, without using any measurement of missing transverse momentum. Furthermore, we show how the use of the peaks in an inclusive energy distribution is generically less affected (as compared to other mass measurement strategies) by combinatorial issues. For some simplified, yet interesting, scenarios we find that these combinatorial issues are absent altogether. As an example of this general strategy, we study SUSY models where gluino decays to an invisible lightest neutralino via an on-shell bottom squark. Taking into account the dominant backgrounds, we show how the mass of the bottom squark, the gluino and (for some class of spectra) that of the neutralino can be determined using this technique.

  17. Overview of high energy physics with polarized particles

    SciTech Connect

    Soffer, J. . Centre de Physique Theorique Brookhaven National Lab., Upton, NY )

    1990-08-01

    The purpose of this talk is to review spin effects in various areas of particle physics at high energy and by selecting the most interesting topics, to show the relevance of dealing with polarized particles. We will see that it provides crucial tests for the Standard Model and can give us clear signatures to uncover new interactions. We will also discuss some striking experimental facts recently observed in hadronic collisions and their implications for current theoretical ideas. 43 refs., 10 figs.

  18. Energy exchange in systems of particles with nonreciprocal interaction

    NASA Astrophysics Data System (ADS)

    Vaulina, O. S.; Lisina, I. I.; Lisin, E. A.

    2015-10-01

    A model is proposed to describe the sources of additional kinetic energy and its redistribution in systems of particles with a nonreciprocal interaction. The proposed model is shown to explain the qualitative specific features of the dust particle dynamics in the sheath region of an RF discharge. Prominence is given to the systems of particles with a quasi-dipole-dipole interaction, which is similar to the interaction induced by the ion focusing effects that occur in experiments on a laboratory dusty plasma, and with the shadow interaction caused by thermophoretic forces and Le Sage's forces.

  19. 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.

  20. A unified theory of resonant excitation of kinetic ballooning modes by energetic ions/alpha particles in tokamaks

    SciTech Connect

    Biglari, H.; Chen, L.

    1991-10-01

    A complete theory of wave-particle interactions is presented whereby both circulating and trapped energetic ions can destabilize kinetic ballooning modes in tokamaks. Four qualitatively different types of resonances, involving wave-precessional drift, wave-transit, wave-bounce, and precessional drift-bounce interactions, are identified, and the destabilization potential of each is assessed. For a characteristic slowing-down distribution function, the dominant interaction is that which taps those resonant ions with the highest energy. Implications of the theory for present and future generation fusion experiments are discussed. 16 refs.

  1. Charged-particle multiplicity at LHC energies

    ScienceCinema

    None

    2011-10-06

    The talk presents the measurement of the pseudorapidity density and the multiplicity distribution with ALICE at the achieved LHC energies of 0.9 and 2.36 TeV.An overview about multiplicity measurements prior to LHC is given and the related theoretical concepts are briefly discussed.The analysis procedure is presented and the systematic uncertainties are detailed. The applied acceptance corrections and the treatment of diffraction are discussed.The results are compared with model predictions. The validity of KNO scaling in restricted phase space regions is revisited. 

  2. 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 quarks and gluons.

  3. 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.

  4. Numerical investigation on the stabilization of the deceleration phase Rayleigh-Taylor instability due to alpha particle heating in ignition target

    NASA Astrophysics Data System (ADS)

    Fan, Zhengfeng; Zhu, Shaoping; Pei, Wenbing; Ye, Wenhua; Li, Meng; Xu, Xiaowen; Wu, Junfeng; Dai, Zhensheng; Wang, Lifeng

    2012-09-01

    Tritium-hydrogen-deuterium (THD) target is adopted in order to experimentally diagnose the properties of the ignition hot spot and the highly compressed main fusion fuel (Edwards M. J. et al., Phys. Plasmas, 18 (2011) 051003). As compared with deuterium-tritium (DT) target, the thermonuclear alpha particles which are needed to heat the fusion fuel, are much less in the THD target. In the present paper, the effect of alpha particle heating on the deceleration phase Rayleigh-Taylor instability (dp-RTI), which is one of the key problems in hot spot formation, is investigated systematically through numerical simulations. It is found that the mass ablation at the hot spot boundary is greatly increased due to the direct alpha particle heating. As a result, the dp-RTI growth rates are greatly reduced and the cut-off mode number decreases greatly from about 33 to 17. This explains why the hydrodynamic instability in the THD target grows more severely than in the DT ignition target.

  5. R-matrix description of particle energy spectra produced by low-energy 3H + 3H reactions

    SciTech Connect

    Brune, C. R.; Caggiano, J. A.; Sayre, D. B.; Bacher, A. D.; Hale, G. M.; Paris, M. W.

    2015-07-20

    An R-matrix model for three-body final states is presented and applied to a recent measurement of the neutron energy spectrum from the 3H + 3H→ 2n + α reaction. The calculation includes the n alpha and n n interactions in the final state, angular momentum conservation, antisymmetrization, and the interference between different channels. A good fit to the measured spectrum is obtained, where clear evidence for the 5He ground state is observed. The model is also used to predict the alpha-particle spectrum from 3H + 3H as well as particle spectra from 3He + 3He. The R-matrix approach presented here is very general, and can be adapted to a wide variety of problems with three-body final states.

  6. Alpha Channeling in Mirror Machines

    SciTech Connect

    Fisch, N. J.

    2006-12-01

    The injection of radio frequency waves can cool charged particles trapped in a magnetic mirror. This cooling effect relies upon waves with azimuthal and axial phase velocities resonating with ions in different axial locations. The ions are then forced to diffuse along highly constrained orbits, such that they can only exit the magnetic trap at low energy. This cooling effect may have application to magnetic fusion mirror machines, where the free energy of the fusion by-products, the {alpha} particles, might be channeled into the waves that effect the cooling, thereby both extracting the fusion ash quickly and making that energy available in a convenient form for more useful purposes.

  7. Alpha channeling in mirror machines.

    PubMed

    Fisch, N J

    2006-12-01

    The injection of radio frequency waves can cool charged particles trapped in a magnetic mirror. This cooling effect relies upon waves with azimuthal and axial phase velocities resonating with ions in different axial locations. The ions are then forced to diffuse along highly constrained orbits, such that they can only exit the magnetic trap at low energy. This cooling effect may have application to magnetic fusion mirror machines, where the free energy of the fusion by-products, the alpha particles, might be channeled into the waves that effect the cooling, thereby both extracting the fusion ash quickly and making that energy available in a convenient form for more useful purposes. PMID:17155807

  8. 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. Klingelhöfer et al., The Rosetta Alpha Particle X-ray Spectrometer (APXS), Space Science Reviews, Vol.128 (2007) 383-396;

  9. Beta/alpha continuous air monitor

    SciTech Connect

    Becker, G.K.; Martz, D.E.

    1989-12-19

    This patent describes an air monitor. It is comprised of: spectrographic detection means for sampling, measuring, and graphically displaying the energy levels of alpha and beta particles, curve fitting means for extrapolating curves depicting repeated measurements of the energy levels, and alarm means for signaling significant deviations from the extrapolated curves.

  10. 12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments

    SciTech Connect

    Kugland, N; Constantin, C G; Niemann, C; Neumayer, P; Chung, H; Doppner, T; Kemp, A; Glenzer, S H; Girard, F

    2008-04-22

    A high contrast 12.6 keV Kr K{alpha} source has been demonstrated on the petawatt-class Titan laser facility. The contrast ratio (K{alpha} to continuum) is 65, with a competitive ultra short pulse laser to x-ray conversion efficiency of 10{sup -5}. Filtered shadowgraphy indicates that the Kr K{alpha} and K{beta} x-rays are emitted from a roughly 1 x 2 mm emission volume, making this source suitable for area backlighting and scattering. Spectral calculations indicate a typical bulk electron temperature of 50-70 eV (i.e. mean ionization state 13-16), based on the observed ratio of K{alpha} to K{beta}. Kr gas jets provide a debris-free high energy K{alpha} source for time-resolved diagnosis of dense matter.

  11. Analytical description of nonlinear particle transport in slab turbulence: High particle energies and stochastic acceleration

    SciTech Connect

    Shalchi, A.

    2012-10-15

    Pitch-angle scattering, parallel spatial diffusion, and stochastic acceleration of cosmic rays are investigated analytically. Based on a second-order quasilinear theory, we derive analytical expressions for the aforementioned transport parameters for all possible magnetic field strengths and particle energies. This work complements previous work where only parallel diffusion for low energetic particles was considered. Furthermore, we compute the first time the momentum diffusion coefficient. It is also shown that the relation between the momentum diffusion coefficient and the parallel spatial diffusion coefficient is more complicated than assumed in previous work.

  12. On the origin of ultra high energy cosmic ray particles

    NASA Astrophysics Data System (ADS)

    Thielheim, K. O.

    1998-06-01

    Understanding physical mechanisms by which Nature succeeds in bestowing `macroscopic' amounts of energy on single `microscopic' particles remains one of the greatest challenges for both, astrophysicists seeking to understand the functioning of cosmic objects, and accelerator designers inventing new conjectures for more powerful machines. The first and introductory chapter of this contribution is a short retrospective on our early research work, in the `Mathematical Physics Division' at Kiel, on the origin of Ultra High Energy Cosmic Ray Particles (UHECRP), beginning in the sixties and seventies with studies on Atmospheric Particle Propagation, proceeding in the seventies and eighties to investigations on Galactic Particle Transfer, and leading in the eighties and nineties to our present work on mechanisms for particle acceleration in pulsar magnetospheres. Cosmic rays, more than many fields of research, are found to be closely related to other branches of physics2. When looking on powerful cosmic accelerators from the point of view of fundamental physics, one has to study charged particle dynamics in extremely strong electromagnetic fields, of a kind that is expected near the surface of rapidly rotating, strongly magnetized neutron stars. Conventional Maxwell Theory (MT), for clearly discernable reasons, does not provide an adequate theoretical means of description in this case. Selfconsistent Electrodynamics (SCED), distinguished from MT through some of its essential premises offers itself, alternatively, as an appropriate language. Therefore, in the second chapter of my talk, I shall outline some features of SCED and reproduce the equation of particle motion on these grounds. In the third and concluding chapter, I shall discuss a mechanism to create very narrow bundles of energetic particles in the polar regions of aligned rotators3.

  13. The enhancement of the alpha track revelation in Lexan and LR-115 by ultrasonic etching

    NASA Astrophysics Data System (ADS)

    Su, Ching-Shen

    1989-11-01

    The revelation of alpha particle tracks in Lexan polycarbonate and in LR-115 cellulose nitrate has been enhanced by the ultrasonic etching process. Alpha particles from 244Cm and 147Sm radioactive sources were used to irradiate the samples. The energies of the alpha particles were obtained by selecting the source to detector distances to give the required energy attenuations of the alpha particles by the air absorber. Alpha particles of energies from approximate 0.1 MeV to 5.8 MeV have been registered in Lexan and LR-115 and the ultrasonic etching process was used to reveal the tracks. Comparisons of the ultrasonic etching with the standard chemical etching of the samples at the same etching conditions have been made, and the mechanism of the enhancement of track revelation by ultrasonic wave has also been discussed.

  14. Consistent energy barrier distributions in magnetic particle chains

    NASA Astrophysics Data System (ADS)

    Laslett, O.; Ruta, S.; Chantrell, R. W.; Barker, J.; Friedman, G.; Hovorka, O.

    2016-04-01

    We investigate long-time thermal activation behaviour in magnetic particle chains of variable length. Chains are modelled as Stoner-Wohlfarth particles coupled by dipolar interactions. Thermal activation is described as a hopping process over a multidimensional energy landscape using the discrete orientation model limit of the Landau-Lifshitz-Gilbert dynamics. The underlying master equation is solved by diagonalising the associated transition matrix, which allows the evaluation of distributions of time scales of intrinsic thermal activation modes and their energy representation. It is shown that as a result of the interaction dependence of these distributions, increasing the particle chain length can lead to acceleration or deceleration of the overall relaxation process depending on the initialisation procedure.

  15. An Alpha Schottky Junction Power Source

    NASA Astrophysics Data System (ADS)

    Litz, Marc; Carroll, James; Henriquez, Stan

    2011-10-01

    Isotope batteries present solutions for long-lived low power sources. Compact sensors, and electronic circuit boards can be powered for the lifetime of infrastructure. Alpha sources are practical for safety reasons because of the limited distance before energy absorption in materials, and the high energy (~5MeV) per particle. Damage to materials from the alphas limits the practical use. A Schottky diode geometry is created from an alpha foil on a diamond-like crystal. A power source is proposed that takes advantage of the radiation damage tolerance of diamond, combined with the short range of the alpha radiation. The internal field of the Schottky barrier creates a current through the diode from electron-hole pairs created by alpha bombardment in the gap. Calculations of the expected current, circuit model results, and design parameters for a device are described.

  16. Radioastronomical measurement of ultrahigh-energy cosmic particle fluxes

    NASA Astrophysics Data System (ADS)

    Filonenko, A. D.

    2012-08-01

    The basic principles underlying the radio telescope measurement of ultrahigh-energy particle fluxes are reviewed. Experimental lunar regolith emission data are presented for the 10^{20} eV energy range. Some conclusions from theoretical work are discussed, as is the influence of a number of factors on the intensity of the radio pulse due to the cascade disk under the Moon's surface.

  17. Lyman Alpha Emitting Galaxies at 2 < z < 3: Towards a Calibrated Probe of Dark Energy

    SciTech Connect

    Caryl Gronwall

    2012-12-03

    The goal of this project was to establish the physical properties of Ly{alpha}#11;emitting galaxies from redshifts of 2 to 3 in order to better calibrate the use of LAEs as probes of the large scale structure of the universe for upcoming dark energy experiments, such as the Hobby Eberly Telescope Dark Energy Experiment (HETDEX). We have obtained narrow-band imaging of the Extended Chandra Deep Field South (ECDF-S) in two different narrow-band #12;filters centered at Ly{alpha}#11; at z=2.1 and 3.1. The resulting of samples of LAEs were used to determine the LAE luminosity function, equivalent width distribution and clustering properties (bias) of LAEs at these redshifts. While the results from the ECDF-S appear robust, they are based on a single field. To explore the effects of cosmic variance and galaxy environment on the physical properties of LAEs, we have also obtained narrow-band data at both redshifts (z = 2:1 and 3:1) in three additional #12;fields (SDSS 1030+-05, the Extended Hubble Deep Field South, and CW 1255+01). The narrow-band imaging data has been reduced and LAE catalogs are being generated. We have calculated preliminary luminosity functions, equivalent width distributions, and clustering properties. We have also obtained follow-up spectroscopy in the optical (using VLT/FORS) and in the near-infrared (using Magellan/MMIRS). Since individual LAEs have too little S/N to enable meaningful fits for stellar population parameters, our previous work has analyzed stacked Spectral Energy Distributions (SEDs). SED #12;fitting was performed on several subsets of LAEs selected by their rest-UV luminosity, UV spectral slope, Ly alpha luminosity, Equivalent Width, or rest-optical (IRAC) luminosity.

  18. Mass, Momentum and Kinetic Energy of a Relativistic Particle

    ERIC Educational Resources Information Center

    Zanchini, Enzo

    2010-01-01

    A rigorous definition of mass in special relativity, proposed in a recent paper, is recalled and employed to obtain simple and rigorous deductions of the expressions of momentum and kinetic energy for a relativistic particle. The whole logical framework appears as the natural extension of the classical one. Only the first, second and third laws of…

  19. Rotation as an origin of high energy particle collisions

    NASA Astrophysics Data System (ADS)

    Zaslavskii, O. B.

    2016-01-01

    We consider collision of two particles in rotating spacetimes without horizons. If the metric coefficient responsible for rotation of spacetime is big enough, the energy of collisions in the center of mass frame can be as large as one likes. This can happen in the ergoregion only. The results are model-independent and apply both to relativistic stars and wormholes.

  20. Energy conservation potential of Portland cement particle size distribution control

    SciTech Connect

    Tresouthick, S.W.; Weiss, S.J.

    1986-01-01

    The main objective of Phase 3 is to develop practical economic methods of controlling the particle size distribution of portland cements using existing or modified mill circuits with the principal aim of reducing electrical energy requirements for cement manufacturing. Because of its scope, the work of Phase 3 will be carried out in 10 main tasks, which will be discussed in this report.