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1

Alpha particle nonionizing energy loss (NIEL) for device applications  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

2

Alpha-particle diagnostics  

SciTech Connect

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.

Young, K.M.

1991-01-01

3

Utility of extracting {alpha}-particle energy by waves  

SciTech Connect

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

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

1994-05-01

4

Nuclear reactions induced by high-energy alpha particles  

NASA Technical Reports Server (NTRS)

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.

Shen, B. S. P.

1974-01-01

5

On the correlation between the binding energies of the triton and the alpha-particle  

E-print Network

We consider the correlation between the binding energies of the triton and the alpha-particle which is empirically observed in calculations employing different phenomenological nucleon-nucleon interactions. Using an effective quantum mechanics approach for short-range interactions with large scattering length |a| >> l, where l is the natural low-energy length scale, we construct the effective interaction potential at leading order in l/|a|. In order to renormalize the four-nucleon system, it is sufficient to include a SU(4)-symmetric one-parameter three-nucleon interaction in addition to the S-wave nucleon-nucleon interactions. The absence of a four-nucleon force at this order explains the empirically observed correlation between the binding energies of the triton and the alpha-particle. We calculate this correlation and obtain a prediction for the alpha-particle binding energy. Corrections to our results are suppressed by l/|a|.

L. Platter; H. -W. Hammer; U. -G. Meißner

2004-11-22

6

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

SciTech Connect

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.

Agarwal, S.; Chatterjee, S.N.

1984-11-01

7

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

SciTech Connect

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.

Farengo, R. [Comisión Nacional de Energía Atómica, Centro Atómico Bariloche e Instituto Balseiro, 8400 Bariloche, RN (Argentina); Ferrari, H. E. [Comisión Nacional de Energía Atómica, Centro Atómico Bariloche e Instituto Balseiro, 8400 Bariloche, RN (Argentina); CONICET, 8400 Bariloche, RN (Argentina); Garcia-Martinez, P. L. [CONICET, 8400 Bariloche, RN (Argentina); Firpo, M.-C.; Ettoumi, W. [Laboratoire de Physique des Plasmas, CNRS, Ecole Polytechnique, 91128, Palaiseau cedex (France); Lifschitz, A. F. [Laboratoire d'Optique Appliquee, ENSTA, CNRS, Ecole Polytechnique, 91761 Palaiseau cedex (France)

2014-08-15

8

Imaging alpha particle detector  

DOEpatents

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.

Anderson, D.F.

1980-10-29

9

Imaging alpha particle detector  

DOEpatents

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.

Anderson, David F. (Los Alamos, NM)

1985-01-01

10

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

SciTech Connect

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.

Espinosa Garcia, Guillermo [ORNL; Golzarri y Moreno, Dr. Jose Ignacio [Instituto de Fisica, Mexico; Bogard, James S [ORNL

2008-01-01

11

Alpha particle emitters in medicine  

SciTech Connect

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.

Fisher, D.R.

1989-09-01

12

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

SciTech Connect

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.

Kerns, J.A.

1986-05-01

13

Modeling energy deposition and cellular radiation effects in human bronchial epithelium by radon progeny alpha particles  

SciTech Connect

Energy deposition and cellular radiation effects arising from the interaction of single {sup 218}Po and {sup 214}Po alpha particles with basal and secretory cell nuclei were simulated for different target cell depths in the bronchial epithelium of human airway generations 2, 4, 6, and 10. To relate the random chord lengths of alpha particle tracks through spherical cell nuclei to the resulting biological endpoints, probabilities per unit track length for different cellular radiation effects as functions of LET were derived from in vitro experiments. The radiobiological data employed in the present study were inactivation and mutation (mutant frequency at the HPRT gen) in V70 Chinese hamster cells and inactivation and transformation in C3H 10T1/2 cells. Based on computed LET spectra and relative frequencies of target cells, probabilities for transformation, mutation, and cell killing in basal and secretory cells were computed for a lifetime exposure of 20 WLM. While predicted transformation probabilities were about two orders of magnitude higher than mutation probabilities, they were still about two orders of magnitude lower than inactivation probabilities. Furthermore, transformation probabilities for basal cells are generally higher than those for secretory cells, and {sup 214}Po alpha particles are primarily responsible for transformation in bronchial target cells.

Hofmann, W.; Menache, M.G.; Crawford-Brown, D.J.; Caswell, R.S.; Karam, L.R.

2000-04-01

14

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

SciTech Connect

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.

Horansky, Robert D.; Stiehl, Gregory M.; Beall, James A.; Irwin, Kent D.; Ullom, Joel N. [National Institute of Standards and Technology, 325 Broadway MS 817.03, Boulder, Colorado (United States); Plionis, Alexander A.; Rabin, Michael W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2010-02-15

15

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

SciTech Connect

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

Avrigeanu, M. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 76900 Bucharest (Romania)], E-mail: mavrig@ifin.nipne.ro; Obreja, A.C.; Roman, F.L.; Avrigeanu, V. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 76900 Bucharest (Romania); Oertzen, W. von [Freie Universitaet Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin (Germany); Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin (Germany)

2009-07-15

16

Nuclear diagnostic for fast alpha particles  

DOEpatents

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.

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

1983-11-23

17

Long range alpha particle detector  

DOEpatents

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.

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

1993-02-02

18

Long range alpha particle detector  

DOEpatents

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.

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

19

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

SciTech Connect

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.

Kumar, Pawan; Singh, Vishwesh; Tripathi, V. K. [Department of Physics, IIT Delhi, New Delhi-110016 (India)

2013-02-15

20

Radioluminescence yield of alpha particles in air  

NASA Astrophysics Data System (ADS)

Alpha particles can be detected by measuring the radioluminescence light which they induce when absorbed in air. The light is emitted in the near ultraviolet region by nitrogen molecules excited by secondary electrons. The accurate knowledge of the radioluminescence yield is of utmost importance for novel radiation detection applications utilizing this secondary effect. Here, the radioluminescence yield of an alpha particle is investigated as a function of energy loss in air for the first time. Also, the total radioluminescence yield of the particle is measured with a carefully calibrated ^{239}Pu emitter used in the experiments. The obtained results consistently indicate that alpha particles generate 19±3 photons per one MeV of energy released in air at normal pressure (temperature 22°C, relative humidity 43%) and the dependence is found to be linear in the studied energy range from 0.3 MeV to 5.1 MeV. The determined radioluminescence yield is higher than previously reported for alpha particles and similar to the radioluminescence yield of electrons at comparable energies. This strengthens the evidence that the luminescence induced by charged particles is mostly proportional to the energy loss in the media and not very sensitive to the type of primary particle.

Sand, J.; Ihantola, S.; Peräjärvi, K.; Toivonen, H.; Toivonen, J.

2014-05-01

21

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

SciTech Connect

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.

Hudson, H. S. [SSL, UC Berkeley, CA 94720 (United States); Fletcher, L.; MacKinnon, A. L. [School of Physics and Astronomy, SUPA, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Woods, T. N., E-mail: hhudson@ssl.berkeley.edu [Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Dr., Boulder, CO 80303 (United States)

2012-06-20

22

ALPHA PARTICLE ENERGY RESPONSE OF 1-MM-THICK POLYCARBONATE TRACK DETECTORS BY 50 HZ-HV ELECTROCHEMICAL ETCHING METHOD.  

PubMed

The electrochemical etching (ECE) method enlarges charged particle tracks to enhance its applications in particular in health physics and radiation dosimetry. The ECE method is usually based on using a high frequency-high voltage (HF-HV) generator with 250-µm-thick polycarbonate track detectors (PCTDs). The authors' recent studies on nitrogen and helium ions and alpha tracks in 1-mm-thick large-size PCTDs under a 50 Hz-HV ECE process provided promising results. In this study, alpha track efficiency and mean track diameter versus energy responses and registration energy range as well as alpha and background track shapes under three sets of 50 Hz-4, 5 and 6 kV applied field conditions have been studied and are reported. The efficiency versus alpha energy has a Bragg-type response from ?15 keV to ?4.5 MeV for the field conditions applied with an efficiency value of 40-50 % at the Bragg peak. The results are presented and discussed. PMID:25301970

Sohrabi, M; Ramezani, V

2014-10-01

23

Energy loss straggling of 5.486 MeV alpha-particles in PP, PET and KAPTON polymeric foils.  

PubMed

The energy loss straggling for 5.486 MeV alpha-particles, from (241)Am source, in PP (C(3)H(6)), PET (C(10)H(8)O(4)) and KAPTON (C(22)H(10)O(5)N(2)) polymeric foils was measured. These measured values were compared with the most commonly used Bohr, Lindhard & Scharff and Bethe-Livingston formulations with the aim to check the reliability of these formulations. Further, Bethe-Livingston formulation has been suitably modified to make it applicable for thicker targets. PMID:20510624

Neetu; Sharma, K; Gulati, Pratibha K; Diwan, P K; Kumar, S

2010-12-01

24

Nuclear diagnostic for fast alpha particles  

DOEpatents

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.

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

1986-01-01

25

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

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.

Giorginis, Georgios [European Commission, Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440 Geel (Belgium); Khryachkov, Vitali [Institute for Physics and Power Engineering (IPPE), Bondarenko sq. 1, 249020 Obninsk, Kaluga Region (Russian Federation)

2005-05-24

26

Alpha particle analysis using PEARLS spectrometry  

SciTech Connect

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.

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

1984-01-01

27

Radioimmunotherapy with alpha-particle-emitting immunoconjugates  

SciTech Connect

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

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

1988-05-20

28

Prospects for alpha particle studies on TFTR  

SciTech Connect

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.

Zweben, S.J.

1987-05-01

29

A nuclear diagnostic for fast alpha particles  

Microsoft Academic Search

The authors investigate the possibility of seeding a fusion plasma with nuclei that can undergo nuclear reactions with energetic alpha particles to produce product nuclei that are radioactive. If a fraction of these product nuclei can be collected and measured, one can obtain information about the presence of fast alpha particles. It appears that a feasible diagnostic could be based

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

1983-01-01

30

[open quotes]Magic[close quotes] energies for detecting light elements with resonant alpha particle backscattering  

SciTech Connect

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 [open quotes]magic[close quotes] 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. [copyright] [ital 1999 American Institute of Physics.

Wetteland, C.J.; Maggiore, C.J.; Tesmer, J.R. (Center for Materials Science, Materials Science and Technology Division, Los Alamos National Laboratory (United States)); He, X.; Lee, D. (Structure/Property Relations, Materials Science and Technology Division, Los Alamos National Laboratory (United States))

1999-06-01

31

Energy-Dependence of Elastic Alpha-Particle Scattering - Microscopic Model  

E-print Network

(1962). PHYSIC AL RE VIE W C VO LUME 6, NUMB E R 4 OCTOBER 1972 Study of ( He, t) Reactions at 70 MeV to Isobaric Analog States of Cr, Ni, and Zr~ R. A. Hinrichs and D. L. Show Cyclotron Laboratory, Michigan State University, East Lansing, Michigan... on the energy dependence of the charge- exchange interaction. II. EXPERIMENTAL PROCEDURE AND RESULTS The reactions ~Cr, "Ni, "Zr('He, t) were studied at a bombarding energy of 70 MeV using 'He ions accelerated in the Michigan State Univer- sity sector...

Lerner, G. M.; Rutledge, L. L.; Hiebert, John C.; Bernstein, A. M.

1972-01-01

32

A High-Throughput Screen for Alpha Particle Radiation Protectants  

PubMed Central

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

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

2010-01-01

33

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

34

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

35

Control of alpha-particle transport by ion cyclotron resonance heating  

SciTech Connect

In this paper control of radial alpha-particle transport by using ion cyclotron range of frequency (ICRF) waves is investigated in a large-aspect-ratio tokamak geometry. Spatially inhomogeneous ICRF wave energy with properly selected frequencies and wave numbers can induce fast convective transports of alpha particles at the speed of order v{sub {alpha}} {approximately} (P{sub RF}/n{sub {alpha}}{epsilon}{sub 0}){rho}{sup p}, where R{sub RF} is the ICRF wave power density, n{sub {alpha}} is the alpha-particle density, {epsilon}{sub 0} is the alpha-particle birth energy, and {rho}{sub p} is the poloidal gyroradius of alpha particles at the birth energy. Application to International Thermonuclear Experimental Reactor (ITER) plasma is studied and possible antenna designs to control alpha-particle flux are discussed.

Chang, C.S.; Imre, K.; Weitzner, H.; Colestock, P. (Princeton Univ., NJ (United States). Plasma Physics Lab.)

1990-12-01

36

Cluster Expansion of Cold Alpha Matter Energy  

Microsoft Academic Search

In the cluster expansion framework of Bose liquids we calculate analytical expressions of the two-body, three-body and four-body diagrams contributing to the g.s. energy of an infinite system of neutral alpha-particles at zero-temperature, interacting via the strong nuclear forces exclusively. This is analytically tractable by assuming a density dependent two-body correlation function of Gaussian type. For the alpha-alpha potential we

F. Carstoiu; S Misicu; V. Balanica; M. Lassaut

2010-01-01

37

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

ERIC Educational Resources Information Center

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…

Andrews, D. G. H.

2008-01-01

38

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

E-print Network

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

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

2013-08-09

39

Actinium-225 in targeted alpha-particle therapeutic applications.  

PubMed

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

Scheinberg, David A; McDevitt, Michael R

2011-10-01

40

Alpha-particle sensitive test SRAMs  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

41

Alternating current long range alpha particle detector  

DOEpatents

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.

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

1993-02-16

42

The status of alpha-particle diagnostics  

SciTech Connect

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.

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

1992-01-01

43

The status of alpha-particle diagnostics  

SciTech Connect

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.

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

1992-08-01

44

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

SciTech Connect

Control of the radial alpha particle transport by using Ion Cyclotron Range of Frequency waves is investigated in a large-aspect-ratio tokamak geometry. It is shown that spatially inhomogeneous ICRF-wave energy with properly selected frequencies and wave numbers can induce fast convective transport of alpha particles at the speed of order {upsilon}{sub alpha} {approximately} (P{sub RF}/n{sub {alpha}}{epsilon}{sub 0}) {rho}{sub p}, where P{sub RF} is the ICRF-wave power density, n{sub {alpha}} is the alpha density, {epsilon}{sub 0} is the alpha birth energy, and {rho}{sub p} is the poloidal gyroradius of alpha particles at the birth energy. Application to ITER plasmas is studied and possible antenna designs to control alpha particle flux are discussed. 8 refs., 3 figs.

Chang, C.S.; Imre, K.; Weitzner, H. (New York Univ., NY (USA). Courant Inst. of Mathematical Sciences); Colestock, P. (Princeton Univ., NJ (USA). Plasma Physics Lab.)

1990-02-01

45

Lunar surface outgassing and alpha particle measurements  

SciTech Connect

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.

Lawson, S. L. (Stefanie L.); Feldman, W. C. (William C.); Lawrence, David J. (David Jeffery),; Moore, K. R. (Kurt R.); Elphic, R. C. (Richard C.); Maurice, S. (Sylvestre); Belian, Richard D.; Binder, Alan B.

2002-01-01

46

Light charged and neutral particle production in proton and alpha reactions on natSi at energies between 20 and 65 MeV  

SciTech Connect

Measurements have been performed to determine inclusive cross sections ((d{sup 2}{sigma}/d{omega}dE), (d{sigma}/dE), (d{sigma}/d{omega}) and {sigma}tot) for the production of neutral and light charged particles (LCP) induced by beams of protons of 26.5, 48.5 and 62.9 MeV and alpha's of 25.4, 45.5 and 57.8 MeV incident energies on natSi targets. The secondary LCPs (p, d, t, 3He, {alpha}, 6Li, 7Li and 7Be) were detected at angles from 10 deg. to 165 deg. in steps of {+-}10 deg. Neutrons emitted in these reactions were only recorded in coincidence with, at least, one detected LCP. Some comparisons between theoretical calculations based on the GNASH and TALYS nuclear reaction codes and the experimental results are presented and discussed.

Dufauquez, C.; El Masri, Y.; Roberfroid, V.; Cabrera, J.; Keutgen, Th.; Mol, J. van [FNRS, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Institut de Physique Nucleaire, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Demetriou, P. [Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles, 1050 Brussels (Belgium); Koning, A.J. [Nuclear Research and Consultancy Group, PO Box 25, 1755 ZG Petten (Netherlands)

2005-05-24

47

Performance comparison of scintillators for alpha particle detectors  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

48

The effect of alpha particles on bacteriophage T4Br+.  

PubMed

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

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

1983-01-01

49

Alpha Particle Physics Experiments in the Tokamak Fusion Test Reactor  

SciTech Connect

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

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

1998-12-14

50

The effects of alpha particle irradiation on stainless steel  

E-print Network

A Monte Carlo code was developed to calculate the alpha particle emission rate from WGPu. It yielded information pertaining to the alpha particle source strength at the WGPU and stainless steel interface as well as the damage production and He...

Shipp, John Douglas

1999-01-01

51

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

PubMed

The potential use of direct high-resolution alpha spectrometry to identify the presence of transactinium elements in air samples is illustrated in the case when alpha-particle-emitting radionuclides are incorporated in nuclear fuel particles. Alpha particle energy spectra are generated through Monte Carlo simulations assuming a nuclide composition similar to RBMK (Chernobyl) nuclear fuel. The major alpha-particle-emitting radionuclides, in terms of activity, are 242Cm, 239Pu and 240Pu. The characteristics of the alpha peaks are determined by fuel particle properties as well as the type of the air filter. It is shown that direct alpha spectrometry can be readily applied to membrane filter samples containing nuclear fuel particles when rapid nuclide identification is of relevance. However, the development of a novel spectrum analysis code is a prerequisite for unfolding complex alpha spectra. PMID:17951235

Pöllänen, R; Siiskonen, T

2008-01-01

52

Diamond detector for alpha-particle spectrometry.  

PubMed

An artificially grown high purity diamond was used as a detector for alpha-particle spectrometry. Diamond detectors can match the performance of silicon detectors employed in standard continuous air monitoring systems. Its radiation hardness and electronic properties make them ideal to work under extreme condition such as high temperature and ambient lights. A 50 ?m thickness single-crystal diamond detector has been compared with a 300 ?m passivated implanted planar silicon detector, under ambient conditions. PMID:24768983

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

2014-08-01

53

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

Microsoft Academic Search

The Lunar Prospector Alpha Particle Spectrometer (APS) was designed to detect characteristic-energy alpha particles from the decay of Rn-222, Po-218, and Po-210 and to therefore map sites of radon release on the lunar surface. These three nuclides are radioactive daughters from the decay of U-238; hence the background level of alpha particle activity is a function of the lunar crustal

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

2005-01-01

54

Alpha-particle-induced cancer in humans.  

PubMed

Updated information is given on alpha-particle-induced cancer in persons internally exposed to 222Rn progeny, Thorotrast, long-lived 226Ra and 228Ra, and short-lived 224Ra. The lung cancer risk to persons breathing 222Rn progeny in the indoor air of offices, schools, and homes is of increasing concern. About half of the recent deaths among the German Thorotrast patients have been from liver cancer. Animal studies indicate that the liver cancer risk from Thorotrast is mainly from its radioactivity and that the risk coefficient for the Thorotrast patients can be used provisionally for other alpha emitters in the human liver. Six skeletal cancers have occurred in persons with average skeletal doses between 0.85 and 11.8 Gy from 226Ra and 228Ra. In the low-dose German 224Ra patients, two skeletal sarcomas have occurred at about 0.7 Gy compared to about six cases predicted by results from 224Ra patients at higher doses. The minimal appearance time for radiation-induced bone sarcomas in humans is about 4 y. Following brief irradiation, the vast majority of induced bone sarcomas are expressed by about 30 y. Recent evidence against the "practical threshold" hypothesis is given. With the downward revision of neutron doses to the atomic-bomb survivors, the follow-up of persons exposed to alpha particles may be the best opportunity to evaluate directly the effects of high LET radiation on humans. PMID:2844697

Mays, C W

1988-10-01

55

Study of backscattering in alpha-particle sources with the new code AlfaMC  

NASA Astrophysics Data System (ADS)

The activity of alpha-particle sources with negligible thickness can be absolutely determined using 2? counting geometry detectors, requiring corrections for backscattering from the source backing. The experimental determination of these corrections is subject to large uncertainties, because the contribution of the backscattered alpha particles to the total counting is generally very low. An interesting alternative is then to use Monte Carlo methods which simulate the transport of alpha-particles into the source. The programme AlfaMC, a new Monte Carlo code developed to simulate specifically the transport of alpha particles, was here applied to the study of the backscattering in alpha-particle sources. Energy and angular distributions for the backscattered alpha particles were deeply analysed based on a multiple scattering process, as a result of a large number of weak collisions with atomic electrons. Some calculated values for the backscattering coefficient were compared with experimental values, showing a good agreement.

Vargas, M. Jurado; Timón, A. Fernández

2015-01-01

56

Fission studies with 140 MeV {alpha} particles  

SciTech Connect

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.

Buttkewitz, A.; Duhm, H. H.; Strauss, W. [I. Institut fuer Experimentalphysik, Universitaet Hamburg, Hamburg (Germany); Goldenbaum, F. [Institut fuer Kernphysik, Forschungszentrum Juelich, Juelich (Germany); Machner, H. [Institut fuer Kernphysik, Forschungszentrum Juelich, Juelich (Germany); Fachbereich Physik, Universitaet Duisburg-Essen, Duisburg (Germany)

2009-09-15

57

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

PubMed Central

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

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

2013-01-01

58

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

PubMed

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

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

2008-09-01

59

Cluster Expansion of Cold Alpha Matter Energy  

E-print Network

In the cluster expansion framework of Bose liquids we calculate analytical expressions of the two-body, three-body and four-body diagrams contributing to the g.s. energy of an infinite system of neutral alpha-particles at zero-temperature, interacting via the strong nuclear forces exclusively. This is analytically tractable by assuming a density dependent two-body correlation function of Gaussian type. For the alpha-alpha potential we adopt the phenomenological Ali-Bodmer interaction and semi-microscopic potentials obtained from the Gogny force parametrizations. We show that under such assumptions we achieve a rapid convergence in the cluster expansion, the four-body contributions to the energy being smaller than the two-body and three-body contributions by at least an order of magnitude.

F. Carstoiu; S Misicu; V. Balanica; M. Lassaut

2010-10-05

60

Cluster Expansion of Cold Alpha Matter Energy  

E-print Network

In the cluster expansion framework of Bose liquids we calculate analytical expressions of the two-body, three-body and four-body diagrams contributing to the g.s. energy of an infinite system of neutral alpha-particles at zero-temperature, interacting via the strong nuclear forces exclusively. This is analytically tractable by assuming a density dependent two-body correlation function of Gaussian type. For the alpha-alpha potential we adopt the phenomenological Ali-Bodmer interaction and semi-microscopic potentials obtained from the Gogny force parametrizations. We show that under such assumptions we achieve a rapid convergence in the cluster expansion, the four-body contributions to the energy being smaller than the two-body and three-body contributions by at least an order of magnitude.

Carstoiu, F; Balanica, V; Lassaut, M

2010-01-01

61

Nuclear techniques for determining the spatial and energy distribution of fast-confined alpha particles in ignited D--T plasma  

SciTech Connect

There are several nuclear reactions between fast-confined ..cap alpha.. particles and low-z ions in ignited D--T plasma. Some of them produce unique and highly penetrating neutron or ..gamma.. radiation. A study has begun to evaluate the feasibility of using these reactions to determine the spatial profile of fast-confined reaction product ..cap alpha.. particles, and to determine a crude envelope of their speed distribution as they thermalize. Particular attention is paid to the means of detecting these radiations, measuring their spectra, and most important of all, reducing and discriminating against the very much larger background of interfering radiation.

Slaughter, D.R.

1985-05-01

62

Turbulent transport of alpha particles in reactor plasmas  

SciTech Connect

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)

Estrada-Mila, C.; Candy, J.; Waltz, R. E. [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States); General Atomics, San Diego, California 92121 (United States)

2006-11-15

63

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

SciTech Connect

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.

Herrmann, Hans W.

1997-06-01

64

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

SciTech Connect

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.

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

1986-03-01

65

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

DOEpatents

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.

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

1983-11-16

66

High-energy resolution alpha spectrometry using cryogenic detectors.  

PubMed

Applications such as environment monitoring implying alpha emitters activity measurement associated with isotope identification, require high-energy resolution detectors. Conventional silicon detectors are inexpensive therefore widely used, although intrinsically limited in energy resolution. Thermal detection principle of cryogenic detectors introduces a breakthrough in alpha particle measurement. For the first time, spectra with 5.5 keV FWHM energy resolution have been obtained for several external alpha emitting sources using a copper-germanium bolometer specially developed for alpha spectrometry. PMID:16618545

Leblanc, E; Coron, N; Leblanc, J; de Marcillac, P; Bouchard, J; Plagnard, J

2006-01-01

67

Cross sections relevant to gamma-ray astronomy: Alpha-particle-induced reactions  

Microsoft Academic Search

Gamma-ray production cross sections have been measured for the gamma-ray lines most strongly excited in the alpha-particle bombardments of ²°Ne, ²⁴Mg, ²⁷Al, ²⁸Si, and ⁵⁶Fe for alpha-particle energies from threshold to approximately 27 MeV. Tabulations of cross sections averaged over alpha-particle energy bins of 1 MeV are provided for calculations relevant to gamma-ray line astronomy. Examples are given of astrophysical

Alan G. Seamster; Eric B. Norman; Donald D. Leach; P. Dyer; D. Bodansky

1984-01-01

68

Energetic alpha particle deposition in a magnetized plasma  

SciTech Connect

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.

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

1991-01-01

69

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

SciTech Connect

Hamiltonian coordinate, guiding center code calculations of the toroidal field ripple loss of alpha particles from a reversed shear plasma in the Tokamak Fusion Test Reactor (TFTR) [Fusion Technol. {bold 21}, 1324 (1992)] predict 40{percent} total alpha losses and 20{percent} ripple diffusion losses. This is about double the loss rate of a comparable non-reversed magnetic shear plasma. High central q is found to increase alpha ripple losses as well as first orbit losses of alphas in the reversed shear simulations. 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. {copyright} {ital 1997 American Institute of Physics.}

Redi, M.H.; White, R.B.; Batha, S.H.; Levinton, F.M.; McCune, D.C. [Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08540 (United States)] [Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08540 (United States)

1997-11-01

70

Measurement of alpha particles on PLT  

SciTech Connect

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.

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

1984-12-01

71

AlphaRad, a new integrated CMOS System-On-Chip for high efficiency alpha particle counting.  

E-print Network

; #12;2 Key words: Solid state detectors; System-on-chip; Alpha particles; Neutrons. The field for a wide range of radiation types and energies, but efficient detection of neutrons (free of gamma contamination) is still demanded, as well as flexible, efficient and cheap systems for gaseous radon monitoring

Paris-Sud XI, Université de

72

Full orbit calculation for lost alpha particle measurement on ITERa)  

NASA Astrophysics Data System (ADS)

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.

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

2008-10-01

73

Alpha particle response characterization of CdZnTe  

SciTech Connect

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

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

2001-06-28

74

Shielding of manned space vehicles against protons and alpha particles  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

75

Alpha particle radiography with the CR39 nuclear track detector  

Microsoft Academic Search

This work studies the alpha particle radiography technique, in conjunction with the CR-39 plastic track detector. The irradiations were made in the CV-28 cyclotron at IEN\\/CNEN\\/RJ, using a 7 MeV\\/nucleon alpha particle beam. All etches were performed by using a 6.25 N NaOH solution, at 70°C. The best etch time to obtain radiographs was determined. A calibration curve (Gray Levels

B. A. de Souza; S. C. Cabral; R. T. Lopes

1995-01-01

76

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

SciTech Connect

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.

Matsuura, H.; Nakao, Y. [Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Motooka, Fukuoka 819-0395 (Japan)

2009-04-15

77

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

SciTech Connect

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

Ohkubo, S. [Department of Applied Science and Environment, Kochi Women's University, Kochi 780-8515 (Japan); Hirabayashi, Y. [Information Initiative Center, Hokkaido University, Sapporo 060-0811 (Japan)

2008-05-12

78

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

DOEpatents

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.

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

1986-04-22

79

Solar flare protons and alpha particles during the last three solar cycles  

Microsoft Academic Search

Event-integrated fluxes of protons and alpha particles in solar-flare-associated particle events during solar cycle 21 (1976--1986) are determined from data obtained by detectors on board the IMP-7 and IMP-8 satellites. Sixty-three solar particle events with proton fluence (E>10 MeV)>10⁷ cm⁻² were identified from October 1972 to March 1987. The average omnidirectional flux of protons with kinetic energy>10 MeV for cycle

J. N. Goswami; R. E. McGuire; R. C. Reedy; D. Lal; R. Jha

1988-01-01

80

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

SciTech Connect

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.

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

1997-03-01

81

Selective flow path alpha particle detector and method of use  

DOEpatents

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.

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

82

Solar wind alpha particle capture at Mars and Venus  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

83

Continuous air monitor for alpha-emitting aerosol particles  

SciTech Connect

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

McFarland, A.R.; Ortiz, C.A. (Texas A and M Univ., College Station, TX (USA). Dept. of Mechanical Engineering); Rodgers, J.C.; Nelson, D.C. (Los Alamos National Lab., NM (USA))

1990-01-01

84

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

E-print Network

Experimental setup for studying the effects of alpha particles on zebrafish embryos E.H.W. Yum to study effects of alpha particles on dechorionated zebrafish embryos. Thin PADC films with a thickness substrates for holding zebrafish embryos for alpha-particle irradiation. These films recorded alpha

Yu, K.N.

85

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

NASA Technical Reports Server (NTRS)

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).

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

1995-01-01

86

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

NASA Astrophysics Data System (ADS)

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.

Kiptily, V. G.; Beaumont, P.; Belli, F.; Cecil, F. E.; Conroy, S.; Craciunescu, T.; Garcia-Munoz, M.; Curuia, M.; Darrow, D.; Ericsson, G.; Fernandes, A. M.; Giacomelli, L.; Gorini, Murari, A.; Nocente, M.; Pereira, R. C.; Von Thun, C. Perez; Popovichev, S.; Riva, M.; Santala, M.; Soare, S.; Sousa, J.; Syme, D. B.; Tardocchi, M.; Zoita, V. L.; Chugunov, I. N.; Gin, D. B.; Khilkevich, E.; Shevelev, A. E.; Goloborod'ko, V.; Sharapov, S. E.; Voitsekhovitch, I.; Yavorskij, V.; JET-EFDA contributors

2014-08-01

87

226Ra determination in phosphogypsum by alpha-particle spectrometry  

NASA Astrophysics Data System (ADS)

A radiochemical method for226Ra determination by alpha-particle spectrometry in environmental samples has been developed in our laboratory. The method has been validated by measurements in samples with known concentrations of this radionuclide and it has been applied in studies related to226Ra behaviour in phosphogypsum (the main by-product of producing phosphoric acid from phosphate rocks).

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

1999-01-01

88

ALPHA-PARTICLE RADIOBIOLOGICAL EXPERIMENTS USING THIN CR-39 DETECTORS  

E-print Network

, Serbia and Monte Negro The present paper studied the feasibility of applying comet assay to evaluate. Comet assay was then applied. Diffusion of DNA out of the cells could be generally observed from the images of stained DNA. The alpha-particle tracks corresponding to the comets developed on the underside

Yu, K.N.

89

PPPL-3239 -Preprint: March 1997, UC-420, 427 Calculations of alpha particle loss for reversed magnetic shear  

E-print Network

ripple loss of alpha particles at birth energy in the reversed shear case simulated, so that all trapped-monotonic q(r) achieved by deliberate modification of plasma startup conditions. Each point in a toroidal

90

PPPL3239 Preprint: March 1997, UC420, 427 Calculations of alpha particle loss for reversed magnetic shear  

E-print Network

ripple loss of alpha particles at birth energy in the reversed shear case simulated, so that all trapped­monotonic q(r) achieved by deliberate modification of plasma startup conditions. Each point in a toroidal

91

TF Ripple Loss of Alpha Particles from the ITER Interim Design: Simulation and Theory  

E-print Network

conditions for the ITER Interim Design [1]: L­mode, H­mode, post­sawtooth, and reversed­shear config particles of birth energy 3.5 MeV, including collisional pitch angle scattering over one alpha slowing down

92

Kinematic measurement of alpha particles accompanied by spontaneous fission of Cf-252  

NASA Astrophysics Data System (ADS)

The energies and relative angles of three particles and the specific energy loss of light particles were recorded for each of more than 100,000 measured events. The comparison of measured distributions with former results gave good agreement, with regard to the integral mean values of energy, angle and mass distribution. The comparison of binary fragments with ternary fragment mass spectra showed that the ternary process is not a binary fission with ensuing alpha emission. The fragments are less stimulated in the ternary process, than in the binary process. Deformation energy is asymmetrically distributed at the fission point.

Heeg, Peter

93

Alpha-particle physics in the tokamak fusion test reactor DT experiment  

NASA Astrophysics Data System (ADS)

A summary is presented of recent alpha-particle experiments on the tokamak fusion test reactor. Alpha particles are generally well confined in MHD-quiescent discharges, and alpha heating of electrons has been observed. The theoretically predicted toroidicity-induced Alfvén eigenmode has been seen in discharges of ? 1 MW of alpha power, but only in plasmas with weak magnetic shear.

Zweben, S. J.; Arunasalam, V.; Batha, S. H.; Budny, R. V.; Bush, C. E.; Cauffman, S.; Chang, C. S.; Chang, Z.; Cheng, C. Z.; Darrow, D. S.; Dendy, R. O.; Duong, H. H.; Fisch, N. J.; Fredrickson, E. D.; Fisher, R. K.; Fonck, R. J.; Fu, G. Y.; Goloborod'ko, V.; Gorelenkov, N.; Hawryluk, R. J.; Heeter, R.; Heidbrink, W. W.; Herrmann, H. W.; Herrmann, M.; Johnson, D. W.; Machuzak, J.; Majeski, R.; McGuire, K. M.; McKee, G.; Medley, S. S.; Mynick, H. E.; Nazikian, R.; Petrov, M. P.; Redi, M. H.; Reznik, S.; Rogers, J.; Schilling, G.; Spong, D. A.; Strachan, J. D.; Stratton, B. C.; Synakowski, E.; Taylor, G.; Wang, S.; White, R. B.; Wong, K. L.; Yavorski, V.; TFTR Group

1997-05-01

94

Alpha-particle physics in the tokamak fusion test reactor DT experiment  

Microsoft Academic Search

A summary is presented of recent alpha-particle experiments on the tokamak fusion test reactor. Alpha particles are generally well confined in MHD-quiescent discharges, and alpha heating of electrons has been observed. The theoretically predicted toroidicity-induced Alfvén eigenmode has been seen in discharges of <= 1 MW of alpha power, but only in plasmas with weak magnetic shear.

S. J. Zweben; V. Arunasalam; S. H. Batha; R. V. Budny; C. E. Bush; S. Cauffman; C. S. Chang; Z. Chang; C. Z. Cheng; D. S. Darrow; R. O. Dendy; H. H. Duong; N. J. Fisch; E. D. Fredrickson; R. K. Fisher; R. J. Fonck; G. Y. Fu; V. Goloborod'ko; N. Gorelenkov; R. J. Hawryluk; R. Heeter; W. W. Heidbrink; H. W. Herrmann; M. Herrmann; D. W. Johnson; J. Machuzak; R. Majeski; K. M. McGuire; G. McKee; S. S. Medley; H. E. Mynick; R. Nazikian; M. P. Petrov; M. H. Redi; S. Reznik; J. Rogers; G. Schilling; D. A. Spong; J. D. Strachan; B. C. Stratton; E. Synakowski; G. Taylor; S. Wang; R. B. White; K. L. Wong; V. Yavorski

1997-01-01

95

Quality factors for alpha particles emitted in tissue  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

96

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

SciTech Connect

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.

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

1998-11-01

97

Alpha-Particle Angular Distributions with Respect to Spin Direction  

Microsoft Academic Search

Angular distribution of alpha particles with respect to the spin direction of residual nuclei from fusion of 176-MeV 20Ne with 150Nd has been measured with the spin spectrometer. Below the Coulomb barrier, the ratio of the 90° to 0° yields with respect to spin direction increases with decreasing Ealpha. This effect is not shown by a statistical-model calculation using penetrabilities

F. A. Dilmanian; D. G. Sarantites; M. Jaeaeskelaeinen; H. Puchta; R. Woodward; J. R. Beene; D. C. Hensley; M. L. Halbert; R. Novotny; L. Adler; R. K. Choudhury; M. N. Namboodiri; R. P. Schmitt; J. B. Natowitz

1982-01-01

98

Possibilities of alpha-particle diagnostics in future tokamaks using helium and lithium beam injection  

SciTech Connect

This paper considers the possibility of using active charge-exchange (CX) diagnostics based on helium and lithium beam injection to investigate the confined alpha-particle distribution function in future fusion experiments. The required helium beam densities are determined by mathematic modeling of the physical processes (double CX, attenuation of the doping beam, and CX flow, taking into account the step process). They are found to be {approximately}1 A for a 40-keV beam for thermalized (ash) alpha-particle diagnostics and 30 to 600 MA for a 0.35 to 0.65 MeV/amu HeH{sup +} ion source for hot alpha-particle diagnostics. A {sup 3}He beam with energy of 500 keV (He{sup +} ion source) and intensity of 0.1 to 3 A is proposed for measurement of the alpha-particle distribution function in the energy range of 0.2 to 2 MeV.

Gorelenkov, N.N.; Krasilnikov, A.V. (I.V. Kurchatov Inst. of Atomic Energy, Moscow (SU))

1991-03-01

99

Alpha particles in coincidence with the superdeformed band in 150Tb  

Microsoft Academic Search

Alpha particle spectra in coincidence both with normal deformed (ND) and superdeformed (SD) bands of 150Tb have been measured using the reaction 120Sn(37Cl,?3n) at 187 MeV bombarding energy. A clear difference is observed between the two spectra, that in coincidence with the SD states being shifted to lower energies. This effect is understood in terms of different angular momentum regions

G. Viesti; M. Lunardon; D. Bazzacco; R. Burch; D. Fabris; S. Lunardi; N. H. Medina; G. Nebbia; C. Rossi Alvarez; G. de Angelis; M. Cinausero; E. Farnea; E. Fioretto; G. Prete; G. Vedovato

1996-01-01

100

Alpha-particle-induced charge collection in p-n junction diodes in semi-insulating GaAs substrates  

Microsoft Academic Search

The bias and angle dependences of the alpha-particle-induced charge collected by GaAs p-n junction diodes are investigated. These diodes, in which the n-layer overlays the p-layer, are fabricated in a semi-insulating GaAs substrate by Si and Mg ion implantation. 241 Am placed in a vacuum is used as an alpha-particle source with an initial energy of 4.03 MeV and a

Yasunari Umemoto; Osamu Kagaya; Yukihiro Kawata

1991-01-01

101

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

102

Protons and alpha particles in the solar wind  

NASA Astrophysics Data System (ADS)

We investigate energetic consequences of ion kinetic instabilitities in the solar wind connected with beam and core protons and alpha particles drifting with respect to each other. We compare theoretical predictions, simulations and observation results. For theoretical prediction we assume drifting bi-Maxwellian ion populations and we calculate theoretical quasilinear heating rates (Hellinger et al., 2013b). The nonlinear evolution of beam-core protons, and alpha particles in the expanding solar wind we investigate using hybrid expanding box system (Hellinger and Travnicek, 2013). The expansion leads to many different kinetic instabilities. In the simulation the beam protons and alpha particles are decelerated with respect to the core protons and all the populations are cooled in the parallel direction and heated in the perpendicular one in agreement with theoretical expectations. On the macroscopic level the kinetic instabilities cause large departures of the system evolution from the double adiabatic prediction and lead to a perpendicular heating and parallel cooling rates. The simulated heating rates are comparable to the heating rates estimated from the Helios observations (Hellinger et al., 2013a); furthermore, the differential velocity between core and beam protons observed by Ulysses exhibits apparent bounds which are compatible with the theoretical constaints imposed by the linear theory for the magnetosonic instability driven by beam-core differential velocity (Matteini et al., 2013). References Hellinger, P., P. M. Travnicek, S. Stverak, L. Matteini, and M. Velli (2013a), Proton thermal energetics in the solar wind: Helios reloaded, J. Geophys. Res., 118, 1351-1365, doi:10.1002/jgra.50107. Hellinger, P., T. Passot, P.-L. Sulem, and P. M. Travnicek (2013b), Quasi-linear heating and acceleration in bi-Maxwellian plasmas, Phys. Plasmas, 20, 122306. Hellinger, P., and P. M. Travnicek (2013), Protons and alpha particles in the expanding solar wind: Hybrid simulations, J. Geophys. Res., 118, 5421-5430, doi:10.1002/jgra.50540. Matteini, L., P. Hellinger, B. E. Goldstein, S. Landi, M. Velli, and M. Neugebauer (2013), Signatures of kinetic instabilities in the solar wind, J. Geophys. Res., 118, 2771-2782, doi:10.1002/jgra.50320.

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

2014-05-01

103

Some electrochemical etching studies on the registration of alpha particle tracks in polycarbonate  

NASA Astrophysics Data System (ADS)

The registration of alpha particle tracks was studied in 250 ?m thick polycarbonate foils using the electrochemical etching (ECE) method. The etchant was a mixture of ethanol, potassium hydroxide, and water at 25°C and the effects of concentration and etching duration were also investigated at different alpha energies by applying a field strength of 32 kV/cm at 2 kHz frequency. The alpha tracks were registered efficiently with an upper energy threshold of about 2.1 MeV having track diameters of up to 230 ?m which are easily observable by the unaided eyes. The etching duration and the etchant concentration showed strong effects on the efficiency, track diameter, and the energy thresholds. A mixture of 15 g KOH + 40 g C 2H 5OH + 45 g H 2O was found to be an optimum mixture which is the same as commonly used in conventional etching called PEW solution. In conclusion, alpha particle tracks can be efficiently registered in polycarbonate and it is applicable to a number of health physics and radiation research applications.

Sohrabi, M.; Khajeian, E.

104

L-shell ionization studies of Pb and Bi with alpha particles  

Microsoft Academic Search

Ionization cross sections for the L subshells of Pb and Bi by alpha-particle bombardment (2.2-8.2 MeV) have been determined from the experimental data and the currently available radiative transition probabilities, fluorescence yields, and Coster-Kronig factors. The measured ionization cross sections and their ratios are compared with the results of ECPSSR calculations [ECPSSR denotes perturbed-stationary-state (PSS) theory with energy-loss (E), Coulomb

B. B. Dhal; T. Nandi; H. C. Padhi

1994-01-01

105

Scattering of 42-MeV alpha particles from Cu-65  

NASA Technical Reports Server (NTRS)

The extended particle-core coupling model was used to predict the properties of low-lying levels of Cu-65. A 42-MeV alpha particle cyclotron beam was used for the experiment. The experiment included magnetic analysis of the incident beam and particle detection by lithium-drifted silicon semiconductors. Angular distributions were measured for 10 to 50 degrees in the center of mass system. Data was reduced by fitting the peaks with a skewed Gaussian function using a least squares computer program with a linear background search. The energy calibration of each system was done by pulsar, and the excitation energies are accurate to + or - 25 keV. The simple weak coupling model cannot account for the experimentally observed quantities of the low-lying levels of Cu-65. The extended particle-core calculation showed that the coupling is not weak and that considerable configuration mixing of the low-lying states results.

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

1972-01-01

106

Exchange of Alpha Particle in the {sup 16}O+{sup 12}C Elastic Scattering  

SciTech Connect

We have analyzed twenty elastic scattering angular distributions of the {sup 16}O+{sup 12}C system, measured at Sao Paulo Pelletron Laboratory and also data from the literature. The energies cover the region around and above Coulomb barrier, ranging from 8.54 up to 75.43 MeV in the center of mass reference frame. In the {sup 16}O+{sup 12}C scattering, two different processes can occur which result in same exit channel, the elastic scattering and the exchange of an alpha particle between projectile and target. We have used the Optical Model formalism for the elastic scattering and the DWBA to describe the alpha transfer reaction contribution. Thus, by analyzing the {sup 16}O+C elastic scattering at backward angles we have obtained the {sup 16}O{sub gs} alpha spectroscopic factor.

Morais, M. C.; Filho, R. Lichtenthaeler [Departamento de Fisica Nuclear, Universidade de Sao Paulo, C.P. 66318, Sao Paulo (Brazil)

2009-06-03

107

Preliminary results from the lunar prospector alpha particle spectrometer  

SciTech Connect

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.

Lawson, S. L. (Stefanie L.)

2001-01-01

108

Design, spectrum measurements and simulations for a 238Pu alpha-particle irradiator for bystander effect and genomic instability experiments.  

PubMed

Design, spectrum measurements and simulations for an alpha-particle irradiator for bystander effect and genomic instability experiments are presented. Measured alpha-particle energy spectra were used to confirm the characteristics of the source of the irradiator specified by the manufacturer of the source. The spectra were measured in vacuum with a high-resolution spectrometer and simulated with an AASI Monte Carlo code. As a next step, we simulated alpha-particle energy spectra at the target plane of the irradiator for three different source-to-target distances. In these simulations, helium was used as the medium between the source and the exit window of the irradiator; its pressure and temperature corresponded to those of the ambient air. Mean energies and full-widths at half-maximum (FWHM) were calculated for the three different helium gas tracks. PMID:16618543

Hakanen, Arvi; Siiskonen, Teemu; Pöllänen, Roy; Kosunen, Antti; Turunen, Asko; Belyakov, Oleg

2006-08-01

109

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

SciTech Connect

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.

Verscharen, Daniel; Bourouaine, Sofiane [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Chandran, Benjamin D. G., E-mail: daniel.verscharen@unh.edu, E-mail: s.bourouaine@unh.edu, E-mail: benjamin.chandran@unh.edu [Also at Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)

2013-08-20

110

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

SciTech Connect

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)

Seregina, E A; Seregin, A A [State Scientific Center of the Russian Federation 'A.I. Leypunsky Institute for Physics and Power Engineering', Obninsk, Kaluga Region (Russian Federation)

2013-02-28

111

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

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

112

A bipolar mechanism for alpha-particle-induced soft errors in GaAs integrated circuits  

Microsoft Academic Search

The alpha-particle-induced collected charge in undoped LEC semi-insulating GaAs is measured in n+-i-n+ and n+-p-n+ isolation structures and is compared with the results of an analytical model based on a bipolar mechnism. In n+-i-n+ isolation structures, a collected-storage multiplication phenomenon induced by alpha-particle incidence is observed. The measured collected charge is about three times the alpha-particle-generated charge. This phenomenon can

Yasunari Umemoto; Nobutoshi Matsunaga; Kazumichi Mitsusada

1989-01-01

113

G. Vlad et al., IT/P3-31 20th IAEA Fusion Energy Conference (FEC 2004). 1-6/11/2004 Vilamoura, Portugal 1 Effects of Alpha Particle Transport  

E-print Network

), should approach the so called ignition condition: heating due to fusion -particles (hot particles) able to sustain the burning plasma · Good confinement of the -particles is crucial in getting such condition, with birth energy Efus=3.52 MeV and critical energy Ecrit33.0 Te(r) (Stix); ­ assume nD=nT=ni/2 and ni

Vlad, Gregorio

114

Solar flare protons and alpha particles during the last three solar cycles  

SciTech Connect

Event-integrated fluxes of protons and alpha particles in solar-flare-associated particle events during solar cycle 21 (1976--1986) are determined from data obtained by detectors on board the IMP-7 and IMP-8 satellites. Sixty-three solar particle events with proton fluence (E>10 MeV)>10/sup 7/ cm/sup -2/ were identified from October 1972 to March 1987. The average omnidirectional flux of protons with kinetic energy>10 MeV for cycle 21, 64 cm/sup -2/ s/sup -1/, is lower than the corresponding number for cycle 20 (92 cm/sup -2/ s/sup -1/) based on satellite data and for the cycle 19 (378 cm/sup -2/ s/sup -1/) based on lunar sample data. Six large events contributed 70% of the total proton fluence during solar cycle 21. Several events in early 1981 with high proton fluences could account for much of the high /sup 56/Co radioactivities observed in the small-sized Salem meteorite. The event-averaged alpha-particle to proton ratio in the energy interval 1--10 MeV/nucleon varies from 0.006 to 0.05, with an average value of 0.02 for the whole cycle. The events during solar cycle 21 are characterized by softer spectra for both protons and alpha particles compared to those in earlier solar cycles. No definitive correlation exists between cycle-averaged solar flare proton fluxes and peak sunspot numbers. A comparison with long-term (million year) averaged data for these parameters, obtained from lunar sample data, shows that the contemporary solar flare proton spectra are characterized by softer spectra (lower R/sub 0/ values). A similar comparison cannot be made for the mean long-term averaged flux, as the contemporary average suffers from uncertainty due to statistics of single events.

Goswami, J.N.; McGuire, R.E.; Reedy, R.C.; Lal, D.; Jha, R.

1988-07-01

115

Full orbit computations of ripple-induced fusion {alpha}-particle losses from burning tokamak plasmas  

SciTech Connect

A full orbit code is used to compute collisionless losses of fusion {alpha} particles from three proposed burning plasma tokamaks: the International Tokamak Experimental Reactor (ITER); a spherical tokamak power plant (STPP) [T. C. Hender, A. Bond, J. Edwards, P. J. Karditsas, K. G. McClements, J. Mustoe, D. V. Sherwood, G. M. Voss, and H. R. Wilson, Fusion Eng. Des. 48, 255 (2000)]; and a spherical tokamak components test facility (CTF) [H. R. Wilson, G. M. Voss, R. J. Akers, L. Appel, A. Dnestrovskij, O. Keating, T. C. Hender, M. J. Hole, G. Huysmans, A. Kirk, P. J. Knight, M. Loughlin, K. G. McClements, M. R. O'Brien, and D. Yu. Sychugov, Proceedings of the 20th IAEA Fusion Energy Conference, Invited Paper FT/3-1Ra]. It has been suggested that {alpha} particle transport could be enhanced due to cyclotron resonance with the toroidal magnetic field ripple. However, calculations for inductive operation in ITER yield a loss rate that appears to be broadly consistent with the predictions of guiding center theory, falling monotonically as the number of toroidal field coils N is increased (and hence the ripple amplitude is decreased). For STPP and CTF the loss rate does not decrease monotonically with N, but collisionless losses are generally low in absolute terms. As in the case of ITER, there is no evidence that finite Larmor radius effects would seriously degrade fusion {alpha}-particle confinement.

McClements, K.G. [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)

2005-07-15

116

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  

E-print Network

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 $Q_{\\mathrm{flow}}$ at which energy is released by alpha-particle deceleration, accounting for azimuthal flow and conservation of total momentum. We find that $Q_{\\mathrm{flow}} > 0 $ at $r r_{\\mathrm{crit}}$. We compare the value of $Q_{\\mathrm{flow}}$ at $rwind streams from the Helios and Ulysses spacecraft. We find that $Q_{\\mathrm{flow}}$ exceeds $Q_{\\alpha}$ at $r < 1\\,\\mathrm{AU}$, $Q_{...

Verscharen, Daniel; Bourouaine, Sofiane; Hollweg, Joseph V

2014-01-01

117

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

NASA Astrophysics Data System (ADS)

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.

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

2007-08-01

118

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

NASA Astrophysics Data System (ADS)

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

Karim, Taskin; McKenna, Gregory

2012-02-01

119

Effects of alpha particles on the angular momentum loss from the Sun  

E-print Network

The classic Weber-Davis model of the solar wind is reconsidered by incorporating alpha particles and by allowing the solar wind to flow out of the equatorial plane in an axisymmetrical configuration. In the ion momentum equations of the solar wind, the ion gyro-frequency is many orders of magnitude higher than any other frequency. This requires that the difference between proton and alpha velocity vectors be aligned with the background magnetic field. With the aid of this alignment condition, the governing equations of the multi-fluid solar wind are derived from the standard transport equations. The governing equations are numerically solved along a prescribed meridional magnetic field line located at colatitude $70^\\circ$ at 1AU and a steady state fast solar wind solution is found. A general analysis concludes, in agreement with the Weber-Davis model, that the magnetic field helps the coronal plasma to achieve an effective corotation out to the Alfv\\'enic radius, where the poloidal Alfv\\'enic Mach number $M_T$ equals unity ($M_T$ is defined by equation (\\ref{eq:mach})). The model computations show that, magnetic stresses predominate the angular momentum loss of the Sun. For the fast wind considered, the proton contribution to the angular momentum loss, which can be larger than the magnetic one, is almost completely canceled by the alpha particles that develop an azimuthal speed in the direction opposite to the solar rotation. The Poynting flux associated with the azimuthal components is negligible in the energy budget. However, the solar rotation can play some role in reducing the relative speed between alpha particles and protons for low latitude fast solar wind streams in interplanetary space.

Bo Li; Xing Li

2006-06-07

120

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

SciTech Connect

The first feasibility study of an {alpha}-particle capture reaction in inverse kinematics at energies relevant to the p process was performed at the Wien Filter of the LISE spectrometer at GANIL. Hereby, the {sup 4}He({sup 78}Kr,{gamma}){sup 82}Sr reaction was investigated using as target an {sup 4}He-implanted thin Al foil. The analysis of the data has shown that the determination of ({alpha},{gamma}) reaction cross sections at rather low energies around 2 MeV/u in inverse kinematics is indeed feasible regarding the high rejection rate of the primary beam, which in the present work was better than a factor of 10{sup 9}. However, the expected position of the recoils of interest was completely masked by particles of currently unknown origin that could hardly be attributed to scattering of the primary beam. The most probable explanation for the origin of these 'pollutants' could be microscopic dust particles of 10 {mu}m diameter and less, that are extremely difficult to avoid in standard experimental conditions. Hence, the use of a gas-jet target instead of a solid one is compulsory.

Ujic, P.; Oliveira Santos, F. de; Stodel, Ch.; Saint-Laurent, M.-G.; Kamalou, O.; Amthor, M. A.; Grevy, S.; Caceres, L. [GANIL, Bd. Henri Becquerel, Caen (France); Lagoyannis, A.; Mertzimekis, T. J.; Harissopulos, S.; Demetriou, P. [Institute of Nuclear Physics, NCSR 'Demokritos', Aghia Paraskevi, Athens (Greece); Perrot, L. [CNRS/IN2P3, IPN Orsay (France); Lefebvre-Schuhl, A. [CSNSM, Orsay (France); Spyrou, A. [NSCL/MSU, East Lansing, Michigan (United States); Koivisto, H.; Laitinen, M.; Uusitalo, J.; Julin, R. [Department of Physics, University of Jyvaeskylae (Finland)

2011-10-28

121

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

SciTech Connect

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.

Ramachandran, K.; Chatterjee, A.; Navin, A.; Mahata, K.; Shrivastava, A.; Tripathi, V.; Kailas, S.; Saxena, A.; Thomas, R.G.; Kumar, Suresh; Sahu, P.K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Nanal, V.; Pillay, R.G. [Department of Nuclear and Atomic Physics, T.I.F.R, Colaba, Mumbai 400 005 (India)

2006-06-15

122

Alpha Particles Induce Apoptosis through the Sphingomyelin Pathway  

PubMed Central

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

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

2011-01-01

123

L-subshell ionization studies of Au for alpha -particle and lithium-ion bombardment  

Microsoft Academic Search

L-subshell ionization of Au has been investigated for alpha -particle and lithium-ion bombardments with energies 0.54-1.74 MeV u-1 and 0.65-1.44 MeV u-1, respectively. Comparison of experimental X-ray production cross sections with the predictions of the ECPSSR and SCA theories shows reasonably good agreement for Lalpha and Lbeta X-rays, whereas for Lgamma and Lgamma 1+5 the ECPSSR theory underestimates the cross

B. B. Dhal; T. Nandi; H. C. Padhi; D. Trautmann

1995-01-01

124

An alpha particle detector for a portable neutron generator for the Nuclear Materials Identification System (NMIS)  

NASA Astrophysics Data System (ADS)

A recoil alpha particle detector has been developed 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 coincident emission of 14.1 MeV neutrons and 3.5 MeV alpha particles produced by the D-T reaction, alpha detection determines the time and direction of 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 ns), inorganic scintillator with a high melting point (1975 °C). One detector has been installed in an APSTNG and is currently being tested. Initial results include a measured efficiency for 3.5 MeV alphas of 90%.

Hausladen, P. A.; Neal, J. S.; Mihalczo, J. T.

2005-12-01

125

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

NASA Technical Reports Server (NTRS)

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.

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

126

Energy dependence of event shapes and of $\\\\alpha_s$ at LEP 2  

Microsoft Academic Search

Infrared and collinear safe event shape distributions and their mean values are determined using the data taken at ve di erent centre of mass energies above $M_Z$ with the DELPHI detector at LEP. From the event shapes, the strong coupling $\\\\alpha_s$ is extracted in $O(\\\\alpha^2_s)$, NLLA and a combined scheme using hadronisation corrections evaluated with fragmentation model generators as well

P. Abreu; W Adam; T Adye; P Adzic; Z Albrecht; T Alderweireld; G D Alekseev; R Alemany; T Allmendinger; P P Allport; S Almehed; Ugo Amaldi; N Amapane; S Amato; E G Anassontzis; P Andersson; A Andreazza; S Andringa; P Antilogus; W D Apel; Y Arnoud; B Åsman; J E Augustin; A Augustinus; Paul Baillon; P Bambade; F Barão; Guido Barbiellini; R Barbier; Dimitri Yuri Bardin; G Barker; A Baroncelli; Marco Battaglia; M Baubillier; K H Becks; M Begalli; A Behrmann; P Beillière; Yu A Belokopytov; K S Belous; N C Benekos; Alberto C Benvenuti; C Bérat; M Berggren; D Bertini; D Bertrand; M Besançon; F Bianchi; M Bigi; S M Bilenky; M A Bizouard; D Bloch; H M Blom; M Bonesini; W Bonivento; M Boonekamp; P S L Booth; A W Borgland; G Borisov; C Bosio; O Botner; E Boudinov; B Bouquet; C Bourdarios; T J V Bowcock; I Boyko; I Bozovic; M Bozzo; P Branchini; T Brenke; R A Brenner; P Brückman; J M Brunet; L Bugge; T Buran; T Burgsmüller; Brigitte Buschbeck; P Buschmann; S Cabrera; M Caccia; M Calvi; T Camporesi; V Canale; F Carena; L Carroll; Carlo Caso; M V Castillo-Gimenez; A Cattai; F R Cavallo; V Chabaud; M M Chapkin; P Charpentier; L Chaussard; P Checchia; G A Chelkov; R Chierici; P V Chliapnikov; P Chochula; V Chorowicz; J Chudoba; K Cieslik; P Collins; R Contri; E Cortina; G Cosme; F Cossutti; J H Cowell; H B Crawley; D J Crennell; S Crépé; G Crosetti; J Cuevas-Maestro; S Czellar; Martyn Davenport; W Da Silva; A Deghorain; G Della Ricca; P A Delpierre; N Demaria; A De Angelis; Wim de Boer; C De Clercq; B De Lotto; A De Min; L S De Paula; H Dijkstra; Lucia Di Ciaccio; J Dolbeau; K Doroba; M Dracos; J Drees; M Dris; A Duperrin; J D Durand; G Eigen; T J C Ekelöf; Gösta Ekspong; M Ellert; M Elsing; J P Engel; B Erzen; M C Espirito-Santo; E Falk; G K Fanourakis; D Fassouliotis; J Fayot; Michael Feindt; A Fenyuk; P Ferrari; A Ferrer; E Ferrer-Ribas; F Ferro; S Fichet; A Firestone; U Flagmeyer; H Föth; E Fokitis; F Fontanelli; B J Franek; A G Frodesen; R Frühwirth; F Fulda-Quenzer; J A Fuster; A Galloni; D Gamba; S Gamblin; M Gandelman; C García; C Gaspar; M Gaspar; U Gasparini; P Gavillet; E N Gazis; D Gelé; N Ghodbane; I Gil; F Glege; R Gokieli; B Golob; G Gómez-Ceballos; P Gonçalves; I González-Caballero; Gian P Gopal; L Gorn; M Górski; Yu Guz; Valerio Gracco; J Grahl; E Graziani; C Green; H J Grimm; P Gris; G Grosdidier; K Grzelak; M Günther; J Guy; F Hahn; S Hahn; S Haider; A Hallgren; K Hamacher; J Hansen; F J Harris; V Hedberg; S Heising; J J Hernández; P Herquet; H Herr; T L Hessing; J M Heuser; E Higón; S O Holmgren; P J Holt; S Hoorelbeke; M A Houlden; Josef Hrubec; K Huet; G J Hughes; K Hultqvist; J N Jackson; R Jacobsson; P Jalocha; R Janik; C Jarlskog; G Jarlskog; P Jarry; B Jean-Marie; E K Johansson; P E Jönsson; C Joram; P Juillot; F Kapusta; K Karafasoulis; S Katsanevas; E C Katsoufis; R Keränen; Borut P Kersevan; B A Khomenko; N N Khovanskii; A P Kiiskinen; B J King; A Kinvig; N J Kjaer; O Klapp; H Klein; P M Kluit; P Kokkinias; M Koratzinos; V Kostyukhin; C Kourkoumelis; O Kuznetsov; Manfred Krammer; E Kriznic; J Krstic; Z Krumshtein; P Kubinec; J Kurowska; K L Kurvinen; J Lamsa; P Langefeld; V Lapin; J P Laugier; R Lauhakangas; Gerhard Leder; F Ledroit; V Lefébure; L Leinonen; A Leisos; R Leitner; J Lemonne; Georg Lenzen; V Lepeltier; T Lesiak; M Lethuillier; J Libby; D Liko; A Lipniacka; I Lippi; B Lörstad; J G Loken; J H Lopes; J M López; R López-Fernandez; D Loukas; P Lutz; L Lyons; J N MacNaughton; J R Mahon; A Maio; A Malek; T G M Malmgren; S Maltezos; V Malychev; F Mandl; J Marco; R P Marco; B Maréchal; M Margoni; J C Marin; C Mariotti; A Markou; C Martínez-Rivero; F Martínez-Vidal; S Martí i García; N Mastroyiannopoulos; F Matorras; C Matteuzzi; Giorgio Matthiae; J Masik; F Mazzucato; M Mazzucato; M L McCubbin; R McKay; R McNulty; G McPherson; C Meroni; W T Meyer; E Migliore; L Mirabito; Winfried A Mitaroff; U Mjörnmark; T Moa; M Moch; R Møller; K Mönig; M R Monge; X Moreau; P Morettini; G A Morton; U Müller; K Münich; M Mulders; C Mulet-Marquis; R Muresan; W J Murray; B Muryn; Gerald Myatt; T Myklebust; F Naraghi; M Nassiakou; Francesco Luigi Navarria; S Navas; K Nawrocki; P Negri; S Némécek; N Neufeld; N Neumeister; R Nicolaidou; B S Nielsen; M Nikolenko; V P Nomokonov; Ainsley Normand; A Nygren; V F Obraztsov; A G Olshevskii; A Onofre; Risto Orava; G Orazi; K Österberg; A Ouraou; M Paganoni; S Paiano; R Pain; R Paiva; J Palacios; H Palka; T D Papadopoulou; K Papageorgiou; L Pape; C Parkes; F Parodi; U Parzefall; A Passeri; O Passon; M Pegoraro; L Peralta; Manfred Pernicka; A Perrotta; C Petridou; A Petrolini; H T Phillips; F Pierre; M Pimenta; E Piotto; T Podobnik; M E Pol; G Polok; P Poropat; V Pozdnyakov; P Privitera; N Pukhaeva; Antonio Pullia; D Radojicic; S Ragazzi; H Rahmani; P N Ratoff; A L Read; P Rebecchi; N G Redaelli; Meinhard Regler; D Reid

1999-01-01

127

On the approximations of the distribution function of fusion alpha particles  

SciTech Connect

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.

Bilato, R., E-mail: roberto.bilato@ipp.mpg.de; Brambilla, M.; Poli, E. [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)

2014-10-15

128

The interaction of energetic alpha-particles with intense lower hybrid waves  

SciTech Connect

Lower hybrid waves are a demonstrated, continuous means of driving toroidal current in a tokamak. When these waves propagate in a tokamak fusion reactor, in which there are energetic {alpha}- particles, there are conditions under which the {alpha}-particles do not appreciably damp, and may even amplify, the wave, thereby enhancing the current-drive effect. Waves traveling in one poloidal direction, in addition to being directed in one toroidal direction, are shown to be the most efficient drivers of current in the presence of the energetic {alpha}-particles.

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

1992-06-01

129

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

SciTech Connect

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.

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

1980-09-01

130

PPPL3119 Preprint: July 1995, UC426 Alfvnic Behavior of Alpha Particle Driven Ion Cyclotron  

E-print Network

PPPL­3119 ­ Preprint: July 1995, UC­426 Alfvénic Behavior of Alpha Particle Driven Ion Cyclotron, Oxfordshire, OX14 3DB UK (Euratom/UKAEA Fusion Association) ABSTRACT Ion cyclotron emission (ICE) has been the top and bottom of the vacuum vessel. Harmonics of the alpha cyclotron frequency (W a ) evaluated

131

PPPL-3119 -Preprint: July 1995, UC-426 Alfvnic Behavior of Alpha Particle Driven Ion Cyclotron  

E-print Network

PPPL-3119 - Preprint: July 1995, UC-426 Alfvénic Behavior of Alpha Particle Driven Ion Cyclotron, Oxfordshire, OX14 3DB UK (Euratom/UKAEA Fusion Association) ABSTRACT Ion cyclotron emission (ICE) has been the top and bottom of the vacuum vessel. Harmonics of the alpha cyclotron frequency ( ) evaluated

132

Direct and indirect effects of alpha-particle irradiations of human prostate tumor cells  

E-print Network

The objective of this project is to establish a model system to study the direct effect, the bystander effect and the combinational effect of alpha-particle irradiations of human prostate tumor cells, toward the goal of ...

Wang, Rong, Ph. D. Massachusetts Institute of Technology

2005-01-01

133

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

SciTech Connect

The detection efficiencies of solid-state nuclear track detectors, made with cellulose nitrate materials (LR-115 II) or alkyl diglycol carbonate (CR-39) were investigated. Detection efficiency for a surface ..cap alpha.. source was experimentally obtained by changing the dimensions between the detector and the source, while ..cap 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 ..cap 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%.

Uda, T.; Iba, H.

1985-09-01

134

Microstructure damage of thin aluminum films by irradiation with alpha particles and fission fragments  

SciTech Connect

The atomic force microscopy (AFM) has been used to study the microstructure damage of thin aluminum film surfaces induced by bombardment of alpha particles and fission fragments from {sup 252}Cf source. Different types of defects (dislocations lines, loops, voids, and blisters) and their complex morphologies appeared under both the beam of alpha particles and a mix of alpha particles and fission fragments. The first surface damage became clearly visible only after 250 hr irradiation of a mix of alpha particles and fission fragments (8.65 x 10{sup 8} ff/cm{sup 2} and 1.36 x 10{sup 10} {alpha}/cm{sup 2}). The number of voids and dislocation lines created on the aluminum surface were (3.8 {+-} 0.8) x 10{sup 7} cm{sup -2} and (2.1 {+-} 0.8) x 10{sup 6} cm{sup -2}, respectively. Single blisters were observed with the mean diameter of (933 {+-} 22) nm and the mean height of (102 {+-} 15) nm. The first ellipsoidal dislocation loops appeared at the fluence of (1.03 x 10{sup 9} ff/cm{sup 2} and 1.62 x 10{sup 10} {alpha}/cm{sup 2}). However, these ellipsoidal loops were not seen with low energetic alpha particles at the same fluence. Our results suggest that the fission fragments might maximize large voids and dislocations and increase the degradation in depth resolution. (authors)

Sadi, S. [Department of Nuclear Engineering and Radiation Health Physics, 100 Radiation Center, Oregon State University, Corvallis, OR 97331-5903 (United States); Paulenova, A. [Radiation Center, 100 Radiation Center, Oregon State University, Corvallis, OR 97331-5903 (United States); Loveland, W.D.; Watson, P.R. [Department of Chemistry, 100 Radiation Center, Oregon State University, Corvallis, OR 97331-5903 (United States)

2007-07-01

135

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

SciTech Connect

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

Bourouaine, Sofiane; Verscharen, Daniel; Chandran, Benjamin D. G. [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States)] [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Maruca, Bennett A. [Space Science Laboratory, University of California, Berkeley, CA 94720 (United States)] [Space Science Laboratory, University of California, Berkeley, CA 94720 (United States); Kasper, Justin C., E-mail: s.bourouaine@unh.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2013-11-01

136

Dark energy and particle mixing  

E-print Network

We show that the vacuum condensate due to particle mixing is responsible of a dynamically evolving dark energy. In particular, we show that values of the adiabatic index close to -1 for vacuum condensates of neutrinos and quarks imply, at the present epoch, contributions to the vacuum energy compatible with the estimated upper bound on the dark energy.

A. Capolupo; S. Capozziello; G. Vitiello

2008-08-30

137

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

138

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

NASA Astrophysics Data System (ADS)

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

Hellinger, Petr; Trávní?ek, Pavel M.

2013-09-01

139

Study of L-subshell ionization cross sections of Ho, Er, and Tm by {alpha} particles  

SciTech Connect

The L-subshell ionization cross sections induced by 1 to 6 MeV {alpha} particles were measured for three elements of the rare earth group: holmium, erbium, and thulium. Simultaneous PIXE and RBS measurements were utilized. The measured cross sections were compared with the theoretical calculations of the ECPSSR theory. The comparison shows good agreement at high bombardment energies especially for L{sub 2} subshell. When the effect of intra-shell transitions (IS) induced by the Coulomb field of the projectile was included in the ECPSSR formalism, the systematic discrepancies between the theoretical and the experimental values at low energies were reduced. The L{sub 2} and L{sub 3} subshells discrepancies have been resolved only after the united atom effect (UA) has been incorporated into the theory. However; as the discrepancies of the L{sub 1} subshell remain to be addressed only possible reasons are discussed.

Dhehadeh, B.A.; Hallak, A.W.; Garwan, M.A. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia)

1994-12-31

140

Test of statistical model cross section calculations for $\\alpha$-induced reactions on $^{107}$Ag at energies of astrophysical interest  

E-print Network

Astrophysical reaction rates, which are mostly derived from theoretical cross sections, are necessary input to nuclear reaction network simulations for studying the origin of $p$ nuclei. Past experiments have found a considerable difference between theoretical and experimental cross sections in some cases, especially for ($\\alpha$,$\\gamma$) reactions at low energy. Therefore, it is important to experimentally test theoretical cross section predictions at low, astrophysically relevant energies. The aim is to measure reaction cross sections of $^{107}$Ag($\\alpha$,$\\gamma$)$^{111}$In and $^{107}$Ag($\\alpha$,n)$^{110}$In at low energies in order to extend the experimental database for astrophysical reactions involving $\\alpha$ particles towards lower mass numbers. Reaction rate predictions are very sensitive to the optical model parameters and this introduces a large uncertainty into theoretical rates involving $\\alpha$ particles at low energy. We have also used Hauser-Feshbach statistical model calculations to s...

Yalcin, C; Rauscher, T; Kiss, G G; Özkan, N; Güray, R T; Halász, Z; Szücs, T; Fülöp, Zs; Korkulu, Z; Somorjai, E

2015-01-01

141

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

NASA Astrophysics Data System (ADS)

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

Ruddy, Frank H.; Seidel, John G.

2007-10-01

142

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

SciTech Connect

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

Ohkubo, S. [Department of Applied Science and Environment, Kochi Women's University, Kochi 780-8515 (Japan); Hirabayashi, Y. [Information Initiative Center, Hokkaido University, Sapporo 060-0810 (Japan)

2004-10-01

143

Scattering of 42 MeV alpha particles from copper-65  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

144

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

SciTech Connect

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

Fernandez, Rodrigo [Department of Astronomy and Astrophysics, University of Toronto, Toronto, Ontario M5S 3H4 (Canada); Thompson, Christopher [CITA, 60 St. George Street, Toronto, Ontario M5S 3H8 (Canada)

2009-10-01

145

Alpha CAM filter particle collection pattern study results  

Microsoft Academic Search

During a January 1991 Westinghouse Internal Audit of the WIPP Radiological Air Monitoring Program, an auditor observed that on an Eberline Alpha-6A CAM filter, some particulate was deposited outside the 25 mm diameter area that the filter is planned to use. Since the CAM uses a 25 mm diameter detector, this observation raised concern that the operational efficiency may be

S. G. Clayton; K. B. Steinbruegge; T. D. Merkling

1992-01-01

146

Production of the Alpha-Particle Emitting Radionuclide Astatine-211 at the Texas A&M Cyclotron Institute  

E-print Network

) Normalized neutron energy spectrum for Bi-209(?,xn) reaction from TALYS ........... 42 Figure 19 Target geometry utilized for MCNPX shielding simulations ................... 44 Figure 20 Gamma-ray spectrum based on first experiment measurement at 35... yields for the second experiment using an alpha-particle beam (25.3 MeV, 96.13 nA) measured at a distance of 20 cm from the detector ....................................................... 50 Table 20 MCNPX contact dose rate projections...

Bhakta, Viharkumar Satish

2011-10-21

147

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

SciTech Connect

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

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

1999-06-03

148

Intense alpha-particle emitting crystallites in uranium mill wastes  

USGS Publications Warehouse

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.

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

1994-01-01

149

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

PubMed

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

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

2011-07-01

150

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

151

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

PubMed

An experimental method for determining the range of alpha particles in films based on I-V(s) analysis has been suggested. The range of 5.5 MeV alpha particles in PbI(2) films determined by this technique is 30+/-5 microm, and this value is in agreement with the value calculated by SRIM (the stopping and range of ions in matter), r=24 microm in PbI(2). More than 100 I-V(s) of PbI(2) films with different thicknesses and quality have been analyzed, and the influence of alpha particle radiation on PbI(2) I-V(s) curves has been studied. Developed analytical methods (dependence of current density on electric field and conception of surface defects) were used, and the method limitations are discussed. It was shown that I-V(s) demonstrate the tendency to obey Ohm's law under alpha radiation. On the other hand, dark conductivity of the lead iodide films shows a typical impure character that can lead to an overestimation of the alpha particles' range in PbI(2) films. After films were exposed to alpha radiation, the dark resistivity and I-V shape of some films improved. Also, a weak decrease of the charge carrier concentration, due to a decrease of the "surface defect" concentration ("surface refining"), was registered after successive measurements of I-V(s). PMID:17552841

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

2007-05-01

152

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

SciTech Connect

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

Dmitriev, Yuri; Bennett, Paul R.; Cirignano, Leonard J.; Klugerman, Mikhail; Shah, Kanai S. [Radiation Monitoring Devices, Inc., Watertown, Massachusetts 02472 (United States)

2007-05-15

153

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

SciTech Connect

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

Sarantites, D.G.; Nicolis, N.G.; Abenante, V.; Majka, Z.; Semkow, T.M. (Washington Univ., St. Louis, MO (USA)); 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. (Oak Ridge National Lab., TN (USA)); Griffin, H.C. (Michigan Univ., Ann Arbor, MI (USA))

1990-01-01

154

Solar flare protons and alpha particles during the last three solar cycles  

NASA Technical Reports Server (NTRS)

This paper presents solar-flare-associated proton and alpha-particle fluxes determined for major events from October 1972 through March 1987 (the period that represents the last part of solar cycle 20 and the whole of solar cycle 21), using data obtained by detectors on board the IMP-7 and IMP-8 satellites, along with earlier obtained data for cycle 20. It was found that the average omnidirectional flux of protons with kinetic energy above 10 MeV for cycle 21 (64/sq cm per sec) is lower than the corresponding number for cycle 20 (92/sq cm per sec) and for the cycle 19 (378/sq cm per sec). No definitive correlation was found to exist between cycle-averaged solar flare proton fluxes and peak sunspot numbers.

Goswami, J. N.; Mcguire, R. E.; Reedy, R. C.; Lal, D.; Jha, R.

1988-01-01

155

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

SciTech Connect

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.

Sasao, M.; Tanaka, N.; Terai, K.; Kaneko, O. [Graduate school of Engineering, Tohoku University, Sendai 980-8579 (Japan); Kisaki, M.; Kobuchi, T.; Tsumori, K.; Okamoto, A.; Kitajima, S. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Shinto, K. [IFMIF R and D Center, Japan Atomic Energy Agency, Rokkasho, Aomori 039-3212 (Japan); Wada, M. [Graduate School of Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan)

2012-02-15

156

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

SciTech Connect

We report progress made during the period 15 September 1991--14 September 1992 on the project Experimental Investigations of Electron Capture from Atomic Hydrogen and Deuterium by Alpha Particles''. In the past year we have developed reliable, narrow energy spread, high-current sources of He[sup ++] based on direct-current magentron and electron-cyclotron resonance discharges. These sources have been proven on our test bench accelerator which has been upgraded to also allow us to test atomic hydrogen effusive targets. We have thus made substantial progress toward our goal of studying single electron capture from atomic hydrogen by doubly-ionized helium. A research plan for the upcoming year is also presented.

Gay, T.J.; Park, J.T.

1992-01-01

157

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

SciTech Connect

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}?8×10{sup 19}m{sup ?3} for ITER-like scenario. The thermal corrections to the cold plasma dispersion relation will change the damping rate to a certain extent under some specific conditions. We have also evaluated the fraction of LH power absorbed by the alpha particles, ? ? 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.

Wang, Jianbing, E-mail: zhangxm@ecust.edu.cn; Zhang, Xianmei, E-mail: zhangxm@ecust.edu.cn; Yu, Limin, E-mail: zhangxm@ecust.edu.cn; Zhao, Xiang, E-mail: zhangxm@ecust.edu.cn [Department of Physics, East China University of Science and Technology, P.O. Box 385, Shanghai 200237 (China)

2014-02-12

158

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

159

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

160

A multi-port low-fluence alpha-particle irradiator: fabrication, testing and benchmark radiobiological studies.  

PubMed

A new multi-port irradiator, designed to facilitate the study of the effects of low fluences of alpha particles on monolayer cultures, has been developed. The irradiator consists of four individual planar (241)Am alpha-particle sources that are housed inside a helium-filled Lucite chamber. Three of the radioactive sources consist of 20 MBq of (241)Am 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-microm-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 alpha 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/microm. Clonogenic cell survival experiments with AG1522 human fibroblasts indicate that the RBE of the alpha particles compared to (137)Cs gamma rays is about 7.6 for this biological end point. PMID:15161346

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

2004-06-01

161

Preferential energization of alpha particles in polar coronal holes at one solar radius above the photosphere  

E-print Network

Heating of polar coronal holes during solar minimum and acceleration of the fast solar wind issuing therefrom lack comprehensive theoretical understanding. Wave particle interactions are considered to have crucial effects on the extreme properties of heavy ions in the collision-less region of the polar coronal holes. In this article, we have presented a novel sensitivity analysis to investigate plasma heating by radio waves at lower hybrid frequencies. We have employed a three fluid Maxwell model comprising electrons, protons, and alpha particles at around two solar radius heliocentric distance in the polar coronal holes and derived a dispersion relation as a thirteenth order polynomial for the frequency. Our model provides indications of preferential heating of alpha particles in comparison with protons by means of lower hybrid instabilities. We have employed the electron velocity and spatial charge distribution as our basic study tools so as to show the effects of alpha proton differential mass and differen...

Chakravarty, Aniruddha

2015-01-01

162

Characterization of mono-energetic charged-particle radiography for high energy density physics experiments  

E-print Network

Charged-particle radiography, specifically protons and alphas, has recently been used to image various High-Energy-Density Physics objects of interest, including Inertial Confinement Fusion capsules during their implosions, ...

Manuel, Mario John-Errol

2008-01-01

163

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

PubMed Central

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

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

2014-01-01

164

Limits on Alpha Particle Temperature Anisotropy and Differential Flow from Kinetic Instabilities: Solar Wind Observations  

E-print Network

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-anisotropy-driven instabilities such as the Alfv\\'en/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 {\\em 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 $T_{\\perp\\alpha}/T_{\\perp p}$ ($T_{\\parallel\\alpha}/T_{\\parallel p}$) when alpha-proton differential flow vel...

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

2013-01-01

165

{sup 144}Sm-{alpha} optical potential at astrophysically relevant energies derived from {sup 144}Sm({alpha},{alpha}){sup 144}Sm elastic scattering  

SciTech Connect

For the determination of the {sup 144}Sm-{alpha} optical potential we measured the angular distribution of {sup 144}Sm({alpha},{alpha}){sup 144}Sm scattering at the energy E{sub lab}=20 MeV with high accuracy. Using the known systematics of {alpha}-nucleus optical potentials we are able to derive the {sup 144}Sm-{alpha} optical potential at the astrophysically relevant energy E{sub c.m.}=9.5 MeV with very limited uncertainties. {copyright} {ital 1997} {ital The American Physical Society}

Mohr, P.; Rauscher, T.; Oberhummer, H. [Institut fuer Kernphysik, Technische Universitaet Wien, Wiedner Hauptstrae 8-10, A-1040 Wien (Austria)] [Institut fuer Kernphysik, Technische Universitaet Wien, Wiedner Hauptstrae 8-10, A-1040 Wien (Austria); Mate, Z.; Fueloep, Z.; Somorjai, E. [Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, H-4001 Debrecen (Hungary)] [Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, H-4001 Debrecen (Hungary); Jaeger, M.; Staudt, G. [Physikalisches Institut, Universitaet Tuebingen, D-72076 Tuebingen (Germany)] [Physikalisches Institut, Universitaet Tuebingen, D-72076 Tuebingen (Germany)

1997-03-01

166

Alpha particle induced charge collection measurements and the effectiveness of reflecting barriers on VLSI memories  

Microsoft Academic Search

This paper presents experimental results of analog charge collection measurement of alpha particle induced carriers in memory arrays. Measurements with high intensity foils and variable angle collimated sources on various memory arrays with different reflecting structures are reported. A P-well reflecting barrier is shown to reduce charge collection by a factor 2 and SER by about two orders of magnitude.

Sai-Wai Fu; Amr M. Mohsen; Tim C. May

1982-01-01

167

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

NASA Technical Reports Server (NTRS)

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.

Tripathi, Ram K.; Townsend, Lawrence W.

1993-01-01

168

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

Microsoft Academic Search

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

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

2004-01-01

169

Alpha Particle X-Ray Spectrometer (APXS): Results from Gusev crater and calibration report  

Microsoft Academic Search

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

R. Gellert; R. Rieder; J. Brückner; B. C. Clark; G. Dreibus; G. Klingelhöfer; G. Lugmair; D. W. Ming; H. Wänke; A. Yen; J. Zipfel; S. W. Squyres

2006-01-01

170

The internal conversion spectrum following 244Cm alpha-particle decay  

NASA Astrophysics Data System (ADS)

The internal conversion spectrum following the alpha-particle decay of 244Cm was studied using the National Physical Laboratory (NPL) ??2 beta-spectrometer. Conversion lines from the two most intense transitions were identified as consistent with the multipolarity assignment of E2. Upper intensity limits were set for a third transition which were also in accord with a multipolarity of E2.

Pearcey, J.; Woods, S. A.; Christmas, P.

1990-01-01

171

CURRENT DRIVE BY LOWER HYBRID WAVES IN THE PRESENCE OF ENERGETIC ALPHA PARTICLES  

E-print Network

CURRENT DRIVE BY LOWER HYBRID WAVES IN THE PRESENCE OF ENERGETIC ALPHA PARTICLES N.J. FISCH, J of America ABSTRACT. Many experiments have proved the effectiveness of lower hybrid waves for driving. 1. INTRODUCTION Lower hybrid waves have been found to be effective in driving toroidal current

172

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

ERIC Educational Resources Information Center

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…

Digilov, M.

1991-01-01

173

Hormetic Effect Induced by Alpha-Particle-Induced Stress Communicated In Vivo between Zebrafish Embryos  

E-print Network

Hormetic Effect Induced by Alpha-Particle-Induced Stress Communicated In Vivo between Zebrafish data showing that embryos of the zebrafish, Danio rerio, at 1.5 h post fertilization (hpf) subjected be communicated to unirradiated bystander zebrafish embryos sharing the same water medium to induce a hormetic

Yu, K.N.

174

Electron transport uniformity characterization of CdZnTe using alpha particles  

SciTech Connect

Novel electrode configurations, such as coplanar grids, have been successful in mitigating the effects of poor hole transport in CdZnTe gamma-ray detectors. However, poor material uniformity remains a major problem preventing the widespread application of such detectors in gamma-ray spectroscopy. Uniform electron transport is critical for achieving good gamma-ray detection performance in the coplanar-grid configuration. The authors have investigated the use of alpha-particle response as a quick and simple electron transport uniformity screening technique for material selection, and as a method to study other spectral broadening mechanisms in coplanar-grid detectors. The method consists of uniformly illuminating, with an alpha-particle source, the cathode side of the CdZnTe crystal in either a planar or a coplanar-grid detector configuration. In the planar geometry, the variation in the measured pulse heights is dictated in large part by the uniformity of the electron transport. An alpha-particle spectrum that has a single sharp peak with little background indicates uniform electron transport and, consequently, that the CdZnTe crystal should result in a coplanar-grid detector with good gamma-ray detection performance. In the coplanar geometry, the measured pulse-height variation provides information on additional sources of spectral broadening. In this paper the authors present the results of their study to measure the correlation between these simple alpha-particle measurements and the coplanar-grid gamma-ray detector response.

Amman, M.; Lee, J.S.; Luke, P.N.

1998-04-01

175

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

176

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

SciTech Connect

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.

Burns, F.J.

1990-01-01

177

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

178

Many-particle decays of {alpha}-chain structures in {sup 24}Mg  

SciTech Connect

We have searched for evidence of exotic cluster configurations in {sup 24}Mg resembling a linear chain of {alpha} particles in various many-particle final states of the {sup 12}C+{sup 12}C system, including {sup 1}C(O{sub 2}{sup +})+{sup 12}C(O{sub 2}{sup +}) and {sup 8}Be+{sup 16}O*(4a). Such configurations are predicted to occur by a number of different theoretical models of the structure of {sup 24}Mg. An array of highly segmented Double-Sided Silicon Strip Detectors permits detailed, high resolution reconstruction of these many-charged-particle final states.

Wuosmaa, A.H.

1993-12-31

179

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

SciTech Connect

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.

Sasao, Mamiko [Organization for Research Initiative and Development, Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan); Wada, Motoi [Graduate School of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan); Isobe, Mitsutaka [National Institute for Fusion Science, Toki Gifu 509-5292 (Japan)

2014-08-21

180

[ital L]-shell ionization studies of Pb and Bi with [alpha] particles  

SciTech Connect

Ionization cross sections for the [ital L] subshells of Pb and Bi by [alpha]-particle bombardment (2.2--8.2 MeV) have been determined from the experimental data and the currently available radiative transition probabilities, fluorescence yields, and Coster-Kronig factors. The measured ionization cross sections and their ratios are compared with the results of ECPSSR calculations [ECPSSR denotes perturbed-stationary-state (PSS) theory with energy-loss (E), Coulomb deflection (C), and relativistic (R) corrections]. The measured individual cross sections for [ital L][sub 1] and [ital L][sub 2] subshells deviated in opposite directions from the theory, whereas their sum shows good agreement. The [ital L][sub 3] and total ionization cross sections obtained from the data also show good agreement with the ECPSSR theory. The ionization cross-section ratios [sigma][sub [ital L]1]/[sigma][sub [ital L]2] and [sigma][sub [ital L]3]/[sigma][sub [ital L]2] show large deviations from the ECPSSR theory. The experimental x-ray production cross-section ratios are found to be in better agreement with the theoretical results obtained from using ECPSSR ionization cross sections and the decay yield data of Xu and Xu [J. Phys. B 25, 695 (1992)] rather than those obtained from using the decay yield data of Krause [J. Phys. Chem. Ref. Data 8, 307 (1979)]. The x-ray production cross sections, however, are in better agreement with the theoretical results obtained from using the decay yield data of Krause. The measured centroid energy of the [ital L][gamma] lines of Pb shows large deviations at high projectile energy, whereas for Bi large deviations are found at the low-energy region.

Dhal, B.B.; Nandi, T.; Padhi, H.C. (Institute of Physics, Bhubaneswar 751005 (India))

1994-01-01

181

PGC-1{alpha}: a key regulator of energy metabolism  

NSDL National Science Digital Library

Peroxisome proliferator-activated receptor-{gamma} coactivator (PGC)-1{alpha} is a member of a family of transcription coactivators that plays a central role in the regulation of cellular energy metabolism. This makes it an inviting target for pharmacological intervention in the treatment of obesity and Type 2 diabetes.

Huiyun Liang (University of Texas Health Science Center Department of Cellular and Structural Biology, Barshop Institute for Longevity and Aging Studies)

2006-12-01

182

Pulsed-laser and alpha particle irradiation effects in Fe-based glassy ferromagnets  

NASA Astrophysics Data System (ADS)

A comparatively study of pulsed-laser and alpha particle irradiation effects in metallic glasses has been performed in order to understand the relationship between magnetic behavior and select variations in the structural characteristics of alloy phases. Samples of Fe78B13Si9 and Fe66Co18B15Si metallic glasses were irradiated with a pulsed excimer laser ((lambda) equals 308 nm, (tau) equals 10 ns) and alpha particle beams (W equals 2.8 MeV) using radiation doses of 1016 and 1017 cm-2. Irradiation-driven changes in the magnetic anisotropy and phase equilibrium of alloy samples were studied by Mossbauer Spectroscopy and scanning electron microscopy. The evolution of phases and microstructure during the radiation- induced amorphous-to-crystalline transformations or revitrification depend on the specific irradiation and sample composition.

Toacsan, M. I.; Barb, D.; Sorescu, M.; Constantinescu, B.; Jeloaica, L.

1998-07-01

183

Influence of Temperature Anisotropy and Alpha-Particle Parameters on Calculated Interplanetary Shock Parameters  

NASA Astrophysics Data System (ADS)

In order to determine interplanetary shock parameters, we use Wind and ACE observations of shock passages in the solar wind. Magnetic field and plasma measurements by individual spacecraft are used with the nonlinear least squares fitting technique of Szabo [1994] with an improved error analysis to calculate the local shock parameters. Further improvement of the technique includes taking into account proton temperature anisotropy and alpha-particle parameters which results in higher accuracy of the calculated shock parameters. The shock parameters calculated at the locations of both spacecraft are then compared to estimate the global shapes of the observed shocks. We present statistics of the influence of proton temperature anisotropy and alpha particle parameters on the calculated shock parameters and discuss deviation of the shock global shape from the widely used planar assumption. The improved technique can be used to analyze STEREO and near-Earth observations of interplanetary shocks.

Koval, A.; Szabo, A.

2007-12-01

184

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

Microsoft Academic Search

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

Hyungsoon Shin; Nak-Myeong Kim

1999-01-01

185

Alpha-particle-induced collected charge model in SOI-DRAM's  

Microsoft Academic Search

We have developed a model for collected charges induced by an alpha-particle for SOI-DRAMs which assumes that the body capacitance equals the gate capacitance and that holes do not recombine with electrons. The validity of our model was supported by three-dimensional (3-D) device simulations that considered various gate lengths, gate oxide thicknesses, and flat-band voltages. The work function difference between

Shigeo Satoh; Yoshiharu Tosaka; Kunihiro Suzuki; Toru Itakura

1999-01-01

186

Collection of charge from alpha-particle tracks in silicon devices  

Microsoft Academic Search

Experimentally and by computer simulation, the collection process of alpha-particle-generated charge in silicon devices has been investigated. The total charge collected and the transient characteristics of collection for various structures were studied. Analytic results indicate that a strong drift field extends far beyond the original depletion layer, and funnels a large number of carriers into the struck node. This field-funneling

C.-M. Hsieh; P. C. Murley; R. R. Obrien

1983-01-01

187

Cyclotron instability of trapped alpha-particles in a Tokamak with elliptic cross-section  

Microsoft Academic Search

Cyclotron excitation of fast magnetosonic waves by trapped alpha-particles produced by fusion in a Tokamak with elliptic cross-section is studied. Earlier, this phenomenon was studied for a Tokamak with circular cross-section. It is shown that ellipticity of the Tokamak cross-section considerably affects the growth rate of oscillations. General expressions for the growth rate of the oscillations are obtained and are

T. D. Kaladze; I. G. Lominadze; A. B. Mikhailovskii; O. A. Pokhotelov

1976-01-01

188

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

NASA Astrophysics Data System (ADS)

In tokamak plasmas, the confinement of energetic ions depends on the magnetic field structure. If the plasma pressure is finite, the equilibrium current (i.e., the Pfirsch-Schlüter current and diamagnetic current) flows in the plasma to maintain the magnetohydrodynamic (MHD) equilibrium. These plasma currents generate poloidal and toroidal magnetic field and alter the field structure. Moreover, if we consider the non-axisymmetry of magnetic field structures such as toroidal field (TF) ripples, the non-axisymmetric component of the equilibrium current can alter TF ripples themselves. When the plasma beta becomes high, the changes in the field structure due to the equilibrium current might affect the confinement of energetic ions significantly. We intend to clarify how these currents alter the field structure and affect the confinement of alpha particles in high-beta plasma. The MHD equilibrium is calculated using VMEC and the orbits of fusion alpha particles are followed by using the fully three-dimensional magnetic field orbit-following Monte Carlo code. In relatively low-beta plasma (e.g., the volume-averaged beta value ????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.

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

2013-08-01

189

Angular Distribution of Alpha Particles Emitted by Oriented Np237 Nuclei  

Microsoft Academic Search

Np237 nuclei were aligned through the electric quadrupole and magnetic hyperfine couplings in NpO2Rbz(NO3)3, cooled to 0.2-4.2°K. A complete experiment, with rotatable monocrystalline sample, solid-state counter, thermometer, and goniometer, was enclosed in a copper container filled with He3 gas and thermally attached to 1\\/2 mole of paramagnetic salt which could be cooled magnetically. The measured temperature dependence of the alpha-particle

S. H. Hanauer; J. W. Dabbs; L. D. Roberts; G. W. Parker

1961-01-01

190

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

PubMed Central

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. PMID:3079913

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

1986-01-01

191

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

SciTech Connect

{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.

Sogo, T.; Roepke, G. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Lazauskas, R. [IPHC, IN2P3-CNRS/Universite Louis Pasteur BP 28, F-67037 Strasbourg Cedex 2 (France); Schuck, P. [Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay F-91406 (France); Universite Paris-Sud, Orsay F-91505 (France); Laboratoire de Physique et Modelisation des Milieux Condenses, CNRS and Universite Joseph Fourier, 25 Avenue des Martyrs, Boite Postale 166, F-38042 Grenoble Cedex 9 (France)

2009-05-15

192

First Evidence of Collective Alpha Particle Effect on Toroidal Alfvén Eigenmodes in the TFTR D-T Experiment  

NASA Astrophysics Data System (ADS)

The alpha particle effect on the excitation of toroidal Alfvén eigenmodes (TAE) was investigated in deuterium-titrium (D-T) plasmas in the Tokamak Fusion Test Reactor. rf power was used to position the plasma near the instability threshold, and the alpha particle effect was inferred from the reduction of rf power threshold for TAE instability in D-T plasmas. Initial calculations indicate that the alpha particles contribute 10%-30% of the total drive in a D-T plasma with 3 MW of peak fusion power.

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

1996-03-01

193

Preferential energization of alpha particles in polar coronal holes at one solar radius above the photosphere  

NASA Astrophysics Data System (ADS)

Heating of polar coronal holes (PCH) during solar minimum and acceleration of the fast solar wind issuing therefrom lack comprehensive theoretical understanding. Wave-particle interactions are considered to have crucial effects on the extreme properties of heavy ions in the collisionless region of the PCH. In this paper, we have presented a novel sensitivity analysis to investigate plasma heating by radio waves at lower hybrid (LH) frequencies. We have employed a three-fluid Maxwell model comprising electrons, protons, and ?-particles at around two solar radii heliocentric distance in the PCH and derived a dispersion relation as a 13th-order polynomial for the frequency. Our model provides indications of preferential heating of ?-particles in comparison with protons by means of LH instabilities. We have employed the electron velocity and spatial charge distribution as our basic study tools so as to show the effects of alpha-proton differential mass and differential perpendicular velocity on the preferential heating of ?-particles.

Chakravarty, Aniruddha; Bose, M.

2015-04-01

194

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

SciTech Connect

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.

Gomberoff, L. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Gomberoff, K. [Department of Physics, Technion, Haifa 32000 (Israel); Deutsch, A. [Rafael, P.O. Box 2250, Haifa 31021 (Israel)

2010-06-15

195

cap alpha. /sup 4/He elastic scattering at high energies  

SciTech Connect

Differential cross sections for ..cap alpha.. /sup 4/He elastic scattering have been calculated at incident ..cap alpha..-particle momenta of 4.32, 5.07, and 7.0 GeV/c within the framework of Glauber multiple scattering theory. The full Glauber amplitude has been calculated using the Monte Carlo method for evaluating multidimensional integrals. We found that, in general, the more realistic double-Gaussian model for the density brings theory closer to experiment as compared to the generally used single-Gaussian model in some momentum transfer regions. Our results with the double-Gaussian model and an acceptable set of NN parameters are in fairly good agreement with the experimental data at 4.32 and 5.07 GeV/c.

Usmani, A.A.; Ahmad, I.; Usmani, Q.N.

1989-03-01

196

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

197

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

SciTech Connect

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

Sakuta, S. B., E-mail: sakuta@dni.polyn.kiae.su [Russian Research Centre Kurchatov Institute (Russian Federation); Burtebaev, N. [National Nuclear Center of the Republic Kazakhstan, Institute of Nuclear Physics (Kazakhstan); Artemov, S. V.; Yarmukhamedov, R. [National Nuclear Center of the Republic Uzbekistan, Institute of Nuclear Physics (Uzbekistan)

2012-07-15

198

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

E-print Network

High precision angular distribution data of ($\\alpha$,$\\alpha$) elastic scattering are presented for the nuclei $^{89}$Y, $^{92}$Mo, $^{106,110,116}$Cd, $^{112,124}$Sn, and $^{144}$Sm at energies around the Coulomb barrier. Such data with small experimental uncertainties over the full angular range (20-170 degrees) are the indispensable prerequisite for the extraction of local optical potentials and for the determination of the total reaction cross section $\\sigma_{\\rm{reac}}$. A systematic fitting procedure was applied to the presented experimental scattering data to obtain comprehensive local potential parameter sets which are composed of a real folding potential and an imaginary potential of Woods-Saxon surface type. The obtained potential parameters were used in turn to construct a new systematic $\\alpha$-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.

P. Mohr; G. G. Kiss; Zs. Fülöp; D. Galaviz; Gy. Gyürky; E. Somorjai

2012-12-12

199

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

SciTech Connect

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.

Sorescu, M. [Duquesne Univ., Pittsburgh, PA (United States). Physics Dept.; Barb, D. [Inst. of Atomic Physics, Bucharest (Romania)

1996-12-31

200

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

PubMed Central

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

2014-01-01

201

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

PubMed Central

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

2012-01-01

202

Exciton dynamics in alpha-particle tracks in organic crystals: Magnetic field study of the scintillation in tetracene crystals  

Microsoft Academic Search

The mechanisms of scintillation of organic crystals bombarded by alpha particles are discussed in terms of the current knowledge of exciton dynamics, which has been derived from a study of the photofluorescence of crystals such as anthracene and tetracene. The scintillation of tetracene excited by 4.4-MeV alpha particles incident in a direction perpendicular to the ab plane has been studied

Nicholas E. Geacintov; Michael Binder; Charles E. Swenberg; Martin Pope

1975-01-01

203

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

PubMed Central

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

Lehnert, B E; Goodwin, E H

1997-01-01

204

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

SciTech Connect

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.

Pittman, S. T. [University of Tennessee, Knoxville (UTK); Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Kozub, R. L. [Tennessee Technological University; Smith, Michael Scott [ORNL

2009-01-01

205

Solar wind alpha particles and heavy ions in the inner heliosphere observed with MESSENGER  

NASA Astrophysics Data System (ADS)

The Fast Imaging Plasma Spectrometer (FIPS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has made the first in situ measurements of solar wind plasma in the inner heliosphere since the Helios 1 and 2 spacecraft in the 1980s. Although the core of the solar wind velocity distribution is obstructed by the spacecraft sunshade, a data analysis technique has been developed that recovers both bulk and thermal speeds to 10% accuracy and provides the first measurements of solar wind heavy ions (mass per charge >2 amu/e) at heliocentric distances within 0.5 AU. Solar wind alpha particles and heavy ions appear to have similar mean flow speeds at values greater than that of the protons by approximately 70% of the Alfvén speed. From an examination of the thermal properties of alpha particles and heavier solar wind ions, we find a ratio of the temperature of alpha particles to that of protons nearly twice that of previously reported Helios observations, though still within the limits of excessive heating of heavy ions observed spectroscopically close to the Sun. Furthermore, examination of typical magnetic power spectra at the orbits of MESSENGER and at 1 AU reveals the lack of a strong signature of local resonant ion heating, implying that a majority of heavy ion heating could occur close to the Sun. These results demonstrate that the solar wind at ˜0.3 AU is a blend of the effects of wave-particle interactions occurring in both the solar corona and the heliosphere.

Gershman, Daniel J.; Zurbuchen, Thomas H.; Fisk, Lennard A.; Gilbert, Jason A.; Raines, Jim M.; Anderson, Brian J.; Smith, Charles W.; Korth, Haje; Solomon, Sean C.

2012-09-01

206

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

PubMed

Exposure of humans to mixed fields of high- and low-linear energy transfer (LET) radiation occurs in many situations-for example, in urban areas with high levels of indoor radon as well as background gamma radiation, during airplane flights or certain forms of radiation therapy. From the perspective of health risk associated with exposure to mixed fields, it is important to understand the interactions between different radiation types. In most cellular investigations on mixed beams, two types of irradiations have been applied sequentially. Simultaneous irradiation is the desirable scenario but requires a dedicated irradiation facility. The authors have constructed a facility where cells can be simultaneously exposed to (241)Am alpha particles and 190-kV X-rays at 37°C. This study presents the technical details and the dosimetry of the setup, as well as validates the performance of the setup for clonogenic survival in AA8 Chinese hamster ovary cells. No significant synergistic effect was observed. The relative biological effectiveness of the alpha particles was 2.56 for 37 % and 1.90 for 10 % clonogenic survival. PMID:22434924

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

2012-09-01

207

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)

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.

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

2015-04-01

208

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)

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.

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

2008-02-01

209

Effects of MA 956 superalloy and alpha-alumina particles on some markers of human osteoblastic cells in primary culture.  

PubMed

One of the problems associated with the modern biomaterials used in prostheses is osteolysis, which, although its exact origin is unknown, has been associated with wear particles. Osteoblasts seem to participate directly in this phenomenon. This paper investigates in vitro cellular response to the wear particles from the metal substrate and ceramic covering (alpha-alumina) of a new titanium yttrium aluminum alloy, MA 956, that has been proposed as a biomaterial because of its exceptional mechanical and electrochemical properties. The effect of different sizes (10 and 80 microm) of MA 956 and alpha-alumina particles on osteoblast function was studied in primary human bone cell cultures. Cells were harvested from trabecular bone fragments obtained during knee arthroplasty. Osteoblastic cell response to the particles was measured by assaying C-terminal type I procollagen (PICP), alkaline phosphatase, and osteocalcin secretion, with and without 1.25(OH)(2)D(3) stimulation, in the cell-conditioned medium. Both sizes of MA 956 and alpha-alumina particles decreased PICP secretion in nonstimulated osteoblastic cells, but this secretion was not affected in the cultures stimulated with 1.25(OH)(2)D(3). Only the 10 microm alpha-alumina particles inhibited alkaline phosphatase activity in 1.25(OH)(2)D(3)-stimulated and nonstimulated cultures. The rise in osteocalcin levels after 1.25(OH)(2)D(3) stimulation was lower in the presence of the 10 microm MA 956 particles than in the presence of alpha-alumina particles. Although both materials seem to have directly affected in vitro osteoblastic cell function, the increase in osteocalcin levels after 1.25(OH)(2)D(3) stimulation was lower after exposure to MA 956 particles than the increase observed after exposure to alpha-alumina particles. Therefore, it does not seem that osteocalcin stimulated bone resorption, suggesting that MA 956 would be less likely to provoke osteolysis. PMID:11077400

Rodrigo, A M; Martínez, M E; Martínez, P; Escudero, M L; Ruíz, J; Saldaña, L; Gómez-García, L; Fernández, L; del Valle, I; Munuera, L

2001-01-01

210

AlfaMC: a fast alpha particle transport Monte Carlo code  

E-print Network

AlfaMC is a Monte Carlo simulation code for the transport of alpha particles. The code is based on the Continuous Slowing Down Approximation and uses the NIST/ASTAR stopping-power database. The code uses a powerful geometrical package allowing the coding of complex geometries. A flexible histogramming package is used which greatly easies the scoring of results. The code is tailored for microdosimetric applications where speed is a key factor. The code is open-source and released under the General Public Licence.

Peralta, Luis

2012-01-01

211

Feasibility of an alpha particle gas densimeter for stack sampling applications  

E-print Network

, for conceivable ranges of flue gas composition, the maximum error in density due to the uncertainty in gas composition is less than 2%. ACKNOWLEDGEMENTS I wish to express my appreciation to Dr. R. A. Fjeld and Dr. A. R. McFarland for their patience... LISTING APPENDIX C TABULATED RESULTS 58 60 72 VI TA 84 Vi LIST OF TABLES TABLE P age I Typical Flue Gas Compositions II Model Flue Gas Compositions 35 Coeff icients for Alpha particle Stopping Power Functions 59 Computed and Experimental...

Johnson, Randall Mark

1983-01-01

212

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

NASA Technical Reports Server (NTRS)

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.

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

2014-01-01

213

Alpha-particle emission probabilities in the decay of 239Pu  

NASA Astrophysics Data System (ADS)

The alpha-particle emission probabilities ( P?) of 239Pu have been measured using material of highest enrichment and radiochemical purity, thin sources produced by vacuum sublimation, and high-resolution ? spectroscopy with ion-implanted Si detectors (PIPS). The results for the major emissions are P?0.07 = 0.7077±0.0014, P?13 = 0.1711 ± 0.0014 and P?51 = 0.1194±0.0007, which for the P?0.07 is about 3.6% lower than the recent evaluated value in the literature.

García-Toraño, E.; Aceña, M. L.; Bortels, G.; Mouchel, D.

1993-10-01

214

Elastic and Inelastic Scattering of 18.4MeV Alpha Particles from Na23  

Microsoft Academic Search

Absolute differential cross sections for the elastic and inelastic (0.439-MeV and 2.080-MeV states) scattering of 18.4-MeV alpha particles from 100-mug\\/cm2 sodium targets have been measured using silicon surface-barrier detectors. The targets were prepared by the vacuum evaporation of sodium metal onto Formvar backings. The elastic and inelastic (2.080-MeV state) cross sections were measured at 2.5° intervals in the laboratory angular

B. T. Lucas; S. W. Cosper; O. E. Johnson

1964-01-01

215

Micro-collimator fabricated by alpha-particle irradiation of polyallyldiglycol carbonate polymer film and subsequent chemical etching  

E-print Network

formed on a test PADC film from a particles having traveled through a 20 mm support substrate attached film and subsequent chemical etching V.W.Y Choi, E.H.W. Yum, K.N. Yu Ã? Department of Physics 25 October 2009 Keywords: Solid-state nuclear track detector SSNTD Alpha particle PADC Collimator a b

Yu, K.N.

216

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

SciTech Connect

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

Hodgkins, P.S.; O`Neill, P.; Stevens, D.; Fairman, M.P. [Medical Research Council, Oxfordshire (United Kingdom)

1996-12-01

217

Alpha voltaic batteries and methods thereof  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

218

Semiphenomenological method of analysis for intermediate-energy alpha-nucleus elastic scattering data  

SciTech Connect

We propose a semiphenomenological method of analysis for intermediate energy ..cap alpha..-nucleus elastic scattering experiments and demonstrate its usefulness by analyzing available elastic ..cap alpha..-nucleus scattering data at 1.37 GeV.

Ahmad, I.; Alvi, M.A.

1983-12-01

219

The {alpha}-particle excited scintillation response of the liquid phase epitaxy grown LuAG:Ce thin films  

SciTech Connect

Liquid phase epitaxy grown Lu{sub 3}Al{sub 5}O{sub 12}:Ce (LuAG:Ce) 20 {mu}m thick films and plate cut from the bulk Czochralski-grown LuAG:Ce crystal were prepared for comparison of photoelectron yield (PhY) and PhY dependence on shaping time (0.5-10 {mu}s). {sup 241}Am ({alpha} particles) was used for excitation. At the 0.5 {mu}s shaping time, the best film shows comparable PhY with the bulk sample. PhY of bulk material increases noticeably more with shaping time than that of the films. Energy resolution of films is better. Influence of Pb{sup 2+} contamination in the films (from the flux) and antisite Lu{sub Al} defect in bulk material is discussed.

Prusa, P.; Cechak, T.; Mares, J. A.; Nikl, M.; Beitlerova, A.; Solovieva, N.; Zorenko, Yu. V.; Gorbenko, V. I.; Tous, J.; Blazek, K. [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 11519 Prague (Czech Republic); Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Laboratory of Optoelectronic Materials, Ivan Franko National University of Lviv, 107 Gen. Tarnavskyj Str., 79017 Lviv (Ukraine); Crytur Ltd., Palackeho 175, 51101 Turnov (Czech Republic)

2008-01-28

220

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

PubMed

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

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

2008-02-01

221

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

222

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

NASA Technical Reports Server (NTRS)

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.

Gorenstein, P.; Bjorkholm, P.

1972-01-01

223

Influence of plasma parameters on the absorption coefficient of alpha particles to lower hybrid waves in tokamaks  

SciTech Connect

In tokamaks, fusion generated ? particles may absorb lower hybrid (LH) wave energy, thus reducing the LH current drive efficiency. The absorption coefficient ?{sub ?} of LH waves due to ? particles changing with some typical parameters is calculated in this paper. Results show that ?{sub ?} increases with the parallel refraction index n{sub ?}, while decreases with the frequency of LH waves ? over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption. The absorption coefficient ?{sub ?} 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 ?{sub ?} 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 ?{sub ?} 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.

Wang, J.; Zhang, X., E-mail: zhangxm@ecust.edu.cn; Yu, L.; Zhao, X. [East China University of Science and Technology, Department of Physics (China)

2014-12-15

224

Influence of plasma parameters on the absorption coefficient of alpha particles to lower hybrid waves in tokamaks  

NASA Astrophysics Data System (ADS)

In tokamaks, fusion generated ? particles may absorb lower hybrid (LH) wave energy, thus reducing the LH current drive efficiency. The absorption coefficient ?? of LH waves due to ? particles changing with some typical parameters is calculated in this paper. Results show that ?? increases with the parallel refraction index n ?, while decreases with the frequency of LH waves ? over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption. The absorption coefficient ?? increases with n e when n e ? 8 × 1019 m-3, while decreases with n e when n e becomes larger, and there is a peak value of ?? when n e ? 8 × 1019 m-1 for the ITER-like scenario. The influence of spectral broadening in parametric decay instabilities on the absorption coefficient is evaluated. The value of ?? with n ? being 2.5 is almost two times larger than that with n ? 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.

Wang, J.; Zhang, X.; Yu, L.; Zhao, X.

2014-12-01

225

Comparative in vitro microdosimetric study of murine- and human-derived cancer cells exposed to alpha particles.  

PubMed

Diffusing alpha-emitter radiation therapy (DaRT) is a proposed new form of brachytherapy using ? particles to treat solid tumors. The method relies on implantable ²²?Ra-loaded sources that continually release short-lived ?-particle-emitting atoms that spread inside the tumor over a few millimeters. This treatment was demonstrated to have a significant effect on tumor growth in murine and human-derived models, but the degree of tumor response varied across cell lines. Tumor response was found to correlate with the degree of radionuclide spread inside the tumor. In this work we examined the radiosensitivity of individual cells to determine its relationship to tumor response. Cells were irradiated in vitro by ? particles using a ²²?Th irradiator, with the mean lethal dose, D?, estimated from survival curves generated by standard methods. The results were further analyzed by microdosimetric tools to calculate z?, the specific energy resulting in a survival probability of 1/e for a single cell, which is considered to better represent the intrinsic radiosensitivity of individual cells. The results of the study demonstrate that, as a rule, tumors that respond more favorably to the DaRT treatment are also characterized by higher intrinsic cellular radiosensitivities, with D? ranging from 0.7 Gy to 1.5 Gy for the extreme cases and z? following the same trend. PMID:22077335

Lazarov, E; Arazi, L; Efrati, M; Cooks, T; Schmidt, M; Keisari, Y; Kelson, I

2012-03-01

226

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...

227

Cosmic Rays High Energy Particles  

E-print Network

1937 Anderson, Neddermeyer Muon 1937 Powell Positron ! Antimatter ! 1932 Anderson Pion Cloud chambers ? Charged particles = seeds for condensation cloud chamber / bubble chamber Cosmics Leaving OUtdoor Droplets for condensation cloud chamber / bubble chamber Cosmics Leaving OUtdoor Droplets CERN #12;T.Hebbeker Lightnings

Hebbeker, Thomas

228

Radii and Binding Energies of Nuclei in the Alpha-Cluster Model  

E-print Network

The alpha-cluster model is based on two assumptions that the proton-neutron pair interactions are responsible for adherence between alpha-clusters and that the NN-interaction in the alpha-clusters is isospin independent. It allows one to estimate the Coulomb energy and the short range inter-cluster bond energy in dependence on the number of clusters. The charge radii are calculated on the number of alpha-clusters too. Unlike the Weizsacker formula in this model the binding energies of alpha-clusters and excess neutrons are estimated separately. The calculated values are in a good agreement with the experimental data.

G. K. Nie

2006-03-22

229

Detection of alpha radiation in a beta radiation field  

DOEpatents

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.

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

2001-01-01

230

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

231

Use of neutralized knock-on ion fluxes for alpha-particle confinement studies  

NASA Astrophysics Data System (ADS)

One of the objectives of neutral particle diagnostics on large tokamaks exploring DT plasma is to measure the distribution functions of fast deuterium (D) and tritium (T) ions in a suprathermal energy range. High energy tails in D,T-ion energy distributions (so-called knock-on ions) appear as a result of close elastic collisions between thermal fuel ions and fusion ?-particles. The knock-on ion density depends directly on the density and energy distribution of the ?-particles. Therefore measurements of the neutralized knock-on D,T-ion fluxes escaping from the plasma volume can provide information on the ?-particle confinement in DT plasma. This paper presents the results of a numerical simulation for the neutralized fast D,T-ion fluxes in the case of ITER fusion plasma. Feasible experimental measurements of the fluxes are considered with respect to the neutral particle diagnostics. We will show that the diagnostics can provide information on the confinement properties of fast ions in DT fusion plasma.

Nesenevich, V. G.; Afanasyev, V. I.; Goncharov, P. R.; Mironov, M. I.; Petrov, M. P.; Petrov, S. Ya

2014-12-01

232

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

233

Gas production due to alpha particle degradation of polyethylene and polyvinylchloride  

SciTech Connect

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.

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

1998-07-01

234

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

PubMed

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

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

235

Elastic {alpha}-scattering on proton rich nuclei at astrophysically relevant energies  

SciTech Connect

In order to improve the reliability of statistical model calculations in the region of heavy proton rich nuclei several elastic alpha scattering experiments have been carried out at low bombarding energies on various even-even and semi-magic nuclei. The extracted local optical potential parameters can be compared with the predictions of global alpha potentials. A study on 112,124Sn({alpha},{alpha})112,124Sn has been made to test the global alpha potentials at both the proton and neutron rich sides of an isotopic chain. The present work describes the experimental challenges of high precision scattering experiments at low energy.

Fueloep, Zs.; Gyuerky, Gy.; Kiss, G. G.; Mate, Z.; Somorjai, E. [ATOMKI, P.O. Box 51. H-4001 Debrecen (Hungary); Galaviz, D.; Mohr, P.; Zilges, A. [Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Rauscher, T. [Universitaet Basel, CH-4056 Basel (Switzerland)

2006-07-12

236

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

SciTech Connect

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.

Bae, Y.K.

1982-08-01

237

Energy of a Many-Particle System  

Microsoft Academic Search

A formulation of the energy eigenvalue problem for a many-particle system is presented in several alternative forms and, following Brueckner and his collaborators, the energy of the system is expressed in terms of solutions to the two-body problem. This work bears considerable resemblance to Brueckner's \\

W. B. Riesenfeld; K. M. Watson

1956-01-01

238

Helium burning and the death of massive stars from the beta-delayed alpha-particle emission of {sup 16}N  

SciTech Connect

Helium burning in massive stars and red giants (at {approximately}200 MK) allows for the nucleo-synthesis of {sup 12}C and {sup 16}O via the {sup 8}Be({alpha},{gamma}){sup 12}C triple alpha capture reaction and the {sup 12}C({alpha},{gamma}) {sup 16}O capture reaction. At 300 keV, the most efficient energy for burning of helium, the resonant triple alpha-capture reaction is well understood but the {sup 12}C({alpha},{gamma}){sup 16}O reaction is poorly understood, due to the fact that it is a non-resonant reaction governed by the bound 1{sup {minus}} and 2{sup +} states of {sup 16}O. The results of helium burning--the {sup 12}C/{sup 16}O ratio, determines the abundance of heavy elements and the dynamics of a massive star at its last stages before a supernova. Attempts to measure the cross section of the {sup 12}C({alpha},{gamma}){sup 16}O reaction lead to values of the E1 S-factor ranging from 0-500 keV-b. The author has measured the astrophysical p-wave S(300)-factor of the {sup 12}C({alpha},{gamma}){sup 16}O reaction by measuring the inverse process of the beta-delayed alpha-particle emission of {sup 16}N, with an increased sensitivity to the (virtual) reduced alpha-particle width of the bound 1{sup {minus}} state at 7.12 MeV in {sup 16}O. The enhanced sensitivity is due to a kinematical factor and matrix elements of the beta decay of {sup 16}N. An experiment performed at Yale University and at the MSU radioactive beam facility with a sensitivity for {sup 16}N beta-decay branching ratio on the order of 10{sup {minus}9} to 10{sup {minus}10} will be discussed. These data (together with other data) were used to extract the S-factor from an R-matrix theory and the author quotes S{sub E1}(300) = 95 {+-} 6(stat){+-}28(syst) keV-b, in agreement with a concurrent experiment at TRIUMF and the one deduced from stellar models of 12 to 40 solar masses stars.

Gai, M.

1993-04-01

239

Energy-range relation and mean energy variation in therapeutic particle beams  

SciTech Connect

Analytical expressions for the mean energy and range of therapeutic light ion beams and low- and high-energy electrons have been derived, based on the energy dependence of their respective stopping powers. The new mean energy and range relations are power-law expressions relevant for light ion radiation therapy, and are based on measured practical ranges or known tabulated stopping powers and ranges for the relevant incident particle energies. A practical extrapolated range, R{sub p}, for light ions was defined, similar to that of electrons, which is very closely related to the extrapolated range of the primary ions. A universal energy-range relation for light ions and electrons that is valid for all material mixtures and compounds has been developed. The new relation can be expressed in terms of the range for protons and alpha particles, and is found to agree closely with experimental data in low atomic number media and when the difference in the mean ionization energy is low. The variation of the mean energy with depth and the new energy-range relation are useful for accurate stopping power and mass scattering power calculations, as well as for general particle transport and dosimetry applications.

Kempe, Johanna; Brahme, Anders [Division of Medical Radiation Physics, Department of Oncology-Pathology, Karolinska Institutet and Stockholm University, Box 260, SE-171 76 Stockholm (Sweden)

2008-01-15

240

Calculation of extracted ion beam particle distribution including within-extractor collisions from H-alpha Doppler shift measurements  

SciTech Connect

Prototype long pulse ion sources are being developed and tested toward the goal of a deuterium beam extraction of 120 keV/65 A. The latest prototype source consists of a magnetic bucket plasma generator and a four-grid copper accelerator system with multicircular apertures of 568 holes. To measure the angular divergence and the ion species of the ion beam, an optical multichannel analyzer (OMA) system for a Doppler-shifted H-alpha lights was set up at the end of a gas-cell neutralizer. But the OMA data are very difficult to analyze due to a large background level on the top of the three energy peaks (coming from H{sup +}, H{sub 2}{sup +}, and H{sub 3}{sup +}). These background spectra in the OMA signals seem to result from partially accelerated ion beams in the accelerator. Extracted ions could undergo a premature charge exchange as the accelerator column tends to have a high hydrogen partial pressure from the unused gas from the plasma generator, resulting in a continuous background of partially accelerated beam particles at the accelerator exit. This effect is calculated by accounting for all the possible atomic collision processes and numerically summing up three ion species across the accelerator column. The collection of all the atomic reaction cross sections and the numerical summing up will be presented. The result considerably depends on the background pressure and the ion beam species ratio (H{sup +}, H{sub 2}{sup +}, and H{sub 3}{sup +}). This effect constitutes more than 20% of the whole particle distribution. And the energy distribution of those suffering from collisions is broad and shows a broad maximum in the vicinity of the half and the third energy region.

Kim, Tae-Seong; Kim, Jinchoon; In, Sang Ryul; Jeong, Seung Ho [University of Science and Technology, Daejeon 305-353 (Korea, Republic of); ProScience, San Diego, California 92129 (United States); Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of)

2008-02-15

241

On alpha heating in toroidal devices  

Microsoft Academic Search

Studies of the alpha particle losses and heating profiles for an alpha-heated TFTR-sized tokamak and a small field-reversed mirror reactor (FRM) are presented. The slowing-down and drift of high-energy alpha particles, including detailed orbital effects, is approximated for tokamak geometry using the SYMALF multi-energy-angle code. Results of the calculation for a beam-driven TFTR-type plasma indicate that, except for the center

G. H. Miley

1979-01-01

242

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

E-print Network

rights reserved. Keywords: PADC; CR-39; Solid-state nuclear track detector; SSNTD; Radiobiology; Alpha particle 1. Introduction Ionizing radiation leads to production of reactive oxygen species in human cells. The effects of ionizing radiation can occur in irradiated (or targeted) cells or in non-irradiated (or non

Yu, K.N.

243

High energy particles and quanta in astrophysics  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

244

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

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

245

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

SciTech Connect

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.

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

2007-10-26

246

Low-energy cross sections in the {sup 12}C({alpha},{gamma}){sup 16}O reaction  

SciTech Connect

The low-energy {sup 12}C({alpha},{gamma}){sup 16}O reaction is analyzed with the potential model. The potentials are chosen from the deep potential describing the {alpha}-particle nuclear rainbow phenomena at high energies. Below E{sub c.m.}=1 MeV, the cross section is found to be dominated by the E2 transition to the ground state of {sup 16}O. No enhancement of the E1 component at low energies is predicted. The extrapolated astrophysical S-factors at E{sub c.m.}=0.3 MeV are S{sub E2}=150 keV b and S{sub E1}=3 keV b.

Katsuma, M. [Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles, CP226, B-1050 Brussels (Belgium)

2008-09-15

247

Elastic {alpha} scattering on {sup 112}Sn and {sup 124}Sn at astrophysically relevant energies  

SciTech Connect

The cross sections for the elastic scattering reactions {sup 112,124}Sn({alpha},{alpha}){sup 112,124}Sn at energies above and below the Coulomb barrier are presented and compared to predictions for global {alpha}-nucleus potentials. The high precision of the new data allows a study of the global {alpha}-nucleus potentials at both the proton- and neutron-rich sides of an isotopic chain. In addition, local {alpha}-nucleus potentials have been extracted for both nuclei and used to reproduce elastic scattering data at higher energies. Predictions from the capture cross section of the reaction {sup 112}Sn({alpha},{gamma}){sup 116}Te at astrophysically relevant energies are presented and compared to experimental data.

Galaviz, D.; Mohr, P.; Zilges, A. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, D-64289 Darmstadt (Germany); Fueloep, Zs.; Gyuerky, Gy.; Mate, Z.; Somorjai, E. [ATOMKI, P.O. Box 51, H-4001 Debrecen (Hungary); Rauscher, T. [Departement fuer Physik und Astronomie, Universitaet Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)

2005-06-01

248

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

SciTech Connect

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.

Plionis, Alexander A [Los Alamos National Laboratory; Peterson, Dominic S [Los Alamos National Laboratory; Tandon, Lav [Los Alamos National Laboratory; Lamont, Stephen P [Los Alamos National Laboratory

2009-01-01

249

Chinese high energy cosmic particle explorer (DAMPE)  

NASA Astrophysics Data System (ADS)

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 CAS’s 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.

Chang, Jin; Hu, Yiming; Wu, Jian

250

Studies of High Energy Particle Astrophysics  

SciTech Connect

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.

Nitz, David F [Michigan Technological University; Fick, Brian E [Michigan Technological University

2014-07-30

251

Pairing gaps and Fermi energies at scission for 296Lv alpha-decay  

E-print Network

The pairing corrections, the single particle occupation numbers, are investigated within density-dependent delta interaction formalism for pairing residual interactions. The potential barrier is computed in the framework of the macroscopic-microscopic model. The microscopic part is based on the Woods-Saxon two center shell model. The alpha-decay of a superheavy element is treated, by paying a special attention to the region of the scission configurations. The sequence of nuclear shapes follows the superasymmetric fission path for alpha decay. It was found that the pairing gaps of the states that reach asymptotically the potential well of the alpha particle have large values at scission but become zero after scission. The 1s1/2 single particle levels of the nascent alpha particle are fully occupied while the superior levels are empties in the scission region and remains in the same states during the penetration of the Coulomb barrier. The projection of the numbers of particle on the two fragments are obtained naturally. At scission, the nascent alpha particle forms a very bound cluster.

M. Mirea

2014-11-12

252

The alpha/beta interfaces of alpha(1)beta(1), alpha(3)beta(3), and F1: domain motions and elastic energy stored during gamma rotation.  

PubMed

ATP synthase (F(o)F(1)) consists of F(1) (ATP-driven motor) and F(o) (H(+)-driven motor). F(1) is a complex of alpha(3)beta(3)gammadeltaepsilon subunits, and gamma is the rotating cam in alpha(3)beta(3). Thermophilic F(1) (TF(1)) is exceptional in that it can be crystallized as a beta monomer and an alpha(3)beta(3) oligomer, and it is sufficiently stable to allow alphabeta refolding and reassembly of hybrid complexes containing 1, 2, and 3 modified alpha or beta. The nucleotide-dependent open-close conversion of conformation is an inherent property of an isolated beta and energy and signals are transferred through alpha/beta interfaces. The catalytic and noncatalytic interfaces of both mitochondrial F(1) (MF(1)) and TF(1) were analyzed by an atom search within the limits of 0.40 nm across the alphabeta interfaces. Seven (plus thermophilic loop in TF(1)) contact areas are located at both the catalytic and noncatalytic interfaces on the open beta form. The number of contact areas on closed beta increased to 11 and 9, respectively, in the catalytic and noncatalytic interfaces. The interfaces in the barrel domain are immobile. The torsional elastic strain applied through the mobile areas is concentrated in hinge residues and the P-loop in beta. The notion of elastic energy in F(o)F(1) has been revised. X-ray crystallography of F(1) is a static snap shot of one state and the elastic hypotheses are still inconsistent with the structure, dyamics, and kinetics of F(o)F(1). The domain motion and elastic energy in F(o)F(1) will be elucidated by time-resolved crystallography. PMID:15254382

Kagawa, Y; Hamamoto, T; Endo, H

2000-10-01

253

Radioactive Positron Emitter Production by Energetic Alpha Particles in Solar Flares  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

254

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

SciTech Connect

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.

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

1992-03-01

255

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

SciTech Connect

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.

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

1992-03-01

256

Elastic and Inelastic Scattering of Alpha-Particles and Protons from Sm-144  

E-print Network

of both spin and parity to the strongly excited levels we observed. All lev- els observed in the o.-particle work mere also ob- served in the proton work, and no new levels were observed. The spin and parity assignments from the proton study... of the level at 2.45 MeV. A level near this energy has already been the subject of some controversy. ""From our data it would appear that there are two levels near this energy. A lev- el with J"= 0+ and E*= 2.481 MeV has been report- d ' ' as being...

Barker, J. H.; Hiebert, John C.

1971-01-01

257

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

SciTech Connect

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.

McFarlane, Steven; Nicholl, Mary Jane; Sutherland, Jane S.; Preston, Chris M., E-mail: Christopher.preston@glasgow.ac.u

2011-05-25

258

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

259

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

NASA Technical Reports Server (NTRS)

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.

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

260

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

NASA Astrophysics Data System (ADS)

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.

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

261

Negative energy particle as an expanding wormhole  

NASA Astrophysics Data System (ADS)

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 ?. The throat expands with the same acceleration 2?|?| 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 -?c/R, where R is the throat radius, similar in form with the Casimir energy inside an expanding spherical box.

Culetu, Hristu

2015-03-01

262

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

SciTech Connect

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.

Khanna, S.M. [Defence Research Establishment Ottawa, Ontario (Canada)] [Defence Research Establishment Ottawa, Ontario (Canada); Liu, H.C.; Wilson, P.H.; Li, L.; Buchanan, M. [National Research Council, Ottawa, Ontario (Canada). Inst. of Microstructural Sciences] [National Research Council, Ottawa, Ontario (Canada). Inst. of Microstructural Sciences

1996-12-01

263

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

SciTech Connect

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

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

1989-01-01

264

MCNPX alpha particle dose estimate to the skin tissue from a low-enriched uranium fuel fragment.  

PubMed

Three alpha volume sources (low-enriched uranium-U(3)Si) were analysed using Monte Carlo modelling in order to calculate the dose delivered to the dermis from a small embedded fuel fragment (sliver). Three shapes were analysed using MCNPX 2.6.0 code: sphere, cylinder and parallelepiped. Essentially, two kinds of runs were performed: count rate run and dosimetry run. The two results were combined to estimate dose coefficients that can be used for alpha dose assessments in the field. The two results were obtained for the 1 and 0 cm counting geometries. These results are very stable and show that the actual dose delivered to the skin per unit count rate for the recovered particle is independent of the shape of the volume alpha source. PMID:22003183

Atanackovic, J

2012-06-01

265

Uncertainties on the determination of the strong coupling alpha_s from the energy evolution of jet fragmentation functions at low z  

E-print Network

The QCD coupling alpha_s is determined at NLO*+NMLLA accuracy from the comparison of experimental jet data to theoretical predictions of the energy-evolution of the parton-to-hadron fragmentation function moments (multiplicity, peak, width, skewness) at low fractional hadron momentum z. From the existing e+e- and e-p jet data, we obtain alpha_s(m_Z^2) = 0.1195 +/- 0.0021 (exp.) {+0.0015}_{-0.0} (scale) at the Z mass. The uncertainties of the extracted alpha_s value are discussed.

David d'Enterria; Redamy Pérez-Ramos

2014-10-17

266

High Energy Particles in the Solar Corona  

E-print Network

Collective Ampere law interactions producing magnetic flux tubes piercing through sunspots into and then out of the solar corona allow for low energy nuclear reactions in a steady state and high energy particle reactions if a magnetic flux tube explodes in a violent event such as a solar flare. Filamentous flux tubes themselves are vortices of Ampere currents circulating around in a tornado fashion in a roughly cylindrical geometry. The magnetic field lines are parallel to and largely confined within the core of the vortex. The vortices may thereby be viewed as long current carrying coils surrounding magnetic flux and subject to inductive Faraday and Ampere laws. These laws set the energy scales of (i) low energy solar nuclear reactions which may regularly occur and (ii) high energy electro-weak interactions which occur when magnetic flux coils explode into violent episodic events such as solar flares or coronal mass ejections.

A. Widom; Y. N. Srivastava; L. Larsen

2008-04-16

267

Cosmic absorption of ultra high energy particles  

E-print Network

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.

Ruffini, R; Xue, S -S

2015-01-01

268

High Energy Particles in the Solar Corona  

E-print Network

Collective Ampere law interactions producing magnetic flux tubes piercing through sunspots into and then out of the solar corona allow for low energy nuclear reactions in a steady state and high energy particle reactions if a magnetic flux tube explodes in a violent event such as a solar flare. Filamentous flux tubes themselves are vortices of Ampere currents circulating around in a tornado fashion in a roughly cylindrical geometry. The magnetic field lines are parallel to and largely confined within the core of the vortex. The vortices may thereby be viewed as long current carrying coils surrounding magnetic flux and subject to inductive Faraday and Ampere laws. These laws set the energy scales of (i) low energy solar nuclear reactions which may regularly occur and (ii) high energy electro-weak interactions which occur when magnetic flux coils explode into violent episodic events such as solar flares or coronal mass ejections.

Widom, A; Larsen, L

2008-01-01

269

Energy loss of proton, ? particle, and electron beams in hafnium dioxide films  

NASA Astrophysics Data System (ADS)

The electronic stopping power, S , of HfO2 films for proton and alpha particle beams has been measured and calculated. The experimental data have been obtained by the Rutherford backscattering technique and cover the range of 120-900 and 120-3000 keV for proton and alpha particle beams, respectively. Theoretical calculations of the energy loss for the same projectiles have been done by means of the dielectric formalism using the Mermin energy loss function—generalized oscillator strength (MELF-GOS) model for a proper description of the HfO2 target on the whole momentum-energy excitation spectrum. At low projectile energies, a nonlinear theory based on the extended Friedel sum rule has been employed. The calculations and experimental measurements show good agreement for protons and a quite good one for alpha particles. In particular, the experimental maximums of both stopping curves (around 120 and 800 keV, respectively) are well reproduced. On the basis of this good agreement, we have also calculated the inelastic mean-free path (IMFP) and the stopping power for electrons in HfO2 films. Our results predict a minimum value of the IMFP and a maximum value of the S for electrons with energies around 120 and 190 eV, respectively.

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

2009-12-01

270

Particle Production and Flow at SIS Energies  

E-print Network

An overview is given over recent measurements of flow and particle production in the energy range from 0.1 to 2AGeV. Excitation functions for the directed sideward and the azimuthally symmetric transverse flow are presented and show the importance of flow phenomena in this incident energy regime. Rapidity density distributions are indicative of a system size dependence of the stopping process. The role of strange particles as a probe for the hot and dense phase of hadronic matter is discussed with respect to the production and propagation. The spectra of Kaons indicate an equilibration with the surrounding baryons during the expansion while their directed flow pattern is different from that of the nucleons.

N. Herrmann; FOPI Collaboration

1996-10-24

271

Dissipation flow-frames: particle, energy, thermometer  

E-print Network

We associate the following physical co-mover conditions of to different frame choices: i) Eckart: particle flow, ii) Landau-Lifshitz: energy flow, iii) J\\"uttner: moving thermometer frame. The role of fixing a flow-frame is analysed with respect to local equilibrium concentrating on dissipative currents and forces in single component relativistic fluids. The special role of a "J\\"uttner frame" is explored and contrasted to the more common Eckart and Landau-Lifshitz choices.

P. Ván; T. S. Biró

2013-05-14

272

Dissipation flow-frames: particle, energy, thermometer  

E-print Network

We associate the following physical co-mover conditions of to different frame choices: i) Eckart: particle flow, ii) Landau-Lifshitz: energy flow, iii) J\\"uttner: moving thermometer frame. The role of fixing a flow-frame is analysed with respect to local equilibrium concentrating on dissipative currents and forces in single component relativistic fluids. The special role of a "J\\"uttner frame" is explored and contrasted to the more common Eckart and Landau-Lifshitz choices.

Ván, P

2013-01-01

273

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

Microsoft Academic Search

Low emission barriers and large subbarrier anisotropies in the alpha-particle decay with respect to the spin direction, of Sn and rare earth compound nuclei, are examined in the light of recent calculations incorporating deformation. To explore the possibility of a correlation between the proton emission barriers and nuclear deformation, we studied proton spectra from the ⁵²Cr(³⁴S,2p2n)⁸²Sr reaction. The proton spectra

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

1989-01-01

274

Micro-collimator fabricated by alpha-particle irradiation of polyallyldiglycol carbonate polymer film and subsequent chemical etching  

Microsoft Academic Search

In the present paper, we propose a method to fabricate a ``micro-collimator'' with a thickness of 15 mum. A commercially available PADC film with a thickness of 100 mum was first chemically etched with NaOH\\/ethanol solution to obtain a thin PADC film. This thin PADC film was then irradiated by 5 MeV alpha particles through a ``macro-collimator'' with a thickness

V. W. Y. Choi; E. H. W. Yum; K. N. Yu

2010-01-01

275

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

NASA Astrophysics Data System (ADS)

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 ?m 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 ?Ci 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.

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

2010-03-01

276

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

SciTech Connect

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.

Betzler, Benjamin R. [Los Alamos National Laboratory; Kiedrowski, Brian C. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory; Martin, William R. [Los Alamos National Laboratory

2012-09-04

277

RADIATION DECOMPOSITION OF SODIUM CHLORATE COMPARISON OF YIELDS AND THE POST-IRRADIATION ANNEALING BEHAVIOR FOR IRRADIATION BY $gamma$-RAYS AND $alpha$PARTICLES  

Microsoft Academic Search

The production of chloride as a function of gamma and alpha radiation ; doses was compared. The yield for decomposition by alpha particles at 25 deg C ; was found to be about the same as the yield for samples irradiated with gamma ; rays at 25 deg C and then annealed at approximates 200 deg C, or for samples

Hochanadel

1963-01-01

278

Method and apparatus for generating low energy nuclear particles  

DOEpatents

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.

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

1999-02-09

279

Method and apparatus for generating low energy nuclear particles  

DOEpatents

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.

Powell, James R. (Shoreham, NY); Reich, Morris (Flushing, NY); Ludewig, Hans (Brookhaven, NY); Todosow, Michael (Miller Place, NY)

1999-02-09

280

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

SciTech Connect

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

Zhang Yifu [Engineering Research Center of Organosilicon Compound and Material, Ministry of Education of China, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Liu Xinghai, E-mail: liuxh@whu.edu.c [School of Printing and Packaging, Wuhan University, Wuhan 430079 (China); Nie Jiaorong [Jianghe Chemical Factory of CSSG, Yuan'an 444200 (China); Yu Lei; Zhong Yalan [Engineering Research Center of Organosilicon Compound and Material, Ministry of Education of China, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Huang Chi, E-mail: chihuang@whu.edu.c [Engineering Research Center of Organosilicon Compound and Material, Ministry of Education of China, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)

2011-02-15

281

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

SciTech Connect

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

Belhout, A.; Kiener, J.; Coc, A.; Duprat, J.; Engrand, C.; Fitoussi, C.; Gounelle, M.; Lefebvre-Schuhl, A.; Sereville, N. de; Tatischeff, V.; Thibaud, J.-P.; Chabot, M.; Hammache, F.; Benhabiles-Mezhoud, H. [USTHB, Faculte de Physique, BP 32, El-Alia, 16111 Bab Ezzouar, Algiers (Algeria); Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), CNRS-IN2P3 et Universite Paris-Sud, F-91405 Orsay Campus (France); Institut de Physique Nucleaire (IPN), CNRS-IN2P3 et Universite Paris-Sud, F-91400 Orsay (France); Departement de Physique, Universite de Boumerdes, Avenue de l'Independance, 35000 Boumerdes (Algeria)

2007-09-15

282

Do the various radiations present in BNCT act synergistically? Cell survival experiments in mixed alpha-particle and gamma-ray fields.  

PubMed

In many radiotherapy situations patients are exposed to mixed field radiation. In particular in BNCT, as with all neutron beam exposures, a significant fraction of the dose is contributed by low LET gamma ray photons. The components of such a mixed field may show a synergistic interaction and produce a greater cell kill effect than would be anticipated from the independent action of the different radiation types. Such a synergy would have important implications for treatment planning and in the interpretation of clinical results. An irradiation setup has been created at the Medical Research Council in Harwell to allow simultaneous irradiation of cells by cobalt-60 gamma rays and plutonium-238 alpha-particles. The setup allows for variation of dose and dose rates for both sources along with variation of the alpha particle energy. A series of cell survival assays for this mixed field have been carried out using V79-4 cells and compared to exposures to the individual components of the field under identical conditions. In the experimental setup described no significant synergistic effect was observed. PMID:19376715

Phoenix, Ben; Green, Stuart; Hill, Mark A; Jones, Bleddyn; Mill, Andrew; Stevens, David L

2009-07-01

283

Confined energy distribution for charged particle beams  

DOEpatents

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.

Jason, Andrew J. (Los Alamos, NM); Blind, Barbara (Los Alamos, NM)

1990-01-01

284

Evaluation of excitation energy and spin from light charged particles multiplicities in heavy-ion collisions  

E-print Network

A simple procedure for evaluating the excitation energy and the spin transfer in heavy-ion dissipative collisions is proposed. It is based on a prediction of the GEMINI evaporation code : for a nucleus with a given excitation energy, the average number of emitted protons decreases with increasing spin, whereas the average number of alpha particles increases. Using that procedure for the reaction 107Ag+58Ni at 52 MeV/nucleon, the excitation energy and spin of quasi-projectiles have been evaluated. The results obtained in this way have been compared with the predictions of a model describing the primary dynamic stage of heavy-ion collisions.

The INDRA; CHIMERA Collaborations; :; J. C. Steckmeyer; Z. Sosin; K. Grotowski; P. Pawlowski

2005-04-25

285

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

SciTech Connect

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

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

2011-01-01

286

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

287

Plasma Phys. Control. Fusion 39 (1997) A275A283. Printed in the UK PII: S0741-3335(97)81172-4 Alpha-particle physics in the tokamak fusion test reactor  

E-print Network

Plasma Phys. Control. Fusion 39 (1997) A275­A283. Printed in the UK PII: S0741-3335(97)81172-4 Alpha-particle physics in the tokamak fusion test reactor DT experiment S J Zwebena , V Arunasalama fusion test reactor. Alpha particles are generally well confined in MHD-quiescent discharges, and alpha

288

Alpha-Cluster Model, Charge Symmetry of Nuclear Force and Single Particle Bound State Potential in Symmetrical Nuclei  

E-print Network

A phenomenological alpha-cluster model based on the charge symmetry of nuclear force allows one to estimate the last proton position radius (LPPR) in a symmetrical nucleus. The values of LPPR obtained for the symmetrical nuclei with 5=15 it is inappropriate to represent a single particle bound state by the Woods-Saxon potential. For the nuclei with 5<=Z<=14 the error of the spectroscopic factor obtained with standard parameters in DWBA analysis of pure peripheral one nucleon transfer reactions is estimated. It is shown that for some nuclei using the standard parameters brings an error more than 20%.

G. K. Nie

2011-06-21

289

Ionization of noble gas atoms by alpha particles and fission fragments from the decay of 252Cf1  

NASA Astrophysics Data System (ADS)

Charge state distributions of He, Ne, Ar, Kr, and Xe ions produced in single collisions with alpha particles and fission fragments from the decay of 252Cf have been measured using time of flight spectrometry. The measurements reveal that the maximum number of electrons removed in a fission fragment collision ranges from eight in the case of Ne to 20 in the case of Xe. Recoil-ion production cross sections have been determined for the resolvable ionic charge states and compared with the predictions of a model based upon the independent electron approximation.

Hill, B. M.; Watson, R. L.; Wohrer, K.; Bandong, B. B.; Sampoll, G.; Horvat, V.

1993-07-01

290

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

SciTech Connect

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.

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

2013-01-30

291

Detachment Energies of Spheroidal Particles from Fluid-Fluid Interfaces  

E-print Network

The energy required to detach a single particle from a fluid-fluid interface is an important parameter for designing certain soft materials, for example, emulsions stabilised by colloidal particles, colloidosomes designed for targeted drug delivery, and bio-sensors composed of magnetic particles adsorbed at interfaces. For a fixed particle volume, prolate and oblate spheroids attach more strongly to interfaces because they have larger particle-interface areas. Calculating the detachment energy of spheroids necessitates the difficult measurement of particle-liquid surface tensions, in contrast with spheres, where the contact angle suffices. We develop a simplified detachment energy model for spheroids which depends only on the particle aspect ratio and the height of the particle centre of mass above the fluid-fluid interface. We use lattice Boltzmann simulations to validate the model and provide quantitative evidence that the approach can be applied to simulate particle-stabilized emulsions, and highlight the experimental implications of this validation.

Gary B. Davies; Timm Krüger; Peter V. Coveney; Jens Harting

2014-10-28

292

Detachment energies of spheroidal particles from fluid-fluid interfaces  

NASA Astrophysics Data System (ADS)

The energy required to detach a single particle from a fluid-fluid interface is an important parameter for designing certain soft materials, for example, emulsions stabilised by colloidal particles, colloidosomes designed for targeted drug delivery, and bio-sensors composed of magnetic particles adsorbed at interfaces. For a fixed particle volume, prolate and oblate spheroids attach more strongly to interfaces because they have larger particle-interface areas. Calculating the detachment energy of spheroids necessitates the difficult measurement of particle-liquid surface tensions, in contrast with spheres, where the contact angle suffices. We develop a simplified detachment energy model for spheroids which depends only on the particle aspect ratio and the height of the particle centre of mass above the fluid-fluid interface. We use lattice Boltzmann simulations to validate the model and provide quantitative evidence that the approach can be applied to simulate particle-stabilized emulsions, and highlight the experimental implications of this validation.

Davies, Gary B.; Krüger, Timm; Coveney, Peter V.; Harting, Jens

2014-10-01

293

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

NASA Technical Reports Server (NTRS)

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.

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

294

Advances in the CO2 laser collective Thomson scattering fast ion\\/alpha particle diagnostic (abstract)  

Microsoft Academic Search

A collective Thomson scattering diagnostic is being developed for the measurement of confined fast ions in hot, dense plasmas. This includes such measurements as the ion tail in JT-60U and the alphas produced in a burning reactor or the upgraded Joint European Torus device. The diagnostic also has the capability of measuring the isotopic ratio of the core ions such

R. K. Richards; D. P. Hutchinson

2001-01-01

295

Technical NoteFEASIBILITY STUDIES OF ALPHA-PARTICLE CHANNELING IN MIRROR MACHINES  

E-print Network

or by otherwise sustaining plasma confinement, thus increasing the effective fusion reactiv- ity. To identify the effective fusion reactivity by a fac- tor of 2.8. In this paper we discuss and reformulate the results Note: Some figures in this paper are in color only in the electronic version. I. INTRODUCTION Alpha

296

Alpha particle transfer reaction [sup 12]C([sup 11]B,[sup 7]Li)[sup 16]O and lack of evidence for a tetrahedral shape of the [sup 16]O nucleus  

SciTech Connect

Angular distributions of the alpha particle transfer reaction [sup 12]C([sup 11]B,[sup 7]Li)[sup 16]O were measured for 28, 35, 40, 50, 56, 60, and 80 MeV beam energies. Exact finite range distorted-wave Born approximation (DWBA) analysis was performed for eight states of [sup 16]O: ground state, 6.13 MeV (3[sup [minus

Barna, R.; D'Amico, V.; De Pasquale, D.; Italiano, A.; Lamberto, A. (Dipartimento di Fisica, Universita di Messina and Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Gruppo collegato di Messina, I-98166 Messina (Italy)); Jarczyk, L.; Kamys, B.; Kistryn, M.; Kozela, A.; Magiera, A.; Rudy, Z.; Strzalkowski, A. (Institute of Physics, Jagellonian University, PL-30059 Cracow (Poland)); Albergo, S.; Potenza, R.; Romanski, J. (Dipartimento di Fisica, Universita di Catania and Istituto Nazionale di Fisica Nucleare, Sezione di Catania, I-95129 Catania (Italy))

1994-07-01

297

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

Microsoft Academic Search

This thesis addresses the problem of α-particle-induced charge collection in high-density dynamic random access memories. A novel technique for the measurement of charge collection in high-density memory cells and bit lines due to α-particle strikes was developed. The technique involves D.C. tests on simple test structures with an α-particle source on the device package as a lid. The advantages of

Oldiges

1989-01-01

298

Pre-equilibrium mechanisms in the93Nb(p,alpha) inclusive reaction at incident energies from 65 to 160 MeV  

E-print Network

The reaction mechanism of pre-equilibrium proton-induced $\\alpha $-particle emission from 93Nb at an incident energy of 100 MeV was investigated with polarized projectiles. A formalism based on the statistical multistep direct emission model of Feshbach, Kerman and Koonin was found to give a reasonably good reproduction of cross section and analyzing power angular distributions at various emission energies. Existing experimental distributions for the same reaction at an incident energy of 65 MeV were also analyzed with the same model. The incident-energy variation from 65 MeV up to 160 MeV was found to be consistent with the predictions of the basic model. However, whereas knockout of an $\\alpha $ cluster is the dominant reaction mechanism in the final stage at the lowest- and highest incident energies, at 100 MeV a pickup process competes with comparable intensity in yield.

S. S. Dimitrova; A. A. Cowley; E. V. Zemlyanaya; K. V. Lukyanov

2014-09-10

299

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

DOEpatents

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.

Douglas, David R. (Newport News, VA); Benson, Stephen V. (Yorktown, VA)

2007-01-23

300

COLLIMATING TOUSCHEK PARTICLES IN AN ENERGY RECOVERY LINEAR ACCELERATOR  

E-print Network

COLLIMATING TOUSCHEK PARTICLES IN AN ENERGY RECOVERY LINEAR ACCELERATOR Michael P. Ehrlichman important in Energy Recovery Linacs (ERLs) not only be- cause of their large current, but also because particles. During the recovery phase of an energy recovery accelerator, E0 can decrease by a few orders

Hoffstaetter, Georg

301

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

SciTech Connect

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

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

1989-01-01

302

Experimental investigations of electron capture from atomic hydrogen and deuterium by alpha particles. Annual progress report, 15 September 1991--14 September 1992  

SciTech Connect

We report progress made during the period 15 September 1991--14 September 1992 on the project ``Experimental Investigations of Electron Capture from Atomic Hydrogen and Deuterium by Alpha Particles``. In the past year we have developed reliable, narrow energy spread, high-current sources of He{sup ++} based on direct-current magentron and electron-cyclotron resonance discharges. These sources have been proven on our test bench accelerator which has been upgraded to also allow us to test atomic hydrogen effusive targets. We have thus made substantial progress toward our goal of studying single electron capture from atomic hydrogen by doubly-ionized helium. A research plan for the upcoming year is also presented.

Gay, T.J.; Park, J.T.

1992-11-01

303

Non-gyrotropic proton and alpha-particle velocity distributions in the solar wind: TAUS observations and stability analysis  

NASA Technical Reports Server (NTRS)

Ion velocity distribution functions have been measured with high time resolution by the TAUS plasma instrument on the PHOBOS mission to Mars in 1989. The unambiguous separation of protons and alpha-particles by TAUS enabled us to study the nonthermal features of their distributions separately and to analyze the stability of the distributions against excitation of waves in the cyclotron-frequency domain. Typical nonthermal features include temperature anisotropies, with T(sub perpendicular) larger than T(sub parallel), and ion beam populations drifting along the local magnetic field direction. Also, distinctly non-gyrotropic alpha-particle velocity distributions were sometimes found. Non-gyrotropy strongly changes the wave dispersion and gives rise to new growing modes, related to the coupling of the standard wave modes existing in gyrotropic plasma. It is found that for the measured non-gyrotropic ion distributions the right-hand polarized wave can also be excited by a temperature anistropy instead of the usual beam drift.

Astudillo, H. F.; Marsch, E.; Livi, S.; Rosenbauer, H.

1995-01-01

304

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

SciTech Connect

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

Cecil, F.E.; Darrow, D.S.; Budny, R.V. [Department of Physics, Colorado School of Mines, Golden, Colorado (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey (United States)

2004-10-01

305

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

SciTech Connect

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.

Nakib, M. Z.; Cooley, J.; Kara, B.; Qiu, H.; Scorza, S. [Department of Physics, Southern Methodist University, Dallas, TX (United States)] [Department of Physics, Southern Methodist University, Dallas, TX (United States); Guiseppe, V. E. [Department of Physics, University of South Dakota, Vermillion, SD (United States)] [Department of Physics, University of South Dakota, Vermillion, SD (United States); Rielage, K. [Los Alamos National Laboratory, Los Alamos, NM (United States)] [Los Alamos National Laboratory, Los Alamos, NM (United States); Schnee, R. W. [Department of Physics, Syracuse University, Syracuse, NY (United States)] [Department of Physics, Syracuse University, Syracuse, NY (United States)

2013-08-08

306

Low energy particle composition. [cosmic rays produced in solar system  

NASA Technical Reports Server (NTRS)

A review is given of current knowledge of low-energy cosmic ray particles produced in the solar system. It is argued that the notion that the sun alone can accelerate particles in the solar system must be abandoned in light of evidence that Jupiter and earth may be sources of observed low-energy particles. Measurements of the composition and energy spectra of low-energy particles during quiet times are examined, emphasizing the abundance of protons and helium and of anomalous N, O, and Ne. The abundance of heavy particles (B, C, N, O, Ne, Ca and Fe) of unknown origin in the earth magnetosphere is examined. Reported observations of Jovian electrons are discussed and solar particle events with anomalous compositions (He-3 rich events and Fe rich events) are treated in detail. Nuclear abundances of solar particles, emphasizing their temporal and spatial variations are considered together with the nature of nuclear reaction products in solar flares.

Gloeckler, G.

1975-01-01

307

Development of a CO2 Laser Collective Thomson Scattering Fast Ion\\/Alpha Particle Diagnostic  

Microsoft Academic Search

A collective Thomson scattering diagnostic is being developed for the measurement of confined fast ions in hot, dense plasmas such as the ion tail in JT-60U and the alphas produced in a burning reactor or the upgraded JET device. A CO2 laser scattering system has been installed on JT-60U for this purpose. The diagnostic also has the capability of measuring

Roger K. Richards; Donald P. Hutchinson

2000-01-01

308

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

SciTech Connect

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.

Schieve, L.A.; Davis, F.; Freels, S. [Univ. of Illinois, Chicago, IL (United States)] [and others

1997-02-01

309

Alpha track analysis and fission track analysis for localizing actinide-bearing micro-particles in the Yenisey River bottom sediments  

Microsoft Academic Search

Distribution of actinides in bottom sediment and flood land soil cores collected from the Yenisey River near the Krasnoyarsk Mining and Chemical Combine (MCC) were analyzed. Actinide-bearing micro-particles were localized using alpha track analysis (ATA) and fission track analysis (FTA). Different types of radioactive micro-particles were found by analysis of the ratios of fission tracks to ?-tracks from single particles.

I. E. Vlasova; St. N. Kalmykov; Yu. V. Konevnik; S. G. Simakin; I. S. Simakin; A. Yu. Anokhin; Yu. A. Sapozhnikov

2008-01-01

310

Fine-particle emissions of energy production in Finland  

NASA Astrophysics Data System (ADS)

The aim of this study was to find out the fine-particle emissions (PM 2.5) of different energy production processes in Finland. The main purpose was to compare the calculated emission factors between different energy production concepts. The purpose was also to define what is known about fine-particle emissions and what should still be studied/measured. Only those energy production processes that produce a significant amount of direct emissions of solid particles have been treated here, i.e. pulverized combustion and oil burners from burner combustion, fluidized bed combustion processes, grate boilers, recovery boilers and diesel power plants. Secondary particles from gaseous pollutants have not been considered within this study. In pulverized coal combustion the particle emission is composed mainly of particles smaller than 5 ?m in aerodynamic diameter. Roughly half of the total mass of particle emission is composed of fine particles (PM 2.5). Depending on boiler size category and particle separation devices, the specific emission factor for fine particles is 1-30 mg MJ -1. For pulverized combustion of peat, ca. 20-25% of the total mass of particle emission is fine particles, and then the specific emission factor is between 5 and 8 mg MJ -1. For recovery boilers, the fine particle portion of the total particle emission is 50-60% (by mass) and the specific emission factor for fine particles varies considerably according to the boiler size category, being between 12 and 77 mg MJ -1. For oil burners, grate boilers and fluidized bed combustion processes, the fine-particle portion of the total particle emission could not be determined, because there were no applicable measurement results at hand. For these combustion techniques, more public measurements are needed in order to clarify the amount and composition of fine particles with different fuel varieties. Additionally, the chemical composition of fine particles is a very important feature when human health effects caused by particulate matter are considered.

Ohlström, Mikael O.; Lehtinen, Kari E. J.; Moisio, Mikko; Jokiniemi, Jorma K.

311

Low-level measurement of alpha-particle emitting nuclei in ceramics and lead  

Microsoft Academic Search

Nearly all natural materials contain trace quantities of uranium (U) and thorium (Th) and their daughter nuclides, many of\\u000a which emit ?-particles in their decay. Lead, at the end of the U-decay chain, typically contains some radioactive210Pb which is chemically inseparable from the other Pb isotopes. ?-particle emission from these decays can affect sensitive\\u000a electronic components, such as memory chips

R. J. McDonald; A. R. Smith; D. L. Hurley; E. B. Norman

1998-01-01

312

I. Excluded volume effects in Ising cluster distributions and nuclear multifragmentation. II. Multiple-chance effects in alpha-particle evaporation  

NASA Astrophysics Data System (ADS)

In Part I, 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 II, 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 as 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.

Breus, Dimitry Eugene

313

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

SciTech Connect

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.

Breus, Dimitry E.

2005-05-16

314

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

PubMed Central

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 0.82–6.0 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

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

2014-01-01

315

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

PubMed

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

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

2014-01-01

316

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

PubMed

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

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

2013-12-30

317

Amorphous silicon ionizing particle detectors  

DOEpatents

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.

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

1988-11-15

318

Amorphous silicon ionizing particle detectors  

DOEpatents

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.

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

1988-01-01

319

High energy shock waves induced increase in the local concentration of systemically given TNF-alpha.  

PubMed

The influence of high energy shock waves (HESW) on the local concentration of systemically given TNF-alpha was studied in a syngeneic rat bladder tumor model. 125I-TNF-alpha was injected intravenously and within 1 minute was followed by HESW tumor exposure. High energy shock waves were generated using an experimental shock wave emitter based on the Siemens Lithostar Plus. Administration of HESW to RBT323 tumors resulted in a 3-fold increase in uptake of 125I-TNF-alpha in the tumor compared with nontreated tumors, whereas the tissue distribution and pharmacokinetics of nontumor tissue were similar irrespective of HESW exposure. These results demonstrate that HESW administration leads to an increase in the local concentration of a systemically given drug. The capacity of HESW to increase local drug concentrations will be of importance in designing more effective combined treatment strategies. PMID:7966708

Cornel, E B; Oosterwijk, E; van de Streek, J D; Grutters, G; Debruyne, F M; Schalken, J A; Oosterhof, G O

1994-12-01

320

[Effect of titanium particles and TNF-alpha on the gene expression and activity of MMP-1, 2, 3 in human knee joint synovial cells].  

PubMed

This paper is aimed to investigate the effect of titanium (Ti) particles and tumor necrosis factor alpha (TNF-alpha) on the expressions of MMP-1, 2, 3 in human synovial cells, so as to explore the possible mechanism of osteolysis post-operation of metal-on-metal total joint arthroplasty in human synovial cells induced by Ti particles. In vitro cell cultures, human synovial cells were treated by Ti particles and/or TNF-alpha. The total RNA was isolated at 2 hours after the treatment. The gene expression of MMP-1, 2, 3 was analyzed by Semi-quantitative Reverse-transcriptional PCR and quantitative real-time PCR. Cell supernatant was collected at 12, 24, 48 hours after the treatment and Gelatin zymography was performed to detect the activity of MMP-2. Compared to those in the control group (untreated), Ti particles and TNF-alpha increased the gene expression of MMP-1, 2, 3 respectively (P < 0.05), and the effect of combination of the two was even more significant (P < 0.01). The trend of activities of MMP-2 is similar with gene expression. Ti particles and TNF-alpha increased MMP-2 activities by 1.3 times and 1.5 times respectively (P < 0.05), and the combination of the two increased by 1.7 times (P < 0.01). Ti particles and TNF-alpha-induced the stimulation of MMP-1, 2, 3 expressions and MMP-2 activities in human knee joint synovial cells may be involved in aseptic loosening after metal-on-metal arthroplasty through increasing the degradation of bone matrix and declining of osseous support structure mechanics. PMID:24459964

Fu, Chunfeng; Xie, Jing; Chen, Rongfu; Wang, Chunli; Xu, Chunming; Chen, Cheng; Wang, Zhiqiang; Lin, Liangbo; Huang, Wei; Liang, Xi; Sung, K L Paul

2013-10-01

321

Enhancement of particle-wave energy exchange by resonance sweeping  

SciTech Connect

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.

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

1996-01-01

322

Enhancement of particle-wave energy exchange by resonance sweeping  

SciTech Connect

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.

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

1995-10-01

323

Zero Energy Bound States in Many--Particle Systems  

E-print Network

It is proved that the eigenvalues in the N--particle system are absorbed at zero energy threshold, if none of the subsystems has a bound state with $E \\leq 0$ and none of the particle pairs has a zero energy resonance. The pair potentials are allowed to take both signs.

Dmitry K. Gridnev

2011-12-01

324

Elastic and Inelastic-Scattering of Alpha-Particles from Ba-138  

E-print Network

PHYSI CA L R EVI EW C VOLUME 6, NUMBER 5 NOVEMB ER 1972 138Elastic and Inelastic Scattering of n Particles from Ba J. H. Barker* and J. C. Hiebert Texas A & M University, College Station, Texas 77843 (Received 8 June 1972) Differential cross... and an opti- cal-model calculation based on an optical potential of the form, II. DESCRIPTION OF EXPERIMENT Most of the experimental techniques have been described in the earlier paper. ' A beam of 49.6 +0.3-MeV u particles was scattered from "Ba U...

Barker, J. H.; Hiebert, John C.

1972-01-01

325

Coincidence measurements between alpha particles and gamma rays in reactions induced by 85 and 155 MeV ¹²C on ¹??Sm  

E-print Network

COINCIDENCE MEASUREMENTS BETWEEN ALPHA PARTICLES AND GAMMA RAYS 12 154 IN REACTIONS INDUCED BY 85 AND 155 MEV C ON Sm A Thesis by STEVEN EDWARD CALA Submitted to the Graduate College of Texas A&M University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE August 1978 Major Subject: Chemistry COINCIDENCE MEASUREMENTS BETWEEN ALPHA PARTICLES AND GAMMA RAYS 12 154 IN REACTIONS INDUCED BY 85 AND 155 MEV C ON Sm A Thesis by STEVEN EDWARD CALA Approved...

Cala, Steven Edward

1978-01-01

326

Quantum design using a multiple internal reflections method in a study of fusion processes in the capture of alpha-particles by nuclei  

E-print Network

A high precision method to determine fusion in the capture of $\\alpha$-particles by nuclei is presented. For $\\alpha$-capture by $^{40}{\\rm Ca}$ and $^{44}{\\rm Ca}$, such an approach gives (1) the parameters of the $\\alpha$--nucleus potential and (2) fusion probabilities. This method found new parametrization and fusion probabilities and decreased the error by $41.72$ times for $\\alpha + ^{40}{\\rm Ca}$ and $34.06$ times for $\\alpha + ^{44}{\\rm Ca}$ in a description of experimental data in comparison with existing results. We show that the sharp angular momentum cutoff proposed by Glas and Mosel is a rough approximation, Wong's formula and the Hill-Wheeler approach determine the penetrability of the barrier without a correct consideration of the barrier shape, and the WKB approach gives reduced fusion probabilities. Based on our fusion probability formula, we explain the difference between experimental cross-sections for $\\alpha + ^{40}{\\rm Ca}$ and $\\alpha + ^{44}{\\rm Ca}$, which is connected with the theory of coexistence of the spherical and deformed shapes in the ground state for nuclei near the neutron magic shell $N=20$. To provide deeper insight into the physics of nuclei with the new magic number $N=26$, the cross-section for $\\alpha + ^{46}{\\rm Ca}$ is predicted for future experimental tests. The role of nuclear deformations in calculations of the fusion probabilities is analyzed.

Sergei P. Maydanyuk; Peng-Ming Zhang; Sergei V. Belchikov

2015-04-02

327

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

328

Emission of alpha particles during the spontaneous fission of {sup 244}Pu  

SciTech Connect

We have measured the light charged particle (LCP) emission probabililty for the spontaneous fission of {sup 244}Pu. For the LCP emission to binary fission probability ratio a value of (2.96{plus_minus}0.31){times}10{sup {minus}3} was found. This result is in agreement with the previously observed trends concerning the LCP emission probability.

Verboven, M.; Jacobs, E.; De Frenne, D.; Thierens, H.; D`hondt, P. [Nuclear Physics Laboratory, Proeftuinstraat 86, B-9000 Gent (Belgium)] [Nuclear Physics Laboratory, Proeftuinstraat 86, B-9000 Gent (Belgium)

1994-03-01

329

Effect of particle size on hydroxyapatite crystal-induced tumor necrosis factor alpha secretion by macrophages  

Microsoft Academic Search

Macrophages may promote a vicious cycle of inflammation and calcification in the vessel wall by ingesting neointimal calcific deposits (predominantly hydroxyapatite) and secreting tumor necrosis factor (TNF)?, itself a vascular calcifying agent. Here we have investigated whether particle size affects the proinflammatory potential of hydroxyapatite crystals in vitro and whether the nuclear factor (NF)-?B pathway plays a role in the

Imad Nadra; Aldo R. Boccaccini; Pandelis Philippidis; Linda C. Whelan; Geraldine M. McCarthy; Dorian O. Haskard; R. Clive Landis

2008-01-01

330

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

SciTech Connect

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.

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

2015-01-01

331

Double-electron capture in collision of fast alpha particles with helium atoms  

NASA Astrophysics Data System (ADS)

A four-body boundary-corrected first-order Jackson-Schiff approximation (JS1-4B) is developed to calculate the differential and integral cross-sections (DCSs) for double-electron exchange in collision of fast alpha ions with helium atoms in their ground states. The influence of the static electron correlations on cross-sections is taken into account through choosing the different wave functions to describe the initial and final bound states of the electrons. The quantum-mechanical post and prior transition amplitudes for double charge exchange are derived in terms of two-dimensional real integrals which can be calculated numerically. The validity and utility of the applied approach is critically assessed in comparison with the available experimental data for differential and integral cross-sections. The present calculations are also compared with the results obtained from the other theories.

Ghanbari-Adivi, Ebrahim; Ghavaminia, Hoda

2014-11-01

332

(n,{alpha}) Reaction studies using a gridded ionization chamber  

SciTech Connect

An {alpha}-spectrometer with a large solid angle has been developed for complex studies of fast neutron induced {alpha}-particle emission reactions. The set-up is based on high-pressure Frisch-gridded ionization chamber employing high-Z structural elements to suppress charge particle background. The spectrometer permits the measurements of energy-angular correlations for {alpha}-particles corresponding to different channels of reaction. Experimental data recently obtained for {sup 58}Ni(n,{alpha}){sup 55}Fe reaction are used for presentation of gridded chamber capabilities.

Goverdovski, A.A.; Khryachkov, V.A.; Ketlerov, V.V.; Mitrofanov, V.F. [Institute of Physics and Power Engineering, Obninsk (Russian Federation); Vonach, H. [Institute fur Radiumforschung Kernphysik, Vienna (Austria); Haight, R.C. [Los Alamos National Lab., NM (United States)

1994-12-31

333

Long-range alpha detector (LRAD)  

SciTech Connect

Historically, alpha detectors have been limited by the very short range of alpha particles in air and by relatively poor sensitivity, even if the particles are intercepted. Of necessity, these detectors are operated in a vacuum or in close proximity to the source if reasonable efficiency is desired. In our new long-range alpha detector (LRAD), alpha particles interact with the ambient air, producing ionization in the air at the rate of about 30,000 ion pairs per MeV of alpha energy. These charges can be transported over significant distances (several meters) in a moving current of air generated by a small fan. An ion chamber located in front of the fan measures the current carried by the moving ions. The LRAD-based monitor is more sensitive and more thorough than conventional monitors. We present current LRAD sensitivity limits and results, practical monitor designs, and proposed uses for LRAD monitors. 4 refs., 7 figs.

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

1991-01-01

334

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

PubMed Central

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

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

1996-01-01

335

Neutron skin thickness of heavy nuclei with $?$-particle correlations and the slope of the nuclear symmetry energy  

E-print Network

The formation of $\\alpha$-particle clusters on the surface of heavy nuclei is described in a generalized relativistic mean-field model with explicit cluster degrees of freedom. The effects on the size of the neutron skin of Sn nuclei and ${}^{208}$Pb are investigated as a function of the mass number and the isospin-dependent part of the effective interaction, respectively. The correlation of the neutron skin thickness with the difference of the neutron and proton numbers and with the slope of the nuclear symmetry energy is modified as compared to the mean-field calculation without alpha-cluster correlations.

Stefan Typel

2014-06-16

336

GROSS ALPHA RADIUM REGULATION  

EPA Science Inventory

The determination of concentrations of natural radioactivity in public water supplies begins with the measurement of the gross alpha particle activity. The gross alpha activity measurement is used as a screening technique. The gross alpha particle activity measurement may be su...

337

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

338

Study of an alpha track analysis and a fission track analysis for determining the hot particles contaminated with Pu and U isotopes.  

PubMed

A fission track analysis and alpha track analysis were developed to detect fissile particles such as uranium and plutonium isotopes as well as to identify particle-bound plutonium in contaminated soil or sediment. To record a reference point, a locator SEM grid electroplated with boron was used to obtain a recorded grid image on the Lexan or CR-39 detector. With the fission track technique, the track images of the grid coated with boron and the fissile nuclides on the CR-39 detector were clearly recorded so that the location of the fissile particles could be easily identified in the radio-contaminated soil matrix. With the alpha track technique, many of the hot particles in the BOMARC soil turned out to be contaminated with plutonium isotopes rather than uranium isotopes. PMID:16934476

Lee, M H; Park, Y J; Jee, K Y; Kim, W H; Clark, Sue B

2007-01-01

339

Orientational energy of anisometric particles in liquid-crystalline suspensions  

NASA Astrophysics Data System (ADS)

We obtain a general expression for the orientational energy of an individual anisometric particle suspended in uniform nematic liquid crystals when the main axis of the particle rotates with respect to the nematic director. We show that there is a qualitative and quantitative analogy between the internal and external problems for cylindrical volumes of nematic liquid crystals, and on this basis we obtain an estimate of the orientational energy of a particle of cylindrical (rodlike, needlelike, or ellipsoidal) shape. For an ensemble of such particles we propose a modified form of their orientational energy in the nematic matrix. This orientational energy has the usual second-order term, and additional fourth-order term in the scalar product of the nematic director and the vector which characterizes an average direction of the main axes of the particles. As an example we obtain the expression for the free energy density of ferronematics, i.e., colloidal suspensions of needlelike magnetic particles in nematic liquid crystals. Unlike previous models, the free energy density includes the proposed modified form of the particle orientational energy, and also a contribution describing the surface saddle-splay deformations of the liquid crystal matrix.

Burylov, S. V.; Zakhlevnykh, A. N.

2013-07-01

340

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

PubMed Central

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

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

2013-01-01

341

Quantum design using a multiple internal reflections method in a study of fusion processes in the capture of alpha-particles by nuclei  

E-print Network

A high precision method to determine fusion in the capture of $\\alpha$-particles by nuclei is presented. For $\\alpha$-capture by $^{40}{\\rm Ca}$ and $^{44}{\\rm Ca}$, such an approach gives (1) the parameters of the $\\alpha$--nucleus potential and (2) fusion probabilities. This method found new parametrization and fusion probabilities and decreased the error by $41.72$ times for $\\alpha + ^{40}{\\rm Ca}$ and $34.06$ times for $\\alpha + ^{44}{\\rm Ca}$ in a description of experimental data in comparison with existing results. We show that the sharp angular momentum cutoff proposed by Glas and Mosel is a rough approximation, Wong's formula and the Hill-Wheeler approach determine the penetrability of the barrier without a correct consideration of the barrier shape, and the WKB approach gives reduced fusion probabilities. Based on our fusion probability formula, we explain the difference between experimental cross-sections for $\\alpha + ^{40}{\\rm Ca}$ and $\\alpha + ^{44}{\\rm Ca}$, which is connected with the theory ...

Maydanyuk, Sergei P; Belchikov, Sergei V

2015-01-01

342

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

NASA Astrophysics Data System (ADS)

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 astronomy—that 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

Ong, Rene A.; Covault, Corbin E.

2009-05-01

343

Determination of plutonium isotopes in bilberry using liquid scintillation spectrometry and alpha-particle spectrometry.  

PubMed

This paper presents ?-particle spectrometry and liquid scintillation spectrometry methods to determine plutonium isotopes in bilberry. The analytical procedure involves sample preparation steps for ashing, digestion of bilberry samples, radiochemical separation of plutonium radioisotopes and their measurement. The validity of the method was checked for coherence using the ? test, z-test, relative bias and relative uncertainty outlier tests. The results indicated that the recommended procedures for both measurement systems could be successfully applied for the accurate determination of plutonium activities in bilberry samples. PMID:24359792

Seferino?lu, Meryem; Aslan, Nazife; Kurt, Aylin; Erden, P?nar Esra; Mert, Hülya

2014-05-01

344

Semiconductor polycrystalline alpha detectors  

NASA Astrophysics Data System (ADS)

In order to check possible novel neutron detectors based on composite semiconductor detectors containing nuclides with large cross sections for neutron, we tested their response to alpha particles. In the present paper we describe results obtained with composite samples made of hexagonal Boron Nitride particles bound with Polystyrene or Nylon-6. The samples were tested under 5.5 MeV alpha particle radiation emitted from 241Am source and 4.8MeV alpha particle of 226Ra source. Some of the responses of these composite detectors to thermal neutrons were already reported and here we shall show some newer results obtained with thermal neutrons, from a low intensity 241Am - 9Be and also from a medium intensity 252Cf source, which were thermalized using 10 cm thick paraffin. The Alpha detection experiments show that all the tested samples, regardless of the binder, show a well-defined peak around the 270 energy channel. There was very little polarization of the alpha radiation, since the amplitude of the alpha peak is reduced after ~ 2min from start of the irradiation, from 100% to 95% and it stayed stable at this level for another 10 minutes. The alpha spectrum detected from a PbI II single crystal is also shown for comparison. The neutron spectrum obtained by the composite BN samples showed an apparent peak around the 150 energy channel. The Signal to noise ratio for neutron detection from radionuclide shown here is about 2 only, whereas recent results to be published later, obtained with our composite BN detectors from a neutron beam of about 10 7 sec -1cm -2 is ~2 5. The 1.4 and 1.7 MeV alpha peaks resulting from the nuclear reaction of thermal neutrons with 10B of the boron nitride detector are not buried in the noise range. The capacitance noise requires small contact areas, therefore for large area detectors it is necessary to produce an electronic read-out device which can add up a multitude of small (less than 10sq.mm) pixilated contacts.

Schieber, M.; Roth, M.; Zuck, A.; Marom, G.; Khakhan, O.; Alfassi, Z. B.

2006-08-01

345

Ultra High Energy Cosmic Rays from Decaying Superheavy Particles  

E-print Network

Decaying superheavy particles can be produced by Topological Defects or, in case they are quasi-stable, as relics from the early Universe. The decays of these particles can be the sources of observed Ultra High Energy Cosmic Rays ($E \\sim 10^{10} - 10^{12} GeV$). The Topological Defects as the UHE CR sources are critically reviewed and cosmic necklaces and monopole-antiminopole pairs are identified as most plausible sources. The relic superheavy particles are shown to be clustering in the halo and their decays produce UHE CR without GZK cutoff. The Lightest Supersymmetric Particles with Ultra High Energies are naturally produced in the cascades accompanying the decays of superheavy particles. These particles are discussed as UHE carriers in the Universe.

V. Berezinsky

1998-01-08

346

Alpha-particle transfer from 6Li to 28Si leading to high excitation of 32S  

NASA Astrophysics Data System (ADS)

The excitation of 32S to energies from 24 to 37 MeV followed by its decay to 28Si has been brought about by the two-step alpha transfer reaction 28Si(6Li,d)32S*??+28Si. A sudden perishing of the decay to the 28Si ground state occurs at 31 MeV of excitation. At about the same energy an increase in the decay to the first excited 2+ state is observed. The yields of 28Si in its ground state or excited to the 21+ and 41+ state prohibit strong fluctuations. This supports the assumption of the existence of states at high excitation in 32S. The results are based on d-? coincidences, which were found to exhibit a strong forward-backward correlation.

Brenner, M.; Lattuada, M.; Gulino, M.; Khlebnikov, S. V.; Chengbo, Li; Prete, G.; Trzaska, W. H.; Zadro, M.; Belov, S. E.

2006-12-01

347

A Method of Measuring Hydrogen Isotopes in Surface Layers of Planetary Soils by Spectroscopy of Recoil Protons in Alpha Particle Elastic Scattering  

Microsoft Academic Search

A theoretical and experimental feasibility study of possible determination of the hydrogen and deuterium concentrations in the surface layers of planetary bodies is presented. The method under study is the recoil proton and deuteron spectrometry of forward scattering in the course of elastic interaction of alpha particles with the nuclei of hydrogen isotopes. The spectra of recoil protons and deuterons

B. N. Korchuganov; G. G. Dol'nikov; M. V. Gerasimov; O. F. Prilutskii; R. Rider; G. Waenke; T. Economou

2004-01-01

348

Quantum Information, Entropy, ALPHA, Hubble Time, and Dark Energy, Linked?  

NASA Astrophysics Data System (ADS)

The postulation of fundamental constants by Newton, Einstein and Planck gave us natural units at Planck scale. Additional postulates may explain coupling constants. About sixty orders of magnitude of Planck times equal Hubble time (W). Substitution of W in Boltzmann's entropy equation (S=k ln W; with Boltzmann constant k = 1 in natural units, and using the natural logarithm to probe nature) equates the statistical entropy (S) of the universe to about 137, the reciprocal of the fine-structure constant (?). Thermodynamic entropy (dS = ?Q/T), a consequence of statistical entropy, implies that the fine-structure constant generates heat out of vacuum energy or dark energy. We draw support from the insights of Maxwell's demon (1867), Gamow (1967) and Eddington (1949). In information theory, entropy is linked to a measure of uncertainty, indicating that the fine-structure constant is greater than or equal to the reciprocal of the natural logarithm of the age of the universe: ?>=1 / 1 lnW . - lnW. The postulation in [1] (a draft of a 2008 planned review paper) will address further issues. [1] S. Goradia, What is Fine Structure Constant? http://www.arxiv.org/abs/physics/0210040v3 (revised 1/6/2007)

Goradia, Shantilal

2008-03-01

349

Dual coherent particle emission as generalised Cherenkov-like effect in high energy particle collisions  

E-print Network

In this paper we introduce a new kind of nuclear/hadronic coherent particle production mechanism in high-energy collisions called \\emph{dual coherent particle emission (DCPE)} which takes place when the phase velocities of the emitted particle v_{Mph} and that of particle source v_{B_1ph} satisfy the dual coherence condition: v_{Mph} <= v_{B_1ph}^-1. The general signatures of the DCPE in the nuclear and hadronic media are established and some experimental evidences are given.

D. B. Ion; E. K. Sarkisyan

2002-09-04

350

The problem of low energy particle measurements in the magnetosphere  

NASA Technical Reports Server (NTRS)

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.

Whipple, E. C., Jr.

1978-01-01

351

Inelastic Alpha Scattering Studies of Low-Energy Octupole Resonance  

E-print Network

argument; there the domi- nant configuration is (2d, 12 ', Ih~~~~)", -. Unfortu- 748 MOSS, BR 0%'N, YOU NGBLOOD, ROZSA, AND BRONSON Nucleus Eexc (MeV) G, (EM) (SPU) 40ea 40Zr '"Sn 2 oBPb 3.73 2.75 2.28 2.6 1 18.6 +3 13.4 + 2 17 +3 36 +5 31...-energy octupole resonance in ' Sm account qualitatively for the data. NUCLEAR REACTIONS +Ca, 66Zn, As, ~Y, 9 Zr, ~ Mo, OMo, Ag. (nat), ii6Sn 118Sn i2 Sn i42Nd i44Sm i48Sm i54Sm i%Au 20spb(~ ~i) E ?g6 MeV measured E?, 0(B) giant resonances, deduced l, P. I...

Moss, JM; Brown, D. R.; Youngblood, David H.; Rozsa, C. M.; Bronson, J. D.

1978-01-01

352

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

PubMed Central

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

Vaidyanathan, Ganesan; Zalutsky, Michael R.

2012-01-01

353

Alpha-Driven Currents in Tokamak Reactors.  

NASA Astrophysics Data System (ADS)

The generation of a net toroidal plasma current in tokamak reactors by interaction of an input magnetosonic wave with the fusion product alpha particles is examined. The wave transfers momentum to the alpha particles by Landau damping and transit time damping and thereby modifies the alpha particle velocity distribution function in an anisotropic manner. The change in the alpha particle distribution function and the resulting toroidal current density and wave energy absorption is calculated for several assumed alpha particle velocity distribution functions. A Gaussian velocity distribution function to model a spread in the alpha particle birth energy due to kinematic effects as well as speed diffusion from collisions with the background plasma is evaluated and found to give identical results as a monoenergetic delta function velocity distribution in the proper limits. The physical processes producing the Gaussian distribution are shown to be small. A more realistic calculation with an alpha particle velocity distribution functions based on a Fokker-Planck model of slowing down against the background electrons is performed and numerical estimates obtained for a reference tokamak reactor design. It is shown, for the assumed parallel wave vector spectrum, that the transit time damping is the dominant process and that interaction of the wave with background electrons can be neglected. The efficiency of the process is found to be comparable to that of lower hybrid current drive and approaches values of 0.15 A/W at high electron temperatures. The magnitude of the induced current is found to be significantly less than that required for plasma confinement and equilibrium, although anomalously large values of the parallel wave magnetic field could produce the design current. Issues such as wave accessibility, absorption, and mode conversion are also examined and found to be favorable for the assumed wave frequency of about four times the cyclotron frequency of deuterium and parallel wave vectors constrained for resonance with the 3.52-MeV alpha particles.

Gouge, Michael Joseph

354

Charged particle rapidity distributions at relativistic energies  

E-print Network

. The theoretical results for the total charged particle multiplicity at midrapidity are consistent with those measured by the PHOBOS Collaboration in central Au+Au collisions at roots = 56 and 130A GeV. We find that these hadronic observables are much more...

Lin, ZW; Pal, S.; Ko, Che Ming; Li, Ba; Zhang, B.

2001-01-01

355

Microdosimetric characterization of energy-deposition patterns near the ends of alpha tracks  

E-print Network

substantial fluctuation in the damage done within small regions when they are crossed by charged particles. For small sites, corresponding to short track segments, the change of LET can be ignored and energy-loss straggling predominates. Past studies have...

Guetersloh, Stephen Brant

2000-01-01

356

Alpha cluster structure in 56Ni  

NASA Astrophysics Data System (ADS)

The inelastic ?-scattering experiment on 56Ni in inverse kinematics was performed at an incident energy of 50 MeV/u at GANIL. A very high multiplicity for ?-particle emission was observed with our phase-space limited experimental set-up. The maximum observed multiplicity, which cannot be explained by means of the statistical decay model, amounted to seven. The ideal classical gas model at kT = 3 MeV fairly well reproduced the experimental momentum distribution and multiplicity of alpha particles. This result strongly suggests that an alpha-gas state in 56Ni may be excited via inelastic alpha scattering.

Akimune, H.; Fujiwara, M.; Gibelin, J.; Harakeh, M. N.; Achouri, L.; Bagchi, S.; Bastin, B.; Boretzky, K.; Bouzomita, H.; Caceres, L.; Damoy, S.; Delaunay, F.; Fernández-Domínguez, B.; Caamano, M.; Garg, U.; Grinyer, G. F.; Kalantar-Nayestanaki, N.; Kamalou, O.; Khan, E.; Krasznahorkay, A.; Lhoutellier, G.; Lukyanov, S.; Mazurek, K.; Najafi, M.; Pancin, J.; Penionzkhevich, Y.; Perrot, L.; Raabe, R.; Rigollet, C. E.; Roger, T.; Sambi, S.; Savajols, H.; Senoville, M.; Stodel, C.; Suen, L.; Thomas, J. C.; van de Walle, J.; Vandebrouck, M.

2013-04-01

357

String black holes as particle accelerators to arbitrarily high energy  

NASA Astrophysics Data System (ADS)

We show that an extremal Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole may act as a particle accelerator with arbitrarily high energy when two uncharged particles falling freely from rest to infinity on the near horizon. We show that the center of mass energy of collision is independent of the extreme fine tuning of the angular momentum of the colliding particles. We further show that the center of mass energy of collisions of particles at the ISCO ( r ISCO ) or at the photon orbit ( r ph ) or at the marginally bound circular orbit ( r mb ) i.e. at r? r ISCO = r ph = r mb =2 M could be arbitrarily large for the aforementioned space-time, which is quite different from the Schwarzschild and the Reissner-Nordstrøm space-time. For non-extremal GMGHS space-time the CM energy is finite and depends upon the asymptotic value of the dilation field ( ? 0).

Pradhan, Parthapratim

2014-07-01

358

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

PubMed Central

A new multi-port irradiator, designed to facilitate the study of the effects of low fluences of ? particles on monolayer cultures, has been developed. The irradiator consists of four individual planar 241Am ?-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-?m-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 ? 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/?m. Clonogenic cell survival experiments with AG1522 human fibroblasts indicate that the RBE of the ? particles compared to 137Cs ? rays is about 7.6 for this biological end point. PMID:15161346

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

2011-01-01

359

Binding Energies and Radii of the Nuclei with N >=Z in an Alpha-Cluster Model  

E-print Network

Using the surface tension energy put in dependence on the number of alpha-clusters in the core in a phenomenological model representing a nucleus as a core and a nuclear molecule on its surface leads to widening the number of isotopes to be described from the narrow strip of beta-stability to the isotopes with N >= Z. The number of alpha-clusters in the molecule is obtained from the analysis of experimental binding energies and the specific density of the core binding energy \\rho and the radii are calculated. It is shown that for the isotopes of one Z with growing A the number of alpha-clusters of the molecule decreases mostly to 3 and \\rho increases to reach a saturation value within \\rho = 2.5 \\div 2.7 MeV/fm^3 at the beta - stable isotopes, so the narrow strip of the binding energies of the beta - stable isotopes with Z <= 84 is outlined by a function of one variable Z.

G. K. Nie

2008-07-01

360

Central Exclusive Particle Production at High Energy Hadron Colliders  

SciTech Connect

We review the subject of central exclusive particle production at high energy hadron colliders. In particular we consider reactions of the type A + B {yields} A + X + B, where X is a fully specified system of particles that is well separated in rapidity from the outgoing beam particles. We focus on the case where the colliding particles are strongly interacting and mainly they will be protons (or antiprotons) as at the ISR, Sp{bar p}S, Tevatron and LHC. The data are surveyed and placed within the context of theoretical developments.

Albrow, M.G.; /Fermilab; Coughlin, T.D.; /University Coll. London; Forshaw, J.R.; /Manchester U.

2010-06-01

361

Entrainment of coarse particles in turbulent flows: An energy approach  

NASA Astrophysics Data System (ADS)

The entrainment of coarse sediment particles under the action of fluctuating hydrodynamic forces is investigated from an energy perspective. It is demonstrated that the entrainment of a grain resting on the channel boundary is possible when the instantaneous flow power transferred to it exceeds a critical level. Its complete removal from the bed matrix occurs only if the impinging flow events supply sufficient mechanical energy. The energy-based criterion is formulated theoretically for entrainment of individual spherical particles in both saltation and rolling modes. Out of the wide range of flow events that can perform mechanical work on a coarse grain, only those with sufficient power and duration or equivalent energy density and characteristic length scale may accomplish its complete dislodgement. The instantaneous velocity upstream of a mobile particle is synchronously recorded with its position, enabling the identification of the flow events responsible for grain entrainment by rolling at near incipient motion flow conditions. For each of the entrainment events, the energy transfer coefficient defined as the ratio of the mechanical work performed on the particle to the mean energy of the flow event responsible for its dislodgement obtains values ranging from 0.04 to 0.10. At the examined low-mobility flow conditions, the majority (about 80%) of the energetic structures leading to complete particle entrainment have a characteristic length of about two to four particle diameters.

Valyrakis, Manousos; Diplas, Panayiotis; Dancey, Clint L.

2013-03-01

362

Experimental and Theoretical Study of Alpha Particle Induced Charge Collection in GaAs FETS  

Microsoft Academic Search

An experimental angular dependence study was made of charge collection in state-of-the-art GaAs FETs. Numerical simulations of the transport of electrons in the active channel and in the semi-insulating substrate were also carried out. It is concluded that charge collected by funneling from the substrate is not significant. Both energy loss in the source and drain metallizations and degradation of

W. T. Anderson; A. R. Knudson; F. A. Buot; H. L. Grubin; J. P. Kreskovsky; A. B. Campbell

1987-01-01

363

The use of CH3OH additive to NaOH for etching alpha particle tracks in a CR-39 plastic nuclear track detector  

NASA Astrophysics Data System (ADS)

Fast detection of alpha particles in CR-39 detectors was investigated using a new chemical etchant. 252Cf and 241Am sources were used for irradiating samples of CR-39 SSNTDs with fission fragments and alpha particles in air at normal temperature and pressure. A series of experimental chemical etching are carried out using new etching solution (8 ml of 10N NaOH+1 ml CH3OH) at 60 °C to detect alpha particle in short time in CR-39 detectors. Suitable analyzing software has been used to analyze experimental data. From fission and alpha track diameters, the value of bulk etching rate is equal to 2.73 ?m/h. Both the sensitivity and etching efficiency were found to vary with the amount of methanol in the etching solution. Pure NaOH was used as a control to compare with the result from etching in NaOH with different concentrations of CH3OH. The etching efficiency is determined and compared with conventional aqueous solution of 6.25N NaOH at 70 °C for etching time equals 5 h. In this study, the obtained etching efficiency shows a considerable agreement with the previous work.

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

2014-08-01

364

Studies on alpha-induced astrophysical reactions using the low-energy RI beam separator CRIB  

NASA Astrophysics Data System (ADS)

Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. Two major methods to study them are the ? resonant scattering, and direct measurements of (?,p) reactions using an active or inactive helium gas target. Among the recent studies at CRIB, the measurement of 7Be+? resonant scattering is discussed.

Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Kubono, S.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Iwasa, N.; Teranishi, T.; Kwon, Y. K.; Lee, P. S.; Binh, D. N.; Khiem, L. H.; Duy, N. G.

2014-03-01

365

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

SciTech Connect

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.

Nicolis, N.G.; Sarantites, D.G.; Abenante, V.; Adler, L.A.; Dilmanian, F.A.; Majka, Z.; Semkow, T.M.; Stracener, D.W. (Washington Univ., St. Louis, MO (USA). 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. (Oak Ridge National Lab., TN (USA)); Griffin, H.C. (Michigan Univ., Ann Arbor, MI (USA). Dep

1990-01-01

366

Characteristics and mechanisms of the bystander response in monolayer cell cultures exposed to very low fluences of alpha particles  

NASA Astrophysics Data System (ADS)

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.

Little, John B.; Azzam, Edouard I.; de Toledo, Sonia M.; Nagasawa, Hatsumi

2005-02-01

367

Particle size and interfacial effects on thermo-physical and heat transfer characteristics of water-based alpha-SiC nanofluids.  

PubMed

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. PMID:20431197

Timofeeva, Elena V; Smith, David S; Yu, Wenhua; France, David M; Singh, Dileep; Routbort, Jules L

2010-05-28

368

Open Problems in $?$ Particle Condensation  

E-print Network

$\\alpha$ particle condensation is a novel state in nuclear systems. We briefly review the present status on the study of $\\alpha$ particle condensation and address the open problems in this research field: $\\alpha$ particle condensation in heavier systems other than the Hoyle state, linear chain and $\\alpha$ particle rings, Hoyle-analogue states with extra neutrons, $\\alpha$ particle condensation related to astrophysics, etc.

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

2010-03-05

369

Particle mixing, flavor condensate and dark energy  

E-print Network

The mixing of neutrinos and quarks generate a vacuum condensate that, at the present epoch, behaves as a cosmological constant. The value of the dark energy is constrained today by the very small breaking of the Lorentz invariance.

Massimo Blasone; Antonio Capolupo; Giuseppe Vitiello

2009-12-08

370

Elementary particle physics and high energy phenomena  

SciTech Connect

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).

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

371

Alternative Discrete Energy Solutions to the Free Particle Dirac Equation  

E-print Network

The usual method of solving the free particle Dirac equation results in the so called continuum energy solutions. Here, we take a different approach and find a set of solutions with quantized energies which are proportional to the total angular momentum.

Thomas Edward Brennan

2013-11-15

372

Development of a bioluminescence resonance energy transfer (BRET) for monitoring estrogen receptor alpha activation  

NASA Astrophysics Data System (ADS)

Estrogen receptor (ER) is a ligand-activated transcriptional factor, able to dimerize after activation and to bind specific DNA sequences (estrogen response elements), thus activating gene target transcription. Since ER homo- and hetero-dimerization (giving a-a and a-b isoforms) is a fundamental step for receptor activation, we developed an assay for detecting compounds that induce human ERa homo-dimerization based on bioluminescence resonance energy transfer (BRET). BRET is a non-radiative energy transfer, occurring between a luminescent donor and a fluorescent acceptor, that strictly depends on the closeness between the two proteins and can therefore be used for studying protein-protein interactions. We cloned ERa coding sequence in frame with either a variant of the green fluorescent protein (enhanced yellow fluorescent protein, EYFP) or Renilla luciferase (RLuc). Upon ERa homo-dimerization, BRET process takes place in the presence of the RLuc substrate coelenterazine resulting in EYFP emission at its characteristic wavelength. The ER alpha-Rluc and ER alpha-EYFP fusion proteins were cloned, then the occurrence of BRET in the presence of ER alpha activators was assayed both in vivo, within cells, and in vitro, with purified fusion proteins.

Michelini, Elisa; Mirasoli, Mara; Karp, Matti; Virta, Marko; Roda, Aldo

2004-06-01

373

Energy related applications of elementary particle physics  

SciTech Connect

The current research position is summarized, and what could be done in the future to clarify issues which were opened up by the research is indicated. Following on the discussion of the viability of catalyzed fusion, there is presented along with the key experimental results, a short account of the physics surrounding the subject. This is followed by a discussion of key research topics addressed. In consequence of the progress made, it appears that the feasibility of a small-scale fusion based on catalyzed reactions rests on either the remote chance that a yet undiscovered ultraheavy negatively charged elementary particle exists in Nature, or on the possible technical realization of a system based on muon-catalyzed fusion (MuCF) in high-density degenerate hydrogen plasma (density 1000 LHD, temperature O(100 eV)). The lattter is considered to have practical promise.

Rafelski, J.

1991-08-31

374

(Medium energy particle physics): Annual progress report  

SciTech Connect

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.

Nefkens, B.M.K.

1985-10-01

375

PAMELA's Measurements of Magnetospheric Effects on High Energy Solar Particles  

E-print Network

The nature of particle acceleration at the Sun, whether through flare reconnection processes or through shocks driven by coronal mass ejections (CMEs), is still under scrutiny despite decades of research. The measured properties of solar energetic particles (SEPs) have long been modeled in different particle-acceleration scenarios. The challenge has been to disentangle to the effects of transport from those of acceleration. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instrument, enables unique observations of SEPs including composition and the angular distribution of the particles about the magnetic field, i.e. pitch angle distribution, over a broad energy range (>80 MeV) -- bridging a critical gap between space-based measurements and ground-based. We present high-energy SEP data from PAMELA acquired during the 2012 May 17 SEP event. These data exhibit differential anisotropies and thus transport features over the instrument rigidity range. SEP protons exhibit two dist...

Adriani, O; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Bravar, U; Bruno, A; Cafagna, F; Campana, D; Carbone, R; Carlson, P; Casolino, M; Castellini, G; Christian, E C; De Donato, C; de Nolfo, G A; De Santis, C; De Simone, N; Di Felice, V; Formato, V; Galper, A M; Karelin, A V; Koldashov, S V; Koldobskiy, S; Krutkov, S Y; Kvashnin, A N; Lee, M; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Mergé, M; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Panico, B; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Ryan, J M; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stochaj, S; Stozhkov, Y I; Thakur, N; Vacchi, A; Vannuccini, E; Vasilyev, G I; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N

2015-01-01

376

Effect of alpha-irradiation of energy 0.5 MeV on the hydrogen bonding in a-Si : H thin films  

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous silicon thin films (a-Si:H) have been prepared by the rf glow discharge technique. The configuration of bonded hydrogen was investigated by infrared absorption measurements of Si:H vibrational modes before and after bombardment with an alpha-particle beam energy of 125 keV/n. The results showed an increase in the absorption mode near 2100, 890 and 850 cm(-1) and a decrease in the absorption mode near 2000 cm(-1) after bombardment. These observations are interpreted in terms of changes of the oscillator strengths of vibrational modes.

Abo-Ghazala, M. S.; Al-Hazmi, S.; Awad, E. M.

2004-07-01

377

Particles and energy fluxes from a conformal field theory perspective  

SciTech Connect

We analyze the creation of particles in two dimensions under the action of conformal transformations. We focus our attention on Mobius transformations and compare the usual approach, based on the Bogoliubov coefficients, with an alternative but equivalent viewpoint based on correlation functions. In the latter approach the absence of particle production under full Mobius transformations is manifest. Moreover, we give examples, using the moving-mirror analogy, to illustrate the close relation between the production of quanta and energy.

Fabbri, A. [Dipartimento di Fisica dell'Universita di Bologna and INFN sezione di Bologna, Via Irnerio 46, 40126 Bologna (Italy); GReCO, Institut d'Astrophysique de Paris, CNRS, 98bis Boul. Arago, 75014 Paris (France); Navarro-Salas, J.; Olmo, G.J. [Departamento de Fisica Teorica IFIC, Centro Mixto Universidad de Valencia-CSIC and Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia (Spain)

2004-09-15

378

Using energy peaks to measure new particle masses  

NASA Astrophysics Data System (ADS)

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.

Agashe, Kaustubh; Franceschini, Roberto; Kim, Doojin

2014-11-01

379

Particles and energy fluxes from a conformal field theory perspective  

NASA Astrophysics Data System (ADS)

We analyze the creation of particles in two dimensions under the action of conformal transformations. We focus our attention on Mobius transformations and compare the usual approach, based on the Bogoliubov coefficients, with an alternative but equivalent viewpoint based on correlation functions. In the latter approach the absence of particle production under full Mobius transformations is manifest. Moreover, we give examples, using the moving-mirror analogy, to illustrate the close relation between the production of quanta and energy.

Fabbri, A.; Navarro-Salas, J.; Olmo, G. J.

2004-09-01

380

Using Energy Peaks to Measure New Particle Masses  

E-print Network

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, without 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 by combinatorial issues as compared to other mass measurement strategies. 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.

Kaustubh Agashe; Roberto Franceschini; Doojin Kim

2014-11-14

381

The Compton-Getting effect for low energy particles  

NASA Technical Reports Server (NTRS)

The traditional first-order Compton-Getting effect, which relates particle distributions as observed in two frames of reference moving with constant relative velocity, is inadequate for the description of low-energy particles (less than a few hundred keV/nucleon) in the solar system. An exact procedure is given for recovering both isotropic and anisotropic distributions in the solar wind frame from observations made in a spacecraft frame. The method is illustrated by analyzing a particle event observed by an experiment on IMP-7 on Oct. 31, 1972.

Ipavich, F. M.

1974-01-01

382

The Compton-Getting effect for low energy particles  

NASA Technical Reports Server (NTRS)

It was found that the traditional first-order Compton-Getting effect, which relates particle distributions as observed in two frames of reference moving with constant relative velocity, is inadequate for the description of low energy particles (less than a few hundred keV/nucleon) in the solar system. An exact procedure is given for recovering both isotropic and anisotropic distributions in the solar wind frame from observations made in a spacecraft frame. The method was illustrated by analyzing a particle event observed on IPM-7.

Ipavich, F. M.

1974-01-01

383

A random walk approach to anomalous particle and energy transport  

E-print Network

The combined Continuous Time Random Walk (CTRW) in position and momentum space is introduced, in the form of two coupled integral equations that describe the evolution of the probability distribution for finding a particle at a certain position and with a certain momentum as a function of time. The integral equations are solved numerically with a pseudospectral method that is based on the expansion of the unknown functions in terms of Chebyshev polynomials. In parallel, Monte-Carlo simulation are performed. Through the inclusion of momentum space, the combined CTRW is able to yield results on density and temperature profile evolution, on particle and heat fluxes and diffusivities, and on kinetic energy distributions. Depending on the choice of the probability distributions of the particle displacements in position and momentum space, the combined CTRW is able to model phenomena of anomalous transport in position as well as in momentum (or energy or velocity) space. An application is made to a toroidally confined plasma that undergoes off-center injection of cold plasma (off-axis fueling), using two variants of the model, the mixed model and the critical gradient model. The phenomenon of profile stiffness is addressed, both for the density and for the temperature profile, respectively, and the particle and energy confinement times are determined. The analysis of the particle and heat fluxes shows that the dynamics realized in the combined CTRW is incompatible with the classical approach of Fick's or Fourier's law for particle and heat transport, respectively.

H. Isliker

2007-10-26

384

Study on the evolution and nature of interstitial-type defects following proton and alpha particle implantation during low-dose proximity gettering of platinum  

Microsoft Academic Search

Platinum has been diffused into epitaxial n-type silicon at 600°C, 650°C and 700°C for 30 min following implantation with 3.3 MeV alpha particles. The doses employed were between 1×1011 and 1×1014 He+ cm?2. Also an implantation involving protons at 850 keV with doses of 5×1013 and 5×1014 H+ cm?2 has been performed followed by an annealing at 600°C or 700°C.

D. C Schmidt; B. G Svensson; J. F Barbot; C Blanchard

1999-01-01

385

L-shell ionisation of medium and heavy elements by 1.2-3.0 MeV incident alpha particles  

Microsoft Academic Search

Thin targets of Yb, W, Au, Pb and Bi were bombarded by 1.2-03.0 MeV alpha particles. From the resulting L X-rays, experimental Li-subshell ionization cross sections were deduced. The measured cross sections are compared with the predictions of the ECPSSR theory by expressing the data in terms of ratios of experimental to theoretical values as a function of the corrected

R. S. Sokhi; D. Crumpton

1985-01-01

386

L-subshell ionisation of 71Lu, 73Ta and 79Au by 1.5-4.5 MeV alpha particles  

Microsoft Academic Search

The L X-rays of 71Lu, 73Ta and 79Au were produced by 1.5-4.5 MeV alpha particle bombardment. The emitted Lalpha, Lgamma1 and Lgamma2,3 lines were selected to convert X-ray production cross sections into ionisation cross sections. The ionisation cross sections obtained were compared with the predictions of the ECPSSR theory. A reasonable agreement of L3-subshell ionisation cross sections between the present

X. Cai; Z. Y. Liu; X. M. Chen; S. X. Ma; Z. C. Chen; Q. Xu; H. P. Liu; X. W. Ma

1992-01-01

387

Systematic study of the L-subshell ionization cross sections of Ho, Er, and Tm by MeV alpha-particle bombardments  

Microsoft Academic Search

The experimental L-subshell ionization cross sections, induced by MeV alpha particle bombardments, of Ho, Er, and Tm are compared with the ECPSSR theory. The general tendencies show systematic discrepancies for the three subshells. To account for the effects of induced intrashell transitions, the coupled state model is incorporated within the ECPSSR calculations, thus yielding the ECPSSR-IS. Systematic discrepancies between the

B. A. Shehadeh; A. B. Hallak

1999-01-01

388

Cumulative genetic damage in hematopoietic stem cells in a patient with a 40-year exposure to alpha particles emitted by thorium dioxide.  

PubMed

Thorotrast, a colloidal suspension of the long-lived radionuclide, thorium-232, was widely used as a radiographic contrast medium for several decades. Due to the poor excretion of the sol, however, Thorotrast would deposit in the liver, bone marrow and other tissue, and patients would receive alpha-particle irradiation for life. To gauge the cumulative genetic damage to hematopoietic stem cells due to chronic exposure to alpha particles, we conducted a multi-end-point evaluation in a 72-year-old man who had been administered a 32-ml bolus of Thorotrast during cerebral angiography performed over 40 years ago in 1950. Peripheral T lymphocytes were cultured to quantify the frequencies and cellular distributions of asymmetrical and symmetrical types of chromosome aberrations in first-division metaphases and micronuclei in cytokinesis-arrested interphase II cells. Aberrations were scored using classical chromosome group analysis methods and chromosome painting techniques. Assays of glycophorin-A (GPA) mutations in red blood cells were also performed to obtain a relative measurement of damage sustained by the erythroid stem cell population. Results revealed that approximately 30% of the lymphocytes in this patient contained one or more chromosome aberrations, the majority of which were of the "stable" type. About one-third of the lymphocytes with chromosome damage carried multiple aberrations, suggesting that significant numbers of stem cells survive exposures to alpha-particle radiation that induce complex genomic alterations. Increased frequencies of GPA mutations were observed, demonstrating that genomic damage is also induced in erythroid progenitors. The numbers of micronuclei in lymphocytes were only moderately increased compared to expected values for persons of comparable age, and thus this end point was not useful for quantifying exposure level. Despite the relatively severe burden of somatic cell damage induced by 40 years of internal alpha-particle irradiation, the patient remains surprisingly free of any serious illness. PMID:9254732

Littlefield, L G; Travis, L B; Sayer, A M; Voelz, G L; Jensen, R H; Boice, J D

1997-08-01

389

Energy States of Colored Particle in a Chromomagnetic Field  

E-print Network

The unitary transformation, which diagonalizes squared Dirac equation in a constant chromomagnetic field is found. Applying this transformation, we find the eigenfunctions of diagonalized Hamiltonian, that describe the states with definite value of energy and call them energy states. It is pointed out that, the energy states are determined by the color interaction term of the particle with the background chromofield and this term is responsible for the splitting of the energy spectrum. We construct supercharge operators for the diagonal Hamiltonian, that ensure the superpartner property of the energy states.

Sh. Mamedov

2006-11-24

390

Charged-particle multiplicity at LHC energies  

SciTech Connect

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. 

None

2010-04-07

391

Charged-particle multiplicity at LHC energies  

ScienceCinema

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. 

None

2011-10-06

392

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

SciTech Connect

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.

Caryl Gronwall

2012-12-03

393

The Pierre Auger Observatory: results on the highest energy particles  

E-print Network

The Pierre Auger Observatory has been designed to investigate the most energetic particles known, the ultra high energy cosmic rays. The observatory, covering an area of 3000 km^2, combines two different detection techniques to study the huge particle showers created by the interaction of primary cosmic rays with the atmosphere. The analysis of the showers allows one to extract information on the nature of the primary cosmic rays, as well as their origin. Moreover, the study of the interaction of these particles with the atmosphere offers a unique window to study particle physics at an energy more than one order of magnitude above the current highest energy human-made accelerator. In this contribution selected results are presented, with a focus on the primary mass composition, the determination of the number of muons, which is sensitive to the shower hadronic interactions, and the measurement of the proton-air cross-section at sqrt(s) = 57 TeV. For the last topic, a link with the proton-proton cross-section measurements using accelerators will be made. Results on the cosmic ray energy spectrum and on searches for ultra high energy photons and neutrinos, will also be discussed.

Ruben Conceição; for the Pierre Auger Collaboration

2013-07-15

394

Benchmarking the Geant4 full system simulation of an associated alpha-particle detector for use in a D-T neutron generator.  

PubMed

The position-sensitive alpha-particle detector used to provide the starting time and initial direction of D-T neutrons in a fast-neutron imaging system was simulated with a Geant4-based Monte Carlo program. The whole detector system, which consists of a YAP:Ce scintillator, a fiber-optic faceplate, a light guide, and a position-sensitive photo-multiplier tube (PSPMT), was modeled, starting with incident D-T alphas. The scintillation photons, whose starting time follows the distribution of a scintillation decay curve, were produced and emitted uniformly into a solid angle of 4? along the track segments of the alpha and its secondaries. Through tracking all photons and taking into account the quantum efficiency of the photocathode, the number of photoelectrons and their time and position distributions were obtained. Using a four-corner data reconstruction formula, the flood images of the alpha detector with and without optical grease between the YAP scintillator and the fiber-optic faceplate were obtained, which show agreement with the experimental results. The reconstructed position uncertainties of incident alpha particles for both cases are 1.198 mm and 0.998 mm respectively across the sensitive area of the detector. Simulation results also show that comparing with other faceplates composed of 500 ?m, 300 ?m, and 100 ?m fibers, the 10-?m-fiber faceplate is the best choice to build the detector for better position performance. In addition, the study of the background originating inside the D-T generator suggests that for 500-?m-thick YAP:Ce coated with 1-?m-thick aluminum, and very good signal-to-noise ratio can be expected through application of a simple threshold. PMID:22728838

Zhang, Xiaodong; Hayward, Jason P; Cates, Joshua W; Hausladen, Paul A; Laubach, Mitchell A; Sparger, Johnathan E; Donnald, Samuel B

2012-08-01

395

Particle Production from SIS to SPS Energies  

E-print Network

The production and propagation of mesons ($\\pi, \\eta, \\rho, \\omega, \\Phi, K, \\bar{K}, J/\\Psi$) in proton-nucleus and nucleus-nucleus collisions from 1 - 200 GeV/u is studied within the covariant transport approach HSD, which explicitly allows to investigate selfenergy effects of the hadrons at finite baryon density. Whereas the experimental pion and $K^+$ spectra can be described without introducing any selfenergies for the mesons, the $K^-$ yield in Ni + Ni collisions is underestimated by a factor of 5 - 7 at 1.66 and 1.85 GeV/u. However, introducing density dependent antikaon masses in line with effective chiral Lagrangians a satisfactory agreement with the data is achieved. A dropping of the $\\rho$-meson mass with baryon density, as suggested by QCD sumrule studies, is proposed to explain the dilepton spectra for S + Au and Pb + Au at SPS energies, which indicates independently that a partial restoration of chiral symmetry might be found already in the present experiments.

W. Cassing

1997-02-27

396

A K alpha dual energy x-ray source for coronary angiography.  

PubMed

The use of characteristic-line radiation from rare-earth targets bombarded by high-energy (up to 1 MeV) electron beams has been evaluated as an x-ray source for dual energy K-edge subtraction imaging of the human coronary arteries. Two characteristic-line x-ray sources, one using the split K alpha 1 and K alpha 2 lines of lanthanum excited by a high-energy electron beam and the other using the K alpha lines of barium and cerium, were studied. A Monte Carlo electron-photon simulation was used to calculate x-ray spectra and energy deposition profiles from targets of these elements bombarded by electrons in the energy range 140 keV to 1 MeV. A general dual-energy imaging model was developed that used these calculated source spectra to numerically investigate the dependence of the subtraction image signal-to-noise ratio on such factors as the ratio of K-line to x-ray continuum yield, continuum spectral shape, x-ray filtering, and detector response. A signal averaging technique for enhancing the signal-to-noise ratio was also evaluated. The results of these calculations were used to identify an optimum electron beam, target, filter, and detector configuration. A compact electron accelerator capable of providing the required electron beam parameters was designed. Calculations indicate that under ideal conditions the optimized system would be capable of imaging 2 mg/cm2 of iodine contrast agent in 20 g/cm2 of tissue with a signal-to-noise ratio of 5, a detector pixel size of 0.25 mm2, and a total image acquisition time of 10 ms. These parameters are consistent with those needed to image the human coronary arteries after an intravenous injection of iodine contrast agent. These capabilities, along with the relatively modest hardware requirements of this system, make it attractive as an x-ray source for dual energy transvenous coronary angiography. PMID:1961150

Manning, H L; Shefer, R E; Klinkowstein, R E; Mistretta, C A

1991-01-01

397

Energy expectation values of a particle in nonstationary fields  

NASA Astrophysics Data System (ADS)

We show that the origin of the nonequivalence of Hamiltonians in different representations is a change of the form of the time-derivative operator at a time-dependent unitary transformation. This nonequivalence does not lead to an ambiguity of the energy expectation values of a particle in nonstationary fields but assigns the basic representation. It has been explicitly or implicitly supposed in previous investigations that this representation is the Dirac one. We prove the alternative assertion about the basic role of the Foldy-Wouthuysen representation. We also derive the general equation for the energy expectation values in the Dirac representation. As an example, we consider a spin-1/2 particle with anomalous magnetic and electric dipole moments in strong time-dependent electromagnetic fields. We apply the obtained results to a spin-1/2 particle in a plane monochromatic electromagnetic wave and give an example of the exact Foldy-Wouthuysen transformation in the nonstationary case.

Silenko, Alexander J.

2015-01-01

398

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

SciTech Connect

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.

Shalchi, A. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

2012-10-15

399

Electromagnetic energy and momentum from a charged particle  

Microsoft Academic Search

We compute the flux of the stress-energy tensor across a tube surrounding the world line of a charged particle. By slight modifications of the definition of the Coulomb energy-momentum, the resulting expression contains the radiation reaction term (proportional to the square of the four-acceleration) but not the Schott term (proportional to the derivative of the acceleration). The equation of motion

Egon Marx

1975-01-01

400

Production of heavy charged Higgs particles at very high energies  

SciTech Connect

The production of heavy charged Higgs bosons at very high energies (LEP) is investigated. It turns out that, in favorable circumstances, charged scalars of mass 50-100 GeV could be detected and be even more copiously produced than the standard neutral Weinberg-Salam-type Higgs particle of the same mass.

Grifols, J.A.; Sola, J.

1981-01-01

401

Itep Investigation of Acoustic Phenomena from High Energy Particles  

NASA Astrophysics Data System (ADS)

The mechanisms of sound wave generation from high energy protons and features of detector response are investigated in ITEP. The attention is attracted to the different possible mechanisms than the dominant thermoradiation excitation of sound. The search of sonic signals from cosmic particles, acoustic accelerator experiments and specific hardware - are the three vectors of ITEP acoustic activity.

Demidov, V. S.; Demidova, E. V.; Gusev, K. E.; Lukyashin, V. E.; Lyashuk, V. I.; Novikov, E. G.; Rostovtsev, A. A.; Sokolov, A. Yu.; Albul, V. I.; Bychkov, V. B.; Krasnov, N. K.; Kurchanov, A. F.

402

Mass, Momentum and Kinetic Energy of a Relativistic Particle  

ERIC Educational Resources Information Center

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…

Zanchini, Enzo

2010-01-01

403

Helium burning and the death of massive stars from the beta-delayed alpha-particle emission of ¹⁶N  

Microsoft Academic Search

Helium burning in massive stars and red giants (at â¼200 MK) allows for the nucleo-synthesis of ¹²C and ¹⁶O via the ⁸Be(α,γ)¹²C triple alpha capture reaction and the ¹²C(α,γ) ¹⁶O capture reaction. At 300 keV, the most efficient energy for burning of helium, the resonant triple alpha-capture reaction is well understood but the ¹²C(α,γ)¹⁶O reaction is poorly understood, due to

Gai

1993-01-01

404

Comparison of cytotoxic and genotoxic effects of plutonium-239 alpha particles and mobile phone GSM 900 radiation in the Allium cepa test.  

PubMed

The goal of this study was to compare the cytotoxic and genotoxic effects of plutonium-239 alpha particles and GSM 900 modulated mobile phone (model Sony Ericsson K550i) radiation in the Allium cepa test. Three groups of bulbs were exposed to mobile phone radiation during 0 (sham), 3 and 9h. A positive control group was treated during 20min with plutonium-239 alpha-radiation. Mitotic abnormalities, chromosome aberrations, micronuclei and mitotic index were analyzed. Exposure to alpha-radiation from plutonium-239 and exposure to modulated radiation from mobile phone during 3 and 9h significantly increased the mitotic index. GSM 900 mobile phone radiation as well as alpha-radiation from plutonium-239 induced both clastogenic and aneugenic effects. However, the aneugenic activity of mobile phone radiation was more pronounced. After 9h of exposure to mobile phone radiation, polyploid cells, three-groups metaphases, amitoses and some unspecified abnormalities were detected, which were not registered in the other experimental groups. Importantly, GSM 900 mobile phone radiation increased the mitotic index, the frequency of mitotic and chromosome abnormalities, and the micronucleus frequency in a time-dependent manner. Due to its sensitivity, the A. cepa test can be recommended as a useful cytogenetic assay to assess cytotoxic and genotoxic effects of radiofrequency electromagnetic fields. PMID:23059817

Pesnya, Dmitry S; Romanovsky, Anton V

2013-01-20

405

Stopping powers of Al, Ti, Cu, Zr, Rh, Ag, Ta and Au for 26 MeV alpha particles and Z3 1 correction  

NASA Astrophysics Data System (ADS)

Stopping powers of Al, Ti, Cu, Zr, Rh, Ag, Ta and Au for 26 MeV alpha particles have been measured using a surface barrier silicon detector with an accuracy of 0.35%. The stopping powers for alpha particles divided by 4 have been compared with the stopping powers for 6.500 MeV protons of the same velocity. Experimental magnitudes of the Z 3 1 correction which is contained in the Bethe-Bloch stopping formula were extracted using the alpha-proton difference. Using the experimental Z 3 1 corrections thus obtained and the experimental Z 3 1 corrections of the previous paper, parameters of ? and b which appear in the theory of Ashley, Ritchie and Brandt for the Z 3 1 correction have been determined with exactly the same method as the previous paper as ? = 1.336 and b = 1.32. The magnitude of the Z 3 1 correction calculated by the theory of Ashley, Ritchie and Brandt using these parameters have been compared with those obtained by other authors.

Shiomi-Tsuda, N.; Sakamoto, N.; Ogawa, H.; Ishiwari, R.

1991-09-01

406

Radium-223 dichloride bone-targeted alpha particle therapy for hormone-refractory breast cancer metastatic to bone  

PubMed Central

Background Hormone-refractory breast cancer metastatic to bone is a clinically challenging disease associated with high morbidity, poor prognosis, and impaired quality of life owing to pain and skeletal-related events. In a preclinical study using a mouse model of breast cancer and bone metastases, Ra-223 dichloride was incorporated into bone matrix and inhibited proliferation of breast cancer cells and differentiation of osteoblasts and osteoclasts (all P values?alpha-particle therapy for the treatment of symptomatic bone metastases in patients with castration-resistant prostate cancer. On the basis of a strong preclinical rationale, we used Ra-223 dichloride to treat bone metastases in a patient with breast cancer. Results A 44-year-old white woman with metastatic breast cancer who was estrogen receptor–positive, BRCA1-negative, BRCA2-negative, PIK3CA mutation (p.His1047Arg) positive presented with diffuse bony metastases and bone pain. She had hormone refractory and chemotherapy refractory breast cancer. After Ra-223 therapy initiation her bone pain improved, with corresponding decrease in tumor markers and mixed response in 18F-FDG PET/CT and 18F-NaF bone PET/CT. The patient derived clinical benefit from therapy. Conclusion We have shown that Ra-223 dichloride can be safely administered in a patient with hormone-refractory bone metastasis from breast cancer at the US FDA–approved dose for prostate cancer. Furthermore, because the treatment did not cause any drop in hematologic parameters, it has the potential to be combined with other radiosensitizing therapies, which may include chemotherapy or targeted therapies. Given that Ra-223 dichloride is already commercially available, this case report may help future patients and provide a rationale for initiating clinical research in the use of Ra-223 dichloride to treat bone metastasis from breast cancer. A randomized clinical trial is needed to provide evidence of efficacy, safety, and good outcomes. PMID:25243101

2014-01-01

407

Radiation damage of InGaAs photodiodes by high energy particles  

SciTech Connect

Results are presented of a study on the performance degradation and the induced lattice defects of In{sub 0.53}Ga{sub 0.47}As p-i-n photodiodes, subjected to 220-MeV carbon particles. The effects on both the dark current and the photo-current are investigated as a function of the carbon fluence and correlated with DLTS results. The device degradation is compared with the one observed after exposure to 1-MeV electrons, 1-MeV fast neutrons and 20-MeV alpha rays, respectively. The differences in damage coefficients will be explained in view of the calculated number of knock-on atoms and the nonionizing energy loss (NIEL). The recovery behavior of the diode performance and of the induced deep levels by isochronal annealing is also reported.

Kudou, T.; Ohyama, H.; Shigaki, K. [Kumamoto National Coll. of Technology, Nishigoshi, Kumamoto (Japan); Simoen, E.; Claeys, C. [IMEC, Leuven (Belgium); Takami, Y. [Rikkyo Univ., Yokosuka, Kanagawa (Japan); Fujii, A. [Kumamoto Univ., Kurokami, Kumamoto (Japan); Sunaga, H. [Takasaki JAERI, Gunma (Japan)

1998-12-31

408

Exchange-correlation energy from pairing matrix fluctuation and the particle-particle random phase approximation  

NASA Astrophysics Data System (ADS)

Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H2, and eliminates delocalization errors in {H2+} and other single-bond systems. It gives surprisingly good non-bonded interaction energies - competitive with the ph-RPA - with the correct R-6 asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations.

van Aggelen, Helen; Yang, Yang; Yang, Weitao

2014-05-01

409

Exchange-correlation energy from pairing matrix fluctuation and the particle-particle random phase approximation  

SciTech Connect

Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H{sub 2}, and eliminates delocalization errors in H{sub 2}{sup +} and other single-bond systems. It gives surprisingly good non-bonded interaction energies – competitive with the ph-RPA – with the correct R{sup ?6} asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations.

Aggelen, Helen van [Department of Inorganic and Physical Chemistry, Ghent University, Ghent (Belgium) [Department of Inorganic and Physical Chemistry, Ghent University, Ghent (Belgium); Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Yang, Yang [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States)] [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Yang, Weitao [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)] [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)

2014-05-14

410

Determination of alpha/sub s/ from energy-energy correlations in e/sup +/e/sup -/ annihilation at 29 GeV  

SciTech Connect

We have studied the energy-energy correlation in e/sup +/e/sup -/ annihilation into hadrons at ..sqrt..s = 29 GeV using the Mark II detector at PEP. We find to O(..cap alpha../sub s//sup 2/) that ..cap alpha../sub s/ = 0.158 +- .003 +- .008 if hadronization is described by string fragmentation. Independent fragmentation schemes give ..cap alpha../sub s/ = .10 - .14, and give poor agreement with the data. A leading-log shower fragmentation model is found to describe the data well.

Wood, D.R.

1987-10-01

411

Generating heavy particles with energy and momentum conservation  

NASA Astrophysics Data System (ADS)

We propose a novel algorithm, called REGGAE, for the generation of momenta of a given sample of particle masses, evenly distributed in Lorentz-invariant phase space and obeying energy and momentum conservation. In comparison to other existing algorithms, REGGAE is designed for the use in multiparticle production in hadronic and nuclear collisions where many hadrons are produced and a large part of the available energy is stored in the form of their masses. The algorithm uses a loop simulating multiple collisions which lead to production of configurations with reasonably large weights. Program summaryProgram title: REGGAE (REscattering-after-Genbod GenerAtor of Events) Catalogue identifier: AEJR_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJR_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1523 No. of bytes in distributed program, including test data, etc.: 9608 Distribution format: tar.gz Programming language: C++ Computer: PC Pentium 4, though no particular tuning for this machine was performed. Operating system: Originally designed on Linux PC with g++, but it has been compiled and ran successfully on OS X with g++ and MS Windows with Microsoft Visual C++ 2008 Express Edition, as well. RAM: This depends on the number of particles which are generated. For 10 particles like in the attached example it requires about 120 kB. Classification: 11.2 Nature of problem: The task is to generate momenta of a sample of particles with given masses which obey energy and momentum conservation. Generated samples should be evenly distributed in the available Lorentz-invariant phase space. Solution method: In general, the algorithm works in two steps. First, all momenta are generated with the GENBOD algorithm. There, particle production is modeled as a sequence of two-body decays of heavy resonances. After all momenta are generated this way, they are reshuffled. Each particle undergoes a collision with some other partner such that in the pair center of mass system the new directions of momenta are distributed isotropically. After each particle collides only a few times, the momenta are distributed evenly across the whole available phase space. Starting with GENBOD is not essential for the procedure but it improves the performance. Running time: This depends on the number of particles and number of events one wants to generate. On a LINUX PC with 2 GHz processor, generation of 1000 events with 10 particles each takes about 3 s.

Mereš, Michal; Melo, Ivan; Tomášik, Boris; Balek, Vladimír; ?erný, Vladimír

2011-12-01

412

YAG:Nd crystals as possible detector to search for double beta and alpha decay of neodymium  

E-print Network

Energy resolution, alpha/beta ratio, pulse-shape discrimination for gamma rays and alpha particles, radioactive contamination were studied with neodymium doped yttrium-aluminum garnet (YAG:Nd). Applicability of YAG:Nd scintillators to search for double beta decay and alpha activity of natural neodymium isotopes are discussed.

Danevich, F A; Nagorny, S S; Tretyak, V I

2004-01-01

413

YAG:Nd crystals as possible detector to search for double beta and alpha decay of neodymium  

E-print Network

Energy resolution, alpha/beta ratio, pulse-shape discrimination for gamma rays and alpha particles, radioactive contamination were studied with neodymium doped yttrium-aluminum garnet (YAG:Nd). Applicability of YAG:Nd scintillators to search for double beta decay and alpha activity of natural neodymium isotopes are discussed.

F. A. Danevich; V. V. Kobychev; S. S. Nagorny; V. I. Tretyak

2004-10-14

414

Automated Reconstruction of Particle Cascades in High Energy Physics Experiments  

E-print Network

We present a procedure for reconstructing particle cascades from event data measured in a high energy physics experiment. For evaluating the hypothesis of a specific physics process causing the observed data, all possible reconstruction versions of the scattering process are constructed from the final state objects. We describe the procedure as well as examples of physics processes of different complexity studied at hadron-hadron colliders. We estimate the performance by 20 microseconds per reconstructed decay vertex, and 0.6 kByte per reconstructed particle in the decay trees.

O. Actis; M. Erdmann; A. Henrichs; A. Hinzmann; M. Kirsch; G. Müller; J. Steggemann

2008-09-08

415

Long-range alpha detector for contamination monitoring  

SciTech Connect

Historically, alpha detectors have been limited by the very short range of alpha particles in air and by relatively poor sensitivity, even if the particles are intercepted. Of necessity, these detectors are operated in a vacuum or in close proximity to the source if reasonable efficiency is desired. In our new long-range alpha detector (LRAD), alpha particles interact with the ambient air, producing ionization in the air at the rate of about 30,000 ion pairs per MeV of alpha energy. These charges can be transported over significant distances (several meters) in a moving current of air generated by a small fan. An ion chamber located in front of the fan measures the current carried by the moving ions. The LRAD-based monitor is more sensitive and more thorough than conventional monitors. We present current LRAD sensitivity limits and results, practical monitor designs, and proposed uses for LRAD monitors. 4 refs., 6 figs.

MacArthur, D.W.; Allander, K.S.; McAtee, J.L.

1991-01-01

416

Matching coefficients for alpha_s and m_b to O(alpha_s^2) in the MSSM  

E-print Network

We compute the exact two-loop matching coefficients for the strong coupling constant alpha_s and the bottom-quark mass m_b within the Minimal Supersymmetric Standard Model (MSSM), taking into account O(alpha_s^2) contributions from Supersymmetric Quantum Chromodynamics (SQCD). We find that the explicit mass pattern of the supersymmetric particles has a significant impact on the predictions of alpha_s and m_b at high energies. Further on, the three-loop corrections exceed the uncertainty due to the current experimental accuracy. In case of the the running bottom-quark mass, they can reach in the large tan(beta) regime up to 30% of the tree-level value.

A. Bauer; L. Mihaila; J. Salomon

2009-02-09

417

Model of collimated jets with high energy particles  

E-print Network

The increasing data set of precise observations of very energetic and collimated jets, with black hole (BH) as putative central engine, at different astrophysical scales and in various environments, should soon permit to discriminate and classify current theoretical models able to describe the jets formation. We construct a purely gravitational theoretical model of perfectly collimated jets of high energy particles in the ideal case where the central engine is a Kerr BH of mass $M$ and angular momentum by unit of mass $a$. We study in Weyl coordinates ($\\rho $, $z$) the unbound Kerr 2D-geodesics which are asymptotes to straight lines parallel to the $z$ axis of equations \\rho =constant= \\rho_{1}= [(a/M)^2+Q/(E^2-1)]^{1/2} of which existence was recently demonstrated (Gariel et al.,A & A, 2010). On these geodesics, flow test particles of energy $E$, with a Carter constant $Q$ and (necessarily) an angular momentum $L_{z}=0$. Studying the characteristics of the geodesics equations system, in the special case of a double root, we exhibit jets with a radial structure, whose energy flux can be calculated. From the observed data of the jet powers, we obtain the mean particles density, the particles flow, the speed and the Lorentz factor of the jets, for any charged or neutral test particle. Then, we numerically apply these results to electrons. We also discuss the domains of initial conditions for geodesics starting inside the ergosphere. All these results come from the Kerr spacetime structure, and enhance the Penrose process as a plausible origin for the high energy jets.

C. Barbachoux; J. Gariel; G. Marcilhacy; N. O. Santos

2010-11-30

418

PAMELA's Measurements of Magnetospheric Effects on High Energy Solar Particles  

NASA Astrophysics Data System (ADS)

Whether solar energetic particles (SEP) attain energies in excess of a GeV through flare reconnection or through CME-driven shocks is still in debate today. Observations of the properties of SEPs relate both to the acceleration mechanisms at play but also to the influences experienced during transport. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instrument, provides new observations of SEPs that uniquely set apart the affects of acceleration from those of transport. PAMELA detects the composition and the angular distribution of the particles about the magnetic field, i.e. pitch angle distribution, over a broad energy range (from ~80 MeV to beyond one GeV) -- bridging a critical gap between space-based measurements and ground-based. We report on the observation of high-energy SEP data from PAMELA acquired during the 2012 May 17 ground level enhancement (GLE). These data exhibit differential anisotropies and thus transport features over the instrument rigidity range. SEP protons exhibit two distinct pitch angle distributions; a low-energy population that extends to 90$^{&iccedil;rc}$ and a population that is beamed at high energies (> 1 GeV), consistent with neutron monitor measurements. The arrival of SEPs over a broad range in energy at Earth within 20 minutes sets strong constraints on the pitch angle distribution of SEPs originating at the Sun. To explain a low-energy SEP population that exhibits significant scattering or redistribution accompanied by a high-energy population that reaches the Earth relatively unaffected by dispersive transport effects, we postulate that the scattering or redistribution takes place locally. We believe these are the first comprehensive measurements of the effects of solar energetic particle transport in the Earth's magnetosheath.

de Nolfo, Georgia; Boezio, M.; Bravar, Ulisse; Bruno, A.; Christian, Eric R.; Martucci, M.; Merge, M.; Mocchiutti, E.; Munini, R.; Ricci, M.; Ryan, James Michael; Stochaj, Steven; Thakur, N.

2015-04-01

419

High-energy particles associated with solar flares  

NASA Technical Reports Server (NTRS)

High-energy particles, the so-called solar cosmic rays, are often generated in association with solar flares, and then emitted into interplanetary space. These particles, consisting of electrons, protons, and other heavier nuclei, including the iron-group, are accelerated in the vicinity of the flare. By studying the temporal and spatial varation of these particles near the earth's orbit, their storage and release mechanisms in the solar corona and their propagation mechanism can be understood. The details of the nuclear composition and the rigidity spectrum for each nuclear component of the solar cosmic rays are important for investigating the acceleration mechanism in solar flares. The timing and efficiency of the acceleration process can also be investigated by using this information. These problems are described in some detail by using observational results on solar cosmic rays and associated phenomena.

Sakurai, K.; Klimas, A. J.

1974-01-01

420

Discovery of Long-Lived Shape Isomeric States which Decay by Strongly Retarded High-Energy Particle Radioactivity  

E-print Network

The reaction 28Si + 181Ta has been studied at E(Lab) = 125 and 135 MeV. Coincidences between high energy particles and various X- and gamma-rays from abnormally long-lived states were observed. e.g. 7.8 - 8.6 MeV alpha-particles with gamma-rays of a superdeformed band, 5.1 - 5.5 MeV alpha-particles with X- and gamma-rays of W, Re, and Pt, and 3.88 MeV particles (interpreted as protons) with 185.8 keV gamma-rays. The data are interpreted in terms of the production of long-lived (t(1/2) of several months) high spin isomeric states in the second well of the potential in the parent nuclei, which decay to the normal states in the daughters, and in the third well of the potential, which decay to the second well.

A. Marinov; S. Gelberg; D. Kolb

2000-06-26

421

Semiconductor polycrystalline alpha detectors  

Microsoft Academic Search

In order to check possible novel neutron detectors based on composite semiconductor detectors containing nuclides with large cross sections for neutron, we tested their response to alpha particles. In the present paper we describe results obtained with composite samples made of hexagonal Boron Nitride particles bound with Polystyrene or Nylon-6. The samples were tested under 5.5 MeV alpha particle radiation

M. Schieber; M. Roth; A. Zuck; G. Marom; O. Khakhan; Z. B. Alfassi

2006-01-01

422

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

NASA Astrophysics Data System (ADS)

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/?m to 975 KeV/gmm 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/?m. The inactivation cross-section (?i) and the action-section for mutant induction (?m) ranged from 2.2 to 92.0 ?m2 and 0.09 to 5.56 × 10-3 ?m2, respectively. The maximum values were obtained by 56Fe with an LET of 200 keV/?m. The mutagenicity (?m/?i) ranged from 2.05 to 7.99 × 10-5 with the maximum value at 150 keV/?m. 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.

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

1994-10-01

423

Broken flavor symmetries in high energy particle phenomenology  

SciTech Connect

Over the past couple of decades, the Standard Model of high energy particle physics has clearly established itself as an invaluable tool in the analysis of high energy particle phenomenon. However, from a field theorists point of view, there are many dissatisfying aspects to the model. One of these, is the large number of free parameters in the theory arising from the Yukawa couplings of the Higgs doublet. In this thesis, we examine various issues relating to the Yukawa coupeng structure of high energy particle field theories. We begin by examining extensions to the Standard Model of particle physics which contain additional scalar fields. By appealing to the flavor structure observed in the fermion mass and Kobayashi-Maskawa matrices, we propose a reasonable phenomenological parameterization of the new Yukawa couplings based on the concept of approximate flavor symmetries. It is shown that such a parameterization eliminates the need for discrete symmetries which limit the allowed couplings of the new scalars. New scalar particles which can mediate exotic flavor changing reactions can have masses as low as the weak scale. Next, we turn to the issue of neutrino mass matrices, where we examine a particular texture which leads to matter independent neutrino oscillation results for solar neutrinos. We, then, examine the basis for extremely strict limits placed on flavor changing interactions which also break lepton- and/or baryon-number. These limits are derived from cosmological considerations. Finally, we embark on an extended analysis of proton decay in supersymmetric SO(10) grand unified theories. In such theories, the dominant decay diagrams involve the Yukawa couplings of a heavy triplet superfield. We argue that past calculations of proton decay which were based on the minimal supersymmetric SU(5) model require reexamination because the Yukawa couplings of that theory are known to be wrong.

Antaramian, A.

1995-02-22

424

Two-Particle Separation Energies in the Superdeformed Well  

NASA Astrophysics Data System (ADS)

The location of nuclear closed shells, as evidenced through discontinuities in binding energy and one- and two-particle separation energy systematics, remains one of the simplest tests of global nuclear models. How shell gaps evolve, whether with increasing mass, increasing neutron:proton ratio or increasing deformation, is still uncertain, and it has recently been suggested that one must go beyond a static meanfield picture to include the effects of dynamic fluctuations in the nuclear shape even in the ground state. The identification of key properties which may distinguish between competing approaches is thus vital. Comparison of the binding energies of superdeformed nuclei in the A ? 190 region shows that two-proton separation energies are higher in the superdeformed state than in the normal state, despite the probably lower Coulomb barrier and lower total binding energy. Possible reasons for this difference are discussed. This somewhat counterintuitive result provides a critical test for global nuclear models.

Wilson, A. N.; Korichi, A.; Siem, S.; Astier, A.; Bazzacco, D.; Bednarczyk, P.; Bergström, M. H.; Chmel, S.; Cullen, D. M.; Davidson, P. M.; Görgen, A.; Hannachi, F.; Hübel, H.; Kintz, N.; Lauritsen, T.; Lopez-Martens, A.; Lunardi, S.; Naguleswaran, S.; Nyakó, B. M.; Rejmund, M.; Schönwasser, G.; Schück, C.; Sharpey-Schafer, J. F.; Timar, J.; Wadsworth, R.; Libert, J.

2011-09-01

425

Origin and transport of high energy particles in the galaxy  

NASA Technical Reports Server (NTRS)

The origin, confinement, and transport of cosmic ray nuclei in the galaxy was studied. The work involves interpretations of the existing cosmic ray physics database derived from both balloon and satellite measurements, combined with an effort directed towards defining the next generation of instruments for the study of cosmic radiation. The shape and the energy dependence of the cosmic ray pathlength distribution in the galaxy was studied, demonstrating that the leaky box model is not a good representation of the detailed particle transport over the energy range covered by the database. Alternative confinement methods were investigated, analyzing the confinement lifetime in these models based upon the available data for radioactive secondary isotopes. The source abundances of several isotopes were studied using compiled nuclear physics data and the detailed transport calculations. The effects of distributed particle acceleration on the secondary to primary ratios were investigated.

Wefel, John P.

1987-01-01

426

Cryogenic Beam Screens for High-Energy Particle Accelerators  

E-print Network

Applied superconductivity has become a key enabling technology for high-energy particle accelerators, thus making them large helium cryogenic systems operating at very low temperature. The circulation of high-intensity particle beams in these machines generates energy deposition in the first wall through different processes. For thermodynamic efficiency, it is advisable to intercept these beam-induced heat loads, which may be large in comparison with cryostat heat in-leaks, at higher temperature than that of the superconducting magnets of the accelerator, by means of beam screens located in the magnet apertures. Beam screens may also be used as part of the ultra-high vacuum system of the accelerator, by sheltering the gas molecules cryopumped on the beam pipe from impinging radiation and thus avoiding pressure runaway. Space being extremely tight in the magnet apertures, cooling of the long, slender beam screens also raises substantial problems in cryogenic heat transfer and fluid flow. We present sizing rule...

Baglin, V; Tavian, L; van Weelderen, R

2013-01-01

427

Study on the evolution and nature of interstitial-type defects following proton and alpha particle implantation during low-dose proximity gettering of platinum  

Microsoft Academic Search

Platinum has been diffused into epitaxial n-type silicon at 600 degC, 650 degC and 700 degC for 30min following implantation with 3.3MeV alpha particles. The doses employed were between 1x1011 and 1x1014He+cm-2. Also an implantation involving protons at 850keV with doses of 5x1013 and 5x1014H+cm-2 has been performed followed by an annealing at 600 degC or 700 degC. Thereafter the

D. C. Schmidt; B. G. Svensson; J. F. Barbot; C. Blanchard

1999-01-01

428

Ion transport and energy conservation in submitochondrial particles  

Microsoft Academic Search

Summary The combination of valinomycin and nigericin in the presence of K+ uncouples submitochondrial particles (SMP) as evidenced by: 1) loss and release of the oligomycin-induced respiratory control; 2) inhibition of the P\\/0 ratio; 3) inhibition of three energy-linked reactions — pyridine-nucleotide transhydrogenation, reversal of electron-transfer, and bromthymol blue and 8-anilino-1-naphtalenesulfonate responses; and 4) change of redox state of cytochromes

Maurice Montal; Britton Chance; Chuan-pu Lee

1970-01-01

429

High-density lipoprotein (HDL3)-associated alpha-tocopherol is taken up by HepG2 cells via the selective uptake pathway and resecreted with endogenously synthesized apo-lipoprotein B-rich lipoprotein particles.  

PubMed Central

alpha-Tocopherol (alphaTocH) is transported in association with lipoproteins in the aqueous milieu of the plasma. Although up to 50% of circulating alphaTocH is transported by high-density lipoproteins (HDLs), little is known about the mechanisms of uptake of HDL-associated alphaTocH. During the current study, human apolipoprotein (apo)E-free HDL subclass 3 (HDL3) labelled with [14C]alphaTocH was used to investigate uptake mechanisms of HDL3-associated alphaTocH by a permanent hepatoblastoma cell line (HepG2). HDL3-associated alphaTocH was taken up independently of HDL3 holoparticles in excess of apoA-I comparable with the non-endocytotic delivery of cholesteryl esters to cells termed the 'selective' cholesteryl ester uptake pathway. Experiments with unlabelled HDL3 demonstrated net mass transfer of alphaTocH to HepG2 cells. Time-dependent studies with [14C]alphaTocH-labelled HDL3 revealed tracer uptake in 80-fold excess of apoA-I and in 4-fold excess of cholesteryl linoleate. In addition to HLDs, low-density lipoprotein (LDL)-associated alphaTocH was also taken up in excess of holoparticles, although to a lesser extent. These findings were confirmed with unlabelled lipoprotein preparations, in which HDL3 displayed a 2- to 3-fold higher alphaTocH donor efficiency than LDLs (lipoproteins adjusted for equal amounts of alphaTocH). An important factor affecting particle-independent uptake of alphaTocH was the cellular cholesterol content (a 2-fold increase in cellular cholesterol levels resulted in a 2.3-fold decrease in uptake). Pulse-chase studies demonstrated that some of the HDL3-associated alphaTocH taken up independently of holoparticle uptake was resecreted along with a newly synthesized apoB-containing lipoprotein fraction. PMID:9576851

Goti, D; Reicher, H; Malle, E; Kostner, G M; Panzenboeck, U; Sattler, W

1998-01-01

430

Energy deposition rates by charged particles. [in upper atmosphere  

NASA Technical Reports Server (NTRS)

A summary of measurements of the precipitation of electrons and positive ions (in the keV-MeV range) detected aboard eight rockets launched within the Energy Budget Campaign from Northern Scandinavia is given, together with corresponding satellite data. In some cases strong temporal variations of the downgoing integral fluxes were observed. The fluxes provide the background for the calculated ion production rates and altitude profiles of the energy deposition into the atmosphere at different levels of geomagnetic disturbance and cosmic noise absorption. The derived ion production rates by eneretic particles are compared to other night-time ionisation sources.

Torkar, K. M.; Urban, A.; Bjordal, J.; Lundblad, J. A.; Soraas, F.; Smith, L. G.; Dumbs, A.; Grandal, B.; Ulwick, J. C.; Vancour, R. P.

1985-01-01

431

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

E-print Network

the bark of Magnolia officinalis which is used as a traditional Chinese medicine, were studied on alpha the associated elevated risks. Various traditional Chinese medicines (TCMs) had been found effective to cure been used as a traditional Chinese medicine for many years. Our current research aims at understanding

Yu, K.N.

432

The alpha magnetic spectrometer on the International Space Station  

Microsoft Academic Search

The Alpha Magnetic Spectrometer (AMS) is a particle physics detector designed to measure charged cosmic ray spectra up to the TV region, with high-energy photon detection capability up to few hundred GeV. AMS is a superconducting spectrometer with large acceptance, long duration (at least three years for the magnet) and state of the art particle identification techniques. AMS will investigate

B. Borgia

2005-01-01

433

Fitting Single Particle Energies in $sdgh$ Major Shell  

E-print Network

We have performed two kinds of non-linear fitting procedures to the single-particle energies in the $sdgh$ major shell to obtain better shell model results. The low-lying energy eigenvalues of the light Sn isotopes with $A=103-110$ in the $sdgh$-shell are calculated in the framework of the nuclear shell model by using CD-Bonn two-body effective nucleon-nucleon interaction. The obtained energy eigenvalues are fitted to the corresponding experimental values by using two different non-linear fitting procedures, i.e., downhill simplex method and clonal selection method. The unknown single-particle energies of the states $2s_{1/2}$, $1d_{3/2}$, and $0h_{11/2}$ are used in the fitting methods to obtain better spectra of the $^{104,106,108,110}$Sn isotopes. We compare the energy spectra of the $^{104,106,108,110}$Sn and $^{103,105,107,109}$Sn isotopes with/without a nonlinear fit to the experimental results.

Dikmen, E; Cengiz, Y

2015-01-01

434

Fitting Single Particle Energies in $sdgh$ Major Shell  

E-print Network

We have performed two kinds of non-linear fitting procedures to the single-particle energies in the $sdgh$ major shell to obtain better shell model results. The low-lying energy eigenvalues of the light Sn isotopes with $A=103-110$ in the $sdgh$-shell are calculated in the framework of the nuclear shell model by using CD-Bonn two-body effective nucleon-nucleon interaction. The obtained energy eigenvalues are fitted to the corresponding experimental values by using two different non-linear fitting procedures, i.e., downhill simplex method and clonal selection method. The unknown single-particle energies of the states $2s_{1/2}$, $1d_{3/2}$, and $0h_{11/2}$ are used in the fitting methods to obtain better spectra of the $^{104,106,108,110}$Sn isotopes. We compare the energy spectra of the $^{104,106,108,110}$Sn and $^{103,105,107,109}$Sn isotopes with/without a nonlinear fit to the experimental results.

E. Dikmen; O. Öztürk; Y. Cengiz

2015-02-12

435

Energy-momentum balance in particle - domain wall perforating collision  

E-print Network

We investigate the energy-momentum balance in the perforating collision of a point particle with an infinitely thin planar domain wall within the linearized gravity in arbitrary dimensions. Since the metric of the wall increases with distance, the wall and the particle are never free, and their energy-momentum balance involves not only the instantaneous kinetic momenta, but also the non-local contribution of gravitational stresses. However, careful analysis shows that the stresses can be unambiguously divided between the colliding objects leading to definition of the gravitationally dressed momenta. These take into account for gravity in the same way as the potential energy does in the non-relativistic theory, but our treatment is fully relativistic. Another unusual feature of our problem is the non-vanishing flux of the total energy-momentum tensor through the lateral surface of the world tube. In this case the zero divergence of the energy-momentum tensor does not imply conservation of the total momentum de...

Gal'tsov, D V; Spiirin, P A

2014-01-01

436

New challenges in high-energy particle radiobiology  

PubMed Central

Densely ionizing radiation has always been a main topic in radiobiology. In fact, ?-particles and neutrons are sources of radiation exposure for the general population and workers in nuclear power plants. More recently, high-energy protons and heavy ions attracted a large interest for two applications: hadrontherapy in oncology and space radiation protection in manned space missions. For many years, studies concentrated on measurements of the relative biological effectiveness (RBE) of the energetic particles for different end points, especially cell killing (for radiotherapy) and carcinogenesis (for late effects). Although more recently, it has been shown that densely ionizing radiation elicits signalling pathways quite distinct from those involved in the cell and tissue response to photons. The response of the microenvironment to charged particles is therefore under scrutiny, and both the damage in the target and non-target tissues are relevant. The role of individual susceptibility in therapy and risk is obviously a major topic in radiation research in general, and for ion radiobiology as well. Particle radiobiology is therefore now entering into a new phase, where beyond RBE, the tissue response is considered. These results may open new applications for both cancer therapy and protection in deep space. PMID:24198199