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1

Transport of Radioactive Material by Alpha Recoil  

SciTech Connect

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

Icenhour, A.S.

2005-05-19

2

Transport of Radioactive Material by Alpha Recoil  

Microsoft Academic Search

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

A. S. Icenhour

2005-01-01

3

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

4

Biological Effect of Lead-212 Localized in the Nucleus of Mammalian Cells: Role of Recoil Energy in the Radiotoxicity of Internal Alpha-Particle Emitters1  

PubMed Central

The radiochemical dipyrrolidinedithiocarbamato-212Pb(II) [212Pb(PDC)2] is synthesized and its effects on colony formation in cultured Chinese hamster V79 cells are investigated. The cellular uptake, biological retention, subcellular distribution and cytotoxicity of the radiocompound are determined. The 212Pb is taken up quickly by the cells, reaching saturation levels in 1.25 h. When the cells are washed, the intracellular activity is retained with a biological half-life of 11.6 h. Gamma-ray spectroscopy indicates that the 212Pb daughters (212Bi, 212Po and 208Tl) are in secular equilibrium within the cell. About 72% of the cellular activity localizes in the cell nucleus, of which 35% is bound specifically to nuclear DNA. The mean cellular uptake required to achieve 37% survival is 0.35 mBq of 212Pb per cell, which delivers a dose of 1.0 Gy to the cell nucleus when the recoil energy of 212Bi and 212Po decays is ignored and 1.7 Gy when recoil is included. The corresponding RBE values compared to acute external 137Cs ? rays at 37% survival are 4.0 and 2.3, respectively. The chemical Pb(PDC)2 is not chemotoxic at the concentrations used in this study. Because the ?-particle emitter 212Pb decays to the ?-particle-emitting daughters 212Bi and 212Po, these studies provide information on the biological effects of ?-particle decays that occur in the cell nucleus. Our earlier studies with cells of the same cell line using 210Po (emits 5.3 MeV ? particle) localized predominantly in the cytoplasm resulted in an RBE of 6. These earlier results for 210Po, along with the present results for 212Pb, suggest that the recoil energy associated with the 212Bi and 212Po daughter nuclei plays little or no role in imparting biological damage to critical targets in the cell nucleus.

Azure, Michael T.; Archer, Ronald D.; Sastry, Kandula S. R.; Rao, Dandamudi V.; Howell, Roger W.

2012-01-01

5

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

SciTech Connect

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

Fleischer, R.L.

1980-02-29

6

ENERGY IDSTRIBUTION FO $alpha$RECOIL NUCLEI IN FORMVAR  

Microsoft Academic Search

BS>The energy distribution curve of the recoil nuclei from Po²¹² ; alpha decay (energy of origin 169 kev) after their passage through formvar films ; between 1.4 and 7.0 mu g\\/cm² thick was ascertained with the help of an ; electronic transmission time measurement. The spectra showed for the thin films ; a strongly asymmetric form, wiuch could be explained

Zahn

1963-01-01

7

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

SciTech Connect

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

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

1985-10-01

8

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

9

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

10

Desorption of 220Rn progeny from large surfaces by alpha- and beta-recoil processes.  

PubMed

Transfer (i.e., desorption or detachment) of 220Rn progeny from a substrate (metal disc, filter material, and activated charcoal) to its surroundings has been investigated. The technique, methodology, and materials used differ from the work of others in a number of significant ways. For instance, 220Rn progeny were deposited on substrates by plate-out techniques, and detached 220Rn progeny were measured using a silicon barrier alpha-particle detector as both the host "receiving" surface and the detector for the detached radionuclides. Transfer of 220Rn progeny from the substrates to the detector was observed by alpha- and beta-recoil processes. The latter were demonstrated by using nonadsorbing 220Rn substrates. Other possible mechanisms of 220Rn progeny transfer are also discussed. PMID:1649806

Bigu, J

1991-08-01

11

Alpha Particle Diagnostic  

SciTech Connect

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

Fisher, Ray, K.

2009-05-13

12

Separation of the alpha-emitting radioisotopes actinium-225 and bismuth-213 from thorium-229 using alpha recoil methods  

Microsoft Academic Search

An innovative method has been demonstrated for separating alpha-emitting isotopes for medical radiotherapy applications. The method relies on recoil-ion separation rather than on conventional wet chemistry techniques to separate medical isotopes from their precursor sources. The isotopes 225Ac and 213Bi have been separated from electro-deposited sources of 229ThO2. Separations of 225Ac were carried out by placing nickel recoil collector foils

F. H. Ruddy; A. R. Dulloo; J. G. Seidel; B. Petrovic

2004-01-01

13

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

SciTech Connect

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

Fleischer, R.L. (General Electric Research and Development Center, Schenectady, NY (USA))

1988-06-01

14

A new setup for elastic recoil analysis using ion induced electron emission for particle identification  

Microsoft Academic Search

We describe a new setup for elastic recoil detection analysis (ERDA) using our recently developed particle identification method. Before the ions and elastic recoil atoms from the target reach a silicon surface barrier detector for energy analysis, they penetrate a set of thin foils (e.g. carbon). The ion induced electron emission yield from the foils depends on the nuclear charge

E. Steinbauer; O. Benka; M. Steinbatz

1998-01-01

15

Electrochemical Etching Amplification of Low-Let Recoil Particle Tracks in Polymers for Fast Neutron Dosimetry.  

National Technical Information Service (NTIS)

An electrochemical etching method for the amplification of fast-neutron-induced recoil particle tracks in polymers was investigated. The technique gave superior results over those obtained by conventional etching methods especially when polycarbonate foil...

M. Sohrabi K. Z. Morgan

1975-01-01

16

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

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

The alpha-recoil effects of uranium in the Oklo reactor  

NASA Astrophysics Data System (ADS)

A series of acid-leaching experiments have been carried out on a sample of uranium ore from reactor zone number 10 of the Oklo mines in Gabon. Anomalously high U-234/U-238 ratios were observed accompanied by modestly increased U-235/U-238 ratios in uranium fractions. These results, which can be interpreted as being due to the alpha-recoil effects of U-238 and Pu-239, provide a convenient way of calculating the conversion factor (the fraction of uranium atoms converted to plutonium) of the natural reactors from radiochemical data, obviating the necessity for mass-spectrometric measurements.

Sheng, Z. Z.; Kuroda, P. K.

1984-12-01

19

Alpha-particle spectrometer experiment  

NASA Technical Reports Server (NTRS)

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

Gorenstein, P.; Bjorkholm, P.

1972-01-01

20

Isomeric yield ratios in proton-, 3-, and alpha-particle-induced reactions on 197Au  

Microsoft Academic Search

Excitation functions and mean projected recoil-ion ranges of the isomeric nuclei produced in proton-, 3-, and alpha-particle-induced reactions on 197Au were measured by an activation technique for bombarding energies Ep<~50 MeV, and E 3He, alpha<~40 MeV. Isomeric yield ratios (sigmam\\/sigmag) were determined as a function of the incident particle energy. The experimental excitation functions and isomeric yield ratios were compared

Y. Nagame; K. Sueki; S. Baba; H. Nakahara

1990-01-01

21

Collective Rayleigh scattering from dielectric particles: A classical theory of the Collective Atomic Recoil Laser  

NASA Astrophysics Data System (ADS)

A classical theory of Rayleigh scattering of electromagnetic radiation by dielectric particles is presented, in which the particles may interact cooperatively via common pump and probe radiation fields. The collective nature of the process is manifest both in the exponential growth of the bunching of the particles at the radiation wavelength to form a particle grating, and in the exponential growth of the counterpropagating probe radiation intensity. We call this `Collective Rayleigh Scattering'. This process arises from a fully classical description of the Collective Atomic Recoil Laser (CARL) with linear dielectric particles.

McNeil, B. W. J.; Robb, G. R. M.

1998-03-01

22

Secondary Fe-Mn-oxides in minerals heavily damaged by alpha-recoil: possible implications for palaeomagnetism  

Microsoft Academic Search

Sub-micron Fe,Mn-oxides in columbite-tantalite minerals are bound to metamict domains in the host. These nano-oxides are secondary minerals as the metamict zones formed through accumulation of damages from alpha-recoil, each of which in a small volume destroys the crystal lattice of the U and Th bearing columbite-tantalite host. Transmission electron microscope investigations demonstrate that the oxides fall in the compositional

Rolf L. Romer; Norbert Nowaczyk; Richard Wirth

2007-01-01

23

Alpha-recoil tracks in natural dark mica: Dating geological samples by optical and scanning force microscopy  

Microsoft Academic Search

Alpha-recoil tracks (ART) are lattice defects caused by the ?-decay of 238U, 235U, 232Th, and daughter products. Visualization of etched ARTs in dark mica by phase-contrast microscopy allows dating of Quaternary geological as well as archaeological materials. Visualization of etched ARTs by Nomarski-differential-interference-contrast microscopy (NDICM) and scanning force microscopy (SFM) enables the access to areal densities (?a) of ART etch

U. A. Glasmacher; M. Lang; S. Klemme; B. Moine; L. Barbero; R. Neumann; G. A. Wagner

2003-01-01

24

Beta-Neutrino Correlations and Recoil Nuclear Alignment Effects in Light Delayed Particle Emitters.  

National Technical Information Service (NTIS)

An analysis of the Doppler-broadened line shapes of alpha -groups from the beta -delayed alpha -decay of sup 20 Na has revealed a simple method of obtaining beta sup + - nu anisotropy coefficients which is applicable for all of the beta -delayed particle ...

R. D. Macfarlane R. J. Nickles N. S. Oakey

1987-01-01

25

Alpha-recoil in UPb geochronology: effective sample size matters  

Microsoft Academic Search

Displacement of the daughter isotope by a-recoil results in an open system on the nanoscale. For a heterogeneous distribution of U and Th, this redistribution of intermediate and stable daughter isotopes results in subvolumes with a deficit of Pb and others with an excess of Pb. Whether such heterogeneities affect the analyzed UPb system depends on: (1) the volume of

Rolf L. Romer

2003-01-01

26

Improvements to alpha-particle spectrometry techniques.  

PubMed

Improvements to the conventional methods for alpha-particle spectrometry measurement and analysis have recently been implemented in our laboratory. They include the application of corrections for energy drift in long-duration measurements, the development and application of an efficient deconvolution method for complex alpha spectra using the new computer code ALFITeX, an alpha-gamma coincidence system using a dual-parameter multichannel analyzer, and the digitization of this coincidence system. PMID:24315085

Caro Marroyo, B; Martn Snchez, A; Jurado Vargas, M

2014-05-01

27

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

28

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 193 photons per one MeV of energy released in air at normal pressure (temperature 22C, 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.; Perjrvi, K.; Toivonen, H.; Toivonen, J.

2014-05-01

29

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

30

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

31

Development of alpha tracks and neutron-induced recoil protons in CR39 for dosimetric applications  

Microsoft Academic Search

In the present work, CR-39 plastic detectors have been used in alpha and neutron detection studies. Detectors were first treated chemically, before irradiation, for background reduction and registration efficiency improvement. CR-39 detectors etched pre-chemically in 6.25N NaOH solution at 70C for 10 h were found to be necessary to minimize the background tracks. Alpha tracks were treated chemically and electrochemically

A. Hussein; S. A. Hager; A. M. I. Kany; M. K. El Nimr; E. H. Ghanim

1996-01-01

32

Development of alpha tracks and neutron-induced recoil protons in CR39 for dosimetric applications  

Microsoft Academic Search

In the present work, CR-39 plastic detectors have been used in alpha and neutron detection studies. Detectors were first treated chemically, before irradiation, for background reduction and registration efficiency improvement. CR-39 detectors etched pre-chemically in 6.25N NaOH solution at 70C for 10 h were found to be necessary to minimize the background tracks.Alpha tracks were treated chemically and electrochemically and

A. Hussein; S. A. Hager; A. M. I. Kany; M. K. El Nimr; E. H. Ghanim

1996-01-01

33

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

34

Global alpha-particle optical potentials.  

National Technical Information Service (NTIS)

A search for a global optical potential for alpha-particles is described. It did not prove possible to find such a potential valid for a wide range of energies and nuclei, even treating the absorbing potential as an adjustable parameter for each nucleus. ...

N. Ferdous

1991-01-01

35

Recoil Distance Method lifetime measurements via gamma-ray and charged-particle spectroscopy at NSCL  

NASA Astrophysics Data System (ADS)

The Recoil Distance Method (RDM) is a well-established technique for measuring lifetimes of electromagnetic transitions. Transition matrix elements derived from the lifetimes provide valuable insight into nuclear structure. Recent RDM investigations at NSCL present a powerful new model-independent tool for the spectroscopy of nuclei with extreme proton-to-neutron ratios that exhibit surprising behavior. Neutron-rich 18C is one such example, where a small B(E2; 2+1 ? 0+gs) represented a dramatic shift from the expected inverse relationship between the B(E2) and 2+1 excitation energy. To shed light on the nature of this quadrupole excitation, the RDM lifetime technique was applied with the Koln/NSCL plunger. States in 18C were populated by the one-proton knockout reaction of a 19N secondary beam. De-excitation gamma rays were detected with the Segmented Germanium Array in coincidence with reaction residues at the focal plane of the S800 Magnetic Spectrometer. The deduced B(E2) and excitation energy were both well described by ab initio no-core shell model calculations. In addition, a novel extension of RDM lifetime measurements via charged-particle spectroscopy of exotic proton emitters has been investigated. Substituting the reaction residue degrader of the Koln/NSCL plunger with a thin silicon detector permits the study of short-lived nuclei beyond the proton dripline. A proof of concept measurement of the mean lifetime of the two-proton emitter 19Mg was conducted. The results indicated a sub-picosecond lifetime, one order of magnitude smaller than the published results, and validate this new technique for lifetime measurements of charged-particle emitters.

Voss, Philip Jonathan

36

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 Alfvn eigenmodes (TAE), and ion cyclotron resonant frequency (ICRF) waves were roughly consistent with theoretical modeling. This paper reviews what was learned and identifies what remains to be understood.

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

1998-12-14

37

Alpha-particle-driven Alfven turbulence and its effect on alpha-particle transport  

SciTech Connect

Recent developments in computational and theoretical studies of alpha-particle-driven Alfven turbulence in both the long (k[perpendicular][rho][sub i] [much lt] 1) and the short (k[perpendicular][rho][sub i] [le] 1) wavelength regimes are reported. In the long wave-length regime, a hybrid particle-fluid model is solved numerically as well as analytically in a simple slab geometry. The dominant nonlinear interactions are found to be couplings between two Alfven waves to generate a zero-frequency electromagnetic convective cell and strong E x B convection of resonant alpha particles, which result in significant changes in plasma equilibria. The fluctuation energies first increase, then saturate and decay. The alpha-particle transport is convective and significant but does not necessarily lead to an appreciable alpha-particle loss. A mode-coupling theory is developed to explain the simulation results. In the short wavelength regime, a reduced turbulence model that describes the coupled nonlinear evolutions of fluctuation spectrum [vert bar][phi][vert bar][sub k][sup 2] and alpha-particle density profile n[sup [alpha

Gang, F.Y.; Sigmar, D.J. (Massachusetts Institute of Technology, Cambridge, MA (United States)); Leboeuf, J.N. (Oak Ridge National Lab., TN (United States)); Wising, F. (Chalmers Univ. of Technology, Gothenburg (Sweden))

1994-05-01

38

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

SciTech Connect

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

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

2002-05-02

39

Recoil Separators for Nuclear Astrophysics  

NASA Astrophysics Data System (ADS)

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

Blackmon, J. C.

2004-10-01

40

Alpha particle diagnostics using impurity pellet injection  

NASA Astrophysics Data System (ADS)

We have proposed using impurity injection to measure the energy distribution of the fast confined alpha particles in a reacting plasma. The ablation cloud surrounding the injected pellet is thick enough that an equilibrium fraction F(sub o)(sup (infinity))(E) of the incident alphas should be neutralized as they pass through the cloud. By observing neutrals created in the large spatial region of the cloud which is expected to be dominated by the helium-like ionization state, e.g., Li(+) ions, we can determine the incident alpha distribution dn(sub He)2+/dE from the measured energy distribution of neutral helium atoms. Initial experiments were performed on TEXT in which we compared pellet penetration with our impurity pellet ablation model, and measured the spatial distribution of various ionization states in carbon pellet clouds. Experiments have recently begun on TFTR with the goal of measuring the alpha particle energy distribution during D-T operation in 1993-94. A series of preliminary experiments are planned to test the diagnostic concept. The first experiments will observe neutrals from beam-injected deuterium ions and the high energy He-3 tail produced during ICH minority heating on TFTR interacting with the cloud. We will also monitor by line radiation the charge state distributions in lithium, boron, and carbon clouds.

Fisher, R. K.; McChesney, J. M.; Howald, A. W.; Parks, P. B.; Snipes, J. A.; Terry, J. L.; Marmar, E. S.; Zweben, S. J.; Medley, S.

1992-05-01

41

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

Dueas, J A; de la Torre Prez, J; Martn Snchez, A; Martel, I

2014-08-01

42

Alpha-particle-induced soft errors in dynamic memories  

Microsoft Academic Search

A new physical soft error mechanism in dynamic RAM's and CCD's is the upset of stored data by the passage of alpha particles through the memory array area. The alpha particles are emitted by the radioactive decay of uranium and thorium which are present in parts-per-million levels in packaging materials. When an alpha particle penetrates the die surface, it can

T. C. May; M. H. Woods

1979-01-01

43

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

SciTech Connect

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

Lumpkin, G.R.; Ewing, R.C. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Geology; Foltyn, E.M. [Los Alamos National Lab., NM (United States)

1985-10-01

44

Alpha particle collective Thomson scattering in TFTR  

SciTech Connect

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

Machuzak, J.S.; Woskov, P.P.; Rhee, D.Y.; Gilmore, J. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center; Bretz, N.L.; Park, H.K. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Aamodt, R.E.; Cheung, P.Y.; Russell, D.A. [Lodestar Research Corp., Boulder, CO (United States); Bindslev, H. [JET Joint Undertaking, Abingdon (United Kingdom)

1993-11-01

45

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

NASA Astrophysics Data System (ADS)

The Lunar Prospector Alpha Particle Spectrometer (APS) was designed to detect characteristic-energy alpha particles from the decay of Rn-222, Po-218, and Po-210 and to therefore map sites of radon release on the lunar surface. These three nuclides are radioactive daughters from the decay of U-238 hence the background level of alpha particle activity is a function of the lunar crustal uranium distribution. Radon reaches the lunar surface either at areas of high soil porosity or where fissures release the trapped gases in which radon is entrained. Once released, the radon spreads out by ``bouncing'' across the surface on ballistic trajectories in a random-walk process. The half-life of Rn-222 allows the gas to spread out by several hundred kilometers before it decays (depositing approximately half of the Po-218 recoil nuclides on the lunar surface) and allows the APS to detect gas release events up to several days after they occur. The long residence time of the Pb-210 precursor to Po-210 allows the mapping of gas vents which have been active over the last approximately 60 years. The APS found only a faint indication of Po-218 alpha particles. However, the Rn-222 alpha particle map shows that radon gas was emanating from the vicinity of craters Aristarchus and Kepler at the time of Lunar Prospector. The Po-210 alpha particle distribution reveals a variability in time and space of lunar gas release events. Po-210 and Rn-222 detections are associated with both thorium enhancements and lunar pyroclastic deposits.

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

2005-09-01

46

Interaction of alpha particles with bronchial cells.  

PubMed

The alpha-activity on the bronchial airways has been calculated for 222Rn daughter exposures producing observable excess bronchogenic lung cancer in underground miners. The activity distribution of aerosol particles with attached 222Rn daughters on the bronchial tree is truly diffuse because of the short half-life of the daughters and the large number of particles in the ambient aerosol. From the bronchial airway activity and the minor epidemiology, it can be shown that it requires, on average, 4 X 10(9) stem cells in bronchial epithelium to be hit in order to produce an observed lung cancer. For very high 222Rn daughter exposures of miners, multiply hit cells are highly probable; yet the lung cancer response is lower per unit exposure at high exposures than for mining exposures--near those sustained in the environment probably due to stem cell death. A knowledge of the number of multiply hit cells in miners permits some infererences to be made about the effectiveness of particulate versus diffusely distributed alpha emitters in the lung, namely, that particulates should not be significantly more effective in lung cancer induction than a diffuse distribution. PMID:2844698

Harley, N H

1988-10-01

47

Measurement of Alpha Particle Radioactivtiy in IC Device Packages  

Microsoft Academic Search

Alpha particle radioactivity in package materials has been shown to cause soft errors in semiconductor devices. The particles are emitted by uranium and thorium decay sequence radioactive isotopes present as trace impurities in the raw materials used to make the package component parts. Chemical and radiation analys s techniques were correlated to alpha particle fluxes, which range in value from

E. S. Meieran; P. R. Engel; T. C. May

1979-01-01

48

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

49

Alpha-Particle Gas-Pressure Sensor  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

50

Nuclear {alpha}-particle condensates: Definitions, occurrence conditions, and consequences  

SciTech Connect

There has been a recent flurry of interest in the possibility of condensates of {alpha} particles in nuclei. In this Rapid Communication we discuss occurrence conditions for such states. Using the quantality condition of Mottelson we show that condensates are only marginally expected in {alpha}-particle states. We proceed to demonstrate that few-body nuclear condensates are ill defined and emphasize the conflict between {alpha}-localization and {alpha}-condensate formation. We also explore the connection between Ikeda diagrams, linear chains, and Tonks-Girardeau gases. Our findings show that no new information is contained in the approximations of nuclear states as {alpha}-cluster condensates. Furthermore, condensates of more than three {alpha} particles are very unlikely to exist due to couplings to other degrees of freedom.

Zinner, N. T.; Jensen, A. S. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

2008-10-15

51

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.

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

2010-01-01

52

Elastic recoil detection analysis using ion-induced electron emission for particle identification  

Microsoft Academic Search

We propose a new method to identify particles in ERD analysis, using their electron emission yield from a thin carbon foil. Before the particles reach a silicon surface barrier detector (SB) they penetrate a set of thin foils (typically 6 foils) with a thickness of 3 mug\\/cm2 each). The emission yield depends on the nuclear charge of the penetrating ion

O. Benka; A. Brandsttter; E. Steinbauer

1994-01-01

53

Effect of alpha particles on Toroidal Alfven Eigenmodes  

SciTech Connect

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

Berk, H.L.

1992-11-01

54

The HERMES recoil detector  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

55

Recoil Based Fuel Breeding Fuel Structure  

SciTech Connect

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

Popa-Simil, Liviu [R and D, LAVM LLC., Los Alamos, NM, 87544 (United States)

2008-07-01

56

Full orbit calculation for lost alpha particle measurement on ITER  

SciTech Connect

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. [Department of Quantum Energy Science, Tohoku University, Sendai 980-8579 (Japan)

2008-10-15

57

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

58

Measurement of alpha particle energy using windowless electret ion chambers.  

PubMed

Electret ion chambers are inexpensive, lightweight, robust, commercially available, passive, charge-integrating devices for accurate measurement of different ionizing radiations. In an earlier work a chamber of dimensions larger than the range of alpha particles having aluminized Mylar windows of different thickness was used for measurement of alpha radiation. Correlation between electret mid-point voltage, alpha particle energy, and response was developed and it was shown that this chamber could be used for estimating the effective energy of an unknown alpha source. In the present study, the electret ion chamber is used in the windowless mode so that the alpha particles dissipate their entire energy inside the volume, and the alpha particle energy is determined from the first principles. This requires that alpha disintegration rate be accurately known or measured by an alternate method. The measured energies were within 1 to 4% of the true values for different sources (230Th, 237Np, 239Pu, 241Am, and 224Cm). This method finds application in quantitative determination of alpha energy absorbed in thin membrane and, hence, the absorbed dose. PMID:12240732

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

2002-10-01

59

Probing [alpha]-particle wave functions using ([ital [rvec d  

SciTech Connect

Wave functions of the [alpha] particle corresponding to different [ital S]- and [ital D]-state deuteron-deuteron overlaps, [l angle][ital dd][vert bar][alpha][r angle], were investigated using exact finite-range distorted-wave Born-approximation (DWBA) analyses of ([ital [rvec d

Crosson, E.R.; Lemieux, S.K.; Ludwig, E.J.; Thompson, W.J. (University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3255 (United States) Triangle Universities Nuclear Laboratory, Durham, North Carolina 27706 (United States)); Bisenberger, M.; Hertenberger, R.; Hofer, D.; Kader, H.; Schiemenz, P.; Graw, G. (Sektion Physik, Universitaet Muenchen, 8046 Garching (Germany)); Eiro, A.M.; Santos, F.D. (Departamento de Fisica, Universidade de Lisboa, 1700 Lisboa (Portugal))

1993-06-01

60

Alpha particle effects on the internal kink modes  

SciTech Connect

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

Wu, Yanlin; Cheng, C.Z.

1994-08-01

61

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

62

Model for alpha particle induced nuclear reactions: 93Nb(alpha,xalphaypzn) from 40-140 MeV  

Microsoft Academic Search

A comprehensive model is introduced for alpha particle induced nuclear reactions. Five different mechanisms are examined and discussed. These include inelastic scattering of the incident alpha particle, nucleon pickup, binary fragmentation, dissolution of the alpha in the nuclear field, and preequilibrium processes initiated by alpha-nucleon collisions. A series of experiments was performed to measure the excitation functions of many nuclides

Ettore Gadioli; Enrica Gadioli-Erba; James J. Hogan; Barbara V. Jacak

1984-01-01

63

Nuclear reaction diagnostics of fast confined and escaping alpha particles  

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 the energy distribution of confined fast alpha particles in tokamak plasmas. Reaction rates for Q-italic = 1 D-T plasmas are estimated. The design of and preliminary results from the prototype fusion gamma ray detector on the tokamak fusion test reactor (TFTR) will be presented. The activation reactions /sup 10/B(..cap alpha..,n-italic) /sup 13/N, /sup 14/N(..cap alpha..,..gamma..) /sup 18/F, /sup 25/Mg(..cap alpha..,p-italic) /sup 28/Al, and /sup 27/Al(..cap alpha..,p-italic) /sup 30/P are similarly examined as diagnostics of fast escaping alpha particles. Count rate estimates for Q-italic = 1 D-T plasmas will be presented.

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

1986-08-01

64

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

65

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

Microsoft Academic Search

A comprehensive model is introduced for alpha particle induced nuclear reactions. Five different mechanisms are examined and discussed. These include inelastic scattering of the incident alpha particle, nucleon pickup, binary fragmentation, dissolution of the alpha in the nuclear field, and preequilibrium processes initiated by alpha-nucleon collisions. A series of experiments was performed to measure the excitation functions of many nuclides

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

1984-01-01

66

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

67

The energetic alpha particle transport method EATM  

SciTech Connect

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

Kirkpatrick, R.C.

1998-02-01

68

Alpha-particle decays from excited states in 24Mg  

NASA Astrophysics Data System (ADS)

Using a cluster model based on the Woods-Saxon potential, alpha-particle decays from excited states in 24Mg have been systematically investigated. Calculations can in general reproduce experimental data, noticing the fact that the preformation factor P of alpha particle in alpha-decaying nuclei is of order from 100 to 10-2. This can be the evidence for the ?+20Ne structure in 24Mg. Meanwhile, the results also show the existence of other configurations, such as 16O+2 ?. Since the calculated decay widths are very sensitive to the angular momentum carried by the outgoing cluster ( ? particle), our results could serve as a guide to experimental spin assignments.

Wang, SiMin; Xu, Chen; Liotta, R. J.; Qi, Chong; Xu, FuRong; Jiang, DongXing

2011-08-01

69

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

70

MHD-Induced Alpha Particle Loss in TFTR  

SciTech Connect

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

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

1999-03-01

71

Probing. alpha. -particle wave functions by ( d ,. alpha. ) tensor analyzing powers  

SciTech Connect

Components of {alpha}-particle wave functions corresponding to {ital d}-{ital d} configurations are used to predict analyzing powers in the ({ital d},{alpha}) reaction. Tensor analyzing powers, especially {ital A}{sub {ital x}{ital x}}, are shown to clearly distinguish between wave functions generated by different realistic nucleon-nucleon interactions. Data for the {sup 58}Ni({ital d},{alpha}){sup 56}Co reaction to the 7{sup +} stretched-nucleon-orbital state at 2.283-MeV excitation in {sup 56}Co, measured with 22-MeV deuterons, are compared to predictions from the Argonne and Urbana interactions. Similar comparisons are made to data for the lowest {ital J} {sup {pi}}=7{sup +} state in {sup 48}Sc populated by the {sup 50}Ti({ital d},{alpha}){sup 48}Sc reaction at 16 MeV.

Crosson, E.R.; Das, R.K.; Lemieux, S.K.; Ludwig, E.J.; Thompson, W.J. (University of North Carolina, Chapel Hill, North Carolina 27599-3255 (United States) Triangle Universities Nuclear Laboratory, Durham, North Carolina 27706 (United States)); Bisenberger, M.; Hertenberger, R.; Hofer, D.; Kader, H.; Schiemenz, P.; Graw, G. (Sektion Physik, Universitaet Muenchen, 8046 Garching (Germany)); Eiro, A.M.; Santos, F.D. (Centro de Fisica Nuclear da Universidade de Lisboa, 1699 Lisboa Codex (Portugal))

1992-02-01

72

Scintillation response of liquid xenon to low energy nuclear recoils  

SciTech Connect

Liquid Xenon (LXe) is expected to be an excellent target and detection medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). We have measured the scintillation efficiency of nuclear recoils with kinetic energy between 10.4 and 56.5 keV relative to that of 122 keV gamma rays from {sup 57}Co. The scintillation yield of 56.5 keV recoils was also measured as a function of applied electric field, and compared to that of gamma rays and alpha particles. The Xe recoils were produced by elastic scattering of 2.4 MeV neutrons in liquid xenon at a variety of scattering angles. The relative scintillation efficiency is 0.130{+-}0.024 and 0.227{+-}0.016 for the lowest and highest energy recoils, respectively. This is about 15% less than the value predicted by Lindhard, based on nuclear quenching. Our results are in good agreement with more recent theoretical predictions that consider the additional reduction of scintillation yield due to biexcitonic collisions in LXe.

Aprile, E.; Giboni, K.L.; Majewski, P.; Ni, K.; Yamashita, M.; Hasty, R.; Manzur, A.; McKinsey, D.N. [Physics Department and Astrophysics Laboratory, Columbia University, New York, New York 10027 (United States); Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520 (United States)

2005-10-01

73

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

74

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

75

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

76

Bootstrap current induced by fusion born alpha particles  

SciTech Connect

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

Hsu, C.T.; Shaing, K.C.; Gormley, R.P.; Sigmar, D.J. (Massachusetts Institute of Technology, Plasma Fusion Center, 167 Albany Street, NW16-260, Cambridge, Massachusetts 02139 (United States))

1992-12-01

77

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

78

Energetic alpha particle deposition in a magnetized plasma  

NASA Astrophysics Data System (ADS)

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 calculated results is not high, it is approximately 6000 times faster.

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

79

Alpha-particle Measurements Needed for Burning Plasma Experiments  

SciTech Connect

The next major step in magnetic fusion studies will be the construction of a burning plasma (BP) experiment where the goals will be to achieve and understand the plasma behavior with the internal heating provided by fusion-generated alpha particles. Two devices with these physics goals have been proposed: the International Thermonuclear Experimental Reactor (ITER) and the Fusion Ignition Research Experiment (FIRE). Extensive conceptual design work for the instrumentation to try to meet the physics demands has been done for these devices, especially ITER. This article provides a new look at the measurements specifically important for understanding the physics aspects of the alpha particles taking into account two significant events. The first is the completion of physics experiments on the Joint European Torus (JET) and the Tokamak Fusion Test Reactor (TFTR) with deuterium-tritium fueling with the first chances to study alpha physics and the second is the realization that relatively compact plasmas, making use of advanced tokamak plasma concepts, are the most probable route to burning plasmas and ultimately a fusion reactor.

Kenneth M. Young

2001-09-26

80

PC-based analysis of alpha-particle spectra  

NASA Astrophysics Data System (ADS)

Recently developed personal-computer (PC) software performs analysis of alpha-particle spectra. The spectra are collected using a commercially available multichannel analyzer board in the PC, interfaced with up to eight alpha-particle detectors. The PC is an IBM PC-AT computer with a 20 Mbyte Bernoulli-Box removable cartridge disk, a math coprocessor and a printer. Once saved on disk, the spectra are analyzed using the software described here. The PC analysis software performs automatic peak-area determination with operator override. Sample analysis can use measured detector efficiencies or chemical yields obtained from a radionuclide spike or both. Background contribution corrections for all peaks are included. Upper limit values are calculated for nuclides specified by the operator and not found in the sample. Nuclide identification uses a master table of up to 64 nuclides with up to 8 alpha lines for each nuclide. Any one of 32 available subtables can be selected for use in an analysis. Analysis time is short and is limited by interaction with the operator, not by calculation time. Both detailed and summary versions of final results are printed for ease of data reporting. Utilities included with the software provide nuclide table editing, subset table editing, energy calibration, efficiency calibration and background analysis with background correction file update.

Chapman, Terry C.

1990-12-01

81

Pre-Equilibrium Alpha-Particle Emission as a Probe to Explore Alpha Clustering in Nuclei  

NASA Astrophysics Data System (ADS)

Experimental data of the double-differential spectra of light particles emitted at pre-equilibrium stage of nuclear processes were obtained at Laboratori Nazionali di Legnaro for the heavy-ion reactions 130 and 250 MeV 16O + 116Sn. Light charged particles were measured in coincidence with evaporation residues in order to avoid unwanted competing mechanisms. The experimental data were collected in a wide angular range from 29 to 82 degrees in the laboratory system. Theoretical model was developed in order to describe simultaneously evaporative and pre-equilibrium emission of the light particles in heavy-ion reactions. Griffin exciton model was used for the description of the pre-equilibrium stage of the compound nucleus formation, while the equilibrium evaporation processes were analyzed in the framework of the statistical theory of heavy-ion reactions. Experimental data were compared with the results of the model calculations and new approach was suggested to take into account alpha cluster formation in the projectile nucleus by measuring and analyzing pre-equilibrium alpha-particle spectra.

Kravchuk, V. L.; Fotina, O. V.; Gramegna, F.; Bruno, M.; D'Agostino, M.; Sambi, S.; Barlini, S.; Casini, G.

82

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

SciTech Connect

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

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

1984-01-01

83

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

84

Design consideration for high-energy-resolution neutron spectrometer based on associated particle detection using proton recoil telescope and time-of-flight technique for ITER  

NASA Astrophysics Data System (ADS)

For ion temperature measurement in the ITER high power operation phase, we propose a promising high-energy-resolution neutron spectrometer based on the associated particle detection using a proton recoil telescope and a time-of-flight spectrometer. To verify the operational principle and the basic performance of this system, we have set up a prototype system through Monte Carlo simulations and carried out a preliminary experiment with a deuterium-tritium (DT) neutron beam at the Fusion Neutronics Source, JAEA. The results have demonstrated that the energy resolution could be achieved around 3.3% (in full width at half maximum) for DT neutrons. In addition, the design consideration of this system for an application to ITER is given on the detection efficiency, the applicable range in the ITER operation, and the detector lifetime.

Naoi, N.; Asai, K.; Iguchi, T.; Watanabe, K.; Kawarabayashi, J.; Nishitani, T.

2006-10-01

85

Design consideration for high-energy-resolution neutron spectrometer based on associated particle detection using proton recoil telescope and time-of-flight technique for ITER  

SciTech Connect

For ion temperature measurement in the ITER high power operation phase, we propose a promising high-energy-resolution neutron spectrometer based on the associated particle detection using a proton recoil telescope and a time-of-flight spectrometer. To verify the operational principle and the basic performance of this system, we have set up a prototype system through Monte Carlo simulations and carried out a preliminary experiment with a deuterium-tritium (DT) neutron beam at the Fusion Neutronics Source, JAEA. The results have demonstrated that the energy resolution could be achieved around 3.3% (in full width at half maximum) for DT neutrons. In addition, the design consideration of this system for an application to ITER is given on the detection efficiency, the applicable range in the ITER operation, and the detector lifetime.

Naoi, N.; Asai, K.; Iguchi, T.; Watanabe, K.; Kawarabayashi, J.; Nishitani, T. [Quantum Engineering, Nagoya University, Furo-chou, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Japan Atomic Energy Agency, Tokai-mura, Naka, Ibaraki 319-1195 (Japan)

2006-10-15

86

Accounting for Recoil Effects in Geochronometers: A New Model Approach  

NASA Astrophysics Data System (ADS)

A number of geologically important chronometers are affected by, or owe their utility to, the "recoil effect". This effect describes the physical displacement of a nuclide due to energetic nuclear processes such as radioactive alpha decay (as in the case of various parent-daughter pairs in the uranium-series decay chains, and Sm-Nd), as well as neutron irradiation (in the case of the methodology for the 40Ar/39Ar dating method). The broad range of affected geochronometers means that the recoil effect can impact a wide range of dating method applications in the geosciences, including but not limited to: Earth surface processes, paleoclimate, volcanic processes, and cosmochemistry and planetary evolution. In particular, the recoil effect can have a notable impact on the use of fine grains (silt- and clay-sized particles) for geochronometric dating purposes. This is because recoil-induced loss of a nuclide from the surfaces of a grain can create an isotopically-depleted outer rind, and for small grains, this depleted rind can be volumetrically significant. When this recoil loss is measurable and occurs in a known time-dependent fashion, it can usefully serve as the basis for chronometers (such as the U-series comminution age method); in other cases recoil loss from fine particles creates an unwanted deviation from expected isotope values (such as for the Ar-Ar method). To improve both the accuracy and precision of ages inferred from geochronometric systems that involve the recoil of a key nuclide from small domains, it is necessary to quantify the magnitude of the recoil loss of that particular nuclide. It is also necessary to quantitatively describe the effect of geological processes that can alter the outer surface of grains, and hence the isotopically-depleted rind. Here we present a new mathematical and numerical model that includes two main features that enable enhanced accuracy and precision of ages determined from geochronometers. Since the surface area of the dated grain is a major control on the magnitude of recoil loss, the first feature is the ability to calculate recoil effects on isotopic compositions for realistic, complex grain shapes and surface roughnesses. This is useful because natural grains may have irregular shapes that do not conform to simple geometric descriptions. Perhaps more importantly, the surface area over which recoiled nuclides are lost can be significantly underestimated when grain surface roughness is not accounted for, since the recoil distances can be of similar characteristic lengthscales to surface roughness features. The second key feature is the ability to incorporate dynamical geologic processes affecting grain surfaces in natural settings, such as dissolution and crystallization. We describe the model and its main components, and point out implications for the geologically-relevant chronometers mentioned above.

Lee, V. E.; Huber, C.

2012-12-01

87

Thick Source Alpha Particle Spectroscopy: Possibilities And Prospects  

NASA Astrophysics Data System (ADS)

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

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

88

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

89

Nuclear Recoil Background Evaluation for WIMP Searches  

Microsoft Academic Search

Nuclear recoils produced by neutrons, alphas and neutrinos as they scatter from target nuclei are important sources of background which must be considered in WIMP searches. PMTs and other detector components may contribute neutrons which generate a source of background. Alphas on the surface of the vessel can also be a serious issue for some of the experiments. And, neutrino-induced

Dongming Mei; Andrew Hime; Christina Keller; Zhongbao Yin

2007-01-01

90

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

91

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

92

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

93

Enhanced production of low energy electrons by alpha particle impact  

PubMed Central

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

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

2011-01-01

94

Stopping power for alpha particles in organic liquids and vapours  

NASA Astrophysics Data System (ADS)

The stopping power for 5.5 MeV alpha particles has been studied in liquid and vapour phases of water, methanol, ethanol, propanol, pentane, hexane, cyclohexane, heptane and octane. Experimental values for stopping powers in the range 5.5 MeV to 0.5 MeV have been extracted by fitting the range-energy data with polynomial and inverse stopping power functions, and compared with existing results. The effect of phase of the absorber on the stopping power has been clearly demonstrated, the stopping power being higher in the vapour phase. Mean values of the excitation potential have been deduced from the experimental stopping powers after allowing for shell, Barkas and Bloch corrections, which are then compared with the recommended values of Berger and Seltzer.

Haque, A. K. M. M.; Nikjoo, H.

1991-01-01

95

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

SciTech Connect

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

Kirsebom, O. S.; Fynbo, H. O. U.; Hyldegaard, S.; Riisager, K. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Alcorta, M.; Borge, M. J. G.; Cubero, M.; Dominguez-Reyes, R.; Madurga, M.; Perea, A.; Tengblad, O. [Instituto de Estructura de la Materia, CSIC, ES-28006 Madrid (Spain); Diget, C. A.; Fulton, B. R. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Fraile, L. M. [PH Department, CERN, CH-1211 Geneva 23 (Switzerland); Jonson, B.; Nilsson, T.; Nyman, G. [Fundamental Physics, Chalmers University of Technology, SE-41296 Goeteborg (Sweden); Munoz Martin, A. [CMAM, Universidad Autonoma de Madrid, Cantoblanco, ES-28049 Madrid (Spain)

2010-06-15

96

Destabilization of tokamak pressure-gradient driven instabilities by energetic alpha-particle populations  

SciTech Connect

This paper reports on alpha-particle populations that can significantly alter existing magnetohydrodynamic (MHD) instabilities in tokamaks through kinetic effects and coupling to otherwise stable shear Alfven waves. Resonances of the trapped alpha-particle precessional drift, with the usual ballooning mode diamagnetic frequency ({omega}{sub *i}/2) and the toroidicity-induced Alfven eigenmode (TAE), are considered. These are examined for noncircular tokamaks in the high-n ballooning limit using an isotopic alpha-particle slowing down distribution and retaining the full-energy and pitch-angle dispersion in the alpha-particle drift frequency. Applying this to the Compact Ignition Tokamak (CIT) and the International Thermonuclear Experimental Reactor (ITER) indicates that ballooning instabilities can persist at betas below the ideal MHD threshold. These are especially dominated by the destabilization of the TAE mode. In addition, a hybrid fluid-particle approach for simulating alpha-particle effects on pressure-gradient driven instabilities is described.

Spong, D.A.; Holmes, J.A.; LeBoeuf, J.N.; Christenson, D.J. (Oak Ridge National Lab., TN (United States))

1990-11-01

97

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

SciTech Connect

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

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

1992-07-01

98

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

SciTech Connect

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

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

1992-07-01

99

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

100

Explanation of the Anomalously Small Absorption of alpha Particles in exp 40 Ca Nuclei.  

National Technical Information Service (NTIS)

The reduced absorption at lower alpha particle energies (approximately 30 MeV) which is necessary to describe the anomalous large angle scattering of alpha particles from exp 40 Ca nuclei is explained by the angular momentum mismatch between the entrance ...

R. Planeta H. Dabrowski L. Freindl K. Grotowski

1979-01-01

101

A global 2.5-dimensional three fluid solar wind model with alpha particles  

Microsoft Academic Search

A global 2.5-dimensional three fluid solar wind model is presented. Two ion species, namely protons and alpha particles, are heated by an empirical energy flux while electrons are heated by the classical heat flux and Coulomb coupling with ions. It is found that for a reasonable relative speed between alpha particles and protons at 1 AU to be achieved, the

Bo Li; Xing Li; Nicolas Labrosse

2006-01-01

102

Analysis and experiment of an alpha particle emitter probe capable of direct air density measurements  

Microsoft Academic Search

A probe has been tested which can directly measure air densities. The probe uses an alpha-particle emitter (sealed Polonium 210), a surface barrier detector, filter amplifiers and sample\\/hold electronics for signal processing. The measurement of the residual energy of alpha particles directly relates to density of the medium they pass through, provided its composition is known. Optimum performance of such

R. A. Golobic; W. J. Honea

1978-01-01

103

One-Step Acceleration of Deuterons and alpha -Particles at the JINR Synchrophasotron.  

National Technical Information Service (NTIS)

The problems are considered which are related to one-step acceleration mode of deuterons and alpha -particles at the JINR synchrophasotron. The one-step mode of acceleration of deuteron and alpha -particles has been realized by widening the driving oscill...

A. I. Mikhailov G. P. Puchkov K. V. Chekhlov

1976-01-01

104

Ion Densities and Particle Charges for Alpha Ionization in an Aerosol Atmosphere: Columnar Recombination Corrections  

Microsoft Academic Search

Ionization by alpha sources in an environment containing small aerosol particles is of interest in aerosol neutralizes, particle chargers and atmospheric electricity. It is known that the conventional ion-balance equation is inadequate in describing the bulk ion densities for alpha sources in view of the columnar recombination process. An earlier self-consistent formulation to include this effect is extended to the

Y. S. Mayya; W. Hollnder

1995-01-01

105

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

106

The Rosetta Alpha Particle X-Ray Spectrometer (APXS)  

NASA Astrophysics Data System (ADS)

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

Klingelhfer, G.; Brckner, J.; D'Uston, C.; Gellert, R.; Rieder, R.

2007-02-01

107

Alpha particle detection with GaN Schottky diodes  

SciTech Connect

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

Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Markov, A. V.; Kozhukhova, E. A.; Gazizov, I. M. [Institute of Rare Metals, B. Tolmachevsky 5, Moscow 119017 (Russian Federation); Kolin, N. G.; Merkurisov, D. I.; Boiko, V. M.; Korulin, A. V. [Obninsk Branch of Federal State Unitary Enterprise, Karpov Institute of Physical Chemistry, Kiev Avenue, Kaluga Region, Obninsk 249033 (Russian Federation); Zalyetin, V. M. [Institute of Physical-Technical Problems, Dubna (Russian Federation); Pearton, S. J. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Lee, I.-H. [School of Advanced Materials Engineering and Research Center for Advanced Materials Development, Chonbuk National University, Chonju 561-756 (Korea, Republic of); Dabiran, A. M.; Chow, P. P. [SVT Associates, Inc., 7620 Executive Drive, Eden Prairie, Minnesota 55344 (United States)

2009-11-15

108

High-resolution alpha-particle spectrometry of the 230U decay series.  

PubMed

High-resolution alpha-particle spectrometry was performed on the (230)U decay series. A (230)U source was prepared on a stainless steel disc by electrodeposition in an ammonium nitrate solution. Spectrometry of the alpha-particle energy spectrum was performed with ion-implanted planar silicon detectors in vacuum. A set of alpha emission probabilities is presented for (230)U and (226)Th. The measured peak intensities were corrected mathematically for coincidental detection of alpha-particles and conversion electrons emitted in the same decay. A good agreement with literature data was observed. The uncertainty budget and the correlation matrix are presented. The validity of the alpha-particle energies was tested and could be confirmed for most peaks within a few keV, but discrepancies were found for the 2nd peak of (226)Th and the main peak of (218)Rn. PMID:22424835

Marouli, M; Pomm, S; Paepen, J; Van Ammel, R; Jobbgy, V; Dirican, A; Suliman, G; Stroh, H; Apostolidis, C; Abbas, K; Morgenstern, A

2012-09-01

109

Microscopic study of 4{alpha}-particle condensation with inclusion of resonances  

SciTech Connect

The 4{alpha} condensate state for {sup 16}O is discussed with the Tohsaki-Horiuchi-Schuck-Roepke (THSR) wave function which has {alpha}-particle condensate character. With a treatment of resonances, it is found that the 4{alpha} THSR wave function yields a fourth 0{sup +} state in the continuum above the 4{alpha}-breakup threshold, in addition to the three 0{sup +} states obtained in a previous analysis. It is shown that this fourth 0{sup +} [(0{sub 4}{sup +}){sub THSR}] state has a structure analogous to that of the Hoyle state because it has a very dilute density and a large component of {alpha}+{sup 12}C(0{sub 2}{sup +}) configuration. Furthermore, single-{alpha} motions are extracted from the microscopic 16-nucleon wave function, and the condensate fraction and momentum distribution of {alpha} particles are quantitatively discussed. It is found that for the (0{sub 4}{sup +}){sub THSR} state a large {alpha}-particle occupation probability concentrates on a single-{alpha} 0S orbit and the {alpha}-particle momentum distribution has a {delta}-function-like peak at zero momentum, both indicating that the state has a strong 4{alpha} condensate character. It is argued that the (0{sub 4}{sup +}){sub THSR} state is the counterpart of the 0{sub 6}{sup +} state which was obtained as the 4{alpha} condensate state in the previous 4{alpha} orthogonality condition model calculation and therefore is likely to correspond to the 0{sub 6}{sup +} state observed at 15.1 MeV. The necessity of including {alpha}+{sup 12}C configurations in the THSR wave function is pointed out.

Funaki, Y. [Institute of Physics, University of Tsukuba, Tsukuba 305-8571 (Japan); Yamada, T. [Laboratory of Physics, Kanto Gakuin University, Yokohama 236-8501 (Japan); Tohsaki, A. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 567-0047 (Japan); Horiuchi, H. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 567-0047 (Japan); International Institute for Advanced Studies, Kizugawa 619-0225 (Japan); Roepke, G. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); 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 et Universite Joseph Fourier, 25 Av. des Martyrs, BP 166, F-38042 Grenoble Cedex 9 (France)

2010-08-15

110

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

NASA Astrophysics Data System (ADS)

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

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

2004-10-01

111

Biocompatibility enhancement of chemically etched CR39 SSNTDs through superficial pore formation by alpha-particle irradiation  

Microsoft Academic Search

Alpha-particle radiobiological experiments involve irradiating cells with alpha particles and require thin biocompatible materials as substrates for cell cultures, which can record alpha-particle transversals. CR-39 SSNTDs with a thickness of about 20?m are suitable substrates. In the present work, the biocompatibility enhancement of these thin CR-39 SSNTDs is studied through superficial pore formation by alpha-particle irradiation. HeLa cells were cultured

C. K. M. Ng; K. F. Chan; W. Y. Li; A. K. W. Tse; W. F. Fong; T. Cheung; K. N. Yu

2008-01-01

112

Test procedure for gross alpha-particle activity in drinking water: interlaboratory collaborative study  

SciTech Connect

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 counting efficiency. A secondary purpose in the study was to see how well the Ra-226 concentration of a drinking-water sample could be estimated from an early gross alpha count subtracted from a late gross alpha count and calculated from the equation provided in the test procedure. The method for gross alpha-particle concentration measurement eliminates the dissolved solids interference problem (which is a significant problem for the EPA-approved method) and provides for greater sensitivity by allowing for the use of much larger samples in the analysis.

Whittaker, E.L.

1986-08-01

113

Alpha-particle effects on high-n instabilities in tokamaks  

SciTech Connect

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

Rewoldt, G.

1988-06-01

114

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

PubMed

In this paper we present a method for the measurement of alpha particle energy using polycarbonate materials as nuclear track detectors (NTDs). This method is based on the interaction of the radiation with the solid-state materials, using the relationship between the energy deposited in the material by the ionising particle and the track developed after an established chemical process. The determination of the geometrical parameters of the formed track, such as major axis, minor axis and overall track length, permit determination of the energy of the alpha particle. The track analysis is performed automatically using a digital image system, and the data are processed in a PC with commercial software. In this experiment 148Gd, 238U, 230Th, 239Pu and 244Cm alpha particle emitters were used. The values for alpha particle energy resolution, the linear response to energy, the confidence in the results and the automatisation of the procedure make this method a promising analysis system. PMID:12382812

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

2002-01-01

115

Alpha particles in field-aligned beams upstream of the bow shock - Simulations  

NASA Technical Reports Server (NTRS)

The possibility that field-aligned ion beams (FABs) formed by direct reflection could contain alpha particles is studied using self-consistent hybrid simulations of an oblique collisionless, supercritical shock. It is found that alpha particles can backstream from a shock in which the angle between the shock normal and the upstream magnetic field is 45 degrees. The deficit of alpha particles in the FABs, expressed as a relative density ratio to H(+) normalized to the solar wind He(2+) to H(+) density ratio, varies between about 0.1 and less than 0.01 and depends on the upstream H(+) and He(2+) temperatures.

Burgess, D.

1989-01-01

116

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

117

WIND measurements of proton and alpha particle flow and number density  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

118

The continuum and the alpha-particle formation  

Microsoft Academic Search

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

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

1988-01-01

119

Decay data measurements on 213Bi using recoil atoms.  

PubMed

In this work, (213)Bi has been separated from an open (225)Ac source by collecting recoil atoms onto a glass plate in vacuum. The activity of such recoil sources has been measured as a function of time, using an ion-implanted planar Si detector in quasi-2? geometry. From these measurements, a new half-life value of T1/2((213)Bi)=45.62 (6)min was derived. Additionally, high-resolution alpha-spectrometry measurements were performed at a solid angle of 0.4% of 4?sr, to verify the energies and emission probabilities of the ?-emissions from (213)Bi. Using (225)Ac, (221)Fr, (217)At and (213)Po peaks as reference peaks, the measured (213)Bi ?-peak energies at E?,0=5878 (4)keV and E?,1=5560 (4)keV were about 10keV higher than validated data. The relative ?-particle emission probabilities of (213)Bi, P?,0=0.9155 (11) and P?,1=0.0845 (11), and the (213)Bi alpha branching factor, P?=1-P?=2.140 (10)%, are compatible with recommended values, but have a higher accuracy. PMID:23416406

Marouli, M; Suliman, G; Pomm, S; Ammel, R Van; Jobbgy, V; Stroh, H; Dikmen, H; Paepen, J; Dirican, A; Bruchertseifer, F; Apostolidis, C; Morgenstern, A

2013-04-01

120

CIT alpha particle extraction and measurement: Low-Z ablation cloud profile simulation for alpha-particle diagnostics  

SciTech Connect

In order to determine the expected properties of the ablation cloud of low-Z pellets interacting with a thermonuclear plasma, which in turn is proposed as a charge-neutralization medium for confined alpha particles, a numerical program has been developed. The physical model for this program is based on Parks' low-Z pellet-plasma interaction model for the interior of the cloud adjacent to the pellet's surface out to the sonic surface (roughly, a millimeter in separation) and then propagating outward from this region using the conservation laws of enthalpy, momentum, and mass, along with the assumption of charge-state equilibrium. The effects of local heating by the plasma electrons slowing down in the cloud, and ionization of the ablatant material are treated self-consistently in the model. In collaboration with Dr. Paul Parks of General Atomics Corporation, a joint ODU-GAC research plan for modeling low-Z pellet-plasma interactions has been devised, and considerable progress has been made in its implementation. Recently, using a constraint in the ablatant flow, results from the program were obtained which could be compared with the results from the GAC experiments on TEXT. The predictions of the program are in pretty good agreement with the TEXT data as to the dimensions of the C{sup +3} region of the cloud along the magnetic field. Also a small improvement has been made in the low-Z pellet plasma-penetration program, which brings the predictions of the model in closer agreement with the carbon pellet injection experiments on TFTR. 22 refs., 3 figs.

Gerdin, G.; Vahala, L.; El Cashlan, A.G.

1990-01-01

121

Some Calculations for exp 12 C in the alpha Particle Model.  

National Technical Information Service (NTIS)

The exp 12 C nucleus as three finite structurelesse alpha particles interacting through phenomenological potentials due to Ali and Bodmer is represented. These potentials are angular-momentum dependent and reproduce the experimental phase shifts delta sub...

V. C. Aguilera-Navarro O. Portilho

1976-01-01

122

Oncogenic Transformation of Mammalian Cells by Ultrasoft X-Rays and Alpha Particles  

NASA Astrophysics Data System (ADS)

For a better understanding of oncogenic cell transformation by ionizing radiation, we conducted experiments with ultrasoft X rays and low energy alpha particles. Confluent C3HlOTl/2 cells were irradiated by Al-K (1.5 keV) X rays or alpha particles from plutonium through a thin mylar sheet, on which the cells attached and grew. Our results indicated that Al-K X rays were more effective in causing cell inactivation and oncogenic transformation than 60Co gamma rays but less effective than 1.0 and 3.7 MeV alpha particles. There was no significant difference between 1.0 and 3.7 MeV alpha particles in transforming cells although the latter were slightly more effective than the former in producing lethal effect. These results indicated that track structure is important in causing biological effects by ionizing radiation

Yang, T. C.; Craise, L. M.; Raju, M. R.

123

CONCERNING THE MULTIPLE-WIRE SPARK COUNTER FOR ALPHA-PARTICLE DETECTION  

Microsoft Academic Search

A guard-wire type of multiple-wire spark counter for alpha-particle ; detection is designed and its operating characteristics studied. It appears that ; its counting properties approach those of the multiple wire-cavity spark counter. ; (auth);

G. Singh; N. K. Saha

1963-01-01

124

Thermoluminescence and Coloration of Lithium Fluoride Produced by Alpha Particles, Electrons, Gamma Rays, and Neutrons  

Microsoft Academic Search

The coloration and thermoluminescence produced in LiF by 2 Mev alpha particles, by 2 Mev electrons, by 1 Mev gamma rays from Co60, and by thermal neutrons are described. The energy initially required to produce an F center varies. It is about 700 ev for alpha, 140 ev for beta, 65 ev for gamma rays, and 65 ev for thermal

Frederick F. Morehead; Farrington Daniels

1957-01-01

125

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

126

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

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

127

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

SciTech Connect

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

Avrigeanu, V.; Avrigeanu, M. [Horia Hulubei National Institute for Physics and Nuclear Engineering, POBox MG-6, 077125 Magurele, Ilfov (Romania)

2012-11-20

128

Relative Yields of Ions Produced by alpha-Particles in Air and Water Vapour  

Microsoft Academic Search

IN continuation1 of the examination of the radiological properties of water, the yield of ion-pairs in water vapour under the action of alpha-particles has been compared with the yield in air. A sector-shaped parallel-plate ionization chamber containing either water vapour at 95 C. or air has been exposed to a semi-collimated beam of 5.0-MeV. alpha-particles derived from a polonium source.

R. K. Appleyard

1949-01-01

129

On resonant excitations of high-n magnetohydrodynamic modes by energetic/alpha particles in tokamaks  

SciTech Connect

Analytical theories for the excitations in tokamaks of magnetohydrodynamic (MHD) modes with large toroidal mode numbers (n>>1) are presented. Specifically, only instability mechanisms due to resonances with energetic ions/alpha particles are considered. It is noted that, while trapped energetic particles contribute to the ideal region, circulating energetic particles contribute mainly to the singular layer dynamics. A unified dispersion relation manifesting both fishbone-like modes and beam transit-resonance modes is then driven. Finally, we also analyze the stability property of toroidicity-induced shear Alfven waves excited via transit resonances with alpha particles in ignited tokamaks. 11 refs.

Chen, Liu

1989-03-01

130

Investigation of the reactions {alpha}p {yields} tpp and {alpha}p {yields} {tau}pn induced by 2.7-GeV/c {alpha} particles  

SciTech Connect

The underlying mechanisms of the reactions {alpha}p {yields} tpp and {alpha}p {yields} {tau}pn are studied. Data from the ITEP two-meter bubble chamber filled with liquid hydrogen and irradiated by a 2.7-GeV/c separated {alpha}-particle beam are analyzed. The total cross sections for the two reactions are estimated at 20.7 {plus_minus} 0.4 and 34.4 {plus_minus} 0.4 mb, respectively. The phase-space domains in which quasifree scattering and final-state interactions play leading roles are isolated. The angular, momentum, and invariant-mass distributions of secondary particles are a obtained over the entire allowed kinematic range. In the region of quasifree scattering, the data are compared with the pole-model predictions. 25 refs., 8 figs.

Blinov, A.V.; Grechko, V.E.; Zombkovsky, S.M. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)] [and others

1995-10-01

131

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

132

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

133

Monte Carlo Calculations of Suprathermal Alpha Particles Trajectories in the Rippled Field of TFTR  

Microsoft Academic Search

We study the transport of suprathermal alpha particles and their energy deposition into electrons, deuterons, tritons and carbon-12 impurity in the rippled field of TFTR. The Monte Carlo code (Punjabi A., Boozer A., Lam M., Kim M., and Burke K., J. Plasma Phys.), 44, 405 (1990) developed by Punjabi and Boozer for the transport of plasma particles due to MHD

Alkesh Punjabi; Maria Lam; Allen Boozer

1996-01-01

134

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

Microsoft Academic Search

The formation of etched tracks in solid-state nuclear track detectors is usually described by assuming an unequivocal correlation of the etch-rate ratio with the energy loss of charged particles. For alpha particles, this assumption could be verified within the scatter of the experimental data. In this article, the dependence of the depth (x) on the track etch rate (VT) was

M. F. Zaki; Tarek M. Hegazy; U. Seddik; A. Ahmed Morsy

2005-01-01

135

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

136

Alpha particle source for radiolysis of gaseous systems  

Microsoft Academic Search

A mechanically stable AmO alpha source for use in gas ; radiolysis was made by depositing americium nitrate, from a suspension, on both ; sides of a platinum disk and calcining at 500 to 550 deg C. In all, 50 layers ; were deposited on each side of the disk, giving a thickness of 0.3 mg\\/cm² ; ond a total

K. Ezerska; M. Fopys

1973-01-01

137

The continuum and the alpha-particle formation  

Microsoft Academic Search

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

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

1988-01-01

138

Alpha CAM filter particle collection pattern study results.  

National Technical Information Service (NTIS)

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 us...

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

1992-01-01

139

Absorbed fractions for alpha-particles in tissues of cortical bone  

NASA Astrophysics Data System (ADS)

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

Watchman, Christopher J.; Bolch, Wesley E.

2009-10-01

140

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

141

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

142

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

143

Mechanics and multiple-particle tracking microheterogeneity of alpha-actinin-cross-linked actin filament networks.  

PubMed Central

Cell morphology is controlled by the actin cytoskeleton organization and mechanical properties, which are regulated by the available contents in actin and actin regulatory proteins. Using rheometry and the recently developed multiple-particle tracking method, we compare the mechanical properties and microheterogeneity of actin filament networks containing the F-actin cross-linking protein alpha-actinin. The elasticity of F-actin/alpha-actinin networks increases with actin concentration more rapidly for a fixed molar ratio of actin to alpha-actinin than in the absence of alpha-actinin, for networks of fixed alpha-actinin concentration and of fixed actin concentration, but more slowly than theoretically predicted for a homogeneous cross-linked semiflexible polymer network. These rheological measurements are complemented by multiple-particle tracking of fluorescent microspheres imbedded in the networks. The distribution of the mean squared displacements of these microspheres becomes progressively more asymmetric and wider for increasing concentration in alpha-actinin and, to a lesser extent, for increasing actin concentration, which suggests that F-actin networks become progressively heterogeneous for increasing protein content. This may explain the slower-than-predicted rise in elasticity of F-actin/alpha-actinin networks. Together these in vitro results suggest that actin and alpha-actinin provides the cell with an unsuspected range of regulatory pathways to modulate its cytoskeleton's micromechanics and local organization in vivo.

Tseng, Y; Wirtz, D

2001-01-01

144

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

SciTech Connect

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

Brede, H.J.; Dietze, G.; Klein, H.; Schoelermann, H. (Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-3300 Braunschweig (DE))

1991-01-01

145

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

146

Kinetic Approach for Studying the Alpha Particle Transport in Plasma Liner Driven Magnetized Target Fusion  

NASA Astrophysics Data System (ADS)

A new promising concept for producing energy from thermonuclear fusion is magnetized target fusion (MTF). In MTF, an imploding material liner is used to compress magnetized plasma to fusion ignition and to inertially confine the resulting burning plasma to obtain the necessary energy gain. Plasma liners have the potential to be formed in a repeatable, standoff manner and allow for the possibility of secondary fusion burn in the liner, which allows for much higher fusion energy yields and relaxes the density and scale length requirements of the magnetized target. To date, no theoretical effort has adequately addressed the issue of thermal transport of high-energy alpha particles from the target to the liner. Although the liner/target system is highly collisional at ignition, the fast alpha particle mean free path is relatively large resulting in nonlocal deposition of the kinetic energy into the liner. Thus, a fluid approach may not be appropriate for assessing the possibility of secondary burn. A MATLAB computer code was developed that numerically modeled the alpha particles, electrons, and Deuterons using distribution functions. These distribution functions were separately evolved over time using the Boltzmann equation for the plasma transport and the nonlinear Fokker-Planck equation for the collisions between the alpha particles and the electrons and Deuterons. Preliminary results from this work shows that the alpha particles collide with the initially at rest Deuterons and transfer enough energy so that both species move outward away from the target. In addition, some of the Deuterons reach fusion burn energies.

Sommer, James

2003-10-01

147

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

PubMed

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

Sibbens, G; Pomm, S; Altzitzoglou, T; Garca-Torao, E; Janssen, H; Dersch, R; Ott, O; Snchez, A Martn; Montero, M P Rubio; Loidl, M; Coron, N; de Marcillac, P; Semkow, T M

2010-01-01

148

Study of nuclear recoils in liquid argon with monoenergetic neutrons  

NASA Astrophysics Data System (ADS)

In the framework of developments for liquid argon dark matter detectors we assembled a laboratory setup to scatter neutrons on a small liquid argon target. The neutrons are produced mono-energetically (Ekin = 2.45 MeV) by nuclear fusion in a deuterium plasma and are collimated onto a 3" liquid argon cell operating in single-phase mode (zero electric field). Organic liquid scintillators are used to tag scattered neutrons and to provide a time-of-flight measurement. The setup is designed to study light pulse shapes and scintillation yields from nuclear and electronic recoils as well as from alpha particles at working points relevant for dark matter searches. Liquid argon offers the possibility to scrutinise scintillation yields in noble liquids with respect to the population strength of the two fundamental excimer states. Here we present experimental methods and first results from recent data towards such studies.

Regenfus, C.; Allkofer, Y.; Amsler, C.; Creus, W.; Ferella, A.; Rochet, J.; Walter, M.

2012-07-01

149

Analysis of alpha3 GlyR single particle tracking in the cell membrane.  

PubMed

Single particle tracking (SPT) of transmembrane receptors in the plasma membrane often reveals heterogeneous diffusion. A thorough interpretation of the displacements requires an extensive analysis suited for discrimination of different motion types present in the data. Here the diffusion pattern of the homomeric alpha3-containing glycine receptor (GlyR) is analyzed in the membrane of HEK 293 cells. More specifically, the influence of the alpha3 RNA splice variants alpha3K and alpha3L on lateral membrane diffusion of the receptor is revealed in detail. Using a combination of ensemble and local SPT analysis, free and anomalous diffusion parameters are determined. The GlyR alpha3 free diffusion coefficient is found to be 0.13 +/- 0.01 microm2/s and both receptor variants display confined motion. The confinement probability level and residence time are significantly elevated for the alpha3L variant compared to the alpha3K variant. Furthermore, for the alpha3L GlyR, the presence of directed motion was also established, with a velocity matching that of saltatory vesicular transport. These findings reveal that alpha3 GlyRs are prone to different types of anomalous diffusion and reinforce the role of RNA splicing in determining lateral membrane trafficking. PMID:24316136

Notelaers, Kristof; Rocha, Susana; Paesen, Rik; Smisdom, Nick; De Clercq, Ben; Meier, Jochen C; Rigo, Jean-Michel; Hofkens, Johan; Ameloot, Marcel

2014-03-01

150

Experimental Studies of ZnS Alpha Particle Counters and Methods for Minimizing Detector Background  

Microsoft Academic Search

The zinc sulfide scintillation counter employed at IBM for low-level alpha flux monitoring of device and packaging materials is described. This counter provides almost 100% counting efficiency for alpha particles of 1.5MeV or greater energy emitted from the surface of planar samples up to 130 cm2 in area, and exhibits a sea level background count rate on the order of

B. J. Masters

1980-01-01

151

Ultra-low background alpha particle counter using pulse shape analysis  

Microsoft Academic Search

The need to measure alpha particle emissivities at levels below 0.005 ?\\/cm2-hr is becoming increasingly important in fundamental physics experiments (e.g. neutrino and rare decay measurements), environmental monitoring, nuclear activities monitoring and semiconductor packaging materials. Present counters can barely reach this level, being limited both by cosmic ray events and by their own alpha emissions. Here we report a detector

W. K. Warburton; Brendan Dwyer-McNally; Michael Momayezi; John E. Wahl

2004-01-01

152

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

153

Mode coupling effects on alpha-particle-driven long wavelength Alfven wave instability  

SciTech Connect

It is demonstrated both analytically and numerically that mode couplings play an important role in the nonlinear evolution of alpha-particle-driven [ital long] [ital wavelength] Alfven wave instabilities. The mode coupling process is characterized by a beat between two linearly unstable Alfven waves having opposite frequencies, which generates a linearly stable, static (zero frequency) mode. The backreaction of the static mode tends to stabilize the Alfven instabilities by eliminating the phase shift between the alpha pressure and the Alfven fluctuations.

Gang, F.Y. (Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)); Leboeuf, J. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States))

1993-08-01

154

Study of alpha-particle emission probabilities and energies in the decay of 240Pu.  

PubMed

In the frame of EUROMET Project No 325 "Analysis of Plutonium Alpha-Particle Spectra", the isotopic composition of a 238, 239, 240Pu mixture was measured by mass spectrometry and by high-resolution alpha-particle spectrometry. The latter revealed a discrepancy with published data of the alpha-particle emission probabilities (Palpha) and the energies (Ealpha) of the two major peaks of 240Pu. New values have been derived: Palpha1 = 0.7256 (6), Palpha2 = 0.2735 (7) and Ealpha1 = 5168.54 (14)keV, Ealpha2 = 5124.10 (15)keV, relative to reference peaks of 238Pu and 239Pu. PMID:14987635

Sibbens, G; Pomm, S

2004-01-01

155

Feasibility of alpha particle measurement in a magnetically confined plasma by CO2 laser Thomson scattering  

NASA Astrophysics Data System (ADS)

Fusion-product alpha particles will dominate the behavior of the next generation of ignited D-T fusion reactors. Advanced diagnostics will be required to characterize the energy deposition of these fast alpha particles in the magnetically confined plasma. For small-angle coherent Thomson scattering of a CO2 laser beam from such a plasma, a resonance in the scattered power occurs near 90 degrees with respect to the magnetic field direction. This spatial concentration permits a simplified detection of the scattered laser power from the plasma using a heterodyne system. The signal produced by the presence of fusion-product alpha particles in an ignited plasma is calculated to be well above the noise level, which results from statistical variations of the background signal produced by scattering from free electrons.

Richards, R. K.; Vandersluis, K. L.; Hutchinson, D. P.

1987-08-01

156

The 1997 IAEA intercomparison of commercially available PC-based software for alpha-particle spectrometry  

NASA Astrophysics Data System (ADS)

Four commercially available, PC-based analysis programs for alpha-particle spectrometry were compared using the 1997 IAEA test spectra, i.e. AlphaVision 1.20 (EG&G Ortec, USA), Alps 4.21 (Westmeier GmbH, Germany), Winner Alpha 4.0f5 (Eurisys Mesures, France) and Genie-2000 (Canberra Industries Inc., USA). A systematic statistical study of the analysis results was performed based on z-scores. The results indicate that the four programs leave room for substantial improvement.

Blaauw, M.; Garca-Torao, E.; Woods, S.; Fazinic, S.

1999-06-01

157

Alfvenic behavior of alpha particle driven ion cyclotron emission in TFTR  

SciTech Connect

Ion cyclotron emission (ICE) has been observed during D-T discharges in the Tokamak Fusion Test Reactor (TFTR), using rf probes located near the top and bottom of the vacuum vessel. Harmonics of the alpha cyclotron frequency ({Omega}{sub {alpha}}) evaluated at the outer midplane plasma edge are observed at the onset of the beam injection phase of TFTR supershots, and persist for approximately 100-250 ms. These results are in contrast with observations of ICE in JET, in which harmonics of {Omega}{sub {alpha}} evolve with the alpha population in the plasma edge. Such differences are believed to be due to the fact that newly-born fusion alpha particles are super-Alfvenic near the edge of JET plasmas, while they are sub-Alfvenic near the edge of TFTR supershot plasmas. In TFTR discharges with edge densities such that newly-born alpha particles are super-Alfvenic, alpha cyclotron harmonics are observed to persist. These results are in qualitative agreement with numerical calculations of growth rates due to the magnetoacoustic cyclotron instability.

Cauffman, S.; Majeski, R. [Princeton Plasma Physics Lab., NJ (United States); McClements, K.G. [UKAEA Government Division, Oxfordshire (United Kingdom). Euratom/UKAEA Fusion Association] [and others

1995-07-01

158

Modeling of alpha-particle-induced soft error rate in DRAM  

SciTech Connect

Alpha-particle-induced soft error in 256M DRAM was numerically investigated. A unified model for alpha-particle-induced charge collection and a soft-error-rate simulator (SERS) was developed. The author investigated the soft error rate of 256M DRAM and identified the bit-bar mode as one of dominant modes for soft error. In addition, for the first time, it was found that trench-oxide depth has a significant influence on soft error rate, and it should be determined by the tradeoff between soft error rate and cell-to-cell isolation characteristics.

Shin, H. [Ewha Womans Univ., Seoul (Korea, Republic of). Dept. of Electronic Engineering

1999-09-01

159

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

160

Measurement and analysis of neutron spectra from thick targets of Al and Ti bombarded by 30 50 MeV alpha particles  

Microsoft Academic Search

Energy distributions of neutrons emitted from thick targets of 27Al and 46Ti are measured for alpha induced reactions at 30, 40, and 50 MeV projectile energies. Measurements are done at 0, 30, and 45 with respect to the projectile direction using the proton recoil scintillation technique. The measured data are compared with results from calculations using three different approaches of

D. Dhar; S. N. Roy; T. Bandyopadhyay; P. K. Sarkar

2003-01-01

161

Scattering and recoiling imaging code (SARIC)  

NASA Astrophysics Data System (ADS)

A new classical ion trajectory simulation program based on the binary collision approximation has been developed in order to support the results of time-of-flight scattering and recoiling spectrometry (TOF-SARS) and scattering and recoiling imaging spectrometry (SARIS). The code was designed to provide information directly related to the TOF-SARS and SARIS measurements and to operate efficiently on small personal computers. The calculation uses the Ziegler-Biersack-Littmark (ZBL) universal screening function or the Molire screening function to simulate the three-dimensional motion of atomic particles and includes simultaneous collisions involving several atoms. For TOF-SARS, the program calculates the energy and time-of-flight distributions of scattered and recoiled particles, polar (incident) angle ?-scans, and azimuthal angle ?-scans. For SARIS, the program provides images of the scattering and recoiling intensities in polar exit angle and azimuthal angle (?, ?)-space. A two-dimensional reliability factor ( R) has been developed in order to obtain a quantitative comparison of experimental and simulated images. Examples of simulations are presented for Ni{100}, {110} and {111} surfaces and a Pt{111} surface. The R-factor is used to quantitatively compare the simulated Pt{111} image to an experimentally emulated image.

Bykov, V.; Kim, C.; Sung, M. M.; Boyd, K. J.; Todorov, S. S.; Rabalais, J. W.

162

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

PubMed

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

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

2007-03-01

163

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

Microsoft Academic Search

The formation of etched tracks in solid-state nuclear track detectors is usually described by assuming an unequivocal correlation of the etch-rate ratio with the energy loss of charged particles. For alpha particles, this assumption could be verified within the scatter of the experimental data. In this article, the dependence of the depth (x) on the track etch rate (V-T) was

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

2005-01-01

164

Alpha-particle dose to the liver and spleen tissues of Japanese Thorotrast patients.  

PubMed

We set out to establish an appropriate and convenient method for calculating alpha-particle absorbed doses to the liver and spleen of Thorotrast patients and to estimate a representative dose rate to the liver for the whole population of surviving and deceased Thorotrast patients in Japan. First, we determined steady-state activity ratios of 232Th progeny from 13 autopsy cases and found them to be identical to those reported in German subjects. Second, we estimated the alpha dose rates in 206 subjects at autopsy from radioactivity measurements and terminal weights of the organs. Combining these results with measurements of exhaled 220Rn in survivors, we considered the representative dose rates at injection to be 0.22 Gy y-1. Additionally, our data suggest that deposition in the spleen has previously been overestimated. This is an error with some bearing on the evaluation of leukemia risks from alpha-particle irradiation. PMID:8225986

Ishikawa, Y; Kato, Y; Mori, T; Machinami, R; Kitagawa, T

1993-11-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

166

Measurement of alphas from the structure of particle clusters produced in hadronic Z decays  

Microsoft Academic Search

Using 106 000 hadronic events obtained with the ALEPH detector at LEP at energies close to the Z resonance peak, the strong coupling constant alphas is measured by an analysis of energy-energy correlations (EEC) and the global event shape variables thrust, C-parameter and oblateness. It is shown that the theoretical uncertainties can be significantly reduced if the final state particles

D. Decamp; B. Deschizeaux; C. Goy; J.-P. Lees; M.-N. Minard; R. Alemany; J. M. Crespo; M. Delfino; E. Fernandez; V. Gaitan; Ll. Garrido; P. Mato; R. Miquel; Ll. M. Mir; S. Orteu; A. Pacheco; J. A. Perlas; E. Tubau; M. G. Catanesi; D. Creanza; M. de Palma; A. Farilla; G. Iaselli; G. Maggi; M. Maggi; S. Natali; S. Nuzzo; M. Quattromini; A. Ranieri; G. Raso; F. Romano; F. Ruggieri; G. Selvaggi; L. Silvestris; P. Tempesta; G. Zito; Y. Gao; H. Hu; D. Huang; X. Huang; J. Lin; J. Lou; C. Qiao; T. Ruan; T. Wang; Y. Xie; D. Xu; R. Xu; J. Zhang; W. Zhao; H. Albrecht; W. B. Atwood; F. Bird; E. Blucher; G. Bonvicini; F. Bossi; D. Brown; T. H. Burnett; H. Drevermann; F. Dydak; R. W. Forty; C. Grab; R. Hagelberg; S. Haywood; B. Jost; M. Kasemann; G. Kellner; J. Knobloch; A. Lacourt; I. Lehraus; T. Lohse; D. Lke; A. Marchioro; M. Martinez; J. May; S. Menary; A. Minten; A. Miotto; J. Nash; P. Palazzi; F. Ranjard; G. Redlinger; A. Roth; J. Rothberg; H. Rotscheidt; W. von Rden; R. St. Denis; D. Schlatter; M. Takashima; M. Talby; W. Tejessy; H. Wachsmuth; S. Wasserbaech; S. Wheeler; W. Wiedenmann; W. Witzeling; J. Wotschack; Z. Ajaltouni; M. Bardadin-Otwinowska; A. Falvard; R. El Fellous; P. Gay; J. Harvey; P. Henrard; J. Jousset; B. Michel; J.-C. Montret; D. Pallin; P. Perret; J. Proriol; F. Prulhire; G. Stimpfl; J. D. Hansen; J. R. Hansen; P. H. Hansen; R. Mllerud; E. R. Nielsen; B. S. Nilsson; I. Efthymiopoulos; E. Simopoulou; A. Vayaki; J. Badier; A. Blondel; G. Bonneaud; J. Bourotte; F. Braems; J. C. Brient; G. Fouque; A. Gamess; R. Guirlet; A. Rosowsky; A. Roug; M. Rumpf; R. Tanaka; H. Videau; D. J. Candlin; E. Veitch; G. Parrini; M. Corden; C. Georgiopoulos; M. Ikeda; J. Lannutti; D. Levinthal; M. Mermikides; L. Sawyer; A. Antonelli; R. Baldini; G. Bencivenni; G. Bologna; P. Campana; G. Capon; V. Chiarella; B. D'Ettorre-Piazzoli; G. Felici; P. Laurelli; G. Mannocchi; F. Massimo-Brancaccio; F. Murtas; G. P. Murtas; G. Nicoletti; L. Passalacqua; M. Pepe-Altarelli; P. Picchi; P. Zografou; B. Altoon; O. Boyle; A. W. Halley; I. Ten Have; J. L. Hearns; J. G. Lynch; W. T. Morton; C. Raine; J. M. Scarr; K. Smith; A. S. Thompson; R. M. Turnbull; B. Brandl; O. Braun; R. Geiges; C. Geweniger; P. Hanke; V. Hepp; E. E. Kluge; Y. Maumary; A. Putzer; B. Rensch; A. Stahl; K. Tittel; M. Wunsch; A. T. Belk; R. Beuselinck; D. M. Binnie; W. Cameron; M. Cattaneo; P. J. Dornan; S. Dugeay; A. M. Greene; J. F. Hassard; N. M. Lieske; S. J. Patton; D. G. Payne; M. J. Phillips; J. K. Sedgbeer; G. Taylor; I. R. Tomalin; A. G. Wright; P. Girtler; D. Kuhn; G. Rudolph; C. K. Bowdery; T. J. Brodbeck; A. J. Finch; F. Foster; G. Hughes; N. R. Keemer; M. Nuttall; A. Patel; B. S. Rowlingson; T. Sloan; S. W. Snow; E. P. Whelan; T. Barczewski; L. A. T. Bauerdick; K. Kleinknecht; B. Renk; S. Roehn; H.-G. Sander; M. Schmelling; H. Schmidt; F. Steeg; J.-P. Albanese; J.-J. Aubert; C. Benchouk; V. Bernard; A. Bonissent; D. Courvoisier; F. Etienne; S. Papalexiou; P. Payre; B. Pietrzyk; Z. Qian; W. Blum; P. Cattaneo; G. Cowan; B. Dehning; H. Dietl; M. Fernandez-Bosman; T. Hansl-Kozanecka; A. Jahn; W. Kozanecki; E. Lange; G. Ltjens; G. Lutz; W. Mnner; H.-G. Moser; Y. B. Pan; R. Richter; J. Schrder; A. S. Schwarz; R. Settles; U. Stierlin; J. Thomas; G. Wolf; V. Bertin; G. de Bouard; J. Boucrot; O. Callot; X. Chen; A. Cordier; M. Davier; G. Ganis; J.-F. Grivaz; Ph. Heusse; P. Janot; V. Journ; D. W. Kim; J. Lefranois; A.-M. Lutz; J.-J. Veillet; I. Videau; Z. Zhang; F. Zomer; S. R. Amendolia; G. Bagliesi; G. Batignani; L. Bosisio; U. Bottigli; C. Bradaschia; M. Carpinelli; M. A. Ciocci; R. dell'Orso; I. Ferrante; F. Fidecaro; L. Fo; E. Focardi; F. Forti; A. Giassi; M. A. Giorgi; F. Ligabue; A. Lusiani; E. B. Mannelli; P. S. Marrocchesi; A. Messineo; L. Moneta; F. Palla; G. Sanguinetti; J. Steinberger; R. Tenchini; G. Tonelli; G. Triggiani; C. Vannini-Castaldi; A. Venturi; P. G. Verdini; J. Walsh; J. M. Carter; M. G. Green; P. V. March; T. Medcalf; I. S. Quazi; M. R. Saich; J. A. Strong; R. M. Thomas; L. R. West; T. Wildish; D. R. Botterill; R. W. Clifft; T. R. Edgecock; M. Edwards; S. M. Fisher; T. J. Jones; P. R. Norton; D. P. Salmon; J. C. Thompson; B. Bloch-Devaux; P. Colas; C. Klopfenstein; E. Lanon; E. Locci; S. Loucatos; E. Monnier; P. Perez; F. Perrier; J. Rander; J.-F. Renardy; A. Roussarie; J.-P. Schuller; J. Schwindling; J. G. Ashman; C. N. Booth; C. Buttar; R. Carney; S. Cartwright; F. Combley; M. Dinsdale; M. Dogru; F. Hatfield; J. Martin; D. Parker; P. Reeves; L. F. Thompson; S. Brandt; H. Burkhardt; C. Grupen; H. Meinhard; L. Mirabito; E. Neugebauer; U. Schfer; H. Seywerd; G. Apollinari; G. Giannini; B. Gobbo; F. Liello; L. Rolandi; U. Stiegler; L. Bellantoni; J. F. Boudreau; D. Cinabro; J. S. Conway; D. F. Cowen; A. J. Deweerd; Z. Feng; D. P. S. Ferguson; J. Grahl; J. L. Harton; J. Hilgart

1991-01-01

167

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

168

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

169

Interaction of alpha particles at the cellular level--implications for the radiation weighting factor.  

PubMed

Since low dose effects of alpha particles are produced by cellular hits in a relatively small fraction of exposed cells, the present study focuses on alpha particle interactions in bronchial epithelial cells following exposure to inhaled radon progeny. A computer code was developed for the calculation of microdosimetric spectra, dose and hit probabilities for alpha particles emitted from uniform and non-uniform source distributions in cylindrical and Y-shaped bronchial airway geometries. Activity accumulations at the dividing spur of bronchial airway bifurcations produce hot spots of cellular hits, indicating that a small fraction of cells located at such sites may receive substantially higher doses. While presently available data on in vitro transformation frequencies suggest that the relative biological effectiveness for alpha particles ranges from about 3 to 10, the effect of inhomogeneous activity distributions of radon progeny may slightly increase the radiation weighting factor relative to a uniform distribution. Thus a radiation weighting factor of about 10 may be more realistic than the current value of 20, at least for lung cancer risk following inhalation of short-lived radon progeny. PMID:15623884

Hofmann, W; Fakir, H; Aubineau-Laniece, I; Pihet, P

2004-01-01

170

Alpha Particle Pressure Gauge for High Altitude Constant Level Balloon Flights  

Microsoft Academic Search

This paper describes an alpha particle pressure gauge designed for use on very high altitude constant level balloon flights. The instrument gives continuous readings from sea level to pressures less than 1 millibar with an accuracy in the 110 millibar range of a few tenths of a millibar. The instrument utilizes a sensitive electrometer measuring the ionization current due to

R. L. Howard; S. W. Nelson; J. R. Winckler

1968-01-01

171

Alternate method for treating Alfven waves driven unstable by {alpha} particles  

SciTech Connect

For treating Alfven waves driven unstable by {alpha} particles, an alternative to the Oak Ridge National Laboratory gyro-Landau fluid approach is suggested. Its primary advantage is that this method can simultaneously treat fluid nonlinearities and kinetic quasilinear effects. It is argued that more perturbative approaches could overestimate the kinetic quasilinear effects. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Hedrick, C.L.; Leboeuf, J.; Prochaska, M.D.; Spong, D.A.; Carreras, B.A. [Oak Ridge National Laboratory, P.O. Box 2009, Oak Ridge, Tennessee 37831-8071 (United States)] [Oak Ridge National Laboratory, P.O. Box 2009, Oak Ridge, Tennessee 37831-8071 (United States)

1995-12-01

172

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

National Technical Information Service (NTIS)

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 ...

C. S. Chang K. Imre H. Weitzner P. Colestock

1990-01-01

173

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. Brckner; B. C. Clark; G. Dreibus; G. Klingelhfer; G. Lugmair; D. W. Ming; H. Wnke; A. Yen; J. Zipfel; S. W. Squyres

2006-01-01

174

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

Microsoft Academic Search

The new alpha particle X-ray spectrometer (APXS) is part of the Athena payload of the two Mars Exploration Rovers (MER). The APXS sensor head is attached to the turret of the instrument deployment device (IDD) of the rover. The APXS is a very light-weight instrument for determining the major and minor elemental composition of Martian soils, rocks, and other geological

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

2003-01-01

175

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

176

Boron compounds as a dominant source of alpha particles in semiconductor devices  

Microsoft Academic Search

The interaction of cosmic ray neutrons and boron is demonstrated as the dominant source of alpha particles and other radiations in electronic devices utilizing borophosphosilicate glass (BPSG). A simple process modification is proposed to significantly reduce this intense source of ionizing radiation without compromising the reflow and passivation properties of BPSG.

Robert Baumann; Tim Hossain; Shinya Murata; Hideki Kitagawa

1995-01-01

177

Nuclear Densities of 1FSUB(7/2) Nuclei from Elastic alpha-Particle Scattering.  

National Technical Information Service (NTIS)

The elastic scattering of 104 MeV alpha particles by sup(40,42,43,44,48)Ca, exp 50 Ti, exp 51 V, exp 52 Cr has been analyzed by phenomenological and semimicroscopic optical potentials in order to get information on isotopic and isotonic differences of the...

E. Friedman H. J. Gils H. Rebel

1983-01-01

178

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

179

Effects of fusion-product alpha particles on plasma stability in the fusion ignition experiment IGNITEX  

Microsoft Academic Search

Summary form only given. The effects of alpha particles on the stability of MHD modes in IGNITEX plasmas are investigated analytically and numerically. The sawtooth and fishbone oscillations, which may occur in the central part of the plasma column, are associated with the n =1, m=1 internal kink modes and are considered to be a potential threat to the attainment

Z. Guo; R. Carrera; G. Y. Fu; G. Miley; E. Montalvo; M. N. Rosenbluth; J. W. Van Dam

1990-01-01

180

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

181

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

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

182

Isomeric yield ratios in proton-, sup 3 He, and. alpha. -particle-induced reactions on sup 197 Au  

Microsoft Academic Search

Excitation functions and mean projected recoil-ion ranges of the isomeric nuclei produced in proton-, ³He-, and α-particle-induced reactions on ¹⁹⁷Au were measured by an activation technique for bombarding energies {ital E}{sub {ital p}}{approx lt}50 MeV, and {ital E} {sub ³He,α}{approx lt}40 MeV. Isomeric yield ratios ({sub {ital m}}\\/{sub {ital g}}) were determined as a function of the incident particle energy.

Y. Nagame; K. Sueki; S. Baba; H. Nakahara

1990-01-01

183

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

SciTech Connect

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

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

1999-02-01

184

Scintillation of liquid helium for low-energy nuclear recoils  

NASA Astrophysics Data System (ADS)

The scintillation properties of liquid helium upon the recoil of a low-energy helium atom are discussed in the context of the possible use of this medium as a detector of dark matter. It is found that the prompt scintillation yield in the range of recoil energies from a few keV to 100 keV is somewhat higher than that obtained by a linear extrapolation from the measured yield for a 5-MeV ? particle. A comparison is made of both the scintillation yield and the charge separation by an electric field for nuclear recoils and for electrons stopped in helium.

Ito, T. M.; Seidel, G. M.

2013-08-01

185

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

SciTech Connect

The therapeutic potential of radionuclides that emit [alpha] particles, as well as their associated health hazards, have attracted considerable attention. The [sup 224]Ra daughters [sup 212]Pb and [sup 212]Bi, by virtue of their radiation properties which involve emission of [alpha] and [beta] particles in their decay to stable [sup 208]Pb, have been proposed as candidates for radioimmunotherapy. Using mouse testes as the experimental model and testicular spermhead survival as the biological end point, the present work examines the radiotoxicity of [sup 212]Pb and its daughters. When [sup 212]Pb, in equilibrium with its daughters [sup 212]Bi, [sup 212]Po and [sup 208]Tl, was administered directly into the testis, the dose required to achieve 37% survival (D[sub 37]) was 0.143 [+-] 0.014 Gy and the corresponding RBE of the mixed radiation field was 4.7 when compared to the D[sub 37] for acute external 120 kVp X rays. This datum, in conjunction with our earlier results for [sup 210]Po, was used to obtain an RBE-LET relationship for [alpha] particles emitted by tissue-incorporated radionuclides: RBE[sub [alpha

Howell, R.W.; Azure, M.T.; Narra, V.R.; Rao, D.V. (Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States))

1994-03-01

186

A spin filter polarimeter and an {alpha}-particle D-state study  

SciTech Connect

A Spin Filter Polarimeter (SFP) which reveals populations of individual hyperfine states of nuclear spin-polarized H{sup {+-}} (or D{sup {+-}}) beams has been tested. the SFP is based on unique properties of a three-level interaction in the 2S{sub 1/2} and 2P{sub 1/2} states of the hydrogen (or deuterium) atoms, created when the polarized ion beams pick up electrons in cesium vapor. The SFP has potential for an absolute accuracy of better than 1.5%, thus it could be used for calibrating polarimeters absolutely for low energy experiments for which no nuclear polarization standard exists. Test results show that the SFP provides a quick and elegant measure of the relative hyperfine state populations in the beam. This {alpha}-particle study is a small part of a larger project studying the deuteron-deuteron configuration of the {alpha}-particle wave function. The differential cross section and tensor analyzing powers (TAP) were measured for the {sup 50}Ti({bar d},{alpha}){sup 48}Sc reaction to the J{sup {pi}} = 7{sup +} state in {sup 48}Sc at E{sub x} = 1.097 MeV and compared with exact finite-range distorted-wave Born approximation (DWBA) calculations. The DWBA calculations use realistic {alpha}-particle wave functions generated from variational Monte-Carlo calculations.

Lemieux, S.K.

1993-12-31

187

Superconducting Transition-Edge Sensor Microcalorimeters for UltraHigh Resolution Alpha-Particle Spectrometry  

Microsoft Academic Search

Alpha-particle spectrometry is a powerful analytical tool for nuclear forensics and environmental monitoring. Super- conducting transition-edge sensor microcalorimeters have been shown to yield unsurpassed energy resolution for alpha spectrom- etry. With nearly an order of magnitude better energy resolution (1.06 keV FWHM at 5.3 MeV) than the current state-of-the-art silicon detectors (8-10 keV at 5.3 MeV), it is possible to

M. P. Croce; M. K. Bacrania; E. M. Bond; D. E. Dry; A. L. Klingensmith; W. A. Moody; S. P. LaMont; M. W. Rabin; J. H. Rim; J. A. Beall; D. A. Bennett; V. Kotsubo; R. D. Horansky; G. C. Hilton; D. Schmidt; J. N. Ullom; R. Cantor

2011-01-01

188

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

NASA Astrophysics Data System (ADS)

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

Watchman, Christopher J.

189

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

NASA Astrophysics Data System (ADS)

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

Ota, S.; Kobayashi, S.; Sihver, L.; Yamashita, N.; Hasebe, N.

2011-01-01

190

Large-angle {alpha}-particle scattering on {sup 12}C and search for signatures of {alpha}-particle Bose condensation  

SciTech Connect

Evidence of the 3{alpha}-particle condensate character of the Hoyle state (the 0{sub 2}{sup +} state at 7.65 MeV in {sup 12}C) implies not only an enhanced radius of {sup 12}C in this state, which was established by many theoretical calculations and confirmed by the recent diffraction model analysis, but also zero relative angular momenta between clusters. We performed coupled-channels model calculations of the angular distributions of {alpha}+{sup 12}C elastic and inelastic (to the 4.44-MeV 2{sup +}, 7.65-MeV 0{sub 2}{sup +}, and 9.65-MeV 3{sub 1}{sup -} states) scattering at 110 MeV and found the ratio of the empirical spectroscopic factors S(L). As the differential cross sections of these reactions are characterized by pronounced enhancement and strong oscillations at large angles, we assumed a potential scattering in the forward hemisphere and the direct transfer of a {sup 8}Be cluster at {theta}{sub c.m.}>90 deg. and took into account the direct transfer of {sup 8}Be in the ground state and in the first excited 2{sup +} and 4{sup +} states. We found that the cluster configuration with L=0 dominates in the 0{sub 2}{sup +} state, being more than three times larger than that in the ground state. This result provides additional evidence of the condensed structure of the Hoyle state in {sup 12}C with a dominance of zero relative angular momentum. The negative-parity 3{sub 1}{sup -} excited state in {sup 12}C observed above the 3{alpha} threshold is also considered to have the 3{alpha}-cluster structure. The present calculations described well the structure of the large-angle cross section on this state. We found a positive interference for all allowed {alpha}+{sup 8}Be configurations with a dominance of the p-orbital (69%){alpha}+{sup 8}Be motion and confirmed the exotic, but hardly a condensed, structure of this state.

Belyaeva, T. L. [Universidad Autonoma del Estado de Mexico, C.P. 50000, Toluca (Mexico); Danilov, A. N.; Demyanova, A. S.; Ogloblin, A. A. [RRC Kurchatov Institute, Moscow RU-123182 (Russian Federation); Goncharov, S. A. [Skobeltsyn Institute of Nuclear Physics, Vorob'evy Gory, Moscow (Russian Federation); Perez-Torres, R. [Universidad Tecnologico del Valle de Toluca (Mexico)

2010-11-15

191

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

SciTech Connect

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

Lombardo, I.; Campajola, L.; Rosato, E.; Spadaccini, G.; Vigilante, M. [Dipartimento di Scienze Fisiche dell'Universita di Napoli Federico II INFN - Sezione di Napoli, Napoli (Italy)

2013-07-18

192

Cytotoxic reaction and TNF-alpha response of macrophages to polyurethane particles.  

PubMed

Their unique mechanical and biological properties make polyurethanes (PUs) ideal materials for many implantable devices. However, uncertain long-term biostability in the human physiological environment limits their extensive clinical applications. Chronic inflammatory response associated with macrophage activation has been suggested as a prime factor; although the mechanism of macrophage activation in response to biomaterial surfaces and debris is still unknown. The overall objective of this work was to study the response of macrophages to PU materials in vitro by measuring cell viability and activity. The studies were carried out using phagocytozable-size PU particles from three types of commercially-available PUs: Pellethane 2363 80ABA (PL); Tecothane TT2065 (TC65); and Tecothane TT2085 (TC85). These polymers posess the same generic composition but differ in the length of hard and soft segments, as revealed by the FTIR and NMR studies. The results showed that PU particles affected both viability and activity of J774 macrophages. The percentage of mortality ranged from 1 to 15% with 10-100 microg ml(-1) of particles after 24 and 48 h incubation. These three types of particles induced different mortality on the macrophages. Specifically, the mortality with PL particles was 1-4% (p > 0.05), while the mortality with TC85 particles was 2-10% (p < 0.05) and 4-15% with TC65 (p < 0.05). Conversely, these particles also affected cell proliferation. Cell numbers increased by 132 and 167% after 24 and 48 h incubation, respectively, without particles, whereas the cell numbers increased only 46 and 78% with TC65, 66 and 105% with TC85, and 67 and 110% with PL in the presence of 100 microg ml(-1) of particles for the respective incubation times. PU particles also increased TNF-alpha release from macrophage. After having been incubated for 24 h with 100 microg ml(-1) particles of TC65, TC85, and PL, macrophages release TNF-alpha 7.4, 5.2, and 4.1 times more than the control. In conclusion, PU particles had cytotoxic effects on J774 macrophage at high concentrations. The order of macrophage response for three types of particles was TC65 > TC85 > PL. PU particles' effect on macrophage viability and activity depends on the concentration of particles and their chemical composition, especially on the ratio of hard to soft segments. PMID:12102593

Ma, Nan; Petit, Alain; Yahia, L'Hocine; Huk, Olga L; Tabrizian, Maryam

2002-01-01

193

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

PubMed

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

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

2009-05-01

194

Status of the JET Faraday cup lost alpha particle diagnostic KA-2  

NASA Astrophysics Data System (ADS)

We review the operational status and present a few recent results from the JET lost alpha particle diagnostic KA2. We summarize the results of our study of the correlation between KA2 signals and JET magnetic fields and the correlation between KA2 signals and the scintillator-based lost alpha probe KA3. In addition we quantify the relative insensitivity of the diagnostic to intense neutron and gamma ray background radiation fields and our observations of the electro-mechanical noise in the diagnostics signals. We present recent observations carried out during the 2011 JET campaign following the installation of the beryllium ITER-like wall. These observations include lost energetic deuterons during both ion-cyclotron and neutral beam heated plasmas; in particular we have measured relatively intense fluxes of energetic particles during sawtooth plasmas.

Cecil, F. E.; Kiptily, V.; Darrow, D. S.; Murari, A.; Contributors, JET-EFDA

2012-09-01

195

Energy resolution of silicon surface-barrier detectors for alpha particles, oxygen ions, and fission fragments  

NASA Astrophysics Data System (ADS)

A group of 53 silicon surface-barrier detectors, 10 manufactured by ORTEC and 43 fabricated by the first author and his students, have been extensively tested for their energy resolutions with 244Cm alpha particles, oxygen ions of 25 and 50 MeV energy from the University of Pittsburgh Van de Graaff accelerator, and fission fragments from a 252Cf source. A total of 47 detectors were tested with alpha particles, 24 were tested with fission fragments, and 8 were tested with the oxygen ions. Six detectors were tested with all three sources. The resistivity of the silicon from which the detectors were made and the reverse bias at which they were operated were given special attention. Capacitance measurements were made on most of the detectors to get an independent measurement of the resistivity of the silicon starting material.

Klema, Ernest D.; Saladin, J. X.; Alessi, James G.; Schmitt, H. W.

1980-12-01

196

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

NASA Astrophysics Data System (ADS)

A scintillator plate with high energy resolution was developed to produce an alpha particle monitor used in nuclear fuel reprocessing plants and mixed plutonium-uranium oxide (MOX) fuel plants. Grains of a Gd2Si2O7 (GPS) scintillator of several 10 to 550 ?m were fixed on a glass substrate and were then mechanically polished. By increasing the size of scintillator grains and removing fine powders, the collected light yield and energy resolution for alpha particles were drastically improved. Energy resolution of 9.3% was achieved using average grain size of 91 ?m. Furthermore, the ratios between counts in a peak and total counts were improved by more than 60% by the further increase of grain size and adoption of mechanically polished surfaces on both sides. Beta and gamma ray influences were suppressed sufficiently by the thin 100 ?m scintillator plates.

Shimaoka, Takehiro; Kaneko, Junichi H.; Izaki, Kenji; Tsubota, Youichi; Higuchi, Mikio; Nishiyama, Shusuke

2014-01-01

197

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

198

THE ANGULAR DISTRIBUTION OF ALPHA PARTICLES EMITTED BY ORIENTED Np²³⁷ NUCLEI (thesis)  

Microsoft Academic Search

Neptunium-237 nuclei were aligned when a monocrystalline sample of ; neptunyl rubidium nitrate was cooled to 0.2 to 4.2 deg K. The rotatable sample ; was placed in a capsule filled with He³ gas for heat transfer. Also in tbe ; capsule were a germanium surface-barrier alpha-particle counter, a thermometer, ; and rotation indicators. The capsule was in thermal contact

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

1960-01-01

199

Absolute number of scintillation photons in liquid xenon by alpha-particles  

SciTech Connect

This paper reports on the absolute scintillation yield obtained to be 3.26 [times] 10[sup 5] for alpha-particles of 5.303 MeV in liquid xenon. This result followed from fitting the absolute photo-electron yields measured with a VUV sensitive photomultiplier, which was used as a photo-diode, to the results of Monte-Carlo simulation.

Miyajima, M.; Sasaki, S.; Tawara, H. (National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)); Shibamura, E. (Saitama College of Health, Kamiokubo 519, Urawa, Saitama 338 (Japan))

1992-08-01

200

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

SciTech Connect

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

Zaider, M.

1992-01-01

201

Ionisation cross sections of Cd, Sn, Te, I and Ba for protons and alpha particles  

Microsoft Academic Search

K-shell X-ray production cross sections of 48Cd, 50Sn, 52Te, 53I and 56Ba have been measured for alpha particles with energies between 2.2 and 2.8 MeV. In addition, production cross sections for 52Te have been measured for protons between 1.6 and 3 MeV. The values have been compared with the earlier experiments and with the theoretical predictions given by four different

L. Avaldi; M. Milazzo; G. Trivia; I. V. Mitchell

1983-01-01

202

Energy dependence of radiation damage in molybdenum irradiated by. cap alpha. particles  

SciTech Connect

Transmission electron microscopy and x-ray analysis are used to study the defect structure produced in polycrystalline molybdenum by irradiation with high-energy (10--50 MeV) ..cap alpha.. particles. The nature of the radiation-induced defect clusters is determined and it is shown that there is no change in the crystal lattice parameters when interstitial and vacancy clusters are present together with isolated voids.

Ibragimov, S.S.; Reutov, V.F.; Abdrashitov, I.Y.; Vagin, S.P.

1983-01-01

203

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

SciTech Connect

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

Bunno, M.; Nakamura, Y. [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)] [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Suzuki, Y. [National Institute for Fusion Science, Toki 509-5292 (Japan)] [National Institute for Fusion Science, Toki 509-5292 (Japan); Shinohara, K.; Matsunaga, G. [Japan Atomic Energy Agency, Naka, Ibaraki 311-0193 (Japan)] [Japan Atomic Energy Agency, Naka, Ibaraki 311-0193 (Japan); Tani, K. [Nippon Advanced Technology, Naka, Ibaraki 311-0102 (Japan)] [Nippon Advanced Technology, Naka, Ibaraki 311-0102 (Japan)

2013-08-15

204

Alpha-particle emission from carbon bombarded with neutrons below 30 MeV  

SciTech Connect

Alpha-particle emission induced by neutron bombardment of carbon has been studied from threshold to over 30 MeV using the spallation neutron source at WNR/LAMPF. Targets include thin foils of CH{sub 2} and thicker foils of CH and polycrystalline graphite. Comparisons are made with evaluated data. Values for KERMA (kinetic energy released in materials) based on the results will be presented and compared with those obtained through other experimental approaches.

Haight, R.C.; Lee, T.M.; Sterbenz, S.M. [and others

1994-07-01

205

Preliminary analysis of alpha-particle effects in the fusion ignition experiment ignitex  

Microsoft Academic Search

In this paper a simple fusion experiment for the production and control do deuterium-tritium-ignited plasmas for scientific study is considered. The basic elements of fusion product alpha-particle containment is rather high even with the assumption of significant levels of toroidal asymmetries. Production of thermally stable plasmas is possible because of the low-beta thermal damping provided by electron cyclotron emission. The

R. Carrera; E. Montalvo; G. Y. Fu; G. H. Miley; L. M. Hively; M. N. Rosenbluth; S. Tamor

1990-01-01

206

Polycrystalline BN and LiF Based Semiconductor Alpha Particle and Neutron Detectors  

Microsoft Academic Search

Composite, polycrystalline, semiconductor, hexagonal BN alone or mixed with B4C or BMg2 and cubic LiF were embedded in an insulating matrix which acts as a binder and tested as alpha particle and neutron detectors. The boron containing semiconductors have the natural abundance of 10B which is ~20%. In the case of LiF is the natural content of 6Li only 7.4%.

M. Schieber; M. Roth; A. Zuck; O. Khakhan; J. Uher; V. Linhart; S. Pospisil; M. Fiederle

2006-01-01

207

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

208

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

209

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

PubMed

The skin tissue-equivalent slab reported in the International Commission on Radiological Protection (ICRP) Publication 116 to calculate the localised skin dose conversion coefficients (LSDCCs) was adopted into the Monte Carlo transport code Geant4. The Geant4 code was then utilised for computation of LSDCCs due to a circular parallel beam of monoenergetic electrons, protons and alpha particles <10 MeV. The computed LSDCCs for both electrons and alpha particles are found to be in good agreement with the results using the MCNPX code of ICRP 116 data. The present work thus validates the LSDCC values for both electrons and alpha particles using the Geant4 code. PMID:23610196

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

2013-10-01

210

First evidence of collective alpha particle effect on TAE modes in the TFTR D-T experiment  

SciTech Connect

The alpha particle effect on the excitation of toroidal Alfven eigenmodes (TAE) was investigated in deuterium-tritium (d-t) plasmas in the Tokamak Fusion Test Reactor (TFTR). 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.; Batha, S.H. [and others

1995-08-01

211

Multi-MeV Li/sup 0/ beam as a diagnostic for fast confined alpha particles  

SciTech Connect

We discuss a method of measuring the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a magnetically contained plasma. We calculate the characteristics of the signals to be expected from injecting multi-MeV Li/sup 0/ into the plasma to undergo double charge-exchange reactions with the alpha particles. Neutralized alpha particles then escape from the plasma to be detected by a charge-exchange analyzer. We also examine the feasibility of producing a Li/sup 0/ beam of the required current and energy, and we discuss a conceptual design for an appropriate beam system.

Grisham, L.R.; Post, D.E.; Mikkelsen, D.R.

1982-04-01

212

Study of the beta-delayed alpha-particle emission of 16N  

NASA Astrophysics Data System (ADS)

The beta-delayed alpha-particle emission of 16N has been studied, with 16N nuclei produced using 80 MeV/nucleon 18O beams on 9Be targets. The 16N secondary nuclei were mass analyzed and separated from the reaction products using the Michigan State University A1200 isotope separator. A detector array, including four thin surface barrier detectors, a p-i-n diode, a Ge gamma-ray detector, and a two-dimensional position sensitive parallel plate avalanche counter, was used for implantation and study of the separated nuclei. A beta-decay branching ratio of (1.3+/-0.3)10-5 to the 1- state at 9.6 MeV and a centroid of 2.35+/-0.05 MeV for the beta-delayed alpha-particle emission were measured. These results are essential for the analysis of a high sensitivity measurement at Yale University of the low-energy beta-delayed alpha-particle emission of 16N, and for understanding the 12C(?,?)16O reaction in the helium burning process in massive stars.

Zhao, Z.; France, R. H., III; Lai, K. S.; Gai, M.; Wilds, E. L.; Kryger, R. A.; Winger, J. A.; Beard, K. B.

1993-07-01

213

alpha-Particle and gamma-ray spectrometry of a plutonium solution for impurity determination.  

PubMed

A highly enriched (240)Pu solution was measured by alpha-particle and gamma-ray spectrometry to determine other radionuclides present in the material as impurities. Low activities of (238)Pu, (241)Am, (243)Cm and (244)Cm were determined by measuring thin sources, made from the original solution, in a high-resolution alpha-particle spectrometer. The sources were prepared by evaporating the plutonium solution on quartz plates in a vacuum chamber. From the ingrowth of (241)Am in the original solution, the amount of (241)Pu could be calculated. After radiochemical separation of (241)Am, the plutonium was measured by high-efficiency alpha-particle spectrometry to determine the amount of (238)Pu. The enriched (240)Pu material was also measured by high-resolution gamma-ray spectrometry, using two different HPGe detectors to determine the impurities of (239)Pu and (241)Am. The preparation of the sources and the measurement methods are described and discussed. The measured impurities, given in % of the (240)Pu activity, are compared with the values on the certificate. PMID:18356064

Sibbens, G; Altzitzoglou, T; Benedik, L; Pomm, S; Van Ammel, R

2008-01-01

214

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

NASA Astrophysics Data System (ADS)

Nonlinear electrostatic instabilities have been shown to occur frequently and under very different conditions in a plasma with two ion beams such as the fast solar wind. These instabilities can be triggered when the phase velocity of electrostatic ion-acoustic propagating forward and backward relative to the interplanetary magnetic field overlap, 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 per cent of the local Alfvn velocity - can trigger a very rich variety of nonlinear electrostatic acoustic-like instabilities. Their growth rates can be rather large and they persist for a wide range of ion temperatures, provided that the alpha particle backstreaming beams, have much larger drift velocities.

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

2009-12-01

215

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

SciTech Connect

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

Behar, Moni; Fadanelli, Raul C.; Nagamine, Luiz C. C. M. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, 91501-970 Porto Alegre, RS (Brazil); Abril, Isabel; Denton, Cristian D. [Departament de Fisica Aplicada, Universitat dAlacant, Apartat 99, E-03080 Alacant (Spain); Garcia-Molina, Rafael [Departamento de Fisica-CIOyN, Universidad de Murcia, Apartado 4021, E-30080 Murcia (Spain); Arista, Nestor R. [Division Colisiones Atomicas, Centro Atomico Bariloche, RA-8400 San Carlos de Bariloche (Argentina)

2009-12-15

216

Phagocytosis of titanium particles and necrosis in TNF-alpha-resistant mouse sarcoma L929 cells.  

PubMed

In the oral cavity, titanium is an excellent biocompatible material. However, it is reported that high ratios of intracellular titanium particles can cause cell apoptosis or necrosis by as-yet unknown mechanisms. The purpose of this study was to investigate the response of tumor necrosis factor alpha (TNF-alpha)-resistant L929 fibroblasts to titanium particles. Cells were cultured in Eagle's medium supplemented with fetal bovine serum and L-glutamine. Titanium particle sizes were less than 9 micro. Cytotoxicity was assayed by a cell counting kit, trypan blue dye exclusion test and lactate dehydrogenase (LDH) leakage. The production of reactive oxygen species (ROS) was detected by a confocal laser scanning microscope (CLSM) using dichlorofluorescein diacetate as a fluorescent probe. Morphology was viewed by a CLSM and with an X-ray microanalyser (XMA). When titanium particles were added to cells, the viability decreased to around 50% at a particle concentration of 2.0%. The number of dead cells and LDH activity in the culture media increased significantly between 1 and 2 days. However, formation of active oxygen species did not occur, since no dichlorofluorescein fluorescence was observed. A scanning electron photomicrograph (SEM) revealed a large number of particles covering or adhering to cellular components in lysed cells compared with flattened control cells attached to the substrate. The XMA showed that the titanium accumulation was coincident with the deformed cell shape. The CLSM also confirmed that particles were within the cells. From these results it was concluded that titanium particles ingested in large quantities into the cell induced necrosis by a pathway other than by producing ROS. PMID:12537961

Osano, E; Kishi, J; Takahashi, Y

2003-02-01

217

Enhancing the sensitivity of recoil-beta tagging  

NASA Astrophysics Data System (ADS)

Tagging with ?-particles at the focal plane of a recoil separator has been shown to be an effective technique for the study of exotic proton-rich nuclei. This article describes three new pieces of apparatus used to greatly improve the sensitivity of the recoil-beta tagging technique. These include a highly-pixelated double-sided silicon strip detector, a plastic phoswich detector for discriminating high-energy ?-particles, and a charged-particle veto box. The performance of these new detectors is described and characterised, and the resulting improvements are discussed.

Henderson, J.; Ruotsalainen, P.; Jenkins, D. G.; Scholey, C.; Auranen, K.; Davies, P. J.; Grahn, T.; Greenlees, P. T.; Henry, T. W.; Herz?, A.; Jakobsson, U.; Joshi, P.; Julin, R.; Juutinen, S.; Konki, J.; Leino, M.; Lotay, G.; Nichols, A. J.; Obertelli, A.; Pakarinen, J.; Partanen, J.; Peura, P.; Rahkila, P.; Sandzelius, M.; Sarn, J.; Sorri, J.; Stolze, S.; Uusitalo, J.; Wadsworth, R.

2013-04-01

218

Alpha-particle autoradiography in CR-39: The determination of the microdistribution of activity and trace element analysis  

NASA Astrophysics Data System (ADS)

New and elaborate techniques for alpha-particle autoradiography of thick specimens based on the plastic nuclear track detector CR-39 have been developed. These permit a full analysis of both trace element and microdistribution of alpha-active nuclides present. The important features of the techniques are: (1) reliable low level counting down to 10 -15Ci g -1, (2) high resolution alpha-particle spectroscopy in CR-39, (3) determination of the absolute abundance of alpha active nuclides present in the specimen, (4) determination of the distribution of emission with height up to 30 microns above the surface of the autoradiograph, (5) the local determination of the radon diffusion coefficient in the specimen which is needed to calculate the activity levels of 222Rn and daughter nuclei, (6) the analysis of small and large clusters of alpha-particle activity recorded on the autoradiograph. These techniques are briefly discussed.

Peter Fews, A.; Henshaw, Denis L.

219

A survey of the physical processes which determine the response function of silicon detectors to alpha particles  

NASA Astrophysics Data System (ADS)

The spectra of monoenergetic alpha particles exhibit a well known asymmetric shape when measured with silicon detectors. The processes are described which determine the response of silicon detectors to alpha particles, particularly the energy dependence of the line shape. In this work particle implanted and passivated silicon (PIPS) detectors are assumed to have a thin dead layer at the front contact and an infinite sensitive volume. The incoming monoenergetic alpha particles lose energy in the dead layer where they develop a Gaussian energy distribution due to electronic energy-loss straggling. In the sensitive volume the alpha particles transfer most of their energy to electronic excitation and ionization ( Es,e) and the remaining fraction to the production of lattice vibrations and crystal damage. The statistical distribution of Es,e has been calculated by Monte Carlo simulation and shown to be asymmetric. The energy Es,e is subsequently used for the creation of electron-hole pairs, which are measured by an amplifier system with a Gaussian contribution to the energy resolution due to electronic noise. This model permits a quantitative calculation of the detector response function to alpha particles, and the result is in excellent agreement with measured spectra. On the basis of this model the energy dependence of the alpha particle line shape is also discussed.

Steinbauer, E.; Bortels, G.; Bauer, P.; Biersack, J. P.; Burger, P.; Ahmad, I.

1994-01-01

220

Redistribution of high energy alpha particles due to sawteeth with partial reconnection  

NASA Astrophysics Data System (ADS)

The redistribution of high energy alpha particles due to internal kink modes is studied in plasmas with ITER-like parameters. The exact particle trajectories in the total fields, equilibrium plus perturbation, are calculated. The equilibrium magnetic field is obtained by analytically solving the Grad-Shafranov equation and the perturbed electric and magnetic fields are reconstructed using ideal MHD and the experimental information about the displacement eigenfunction. The (1, 1), (2, 2) and (2, 1) modes are included and the effect of changing their amplitude and frequency is determined. The results show that if the conditions are similar to those reported in Igochine et al (2007 Nucl. Fusion 47 23), the peak density of counter-passing particles decreases between 25% and 40% (depending on the energy); the peak of the trapped particles density shifts outwards by approximately 10% of the minor radius and the total on axis density decreases by more than 25%. This redistribution occurs inside the q = 1 surface. The addition of a (2, 1) mode, which can produce the stochastization of the magnetic field, significantly increases particle redistribution and allows particles to spread beyond the q = 1 surface. Different groups of particles (co-passing, counter-passing, trapped) respond differently to the perturbations.

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

2013-04-01

221

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

ERIC Educational Resources Information Center

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

Ouseph, P. J.; Mostovych, Andrew

1978-01-01

222

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

National Technical Information Service (NTIS)

We report on a theory for describing the biological effects of ionizing radiation in particular radon (alpha) particles. Behind this approach is the recognition that biological effects such as chromosome aberrations, cellular transformation, cellular inac...

M. Zaider

1992-01-01

223

Analysis of neutron emission spectra for 30 50 MeV alpha-particle induced reactions in thick targets  

Microsoft Academic Search

Comparisons of calculated neutron yield distributions from alpha-particle induced reactions on thick targets are made with measured data to analyze the initial reaction process in the framework of the exciton (hybrid) model code ALICE91 (M. Blann, Lawrence Livermore National Laboratory Report UCID 19614, 1982). We have considered two reaction mechanisms: dissolution of the alpha in the nuclear field, and preequilibrium

D. Dhar; S. N. Roy; Maitreyee Nandy; P. K. Sarkar

2003-01-01

224

Dependence of scintillation characteristics in the CsI(Tl) crystal on Tl* concentrations under electron and alpha particles excitations  

Microsoft Academic Search

This paper reports the emission spectra, pulse heights and decay curves of CsI(Tl) crystals with a Tl* concentration ranging from 10-6 mol to 10-2 mol, under electron and alpha particle excitations. Larger pulse heights from the crystals with Tl+concentration of more than 10-3 mol were observed for a higher ionization density of alpha particle excitation, compared with those of electron

M. M. Hamadaa; F. E. Costa; M. C. C. Pereira; S. Kubota

2000-01-01

225

Dependence of scintillation characteristics in the CsI(Tl) crystal on Tl+ concentrations under electron and alpha particles excitations  

Microsoft Academic Search

This paper reports the emission spectra, pulse heights, and decay curves of CsI(TI) crystals with a Tl+ concentration ranging from 10-6 to 10-2 mol under electron and alpha particle excitations. Larger pulse heights from the crystals with Tl+ concentration of more than 10-3 mol were observed for a higher ionization density of alpha particle excitation compared with those of electron

Margarida M. Hamada; Fabio E. Costa; Maria C. C. Pereira; Shinzou Kubota

2001-01-01

226

Deep level defects and carrier removal due to proton and alpha particle irradiation of InP  

Microsoft Academic Search

Deep level transient spectroscopy and capacitance voltage measurements of the defect introduction rates and carrier removal rates for 2 MeV proton and 2 MeV alpha particle irradiations in p-type InP have been performed. The carrier removal rate for 2 MeV protons was 6500 cm?1 and for 2 MeV alpha particles was 73 400 cm?1, or 12 times higher. The defect

George C. Rybicki; Christian A. Zorman

1994-01-01

227

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

228

Malignant transformation of human bronchial epithelial cells by radon-simulated alpha-particles.  

PubMed

Epidemiological studies have shown that inhalation of radon is associated with an increased risk for bronchogenic carcinoma in uranium miners. These alpha-emitting radon daughters also represent the largest component of background radiation to the general public. In the present study, the oncogenic transforming effects of single versus multiple doses of radon-simulated alpha-particles were examined using human papillomavirus-immortalized human bronchial epithelial cells. Endpoints such as growth kinetics, resistance to serum and 12-O-tetradecanoylphorbol-13-acetate-induced terminal differentiation, anchorage-independent growth and tumorigenicity in nude mice were used to assess the various stages of transformation in the bronchial epithelial cells. We show here, for the first time, that immortalized human cells in culture can be malignantly transformed by a single 30 cGy dose of alpha-particles. Transformed cells produced progressively growing subcutaneous tumors upon inoculation into athymic nude mice. Immunofluorescent staining of keratin and isozyme analysis of the cell lines subsequently generated from these tumors indicated that the cells were of human epithelial origin. Analysis of genomic DNA from the tumorigenic cell lines using PCR amplification and restriction enzyme analysis demonstrated no point mutation at either codon 12/13 or 61 in any of the ras oncogenes examined (K-, N- and H-ras). This system provides an opportunity to study the cellular and molecular changes at the various stages in radiation carcinogenesis involving human cells. PMID:8118924

Hei, T K; Piao, C Q; Willey, J C; Thomas, S; Hall, E J

1994-03-01

229

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

SciTech Connect

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

Sager, G.T.; Miley, G.H. (Illinois Univ., Urbana, IL (United States). Fusion Studies Lab.); Burrell, K.H. (General Atomics Co., San Diego, CA (United States))

1990-11-01

230

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

231

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

232

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

233

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

SciTech Connect

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

Marsh, S.F.

1991-01-01

234

Test Procedure for Gross Alpha Particle Activity in Drinking Water: Interlaboratory Collaborative Study.  

National Technical Information Service (NTIS)

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 s...

E. L. Whittaker

1986-01-01

235

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

NASA Astrophysics Data System (ADS)

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

Campbell, J. L.

2012-10-01

236

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

SciTech Connect

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

Tie-Nan Jiang (Institute of Radiation Medicine, Tianjin (China)); Lord, B.I.; Hendry, J.H. (Paterson Institute for Cancer Research, Manchester (United Kingdom))

1994-03-01

237

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

SciTech Connect

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

Wang, S. [Princeton Plasma Physics Lab., NJ (United States)]|[Academia Sinica, Hefei, Anhui (China). Inst. of Plasma Physics; Zweben, S.J. [Princeton Univ., NJ (United States). Plasma Physics Lab.

1996-05-01

238

NBS (National Bureau of Standards) large-area alpha-particle counting systems  

SciTech Connect

Two alpha-particle counting systems for the measurement of large-area sources were developed at the National Bureau of Standards. The systems and their characteristics are described. One system uses an internal-source proportional counter and the other measures sources external to the counting volume through a thin aluminized mylar window. The internal system is used to measure sources in the lower-activity ranges. These calibrated sources are then used to establish the efficiency of the external counter used to measure the higher-activity sources.

Hutchinson, J.M.R.; Bright, S.J.

1987-01-01

239

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

NASA Astrophysics Data System (ADS)

The alpha particle x-ray spectrometer on the Spirit rover determined major and minor elements of soils and rocks in Gusev crater in order to unravel the crustal evolution of planet Mars. The composition of soils is similar to those at previous landing sites, as a result of global mixing and distribution by dust storms. Rocks (fresh surfaces exposed by the rock abrasion tool) resemble volcanic rocks of primitive basaltic composition with low intrinsic potassium contents. High abundance of bromine (up to 170 parts per million) in rocks may indicate the alteration of surfaces formed during a past period of aqueous activity in Gusev crater.

Gellert, R.; Rieder, R.; Anderson, R. C.; Brckner, J.; Clark, B. C.; Dreibus, G.; Economou, T.; Klingelhfer, G.; Lugmair, G. W.; Ming, D. W.; Squyres, S. W.; d'Uston, C.; Wnke, H.; Yen, A.; Zipfel, J.

2004-08-01

240

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 = 0.70770.0014, P?13 = 0.1711 0.0014 and P?51 = 0.11940.0007, which for the P?0.07 is about 3.6% lower than the recent evaluated value in the literature.

Garca-Torao, E.; Acea, M. L.; Bortels, G.; Mouchel, D.

1993-10-01

241

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

NASA Technical Reports Server (NTRS)

The alpha particle x-ray spectrometer on the Spirit rover determined major and minor elements of soils and rocks in Gusev crater in order to unravel the crustal evolution of planet Mars. The composition of soils is similar to those at previous landing sites, as a result of global mixing and distribution by dust storms. Rocks (fresh surfaces exposed by the rock abrasion tool) resemble volcanic rocks of primitive basaltic composition with low intrinsic potassium contents. High abundance of bromine (up to 170 parts per million) in rocks may indicate the alteration of surfaces formed during a past period of aqueous activity in Gusev crater.

Gellert, R.; Rieder, R.; Anderson, R. C.; Brueckner, J.; Clark, B. C.; Dreibus, G.; Economou, T.; Klingelhoefer, G.; Lugmair, G. W.; Ming, D. W.

2005-01-01

242

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

SciTech Connect

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

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

1991-10-01

243

Spectroscopic studies on alpha particle-irradiated PADC (CR-39 detector)  

NASA Astrophysics Data System (ADS)

Spectroscopic studies on a Poly Allyl Diglycol Carbonate (PADC or CR-39) detector irradiated with 5 MeV ?-particles were carried out. The CR-39 samples were exposed to perpendicular incidence of ?-particles with different fluence ranging from 0.85 109 to 6.79 109 particles/cm2. The induced modifications in the CR-39 detectors were investigated using UV-Vis, FTIR, and photoluminescence (PL) spectroscopy. The results reveal that UV-Visible and FTIR spectroscopic techniques are insensitive to detect the induced modifications in the irradiated CR-39 detector within the selected range of fluence. Photoluminescence (PL) spectra, on the other hand, showed a reasonable difference between the detected spectra of the irradiated samples. The integrated intensity (N) under the PL emission band and peaks heights (P) exhibits a linear correlation with the alpha particles fluence. The fitting linear formula and the relevant parameters for both relations (N and P vs. fluence) were determined. The comparison study between the three spectroscopic techniques indicated that PL spectroscopy provides a sensitive method for ?-particles dosimetric applications using a CR-39 detector.

El Ghazaly, M.; Hassan, H. E.

244

Collective atomic recoil lasing  

NASA Astrophysics Data System (ADS)

A cloud of ultra-cold atoms is loaded into the attractive potential of a light wave that is generated by two counter-propagating modes of a high-finesse ring resonator. The two modes are coupled by the atoms due to coherent Rayleigh scattering and generate a potential which acts back on the motion of the atoms. This feedback leads to a new frequency component and can be described in terms of the long time proposed collective atomic recoil laser (CARL). This model is investigated experimentally and extended by introducing an optical friction force acting on the atoms. This allows for steady state operation of the CARL. Furthermore, it leads to a threshold behaviour of the CARL that translates into a novel type of phase transition: while passing the threshold the initially homogeneous atomic distribution is bunched in space and velocity. With this behaviour the system turns out to acquire some of the main features of the so-called Kuramoto model which provides a very general description of a network of limit cycle oscillators.

Zimmermann, Claus; Kruse, Dietmar; von Cube, Christoph; Slama, Sebastian; Deh, Benjamin; Courteille, Philippe

2004-06-01

245

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

SciTech Connect

The authors have measured the time dependence and the intensity of the primary scintillation light in liquid xenon excited by {sup 241}Am alpha particles and {sup 207}Bi internal conversion electrons, at different electric field strengths. High purity liquid xenon was used to fill a parallel plate ionization chamber equipped with a CaF{sub 2} window coupled to a UV sensitive photomultiplier tube. The effect of the specific ionization density on the scintillation light as well as the time correlation between the light signal and the charge signal is reported. The authors demonstrate that the fast scintillation signal produced in liquid xenon by an ionizing particle provides an ideal trigger in a detector aiming at a complete three-dimensional even reconstruction with an excellent background rejection capability.

Aprile, E.; Mukherjee, R.; Suzuki, M. (Columbia Univ., New York, NY (USA). Dept. of Physics)

1990-04-01

246

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

247

Transport theory for energetic alpha particles and tolerable magnitude of error fields in tokamaks with broken symmetry  

NASA Astrophysics Data System (ADS)

A transport theory for energetic fusion born alpha particles in tokamaks with broken symmetry has been developed. The theory is a generalization of the theory for neoclassical toroidal plasma viscosity for thermal particles in tokamaks. It is shown that the radial energy transport rate can be comparable to the slowing down rate for energetic alpha particles when the ratio of the typical magnitude of the perturbed magnetic field strength to that of the equilibrium magnetic field strength is of the order of 10-4 or larger. This imposes a constraint on the magnitude of the error fields in thermonuclear fusion reactors. The implications on stellarators as potential fusion reactors are also discussed.

Shaing, K. C.; Hsu, C. T.

2014-03-01

248

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

249

Single particle characterization of iron-induced pore-forming alpha-synuclein oligomers.  

PubMed

Aggregation of alpha-synuclein is a key event in several neurodegenerative diseases, including Parkinson disease. Recent findings suggest that oligomers represent the principal toxic aggregate species. Using confocal single-molecule fluorescence techniques, such as scanning for intensely fluorescent targets (SIFT) and atomic force microscopy, we monitored alpha-synuclein oligomer formation at the single particle level. Organic solvents were used to trigger aggregation, which resulted in small oligomers ("intermediate I"). Under these conditions, Fe(3+) at low micromolar concentrations dramatically increased aggregation and induced formation of larger oligomers ("intermediate II"). Both oligomer species were on-pathway to amyloid fibrils and could seed amyloid formation. Notably, only Fe(3+)-induced oligomers were SDS-resistant and could form ion-permeable pores in a planar lipid bilayer, which were inhibited by the oligomer-specific A11 antibody. Moreover, baicalein and N'-benzylidene-benzohydrazide derivatives inhibited oligomer formation. Baicalein also inhibited alpha-synuclein-dependent toxicity in neuronal cells. Our results may provide a potential disease mechanism regarding the role of ferric iron and of toxic oligomer species in Parkinson diseases. Moreover, scanning for intensely fluorescent targets allows high throughput screening for aggregation inhibitors and may provide new approaches for drug development and therapy. PMID:18258594

Kostka, Marcus; Hgen, Tobias; Danzer, Karin M; Levin, Johannes; Habeck, Matthias; Wirth, Andreas; Wagner, Richard; Glabe, Charles G; Finger, Sabine; Heinzelmann, Udo; Garidel, Patrick; Duan, Wenzhen; Ross, Christopher A; Kretzschmar, Hans; Giese, Armin

2008-04-18

250

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

251

Targeted Cytoplasmic Irradiation with Alpha Particles Induces Mutations in Mammalian Cells  

NASA Astrophysics Data System (ADS)

Ever since x-rays were shown to induce mutation in Drosophila more than 70 years ago, prevailing dogma considered the genotoxic effects of ionizing radiation, such as mutations and carcinogenesis, as being due mostly to direct damage to the nucleus. Although there was indication that alpha particle traversal through cellular cytoplasm was innocuous, the full impact remained unknown. The availability of the microbeam at the Radiological Research Accelerator Facility of Columbia University made it possible to target and irradiate the cytoplasm of individual cells in a highly localized spatial region. By using dual fluorochrome dyes (Hoechst and Nile Red) to locate nucleus and cellular cytoplasm, respectively, thereby avoiding inadvertent traversal of nuclei, we show here that cytoplasmic irradiation is mutagenic at the CD59 (S1) locus of human-hamster hybrid (AL) cells, while inflicting minimal cytotoxicity. The principal class of mutations induced are similar to those of spontaneous origin and are entirely different from those of nuclear irradiation. Furthermore, experiments with radical scavenger and inhibitor of intracellular glutathione indicated that the mutagenicity of cytoplasmic irradiation depends on generation of reactive oxygen species. These findings suggest that cytoplasm is an important target for genotoxic effects of ionizing radiation, particularly radon, the second leading cause of lung cancer in the United States. In addition, cytoplasmic traversal by alpha particles may be more dangerous than nuclear traversal, because the mutagenicity is accomplished by little or no killing of the target cells.

Wu, Li-Jun; Randers-Pehrson, Gerhard; Xu, An; Waldren, Charles A.; Geard, Charles R.; Yu, Zengliang; Hei, Tom K.

1999-04-01

252

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

253

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

254

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

255

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 Alfven 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 to perpendicular heating and parallel cooling rates which are comparable to the heating rates estimated from the Helios observations.

Travnicek, P. M.; Hellinger, P.

2013-12-01

256

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 Alfvn 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; Trvn?ek, Pavel M.

2013-09-01

257

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

258

Use of infinitely thick source alpha particle pulse height distributions in the determination of individual specific alpha activities  

NASA Astrophysics Data System (ADS)

A method is presented in which material containing a complex mixture of alpha emitting radionuclides might be analyzed with minimal sample preparation and the individual specific activities of each alpha emitting species found. A theoretical relationship describing the pulse height distribution of an infinitely thick source of alpha activity is developed. This relationship is then fit to uranium and thorium oxide pulse height distribution data obtained with a PIPS detector/MCA counting system, confirming the validity of the theoretical pulse height distribution. The method does not require complex and time consuming sample preparation common to conventional alpha spectroscopy. Results obtained from fits to the pulse height distributions are in agreement with the specific alpha activities of the oxides.

Phoenix, Kevin A.

1997-10-01

259

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

260

Half-life estimation of the first excited state of {sup 229}Th by using {alpha}-particle spectrometry  

SciTech Connect

To search for a direct-decay signal from the isomer {sup 229}Th{sup m}, {alpha}-particle spectra of {sup 229}Th{sup m,g} produced from 93 mg of {sup 233}U have been measured by using a rapid and high-resolution {alpha}-particle spectrometry, which can distinguish {alpha} lines of {sup 229}Th{sup m} from those of its ground state. Although {alpha} events were not obtained in the expected energy region for {sup 229}Th{sup m} with the exception of those derived from {sup 229}Th{sup g}, we can estimate that the half-life of {sup 229}Th{sup m} is shorter than 2 h at 3{sigma} confidence level under the chemical condition of chloride or hydroxide.

Kikunaga, H. [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Nishina Center for Accelerator-Base Science, RIKEN, Wako, Saitama 351-0198 (Japan); Kasamatsu, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Haba, H. [Nishina Center for Accelerator-Base Science, RIKEN, Wako, Saitama 351-0198 (Japan); Mitsugashira, T. [Institute for Material Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Hara, M. [International Research Center for Nuclear Materials Science, Tohoku University, Oarai-machi, Ibaraki 311-1313 (Japan); Takamiya, K. [Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494 (Japan); Ohtsuki, T. [Laboratory of Nuclear Science, Tohoku University, Sendai, Miyagi 982-0826 (Japan); Yokoyama, A.; Nakanishi, T. [Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192 (Japan); Shinohara, A. [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

2009-09-15

261

Determination of 239Pu/240Pu isotopic ratio by high-resolution alpha-particle spectrometry using the ADAM program.  

PubMed

A novel analysis program to unfold alpha-particle energy spectra was introduced, demonstrated and validated using radiochemically processed test sources, which contained different amounts of (239)Pu and (240)Pu. A high-resolution alpha spectrometer was used for data acquisition. The software known as ADAM unfolds the spectra using nuclide-specific decay data as a constraint. The peaks can have different shapes and the software can also cope with the coincidences between alpha particles and electrons/photons. In the present paper, the (239)Pu/(240)Pu activity ratios from alpha spectrometry agreed, within the stated uncertainties, with the reference values. Number of counts in the (239,240)Pu peak group must be larger than 100 to obtain reliable values when using semiconductor detector of energy resolution FWHM=10.6 keV. PMID:22227537

Pllnen, R; Siiskonen, T; Ihantola, S; Toivonen, H; Pelikan, A; Inn, K; La Rosa, J; Bene, B J

2012-04-01

262

Some Properties of Supported Small alpha-Fe2O3 Particles Determined with the Mssbauer Effect  

Microsoft Academic Search

Mssbauer spectra of Fe57 in alpha-Fe2O3 have been measured as a function of particle size and temperature. Bulk alpha-Fe2O3 shows a change in the sign of the quadrupole interaction in going through the Morin transition temperature, 263K. Analyses of the spectra show that the magnetization vector is in the c plane above the transition temperature and parallel to the c

Walter Kndig; Hans Bmmel; G. Constabaris; R. H. Lindquist

1966-01-01

263

Onboard detection of intrinsic Ly. alpha. radiation from a neutral particle beam  

SciTech Connect

We consider photometers onboard a hydrogen neutral particle beam (NPB) space platform which monitor the instrinsic radiation from excited atoms in the NPB in flight. The radiation of choice is the Lyman {alpha} (Ly{alpha}) line 1216 A, emitted when the beam's {approx equal} 7% fraction of H (2S) atoms is motionally quenched in the earth's magnetic field. At nominal 20-MeV NPB energy, the Ly{alpha} radiation persists at 1% of its initial intensity out to 100 m along the beam, and is red-shifted to 1494 A when viewed form behind the exciting NPB pulse. A photosensitive detector with a {approximately} 5{degree} field of view, placed adjacent to the NPB exit port and viewing the NPB pulse along its limb, shows marked changes in detected Ly{alpha} intensity when the NPB axis shifts direction. If the NPB pulse is nominally 50 MA times 100 {mu}s, and if the detector is a 1-cm{sup 2} array of 25 {mu}m times 25 {mu}m photosensitive pixels located in the focal plane of an 8-cm diam. f/1 LiF lens, then pixels at the brightest part of the beam image are illuminated by up to 2300 Ly{alpha} photons per NPB pulse. The pixel quantum efficiency, optics transmission losses, and a geometric correction for viewing angle reduce the maximum count rate to {approximately} 200 photoelectrons per pixel per pulse under realistic operating conditions, and at a limb-viewing angle (i.e., angle between beam and detector axes) of {approx equal} 6 mrad. At smaller viewing angles the pixels count rate declines rapidly, but rapidly, but becomes sensitive to small angular shifts in the NPB axis direction. In the limit of shot-noise on the pixel count, and at optimum viewing angle ({approx equal} 0.54 mrad), we find that a single pixel can sense beam-axis shifts of {approx equal} {plus minus}50 {mu}rad. 8 refs., 7 figs., 2 tabs.

Robiscoe, R.T. (Montana State Univ., Bozeman, MT (USA). Dept. of Physics); Cobb, D.D.; Maier, W.B. II (Los Alamos National Lab., NM (USA))

1990-05-01

264

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

PubMed

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

Chauhan, Vinita; Howland, Matthew

2014-10-01

265

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

USGS Publications Warehouse

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

Martinez, P.; Senftle, F. E.

1960-01-01

266

Range of recoil atoms in isotropic stopping materials  

Microsoft Academic Search

A calculation of the stopping power, range, and range straggling of low energetic atoms ( E≲1 MeV) is reported. The computation applied the biatomic repulsive potential of Firsov and thus had to be carried out numerically. The results, however, are presented in an analytical form. --- Experimental checks were performed with recoil atoms. 96 keV Ra-224 atoms from the alpha-decay

Jochen P. Biersack

1968-01-01

267

Positron study of alpha particles effect on oxide-dispersion-strengthened steels  

NASA Astrophysics Data System (ADS)

Microstructure of oxide-dispersion-strengthened steels with different chromium content - MA 956 (20% Cr), ODM 751 (16% Cr) and MA 957 (14% Cr) were studied by positron annihilation lifetime spectroscopy. Samples were measured before and after helium ion implantation (He2+); therefore microstructure changes and radiation resistance to alpha particles of these steels were observed. Defect accumulation due to the radiation treatment was proven in all investigated materials. After ion implantation, mean lifetimes increased of about ~ 10 ps, which indicates significant change in microstructure. According to calculations of a defect volume from defect concentration and pre-dominant size of defects, ODM 751 is the most resistant steel in comparison to other investigated materials.

Veternikova, J.; Slugen, V.; Stancek, S.; Degmova, J.; Sabelova, V.; Sojak, S.; Petriska, M.; Hinca, R.

2013-06-01

268

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

PubMed

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(+) ion source (2 A, the beam radius of 11.3 mm, the beam energy less than 20 keV). Present strong-focusing He(+) 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. PMID:22380323

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

2012-02-01

269

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

SciTech Connect

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

Liu, X. J.; Xiao, B. J. [Institute of Plasma Physics, Chinese Academy of Sciences, PO Box 1126, Hefei 230031 (China); Liu, L. [Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088 (China); College of Material Sciences and Optoelectronic Technology, Graduate University of the Chinese Academy of Sciences, PO Box 4588, Beijing 100049 (China); Wang, J. G. [Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088 (China); Qu, Y. Z. [College of Material Sciences and Optoelectronic Technology, Graduate University of the Chinese Academy of Sciences, PO Box 4588, Beijing 100049 (China)

2011-10-15

270

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

271

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

272

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

273

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

274

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

NASA Astrophysics Data System (ADS)

This study reports the characteristic studies for the detection of alpha particles in DAM-ADC nuclear track detector. Several important parameters that control the track formation such as, the bulk etch rate (VB), track etching rate (VT), dependence of VB and VT on etching concentration and temperature have been extensively studied. The activation energy (Eb) of the bulk etching rate for the DAM-ADC sheets has been calculated, the dependence of etching efficiency and sensitivity upon etchant concentrations and temperature has been investigated, registration efficiency of DAM-ADC detector etched at the optimum etching condition has been examined. The detailed studied results presented in this study provide various useful information about the mechanism of track formation in polymers.

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

2014-09-01

275

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

276

Beat wave launch of lower-hybrid wave for alpha particle diagnostic  

SciTech Connect

By use of nonlinear mixing of oppositely-directed pump waves of frequency {ital f}{sub 0}{plus_minus}{delta}{ital f}{gt}{ital f}{sub {ital pe}},{ital f}{sub {ital ce}}, a beat wave of frequency {ital f}{sub 12}=2{delta}{ital f} and velocity {ital v}{sub 12}={ital c}{delta}{ital f}/{ital f}{sub 0} may be launched deeply into the interior of a confined plasma. For launch perpendicular to magnetic field at a beat frequency in the lower-hybrid range, {ital f}{sub {ital ci}}{lt}{ital f}{sub 12}{lt}{ital f}{sub {ital ce}}, wave damping is proportional to the local derivative of the fast ion distribution function, {partial_derivative}{ital f}{sub {alpha}}/{ital dv}{parallel}{sub {ital v}}{sub 12}, thus providing (in combination with a wave-scattering diagnostic) a potential means for direct, noninvasive measurement of the local alpha-particle distribution. Present experiments on the Davis Divertor Torus (DDT) are aimed at developing quantitative agreement between computed and actual Langmuir probe measurements of spatial and temporal beat-wave distributions in a three-dimensional plasma volume. {copyright} {ital 1996 American Institute of Physics.}

Horton, R.D.; Evans, R.W.; Hwang, D.Q.; McLean, H.S. [UC Davis/LLNL Livermore, California 94551 (United States); Rogers, J.H. [Princeton Plasma Physics Laboratory, Princeton, New Jersey (United States)

1996-02-01

277

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

SciTech Connect

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

Jaggi, Jaspreet Singh [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Seshan, Surya V. [Department of Pathology, Cornell University Weill Medical College, New York, NY (United States); McDevitt, Michael R. [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Sgouros, George [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD (United States); Hyjek, Elizabeth [Department of Pathology, Cornell University Weill Medical College, New York, NY (United States); Scheinberg, David A. [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States) and Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)]. E-mail: d-scheinberg@ski.mskcc.org

2006-04-01

278

Biodegradation process of alpha-TCP particles and new bone formation in a rabbit cranial defect model.  

PubMed

The purpose of the present study was to observe the biodegradation process of pure alpha-tricalcium phosphate (alpha-TCP) particles and to determine the efficacy of alpha-TCP as a space maintainer in a bone defect. We used 14 rabbits and prepared two cranial bone defects in each rabbit. One defect was left empty as a control, whereas the other was filled with alpha-TCP particles about 300 mum in diameter. Animals were sacrificed at 1 week, 4 weeks, and 8 weeks. The cranial bone was then embedded either in paraffin wax for the preparation of decalcified specimens, or in polyester resin for the preparation of nondecalcified specimens. All specimens were evaluated histologically and histomorphometrically. As a consequence of the degradation of alpha-TCP, a "reticulate structure" appeared in the particles at 1 week and new bone was observed in this structure at 8 weeks. The amount of new bone between the control and experimental groups was not significantly different at any of the time points. However, in the experimental group, new bone at the surface of alpha-TCP was evident even in the center of the defect whereas fibrous connective tissue was dominant in the control group. These results indicate that alpha-TCP is a degradable osteoconductive material that is able to act as a space maintainer for bone regeneration when applied to a bone defect. While there was no significant difference in total bone formation between the experimental and negative control groups, the space-maintaining and osteoconductive properties of the particles may result in more complete bone formation in longer-term studies. PMID:16680680

Kihara, Hidemichi; Shiota, Makoto; Yamashita, Yasuo; Kasugai, Shohei

2006-11-01

279

A quantum model for collective recoil lasing  

NASA Astrophysics Data System (ADS)

Free Electron Laser (FEL) and Collective Atomic Recoil Laser (CARL) are described by the same model of classical equations for properly defined scaled variables. These equations are extended to the quantum domain describing the particle's motion by a Schrdinger equation coupled to a self-consistent radiation field. The model depends on a single collective parameter bar rho which represents the maximum number of photons emitted per particle. We demonstrate that the classical model is recovered in the limit bar rho >> 1, in which the Wigner function associated to the Schrdinger equation obeys to the classical Vlasov equation. On the contrary, for bar rho <= 1, a new quantum regime is obtained in which both FELs and CARLs behave as a two-state system coupled to the self-consistent radiation field and described by Maxwell-Bloch equations.

Bonifacio, R.; Cola, M. M.; Piovella, N.; Robb, G. R. M.

2005-01-01

280

Charge-Collection Length Induced by Proton and Alpha Particle Injected Into Silicon Detectors Due to Funneling Effect  

Microsoft Academic Search

Measured deposited energies by 3 to 70 MeV protons and 9.5 to 24.5 MeV\\/nucleon alpha particles in partially depleted silicon detectors were 2 to 5 times larger than calculated deposited energies in an original depletion layer. All released charge carriers within a charge-collection length were collected. The charge-collection lengths are found to be independent of particle species, energies and stopping

Masashi Takada; Tomoya Nunomiya; Takeshi Ishikura; T. Nakamura

2009-01-01

281

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

Microsoft Academic Search

The possibilities for using 4.7 MeV alpha particles produced at the U-120 CIP Cyclotron for charged particle induced X- and gamma-ray emission applications (PIXE and PIGE, respectively) and for fast neutron radiation damage simulation are presented. The combined analysis using PIGE and PIXE methods either separately or simultaneously is an excellent means of determining the relative abundances of lighter elements

B. Constantinescu; S. Dima; V. Florescu; E. A. Ivanov; D. Plostinaru; C. Srbu

1986-01-01

282

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

NASA Astrophysics Data System (ADS)

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

Amir, Haider F. Abdul; Chee, Fuei Pien

2012-09-01

283

Quantum recoil and Bohm diffusion  

SciTech Connect

It is argued that the inclusion of the Bohm potential in quantum fluid equations is equivalent to inclusion of a nonrelativistic form of the quantum recoil in plasma kinetic theory. The Bohm term is incorrect when applied to waves with phase speed greater than the speed of light.

Melrose, D. B.; Mushtaq, A. [School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia)

2009-09-15

284

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

PubMed Central

Chemokines are chemotactic cytokines that can play a key role in leukocyte recruitment to sites of tissue injury or infection. Previous studies have demonstrated that exposure to alpha-quartz as well as other noxious particles increases chemokine gene expression in rat lung, although the cells responsible for chemokine expression and the mechanisms underlying this response have remained unclear. The present studies demonstrate that exposure of rats to alpha-quartz induced expression of mRNA for the chemokine macrophage-inflammatory protein (MIP)-2 in epithelial cells lining the terminal bronchioles and alveolar ducts as well as macrophages and alveolar type II cells in the more distal lung. Treatment of rats with an anti-MIP-2 antiserum before alpha-quartz exposure markedly attenuated neutrophilic infiltration of the lungs demonstrating an important role for MIP-2 in alpha-quartz-induced pulmonary inflammation. In vitro exposure of primary cultures of rat alveolar type II cells or the rat alveolar type II cell line RLE-6TN to tumor necrosis factor-alpha, endotoxin, or alpha-quartz increased mRNA for MIP-2 as well as the structurally and functionally similar chemokine cytokine-induced neutrophil chemoattractant but not the chemokine MIP-1 alpha. The alpha-quartz-induced increase in epithelial MIP-2 mRNA resulted, at least in part, from increased gene transcription and was associated with the release of active MIP-2 protein. Induction of RLE-6TN MIP-2 and cytokine-induced neutrophil chemoattractant mRNA expression was not unique to alpha-quartz, being also increased by crocidolite asbestus fibers but not by titanium dioxide or MMVF-10 glass fibers. These findings indicate that epithelial cells contribute to chemokine expression in rat lung after exposure to alpha-quartz and potentially other noxious particles and suggest that alpha-quartz-activated MIP-2 expression in vivo results, at least in part, from a direct action of the particles on the lung epithelium. Images Figure 1 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8

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

1996-01-01

285

Evidence for Direct Durable Capture of 1- to 8-Mev Solar Alpha Particles onto Geomagnetically Trapped Orbits.  

National Technical Information Service (NTIS)

By using satellite observations from Injun 5, an examination of the temporal variations of the intensity of geomagnetically trapped alpha particles has been made for the 8-month period September 1968 to April 1969. The most prominent change was a stepwise...

J. A. Van Allen B. A. Randall

1970-01-01

286

Determination of Geometry and Absorption Effects and Their Impact on the Accuracy of Alpha Particle Soft Error Rate Extrapolations  

Microsoft Academic Search

The results of a physical experiment and extensive simulation runs are presented for the first time demonstrating the significant effects of geometry and air absorption on accelerated alpha particle soft error rate tests. These results show that geometry and absorption must be properly accounted for even when the source is in close proximity to the device to avoid substantial underestimation

Robert C. Baumann; Daniele Radaelli

2007-01-01

287

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

SciTech Connect

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

Kuterbekov, K.A.; Zholdybayev, T.K. [Institute of Nuclear Physics, National Nuclear Center of the Republic of Kazakhstan, Almaty, 480082 (Kazakhstan); Kukhtina, I.N.; Penionzhkevich, Yu.E. [Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 (Russian Federation)

2005-06-01

288

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

289

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

PubMed Central

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

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

1998-01-01

290

Synchrotron-radiation experiments with recoil ions  

SciTech Connect

Studies of atoms, ions and molecules with synchrotron radiation have generally focused on measurements of properties of the electrons ejected during, or after, the photoionization process. Much can also be learned, however, about the atomic or molecular relaxation process by studies of the residual ions or molecular fragments following inner-shell photoionization. Measurements are reported of mean kinetic energies of highly charged argon, krypton, and xenon recoil ions produced by vacancy cascades following inner-shell photoionization using white and monochromatic synchrotron x radiation. Energies are much lower than for the same charge-state ions produced by charged-particle impact. The results may be applicable to design of future angle-resolved ion-atom collision experiments. Photoion charge distributions are presented and compared with other measurements and calculations. Related experiments with synchrotron-radiation produced recoil ion, including photoionization of stored ions and measurement of shakeoff in near-threshold excitation, are briefly discussed. 24 refs., 6 figs., 1 tab.

Levin, J.C.

1989-01-01

291

The effects of radon daughter alpha-particle irradiation in K1 and xrs-5 CHO cell lines.  

PubMed

We investigated the radiobiological effects of the radon daughter bismuth-212 (212Bi) in Chinese hamster ovary (CHO) K1 cells and in xrs-5 cells, which are X-ray sensitive and deficient in the ability to rejoin DNA double-strand breaks. The cells were exposed to 250 kVp X-rays or to 212Bi chelated to diethylene triamine pentaacetic acid (DTPA); chelation of 212Bi to DTPA prevented its attachment to or entry into the cells. Cytotoxic, clastogenic, and mutagenic responses of the cells were measured and RBEs (D10, 2 chromatid aberrations/cell and 10 induced 6-thioguanine-resistant mutants) were calculated to be 3.8, 3.5, and 3.9, respectively for K1, and 1.4, 0.8, and 5.1, respectively, for xrs-5. With the exception of the RBE of less than 1 for alpha-induced aberrations in xrs-5, the results are consistent with the following conclusions: (1) alpha-particles are in general more effective cytotoxic, clastogenic and mutagenic agents than X-rays; (2) the primary lethal and clastogenic lesion induced by both X-rays and alpha-particles is probably a DNA double-strand break; (3) DNA double-strand breaks induced by alpha-radiation are less well repaired than those induced by X-rays, although a portion of alpha-induced damage is repairable; and (4) deficiencies in rejoining DNA double-strand breaks affect the clastogenic and cytotoxic effects of X-rays and alpha-radiation, not their mutagenic effects. The RBE of 0.8 for aberration induction in xrs-5 cells could reflect a deficiency in the ability of these cells to convert alpha-induced damage to chromosome aberrations. Alternatively, the RBE of less than 1 might reflect an unusual sensitivity of xrs-5 cells to alpha-induced G2 delays. PMID:2030713

Shadley, J D; Whitlock, J L; Rotmensch, J; Atcher, R W; Tang, J; Schwartz, J L

1991-05-01

292

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

293

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

294

Emission rates of alpha particles from supports with different surface conditions in direct deposition sources.  

PubMed

Direct deposition is the only method that can be utilised for the standardisation of radioactive solutions because there is no deposition loss on a support. The present study investigated how much the roughness of the support influences the emission rate of alpha particles for direct deposition sources from the practical viewpoint of use of the method. A number of samples were prepared by evaporating a 0.1-ml aliquot of a dilute nitric acid aqueous solution that contained (241)Am on stainless steel supports with four different surface conditions; untreated supports were either polished (using metal abrasives available commercially) or not polished, and buffed supports (grid size of #400) were either polished or not polished. Alpha spectrometry of the samples revealed that the detection efficiency was significantly different between the non-polished and polished supports; the former was lower by 3 % than the latter for both the untreated and buffed supports. Microscopic observations clarified that the counting loss was attributed to irregular flaws or polishing lines on the non-polished supports, most of which were found to be in the order of submicron in depth and were diminished on the polished supports. One may usually assume that a direct deposition source offers no counting loss if its entire energy spectrum is seen above a low-energy discrimination limit of the spectrometer. However, this should be experimentally confirmed using a solution with known activity. It was difficult to identify the counting loss for the buffed supports without polishing because their energy spectra showed little degradation. PMID:21097486

Kurihara, Osamu; Saito, Fumihiro; Koarashi, Jun; Kim, Eunjoo; Shiraishi, Kunio; Yamada, Yuji; Akashi, Makoto

2011-04-01

295

The biological effects of Auger electrons compared to alpha-particles and Li ions.  

PubMed

The present study reports the results of V-79 Chinese hamster cell survival studies in which Auger electron emission was stimulated in gadolinium (Gd) after thermal neutron capture. When a porphyrin that had previously been labeled with boron (10BOPP) was also labeled with Gd (Gd-10BOPP), the cells were incubated with Gd-10BOPP to assess the compound's ability to physiologically transport the Gd into the cell, and localize the Gd atoms in or near the cell's critical target, presumably the DNA. It was anticipated that Auger electron emission, stimulated during the 157Gd (n, gamma)158Gd interaction, would impart additional high LET damage to that observed from the alpha-particle and Li ion during the 10B(n, alpha) 7Li reaction. Following irradiation with thermal neutrons from the Brookhaven Medical Research Reactor, the effectiveness of the Auger electrons was determined by comparing the response of cells incubated with 10BOPP, where damage was imparted by the boron neutron capture (BNC) products, to that from Gd-10BOPP, with equal concentration of 10B in both solutions. An Auger effectiveness factor of approximately 2 was found for the Gd-10BOPP cells. The Auger effectiveness observed with Gd strongly suggested that the 10BOPP molecule physiologically transported the Gd3+ ion intracellularly where it probably bound to DNA. Others have reported that Gd3+ does, in fact, complex with DNA. While depositing less energy per interaction than the high LET BNC reaction by-products, Auger electron ionization was more effective. PMID:9004772

Laster, B H; Shani, G; Kahl, S B; Warkentien, L

1996-01-01

296

[Production of 61Cu, 62Zn by alpha and 3He particle bombardment of natural nickel (author's transl)].  

PubMed

The optimum irradiation conditions were investigated for the production of 61Cu and 62Zn by alpha and 3He particle bombardment of natural nickel. Formation cross sections and thick-target yields were obtained for reaction products in the energy range of 10 to 40 MeV. For the production of 61Cu and 62Zn, the alpha particle bombardment was found superior to the 3He particle bombardment in so far as the yield was concerned. When the incident alpha energy of 21 MeV was chosen, after 2.4 hours of cooling, 2.1 mCi/muA.h of 61Cu could be produced with less than 1% of 60Cu contamination. For the production of 62Zn, when the incident alpha energy of 35 MeV and the target thickness of 57 mg /cm2 were chosen, 97.5 muCi/muA.h of 62Zn could be produced. Radiochemical purity of 62Zn was the highest at 12 hours after the end of bombardment. PMID:752170

Muramatsu, H; Shirai, E; Nakahara, H; Murakami, Y

1978-11-01

297

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

298

The recoil shadow anisotropy method  

NASA Astrophysics Data System (ADS)

The Recoil Shadow Anisotropy Method (RSAM) is a new experimental method for identifying isomers in the nanosecond range and measuring their half-lives. This method can be applied to experiments performed with thin targets and ?-ray multidetector arrays including collimated composite detectors and does not require any additional device. It uses the shadow effect imposed by the collimators on the different elements of composite detectors for ?-rays emitted by recoiling nuclei. RSAM was developed for the clover detectors of the Eurogam-2 array and tested using several data sets obtained with this array. A number of known isomers with half-lives lying between 0.9 and 18 ns in 194Hg, 191Au, 148Gd, 149Gd, 193Pb and 194Pb have been successfully re-measured, proving the ability of RSAM for lifetime measurements.

Gueorguieva, E.; Kaci, M.; Schck, C.; Minkova, A.; Vieu, Ch.; Correia, J. J.; Dionisio, J. S.

2001-12-01

299

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

SciTech Connect

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.

Timofeeva, E.; Smith, D. S.; Yu, W.; France, D. M.; Singh, D.; Routbort, J. L. (Energy Systems); ( NE); (Univ. of Illinois)

2010-01-01

300

Primary scintillation characteristics of Ar+CF4 gas mixtures excited by proton and alpha particles  

NASA Astrophysics Data System (ADS)

In this paper, we report how the concentration of carbon-tetrafluoride (CF4) affects the primary scintillation from Ar+CF4 gas mixtures excited by proton and alpha particles. The single photon counting method was used to measure the time spectra of the primary scintillation from Ar, CF4 and their mixtures at atmospheric pressure. Pure Ar exhibits a fast decay time constant, which is approximately 6 ns, and a slow decay time tail. Initially, increases in the concentration of CF4 increase the decay time of the Ar+CF4 gas mixture. However, when the concentration of CF4 exceeds a certain threshold, the decay time decreases to that of pure CF4, approximately 8-9 ns. We also report the photon emission spectra of Ar+CF4 mixtures excited by protons. The emission spectrum of the primary scintillation from Ar is improved by CF4 in both the ultraviolet region and the visible to near-infrared region.

Liu, Jinliang; Ouyang, Xiaoping; Chen, Liang; Zhang, Xianpeng; Liu, Jun; Zhang, Zhongbing; Ruan, Jinlu

2012-12-01

301

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, Cleste D. M.

2012-09-01

302

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

NASA Astrophysics Data System (ADS)

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.; Brckner, J.; Clark, B. C.; Dreibus, G.; Klingelhfer, G.; Lugmair, G.; Ming, D. W.; Wnke, H.; Yen, A.; Zipfel, J.; Squyres, S. W.

2006-01-01

303

Gamma-Ray, Neutron, and Alpha-Particle Spectrometers for the Lunar Prospector mission  

NASA Astrophysics Data System (ADS)

Gamma-Ray, Neutron, and Alpha-Particle Spectrometers (GRS, NS, and APS, respectively) were included in the payload complement of Lunar Prospector (LP). Specific objectives of the GRS were to map abundances of Fe, Ti, Th, K, Si, O, Mg, Al, and Ca to depths of 20 cm. Those of the NS were to search for water ice to depths of 100 cm near the lunar poles and to map regolith maturity. Objectives of the APS were to search for, map, and provide a measure of the time history of gaseous release events at the lunar surface. The purpose of this paper is to document the mechanical, analog electronic, digital electronic, and microprocessor designs of the suite of spectrometers, present a representative sample of the calibrated response functions of all sensors, and document the operation of all three LP spectrometers in sufficient detail as to enable the full knowledgeable use of all data products that were archived in the Planetary Data System for future use by the planetary-science community.

Feldman, W. C.; Ahola, K.; Barraclough, B. L.; Belian, R. D.; Black, R. K.; Elphic, R. C.; Everett, D. T.; Fuller, K. R.; Kroesche, J.; Lawrence, D. J.; Lawson, S. L.; Longmire, J. L.; Maurice, S.; Miller, M. C.; Prettyman, T. H.; Storms, S. A.; Thornton, G. W.

2004-07-01

304

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

305

Reduced proton and alpha particle precipitations at Mars during solar wind pressure pulses: Mars Express results  

NASA Astrophysics Data System (ADS)

We performed a statistical study of downward moving protons and alpha particles of ~keV energy (assumed to be of solar wind origin) inside the Martian induced magnetosphere from July 2006 to July 2010. Ion and electron data are from the Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) package on board Mars Express. We investigated the solar wind ion entry into the ionosphere, excluding intervals of low-altitude magnetosheath encounters. The study compares periods of quiet solar wind conditions and periods of solar wind pressure pulses, including interplanetary coronal mass ejections and corotating interaction regions. The solar wind ion precipitation appears localized and/or intermittent, consistent with previous measurements. Precipitation events are less frequent, and the precipitating fluxes do not increase during pressure pulse encounters. During pressure pulses, the occurrence frequency of observed proton precipitation events is reduced by a factor of ~3, and for He2+ events the occurrence frequency is reduced by a factor of ~2. One explanation is that during pressure pulse periods, the mass loading of the solar wind plasma increases due to a deeper penetration of the interplanetary magnetic flux tubes into the ionosphere. The associated decrease of the solar wind speed thus increases the pileup of the interplanetary magnetic field on the dayside of the planet. The magnetic barrier becomes thicker in terms of solar wind ion gyroradii, causing the observed reduction of H+/He2+ precipitations.

DiVal, C.; Stenberg, G.; Nilsson, H.; Edberg, N. J. T.; Barabash, S.

2013-06-01

306

Alpha decay of the new isotope197Rn  

NASA Astrophysics Data System (ADS)

The new radon isotope197Rn was produced in the reaction169Tm(35Cl, 7n)197Rn using bombarding energies from 5.6 to 6.1 MeV/nucleon. Fusion products were separated in-flight from the primary beam using a gas-filled recoil separator. The alpha particle energy and half-life of197Rn were measured to be (72607) keV and (65{-14/+25}) ms, respectively. Another new alpha line was assigned to an isomeric state in197Rn for which an alpha particle energy of (73567) keV and a half-life of (19{-4/+8}) ms were obtained.

Enqvist, T.; Armbruster, P.; Eskola, K.; Leino, M.; Ninov, V.; Trzaska, W. H.; Uusitalo, J.

1996-12-01

307

Neutrino-recoil induced desorption  

Microsoft Academic Search

Nuclear decay induced [sup 37]Cl ion desorption from the electron capture decay [sup 37]Ar[r arrow][sup 37]Cl+[nu] is reported for the first time. A mixture of one part [sup 36]Ar and [similar to]5[times]10[sup [minus]5] parts [sup 37]Ar ([sup 36\\/37]Ar) is physisorbed on a gold-plated Si wafer kept at 16 K under ultrahigh vacuum conditions. The time of flight (TOF) of recoiled

L. Zhu; R. Avci; G. J. Lapeyre; M. M. Hindi; R. L. Kozub; S. J. Robinson

1994-01-01

308

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

PubMed

We have suggested ultrafine particle coating processes for preparing nanocrystalline particle coated alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route, which is environmentally friendly. The nanometric ammonium aluminum carbonate hydroxide (AACH) as a precursor for coating of alumina was produced from precipitation reaction of ammonium aluminum sulfate and ammonium hydrogen carbonate. The synthetic crystalline size and morphology were greatly dependent on pH and temperature. By adding ammonium aluminum sulfate solution dispersed the alpha-alumina core particle in the ammonium hydrogen carbonate aqueous solution, nanometric AACH with a size of 5 nm was tightly bonded and uniformly coated on the core powder due to formation of surface complexes by the adsorption of carbonates, hydroxyl and ammonia groups on the surface of aluminum oxide. The synthetic precursor rapidly converted to amorphous- and y-alumina phase without significant change in the morphological features through decomposition of surface complexes and thermal-assisted phase transformation. As a result, the nanocrystalline polymorphic particle coated alpha-alumina core powders with highly uniform distribution were prepared from the route of carbonate precipitation and thermal-assisted combustion. PMID:18047085

Kim, Sang Woo; Jung, Young Mi

2007-11-01

309

Mutations in the tumor suppressor gene p53 in human liver cancer induced by alpha-particles.  

PubMed

The p53 tumor suppressor gene is mutated in varying fractions of almost all tumor types studied. The rate of mutations and the mutational spectrum in some tumors are specific for environmental mutagens assumed to be involved in the carcinogenic process. Thus, hepatocellular carcinomas supposedly induced by aflatoxin exposure often contain a specific point mutation in codon 249, and in lung cancers of miners with heavy radon exposure, another specific point mutation in codon 249 suggestive of an alpha-particle-specific mutation has been shown. The interpretation of studies linking the mutational spectrum with specific environmental exposures is complicated by the multifactorial or unknown genesis of most tumors. However, people given injections of the X-ray contrast medium Thorotrast (Th) in the past have experienced an enormous risk of liver tumors, and virtually all of these are supposedly induced by alpha-particles from the decay of 232Th. The examination of these tumors may provide evidence as to whether specific p53 point mutations are relevant in alpha-particle carcinogenesis. Therefore, we collected paraffin-embedded, formalin-fixed archival tissues from 18 hepatocellular carcinomas, 9 cholangiocarcinomas, and 9 hepatic angiosarcomas from Thorotrast-exposed patients. The tissues were analyzed for p53 protein expression by immunohistochemical staining by using the mAb DO-7 and for mutations of exons 5-8 by PCR and constant denaturant gel electrophoresis. G --> T transversions of the third base of codon 249 of the p53 gene were specifically screened for by restriction enzymes. No high score for p53 protein expression (i.e., positive staining of >20% of examined cells) was observed; lower scores were seen in 5 of 18 (28%) hepatocellular carcinomas, 1 of 9 (11%) cholangiocarcinomas, and 0 of 8 (0%) hepatic angiosarcomas. Only one p53 mutation, a heterozygous T --> G transversion of the first base codon 176, occurred in a hepatocellular carcinoma. The rate of p53 point mutations in alpha-particle-induced liver tumors seems to be lower than in European hepatocellular carcinomas in general. The study does not exclude the possibility that alpha-particle carcinogenesis may involve inactivation of p53 by gross deletions of the gene, but it speaks against the proposed specificity of point mutations of codon 249 in cancer supposedly induced by alpha-particles from radon progeny. PMID:8672994

Andersson, M; Jnsson, M; Nielsen, L L; Vyberg, M; Visfeldt, J; Storm, H H; Wallin, H

1995-01-01

310

The measurement of 240Pu/ 239Pu and 238Pu/ 239Pu isotopic ratios by alpha-particle spectrometry  

NASA Astrophysics Data System (ADS)

The measurement of the alpha-activity ratio of {238Pu }/{( 239Pu + 240Pu) } is a routine practice in the determination of the isotopic composition of plutonium. However, measurement of the atomic ratio of 240Pu/ 239Pu by alpha-particle spectrometry is hampered due to insufficient energy resolution for the set of closely spaced peaks of these two isotopes. Passivated and implanted, planar silicon (PIPS) detectors have recently become available with an energy resolution of 10 keV or better, which significantly improves the deconvolution of spectra from plutonium samples. A set of alpha sources was prepared on porcelain disks by ignition, and the spectra were accumulated at a gain of approximately 1 keV per channel. The GRPANL computer program as developed by Lawrence Livermore National Laboratory was used to analyze the spectra. The isotopic ratios were measured in parallel by mass spectrometry. It was found that the agreement on the ratios of 240Pu/ 239Pu and 238Pu/ 239Pu between mass spectrometry and measurements by PIPS detectors was within 2%. Half-life values were obtained from the literature (M. Lammer and O. Schwerer, Handbook of Nuclear Data for Safeguards, Rep. INDC(NDS)-248, IAEA, Vienna, 1991; ref. [5]). Other factors were also studied to improve the accuracy of the data. The alpha-particle emission probabilities of highly enriched 239Pu and 240Pu have been measured. The alpha-particle energies obtained in the fitting were in agreement with those in ref. [5]. The fitted energy values were used throughout this work.

Raab, W.; Parus, J. L.

1994-01-01

311

Refueling pellets as a source of charge exchange neutrals for alpha particle measurements  

Microsoft Academic Search

Alpha interactions with neutrals in the ablation cloud of a refueling pellet are considered as a fast alpha diagnostic through charge-capture radiation (ACCR) by the alphas or their complete neutralization and escape. Calculations of pellet penetration into a reactor plasma indicate that regions of r\\/a>0.61 could be reached by refueling pellets with initial radii of 4 mm, hence this would

G. Gerdin

1987-01-01

312

Nanodosimetry and nanodosimetric-based models of radiation action for radon alpha particles. Final performance technical report  

SciTech Connect

The goal of this project was to develop theoretical/computational tools for evaluating the risks incurred by populations exposed to radon alpha particles. Topics of concern include the following: compound dual radiation action (general aspects); a mathematical formalism describing the yield of radiation induced single-and double-strand DNA breaks, and its dependence on radiation quality; a study of the excited states in cytosine and guanine stacks in the Hartree-Fock and exciton approximations; nanodosimetry of radon alpha particles; application of the HSEF to assessing radiation risks in the practice of radiation protection; carcinogenic risk coefficients at environmental levels of radon exposures: a microdosimetric approach; and hit-size effectiveness approach in radiation protection.

Zaider, M.

1997-12-31

313

Refueling pellets as a source of charge exchange neutrals for alpha particle measurements  

SciTech Connect

Alpha interactions with neutrals in the ablation cloud of a refueling pellet are considered as a fast alpha diagnostic through charge-capture radiation (ACCR) by the alphas or their complete neutralization and escape. Calculations of pellet penetration into a reactor plasma indicate that regions of r/a>0.61 could be reached by refueling pellets with initial radii of 4 mm, hence this would be an outer core diagnostic. A spherically symmetric neutral-gas shielding model (SSMNGSM) in which ionization is treated self-consistently and governed by local thermodynamic equilibrium is used in these calculations. Collisional processes are found to govern the alpha--cloud interactions and local equilibrium calculations were performed in which the charge exchange and ionization cross sections are used to obtain the state fractions of the alphas in the cloud. At 1640 A the ratio of ACCR to cloud bremsstrahlung is found to be 10/sup -5/ whereas at 304 A this ratio ranges from 3 x 10/sup -3/ to 0.5 for the cases considered; no neutralized alphas escape the cloud. Magnetic field effects are considered and they appear to reduce the bremsstrahlung from the cloud by a factor of 300 at 304 A in regions perpendicular to the magnetic field from the pellet's surface; escape of neutralized alphas may be possible in these directions. Alpha refueling pellet interactions are potentially useful as outer core fast alpha diagnostics and this could be tested in near term experiments.

Gerdin, G.

1987-12-01

314

Elastic and inelastic scattering of alpha particles from 40,44Ca over a broad range of energies and angles  

Microsoft Academic Search

Angular distributions for alpha particle elastic scattering by 40,44Ca and excitation of the 3.73 MeV 3- collective state of 40Ca were measured for incident energies ranging from 40 to 62 MeV. An extensive optical model analysis of these elastic scattering cross sections and other available data, using squared Woods-Saxon form factors, results in potentials with fixed geometry for both real

Th. Delbar; Gh. Grgoire; G. Paic; R. Ceuleneer; F. Michel; R. Vanderpoorten; A. Budzanowski; H. Dabrowski; L. Freindl; K. Grotowski; S. Micek; R. Planeta; A. Strzalkowski; K. A. Eberhard

1978-01-01

315

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

SciTech Connect

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

Zaider, M.

1992-12-31

316

Production cross sections of lithium and beryllium isotopes in 12C by high-energy protons and alpha particles  

Microsoft Academic Search

The formation cross sections of 6Li, 7Li and 7Be, 9Be, 10Be by high-energy protons and alpha-particles in a 12C target have been determined by a high sensitivity mass-spectrometric technique. A method for extracting lithium and beryllium from the irradiated graphite without interference by natural contamination has been developed. Cross sections have been measured for 150 MeV and 600 MeV protons

P. Fontes; C. Perron; J. Lestringuez; F. Yiou; R. Bernas

1971-01-01

317

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

Microsoft Academic Search

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

Hatsumi Nagasawa; Paul F. Wilson; David J. Chen; Larry H. Thompson; Joel S. Bedford; John B. Little

2008-01-01

318

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

Microsoft Academic Search

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

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

2007-01-01

319

The Role of Heat Flux in Governing the Thermal Behavior of Alpha Particles in the Fast Solar Wind  

Microsoft Academic Search

We present a 16-moment, three-fluid description of the solar wind consisting of electrons, protons, and alpha particles. We assume gyrotropic flow (transport across the magnetic field is neglected) which reduces the 16-moment set of transport equations to a six-moment set yielding the density, velocity, temperatures parallel and perpendicular to the magnetic field, and parallel heat conductive fluxes from the parallel

L. A. Allen; X. Li

2005-01-01

320

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

SciTech Connect

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

Burtebayev, N.; Nassurlla, Marzhan; Nassurlla, Maulen; Kerimkulov, Zh. K. [Institute of Nuclear Physics, Almaty (Kazakhstan); Sakuta, S. B. [Russian Research Center 'Kurchatov Institute', Moscow (Russian Federation)

2008-11-11

321

Bismuth212-labeled anti-Tac monoclonal antibody: alpha-particle-emitting radionuclides as modalities for radioimmunotherapy  

Microsoft Academic Search

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

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

1986-01-01

322

Cytogenetic and molecular genetic analysis of tumorigenic human bronchial epithelial cells induced by radon alpha particles.  

PubMed

To establish a cell culture model for lung carcinogenesis, independent populations of the human papillomavirus 18-immortalized human bronchial epithelial cell line BEP2D were treated with high linear energy transfer radon-simulated alpha-particles, expanded and xenotransplanted into Nu/Nu mice. Six independent cell lines were established from tumors that developed from three separate radiation treatments as follows: treatment (Tx) 1 (30 cGy--two doses), H2BT, Tx 2 (30 cGy--single dose), R30T1L, R30T2 and R30T3L, Tx 3 (30 cGy--single dose), H1ATN and H1ATBA1. Cytogenetic analysis revealed common changes in all tumor lines: loss of the Y chromosome (ch), one of three copies of ch8, one of three copies of ch14, and one of two copies of ch4p16-pter and ch11p15-pter. Analysis of polymerase chain reaction-amplified short tandem repeats of informative loci confirmed the loss of chY in all lines and loss of heterozygosity (LOH) at eight loci spanning the length of ch8 in all lines from Tx's 1 and 2. Our data support previous studies indicating the presence of tumor suppressor genes on ch8. LOH also was confirmed on ch14 at locus D14S306 in all cell lines from Tx 2 and in one of two lines from Tx 3. This region, 14q12-q13, may contain changes in one of the five known somatostatin receptor genes (SSTR1). No LOH was detected at any of the informative loci tested for on ch4 or ch11. PMID:9214610

Weaver, D A; Hei, T K; Hukku, B; McRaven, J A; Willey, J C

1997-06-01

323

Deletion-pattern analysis of alpha-particle and X-ray induced mutations at the HPRT locus of V79 Chinese hamster cells.  

PubMed

To investigate the mutagenic mechanisms of low-energy alpha particles V79 Chinese hamster cells were irradiated with 241Am-alpha particles (mean LET of 112 keV/micron). Parallel experiments were performed using 300 kV X-rays. Cell inactivation and mutation induction cross sections were measured. At approximately 20%--survival level, DNA deletions were analysed at the HPRT locus by multiplex-PCR-analysis of all nine exons of 47 alpha-irradiated and 36 background mutants. 92 HPRT- mutants isolated after 300 kV-X-irradiation were analysed similarly for comparison, along with 15 corresponding background mutants. The resulting mutant deletion-pattern distributions were corrected for background mutations. alpha Particles induced a larger fraction of deletions than X-rays. Furthermore, non-contiguous partial deletions were present among the alpha-induced mutants, a type not found after X-irradiation. PMID:9852989

Schmidt, P; Kiefer, J

1998-11-01

324

The Role of Heat Flux in Governing the Thermal Behavior of Alpha Particles in the Fast Solar Wind  

NASA Astrophysics Data System (ADS)

We present a 16-moment, three-fluid description of the solar wind consisting of electrons, protons, and alpha particles. We assume gyrotropic flow (transport across the magnetic field is neglected) which reduces the 16-moment set of transport equations to a six-moment set yielding the density, velocity, temperatures parallel and perpendicular to the magnetic field, and parallel heat conductive fluxes from the parallel and perpendicular directions for each particles species. The model incorporates the effects of Coulomb collisions. It allows for non-radial divergence of the magnetic field and heating and momentum addition to the particles. We investigate the influence of the heat conductive flux in shaping the temperature anisotropy.

Allen, L. A.; Li, X.

2005-12-01

325

The biological effectiveness of radon-progeny alpha particles. III. Quality factors  

SciTech Connect

Domestic radon risk estimates are typically based either on data for uranium miners or on data derived from A-bomb survivors; comparison of domestic radon risk estimates derived from these two disparate sources represents an important test of their reliability. There is currently a significant discrepancy of about a factor of three between domestic radon risk estimates generated with these two independent methods. To base such risk estimates on the data for A-bomb survivors, who were exposed mainly to low-LET radiation, requires a quality factor for {alpha} particles from radon progeny; the final risk estimate is then directly proportional to this quality factor. We have used the most extensive quantitative in vitro data set currently available at high LET for an oncogenic end point, to make the best estimate we can that could be used as a basis for a quality factor. Our best estimates of values appropriate for the quality factor for radon progeny are significantly lower than those currently used (20-25) in estimating lung cancer mortality due to radon. Specifically, our best estimate for home dwellers is around 10. In addition, because of the different geometry in the bronchial epithelia of nonsmokers compared to smokers, our best estimate of an appropriate quality factor for home dwellers is about 18% greater than that for miners; thus our best estimate of the {open_quotes}effective K factor{close_quotes} to convert to effective dose/WLM in miners would be increased by this factor. Based on a quality factor of {approximately}10, the dosimetrically based estimate of radon-induced mortality would be {approximately}35,000 per year in the U.S. rather than the value of {approximately}70,000 obtained using a quality factor of 20. The value of 35,000, while larger than the values based on data for miners ({approximately}20,000), is much smaller than previous estimates of {approximately}70,000 based on dosimetric methods. 54 refs., 7 figs.

Brenner, D.J.; Miller, R.C.; Huang, Y. [Columbia Univ., New York, NY (United States)] [and others

1995-04-01

326

The biological effectiveness of radon-progeny alpha particles. III. Quality factors.  

PubMed

Domestic radon risk estimates are typically based either on data for uranium miners or on data derived from A-bomb survivors; comparison of domestic radon risk estimates derived from these two disparate sources represents an important test of their reliability. There is currently a significant discrepancy of about a factor of three between domestic radon risk estimates generated with these two independent methods. To base such risk estimates on the data for A-bomb survivors, who were exposed mainly to low-LET radiation, requires a quality factor for alpha particles from random progeny; the final risk estimate is then directly proportional to this quality factor. We have used the most extensive quantitative in vitro data set currently available at high LET for an oncogenic end point, to make the best estimate we can that could be used as a basis for a quality factor. Our best estimates of values appropriate for the quality factor for radom progeny are significantly lower than those currently used (20-25) in estimating lung cancer mortality due to randon. Specifically, our best estimate for home dwellers is around 10. In addition, because of the different geometry in the bronchial epithelia of nonsmokers compared to smokers, our best estimate of an appropriate quality factor for home dwellers is about 18% greater than that for miners; thus our best estimate of the "effective K factor" to convert to effective dose/WLM in home dwellers from effective dose/WLM in miners would be increased by this factor. Based on a quality factor of approximately 10, the dosimetrically based estimate of radon-induced mortality would be approximately 35,000 per year in the U.S. rather than the value of approximately 70,000 obtained using a quality factor of 20. The value of 35,000, while larger than the values based on data for miners (approximately 20,000), is much smaller than previous estimates of approximately 70,000 based on dosimetric methods; thus risk estimates based on the two approaches, dosimetric and epidemiological, may be partially reconciled. Finally, a quality factor of 10 would reduce the proportion of the collective effective dose caused by radon progeny from the currently accepted value of 55% down to about 38%. PMID:7899560

Brenner, D J; Miller, R C; Huang, Y; Hall, E J

1995-04-01

327

Channeling patterns recorded using radioactive recoil atoms  

Microsoft Academic Search

Differences in the penetration of Rn-220 recoil atoms injected from a Ra-224 point source into single crystals of Si, SiO2 and KCl were used to record patterns showing directions and planes along which the recoil atoms channeled deeper into the crystal.

C. Jech

1972-01-01

328

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

SciTech Connect

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.

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

1986-01-01

329

The Collective Atomic Recoil Laser  

NASA Astrophysics Data System (ADS)

An ensemble of periodically ordered atoms coherently scatters the light of an incident laser beam. The scattered and the incident light may interfere and give rise to a light intensity modulation and thus to optical dipole forces which, in turn, emphasize the atomic ordering. This positive feedback is at the origin of the collective atomic recoil laser (CARL). We demonstrate this dynamics using ultracold atoms confined by dipole forces in a unidirectionally pumped far red-detuned high-finesse optical ring cavity. Under the influence of an additional dissipative force exerted by an optical molasses the atoms, starting from an unordered distribution, spontaneously form a density grating moving at constant velocity. Additionally, steady state lasing is observed in the reverse direction if the pump laser power exceeds a certain threshold. We compare the dynamics of the atomic trajectories to the behavior of globally coupled oscillators, which exhibit phase transitions from incoherent to coherent states if the coupling strength exceeds a critical value.

Courteille, Ph. W.; von Cube, C.; Deh, B.; Kruse, D.; Ludewig, A.; Slama, S.; Zimmermann, C.

2005-05-01

330

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

PubMed

The yield of single-strand breaks (ssb) and double-strand breaks (dsb) produced by alpha-particles at the end of their track in DNA-films was determined experimentally. Helium nuclei were accelerated to 600 keV in the 400 kV ion accelerator and scattered at a carbon target. The elastically scattered alpha-particles with energies of 344 keV and 485 keV were used to irradiate supercircular plasmid DNA in vacuo. For the dosimetry of the alpha-particles a surface barrier detector was used and the energy distribution of the alpha-particles determined. The energy loss of the particles in the DNA-layer was calculated. DNA samples were separated into the three conformational isomers using agarose gel electrophoresis. After fluorochromation the number of ssb and dsb per plasmid DNA molecule was established from the band intensities assuming the validity of Poisson statistics. Linear dose effect correlations were found for ssb and dsb per plasmid molecule. In the case of 344 keV-alpha-particles the yield of dsb was (8.6 +/- 0.9) x 10(-11) breaks/Gy x dalton. The ratio of ssb/dsb was 0.5 +/- 0.2. This is at least a factor of six larger than the ratio found in experiments with higher energy alpha-particles and from model calculations. Similar experiments with protons yielded a relative biological effectiveness (rbe) value of 2.8 for the induction of double-strand breaks by track end alpha-particles. PMID:9232893

Scholz, V; Weidner, J; Khnlein, W; Frekers, D; Wrtche, H J

1997-01-01

331

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; Gnter, 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

332

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

333

Development of a He- and He0 beam source for alpha particle measurement in a burning plasma  

NASA Astrophysics Data System (ADS)

Proof of principle experiments of neutral helium beam production for alpha particle diagnostics was carried out on a test stand. Negative helium ions were produced in the Li charge exchange cell, in which stable and long time operation was possible. He- beam was accelerated to 157 keV. Finally, He0 beam was successfully produced after the flight in the drift-tube through the auto-electron-detachment process from He- to He0. A neutral beam detector using a pyroelectric device was also developed to measure He0 beam intensity. The metastable component in the neutral helium beam was found to be less than 2%.

Tanaka, N.; Sasao, M.; Terai, K.; Okamoto, A.; Kitajima, S.; Yamaoka, H.; Wada, M.

2012-02-01

334

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

SciTech Connect

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

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

2003-03-26

335

Standardisation of low-activity actinide solutions by alpha-particle counting at a defined solid angle.  

PubMed

In the frame of an IAEA co-ordinated research project 232U, 236Pu and 229Th tracers were standardised by alpha-particle counting at a defined solid angle. The aim of this project was to assign property values that are traceable to the International System of Units (SI). This article depicts the standardisation of the tracers, elaborating on problems related to low activity and interference from daughter nuclides. The activity concentrations of 232U, 236Pu and 229Th were found to be, respectively (734+/-4), (142.0+/-0.9) and (528.2+/-2.6) Bq g(-1), at reference date (1 January 2003). PMID:15177379

Sibbens, G; Pomm, S; Altzitzoglou, T

2004-01-01

336

Scattering of Alpha Particles by Oxygen. I. Bombarding Energy Range 5.8 to 10.0 MeV  

Microsoft Academic Search

Absolute differential cross sections for the elastic scattering of alpha particles by O16 have been measured as a function of bombarding energy in the range 5.8-10.0 MeV. Measurements were made at center-of-mass angles of 90.0, 109.9, 114.0, 125.3, 131.4, 140.8, 149.4, 154.0, 158.8, and 163.8. Detailed angular distributions have been measured at 6.97, 8.63, and 9.92 MeV (lab). Sixteen resonances

W. E. Hunt; M. K. Mehta; R. H. Davis

1967-01-01

337

Contribution from the inner shell of water vapour to dose profiles under proton and alpha particle irradiation  

NASA Astrophysics Data System (ADS)

Doubly differential cross sections for electron emission calculated using the CDW - EIS model and a simple approximation for the electron transport in the target are used to obtain dose profiles around the ion path for proton and alpha particles in water vapour. The contribution from each initial molecular orbital is determined. At large distances from the track, discrepancies are found with other models and with the well known dependence.

Olivera, G. H.; Fainstein, P. D.; Rivarola, R. D.

1996-09-01

338

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

339

Scattering of {alpha} Particles on {sup 11}B Nuclei at Energies 40 and 50 MeV  

SciTech Connect

The differential cross sections for elastic and inelastic scattering of {alpha} particles on {sup 11}B nuclei at energies of 40 and 50 MeV were measured in the entire angular range. The measured angular distributions were analyzed in terms of the optical model, the distorted-wave Born approximation, and the coupled-channel method. Optical model potentials and quadrupole ({beta}{sub 2}) and hexadecapole ({beta}{sub 4}) deformation parameters were found from this analysis. The rise in the cross sections at backward angles was shown to be associated with the transfer mechanism of the heavy {sup 7}Li cluster.

Burtebaev, N.; Baktybaev, M.K.; Duisebaev, B.A. [Institute of Nuclear Physics, National Nuclear Center, Almaty (Kazakhstan); Peterson, R.J. [University of Colorado (United States); Sakuta, S.B. [Russian Research Centre Kurchatov Institute, pl. Akademika Kurchatova 1, Moscow, 123182 (Russian Federation)

2005-08-01

340

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 37C. 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.

2012-01-01

341

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

342

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

343

Comparison of alpha-particle and neutron-induced combinational and sequential logic error rates at the 32nm technology node  

Microsoft Academic Search

We report on particle induced upset rates of combinational and sequential logic. A novel test chip has been designed in a 32 nm process to study the effects of single event transients (SET) and to verify the accuracy of our simulation models. The test chip has been tested under neutron and alpha particle radiation. Our measured data verify simulation-based projections

B. Gill; N. Seifert; V. Zia

2009-01-01

344

Bystander effect for chromosomal aberrations induced in wild-type and repair deficient CHO cells by low fluences of alpha particles  

Microsoft Academic Search

We have previously shown that when confluent cultures of mammalian cells are exposed to very low fluences of alpha particles, fluences whereby as few as 1% of the cell nuclei are traversed by a single particle, genetic effects including specific gene mutations and sister chromatid exchanges (SCE) are induced in neighboring, non-irradiated bystander cells. The present investigation was designed to

Hatsumi Nagasawa; John B. Little

2002-01-01

345

Helium measurements simulating alpha-particle diagnostics by the pellet charge exchange in Large Helical Device  

NASA Astrophysics Data System (ADS)

It is very important to investigate the confinement of ? particle, which is produced by the nuclear reaction in ITER or fusion reactor. The pellet charge exchange measurement (PCX) is one of the most powerful methods because it can directly provide the profile of ? particle energy spectra in plasma. In Large Helical Device (LHD), it is possible to confine the high energetic particle (helium) accelerated by using the ion cyclotron resonance heating (ICH). Therefore it is possible to perform the simulation experiment of ? particle diagnostic in LHD.

Ozaki, T.; Goncharov, P.; Veschev, E.; Sudo, S.; Tamura, N.

2008-03-01

346

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

NASA Astrophysics Data System (ADS)

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

Constantinescu, B.; Dima, S.; Florescu, V.; Ivanov, E. A.; Plo?tinaru, D.; Srbu, C.

1986-07-01

347

Gas powered fluid gun with recoil mitigation  

DOEpatents

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

Grubelich, Mark C; Yonas, Gerold

2013-11-12

348

Recoil effects in a bag model  

SciTech Connect

We attempt to resolve a recent dispute regarding the size, as well as the proper formulation, of recoil corrections to baryon magnetic moments in a bag model. It is demonstrated that the overall center-of-the-system (OCS) motion, when factored out properly to yield the momentum-conservation delta-functions, cannot give rise to additional and sizable recoil corrections as addressed by Betz and Goldflam and independently by Guichon. Thus, the only contribution due to baryon recoil comes from the spinor rotation of the constituent quarks.

Gattone, A.O.; Hwang, W.P.

1984-11-15

349

Photon recoil momentum in dispersive media.  

PubMed

A systematic shift of the photon recoil momentum due to the index of refraction of a dilute gas of atoms has been observed. The recoil frequency was determined with a two-pulse light grating interferometer using near-resonant laser light. The results show that the recoil momentum of atoms caused by the absorption of a photon is n variant Planck's k, where n is the index of refraction of the gas and k is the vacuum wave vector of the photon. This systematic effect must be accounted for in high-precision atom interferometry with light gratings. PMID:15904272

Campbell, Gretchen K; Leanhardt, Aaron E; Mun, Jongchul; Boyd, Micah; Streed, Erik W; Ketterle, Wolfgang; Pritchard, David E

2005-05-01

350

Photon Recoil Momentum in Dispersive Media  

SciTech Connect

A systematic shift of the photon recoil momentum due to the index of refraction of a dilute gas of atoms has been observed. The recoil frequency was determined with a two-pulse light grating interferometer using near-resonant laser light. The results show that the recoil momentum of atoms caused by the absorption of a photon is n({Dirac_h}/2{pi})k, where n is the index of refraction of the gas and k is the vacuum wave vector of the photon. This systematic effect must be accounted for in high-precision atom interferometry with light gratings.

Campbell, Gretchen K.; Leanhardt, Aaron E.; Mun, Jongchul; Boyd, Micah; Streed, Erik W.; Ketterle, Wolfgang; Pritchard, David E. [MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2005-05-06

351

Recoiling DNA molecule: simulation and experiment  

NASA Astrophysics Data System (ADS)

Single molecule DNA experiments often generate data from force versus extension measurements involving the tethering of a microsphere to one end of a single DNA molecule while the other is attached to a substrate. We show that the persistence length of single DNA molecules can also be measured based on the recoil dynamics of these DNA-microsphere complexes if appropriate corrections are made to the friction coefficient of the microsphere in the vicinity of the substrate. Comparison between computer simulated recoil curves, generated from the corresponding Langevin equation, and experimental recoils are used to assure the validity of data analysis.

Neto, Jos Coelho; Dickman, Ronald; Mesquita, O. N.

2005-01-01

352

Scattering and Recoiling Imaging Spectrometry (SARIS) Study of Pt(111)  

NASA Astrophysics Data System (ADS)

Scattering and recoiling imaging spectrometry (SARIS) uses a time-resolving and position sensitive microchannel plate (MCP) to measure the velocity-resolved spatial distribution pattern of scattered and recoiled particles from a single crystalline surface. The SARIS images combine the advantage of atomic scale microscopy and spatial averaging simultaneously since they are created from a macroscopic surface area but they are directly related to the short range atomic arrangement of the surface. SARIS is applied to the Pt(111) surface to elucidate basic phenomena in ion scattering processes such as blocking, focusing, and semichanneling. Furthermore, it is capable of qualitative determination of the structure of Pt(111) by interatomic vector analysis based on blocking cones extracted from experimental images. Quantitative structural analysis is achieved by systematic comparison between the experimental results and those of computer simulations. A computer simulation program called scattering and recoiling imaging code (SARIC), based on the well-established classical ion scattering theory, has been developed for such simulations.

Kim, C.; Hfner, C.; Bykov, V.; Rabalais, J. W.

1997-03-01

353

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

354

High resolution alpha particle detection using 4H-SiC epitaxial layers: Fabrication, characterization, and noise analysis  

NASA Astrophysics Data System (ADS)

In this article we report the fabrication and characterization of large area, room-temperature operable and very high resolution Schottky barrier detectors for alpha particles using 20 ?m thick n-type 4H-SiC epitaxial layers. Schottky barriers were fabricated by depositing circular nickel contacts of ~11 mm2 area on the 4H-SiC epitaxial layers. Room temperature current-voltage measurements revealed very high Schottky barrier height of 1.6 eV and extremely low leakage current of 3.5 pA at an operating reverse bias of -90 V. We also report an energy resolution of 0.29%, which is the best resolution obtained so far for uncollimated 5.48 MeV alpha particles in 4H-SiC epitaxial detectors with such a large area. Very low micropipe density (<1 cm-2) and low effective doping concentration (2.41014 cm-3) in the epilayer helped to achieve a high resolution even with the large detector area and a broad source. A diffusion length of ~18.6 ?m for holes has been determined in these detectors following a calculation based on a drift-diffusion model. A noise analysis in terms of equivalent noise charge revealed that the white series noise due to the detector capacitance has substantial effect on their spectroscopic performance.

Chaudhuri, Sandeep K.; Zavalla, Kelvin J.; Mandal, Krishna C.

2013-11-01

355

Fabrication of substrates with curvature for cell cultivation by alpha-particle irradiation and chemical etching of PADC films  

NASA Astrophysics Data System (ADS)

In the present paper, we developed a microfabrication technology to generate cell-culture substrates with identical chemistry and well-defined curvature. Micrometer-sized pits with curved surfaces were created on a two-dimensional surface of a polymer known as polyallyldiglycol carbonate (PADC). A PADC film was first irradiated by alpha particles and then chemically etched under specific conditions to generate pits with well-defined curvature at the incident positions of the alpha particles. The surface with these pits was employed as a model system for studying the effects of substrate curvature on cell behavior. As an application, the present work studied mechanosensing of substrate curvature by epithelial cells (HeLa cells) through regulation of microtubule (MT) dynamics. We used end-binding protein 3-green fluorescent protein (EB3-GFP) as a marker of MT growth to show that epithelial cells having migrated into the pits with curved surfaces had significantly smaller MT growth speeds than those having stayed on flat surfaces without the pits.

Ng, C. K. M.; Tjhin, V. T.; Lin, A. C. C.; Cheng, J. P.; Cheng, S. H.; Yu, K. N.

2012-05-01

356

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

SciTech Connect

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

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

1987-10-01

357

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

358

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

359

Collective atomic recoil laser (CARL) optical gain without inversion by collective atomic recoil and self-bunching of two-level atoms  

NASA Astrophysics Data System (ADS)

We suggest a novel tunable laser concept, the Collective Atomic Recoil Laser (CARL) which unifies the physics of the FEL and of the atomic lasers. We demonstrate that a cold beam of two-level particles driven coherently by a counter-propagating resonant wave can amplify exponentially a co-propagating optical probe up to a saturation value through an instability very similar to that of a high gain FEL. In addition, the two level atoms undergo collective recoil and exponential self-bunching in space and form a longitudinal grating on the scale of the wavelength of the amplified optical signal.

Bonifacio, R.; De Salvo, L.

1994-03-01

360

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

361

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

362

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

SciTech Connect

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

Chen, K. R.; Tsai, T. H.; Chen, L. [Physics Department, Institute of Electro-Optical Science and Engineering, and Plasma and Space Science Center, National Cheng Kung University, Tainan 701, Taiwan (China); Physics Department and Plasma and Space Science Center, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

2010-02-15

363

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

PubMed

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

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

2010-02-01

364

Outgassing from alpha particle irradiation of lithium hydride and lithium hydroxide  

Microsoft Academic Search

We have experimentally studied the effects of ?-particle radiation on isotopically enriched lithium hydride (6LiH) and its corrosion product lithium hydroxide (6LiOH) to determine, in particular, the type and amount of gases evolved during irradiation. SRIM Monte Carlo simulations suggest that irradiating these materials with 2.2-MeV ?-particles will ionize atoms and form hydrogen vacancies in the target material, and that

Carol Haertling; Igor Usov; Yongqiang Wang

2011-01-01

365

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

366

The Radiation Chemistsry of Aqueous Solutions. III. The Isotope Effect for Polonium alpha-Particles and Tritium beta-Particles  

Microsoft Academic Search

Investigations similar to those described in parts I and II for ordinary water have been made on D_2O. For tritium beta-particles the derived yields are GD = 3\\\\cdot340\\\\cdot03, GOD = 2\\\\cdot260\\\\cdot1, GD_2O_2 = 0\\\\cdot81_5 0\\\\cdot02, GD_2 = 0.27_50.08_5 and G-D_2O = 3\\\\cdot890\\\\cdot14. Observed yields G(Ce3+)T1^+ = 7\\\\cdot500.5, G(Fe3+)-O_2 = 7\\\\cdot150\\\\cdot15, G(D_2)0\\\\cdot1N = 0\\\\cdot610\\\\cdot02 and G(D_2O_2)O_2_i = 1\\\\cdot020\\\\cdot1 are close to

E. Collinson; F. S. Dainton; J. Kroh

1962-01-01

367

Propagation effects in the quantum description of collective recoil lasing  

NASA Astrophysics Data System (ADS)

The free electron laser and collective atomic recoil laser (CARL) are examples of collective recoil lasing, where exponential amplification of a radiation field occurs simultaneously with self-bunching of an ensemble of particles (electrons in the case of the FEL and atoms in the case of the CARL). In this paper, we discuss quantum and propagation effects using a model where the particle dynamics are described quantum-mechanically in terms of a matter-wave field, which evolves self-consistently with the radiation field. The model shows that the scattered radiation evolves superradiantly both in the case where the particle ensemble is short compared to the cooperation length of the system, and where the ensemble is long compared to the cooperation length. In both short and long pulse cases there exist a classical and quantum regime of superradiant emission. For short samples in both quantum and classical regimes the superradiant pulse has a low peak intensity and is said to exhibit 'weak' superradiance. For long pulses in both quantum and classical regimes of evolution, the dynamics at the rear edge of the sample is dominated by propagation. This produces a 'strong' superradiant pulse with much higher peak intensity than that predicted by 'mean-field' or 'steady-state' models in which propagation effects are neglected.

Bonifacio, R.; Piovella, N.; Robb, G. R. M.; Cola, M. M.

2005-08-01

368

Experimental validation of an analytical method to obtain the response function of an alpha particle spectrometer  

PubMed

In a previous paper, one of the authors suggested an analytical method for calculation of the response function of an alpha spectrometer for the case of large solid angles. This paper describes the experimental verification of the method. Spectra of a well-known natural uranium sample were measured with a 450 mm2 Si detector and compared to the theoretical predictions. The measurements were carried out with two different geometrical configurations. In both cases a good agreement was observed between experimental and theoretical results. PMID:10724372

Romanikhin; Garcia-Torano Martinez E

2000-03-01

369

Single particle tracking of alpha7 nicotinic AChR in hippocampal neurons reveals regulated confinement at glutamatergic and GABAergic perisynaptic sites.  

PubMed

Alpha7 neuronal nicotinic acetylcholine receptors (alpha7-nAChR) form Ca(2+)-permeable homopentameric channels modulating cortical network activity and cognitive processing. They are located pre- and postsynaptically and are highly abundant in hippocampal GABAergic interneurons. It is unclear how alpha7-nAChRs are positioned in specific membrane microdomains, particularly in cultured neurons which are devoid of cholinergic synapses. To address this issue, we monitored by single particle tracking the lateral mobility of individual alpha7-nAChRs labeled with alpha-bungarotoxin linked to quantum dots in live rat cultured hippocampal interneurons. Quantitative analysis revealed different modes of lateral diffusion of alpha7-nAChR dependent on their subcellular localization. Confined receptors were found in the immediate vicinity of glutamatergic and GABAergic postsynaptic densities, as well as in extrasynaptic clusters of alpha-bungarotoxin labeling on dendrites. alpha7-nAChRs avoided entering postsynaptic densities, but exhibited reduced mobility and long dwell times at perisynaptic locations, indicative of regulated confinement. Their diffusion coefficient was lower, on average, at glutamatergic than at GABAergic perisynaptic sites, suggesting differential, synapse-specific tethering mechanisms. Disruption of the cytoskeleton affected alpha7-nAChR mobility and cell surface expression, but not their ability to form clusters. Finally, using tetrodotoxin to silence network activity, as well as exposure to a selective alpha7-nAChR agonist or antagonist, we observed that alpha7-nAChRs cell surface dynamics is modulated by chronic changes in neuronal activity. Altogether, given their high Ca(2+)-permeability, our results suggest a possible role of alpha7-nAChR on interneurons for activating Ca(2+)-dependent signaling in the vicinity of GABAergic and glutamatergic synapses. PMID:20634896

Brli, Thomas; Baer, Kristin; Ewers, Helge; Sidler, Corinne; Fuhrer, Christian; Fritschy, Jean-Marc

2010-01-01

370

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

PubMed Central

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

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

2012-01-01

371

Application of the Monte Carlo method to study the alpha particle energy spectra for radioactive aerosol sampled by an air filter.  

PubMed

An alpha spectrometer including a semi-conductor detector is commonly used for measurements of the emergent alpha particles from an air filter, on which was sampled a radioactive aerosol. The alpha spectrometry and the detection efficiency are necessary input information for real radioactivity measurements. The MCNPX code based on the Monte Carlo method has been applied to simulate the detection process in order to obtain spectrum peaks and determine the detection efficiency for modeled geometry. First simulations with MCNPX have been carried out in order to validate the alpha particle energy spectrometry of an electrodeposited solid source and an initial simulated filter model. Furthermore, to improve our first filter model, the real spatial distribution of radioactive aerosols across the filter thickness, found experimentally, is taken into account in a multi-layer filter model. Such an alpha particle distribution allows achieving an adequate simulation of the filter. Comparison between measured and simulated alpha spectra highlights the good agreement in spectral parameters and in detection efficiency even under different aerosol spatial distributions inside the volume of the filter. PMID:19590272

Geryes, T; Monsanglant-Louvet, C; Berger, L; Gehin, E

2009-08-01

372

Channeling of Fusion Alpha-Particle Power Using Minority Ion Catalysis  

NASA Astrophysics Data System (ADS)

Maintaining fuel ions hotter than electrons would greatly facilitate controlled nuclear fusion. The parameter range for achieving this temperature disparity is shown here to be enhanced by catalyzing the ?-channeling effect (wave-induced simultaneous expulsion and cooling of ? particles) through minority-ion heating. Specifically, a wave can extract energy from hot ? particles and transfer it to colder minority ions, which act as a catalyst, eventually forwarding the energy to still colder fuel ions through collisions. In comparison with the traditional ?-channeling mechanism, the requirements are thereby relaxed on the waves that accomplish the ? channeling, which no longer have to interact simultaneously with ? particles and fuel ions. Numerical simulations illustrate how the new scheme may increase, for example, the effective fusion reactivity of mirror-confined plasmas.

Zhmoginov, A. I.; Fisch, N. J.

2011-10-01

373

Alpha decay studies near ^100Sn  

NASA Astrophysics Data System (ADS)

Nuclei around the exotic doubly-magic ^100Sn can provide key information to, and serve as rigorous tests of, the nuclear shell model. In particular, the energy splitting between neutron single-particle orbits in this region, the ?d5/2 - ?g7/2, can be extracted from the low-energy excited states in the odd-N Sn isotopes, ideally from ^101Sn. Identification and examination of these nuclei is aided by the presence of an island of alpha and proton radioactivity for nuclei with Z > 50 near ^100Sn. The isotopes ^109Xe and ^105Te were identified at the Holifield Radioactive Ion Beam Facility using the Recoil Mass Spectrometer through the observation of the characteristic alpha decay chain ^109Xe -> ^105Te -> ^101Sn. The efficient identification of the fast ^105Te alpha decay was enabled through the use of digital signal processing using advanced pulse shape analysis alogrithms. The unique double alpha decay pulse provided an ideal tag to observe gamma-ray emission from the excited states of both ^105Te and ^101Sn at approximately 150 and 172 keV, respectively. Both excited states in ^105Te and ^101Sn were populated through alpha decay. The observation of the first excited state in ^101Sn provides the ?d5/2 - ?g7/2 energy splitting. Using the experimental value in shell model calculations suggests an ordering of single particle states in ^101Sn that contradicts previous expectations. The possibility of reaching the ^108Xe -> ^104Te -> ^100Sn alpha decay chain will also be discussed.

Liddick, Sean

2008-10-01

374

Outgassing from alpha particle irradiation of lithium hydride and lithium hydroxide  

NASA Astrophysics Data System (ADS)

We have experimentally studied the effects of ?-particle radiation on isotopically enriched lithium hydride ( 6LiH) and its corrosion product lithium hydroxide ( 6LiOH) to determine, in particular, the type and amount of gases evolved during irradiation. SRIM Monte Carlo simulations suggest that irradiating these materials with 2.2-MeV ?-particles will ionize atoms and form hydrogen vacancies in the target material, and that these ?-particles will penetrate 13.5 and 9 ?m into LiH and LiOH, respectively. Using an accelerator to irradiate LiH and LiOH with 2.2-MeV ?-particles released only H 2 and CO 2; no other product gases were observed. At 25 C, doses that simulated 66.5 years of actinide exposure (with accelerated fluxes) produced 2.3 10 5 mol/(cm 3 J) H 2 in LiH and 2.3 10 6 mol/(cm 3 J) H 2 in LiOH, in the form of a 9-?m-thick surface layer on LiH. More H 2 evolved from LiOH than from LiH. We argue that the production of H 2 gas was the result of radiolysis, rather than radiation-induced chemical reaction.

Haertling, Carol; Usov, Igor; Wang, Yongqiang

2011-02-01

375

Study of Creep in Stainless Steel Irradiated with Fast Neutron and alpha Particles.  

National Technical Information Service (NTIS)

The objective of the present work is to study the creep behavior of the 316 type stainless steel 50% cold worked in different conditions of temperature and applied stress, after neutron radiation and Alfa particles implantation. For this experiment, non-i...

D. A. C. Correa Tese

1985-01-01

376

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

PubMed

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

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

2013-09-01

377

Hit rates and radiation doses to nuclei of bone lining cells from alpha-particle-emitting radionuclides.  

PubMed

Factors relating the local concentration of a bone-seeking alpha-particle emitter to the mean hit rate have been determined for nuclei of bone lining cells using a Monte Carlo procedure. Cell nuclei were approximated by oblate spheroids with dimensions and location taken from a previous histomorphometric study. The Monte Carlo simulation is applicable for planar and diffuse labels at plane or cylindrical bone surfaces. Additionally, the mean nuclear dose per hit, the dose mean per hit, the mean track segment length and its second moment, the percentage of stoppers, and the frequency distribution of the dose have been determined. Some basic features of the hit statistics for bone lining cells have been outlined, and the consequences of existing standards of radiation protection with regard to the hit frequency to cell nuclei are discussed. PMID:1641467

Polig, E; Jee, W S; Kruglikov, I L

1992-08-01

378

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

SciTech Connect

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

Sakuta, S. B., E-mail: sakuta@dni.polyn.kiae.s [Russian Research Centre Kurchatov Institute (Russian Federation); Artemov, S.V. [Uzbek Academy of Sciences, Institute of Nuclear Physics (Uzbekistan); Burtebaev, N.; Kerimkulov, Zh. [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan); Novatsky, B. G.; Stepanov, D.N. [Russian Research Centre Kurchatov Institute (Russian Federation); Yarmukhamedov, R. [Uzbek Academy of Sciences, Institute of Nuclear Physics (Uzbekistan)

2009-12-15

379

Hit rates and radiation doses to nuclei of bone lining cells from alpha-particle-emitting radionuclides  

NASA Technical Reports Server (NTRS)

Factors relating the local concentration of a bone-seeking alpha-particle emitter to the mean hit rate have been determined for nuclei of bone lining cells using a Monte Carlo procedure. Cell nuclei were approximated by oblate spheroids with dimensions and location taken from a previous histomorphometric study. The Monte Carlo simulation is applicable for planar and diffuse labels at plane or cylindrical bone surfaces. Additionally, the mean nuclear dose per hit, the dose mean per hit, the mean track segment length and its second moment, the percentage of stoppers, and the frequency distribution of the dose have been determined. Some basic features of the hit statistics for bone lining cells have been outlined, and the consequences of existing standards of radiation protection with regard to the hit frequency to cell nuclei are discussed.

Polig, E.; Jee, W. S.; Kruglikov, I. L.

1992-01-01

380

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

381

Inelastic processes in ion\\/surface collisions: Direct recoil ion fractions as a function of kinetic energy  

Microsoft Academic Search

Time-of-flight (TOF) spectra of the scattered and recoiled particles resulting from 110 keV Ar+ ions impingent on surfaces of MgO, Mg(OH)2, graphite, Si, and SiO2 have been obtained. Measurements of directly recoiled (DR) neutrals plus ions and neutrals only are used to calculate positive and negative ion fractions Y+,? from DR events. These positive and negative ion yields observed for

J. Wayne Rabalais; Jie-Nan Chen

1986-01-01

382

Exploitation of the charge sharing effect in Timepix device to achieve sub-pixel resolution in imaging applications with alpha particles.  

NASA Astrophysics Data System (ADS)

The Timepix device is a pixelated silicon detector. Because of its structure, an incoming particle can deposit its energy in several adjacent pixels as a result of the charge sharing effect. The distribution of energy in the pixels activated by a heavy charged particle can be exploited to determine the entering point of the particle with a precision better than the pixel dimensions. This is experimentally illustrated by images of different samples obtained with alpha particles. This work was carried out within the CERN Medipix Collaboration.

Teyssier, C.; Gurin, P. Allard; Bergeron, G.; Dallaire, F.; Leroy, C.; Pospisil, S.; Trudeau, Y. B.

2012-08-01

383

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

PubMed

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

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

2008-11-01

384

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

SciTech Connect

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

Neal, John S [ORNL; Giles, N. C. [West Virginia University; Yang, Xiaocheng [West Virginia University; Wall, R. Andrew [Wake Forest University, Winston-Salem, NC; Ucer, Burak [Wake Forest University, Winston-Salem, NC; Williams, Richard T. [Wake Forest University, Winston-Salem, NC; Wisniewski, Dariusz J [ORNL; Boatner, Lynn A [ORNL; Rengarajan, Varatharajan [ORNL; Nause, Jeff E [ORNL; Nemeth, Bell [Cermet, Inc., Atlanta

2008-01-01

385

Observation of nuclear recoil events from neutron scattering in low temperature calorimetric detectors  

Microsoft Academic Search

Energy spectra are obtained for low temperature calorimetric detectors exposed to a neutron source to produce nuclear recoil events simulating those which would occur in a ``dark matter'' detector. The targets used were a 4 g Si crystal and a 32 g LiF crystal, fitted with Ge temperature sensors to observe the particle scattering events as thermal pulses at a

P. F. Smith; G. J. Homer; S. F. J. Read; D. J. White; J. D. Lewin; N. J. C. Spooner

1991-01-01

386

Investigation of Chemical-Vapour-Deposition Diamond Alpha-Particle Detectors  

NASA Astrophysics Data System (ADS)

Diamond films with [100] texture were prepared by a hot-filament chemical vapour deposition technique to fabricate particle detectors. The response of detectors to 5.5 MeV 241Am particles is studied. The photocurrent increases linearly and then levels off with voltage, and 7 nA is obtained at bias voltage of 100 V. The time-dependent photocurrent initially increases rapidly and then tends to reach saturation. Furthermore, a little increase of the dark-current after irradiation can be accounted for by the release of the charges captured by the trapping centres at low energy levels during irradiation. An obvious peak of the pulse height distribution can be observed, associated with the energy of 5.5 MeV.

Gu, Bei-Bei; Wang, Lin-Jun; Zhang, Ming-Long; Xia, Yi-Ben

2004-10-01

387

Minimum ionizing and alpha particles detectors based on epitaxial semiconductor silicon carbide  

Microsoft Academic Search

The relatively high value of the energy required to produce an electron-hole pair in silicon carbide, SiC, by a minimum ionizing particle (MIP) against the value for Si, imposes severe constrains in the crystallographic quality, the thickness and the doping concentration of the SiC epitaxial layer used as the detection medium. In this work, a 40 ?m thick 4 H-SiC

F. Nava; P. Vanni; M. Bruzzi; S. Lagomarsino; S. Sciortino; G. Wagner; C. Lanzieri

2004-01-01

388

Onboard detection of intrinsic Ly. alpha. radiation from a neutral particle beam  

Microsoft Academic Search

We consider photometers onboard a hydrogen neutral particle beam (NPB) space platform which monitor the instrinsic radiation from excited atoms in the NPB in flight. The radiation of choice is the Lyman α (Lyα) line 1216 A, emitted when the beam's {approx equal} 7% fraction of H (2S) atoms is motionally quenched in the earth's magnetic field. At nominal 20-MeV

R. T. Robiscoe; D. D. Cobb; W. B. II Maier

1990-01-01

389

Alpha-particle formation and decay rates from SkyrmeHFB wave functions  

NASA Astrophysics Data System (ADS)

? decay is treated microscopically, where the unstable mother nucleus and residual daughter nucleus are described using HartreeFockBogoliubov (HFB) wave functions, obtained with the Skyrme effective interaction. From these wave functions the amplitude for forming ? particles in the mother nucleus is computed. Two different Skyrme parametrizations with different pairing properties are compared, and we find good agreement with experiment for relative decay rates in both cases. The absolute values of the decay rates are underestimated.

Ward, D. E.; Carlsson, B. G.; berg, S.

2014-05-01

390

Development of phoswich detectors for simultaneous counting of alpha particles and other radiations (emitted from Actinides)  

Microsoft Academic Search

In order to develop actinide monitors, simultaneous counting of ? particles and other radiations has been investigated by means of phoswich detectors. Typical phoswiches devised up to the present consist of the following: ZnS(Ag)\\/NE102A for ? and ?(?) counting, ZnS(Ag)\\/NaI (Tl) or YAP for ? and ?(?) counting, ZnS(Ag)\\/anthracene\\/6Li glass for ?, ?(?), thermal- and fast-neutron counting, etc. Optical filters

Shigekazu Usuda; Kenichiro Yasuda; Satoshi Sakurai

1998-01-01

391

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

392

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

393

The biological effectiveness of radon-progeny alpha particles. II. Oncogenic transformation as a function of linear energy transfer  

SciTech Connect

Epidemiological studies have established an association between exposure to radon and carcinoma of the lung. However, based on data for either lung cancer in uranium miners exposed to radon or bronchial epithelial carcinomas in Japanese A-bomb survivors, it has not been possible to assign estimates of risk of lung cancer for the general population exposed to radon in their homes. Based on past success with the excellent quantitative properties of the C3H 10T1/2 in vitro oncogenic transformation assay system, the relative biological effectiveness (RBE) for radiation-induced transformation for charged particles of defined LET has been determined. As the LET of the radiation was increased, the rate of induction of oncogenic transformation increased and the RBE{sub m} approached 20. At higher LETs, RBE dropped precipitously. The rapid drop in effectiveness for {alpha} particles with LETs between 120 and 265 KeV/{mu}m implies a lower quality factor than the 20-25 currently considered appropriate when estimating lung cancer mortality. 29 refs., 3 figs., 21 tabs.

Miller, R.C.; Marino, S.A.; Brenner, D.J. [College of Physicians and Surgeons of Columbia Univ., New York, NY (United States)] [and others

1995-04-01

394

Microdosimetry of alpha particles for simple and 3D voxelised geometries using MCNPX and Geant4 Monte Carlo codes.  

PubMed

Microdosimetry using Monte Carlo simulation is a suitable technique to describe the stochastic nature of energy deposition by alpha particle at cellular level. Because of its short range, the energy imparted by this particle to the targets is highly non-uniform. Thus, to achieve accurate dosimetric results, the modelling of the geometry should be as realistic as possible. The objectives of the present study were to validate the use of the MCNPX and Geant4 Monte Carlo codes for microdosimetric studies using simple and three-dimensional voxelised geometry and to study their limit of validity in this last case. To that aim, the specific energy (z) deposited in the cell nucleus, the single-hit density of specific energy f(1)(z) and the mean-specific energy were calculated. Results show a good agreement when compared with the literature using simple geometry. The maximum percentage difference found is <6 %. For voxelised phantom, the study of the voxel size highlighted that the shape of the curve f(1)(z) obtained with MCNPX for <1 m voxel size presents a significant difference with the shape of non-voxelised geometry. When using Geant4, little differences are observed whatever the voxel size is. Below 1 m, the use of Geant4 is required. However, the calculation time is 10 times higher with Geant4 than MCNPX code in the same conditions. PMID:21993801

Elbast, M; Saudo, A; Franck, D; Petitot, F; Desbre, A

2012-07-01

395

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, Hlya

2014-05-01

396

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

NASA Astrophysics Data System (ADS)

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

Schuurmans, P.; Will, B.; Berkes, I.; Camps, J.; de Jesus, M.; de Moor, P.; Herzog, P.; Lindroos, M.; Paulsen, R.; Severijns, N.; van Geert, A.; van Duppen, P.; Vanneste, L.; Nicole Collaboration; ISOLDE Collaboration

1996-12-01

397

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

PubMed Central

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

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

2012-01-01

398

Stripping of two protons and one alpha particle transfer reactions for (sup 16) O + (sup A) Sm and their influence on the fusion cross section.  

National Technical Information Service (NTIS)

Transfer cross section angular distribution data for the stripping of two protons and one alpha particle are studied for the (sup 16) O + (sup A) Sm systems (A=144, 148, 150, 152 and 154), at near barrier energies. A semiclassical formalism is used to der...

A. M. M. Maciel P. R. Gomes

1995-01-01

399

Influence of cell position relative to planar alpha-particle sources on survival and preneoplastic transformation of primary rat tracheal epithelial cells  

SciTech Connect

Rat tracheal epithelial cells exposed directly on planar {sup 210}Po sources exhibited exponential cell killing; however, no significant increase in induction of preneoplastic transformation was observed over a range of {alpha}-particle fluences (0.017-0.050 {mu}m{sup {minus}2}). In contrast, up to 10-fold increases in frequencies of preneoplastic transformants, above control levels, were observed after exposure of rat tracheal epithelial cells to similar {alpha}-particle fluences on {sup 238}Pu and {sup 241}Am sources. Two alternative hypotheses are evaluated as an explanation for this apparent difference in the biological effect of {alpha} particles emitted from different sources: (a) possible interactions between effects produced by {alpha} particles and by low-energy photons, which occur with {sup 238}Pu and {sup 241}Am but not with {sup 210}Po; and (b) the influence of spatial relationships between exposed cells and the surface of the planar source. The data suggest that the cell-to-source spatial relationships affect both survival and transformation markedly. 29 refs., 4 figs., 6 tabs.

Terzaghi-Howe, M.; Turner, J.E. [Oak Ridge National Laboratory, TN (United States); Ford, J.R. [Medical Research Council, Oxon (United Kingdom)

1996-04-01

400

Gamma-diagnostics of alpha-particles in 4He and D-T plasmas  

NASA Astrophysics Data System (ADS)

This article reports on ?-ray diagnosis of ICRF-accelerated 4He ions and fusion ? particles used in the JET tokamak. This diagnostic based on the analysis of ? rays emitted in nuclear reaction 9Be(?,n?)12C. The results of the first observation of the 4.44-MeV ?-radiation due to the reaction 9Be(?,n?)12C in JET deuterium-tritium experiment (DTE1) are presented. Gamma-ray spectra have been recorded with collimated spectrometer, and the ?-ray emission radial profiles measured with the JET neutron/gamma profile monitor. Doppler broadening effects which could be used for the ICRF-accelerated 4He-ion diagnosis with high energy resolution ?-ray detectors are discussed. Capabilities of the ?-ray measurements in next step D-T devices are discussed.

Kiptily, V. G.; Popovichev, S.; Sharapov, S. E.; Bertalot, L.; Cecil, F. E.; Conroy, S.; Mantsinen, M. J.

2003-03-01

401

Alpha-Particle Emitting 213Bi-Anti-EGFR Immunoconjugates Eradicate Tumor Cells Independent of Oxygenation  

PubMed Central

Hypoxia is a central problem in tumor treatment because hypoxic cells are less sensitive to chemo- and radiotherapy than normoxic cells. Radioresistance of hypoxic tumor cells is due to reduced sensitivity towards low Linear Energy Transfer (LET) radiation. High LET ?-emitters are thought to eradicate tumor cells independent of cellular oxygenation. Therefore, the aim of this study was to demonstrate that cell-bound ?-particle emitting 213Bi immunoconjugates kill hypoxic and normoxic CAL33 tumor cells with identical efficiency. For that purpose CAL33 cells were incubated with 213Bi-anti-EGFR-MAb or irradiated with photons with a nominal energy of 6 MeV both under hypoxic and normoxic conditions. Oxygenation of cells was checked via the hypoxia-associated marker HIF-1?. Survival of cells was analysed using the clonogenic assay. Cell viability was monitored with the WST colorimetric assay. Results were evaluated statistically using a t-test and a Generalized Linear Mixed Model (GLMM). Survival and viability of CAL33 cells decreased both after incubation with increasing 213Bi-anti-EGFR-MAb activity concentrations (9.25 kBq/ml1.48 MBq/ml) and irradiation with increasing doses of photons (0.512 Gy). Following photon irradiation survival and viability of normoxic cells were significantly lower than those of hypoxic cells at all doses analysed. In contrast, cell death induced by 213Bi-anti-EGFR-MAb turned out to be independent of cellular oxygenation. These results demonstrate that ?-particle emitting 213Bi-immunoconjugates eradicate hypoxic tumor cells as effective as normoxic cells. Therefore, 213Bi-radioimmunotherapy seems to be an appropriate strategy for treatment of hypoxic tumors.

Gaertner, Florian C.; Bruchertseifer, Frank; Morgenstern, Alfred; Essler, Markus; Senekowitsch-Schmidtke, Reingard

2013-01-01

402

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

PubMed

Hypoxia is a central problem in tumor treatment because hypoxic cells are less sensitive to chemo- and radiotherapy than normoxic cells. Radioresistance of hypoxic tumor cells is due to reduced sensitivity towards low Linear Energy Transfer (LET) radiation. High LET ?-emitters are thought to eradicate tumor cells independent of cellular oxygenation. Therefore, the aim of this study was to demonstrate that cell-bound ?-particle emitting (213)Bi immunoconjugates kill hypoxic and normoxic CAL33 tumor cells with identical efficiency. For that purpose CAL33 cells were incubated with (213)Bi-anti-EGFR-MAb or irradiated with photons with a nominal energy of 6 MeV both under hypoxic and normoxic conditions. Oxygenation of cells was checked via the hypoxia-associated marker HIF-1?. Survival of cells was analysed using the clonogenic assay. Cell viability was monitored with the WST colorimetric assay. Results were evaluated statistically using a t-test and a Generalized Linear Mixed Model (GLMM). Survival and viability of CAL33 cells decreased both after incubation with increasing (213)Bi-anti-EGFR-MAb activity concentrations (9.25 kBq/ml-1.48 MBq/ml) and irradiation with increasing doses of photons (0.5-12 Gy). Following photon irradiation survival and viability of normoxic cells were significantly lower than those of hypoxic cells at all doses analysed. In contrast, cell death induced by (213)Bi-anti-EGFR-MAb turned out to be independent of cellular oxygenation. These results demonstrate that ?-particle emitting (213)Bi-immunoconjugates eradicate hypoxic tumor cells as effective as normoxic cells. Therefore, (213)Bi-radioimmunotherapy seems to be an appropriate strategy for treatment of hypoxic tumors. PMID:23724085

Wulbrand, Christian; Seidl, Christof; Gaertner, Florian C; Bruchertseifer, Frank; Morgenstern, Alfred; Essler, Markus; Senekowitsch-Schmidtke, Reingard

2013-01-01

403

Recoil-ion and electron momentum spectroscopy: reaction-microscopes  

NASA Astrophysics Data System (ADS)

Recoil-ion and electron momentum spectroscopy is a rapidly developing technique that allows one to measure the vector momenta of several ions and electrons resulting from atomic or molecular fragmentation. In a unique combination, large solid angles close to 4pi and superior momentum resolutions around a few per cent of an atomic unit (a.u.) are typically reached in state-of-the art machines, so-called reaction-microscopes. Evolving from recoil-ion and cold target recoil-ion momentum spectroscopy (COLTRIMS), reaction-microscopesthe `bubble chambers of atomic physics'mark the decisive step forward to investigate many-particle quantum-dynamics occurring when atomic and molecular systems or even surfaces and solids are exposed to time-dependent external electromagnetic fields. This paper concentrates on just these latest technical developments and on at least four new classes of fragmentation experiments that have emerged within about the last five years. First, multi-dimensional images in momentum space brought unprecedented information on the dynamics of single-photon induced fragmentation of fixed-in-space molecules and on their structure. Second, a break-through in the investigation of high-intensity short-pulse laser induced fragmentation of atoms and molecules has been achieved by using reaction-microscopes. Third, for electron and ion-impact, the investigation of two-electron reactions has matured to a state such that the first fully differential cross sections (FDCSs) are reported. Fourth, comprehensive sets of FDCSs for single ionization of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies. In addition, a brief summary on the kinematics is provided at the beginning. Finally, the rich future potential of the method is briefly envisaged.

Ullrich, J.; Moshammer, R.; Dorn, A.; Drner, R.; Schmidt, L. Ph H.; Schmidt-Bcking, H.

2003-09-01

404

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...

405

Identification of B-Cell Epitopes on Virus-Like Particles of Cutaneous Alpha-Human Papillomaviruses ?  

PubMed Central

Human papillomavirus (PV) (HPV) types 2, 27, and 57 are closely related and, hence, represent a promising model system to study the correlation of phylogenetic relationship and immunological distinctiveness of PVs. These HPV types cause a large fraction of cutaneous warts occurring in immunocompromised patients. Therefore, they constitute a target for the development of virus-like particle (VLP)-based vaccines. However, the immunogenic structure of HPV type 2, 27, and 57 capsids has not been studied yet. Here we provide, for the first time, a characterization of the B-cell epitopes on VLPs of cutaneous alpha-HPVs using a panel of 94 monoclonal antibodies (MAbs) generated upon immunization with capsids from HPV types 2, 27, and 57. The MAbs generated were characterized regarding their reactivities with glutathione S-transferase-L1 fusion proteins from 18 different PV types, the nature of their recognized epitopes, their isotypes, and their ability to neutralize HPV type 2, 27, 57, or 16. In total, 33 of the 94 MAbs (35%) showed type-specific reactivity. All type-specific MAbs recognize linear epitopes, most of which map to the hypervariable surface loop regions of the L1 amino acid sequence. Four of the generated MAbs neutralized pseudovirions of the inoculated HPV type efficiently. All four MAbs recognized epitopes within the BC loop, which is required and sufficient for their neutralizing activity. Our data highlight the immunological distinctiveness of individual HPV types, even in comparison to their closest relatives, and they provide a basis for the development of VLP-based vaccines against cutaneous alpha-HPVs.

Senger, Tilo; Becker, Maria R.; Schadlich, Lysann; Waterboer, Tim; Gissmann, Lutz

2009-01-01

406

Identification of B-cell epitopes on virus-like particles of cutaneous alpha-human papillomaviruses.  

PubMed

Human papillomavirus (PV) (HPV) types 2, 27, and 57 are closely related and, hence, represent a promising model system to study the correlation of phylogenetic relationship and immunological distinctiveness of PVs. These HPV types cause a large fraction of cutaneous warts occurring in immunocompromised patients. Therefore, they constitute a target for the development of virus-like particle (VLP)-based vaccines. However, the immunogenic structure of HPV type 2, 27, and 57 capsids has not been studied yet. Here we provide, for the first time, a characterization of the B-cell epitopes on VLPs of cutaneous alpha-HPVs using a panel of 94 monoclonal antibodies (MAbs) generated upon immunization with capsids from HPV types 2, 27, and 57. The MAbs generated were characterized regarding their reactivities with glutathione S-transferase-L1 fusion proteins from 18 different PV types, the nature of their recognized epitopes, their isotypes, and their ability to neutralize HPV type 2, 27, 57, or 16. In total, 33 of the 94 MAbs (35%) showed type-specific reactivity. All type-specific MAbs recognize linear epitopes, most of which map to the hypervariable surface loop regions of the L1 amino acid sequence. Four of the generated MAbs neutralized pseudovirions of the inoculated HPV type efficiently. All four MAbs recognized epitopes within the BC loop, which is required and sufficient for their neutralizing activity. Our data highlight the immunological distinctiveness of individual HPV types, even in comparison to their closest relatives, and they provide a basis for the development of VLP-based vaccines against cutaneous alpha-HPVs. PMID:19793806

Senger, Tilo; Becker, Maria R; Schdlich, Lysann; Waterboer, Tim; Gissmann, Lutz

2009-12-01

407

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

408

Sonic Rarefaction Wave Low Recoil Gun.  

National Technical Information Service (NTIS)

A principal challenge faced by the U.S. Army TACOM-ARDEC Benet Laboratories in the design of armaments for lightweight future fighting vehicles with lethality overmatch is mitigating the deleterious effects of large caliber cannon recoil. The sonic RArefa...

E. Kathe R. Dillon

2002-01-01

409

Proton recoil scintillator neutron rem meter  

DOEpatents

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

Olsher, Richard H. (Los Alamos, NM); Seagraves, David T. (Los Alamos, NM)

2003-01-01

410

Optical recoil of asymmetric nano-optical antenna  

NASA Astrophysics Data System (ADS)

We propose nano-optical antennas with asymmetric radiation patterns as light-driven mechanical recoil force generators. Directional antennas are found to generate recoil force efficiently when driven in the spectral proximity of their resonances. It is also shown that the recoil force is equivalent to the Poynting vector integrated over a closed sphere containing the antenna structures.

Song, Jung-Hwan; Shin, Jonghwa; Lim, Hee-Jin; Lee, Yong-Hee

2011-08-01

411

Gold Coated Lanthanide Phosphate Nanoparticles for Targeted Alpha Generator Radiotherapy  

SciTech Connect

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

McLaughlin, Mark F [ORNL; Woodward, Jonathan [ORNL; Boll, Rose Ann [ORNL; Wall, Jonathan [University of Tennessee, Knoxville (UTK); Rondinone, Adam Justin [ORNL; Kennel, Steve J [ORNL; Mirzadeh, Saed [ORNL; Robertson, David J. [University of Missouri

2013-01-01

412

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

413

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

PubMed

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(+), H(2) (+), and H(3) (+)). 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(+), H(2) (+), and H(3) (+)). 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. PMID:18315152

Kim, Tae-Seong; Kim, Jinchoon; In, Sang Ryul; Jeong, Seung Ho

2008-02-01

414

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

415

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

416

Cell Cycle Checkpoint Proteins p21 and Hus1 Regulating Intercellular Signaling Induced By Alpha Particle Irradiation  

NASA Astrophysics Data System (ADS)

In recent years, the attentions for radiation induced bystander effects (RIBE) have been paid on the intercellular signaling events connecting the irradiated and non-irradiated cells. p21 is a member of the Cip/Kip family and plays essential roles in cell cycle progression arrest after cellular irradiation. DNA damage checkpoint protein Hus1 is a member of the Rad9-Rad1-Hus1 complex and functions as scaffold at the damage sites to facilitate the activation of downstream effectors. Using the medium trasfer method and the cells of MEF, MEF (p21-/-), MEF (p21-/-Hus1-/-) as either medium donor or receptor cells, it was found that with 5cGy alpha particle irradiation, the bystander cells showed a significant induction of -H2AX for normal MEFs (p0.05). However, the absence of p21 resulted in deficiency in inducing bystander effects. Further results indicated p21 affected the intercellular DNA damage signaling mainly through disrupting the production or release of the damage signals from irradiated cells. When Hus1 and p21 were both knocked out, an obvious induction of -H2AX recurred in bystander cells and the induction of -H2AX was GJIC (gap junction-mediated intercellular communication) dependent, indicating the interrelationship between p21 and Hus1 regulated the production and relay of DNA damage signals from irradiated cells to non-irradiated bystander cells.

Wu, Lijun; Zhao, Ye; Wang, Jun; Hang, Haiying

417

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

SciTech Connect

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

Lagoyannis, A.; Konstantinopoulos, T.; Demetriou, P.; Harissopulos, S. [Institute of Nuclear Physics, NCSR 'Demokritos', 153.10 Aghia Paraskevi, Athens (Greece); Becker, H.-W. [DTL-Institut fuer Experimentalphysik III, Ruhr-Universitaet Bochum, 40781 Bochum (Germany)

2008-05-12

418

Low-altitude measurements of precipitating protons, alpha particles, and heavy ions during the geomagnetic storm on March 26-27, 1976  

NASA Technical Reports Server (NTRS)

During the geomagnetic storm of March 16-17, 1976, observations were made of precipitating protons, alpha particles, and heavy ions by two counter telescopes aboard the low-altitude S3-2 satellite. These observations are presented in this paper and their significance discussed. Briefly, a two-zone precipitation region is observed on the nightside, at L equals 2.7 and L equals 4.0 with an alpha/p ratio of about 0.008 in the low-latitude region and about 0.0009 at higher latitude at 0.4 MeV/necleon. The heavier ions, CNO nuclei, are seen in the low-latitude zone with a CNO/alpha ratio of about 0.056 at 0.25 MeV/nucleon.

Scholer, M.; Hovestadt, D.; Hartmann, G.; Blake, J. B.; Fennell, J. F.; Gloeckler, G.

1979-01-01

419

A Recoil Mass Spectrometer for the HHIRF facility  

SciTech Connect

A Recoil Mass Spectrometer (RMS) is to be built that will carry out a broad research program in heavy-ion science. The RMS will make possible the study of otherwise inaccessible exotic nuclei. Careful attention has been given to match the RMS to all the beams available from the HHIRF accelerators, including those beams with the highest energy, as well as massive particles for use in inverse reactions. The RMS is to be a momentum achromat followed by a split electric-dipole mass spectrometer of the type operating at NSRL at the University of Rochester. The RMS is essential for many of the proposed experiments on short-lived and/or low cross-section products. The spectrometer design is discussed, with examples and comparisons with other spectrometers given. Detector arrays to be used with the RMS are also discussed. 21 refs., 4 figs., 1 tab.

Cole, J.D. (EG and G Idaho, Inc., Idaho Falls, ID (USA)); Cormier, T.M. (Texas A and M Univ., College Station, TX (USA)); Hamilton, J.H. (Vanderbilt Univ., Nashville, TN (USA). Dept. of Physics and Astronomy)

1989-01-01

420

Theory of a collective atomic recoil laser  

NASA Astrophysics Data System (ADS)

We perform a study of a collective atomic recoil laser (CARL) that goes beyond the initial growth period. The study is based on a theory that treats both internal and external degrees of atomic freedom quantum mechanically but regards the laser light as a classical field obeying Maxwell's equations. We introduce the concepts of momentum families and diffraction groups and organize the matter wave equations in terms of diffraction groups. The steady-state lasing conditions are discussed in connection with the probe gain in the recoil-induced resonances. The nontrivial steady states and the linear stability analysis of the steady states are both carried out by the method of two-dimensional continued fractions. Both stable and unstable nontrivial steady states are calculated and discussed in the context of regarding the CARL as multiwave mixing involving many modes of matter waves and two optical fields.

Ling, H. Y.; Pu, H.; Baksmaty, L.; Bigelow, N. P.

2001-05-01

421

Molecular Recoiling in Polymer Thin Film Dewetting  

NASA Astrophysics Data System (ADS)

The molecular recoiling force stemming from nonequilibrium chain conformation was found to play a very important role in the dewetting stability of polymer thin films. Correct measurements and inclusion of this molecular force into thermodynamic consideration are crucial for analyzing dewetting phenomena and nanoscale polymer chain physics. This force was measured using a simple method based on contour relaxation at the incipient dewetting holes. The recoiling stress was found to increase dramatically with molecular weight and decreasing film thickness. The corresponding forces were calculated to be in the range from 9.0 to 28.2mN/m, too large to be neglected when compared to the dispersive forces (10mN/m) commonly operative in thin polymer films.

Yang, M. H.; Hou, S. Y.; Chang, Y. L.; Yang, A. C.-M.

2006-02-01

422

1-15 MeV proton and alpha particle radiation effects on GaAs quantum well light emitting diodes [and QWIPs  

Microsoft Academic Search

Permanent radiation damage was investigated in GaAs quantum well light emitting diodes (QW LEDs) due to protons and alpha particles in the 1-15 MeV energy range. At room temperature, these devices under forward bias emit infrared radiation at 980 mm. Current-voltage (I-V) and light emission characteristics of these devices were studied as a function of fluence and energy of protons

S. M. Khanna; D. Estan; H. C. Liu; M. Gao; M. Buchanan; A. J. SpringThorpe

2000-01-01

423

West Nile Virus Genome with Glycosylated Envelope Protein and Deletion of Alpha Helices 1, 2, and 4 in the Capsid Protein Is Noninfectious and Efficiently Secretes Subviral Particles  

PubMed Central

Flavivirus genomes with deletions in the capsid (C) gene are attractive vaccine candidates, as they secrete highly immunogenic subviral particles (SVPs) without generating infectious virus. Here, we report that cytomegalovirus promoter-driven cDNA of West Nile virus Kunjin (KUNV) containing a glycosylation motif in the envelope (E) gene and a combined deletion of alpha helices 1, 2, and 4 in C produces significantly more SVPs than KUNV cDNAs with nonglycosylated E and various other deletions in C.

Roby, Justin A.; Hall, Roy A.

2013-01-01

424

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

NASA Astrophysics Data System (ADS)

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

Darrow, D. S.; Cecil, F. E.; Kiptily, V.; Fullard, K.; Horton, A.; Murari, A.; Jet Efda Contributors

2010-10-01

425

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

PubMed

The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of ? 2?MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential. PMID:21058457

Darrow, D S; Cecil, F E; Kiptily, V; Fullard, K; Horton, A; Murari, A

2010-10-01

426

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

SciTech Connect

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

Darrow, D. S. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Cecil, F. E. [Physics Department, Colorado School of Mines, Golden, Colorado 80401 (United States); Kiptily, V.; Fullard, K.; Horton, A. [Culham Centre for Fusion Energy, Euratom/CCFE Fusion Assoc., Abingdon, Oxon OX14 3DB (United Kingdom); Murari, A. [Consorzio RFX-Associazione EURATOM ENEA per la Fusione, I-35127 Padova (Italy); Collaboration: JET EFDA Contributors

2010-10-15