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1

Alpha Particle  

NASA Astrophysics Data System (ADS)

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

Murdin, P.

2000-11-01

2

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

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

3

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

4

Energy transfer from fusion alpha particles to externally driven high frequency waves in a tokamak  

NASA Astrophysics Data System (ADS)

The possibility of energy transfer from fusion alpha particles to externally driven wave fields for the purpose of driving current in a tokamak reactor was originally suggested by Fisch and Rax (Phys. Rev. Lett. 69 (1992) 612). The idea is reconsidered here for a class of alpha particle distribution functions that is nearly isotropic, except for the presence of diamagnetic flow due to radial inhomogeneity. The transfer of energy from alpha particles to high frequency waves (far above the ion gyrofrequency) requires that the driving term, which is proportional to the radial gradient of the alpha particle distribution function, be large enough to dominate the usual Landau damping. For a classic slowing down distribution, Landau damping dominates and the alpha particles absorb energy from the waves. Alternatively, if the alpha particle distribution is peaked near the birth speed, then the radial gradient driving term tends to dominate and energy can be extracted by the waves. Radial diffusion is a natural mechanism which displaces alpha particles outward before they can slow down (locally). However, a solution of a model Fokker-Planck equation, including radial diffusion and collisional slowing down, shows that the alpha particle distribution function still tends to absorb energy from the waves. Within the context of linear theory, high frequency waves may not be optimal as a means of extracting energy from alpha particles

Kupfer, K.; Chiu, S. C.; Chan, V. S.

1995-02-01

5

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

6

Solar flare alpha particles  

NASA Technical Reports Server (NTRS)

Interplanetary disturbances frequently change the instantaneous values of the low energy solar flare alpha-to-proton flux ratios. The fluxes of alpha particles were integrated over the duration of seven large solar events occurring between May 28, 1967, and November 6, 1969, in order to investigate the total alpha particles fluxes observed at 1 AU resulting from the flares. The spectra of the event integrated alphas are always softer than the spectra of the event integrated protons. As a consequence, the event-integrated alpha-to-proton ratios decrease slightly with increasing energy per nucleon. The He-4/H-1 ratios averaged over the seven events are found to vary as 0.026 (E/nucl) sup -0.2 in the range 1 to 10 MeV/nucleon. The value of the ratio at 1 MeV/nucleon is less than the helium-to-hydrogen abundance determined from spectroscopic studies of prominences and the chromosphere, and is less than the average solar wind helium-to-hydrogen abundance.

Lanzerotti, L. J.

1973-01-01

7

Imaging alpha particle detector  

DOEpatents

A method and apparatus for detecting and imaging alpha particles sources is described. A dielectric coated high voltage electrode and a tungsten wire grid constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source to be quantitatively or qualitatively analyzed. A thin polyester film window allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

Anderson, D.F.

1980-10-29

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

RANGE-ENERGY RELATIONS FOR PROTONS AND ALPHA-PARTICLES IN VARIOUS EXPLOSIVES  

Microsoft Academic Search

Differential energy loss and range data were calculated for low and ; medium-energy protons and alpha particles in various explosives. The ; explosives include cyclonite; cyclotetramethylene tetranitramine; 2,4,6-; trinitrotoluene; pentaerythritol tetranitrate; 2,4,6-trinitrophenyl methyl ; nitramine; lead styphnate; mercury fulminate; and lead azide. (C.H.);

JOSEPH CERNY; MAURICE S. KIRSHENBAUM; ROGER C. NICHOLS

1963-01-01

10

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

11

1. INTRODUCTION High-energy fusion-product (fp) transport (e.g., alpha particle  

E-print Network

-T plasmas) is a central issue in fusion reactor de- velopment. Important effects dependent on fp transport by energetic, charged fusion products is a crucial issue for obtaining fusion reactor conditions. The evolution1 1. INTRODUCTION High-energy fusion-product (fp) transport (e.g., alpha particle transport in D

Hively, Lee M.

12

Characterization of Solidified Gas Thin Film Targets via Alpha Particle Energy Loss  

E-print Network

A method is reported for measuring the thickness and uniformity of thin films of solidified gas targets. The energy of alpha particles traversing the film is measured and the energy loss is converted to thickness using the stopping power. The uniformity is determined by measuring the thickness at different positions with an array of sources. Monte Carlo simulations have been performed to study the film deposition mechanism. Thickness calibrations for a TRIUMF solid hydrogen target system are presented.

MUH collaboration; M. C. Fujiwara; G. A. Beer; J. L. Beveridge; J. L. Douglas; T. M. Huber; R. Jacot-Guillarmod; S. K. Kim; P. E. Knowles; A. R. Kunselman; M. Maier; G. M. Marshall; G. R. Mason; F. Mulhauser; A. Olin; C. Petitjean; T. A. Porcelli; J. Zmeskal

1996-10-06

13

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

SciTech Connect

We have simulated the alpha thermalization process using a Monte-Carlo technique, in which the alpha guiding center is followed between simulated collisions and Spitzer's collision model is used for the alpha-plasma interaction. Monte-Carlo techniques are used to determine the alpha radial birth position, the alpha particle position at a collision, and the angle scatter and dispersion at a collision. The plasma is modeled as a hot reacting core, surrounded by a cold halo plasma (T approx.50 eV). Alpha orbits that intersect the halo lose 90% of their energy to the halo electrons because of the halo drag, which is ten times greater than the drag in the core. The uneven drag across the alpha orbit also produces an outward, radial, guiding center drift. This drag drift is dependent on the plasma density and temperature radial profiles. We have modeled these profiles and have specifically studied a single-scale-length model, in which the density scale length (r/sub pD/) equals the temperature scale length (r/sub pT/), and a two-scale-length model, in which r/sub pD//r/sub pT/ = 1.1.

Kerns, J.A.

1986-05-01

14

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

SciTech Connect

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

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

2010-02-15

15

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

SciTech Connect

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

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

2009-07-15

16

Alpha particle confinement in tandem mirrors  

SciTech Connect

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

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

1980-10-10

17

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

18

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

19

Nuclear Alpha-Particle Condensates  

E-print Network

The $\\alpha$-particle condensate in nuclei is a novel state described by a product state of $\\alpha$'s, all with their c.o.m. in the lowest 0S orbit. We demonstrate that a typical $\\alpha$-particle condensate is the Hoyle state ($E_{x}=7.65$ MeV, $0^+_2$ state in $^{12}$C), which plays a crucial role for the synthesis of $^{12}$C in the universe. The influence of antisymmentrization in the Hoyle state on the bosonic character of the $\\alpha$ particle is discussed in detail. It is shown to be weak. The bosonic aspects in the Hoyle state, therefore, are predominant. It is conjectured that $\\alpha$-particle condensate states also exist in heavier $n\\alpha$ nuclei, like $^{16}$O, $^{20}$Ne, etc. For instance the $0^+_6$ state of $^{16}$O at $E_{x}=15.1$ MeV is identified from a theoretical analysis as being a strong candidate of a $4\\alpha$ condensate. The calculated small width (34 keV) of $0^+_6$, consistent with data, lends credit to the existence of heavier Hoyle-analogue states. In non-self-conjugated nuclei such as $^{11}$B and $^{13}$C, we discuss candidates for the product states of clusters, composed of $\\alpha$'s, triton's, and neutrons etc. The relationship of $\\alpha$-particle condensation in finite nuclei to quartetting in symmetric nuclear matter is investigated with the help of an in-medium modified four-nucleon equation. A nonlinear order parameter equation for quartet condensation is derived and solved for $\\alpha$ particle condensation in infinite nuclear matter. The strong qualitative difference with the pairing case is pointed out.

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

2011-03-21

20

Alpha particle confinement in tokamaks  

SciTech Connect

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

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

1988-11-01

21

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

22

Radioluminescence yield of alpha particles in air  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

23

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

24

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

SciTech Connect

This paper reports on a search for flare emission via charge-exchange radiation in the wings of the Ly{alpha} line of He II at 304 A, as originally suggested for hydrogen by Orrall and Zirker. Via this mechanism a primary {alpha} particle that penetrates into the neutral chromosphere can pick up an atomic electron and emit in the He II bound-bound spectrum before it stops. The Extreme-ultraviolet Variability Experiment on board the Solar Dynamics Observatory gives us our first chance to search for this effect systematically. The Orrall-Zirker mechanism has great importance for flare physics because of the essential roles that particle acceleration plays; this mechanism is one of the few proposed that would allow remote sensing of primary accelerated particles below a few MeV nucleon{sup -1}. We study 10 events in total, including the {gamma}-ray events SOL2010-06-12 (M2.0) and SOL2011-02-24 (M3.5) (the latter a limb flare), seven X-class flares, and one prominent M-class event that produced solar energetic particles. The absence of charge-exchange line wings may point to a need for more complete theoretical work. Some of the events do have broadband signatures, which could correspond to continua from other origins, but these do not have the spectral signatures expected from the Orrall-Zirker mechanism.

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

2012-06-20

25

Charge-exchange limits on low-energy alpha-particle fluxes in solar flares  

E-print Network

This paper reports on a search for flare emission via charge-exchange radiation in the wings of the Lyman-alpha line of He ii at 304 A, as originally suggested for hydrogen by Orrall and Zirker. Via this mechanism a primary alpha particle that penetrates into the neutral chromosphere can pick up an atomic electron and emit in the He ii bound-bound spectrum before it stops. The Extreme-ultraviolet Variability Experiment (EVE) on board the Solar Dynamics Observatory (SDO) gives us our first chance to search for this effect systematically. The Orrall-Zirker mechanism has great importance for flare physics because of the essential roles that particle acceleration plays; this mechanism is one of the few proposed that would allow remote sensing of primary accelerated particles below a few MeV/nucleon. We study ten events in total, including the gamma-ray events SOL2010-06-12 (M2.0) and SOL2011-02-24 (M3.5) (the latter a limb flare), seven X-class flares, and one prominent M-class event that produced solar energetic...

Hudson, Hugh; MacKinnon, Alec; Woods, Tom

2014-01-01

26

Corrections to the participant-spectator model of high-energy alpha-particle fragmentation  

NASA Astrophysics Data System (ADS)

The participant-spectator model of nuclear fragmentation is described in terms of pole graphs from direct reaction theory. Corrections to the model for more than one projectile fragment scattering on the target are considered using a triangle graph model. Results for alpha-particle fragmentation at 1 A GeV indicate that corrections to the participant-spectator picture are significant, as indicated by the large interference effects found between the pole and triangle graph terms in the double and single differential cross sections.

Cucinotta, Francis A.; Townsend, Lawrence W.; Wilson, John W.; Norbury, John W.

1991-05-01

27

Applied Radiation and Isotopes 59 (2003) 363366 Comparison among alpha-particle energy losses in air obtained  

E-print Network

source (main alpha energy=4.6875 MeV under vacuum, activity=662 Bq, active diameter=5 mm). In the present). The alpha energy losses have been experimentally determined for both 241 Am and 230 Th sources using alpha energy=5.4857 MeV under vacuum, activity=3.34 kBq, active diameter= 5 mm) and a planar 230 Th alpha

Yu, K.N.

28

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

29

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

30

Measurement of the OXYGEN-17(PROTON, Alpha Particle) Nitrogen -14 Cross Section at Stellar Energies (proton Energies, Resonant Reaction)  

NASA Astrophysics Data System (ADS)

The isotopic abundance ratio 16O/17O has been shown to be a good probe of mass flow and mixing in stars. This ratio is sensitive to the depth of convective mixing which occurs on the giant branch and to the amount of nonconvective mixing occurring on the main sequence. The interpretation of recent observations of this ratio in red giants is limited by a large uncertainty in the value of the 17O(p, alpha)14N reaction rate. This reaction rate is dominated at stellar energies by a resonance at E_{rm x} = 5673 keV in the compound nucleus 18 F, whose strength was previously uncertain. We have carried out a measurement of the ^ {17}O(p,alpha)^{14 }N cross section at proton energies of 75 keV and 65 keV. Thick, high-purity rm Ta_2O _5 targets enriched to 77% ^ {17}O were used in conjunction with beam currents of 0.45 mA and large-solid-angle detectors. The background for the experiment was measured using targets of natural isotopic composition. The resonance peak was observed in the data collected at 75 keV, and we determined the proton width of the 5673 keV state to be 22 +/- 4 neV. This implies a rate for the 17O(p,alpha)^ {14}N reaction that is ten times greater than the typical rates used previously in stellar models.

Blackmon, Jeffery Curtis

31

Determination of primary energy in nucleus-nucleus collisions and the high P(sub)T tail of alpha-particles  

NASA Astrophysics Data System (ADS)

A determination of primary energy is required in order to study the energy dependence of meson multiplicity in A-A collisions in cosmic rays. Various procedures which estimate the energy of a primary nucleus from its interaction were investigated. An average of two methods were used, one using the pions and wounded protons and the other using spectator protons and alpha particles. The high PT tail observed for Z = 2 fragments requires a modification of the latter method.

Freier, P. S.; Atwater, T. W.

1985-08-01

32

Decay Times, Fluorescent Efficiencies, and Energy Storage Properties for Various Substances with Gamma-Ray or Alpha-Particle Excitation  

Microsoft Academic Search

The results of measurements of the decay time of light flashes induced by gamma-ray quanta, or alpha-particles by means of pulse distribution curves for various crystals, powders, and solutions are presented. The decay of organic substances can be described essentially by a single exponential; in addition, a small more slowly decaying portion is present. The decay of inorganic crystals can

Loran Bittman; Milton Furst; Hartmut Kallmann

1952-01-01

33

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

34

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

SciTech Connect

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

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

1982-11-01

35

Radioimmunotherapy with alpha-particle emitting radionuclides.  

PubMed

An important consideration in the development of effective strategies for radioimmunotherapy is the nature of the radiation emitted by the radionuclide. Radionuclides decaying by the emission of alpha-particles offer the possibility of matching the cell specific reactivity of monoclonal antibodies with radiation with a range of only a few cell diameters. Furthermore, alpha-particles have important biological advantages compared with external beam radiation and beta-particles including a higher biological effectiveness, which is nearly independent of oxygen concentration, dose rate and cell cycle position. In this review, the clinical settings most likely to benefit from alpha-particle radioimmunotherapy will be discussed. The current status of preclinical and clinical research with antibodies labeled with 3 promising alpha-particle emitting radionuclides - (213)Bi, (225)Ac, and (211)At - also will be summarized. PMID:15640792

Zalutsky, M R; Pozzi, O R

2004-12-01

36

A High-Throughput Screen for Alpha Particle Radiation Protectants  

PubMed Central

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

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

2010-01-01

37

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

38

Alpha particle backscattering measurements used for chemical analysis of surfaces  

NASA Technical Reports Server (NTRS)

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

Patterson, J. H.

1967-01-01

39

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

ERIC Educational Resources Information Center

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

Andrews, D. G. H.

2008-01-01

40

Alpha-particle sensitive test SRAMs  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

41

Deconvolution of Alpha Spectra From Hot Particles  

Microsoft Academic Search

A computer code known as AASIFIT is developed to unfold complex alpha spectra. Peak shapes used in the fitting are obtained\\u000a from the simulations. In addition to activities of the nuclides present in the sample, the code can provide source characterization.\\u000a AASIFIT is applied for a nuclear bomb particle collected in Thule, Greenland. It is shown that direct alpha spectrometry

Roy Pöllänen; Tero Karhunen; Teemu Siiskonen; Harri Toivonen; Andreas Pelikan

42

Lunar surface outgassing and alpha particle measurements  

SciTech Connect

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

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

2002-01-01

43

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

SciTech Connect

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

Faria, P. N. de; Lichtenthaeler, R.; Pires, K. C. C.; Lepine-Szily, A.; Guimaraes, V.; Mendes, D. R. Jr.; Barioni, A.; Morcelle, V.; Morais, M. C. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05314-970 Sao Paulo (Brazil); Moro, A. M. [Departamento de FAMN, Universidad de Sevilla, Apartado 1065, E-41080, Sevilla (Spain); Arazi, A. [Laboratorio Tandar, Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429), Buenos Aires (Argentina)

2010-09-15

44

Absorbed fractions for alpha particles in ellipsoidal volumes.  

PubMed

Internal dosimetry of alpha particles is gaining attention due to the increasing applications in cancer treatment and also for the assessment of environmental contamination from radionuclides. We developed a Monte Carlo simulation in GEANT4 in order to calculate the absorbed fractions for monoenergetic alpha particles in the energy interval between 0.1 and 10 MeV, uniformly distributed in ellipsoids made of soft tissue. For each volume, we simulated a spherical shape, three oblate and three prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found; and the dependence of the fit parameters on the alpha energy is discussed and fitted by parametric functions. With the proposed formulation, the absorbed fraction for alpha particles in the energy range explored can be calculated for volumes and for ellipsoidal shapes of practical interest. This method can be applied to the evaluation of absorbed fraction from alpha-emitting radionuclides. The contribution to the deposited energy coming from electron and photon emissions can be accounted for exploiting the specific formulations previously introduced. As an example of application, the dosimetry of (213)Bi and its decay chain in ellipsoids is reported. PMID:23877354

Amato, Ernesto; Italiano, Antonio; Baldari, Sergio

2013-08-21

45

Absorbed fractions for alpha particles in ellipsoidal volumes  

NASA Astrophysics Data System (ADS)

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

Amato, Ernesto; Italiano, Antonio; Baldari, Sergio

2013-08-01

46

Performance comparison of scintillators for alpha particle detectors  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

47

Targeted alpha-particle immunotherapy for acute myeloid leukemia.  

PubMed

Because alpha-particles have a shorter range and a higher linear energy transfer (LET) compared with beta-particles, targeted alpha-particle immunotherapy offers the potential for more efficient tumor cell killing while sparing surrounding normal cells. To date, clinical studies of alpha-particle immunotherapy for acute myeloid leukemia (AML) have focused on the myeloid cell surface antigen CD33 as a target using the humanized monoclonal antibody lintuzumab. An initial phase I study demonstrated the safety, feasibility, and antileukemic effects of bismuth-213 ((213)Bi)-labeled lintuzumab. In a subsequent study, (213)Bi-lintuzumab produced remissions in some patients with AML after partial cytoreduction with cytarabine, suggesting the utility of targeted alpha-particle therapy for small-volume disease. The widespread use of (213)Bi, however, is limited by its short half-life. Therefore, a second-generation construct containing actinium-225 ((225)Ac), a radiometal that generates four alpha-particle emissions, was developed. A phase I trial demonstrated that (225)Ac-lintuzumab is safe at doses of 3 ?Ci/kg or less and has antileukemic activity across all dose levels studied. Fractionated-dose (225)Ac-lintuzumab in combination with low-dose cytarabine (LDAC) is now under investigation for the management of older patients with untreated AML in a multicenter trial. Preclinical studies using (213)Bi- and astatine-211 ((211)At)-labeled anti-CD45 antibodies have shown that alpha-particle immunotherapy may be useful as part conditioning before hematopoietic cell transplantation. The use of novel pretargeting strategies may further improve target-to-normal organ dose ratios. PMID:24857092

Jurcic, Joseph G; Rosenblat, Todd L

2014-01-01

48

Alpha Particle Physics Experiments in the Tokamak Fusion Test Reactor  

SciTech Connect

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

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

1998-12-14

49

The Capture of Electrons by Swiftly Moving Alpha-Particles  

Microsoft Academic Search

Relative velocities of an alpha particle and an electron which are favorable for the capture of the electron.-A stream of electrons from a thermionic source is superposed on a beam of alpha-particles from polonium. To determine the number of captures, the alpha-particle beam is subjected to a magnetic field and the number of deflected alpha-particles counted by the scintillation method.

Bergen Davis; A. H. Barnes

1929-01-01

50

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

PubMed

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

Pöllänen, R; Siiskonen, T

2008-01-01

51

Alpha-particle sensitive test SRAMs  

SciTech Connect

This paper reports on a bench-level test 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 was demonstrated using a specially designed 2-{mu}m n-well CMOS 4k-bit test SRAM and a Po-208 5.1-MeV 0.61-LET alpha-particle source.

Buehler, M.G.; Blaes, B.R. (Jet Propulsion Lab., Pasadena, CA (USA))

1990-12-01

52

Alpha-particle Gas Pressure Gauge  

NASA Technical Reports Server (NTRS)

Described are preliminary results obtained on a novel gas pressure gauge that operates between 0.1 and 1000 mb. This gauge uses a 1- micron Ci alpha particle source to ionize the gas in a small chamber with an electric field imposed between anode and cathode electrodes that drives positive ions to the cathode where they are collected electronically. This gauge could make Martian pressure measurements.

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

1995-01-01

53

A single-particle/single-cell microbeam based on an isotopic alpha source  

E-print Network

for the ions will be a 6.5 mCi radioactive alpha-particle emitter, plated on the tip of a wire. Alpha particles- tions indicate we will obtain a 6.5 mCi (2.4 · 108 dps) source with 40 keV energy spread [2]. Assuming

54

Technical NoteFEASIBILITY STUDIES OF ALPHA-PARTICLE CHANNELING IN MIRROR MACHINES  

E-print Network

Technical NoteFEASIBILITY STUDIES OF ALPHA-PARTICLE CHANNELING IN MIRROR MACHINES A. I. ZHMOGINOV such as mirror machines can benefit this concept by efficiently redirecting a-particle energy to fuel ion heating designs and for proof-of-principle experiments. KEYWORDS: alpha channeling, mirror machines, ray tracing

55

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

SciTech Connect

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, H.W.

1997-09-01

56

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

PubMed Central

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

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

2013-01-01

57

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

58

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

59

Collective transport of alpha particles due to Alfven wave instability  

SciTech Connect

Recently a new point of view has developed for describing saturation of discrete modes excited by weak sources. The method applies to the evolution of energetic particles in the beam plasma instability as well as to the description of how [alpha] particles evolve when they destabilize Alfven waves under reactor conditions. Over a wide range of parameters the system produces pulsations, where there are relativelybrief bursts of wave energy separated by longer intervals of quiescence. There are two types of pulsations; benign and explosive. In the benign phase, valid when particle motion is not stochastic, the distribution function is close to that predicted by classical transport theory, and the instability saturates when the wave trapping frequency equals the expected linear growth rate. If the field amplitude in a burst reaches the level where orbit stochasticity occurs, the quasilinear diffusion causes rapid transfer of particle energy to wave energy and rapid flattening of the particle distribution function. The bursting phaseis followed by a relatively long quiescent time interval where the source provides the necessary free energy to regenerate the cycle. The critical issue is whether the instability develops to a high enough level to produce stochastic diffusion. In general this question can be assessed by using mapping methods to obtain criteria of overlapping of orbit resonance.

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

1993-02-01

60

Collective transport of alpha particles due to Alfven wave instability  

SciTech Connect

Recently a new point of view has developed for describing saturation of discrete modes excited by weak sources. The method applies to the evolution of energetic particles in the beam plasma instability as well as to the description of how {alpha} particles evolve when they destabilize Alfven waves under reactor conditions. Over a wide range of parameters the system produces pulsations, where there are relativelybrief bursts of wave energy separated by longer intervals of quiescence. There are two types of pulsations; benign and explosive. In the benign phase, valid when particle motion is not stochastic, the distribution function is close to that predicted by classical transport theory, and the instability saturates when the wave trapping frequency equals the expected linear growth rate. If the field amplitude in a burst reaches the level where orbit stochasticity occurs, the quasilinear diffusion causes rapid transfer of particle energy to wave energy and rapid flattening of the particle distribution function. The bursting phaseis followed by a relatively long quiescent time interval where the source provides the necessary free energy to regenerate the cycle. The critical issue is whether the instability develops to a high enough level to produce stochastic diffusion. In general this question can be assessed by using mapping methods to obtain criteria of overlapping of orbit resonance.

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

1993-02-01

61

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

62

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; Pommé, S; Paepen, J; Van Ammel, R; Jobbágy, V; Dirican, A; Suliman, G; Stroh, H; Apostolidis, C; Abbas, K; Morgenstern, A

2012-09-01

63

High-energy resolution alpha spectrometry using cryogenic detectors.  

PubMed

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

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

2006-01-01

64

Complex-Energy Shell-Model Description of Alpha Decay  

SciTech Connect

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

Id Betan, R. [Rosario Physics Institute, Rosario, Argentina] [Rosario Physics Institute, Rosario, Argentina; Nazarewicz, Witold [ORNL] [ORNL

2011-01-01

65

The {alpha} particle as a canonically quantized multiskyrmion  

SciTech Connect

The rational map approximation to the solution to the SU(2) Skyrme model with baryon number B=4 is canonically quantized. The quantization procedure leads to anomalous breaking of the chiral symmetry, and exponential fall-off of the energy density of the soliton at large distances. The model is extended to SU(2) representations of arbitrary dimension. These soliton solutions capture the double node feature of the empirical {alpha} particle charge form factor, but as expected lead to a too compact matter distribution. Comparison to phenomenology indicates a preference for the fundamental representation.

Acus, A.; Norvaisas, E.; Riska, D. O. [VU Institute of Theoretical Physics and Astronomy, Gostauto 12, Vilnius 01108 and Department of Physics and Technology, Vilnius Pedagogical University (Lithuania); Helsinki Institute of Physics, POB 64, 00014 University of Helsinki (Finland)

2006-08-15

66

Measurements of geomagnetically trapped alpha particles, 1968-1970. I - Quiet time distributions  

NASA Technical Reports Server (NTRS)

Results of observations of geomagnetically trapped alpha particles over the energy range from 1.18 to 8 MeV performed with the aid of the Injun 5 polar-orbiting satellite during the period from September 1968 to May 1970. Following a presentation of a time history covering this entire period, a detailed analysis is made of the magnetically quiet period from Feb. 11 to 28, 1970. During this period the alpha particle fluxes and the intensity ratio of alpha particles to protons attained their lowest values in approximately 20 months; the alpha particle intensity versus L profile was most similar to the proton profile at the same energy per nucleon interval; the intensity ratio was nearly constant as a function of L in the same energy per nucleon representation, but rose sharply with L when computed in the same total energy interval; the variation of alpha particle intensity with B suggested a steep angular distribution at small equatorial pitch angles, while the intensity ratio showed little dependence on B; and the alpha particle spectral parameter showed a markedly different dependence on L from the equivalent one for protons.

Krimigis, S. M.; Verzariu, P.

1973-01-01

67

Microdosimetry of radon progeny alpha particles in bronchial airway bifurcations.  

PubMed

A Monte Carlo code, initially developed for the calculation of microdosimetric spectra for alpha particles in cylindrical airways, has been extended to allow the computation of microdosimetric parameters for multiple source-target configurations in bronchial airway bifurcations. The objective of the present study was to investigate the effects of uniform and non-uniform radon progeny surface activity distributions in symmetric and asymmetric bronchial airway bifurcations on absorbed dose, hit frequency, lineal energy, single hit specific energy and LET spectra. In order to assess the effects of multiple hits, dose-dependent specific energy spectra were calculated by solving the compound Poisson process by iterative convolution. While the simulations showed significant differences of cellular dose quantities at different cell locations for uniformly distributed surface activities, even higher variations, as high as several orders of magnitude, were observed for non-uniform surface activity distributions, depending on the location of the cell and the local activity distribution. PMID:15972358

Fakir, H; Hofmann, W; Aubineau-Lanièce, I

2005-01-01

68

Characterization of radioactive particles using non-destructive alpha spectrometry  

Microsoft Academic Search

Spherical particles with known properties were used to demonstrate and test a novel software package known as AASIFIT, which is able to unfold complex alpha spectra. A unique feature of the program is that it uses simulated peak shapes in the fitting process. The experimental reference particles in the testing were artificially produced U particles of diameter 1.4?m and a

Y. Ranebo; R. Pöllänen; M. Eriksson; T. Siiskonen; N. Niagolova

2010-01-01

69

{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

70

Depth Measurements Using Alpha Particles and Upsettable SRAMs  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

71

Alpha particle induced inner-shell ionization measurements for the undergraduate laboratory  

SciTech Connect

The interaction of alpha particles with low atomic number elements has been studied in an attempt to determine the inner-shell ionization cross section. These cross sections were determined by measuring the characteristic x-rays that were produced when a thin aluminum target was bombarded by alpha particles from a 48 MBq {sup 244}Cm alpha source. The x-rays were detected with a Si(Li) x-ray detector whose resolution was 190 eV at 5.9 keV. The efficiency of the detector was determined from standard radioactive sources. The energies of the alpha particles were varied by placing thin Mylar absorbers between the alpha source and the target. The results are favorably compared to a current ionization theory given in such a form that an undergraduate physics major can do the calculations. This experiment is intended as an undergraduate laboratory experiment in the atomic or nuclear area.

Sun, H.L.; Duggan, J.L. [Univ. of North Texas, Denton, TX (United States); Desmarais, D. [Univ. of Alberta (Canada)

1992-12-01

72

Alpha-particle-induced, inner-shell ionization measurements for the undergraduate laboratory  

SciTech Connect

The interaction of ..cap alpha.. particles with low atomic number elements has been studied in an attempt to determine the inner-shell ionization cross section. These cross sections were determined by measuring the characteristic x rays that were produced when a thin aluminum target was bombarded by ..cap alpha.. particles from a 48-MBq /sup 224/Cm ..cap alpha.. source. The x rays were detected with a Si(Li) x-ray detector whose resolution was 190 eV at 5.9 keV. The efficiency of the detector was determined from standard radioactive sources. The energies of the ..cap alpha.. particles were varied by placing thin Mylar absorbers between the ..cap alpha.. source and the target. The results are favorably compared to a current ionization theory given in such a form that an undergraduate physics major can do the calculations. This experiment is intended as an undergraduate laboratory experiment in the atomic or nuclear area.

Desmarais, D.; Duggan, J.L.

1984-06-01

73

PC based analysis of alpha-particle spectra  

Microsoft Academic Search

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 (8) alpha-particle detectors. The PC is a IBM PC-AT computer with a 20 Mbyte Bernoulli Box removable cartridge disk, a math co-processor, and a printer. Once saved on disk, the

T CHAPMAN

1990-01-01

74

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

75

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

76

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

77

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. Lüke; 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 Rüden; 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. Prulhière; G. Stimpfl; J. D. Hansen; J. R. Hansen; P. H. Hansen; R. Møllerud; 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. Rougé; 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. Lütjens; G. Lutz; W. Männer; H.-G. Moser; Y. B. Pan; R. Richter; J. Schröder; 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. Journé; D. W. Kim; J. Lefrançois; 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. Foà; 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. Lançon; 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. Schäfer; 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

78

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

79

Energetic alpha particle deposition in a magnetized plasma  

Microsoft Academic Search

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

D. P. Smitherman; R. C. Kirkpatrick

1991-01-01

80

Particle Physics Aspects of Antihydrogen Studies with ALPHA at CERN  

E-print Network

discuss aspects of antihydrogen studies, that relate to particle physics ideas and techniques, within probing physics at the Planck Scale. We discuss some of the particle detection techniques used in ALPHA technical developments are required in order to produce, detect, trap, cool and interrogate anti- atoms

Fajans, Joel

81

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

Microsoft Academic Search

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

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

1988-01-01

82

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

83

Discrimination of nuclear recoils from alpha particles with superheated liquids  

NASA Astrophysics Data System (ADS)

The PICASSO collaboration observed for the first time a significant difference between the acoustic signals induced by neutrons and alpha particles in a detector based on superheated liquids. This new discovery offers the possibility of improved background suppression and could be especially useful for dark matter experiments. This new effect may be attributed to the formation of multiple bubbles on alpha tracks, compared to single nucleations created by neutron-induced recoils.

Aubin, F.; Auger, M.; Genest, M.-H.; Giroux, G.; Gornea, R.; Faust, R.; Leroy, C.; Lessard, L.; Martin, J.-P.; Morlat, T.; Piro, M.-C.; Starinski, N.; Zacek, V.; Beltran, B.; Krauss, C. B.; Behnke, E.; Levine, I.; Shepherd, T.; Nadeau, P.; Wichoski, U.; Pospisil, S.; Stekl, I.; Sodomka, J.; Clark, K.; Dai, X.; Davour, A.; Levy, C.; Noble, A. J.; Storey, C.

2008-10-01

84

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

85

2948 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 39, NO. 11, NOVEMBER 2011 Simulation of Alpha Particles in Rotating Plasma  

E-print Network

connecting the hot core of the plasma to the cold edge. That is, there is coupled diffusion in energy particle kinetic energy, in an extension of the alpha channeling concept. The interaction of alpha advantages as fusion reactors including high beta, steady-state op- eration, and a simple coil configuration

86

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

87

TF ripple loss of alpha particles in TFTR DT experiments  

SciTech Connect

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

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

1995-08-01

88

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

89

Making A D-Latch Sensitive To Alpha Particles  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

90

Fetal dosimetry from natural alpha-particle emitters.  

PubMed

The alpha-particle dose to human fetal bone marrow from natural exposure was investigated. The rate of calcification and the (210)Pb activity levels in fetal vertebrae showed that (210)Pb follows the uptake of calcium into the skeleton. Lead-210-supported (210)Po activity concentrations of up to 0.18 Bq kg(-1) were found in fetal lumbar vertebra. The mean chord length of the trabecular spaces in lumbar vertebra were 110-320 micrometer at 20- 40 weeks, in rib 130-180 micrometer at 20-35 weeks, and in sternum 190 micrometer at 35 weeks of gestation. In lumbar vertebra, up to 80% of marrow was within alpha-particle range (37 micrometer) of a bone surface. This resulted in a gestational equivalent dose to marrow from (210)Pb-supported (210)Po in bone of 8 and 24 micrometerSv when the contribution from all major natural alpha-particle-emitting radionuclides was considered. The mean distance of CD34(+) cells from the nearest bone surfaces in lumbar vertebra was 61 and 46 micrometer at mid- and late gestation, respectively. The mean cellular and nuclear diameters of CD34(+) cells were 5.5 and 3.8 micrometer respectively, and remained constant with gestational age. Few stem cells were hit by alpha particles at natural exposure; however, those that were hit received doses of up to 1.3 Gy. PMID:10564954

Purnell, S J; Allen, J E; Oyedepo, A C; Henshaw, D L

1999-12-01

91

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

E-print Network

of the alpha distribution function made with a sensitive active neutral particle diagnostic. The calculations products inferred from triton burnup experiments at Japan Atomic Energy Research Institute Tokamak-60

Redi, Martha H.

92

IV. ALPHA-PARTICLE PHYSICS IN BPX D. J. SIGMAR (MIT)  

E-print Network

IV. ALPHA-PARTICLE PHYSICS IN BPX D. J. SIGMAR (MIT) 1V.A. INTRODUCTION A central part Reactor (ETR). The list of currently conceptualized alpha- particle physics issues starts with the global. Quantitative measurements of 7"" due to al- pha particles require Q 2 2. 1113 #12;Sigmar ALPHA-PARTICLE PHYSICS

93

Michrochannel plate for position sensitive alpha particle detection  

SciTech Connect

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

Paul Hurley and James Tinsley

2007-08-31

94

Alpha Decay in the Complex-Energy Shell Model  

SciTech Connect

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

Betan, R. Id [UTK/ORNL/Instituto de Fisica Rosario (CONICET), Argentina; Nazarewicz, Witold [UTK/ORNL/University of Warsaw

2012-01-01

95

ICRF (Ion Cyclotron Range of Frequency) Enhancement of Fusion Reactivity in the Presence of alpha Particles.  

National Technical Information Service (NTIS)

Absorption of ICRF (ion cyclotron range of frequency) waves by alpha particles and fusion reactivity enhancement due to the ICRF induced ion tail are investigated. The rate of linear absorption by alpha particles increases with the cyclotron harmonic numb...

M. Yamagiwa, T. Takizuka

1988-01-01

96

SOLAR PROTONS, ALPHA PARTICLES, AND HEAVY NUCLEI IN NOVEMBER 1960  

Microsoft Academic Search

Energy spectra of solar protons and a particles were measured in the event fol- lowing the November 12, 1960, flare. The ratio of the abundance of protons to the abundance of a particles above the same rigidity was found to be 2. Spectra of protons, a particles, and medium nuclei were measured after the November 15, 1960, flare. The proton

E. P. Ney; W. A. Stein

1962-01-01

97

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

98

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

PubMed

Targeted alpha-particle emitters hold great promise as therapeutics for micrometastatic disease. Because of their high energy deposition and short range, tumor targeted alpha-particles can result in high cancer-cell killing with minimal normal-tissue irradiation. Actinium-225 is a potential generator for alpha-particle therapy: it decays with a 10-day half-life and generates three alpha-particle-emitting daughters. Retention of (225)Ac daughters at the target increases efficacy; escape and distribution throughout the body increases toxicity. During circulation, molecular carriers conjugated to (225)Ac cannot retain any of the daughters. We previously proposed liposomal encapsulation of (225)Ac to retain the daughters, whose retention was shown to be liposome-size dependent. However, daughter retention was lower than expected: 22% of theoretical maximum decreasing to 14%, partially due to the binding of (225)Ac to the phospholipid membrane. In this study, Multivesicular liposomes (MUVELs) composed of different phospholipids were developed to increase daughter retention. MUVELs are large liposomes with entrapped smaller lipid-vesicles containing (225)Ac. PEGylated MUVELs stably retained over time 98% of encapsulated (225)Ac. Retention of (213)Bi, the last daughter, was 31% of the theoretical maximum retention of (213)Bi for the liposome sizes studied. MUVELs were conjugated to an anti-HER2/neu antibody (immunolabeled MUVELs) and were evaluated in vitro with SKOV3-NMP2 ovarian cancer cells, exhibiting significant cellular internalization (83%). This work demonstrates that immunolabeled MUVELs might be able to deliver higher fractions of generated alpha-particles per targeted (225)Ac compared to the relative fractions of alpha-particles delivered by (225)Ac-labeled molecular carriers. PMID:17935286

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

2007-01-01

99

Destabilization of low mode number Alfven modes in a tokamak by energetic or alpha particles  

SciTech Connect

With the inclusion of finite Larmor radius effects in the shear Alfven eigenmode equation, the continuous Alfven spectrum, which has been extensively discussed in ideal magnetohydrodynamics, is removed. Neutrally stable, discrete radial eigenmodes appear in the absence of sources of free energy and dissipation. Alpha (or energetic) particle toroidal drifts destabilize these modes, provided the particles are faster than the Alfven speed. Although the electron Landu resonance contributes to damping, a stability study of the parametric variation of the energy and the density scale length of the energetic particles shows that modes with low radial mode numbers remain unstable in most cases. Since the alpha particles are concentrated in the center of the plasma, this drift-type instability suggests anomalous helium ash diffusion. Indeed, it is shown that stochasticity of alpha orbits due to the overlapping of radially neighboring Alfven resonances is induced at low amplitudes, e/sub i//sup approx./phi/T/sub i/ greater than or equal to 0.05, implying a diffusion coefficient D/sub r//sup ..cap alpha../ greater than or equal to 4.4 x 10/sup 3/cm/sup 2//s.

Tsang, K. T.; Sigmar, D. J.; Whitson, J. C.

1980-12-01

100

Characteristics of sunward flowing proton and alpha particle fluxes of moderate intensity  

NASA Technical Reports Server (NTRS)

The diffusive streaming of low-energy protons has been found to be predominately toward the sun during periods between prompt solar particle events. This occurs for essentially all solar wind velocities and proton intensities. The average radial component of this anisotropy (14%) and its dependence on the solar wind velocity agree with values found by a steady-state propagation model. The average radial component (16%) of the diffusive flow of low-energy alpha particles is similar to that observed for protons, suggesting a common origin. The sunward diffusion of alpha particles and protons indicates that these slightly enhanced fluxes contain a positive radial gradient. The direction of the diffusive anisotropy is a function of the magnetic field direction.

Marshall, F. E.; Stone, E. C.

1978-01-01

101

Fokker Planck kinetic modeling of suprathermal alpha-particles in a fusion plasma  

E-print Network

We present an ion kinetic model describing the ignition and burn of the deuterium-tritium fuel of inertial fusion targets. The analysis of the underlying physical model enables us to develop efficient numerical methods to simulate the creation, transport and collisional relaxation of fusion reaction products (alpha-particles) at a kinetic level. A two-energy-scale approach leads to a self-consistent modeling of the coupling between suprathermal alpha-particles and the thermal bulk of the imploding plasma. This method provides an accurate numerical treatment of energy deposition and transport processes involving suprathermal particles. The numerical tools presented here are validated against known analytical results. This enables us to investigate the potential role of ion kinetic effects on the physics of ignition and thermonuclear burn in inertial confinement fusion schemes.

Peigney, Benjamin-Edouard; Tikhonchuk, Vladimir

2014-01-01

102

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

103

PARTICLE-GAMMA COINCIDENCE STUDIES OF ALPHA-INDUCED REACTIONS ON C¹² AND Ne²°  

Microsoft Academic Search

The 22-Mev alpha -particle beam of the Indiana University cyclotron was ; used to bombard targets of C¹² and Ne²°. Angularr distributions of ; elastic and inelastic particle groups were measured for both nuclei. Qualitative ; comparison of the results both with current nuclear interaction theory and with ; measurements at other bombarding energies are shown. Problems concerning the ;

Eidson

1962-01-01

104

Alpha-particle-induced, inner-shell ionization measurements for the undergraduate laboratory  

Microsoft Academic Search

The interaction of alpha particles with low atomic number elements has been studied in an attempt to determine the inner-shell ionization cross section. These cross sections were determined by measuring the characteristic x rays that were produced when a thin aluminum target was bombarded by alpha particles from a 48-MBq 224Cm alpha source. The x rays were detected with a

D. Desmarais; J. L. Duggan

1984-01-01

105

Probing Pre-Formed Alpha Particles in the Ground State of Nuclei  

NASA Astrophysics Data System (ADS)

In this proceeding we report on alpha particle emission through the nuclear break-up in the reaction 40Ca on a 40Ca target at 50A MeV. It is observed that alpha particles are emitted to the continuum with very specific angular distribution during the reaction. The alpha particle properties seem to be compatible with an alpha cluster in the daughter nucleus that is perturbed by the short range nuclear attraction of the collision partner and emitted as described by a time-dependent theory. This mechanism offers new possibilities to study alpha particle properties in the nuclear medium.

Scarpaci, J. A.; Fallot, M.; Lacroix, D.; Assié, M.; Lefebvre, L.; Frascaria, N.; Beaumel, D.; Bhar, C.; Blumenfeld, Y.; Chbihi, A.; Chomaz, Ph.; Désesquelle, P.; Frankland, J.; Idbarkach, H.; Khan, E.; Laville, J. L.; Plagnol, E.; Pollacco, E. C.; Roussel-Chomaz, P.; Roynette, J. C.; Shrivastava, A.; Zerguerras, T.

106

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

107

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

NASA Technical Reports Server (NTRS)

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

Gloeckler, G.

1975-01-01

108

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

109

Differential Flow Between Solar Wind Protons and Alpha Particles: First WIND Observations  

E-print Network

Differential Flow Between Solar Wind Protons and Alpha J Particles: First WIND Observations . T Flight Center, Greenbelt, Maryland w Abstract. Alpha particle and proton measurements in the solar ind particle and proton meas rements in the solar wind using the first results from the Solar o Wind Experiment

Richardson, John

110

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

SciTech Connect

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

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

2013-02-28

111

Channeling of Fusion Alpha-Particle Power Using Minority Ion Catalysis A. I. Zhmoginov and N. J. Fisch  

E-print Network

reactions carry almost 20% of the released fusion energy. Before this energy is lost to electrons through, with electrons kept cold, so that the effective fusion reactivity can be increased [9­11]. The meansChanneling of Fusion Alpha-Particle Power Using Minority Ion Catalysis A. I. Zhmoginov and N. J

112

Effects of anomalous alpha particle diffusion on fusion power coupling into tokamak plasma  

Microsoft Academic Search

The alpha particle power coupling efficiency to the bulk plasma, etaalpha identical to Palpha(coupled)\\/Palpha(birth), is reduced when the energetic alpha particles are subject to anomalous radial diffusion, Dalphaan, caused by alpha particle instabilities. If etaalpha is appreciably smaller than 1, this has a strong effect on the ignition margin MI [? Palpha (coupled)\\/Ploss] of a tokamak plasma. First, a simple

D. Sigmar; R. Gormley; G. Kamelander

1993-01-01

113

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

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

2012-04-01

114

Characteristics of the spectra of protons and alpha particles in recurrent events at 1 AU  

NASA Technical Reports Server (NTRS)

A study of 31 individual recurrent events from three long-lived corotating particle streams is presented. The spectra of protons and alpha particles during these streams are fit well by an exponential in particle rigidity. Although the spectra show considerable temporal variation, the proton and alpha particle spectra are correlated so that the e-folding rigidities Po(alpha) and Po(p) of the two spectra are in the ratio Po(alpha)/Po(p) = 1.5 plus or minus 0.1. The consistency of this ratio may be a characteristic of the interplanetary acceleration process.

Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

1979-01-01

115

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

E-print Network

Induction of a bystander mutagenic effect of alpha particles in mammalian cells Hongning Zhou, including chromosomal damage, gene mutations, induction of micronuclei, and sister chromatid exchanges (SCE

116

Damage of EUV optical coatings induced by alpha-particles bombardment  

NASA Astrophysics Data System (ADS)

Future solar missions will investigate the Sun from very close distances and optical components are constantly exposed to low energy ions irradiation. Single layer thin films as well as extreme ultraviolet multilayer coatings have been exposed to low energy alpha particles (4keV). In order to change the total dose accumulated, for each ion fluency the time of exposure was varied. The experiment was carried out considering typical doses accumulated during the ESA Solar Orbiter mission. Results show that ion implantation affects the performances of both single and multilayer coatings.

Pelizzo, M. G.; Zuccon, S.; Napolitani, E.; Corso, A. J.; Zuppella, P.; Tessarolo, E.; Nardello, M.; Gerlin, F.; Naletto, G.; Fineschi, S.; Antonucci, E.

2014-09-01

117

Comments on ICRU report no. 49: stopping powers and ranges for protons and alpha particles.  

PubMed

The International Commission on Radiation Units and Measurements (ICRU) published Report No. 49, Stopping Powers and Ranges for Protons and Alpha Particles, in 1993. Since the report shows only limited comparisons to experimental data, this Commentary discusses limits on the accuracy of its tables. Some of the stopping tabulations appear to have unusual variations for high energies (>1 MeV/nucleon) of the order of 2-4%, while the lower energies have possible errors of 10-20% for those targets which were not fitted with new data. PMID:10409333

Ziegler, J F

1999-08-01

118

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

SciTech Connect

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

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

2005-07-15

119

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

120

Partition of cross sections in asymmetric nucleus-nucleus reactions and the origin of fast alpha particles  

SciTech Connect

To investigate the mechanism of asymmetric nucleus-nucleus reactions from the Coulomb barrier to intermediate energies the /sup 14/N + /sup 159/Tb reaction was studied at five bombarding energies between 8 and 23 MeV/u via particle-particle correlations (at selected energies) and particle KX-ray coincidences to identify the specific reaction channels. With the KX-ray method partial cross sections for projectile-like fragments (PLF) as a function of the atomic number (Z/sub res/) of the residual nucleus can be determined. The charge balance yields the ''missing charge'' dZ = Z/sub proj/ + Z/sub targ/ - Z/sub PLF/ - Z/sub TLF/ that indicates whether, in addition to the PLF, other charged particles are emitted. A large fraction of the inclusive cross sections is found to originate from such channels with two or more fragments in the exit channel, and this fraction increases as the PLF is further removed in mass from the incident projectile, and with increasing bombarding energy. From the particle-particle correlation studies it is found that sequential decays of PLF's are dominant. ''Non-sequential'' processes, if present, are associated with inelastic reactions involving excitations of both projectile and target. The bulk of the large alpha-particle cross section at small angles is found to be associated with channels in which, in addition to the alpha particle, only nucleons and other alpha particles are emitted. From ..gamma..-ray multiplicity measurements and from the broad distribution of the strength with Z/sub res/ it is concluded that these alpha particles originate from inelastic (damped) processes. 27 refs., 10 figs.

Siemssen, R.H.

1985-01-01

121

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

122

Alpha particle induced inner-shell ionization measurements for the undergraduate laboratory  

Microsoft Academic Search

The interaction of alpha particles with low atomic number elements has been studied in an attempt to determine the inner-shell ionization cross section. These cross sections were determined by measuring the characteristic x-rays that were produced when a thin aluminum target was bombarded by alpha particles from a 48 MBq ²⁴⁴Cm alpha source. The x-rays were detected with a Si(Li)

H. L. Sun; J. L. Duggan; D. Desmarais

1992-01-01

123

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

124

The Ternary Alpha Energy Distribution Revisited  

NASA Astrophysics Data System (ADS)

The shape of the energy distribution of the particles emitted in ternary fission has been studied since the discovery of the phenomenon for a large variety of fissioning systems. The general tendency of the observations is that most particles have a Gaussian-shaped energy distribution, except the ?-particles, for which mostly an important non-Gaussian tailing on the low-energy side is reported. The origin of this tailing is generally ascribed to the decay of ternary 5He particles in an ?-particle and a neutron. Since the experiments reported in the literature are rarely optimised for measuring the low-energy part of the ?-spectrum, we realised good experimental conditions for studying the 235U(nth,f) ternary ? energy distribution at the High Flux Reactor of the ILL in Grenoble. Thanks to a very intense and clean neutron beam, a small, very thin sample of highly enriched U could be used, with an activity of only 1.6 Bq. So the measurements could be done without absorber in between the sample and the ?E-E detector. With the resulting low detection limit of 6 MeV, a clearly asymmetric energy distribution was obtained, in agreement with most data in the literature.

Wagemans, Cyriel; Janssens, Peter; Heyse, Jan; Serot, Olivier; Geltenbort, Peter; Soldner, Torsten

2004-02-01

125

Photoluminescence study of gallium arsenide irradiated with 15 MeV alpha particles  

SciTech Connect

Gallium arsenide wafers were irradiated at room temperature with 15 MeV alpha particles and fluences in the range 10{sup 10} to 10{sup 14} {alpha}/cm{sup 2}. This experiment extends the previous investigation of the same samples irradiated by 2.5, 5.0, and 10 MeV to 15 MeV, at which energy nuclear transmutations occur, and were observed via {gamma} ray analysis but no definitive effects of transmutations on photoluminescence measurements were observed. The gallium vacancy introduction rate b(V{sub Ga}) and silicon at the arsenic site introduction rate b(Si{sub As}) due to 15 MeV alpha particles were measured by low temperature photoluminescence spectroscopy and found to be (2.3 {+-} 0.8) x 10{sup 3} and (1.5 {+-} 0.3) x 10{sup 3} cm{sup {minus}1} respectively. The theoretical vacancy introduction rate, as calculated by taking into account only primary interactions, is (1.07 {+-} 0.02) x 10{sup 3} cm{sup {minus}1}.

Sellami, L.; Aubin, M.; Aktik, C.; Carlone, C.; Houdayer, A.; Hinrichsen, P.

1999-12-01

126

Direct study of the alpha-nucleus optical potential at astrophysical energies using the 64Zn(p,alpha)61Cu reaction  

E-print Network

In the model calculations of heavy element nucleosynthesis processes the nuclear reaction rates are taken from statistical model calculations which utilize various nuclear input parameters. It is found that in the case of reactions involving alpha particles the calculations bear a high uncertainty owing to the largely unknown low energy alpha-nucleus optical potential. Experiments are typically restricted to higher energies and therefore no direct astrophysical consequences can be drawn. In the present work a (p,alpha) reaction is used for the first time to study the alpha-nucleus optical potential. The measured 64Zn(p,alpha)61Cu cross section is uniquely sensitive to the alpha-nucleus potential and the measurement covers the whole astrophysically relevant energy range. By the comparison to model calculations, direct evidence is provided for the incorrectness of global optical potentials used in astrophysical models.

Gyürky, Gy; Halász, Z; Kiss, G G; Szücs, T

2014-01-01

127

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

128

Alpha Particle-Driven Toroidal Alfv en Eigenmodes in Tokamak Fusion Test Reactor Deuterium-Tritium Plasmas: Theory and  

E-print Network

26, 11 1984 Deuterium- Tritium plasmas are analyzed using the NOVA-K code C. Z. Cheng, Phys. Reports be destabilized by super-Alfv enic alpha particles via parallel wave particle resonances1. Such alpha

129

Determination of alpha_s from the QCD static energy: an update  

E-print Network

We present an update of our determination of the strong coupling alpha_s from the quantum chromodynamics static energy. This updated analysis includes new lattice data, at smaller lattice spacings and reaching shorter distances, the use of better suited perturbative expressions to compare with data in a wider distance range, and a comprehensive and detailed estimate of the error sources that contribute to the uncertainty of the final result. Our updated value for alpha_s at the Z-mass scale, M_Z, is alpha_s(M_Z)=0.1166^{+0.0012}_{-0.0008}, which supersedes our previous result.

Alexei Bazavov; Nora Brambilla; Xavier Garcia i Tormo; Peter Petreczky; Joan Soto; Antonio Vairo

2014-07-31

130

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

131

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

132

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

133

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

134

On the approximations of the distribution function of fusion alpha particles  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

135

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

136

Deep UV emitting scintillators for alpha and beta particle detection  

NASA Astrophysics Data System (ADS)

Several deep UV emitting scintillators, whose emission falls in the solar blind region of the spectrum (200-280 nm), are described and their scintillator properties are characterized. They include LaPO 4:Pr, YPO 4:Pr, YAlO 3:Pr, Pr(PO 3) 3, YPO 4:Bi and ScPO 4. These materials would facilitate the detection of ionizing radiation in open areas, even during the daylight hours, and could be used to support large area surveys that monitor for the presence of ionization radiation due, for example, to system leaks or transfer contamination. These materials can be used in the form of powders, thin films or paints for radiation detection. They are characterized for both beta radiation using electron beams (2-35 keV) and 137Cs and alpha radiations using 241Am sources. Their absolute light yields are estimated and are compared to that of Y 2SiO 5:Ce. Their light yields decrease as a function of electron energy but at 10 keV they approach 8000 ph/MeV.

Zhou, Y.; Jia, D. D.; Lewis, L. A.; Feofilov, S. P.; Meltzer, R. S.

2011-03-01

137

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

PubMed

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

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

1992-05-01

138

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

E-print Network

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

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

2005-01-01

139

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

SciTech Connect

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

Wong, K.L.

1989-07-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

141

Is the first excited state of the $\\alpha$-particle a breathing mode?  

E-print Network

The isoscalar monopole excitation of 4He is studied within a few-body ab initio approach. We consider the transition density to the low-lying and narrow 0+ resonance, as well as various sum rules and the strength energy distribution itself at different momentum transfers q. Realistic nuclear forces of chiral and phenomenological nature are employed. Various indications for a collective breathing mode are found: i) the specific shape of the transition density, ii) the high degree of exhaustion of the non-energy-weighted sum rule at low q and iii) the complete dominance of the resonance peak in the excitation spectrum. For the incompressibility K of the alpha-particle values between 20 and 30 MeV are found.

Bacca, Sonia; Leidemann, Winfried; Orlandini, Giuseppina

2014-01-01

142

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

E-print Network

Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including relative drifts between particle species. Two non-collisional mechanisms have been proposed for limiting differential flow between alpha particles and protons: plasma instabilities and the rotational force. Both mechanisms decelerate the alpha particles. In this paper, we derive an analytic expression for the rate $Q_{\\mathrm{flow}}$ at which energy is released by alpha-particle deceleration, accounting for azimuthal flow and conservation of total momentum. We find that $Q_{\\mathrm{flow}} > 0 $ at $r r_{\\mathrm{crit}}$. We compare the value of $Q_{\\mathrm{flow}}$ at $rheating rates for protons and alpha particles, denoted $Q_{\\mathrm{p}}$ and $Q_{\\alpha}$, deduced from in-situ measurements of fast-wind streams from the Helios and Ulysses spacecraft. We find that $Q_{\\mathrm{flow}}$ exceeds $Q_{\\alpha}$ at $r < 1\\,\\mathrm{AU}$, $Q_{...

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

2014-01-01

143

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

144

Biological effects of alpha particle radiation exposure on human monocytic cells.  

PubMed

Radon ((222)Rn) gas produces decay progeny that emits high energy alpha (?)-particles. Epidemiological studies have shown that exposure to (222)Rn is linked with elevated risk of developing lung cancer, however clear mechanisms leading to such effects have not been delineated. Cytokines play a critical role in inflammation and their dysregulated production often contributes to disease pathogenesis. In this study, Bio-plex multiplex technology was employed to investigate modulations of 27 pro-inflammatory cytokines following exposure of human monocytic cells to 1.5 Gy of ?-particle radiation. Concurrently, DNA damage was assessed by examining the formation of phosphorylated H2A histone family X (?-H2AX) sites. Of the 27 cytokines assessed, 4 cytokines were shown to be statistically downregulated by ?2 fold relative to the untreated controls and included the interleukin (IL) family of proteins (IL-2, IL-15 and IL-17) and macrophage inflammatory protein 1 beta (MIP-1b). Interferon-inducible protein-12 (IP-12), vascular endothelial growth factor and regulated on activation normal T cell expressed and secreted (RANTES) were shown to be high expressors and upregulated. Cells irradiated with ?-particles ranging from 0.27 to 2.14 Gy showed statistically significant, dose-dependant increases in ?-H2AX formation. These data suggest that ?-particle radiation causes dysregulation in the production of a number of pro-inflammatory cytokines and results in significant DNA damage. PMID:22153871

Chauhan, Vinita; Howland, Matthew; Kutzner, Barbara; McNamee, James P; Bellier, Pascale V; Wilkins, Ruth C

2012-04-01

145

Dark energy and particle mixing  

E-print Network

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

A. Capolupo; S. Capozziello; G. Vitiello

2008-08-30

146

Coaxial charged particle energy analyzer  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

147

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

SciTech Connect

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

Day, J. P.; McEwen, J. E.; Elhanafy, M.; Smith, E.; Woodhouse, R.; Papp, Z. [Department of Physics and Astronomy, California State University Long Beach, Long Beach, California (United States)

2011-09-15

148

MHD-Induced Alpha Particle Loss in TFTR S.J. Zweben, D.S. Darrow, E.D. Fredrickson,  

E-print Network

1 MHD-Induced Alpha Particle Loss in TFTR S.J. Zweben, D.S. Darrow, E.D. Fredrickson, G. Taylor, S MHD-induced increases in alpha particle loss to the wall were observed for both coherent modes of the coherent MHD-induced alpha loss as seen by these detectors was normally comparable to the MHD

149

Discussion of Alpha Particle Physics Issues for AT Burning Plasmas  

E-print Network

. Gorelenkov · M3D (non-linear 3D kinetic-MHD) G. Fu v R&D Needs » Alpha simulation experiments needed of TAEs and enhanced loss » Generic avelanche events and stochastic diffusion observed » Major progress,...) » Physics and scaling of such regimes are poorly understood v R&D Issues » RF & flow shear control of ITBs

150

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

151

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

152

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

NASA Astrophysics Data System (ADS)

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.

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

153

Studies of Light and Charge Produced by Alpha-Particles in High-Pressure Xenon  

NASA Technical Reports Server (NTRS)

The results of measurements of scintillation light induced by alpha-particles in high-pressure Xe are presented. The ratio of N(sub ex)/N(sub i) and the intensity and time characteristics of the luminescence signal have been measured for different densities up to 0.74 g/cc. The role and mechanisms of the electron-ion recombination in high-pressure gas have been investigated. The existence of clusters and self-trapped excitons above 0.6 g/cc has been observed and discussed. This work is a part of a development program of high-pressure Xe detectors for low-energy gamma rays.

Bolotnikov, Aleksey; Ramsey, Brian

1999-01-01

154

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

NASA Astrophysics Data System (ADS)

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(++) 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.

155

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

156

Production of an Associated Particle Neutron Generator with ZnO:Ga Alpha-Detector  

SciTech Connect

An associated particle neutron generator (APNG) capable of 109 neutrons per second has been operated with an alpha particle detector made of a ZnO:Ga phosphor with decay time of approximately 1 ns. Fast 14.1 MeV neutrons and 3.5 MeV alpha particles are produced through deuterium-tritium (DT) fusion reactions and travel in opposite directions to conserve momentum. The neutron generator provides high rate capability, excellent subnanosecond time resolution (< 0.7 ns), and a large solid angle with acceptance of 8%. The alpha detector was found to have a detection efficiency of 88% using a Burle 8850 bialkali photocathode. The DT beam spot diameter was measured down to 2.1 mm with the possibility of achieving 1 mm if desired. An opaque aperture was placed on the alpha detector and the neutron beam was obstructed using various amounts of lead shielding in an effort to study the generator s imaging contrast capability for neutron radiography. The alpha detector can be pixilated using a multianode photomultiplier tube to deliver imaging capability and to enhance the signal to noise ratio. Due to its ability to suppress background, the developed APNG is to be used to search cargo containers for illicit special nuclear materials, using as a trigger prompt fission gamma rays in coincidence with an alpha particle within a 10 ns gate.

Koltick, David [Purdue University] [Purdue University; Kane, S Z. [Purdue University] [Purdue University; Mihalczo, John T [ORNL] [ORNL; McConchie, Seth M [ORNL] [ORNL; Mace, E. K. [2K Corporation] [2K Corporation; Lvovsky, M. [Lexel Imaging Systems] [Lexel Imaging Systems

2008-01-01

157

Cosmic Rays High Energy Particles  

E-print Network

T.Hebbeker Cosmic Rays High Energy Particles from the Universe Thomas Hebbeker RWTH Aachen.Hebbeker Cosmic Rays Discovery / Properties Influence on Earth / Life / Science High Energy Cosmic Rays Cosmic + + + + + + + + ++ + + + + Ionizing radiation discharges electrometer #12;T.Hebbeker Electric Properties of Cosmic Rays 1927 Clay

Hebbeker, Thomas

158

Cosmic Rays High Energy Particles  

E-print Network

T.Hebbeker Cosmic Rays High Energy Particles from the Universe Thomas Hebbeker RWTH Aachen #12;T.Hebbeker Cosmic Rays Discovery / Properties Influence on Earth / Life / Science High Energy Cosmic Rays Cosmic Sources and Propagation Auger-Observatory First Auger Results #12;T.Hebbeker Cosmic

Hebbeker, Thomas

159

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

NASA Astrophysics Data System (ADS)

Part of the energy of the Lower Hybrid (LH) waves may be absorbed by the ? particles via the so-called perpendicular landau damping mechanism, which depends on various parameters of fusion reactors and the LH waves. In this article, we calculate the absorption coefficient ?? of LH waves due to ? particles. Results show that, the ?? increases with the parallel refraction index n? while deceases with increasing the frequency of LH waves ?LH over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of ?? when ne?8×1019m-3 for ITER-like scenario. The thermal corrections to the cold plasma dispersion relation will change the damping rate to a certain extent under some specific conditions. We have also evaluated the fraction of LH power absorbed by the alpha particles, ? ? 0.47% and 4.1% for an LH frequency of 5 GHz and 3.7 GHz respectively for ITER-like scenario. This work gives the effective reference for the choice of parameters of future fusion reactors.

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

2014-02-01

160

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

161

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

162

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

SciTech Connect

An experiment was done with TFTR DT plasmas to determine the effect of the q(r) profile on the alpha particle ripple loss to the outer midplane. The alpha particle loss measurements were made using a radially movable scintillator detector 20 degrees below the outer midplane. The experimental results were compared with TF ripple loss calculations done using a Monte Carlo guiding center orbit following code, ORBIT. Although some of the experimental results are consistent with the ORBIT code modeling, the variation of the alpha loss with the q(r) profiles is not well explained by this code. Quantitative interpretation of these measurements requires a careful analysis of the limiter shadowing effect, which strongly determines the diffusion of alphas into the detector aperture.

D.S. Darrow; M. Diesso; R.V. Budny; S. Batha; S.J. Zweben; et al.

1997-09-01

163

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

164

Extraction of alpha_s from the energy evolution of jet fragmentation functions at low z  

E-print Network

A novel method to extract the QCD coupling alpha_s from the energy evolution of the moments of the parton-to-hadron fragmentation functions at low fractional hadron momentum z, is presented. The evolution of the moments (multiplicity, peak, width, skewness) of the charged-hadron distribution in jets is computed at NMLLA+NLO* accuracy and compared to the experimental deep-inelastic e-p data. Values of the strong coupling constant at the Z pole are obtained, alpha_s(m_Z) = 0.119 +/- 0.010, in excellent numerical agreement with the current world average determined using other methods at the same level of accuracy.

d'Enterria, David

2014-01-01

165

Alpha-particle formation and decay rates from Skyrme-HFB wave functions  

E-print Network

$\\alpha$ decay is treated microscopically, where the unstable mother nucleus and residual daughter nucleus are described using HFB wave functions, obtained with the Skyrme effective interaction. From these wave functions the amplitude for forming $\\alpha$ 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 under-estimated.

D. E. Ward; B. G. Carlsson; S. Åberg

2014-02-10

166

Rigidity-independent coronal propagation and escape of solar protons and alpha particles  

NASA Technical Reports Server (NTRS)

In a study of rigidity-independent coronal propagation processes, data on the azimuthal variation of the solar proton/alpha-particle ratio were obtained. Sources for the data included a statistical analysis of events observed by Heos-2, a comparative study of events recorded by both Heos-2 and Pioneer-10 and -11, and a multiday survey of individual events observed by Heos-2 and Pioneer-10. The statistical investigation of Heos-2 events reveals an increase of the lower value of the proton/alpha-particle ratio away from the well-connected region. The data from one or two spacecraft connected at different heliolongitudes indicates no azimuthal dependence of the proton/alpha-particle ratio. All the data appear to suggest rigidity-independent propagation or escape processes.

Perron, C.; Domingo, V.; Reinhard, R.; Wenzel, K.-P.

1978-01-01

167

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

PubMed Central

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

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

2014-01-01

168

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

169

Alpha-particle emission probabilities in the decay of 238U  

PubMed

238U decays by alpha-particle emission to 234Th. No direct measurements of alpha-particle emission probabilities (Palpha) of this nuclide have been reported since 1961, and recommended values for Palpha have remained unchanged for years, until recent evaluations suggested new values. This work presents the results of new measurements made with Si detectors and sources of natural uranium. The results obtained for the analysis of twenty spectra are: Palpha0 = 0.7754+/-0.0050, Palpha50 = 0.2233+/-0.0050 and Palpha163 = 0.0013+/-0.0003. PMID:10724411

Garcia-Torano

2000-03-01

170

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

E-print Network

The alpha accompanied cold ternary fission of even-even 244Cm, 246Cm, 248Cm, 250Cm and 252Cm isotopes have been studied by taking the interacting barrier as the sum of Coulomb and proximity potential with the fragments in equatorial configuration. The favorable fragment combinations are obtained from the cold reaction valley plot and by calculating the relative yield for the charge minimized fragments. In the alpha accompanied ternary fission of 244Cm isotope, the highest yield is found for the fragment combination 110Ru+4He+130Sn, which possess near doubly magic nuclei 130Sn. For the ternary fission of 246Cm, 248Cm, 250Cm and 252Cm isotopes with 4He as light charged particle, the highest yield is obtained for the fragment combination with doubly magic nuclei 132Sn as the heavier fragment. The emission probabilities and kinetic energies of long range alpha particle have been computed for the 242,244,246,248Cm isotopes and are found to be in good agreement with the experimental data. The relative yields for the 4He accompanied ternary fission (equatorial and collinear) of 242-252Cm isotopes are compared with the corresponding yield for binary fission. The effect of deformation and orientation of fragments in the 4He accompanied ternary fission of 244-252Cm isotopes are studied. Our study reveals that the ground state deformation has an important role in the alpha accompanied ternary fission as that of shell effect.

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

2014-09-02

171

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

NASA Astrophysics Data System (ADS)

The alpha accompanied cold ternary fission of even-even 244Cm, 246Cm, 248Cm, 250Cm and 252Cm isotopes has been studied by taking the interacting barrier as the sum of the Coulomb and proximity potential with the fragments in equatorial configuration. The favorable fragment combinations are obtained from the cold reaction valley plot and by calculating the relative yield for the charge minimized fragments. In the alpha accompanied ternary fission of the 244Cm isotope, the highest yield is found for the fragment combination 110Ru+4He+130Sn, which possess near doubly magic nuclei 130Sn. For the ternary fission of 246Cm, 248Cm, 250Cm and 252Cm isotopes with 4He as the light charged particle, the highest yield is obtained for the fragment combination with doubly magic nuclei 132Sn as the heavier fragment. The emission probabilities and kinetic energies of long range alpha particles have been computed for the 242,244,246,248Cm isotopes and are found to be in good agreement with the experimental data. The relative yields for the 4He accompanied ternary fission (equatorial and collinear) of 242-252Cm isotopes are compared with the corresponding yield for binary fission. The effect of deformation and orientation of fragments in the 4He accompanied ternary fission of 244-252Cm isotopes are studied. Our study reveals that the ground state deformation has as an important role in the alpha accompanied ternary fission as that of the shell effect.

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

2014-10-01

172

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

SciTech Connect

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

Garnier, Josselin [Laboratoire de Probabilites et Modeles Aleatoires and Laboratoire Jacques-Louis Lions, Universite Paris VII, 2 Place Jussieu, 75251 Paris Cedex 05 (France); Cherfils-Clerouin, Catherine [Commissariat a l'Energie Atomique, Direction des Applications Militaires, Boite Postale 12, 91680 Bruyeres le Chatel (France)

2008-10-15

173

Alpha particle-driven toroidal Alfven eigenmodes in Tokamak Fusion Test Reactor deuteriumtritium plasmas: Theory and experiments  

E-print Network

., Plasma Phys. Controlled Fusion 26, 11 1984 deuterium­tritium plasmas are analyzed using the NOVA-K code C can be destabilized by super- Alfve´nic alpha particles via parallel wave particle resonances.1

Fu, Guoyong

174

Nuclear Spins and Magnetic Moments by the alpha-Particle Model  

Microsoft Academic Search

Some properties of the light nuclei of the type nalpha+\\/-1 have been calculated on the basis of the alpha-particle model. By means of this description, spins and magnetic moments of the same nuclei are calculated here. The results for the magnetic moments of many of the nuclei are undetermined within a certain range of possible values since the relative order

R. G. Sachs

1939-01-01

175

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

176

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

ERIC Educational Resources Information Center

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

Digilov, M.

1991-01-01

177

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

178

Condition for absolute confinement of alpha-particles in axisymmetric tori  

Microsoft Academic Search

The paper derives a necessary condition for an axisymmetric torus to act as an absolute trap for fusion-generated alpha particles. For practical reasons it is assumed that the fusion reaction only occurs on the elliptic magnetic axis with maximum plasma pressure. It is shown that an important condition for any confinement system to be a fusion reactor is that the

K. Ikuta

1976-01-01

179

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. Brückner; G. Klingelhöfer; G. Dreibus; A. Yen; S. W. Squyres

2003-01-01

180

Depleted uranium-catalyzed oxidative DNA damage: absence of significant alpha particle decay  

Microsoft Academic Search

Depleted uranium (DU) is a dense heavy metal used primarily in military applications. Published data from our laboratory have demonstrated that DU exposure in vitro to immortalized human osteoblast cells (HOS) is both neoplastically transforming and genotoxic. DU possesses both a radiological (alpha particle) and a chemical (metal) component. Since DU has a low-specific activity in comparison to natural uranium,

Alexandra C. Miller; Michael Stewart; Kia Brooks; Lin Shi; Natalie Page

2002-01-01

181

Production of actinium-225 for alpha particle mediated radioimmunotherapy.  

PubMed

The initial clinical trials for treatment of acute myeloid leukemia have demonstrated the effectiveness of the alpha emitter (213)Bi in killing cancer cells. Bismuth-213 is obtained from a radionuclide generator system from decay of 10-days (225)Ac parent. Recent pre-clinical studies have also shown the potential application of both (213)Bi, and the (225)Ac parent radionuclide in a variety of cancer systems and targeted radiotherapy. This paper describes our five years of experience in production of (225)Ac in partial support of the on-going clinical trials. A four-step chemical process, consisting of both anion and cation exchange chromatography, is utilized for routine separation of carrier-free (225)Ac from a mixture of (228)Th, (229)Th and (232)Th. The separation of Ra and Ac from Th is achieved using the marcoporous anion exchange resin MP1 in 8M HNO(3) media. Two sequential MP1/NO(3) columns provide a separation factor of approximately 10(6) for Ra and Ac from Th. The separation of Ac from Ra is accomplished on a low cross-linking cation exchange resin AG50-X4 using 1.2M HNO(3) as eluant. Two sequential AG50/NO(3) columns provide a separation factor of approximately 10(2) for Ac from Ra. A 60-day processing schedule has been adopted in order to reduce the processing cost and to provide the highest levels of (225)Ac possible. Over an 8-week campaign, a total of approximately 100 mCi of (225)Ac (approximately 80% of the theoretical yield) is shipped in 5-6 batches, with the first batch typically consisting of approximately 50 mCi. After the initial separation and purification of Ac, the Ra pool is re-processed on a bi-weekly schedule or as needed to provide smaller batches of (225)Ac. The averaged radioisotopic purity of the (225)Ac was 99.6 +/- 0.7% with a (225)Ra content of < or =0.6%, and an average (229)Th content of (4(-4)(+5)) x 10(-5)%. PMID:15763472

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

2005-05-01

182

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

SciTech Connect

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

Cooper, E.L.; Cox, J.M.; Workman, W.J. [Chalk River Labs. (Canada). Environmental Research Branch

1998-12-31

183

Map model for nonlinear alpha particle interaction with toroidal Alfven waves  

SciTech Connect

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

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

1992-09-01

184

Energetic protons, alpha particles, and electrons in magnetic flux transfer events  

NASA Technical Reports Server (NTRS)

Energetic proton, alpha particle, and electron data are presented for two magnetopause crossings, which show magnetic field signatures characteristic of flux transfer events (FTEs). Energetic proton and alpha particles are observed streaming along the magnetic field within the magnetosheath in all events showing magnetic signatures characteristic of the FTEs. Flux ratios as high as about 180 parallel and antiparallel to the magnetic field are observed, which means that ions of about 30 keV per charge are at times streaming almost scatter-free from the magnetopause into the magnetosheath. Energetic ion bursts with signatures equal to those observed in FTEs are reduced by more than an order of magnitude as compared to the trapped particle flux.

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

1982-01-01

185

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

PubMed

Radioimmunotherapy has proven clinically effective in patients with non-Hodgkin's lymphoma. Radioimmunotherapy trials have so far been performed with beta-emitting isotopes. In contrast to beta-emitters, the shorter range and high linear energy transfer (LET) of alpha particles allow for more efficient and selective killing of individually targeted tumor cells. However, there are several obstacles to the use of alpha-particle immunotherapy, including problems with chelation chemistry and nontarget tissue toxicity. The alpha-emitting radioimmunoconjugate (227)Th-DOTA-p-benzyl-rituximab is a new potential anti-lymphoma agent that might overcome some of these difficulties. The present study explores the immunoreactivity, in vivo stability and biodistribution, as well as the effect on in vitro cell growth, of this novel radioimmunoconjugate. To evaluate in vivo stability, uptake in balb/c mice of the alpha-particle-emitting nuclide (227)Th alone, the chelated form, (227)Th-p-nitrobenzyl-DOTA and the radioimmunoconjugate (227)Th-DOTA-p-benzyl-rituximab was compared in a range of organs at increasing time points after injection. The immunoreactive fraction of (227)Th-DOTA-p-benzyl-rituximab was 56-65%. During the 28 days after injection of radioimmunoconjugate only, very modest amounts of the (227)Th had detached from DOTA-p-benzyl-rituximab, indicating a relevant stability in vivo. The half-life of (227)Th-DOTA-p-benzyl-rituximab in blood was 7.4 days. Incubation of lymphoma cells with (227)Th-DOTA-p-benzyl-rituximab resulted in a significant antigen-dependent inhibition of cell growth. The data presented here warrant further studies of (227)Th-DOTA-p-benzyl-rituximab. PMID:16546683

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

2006-02-01

186

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

E-print Network

The alpha accompanied cold ternary fission of even-even 244Cm, 246Cm, 248Cm, 250Cm and 252Cm isotopes have been studied by taking the interacting barrier as the sum of Coulomb and proximity potential with the fragments in equatorial configuration. The favorable fragment combinations are obtained from the cold reaction valley plot and by calculating the relative yield for the charge minimized fragments. In the alpha accompanied ternary fission of 244Cm isotope, the highest yield is found for the fragment combination 110Ru+4He+130Sn, which possess near doubly magic nuclei 130Sn. For the ternary fission of 246Cm, 248Cm, 250Cm and 252Cm isotopes with 4He as light charged particle, the highest yield is obtained for the fragment combination with doubly magic nuclei 132Sn as the heavier fragment. The emission probabilities and kinetic energies of long range alpha particle have been computed for the 242,244,246,248Cm isotopes and are found to be in good agreement with the experimental data. The relative yields for th...

Santhosh, K P; Priyanka, B

2014-01-01

187

Ionization and scintillation response of high-pressure xenon gas to alpha particles  

E-print Network

High-pressure xenon gas is an attractive detection medium for a variety of applications in fundamental and applied physics. In this paper we study the ionization and scintillation detection properties of xenon gas at 10 bar pressure. For this purpose, we use a source of alpha particles in the NEXT-DEMO time projection chamber, the large scale prototype of the NEXT-100 neutrinoless double beta decay experiment, in three different drift electric field configurations. We measure the ionization electron drift velocity and longitudinal diffusion, and compare our results to expectations based on available electron scattering cross sections on pure xenon. In addition, two types of measurements addressing the connection between the ionization and scintillation yields are performed. On the one hand we observe, for the first time in xenon gas, large event-by-event correlated fluctuations between the ionization and scintillation signals, similar to that already observed in liquid xenon. On the other hand, we study the field dependence of the average scintillation and ionization yields. Both types of measurements may shed light on the mechanism of electron-ion recombination in xenon gas for highly-ionizing particles. Finally, by comparing the response of alpha particles and electrons in NEXT-DEMO, we find no evidence for quenching of the primary scintillation light produced by alpha particles in the xenon gas.

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

2012-11-19

188

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

PubMed Central

Ever since the discovery of X-rays was made by Röntgen 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 AL 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 ?M 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. PMID:10681418

Zhou, Hongning; Randers-Pehrson, Gerhard; Waldren, Charles A.; Vannais, Diane; Hall, Eric J.; Hei, Tom K.

2000-01-01

189

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

PubMed

The probability of the formation of ionization clusters by primary alpha-particles at 5.4 MeV in nanometric volumes of propane was studied experimentally and by Monte Carlo simulation, as a function of the distance between the center line of the particle beam and the center of the target volume. The volumes were of cylindrical shape, 3.7 mm in diameter and height. As the investigations were performed at gas pressures of 300 Pa and 350 Pa, the dimensions of the target volume were equivalent to 20.6 nm or 24.0 nm in a material of density 1.0 g/cm(3). The dependence of ionization-cluster formation on distance was studied up to values equivalent to about 70 nm. To validate the measurements, a Monte Carlo model was developed which allows the experimental arrangement and the interactions of alpha-particles and secondary electrons in the counter gas to be properly simulated. This model is supplemented by a mathematical formulation of cluster size formation in nanometric targets. The main results of our study are (i) that the mean ionization-cluster size in the delta-electron cloud of an alpha-particle track segment, decreases as a function of the distance between the center line of the alpha-particle beam and the center of the sensitive target volume to the power of 2.6, and (ii) that the mean cluster size in critical volumes and the relative variance of mean cluster size due to delta-electrons are invariant at distances greater than about 20 nm. We could imagine that the ionization-cluster formation in nanometric volumes might in future provide the physical basis for a redefinition of radiation quality. PMID:12541070

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

2002-12-01

190

Clusters of intramembrane particles associated with binding sites for alpha-bungarotoxin in cultured chick myotubes  

PubMed Central

Developing chick myotubes in tissue culture were freeze-fractured to yield complementary replicas of large areas of membrane. Regions of muscle fibers with high concentrations of acetylcholine receptors were identified by binding of fluorescent-labeled alpha-bungarotoxin. Membranes in such regions contained clusters of large (100 A Diam) angular particles, similar in appearance to particles found in postsynaptic membranes of cholinergic synapses. Particles appeared in apposing areas of cytoplasmic and external leaflets but were more prevalent in the cytoplasmic leaflet. The areas of high particle concentration were coextensive with the fluorescence due to bound toxin. Treatment of cultures with tetrodotoxin increased the size of fluorescent spots and areas of high concentration of particles relative to those found in control cultures. In muscle cultures grown in the presence of spinal cord explants, some neurites contacted and innervated nearby myotubes. Intense fluorescence due to binding or alpha-bungarotoxin was present at portions of such neurite-myotube contacts. At these same portions, a high concentration of large angular particles was present in the sarcolemma adjacent to the neurite. In addition, an ordered arrangement of large particles was seen in the cytoplasmic leaflet of the neuronal plasmalemma directly apposing the muscle. The possible significance of these arrangements is discussed. Clusters on myotubes tended to be larger (contain more particles) when they occurred in groups, defined as three or more clusters with an intercluster distance of less than 0.5 micrometers. Clusters were also larger in myotubes treated with tetrodotoxin and in myotubes adjacent to some neurites in nerve-muscle cocultures. Several depressions containing particles similar to those in the clusters were found in the sarcolemma. The implications of these depressions are discussed in light of current theories of incorporation of proteins into cell membranes. PMID:479313

1979-01-01

191

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

SciTech Connect

Predictions for ripple loss of fast ions from TFTR are investigated with a guiding center including both collisional and ripple effects. Discrepancies between measurements and calculations of plasma beta at low current and large major radius are resolved when both effects are included for neutral beam ions. A synergistic enhancement of fast ion diffusion is found for toroidal field ripple with collisions. S = 5.4 for neutral beam ions and S = 1.4--2.4 for alpha particles. A 20--30% reduction in alpha particle heating is predicted for R = 2.6 m DT plasmas on TFTR due to first orbit and collisional stochastic ripple diffusion, although these losses will be reduced if q{sub a} and R are smaller, as for most planned DT experiments.

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

1994-09-01

192

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

193

The Ionization and Stopping Power of Various Gases for Alpha Particles from Polonium. II  

Microsoft Academic Search

The ionizations of nitric oxide, nitrous oxide, and air were found to be strictly proportional along the range, while methyl iodide shows definite systematic deviations. A method of determining differential stopping powers for alpha-particles has been applied to a number of gases. The results show that such unstable molecules as NO and H3C-N=NCH3 give strictly additive stopping powers. The stopping

G. E. Gibson; H. Eyring

1927-01-01

194

Geminate Recombination of alpha-Particle-Excited Carriers in Liguid Argon  

Microsoft Academic Search

We report experimental evidence showing that the electric-field-dependent yield of carriers excited in the track of an alpha particle stopping in liquid argon is dominated by geminate (initial) recombination of electron-ion pairs. This is the first confirmation of geminate carrier recombination in a noble-gas liquid. The thermalization length of the hot electrons is determined to be about 28 nm.

C. R. Gruhn; M. D. Edmiston

1978-01-01

195

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

Bunno, M.; Nakamura, Y. [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

196

Rapid appearance of transient secondary adrenocortical insufficiency after alpha-particle radiation therapy for Cushing's disease  

Microsoft Academic Search

A 17-year-old woman received 12,000 rads of alpha-particle radiation for the treatment of Cushing's disease. One day after the completion of therapy, the patient developed nausea, vomiting, headache, and postural hypotension. Laboratory evaluation demonstrated a marked fall of the previously elevated urinary 17-hydroxycorticosteroids (17-OHCS) and undetectable plasma cortisols. The urinary 17-OHCS transiently returned to supranormal levels but over a 2¹\\/â-week

D. M. Cook; R. M. Jordan; J. W. Kendall; J. A. Linfoot

1976-01-01

197

Alpha particles versus conventional radiotherapy to the pituitary region: a comparison of risk-benefit  

SciTech Connect

At the present time there are no prospective controlled studies or comparative studies on the effectiveness of the various modalities of pituitary treatment-surgery and photon and alpha particle pituitary irradiation. In this review the results of alpha particle pituitary irradiation (APPI), initiated at the Donner Laboratory and Donner Pavilion at the Lawrence Berkeley Laboratory, University of California, Berkeley, and the results of conventonal photon irradiation (gamma or x-rays) will be presented. In general it has been established that the effects of photon therapy are related to the size of radiation field, type of isodose curve, total radiation dose (rads), duration of therapy, and rads delivered per fraction. Minor complications of photon therapy included epilation of the scalp and, occasionally, mild headache. In the past few years there has been a trend to reduce the total radiation dose as well as the dose per fraction. Finally, in photon therapy, large fields are utilized, involving a large volume of tissue. In contrast, alpha particle pituitary irradiation utilizes a pencil-shaped beam which is made to fit the contour of the sella turcica. The dose to the skin and peripheral portions of the brain is minimal, and no epilation occurs.

Linfoot, J.A.

1980-01-01

198

Alpha Particle Physics Experiments in the Tokamak Fusion Test Reactor S.J. Zweben, R.V. Budny, D.S. Darrow, S.S. Medley, R. Nazikian,  

E-print Network

1 Alpha Particle Physics Experiments in the Tokamak Fusion Test Reactor S.J. Zweben, R.V. Budny, D Princeton Plasma Physics Laboratory P.O. Box 451, Princeton, NJ 08540 USA Abstract Alpha particle physics and papers on alpha particle physics and fusion products measurements has also been compiled recently [2

199

Radioimmunotherapy of Breast Cancer Metastases with Alpha-Particle-emitter 225Ac: Comparing Efficacy with 213Bi, 90Y  

PubMed Central

Alpha-particles are suitable to treat cancer micrometastases because of their short range and very high linear energy transfer. Alpha-particle-emitter 213Bi based radioimmunotherapy has shown efficacy in a variety of metastatic animal cancer models, such as breast, ovarian, prostate cancer and leukemia. Its clinical implementation, however, is challenging due to the limited supply of 225Ac, the high technical requirement to prepare radioimmunoconjugate with very short half-life (T1/2=45.6 mins) on site and prohibitive cost. In this study, we investigated the efficacy of the alpha-particle-emitter 225Ac, parent of 213Bi, in a mouse model of breast cancer metastases. A single administration of 225Ac (400 nCi) labeled anti-rat HER-2/neu monoclonal antibody (7.16.4) completely eradicated breast cancer lung micrometastases in about 67% of HER-2/neu transgenic mice and led to long-term survival of these mice for up to one year. Treatment with 225Ac-7.16.4 is significantly more effective than 213Bi-7.16.4 (120 ?Ci) (median survival = 61 days, P=0.001), and 90Y-7.16.4 (120 ?Ci) (median survival = 50 days, P<0.001), as well as untreated control (median survival = 41 days, P=0.0001). Dosimetric analysis showed that 225Ac treated metastases received a total dose of 9.6 Gy, significantly higher than 2.0 Gy from 213Bi and 2.4 Gy from 90Y. Biodistribution studies revealed that 225Ac daughters, 221Fr and 213Bi, accumulated in kidneys and probably contributed to the long-term renal toxicity observed in surviving mice. These data suggest 225Ac labeled anti-HER-2/neu monoclonal antibody could significantly prolong survival in HER-2/neu-positive metastatic breast cancer patients. PMID:19920193

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

2009-01-01

200

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

PubMed

alpha-Particles are suitable to treat cancer micrometastases because of their short range and very high linear energy transfer. alpha-Particle emitter (213)Bi-based radioimmunotherapy has shown efficacy in a variety of metastatic animal cancer models, such as breast, ovarian, and prostate cancers. Its clinical implementation, however, is challenging due to the limited supply of (225)Ac, high technical requirement to prepare radioimmunoconjugate with very short half-life (T(1/2) = 45.6 min) on site, and prohibitive cost. In this study, we investigated the efficacy of the alpha-particle emitter (225)Ac, parent of (213)Bi, in a mouse model of breast cancer metastases. A single administration of (225)Ac (400 nCi)-labeled anti-rat HER-2/neu monoclonal antibody (7.16.4) completely eradicated breast cancer lung micrometastases in approximately 67% of HER-2/neu transgenic mice and led to long-term survival of these mice for up to 1 year. Treatment with (225)Ac-7.16.4 is significantly more effective than (213)Bi-7.16.4 (120 microCi; median survival, 61 days; P = 0.001) and (90)Y-7.16.4 (120 microCi; median survival, 50 days; P < 0.001) as well as untreated control (median survival, 41 days; P < 0.0001). Dosimetric analysis showed that (225)Ac-treated metastases received a total dose of 9.6 Gy, significantly higher than 2.0 Gy from (213)Bi and 2.4 Gy from (90)Y. Biodistribution studies revealed that (225)Ac daughters, (221)Fr and (213)Bi, accumulated in kidneys and probably contributed to the long-term renal toxicity observed in surviving mice. These data suggest (225)Ac-labeled anti-HER-2/neu monoclonal antibody could significantly prolong survival in HER-2/neu-positive metastatic breast cancer patients. PMID:19920193

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

2009-12-01

201

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

NSDL National Science Digital Library

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

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

2006-12-01

202

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

203

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

PubMed Central

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

2014-01-01

204

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

E-print Network

with measurements of the alpha distribution function made with a sensitive active neutral particle diagnostic burnup experiments at JT­60U [2]. Both these observations support the assertion that suprathermal ions

205

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

E-print Network

with measurements of the alpha distribution function made with a sensitive active neutral particle diagnostic burnup experiments at JT-60U [2]. Both these observations support the assertion that suprathermal ions

206

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

PubMed Central

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

2012-01-01

207

The WASTED Resolutions: exploration of the spatial and energy limits of the Webcam Alpha Spectrometer TEchnology Demonstrator  

NASA Astrophysics Data System (ADS)

Scientists and engineers build simple, low-cost, webcam-based instruments for use in many disciplines. Analysis of the optical signal received through the three broadband color filters -- red, green and blue -- form the basis of many of those instruments. The CMOS sensors in webcam pixels also produce signals in response to ionizing radiations -- such as alpha particles from a radioactive source. Simple alpha radiography has been demonstrated with an alpha source and a webcam modified to expose the sensors. The performance of the Webcam Alpha Spectrometer TEchnology Demonstrator (WASTED) built from such a modified webcam and a commercially available alpha source mounted to an optics rail is analyzed in terms of the energy upper-half-width-half-maximum and of the spatial modulation transfer function.

Fryman, Joseph; Pallone, Arthur

2012-02-01

208

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

PubMed Central

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

Lehnert, B E; Goodwin, E H

1997-01-01

209

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

210

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

PubMed

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

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

2012-09-01

211

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

SciTech Connect

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

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

1989-03-01

212

Alpha-Particle and Gamma-Ray Spectra of the U230 Decay Series  

Microsoft Academic Search

The radiations of the U230 family have been investigated with an electromagnetic alpha-particle spectrograph and gamma-ray scintillation counters. The following alpha groups were found: U230-5.884 (67.2%), 5.813 (32.1%), 5.658 (0.7%); Th226-6.330 (79%), 6.220 (19%), 6.095 (1.7%), 6.029 (0.6%); Ra222-6.551 Em218-7.127 Mev. The following gamma rays were seen: U230-72 (0.75%), 158 (0.33%); 232 (0.24%); Th226-112 (4.8%); 131 (0.4%), 197 (0.40%), 242

Frank Asaro; I. Perlman

1956-01-01

213

Free Energy Formalism for Particle Adsorption  

E-print Network

The equilibrium properties of particles adsorption is investigated theoretically. The model relies on a free energy formulation which allows to generalize the Maxwell-Boltzmann description to solutions for which the bulk volume fraction of potentially adsorbed particles is very high. As an application we consider the equilibrium physical adsorption of neutral and charged particles from solution onto two parallel adsorbing surfaces.

Pierre Gosselin; Herve Mohrbach

2005-02-04

214

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

SciTech Connect

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

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

2009-01-01

215

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

216

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

217

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

218

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

219

Elastic scattering of alpha particles and the phase of the nucleon-nucleon scattering amplitude  

NASA Technical Reports Server (NTRS)

Glauber theory can describe elastic scattering of alpha particles by He-4, He-3, H-2, and H-1 at 7 GeV/c if the phase of the nucleon-nucleon elastic-scattering amplitude varies with momentum transfer. The phase variation leads to diffraction patterns differing markedly from those typical of constant-phase calculations and greatly affects the magnitudes of the intensities. These changes are mainly due to changes in the interference between amplitudes for different orders of multiple scattering and to a decrease in their moduli.

Franco, V.; Yin, Y.

1985-01-01

220

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

221

Feasibility of an alpha particle gas densimeter for stack sampling applications  

E-print Network

LISTING APPENDIX C TABULATED RESULTS 58 60 72 VI TA 84 Vi LIST OF TABLES TABLE P age I Typical Flue Gas Compositions II Model Flue Gas Compositions 35 Coeff icients for Alpha particle Stopping Power Functions 59 Computed and Experimental... is obtained using a Type S Pitot. Tube, described in EPA Method 2 , using, 2 V = K 2g AP Ps (4) where, K = pitot tube flow coefficient g = gravitational constant AP = pressure drop data from pitot tube p = stack gas density. s Stack gas density...

Johnson, Randall Mark

2012-06-07

222

Muon-alpha-particle sticking probability in muon-catalyzed fusion  

NASA Astrophysics Data System (ADS)

The Green's-function Monte Carlo method is used to calculate the ground-state wave function of the muonic-molecular ion composed of a negative muon bound to a deuteron and a triton. Using the sudden approximation, the probability that the muon will remain bound to the escaping alpha particle after fusion occurs is found to be 0.90%, about 25% smaller than previous estimates based on the Born-Oppenheimer approximation. The numerical method for determining the wave function is discussed in detail.

Ceperley, D.; Alder, B. J.

1985-04-01

223

Balmer alpha emission and hydrogen atom energy in ion-source discharges  

SciTech Connect

The structure of the hydrogen Balmer alpha line emission profiles from three types of neutral beam injector ion source plasmas (filling pressure approx. 10 mTorr, electron density approx. 1 to 2 x 10/sup 12/ cm/sup -3/, electron temperature approx. 2 to 4 eV) is studied with the aid of a simple model for the neutral particle balance and H/sub ..cap alpha../ emission. A large fraction of the H/sub ..cap alpha../ is produced by dissociative excitation of H/sub 2/ and dissociative recombination of H/sub 2//sup +/, while the remainder is produced by excitation of H atoms, most of which have energies that are close to the characteristic H/sub 2/ dissociation energies. The H/sub ..cap alpha../ linewidth is thus insensitive to the discharge operating conditions and equals approx. 0.27 A when only slow (approx. 0.3 eV) dissociatively excited atoms are present or approx. 0.35 A when fast (> 1 eV) atoms, apparently also produced in dissociation reactions, are present as well.

McNeill, D.H.; Kim, J.

1981-07-01

224

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 peak’s 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.

225

Study of substrate topographical effects on epithelial cell behavior using etched alpha-particle tracks on PADC films  

E-print Network

by the topography of track-etch pits, while etching of the substrate alone (without alpha-particle irradiation) did-particle irradiation; PADC; HeLa cell; Topography; Vinculin 1. Introduction Many implant applications involve porous materials. It is now well established that pores introduce topographies onto the substrates, while substrate

Yu, K.N.

226

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

NASA Technical Reports Server (NTRS)

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

Aprile, Elena; Mukherjee, Reshmi; Suzuki, Masayo

1990-01-01

227

Particle production at RHIC energies  

E-print Network

This paper presents recent results from the BRAHMS experiment at RHIC; including results on particle production in rapidity space extending from y=0 to y ~ 3 and on the transverse momentum distribution of fully identified charged particles. These results were obtained from the 5% most central Au-Au collisions recorded during RHIC Run-2 at sqrt{s_{NN}} = 200 GeV.

R. Debbe; for the BRAHMS collaboration

2003-08-06

228

Astronomy with ultra high-energy particles  

E-print Network

Recent measurements of the properties of cosmic rays above 10^17 eV are summarized and implications on our contemporary understanding of their origin are discussed. Cosmic rays with energies exceeding 10^20 eV have been measured, they are the highest-energy particles in the Universe. Particles at highest energies are expected to be only marginally deflected by magnetic fields and they should point towards their sources on the sky. Recent results of the Pierre Auger Observatory have opened a new window to the Universe - astronomy with ultra high-energy particles.

Joerg R. Hoerandel

2008-03-20

229

Mechanical properties and microstructure of $alpha;-particle irradiated Fe-12% Cr-15, 30% Mn alloys  

NASA Astrophysics Data System (ADS)

The effect of helium injection on the mechanical properties of Fe?Cr?Mn alloys has been investigated. Materials used are Fe-12%Cr-15%Mn alloy and Fe-12%Cr-30%Mn alloy. The elongation of these alloys decreased with alpha particle irradiation. Intergranular-ductile fracture was observed on the Fe-12%Cr-30%Mn alloy in which alpha particles had been injected in amounts up to 2.1 × 10 17 cm -2 at the depth of range, whereas transgranular-ductile fracture occurred on the Fe-12%Cr-15%Mn alloy. These phenomena are, however, in contrast to the authors' previous result of Type 316 stainless steel which showed intergranular-brittle fracture in the helium deposited zone. The difference of formation and distribution of helium bubbles among the two Fe?Cr?Mn alloys and the 316 stainless steel was recognized, and this difference is considered to be an important factor to determine the fracture modes of these materials.

Miyahara, K.; Okazaki, Y.; Mochizukl, M.; Hosoi, Y.; Kayano, H.

1988-07-01

230

Targeted cytoplasmic irradiation with alpha particles induces mutations in mammalian cells  

PubMed Central

Ever since x-rays were shown to induce mutation in Drosophila more than 70 years ago, prevailing dogma considered the genotoxic effects of ionizing radiation, such as mutations and carcinogenesis, as being due mostly to direct damage to the nucleus. Although there was indication that alpha particle traversal through cellular cytoplasm was innocuous, the full impact remained unknown. The availability of the microbeam at the Radiological Research Accelerator Facility of Columbia University made it possible to target and irradiate the cytoplasm of individual cells in a highly localized spatial region. By using dual fluorochrome dyes (Hoechst and Nile Red) to locate nucleus and cellular cytoplasm, respectively, thereby avoiding inadvertent traversal of nuclei, we show here that cytoplasmic irradiation is mutagenic at the CD59 (S1) locus of human–hamster hybrid (AL) cells, while inflicting minimal cytotoxicity. The principal class of mutations induced are similar to those of spontaneous origin and are entirely different from those of nuclear irradiation. Furthermore, experiments with radical scavenger and inhibitor of intracellular glutathione indicated that the mutagenicity of cytoplasmic irradiation depends on generation of reactive oxygen species. These findings suggest that cytoplasm is an important target for genotoxic effects of ionizing radiation, particularly radon, the second leading cause of lung cancer in the United States. In addition, cytoplasmic traversal by alpha particles may be more dangerous than nuclear traversal, because the mutagenicity is accomplished by little or no killing of the target cells. PMID:10220401

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

1999-01-01

231

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

232

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

PubMed Central

Background Abnormal regulation of angiogenesis in tumors results in the formation of vessels that are necessary for tumor growth, but compromised in structure and function. Abnormal tumor vasculature impairs oxygen and drug delivery and results in radiotherapy and chemotherapy resistance, respectively. Alpha particles are extraordinarily potent, short-ranged radiations with geometry uniquely suitable for selectively killing neovasculature. Methodology and Principal Findings Actinium-225 (225Ac)-E4G10, an alpha-emitting antibody construct reactive with the unengaged form of vascular endothelial cadherin, is capable of potent, selective killing of tumor neovascular endothelium and late endothelial progenitors in bone-marrow and blood. No specific normal-tissue uptake of E4G10 was seen by imaging or post-mortem biodistribution studies in mice. In a mouse-model of prostatic carcinoma, 225Ac-E4G10 treatment resulted in inhibition of tumor growth, lower serum prostate specific antigen level and markedly prolonged survival, which was further enhanced by subsequent administration of paclitaxel. Immunohistochemistry revealed lower vessel density and enhanced tumor cell apoptosis in 225Ac-E4G10 treated tumors. Additionally, the residual tumor vasculature appeared normalized as evident by enhanced pericyte coverage following 225Ac-E4G10 therapy. However, no toxicity was observed in vascularized normal organs following 225Ac-E4G10 therapy. Conclusions The data suggest that alpha-particle immunotherapy to neovasculature, alone or in combination with sequential chemotherapy, is an effective approach to cancer therapy. PMID:17342201

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

2007-01-01

233

Two-pion production in {alpha}p scattering at 1 GeV/nucleon in the energy region of the Roper resonance excitation  

SciTech Connect

Semiexclusive measurements of the two-pion-production p({alpha},{alpha}{sup '})p{pi}{pi} reaction have been carried out at an energy of E{sub {alpha}}=4.2 GeV at the Saturne-II (Saclay) accelerator with the SPES4-{pi} installation. This reaction was investigated by simultaneous registration of the scattered {alpha} particle and the secondary proton. The obtained results show that the two-pion production in inelastic {alpha}-particle scattering on the proton at the energy of the experiment proceeds mainly through excitation in the target proton of the Roper resonance and its decay with emission of two pions in the isospin I=0,S-wave state.

Alkhazov, G. D.; Kravtsov, A. V.; Mylnikov, V. A.; Orischin, E. M.; Prokofiev, A. N.; Razmyslovich, B. V.; Smirnov, I. B.; Tkach, I. I.; Volkov, S. S.; Zhdanov, A. A. [Petersburg Nuclear Physics Institute, Gatchina RU-188300 (Russian Federation); Augustyniak, W.; Zupranski, P. [Institute for Nuclear Studies, Warsaw PL-00681 (Poland); Boivin, M. [Laboratoire National Saturne, CNRS/IN2P3 and CEA/DSM, Gif-sur-Yvette Cedex F-91191 (France); Boyard, J.-L.; Farhi, L.; Hennino, T.; Jourdain, J.-C.; Kunne, R.; Ramstein, B.; Roy-Stephan, M. [Institut de Physique Nucleaire Orsay, CNRS/IN2P3, Orsay F-91400 (France)] (and others)

2008-08-15

234

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

PubMed Central

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

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

2011-01-01

235

Alpha voltaic batteries and methods thereof  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

236

Cell killing and division delay in asynchronous and synchronized HeLa cells irradiated with alpha particles or x rays  

SciTech Connect

HeLa cells irradiated with a single or two split doses of ..cap alpha.. particles or X rays were observed with time-lapse photography or examined for their colony-forming ability. The cell cycle-dependent variation of cell killing and division delay were compared in synchronous and asynchronous cell populations. Cellular damage by ..cap alpha.. particles was manifested in the form of cessation of division, or death, rather than partial division which was predominant for X irradiation. The pattern of cell killing with ..cap alpha.. particles was similar to that found with X rays, in that high sensitivity was noted at or close to mitosis, while a resistant peak remained at late S but not in early G/sub 1/. The pattern of division delay was similar for X rays and ..cap alpha.. particles during G/sub 2/-M, with a maximum delay at mid G/sub 2/ and no delay past the transition point, but differed during G/sub 1/-S. During this period, division delay increased with cell age, whereas it showed a broad peak at G/sub 1/-S boundary and a trough at late S for X rays. However, such was not the case for ..cap alpha.. particles.

Sasaki, H.

1984-08-01

237

Decay of the 112Sn compound nucleus: Excitation functions of evaporation residues, energy spectra, and angular distributions of evaporated protons and alphas  

NASA Astrophysics Data System (ADS)

Evaporation residue excitation functions of the reaction 19F + 93Nb --> 112Sn*, in the bombarding energy range between 54 and 95 MeV, have been measured using the recoil catcher technique. Energy spectra, angular distributions, and correlations between angular anisotropy and ejectile energy of evaporated protons and alpha particles have been measured for the above system at 73 and 95 MeV bombarding energies. The experimental data are compared with the predictions of the statistical model code PACE2 making use of two different level density formalisms. The level density parameters derived from the proton and alpha spectra are presented. The angular-anisotropy ejectile-energy correlations of the alpha particles show a peak in the variation of the anisotropy with the ejectile energy in the subevaporation barrier range. The sensitivity of the angular-anisotropy ejectile-energy correlations to the statistical model parameters is discussed.

John, Bency; Kataria, S. K.; Tomar, B. S.; Goswami, A.; Gubbi, G. K.; Manohar, S. B.

1997-11-01

238

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

SciTech Connect

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

Ahmad, I.; Alvi, M.A.

1983-12-01

239

Measurement of alphas from energy-energy correlations at the Z0 resonance  

Microsoft Academic Search

We determine the strong coupling alphas from a comprehensive study of energy-energy correlations (EEC's) and their asymmetry (AEEC's) in hadronic decays of Z0 bosons collected by the SLD experiment at SLAC. The data are compared with all four available predictions of QCD calculated up to O(alpha2s) in perturbation theory, and also with a resummed calculation matched to all four of

K. Abe; I. Abt; W. W. Ash; D. Aston; N. Bacchetta; K. G. Baird; C. Baltay; H. R. Band; M. B. Barakat; G. Baranko; O. Bardon; T. Barklow; A. O. Bazarko; R. Ben-David; A. C. Benvenuti; T. Bienz; G. M. Bilei; D. Bisello; G. Blaylock; J. R. Bogart; T. Bolton; G. R. Bower; J. E. Brau; M. Breidenbach; W. M. Bugg; D. Burke; T. H. Burnett; P. N. Burrows; W. Busza; A. Calcaterra; D. O. Caldwell; D. Calloway; B. Camanzi; M. Carpinelli; R. Cassell; R. Castaldi; A. Castro; M. Cavalli-Sforza; E. Church; H. O. Cohn; J. A. Coller; V. Cook; R. Cotton; R. F. Cowan; D. G. Coyne; A. D'oliveira; C. J. Damerell; S. Dasu; R. de Sangro; P. de Simone; R. dell'orso; Y. C. Du; R. Dubois; B. I. Eisenstein; R. Elia; C. Fan; M. J. Fero; R. Frey; K. Furuno; T. Gillman; G. Gladding; S. Gonzalez; G. D. Hallewell; E. L. Hart; Y. Hasegawa; S. Hedges; S. S. Hertzbach; M. D. Hildreth; J. Huber; M. E. Huffer; E. W. Hughes; H. Hwang; Y. Iwasaki; P. Jacques; J. Jaros; A. S. Johnson; J. R. Johnson; R. A. Johnson; T. Junk; R. Kajikawa; M. Kalelkar; I. Karliner; H. Kawahara; H. W. Kendall; M. E. King; R. King; R. R. Kofler; N. M. Krishna; R. S. Kroeger; Y. Kwon; J. F. Labs; M. Langston; A. Lath; J. A. Lauber; D. W. Leith; X. Liu; M. Loreti; A. Lu; H. L. Lynch; J. Ma; G. Mancinelli; S. Manly; G. Mantovani; T. W. Markiewicz; T. Maruyama; H. Masuda; E. Mazzucato; A. K. McKemey; B. T. Meadows; R. Messner; P. M. Mockett; K. C. Moffeit; B. Mours; G. Müller; D. Muller; T. Nagamine; U. Nauenberg; H. Neal; M. Nussbaum; L. S. Osborne; R. S. Panvini; T. J. Pavel; I. Peruzzi; L. Pescara; M. Piccolo; L. Piemontese; E. Pieroni; K. T. Pitts; R. J. Plano; R. Prepost; C. Y. Prescott; G. D. Punkar; J. Quigley; B. N. Ratcliff; T. W. Reeves; P. E. Rensing; L. S. Rochester; J. E. Rothberg; P. C. Rowson; J. J. Russell; O. H. Saxton; T. Schalk; R. H. Schindler; U. Schneekloth; B. A. Schumm; A. Seiden; S. Sen; M. H. Shaevitz; J. T. Shank; G. Shapiro; D. J. Sherden; C. Simopoulos; S. R. Smith; J. A. Snyder; P. Stamer; H. Steiner; R. Steiner; M. G. Strauss; D. Su; F. Suekane; A. Sugiyama; S. Suzuki; M. Swartz; A. Szumilo; T. Takahashi; F. E. Taylor; E. Torrence; J. D. Turk; T. Usher; J. Va'vra; C. Vannini; E. Vella; J. P. Venuti; P. G. Verdini; S. R. Wagner; A. P. Waite; S. J. Watts; A. W. Weidemann; J. S. Whitaker; S. L. White; F. J. Wickens; D. A. Williams; S. H. Williams; S. Willocq; R. J. Wilson; W. J. Wisniewski; M. Woods; G. B. Word; J. Wyss; R. K. Yamamoto; J. M. Yamartino; S. J. Yellin; C. C. Young; H. Yuta; G. Zapalac; R. W. Zdarko; C. Zeitlin; J. Zhou

1994-01-01

240

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

241

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

SciTech Connect

This paper describes a methodology for predicting the SEU susceptibility of a standard-cell D-latch using an alpha-particle sensitive SRAM, SPICE critical charge simulation results, and alpha-particle interaction physics. Measurements were made on a 1.6-{mu}m n-well CMOS 4k-bit test SRAM irradiated with an Am-241 alpha-particle source. A collection depth of 6.09 {mu}m was determined using these results and TRIM computer code. Using this collection depth and SPICE derived critical charge results on the latch design, an LET threshold of 34 Mev cm{sup 2}/mg was predicted. Heavy ion tests were then performed on the latch and an LET threshold of 41 MeV cm{sup 2}/mg was determined.

Blaes, B.R.; Soli, G.A.; Buehler, M.G. (Jet Propulsion Lab., Pasadena, CA (United States))

1991-12-01

242

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

243

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

PubMed Central

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

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

2012-01-01

244

A 244Cm irradiator for protracted exposure of cultured Mammalian cells with alpha particles.  

PubMed

A 244Cm alpha-particle irradiator was designed and constructed for radiobiological studies where protracted exposure at a low dose rate of cultured mammalian cells is required. It allows irradiation of a cell monolayer attached to the Mylar bottom of a specially designed Petri dish of 56 mm diameter (approximately 25 cm(2) area). The irradiator is based on a 20-mm-diameter stainless steel chamber containing a 148 kBq 244Cm source. The chamber, flushed with helium gas at a pressure kept slightly above the external pressure, is inserted into a cell incubator where temperature and CO2 concentration are controlled. Spectrometric and dosimetric characterization of the irradiator was carried out by means of an ion-implanted-silicon charged-particle detector, CR39 detectors, and Monte Carlo simulations with the TRIM code. Average LET of particles incident on the cells at the center of the Petri dish was evaluated to be 120 keV microm(-1) at 59 mm from the source, and the average dose rate was 5.69 x 10 Gy s(-1), with +12% and -8% variations at the center and the edge, respectively. The irradiator has been successfully tested and used for several experiments involving 16-d exposure of human fibroblasts monolayers. PMID:16340609

Esposito, G; Belli, M; Simone, G; Sorrentino, E; Tabocchini, M A

2006-01-01

245

Detection of alpha radiation in a beta radiation field  

DOEpatents

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

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

2001-01-01

246

Complex aberrations in lymphocytes exposed to mixed beams of (241)Am alpha particles and X-rays.  

PubMed

Modern radiotherapy treatment modalities are associated with undesired out-of-field exposure to complex mixed beams of high and low energy transfer (LET) radiation that can give rise to secondary cancers. The biological effectiveness of mixed beams is not known. The aim of the investigation was the analysis of chromosomal damage in human peripheral blood lymphocytes (PBL) exposed to a mixed beam of X-rays and alpha particles. Using a dedicated exposure facility PBL were exposed to increasing doses of alpha particles (from (241)Am), X-rays and a mixture of both. Chromosomal aberrations were analysed in chromosomes 2, 8 and 14 using fluorescence in situ hybridisation. The found and expected frequencies of simple and complex aberrations were compared. Simple aberrations showed linear dose-response relationships with doses. A higher than expected frequency of simple aberrations was only observed after the highest mixed beam dose. A linear-quadratic dose response curve for complex aberrations was observed after mixed-beam exposure. Higher than expected frequencies of complex aberrations were observed for the two highest doses. Both the linear-quadratic dose-response relationship and the calculation of expected frequencies show that exposure of PBL to mixed beams of high and low LET radiation leads to a higher than expected frequency of complex-type aberrations. Because chromosomal changes are associated with cancer induction this result may imply that the cancer risk of exposure to mixed beams in radiation oncology may be higher than expected based on the additive action of the individual dose components. PMID:23669292

Staaf, Elina; Deperas-Kaminska, Marta; Brehwens, Karl; Haghdoost, Siamak; Czub, Joanna; Wojcik, Andrzej

2013-08-30

247

Analysis of ⁹°Sr and alpha-particle emitters on air filters and swipe samples using a liquid scintillation counter with alpha\\/beta discrimination  

Microsoft Academic Search

The capabilities of a Quantulus{trademark} model 1220 Liquid Scintillation Counter (LSC) for rapidly analyzing alpha-particle emitters and ⁹°Sr on air filters and swipe samples have been studied. Counting conditions were established and the instrument was calibrated using quench standards of ⁹°Sr\\/Y and ²⁴¹Am prepared on membrane filters. A LOTUS{trademark} template was developed to analyze the spectra. The data were used

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

1998-01-01

248

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

249

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

250

149Sm(n,alpha)146Nd cross sections in the MeV energy region  

SciTech Connect

We have measured the {sup 149}Sm(n,{alpha}){sup 146}Nd cross section at 4.5, 5.0, 5.5, 6.0, and 6.5 MeV. Measurements were performed at the 4.5 MV Van de Graaff accelerator of Peking University with monoenergetic neutrons produced via the {sup 2}H(d,n){sup 3}He reaction using a deuterium gas target. Alpha particles were detected with a double-section gridded ionization chamber having two back-to-back {sup 149}Sm{sub 2}O{sub 3} samples attached to the common cathode. Absolute neutron flux was measured using a small {sup 238}U fission chamber and monitored by a BF{sub 3} long counter. These are the first reported cross sections for this reaction at these energies, except at 6.0 eV, where our new data are in good agreement with our earlier result. The present results help to much better constrain the {sup 149}Sm(n,{alpha}){sup 146}Nd cross section in a region where its energy dependence is changing fairly rapidly and there are large differences between evaluated nuclear data libraries.

Zhang, Guohui [Peking University; Gledenov, Yu. M. [Joint Institute for Nuclear Research, Dubna, Russia; Khuukhenkhuu, G [National University of Mongolia; Sedysheva, M. V. [Joint Institute for Nuclear Research, Dubna, Russia; Szalanski, P. [University of Lodz; Koehler, Paul Edward [ORNL; Voronov, Yu. N. [Joint Institute for Nuclear Research, Dubna, Russia; Liu, Jiaming [Peking University; Liu, Xiang [Peking University; Han, Jinhua [Peking University; Chen, Jinxiang [Peking University

2011-01-01

251

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

252

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

253

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

SciTech Connect

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

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

1995-07-01

254

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

SciTech Connect

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

Bae, Y.K.

1982-08-01

255

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

E-print Network

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

G. K. Nie

2006-03-22

256

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

257

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

SciTech Connect

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

Dong Jianmin [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Institute for Theoretical Physics, Justus-Liebig-University, D-35392 Giessen (Germany); Zuo Wei [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Scheid, Werner [Institute for Theoretical Physics, Justus-Liebig-University, D-35392 Giessen (Germany)

2011-07-01

258

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

SciTech Connect

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

Benhabiles-Mezhoud, H.; Kiener, J.; Thibaud, J.-P.; Tatischeff, V.; Deloncle, I.; Coc, A.; Duprat, J.; Hamadache, C.; Lefebvre-Schuhl, A.; Dalouzy, J.-C.; Grancey, F. de; Oliveira, F. de; Dayras, F.; Sereville, N. de; Pellegriti, M.-G.; Lamia, L.; Ouichaoui, S. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), CNRS-IN2P3 et Universite Paris-Sud, 91405 Orsay Campus (France); GANIL, CEA/DSM-CNRS/IN2P3, Caen (France); CEA, LIST, 91191 Gif-sur-Yvette CEDEX (France); Institut de Physique Nucleaire (IPN), CNRS-IN2P3 et Universite Paris-Sud, 91400 Orsay (France); INFN--Laboratori Nazionali del Sud, via S. Sofia 62, 95125 Catania (Italy); USTHB, Faculte de Physique, Boite Postale 32, El-Alia, 16111 Bab Ezzouar, Algiers (Algeria)

2011-02-15

259

Reconstructing the dark energy equation of state with varying alpha  

E-print Network

The possibility of reconstructing the dark energy equation of state from variations in the fine structure constant is investigated for a class of models where the quintessence field is non-minimally coupled to the electromagnetic field. For given classes of couplings and quintessence interaction potentials, it is typically found that variations in alpha would need to be measured to within an accuracy of at least $5 \\times 10^{-7}$ to obtain a reconstructed equation of state with less than a twenty per cent deviation from the true equation of state between redshifts 0 and 3. In this case, it is argued that the sign of the first derivative of the equation of state can be uncovered from the reconstruction, thus providing unique information on how the universe developed into its present dark energy dominated phase independent of high redshift surveys. Such information would complement future observations anticipated from the Supernova Acceleration Probe.

N. J. Nunes; James E. Lidsey

2003-10-30

260

Collisionless current generation in the center of the tokamak plasma by an isotropic source of {alpha}-particles  

SciTech Connect

The density of the noninductive current generated due to collisionless motion of {alpha}-particles in the tokamak magnetic field is calculated. The analysis is based on fully three-dimensional calculations of charged particle trajectories without simplifying assumptions typical for drift and neoclassical approaches. The current is calculated over the entire cross section of the plasma column, including the magnetic axis. It is shown that the current density is not a function of a magnetic surface and is strongly polarized over the poloidal angle. The current density distribution in the tokamak poloidal cross section is obtained, and the current density as a function of the safety factor, the tokamak aspect ratio, and the ratio of the particle Larmor radius on the axis to the tokamak minor radius is determined. It is shown that, when the source of {alpha}-particles is spatially nonuniform, the current density in the center of the tokamak is nonzero due to asymmetry of the phase-space boundary between trapped and passing particles. The current density scaling in the tokamak center differs from the known approximations for the bootstrap current and is sensitive to the spatial distribution of {alpha}-particles.

Ilgisonis, V. I.; Sorokina, E. A.; Yurchenko, E. I. [Russian Research Centre Kurchatov Institute (Russian Federation)

2010-01-15

261

Determining the impact of alpha-particle-emitting contamination from the Fukushima Daiichi disaster on Japanese manufacturing sites  

Microsoft Academic Search

We briefly review nuclear reactor operation from the point of view of the major radioactive contaminants formed and consider how these were released and dispersed into the air, water, and soil around Fukushima. The risk of contamination from alpha-particle-emitting uranium and plutonium isotopes at semiconductor manufacturing sites in Japan is considered from theoretical aspects. We report the results of low

Robert C. Baumann

2011-01-01

262

Low energy particles in the magnetosphere  

Microsoft Academic Search

Consideration is given to the low-energy (less than 100 eV) hybrid plasma particle population in the earth's magnetosphere. Satellite observations of a cold plasma in the outer plasmasphere and plasmatrough at temperatures greater than expected for plasma filling by upward flowing ionization are noted, and results of ATS-6 measurements of cold particle angular and density distributions are presented which reveal

C. R. Chappell

1982-01-01

263

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

SciTech Connect

We reported previously that the homologous recombinational repair (HRR)-deficient Chinese hamster mutant cell line irs3 (deficient in the Rad51 paralog Rad51C) showed only a 50% spontaneous frequency of sister chromatid exchange (SCE) as compared to parental wild-type V79 cells. Furthermore, when irradiated with very low doses of alpha particles, SCEs were not induced in irs3 cells, as compared to a prominent bystander effect observed in V79 cells (Nagasawa et al., Radiat. Res. 164, 141-147, 2005). In the present study, we examined additional Chinese hamster cell lines deficient in the Rad51 paralogs Rad51C, Rad51D, Xrcc2, and Xrcc3 as well as another essential HRR protein, Brca2. Spontaneous SCE frequencies in non-irradiated wild-type cell lines CHO, AA8 and V79 were 0.33 SCE/chromosome, whereas two Rad51C-deficient cell lines showed only 0.16 SCE/chromosome. Spontaneous SCE frequencies in cell lines defective in Rad51D, Xrcc2, Xrcc3, and Brca2 ranged from 0.23-0.33 SCE/chromosome, 0-30% lower than wild-type cells. SCEs were induced significantly 20-50% above spontaneous levels in wild-type cells exposed to a mean dose of 1.3 mGy of alpha particles (<1% of nuclei traversed by an alpha particle). However, induction of SCEs above spontaneous levels was minimal or absent after {alpha}-particle irradiation in all of the HRR-deficient cell lines. These data suggest that Brca2 and the Rad51 paralogs contribute to DNA damage repair processes induced in bystander cells (presumably oxidative damage repair in S-phase cells) following irradiation with very low doses of alpha particles.

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

2007-10-26

264

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

SciTech Connect

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

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

2008-01-15

265

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

SciTech Connect

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

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

2009-01-01

266

Alpha-Calcitonin Gene-Related Peptide Can Reverse The Catabolic Influence Of UHMWPE Particles On RANKL Expression In Primary Human Osteoblasts  

PubMed Central

Background and purpose: A linkage between the neurotransmitter alpha-calcitonin gene-related peptide (alpha-CGRP) and particle-induced osteolysis has been shown previously. The suggested osteoprotective influence of alpha-CGRP on the catabolic effects of ultra-high molecular weight polyethylene (UHMWPE) particles is analyzed in this study in primary human osteoblasts. Methods: Primary human osteoblasts were stimulated by UHMWPE particles (cell/particle ratios 1:100 and 1:500) and different doses of alpha-CGRP (10-7 M, 10-9 M, 10-11 M). Receptor activator of nuclear factor-?B ligand (RANKL) and osteoprotegerin (OPG) mRNA expression and protein levels were measured by RT-PCR and Western blot. Results: Particle stimulation leads to a significant dose-dependent increase of RANKL mRNA in both cell-particle ratios and a significant down-regulation of OPG mRNA in cell-particle concentrations of 1:500. A significant depression of alkaline phosphatase was found due to particle stimulation. Alpha-CGRP in all tested concentrations showed a significant depressive effect on the expression of RANKL mRNA in primary human osteoblasts under particle stimulation. Comparable reactions of RANKL protein levels due to particles and alpha-CGRP were found by Western blot analysis. In cell-particle ratios of 1:100 after 24 hours the osteoprotective influence of alpha-CGRP reversed the catabolic effects of particles on the RANKL expression. Interpretation: The in-vivo use of alpha-CGRP, which leads to down-regulated RANKL in-vitro, might inhibit the catabolic effect of particles in conditions of particle induced osteolysis. PMID:20877694

Kauther, Max D.; Xu, Jie; Wedemeyer, Christian

2010-01-01

267

High energy particles and quanta in astrophysics  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

268

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

269

Relativistic effects in energy extraction from alpha particles A. Fruchtman  

E-print Network

for Technological Education Holon, Holon, Israel N. J. Fisch and E. J. Valeo Princeton Plasma Physics Laboratory and one lower frequency wave.18 The present work is motivated by the possibility of ac- complishing

270

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

271

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

SciTech Connect

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

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

2008-09-15

272

High-energy solar-particle events  

Microsoft Academic Search

Recent high-energy solar-particle events have been illustrated and described individually. The manner in which the observations have been used to develop and test concepts of the hydromagnetic behaviour of the solar plasma in space has been outlined. Some of the events have been analyzed in more detail than hitherto. The results seem to support the concept that the magnetic field

Hugh Carmichael

1962-01-01

273

Energy and particle fluxes in PLD processes  

NASA Astrophysics Data System (ADS)

The main advantage of the PLD process consists in thin film deposition by a plasma flow with high kinetic particle energy. The energy and mass balance of the particle beam formation generated by laser ablation is the key for qualitative and quantitative understanding of the fundamental processes. Thermal evaporation and inverse bremsstrahlung will be discussed in this context. For experimental estimation of the energy and mass balance several in-situ measuring systems have been installed, in particular the ballistic microbalance and electrical probes. As a representative example the ablation of aluminium and carbon by pulsed Nd:YAG laser irradiation in the intensity range of 10 8 W/cm 2 is presented in more detail.

Lenk, A.; Schultrich, B.; Witke, T.; Weiß, H.-J.

1997-02-01

274

Characterization of an Associated Particle Neutron Generator with ZnO:Ga Alpha-Detector and Active Focusing  

SciTech Connect

A deuterium-tritium (DT) associated particle neutron generator (APNG) with active focusing has been operated using an alpha particle detector made of a ZnO:Ga phosphor with decay time of approximately 1 ns. The APNG is capable of producing 109 neutrons per second. The DT beam spot diameter was adjusted and measured from 7 mm to 2.1 mm with the possibility of achieving 1 mm subject to the removal of a safety interlock protecting the APNG tritiated target. In addition, the alpha detector was found to have a detection efficiency of 88% and sub-nanosecond time resolution (<0.7 ns) using a Burle 8850 bialkali photocathode. Lastly, the neutron beam was obstructed using various amounts of lead shielding to study the generator's imaging contrast capability for neutron radiography. The APNG provides high-rate capability and a large solid angle with acceptance of 8%.

McConchie, Seth M [ORNL; Mihalczo, John T [ORNL

2008-01-01

275

Relative drifts and temperature anisotropies of protons and $\\alpha$ particles in the expanding solar wind -- 2.5D hybrid simulations  

E-print Network

We perform 2.5D hybrid simulations to investigate the origin and evolution of relative drift speeds between protons and $\\alpha$ particles in the collisionless turbulent low-$\\beta$ solar wind plasma. We study the generation of differential streaming by wave-particle interactions and absorption of turbulent wave spectra. Next we focus on the role of the relative drifts for the turbulent heating and acceleration of ions in the collisionless fast solar wind streams. The energy source is given by an initial broad-band spectrum of parallel propagating Alfv\\'en-cyclotron waves, which co-exists with the plasma and is self-consistently coupled to the perpendicular ion bulk velocities. We include the effect of a gradual solar wind expansion, which cools and decelerates the minor ions. This paper for the first time considers the combined effect of self-consistently initialized dispersive turbulent Alfv\\'enic spectra with differentially streaming protons and $\\alpha$ particles in the expanding solar wind outflows withi...

Maneva, Y G; Viñas, A

2014-01-01

276

Complementary Measurement of Thermal Architecture of NbSi TES with Alpha Particle and Complex Impedance  

NASA Astrophysics Data System (ADS)

As shown by the Planck mission (Planck Collaboration. Astronomy and astrophysics. arXiv1303.5071P, 2013), background limited bolometers in a space environment are very sensitive to high energy particles. In order to not degrade their sensitivity, it is necessary to reduce this unwanted signal. To achieve this goal, a good understanding of the detector's thermal architecture is mandatory. To investigate this question, we used an particle source in front of our niobium silicon (NbSi) alloy Transition edge sensors (TES). The number of time constants required to fit the data and the way these time constants behave as we change the bias power gave us a good insight on the TES thermal architecture. Indeed we expect a decrease of the detector time constant due to the electro-thermal feedback properties. We will first present some standard characterizations of NbSi TES using a simple thermal model and how they indicate the presence of multiple thermal decouplings. Then we will show the results of the particles measurements and how we used them to build our thermal model for Complex Impedance fitting. All this work has been done for the QUBIC experiment, a B-modes instrument.

Martino, J.; Miniussi, A.; Piat, M.; Prêle, D.; Pajot, F.; Decourcelle, T.; Voisin, F.; Bélier, B.; Coron, N.; Ghribi, A.; Marnieros, S.; Perbost, C.

2014-08-01

277

Critical Exponents and Particle Multiplicity Distributions in High Energy Collisions  

E-print Network

Data from the L3, Tasso, Opal and Delphi collaborations are analyzed in terms of a statistical model of high energy collisions. The model contains a power law critical exponent tau and Levy index alpha. These data are used to study values of tau and alpha. The very high multiplicity events in L3, Opal and Delphi are consistent with a model based on a Feynman-Wilson gas which has a tail exponent tau=3/2 and alpha=1/2.

A. Z. Mekjian; S. J. Lee; T. Csorgo

2007-11-28

278

Safety-factor profile dependence of the diamagnetic effect on fusion alpha particle losses in a rippled tokamak  

NASA Astrophysics Data System (ADS)

The finite number of the toroidal field coils (TFCs) breaks the symmetry of tokamak plasmas. The non-axisymmetric field from TFCs is called toroidal field (TF) ripple. Because of TF ripples, energetic ion losses are increased in tokamak plasmas. With increasing the beta value, the plasma changes the magnetic field structures and energetic ion losses. The diamagnetic effect due to the poloidal plasma current is one of the most important finite beta effects. In this study, we clarified how the diamagnetic effect and the fusion alpha particle losses are changed by the safety-factor-profile. Keeping the plasma-pressure profile and the shape of plasma boundary, the MHD equilibrium was solved by the VMEC code for different safety-factor profiles. To investigate the diamagnetic effect, we created the two kinds of field structures: the MHD equilibrium fields with and without the toroidal field due to the plasma current. Trajectories of 10,000 fusion alpha particles were followed in each MHD equilibrium field with different safety-factor profile. By comparing the loss rates, the safety-factor dependence of the diamagnetic effect on the fusion alpha particle losses was clarified in this study.

Bunno, Michinao; Nakamura, Yuji; Suzuki, Yasuhiro; Shinohara, Koji; Matsunaga, Go; Tani, Keiji

2012-10-01

279

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

280

High Energy Particles in the Solar Corona  

E-print Network

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

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

2008-04-16

281

Review of lattice results concerning low energy particle physics  

E-print Network

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

Sinya Aoki; Yasumichi Aoki; Claude Bernard; Tom Blum; Gilberto Colangelo; Michele Della Morte; Stephan Dürr; Aida X. El Khadra; Hidenori Fukaya; Roger Horsley; Andreas Jüttner; Takeshi Kaneko; Jack Laiho; Laurent Lellouch; Heinrich Leutwyler; Vittorio Lubicz; Enrico Lunghi; Silvia Necco; Tetsuya Onogi; Carlos Pena; Christopher T. Sachrajda; Stephen R. Sharpe; Silvano Simula; Rainer Sommer; Ruth S. Van de Water; Anastassios Vladikas; Urs Wenger; Hartmut Wittig

2013-10-31

282

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

SciTech Connect

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

Dong Tiekuang [Department of Physics, Nanjing University, Nanjing 210008 (China); Faculty of Information Technology, Macau University of Science and Technology, Macau 999078 (China); Ren Zhongzhou [Department of Physics, Nanjing University, Nanjing 210008 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy-Ion Accelerator, Lanzhou 730000 (China)

2010-09-15

283

An improved measuremebts of alphaS (MZ0) using energy correlations with the OPAL detector at LEP  

Microsoft Academic Search

We report on an improved measurement of the value of the strong coupling constant sigmas at the Z0 peak, using the asymmetry of the energy-energy correlation function. The analysis, based on second-order perturbation theory and a data sample of about 145000 multihadronic Z0 decays, yields alphas(Mz0 = 0.118+\\/-0.001(stat.)+\\/-0.003(exp.syst.)-0.004+0.0009 (theor. syst.), where the theoretical systematic error accounts for uncertainties due to

P. D. Acton; G. Alexander; J. Allison; P. P. Allport; K. J. Anderson; S. Arcelli; P. Ashton; A. Astbury; D. Axen; G. Azuelos; G. A. Bahan; J. T. M. Baines; A. H. Ball; J. Banks; G. J. Barker; R. J. Barlow; J. R. Batley; G. Beaudoin; A. Beck; J. Becker; T. Behnke; K. W. Bell; G. Bella; P. Berlich; S. Bethke; O. Biebel; U. Binder; I. J. Bloodworth; P. Bock; B. Boden; H. M. Bosch; S. Bougerolle; B. B. Brabson; H. Breuker; R. M. Brown; R. Brun; A. Buijs; H. J. Burckhart; P. Capiluppi; R. K. Carnegie; A. A. Carter; J. R. Carter; C. Y. Chang; D. G. Charlton; P. E. L. Clarke; I. Cohen; W. J. Collins; J. E. Conboy; M. Cooper; M. Couch; M. Coupland; M. Cuffiani; S. Dado; G. M. Dallavalle; S. de Jong; P. Debu; L. A. del Pozo; M. M. Dennino; A. Dieckmann; M. Dittmar; M. S. Dixit; E. Duchovni; G. Duckeck; I. P. Duerdoth; D. J. P. Dumas; G. Eckerlin; P. A. Elcombe; P. G. Estabrooks; E. Etzion; F. Fabbri; M. Fincke-Keeler; H. M. Fischer; D. G. Fong; C. Fukunaga; A. Gaidot; O. Ganel; J. W. Gary; J. Gascon; R. F. McGowan; N. I. Geddes; C. Geich-Gimbel; S. W. Gensler; F. X. Gentit; G. Giacomelli; V. Gibson; W. R. Gibson; J. D. Gillies; J. Goldberg; M. J. Goodrick; W. Gorn; C. Grandi; F. C. Grant; J. Hagemann; G. G. Hanson; M. Hansroul; C. K. Hargrove; P. F. Harrison; J. Hart; P. M. Hattersley; M. Hauschild; C. M. Hawkes; E. Heflin; R. J. Hemingway; R. D. Heuer; J. C. Hill; S. J. Hillier; D. A. Hinshaw; C. Ho; J. D. Hobbs; P. R. Hobson; D. Hochman; B. Holl; R. J. Homer; A. K. Honma; S. R. Hou; C. P. Howarth; R. E. Hughes-Jones; R. Humbert; P. Igo-Kemenes; H. Ihssen; D. C. Imrie; A. C. Janissen; A. Jawahery; P. W. Jeffreys; H. Jeremie; M. Jimack; M. Jobes; R. W. L. Jones; P. Jovanovic; D. Karlen; K. Kawagoe; T. Kawamoto; R. K. Keeler; R. G. Kellogg; B. W. Kennedy; C. Kleinwort; D. E. Klem; T. Kobayashi; T. P. Kokott; S. Komamiya; L. Köpke; J. F. Kral; R. Kowalewski; H. Kreutzmann; J. von Krogh; J. Kroll; M. Kuwano; P. Kyberd; G. D. Lafferty; F. Lamarche; W. J. Larson; J. G. Layter; P. Le Du; P. Leblanc; A. M. Lee; M. H. Lehto; D. Lellouch; P. Lennert; C. Leroy; J. Letts; S. Levegrün; L. Levinson; S. L. Lloyd; F. K. Loebinger; J. M. Lorah; B. Lorazo; M. J. Losty; X. C. Lou; J. Ludwig; M. Mannelli; S. Marcellini; G. Maringer; A. J. Martin; J. P. Martin; T. Mashimo; P. Mättig; U. Maur; J. McKenna; T. J. McMahon; J. R. McNutt; F. Meijers; D. Menszner; F. S. Merritt; H. Mes; A. Michelini; R. P. Middleton; G. Mikenberg; J. Mildenberger; D. J. Miller; R. Mir; W. Mohr; C. Moisan; A. Montanari; T. Mori; M. W. Moss; T. Mouthuy; B. Nellen; H. H. Nguyen; M. Nozaki; S. W. O'Neale; B. P. O'Neill; F. G. Oakham; F. Odorici; M. Ogg; H. O. Ogren; H. Oh; C. J. Oram; M. J. Oreglia; S. Orito; J. P. Pansart; B. Panzer-Steindel; P. Paschievici; G. N. Patrick; S. J. Pawley; P. Pfister; J. E. Pilcher; J. L. Pinfold; D. Pitman; D. E. Plane; P. Poffenberger; B. Poli; A. Pouladdej; E. Prebys; T. W. Pritchard; H. Przysiezniak; G. Quast; M. W. Redmond; D. L. Rees; K. Riles; S. A. Robins; D. Robinson; A. Rollnik; J. M. Roney; E. Ros; S. Rossberg; A. M. Rossi; M. Rosvick; P. Routenburg; K. Runge; O. Runolfsson; D. R. Rust; S. Sanghera; M. Sasaki; A. D. Schaile; O. Schaile; W. Schappert; P. Scharff-Hansen; P. Schenk; H. von der Schmitt; S. Schreiber; J. Schweining; W. G. Scott; M. Settles; B. C. Shen; P. Sherwood; R. Shypit; A. Simon; P. Singh; G. P. Siroli; A. Skuja; A. M. Smith; T. J. Smith; G. A. Snow; R. Sobie; R. W. Springer; M. Sproston; K. Stephens; H. E. Stier; R. Ströhmer; D. Strom; H. Takeda; T. Takeshita; P. Taras; S. Tarem; P. Teixeira-Dias; N. J. Thackray; G. Transtromer; T. Tsukamoto; M. F. Turner; G. Tysarczyk-Niemeyer; D. van den Plas; R. van Kooten; G. J. Vandalen; G. Vasseur; C. J. Virtue; A. Wagner; C. Wahl; J. P. Walker; C. P. Ward; D. R. Ward; P. M. Watkins; A. T. Watson; N. K. Watson; M. Weber; P. Weber; S. Weisz; P. S. Wells; N. Wermes; M. Weymann; M. A. Whalley; G. W. Wilson; J. A. Wilson; I. Wingerter; V.-H. Winterer; N. C. Wood; S. Wotton; T. R. Wyatt; R. Yaari; Y. Yang; G. Yekutieli; M. Yurko; I. Zacharov; W. Zeuner; G. T. Zorn

1992-01-01

284

The Apollo Alpha Spectrometer.  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

285

Influence of alpha particle bombardment and postannealing on photoluminescence from GaAs\\/Al{sub 0.35}Ga{sub 0.65}As multiple quantum wells  

Microsoft Academic Search

Multiple quantum well (MQW) samples grown by the molecular beam epitaxy method were irradiated by alpha particles from isotope ²³⁹Pu. The photoluminescence (PL) spectra and PL integrated intensity dependencies are presented at various alpha particle fluences, up to 10¹¹cm⁻². The experimental results are in agreement with a model which assumes that point centers (residual impurities and point defects introduced during

J. Kundrotas; A. Dargys; G. Valusis; S. Asmontas; K. Kohler; C. Leroy

2001-01-01

286

The thermoluminescence response of doped SiO2 optical fibres subjected to alpha-particle irradiation.  

PubMed

Ion beams are used in radiotherapy to deliver a more precise dose to the target volume while minimizing dose to the surrounding healthy tissue. For optimum dose monitoring in ion-beam therapy, it is essential to be able to measure the delivered dose with a sensitivity, spatial resolution and dynamic range that is sufficient to meet the demands of the various therapy situations. Optical fibres have been demonstrated by this group to show promising thermoluminescence properties with respect to photon, electron and proton irradiation. In particular, and also given the flexibility and small size of optical fibre cores, for example 125.0+/-0.1 microm for the Al- and Ge-doped fibres used in this study, these fibres have the potential to fulfill the above requirements. This study investigates the thermoluminescence dosimetric characteristics of variously doped SiO(2) optical fibres irradiated with alpha particles from (241)Am. Following subtraction of the gamma contribution from the above source, the thermoluminescence characteristics of variously doped SiO(2) optical fibres have been compared with that of TLD-100 rods. The irradiations were performed in a bell jar. Of related potential significance is the effective atomic number, Z(eff) of the fibre, modifying measured dose from that deposited in tissues; in the present work, a scanning electron microscope and associated energy dispersive X-ray spectroscopy facility have been used to provide evaluation of Z(eff). For Ge-doped fibres, the effective atomic numbers value was 11.4, the equivalent value for Al-doped fibres was 12.3. This paper further presents results on dose response and the glow curves obtained. The results obtained indicate there to be good potential for use of variously doped SiO(2) optical fibres in measuring ion-beam doses in radiotherapeutic applications. PMID:18693114

Ramli, Ahmad Termizi; Bradley, D A; Hashim, Suhairul; Wagiran, Husin

2009-03-01

287

Method and apparatus for generating low energy nuclear particles  

DOEpatents

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

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

1999-02-09

288

Method and apparatus for generating low energy nuclear particles  

DOEpatents

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

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

1999-02-09

289

Reaction cross sections of intermediate energy ? particles within a relativistic optical model  

NASA Astrophysics Data System (ADS)

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

Ait-Tahar, S.; Nedjadi, Y.

1995-07-01

290

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

SciTech Connect

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

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

2012-09-04

291

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

SciTech Connect

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

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

1983-01-01

292

Operant responding following exposure to HZE particles and its relationship to particle energy and linear energy transfer  

NASA Astrophysics Data System (ADS)

On exploratory class missions astronauts will be exposed to a variety of heavy particles (HZE particles) which differ in terms of particle energy and particle linear energy transfer. The present experiments were designed to evaluate how these physical characteristics of different particles affect cognitive performance, specifically operant responding. Following exposure to 28Si, 48Ti, 12C and 16O particles at the NASA Space Radiation Laboratory rats were tested for their ability to respond appropriately to changes in reinforcement schedules using an operant task. The results showed that the effectiveness of different particles in disrupting cognitive performance, defined as the lowest dose that produced a performance decrement, varied as a function of the energy of the specific particle: for comparisons between different energies of the same particle ( e.g., 56Fe) the effectiveness of the particle was directly proportional to particle linear energy transfer, whereas for comparisons between different particles ( e.g., 56Fe and 16O) effectiveness was inversely proportional to particle linear energy transfer. The results are discussed in terms of the mechanisms that influence the effectiveness of different particles and energies and in terms of their implications for analyzing the possible risks to astronauts of decrements in cognitive performance following exposure to HZE particles on long-duration exploratory class missions.

Rabin, Bernard M.; Carrihill-Knoll, Kirsty L.; Shukitt-Hale, Barbara

2011-07-01

293

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

SciTech Connect

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

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

2011-01-01

294

LET-dependent bystander effects caused by irradiation of human prostate carcinoma cells with X rays or alpha particles.  

PubMed

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

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

2008-10-01

295

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

PubMed

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, He(0) beam was successfully produced after the flight in the drift-tube through the auto-electron-detachment process from He(-) to He(0). A neutral beam detector using a pyroelectric device was also developed to measure He(0) beam intensity. The metastable component in the neutral helium beam was found to be less than 2%. PMID:22380272

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

2012-02-01

296

Prerainbow Oscillations in $^3$He Scattering from the Hoyle State of $^{12}$c and Alpha Particle Condensation  

E-print Network

$^3$He+$^{12}$C scattering is studied in a coupled channel method by using a double folding model with microscopic wave functions of $^{12}$C. Experimental angular distributions in elastic and inelastic scattering to the $2^+$ (4.44 MeV), 0$^+_2$ (7.65 MeV) and 3$^-$ (9.63 MeV) states of $^{12}$C are well reproduced. It is found that the Airy minimum of the prerainbow oscillations for the Hoyle state is considerably shifted to a larger angle due to its dilute density distribution compared with that of the normal ground state in agreement with the idea of $\\alpha$ particle condensation.

S. Ohkubo; Y. Hirabayashi

2011-02-11

297

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

298

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

E-print Network

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

G. K. Nie

2011-06-19

299

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

PubMed Central

Alpha- (?-) particle radiation exposure has been linked to the development of lung cancer and has been identified as a radiation type likely to be employed in radiological dispersal devices. Currently, there exists a knowledge gap concerning cytokine modulations associated with exposure to ?-particles. Bio-plex technology was employed to investigate changes in proinflammatory cytokines in two human-derived cell lines. Cells were irradiated at a dose of 1.5?Gy to either ?-particles or X-rays at equivalent dose rates. The two cell lines exhibited a unique pattern of cytokine expression and the response varied with radiation type. Of the 27 cytokines assessed, only vascular endothelin growth factor (VEGF) was observed to be modulated in both cell lines solely after ?-particle exposure, and the expression of VEGF was shown to be dose responsive. These results suggest that certain proinflammatory cytokines may be involved in the biological effects related to ?- particle exposure and the responses are cell type and radiation type specific. PMID:22619631

Chauhan, Vinita; Howland, Matthew; Wilkins, Ruth

2012-01-01

300

Particle motion and energy distribution in tumbling ball mills  

Microsoft Academic Search

The charge flow characteristics and the local energy distributions have a profound influence on the comminution behavior in tumbling ball mills. Computer simulation using a particle dynamics method offers a viable approach for investigating the flow and energy distribution characteristics within tumbling particulate media. In particle dynamics method, particulate systems are simulated by tracking particles as they move in response

Anil Misra; Josephine Cheung

1999-01-01

301

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

NASA Astrophysics Data System (ADS)

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

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

302

Detachment energies of spheroidal particles from fluid-fluid interfaces  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

303

Detachment Energies of Spheroidal Particles from Fluid-Fluid Interfaces  

E-print Network

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

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

2014-07-01

304

Co-Cr-Mo Alloy Particles Induce Tumor Necrosis Factor Alpha Production in MLO-Y4 Osteocytes: A Role for Osteocytes in Particle Induced Inflammation  

PubMed Central

Wear debris-induced osteolysis is purportedly the limiting problem affecting the long term results of joint arthroplasty. Pathogenic effects of wear debris in peri-implant cells such as macrophages, osteoblasts and osteoclasts have been well studied. In contrast, the affects of wear-debris on osteocytes, which make up over 90% of all bone cells, remains unknown. We hypothesized that metal implant debris can induce the proinflammatory response in osteocytes. This study demonstrated the effects of cobalt-chromium-molybdenum alloy (Co-Cr-Mo) particles on a well-characterized MLO-Y4 osteocyte cell line. Co-Cr-Mo alloy particle treatment significantly (p<0.05) up-regulated tumor necrosis factor alpha (TNF?) gene expression after 3 and 6 hr and TNF? protein production after 24 hr, but down-regulated interleukin-6 (IL-6) gene expression after 6 hr. Co-Cr-Mo alloy particle treatment also induced osteocyte apoptosis after 24 hr. This apoptotic effect was partially (40%) dependent on TNF?. Therefore, our results suggest that osteocytes play a role in particle induced inflammation and bone resorption following total hip arthroplasty by inducing pro-inflammatory cytokines and inducing osteocyte apoptosis. PMID:19497395

Kanaji, Arihiko; Caicedo, Marco S.; Virdi, Amarjit S.; Sumner, D. Rick; Hallab, Nadim J.; Sena, Kotaro

2009-01-01

305

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

SciTech Connect

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

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

1992-11-01

306

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

307

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

308

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

NASA Astrophysics Data System (ADS)

Southern Methodist University houses one of five existing commercially available UltraLo 1800 production model alpha counters made by XIA LLC. The instrument has an electron drift chamber with a 707 cm2 or 1800 cm2 counting region which is determined by selecting the inner electrode size. The SMU team operating this device is part of the SuperCDMS screening working group, and uses the alpha counter to study the background rates from the decay of radon in materials used to construct the SuperCDMS experiment. We have studied four acrylic samples obtained from the MiniCLEAN direct dark matter search with the XIA instrument demonstrating its utility in low background experiments by investigating the plate-out of 210Pb and comparing the effectiveness of cleaning procedures in removing 222Rn progenies from the samples.

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

2013-08-01

309

Alpha-particle resonances and clusters in 32S, 34S, 36Ar and 40Ca  

NASA Astrophysics Data System (ADS)

Recently the nuclei 32S, 34S and 40Ca have been examined in detail from an alpha-cluster point of view, adding to previous knowledge on cluster structures in medium light nuclei. But as often in science, new results give rise to more new questions than old ones they answer. In the text below some of these open questions and suggestions for future work are stated.

Norrby, Markus

2013-04-01

310

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

311

Energy transport in alpha-helical protein models: One-strand versus three-strand systems  

Microsoft Academic Search

We study the transport of vibrational energy in alpha-helix forms of proteins within the frame of a steric Davydov model. Our main objective is the comparison of the localization and transport properties of the widely used one-strand approximation of the alpha helix associated with a linear chain of hydrogen bonded peptide groups and the complete three-dimensional helical system consisting of

Dirk Hennig

2002-01-01

312

Alpha-particle carcinogenesis in Thorotrast patients: epidemiology, dosimetry, pathology, and molecular analysis.  

PubMed

We studied the alpha-radiation risks in patients who received injections of Thorotrast, an X-ray contrast medium used in Europe, Japan, and the United States from 1930 to 1955. Thorotrast was composed of thorium dioxide (ThO2) and Th-232, a naturally occurring radionuclide. Because the physical half-life of ThO2 is 14 billion years and Thorotrast is hardly eliminated from the body, tissues in which it was deposited are irradiated by alpha-radiation for the entire lifetime of the subject. The dosimetry of Thorotrast patients is very complicated, but currently its reliability is quite high compared with other irradiated populations. The major causes of the death of Thorotrast patients are liver cancer, liver cirrhosis, leukemia, and other cancers. Three histologies of liver cancer are found: cholangiocarcinoma, hepatocellular carcinoma, and angiosarcoma. Although cholangiocarcinoma is the most frequent, angiosarcoma is characteristic of alpha-radiation. Among blood neoplasms with a higher incidence of increase than the general population, erythroleukemia and myelodysplastic syndrome were remarkable. Thorotrast patients exhaled a high concentration of radon (Rn-220), a progeny of Th-232, but no excesses of lung cancer in the patients of Japan, Germany, and Denmark were reported. Mutation analyses of p53 genes and loss of heterozygosity (LOH) studies at 17p locus were performed to characterize the genetic changes in Thorotrast-induced liver tumors. Interestingly, LOH, supposedly corresponding to large deletions was not frequent; most mutations were transitions, also seen in tumors of the general population, suggesting that genetic changes of Thorotrast-induced cancers are mainly delayed mutations, and not the result of the direct effects of radiation. PMID:11797840

Ishikawa, Y; Wada, I; Fukumoto, M

2001-01-01

313

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

SciTech Connect

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

Breus, Dimitry E.

2005-05-16

314

ALPHA CHANNELING IN MIRROR MACHINES AND IN TOKAMAKS Nathaniel J. Fisch  

E-print Network

the fusion ash.2 Channeling 75% of the alpha particle energy to ions can result in more than a factor of two diffused by waves must then necessarily leave the device cold, giving up their energy to the waves in tokamaks exploits the higher population of high-energy alpha particles in the tokamak interior compared

315

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

PubMed

Alpha-particle radiopharmaceutical therapy (?RPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, ?RPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of ?-particle emissions, a dosimetric methodology that accurately predicts the thresholds for organ toxicity has not been reported. This is in part due to the fact that the biological effects caused by ?-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or ?-particle emitting radiopharmaceuticals. The concept of relative biological effectiveness (RBE) is used to quantify the ratio of absorbed doses required to achieve a given biological response with alpha particles versus a reference radiation (typically a beta emitter or external beam radiation). However, as conventionally defined, the RBE varies as a function of absorbed dose and therefore a single RBE value is limited in its utility because it cannot be used to predict response over a wide range of absorbed doses. Therefore, efforts are underway to standardize bioeffect modeling for different fractionation schemes and dose rates for both nuclear medicine and external beam radiotherapy. Given the preponderant use of external beams of radiation compared to nuclear medicine in cancer therapy, the more clinically relevant quantity, the 2 Gy equieffective dose, EQD2(?/?), has recently been proposed by the ICRU. In concert with EQD2(?/?), we introduce a new, redefined RBE quantity, named RBE2(?/?), as the ratio of the two linear coefficients that characterize the ? particle absorbed dose-response curve and the low-LET megavoltage photon 2 Gy fraction equieffective dose-response curve. The theoretical framework for the proposed new formalism is presented along with its application to experimental data obtained from irradiation of a breast cancer cell line. Radiobiological parameters are obtained using the linear quadratic model to fit cell survival data for MDA-MB-231 human breast cancer cells that were irradiated with either ? particles or a single fraction of low-LET (137)Cs ? rays. From these, the linear coefficient for both the biologically effective dose (BED) and the EQD2(?/?) response lines were derived for fractionated irradiation. The standard RBE calculation, using the traditional single fraction reference radiation, gave RBE values that ranged from 2.4 for a surviving fraction of 0.82-6.0 for a surviving fraction of 0.02, while the dose-independent RBE2(4.6) value was 4.5 for all surviving fraction values. Furthermore, bioeffect modeling with RBE2(?/?) and EQD2(?/?) demonstrated the capacity to predict the surviving fraction of cells irradiated with acute and fractionated low-LET radiation, ? particles and chronic exponentially decreasing dose rates of low-LET radiation. RBE2(?/?) is independent of absorbed dose for ?-particle emitters and it provides a more logical framework for data reporting and conversion to equieffective dose than the conventional dose-dependent definition of RBE. Moreover, it provides a much needed foundation for the ongoing development of an ?-particle dosimetry paradigm and will facilitate the use of tolerance dose data available from external beam radiation therapy, thereby helping to develop ?RPT as a single modality as well as for combination therapies. PMID:24502376

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

2014-01-01

316

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

E-print Network

Ab. Table 1. Physical characteristics of radionuclide utilized for TRT. Isotope Half-life (h) Particle Emitted Maximum Energy (keV) LET* Range in Tissue (mm) Iodine-131 (I-131) 193 ?- 970 low 2 Rhenium-186 (Re-186) 91 ?- 1,080 low 11 Rhenium...Ab. Table 1. Physical characteristics of radionuclide utilized for TRT. Isotope Half-life (h) Particle Emitted Maximum Energy (keV) LET* Range in Tissue (mm) Iodine-131 (I-131) 193 ?- 970 low 2 Rhenium-186 (Re-186) 91 ?- 1,080 low 11 Rhenium...

Bhakta, Viharkumar Satish

2011-10-21

317

Radiotoxicity of Gadolinium-148 and Radium-223 in Mouse Testes: Relative Biological Effectiveness of Alpha-Particle Emitters In Vivo  

PubMed Central

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

Howell, Roger W.; Goddu, S. Murty; Narra, Venkat R.; Fisher, Darrell R.; Schenter, Robert E.; Rao, Dandamudi V.

2012-01-01

318

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

SciTech Connect

High precision angular distribution data of (?,?) elastic scattering are presented for the nuclei {sup 89}Y, {sup 92}Mo, {sup 106,110,116}Cd, {sup 112,124}Sn, and {sup 144}Sm at energies around the Coulomb barrier. Such data with small experimental uncertainties over the full angular range (20–170°) are the indispensable prerequisite for the extraction of local optical potentials and for the determination of the total reaction cross section ?{sub reac}. A systematic fitting procedure was applied to the experimental scattering data presented to obtain comprehensive local potential parameter sets that are composed of a real folding potential and an imaginary potential of Woods–Saxon surface type. The potential parameters obtained were used in turn to construct a new systematic ?-nucleus potential with very few parameters. Although this new potential cannot reproduce the angular distributions with the same small deviations as the local potential, the new potential is able to predict the total reaction cross sections for all cases under study.

Mohr, P., E-mail: mohr@atomki.mta.hu [Institute of Nuclear Research (ATOMKI), H-4001 Debrecen (Hungary); Diakonie-Klinikum, D-74523 Schwäbisch Hall (Germany)] [Germany; Kiss, G.G.; Fülöp, Zs. [Institute of Nuclear Research (ATOMKI), H-4001 Debrecen (Hungary)] [Institute of Nuclear Research (ATOMKI), H-4001 Debrecen (Hungary); Galaviz, D. [Centro de Física Nuclear, University of Lisbon, P-1649-003 Lisbon (Portugal)] [Centro de Física Nuclear, University of Lisbon, P-1649-003 Lisbon (Portugal); Gyürky, Gy.; Somorjai, E. [Institute of Nuclear Research (ATOMKI), H-4001 Debrecen (Hungary)] [Institute of Nuclear Research (ATOMKI), H-4001 Debrecen (Hungary)

2013-11-15

319

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

E-print Network

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

Cala, Steven Edward

2012-06-07

320

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

321

Molecular structures of citrate and tricarballylate adsorbed on alpha-FeOOH particles in aqueous suspensions.  

PubMed

In this work, the adsorption of citric (2-hydroxypropane-1,2,3-tricarboxylic acid) and tricarballylic (propane-1,2,3-tricarboxylic acid) acids onto alpha-FeOOH (goethite) in aqueous suspensions was studied as a function of pH and total ligand concentration in 0.1 M NaCl at 25.0 degrees C, and the molecular structures of the surface complexes formed were analyzed by means of ATR-FTIR spectroscopy. The adsorption experiments were carried out as a series of batch experiments, and a newly developed simultaneous infrared and potentiometric titration technique was used to collect in situ infrared spectra with high signal-to-noise ratios. The high quality of the infrared spectra allowed analysis by means of two-dimensional correlation spectroscopy formalism that aided the resolution of pH-dependent spectral features. This has enabled the detection of two previously unidentified citrate-goethite surface complexes: one protonated species at low pH, and one inner sphere complex prevailing at high pH and coordinated via a combination of hydroxyl and carboxylate groups. In addition, an inner sphere complex involving only carboxylate coordination predominating at low pH and an outer sphere complex existing in the circumneutral pH region were identified. The behavior of tricarballylate parallels that of citrate, except no inner sphere surface complex is formed at high pH values, which is in accordance with the lack of an alpha-hydroxyl group. The comparison between citrate and tricarballylate reinforces previous observations showing that inner sphere surface complexes of pure carboxylates at water-iron oxide interfaces are suppressed at high pH values, where outer sphere species are relatively more predominant. It also shows that significant amounts of inner sphere surface complexes of carboxylates only seem to form in the basic pH region when the ligands contain complementary functional groups, such as the hydroxyl or amine groups. PMID:19678691

Lindegren, Malin; Loring, John S; Persson, Per

2009-09-15

322

Alpha decay energies and half-lives for possibly synthesized superheavy elements  

NASA Astrophysics Data System (ADS)

We investigate the ground state properties of some superheavy nuclei, which may be synthesized in future experiments. Special emphases are placed on the alpha decay energies and half-lives. The alpha decay energies and half-lives from different theoretical models are compared and discussed comprehensively. Through these calculations and comparisons, the optimal superheavy elements to be synthesized in future experiments are proposed theoretically. Supported by National Natural Science Foundation of China (10125521, 10535010) and Major State Basic Research Development Program (G2000077400)

Zhi, Qi-Jun; Ren, Zhong-Zhou; Zhang, Xiao-Ping; Zhou, Xiao-Hong; Gan, Zai-Guo; Qin, Zhi; Xu, Hu-Shan

2008-01-01

323

Enhancement of particle-wave energy exchange by resonance sweeping  

SciTech Connect

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

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

1996-01-01

324

Enhancement of particle-wave energy exchange by resonance sweeping  

SciTech Connect

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

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

1995-10-01

325

''Bare'' single-particle energies in Ni-56  

E-print Network

The structure of the low-lying levels in the mirror nuclei Ni-57 and Cu-57 is described within the extended unified model. The problem of single-particle energies in Ni-56 is treated in detail. ''Bare'' single-particle energies are extracted from...

Trache, L.; Kolomiets, A.; Shlomo, S.; Heyde, K.; Dejbakhsh, H.; Gagliardi, Carl A.; Tribble, Robert E.; Zhou, XG; Jacob, VE; Oros, AM.

1996-01-01

326

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

327

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

328

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

SciTech Connect

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

Akli, K. U.; Jiang, S.; Storm, M. S.; Krygier, A.; Freeman, R. R. [The Ohio State University, Columbus, Ohio 43210 (United States); Sanchez del Rio, M. [European Synchrotron Radiation Facility (France); Stephens, R. B. [General Atomics, San Diego, California 92121 (United States); Pereira, N. R. [Ecopulse Inc., Springfield, Virginia 22152 (United States); Baronova, E. O. [RRC Kurchatov Institute, Moscow (Russian Federation); Theobald, W. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Ping, Y.; McLean, H. S.; Patel, P. K.; Key, M. H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2011-12-15

329

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

PubMed Central

The higher potential efficacy of alpha-particle radiopharmaceutical therapy lies in the 3 to 8-fold greater biological effectiveness (RBE) of alpha particles relative to photon or beta-particle radiation. This greater RBE, however, also applies to normal tissue, thereby reducing the potential advantage of high RBE. Since alpha particles typically cause DNA double strand breaks (DSBs), targeting tumors that are defective in DSB repair effectively increases the RBE, yielding a secondary, RBE-based differentiation between tumor and normal tissue that is complementary to conventional, receptor-mediated tumor targeting. In some triple negative breast cancers (TNBC, ER?/PR?/HER-2?), germline mutation in BRCA-1, a key gene in homologous recombination (HR) DSB repair, predisposes patients to early onset of breast cancer. These patients have few treatment options once the cancer has metastasized. In this study, we investigated the efficacy of alpha particle emitter, 213Bi labeled anti-EGFR antibody, Cetuximab, in BRCA-1 defective TNBC. 213Bi-Cetuximab was found to be significantly more effective in the BRCA-1 mutated TNBC cell line HCC1937 than BRCA-1 competent TNBC cell MDA-MB-231. siRNA knockdown of BRCA-1 or DNA-PKcs, a key gene in non-homologous end joining (NHEJ) DSB repair pathway, also sensitized TNBC cells to 213Bi-Cetuximab. Furthermore, the small molecule inhibitor of DNA-PKcs, NU7441, sensitized BRCA-1 competent TNBC cells to alpha particle radiation. Immunofluorescent staining of ?H2AX foci and comet assay confirmed that enhanced RBE is caused by impaired DSB repair. These data offer a novel strategy for enhancing conventional receptor-mediated targeting with an additional, potentially synergistic radiobiological targeting that could be applied to TNBC. PMID:23873849

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

2013-01-01

330

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

PubMed

The higher potential efficacy of alpha-particle radiopharmaceutical therapy lies in the 3- to 8-fold greater relative biological effectiveness (RBE) of alpha particles relative to photon or beta-particle radiation. This greater RBE, however, also applies to normal tissue, thereby reducing the potential advantage of high RBE. As alpha particles typically cause DNA double-strand breaks (DSB), targeting tumors that are defective in DSB repair effectively increases the RBE, yielding a secondary, RBE-based differentiation between tumor and normal tissue that is complementary to conventional, receptor-mediated tumor targeting. In some triple-negative breast cancers (TNBC; ER(-)/PR(-)/HER-2(-)), germline mutation in BRCA-1, a key gene in homologous recombination DSB repair, predisposes patients to early onset of breast cancer. These patients have few treatment options once the cancer has metastasized. In this study, we investigated the efficacy of alpha-particle emitter, (213)Bi-labeled anti-EGF receptor antibody, cetuximab, in BRCA-1-defective TNBC. (213)Bi-cetuximab was found to be significantly more effective in the BRCA-1-mutated TNBC cell line HCC1937 than BRCA-1-competent TNBC cell MDA-MB-231. siRNA knockdown of BRCA-1 or DNA-dependent protein kinase, catalytic subunit (DNA-PKcs), a key gene in non-homologous end-joining DSB repair pathway, also sensitized TNBC cells to (213)Bi-cetuximab. Furthermore, the small-molecule inhibitor of DNA-PKcs, NU7441, sensitized BRCA-1-competent TNBC cells to alpha-particle radiation. Immunofluorescent staining of ?-H2AX foci and comet assay confirmed that enhanced RBE is caused by impaired DSB repair. These data offer a novel strategy for enhancing conventional receptor-mediated targeting with an additional, potentially synergistic radiobiological targeting that could be applied to TNBC. PMID:23873849

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

2013-10-01

331

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...

332

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

333

Semiconductor polycrystalline alpha detectors  

NASA Astrophysics Data System (ADS)

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

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

2006-08-01

334

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

PubMed Central

Targeted radiotherapy using agents tagged with ?-emitting radionuclides is gaining traction with several clinical trials already undertaken or ongoing, and others in the advanced planning stage. The most commonly used ?-emitting radionuclides are 213Bi, 211At, 223Ra and 225Ac. While each one of these has pros and cons, it can be argued that 211At probably is the most versatile based on its half life, decay scheme and chemistry. On the other hand, for targeting bone metastases, 223Ra is the ideal radionuclide because simple cationic radium can be used for this purpose. In this review, we will discuss the recent developments taken place in the application of 211At-labeled radiopharmaceuticals and give an overview of the current status of 223Ra for targeted ?-particle radiotherapy. PMID:22202151

Vaidyanathan, Ganesan; Zalutsky, Michael R.

2012-01-01

335

Charged particle rapidity distributions at relativistic energies  

E-print Network

of ultrarelativistic nucleon- nucleon scattering to nucleus-nucleus collisions, predicts too many charged particles compared with the PHOBOS data @7#. On the other hand, the hadronic cascade model LUCIFER @8# predicts a charged particle multiplicity near... midrapidity that is comparable to the PHOBOS data @9#. In this Rapid Communication, we shall use a multiphase transport model ~AMPT! @10#, that includes both partonic and hadronic inter- actions, to study their effects not only on the total charged...

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

2001-01-01

336

Inelastic Alpha Scattering Studies of Low-Energy Octupole Resonance  

E-print Network

are in excellent agreement with /- = 3 distorted-wave Born approximation calculations. Studies of the angular range from cr&,b ?3.5' to 6' in "Sn indicate very little contribution from l ~ 1 strength. Energy- weighted sum rule fractions for this low...-energy octupole resonance in ' Sm account qualitatively for the data. NUCLEAR REACTIONS +Ca, 66Zn, As, ~Y, 9 Zr, ~ Mo, OMo, Ag. (nat), ii6Sn 118Sn i2 Sn i42Nd i44Sm i48Sm i54Sm i%Au 20spb(~ ~i) E ?g6 MeV measured E?, 0(B) giant resonances, deduced l, P. I...

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

1978-01-01

337

Radioimmunotherapy with alpha-emitting nuclides.  

PubMed

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

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

1998-09-01

338

Neutrino Masses, Cosmological Parameters and Dark Energy from the Transmitted Flux in the Lyman-alpha Forest  

NASA Astrophysics Data System (ADS)

The signature left in quasar spectra by the presence of neutral hydrogen in the Universe allows one to constrain the sum of the neutrino masses with unprecedented sensitivity, with respect to laboratory experiments. At the forefront of elementary particle physics and cosmology, this may also shed a new light on the neutrino mass hierarchy, and on the absolute mass scale of neutrinos. In addition, constrains on cosmological parameters and on the dark energy equation of state can be derived, from a joint parameter estimation. This however requires a detailed modeling of the line-of-sight power spectrum of the transmitted flux in the Lyman-alpha forest on scales ranging from a few to hundreds of Mpcs, which in turns demands for the inclusion and careful treatment of cosmological neutrinos. In particular, since massive neutrinos are known to significantly alter structure formation, one needs to quantify their free-streaming effect consistently. We develop here a new hydrodynamical code which incorporates cold dark matter, gas, and is also able to reproduce the impact of massive neutrinos on the one-dimensional power spectrum with a novel technique. In synergy with corresponding experimental work from state-of-the-art surveys such as BOSS, and with upcoming or future large-scale-structure probes (e.g. Planck, Euclid), this will allow one to constrain the sum of the neutrino massses and the main cosmological parameters with unprecedented statistical significance. The theoretical study presented here will be combined with topological techniques to investigate dark energy and the expansion history of the Universe directly from the Lyman-alpha transmitted flux. The method will be also relevant for BigBOSS, which is expected to produce Lyman-alpha forest data along ~600,000 distant QSOs, and the data will be used to study the line-of-sight one-dimensional fluctuations.

Rossi, Graziano; Palanque-Delabrouille, N.; Yeche, C.; Borde, A.; Rich, J.; Viel, M.; Lesgourgues, J.

2013-01-01

339

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

PubMed Central

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

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

1989-01-01

340

Relativistic configuration-interaction calculation of $K\\alpha$ transition energies in beryllium-like iron  

E-print Network

We perform relativistic configuration-interaction calculations of the energy levels of the low-lying and core-excited states of beryllium-like iron, Fe$^{22+}$. The results include the QED contributions calculated by two different methods, the model QED operator approach and the screening-potential approach. The uncertainties of theoretical energies are estimated systematically. The predicted wavelengths of the K\\alpha transitions in beryllium-like iron improve previous theoretical results and compare favorably with the experimental data.

Yerokhin, V A; Fritzsche, S

2014-01-01

341

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

NASA Astrophysics Data System (ADS)

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

Ong, Rene A.; Covault, Corbin E.

2009-05-01

342

Distribution of porous colloidal particles in an energy field  

NASA Astrophysics Data System (ADS)

The spatial distribution of colloidal particles in an energy field is evaluated theoretically. The field may be established by a relatively large object such as a rigid wall, a closed boundary, and a particle. The set of nonlinear hypernetted chain equations describing the variations of the correlation functions for particle-particle and particle-object interactions is solved. A numerical scheme based on the discrete Fourier transform is proposed for the former, and a Newton-Raphson iterative method for the latter. Three cases are examined to illustrate the method proposed, namely, particles in a planar slit, cylindrical pore, and square duct. The qualitative behavior of the spatial variation of the concentration of colloidal particles predicted by the present study is consistent with that observed experimentally by D.H. Van Winkle and C.A. Murray [J. Chem. Phys. 89 (1988) 3885].

Hsu, Jyh-Ping; Tseng, Ming-Tsan; Tseng, Shiojenn

1999-03-01

343

Electronic energy levels of cinnabar (alpha-HgS)  

Microsoft Academic Search

We have calculated the electronic energy levels of trigonal mercury sulfide in the semiempirical tight-binding scheme. The atomic levels 3s, 3p of sulfur and 6s, 6p of mercury constitute the starting basis set. The computed two-center overlap integrals are subsequently scaled by a common multiplicative factor to reproduce the experimental optical gap. The effect of the atomic virtual level 4s

E. Doni; L. Resca; S. Rodriguez; W. M. Becker

1979-01-01

344

Neutron angular and energy distributions from 710-MeV alphas stopping in water, carbon, steel, and lead, and 640-MeV alphas stopping in lead  

SciTech Connect

We measured neutron angular and energy distributions from 710-MeV alphas stopping in targets of water, carbon, steel, and lead for neutron energies from 3 MeV to above 300 MeV. We also measured neutron spectra from 640-MeV alphas stopping in lead. These spectra are similar to the 710-MeV spectra but are reduced in magnitude by about 20 percent. The angular distributions are forward peaked and have a broad bump at about 120 MeV in the 0- and 6-degree spectra. The 710-MeV integrated yields above 10 MeV are about 0.5 neutron per incident alpha, independent of the target. The measured spectra from the water target are consistent with the calculations of an intranuclear-cascade model at the forward angles, but are larger than the calculations at the backward angles.

Cecil, R.A.; Anderson, B.D.; Baldwin, A.R.; Madey, R.; Galonsky, A.; Miller, P.; Young, L.; Waterman, F.M.

1980-06-01

345

String black holes as particle accelerators to arbitrarily high energy  

NASA Astrophysics Data System (ADS)

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

Pradhan, Parthapratim

2014-07-01

346

String Black Holes as Particle Accelerators to Arbitrarily High Energy  

E-print Network

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

Parthapratim Pradhan

2013-10-30

347

Dissipative Particle Dynamics with Energy Conservation: Heat Conduction  

Microsoft Academic Search

We study by means of numerical simulations the model of dissipative particle dynamics with energy conservation for the simple case of thermal conduction. It is shown that the model displays correct equilibrium fluctuations and reproduces Fourier law. The connection between \\

Marisol Ripoll; Pep Español; Matthieu H. Ernst

1999-01-01

348

Particle Production in High-energy Heavy-ion Collisions  

E-print Network

Particle production mechanisms in high-energy heavy-ion collisions are reviewed in connection with recent experimental data from RHIC. Implications on mini-jet production, parton saturation and jet quenching are discussed.

Xin-Nian Wang

2001-11-29

349

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

NASA Technical Reports Server (NTRS)

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

Combi, Michael R.; Smyth, William H.

1988-01-01

350

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

351

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 (p¡0.05). However, the absence of p21 resulted in deficiency in inducing bystander effects. Further results indicated p21 affected the intercellular DNA damage signaling mainly through disrupting the production or release of the damage signals from irradiated cells. When Hus1 and p21 were both knocked out, an obvious induction of -H2AX recurred in bystander cells and the induction of -H2AX was GJIC (gap junction-mediated intercellular communication) dependent, indicating the interrelationship between p21 and Hus1 regulated the production and relay of DNA damage signals from irradiated cells to non-irradiated bystander cells.

Wu, Lijun; Zhao, Ye; Wang, Jun; Hang, Haiying

352

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

E-print Network

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

G. K. Nie

2008-06-23

353

Alpha Channeling in a Rotating Plasma  

SciTech Connect

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

Abraham J. Fetterman and Nathaniel J. Fisch

2008-09-23

354

STRV RADMON: An integrated high-energy particle detector  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

355

Open Problems in $?$ Particle Condensation  

E-print Network

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

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

2010-03-05

356

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

NASA Technical Reports Server (NTRS)

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

Ruyten, Wilhelmus M.

1992-01-01

357

Particle mixing, flavor condensate and dark energy  

E-print Network

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

Massimo Blasone; Antonio Capolupo; Giuseppe Vitiello

2009-12-08

358

Elementary particle physics and high energy phenomena  

SciTech Connect

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

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

1992-06-01

359

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

360

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

361

Indpeendent Yields of Iodine and Tellurium Isotopes in Fission of 232 Thorium with 30.5 MeV Alpha Particles  

Microsoft Academic Search

Iodine and tellurium isotopes produced in the fission of Th with 30.5 MeV alpha particles were separated using a method of sublimation in an air stream and the independent yields of I, I, I, I I, Te, Te and Te (cumulative) were determined by means of high resolution Ge(Li) ?-ray spectrometry. A Gaussian fit to the experimental data was used

E. Dobreva; N. Nenoff; B. Zhuikov

1981-01-01

362

Engineered Modular Recombinant Transporters: Application of New Platform for Targeted Radiotherapeutic Agents to {alpha}-Particle Emitting {sup 211}At  

SciTech Connect

Purpose: To generate and evaluate a modular recombinant transporter (MRT) for targeting {sup 211}At to cancer cells overexpressing the epidermal growth factor receptor (EGFR). Methods and Materials: The MRT was produced with four functional modules: (1) human epidermal growth factor as the internalizable ligand, (2) the optimized nuclear localization sequence of simian vacuolating virus 40 (SV40) large T-antigen, (3) a translocation domain of diphtheria toxin as an endosomolytic module, and (4) the Escherichia coli hemoglobin-like protein (HMP) as a carrier module. MRT was labeled using N-succinimidyl 3-[{sup 211}At]astato-5-guanidinomethylbenzoate (SAGMB), its {sup 125}I analogue SGMIB, or with {sup 131}I using Iodogen. Binding, internalization, and clonogenic assays were performed with EGFR-expressing A431, D247 MG, and U87MG.wtEGFR human cancer cell lines. Results: The affinity of SGMIB-MRT binding to A431 cells, determined by Scatchard analysis, was 22 nM, comparable to that measured before labeling. The binding of SGMIB-MRT and its internalization by A431 cancer cells was 96% and 99% EGFR specific, respectively. Paired label assays demonstrated that compared with Iodogen-labeled MRT, SGMIB-MRT and SAGMB-MRT exhibited more than threefold greater peak levels and durations of intracellular retention of activity. SAGMB-MRT was 10-20 times more cytotoxic than [{sup 211}At]astatide for all three cell lines. Conclusion: The results of this study have demonstrated the initial proof of principle for the MRT approach for designing targeted {alpha}-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this {sup 211}At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor.

Rosenkranz, Andrey A. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Department of Biophysics, Biological Faculty, Moscow State University, Moscow (Russian Federation); Vaidyanathan, Ganesan; Pozzi, Oscar R. [Department of Radiology, Duke University Medical Center, Durham, NC (United States); Lunin, Vladimir G. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Gamaleya Institute of Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow (Russian Federation); Zalutsky, Michael R. [Department of Radiology, Duke University Medical Center, Durham, NC (United States)], E-mail: zalut001@mc.duke.edu; Sobolev, Alexander S. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Department of Biophysics, Biological Faculty, Moscow State University, Moscow (Russian Federation)], E-mail: sobolev@igb.ac.ru

2008-09-01

363

Particle and Wave Energy Transport During Magnetic Reconnection  

NASA Astrophysics Data System (ADS)

A fundamental issue in magnetic reconnection concerns the magnetic energy stored in a reversed-field configuration: how much magnetic energy is lost as spontaneous reconnection develops and where does it go? This question is addressed using implicit 2-D PIC simulations together with the kinetic theory of energy transport of both waves and particles. The primary initial condition in these studies is a Harris equilibrium with a small guide field and background particles. The decrease in time of the integrated magnetic energy density is associated with an almost equal increase in time of the integrated ion energy density. Electrons receive only a small fraction of the initial free energy but electron phase space holes appear to play a role in the production of electromagnetic waves over a large region of the simulation box. The spatial transport of particle and field energies is studied at a late time. The dominant Poynting flux transports magnetic energy across the magnetic flux pile-up region, and is associated with the reconnection E-field. A weaker but faster Poynting flux on the separatrices is associated with the Hall electric and magnetic fields, EH and BH. The ion energy density flux and its components (bulk flow energy, enthalpy flux and heat flux) are analyzed and compared with the Poynting flux for both Harris and non-Harris initial conditions. ---Research supported by NASA and NSF

Goldman, M. V.; Newman, D. L.; Lapenta, G.; Markidis, S.; Gosling, J. T.; Andersson, L.; Eriksson, S.

2012-12-01

364

The Low-Energy Frontier of Particle Physics  

E-print Network

Most embeddings of the Standard Model into a more unified theory, in particular the ones based on supergravity or superstrings, predict the existence of a hidden sector of particles which have only very weak interactions with the visible sector Standard Model particles. Some of these exotic particle candidates (such as e.g. "axions", "axion-like particles" and "hidden U(1) gauge bosons") may be very light, with masses in the sub-eV range, and have very weak interactions with photons. Correspondingly, these very weakly interacting sub-eV particles (WISPs) may lead to observable effects in experiments (as well as in astrophysical and cosmological observations) searching for light shining through a wall, for changes in laser polarisation, for non-linear processes in large electromagnetic fields and for deviations from Coulomb's law. We present the physics case and a status report of this emerging low-energy frontier of fundamental physics.

Joerg Jaeckel; Andreas Ringwald

2010-02-01

365

(Medium energy particle physics): Annual progress report  

SciTech Connect

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

Nefkens, B.M.K.

1985-10-01

366

Energy related applications of elementary particle physics  

SciTech Connect

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

Rafelski, J.

1991-08-31

367

A Mathematica Program Using Isotropic Harmonic Oscillator Eigenstates to Model Alpha-Particle Tunneling Half Life Variability  

E-print Network

We have developed a Mathematica program which uses three-dimensional, isotropic harmonic oscillator wavefunctions for the solutions interior to the nucleus, and Coulomb wavefunctions for the exterior. The algorithm enables us to calculate the half life for alpha decay for alpha decay for varying depths of the nuclear potential well.

Eugene F. Chaffin; Nicholas W. Gothard; Joshua Tuttle

2001-05-28

368

Sculpting optical energy landscapes for multi-particle nanoscale assembly  

NASA Astrophysics Data System (ADS)

To understand the forces and dynamics of two or more neutral particles trapped within an optical beam, careful consideration of the influence of inter-particle forces is required. The well-known, field-independent intrinsic force is known to derive from the Casimir-Polder interaction. However, the magnitude of this force may be over-ridden by the effect known as optical binding, in cases when the laser beam is of sufficient intensity. This binding interaction is completely independent of optomechanical effects relating to optical tweezers, and involves a stimulated (pairwise) forward-scattering process. Unlike the Casimir-Polder coupling, optical binding is not always an attractive force when both particles are in their ground state. Associated with optical binding are potential energy surfaces, which reveal intricate patterns of local minima - sets of positions in which one of the particles will sit at equilibrium (with the other notionally set at the origin). These optical energy landscapes, which can be illustrated by use of contour diagrams, have mostly been considered for systems in which spherical particles are optically bound. The effect of different particle shapes, for example tube-like structures, can also be explored. Moreover, although the theory of conventional optical binding generally assumes situations in which both particles reside in their ground states, new results arise when individual particles are excited to a higher electronic state. Although, in the experimentally most convenient structural configuration (for tumbling spherical particles), pairwise optical binding vanishes in the short-range region, novel effects can arise as a result of non-zero optical binding between three neighbouring particles.

Bradshaw, David S.; Forbes, Kayn A.; Andrews, David L.

2014-05-01

369

Energy States of Colored Particle in a Chromomagnetic Field  

E-print Network

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

Sh. Mamedov

2006-08-20

370

Determination of isoprene and alpha-/beta-pinene oxidation products in boreal forest aerosols from Hyytiälä, Finland: diel variations and possible link with particle formation events.  

PubMed

Biogenic volatile organic compounds (VOCs), such as isoprene and alpha-/beta-pinene, are photo-oxidized in the atmosphere to non-volatile species resulting in secondary organic aerosol (SOA). The goal of this study was to examine time trends and diel variations of oxidation products of isoprene and alpha-/beta-pinene in order to investigate whether they are linked with meteorological parameters or trace gases. Separate day-night aerosol samples (PM(1)) were collected in a Scots pine dominated forest in southern Finland during 28 July-11 August 2005 and analyzed with gas chromatography/mass spectrometry (GC/MS). In addition, inorganic trace gases (SO(2), CO, NO(x), and O(3)), meteorological parameters, and the particle number concentration were monitored. The median total concentration of terpenoic acids (i.e., pinic acid, norpinic acid, and two novel compounds, 3-hydroxyglutaric acid and 2-hydroxy-4-isopropyladipic acid) was 65 ng m(-3), while that of isoprene oxidation products (i.e., 2-methyltetrols and C(5) alkene triols) was 17.2 ng m(-3). The 2-methyltetrols exhibited day/night variations with maxima during day-time, while alpha-/beta-pinene oxidation products did not show any diel variation. The sampling period was marked by a relatively high condensation sink, caused by pre-existing aerosol particles, and no nucleation events. In general, the concentration trends of the SOA compounds reflected those of the inorganic trace gases, meteorological parameters, and condensation sink. Both the isoprene and alpha-/beta-pinene SOA products were strongly influenced by SO(2), which is consistent with earlier reports that acidity plays a role in SOA formation. The results support previous proposals that oxygenated VOCs contribute to particle growth processes above boreal forest. PMID:18211553

Kourtchev, I; Ruuskanen, T M; Keronen, P; Sogacheva, L; Dal Maso, M; Reissell, A; Chi, X; Vermeylen, R; Kulmala, M; Maenhaut, W; Claeys, M

2008-01-01

371

Charged-particle multiplicity at LHC energies  

ScienceCinema

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

None

2011-10-06

372

Bremsstrahlung in {alpha} Decay Reexamined  

SciTech Connect

A high-statistics measurement of bremsstrahlung emitted in the {alpha} decay of {sup 210}Po has been performed, which allows us to follow the photon spectra up to energies of {approx}500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the {alpha} particle and the emitted photon.

Boie, H.; Scheit, H.; Jentschura, U. D.; Koeck, F.; Lauer, M.; Schwalm, D. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Milstein, A. I.; Terekhov, I. S. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation)

2007-07-13

373

Bremsstrahlung in alpha decay reexamined.  

PubMed

A high-statistics measurement of bremsstrahlung emitted in the alpha decay of (210)Po has been performed, which allows us to follow the photon spectra up to energies of approximately 500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the alpha particle and the emitted photon. PMID:17678219

Boie, H; Scheit, H; Jentschura, U D; Köck, F; Lauer, M; Milstein, A I; Terekhov, I S; Schwalm, D

2007-07-13

374

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

PubMed Central

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

2014-01-01

375

On the origin of ultra high energy cosmic ray particles  

NASA Astrophysics Data System (ADS)

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

Thielheim, K. O.

1998-06-01

376

Diagnostic of the spatial and velocity distribution of alpha particles in tokamak fusion reactor using beat-wave generated lower hybrid wave. Progress report, 1994--1995  

SciTech Connect

The alpha particle population from fusion reactions in a DT tokamak reactor can have dramatic effects on the pressure profiles, energetic particle confinement, and the overall stability of the plasma; thus leading to important design consideration of a fusion reactor based on the tokamak concept. In order to fully understand the effects of the alpha population, a non-invasive diagnostic technique suitable for use in a reacting plasma environment needs to be developed to map out both the spatial and velocity distribution of the alphas. The proposed experimental goals for the eventual demonstration of LH wave interaction with a fast ion population is given in the reduced 3 year plan in table 1. At present time the authors are approaching the 8th month in their first year of this project. Up to now, their main effort has been concentrated in the operation of the two beat wave sources in burst mode. The second priority in the experimental project is the probe diagnostics and computer aided data acquisition system. The progress made so far is given, and they are ready to perform the beat-wave generated lower hybrid wave experiment. Some theoretical calculation had been reported at APS meetings. More refined theoretical models are being constructed in collaboration with Drs. J. Rogers and E. Valeo at PPPL.

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

1995-03-05

377

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

SciTech Connect

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

Caryl Gronwall

2012-12-03

378

Newer energy-efficient approach to particle production by comminution  

Microsoft Academic Search

Grinding tests on solids of varying hardness show that, in general, energy utilization in a choke-fed high-pressure roll mill is higher than in a ball mill, but lower than in the single-particle mode of comminution under slow compressive loads. The presence of moisture in feeds improves the energy efficiency of the high-pressure roll mill somewhat, presumably by reducing interparticle friction

D. W. Fuerstenau; P. C. Kapur

1995-01-01

379

Production of heavy charged Higgs particles at very high energies  

Microsoft Academic Search

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

J. A. Grifols; J. Solà

1981-01-01

380

Low-energy particle radiation environment at synchronous altitude  

NASA Technical Reports Server (NTRS)

The degradation of thermal control coatings of satellites due to the effects of low energy charged particles in the space environment is discussed. Data obtained from ATS-5 satellite measurement of proton and electron fluxes are presented. The variations in electron density, proton density, and magnetic activity are presented to show correlations which exist between these space factors.

Shelley, E. G.; Lens, S. K.

1972-01-01

381

Analysis of nuclear materials by energy dispersive x-ray fluorescence and spectral effects of alpha decay  

SciTech Connect

Energy dispersive X-ray fluorescence (EDXRF) spectra collected from alpha emitters are complicated by artifacts inherent to the alpha decay process, particularly when using portable instruments. For example, {sup 239}Pu EDXRF spectra exhibit a prominent uranium L X-ray emission peak series due to sample alpha decay rather than source-induced X-ray fluorescence. A portable EDXRF instrument was used to collect spectra from plutonium, americium, and a Pu-contaminated steel sample. The plutonium sample was also analyzed by wavelength dispersive XRF to demonstrate spectral differences observed when using these very different instruments.

Worley, Christopher G [Los Alamos National Laboratory

2009-01-01

382

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

PubMed

Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H2, and eliminates delocalization errors in H2(+) and other single-bond systems. It gives surprisingly good non-bonded interaction energies--competitive with the ph-RPA--with the correct R(-6) asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations. PMID:24832319

van Aggelen, Helen; Yang, Yang; Yang, Weitao

2014-05-14

383

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

NASA Astrophysics Data System (ADS)

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

van Aggelen, Helen; Yang, Yang; Yang, Weitao

2014-05-01

384

An alpha scintillation spectrometer  

E-print Network

. Uranium 1'hick Uranium sources were tested to determine if any differences would exist between the oulse height distribution oi' thick Uranium and Thorium sources. Sources were prepared by placing small pieces of Uranium nitrate, UO2 (NO3)2 6H20, on a... phosphor covered light-piper. The ten different energy alpha particles that were emitted from the Uranium were blended into a continuous distribution, there being no apparent difference between this and the thick Thorium distribution. The same was true...

Yates, Ralph Aaron

2012-06-07

385

Advances in particle identification in AMS at low energies  

NASA Astrophysics Data System (ADS)

Special gas ionisation detectors have been developed for AMS at low energies (0.3-3 MeV). By using very thin silicon nitride foils as entrance windows and low-noise preamplifiers, significant improvements in the performance has been obtained. In addition, electronic noise has been reduced by a compact design which minimises cable length and input capacitance. The resolution has been systematically studied as a function of energy for various projectiles ranging from protons to uranium. Energy straggling in the thin entrance foil is only a minor contribution to the total energy resolution. For heavier ions zp > 6 the resolution is limited by the statistical nature of the ionisation process in the counter gas. For light elements, the electronic noise is the dominant contribution to the resolution. Particle identification with ? E - E techniques has been studied as well. Good isobar separation for 10Be- 10B can be obtained in the energy range of 0.3-0.8 MeV. Also isobaric molecules such as BeH and CH can be identified in the energy range of 1 MeV. These advances in detector performance represent an essential step forward in the development of multi-isotope AMS facilities at low energies. The detector development has also a potential for application in other fields of research where good energy resolution and particle identification is needed.

Suter, Martin; Döbeli, Max; Grajcar, Michal; Müller, Arnold; Stocker, Martin; Sun, Guoyan; Synal, Hans-Arno; Wacker, Lukas

2007-06-01

386

Long-range alpha detector for contamination monitoring  

SciTech Connect

Historically, alpha detectors have been limited by the very short range of alpha particles in air and by relatively poor sensitivity, even if the particles are intercepted. Of necessity, these detectors are operated in a vacuum or in close proximity to the source if reasonable efficiency is desired. In our new long-range alpha detector (LRAD), alpha particles interact with the ambient air, producing ionization in the air at the rate of about 30,000 ion pairs per MeV of alpha energy. These charges can be transported over significant distances (several meters) in a moving current of air generated by a small fan. An ion chamber located in front of the fan measures the current carried by the moving ions. The LRAD-based monitor is more sensitive and more thorough than conventional monitors. We present current LRAD sensitivity limits and results, practical monitor designs, and proposed uses for LRAD monitors. 4 refs., 6 figs.

MacArthur, D.W.; Allander, K.S.; McAtee, J.L.

1991-01-01

387

A Closed Parameterization of DNA-Damage by Charged Particles, as a Function of Energy -- A Geometrical Approach  

PubMed Central

Purpose To present a closed formalism calculating charged particle radiation damage induced in DNA. The formalism is valid for all types of charged particles and due to its closed nature is suited to provide fast conversion of dose to DNA-damage. Methods The induction of double strand breaks in DNA–strings residing in irradiated cells is quantified using a single particle model. This leads to a proposal to use the cumulative Cauchy distribution to express the mix of high and low LET type damage probability generated by a single particle. A microscopic phenomenological Monte Carlo code is used to fit the parameters of the model as a function of kinetic energy related to the damage to a DNA molecule embedded in a cell. The model is applied for four particles: electrons, protons, alpha–particles, and carbon ions. A geometric interpretation of this observation using the impact ionization mean free path as a quantifier, allows extension of the model to very low energies. Results The mathematical expression describes the model adequately using a chi–square test (). This applies to all particle types with an almost perfect fit for protons, while the other particles seem to result in some discrepancies at very low energies. The implementation calculating a strict version of the RBE based on complex damage alone is corroborated by experimental data from the measured RBE. The geometric interpretation generates a unique dimensionless parameter for each type of charged particle. In addition, it predicts a distribution of DNA damage which is different from the current models. PMID:25340636

Van den Heuvel, Frank

2014-01-01

388

Automated Reconstruction of Particle Cascades in High Energy Physics Experiments  

E-print Network

We present a procedure for reconstructing particle cascades from event data measured in a high energy physics experiment. For evaluating the hypothesis of a specific physics process causing the observed data, all possible reconstruction versions of the scattering process are constructed from the final state objects. We describe the procedure as well as examples of physics processes of different complexity studied at hadron-hadron colliders. We estimate the performance by 20 microseconds per reconstructed decay vertex, and 0.6 kByte per reconstructed particle in the decay trees.

O. Actis; M. Erdmann; A. Henrichs; A. Hinzmann; M. Kirsch; G. Müller; J. Steggemann

2008-01-08

389

A (238)Pu irradiator for exposure of cultured cells with alpha-radiation: construction, calibration and dosimetry.  

PubMed

An alpha-particle irradiator that can facilitate investigations of alpha-radiation effects on human cells in radiation protection, carcinogenesis and radioimmunotherapy was constructed. The irradiator was based on a 1.3 GBq (238)Pu source, housed in a stainless steel tube flushed with helium. Radiation provided by (238)Pu consists mainly of alpha-particles with energy of 5.5 MeV. The alpha-particle fluence and energy spectra were measured with a silicon semiconductor detector. Monte Carlo simulations were used to estimate the mean number of alpha-particles and the mean absorbed alpha-particle dose to cells for various irradiation times and distances between cells and source. There was a linear dependence between exposure time and alpha-particle fluence for exposure times above 1s. The alpha-particle activity concentration varied with a factor 2.7 over the source area, while the variation in energy peak position was <4%. At the cell nucleus position and with a distance of 45 mm between the source and the mylar dish surface, the alpha-fluence was 4.6 x 10(4)counts/(mm(2)s), the average incident alpha-particle energy was 2.5 MeV and the average linear energy transfer was 167 keV/microm. The average dose rate to the cells, with 5 microm diameter nucleus, was 1.2 Gy/s. The (238)Pu alpha-particle irradiator is feasible for irradiation of cells and it can be used for studies of both direct effects and bystander effects of alpha-radiation. PMID:19716308

Tisnek, Nikolai; Kalanxhi, Erta; Serkland, Camilla Walle; Iversen, Jørn; Belyakov, Oleg V; Dahle, Jostein

2009-11-01

390

SOLANG: A user-friendly code to calculate the geometry factor using Monte Carlo simulations. Application to alpha-particle spectrometry.  

PubMed

Monte Carlo simulation was applied to calculate the effective solid angle (or geometry factor) presented by a plane radioactive source at a detector entrance window. A fast and user-friendly computer program SOLANG was written to perform the calculations for disk or rectangular sources and circular non-coaxial detector disks. Results can be achieved with great precision, depending on the number of simulated trajectories. Some checks and applications to the calculation of efficiencies of semiconductor detectors and gas ionization chambers used to measure alpha particles are presented. Their results were very reliable. The code is available free of charge on request to the authors. PMID:21316251

Cornejo Díaz, N A; Martín Sánchez, A; de la Torre Pérez, J

2011-05-01

391

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. PMID:24049184

Roby, Justin A.; Hall, Roy A.

2013-01-01

392

Broken flavor symmetries in high energy particle phenomenology  

SciTech Connect

Over the past couple of decades, the Standard Model of high energy particle physics has clearly established itself as an invaluable tool in the analysis of high energy particle phenomenon. However, from a field theorists point of view, there are many dissatisfying aspects to the model. One of these, is the large number of free parameters in the theory arising from the Yukawa couplings of the Higgs doublet. In this thesis, we examine various issues relating to the Yukawa coupeng structure of high energy particle field theories. We begin by examining extensions to the Standard Model of particle physics which contain additional scalar fields. By appealing to the flavor structure observed in the fermion mass and Kobayashi-Maskawa matrices, we propose a reasonable phenomenological parameterization of the new Yukawa couplings based on the concept of approximate flavor symmetries. It is shown that such a parameterization eliminates the need for discrete symmetries which limit the allowed couplings of the new scalars. New scalar particles which can mediate exotic flavor changing reactions can have masses as low as the weak scale. Next, we turn to the issue of neutrino mass matrices, where we examine a particular texture which leads to matter independent neutrino oscillation results for solar neutrinos. We, then, examine the basis for extremely strict limits placed on flavor changing interactions which also break lepton- and/or baryon-number. These limits are derived from cosmological considerations. Finally, we embark on an extended analysis of proton decay in supersymmetric SO(10) grand unified theories. In such theories, the dominant decay diagrams involve the Yukawa couplings of a heavy triplet superfield. We argue that past calculations of proton decay which were based on the minimal supersymmetric SU(5) model require reexamination because the Yukawa couplings of that theory are known to be wrong.

Antaramian, A.

1995-02-22

393

The Maximum Energy of Accelerated Particles in Relativistic Collisionless Shocks  

NASA Astrophysics Data System (ADS)

The afterglow emission from gamma-ray bursts (GRBs) is usually interpreted as synchrotron radiation from electrons accelerated at the GRB external shock that propagates with relativistic velocities into the magnetized interstellar medium. By means of multi-dimensional particle-in-cell simulations, we investigate the acceleration performance of weakly magnetized relativistic shocks, in the magnetization range 0 <~ ? <~ 10-1. The pre-shock magnetic field is orthogonal to the flow, as generically expected for relativistic shocks. We find that relativistic perpendicular shocks propagating in electron-positron plasmas are efficient particle accelerators if the magnetization is ? <~ 10-3. For electron-ion plasmas, the transition to efficient acceleration occurs for ? <~ 3 × 10-5. Here, the acceleration process proceeds similarly for the two species, since the electrons enter the shock nearly in equipartition with the ions, as a result of strong pre-heating in the self-generated upstream turbulence. In both electron-positron and electron-ion shocks, we find that the maximum energy of the accelerated particles scales in time as ?maxvpropt 1/2. This scaling is shallower than the so-called (and commonly assumed) Bohm limit ?maxvpropt, and it naturally results from the small-scale nature of the Weibel turbulence generated in the shock layer. In magnetized plasmas, the energy of the accelerated particles increases until it reaches a saturation value ?sat/?0 mic 2 ~ ?-1/4, where ?0 mic 2 is the mean energy per particle in the upstream bulk flow. Further energization is prevented by the fact that the self-generated turbulence is confined within a finite region of thickness vprop?-1/2 around the shock. Our results can provide physically grounded inputs for models of non-thermal emission from a variety of astrophysical sources, with particular relevance to GRB afterglows.

Sironi, Lorenzo; Spitkovsky, Anatoly; Arons, Jonathan

2013-07-01

394

Instrument to measure energy and charge of low energy interplanetary particles  

NASA Technical Reports Server (NTRS)

An experiment to measure the charge composition and energy spectra of ultra low energy charged particles in interplanetary space has been developed and launched on the IMP 8 (Explorer 50) satellite on Oct. 26, 1973. The instrument consists of two separate sensors sharing common electronics. One of these sensors uses a thin window gas proportional counter to measure the rate of energy loss and a totally depleted silicon surface barrier detector to measure total energy of incoming particles. The energy range for two dimensional analysis extends from 300 KeV to 2.5 MeV for protons and 60 KeV/nucleon to 25 MeV/nucleon for iron with excellent resolution of individual chemical elements. The other sensor combines electrostatic deflection with total energy measurements in silicon surface barrier detectors to give the ionic charge and kinetic energy of the particle.

Tums, E.; Gloeckler, G.; Cain, J.; Sciambi, R.; Fan, C. Y.

1974-01-01

395

Absorption of intermediate-energy photons by multi-particle clusters in 6Li  

Microsoft Academic Search

The results of a study of the 6Li(gamma, cc) (c, c:´ charged particle) reaction with the tagged-photon technique are presented. It is shown that the (gamma, pt) reaction can be understood within the framework of a semi-phenomenological quasi-alpha reaction model. The total (gamma, pt) cross section is found to be larger than the 6Li(gamma, pn)alpha cross section at the same

D. Ryckbosch; L. van Hoorebeke; R. van de Vyver; C. van den Abeele; J. Dias; J.-O. Adler; K. I. Blomqvist; D. Nilsson; B. Schröder; K. Ziakas

1994-01-01

396

Terpenylic acid and related compounds from the oxidation of alpha-pinene: implications for new particle formation and growth above forests.  

PubMed

Novel secondary organic aerosol (SOA) products from the monoterpene alpha-pinene with unique dimer-forming properties have been identified as lactone-containing terpenoic acids, i.e., terpenylic and 2-hydroxyterpenylic acid, and diaterpenylic acid acetate. The structural characterizations were based on the synthesis of reference compounds and detailed interpretation of mass spectral data. Terpenylic acid and diaterpenylic acid acetate are early oxidation products generated upon both photooxidation and ozonolysis, while 2-hydroxyterpenylic acid is an abundant SOA tracer in ambient fine aerosol that can be explained by further oxidation of terpenylic acid. Quantum chemical calculations support that noncovalent dimer formation involving double hydrogen bonding interactions between carboxyl groups of the monomers is energetically favorable. The molecular properties allow us to explain initial particle formation in laboratory chamber experiments and are suggested to play a role in new particle formation and growth above forests, a natural phenomenon that has fascinated scientists for more than a century. PMID:19806730

Claeys, Magda; Iinuma, Yoshiteru; Szmigielski, Rafal; Surratt, Jason D; Blockhuys, Frank; Van Alsenoy, Christian; Böge, Olaf; Sierau, Berko; Gómez-González, Yadian; Vermeylen, Reinhilde; Van der Veken, Pieter; Shahgholi, Mona; Chan, Arthur W H; Herrmann, Hartmut; Seinfeld, John H; Maenhaut, Willy

2009-09-15

397

Post-shock spikes: A new feature of proton and alpha enhancements associated with an interplanetary shock wave  

NASA Technical Reports Server (NTRS)

Abrupt and prolonged enhancements in the intensities of 100 to approximately 2000 keV nucleon protons and alpha particles observed in interplanetary space are interpreted as particle populations confined between an interplanetary shock front and a magnetic field discontinuity. Prominent intensity spikes observed only below approximately 400 keV per charge for both protons and alpha particles several hours behind the shock front suggest that some fraction of the confined particles is accelerated by an energy per charge dependent process.

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

1974-01-01

398

Elementary Analysis of a Cometary Surface - the Alpha Particle X-Ray Spectrometer APXS on the Rosetta Mission to Comet 67P/CHURYUMOV-GERASIMENKO  

NASA Astrophysics Data System (ADS)

After a 10 years cruise the Rosetta probe will reach its final target in the middle of this year, the comet 67P/Churyumov-Gerasimenko. The main objectives of the mission are to gain more knowledge of the composition, the origin and formation of comets and the solar system. After extensive remote examination of the comet the lander Philae will be separated to land on the comet surface. It will start immediately examining the landing site with its scientific payload. A part of this payload is the APXS (Alpha Particle X-Ray Spectrometer), it will measure in situ the chemical composition of the comet's surface and its changes during the journey of the comet towards the sun. APXS is a combination of two spectrometers in one single instrument, being low in mass and power consumption. It will irradiate the cometary surface with Curium 244 sources, which are emitting alpha-particle and X-rays. In the alpha-mode the instrument uses alpha backscattering spectroscopy to detect lower Z elements like C, N and O and groups of elements with higher Z. In the X-ray mode alpha particle/X-ray induced X-ray spectroscopy (XRF) will allow the detection of most of the higher Z elements from Na up to Ni and above. Both modes will be always run in parallel allowing to determine lower and higher Z elements simultaneously. During the long duration travel to the comet checkouts and software updates of the Rosetta probe and its payload were performed at regular intervals. In recent 3 years the solar powered Rosetta probe had to pass a hibernation phase because of a long passage far away from the sun. After the successful wakeup in January 2014 an extensive test phase of all instruments and subsystems has to be performed, including the APXS. After the landing on the comet an intense long measurement phase of all instruments is planned, the First Science Sequence (FSS). It will be followed by a long term science phase (LTS), determined by periodical changes between measurements and forced breaks to recharge the lander batteries. During these operations the Rosetta probe will escort the comet and the lander along the comets trajectory around the sun. As long as possible APXS and the other instruments will continue to repeat their measurements to monitor the changes and rising activity of the comet. This will shed light on state, composition, evolution and the origin of comets and the solar system. Acknowledgements: This project is funded by the German Space Agency DLR under contracts 50 QP 0404 and 50 QP 0902. References: G. Klingelhöfer, J. Brückner, C. d'Uston, R. Gellert, and R. Rieder, The Rosetta Alpha Particle X-ray Spectrometer (APXS), Space Science Reviews, Vol.128 (2007) 383-396; doi:10.1007/s11214-006-9137-3

Schmanke, Dirk; Economou, Thanasis; Brueckner, Johannes; Gellert, Ralf; Rodionov, Daniel; Klingelhoefer, Goestar; Girones Lopez, Jordi; Uston, Lionel D.

399

High energy particles with negative and positive energies in the vicinity of black holes  

E-print Network

It is shown that the energy in the centre of mass frame of two colliding particles in free fall at any point of the ergosphere of the rotating black hole can grow without limit for fixed energy values of particles on infinity. The effect takes place for large negative values of the angular momentum of one of the particles. It occurs that the geodesics with negative energy in equatorial plane of rotating black holes cannot originate or terminate inside the ergosphere. Their length is always finite and this leads to conclusion that they must originate and terminate inside the gravitational radius of the ergosphere. The energy in the centre of mass frame of one particle falling into the gravitational radius and the other arriving from the area inside it is growing without limit on the horizon.

A. A. Grib; Yu. V. Pavlov

2014-01-02

400

High energy particles with negative and positive energies in the vicinity of black holes  

NASA Astrophysics Data System (ADS)

It is shown that the energy in the centre of mass frame of two colliding particles in free fall at any point of the ergosphere of the rotating black hole can grow without limit for fixed energy values of particles on infinity. The effect takes place for large negative values of the angular momentum of one of the particles. It occurs that the geodesics with negative energy in equatorial plane of rotating black holes cannot originate or terminate inside the ergosphere. Their length is always finite and this leads to conclusion that they must originate and terminate inside the gravitational radius of the ergosphere. The energy in the centre of mass frame of one particle falling into the gravitational radius and the other arriving from the area inside it is growing without limit on the horizon.

Grib, A. A.; Pavlov, Yu. V.

2014-07-01

401

High energy particles with negative and positive energies in the vicinity of black holes  

E-print Network

It is shown that the energy in the centre of mass frame of two colliding particles in free fall at any point of the ergosphere of the rotating black hole can grow without limit for fixed energy values of particles on infinity. The effect takes place for large negative values of the angular momentum of one of the particles. It occurs that the geodesics with negative energy in equatorial plane of rotating black holes cannot originate or terminate inside the ergosphere. Their length is always finite and this leads to conclusion that they must originate and terminate inside the gravitational radius of the ergosphere. The energy in the centre of mass frame of one particle falling into the gravitational radius and the other arriving from the area inside it is growing without limit on the horizon.

Grib, A A

2014-01-01

402

Energy-momentum balance in particle - domain wall perforating collision  

E-print Network

We investigate the energy-momentum balance in the perforating collision of a point particle with an infinitely thin planar domain wall within the linearized gravity in arbitrary dimensions. Since the metric of the wall increases with distance, the wall and the particle are never free, and their energy-momentum balance involves not only the instantaneous kinetic momenta, but also the non-local contribution of gravitational stresses. However, careful analysis shows that the stresses can be unambiguously divided between the colliding objects leading to definition of the gravitationally dressed momenta. These take into account for gravity in the same way as the potential energy does in the non-relativistic theory, but our treatment is fully relativistic. Another unusual feature of our problem is the non-vanishing flux of the total energy-momentum tensor through the lateral surface of the world tube. In this case the zero divergence of the energy-momentum tensor does not imply conservation of the total momentum de...

Gal'tsov, D V; Spiirin, P A

2014-01-01

403

Aspects of trapped confined alpha physics on TFTR  

SciTech Connect

The energy distributions and radial density profiles of the fast-confined trapped alpha particles in DT experiments on TFTR are being measured in the energy range 0.5 to 3.5 MeV using the Pellet Charge Exchange diagnostic developed in a collaboration involving General Atomics, the A.F. Ioffe Physical-Technical Institute, and the Princeton Plasma Physics Laboratory. A brief description of the measurement technique which involves active neutral particle analysis using the ablation cloud surrounding an injected lithium or pellet as the neutralizer is presented. In the core of quiescent TFTR discharges, measured alpha spectra are consistent with classical slowing down. Measured Doppler broadening of alphas near the birth energy is consistent with the effective temperature of interacting deuterium and tritium ions. Outside the core alpha energy spectra and density profiles are influenced by the magnetic field ripple and appear to be consistent with stochastic ripple diffusion. Sawtooth oscillations lead to the significant broadening of alpha density profiles. The experimental data are modeled using a Fokker-Planck Post TRANSP (FTTP) code which includes the effects of the classical slowing down, magnetic field ripple losses, and the sawtooth mixing of alpha particles. The comparison of the experimental data with the FPPT calculations shows that broadening of trapped alpha density profiles after the sawtooth crashes can be explained by the influence of poloidal electric field generated during the crashes.

Petrov, M.P. [A.F. Ioffe Physical-Technical Inst., St. Petersburg (Russian Federation); Gorelenkov, N.N. [TRINITI, Troitsk (Russian Federation); Budny, R.V.; Mansfield, D.K.; Medley, S.S. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Duong, H.H.; Fisher, R.K.; McChesney, J.M.; Parks, P.B. [General Atomics, San Diego, CA (United States)

1996-06-01

404

Lyman alpha radiation in external galaxies  

NASA Technical Reports Server (NTRS)

The Ly alpha line of atomic hydrogen is often a luminous component of the radiation emitted by distant galaxies. Except for those galaxies which have a substantial central source of non-stellar ionizing radiation, most of the Ly alpha radiation emitted by galaxies is generated within regions of the interstellar medium which are photoionized by starlight. Conversely, much of the energy radiated by photoionized regions is carried by the Ly alpha line. Only hot, massive stars are capable of ionizing hydrogen in the interstellar medium which surrounds them, and because such stars are necessarily short-lived, Ly alpha emission traces regions of active star formation. Researchers argue that the strength of the Ly alpha emission observed from external galaxies may be used to estimate quantitatively the dust content of the emitting region, while the Ly alpha line profile is sensitive to the presence of shock waves. Interstellar dust particles and shock waves are intimately associated with the process of star formation in two senses. First, both dust particles and shock waves owe their existence to stellar activity; second, they may both serve as agents which facilitate the formation of stars, shocks by triggering gravitational instabilities in the interstellar gas that they compress, and dust by shielding star-forming molecular clouds from the ionizing and dissociative effects of external UV radiation. By using Ly alpha observations as a probe of the dust content in diffuse gas at high redshift, we might hope to learn about the earliest epochs of star formation.

Neufeld, David A.; Mckee, Christopher F.

1990-01-01

405

Particles acceleration at relativistic shocks and high energy astrophysics  

NASA Astrophysics Data System (ADS)

High energy astrophysical phenomena stem from the generation of powerful flows emanating from Super Nova explosions, Gamma Ray Bursts, from ejections in the environment of Black Holes or Neutron Stars that lead to the formation of very strong shocks where particle acceleration takes place. The new developments in these issues are based on the interdependence between the shock structure, the generation of supra-thermal particles and the generation of turbulence. This view started with the studies of Super Nova Remnants, both with X-ray observations and with theoretical investigations, that concluded that the magnetic field is largely amplified by MHD instabilities in the precursor. It is thought, and numerical simulations support that view, that the penetration of supra-thermal particles in the shock precursor generates a magnetic turbulence which in turn produces the scattering process needed for particle acceleration through the Fermi process. This successful development inspired similar investigations for the termination shock of Gamma Ray Bursts. However in ultra-relativistic shocks, difficulties arise with the transverse magnetic field that puts a limitation to particle penetration upstream and that drags particles in the downstream flow and makes shock recrossing difficult. It turns out that only fast enough micro-turbulence can make the Fermi process operative when its level is high enough. This very challenging requirement can nevertheless be fulfilled naturally, as proved by recent numerical simulations. These points are briefly discussed in the presentation and astrophysical consequences are drawn. In particular, it is shown that ultra-relativistic shocks are very efficient electron accelerators and radiation emitters, but poor proton accelerators. It turns out that mildly relativistic shocks inside relativistic flows are better candidates for the generation of UHE-Cosmic Rays. The acceleration performance depends essentially of two parameters: the conversion factor of incoming energy at a shock into magnetic turbulence (this number is provided by the numerical simulations) and the jet power. The Pierre Auger Observatory suggests that the UHECR spectrum is enriched with heavy elements at high energies. What we know about the closest Radio-jets, as those of Centaurus A, together with the theoretical view, indicates that UHECRs can be accelerated up to a few Z × 10^{18} eV, and iron nuclei (Z=26) from these nearby radio galaxies can populate the UHE-Cosmic Rays, as long as they are not photo-dissociated. Nevertheless a significant proton contribution can come from GRB internal shocks as well.

Pelletier, G.; Lemoine, M.

2011-12-01

406

Theories of Variable Mass Particles and Low Energy Nuclear Phenomena  

NASA Astrophysics Data System (ADS)

Variable particle masses have sometimes been invoked to explain observed anomalies in low energy nuclear reactions (LENR). Such behavior has never been observed directly, and is not considered possible in theoretical nuclear physics. Nevertheless, there are covariant off-mass-shell theories of relativistic particle dynamics, based on works by Fock, Stueckelberg, Feynman, Greenberger, Horwitz, and others. We review some of these and we also consider virtual particles that arise in conventional Feynman diagrams in relativistic field theories. Effective Lagrangian models incorporating variable mass particle theories might be useful in describing anomalous nuclear reactions by combining mass shifts together with resonant tunneling and other effects. A detailed model for resonant fusion in a deuterium molecule with off-shell deuterons and electrons is presented as an example. Experimental means of observing such off-shell behavior directly, if it exists, is proposed and described. Brief explanations for elemental transmutation and formation of micro-craters are also given, and an alternative mechanism for the mass shift in the Widom-Larsen theory is presented. If variable mass theories were to find experimental support from LENR, then they would undoubtedly have important implications for the foundations of quantum mechanics, and practical applications may arise.

Davidson, Mark

2014-02-01

407

Hygroscopicity of particles generated from photooxidation of alpha-pinene under different oxidation conditions in the presence of sulfate seed aerosols.  

PubMed

Smog chamber experiments were conducted to investigate the hygroscopicity of particles generated from photooxidation of alpha-pinene/NO(x) with different sulfate seed aerosols or oxidation conditions. Hygroscopicity of particles was measured by a tandem differential mobility analyzer (TDMA) in terms of hygroscopic growth factor (Gf), with a relative humidity of 85%. With sulfate seed aerosols present, Gf of the aerosols decreased very fast before notable secondary organic aerosols (SOA) formation was observed, indicating a heterogeneous process between inorganic seeds and organic products might take place as soon as oxidation begins, rather than only happening after gas-aerosol partition of organic products starts. The final SOA-coated sulfate particles had similar or lower Gf than seed-free SOA. The hygroscopicity of the final particles was not dependent on the thickness but on the hygroscopicity properties of the SOA, which were influenced by the initial sulfate seed particles. In the two designed aging processes, Gf of the particles increased more significantly with introduction of OH radical than with ozone. However, the hygroscopicity of SOA was very low even after a long time of aging, implying that either SOA aging in the chamber was very slow or the Gf of SOA did not change significantly in aging. Using an aerosol composition speciation monitor (ACSM) and matrix factorization (PMF) method, two factors for the components of SOA were identified, but the correlation between SOA hygroscopicity and the proportion of the more highly oxidized factor could be either positive or negative depending on the speciation of seed aerosols present. PMID:24649698

Chu, Biwu; Wang, Kun; Takekawa, Hideto; Li, Junhua; Zhou, Wei; Jiang, Jingkun; Ma, Qinxing; He, Hong; Hao, Jiming

2014-01-01

408

H Ly-alpha transmittance of thin foils of C, Si/C, and Al/C for keV particle detectors  

NASA Technical Reports Server (NTRS)

A class of instruments designed for remote sensing of space plasmas by measuring energetic neutral atoms (ENA) uses a thin foil as both a signal generator and a light shield. An ENA imager must look directly at the ENA source region, which is also usually an intense source of H Ly-alpha (1216 A) photons. It is desirable to minimize the energy threshold for ENA detectors, at the same time maximizing the blocking of H Ly-alpha. Optimizing filter design to meet these two contrary requirements has led us to measure the transmittance of thin C, Si/C, and Al/C foils at H Ly-alpha. Our results indicate that (1) transmittance of less than 0.0007 can be achieved with 7 micro-g/sq cm Si on 1.7 micro-g/sq cm C; (2) an Si/C composite foil with a thin carbon layer is more effective in blocking UV radiation while having the lowest energy threshold of all the foils measured; and (3) transmittance of Si/C foils of known Si and C thicknesses cannot be accurately predicted, but must be measured.

Drake, V. A.; Sandel, B. R.; Jenkins, D. G.; Hsieh, K. C.

1992-01-01

409

PRECISE AND RAPID CALCULATIONS OF ENERGY AND PARTICLE FLUX FOR DETAILED BALANCE PHOTOVOLTAIC APPLICATIONS  

E-print Network

PRECISE AND RAPID CALCULATIONS OF ENERGY AND PARTICLE FLUX FOR DETAILED BALANCE PHOTOVOLTAIC problem that this paper addresses is the rapid and precise calculation of the energy and particle flux for photovoltaic efficiency limit calculations. The calculation of energy and particle flux is essential

Honsberg, Christiana

410

SPECTRAL THEORY OF DIFFERENTIAL OPERATORS AND ENERGY LEVELS OF SUBATOMIC PARTICLES  

E-print Network

SPECTRAL THEORY OF DIFFERENTIAL OPERATORS AND ENERGY LEVELS OF SUBATOMIC PARTICLES TIAN MA theory to study energy levels, corresponding to bounds states, for subatomic particles. We show that the energy levels of each subatomic particle are finite and discrete, and corresponds to negative eigenvalues

Wang, Shouhong

411

The variation of protons, alpha particles, and the magnetic field across the bow shock of Comet Halley  

NASA Astrophysics Data System (ADS)

Data from the Ion Mass Spectrometer and the magnetometer on the Giotto spacecraft are used to examine the structure of the inbound crossing of the Comet Halley bow shock on March 13, 1986. It is found that the velocity decrease, the field strength increase, and the heating of picked up cometary protons occurred over a broad region corresponding to several heavy-ion gyroradii. The solar-wind protons and alphas, on the other hand, were compressed and heated at a narrow structure on the leading edge of the broad shock region.

Neugebauer, M.; Neubauer, F. M.; Balsiger, H.; Fuselier, S. A.; Goldstein, B. E.; Goldstein, R.; Mariani, F.; Rosenbauer, H.; Schwenn, R.; Shelley, E. G.

1987-10-01

412

Auroral Lyman alpha and H2 bands from the giant planets. 2: Effect of the anisotropy of the precipitating particles on the interpretation of the 'color ratio'  

NASA Astrophysics Data System (ADS)

Previous spectral analyses have given evidence of collisionally excited Jovian and (at times) Saturnian H2 Werner bands being absorbed by hydrocarbons at the shortest wavelengths along the auroral ovals, and of a longitudinal dependence of this absorption in the Jovian aurorae. This 'color ratio' has been used to estimate the energy of the primary particles. In such estimates, particles are generally assumed to penetrate vertically into the atmosphere. However, the precipitating particle angular distribution is unknown, and a model developed for a diffuse aurora by Prange and Elkhamsi (1991), for instance, predicts quite different possible distributions. We consider here the influence of the angular distribution used in the model, and show that distributions peaking far from vertical may increase the energy derived from a given color ratio by as much as a factor of 3. We discuss previous interpretations of the color ratio longitudinal modulation (variation of the auroral atmosphere structure, or of the incident particle energy) in view of the subsequent increase in energy input. We argue that an interpretation in terms of energy variations only is not consistent with the energy available in the magnetosphere if the aurorae are diffuse, and we discuss this finding in the context of recent Hubble Space Telescope (HST) images.

Prange, Renee; Rego, Daniel; Gerard, Jean-Claude

1995-04-01

413

AN UPDATED {sup 6}Li(p, {alpha}){sup 3}He REACTION RATE AT ASTROPHYSICAL ENERGIES WITH THE TROJAN HORSE METHOD  

SciTech Connect

The lithium problem influencing primordial and stellar nucleosynthesis is one of the most interesting unsolved issues in astrophysics. {sup 6}Li is the most fragile of lithium's stable isotopes and is largely destroyed in most stars during the pre-main-sequence (PMS) phase. For these stars, the convective envelope easily reaches, at least at its bottom, the relatively low {sup 6}Li ignition temperature. Thus, gaining an understanding of {sup 6}Li depletion also gives hints about the extent of convective regions. For this reason, charged-particle-induced reactions in lithium have been the subject of several studies. Low-energy extrapolations of these studies provide information about both the zero-energy astrophysical S(E) factor and the electron screening potential, U{sub e} . Thanks to recent direct measurements, new estimates of the {sup 6}Li(p, {alpha}){sup 3}He bare-nucleus S(E) factor and the corresponding U{sub e} value have been obtained by applying the Trojan Horse method to the {sup 2}H({sup 6}Li, {alpha} {sup 3}He)n reaction in quasi-free kinematics. The calculated reaction rate covers the temperature window 0.01 to 2T{sub 9} and its impact on the surface lithium depletion in PMS models with different masses and metallicities has been evaluated in detail by adopting an updated version of the FRANEC evolutionary code.

Lamia, L.; Spitaleri, C.; Sergi, M. L. [Dipartimento di Fisica e Astronomia, Universita di Catania, I-95123 Catania (Italy); Pizzone, R. G.; Tumino, A.; La Cognata, M. [INFN-Laboratori Nazionali del Sud, I-95125 Catania (Italy); Tognelli, E.; Degl'Innocenti, S.; Prada Moroni, P. G. [Dipartimento di Fisica, Universita di Pisa, I-56127 Pisa (Italy); Pappalardo, L. [Dipartimento di Fisica e Scienze della Terra, Universita di Ferrara, I-44100 Ferrara (Italy)

2013-05-01

414

PARTICLE ENERGY SPECTRA AT TRAVELING INTERPLANETARY SHOCK WAVES  

SciTech Connect

We have searched for evidence of significant shock acceleration of He ions of {approx}1-10 MeV amu{sup -1} in situ at 258 interplanetary traveling shock waves observed by the Wind spacecraft. We find that the probability of observing significant acceleration, and the particle intensity observed, depends strongly upon the shock speed and less strongly upon the shock compression ratio. For most of the 39 fast shocks with significant acceleration, the observed spectral index agrees with either that calculated from the shock compression ratio or with the spectral index of the upstream background, when the latter spectrum is harder, as expected from diffusive shock theory. In many events the spectra are observed to roll downward at higher energies, as expected from Ellison-Ramaty and from Lee shock-acceleration theories. The dearth of acceleration at {approx}85% of the shocks is explained by (1) a low shock speed, (2) a low shock compression ratio, and (3) a low value of the shock-normal angle with the magnetic field, which may cause the energy spectra that roll downward at energies below our observational threshold. Quasi-parallel shock waves are rarely able to produce measurable acceleration at 1 AU. The dependence of intensity on shock speed, seen here at local shocks, mirrors the dependence found previously for the peak intensities in large solar energetic-particle events upon speeds of the associated coronal mass ejections which drive the shocks.

Reames, Donald V., E-mail: dvreames@umd.edu [Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States)

2012-09-20

415

Induced radioactivity in and around high-energy particle accelerators.  

PubMed

Particle accelerators and their surroundings are locations of residual radioactivity production that is induced by the interaction of high-energy particles with matter. This paper gives an overview of the principles of activation caused at proton accelerators, which are the main machines operated at Conseil Européen pour la Recherche Nucléaire. It describes the parameters defining radio-nuclide production caused by beam losses. The second part of the paper concentrates on the analytic calculation of activation and the Monte Carlo approach as it is implemented in the FLUKA code. Techniques used to obtain, on the one hand, estimates of radioactivity in Becquerel and, on the other hand, residual dose rates caused by the activated material are discussed. The last part of the paper focuses on experiments that allow for benchmarking FLUKA activation calculations and on simulations used to predict activation in and around high-energy proton machines. In that respect, the paper addresses the residual dose rate that will be induced by proton-proton collisions at an energy of two times 7 TeV in and around the Compact Muon Solenoid (CMS) detector. Besides activation of solid materials, the air activation expected in the CMS cavern caused by this beam operation is also discussed. PMID:21697180

Vincke, Helmut; Theis, Chris; Roesler, Stefan

2011-07-01

416

High energy particles in solar flares: observations, mechanisms and transport  

NASA Astrophysics Data System (ADS)

We review the observations bearing on electron and ion acceleration in solar flares, and the key challenges they pose to theory. Solar flare hard X-rays testify to the presence of accelerated electrons, with energies extending from thermal to the MeV range and possibly beyond. A variety of line and continuum signatures in the gamma-ray range reveal properties of energetic ions, from MeV to GeV energies. We review the ideas of the thick target and local reacceleration models for source regions and their implications for overall pictures of the flare energy release. Attainment of the highest particle energies poses a different sort of challenge to theory. Using the nuclear transport code FLUKA we show examples of the transport and radiation of ~GeV energy ions and their secondaries, and consider some of the questions raised by long-lasting high-energy continuum after flares. The further constraints offered by radio and sub-mm observations are discussed, sub-mm in particular both posing new questions and offering new insights. We conclude by identifying a few key questions for future flare studies.

MacKinnon, Alexander

417

Squeezed States and Particle Production in High Energy Collisions  

NASA Technical Reports Server (NTRS)

Using the 'quantum optical approach' we propose a model of multiplicity distributions in high energy collisions based on squeezed coherent states. We show that the k-mode squeezed coherent state is the most general one in describing hadronic multiplicity distributions in particle collision processes, describing not only p(bar-p) collisions but e(+)e(-), vp and diffractive collisions as well. The reason for this phenomenological fit has been gained by working out a microscopic theory in which the squeezed coherent sources arise naturally if one considers the Lorentz squeezing of hadrons and works in the covariant phase space formalism.

Bambah, Bindu A.

1996-01-01

418

The role of nonhomologous end joining and homologous recombination in the clonogenic bystander effects of mammalian cells after exposure to counted 10 MeV protons and 4.5 MeV alpha-particles of the PTB microbeam.  

PubMed

We have studied the dependence of clonogenic bystander effects on defects in the pathways of DNA double-strand break (DSB) repair and on linear energy transfer (LET). The single-ion microbeam of the Physikalisch-Technische Bundesanstalt (PTB) was used to irradiate parental Chinese hamster ovary cells or derivatives deficient in nonhomologous end joining (NHEJ) or homologous recombination (HR) in the G1-phase of the cell cycle. Cell nuclei were targeted with 10 MeV protons (LET = 4.7 keV/microm) or 4.5 MeV alpha-particles (LET = 100 keV/microm). During exposure, the cells were confluent, allowing signal transfer through both gap junctions and diffusion. When all cell nuclei were targeted with 10 MeV protons, approximately exponential survival curves were obtained for all three cell lines. When only 10% of all cell nuclei were targeted, a significant bystander effect was observed for parental and HR-deficient cells, but not for NHEJ-deficient cells. For all three cell lines, the survival data after exposure of all cell nuclei to 4.5 MeV alpha-particles could be fitted by exponential curves. When only 10% of all cell nuclei were targeted, significant bystander effects were obtained for parental and HR-deficient cells, whereas for NHEJ-deficient cells a small, but significant, bystander effect was observed only at higher doses. The data suggest that bystander cell killing is a consequence of un- or misrejoined DSB which occur in bystander cells during the S-phase as a result of the processing of oxidative bistranded DNA lesions. The relative contributions of NHEJ and HR to the repairing of DSB in the late S/G2-phase may affect clonogenic bystander effects. PMID:18688633

Frankenberg, Dieter; Greif, Klaus-D; Beverung, Wolfgang; Langner, Frank; Giesen, Ulrich

2008-11-01

419

Particle description of zero energy vacuum. II. Basic vacuum systems  

E-print Network

We describe vacuum as a system of virtual particles, some of which have negative energies. Any system of vacuum particles is a part of a keneme, i.e. of a system of n particles which can, without violating the conservation laws, annihilate in the strict sense of the word (transform into nothing). A keneme is a homogeneous system, i.e. its state is invariant by all transformations of the invariance group. But a homogeneous system is not necessarily a keneme. In the simple case of a spin system, where the invariance group is SU(2), a homogeneous system is a system whose total spin is unpolarized; a keneme is a system whose total spin is zero. The state of a homogeneous system is described by a statistical operator with infinite trace (von Neumann), to which corresponds a characteristic distribution. The characteristic distributions of the homogeneous systems of vacuum are defined and studied. Finally it is shown how this description of vacuum can be used to solve the frame problem posed in (I).

J. Y. Grandpeix; F. Lurcat

2001-06-25

420

Development of a He{sup -} and He{sup 0} beam source for alpha particle measurement in a burning plasma  

SciTech Connect

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{sup -} beam was accelerated to 157 keV. Finally, He{sup 0} beam was successfully produced after the flight in the drift-tube through the auto-electron-detachment process from He{sup -} to He{sup 0}. A neutral beam detector using a pyroelectric device was also developed to measure He{sup 0} 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. [Tohoku University, Aoba, Sendai 980-8579 (Japan); Yamaoka, H. [Harima Institute, RIKEN, Sayo, Hyogo 679-5148 (Japan); Wada, M. [Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan)

2012-02-15