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1

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; Schöffler, Markus; Trinter, Florian; Waitz, Markus; Voigtsberger, Jörg; Sann, Hendrik; Meckel, Moritz; Stuck, Christian; Lenz, Ute; Odenweller, Matthias; Neumann, Nadine; Schössler, 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-Böcking, Horst; Dörner, Reinhard

2011-01-01

2

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

3

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

4

Nuclear reactions induced by high-energy alpha particles  

NASA Technical Reports Server (NTRS)

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

Shen, B. S. P.

1974-01-01

5

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

E-print Network

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

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

2004-09-20

6

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

SciTech Connect

The redistribution of alpha particles due to internal kink modes is studied. The exact particle trajectories in the total fields, equilibrium plus perturbation, are calculated. The equilibrium has circular cross section and the plasma parameters are similar to those expected in ITER. The alpha particles are initially distributed according to a slowing down distribution function and have energies between 18?keV and 3.5?MeV. The (1, 1), (2, 2), and (2, 1) modes are included and the effect of changing their amplitude and frequency is studied. When only the (1, 1) mode is included, the spreading of high energy (E?1?MeV) alpha particles increases slowly with the energy and mode frequency. At lower energies, the redistribution is more sensitive to the mode frequency and particle energy. When a (2, 1) mode is added, the spreading increases significantly and particles can reach the edge of the plasma. Trapped particles are the most affected and the redistribution parameter can have maxima above 1?MeV, depending on the mode frequency. These results can have important implications for ash removal.

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

2014-08-15

7

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

8

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.

9

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

SciTech Connect

A preliminary procedure for alpha energy analysis of radon and progeny using Nuclear Track Methodology (NTM) is described in this paper. The method is based on the relationship between alpha-particle energies deposited in polycarbonate material (CR-39) and the track size developed after a well-established chemical etching process. Track geometry, defined by parameters such as major or minor diameters, track area and overall track length, is shown to correlate with alpha-particle energy over the range 6.00 MeV (218Po) to 7.69 MeV (214Po). Track features are measured and the data analyzed automatically using a digital imaging system and commercial PC software. Examination of particle track diameters in CR-39 exposed to environmental radon reveals a multi-modal distribution. Locations of the maxima in this distribution are highly correlated with alpha particle energies of radon daughters, and the distributions are sufficiently resolved to identify the radioisotopes. This method can be useful for estimating the radiation dose from indoor exposure to radon and its progeny.

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

2008-01-01

10

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

SciTech Connect

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

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

2009-12-15

11

Alpha particle emitters in medicine  

SciTech Connect

Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 ({sup 211}At) and natural bismuth-212 ({sup 212}Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 ({sup 223}Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs.

Fisher, D.R.

1989-09-01

12

Energy distribution of ternary {alpha} particles in spontaneous fission of {sup 252}Cf  

SciTech Connect

The energy distribution of the ternary {alpha} particles in spontaneous fission of {sup 252}Cf was measured. For the first time an energy threshold as low as 1 MeV was reached. The experiment used an array of unshielded silicon detectors measuring energy and time-of-flight (TOF) of ternary particles in coincidence with fission fragments. The TOF resolution of the system was sufficient for clear separation of {sup 6}He and tritons from {sup 4}He. The statistics were adequate to extract the {sup 6}He/{sup 4}He yield ratio. For both {sup 4}He and {sup 6}He, an excess in the yield (as compared to a Gaussian shape) was observed at energies below 9 MeV. The measured ternary {alpha} spectrum was corrected for the distortion induced by the detection geometry covering equatorial particle emission only. The emission angle was found to affect mainly the width of the energy distribution by up to 1 MeV.

Mutterer, M.; Kalben, J. von [Institute of Nuclear Physics, University of Technology, Darmstadt (Germany); Kopatch, Yu. N. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Yamaledtinov, S. R.; Lyapin, V. G.; Sillanpaeae, M.; Trzaska, W. H. [Department of Physics, University of Jyvaeskylae, Jyvaeskylae (Finland); Khlebnikov, S. V.; Tyurin, G. P. [V. G. Khlopin Radium Institute, St. Petersburg (Russian Federation)

2008-12-15

13

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

ERIC Educational Resources Information Center

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

Ouseph, P. J.; Mostovych, Andrew

1978-01-01

14

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

SciTech Connect

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

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

2000-04-01

15

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

PubMed

Energy deposition and cellular radiation effects arising from the interaction of single 218Po and 214Po alpha particles with basal and secretory cell nuclei were simulated for different target cell depths in the bronchial epithelium of human airway generations 2, 4, 6, and 10. To relate the random chord lengths of alpha particle tracks through spherical cell nuclei to the resulting biological endpoints, probabilities per unit track length for different cellular radiation effects as functions of LET were derived from in vitro experiments. The radiobiological data employed in the present study were inactivation and mutation (mutant frequency at the HPRT gene) in V79 Chinese hamster cells and inactivation and transformation in C3H 10T1/2 cells. Based on computed LET spectra and relative frequencies of target cells, probabilities for transformation, mutation, and cell killing in basal and secretory cells were computed for a lifetime exposure of 20 WLM. While predicted transformation probabilities were about two orders of magnitude higher than mutation probabilities, they were still about two orders of magnitude lower than inactivation probabilities. Furthermore transformation probabilities for basal cells are generally higher than those for secretory cells, and 214Po alpha particles are primarily responsible for transformations in bronchial target cells. PMID:10749522

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

2000-04-01

16

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

NASA Astrophysics Data System (ADS)

The only two previous measurements of the energies of alpha particles emitted by 236Pu were relative determinations. They were in fair agreement with each other, except for the intensity ratios of the two strong lines. We now report an absolute energy measurement which was carried out using the 180° uniform-field magnetic spectrometer at BIPM on four sources prepared at AERE, Harwell with material formed by the reaction 238U( p, 3 n) 236Npå236Npå236Pu . The alpha particles were detected with aid of Kodak LR 115 (Type 2) cellulose-nitrate films which had considerable advantages over nuclear-track plates. Etching for seven hours in dilute NaOH at 40°C produced only weak and sufficiently reproducible distortions of the films reducing uncertainties to at most 50 eV. From six spectra the following mean values of particle energy E? and relative intensity I? were obtained: E? = (5767.66±0.08) keV, I? = (69.26±0.45) %; E? = (5721000±0.10) keV, I? = (30.56±0.45) %.

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

1984-06-01

17

Track etch parameters in CR-39 detectors for proton and alpha particles of different energies  

NASA Astrophysics Data System (ADS)

Etchable track formation in poly-allyl-diglycol carbonate (commercially known as CR-39) track detectors is a process directly related to density of damage produced along the charged particle path; it requires knowledge of the variation of bulk etch rate Vb and track etch rate Vt as a function of the initial particle energy and etching time. In this paper, the track etch parameters have been experimentally measured in CR-39 detectors irradiated with proton and alpha particles in the energy ranges 0.5-2.5 MeV and 1-5.8 MeV, respectively. Detectors were chemically etched in a hot hydroxide potassium solution for periods ranging from 1 to 32 h. The dependence of track diameters on the energy values, the correlation between the maximum track diameter and the Bragg peak and the variation of the track etch rate Vt as a function of the incident particle energy for different etching times are presented and discussed. Critical values of detection angles and optimal energies of the incident protons on the CR-39 have been deduced. The present results are compared with those given in recently published works.

Lounis, Z.; Djeffal, S.; Morsli, K.; Allab, M.

2001-09-01

18

Range of Medium and High Energy Protons and Alpha Particles in NaI Scintillator  

NASA Astrophysics Data System (ADS)

We have calculated the range of protons and alpha particles in NaI scintillator which is a commonly used substance in scintillation detector manufacturing. The electronic stopping power of protons and alpha particles in NaI is calculated first by using the theoretical formulation of Montenegro et al. The range calculation has been performed by applying a technique that we developed in the earlier works. The results are compared with Monte Carlo simulation program SRIM2003 and PRAL. It is found that the obtained results are in satisfactory agreement with the literature.

Kabadayi, Oe.

2006-06-01

19

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

20

Long range alpha particle detector  

DOEpatents

An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

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

1993-02-02

21

Long range alpha particle detector  

DOEpatents

An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

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

1993-01-01

22

Studies of mass and energy correlations in thermal neutron fission of U-235 accompanied by long range alpha particles  

Microsoft Academic Search

Several characteristics of fission accompanied by long range alpha particles (LRA) have been studied in the thermal neutron\\u000a induced fission of235U. The kinetic energies of fission fragments and the LRA were measured with a back-to-back ionization chamber and semiconductor\\u000a detectors respectively. The kinetic energies of the two fragments and the LRA in LRA fission, along with the energies of pair

R K Choudhury; S S Kapoor; D M Nadkarni; P N Rama Rao; S R Srinivas Murthy

1976-01-01

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

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

E-print Network

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

Typel, Stefan

2014-01-01

25

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

26

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

27

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

28

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

PubMed

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

Sohrabi, M; Ramezani, V

2014-10-01

29

DNA complex lesions induced by protons and alpha-particles: track structure characteristics determining linear energy transfer and particle type dependence.  

PubMed

The yield of DNA double-strand breaks (dsb) and DNA complex lesions induced by protons and alpha-particles of various energies was simulated using a Monte Carlo track structure code (MOCA15) and a simple model of the DNA molecule. DNA breaks of different complexity were analysed. The linear energy transfer (LET) and particle-type dependence of lesions of higher complexity seems to confirm the importance of clustered damage in DNA as a relevant step leading to biological endpoints such as cell inactivation. The detailed structure of proton and alpha-particle tracks was analysed to identify the main characteristics possibly responsible for such a dependence. The role of the primary ion and of its secondary electrons in inducing dsb and complex lesions is described, showing that the relative contribution of secondary electron tracks alone in inducing clustered lesions is almost negligible at high LET, but tends to dominate below = 10 keV/micron. This is consistent with the observed similar effectiveness of low-LET fast particle radiation and sparsely ionizing radiation such as x-rays. The dependence on LET and particle type is mainly due to energy deposition events of the primary ion together with short range electrons surrounding the ion track; the yield of complex lesions due to secondary electron tracks alone is substantially LET independent. The radial distributions of the energy contributing to the induction of complex lesions were analyzed and compared with the radial distributions of energy deposition of the full tracks. The results suggest that the stochastic behaviour (i.e. cluster properties) of the energy deposition pattern within a radius of a few nanometers around the ion track plays a relevant role in determining the biological radiation effectiveness. PMID:9271797

Ottolenghi, A; Merzagora, M; Paretzke, H G

1997-06-01

30

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

PubMed

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

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

2013-09-01

31

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

32

Alpha particle diagnostics using impurity pellet injection  

SciTech Connect

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

Fisher, R.K.; McChesney, J.M.; Howald, A.W.; Parks, P.B. (General Atomics, San Diego, CA (United States)); Snipes, J.A.; Terry, J.L.; Marmar, E.S. (Massachusetts Inst. of Tech., Cambridge, MA (United States)); Zweben, S.J.; Medley, S.S. (Princeton Univ., NJ (United States). Plasma Physics Lab.)

1992-05-01

33

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

E-print Network

detectors are passivated implanted planar silicon (PIPS) detectors with areas of 300 mm2 . Energy of the alpha spectroscopy system and was facing up towards the detector. A collimator made of acrylic resin by the detector. A ruler attached to the holder was provided with the alpha spectroscopy system to give

Yu, K.N.

34

Alpha particle condensation and nuclear rainbow scattering  

E-print Network

It is shown that a dilute property of an $\\alpha$ particle condensate can be seen in the Airy structure of nuclear rainbow and prerainbow scattering. The dilute property of the Hoyle state of $^{12}$C with a developed $\\alpha$ cluster structure is discussed by studying refractive $^3$He+$^{12}$C and $\\alpha$+$^{12}$C scattering.

S Ohkubo; Y Hirabayashi

2011-02-09

35

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

E-print Network

and CaO targets of about 0.5 mg/cm' were used and different targets were always cross-checked against a CaO standard. Absolute normaliza- tions were also checked by comparing forward angle, low-energy a scattering with the Ruther- ford formula...

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

1972-01-01

36

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

37

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

38

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

39

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

40

Control of alpha-particle transport by ion cyclotron resonance heating  

SciTech Connect

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

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

1990-12-01

41

Alpha-Particle Condensation in Nuclear Systems  

E-print Network

The onset of quartetting, i.e. alpha-particle condensation, in symmetric nuclear matter is studied with the help of an in-medium modified four nucleon equation. It is found that at very low density quartetting wins over pairing, because of the strong binding of the alpha-particles. The critical temperature can reach values up to around 6 MeV. Also the disappearance of alpha-particles with increasing density, i.e. the Mott transition, is investigated. In finite nuclei the Hoyle state, that is the 0_2^+ of 12C, is identified as an "alpha-particle condensate" state. It is conjectured that such states also exist in heavier n alpha-nuclei, like 16O, 20Ne, etc. For instance the 6-th 0^+ state of 16O at 15.1 MeV is identified from a theoretical analysis as being a strong candidate for an alpha condensate state. Exploratory calculations are performed for the density dependence of the alpha condensate fraction at zero temperature to address the suppression of the four-particle condensate below nuclear-matter density. Possible quartet condensation in other systems is discussed briefly

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

2008-09-03

42

Alpha particle haloes in chlorite and cordierite  

Microsoft Academic Search

Summary  Effects of the impact of natural long-term irradiation with alpha particles in one chamosite and one cordierite sample were\\u000a characterised in detail using electron microprobe, Raman microprobe, optical absorption spectroscopy (cordierite only), and\\u000a transmission electron microscopy (TEM; cordierite only) analysis. In both cases, the impact of 4He cores (alpha particles) that were emitted from actinide-bearing mineral inclusions has caused the

L. Nasdala; M. Wildner; R. Wirth; N. Groschopf; D. C. Pal; A. Möller

2006-01-01

43

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

44

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

45

Alpha-particle condensation in excited 12C  

E-print Network

The fragmentation of quasi-projectiles from the nuclear reaction $^{40}Ca$+$^{12}C$ at 25 MeV/nucleon was used to produce excited states candidates to $\\alpha$-particle condensation. The methodology relies on high granularity 4$\\pi$ detection coupled to correlation function techniques. Under the assumption that the equality among the kinetic energies of the emitted $\\alpha$-particles and the emission simultaneity constitutes a reliable fingerprint of $\\alpha$ condensation, we identify several tens of events corresponding to the deexcitation of the Hoyle state of $^{12}$C which fulfill the condition.

Ad. R. Raduta; B. Borderie; E. Geraci; N. Le Neindre; P. Napolitani; M. F. Rivet; R. Alba; F. Amorini; G. Cardella; M. Chatterjee; E. De Filippo; D. Guinet; P. Lautesse; E. La Guidara; G. Lanzalone; G. Lanzano; I. Lombardo; O. Lopez; C. Maiolino; A. Pagano; S. Pirrone; G. Politi; F. Porto; F. Rizzo; P. Russotto; J. P. Wieleczko

2010-04-19

46

Actinium-225 in targeted alpha-particle therapeutic applications.  

PubMed

Alpha particle-emitting isotopes are being investigated in radioimmunotherapeutic applications because of their unparalleled cytotoxicity when targeted to cancer and their relative lack of toxicity towards untargeted normal tissue. Actinium- 225 has been developed into potent targeting drug constructs and is in clinical use against acute myelogenous leukemia. The key properties of the alpha particles generated by 225Ac are the following: i) limited range in tissue of a few cell diameters; ii) high linear energy transfer leading to dense radiation damage along each alpha track; iii) a 10 day halflife; and iv) four net alpha particles emitted per decay. Targeting 225Ac-drug constructs have potential in the treatment of cancer. PMID:22202153

Scheinberg, David A; McDevitt, Michael R

2011-10-01

47

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

48

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

SciTech Connect

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

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

1990-02-01

49

Alternating current long range alpha particle detector  

DOEpatents

An alpha particle detector, utilizing alternating currents, which is capable of detecting alpha particles from distinct sources. The use of alternating currents allows use of simpler ac circuits which, in turn, are not susceptible to dc error components. It also allows the benefit of gas gain, if desired. In the invention, a voltage source creates an electric field between two conductive grids, and between the grids and a conductive enclosure. Air containing air ions created by collision with alpha particles is drawn into the enclosure and detected. In some embodiments, the air flow into the enclosure is interrupted, creating an alternating flow of ions. In another embodiment, a modulated voltage is applied to the grid, also modulating the detection of ions.

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

1993-02-16

50

Alternating current long range alpha particle detector  

DOEpatents

An alpha particle detector, utilizing alternating currents, whcih is capable of detecting alpha particles from distinct sources. The use of alternating currents allows use of simpler ac circuits which, in turn, are not susceptible to dc error components. It also allows the benefit of gas gain, if desired. In the invention, a voltage source creates an electric field between two conductive grids, and between the grids and a conductive enclosure. Air containing air ions created by collision with alpha particles is drawn into the enclosure and detected. In some embodiments, the air flow into the enclosure is interrupted, creating an alternating flow of ions. In another embodiment, a modulated voltage is applied to the grid, also modulating the detection of ions.

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

1993-01-01

51

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

52

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

53

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

54

Alpha-particle-induced soft errors in dynamic memories  

Microsoft Academic Search

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

T. C. May; M. H. Woods

1979-01-01

55

Mechanism and Rate of Long-Range alpha-Particle Emission in Fission  

Microsoft Academic Search

The statistical theory of fission has been used in previous works to calculate the energy and angular distributions of the long-range alpha particle emitted in fission. It is now applied to calculate the probability of long-range alpha-particle-accompanied fission relative to binary fission. For thermal-neutron fission of U235 the calculated rate is 1 alpha-particle-accompanied fission in 461 binary fissions, which agrees

Peter Fong

1971-01-01

56

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

Microsoft Academic Search

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

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

2005-01-01

57

Alpha particle losses from Tokamak Fusion Test Reactor deuterium-tritium plasmas  

SciTech Connect

Because alpha particle losses can have a significant influence on tokamak reactor viability, the loss of deuterium-tritium alpha particles from the Tokamak Fusion Test Reactor (TFTR) has been measured under a wide range of conditions. In TFTR, first orbit loss and stochastic toroidal field ripple diffusion are always present. Other losses can arise due to magnetohydrodynamic instabilities or due to waves in the ion cyclotron range of frequencies. No alpha particle losses have yet been seen due to collective instabilities driven by alphas. Ion Bernstein waves can drive large losses of fast ions from TFTR, and details of those losses support one element of the alpha energy channeling scenario.

Darrow, D.S.; Zweben, S.J. [Princeton Univ., NJ (United States). Plasma Physics Lab.] [Princeton Univ., NJ (United States). Plasma Physics Lab.; Batha, S. [Fusion Physics and Technology, Torrance, CA (United States)] [Fusion Physics and Technology, Torrance, CA (United States)

1996-01-01

58

Absolute measurement of the energies of alpha-particles emitted by sources of 252Cf and 227Ac  

NASA Astrophysics Data System (ADS)

Absolute energy measurements of ?-particles from sources of 252Cf and 227Ac by magnetic spectrometry are described. The sources were prepared at AERE, Harwell and measurements carried out using the 180° uniform-field spectrometer at BIPM followed the well-established technique applying cellulose-nitrate films (Kodak LR115) for track detection. The following values and uncertainties were obtained: 252Cf: E ? 0 = (6118.24±0.04) keV, E ? 43 = (6075.77±0.11) keV; 250Cf: E ? 0 = (6030.35±0.20) keV; 227Ac: E ? 0 = (4953.37±0.14) kev, E ? 13 = (4940.8±0.8) keV.

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

1986-12-01

59

Effect of alpha particles on bacteriophage T4Br(+)  

SciTech Connect

The effects of heavy particle radiation, which is believed to be responsible for the high relative biological effectiveness (RBE) of space hadrons, on bacteriophages are investigated. Dry film cultures of bacteriophage T4 were irradiated with 5.3 MeV Po-210 alpha particles to doses from 5 to 60 Gray, and compared with cultures irradiated by Co-60 gamma radiation. Examination of the exponential dose-response curves for bacteriophage survival indicates an RBE of 4.68 for the alpha particles. The r-mutation frequency per 10,000 surviving phages is found to peak at 7.1 at doses between 65 and 85 Gray for gamma radiation, however it declines steadily from a level of 10.2 per 10,000 survivors with increasing dose of alpha radiation. Comparison of the mutation frequencies at the same levels of lethality and the spectra of mutations produced by the two types of radiation indicates alpha and gamma radiation to differ as well in the mechanisms of mutation production. It is concluded that the observed high RBE of space hadrons cannot be explained by the presence of high-energy particles in the secondary radiation. 13 references.

Leonteva, G.A.; Akoev, I.G.; Grigorev, A.E.

1983-01-01

60

Gamma-Rays of Lithium and Fluorine Under Alpha-Particle Bombardment  

Microsoft Academic Search

The energies of the gamma-rays emitted from lithium and fluorine under bombardment by polonium alpha-particles are determined, and their variation with the energy of the incident particles is studied. In the case of lithium no change in gamma-ray energy is observed as the range of the incident alpha-particles is reduced from 3.9 cm to 2.5 cm. This is taken to

Karl C. Speh

1936-01-01

61

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

NASA Astrophysics Data System (ADS)

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

Vargas, M. Jurado; Timón, A. Fernández

2015-01-01

62

Fission studies with 140 MeV {alpha} particles  

SciTech Connect

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

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

2009-09-15

63

The Ionization and Stopping Power of Various Gases for Alpha-Particles from Polonium: I  

Microsoft Academic Search

Determinations of the differential ionizations and stopping powers of hydrogen, neon, nitrogen, oxygen, argon, and methyl iodide have been made at intervals along the range of alpha-particles from polonium. From the results of these and other determinations it is shown that the energy lost by the alpha-particle per ion is nearly independent of the speed throughout the range. There are

G. E. Gibson; E. W. Gardiner

1927-01-01

64

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

65

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

PubMed

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

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

2008-09-01

66

Simulation of Alpha Particles in Rotating Plasma Interacting with a Stationary Ripple  

SciTech Connect

Superthermal ExB rotation can provide magnetohydrodynamic (MHD) stability and enhanced confinement to axisymmetric mirrors. However, the rotation speed has been limited by phenomena at end electrodes. A new prediction is that rotation might instead be produced using a magnetic ripple and alpha particle kinetic energy, in an extension of the alpha channeling concept. The interaction of alpha particles with the ripple results in visually interesting and practically useful orbits.

Abraham J. Fetterman and Nathaniel J. Fisch

2011-01-11

67

Alpha particle loss in the TFTR DT experiments  

SciTech Connect

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

Zweben, S.J.; Darrow, D.S.; Herrmann, H.W. [and others

1995-01-01

68

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

69

Scattering of alpha particles by 22Ne  

Microsoft Academic Search

Differential cross sections at a few angles for 22Ne(alpha,alphai)22Ne are reported for alphai=alpha0, alpha1, and alpha2 mainly in 10 keV steps for 22alpha,alpha), 13.4<=Ealpha (MeV)<=20,8, elastic and inelastic (2+, 1.27 MeV and 4+, 3.36 MeV). Measured sigma(theta,Ealpha) at one or two angles.

C. A. Davis

1981-01-01

70

A new alpha-particle irradiator with absolute dosimetric determination.  

PubMed

A new experimental setup for uniform alpha-particle irradiation of cells in vitro is described. The alpha-particle irradiator is based on a radioactive (212)Pb/(212)Bi source. In the experimental setup proposed, cells are grown directly on a polylysine-coated track-etch material that forms the base of custom-made cell dishes. Alpha-particle irradiation is done through the base of the dish. Immediately prior to irradiation, the cell dish is scanned under a microscope, and images of cells with the corresponding coordinates are saved. After irradiation and after the biological end point under study has been determined, the cell dish is etched to develop alpha-particle tracks in the dish base. A microscope image series of alpha-particle track images is obtained by accurately revisiting every original (preirradiation) cell position in the track-etched dish. The number of alpha-particle traversals of each individual cell is scored by mapping images of alpha-particle tracks onto the images of cells recorded prior to irradiation. The uncertainty of the alpha-particle hit determination is 0.9 microm. The procedure described thus presents a method for radiobiological experiments with absolute, rather than statistical, cell dosimetry. PMID:10630972

Soyland, C; Hassfjell, S P; Steen, H B

2000-01-01

71

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

SciTech Connect

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

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

2004-05-13

72

Accurate determination of lithium, boron, fluorine and sodium in some matrices using low energy alpha-particles induced gamma-rays  

Microsoft Academic Search

A method is described for analyzing some light elements with high accuracy. Prompt gamma-ray spectrometry with 3.5 MeV alpha-particles\\u000a from a Van de Graaff accelerator was used: this technique is non-destructive, rapid and experimentally simple. Sensitivities\\u000a are indicated and factors affecting the accuracy of analysis are considered. A range of different materials has been analyzed\\u000a and analytical results are presented.

B. Borderie; M. Basutcu; J. N. Barrandon; J. L. Pinault

1980-01-01

73

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

SciTech Connect

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

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

1992-07-01

74

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

SciTech Connect

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

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

1992-07-01

75

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

Microsoft Academic Search

The spectra of monoenergetic alpha particles exhibit a well known asymmetric shape when measured with silicon detectors. The processes are described which determine the response of silicon detectors to alpha particles, particularly the energy dependence of the line shape. In this work particle implanted and passivated silicon (PIPS) detectors are assumed to have a thin dead layer at the front

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

1994-01-01

76

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

77

Preliminary experiments: High-energy alpha PIXE in archaeometry  

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

78

Alpha particle losses from Tokamak Fusion Test Reactor deuterium{endash}tritium plasmas  

SciTech Connect

Because alpha particle losses can have a significant influence on tokamak reactor viability, the loss of deuterium{endash}tritium alpha particles from the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire {ital et} {ital al}., Phys. Plasmas {bold 2}, 2176 (1995)] has been measured under a wide range of conditions. In TFTR, first orbit loss and stochastic toroidal field ripple diffusion are always present. Other losses can arise due to magnetohydrodynamic instabilities or due to waves in the ion cyclotron range of frequencies. No alpha particle losses have yet been seen due to collective instabilities driven by alphas. Ion Bernstein waves can drive large losses of fast ions from TFTR, and details of those losses support one element of the alpha energy channeling scenario. {copyright} {ital 1996 American Institute of Physics.}

Darrow, D.S.; Zweben, S.J.; Batha, S.; Budny, R.V.; Bush, C.E.; Chang, Z.; Cheng, C.Z.; Duong, H.H.; Fang, J.; Fisch, N.J.; Fischer, R.; Fredrickson, E.D.; Fu, G.Y.; Heeter, R.F.; Heidbrink, W.W.; Herrmann, H.W.; Herrmann, M.C.; Hill, K.; Jaeger, E.F.; James, R.; Majeski, R.; Medley, S.S.; Murakami, M.; Petrov, M.; Phillips, C.K.; Redi, M.H.; Ruskov, E.; Spong, D.A.; Strait, E.J.; Taylor, G.; White, R.B.; Wilson, J.R.; Wong, K.; Zarnstorff, M.C. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States)

1996-05-01

79

Alpha particle diagnostics using impurity pellet injection (invited)  

SciTech Connect

We have proposed using impurity pellet injection to measure the energy distribution of the fast confined alpha particles in a reacting plasma (R. K. Fisher {ital et} {ital al}., Fusion Technol. {bold 13}, 536 (1988)). The ablation cloud surrounding the injected pellet is thick enough that an equilibrium fraction {ital F}{sup {infinity}}{sub 0}({ital E}) of the incident alphas should be neutralized as they pass through the cloud. By observing neutrals created in the large spatial region of the cloud which is expected to be dominated by the heliumlike ionization state, e.g., Li{sup +} ions, we can determine the incident alpha distribution {ital dn}{sub He}{sup 2+}/{ital dE} from the measured energy distribution of neutral helium atoms {ital dn}{sub He{sup 0}}/{ital dE} using {ital dn}{sub He{sup 0}}/{ital dE} = {ital dn}{sub He}{sup 2+}/{ital dE}{center dot}{ital F}{sup {infinity}}{sub 0} ({ital E},Li{sup +}). Initial experiments were performed on the Texas Experimental Tokamak (TEXT) in which we compared pellet penetration with our impurity pellet ablation model (P. B. Parks {ital et} {ital al}., Nucl. Fusion {bold 28}, 477 (1988)), and measured the spatial distribution of various ionization states in carbon pellet clouds (R. K. Fisher {ital et} {ital al}., Rev. Sci. Instrum. {bold 61}, 3196 (1990)). Experiments have recently begun on the Tokamak Fusion Test Reactor (TFTR) with the goal of measuring the alpha particle energy distribution during D--T operation in 1993--94. A series of preliminary experiments are planned to test the diagnostic concept. The first experiments will observe neutrals from beam-injected deuterium ions and the high energy {sup 3}He tail produced during ion cyclotron (ICH) minority heating on TFTR interacting with the cloud. We will also monitor by line radiation the charge state distributions in lithium, boron, and carbon clouds.

Fisher, R.K.; McChesney, J.M.; Howald, A.W.; Parks, P.B. (General Atomics, P.O. Box 85608, San Diego, California 92186-9784 (United States)); Snipes, J.A.; Terry, J.L.; Marmar, E.S. (Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)); Zweben, S.J.; Medley, S.S. (Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States))

1992-10-01

80

Determination of alpha_s from the QCD static energy  

E-print Network

We compare lattice data for the short-distance part of the static energy in 2+1 flavor quantum chromodynamics (QCD) with perturbative calculations, up to next-to-next-to-next-to leading-logarithmic accuracy. We show that perturbation theory describes very well the lattice data at short distances, and exploit this fact to obtain a determination of the product of the lattice scale r_0 with the QCD scale Lambda_{MS}. With the input of the value of r_0, this provides a determination of the strong coupling alpha_s at the typical distance scale of the lattice data. We obtain alpha_s(1.5 GeV)=0.326\\pm0.019, which provides a novel determination of alpha_s at low energy and with three-loop accuracy (including resummation of the leading ultrasoft logarithms). When this value is evolved to the Z-mass scale M_Z, it corresponds to alpha_s(M_Z)=0.1156^{+0.0021}_{-0.0022}.

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

2012-12-18

81

Performance of CVD diamond alpha particle detectors  

NASA Astrophysics Data System (ADS)

The inherent properties of diamond can, in principle, make it an ideal material for radiation detectors with interesting capabilities. We have fabricated a particle detector using a free-standing CVD diamond film with a thickness of 300 ?m and area of 2 cm×2 cm and measured 5.5 MeV ? spectra from an 241Am source. The I-V characteristics indicate that a fine Ohmic contact is formed between the CVD diamond and electrode. At the external electric field 10 kV/cm, the collection efficiency reaches an average value of 41%, corresponding to a charge collection distance (CCD) of about 259 ?m and the energy resolution achieves 4.3%.

Minglong, Zhang; Yiben, Xia; Linjun, Wang; Hujiang, Shen; Beibei, Gu

2004-05-01

82

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

83

Shielding of manned space vehicles against protons and alpha particles  

NASA Technical Reports Server (NTRS)

The available information on the shielding of manned space vehicles against protons and alpha particles is summarized. The emphasis is placed on shielding against Van Allen belt protons and against solar-flare protons and alpha particles, but information on shielding against galactic cosmic rays is also presented. The approximation methods for use by nonexperts in the space shielding field are those that are standard in the space shielding literature.

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

1972-01-01

84

Alpha particle physics in a tokamak burning plasma experiment  

NASA Astrophysics Data System (ADS)

Much is known about the behavior of energetic ions in tokamak devices but much remains to be understood. Single-particle effects are well understood and provide a firm basis for extrapolation to a burning plasma. In contrast, collective effects involving fast ions are more poorly understood and extrapolations are unreliable. Collective modes of concern include toroidicity-induced and ellipticity-induced Alfvén eigenmodes, kinetic ballooning modes, and internal kink modes. In addition to these magnetohydrodynamic normal modes, there are also energetic particle modes characterized by strong dependence on the fast-ion distribution function. Although many issues are important areas of study in current experiments, five issues distinguish burning plasma experiments. First, the energetic alphas are not the dominant source of free energy for the instabilities unless the fusion power exceeds the heating power by a factor of 10. Second, the damping of the instabilities depends sensitively on mode coupling to other heavily-damped waves. The magnitude of this coupling is expected to depend on the normalized thermal gyroradius, which is much smaller in a reactor. Third, in a reactor, both the radial extent of the instabilities and the fast-ion orbit contract relative to current experiments, so the fast-ion transport will change. Fourth, when instability occurs, a larger number of modes are unstable, so the mechanism of nonlinear saturation could shift from fast-ion transport to mode coupling. Fifth, because of the extreme sensitivity of energetic particle modes to the distribution function, an isotropic alpha particle distribution function differs from anisotropic fast-ion populations.

Heidbrink, W. W.

2002-05-01

85

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

86

Age response for line CHO Chinese hamster cells exposed to x irradiation and alpha particles from plutonium  

Microsoft Academic Search

The age response of Chinese hamster cells (line CHO) synchronized by ; mitotic selection and by mitotic selection with hydroxyurea resynchronization was ; studied for x rays and alpha particles from plutonium of 4.4-MeV residual energy. ; The age response for alpha particles when mitotically synchronized cells are used ; indicated that cells in S are slightly more sensitive but

M. R. Raju; R. A. Tobey; J. H. Jett; R. A. Walters

1975-01-01

87

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

DOEpatents

Neutron activation due to high levels of neutron production in a first heated deuterium-tritium plasma is substantially reduced by using Ion Cyclotron Resonance Frequency (ICRF) heating of energetic .sup.3 He.sup.++ ions in a second deuterium-.sup.3 He.sup.++ plasma which exhibit an energy distribution and density similar to that of alpha particles in fusion reactor experiments to simulate fusion alpha particle heating in the first plasma. The majority of the fast .sup.3 He.sup.++ ions and their slowing down spectrum can be studied using either a modulated hydrogen beam source for producing excited states of He.sup.+ in combination with spectrometers or double charge exchange with a high energy neutral lithium beam and charged particle detectors at the plasma edge. The maintenance problems thus associated with neutron activation are substantially reduced permitting energetic alpha particle behavior to be studied in near term large fusion experiments.

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

1986-04-22

88

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

SciTech Connect

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

Avancini, S. S.; Barros, C. C. Jr.; Menezes, D. P. [Departamento de Fisica, CFM, Universidade Federal de Santa Catarina Florianopolis SC, CP 476, CEP 88.040 900 (Brazil); Providencia, C. [Centro de Fisica Computacional, Department of Physics, University of Coimbra, P 3004 516, Coimbra (Portugal)

2010-08-15

89

High energy particle astronomy.  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

90

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

91

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

92

Radon monitor and control system based upon alpha particle detection  

SciTech Connect

A system is designed for monitoring or controlling the level of radon in indoor air, based upon measuring alpha particles due to the decay of radon or its daughter atoms. In one embodiment, the alpha particle decay of radon itself is detected and analyzed to control a vent in the heating and air conditioning system to automatically keep the radon level below a preselected level. In another embodiment, the daughter atoms {sub 218}Po and {sub 214}Po are collected from the indoor air and their alpha particle decays are analyzed to provide a sensitive monitor of radon levels or to control vents in the HVAC system to reduce radon concentrations to permissible levels. In addition, the system provides information on the quality of the air filter and indicates when it needs servicing.

Hurst, G.S.

1992-01-01

93

Alpha-particle radiobiological experiments using thin CR-39 detectors.  

PubMed

The present paper studied the feasibility of applying comet assay to evaluate the DNA damage in individual HeLa cervix cancer cells after alpha-particle irradiation. We prepared thin CR-39 detectors (<20 microm) as cell-culture substrates, with UV irradiation to shorten the track formation time. After irradiation of the HeLa cells by alpha particles, the tracks on the underside of the CR-39 detector were developed by chemical etching in (while floating on) a 14 N KOH solution at 37 degrees C. Comet assay was then applied. Diffusion of DNA out of the cells could be generally observed from the images of stained DNA. The alpha-particle tracks corresponding to the comets developed on the underside of the CR-39 detectors could also be observed by just changing the focal plane of the confocal microscope. PMID:17132662

Chan, K F; Siu, S Y M; McClella, K E; Tse, A K W; Lau, B M F; Nikezic, D; Richardson, B J; Lam, P K S; Fong, W F; Yu, K N

2006-01-01

94

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

NASA Astrophysics Data System (ADS)

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

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

1994-01-01

95

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

SciTech Connect

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

Ryutov, D.D. [Lawrence Livermore National Laboratory (United States)

2002-03-15

96

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

97

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

98

MHD-Induced Alpha Particle Loss in TFTR  

SciTech Connect

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

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

1999-03-01

99

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

100

Fast detection of alpha particles in DAM-ADC nuclear track detectors  

NASA Astrophysics Data System (ADS)

Fast detection of alpha particles in DAM-ADC nuclear track detectors using a new chemical etchant was investigated. 252Cf and 241Am sources were used for irradiating samples of DAM-ADC SSNTDs with fission fragments and alpha particles in air at normal temperature and pressure. A series of experimental chemical etching are carried out using new etching solution (8 ml of 10 N NaOH+ 1 ml CH3OH) at 60 °C to detect alpha particle in short time in DAM-ADC detectors. Suitable analyzing software has been used to analyze experimental data. From fission and alpha track diameters, the value of bulk etching rate is equal to 8.52 ?m/h. Both of the sensitivity and etching efficiency were found to vary with the amount of methanol in the etching solution and etching time. The DAM-ADC detectors represent the best efficiency applicable in detectors in the entire range of alpha energies (from 1 to 5 MeV). The activation energies of this etchant have been calculated; track activation energy, ET, has been found to be lower than the bulk activation energy, EB, for the DAM-ADC nuclear track detectors. These results are in more agreement with the previous work.

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

2015-02-01

101

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.

102

226Ra determination in phosphogypsum by alpha-particle spectrometry  

NASA Astrophysics Data System (ADS)

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

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

1999-01-01

103

Alpha-Particle Decay Branching Ratio Measurements for Excited States of NITROGEN-15  

NASA Astrophysics Data System (ADS)

The reactions, ^{12 }C(^7Li,alpha)^{15}N and ^7Li(^{12 }C,^{15}Ntoalpha + ^{11}B)alpha at E_{rm cm} = 33.2 MeV, are used to measure the alpha-particle decay branching ratio, Gamma_alpha/Gamma, of states in ^{15}N produced at several excitation energies, rm E_{x}(^{15}N). Resonant Particle Decay Spectroscopy is applied to the sequential reaction to identify ^{15 }N states and construct their alpha-particle angular correlations from the kinematic reconstruction of the relative kinetic energy of the ^ {15}N break-up products (alpha and ^{11}B) detected in coincidence by use of two position sensitive detectors. It is shown that the symmetry observed in these correlations implies azimuthal isotropy, so that integration can be accomplished to yield Gamma_alpha/ Gamma in conjunction with the measured ^{15}N production cross sections. For excited states at rm E_{x}( ^{15}N) = 11.44, 12.56, 13.01, 13.18, 13.83 and 14.11 MeV, the measured values of Gamma_alpha/Gamma are 0.07 +/- 0.01, 0.60 +/- 0.04, 0.84 +/- 0.09, 0.34 +/- 0.04, 0.37 +/- 0.09 and 0.31 +/- 0.06 respectively (absolute uncertainty is ~15%). Reduced widths of some of these states are calculated under limiting approximations. Spectral analysis also yields: (a) New excited states at rm E_{x}(^ {15}N) = 12.67, 12.83, 15.15 and 22.58 MeV, (b) confirmation of previously questioned states at rm E_{x}(^{15 }N) = 15.87 and 21.37 MeV, (c) previously unknown alpha-particle decays for 17 excited states and (d) correction of previously reported energy widths for states at rm E_{x}(^{15}N) = 16.20, 16.46, 17.12, and 20.95 MeV. Probable spin-parity values are proposed for several ^ {15}N states based on a DWBA analysis carried out for the angular distributions of the ^{12}C(^7Li,alpha) ^{15}N reaction and the best theoretical descriptions of the alpha-particle angular correlations of the sequential reaction.

Liendo, Jacinto Alberto

104

New concept for a wall detector for alpha particles  

SciTech Connect

A new concept for a wall-mounted detector is described here that would measure D-T alpha flux and corresponding pitch angle distribution in tokamaks (or related toroidal devices). The sensing element is a conical Micro Channel Ring (MCR) coated with 1 to 2..mu.. of ZnS scintillator (or possibly ZnO). The collimation of the ..cap alpha.. particles is provided by two circumferential slots at the wall surface. The alpha scintillation events on the MCR are transferred through the ring channels and coupled fiber optics bundle to an external processor. From the magnetic field vector at a given point on the device wall, a certain relation can be set up between the ..cap alpha..-induced scintillation position on the MCR and its original pitch angle (i.e., the angle between the ..cap alpha.. emission from the fusion reaction and the magnetic field vector) which is equal to the local pitch angle since the wall ..cap alpha.. flux is dominated by prompt losses.

Miley, G.H.; Kislev, H.; Micklich, B.J.

1985-01-01

105

Evidence for alpha-particle chain configurations in sup 24 Mg  

SciTech Connect

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

Wuosmaa, A.H.; Back, B.B.; Betts, R.R.; Ferre, M.; Gehring, J.; Glagola, P.G.; Happ, Th.; Henderson, D.J.; Wilt, P. (Argonne National Lab., IL (United States)); Bearden, I.G. (Purdue Univ., Lafayette, IN (United States). Dept. of Physics)

1992-01-01

106

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

SciTech Connect

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

Wuosmaa, A.H.; Back, B.B.; Betts, R.R.; Ferre, M.; Gehring, J.; Glagola, P.G.; Happ, Th.; Henderson, D.J.; Wilt, P. [Argonne National Lab., IL (United States); Bearden, I.G. [Purdue Univ., Lafayette, IN (United States). Dept. of Physics

1992-09-01

107

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

108

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

109

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

SciTech Connect

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

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

1998-11-01

110

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

NASA Astrophysics Data System (ADS)

The formation of etched tracks in solid-state nuclear track detectors is usually described by assuming an unequivocal correlation of the etch-rate ratio with the energy loss of charged particles. For alpha particles, this assumption could be verified within the scatter of the experimental data. In this article, the dependence of the depth (x) on the track etch rate (V-T) was determined experimentally by track length measurement. It is found that the track etch rate as a function of the depth within the detector follows the Bragg curve. The track etch rate has been found to be described by a generalization of the restricted energy loss, in good approximation along the trajectories of alpha particles.

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

2005-01-01

111

The (?,n) production rate of plutonium alpha particles on vermiculite  

Microsoft Academic Search

The (?,n) production rate for plutonium alpha particles on vermiculite relative to that on PuO2 is estimated within the framework of a homogeneous medium model using thick target elemental values evaluated at 5.5 MeV. The composition of the vermiculite is highly variable and the predicted relative (?,n) rate varies over a range of approximately 7–25, but this is in broad

S. Croft; A. R. Yates

1997-01-01

112

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

113

Further measurement of the {beta}-delayed {alpha}-particle emission of {sup 16}N  

SciTech Connect

We measured the {beta}-delayed {alpha}-particle emission spectrum of {sup 16}N with a sensitivity for {beta}-decay branching ratios of the order of 10{sup -10}. The {sup 16}N nuclei were produced using the d({sup 15}N,{sup 16}N)p reaction with 70 MeV {sup 15}N beams and a deuterium gas target 7.5 cm long at a pressure of 1250 torr. The {sup 16}N nuclei were collected (over 10 s) using a thin aluminum foil with an areal density of 180 {mu}g/cm{sup 2} tilted at 7 deg. with respect to the beam. The activity was transferred to the counting area by means of a stepping motor in less than 3 s with the counting carried out over 8 s. The {beta}-delayed {alpha}-particles were measured using a time-of-flight method to achieve a sufficiently low background. Standard calibration sources ({sup 148}Gd, {sup 241}Am, {sup 208,209}Po, and {sup 227}Ac) as well as {alpha} particles and {sup 7}Li from the {sup 10}B(n,{alpha}){sup 7}Li reaction were used for an accurate energy calibration. The energy resolution of the catcher foil (180-220 keV) was calculated and the time-of-flight resolution (3-10 nsec) was measured using the {beta}-delayed {alpha}-particle emission from {sup 8}Li that was produced using the d({sup 7}Li,{sup 8}Li)p reaction with the same setup. The line shape was corrected to account for the variation in the energy and time resolution and a high statistics spectrum of the {beta}-delayed {alpha}-particle emission of {sup 16}N is reported. However, our data (as well as earlier Mainz data and unpublished Seattle data) do not agree with an earlier measurement of the {beta}-delayed {alpha}-particle emission of {sup 16}N taken at TRIUMF after averaging over the energy resolution of our collection system. This disagreement, among other issues, prohibits accurate inclusion of the f-wave component in the R-matrix analysis.

France III, R. H.; Wilds, E. L.; McDonald, J. E.; Gai, M. [Department of Chemistry and Physics, Campus Box 82, Georgia College and State University, Milledgeville, Georgia 31061 (United States); Division of Radiation Safety, Connecticut-DEP, 79 Elm Street, Hartford, Connecticut 06106 (United States); Department of Physics, University of Hartford, West Hartford, Connecticut 06117-1599 (United States); Laboratory for Nuclear Sciences at Avery Point, University of Connecticut, Groton, Connecticut 06340-6097 (United States) and Department of Physics, WNSL-102, P.O. Box 208124, Yale University, 272 Whitney Avenue, New Haven, Connecticut 06520-8124 (United States)

2007-06-15

114

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

PubMed

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

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

2010-08-01

115

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

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

117

Alpha-particle Measurements Needed for Burning Plasma Experiments  

SciTech Connect

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

Kenneth M. Young

2001-09-26

118

Cryogenic microcalorimeter system for ultra-high resolution alpha-particle spectrometry  

SciTech Connect

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

Rabin, Michael W [Los Alamos National Laboratory; Hoover, Andrew S [Los Alamos National Laboratory; Bacrania, Mnesh K [Los Alamos National Laboratory; Croce, Mark P [Los Alamos National Laboratory; Hoteling, N J [Los Alamos National Laboratory; Lamont, S P [Los Alamos National Laboratory; Plionis, A A [Los Alamos National Laboratory; Dry, D E [Los Alamos National Laboratory; Ullom, J N [NIST; Bennett, D A [NIST; Horansky, R [NIST; Kotsubo, V [NIST; Cantor, R [STAR CRYOELECTRONICS

2009-01-01

119

Comparison between different models for alpha-particle range determination and a new approach to CR-39 detector  

NASA Astrophysics Data System (ADS)

An extensive study was carried out to compare different models and a new approach for measuring the alpha-particle range in the CR-39 detector. The CR-39 samples were exposed perpendicularly to alpha particles with energies ranging from 2.5 MeV to 5.5 MeV emitted from 241Am. The CR-39 samples were etched in 7.25 N NaOH at (70 ± 0.5) °C for different durations. Both the track diameters and the track cone lengths were measured under an optical microscope. The new approach is based on measurement of the track etch rate along the particle's trajectory as a function of the removal thickness (h). A correlation was found to exist between the removal thickness at the maximum track etch rate ( V Tmax ) and the range of alpha particles in the CR-39 detector. The track etch rate data were fitted using the function V T ( h) = a 1 + [ a 2 - a 3 h]exp[ a 4 h]. The ranges of alpha particles were determined by setting the first order derivative of the fitting function equal to zero, where h is equal to the range of the alpha particles (R) in the CR-39 detector. Furthermore, the range of the alpha particle in the CR-39 detector was measured using the over-etched track diameter and the track cone length. The theoretical predictions of the alpha-particle ranges were calculated using the SRIM software. A well-known function, R( E) = b 1 E b2, was used to fit the experimental results and the theoretical predictions. Experiments showed that the determination of the alpha-particle range based on the cone length model was in a good agreement with the theoretical calculations, where the discrepancy was less than that for the over-etched track diameter and the maximum track etch rate models.

El Ghazaly, M.; Salama, T. T.; Khalil, E. I.; Abd El Raouf, Kh. M.

2012-08-01

120

Protons and alpha particles in the solar wind  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

121

Thick Source Alpha Particle Spectroscopy: Possibilities And Prospects  

NASA Astrophysics Data System (ADS)

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

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

122

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

Microsoft Academic Search

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

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

1983-01-01

123

Fission studies with 140 MeV $\\bm{\\alpha}$-Particles  

E-print Network

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

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

2009-01-01

124

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

125

The Astrophysical S-Factor of CARBON-12(ALPHA Particle, Photon) OXYGEN-16 from the Beta-Delayed Alpha - Emission of NITROGEN-16 (helium Burning)  

NASA Astrophysics Data System (ADS)

Helium burning plays a key role in both the formation of heavy elements and the collapse of massive stars. The result of the helium burning--the ^{12 }C/16O ratio, determines the abundance of heavy elements and the dynamics of a massive star at its final stages before a supernova explosion. One of the two reactions in the helium burning process, the 12C( alpha,gamma)16O capture reaction, is poorly understood despite intense theoretical and experimental work during the last two decades. The previously extracted p-wave 'S-factor' for the 12C(alpha,gamma) 16O capture reaction at 300 keV (SE1(300)) ranges in value from 0 to 500 keV-barn. On the other hand, the beta-delayed alpha-particle emission spectrum at low energy provides a very sensitive means to determine the reduced alpha-particle width of the bound 1^- state, hence the 'S-factor'. The spectrum of low energy beta-delayed alpha -particle emission 16N, was measured with high sensitivity; e.g., at E _sp?{L} ~ 1 MeV a sensitivity for a beta-decay branching ratio in the range of 10^{-9} (to 10^{-10}) was achieved. The branching ratio and spectrum of beta -decay of 16N to the relevant broad 1^- resonance were remeasured. The alpha-particle spectra were unfolded to remove effects of finite energy resolution (foil thickness). We used previous theoretical work of Ji, Filippone, Humblet and Koonin to extract from these data the astrophysical E1 S-factor for the 12C( alpha,gamma)16O capture reaction and find SE1(300) = 95 +/- 6 (stat) +/- 28 (syst) keV-barn.

Zhao, Zhiping

1993-01-01

126

Free Particle Energy Eigenstates Model  

NSDL National Science Digital Library

The Free Particle Energy Eigenstates model shows the time evolution of a superpostion of free particle energy eigenstates. A table shows the energy, momentum, and amplitude of each eigenstate. The Free Particle Energy Eigenstates model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Download and then double the ejs_qm_FreeParticleEigenstates.jar file to run this program if Java is installed.

Christian, Wolfgang

2008-09-26

127

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

128

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

SciTech Connect

We investigate the conditions under which parallel-propagating Alfven/ion-cyclotron (A/IC) waves and fast-magnetosonic/whistler (FM/W) waves are driven unstable by the differential flow and temperature anisotropy of alpha particles in the solar wind. We focus on the limit in which w{sub Parallel-To {alpha}} {approx}> 0.25v{sub A}, where w{sub Parallel-To {alpha}} is the parallel alpha-particle thermal speed and v{sub A} is the Alfven speed. We derive analytic expressions for the instability thresholds of these waves, which show, e.g., how the minimum unstable alpha-particle beam speed depends upon w{sub Parallel-To {alpha}}/v{sub A}, the degree of alpha-particle temperature anisotropy, and the alpha-to-proton temperature ratio. We validate our analytical results using numerical solutions to the full hot-plasma dispersion relation. Consistent with previous work, we find that temperature anisotropy allows A/IC waves and FM/W waves to become unstable at significantly lower values of the alpha-particle beam speed U{sub {alpha}} than in the isotropic-temperature case. Likewise, differential flow lowers the minimum temperature anisotropy needed to excite A/IC or FM/W waves relative to the case in which U{sub {alpha}} = 0. We discuss the relevance of our results to alpha particles in the solar wind near 1 AU.

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

2013-08-20

129

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

PubMed

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

Giesen, U; Beck, J

2014-10-01

130

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

NASA Technical Reports Server (NTRS)

One of the main uncertainties in risk estimation for environmental radon exposure using lung cancer data from underground miners is the extrapolation from high- to low-dose exposure where multiple traversal is extremely rare. The biological effects of a single alpha particle are currently unknown. Using the recently available microbeam source at the Radiological Research Accelerator Facility at Columbia University, we examined the frequencies and molecular spectrum of S1- mutants induced in human-hamster hybrid (A(L)) cells by either a single or an exact number of alpha particles. Exponentially growing cells were stained briefly with a nontoxic concentration of Hoechst dye for image analysis, and the location of individual cells was computer-monitored. The nucleus of each cell was irradiated with either 1,2,4, or 8 alpha particles at a linear energy transfer of 90 keV/microm consistent with the energy spectrum of domestic radon exposure. Although single-particle traversal was only slightly cytotoxic to A(L) cells (survival fraction approximately 0.82), it was highly mutagenic, and the induced mutant fraction averaged 110 mutants per 10(5) survivors. In addition, both toxicity and mutant induction were dose-dependent. Multiplex PCR analysis of mutant DNA showed that the proportion of mutants with multilocus deletions increased with the number of particle traversals. These data provide direct evidence that a single a particle traversing a nucleus will have a high probability of resulting in a mutation and highlight the need for radiation protection at low doses.

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

1997-01-01

131

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

Microsoft Academic Search

The measurement of the alpha-activity ratio of 238Pu\\/(239Pu + 240Pu) is a routine practice in the determination of the isotopic composition of plutonium. However, measurement of the atomic ratio of 240Pu\\/239Pu by alpha-particle spectrometry is hampered due to insufficient energy resolution for the set of closely spaced peaks of these two isotopes. Passivated and implanted, planar silicon (PIPS) detectors have

W. Raab; J. L. Parus

1994-01-01

132

Energetic/alpha particle effects on MHD modes and transport  

SciTech Connect

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

Cheng, C.Z.; Budny, R. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Chen, L. [Univ. of California, Irvine, CA (United States). Dept. of Physics

1995-01-01

133

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

134

Alpha particles induce apoptosis through the sphingomyelin pathway.  

PubMed

The sphingomyelin pathway involves the enzymatic cleavage of sphingomyelin to produce ceramide, a second messenger that serves as a key mediator in the rapid apoptotic response to various cell stressors. Low-linear energy transfer (LET) ? radiation can initiate this pathway, independent of DNA damage, via the cell membrane. Whether short-ranged, high-LET ? particles, which are of interest as potent environmental carcinogens, radiotherapies and potential components of dirty bombs, can act through this mechanism to signal apoptosis is unknown. Here we show that irradiation of Jurkat cells with ? particles emitted by the ²²?Ac-DOTA-anti-CD3 IgG antibody construct results in dose-dependent apoptosis. This apoptosis was significantly reduced by pretreating cells with cholesterol-depleting nystatin, a reagent known to inhibit ceramide signaling by interfering with membrane raft coalescence and ceramide-rich platform generation. The effects of nystatin on ?-particle-induced apoptosis were related to disruption of the ceramide pathway and not to microdosimetry alterations, because similar results were obtained after external irradiation of the cells with a broad beam of collimated ? particles using a planar ²?¹Am source. External irradiation allowed for more precise control of the dosimetry and geometry of the irradiation, independent of antibody binding or cell internalization kinetics. Mechanistically consistent with these findings, Jurkat cells rapidly increased membrane concentrations of ceramide after external irradiation with an average of five ?-particle traversals per cell. These data indicate that ? particles can activate the sphingomyelin pathway to induce apoptosis. PMID:21631289

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

2011-10-01

135

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

E-print Network

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

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

2014-01-01

136

Alpha-particle-driven instability of alfven waves in a tandem mirror. Final summary report, 21 February-20 May 1985  

SciTech Connect

Alpha particles born at D-T fusion are mirror confined in the tandem mirror due to their relatively high energy. Therefore, they have a loss-cone type distribution in the velocity space. This anisotropy is susceptible to microinstability. The objective of this work is to study the possible instability that can be driven by the alpha loss-cone. The low frequency (at the order of the ion cyclotron frequency) wave spectrum is studied to seek the waves that can be destabilized by the alphas. The radial mode structure is found for the growth rate calculation. The alpha particle distribution with a loss-cone is obtained from a Legendre function expansion and a diffusion front method. The growth rate of the instability is formulated from linear stability theory and computed numerically. A marginal stability boundary in the ion density and temperature parameters is calculated.

Ho, S.K.

1985-08-20

137

Study of excitation functions of alpha-particle induced nuclear reactions on holmium for 167Tm production.  

PubMed

(167)Tm is a candidate radioisotope for both nuclear medicine diagnostics and therapy due to its emitted Auger-electrons, low energy X- and gamma-rays. In the frame of a systematic study of excitation functions for production of medically relevant radioisotopes by charged particle induced reactions on rare earths, the (165)Ho(alpha,2n)(167)Tm reaction and the (165)Ho(alpha,n)(168)Tm, (165)Ho(alpha,3n)(166)Tm, (165)Ho(alpha,4n)(165)Tm side reactions were measured up to 40 MeV by the stacked foil irradiation technique and gamma-ray spectroscopy. The measured results were compared to the ALICE-IPPE and EMPIRE-II theoretical curves. Thick target yields, impurity levels and specific activities were deduced and compared with the same parameters for other charged particle production routes of (167)Tm. PMID:20022515

Tárkányi, F; Hermanne, A; Király, B; Takács, S; Ignatyuk, A V

2010-03-01

138

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

139

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

140

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

PubMed

The energy and specific energy absorbed in the main cell compartments (nucleus and cytoplasm) in typical radiobiology experiments are usually estimated by calculations as they are not accessible for a direct measurement. In most of the work, the cell geometry is modelled using the combination of simple mathematical volumes. We propose a method based on high resolution confocal imaging and ion beam analysis (IBA) in order to import realistic cell nuclei geometries in Monte-Carlo simulations and thus take into account the variety of different geometries encountered in a typical cell population. Seventy-six cell nuclei have been imaged using confocal microscopy and their chemical composition has been measured using IBA. A cellular phantom was created from these data using the ImageJ image analysis software and imported in the Geant4 Monte-Carlo simulation toolkit. Total energy and specific energy distributions in the 76 cell nuclei have been calculated for two types of irradiation protocols: a 3 MeV alpha particle microbeam used for targeted irradiation and a ²³?Pu alpha source used for large angle random irradiation. Qualitative images of the energy deposited along the particle tracks have been produced and show good agreement with images of DNA double strand break signalling proteins obtained experimentally. The methodology presented in this paper provides microdosimetric quantities calculated from realistic cellular volumes. It is based on open-source oriented software that is publicly available. PMID:22456322

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

2012-04-21

141

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

2014-11-04

142

Experimental Study of the Cross Sections of {alpha}-Particle Induced Reactions on 209Bi  

SciTech Connect

Alpha particle induced reactions for generation of 211At used in therapeutic nuclear medicine and possible contaminants were investigated with the stacked foil activation technique on natural bismuth targets up to E{alpha}=39 MeV. Excitation functions for the reactions 209Bi({alpha},2n)211At, 209Bi({alpha},3n)210At, 209Bi({alpha},x) 210Po obtained from direct alpha emission measurements and gamma spectra from decay products are compared with earlier literature values. Thick target yields have been deduced from the experimental cross sections.

Hermanne, A. [Cyclotron Department, Vrije Universiteit Brussel, Laarbeeklaan 103, B1090 Brussels (Belgium); Tarkanyi, F.; Takacs, S.; Szucs, Z. [Atomki, Hungarian Academy of Sciences, Bem Ter, H4001 Debrecen (Hungary)

2005-05-24

143

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

144

Enhanced homologous recombination is induced by alpha-particle radiation in somatic cells of Arabidopsis thaliana  

NASA Astrophysics Data System (ADS)

Almost 9 percent of cosmic rays which strike the earth's atmosphere are alpha particles. As one of the ionizing radiations (IR), its biological effects have been widely studied. However, the plant genomic instability induced by alpha-particle radiation was not largely known. In this research, the Arabidopsis thaliana transgenic for GUS recombination substrate was used to evaluate the genomic instability induced by alpha-particle radiation (3.3MeV). The pronounced effects of systemic exposure to alpha-particle radiation on the somatic homologous recombination frequency (HRF) were found at different doses. The 10Gy dose of radiation induced the maximal HRF which was 1.9-fold higher than the control. The local radiation of alpha-particle (10Gy) on root also resulted in a 2.5-fold increase of somatic HRF in non-radiated aerial plant, indicating that the signal(s) of genomic instability was transferred to non-radiated parts and initiated their genomic instability. Concurrent treatment of seedlings of Arabidopsis thaliana with alpha-particle and DMSO(ROS scavenger) both in systemic and local radiation signifi- cantly suppressed the somatic HR, indicating that the free radicals produced by alpha-particle radiation took part in the production of signal of genomic instability rather than the signal transfer. Key words: alpha-particle radiation, somatic homologous recombination, genomic instability

Bian, Po; Liu, Ping; Wu, Yuejin

145

On interstitial dislocation loops in aluminium bombarded with alpha-particles  

Microsoft Academic Search

Electron transmission microscopy and selected area diffraction have shown that the dislocation loops in aluminium bombarded with 38 Mev alpha-particles lie generally upon the {110} planes with a [110] Burgers vector normal to the loop. These loops are only seen where the alpha-particles come to rest. The theory of diffraction contrast at dislocations (Hirsch et al. 1960) has been used

D. J. Mazey; R. S. Barnes; A. Howie

1962-01-01

146

Fission of THORIUM-232 and URANIUM-238 Induced by Inelastic Scattering of 120 Mev Alpha Particles.  

NASA Astrophysics Data System (ADS)

This thesis describes the inelastic scattering of 120 MeV alpha-particles from ('232)Th and ('238)U in coincidence with fission of the target nuclei. The fission probability and angular distribution of the fission fragments have been measured. The alpha-particles are detected with the Q3D magnetic spectrograph, for which instrument position sensitive focal plane detectors are built. For the fission fragments, position sensitive parallel plate avalanche detectors are developed. No evidence for the fission decay of the giant quadrupole resonance has been found. For ('238)U, however, a weakly excited structure with unknown multipolarity is seen at about 9.5 MeV excitation energy, similar to that which has been reported in inelastic scattering of lithium ions in coincidence with fission. The overall feature of the fission probability for excitation energies above the fission barrier is well reproduced by statistical calculations. At the barrier region, evidence for positive and negative subbarrier resonances has been found, the negative parity ones occurring at the same excitation energy where photofission resonances are located. The data are analyzed with the two-humped barrier model. For ('238)U the data are reasonably well fitted with the barriers known from literature. For ('232)Th, however, the outer barrier is found to be higher. Also, for ('232)Th, introducing an additional mass symmetric and axially asymmetric outer barrier, as was previously found necessary for ('238)U, does not result in a good fit to the data at higher excitation energies.

van der Plicht, Johannes

1980-12-01

147

Evidence for strong refraction of $^3$He in an alpha-particle condensate  

E-print Network

We have analyzed $^{3}$He scattering from $^{12}$C at 34.7 and 72 MeV in a coupled channel method with a double folding potential derived from the precise wave functions for the ground 0$^+$ state and $0_2^+$ (7.65 MeV) Hoyle state, which has been suggested to be an $\\alpha$ particle condensate. It is found that strong refraction of $^3$He in the Hoyle state can be clearly seen in the experimental angular distribution at {\\it low} incident energy region as an Airy minimum of the {\\it pre-rainbow oscillations}.

S. Ohkubo; Y. Hirabayashi

2011-02-09

148

Alpha Particles Induce Apoptosis through the Sphingomyelin Pathway  

PubMed Central

The sphingomyelin pathway involves the enzymatic cleavage of sphingomyelin to produce ceramide, a second messenger that serves as a key mediator in the rapid apoptotic response to various cell stressors. Low-linear energy transfer (LET) ? radiation can initiate this pathway, independent of DNA damage, via the cell membrane. Whether short-ranged, high-LET a particles, which are of interest as potent environmental carcinogens, radiotherapies and potential components of dirty bombs, can act through this mechanism to signal apoptosis is unknown. Here we show that irradiation of Jurkat cells with a particles emitted by the 225Ac-DOTA-anti-CD3 IgG antibody construct results in dose-dependent apoptosis. This apoptosis was significantly reduced by pretreating cells with cholesterol-depleting nystatin, a reagent known to inhibit ceramide signaling by interfering with membrane raft coalescence and ceramide-rich platform generation. The effects of nystatin on ?-particle-induced apoptosis were related to disruption of the ceramide pathway and not to microdosimetry alterations, because similar results were obtained after external irradiation of the cells with a broad beam of collimated a particles using a planar 241Am source. External irradiation allowed for more precise control of the dosimetry and geometry of the irradiation, independent of antibody binding or cell internalization kinetics. Mechanistically consistent with these findings, Jurkat cells rapidly increased membrane concentrations of ceramide after external irradiation with an average of five ?-particle traversals per cell. These data indicate that a particles can activate the sphingomyelin pathway to induce apoptosis. PMID:21631289

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

2011-01-01

149

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

150

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

Microsoft Academic Search

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

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

1999-01-01

151

Cancer Stem Cell Targeting Using the Alpha-Particle Emitter, 213Bi: Mathematical Modeling and Feasibility Analysis  

PubMed Central

There is increasing recognition that treatment failure in cancer may be associated with the failure to sterilize a small subpopulation of tumor cells that have been characterized as tumor stem cells. Defined as cells that are able to self-renew and also to replenish a phenotypically diverse tumor-cell population, such cells are also considered resistant to chemotherapy. These characteristics are optimal for targeting by using alpha-particle-emitting radionuclides. Because of their high-energy deposition density per track, alpha-particles are capable of targeting single cells or small clusters of cells with minimal normal organ toxicity. The DNA damage induced by alpha-particles is largely irreparable and, therefore, alpha-particle-induced damage is minimally susceptible to resistance mechanisms. In this work, theoretical modeling was performed to examine the potential of alpha-emitter targeting of such small clusters of cancer stem cells. Critical parameters influencing efficacy and toxicity were identified and their relationship elucidated. The results identify specific activity, antigen site density, and number of target cells as critical parameters for effective cell killing and demonstrate substantial efficacy gains by targeting a smaller number of stem cells, as opposed to the entire tumor-cell population. PMID:18298331

Sgouros, George; Song, Hong

2010-01-01

152

Stopping power and ranges of electrons, protons and alpha particles in liquid water using the Geant4-DNA package  

NASA Astrophysics Data System (ADS)

This paper presents stopping power and ranges of electrons, protons, and alpha particles in liquid water, calculated using the latest Geant4-DNA processes implemented in the Geant4 Monte Carlo simulation toolkit. Inelastic cross sections are obtained using the first Born approximation and semi-empirical formulas like Rudd's model for ionisation and the Miller and Green formula for excitation. Elastic collisions and vibrational excitations are considered for tracking electrons until complete thermalisation (0.025 eV). A speed scaling procedure with an effective charge screening term was used to compute alpha particle and heavy ion cross sections. Geant4-DNA simulations were carried out using thin liquid water volumes to determine the linear energy loss (dE/dX), while larger volumes were used to obtain the particle range. While results converge for highly energetic particles, differences are observed for low energies when the applied theoretical models begin to diverge from each other. Results show a good agreement between the analytical calculations obtained from the models, the Geant4-DNA Monte Carlo simulation predictions and the data published in the ICRU reports. Geant4-DNA processes apply to the following energy ranges: 0.025 eV-1 MeV for electrons, 100 eV-100 MeV for protons and 1 keV-400 MeV for alpha particles in liquid water, however since experimental data for very low energies is scarce and very difficult to obtain these processes could not be thoroughly validated so they are recommended for energies above 1 eV for electrons, 1 keV for protons and 10 keV for alpha particles. Relativistic, highly charged ions were implemented in our own “house” version of the code and will be available in future releases of Geant4.

Francis, Z.; Incerti, S.; Karamitros, M.; Tran, H. N.; Villagrasa, C.

2011-10-01

153

Comparison of high-n instabilities including alpha-particle effects in BPX and TFTR  

SciTech Connect

Three distinct types of high toroidal mode number instabilities are obtained from a comprehensive kinetic calculation, using as input transport code results from the analysis of a recent design for the Burning Plasma Experiment (BPX). These instabilities are: the collisionless trapped-electron ion-temperature-gradient mode, the magnetohydrodynamic ballooning mode, and a high toroidal mode number version of the toroidicity-induced Alfven eigenmode or gap'' mode. The dependence of the instability linear eigenfrequencies on minor radius, beta, and toroidal mode number are investigated, along with the effects of hot alpha particles. Relative quasilinear fluxes of particles and energy for each species are also obtained. In addition, the beta dependence of the magnetohydrodynamic ballooning mode is investigated for a case using as input the results of a transport code calculation for the Tokamak Fusion Test Reactor (TFTR) in an extrapolation to a deuterium-tritium mixture. The effects of alpha particles and the relative quasilinear fluxes are also investigated for this case. 13 refs., 13 figs., 4 tabs.

Rewoldt, G.

1991-07-01

154

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

155

On the approximations of the distribution function of fusion alpha particles  

SciTech Connect

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

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

2014-10-15

156

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

157

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

158

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

159

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

160

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

161

GR Schwarzschild Particle Energy Program  

NSDL National Science Digital Library

The GR Schwarzschild Particle Energy program simulates orbits of objects around a black hole using the Schwarzschild metric. It also displays a plot of the effective potential well in which the orbiting particle resides. The user can change the orbiterâs state by entering new energy and angular momentum values and dragging the marker to different positions. The default configuration is a circular orbit. GR Schwarzschild Particle Energy is part of a suite of Open Source Physics programs that model aspects of General Relativity. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the gr_schwarzschild_particle_energy.jar file will run the program if Java is installed. Other programs provide additional visualizations. They can be found by searching ComPADRE for Open Source Physics, OSP, or General Relativity.

Christian, Wolfgang; Belloni, Mario; Cox, Anne

2008-05-27

162

Some alpha-particle heating and acceleration mechanisms in the solar wind - Prognoz 7 measurements  

Microsoft Academic Search

The solar wind alpha-particle and proton measurements made by the mass spectrometer on Prognoz 7 are discussed. Bulk velocity difference V(alpha) - Vp is a sign of relative helium abundance differential with increasing solar wind velocity. It may be the result of mixing of solar wind streams with different velocities and different relative abundances. The correlation T(alpha)\\/Tp and absolute value

Yu. I. Yermolaev; V. V. Stupin

1990-01-01

163

Alpha-particle condensation in 16O via a full four-body OCM calculation  

E-print Network

In order to explore the 4 \\alpha-particle condensate state in 16O, we solve a full four-body equation of motion based on the 4 \\alpha OCM (Orthogonality Condition Model) in a large 4 \\alpha model space spanned by Gaussian basis functions. A full spectrum up to the 0_6^+ state is reproduced consistently with the lowest six 0^+ states of the experimental spectrum. The 0^+_6 state is obtained at about 2 MeV above the 4 \\alpha breakup threshold and has a dilute density structure, with a radius of about 5 fm. The state has an appreciably large \\alpha condensate fraction of 61 %, and a large component of \\alpha+12C(0_2^+) configuration, both features being reliable evidence for this state to be of 4 \\alpha condensate nature.

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

2008-02-22

164

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

Microsoft Academic Search

Gallium arsenide quantum well infrared photodetectors (QWIPs) are ideally suited for infrared imagery due to their detection capability over a wide infrared wavelength region and the feasibility of fabrication of monolithic two-dimensional arrays of such detectors. This paper reports on the effects of high energy proton and alpha particle radiations on the performance of these devices. The particle energies ranged

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

1996-01-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

166

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

167

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

SciTech Connect

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

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

2013-11-01

168

Thermomechanical and Microstructural Characterization of Geopolymers with alpha-Al2O3 Particle Filler  

Microsoft Academic Search

Geopolymers with different content of alpha-Al2O3 particle filler were prepared. The thermo-mechanical and microstructural characterization of the obtained geopolymers were systematically studied by flexural strength and thermal shrinkage measurements, TG-DTA (thermogravimetry and differential thermal analysis), XRD (X-ray diffractometry), and SEM (scanning electron microscopy). The results show that the addition of alpha-Al2O3 particle filler not only increases the onset crystalline temperature

T. S. Lin; D. C. Jia; P. G. He; M. R. Wang

2009-01-01

169

Feasibility of an alpha particle gas densimeter for stack sampling applications  

E-print Network

FEASIBILITY OF AN ALPHA PARTICLE GAS DENSIMETER FOR STACK SAMPLING APPLICATIONS A Thesis by RANDALL ~ JOHNSON Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE May l983 Major Subject: Nuclear Engineering FEASIBILITY OF AN ALPHA PARTICLE GAS DENSIMETER FOR STACK SAMPLING APPLICATIONS A Thesis by RANDALL MARK JO HN SON Approved as to style and content by: Ro ert A. F3e d (Ch irman of Committee...

Johnson, Randall Mark

2012-06-07

170

Traversal of cells by radiation and absorbed fraction estimates for electrons and alpha particles  

SciTech Connect

Consideration of the pathlength which radiation traverses in a cell is central to algorithms for estimating energy deposition on a cellular level. Distinct pathlength distributions occur for radionuclides: (1) uniformly distributed in space about the cell (referred to as -randomness); (2) uniformly distributed on the surface of the cell (S-randomness); and (3) uniformly distributed within the cell volume (I-randomness). For a spherical cell of diameter d, the mean pathlengths are 2/3d, 1/2d, and 3/4d, respectively, for these distributions. Algorithms for simulating the path of radiation through a cell are presented and the absorbed fraction in the cell and its nucleus are tabulated for low energy electrons and alpha particles emitted on the surface of spherical cells. The algorithms and absorbed fraction data should be of interest to those concerned with the dosimetry of radionuclide-labeled monoclonal antibodies. 8 refs., 3 figs., 2 tabs.

Eckerman, K.F.; Ryman, J.C.; Taner, A.C.; Kerr, G.D.

1985-01-01

171

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

172

Simple preparation of thin CR-39 detectors for alpha-particle radiobiological experiments  

NASA Astrophysics Data System (ADS)

Alpha-particle radiobiological experiments involve irradiating cells with alpha particles and require accurate positions where the alpha particles hit the cells. In the present work, we prepared thin CR-39 detectors from commercially available CR-39 SSNTDs with a thickness of 100 ?m by etching them in 1 N NaOH/ethanol at 40 °C to below 20 ?m. The desired final thickness was achieved within ˜8 h. Such etching conditions can provide relatively small roughness of the detector as revealed by atomic force microscope, and thus provide transparent detectors for radiobiological experiments. UV radiation was employed to shorten track formation time on these thin CR-39 detectors. After exposure to UV light (UVA + B radiation) for 2-3 h with doses from 259 to 389 W/cm 2, 5 MeV alpha-particle tracks can be seen to develop on these CR-39 detectors clearly under the optical microscope within 2 h in 14 N KOH at 37 °C. As an example for practical use, custom-made petri dishes, with a hole drilled at the bottom and covered with a thin CR-39 detector, were used for culturing HeLa cells. The feasibility of using these thin CR-39 detectors is demonstrated by taking photographs of the cells and alpha-particle tracks together under the optical microscope, which can allow the hit positions on the cells by the alpha particles to be determined accurately.

Chan, K. F.; Lau, B. M. F.; Nikezic, D.; Tse, A. K. W.; Fong, W. F.; Yu, K. N.

2007-10-01

173

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

174

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

175

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

176

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

NASA Astrophysics Data System (ADS)

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

Raab, W.; Parus, J. L.

1994-01-01

177

Correct Identification of Energetic Alpha and Proton Tracks in Experiments on CR-39 Charged Particle Detection during Hydrogen Desorption from Pd/PdO:Hx Heterostructure  

NASA Astrophysics Data System (ADS)

Results of correct identification of energetic alpha and proton tracks, observed after hydrogen desorption from Pd/PdO:Hx samples, are presented. Using CR-39 plastic track detector we unambiguously identified tracks of as minimum two groups of alpha particles with energies 10-13 and 15-17.5 MeV. It was also confirmed the emission of protons with energies ~1.7-1.9 MeV.

Roussetski, A. S.; Lipson, A. G.; Lyakhov, B. F.; Saunin, E. I.

178

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

SciTech Connect

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

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

1999-06-03

179

Alpha and beta particle induced scintillations in liquid and solid neon  

Microsoft Academic Search

Scintillations induced by alpha and beta particles in liquid and solid neon are studied and their light yield measured. Charged particle scintillation in neon is primarily in the extreme ultraviolet (EUV). We detect this EUV light by converting it to blue using a wavelength shifting fluor and detecting the blue light with a photomultiplier tube. It is observed that liquid

R. A. Michniak; R. Alleaume; D. N. McKinsey; J. M. Doyle

2002-01-01

180

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

181

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

182

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

SciTech Connect

Part of the energy of the Lower Hybrid (LH) waves may be absorbed by the ? particles via the so-called perpendicular landau damping mechanism, which depends on various parameters of fusion reactors and the LH waves. In this article, we calculate the absorption coefficient ?{sub ?} of LH waves due to ? particles. Results show that, the ?{sub ?} increases with the parallel refraction index n{sub ?} while deceases with increasing the frequency of LH waves ?{sub LH} over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of ?{sub ?} when n{sub e}?8×10{sup 19}m{sup ?3} for ITER-like scenario. The thermal corrections to the cold plasma dispersion relation will change the damping rate to a certain extent under some specific conditions. We have also evaluated the fraction of LH power absorbed by the alpha particles, ? ? 0.47% and 4.1% for an LH frequency of 5 GHz and 3.7 GHz respectively for ITER-like scenario. This work gives the effective reference for the choice of parameters of future fusion reactors.

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

2014-02-12

183

Energy deposition from particle beams  

NASA Astrophysics Data System (ADS)

A FORTRAN code named PARTEN, designed to compute electron or heavy-particle energy deposition in a layered, infinite plane target, was written and tested by comparison with measurements. Ease of use, transportability, and economy in computing times were primary considerations. The user may choose to include or omit energy loss straggling and multiple scattering detours. The user also has the optics of including a treatment of the photon electron multiplication and transport process for ion beams.

Osborne, W. Z.

1984-11-01

184

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

185

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

E-print Network

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

Manuel, Mario John-Errol

2008-01-01

186

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

187

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

188

Stellar Helium Burning: a Further Measurement of the Beta-Delayed Alpha-Particle Emission of (16)N  

NASA Astrophysics Data System (ADS)

The 12C(?,?)16O reaction is of critical importance for understanding stellar evolution. During helium burning this reaction competes with the triple-alpha reaction that forms carbon. The final carbon/oxygen ratio at the end of this burning stage largely determines the final stages of the star. The beta-delayed alpha-emission of 16N (i.e. prompt alpha-particles emitted from excited states of 16O populated by the slow beta-decay of 16N) has been predicted to provide a constraint on the cross section of this reaction, but requires a high sensitivity (B.R. ~ 10-9) measurement. The low energy portion of the alpha-particle spectrum has been predicted to provide a sensitive means to deduce the reduced alpha-particle width of the bound 1- state in 16O. In the past few years three attempts have been made to constrain the p-wave component of this cross section using the beta-delayed alpha-particle emission of 16N. In this work we have made a high statistics measurement of this spectrum as a continuation of our earlier low statistics Yale-UConn experiment. We have improved the statistics by a factor of more than 5, the energy resolution by 20%, and we demonstrate an understanding of our line shape from known and measured quantities. Our newly measured spectrum is compared to the three previous high statistics experiments and found to be consistent with the experimental results from Mainz and Seattle and inconsistent with those from TRIUMF. Our discrepancy with the TRIUMF results is in the width of the primary peak, with the largest differences (nearly a factor of two) near the region of the interference minimum. This region of the spectrum determines the size of the f-wave contribution to the low energy secondary maximum. This is crucial as the magnitude of the p-wave contribution only is of importance to astrophysics due to the low energy (~300 keV) that stellar helium burning occurs in massive stars. We conclude that with the current data sets the p-wave S-factor of the 12C(?,?)16O reaction cannot be determined at this stage with the accuracy (15-20%) required for the stellar evolution models developed by Woosley and Weaver.

France, Ralph Hayward, III

1997-11-01

189

Folding model analysis of alpha-particle elastic scattering with a semirealistic density dependent effective interaction  

SciTech Connect

The aim of this study was to examine the density dependent effective interaction, DDEI, applied in the double-folding model and to investigate whether folding model analyses of alpha particle elastic scattering could be used to calculate nuclear matter densities. Accordingly, differential cross-sections for the elastic scattering of alpha particles from (40)Ca, (46,48,50)Ti, (58)Ni, (90)Zr and (208)Pb at 140 MeV and from (58,60,62,64)Ni at 172 MeV were analyzed using the model with a semirealistic DDEI based on the M3Y interaction for the real potential and various phenomenological imaginary potentials. Good fits with consistent parameters of the model were obtained. The application of folding model analyses of alpha particle elastic scattering to the determination of nuclear matter density distribution was critically examined.

Kobos, A.M.; Brown, B.A.; Hodgson, P.E.; Satchler, G.R.; Budzanowski, A.

1982-01-01

190

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

PubMed Central

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

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

2014-01-01

191

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

192

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

193

Plasma heating from alpha particle micro-instabilities  

SciTech Connect

Potential use of thermonuclear (i.e., fusion product) driven kinetic instabilities to heat the background plasma has long been recognized. Considerable research on velocity space micro-instabilities exists. Most work to date has focused upon the basic physics criteria for and characteristics of particular micro-instabilities. Kinetic instabilities resulting in spatial transport of fusion products have also received some attention, but the effects on reactor concepts and performance remain uncertain. We have developed an engineering model which scopes the effect of a velocity space relaxation of fast alphas on a quasi-linear time scale. This model includes the additional heating to background plasma ions under the assumptions of: ion damping of the plasma wave; heating to background plasma results predominantly from fusion products; and periodic hiccups of the instability.

Miley, G.H.; Sutton, W.R.; Choi, C.K.

1981-01-01

194

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

195

TAE SATURATION OF ALPHA PARTICLE DRIVEN INSTABILITY IN TFTR \\Lambda  

E-print Network

Radius (FLR) effects [8], allows the expression for the growth rate and saturation level to be integrated be appreciably bigger than fl d . Here fl L is the linear TAE growth rate, fl d is the TAE damping rate, ! b perturbed magnetic energy and wave kinetic energy so that WE = R d 3 rffiB \\Delta ffiB=4Ã?, where ffi

196

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

197

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

198

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

199

Calculation of absorbed fractions to human skeletal tissues due to alpha particles using the Monte Carlo and 3-D chord-based transport techniques.  

PubMed

Absorbed fraction (AF) calculations to the human skeletal tissues due to alpha particles are of interest to the internal dosimetry of occupationally exposed workers and members of the public. The transport of alpha particles through the skeletal tissue is complicated by the detailed and complex microscopic histology of the skeleton. In this study, both Monte Carlo and chord-based techniques were applied to the transport of alpha particles through 3-D microCT images of the skeletal microstructure of trabecular spongiosa. The Monte Carlo program used was 'Visual Monte Carlo--VMC'. VMC simulates the emission of the alpha particles and their subsequent energy deposition track. The second method applied to alpha transport is the chord-based technique, which randomly generates chord lengths across bone trabeculae and the marrow cavities via alternate and uniform sampling of their cumulative density functions. This paper compares the AF of energy to two radiosensitive skeletal tissues, active marrow and shallow active marrow, obtained with these two techniques. PMID:17569685

Hunt, J G; Watchman, C J; Bolch, W E

2007-01-01

200

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

201

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

SciTech Connect

The goal of these experiments is to establish a quantitative correlation between early DNA damage and cancer incidence in a way that would be helpful for assessing the carcinogenic risk of radon alone or in combination with specific indoor pollutants. Rat tracheal epithelium has been exposed in vivo to {sup 210}Po alpha particles in the presence and absence of NO{sub 2} or cigarette smoke. The major accomplishments so far are: the design and implementation of a tracheal implant to simulate radon alpha particle exposure, the measurement of DNA breaks in a small 7.0 mm segment of the trachea exposed to external x-irradiation, the measurement of the rate of repair of the x-ray induced tracheal DNA strand breaks, the measurement of DNA strand breaks following inhalation of cigarette smoke or NO{sub 2}, the measurement of tracheal DNA stand breaks following exposure to high doses {sup 210}Po alpha particle radiation, the assessment of the amount of mucous in the goblet cells and in the underlying mucous glands. So far we have been unable to detect DNA strand breaks in the tracheal epithelium as a result of exposure to NO{sub 2} cigarette smoke or {sup 210}Po alpha particles. We have developed a simple artificial' trachea consisting of rat tracheal epithelial cells growing on a basement membrane coated millipore filter. Experiments are proposed to utilize these artificial tracheas to eliminate the potential interference of increased mucous secretion and/or inflammation that can significantly affect the radiation dose from the alpha particles. 61 refs., 17 figs.

Burns, F.J.

1990-01-01

202

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

PubMed

Childhood exposure to ionizing radiation increases the risk of developing thyroid cancer later in life and this is suggested to be due to higher proliferation of the young thyroid. The interest of using high-LET alpha particles from Astatine-211 ((211)At), concentrated in the thyroid by the same mechanism as (131)I [1], in cancer treatment has increased during recent years because of its high efficiency in inducing biological damage and beneficial dose distribution when compared to low-LET radiation. Most knowledge of the DNA damage response in thyroid is from studies using low-LET irradiation and much less is known of high-LET irradiation. In this paper we investigated the DNA damage response and biological consequences to photons from Cobolt-60 ((60)Co) and alpha particles from (211)At in normal primary thyrocytes of different cell cycle status. For both radiation qualities the intensity levels of ?H2AX decreased during the first 24h in both cycling and stationary cultures and complete repair was seen in all cultures but cycling cells exposed to (211)At. Compared to stationary cells alpha particles were more harmful for cycling cultures, an effect also seen at the pChk2 levels. Increasing ratios of micronuclei per cell nuclei were seen up to 1Gy (211)At. We found that primary thyrocytes were much more sensitive to alpha particle exposure compared with low-LET photons. Calculations of the relative biological effectiveness yielded higher RBE for cycling cells compared with stationary cultures at a modest level of damage, clearly demonstrating that cell cycle status influences the relative effectiveness of alpha particles. PMID:24769180

Lyckesvärd, Madeleine Nordén; Delle, Ulla; Kahu, Helena; Lindegren, Sture; Jensen, Holger; Bäck, Tom; Swanpalmer, John; Elmroth, Kecke

2014-04-21

203

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

204

M-FISH analysis shows that complex chromosome aberrations induced by alpha -particle tracks are cumulative products of localized rearrangements.  

PubMed

Complex chromosome aberrations are characteristically induced after exposure to low doses of densely ionizing radiation, but little is understood about their formation. To address this issue, we irradiated human peripheral blood lymphocytes in vitro with 0.5 Gy densely ionizing alpha-particles (mean of 1 alpha-particle/cell) and analyzed the chromosome aberrations produced by using 24-color multiplex fluorescence in situ hybridization (M-FISH). Our data suggest that complex formation is a consequence of direct nuclear alpha-particle traversal and show that the likely product of illegitimate repair of damage from a single alpha-particle is a single complex exchange. From an assessment of the "cycle structure" of each complex exchange we predict alpha-particle-induced damage to be repaired at specific localized sites, and complexes to be formed as cumulative products of this repair. PMID:12205292

Anderson, Rhona M; Stevens, David L; Goodhead, Dudley T

2002-09-17

205

Alfven eigenmode and ion Bernstein wave studies for controlling fusion alpha particles  

NASA Astrophysics Data System (ADS)

In magnetic confinement fusion reactor plasmas, the charged fusion products (such as alpha particles in deuterium-tritium plasmas) will be the dominant power source, and by controlling these charged fusion products using wave-particle interactions the reactor performance could be optimized. This thesis studies two candidate waves: Mode-Converted Ion Bernstein Waves (MCIBWs) and Alfvén Eigenmodes (AEs). Rates of MCIBW-driven losses of alpha-like fast deuterons, previously observed in the Tokamak Fusion Test Reactor (TFTR), are reproduced by a new model so that the wave-particle diffusion coefficient can be deduced. The MCIBW power in TFTR is found to be ~ 1/3 that needed for collisionless alpha particle control. A reasonable reactor power scaling is derived. To study AEs, existing magnetic fluctuation probes at the Joint European Torus (JET) have been absolutely calibrated from 30-500 kHz for the first time, allowing fluctuation measurements with |dBpol|/B0>10- 8 and toroidal mode numbers |n|<32 using an 8-channel, 4-second, 1-MHz digitizer. Data analysis and database tools have been developed and applied to 4280 JET discharges using hydrogen, deuterium, tritium and helium-3. Three classes of AEs (driven by fast ions from various ion cyclotron range-of-frequency heating (ICRH) schemes) are identified. New AE phenomena are observed. AEs are less stable in ``Optimised Shear'' plasmas. AE ``pitchfork splitting'' (amplitude modulation) has been discovered. In other discharges, chaotic AE amplitude evolution and two types of explosive behavior have been discovered and found to be consistent with theoretical expectations. The strongest AEs appear to redistribute fast ions. No evidence for alpha-particle driven AEs has been found. ICRH beatwaves are studied as a potential AE driver. The beatwave spectrum has been discovered to include multiple beat-frequency harmonies plus sums and differences of beat frequencies. AE excitation with beatwaves remains an area for future work. Data obtained incidentally regarding other plasma instabilities, including some of possible use for alpha particle control, are included for completeness. Finally, an integrated alpha particle control experiment is suggested, including a candidate scenario for JET.

Heeter, Robert Franklin

1999-12-01

206

Density-induced suppression of the alpha-particle condensate in nuclear matter and the structure of alpha cluster states in nuclei  

E-print Network

At low densities, with decreasing temperatures, in symmetric nuclear matter alpha-particles are formed, which eventually give raise to a quantum condensate with four-nucleon alpha-like correlations (quartetting). Starting with a model of alpha-matter, where undistorted alpha particles interact via an effective interaction such as the Ali-Bodmer potential, the suppression of the condensate fraction at zero temperature with increasing density is considered. Using a Jastrow-Feenberg approach, it is found that the condensate fraction vanishes near saturation density. Additionally, the modification of the internal state of the alpha particle due to medium effects will further reduce the condensate. In finite systems, an enhancement of the S state wave function of the c.o.m. orbital of alpha particle motion is considered as the correspondence to the condensate. Wave functions have been constructed for self-conjugate 4n nuclei which describe the condensate state, but are fully antisymmetrized on the nucleonic level. These condensate-like cluster wave functions have been successfully applied to describe properties of low-density states near the n alpha threshold. Comparison with OCM calculations in 12C and 16O shows strong enhancement of the occupation of the S-state c.o.m. orbital of the alpha-particles. This enhancement is decreasing if the baryon density increases, similar to the density-induced suppression of the condensate fraction in alpha matter. The ground states of 12C and 16O show no enhancement at all, thus a quartetting condensate cannot be formed at saturation densities.

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

2008-01-21

207

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

SciTech Connect

We report on an extensive on-line nuclear orientation study of the angular distribution of {alpha} particles emitted in the favored decay of neutron deficient At and Rn nuclei near the {ital N}=126 shell closure. Surprisingly large anisotropies were observed, showing pronounced changes from one isotope to another. Comparing these data with several theoretical models shows that anisotropic {alpha} emission in favored decays from near-spherical nuclei can well be explained within the shell model, implying that it is mainly determined by the structure of the decaying nucleus. {copyright} {ital 1996 The American Physical Society.}

NICOLE Collaboration and ISOLDE Collaboration

1996-12-01

208

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

209

Alpha particle induced gamma yields in uranium hexafluoride  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

210

Alpha Channeling in Rotating Plasma with Stationary Waves  

SciTech Connect

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

A. Fetterman and N.J. Fisch

2010-02-15

211

An alpha-particle emitting antibody ([213Bi]J591) for radioimmunotherapy of prostate cancer.  

PubMed

A novel alpha-particle emitting monoclonal antibody construct targeting the external domain of prostate-specific membrane antigen (PSMA) was prepared and evaluated in vitro and in vivo. The chelating agent, N-[2-amino-3-(p-isothiocyanatophen-yl)propyl]-trans-cyclohexane-1, 2-diamine-N,N',N',N'',N''-pentaacetic acid, was appended to J591 monoclonal antibody to stably bind the 213Bi radiometal ion. Bismuth-213 is a short-lived (t 1/2 = 46 min) radionuclide that emits high energy alpha-particles with an effective range of 0.07-0.10 mm that are ideally suited to treating single-celled neoplasms and micrometastatic carcinomas. The LNCaP prostate cancer cell line had an estimated 180,000 molecules of PSMA per cell; J591 bound to PSMA with a 3-nM affinity. After binding, the radiolabeled construct-antigen complex was rapidly internalized into the cell, carrying the radiometal inside. [213Bi]J591 was specifically cytotoxic to LNCaP. The LD50 value of [213Bi]J591 was 220 nCi/ml at a specific activity of 6.4 Ci/g. The potency and specificity of [213Bi]J591 directed against LNCaP spheroids, an in vitro model for micrometastatic cancer, also was investigated. [213Bi]J591 effectively stopped growth of LNCaP spheroids relative to an equivalent dose of the irrelevant control [213Bi]HuM195 or unlabeled J591. Cytotoxicity experiments in vivo were carried out in an athymic nude mouse model with an i.m. xenograft of LNCaP cells. [213Bi]J591 was able to significantly improve (P < 0.0031) median tumor-free survival (54 days) in these experiments relative to treatment with irrelevant control [213Bi]HuM195 (33 days), or no treatment (31 days). Prostate-specific antigen (PSA) was also specifically reduced in treated animals. At day 51, mean PSA values were 104 ng/ml +/- 54 ng/ml (n = 4, untreated animals), 66 ng/ml +/- 16 ng/ml (n = 6, animals treated with [213Bi]HuM195), and 28 ng/ml +/- 22 ng/ml (n = 6, animals treated with [213Bi]J591). The reduction of PSA levels in mice treated with [213Bi]J591 relative to mice treated with [213Bi]HuM195 and untreated control animals was significant with P < 0.007 and P < 0.0136, respectively. In conclusion, a novel [213Bi]-radiolabeled J591 has been constructed that selectively delivers alpha-particles to prostate cancer cells for potent and specific killing in vitro and in vivo. PMID:11085533

McDevitt, M R; Barendswaard, E; Ma, D; Lai, L; Curcio, M J; Sgouros, G; Ballangrud, A M; Yang, W H; Finn, R D; Pellegrini, V; Geerlings, M W; Lee, M; Brechbiel, M W; Bander, N H; Cordon-Cardo, C; Scheinberg, D A

2000-11-01

212

Production of the therapeutic radionuclides 193mPt and 195mPt with high specific activity via alpha-particle-induced reactions on 192Os.  

PubMed

For the production of therapy-relevant radionuclides (193m)Pt (T(1/2)=4.33 d) and (195m)Pt (T(1/2)=4.03 d) with a high specific activity, the (192)Os(alpha,n)(195m)Pt and (192)Os(alpha,3n)(193m)Pt nuclear reactions were investigated for the first time from their respective thresholds up to 28 MeV. Thin samples of enriched (192)Os were prepared by electrodeposition on Ni, and the conventional stacked-foil technique was used for cross-section measurements. The calculated thick target yields were found to be 0.013 MBq/microA h for the (192)Os(alpha,n)(195m)Pt reaction in the energy range of E(alpha)=24-->18 MeV, and 0.25 MBq/microA h for the (192)Os(alpha,3n)(193m)Pt reaction in the energy range of E(alpha)=28-->24 MeV. The two radionuclides could not be detected in the interactions of (3)He particles with (192)Os. A production method involving high-current alpha-particle irradiation of enriched (192)Os and efficient chemical separation of radioplatinum was developed. Batch yields of about 1 MBq (195m)Pt and 8.7 MBq (193m)Pt were achieved. Compared to the reactor production these batch yields are very low, but the (192)Os(alpha,n)(195m)Pt and (192)Os(alpha,3n)(193m)Pt reactions are superior with respect to the specific activity of the products which is higher by two orders of magnitude. PMID:18083038

Hilgers, K; Coenen, H H; Qaim, S M

2008-04-01

213

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

214

Measurement of potential alpha energy exposure and potential alpha energy concentration and estimating radiation dose of radon in Sari city in the north region of Iran.  

PubMed

In dwellings in Sari city in the northern region of Iran, the potential alpha energy exposure (PAEE) and potential alpha energy concentration (PAEC) have been measured and the radiation dose due to radon and its progenies has been estimated. In this study, the dosemeters DOSEman and SARAD GmbH (Germany), which are sensitive to alpha particles, were used. The population of the city of Sari is 495 369 people and the density of population is 116.5 people per km(2). A percentage of the total household population of Sari in areas of geographically different samples was selected. The PAEE, PAEC and radon concentration in four different seasons in a year in homes for sampling were measured. The mean PAEE due to indoor radon in homes of four cities in Sari city was estimated to be 28.23 Bq m(-3) and the mean PAEC was estimated to be 27.11 Bq m(-3). Also the mean indoor radon level was found to be 29.95 Bq m(-3). The annual dose equivalent is ?0.0151 ?Sv y(-1). Measurement results show that the average PAEE, PAEC and radon concentration are higher in winter than in other seasons. This difference could be due to stillness and lack of air movement indoors in winter. PMID:24292487

Rahimi, Seyed Ali; Nikpour, Behzad

2014-12-01

215

Targeted alpha-particle radiotherapy with 211At-labeled monoclonal antibodies.  

PubMed

An attractive feature of targeted radionuclide therapy is the ability to select radionuclides and targeting vehicles with characteristics that are best suited for a particular clinical application. One combination that has been receiving increasing attention is the use of monoclonal antibodies (mAbs) specifically reactive to receptors and antigens that are expressed in tumor cells to selectively deliver the alpha-particle-emitting radiohalogen astatine-211 (211At) to malignant cell populations. Promising results have been obtained in preclinical models with multiple 211At-labeled mAbs; however, translation of the concept to the clinic has been slow. Impediments to this process include limited radionuclide availability, the need for suitable radiochemistry methods operant at high activity levels and lack of data concerning the toxicity of alpha-particle emitters in humans. Nonetheless, two clinical trials have been initiated to date with 211At-labeled mAbs, and others are planned for the near future. PMID:17921029

Zalutsky, Michael R; Reardon, David A; Pozzi, Oscar R; Vaidyanathan, Ganesan; Bigner, Darell D

2007-10-01

216

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

217

Critical temperature for {alpha}-particle condensation in asymmetric nuclear matter  

SciTech Connect

The critical temperature for {alpha}-particle condensation in nuclear matter with Fermi surface imbalance between protons and neutrons is determined. The in-medium four-body Schroedinger equation, generalizing the Thouless criterion of the BCS transition, is applied using a Hartree-Fock wave function for the quartet projected onto zero total momentum in matter with different chemical potentials for protons and neutrons.

Sogo, Takaaki; Roepke, Gerd; Schuck, Peter [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay F-91406, France, Universite Paris-Sud, Orsay F-91505, France, and Laboratoire de Physique et Modelisation des Milieux Condenses, CNRS and Universite Joseph Fourier, 25 Avenue des Martyrs, Boite Postale 166, F-38042 Grenoble Cedex 9 (France)

2010-09-15

218

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

219

K Shell Ionizations of Carbon, Nitrogen, Oxygen, Fluorine and Neon by Proton and Alpha Particle Bombardments  

Microsoft Academic Search

The K Auger electron spectra have been measured for carbon, nitrogen, oxygen, fluorine and neon excited by protons and alpha particles of 0.5-2.6 MeV. In comparison with the spectra obtained by electron impact, the satellite lines have grown more intensively as projectiles become heavier. This indicates the presence of a contribution of simultaneous L shell ionization. A quantitative analysis has

Naoto Kobayashi; Nobuhiro Maeda; Hiroshi Hori; Masakatsu Sakisaka

1976-01-01

220

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 in a tokamak. A large number of alpha particle measurements and physics experiments were performed during

221

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

PubMed

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

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

2008-01-01

222

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

PubMed

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

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

2003-06-01

223

Evidence of DNA double strand breaks formation in Escherichia coli bacteria exposed to alpha particles of different LET assessed by the SOS response.  

PubMed

Ionizing radiation produces a plethora of lesion upon DNA which sometimes is generated among a relatively small region due to clustered energy deposition events, the so called locally multiply damaged sites that could change to DSB. Such clustered damages are more likely to occur in high LET radiation exposures. The effect of alpha particles of different LET was evaluated on the bacterium Escherichia coli either by survival properties or the SOS response activity. Alpha radiation and LET distribution was controlled by means of Nuclear Track Detectors. The results suggest that alpha particles produce two types of lesion: lethal lesions and SOS inducing-mutagenic, a proportion that varies depending on the LET values. The SOS response as a sensitive parameter to assess RBE is mentioned. PMID:22705051

Serment-Guerrero, Jorge; Breña-Valle, Matilde; Aguilar-Moreno, Magdalena; Balcázar, Miguel

2012-12-01

224

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

225

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

226

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

NASA Technical Reports Server (NTRS)

A power source that converts a-particle energy into electricity by coulomb collision in doped diamond films is described. Alpha particle decay from curium-244 creates electron-hole pairs by free- ing electrons and holes inside the crystal lattice in N- and P-doped diamond films. Ohmic contacts provide electrical connection to an electronic device. Due to the built-in electric field at the rectifying junction across the hT- and P-doped diamond films, the free electrons are constrained to traveling in generally one direction. This one direction then supplies electrons in a manner similar to that of a battery. The radioactive curium layer may be disposed on diamond films for even distribution of a-particle radiation. The resulting power source may be mounted on a diamond substrate that serves to insulate structures below the diamond substrate from a-particle emission. Additional insulation or isolation may be provided in order to prevent damage from a-particle collision. N-doped silicon may be used instead of N-doped diamond.

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

2004-01-01

227

Low-energy nuclear reactions and the alpha-nucleus optical potential: where do we stand?  

Microsoft Academic Search

Recent efforts to develop an accurate and reliable alpha-nucleus optical potential at low energies are presented. In view of the advent of new data on alpha elastic scattering and alpha radiative-capture reactions, the global semi-microscopic alpha-nucleus potential is revisited and compared with the updated database. Needs for improvements are discussed.

P. Demetriou; M. Axiotis

2007-01-01

228

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

229

Measurements of nonthermal confined alpha particles in Tokamak Test Fusion Reactor D{endash}T plasmas (invited)  

SciTech Connect

Experience with the {alpha} charge exchange recombination spectroscopy and pellet charge exchange confined, nonthermal alpha particle diagnostics over the first two years of Tokamak test fusion reactor (TFTR) D{endash}T operation is summarized. A brief summary of the concept, instrumentation, and analysis techniques for each diagnostic is given, followed by examples of alpha physics results. Issues important to further development of these diagnostic techniques for TFTR and ITER are discussed. {copyright} {ital 1997 American Institute of Physics.}

Stratton, B.C.; Budny, R.V.; Duong, H.H.; Mansfield, D.K.; Medley, S.S.; Redi, M.H. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Fonck, R.J.; McKee, G.R. [Department of Nuclear Engineering and Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)] [Department of Nuclear Engineering and Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Oedblom, A.; Wising, F. [Institute for Electromagnetic Field Theory, Chalmers University of Technology, S-412 96 Gothenburg (Sweden)] [Institute for Electromagnetic Field Theory, Chalmers University of Technology, S-412 96 Gothenburg (Sweden); Fisher, R.K.; McChesney, J.M.; Parks, P.B. [General Atomics, San Diego, California 92186 (United States)] [General Atomics, San Diego, California 92186 (United States); Petrov, M.P. [A. F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russia)] [A. F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russia); Gorelenkov, N.N. [TRINITI, Troitsk 14092 (Russia)] [TRINITI, Troitsk 14092 (Russia)

1997-01-01

230

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

Microsoft Academic Search

A method is presented in which material containing a complex mixture of alpha emitting radionuclides might be analyzed with minimal sample preparation and the individual specific activities of each alpha emitting species found. A theoretical relationship describing the pulse height distribution of an infinitely thick source of alpha activity is developed. This relationship is then fit to uranium and thorium

Kevin A. Phoenix

1997-01-01

231

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

232

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

233

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

234

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

PubMed

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

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

2003-01-01

235

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

236

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

Microsoft Academic Search

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

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

1975-01-01

237

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

238

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

239

Determination of alpha-particle track depths in CR-39 detector from their cross-sections and replica heights  

NASA Astrophysics Data System (ADS)

A challenging task in the application of solid-state nuclear track detectors (SSNTDs) is the measurement of depths of the tracks. One approach involves breaking and polishing the side of SSNTDs to reveal the cross-sections of the tracks for direct measurements. Recently, surface profilometry was used to measure the heights of the replicas of alpha-particle tracks to give the track depths. In the present work, systematic comparisons among the track depths for alpha-particles with normal incidence and different incident energies were made for these two methods. After irradiation, the detectors were etched in a 6.25 N aqueous solution of NaOH at 70 °C. Both long etching time of 15 h (to produce spherical-phase tracks) and short etching time from 1 to 8 h (to produce sharp-phase tracks) were used. Good agreement was achieved between the two methods for spherical-phase tracks but not for sharp-phase tracks. It has been found that the surface profilometry method only works for replicas for spherical-phase tracks. Replicas for sharp-phase tracks are easier to collapse or deform, so the surface profilometry method may not give correct results.

Ng, F. M. F.; Luk, K. Y.; Nikezic, D.; Yu, K. N.

2007-10-01

240

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

241

ON THE RELATIVE SPEED AND TEMPERATURE RATIO OF SOLAR WIND ALPHA PARTICLES AND PROTONS: COLLISIONS VERSUS WAVE EFFECTS  

SciTech Connect

We study the relative flow speed and the temperature ratio of alpha particles and protons and their connections to the helium ion abundance, the collisional age, and the power of transverse fluctuations within the inertial range. It is found that the alpha-to-proton temperature ratio, T{sub {alpha}}/T{sub p} , anti-correlates with the helium ion abundance. Despite a relatively high collisional age and small wave power, the ratio T{sub {alpha}}/T{sub p} can reach comparatively high values (even above 2) whenever the helium ion abundance is below about 0.02. In contrast, the differential speed of alpha particles with respect to protons is correlated with the total wave power and anti-correlated with the collisional age. Ultimately, the individual heating of each ion species is positively correlated with the total wave power. Our findings suggest that a high-friction collision could be efficient in reducing the differential speed between alpha particles and protons, but appears not to be sufficient to equalize the alpha and proton temperatures, i.e., to make T{sub {alpha}} {approx_equal} T{sub p} . This is a hint that the local wave heating process is acting on a timescale shorter than the collision time.

Bourouaine, Sofiane; Marsch, Eckart [Max-Planck-Institut fuer Sonnensystemforschung, 37191 Katlenburg-Lindau (Germany); Neubauer, Fritz M. [Institut fuer Geophysik und Meteorologie, Universitaet zu Koeln, Albertus-Magnus-Platz, Koeln 50923 (Germany)

2011-02-10

242

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

PubMed

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

Esaka, Fumitaka; Magara, Masaaki

2014-03-01

243

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

244

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

245

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

NASA Technical Reports Server (NTRS)

Many planetary surface processes (like physical and chemical weathering, water activity, diagenesis, low-temperature or impact metamorphism, and biogenic activity) leave traces of their actions as features in the size range 10s to 100s of micron. The Mapping alpha-particle X-ray Spectrometer ("Map-X") is intended to provide chemical imaging at 2 orders of magnitude higher spatial resolution than previously flown instruments, yielding elemental chemistry at or below the scale length where many relict physical, chemical, and biological features can be imaged and interpreted in ancient rocks.

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

2014-01-01

246

Alpha-particle emission probabilities in the decay of 239Pu  

NASA Astrophysics Data System (ADS)

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

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

1993-10-01

247

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

248

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

249

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.

250

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

251

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

PubMed

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

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

2007-03-01

252

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

NASA Astrophysics Data System (ADS)

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

Phoenix, Kevin A.

1997-10-01

253

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

254

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

255

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

PubMed

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

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

2008-02-01

256

Targeted Cytoplasmic Irradiation with Alpha Particles Induces Mutations in Mammalian Cells  

NASA Astrophysics Data System (ADS)

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

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

1999-04-01

257

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

258

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

259

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

NASA Astrophysics Data System (ADS)

In tokamaks, fusion generated ? particles may absorb lower hybrid (LH) wave energy, thus reducing the LH current drive efficiency. The absorption coefficient ?? of LH waves due to ? particles changing with some typical parameters is calculated in this paper. Results show that ?? increases with the parallel refraction index n ?, while decreases with the frequency of LH waves ? over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption. The absorption coefficient ?? increases with n e when n e ? 8 × 1019 m-3, while decreases with n e when n e becomes larger, and there is a peak value of ?? when n e ? 8 × 1019 m-1 for the ITER-like scenario. The influence of spectral broadening in parametric decay instabilities on the absorption coefficient is evaluated. The value of ?? with n ? being 2.5 is almost two times larger than that with n ? being 2.0 and is even lager in the case of 2.9, which will obviously increase the absorption of the LH power by alpha particles.

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

2014-12-01

260

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

261

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

EPA Science Inventory

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

262

Determination of alphas from energy-energy correlations measured on the Z0 resonance  

Microsoft Academic Search

We present a study of energy-energy correlations based on 83 000 hadronic Z0 decays. From this data we determine the strong coupling constant alphas to second order QCD: alphas(91.2 GeV)=0.121+\\/-0.004(exp.)+\\/-0.002(hadr.)-0.006+0.009(scale)+\\/-0.006(theor.) from the energy-energy correlation and alphas(91.2 GeV)=0.115+\\/-0.004(exp.)-0.004+0.007(hadr.)-0.000+0.002(scale)-0.005+0.003 (theor.) from its asymmetry using a renormalization scale mu1=0.1 s. The first error (exp.) is the systematic experimental uncertainly, the statistical error is

B. Adeva; O. Adriani; M. Aguilar-Benitez; H. Akbari; J. Alcaraz; A. Aloisio; G. Alverson; M. G. Alviggi; Q. An; H. Anderhub; A. L. Anderson; V. P. Andreev; T. Angelov; L. Antonov; D. Antreasyan; P. Arce; A. Arefiev; T. Azemoon; T. Aziz; P. V. K. S. Baba; P. Bagnaia; J. A. Bakken; L. Baksay; R. C. Ball; S. Banerjee; J. Bao; L. Barone; A. Bay; U. Becker; J. Behrens; S. Beingessner; Gy. L. Bencze; J. Berdugo; P. Berges; B. Bertucci; B. L. Betev; A. Biland; R. Bizzarri; J. J. Blaising; P. Blömeke; B. Blumenfeld; G. J. Bobbink; M. Bocciolini; W. Böhlen; A. Böhn; T. Böhringer; B. Borgia; D. Bourilkov; M. Bourquin; D. Boutigny; B. Bouwens; J. G. Branson; I. C. Brock; F. Bruyant; C. Buisson; A. Bujak; J. D. Burger; J. P. Burq; J. Busenitz; X. D. Cai; C. Camps; M. Capell; F. Carbonara; F. Carminati; A. M. Cartacci; M. Cerrada; F. Cesaroni; Y. H. Chang; U. K. Chaturvedi; M. Chemarin; A. Chen; C. Chen; G. M. Chen; H. F. Chen; H. S. Chen; M. Chen; M. L. Chen; G. Chiefari; C. Y. Chien; F. Chollet; C. Civinini; I. Clare; R. Clare; H. O. Cohn; G. Coignet; N. Colino; V. Commichau; G. Conforto; A. Contin; F. Crijns; X. Y. Cui; T. S. Dai; R. D'Alessandro; R. de Asmundis; A. Degré; K. Deiters; E. Dénes; P. Denes; F. Denotaristefani; M. Dhina; M. Diemoz; F. Diez-Hedo; H. R. Dimitrov; C. Dionisi; F. Dittus; R. Dolin; E. Drago; T. Driever; D. Duchesneau; P. Duinker; I. Duran; H. El Mamouni; A. Engler; F. J. Eppling; F. C. Erné; P. Extermann; R. Fabbretti; G. Faber; M. Fabre; S. Falciano; Q. Fan; S. J. Fan; O. Fackler; J. Fay; J. Fehlmann; H. Fenker; T. Ferguson; G. Fernandez; F. Ferroni; H. Fesefeldt; J. Field; F. Filthaut; G. Finocchiaro; P. H. Fisher; G. Forconi; T. Foreman; K. Freudenreich; W. Friebel; M. Fukushima; M. Gailloud; Yu. Galaktionov; E. Gallo; S. N. Ganguli; P. Garcia-Abia; S. S. Gau; S. Gentile; M. Glaubman; S. Goldfarb; Z. F. Gong; E. Gonzalez; A. Gordeev; P. Göttlicher; D. Goujon; G. Gratta; C. Grinnell; M. Gruenewald; M. Guanziroli; A. Gurtu; H. R. Gustafson; L. J. Gutay; H. Haan; S. Hancke; K. Hangarter; M. Harris; A. Hasan; D. Hauschildt; C. F. He; T. Hebbeker; M. Hebert; G. Herten; U. Herten; A. Hervé; K. Hilgers; H. Hofer; H. Hoorani; L. S. Hsu; G. Hu; B. Ille; M. M. Ilyas; V. Innocente; E. Isiksal; E. Jagel; B. N. Jin; L. W. Jones; R. A. Khan; Yu. Kamyshkov; Y. Karyotakis; M. Kaur; S. Khokhar; V. Khoze; M. N. Kienzle-Focacci; W. Kinnison; D. Kirkby; W. Kittel; A. Klimentov; A. C. König; O. Kornadt; V. Koutsenko; R. W. Kraemer; T. Kramer; V. R. Krastev; W. Krenz; J. Krizmanic; A. Kuhn; K. S. Kumar; V. Kumar; A. Kunin; A. van Laak; V. Lalieu; G. Landi; K. Lanius; D. Lanske; S. Lanzano; P. Lebrun; P. Lecomte; P. Lecoq; P. Le Coultre; D. Lee; I. Leedom; J. M. Le Goff; L. Leistam; R. Leiste; M. Lenti; J. Lettry; P. M. Levchenko; X. Leytens; C. Li; H. T. Li; J. F. Li; L. Li; P. J. Li; Q. Li; X. G. Li; J. Y. Liao; Z. Y. Lin; F. L. Linde; D. Linnhofer; R. Liu; Y. Liu; W. Lohmann; S. Lökös; E. Longo; Y. S. Lu; J. M. Lubbers; K. Lübelsmeyer; C. Luci; D. Luckey; L. Ludovici; X. Lue; L. Luminari; W. G. Ma; M. MacDermott; R. Magahiz; M. Maire; P. K. Malhotra; R. Malik; A. Malinin; C. Maña; D. N. Mao; Y. F. Mao; M. Maolinbay; P. Marchesini; A. Marchionni; J. P. Martin; L. Martinez; F. Marzano; G. G. G. Massaro; T. Matsuda; K. Mazumdar; P. McBride; T. McMahon; D. McNally; Th. Meinholz; M. Merk; L. Merola; M. Meschini; W. J. Metzger; Y. Mi; M. Micke; U. Micke; G. B. Mills; Y. Mir; G. Mirabelli; J. Mnich; M. Möller; B. Monteleoni; G. Morand; R. Morand; S. Morganti; R. Mount; E. Nagy; M. Napolitano; H. Newman; M. A. Niaz; L. Niessen; D. Pandoulas; F. Plasil; G. Passaleva; G. Paternoster; S. Patricelli; Y. J. Pei; D. Perret-Gallix; J. Perrier; A. Pevsner; M. Pieri; P. A. Piroué; V. Plyaskin; M. Pohl; V. Pojidaev; N. Produit; J. M. Qian; K. N. Qureshi; R. Raghavan; G. Rahal-Callot; P. Razis; K. Read; D. Ren; Z. Ren; S. Reucroft; S. Riemann; O. Rind; C. Rippich; H. A. Rizvi; B. P. Roe; M. Röhner; S. Röhner; U. Roeser; Th. Rombach; L. Romero; J. Rose; S. Rosier-Lees; R. Rosmalen; Ph. Rosselet; J. A. Rubio; W. Ruckstuhl; H. Rykaczewski; M. Sachwitz; J. Salicio; G. Sanders; G. Sartorelli; G. Sauvage; A. Savin; V. Schegelsky; D. Schmitz; P. Schmitz; M. Schneegans; M. Schöntag; H. Schopper; D. J. Schotanus; H. J. Schreiber; R. Schulte; S. Schulte; K. Schultze; J. Schütte; J. Schwenke; G. Schwering; C. Sciacca; I. Scott; R. Sehgal; P. G. Seiler; J. C. Sens; I. Sheer; V. Shevchenko; S. Shevchenko; X. R. Shi; K. Shmakov; V. Shoutko; E. Shumilov; N. Smirnov; A. Sopczak; C. Spartiotis; T. Spickermann; B. Spiess; P. Spillantini; R. Starosta; M. Steuer; D. P. Stickland; W. Stoeffl; B. Stöhr; H. Stone; K. Strauch; B. C. Stringfellow; K. Sudhakar; G. Sultanov; R. L. Sumner; L. Z. Sun; H. Suter; R. B. Sutton; J. D. Swain; A. A. Syed; X. W. Tang; E. Tarkovsky; L. Taylor; E. Thomas; C. Timmermans

1991-01-01

263

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

264

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

265

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

266

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

267

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

PubMed

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

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

2011-02-01

268

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

269

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

PubMed

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

Seferino?lu, Meryem; Dirican, Abdullah; Esra Erden, P?nar; Erçin, Demet

2014-12-01

270

Energy Loss of High-Energy Particles in Particle-in-Cell Simulation  

E-print Network

When a charged particle moves through a plasma at a speed much higher than the thermal velocity of the plasma, it is subjected to the force of the electrostatic field induced in the plasma by itself and loses its energy. This process is well-known as the stopping power of a plasma. In this paper we show that the same process works in particle-in-cell (PIC) simulations as well and the energy loss rate of fast particles due to this process is mainly determined by the number of plasma electrons contained in the electron skin depth volume. However, since there are generally very few particles in that volume in PIC simulations compared with real plasmas, the energy loss effect can be exaggerated significantly and can affect the results. Therefore, especially for the simulations that investigate the particle acceleration processes, the number of particles used in the simulations should be chosen large enough to avoid this artificial energy loss.

Kato, Tsunehiko N

2013-01-01

271

A direct determination of the energy release for the 3alpha breakup of the second-excited state of 12C  

Microsoft Academic Search

The energy difference between the second-excited state of 12C and three alpha-particles has been determined by implanting 12B ions within a silicon surface-barrier detector, and observing the pulses from the 3alpha decay of the second-excited state of 12C, formed in ~ 1.5% of the 12B decays. The result obtained, Q = 379.6 +\\/- 2.0 keV is in good agreement with

C. A. Barnes; Davis B. Nichols

1973-01-01

272

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

SciTech Connect

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

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

2006-04-01

273

Renal tubulointerstitial changes after internal irradiation with alpha-particle-emitting actinium daughters.  

PubMed

The effect of external gamma irradiation on the kidneys is well described. However, the mechanisms of radiation nephropathy as a consequence of targeted radionuclide therapies are poorly understood. The functional and morphologic changes were studied chronologically (from 10 to 40 wk) in mouse kidneys after injection with an actinium-225 (225Ac) nanogenerator, a molecular-sized, antibody-targeted, in vivo generator of alpha-particle-emitting elements. Renal irradiation from free, radioactive daughters of 225Ac led to time-dependent reduction in renal function manifesting as increase in blood urea nitrogen. The histopathologic changes corresponded with the decline in renal function. Glomerular, tubular, and endothelial cell nuclear pleomorphism and focal tubular cell injury, lysis, and karyorrhexis were observed as early as 10 wk. Progressive thinning of the cortex as a result of widespread tubulolysis, collapsed tubules, glomerular crowding, decrease in glomerular cellularity, interstitial inflammation, and an elevated juxtaglomerular cell count were noted at 20 to 30 wk after treatment. By 35 to 40 wk, regeneration of simplified tubules with tubular atrophy and loss with focal, mild interstitial fibrosis had occurred. A lower juxtaglomerular cell count with focal cytoplasmic vacuolization, suggesting increased degranulation, was also observed in this period. A focal increase in tubular and interstitial cell TGF-beta1 expression starting at 20 wk, peaking at 25 wk, and later declining in intensity with mild increase in the extracellular matrix deposition was noticed. These findings suggest that internally delivered alpha-particle irradiation-induced loss of tubular epithelial cells triggers a chain of adaptive changes that result in progressive renal parenchymal damage accompanied by a loss of renal function. These findings are dissimilar to those seen after gamma or beta irradiation of kidneys. PMID:15987754

Jaggi, Jaspreet Singh; Seshan, Surya V; McDevitt, Michael R; LaPerle, Krista; Sgouros, George; Scheinberg, David A

2005-09-01

274

Inner heliosphere spatial gradients of GCR protons and alpha particles in the low GeV range  

NASA Astrophysics Data System (ADS)

The spacecraft Ulysses was launched in October 1990 in the maximum phase of solar cycle 22, reached its final, highly inclined (80.2°) Keplerian orbit around the Sun in February 1992, and was finally switched off in June 2009. The Kiel Electron Telescope (KET) aboard Ulysses measures electrons from 3 MeV to a few GeV and protons and helium in the energy range from 6 MeV/nucleon to above 2 GeV/nucleon. In order to investigate the radial and latitudinal gradients of galactic cosmic rays (GCR), it is essential to know their intensity variations for a stationary observer in the heliosphere because the Ulysses measurements reflect not only the spatial but also the temporal variation of the energetic particle intensities. This was accomplished in the past with the Interplanetary Monitoring Platform-J (IMP 8) until it was lost in 2006. Fortunately, the satellite-borne experiment PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) was launched in June 2006 and can be used as a reliable 1 AU baseline for measurements of the KET aboard Ulysses. With these tools at hand, we have the opportunity to determine the spatial gradients of GCR protons and alpha particles at about 0.1 to 1 GeV/n in the inner heliosphere during the extended minimum of solar cycle 23. We then compare these A<0 magnetic epoch results with previous Ulysses/KET findings from the preceding A>0 cycle.

Gieseler, J.; Boezio, M.; Casolino, M.; De Simone, N.; Di Felice, V.; Heber, B.; Martucci, M.; Picozza, P.

2013-12-01

275

Radiochemical determination of cross sections of alpha-particle induced reactions on 192Os for the production of the therapeutic radionuclide 193mPt.  

PubMed

For determination of cross sections of alpha-particle induced reactions on 99.65% enriched (192)Os, the methods for electrolytic preparation of thin samples and radiochemical separation of radioplatinum were optimized. The excitation functions of the (192)Os(alpha,n)(195m)Pt and (192)Os(alpha,3n) (193m)Pt reactions were measured from 20 to 39 MeV. The cross section of the latter reaction reaches a maximum value of about 1.5b at an energy around 36 MeV. The results of nuclear model calculations using the codes TALYS and STAPRE agreed well with the measured data. The optimum energy range for the production of no-carrier-added (193m)Pt (T(1/2)=4.33 d) was found to be E(alpha)=40-->30 MeV. The thick target yield amounts to 10 MBq/microA h and a possible batch yield of 2 GBq should be sufficient for Auger electron therapy on a wide scale. PMID:20538474

Uddin, M S; Scholten, B; Hermanne, A; Sudár, S; Coenen, H H; Qaim, S M

2010-10-01

276

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

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

277

Monte-Carlo study of energy deposition by heavy charged particles in sub-cellular volumes.  

PubMed

Detailed-history Monte-Carlo code is used to study the energy deposition from proton and alpha particle tracks at the sub-cellular level. Inelastic cross sections for both the vapour and liquid phases of water have been implemented into the code in order to explore the influence of non-linear density effects associated with the condensed-phase cellular environment. Results of energy deposition and its straggling for 0.5 to 5 MeV amu(-1) protons and alpha particles traversing or passing near spherical volumes of 2-200 nm in diameter relevant to DNA- and chromosome-size targets are presented. It is shown that the explicit account of delta-ray transport reduces the dose by as much as 10-60%, whereas stochastic fluctuations lead to a relative uncertainty ranging from 20% to more than 100%. Protons and alpha particles of the same velocity exhibit a similar delta-ray effect, whereas the relative uncertainty of the alphas is almost half that of protons. The effect of the phase is noticeable (10-15%) mainly through differences on the transport of delta-rays, which in liquid water have higher penetration distances. It is expected that the implementation of such results into multi-scale biophysical models of radiation effects will lead to a more realistic predictions on the efficacy of new radiotherapeutic modalities that employ either external proton beam irradiation or internal alpha-emitting radionuclides. PMID:17513851

Emfietzoglou, D; Papamichael, G; Pathak, A; Fotopoulos, A; Nikjoo, H

2007-01-01

278

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

279

Time-dependent theory of alpha decay  

Microsoft Academic Search

Using Green's function techniques a time-dependent theory of ..cap alpha.. decay in the standard one-body model is developed. Formulas are obtained for the decay rate and ..cap alpha.. energy. These formulas are combined with experimental information to show that to a good approximation the initial ..cap alpha..-particle wave function vanishes on or near the nuclear surface.

Michael G. Fuda

1984-01-01

280

Time-dependent theory of alpha decay  

SciTech Connect

Using Green's function techniques a time-dependent theory of ..cap alpha.. decay in the standard one-body model is developed. Formulas are obtained for the decay rate and ..cap alpha.. energy. These formulas are combined with experimental information to show that to a good approximation the initial ..cap alpha..-particle wave function vanishes on or near the nuclear surface.

Fuda, M.G.

1984-09-01

281

Chinese high energy cosmic particle explorer (DAMPE)  

NASA Astrophysics Data System (ADS)

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

Chang, Jin; Hu, Yiming; Wu, Jian

282

Studies of High Energy Particle Astrophysics  

SciTech Connect

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

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

2014-07-30

283

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

284

Biophysical analysis of the dose-dependent overdispersion and the restricted linear energy transfer dependence expressed in dicentric chromosome data from alpha-irradiated human lymphocytes.  

PubMed

Experimental data for the induction of dicentric chromosomes in phytohemagglutinin (PHA)-stimulated human T lymphocytes by 241Am alpha-particles obtained by Schmid et al. have been analyzed in the light of biophysical theory. As usual in experiments with alpha-particles, the relative variance of the intercellular distribution of the number of aberrations per cell exceeds unity, and the multiplicity of the aberrations per particle traversal through the cell is understood as the basic effect causing this overdispersion. However, the clearly expressed dose dependence of the relative variance differs from the dose-independent relative variance predicted by the multiplicity effect alone. Since such dose dependence is often observed in experiments with alpha-particles, protons, and high-energy neutrons, the interpretation of the overdispersion needs to be supplemented. In a new, more general statistical model, the distribution function of the number of aberrations is interpreted as resulting from the convolution of a Poisson distribution for the spontaneous aberrations with the overdispersed distributions for the aberrations caused by intratrack or intertrack lesion interaction, and the fluctuation of the cross-sectional area of the cellular chromatin must also be considered. Using a suitable mathematical formulation of the resulting dose-dependent over-dispersion, the mean number lambda 1 of the aberrations produced by a single particle traversal through the cell nucleus and the mean number lambda 2 of the aberrations per pairwise approach between two alpha-particle tracks could be estimated. Coefficient alpha of the dose-proportional yield component, when compared between 241Am alpha-particle irradiation and 137Cs gamma-ray exposure, is found to increase approximately in proportion to dose-mean restricted linear energy transfer, which indicates an underlying pairwise molecular lesion interaction on the nanometer scale. PMID:9271796

Greinert, R; Harder, D

1997-06-01

285

STUDIES OF LOW-ENERGY NUCLEAR REACTIONS IN MEDIUM MASS NUCLEI--DECAY SCHEME STUDIES. Technical Progress Report, November 15, 1960 to November 14, 1961  

Microsoft Academic Search

Nuclear Reactions. Natural Mo foil targets were bombarded with alpha ; particles at energies up to 40 Mev, and excitation functions were determined for ; the following reactions: Mo⁹² ( alpha , n), ( alpha ,p), ( alpha , alpha ; 2n), ( alpha ,pn), ( alpha ,p2n) + ( alpha , 3n): and Mo¹°° ( alpha ,n). ; The

Pate

1962-01-01

286

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

287

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

288

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

289

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

290

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

PubMed Central

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

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

2008-01-01

291

Thorium and actinium polyphosphonate compounds as bone-seeking alpha particle-emitting agents.  

PubMed

The present study explores the use of alpha-particle-emitting, bone-seeking agents as candidates for targeted radiotherapy. Actinium and thorium 1,4,7,10 tetraazacyclododecane N,N',N'',N''' 1,4,7,10-tetra(methylene) phosphonic acid (DOTMP) and thorium-diethylene triamine N,N',N'' penta(methylene) phosphonic acid (DTMP) were prepared and their biodistribution evaluated in conventional Balb/C mice at four hours after injection. All three bone-seeking agents showed a high uptake in bone and a low uptake in soft tissues. Among the soft tissue organs, only kidney had a relatively high uptake. The femur/kidney ratios for 227Th-DTMP, 228-Ac-DOTMP and 227Th-DOTMP were 14.2, 7.6 and 6.0, respectively. A higher liver uptake of 228Ac-DOTMP was seen than for 227Th-DTMP and 227Th-DOTMP. This suggests that some demetallation of the 228Ac-DOTMP complex had occurred. The results indicate that 225Ac-DOTMP, 227Th-DOTMP and 227Th-DTMP have promising properties as potential therapeutic bone-seeking agents. PMID:15015582

Henriksen, Gjermund; Bruland, Oyvind S; Larsen, Roy H

2004-01-01

292

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

293

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

NASA Astrophysics Data System (ADS)

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

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

1999-01-01

294

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

SciTech Connect

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

Cheng, C.Z.; Stratton, B.; Zweben, S.J. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Pitcher, C.S. [Toronto Univ., Downsview, ON (Canada)

1993-11-01

295

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

296

Design and operation of the pellet charge exchange diagnostic for measurement of energetic confined {alpha} particles and tritons on the Tokamak Fusion Test Reactor  

SciTech Connect

Radially resolved energy and density distributions of the confined {alpha} particles in D{endash}T experiments on the Tokamak Fusion Test Reactor (TFTR) are being measured with the pellet charge exchange (PCX) diagnostic. Other energetic ion species can be detected as well, such as tritons produced in D{endash}D plasmas and H, He{sup 3}, or tritium rf-driven minority ion tails. The ablation cloud formed by injected low-{ital Z} impurity pellets provides the neutralization target for this active charge exchange technique. Because the cloud neutralization efficiency is uncertain, the PCX diagnostic is not absolutely calibrated so only relative density profiles are obtained. A mass and energy resolving {ital E}{parallel}{ital B} neutral particle analyzer (NPA) is used which has eight energy channels covering the energy range of 0.3{endash}3.7 MeV for {alpha} particles with energy resolution ranging from 5.8{percent} to 11.3{percent} and a spatial resolution of {approximately}5 cm. The PCX diagnostic views deeply trapped ions in a narrow pitch angle range around a mean value of {ital v}{parallel}/{ital v}={minus}0.048{plus_minus}10{sup {minus}3}. For D{endash}T operation, the NPA was shielded by a polyethylene{endash}lead enclosure providing 100{times} attenuation of ambient {gamma} radiation and 14 MeV neutrons. The PCX diagnostic technique and its application on TFTR are described in detail. {copyright} {ital 1996 American Institute of Physics.}

Medley, S.S.; Mansfield, D.K.; Roquemore, A.L. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Fisher, R.K.; Duong, H.H.; McChesney, J.M.; Parks, P.B. [General Atomics, San Diego, California 92186 (United States)] [General Atomics, San Diego, California 92186 (United States); Petrov, M.P.; Khudoleev, A.V. [A. F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russia)] [A. F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russia); Gorelenkov, N.N. [TRINITI, Troisk 142092 (Russia)] [TRINITI, Troisk 142092 (Russia)

1996-09-01

297

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

PubMed

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

Atanackovic, J

2012-06-01

298

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

299

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

300

Features of gas discharge in narrow-gap micropattern gas detectors at a high level of alpha-particle background  

NASA Astrophysics Data System (ADS)

Preliminary results of research into electron multiplication in micropattern gas detectors (MPGDs) at a high level of alpha-particle background are presented. This work has expanded the borders of understanding of the streamer mode nature. It is seen as a complex of electrostatic and electromagnetic interactions which begin the appearance of the precursor in plasma state. In an inter-electrode gap, plasma oscillations occur which are accompanied by longitudinal elastic waves of ionization, which can reach the cathode surface with an induced negative charge. With the release of this charge, due to the previously established conducting channel, there is a strong pulse accompanied by emission due to the recombination of positive and negative ions and a thin cord or streamer. With the aim of protecting the MPGDs from spark breakdown at a high-level alpha-particle background, the following gas composition of buffer, cooling, and electronegative components is offered: 70% He + 28% CF4 + 2% SF6.

Razin, V. I.; Reshetin, A. I.

2012-01-01

301

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

302

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

Microsoft Academic Search

We reported previously that the homologous recombinational repair (HRR)-deficient Chinese hamster mutant cell line irs3 (deficient in the Rad51 paralog Rad51C) showed only a 50% spontaneous frequency of sister chromatid exchange (SCE) as compared to parental wild-type V79 cells. Furthermore, when irradiated with very low doses of alpha particles, SCEs were not induced in irs3 cells, as compared to a

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

2008-01-01

303

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

Microsoft Academic Search

We reported previously that the homologous recombinational repair (HRR)-deficient Chinese hamster mutant cell line irs3 (deficient in the Rad51 paralog Rad51C) showed only a 50% spontaneous frequency of sister chromatid exchange (SCE) as compared to parental wild-type V79 cells. Furthermore, when irradiated with very low doses of alpha particles, SCEs were not induced in irs3 cells, as compared to a

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

2007-01-01

304

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

SciTech Connect

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

Wong, K.L.; Schmidt, G.L.; Batha, S.H.; Bell, R.; Chang, Z.; Chen, L.; Darrow, D.S.; Duong, H.H.; Fu, G.Y.; Hammett, G.W.; Levinton, F.; Majeski, R.; Mazzucato, E.; Nazikian, R.; Owens, D.K.; Petrov, M.; Rogers, J.H.; Schilling, G.; Wilson, J.R. [Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)] [Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)

1996-03-01

305

The cross-section for the binary and ternary fission of uranium and lead induced by 5.1, 8.8 and 12.7 GeV alpha-particles  

Microsoft Academic Search

Summary  The cross-sections for the binary and ternary fission of U and Pb induced by alpha-particles of energies at 5.1, 8.8 and 12.7\\u000a GeV have been determined by using a polycarbonate (makrofol) as a detector of the fission fragments. The values obtained for\\u000a the cross-sections are discussed and compared with those obtained with high-energy protons.

Ž. Todorovi?; R. Antanasijevic

1983-01-01

306

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

307

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

308

Effects of corotating interaction regions on Ulysses high energy particles  

SciTech Connect

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

Droege, W.; Kunow, H.; Heber, B.; Mueller-Mellin, R.; Sierks, H.; Wibberenz, G.; Raviart, A.; Ducros, R.; Ferrando, P.; Rastoin, C.; Paizis, C.; Gosling, J. T. [Institut fuer Kernphysik, Universitaet Kiel, 24118 Kiel (Germany); CEA, DSM/DAPNIA/Service d'Astrophysique, C.E. Saclay, 91191 Gif-sur-Yvette (France); Instituto Fisica Cosmica CNR, Universita di Milano, 20133 Milano (Italy); Los Alamos National Laboratory, Los Alamos New Mexico 87545 (United States)

1996-07-20

309

Effects of corotating interaction regions on Ulysses high energy particles  

SciTech Connect

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

Droege, W.; Kunow, H.; Heber, B.; Mueller-Mellin, R.; Sierks, H.; Wibberenz, G. [Institut fuer Kernphysik, Universitaet Kiel, 24118 Kiel (Germany); Raviart, A.; Ducros, R.; Ferrando, P.; Rastoin, C. [CEA, DSM/DAPNIA/Service dAstrophysique, C.E. Saclay, 91191 Gif-sur-Yvette (France); Paizis, C. [Instituto Fisica Cosmica CNR, Universita di Milano, 20133 Milano (Italy); Gosling, J.T. [Los Alamos National Laboratory, Los Alamos New Mexico 87545 (United States)

1996-07-01

310

Gamma Rays from Li7, F19, Ne22, and Na22 Produced by Alpha-Particle Bombardment of Lithium and Fluorine  

Microsoft Academic Search

The study of the gamma radiation following the inelastic scattering of alpha particles in thin fluorine and lithium targets has led to the discovery of new levels in the compound nuclei Na23 and B11. The (alpha, p) and (alpha, n) reactions in F19 have led to the establishment of the 1.28-Mev level as first-excited state of Ne22, and the discovery

N. P. Heydenburg; G. M. Temmer

1954-01-01

311

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

312

Measurement of the 187Re({\\alpha},n)190Ir reaction cross section at sub-Coulomb energies using the Cologne Clover Counting Setup  

E-print Network

Uncertainties in adopted models of particle+nucleus optical-model potentials directly influence the accuracy in the theoretical predictions of reaction rates as they are needed for reaction-network calculations in, for instance, {\\gamma}-process nucleosynthesis. The improvement of the {\\alpha}+nucleus optical-model potential is hampered by the lack of experimental data at astrophysically relevant energies especially for heavier nuclei. Measuring the Re187({\\alpha},n)Ir190 reaction cross section at sub-Coulomb energies extends the scarce experimental data available in this mass region and helps understanding the energy dependence of the imaginary part of the {\\alpha}+nucleus optical-model potential at low energies. Applying the activation method, after the irradiation of natural rhenium targets with {\\alpha}-particle energies of 12.4 to 14.1 MeV, the reaction yield and thus the reaction cross section were determined via {\\gamma}-ray spectroscopy by using the Cologne Clover Counting Setup and the method of {\\ga...

Scholz, P; Hennig, A; Netterdon, L; Becker, H W; Endres, J; Mayer, J; Giesen, U; Rogalla, D; Schlüter, F; Pickstone, S G; Zell, K O; Zilges, A

2015-01-01

313

Singlet and triplet energies of alpha-oligothiophenes: A spectroscopic, theoretical, and photoacoustic study: Extrapolation to polythiophene  

Microsoft Academic Search

The triplet state energies, ET(0-0), for the alpha-oligothiophenes (alphan's) with n=1-7, were determined and vary from 18 000 cm-1 (alpha2) to 13 000 cm-1 (alpha7). The data were obtained from spectroscopic and calorimetric measurements. It was found that the triplet energies decrease with the increase ring number (n), leveling off beginning with the alpha-oligothiophene with n=5. A linear relation was

J. Seixas de Melo; Luís M. Silva; Luís G. Arnaut; R. S. Becker

1999-01-01

314

STRV RADMON: An integrated high-energy particle detector  

Microsoft Academic Search

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,

Martin Buehler; George Soli; Brent Blaes; Gemma Tardio

1993-01-01

315

Incident-Energy Dependent Quenching of the Analyzing Power in Pre-Equilibrium Composite Particle Emission  

SciTech Connect

The proton-induced pre-equilibrium process in the energy range of 100 to 160 MeV, which leads to emission of composite ejectiles such as {sup 3}He and {alpha}-particles, is discussed. New cross section and analyzing power measurements for the (p,{sup 3}He) reaction on {sup 93}Nb at an incident energy of 160 MeV are presented, and these are found to be in agreement with the prediction of a statistical multistep theoretical formulation. The observed quenching of the analyzing power is also reproduced well by the theory. The results are consistent with earlier work at lower incident energies and other nuclear species.

Cowley, A. A. [Physics Department, Stellenbosch University, Private Bag X1, Matieland 7602 (South Africa); iThemba LABS, PO Box 722, Somerset West 7129 (South Africa); Dimitrova, S. S. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 1784 Sofia (Bulgaria); Zyl, J. J. van [Physics Department, Stellenbosch University, Private Bag X1, Matieland 7602 (South Africa)

2011-10-28

316

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

SciTech Connect

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

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

2011-02-15

317

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

PubMed Central

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

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

2013-01-01

318

Emission of Long-Range Alpha Particles in the Fission of U238 with 17.5MeV Protons  

Microsoft Academic Search

The angular distribution of long-range alpha particles from ternary fission induced by 17.5-MeV protons incident on U238 has been measured with respect to both the fission-fragment axis and the beam direction. For alpha particles emitted perpendicularly to the fragment direction, the distributions are found to be independent of the azimuthal angle about the fission-fragment separation axis and independent of the

R. A. Atneosen; T. D. Thomas; G. T. Garvey

1965-01-01

319

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

320

Determination of alphas from energy-energy correlations in e+e- annihilation at 29 GeV  

Microsoft Academic Search

We have studied the energy-energy correlation in e+e- annihilation into hadrons at &surd;s =29 GeV using the Mark II detector at the SLAC storage ring PEP. We find to O(alpha2s) that alphas=0.158+\\/-0.003+\\/-0.008 if hadronization is described by string fragmentation. Independent fragmentation schemes give alphas=0.10-0.14, and give poor agreement with the data. A leading-log shower fragmentation model is found to describe

R. D. Wood; A. Petersen; G. Abrams; C. E. Adolphsen; C. Akerlof; J. P. Alexander; M. Alvarez; D. Amidei; A. R. Baden; J. Ballam; B. C. Barish; T. Barklow; B. A. Barnett; J. Bartelt; D. Blockus; G. Bonvicini; A. Boyarski; J. Boyer; B. Brabson; A. Breakstone; J. M. Brom; F. Bulos; P. R. Burchat; D. L. Burke; F. Butler; F. Calvino; R. J. Cence; J. Chapman; D. Cords; D. P. Coupal; H. C. Destaebler; D. E. Dorfan; J. M. Dorfan; P. S. Drell; G. J. Feldman; E. Fernandez; R. C. Field; W. T. Ford; C. Fordham; R. Frey; D. Fujino; K. K. Gan; G. Gidal; L. Gladney; T. Glanzman; M. S. Gold; G. Goldhaber; L. Golding; A. Green; P. Grosse-Wiesmann; J. Haggerty; G. Hanson; R. Harr; F. A. Harris; C. M. Hawkes; K. Hayes; D. Herrup; C. A. Heusch; T. Himel; M. Hoenk; R. J. Hollebeek; D. Hutchinson; J. Hylen; W. R. Innes; M. Jaffre; J. A. Jaros; I. Juricic; J. A. Kadyk; D. Karlen; J. Kent; S. R. Klein; A. Koide; W. Koska; W. Kozanecki; A. J. Lankford; R. R. Larsen; B. W. Leclaire; M. E. Levi; Z. Li; A. M. Litke; N. S. Lockyer; V. Lüth; C. Matteuzzi; J. A. Matthews; D. I. Meyer; B. D. Milliken; K. C. Moffeit; L. Müller; J. Nash; M. E. Nelson; D. Nitz; H. Ogren; R. A. Ong; K. F. O'shaughnessy; S. I. Parker; C. Peck; M. L. Perl; M. Petradza; F. C. Porter; P. Rankin; B. Richter; K. Riles; P. C. Rowson; D. R. Rust; H. F. Sadrozinski; T. Schaad; T. L. Schalk; H. Schellman; W. B. Schmidke; A. S. Schwarz; A. Seiden; P. D. Sheldon; J. G. Smith; A. Snyder; E. Soderstrom; D. P. Stoker; R. Stroynowski; R. Thun; G. H. Trilling; R. Tschirhart; C. de La Vaissiere; R. van Kooten; H. Veltman; P. Voruganti; S. R. Wagner; P. Weber; A. J. Weinstein; A. J. Weir; S. Weisz; S. L. White; E. Wicklund; D. Y. Wu; J. M. Yelton

1988-01-01

321

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

322

Relative toxicity of chronic irradiation by 45Ca beta particles and 242Cm alpha particles with respect to the production of lung tumors in CBA/Ca mice.  

PubMed

Approximately 1800 female CBA/Ca mice were exposed by inhalation at three dose levels to beta particles from (45)Ca-labeled fused aluminosilicate particles (FAP), to alpha particles from (242)Cm-labeled FAP, or to carrier control FAP. Another group of mice inhaled no FAP and were designated as untreated cage controls. The FAP in combination with these radionuclides was used to achieve the same spatial and temporal distribution of alpha- and beta-particle dose within the irradiated mice. Some mice were killed to determine the clearance of radiolabeled FAP from their lungs, and the remainder were allocated to a life-span study. All animals were subjected to a detailed necropsy. To facilitate the identification of small tumors, the lungs were rendered transparent in methyl salicylate and examined under back illumination for the presence of lesions. Lung nodules and other microscopic lesions were excised for histological examination. The median survival of mice in all groups was approximately 910 days. The control animals lived longer than those that were irradiated, but it was difficult to determine a dose-response relationship for survival among the exposed mice. Benign adenomas and, less frequently, malignant adenocarcinomas were identified in all animal groups. The prevalence of these tumors was approximately 28.8% in the control mice, which is consistent with the results of other studies using the same strain of mouse. After exposure to radionuclide-labeled FAP, there was a significant dose-related increase in the prevalence of lung tumors in (242)Cm- (peak prevalence 55%) and (45)Ca-exposed (peak prevalence 48.6%) mice. The prevalence of tumors in the mice that received (242)Cm-labeled FAP was approximately twice that in the mice that inhaled (45)Ca-labeled FAP within the range of doses employed (0.55-4.69 Gy). Using the ratio of the slope of the linear component of the dose-response curves, the toxicity of the alpha particles relative to the beta particles was 1.5 (90% CI: 0.7, 9.0) for all adenomas and 9.4 (90% CI: 5.0, 23.0) for the less frequent adenocarcinomas. The relative toxicity for adenocarcinomas was found to decrease with increasing dose. PMID:17067209

Priest, N D; Hoel, D G; Brooks, P N

2006-11-01

323

Induction of linear tracks of DNA double-strand breaks by alpha-particle irradiation of cells.  

PubMed

Understanding how cells maintain genome integrity when challenged with DNA double-strand breaks (DSBs) is of major importance, particularly since the discovery of multiple links of DSBs with genome instability and cancer-predisposition disorders. Ionizing radiation is the agent of choice to produce DSBs in cells; however, targeting DSBs and monitoring changes in their position over time can be difficult. Here we describe a procedure for induction of easily recognizable linear arrays of DSBs in nuclei of adherent eukaryotic cells by exposing the cells to alpha particles from a small Americium source (Box 1). Each alpha particle traversing the cell nucleus induces a linear array of DSBs, typically 10-20 DSBs per 10 mum track length. Because alpha particles cannot penetrate cell-culture plastic or coverslips, it is necessary to irradiate cells through a Mylar membrane. We describe setup and irradiation procedures for two types of experiments: immunodetection of DSB response proteins in fixed cells grown in Mylar-bottom culture dishes (Option A) and detection of fluorescently labeled DSB-response proteins in living cells irradiated through a Mylar membrane placed on top of the cells (Option B). Using immunodetection, recruitment of repair proteins to individual DSB sites as early as 30 s after irradiation can be detected. Furthermore, combined with fluorescence live-cell microscopy of fluorescently tagged DSB-response proteins, this technique allows spatiotemporal analysis of the DSB repair response in living cells. Although the procedures might seem a bit intimidating, in our experience, once the source and the setup are ready, it is easy to obtain results. Because the live-cell procedure requires more hands-on experience, we recommend starting with the fixed-cell application. PMID:18309310

Stap, Jan; Krawczyk, Przemek M; Van Oven, Carel H; Barendsen, Gerrit W; Essers, Jeroen; Kanaar, Roland; Aten, Jacob A

2008-03-01

324

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

NASA Astrophysics Data System (ADS)

A guiding center orbit following code, which incorporates a set of non-singular coordinates for orbit integration, was developed and applied to investigate the alpha particle heating in an ITER-like tokamak with an internal transport barrier. It is found that a relatively large q (safety factor) value can significantly broaden the alpha heating profile in comparison with the local heating approximation; this broadening is due to the finite orbit width effects; when the orbit width is much smaller than the scale length of the alpha particle source profile, the heating profile agrees with the source profile, otherwise, the heating profile can be significantly broadened. It is also found that the stagnation particles move to the magnetic axis during the slowing-down process, thus the effect of stagnation orbits is not beneficial to the helium ash removal. The source profile of helium ash is broadened in comparison with the alpha source profile, which is similar to the heating profile.

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

2014-12-01

325

Experimental and theoretical studies of nuclear generation of ozone and its photolysis into singlet delta oxygen. [Alpha Particles  

Microsoft Academic Search

A series of measurements of Oâ yield in nuclear induced Oâ and Oâ-SFâ discharges created by bombardment with energetic particles from the ¹°B(n,..cap alpha..)⁷Li reaction are reported. Continuous irradiation at dose ratios of 10¹⁵⁻¹°sup 17\\/ eV.cm⁻³.s⁻¹ and pulsed irradiation (approx.10 ms FWHM) at a peak dose rate of approx.10²° eV.cm⁻³.s⁻¹ were conducted. At the lower dose rates, SFâ addition generally

Elsayed-Ali

1985-01-01

326

Development of sequence and regular band lasers for use as local oscillators in Thomson scattering alpha particle diagnostics (abstract)  

NASA Astrophysics Data System (ADS)

Heterodyne detection will be used to measure the scattered signal from a 100-MW pulsed CO2 laser Thomson scattered from energetic alpha particles. This measurement requires local oscillators displaced from the pump line by 6 to 21 GHz. We are developing cw sequence and regular band N2O and CO2 lasers which provide many lines in the required frequency range. The sequence lines are obtained by using a small in-cavity hot cell. Operating characteristics will be discussed for a variety of experimental arrangements.

Bennett, C. A.; Hutchinson, D. P.; Vander Sluis, K. L.; Staats, P. A.

1985-05-01

327

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

SciTech Connect

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

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

2003-03-26

328

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

329

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

330

The contribution of secondary heavy particles to the absorbed dose from high-energy photon beams.  

PubMed

High-energy photon radiotherapy sources produce non-negligible numbers of secondary heavy particles (neutrons, protons and alphas) which contribute to the dose in a patient. They also present a radiation protection problem. The contribution of such particles to the absorbed dose in a tissue-like medium and to the equivalent dose is considered in this study experimentally. Track etch detectors were chosen as a basic type of measuring instrument: cellulose nitrate Kodak LR115 and polyallyldiglycol carbonate CR39 were used as detectors. Several methods of directly read datum (track density, track parameter, LET spectrum etc) interpretation have been analysed. It has been ascertained that the contribution of secondary heavy particles represents approximately 0.002 of the photon dose and 0.02 of the equivalent dose, both at 50 MeV as maximum photon energy. The contribution of a 20 MV bremsstrahlung beam is roughly one-fifth of that at 50 MV. PMID:8971975

Spurný, F; Johansson, L; Sätherberg, A; Bednár, J; Turek, K

1996-12-01

331

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

SciTech Connect

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

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

1994-07-01

332

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

333

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

334

PGC-1alpha deficiency causes multi-system energy metabolic derangements: muscle dysfunction, abnormal weight control and hepatic steatosis.  

PubMed

The gene encoding the transcriptional coactivator peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) was targeted in mice. PGC-1alpha null (PGC-1alpha(-/-)) mice were viable. However, extensive phenotyping revealed multi-system abnormalities indicative of an abnormal energy metabolic phenotype. The postnatal growth of heart and slow-twitch skeletal muscle, organs with high mitochondrial energy demands, is blunted in PGC-1alpha(-/-) mice. With age, the PGC-1alpha(-/-) mice develop abnormally increased body fat, a phenotype that is more severe in females. Mitochondrial number and respiratory capacity is diminished in slow-twitch skeletal muscle of PGC-1alpha(-/-) mice, leading to reduced muscle performance and exercise capacity. PGC-1alpha(-/-) mice exhibit a modest diminution in cardiac function related largely to abnormal control of heart rate. The PGC-1alpha(-/-) mice were unable to maintain core body temperature following exposure to cold, consistent with an altered thermogenic response. Following short-term starvation, PGC-1alpha(-/-) mice develop hepatic steatosis due to a combination of reduced mitochondrial respiratory capacity and an increased expression of lipogenic genes. Surprisingly, PGC-1alpha(-/-) mice were less susceptible to diet-induced insulin resistance than wild-type controls. Lastly, vacuolar lesions were detected in the central nervous system of PGC-1alpha(-/-) mice. These results demonstrate that PGC-1alpha is necessary for appropriate adaptation to the metabolic and physiologic stressors of postnatal life. PMID:15760270

Leone, Teresa C; Lehman, John J; Finck, Brian N; Schaeffer, Paul J; Wende, Adam R; Boudina, Sihem; Courtois, Michael; Wozniak, David F; Sambandam, Nandakumar; Bernal-Mizrachi, Carlos; Chen, Zhouji; Holloszy, John O; Medeiros, Denis M; Schmidt, Robert E; Saffitz, Jeffrey E; Abel, E Dale; Semenkovich, Clay F; Kelly, Daniel P

2005-04-01

335

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

NASA Technical Reports Server (NTRS)

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

Gloeckler, G.

1975-01-01

336

Shape of the 4.438 MeV gamma-ray line of ^12C from proton and alpha-particle induced reactions on ^12C and ^16O  

E-print Network

We calculated in detail the angular distribution of gamma-rays and the resulting shape of the gamma-ray line produced by the nuclear deexcitation of the 4.439 MeV state of ^12C following proton and alpha-particle interactions with ^12C and ^16O in the energy range from threshold to 100 MeV per nucleon, making use of available experimental data. In the proton energy range from 8.6 to 20 MeV, the extensive data set of a recent accelerator experiment on gamma-ray line shapes and angular distributions was used to deduce parameterizations for the gamma-ray emission of the 2^+, 4.439 MeV state of ^12C following inelastic proton scattering off ^12C and proton induced spallation of ^16O. At higher proton energies and for alpha-particle induced reactions, optical model calculations were the main source to obtain the needed reaction parameters for the calculation of gamma-ray line shapes and angular distributions. Line shapes are predicted for various interaction scenarios of accelerated protons and alpha-particles in solar flares.

J. Kiener; N. de Sereville; V. Tatischeff

2001-05-16

337

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.

338

A primary standard for the measurement of alpha and beta particle surface emission rate at the National Metrology Institute of South Africa.  

PubMed

An absolute alpha and beta particle measurement system for the calibration of extended area sources has been established at the National Metrology Institute of South Africa (NMISA). Various characteristics of the measurement system were studied. Dead time and optimal values for high-voltage and low-energy discrimination were determined. The surface emission rates from four extended area sources (Am-241, Sr-90/Y-90, Cl-36 and C-14) that were previously certified by National Physical Laboratory (NPL) were measured. The results obtained with the NMISA measurement system and those from the NPL were in excellent agreement with E(n) values of below 0.25 being observed for all four sources. PMID:18358733

Mostert, J C

2008-01-01

339

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

340

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

341

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

342

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

SciTech Connect

This study examined the effect of internal exposure to {alpha}-particle radiation on subsequent fertility among women employed in radium dial industry prior to 1930, when appreciable amounts of radium were often ingested through the practice of pointing the paint brush with the lips. The analysis was limited to women for whom a radium body burden measurement had been obtained and who were married prior to age 45 (n = 603). Internal radiation dose to the ovary was calculated based on initial intakes of radium-226 and radium-228, average ovarian mass, number and energy of {alpha} particles emitted, fraction of energy absorbed within the ovary, effective retention integrals and estimated photon irradiation. Time between marriage and pregnancy, number of pregnancies and number of live births served as surrogates for fertility. Radiation appeared to have no effect on fertility at estimated cumulative ovarian dose equivalents below 5 Sv; above this dose, however, statistically significant declines in both number of pregnancies and live births were observed. These trends persisted after multivariable adjustment for potential confounding variables and after exclusion of subjects contributing a potential classification or selection bias to the study. Additionally, the high-dose group experienced fewer live births than would have been expected based on population rates. There were no differences in time to first pregnancy between high- and low-dose groups. These results are consistent with earlier studies of {gamma}-ray exposures and suggest that exposure to high doses of radiation from internally deposited radium reduces fertility rather than inducing sterility. 42 refs., 5 tabs.

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

1997-02-01

343

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

344

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

SciTech Connect

Southern Methodist University houses one of five existing commercially available UltraLo 1800 production model alpha counters made by XIA LLC. The instrument has an electron drift chamber with a 707 cm{sup 2} or 1800 cm{sup 2} counting region which is determined by selecting the inner electrode size. The SMU team operating this device is part of the SuperCDMS screening working group, and uses the alpha counter to study the background rates from the decay of radon in materials used to construct the SuperCDMS experiment. We have studied four acrylic samples obtained from the MiniCLEAN direct dark matter search with the XIA instrument demonstrating its utility in low background experiments by investigating the plate-out of {sup 210}Pb and comparing the effectiveness of cleaning procedures in removing {sup 222}Rn progenies from the samples.

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

2013-08-08

345

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

346

''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

347

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

348

Rejoining of double strand breaks in normal human and ataxia-telangiectasia fibroblasts after exposure to 60Co gamma-rays, 241Am alpha-particles or bleomycin.  

PubMed

The rejoining of DNA double strand breaks (dsb) induced by 60Co gamma-rays, 241Am alpha-particles or bleomycin was measured by neutral filter elution. In agreement with their colony-forming ability, ataxia-telangiectasia cells (AT2BE) and normal fibroblasts exhibited similar dsb rejoining capacity following alpha-irradiation, but showed marked differences in the rejoining kinetics of dsb induced by gamma-rays or bleomycin. PMID:2435666

Coquerelle, T M; Weibezahn, K F; Lücke-Huhle, C

1987-02-01

349

Variations of the hydrodynamic parameters of solar wind protons and alpha particles from Prognoz-7 measurements.  

NASA Astrophysics Data System (ADS)

The variations and relations between the hydrodynamic parameters of the proton and ? components of the solar wind have been investigated from the results of selective measurements of these components at the Prognoz-7 satellite. The parameter values averaged over the observation interval agree with their long-period variations during the solar cycle. With an increase in the solar wind velocity vp, the temperature Tp increases on the average as the power law v2.4p, while the concentration n decreases such that the momentum flux nvp2 is almost constant in the slow solar wind, but increases in the high-speed solar wind. The correlation observed between the temperature ratio T?/Tp and the magnitude of the difference of the ?-particle and proton velocities |v?-vp| suggests that the preferential heating of the ? particles is due not only to preferential acceleration of the ? particles, but also to any significant shift between the maxima of the ?-particle and proton distribution functions in velocity space. The conditions in the solar wind affecting the variation of the relative ?-particle abundance n?/np are investigated, along with the role of Coulomb viscosity of the components in balancing the difference in the velocities and temperatures of the protons and ? particles.

Ermolaev, Yu. I.; Stupin, V. V.; Zastenker, G. N.; Khamitov, G. P.; Kozak, I.

1990-09-01

350

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

SciTech Connect

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

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

2015-01-01

351

Amorphous silicon ionizing particle detectors  

DOEpatents

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

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

1988-01-01

352

Amorphous silicon ionizing particle detectors  

DOEpatents

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

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

1988-11-15

353

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

354

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

PubMed

Alpha-particle radiopharmaceutical therapy (?RPT) is currently enjoying increasing attention as a viable alternative to chemotherapy for targeting of disseminated micrometastatic disease. In theory, ?RPT can be personalized through pre-therapeutic imaging and dosimetry. However, in practice, given the particularities of ?-particle emissions, a dosimetric methodology that accurately predicts the thresholds for organ toxicity has not been reported. This is in part due to the fact that the biological effects caused by ?-particle radiation differ markedly from the effects caused by traditional external beam (photon or electron) radiation or ?-particle emitting radiopharmaceuticals. The concept of relative biological effectiveness (RBE) is used to quantify the ratio of absorbed doses required to achieve a given biological response with alpha particles versus a reference radiation (typically a beta emitter or external beam radiation). However, as conventionally defined, the RBE varies as a function of absorbed dose and therefore a single RBE value is limited in its utility because it cannot be used to predict response over a wide range of absorbed doses. Therefore, efforts are underway to standardize bioeffect modeling for different fractionation schemes and dose rates for both nuclear medicine and external beam radiotherapy. Given the preponderant use of external beams of radiation compared to nuclear medicine in cancer therapy, the more clinically relevant quantity, the 2 Gy equieffective dose, EQD2(?/?), has recently been proposed by the ICRU. In concert with EQD2(?/?), we introduce a new, redefined RBE quantity, named RBE2(?/?), as the ratio of the two linear coefficients that characterize the ? particle absorbed dose-response curve and the low-LET megavoltage photon 2 Gy fraction equieffective dose-response curve. The theoretical framework for the proposed new formalism is presented along with its application to experimental data obtained from irradiation of a breast cancer cell line. Radiobiological parameters are obtained using the linear quadratic model to fit cell survival data for MDA-MB-231 human breast cancer cells that were irradiated with either ? particles or a single fraction of low-LET (137)Cs ? rays. From these, the linear coefficient for both the biologically effective dose (BED) and the EQD2(?/?) response lines were derived for fractionated irradiation. The standard RBE calculation, using the traditional single fraction reference radiation, gave RBE values that ranged from 2.4 for a surviving fraction of 0.82-6.0 for a surviving fraction of 0.02, while the dose-independent RBE2(4.6) value was 4.5 for all surviving fraction values. Furthermore, bioeffect modeling with RBE2(?/?) and EQD2(?/?) demonstrated the capacity to predict the surviving fraction of cells irradiated with acute and fractionated low-LET radiation, ? particles and chronic exponentially decreasing dose rates of low-LET radiation. RBE2(?/?) is independent of absorbed dose for ?-particle emitters and it provides a more logical framework for data reporting and conversion to equieffective dose than the conventional dose-dependent definition of RBE. Moreover, it provides a much needed foundation for the ongoing development of an ?-particle dosimetry paradigm and will facilitate the use of tolerance dose data available from external beam radiation therapy, thereby helping to develop ?RPT as a single modality as well as for combination therapies. PMID:24377718

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

2013-12-30

355

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

PubMed Central

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

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

2014-01-01

356

Genomic Profiling of a Human Leukemic Monocytic Cell-Line (THP-1) Exposed to Alpha Particle Radiation  

PubMed Central

This study examined alpha (?-) particle radiation effects on global changes in gene expression in human leukemic monocytic cells (THP-1) for the purposes of mining for candidate biomarkers that could be used for the development of a biological assessment tool. THP-1 cells were exposed to ?-particle radiation at a dose range of 0 to 1.5 Gy. Twenty-four hours and three days after exposure gene expression was monitored using microarray technology. A total of 16 genes were dose responsive and classified as early onset due to their expression 24 h after exposure. Forty-eight transcripts were dose responsive and classified as late-onset as they were expressed 72 h after exposure. Among these genes, 6 genes were time and dose responsive and validated further using alternate technology. These transcripts were upregulated and associated with biological processes related to immune function, organelle stability and cell signalling/communication. This panel of genes merits further validation to determine if they are strong candidate biomarkers indicative of ?-particle exposure. PMID:23097634

Chauhan, Vinita; Howland, Matthew

2012-01-01

357

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

358

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

359

A comparison of the effects of ultraviolet radiation on CR-39 and lexan plastics irradiated by alpha particles  

NASA Astrophysics Data System (ADS)

A study of the effects of UV radiation on the damaged tracks of alpha particles and fission fragments in CR-39 and Lexan plastic detectors is reported. The increase in the track-density caused by UV exposure was found to be less than 40%. While the track-diameter in CR-39 plastics could be enhanced by 100%, the increase in Lexan was found to be more than 40%. Both the increase in the track-diameter and the track-density tend to saturate after the samples were exposed to the carbon are source for 3 h or to sunlight for 5 d approximately. Based on the large increase in the track-diameter, an application to measure personal doses of UV radiation using CR-39 track detectors is proposed.

Wong, C. F.; Hoberg, P.

1982-12-01

360

The cross-sections for the binary and ternary fission of uranium and thorium induced by 0.65, 1.74 and 4.11 GeV alpha-particles  

Microsoft Academic Search

Summary  The cross-sections for the binary and ternary fission of U and Th induced by alpha-particles of energies of 0.65, 1.74 and\\u000a 4.11 GeV have been determined by using a polycarbonate (macrofol) as a detector of the fission fragments. The values obtained\\u000a for the cross-sections are discussed and compared with those obtained by irradiation with high-energy protons and deuterons.

Ž. Todorovi?; R. Antanasijevic

1976-01-01

361

Inelastic Alpha Scattering Studies of Low-Energy Octupole Resonance  

E-print Network

the form of abroad (2 to 3 MeV' r n zxan distribution superimposed with nar- fre uen row states whose angular d' tr b t'xs i u cons were most recently not the same as that of the br ormed nucleus "'Sm two broad peaks were precognizable at most angles...- sult of two factors. First, the RPA predicts a weak LEQR at a modestly high excitation energy [which reduces the B(Z3) for a given EWSR frac- tion]. Second, the well-known tendency for other giant resonances to become increasingly broad...

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

1978-01-01

362

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

363

Automated image analysis of alpha-particle autoradiographs of human bone  

NASA Astrophysics Data System (ADS)

Further techniques [4,5] for the analysis of CR-39 ?-particle autoradiographs have been developed for application to ?-autoradiography of autopsy bone at natural levels for exposure. The most significant new approach is the use of fully automated image analysis using a system developed in this laboratory. A 5 cm × 5 cm autoradiograph of tissue in which the activity is below 1 Bq kg -1 is scanned to both locate and measure the recorded ?-particle tracks at a rate of 5 cm 2/h. Improved methods of calibration have also been developed. The techniques are described and in order to illustrate their application, a bone sample contaminated with 239Pu is analysed. Results from natural levels are the subject of a separate publication.

Hatzialekou, Urania; Henshaw, Denis L.; Fews, A. Peter

1988-01-01

364

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

365

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

PubMed

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

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

2008-11-01

366

Alpha particle and proton relative thermoluminescence efficiencies in LiF:Mg,Cu,P:is track structure theory up to the task?  

PubMed

Low-energy alpha particle and proton heavy charged particle (HCP) relative thermoluminescence (TL) efficiencies are calculated for the major dosimetric glow peak in LiF:Mg,Cu,P (MCP-N) in the framework of track structure theory (TST). The calculations employ previously published TRIPOS-E Monte Carlo track segment values of the radial dose in condensed phase LiF calculated at the Instituto National de Investigaciones Nucleares (Mexico) and experimentally measured normalised (60)Co gamma-induced TL dose-response functions, f(D), carried out at the Institute of Nuclear Physics (Poland). The motivation for the calculations is to test the validity of TST in a TL system in which f(D) is not supralinear (f(D) >1) and is not significantly dependent on photon energy contrary to the behaviour of the dose-response of composite peak 5 in the glow curve of LiF:Mg,Ti (TLD-100). The calculated HCP relative efficiencies in LiF:MCP-N are 23-87% lower than the experimentally measured values, indicating a weakness in the major premise of TST which exclusively relates HCP effects to the radiation action of the secondary electrons liberated by the HCP slowing down. However, an analysis of the uncertainties involved in the TST calculations and experiments (i.e. experimental measurement of f(D) at high levels of dose, sample light self-absorption and accuracy in the estimation of D(r), especially towards the end of the HCP track) indicate that these may be too large to enable a definite conclusion. More accurate estimation of sample light self-absorption, improved measurements of f(D) and full-track Monte Carlo calculations of D(r) incorporating improvements of the low-energy electron transport are indicated in order to reduce uncertainties and enable a final conclusion. PMID:22042968

Horowitz, Y S; Siboni, D; Oster, L; Livingstone, J; Guatelli, S; Rosenfeld, A; Emfietzoglou, D; Bilski, P; Obryk, B

2012-07-01

367

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

368

Acceleration of low energy charged particles by gravitational waves  

E-print Network

The acceleration of charged particles in the presence of a magnetic field and gravitational waves is under consideration. It is shown that the weak gravitational waves can cause the acceleration of low energy particles under appropriate conditions. Such conditions may be satisfied close to the source of the gravitational waves if the magnetized plasma is in a turbulent state.

G. Voyatzis; L. Vlahos; S. Ichtiaroglou; D. Papadopoulos

2005-12-07

369

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

PubMed

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

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

2006-09-22

370

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

2014-03-25

371

Energy Transduction Inside Vesicles by Mineral Particles: Formation of NADH  

NASA Astrophysics Data System (ADS)

Mineral semiconducting particles can be encapsulated inside vesicles, forming an energy transduction system that could have formed at any stage of the origin of life. This system can drive reactions such as the reduction of NAD+ to NADH.

Summers, D. P.; Noveron, J.; Basa, R. C. B.; Rodoni, D.

2010-04-01

372

Energy conservation potential of Portland cement particle size distribution control  

SciTech Connect

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

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

1986-01-01

373

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

PubMed

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

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

2014-05-01

374

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

E-print Network

to the second switching magnet were made of 0.29- mm tantalum in order to minimize slit-edge scat- tering. No slits were placed in the scattering chamber. All collimators were thus located such that slit-scattered n particles would have to tra- verse... from a 95/q en- riched isotope obtained from the Oak Ridge Nation- al Laboratory isotopes sales division. The Sm,O, was reduced in a tantalum-tube electron gun by heating in the presence of lanthanum metal to a temperature of approximately 1500'F...

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

1971-01-01

375

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

E-print Network

PHYSI CA L R EVI EW C VOLUME 6, NUMBER 5 NOVEMB ER 1972 138Elastic and Inelastic Scattering of n Particles from Ba J. H. Barker* and J. C. Hiebert Texas A & M University, College Station, Texas 77843 (Received 8 June 1972) Differential cross... multiplets at 3.34 and 3.50 MeV. Values of P&R' are obtained for all observed levels. Reasonable agreement for excitation en- ergies and J~ assignments has been obtained between the present results and previous experi- mental measurements and with recent...

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

1972-01-01

376

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

377

Limit on possible energy-dependent velocities for massless particles  

SciTech Connect

A basic tenet of special relativity is that all massless particles travel at a constant, energy-independent velocity. Astrophysical data, including observation of the Crab pulsar at {similar to}100 MeV and the recent detection of the pulsar in Hercules X-1 at energies {ge}100 TeV, are used to place new experimental constraints on energy-dependent deviations from constant velocity for massless particles. Previous experiments reached energies {similar to}10 GeV; this analysis improves the previous constraints by 7 orders of magnitude.

Haines, T.J.; Alexandreas, D.E.; Allen, R.C.; Biller, S.; Berley, D.; Burman, R.L.; Cady, D.R.; Chang, C.Y.; Dingus, B.L.; Dion, G.M.; Ellsworth, R.W.; Goodman, J.A.; Hoffman, C.M.; Lloyd-Evans, J.; Nagle, D.E.; Potter, M.; Sandberg, V.D.; Wilkinson, C.A.; Yodh, G.B. (The University of Maryland, College Park, Maryland 20742 (US) The University of California, Irvine, California 92717 (US) Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (US) George Mason University, Fairfax, Virginia 22030 (US))

1990-01-15

378

Strong absorption model analysis of alpha scattering  

NASA Astrophysics Data System (ADS)

Angular distribution of alpha particles at several energies, E(sub alpha) = 21 approx. 85.6 MeV from a number of nuclei between Ni-20 and Sn-119, extending to wide angular range up to approx. 160 C in some cases, have been analyzed in terms of three-parameter strong absorption model of Frahn and Venter. Interaction radius and surface diffuseness are obtained from the parameter values rendering the best fit to the elastic scattering data. The inelastic scattering of alpha particles from a number of nuclei, leading to quadrupole and octupole excitations has also been studied giving the deformation parameters (beta sub L).

Rahman, M. A.; Chandrapaul, S.; Sengupta, H. M.; Rahman, M.

1991-07-01

379

Alpha cluster structure in 56Ni  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

380

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

PubMed

This paper develops a deterministic model of frequency distributions for energy imparted (total energy deposition) in small volumes similar to DNA molecules from high-energy ions of interest for space radiation protection and cancer therapy. Frequency distributions for energy imparted are useful for considering radiation quality and for modeling biological damage produced by ionizing radiation. For high-energy ions, secondary electron (delta-ray) tracks originating from a primary ion track make dominant contributions to energy deposition events in small volumes. Our method uses the distribution of electrons produced about an ion's path and incorporates results from Monte Carlo simulation of electron tracks to predict frequency distributions for ions, including their dependence on radial distance. The contribution from primary ion events is treated using an impact parameter formalism of spatially restricted linear energy transfer (LET) and energy-transfer straggling. We validate our model by comparing it directly to results from Monte Carlo simulations for proton and alpha-particle tracks. We show for the first time frequency distributions of energy imparted in DNA structures by several high-energy ions such as cosmic-ray iron ions. Our comparison with results from Monte Carlo simulations at low energies indicates the accuracy of the method. PMID:10761008

Cucinotta, F A; Nikjoo, H; Goodhead, D T

2000-04-01

381

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

382

Simulation of coherent energy transfer in an alpha-helical peptide by Fermi resonance.  

PubMed Central

A mechanism by which NH stretching quanta are coherently transported along a chain of hydrogen bonded peptide groups is demonstrated by classical simulation of a section of the alpha-helical peptide poly(L-alanine). Vibrational motion takes place on a complex energy surface constructed from earlier ab initio and empirical surfaces. A speculative hypothesis of the biological role of this mechanism is presented, and the critical parameters governing the dynamics are identified and discussed. Images FIGURE 1 PMID:1547322

Clarke, D L; Collins, M A

1992-01-01

383

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

384

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

385

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

386

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

PubMed

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

2011-10-01

387

Sol-gel derived carbon ceramic electrode containing methylene blue-intercalated alpha-zirconium phosphate micro particles.  

PubMed

Methylene blue-intercalated alpha-zirconium phosphate (MBZrP) micro particles in deionized water were deposited onto the surface of graphite powder to prepare graphite powder-supported MBZrP, which was subsequently dispersed into methyltrimethoxysilane-derived gels to yield a conductive composite. The composite was used as electrode material to fabricate a surface-renewable, rigid, leak-free carbon ceramic composite electrode, bulk-modified with methylene blue (MB). In the configuration, alpha-zirconium phosphate was employed as a solid host for MB, which acted as a catalyst. Graphite powder ensured conductivity by percolation, the silicate provided a rigid porous backbone and the methyl groups endowed hydrophobicity and thus limited the wetting section of the modified electrode. Peak currents of the MBZrP-modified electrode were surface-confined at low scan rates but diffusion-controlled at high scan rates. Square-wave voltammetric study revealed that MBZrP immobilized in carbon ceramic matrix presented a two-electron, three-proton redox process in acidic aqueous solution with pH ranged from 0.44 to 2.94. In addition, the chemically modified electrode showed an electrocatalytic activity toward nitrite reduction at +0.15 V ( vs. Ag/AgCl) in acidic aqueous solution (pH=0.44). The linear range and detection limit are 1x10(-6)-4x10(-3) mol x L(-1) and 1.5x10(-7) mol x L(-1), respectively. PMID:11941443

Yuan, Yi; Wang, Peng; Zhu, Guoyi

2002-03-01

388

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

PubMed Central

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

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

2011-01-01

389

Effect of energy distribution on sorption kinetics in bidispersed particles  

SciTech Connect

In this article, the authors present a model to describe sorption kinetics of gaseous adsorbates onto bidispersed heterogeneous microporous particles. This model describes adsorption and desorption of gaseous adsorbates with allowance for the energy distribution of adsorption site for both equilibrium isotherm and diffusion of the adsorbed species. The adsorbed species of all energy levels diffuse in two directions inside the particle. One direction is the direction along the particle coordinate while the other is the direction perpendicular to the particle coordinate (that is, the direction into the grain of the solid). This model is more fundamental than models previously proposed by Do and coworkers. Effects of energy distribution on the adsorption and desorption dynamics are investigated. Extensive experimental analysis of adsorption and desorption dynamics of ethane and propane onto Ajax activated carbon are carried out to validate this theory.

Hu, Xijun; Rao, G.N.; Do, D.D. (Univ. of Queensland, Brisbane (Australia))

1993-02-01

390

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

391

STRV RADMON: An integrated high-energy particle detector  

NASA Astrophysics Data System (ADS)

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

392

Determination of 239Pu and 240Pu isotope ratio for a nuclear bomb particle using X-ray spectrometry in conjunction with gamma-ray spectrometry and non-destructive alpha-particle spectrometry  

Microsoft Academic Search

A nuclear bomb particle from Thule containing Pu and U was analyzed using X-ray spectrometry in combination with gamma-ray spectrometry and non-destructive alpha-spectrometry. The main objective was to investigate the possibility to determine the 239Pu and 240Pu isotope ratios. Previously, X-ray spectrometry together with the above-mentioned methods has been successfully applied for radiochemically processed samples, but not for individual particles.

R. Pöllänen; K. Ruotsalainen; H. Toivonen

2009-01-01

393

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

394

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

395

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

396

Alternative Discrete Energy Solutions to the Free Particle Dirac Equation  

E-print Network

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

Thomas Edward Brennan

2013-11-15

397

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

398

Effect of inhomogeneity in energy transfer through alpha helical proteins with interspine coupling  

NASA Astrophysics Data System (ADS)

The dynamics of homogeneous and inhomogeneous alpha helical proteins with interspine coupling is under investigation in this paper by proposing a suitable model Hamiltonian. For specific choice of parameters, the dynamics of homogeneous alpha helical proteins is found to be governed by a set of completely integrable three coupled derivative nonlinear Schrödinger (NLS) equations (Chen-Lee-Liu equations). The effect of inhomogeneity is understood by performing a perturbation analysis on the resulting perturbed three coupled NLS equation. An equivalent set of integrable discrete three coupled derivative NLS equations is derived through an appropriate generalization of the Lax pair of the original Ablowitz-Ladik lattice and the nature of the energy transfer along the lattice is studied.

Veni, S. Saravana; Latha, M. M.

2014-08-01

399

Improved peak shape fitting in alpha spectra.  

PubMed

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

Pommé, S; Caro Marroyo, B

2015-02-01

400

(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

401

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

E-print Network

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

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

2015-01-01

402

Particles and energy fluxes from a conformal field theory perspective  

SciTech Connect

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

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

2004-09-15

403

HgI2 low energy beta particle detector  

NASA Technical Reports Server (NTRS)

An HgI2 device structure was designed and tested which allows HgI2 to be used to make low-energy beta-particle detectors. The devices detected tritium beta particles with an efficiency of about 25 percent. A protective encapsulant has been developed which should protect the devices for up to 20 years and will attenuate only a small fraction of the beta particles. It is noted that the devices hold significant promise to provide a practical alternative to liquid scintillation counters and gas flow-through proportional counters.

Shah, K. S.; Squillante, M. R.; Entine, G.

1990-01-01

404

Energy Requirement for Lignocellulosic Feedstock Densifications in Relation to Particle Physical Properties, Preheating, and Binding  

E-print Network

Energy Requirement for Lignocellulosic Feedstock Densifications in Relation to Particle Physical the energy consumption of herbaceous feedstock compression in relation to particle physical properties was a function of the particle size, moisture content, and feedstock type. During pelletization, where all

405

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

406

Resonating-group calculation of radiative capture reactions alpha(He-3, gamma)Be-7 and alpha(t, gamma)Li-7 at astrophysical low energies  

NASA Astrophysics Data System (ADS)

Resonating-group analysis is used to determine the total cross sections and astrophysical reaction rates (S factors) of two radiative-capture reactions of importance in solar-evolution models. All available multipole contributions and the Pauli principle are accounted for, and the results are presented in graphs and a table. S factors for incident energies (Ecm) as low as 10 keV are determined without normalization, artificial parameters, or extrapolation for the reactions alpha(He-3, gamma)Be-7 and alpha(t, gamma)Li-7. At Ecm = 10 keV, the S factor for the Be-7 reaction is 0.508 keV barn. The S factors for the Li-7 reaction are found to be about five times smaller than those of Be-7; this difference is attributed to different threshold energies and Coulomb penetration factors. The solar-model implications are discussed in detail.

Kajino, T.; Arima, A.

1984-02-01

407

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

SciTech Connect

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

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

2008-04-22

408

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

409

Combined application of alpha-track and fission-track techniques for detection of plutonium particles in environmental samples prior to isotopic measurement using thermo-ionization mass spectrometry.  

PubMed

The fission track technique is a sensitive detection method for particles which contain radio-nuclides like (235)U or (239)Pu. However, when the sample is a mixture of plutonium and uranium, discrimination between uranium particles and plutonium particles is difficult using this technique. In this study, we developed a method for detecting plutonium particles in a sample mixture of plutonium and uranium particles using alpha track and fission track techniques. The specific radioactivity (Bq/g) for alpha decay of plutonium is several orders of magnitude higher than that of uranium, indicating that the formation of the alpha track due to alpha decay of uranium can be disregarded under suitable conditions. While alpha tracks in addition to fission tracks were detected in a plutonium particle, only fission tracks were detected in a uranium particle, thereby making the alpha tracks an indicator for detecting particles containing plutonium. In addition, it was confirmed that there is a linear relationship between the numbers of alpha tracks produced by plutonium particles made of plutonium certified standard material and the ion intensities of the various plutonium isotopes measured by thermo-ionization mass spectrometry. Using this correlation, the accuracy in isotope ratios, signal intensity and measurement errors is presumable from the number of alpha tracks prior to the isotope ratio measurements by thermal ionization mass spectrometry. It is expected that this method will become an effective tool for plutonium particle analysis. The particles used in this study had sizes between 0.3 and 2.0 ?m. PMID:21645753

Lee, Chi-Gyu; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki; Kimura, Takaumi

2011-07-15

410

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

PubMed

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

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

1997-08-01

411

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

412

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

413

Energy expectation values of a particle in nonstationary fields  

NASA Astrophysics Data System (ADS)

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

Silenko, Alexander J.

2015-01-01

414

PREFACE: The EPS High Energy Particle Physics Conference  

Microsoft Academic Search

HEPP2007, the EPS High Energy Particle Physics Conference, was held in Manchester from July 19-26 2007. It brought together 580 delegates across the whole subject: from string theorists to detector technologists, from young postgraduate students to senior professors. Geographically they came from the UK, from the rest of Europe, from North America, and from the rest of the world. It

Roger Barlow

2008-01-01

415

Energy conservation potential of Portland Cement particle size distribution control  

SciTech Connect

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

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

1986-01-01

416

Energy conservation potential of Portland cement particle size distribution control  

SciTech Connect

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

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

1986-01-01

417

Mass, Momentum and Kinetic Energy of a Relativistic Particle  

ERIC Educational Resources Information Center

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

Zanchini, Enzo

2010-01-01

418

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

SciTech Connect

Pitch-angle scattering, parallel spatial diffusion, and stochastic acceleration of cosmic rays are investigated analytically. Based on a second-order quasilinear theory, we deri