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1

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

2

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

3

Alpha Particle  

NASA Astrophysics Data System (ADS)

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

Murdin, P.

2000-11-01

4

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

5

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

6

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

7

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

PubMed

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

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

1992-05-01

8

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

Microsoft Academic Search

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

Robert C. Baumann

2011-01-01

9

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

PubMed Central

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

Lehnert, B E; Goodwin, E H

1997-01-01

10

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

Microsoft Academic Search

Anti-Tac, a monoclonal antibody directed to the human interleukin 2 (IL-2) receptor, has been successfully conjugated to the alpha-particle-emitting radionuclide bismuth-212 by use of a bifunctional ligand, the isobutylcarboxycarbonic anhydride of diethylenetriaminepentaacetic acid. The physical properties of 212Bi are appropriate for radioimmunotherapy in that it has a short half-life, deposits its high energy over a short distance, and can be

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

1986-01-01

11

Radioimmunotherapy with alpha-emitting nuclides.  

PubMed

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

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

1998-09-01

12

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

E-print Network

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

Bhakta, Viharkumar Satish

2011-10-21

13

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

14

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

15

Imaging alpha particle detector  

DOEpatents

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

Anderson, D.F.

1980-10-29

16

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

17

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

18

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

PubMed Central

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

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

1989-01-01

19

First In Vivo Evaluation of Liposome-encapsulated 223Ra as a Potential Alpha-particle-emitting Cancer Therapeutic Agent  

SciTech Connect

Liposomes carrying chemotherapeutics have had some success in cancer treatment and may be suitable carriers for therapeutic radionuclides. This study was designed to evaluate the biodistribution of and to estimate the radiation doses from the alpha emitter 223Ra loaded into pegylated liposomes in selected tissues. 223Ra was encapsulated in pegylated liposomal doxorubicin by ionophore-mediated loading. The biodistribution of liposomal 223Ra was compared to free cationic 223Ra in Balb/C mice. We showed that liposomal 223 Ra circulated in the blood with an initial half-time in excess of 24 hours, which agreed well with that reported for liposomal doxorubicin in rodents, while the blood half-time of cationic 223Ra was considerably less than one hour. When liposomal 223 Ra was catabolized, the released 223Ra was either excreted or taken up in the skeleton. This skeletal uptake increased up to 14 days after treatment, but did not reach the level seen with free 223Ra. Pre-treatment with non-radioactive liposomal doxorubicin 4 days in advance lessened the liver uptake of liposomal 223 Ra. Dose estimates showed that the spleen, followed by bone surfaces, received the highest absorbed doses. Liposomal 223 Ra was relatively stable in vivo and may have potential for radionuclide therapy and combination therapy with chemotherapeutic agents.

Jonasdottir, Thora J.; Fisher, Darrell R.; Borrebaek, Jorgen; Bruland, Oyvind S.; Larsen, Roy H.

2006-09-13

20

Solar flare alpha particles  

NASA Technical Reports Server (NTRS)

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

Lanzerotti, L. J.

1973-01-01

21

Cancer radioimmunotherapy with alpha-emitting nuclides.  

PubMed

In lymphoid malignancies and in certain solid cancers such as medullary thyroid carcinoma, somewhat mixed success has been achieved when applying radioimmunotherapy (RIT) with beta-emitters for the treatment of refractory cases. The development of novel RIT with alpha-emitters has created new opportunities and theoretical advantages due to the high linear energy transfer (LET) and the short path length in biological tissue of alpha-particles. These physical properties offer the prospect of achieving selective tumoural cell killing. Thus, RIT with alpha-emitters appears particularly suited for the elimination of circulating single cells or cell clusters or for the treatment of micrometastases at an early stage. However, to avoid non-specific irradiation of healthy tissues, it is necessary to identify accessible tumoural targets easily and rapidly. For this purpose, a small number of alpha-emitters have been investigated, among which only a few have been used for in vivo preclinical studies. Another problem is the availability and cost of these radionuclides; for instance, the low cost and the development of a reliable actinium-225/bismuth-213 generator were probably determining elements in the choice of bismuth-213 in the only human trial of RIT with an alpha-emitter. This article reviews the literature concerning monoclonal antibodies radiolabelled with alpha-emitters that have been developed for possible RIT in cancer patients. The principal radio-immunoconjugates are considered, starting with physical and chemical properties of alpha-emitters, their mode of production, the possibilities and difficulties of labelling, in vitro studies and finally, when available, in vivo preclinical and clinical studies. PMID:15841373

Couturier, Olivier; Supiot, Stphane; Degraef-Mougin, Marie; Faivre-Chauvet, Alain; Carlier, Thomas; Chatal, Jean-Franois; Davodeau, Franois; Cherel, Michel

2005-05-01

22

Radioluminescence yield of alpha particles in air  

NASA Astrophysics Data System (ADS)

Alpha particles can be detected by measuring the radioluminescence light which they induce when absorbed in air. The light is emitted in the near ultraviolet region by nitrogen molecules excited by secondary electrons. The accurate knowledge of the radioluminescence yield is of utmost importance for novel radiation detection applications utilizing this secondary effect. Here, the radioluminescence yield of an alpha particle is investigated as a function of energy loss in air for the first time. Also, the total radioluminescence yield of the particle is measured with a carefully calibrated ^{239}Pu emitter used in the experiments. The obtained results consistently indicate that alpha particles generate 193 photons per one MeV of energy released in air at normal pressure (temperature 22C, relative humidity 43%) and the dependence is found to be linear in the studied energy range from 0.3 MeV to 5.1 MeV. The determined radioluminescence yield is higher than previously reported for alpha particles and similar to the radioluminescence yield of electrons at comparable energies. This strengthens the evidence that the luminescence induced by charged particles is mostly proportional to the energy loss in the media and not very sensitive to the type of primary particle.

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

2014-05-01

23

Nuclear Alpha-Particle Condensates  

E-print Network

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

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

2011-03-21

24

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

25

Alpha-particle spectrometer experiment  

NASA Technical Reports Server (NTRS)

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

Gorenstein, P.; Bjorkholm, P.

1972-01-01

26

Commercial Availability of Alpha-Emitting Radionuclides for Medicine  

Microsoft Academic Search

Alpha-emitting radionuclides provide effective cell-killing properties and have been shown to be effective in cancer treatment. The number of different alpha emitters having suitable physical and chemical characteristics for applications in medicine is relatively few. Development and testing of new radiopharmaceuticals requires a reliable supply of alpha-emitters in high quality, with timely delivery, but at reasonable cost. Applications and commercial

Darrell R

2008-01-01

27

Use of superheated liquid dispersion technique for measuring alpha-emitting actinides in environmental samples  

Microsoft Academic Search

This paper presents a novel fast screening technique of measuring concentrations of alpha-emitting actinides in environmental samples. This novel technique is called superheated liquid dispersion (SLD), which involves dispersing fine superheated liquid (e.g. Freon-12) droplets into a mixture of glycerin and the actinide-containing chemical extractant. The interactions between alpha particles and superheated liquid droplets trigger bubbles. Therefore, one may relate

C. K. Wang; W. Lim; L. K. Pan

1994-01-01

28

Collection and Analysis of Aircraft Emitted Particles  

NASA Technical Reports Server (NTRS)

The University of Denver Aerosol Group proposed to adapt an impactor system for the collection of particles emitted by aircraft. The collection substrates were electron microscope grids which were analyzed by Dr. Pat Sheridan using a transmission electron microscope. The impactor was flown in the SNIFF behind aircraft and engine emissions were sampled. This report details the results of that work.

Wilson, James Charles

1999-01-01

29

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

30

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

NASA Astrophysics Data System (ADS)

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

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

31

Commercial Availability of Alpha-Emitting Radionuclides for Medicine  

SciTech Connect

Alpha-emitting radionuclides provide effective cell-killing properties and have been shown to be effective in cancer treatment. The number of different alpha emitters having suitable physical and chemical characteristics for applications in medicine is relatively few. Development and testing of new radiopharmaceuticals requires a reliable supply of alpha-emitters in high quality, with timely delivery, but at reasonable cost. Applications and commercial availability of the follow alpha emitters are reviewed: Actinium-225, bismuth-213, astatine-211, radium-223, bismuth-212, radium-224, radium-226, terbium-149, and thorium-227. Recommendations for improving the supply of these alpha emitters include an increased federal commitment (through funding and joint-agency cooperation), establishing new production capabilities, and strengthening federal-private partnerships with companies involved in helping to meet critical radionuclide supplies.

Fisher, Darrell R.

2008-09-15

32

Direct analysis of air filter samples for alpha emitting isotopes  

SciTech Connect

The traditional method for determination of alpha emitting isotopes on air filters has been to process the samples by radiochemical methods. However, this method is too slow for cases of incidents involving radioactive materials where the determination of personnel received dose is urgent. A method is developed to directly analyze the air filters taken from personal and area air monitors. The site knowledge is used in combination with alpha spectral information to identify isotopes. A mathematical function is developed to estimate the activity for each isotope. The strengths and weaknesses of the method are discussed.

Mohagheghi, A.H.; Ghanbari, F.; Ebara, S.B.; Enghauser, M.E. [Sandia National Labs., Albuquerque, NM (United States); Bakhtiar, S.N. [Westinghouse WIPP, Carlsbad, NM (United States)

1997-04-01

33

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

Pllnen, R; Siiskonen, T

2008-01-01

34

Use of superheated liquid dispersion technique for measuring alpha-emitting actinides in environmental samples  

NASA Astrophysics Data System (ADS)

This paper presents a novel fast screening technique of measuring concentrations of alpha-emitting actinides in environmental samples. This novel technique is called superheated liquid dispersion (SLD), which involves dispersing fine superheated liquid (e.g. Freon-12) droplets into a mixture of glycerin and the actinide-containing chemical extractant. The interactions between alpha particles and superheated liquid droplets trigger bubbles. Therefore, one may relate the number of bubbles to the actinide concentration in the sample. The results obtained from the computer simulation and the experiment support the above claim.

K. Wang, C.; Lim, W.; K. Pan, L.

1994-02-01

35

Use of superheated liquid dispersion technique for measuring alpha-emitting actinides in environmental samples  

NASA Astrophysics Data System (ADS)

This paper presents a novel fast screening technique of measuring concentrations of alpha-emitting actinides in environmental samples. This novel technique is called superheated liquid dispersion (SLD), which involves dispersing fine superheated liquid (e.g. Freon-12) droplets into a mixture of glycerin and the actinide-containing chemical extractant. The interactions between alpha particles and superheated liquid droplets trigger bubbles. Therefore, one may relate the number of bubbles to the actinide concentration in the sample. The results obtained from the computer simulation and the experiment support the above claim.

Wang, C. K.; Lim, W.; Pan, L. K.

1994-12-01

36

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

37

Angular distributions of sequentially emitted particles and gamma rays in deep inelastic processes  

SciTech Connect

A general theory for the angular distribution of sequentially emitted particles and gamma rays is developed. Comparison with experimental data allows one to obtain information on the fragment spin and misalignment. Angular distributions of sequentially emitted gammas, alphas, and fission fragments are discussed in detail. It is shown that the experimental data are consistent with the thermal excitation of angular momentum-bearing modes. The anomaly of sequential fission suggests the presence of a prompt or direct fission component. 13 figures.

Moretto, L.G.

1981-01-01

38

Alpha particle confinement in tandem mirrors  

SciTech Connect

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

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

1980-10-10

39

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

40

Absorbed fractions for alpha particles in ellipsoidal volumes.  

PubMed

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

Amato, Ernesto; Italiano, Antonio; Baldari, Sergio

2013-08-21

41

Absorbed fractions for alpha particles in ellipsoidal volumes  

NASA Astrophysics Data System (ADS)

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

Amato, Ernesto; Italiano, Antonio; Baldari, Sergio

2013-08-01

42

Fetal dosimetry from natural alpha-particle emitters.  

PubMed

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

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

1999-12-01

43

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

44

Deconvolution of Alpha Spectra From Hot Particles  

Microsoft Academic Search

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

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

45

Lunar surface outgassing and alpha particle measurements  

SciTech Connect

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

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

2002-01-01

46

Investigation of particles emitted from modern 2-stroke scooters  

NASA Astrophysics Data System (ADS)

Transmission electron microscopy (TEM), combined with X-ray energy dispersive spectroscopy (EDS)both single and tandem differential mobility analyzer (TDMA)have been used to investigate particles emitted by two modern 2-stroke scooters with different mixture preparation systems (direct injection and carburetor). In this study, we focused on investigating the influence of engine type and catalytic converter on morphology, volatility, and structure of the particles. The experiments showed an almost complete removal of the enormous number of exhaust particles when the temperature of an evaporation tube along the sampling line is increased from ambient to 400 C. These results suggest that the exhaust particles emitted by 2-stroke scooters are volatile and no indication on the occurrence of layer structure was found, regardless of the mixture preparation system of the engine. Exhaust particles scanned before the catalytic converter were higher in number and lost a larger fraction of their volume in the evaporation tube compared to those scanned downstream of it. The presence of three major particle groups was identified by TEM analyzes, namely particles that are dominant in number but unstable under vacuum at room temperature, soot-like agglomerates and calcium-rich particles. The size of the unstable particles obtained by TEM agrees fairly with the result measured by differential mobility analyzer (DMA). We conclude that number concentration and size distribution of the particles emitted by 2-stroke scooters, are roughly in the range of 4-stroke diesel engines; however, the nature of the particles is quite different.

Etissa, D.; Mohr, M.; Schreiber, D.; Buffat, P. A.

47

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

48

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

PubMed

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

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

2012-09-01

49

Alpha Particle Physics Experiments in the Tokamak Fusion Test Reactor  

SciTech Connect

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

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

1998-12-14

50

THE SPATIALLY RESOLVED H{alpha}-EMITTING WIND STRUCTURE OF P CYGNI  

SciTech Connect

High spatial resolution observations of the H{alpha}-emitting wind structure associated with the luminous blue variable star P Cygni were obtained with the Navy Prototype Optical Interferometer. These observations represent the most comprehensive interferometric data set on P Cyg to date. We demonstrate how the apparent size of the H{alpha}-emitting region of the wind structure of P Cyg compares between the 2005, 2007, and 2008 observing seasons and how this relates to the H{alpha} line spectroscopy. Using the data sets from 2005, 2007, and 2008 observing seasons, we fit a circularly symmetric Gaussian model to the interferometric signature from the H{alpha}-emitting wind structure of P Cyg. Based on our results, we conclude that the radial extent of the H{alpha}-emitting wind structure around P Cyg is stable at the 10% level. We also show how the radial distribution of the H{alpha} flux from the wind structure deviates from a Gaussian shape, whereas a two-component Gaussian model is sufficient to fully describe the H{alpha}-emitting region around P Cyg.

Balan, Aurelian; Tycner, C. [Department of Physics, Central Michigan University, Mount Pleasant, MI 48859 (United States); Zavala, R. T.; Benson, J. A.; Hutter, D. J. [US Naval Observatory, Flagstaff Station, 10391 W. Naval Observatory Rd., Flagstaff, AZ 86001 (United States); Templeton, M., E-mail: abalan@delta.ed, E-mail: c.tycner@cmich.ed, E-mail: bzavala@nofs.navy.mi, E-mail: jbenson@nofs.navy.mi, E-mail: djh@nofs.navy.mi, E-mail: matthewt@aavso.or [American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138 (United States)

2010-06-15

51

The Capture of Electrons by Swiftly Moving Alpha-Particles  

Microsoft Academic Search

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

Bergen Davis; A. H. Barnes

1929-01-01

52

Alpha-particle sensitive test SRAMs  

SciTech Connect

This paper reports on a bench-level test being developed to evaluate memory-cell upsets in a test SRAM designed with a cell offset voltage. This offset voltage controls the critical charge needed to upset the cell. The effect was demonstrated using a specially designed 2-{mu}m n-well CMOS 4k-bit test SRAM and a Po-208 5.1-MeV 0.61-LET alpha-particle source.

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

1990-12-01

53

Alpha-particle Gas Pressure Gauge  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

54

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

NASA Astrophysics Data System (ADS)

An innovative method has been demonstrated for separating alpha-emitting isotopes for medical radiotherapy applications. The method relies on recoil-ion separation rather than on conventional wet chemistry techniques to separate medical isotopes from their precursor sources. The isotopes 225Ac and 213Bi have been separated from electro-deposited sources of 229ThO 2. Separations of 225Ac were carried out by placing nickel recoil collector foils in firm contact with the 229ThO 2 sources. One-stage recoil-ion separations of 225Ac from 229Th have been performed as well as two-stage separations of 213Bi from previously recoil separated 225Ac. In addition, a direct recoil separation of 213Bi from 229Th has been demonstrated. The 213Bi from the one-stage direct separation has a high isotopic purity, but contains small amounts of long-lived 225Ac alpha activity. The two-stage separations of 213Bi produce high isotopic purity material (>99.9999%), but result in lower isotopic yields. Range-energy calculations have been carried out to determine the yields of recoil ions as a function of alpha-particle energy and ThO 2 thickness. The results of the calculations have been benchmarked with recoil separation measurements carried out using ThO 2 electro-deposits over a range of thickness. A computer code based on the generalized Bateman equations has been developed to allow calculations of the amounts of any isotope in the 229Th decay chain as a function of recoil separation exposure time and elapsed time after the separation. An excellent match has been obtained between the predictions of the Bateman calculations and the results of recoil separation measurements. The recoil separation method has proven to be a simple and effective way of separating medically useful isotopes such as 213Bi. In addition, the method has been shown to produce no chemical or radioactive wastes, in contrast to radiochemical separation methods, which generate mixed (chemical and radioactive) waste.

Ruddy, F. H.; Dulloo, A. R.; Seidel, J. G.; Petrovi?, B.

2004-01-01

55

Turbulent transport of alpha particles in reactor plasmas  

SciTech Connect

A systematic study of the behavior of energetic ions in reactor plasmas is presented. Using self-consistent gyrokinetic simulations, in concert with an analytic asymptotic theory, it is found that alpha particles can interact significantly with core ion-temperature-gradient turbulence. Specifically, the per-particle flux of energetic alphas is comparable to the per-particle flux of thermal species (deuterium or helium ash). This finding opposes the conventional wisdom that energetic ions, because of their large gyroradii, do not interact with the turbulence. For the parameters studied, a turbulent modification of the alpha-particle density profile appears to be stronger than turbulent modification of the alpha-particle pressure profile. Crude estimates indicate that the alpha density modification, which is directly proportional to the core turbulence intensity, could be in the range of 15% at midradius in a reactor. The corresponding modification of the alpha-particle pressure profile is predicted to be smaller (in the 1% range)

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

2006-11-15

56

Alpha-Particle Gas-Pressure Sensor  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

57

Local Control of Lung Derived Tumors by Diffusing Alpha-Emitting Atoms Released From Intratumoral Wires Loaded With Radium-224  

SciTech Connect

Purpose: Diffusing alpha-emitters radiation therapy (DART) is a new form of brachytherapy enabling the treatment of solid tumors with alpha radiation. The present study examines the antitumoral effects resulting from the release of alpha emitting radioisotopes into solid lung carcinoma (LL2, A427, and NCI-H520). Methods and Materials: An in vitro setup tested the dose-dependent killing of tumor cells exposed to alpha particles. In in vivo studies, radioactive wires (0.3 mm diameter, 5 mm long) with {sup 224}Ra activities in the range of 21-38 kBq were inserted into LL/2 tumors in C57BL/6 mice and into human-derived A427 or NCI-H520 tumors in athymic mice. The efficacy of the short-lived daughters of {sup 224}Ra to produce tumor growth retardation and prolong life was assessed, and the spread of radioisotopes inside tumors was measured using autoradiography. Results: The insertion of a single DART wire into the center of 6- to 7-mm tumors had a pronounced retardation effect on tumor growth, leading to a significant inhibition of 49% (LL2) and 93% (A427) in tumor development and prolongations of 48% (LL2) in life expectancy. In the human model, more than 80% of the treated tumors disappeared or shrunk. Autoradiographic analysis of the treated sectioned tissue revealed the intratumoral distribution of the radioisotopes, and histological analysis showed corresponding areas of necrosis. In vitro experiments demonstrated a dose-dependent killing of tumors cells exposed to alpha particles. Conclusions: Short-lived diffusing alpha-emitters produced tumor growth retardation and increased survival in mice bearing lung tumor implants. These results justify further investigations with improved dose distributions.

Cooks, Tomer [Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel); Schmidt, Michael [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv (Israel); Bittan, Hadas; Lazarov, Elinor [Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel); School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv (Israel); Arazi, Lior; Kelson, Itzhak [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv (Israel); Althera Medical Ltd., Tel Aviv (Israel); Keisari, Yona [Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel)], E-mail: ykeisari@post.tau.ac.il

2009-07-01

58

EVIDENCE FOR SPATIALLY COMPACT Ly{alpha} EMISSION IN z = 3.1 Ly{alpha}-EMITTING GALAXIES  

SciTech Connect

We present the results of a high spatial resolution study of the line emission in a sample of z = 3.1 Ly{alpha}-emitting galaxies (LAEs) in the Extended Chandra Deep Field-South. Of the eight objects with coverage in our HST/WFPC2 narrowband imaging, two have clear detections and two are barely detected ({approx}2 {sigma}). The clear detections are within {approx}0.5 kpc of the centroid of the corresponding rest-UV continuum source, suggesting that the line-emitting gas and young stars in LAEs are spatially coincident. The brightest object exhibits extended emission with a half-light radius of {approx}1.5 kpc, but a stack of the remaining LAE surface brightness profiles is consistent with the WFPC2 point-spread function. This suggests that the Ly{alpha} emission in these objects originates from a compact ({approx}<2 kpc) region and cannot be significantly more extended than the far-UV continuum emission ({approx}<1 kpc). Comparing our WFPC2 photometry to previous ground-based measurements of their monochromatic fluxes, we find at 95% (99.7%) confidence that we cannot be missing more than 22% (32%) of the Ly{alpha} emission.

Bond, Nicholas A.; Gawiser, Eric [Physics and Astronomy Department, Rutgers University, Piscataway, NJ 08854-8019 (United States); Feldmeier, John J. [Department of Physics and Astronomy, Youngstown State University, Youngstown, OH 44555 (United States); Matkovic, Ana; Gronwall, Caryl; Ciardullo, Robin, E-mail: nbond@physics.rutgers.ed, E-mail: gawiser@physics.rutgers.ed, E-mail: jjfeldmeier@ysu.ed, E-mail: matkovic@astro.psu.ed, E-mail: caryl@astro.psu.ed, E-mail: rbc@astro.psu.ed [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)

2010-06-20

59

Effects of inhaled alpha-emitting actin-ides on mouse alveolar macrophages  

SciTech Connect

The effects of inhaled alpha-emitting actinides on the alveolar macrophage (AM) population of the rodent lung are reviewed and, in particular, of the effects of [sup 239]PuO[sub 2] on murine AM. The effects discussed include changes that AM pool size, macrophage diameter, mobility, phagocytic competence, and enzyme content. Finally, similarities in the dose-response relationships for the induction of nuclear aberrations by alpha emitters and in the induction of lung tumors by the same materials are noted. 14 refs., 9 figs.

Morgan, A.; Talbot, R.J. (AEA Environment and Energy, Oxfordshire (United Kingdom))

1992-07-01

60

Macro-distribution of naturally occurring alpha-emitting isotopes of U in the human skeleton  

Microsoft Academic Search

Argonne National Laboratory (ANL) exhumed the remains of two individuals who had received Pu by intravenous injection, performed Pu analysis on these remains, and then sent portions of individual bones to our laboratory. We analyzed these bone samples to determine the macro-distribution of naturally occurring alpha-emitting isotopes of U (²³⁴U and ²³⁸U). We found that the sacrum contained the highest

Narayani P. Singh; David B. Bennett; McDonald E. Wrenn

1987-01-01

61

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

62

DISCOVERY OF AN H{alpha} EMITTING DISK AROUND THE SUPERMASSIVE BLACK HOLE OF M31  

SciTech Connect

Due to its proximity, the mass of the supermassive black hole in the nucleus of the Andromeda galaxy (M31), the most massive black hole in the Local Group of galaxies, has been measured by several methods involving the kinematics of a stellar disk which surrounds it. We report here the discovery of an eccentric H{alpha} emitting disk around the black hole at the center of M31 and show how modeling this disk can provide an independent determination of the mass of the black hole. Our model implies a mass of 5.0{sup +0.8}{sub -1.0} Multiplication-Sign 10{sup 7} M{sub Sun} for the central black hole, consistent with the average of determinations by methods involving stellar dynamics, and compatible (at 1{sigma} level) with measurements obtained from the most detailed models of the stellar disk around the central black hole. This value is also consistent with the M-{sigma} relation. In order to make a comparison, we applied our simulation on the stellar kinematics in the nucleus of M31 and concluded that the parameters obtained for the stellar disk are not formally compatible with the parameters obtained for the H{alpha} emitting disk. This result suggests that the stellar and the H{alpha} emitting disks are intrinsically different from each other. A plausible explanation is that the H{alpha} emission is associated with a gaseous disk. This hypothesis is supported by the detection of traces of weaker nebular lines in the nuclear region of M31. However, we cannot exclude the possibility that the H{alpha} emission is, at least partially, generated by stars.

Menezes, R. B.; Steiner, J. E.; Ricci, T. V., E-mail: robertobm@astro.iag.usp.br [Instituto de Astronomia Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, Sao Paulo, SP CEP 05508-090 (Brazil)

2013-01-10

63

Calibration and operation of continuous air monitors for alpha-emitting radionuclides  

SciTech Connect

Spectrometer-based continuous air monitors have improved our capabilities for detecting aerosols of alpha-emitting radionuclides. This paper describes basic requirements and statistical limitations in the sensitivity of alpha continuous air monitors, and presents a technical basis for selecting the energy window for detection of uranium and plutonium aerosols, correcting for interference from airborne dust, selecting filters with low pressure drop and good front surface collection characteristics, and properly using electroplated calibration sources. Sensitivity limits are described for detecting uranium or plutonium aerosols in the presence of increased concentrations of naturally occurring, alpha-emitting radon progeny radionuclides. Decreasing the lower energy boundary of the detection window from 4.3 MeV to 2.7 MeV improves by a factor of three the detection of plutonium in the presence of dust, while causing minimal additional interference from ambient radon progeny. Selection of the Millipore Fluoropore teflon membrane filter reduces both pressure drop and interference from ambient radon progeny by up to a factor of two. Field collection of ambient radon progeny can be used to verify the proper energy of alpha emissions from electroplated calibration sources. In the absence of energy verification, errors in instrument calibration may result from solid state diffusion of the electroplated calibration radionuclide into the substrate plate.

Hoover, M.D.; Newton, G.J.

1993-12-31

64

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

SciTech Connect

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

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

1982-11-01

65

Characterization of radioactive particles using non-destructive alpha spectrometry  

Microsoft Academic Search

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

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

2010-01-01

66

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

67

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

68

Depth Measurements Using Alpha Particles and Upsettable SRAMs  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

69

PC based analysis of alpha-particle spectra  

Microsoft Academic Search

Recently developed personal computer (PC) software performs analysis of alpha-particle spectra. The spectra are collected using a commercially available multichannel analyzer board in the PC, interfaced with up to eight (8) alpha-particle detectors. The PC is a IBM PC-AT computer with a 20 Mbyte Bernoulli Box removable cartridge disk, a math co-processor, and a printer. Once saved on disk, the

T CHAPMAN

1990-01-01

70

Coordination chemistry of the sup 212 Pb/ sup 212 Bi nuclear transformation: Alpha-emitting radiopharmaceuticals  

SciTech Connect

Subdivisions of this project are: (a) the synthesis of prototypical thiolate and dithiocarbamate based hexacoordinate complexes, (b) radiochemical engineering for generation of no-carrier-added lead and bismuth radioelements, (c) the first isolation of bismuth-binding proteins from in vivo studies with cyclotron produced {sup 205/206}Bi tracer, and (d) initial development of transport mechanisms for the intracellular radiobiological study of alpha emitting bismuth, and (e) the initiation of chemical equilibrium studies and biochemical pathways with cyclotron-produced, no-carrier-added, {sup 203}Pb (T{sub 1/2} = 51 hr).

Parks, N.J.; Harris, W.R.; Keen, C.L.; Cooper, S.R.

1992-07-01

71

Regarding action levels for contamination by alpha and beta emitting radionuclides.  

PubMed

Today, there exist a number of different international documents, regulating both civilian and military operations, which present action levels regarding contamination of alpha- and/or beta-emitting radionuclides. There are, however, inconsistencies among the action levels suggested in different documents, which can be explained only in part by differences in their intended use. Many of the suggested action levels are calculated using conservative estimates. This work presents some of the suggested action levels for skin contamination, their background and rationale, and discusses which implications they might have. The focus is on action levels and guidelines aimed at emergency situations and operations in radioactively contaminated areas. PMID:24978289

Boson, Jonas; Ulvsand, Thomas; Plamboeck, Agneta H

2014-08-01

72

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

73

Energetic alpha particle deposition in a magnetized plasma  

Microsoft Academic Search

The problem of energetic alpha particle deposition in a dense, magnetized deuterium-tritium (DT) thermonuclear fuel has been studied numerically for the case of coulomb interactions in cylindrical geometry. This was done by following the particle trajectories initiated at various radii and in different directions through the plasma and its imposed field until they had either left the plasma or deposited

D. P. Smitherman; R. C. Kirkpatrick

1991-01-01

74

Particle Physics Aspects of Antihydrogen Studies with ALPHA at CERN  

E-print Network

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

Fajans, Joel

75

CANDIDATES OF H{alpha} EMITTING REGIONS IN THE MAGELLANIC STREAM IV CLOUD  

SciTech Connect

From H{alpha} narrowband observations, we identified three H{alpha} emitting regions in the direction of Magellanic Stream IV (MS IV). They consist of three parallel filaments of 2 arcmin width and 6-30 arcmin length at 12 arcmin intervals. Their mean surface brightness (SB) is {approx}2 Multiplication-Sign 10{sup -18} erg s{sup -1} cm{sup -2} arcsec{sup -2}. Because of their low SB, the regions were not detected in previous H{alpha} surveys. In the H I map, the position of the filaments overlap MS, suggesting that they are parts of the MS, but there also exists a local H I structure. If the filaments are associated with the MS, the sizes are 30 pc Multiplication-Sign 100-500 pc. The filaments lie at the leading edge of a downstream cloud, which supports shock heating and its propagation (shock cascade) model for the ionizing source. If they are local objects, on the other hand, Fossil Stroemgren Trails of more than two stars is a possible interpretation, and the sizes would be 0.1 pc Multiplication-Sign 0.3-1.5 pc at 180 pc distance. The positional information of the H{alpha} filaments presented in this Letter enables future spectroscopic observations to clarify their nature.

Yagi, Masafumi; Komiyama, Yutaka [Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Yoshida, Michitoshi, E-mail: YAGI.Masafumi@nao.ac.jp [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)

2012-04-10

76

DUST EXTINCTION AND METALLICITIES OF STAR-FORMING Ly{alpha} EMITTING GALAXIES AT LOW REDSHIFT  

SciTech Connect

We present the results of an optical spectroscopic study of 12 GALEX-discovered star-forming Ly{alpha} emitting galaxies (LAEs) at z {approx} 0.3. We measure the emission-line fluxes from these galaxies by fitting their observed spectra to stellar population models in order to correct for underlying stellar absorption. We revisit earlier stellar population model fitting results, finding that excluding now-known active galactic nuclei lowers the typical stellar population age and stellar mass of this sample to {approx}300 Myr and {approx}4 x 10{sup 9} M{sub sun}, respectively. We calculate their dust extinction using the Balmer decrement, and find a typical visual attenuation of A{sub V} {approx} 0.3 mag, similar to that seen in some high-redshift LAEs. Comparing the ratios of Ly{alpha}/H{alpha} and the Ly{alpha} equivalent widths to the measured dust extinction, we find that the interstellar media (ISMs) in these objects appear to be neither enhancing nor seriously attenuating the Ly{alpha} equivalent widths, as would be the case in a quasi-clumpy ISM. Lastly, we perform a detailed analysis of the gas-phase metallicities of these galaxies, and we find that most galaxies in our sample have Z {approx}< 0.4 Z{sub sun}. We find that at a fixed stellar mass, these low-redshift LAE analogs are offset by {approx}0.3-0.6 dex lower metallicity from the general galaxy population at similar redshifts based on the local mass-metallicity relationship. This implies that galaxies with Ly{alpha} in emission may be systematically more metal-poor than star-forming galaxies at the same stellar mass and redshift, similar to preliminary results at z {approx} 2.

Finkelstein, Steven L.; Papovich, Casey [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Cohen, Seth H.; Malhotra, Sangeeta; Rhoads, James E. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Moustakas, John, E-mail: stevenf@physics.tamu.edu [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States)

2011-06-01

77

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

78

Development of alpha-emitting radionuclide lead 212 for the potential treatment of ovarian carcinoma  

SciTech Connect

alpha-Emitting radionuclides may be an effective alternative treatment against ovarian carcinoma because they have short half-lives and are densely ionizing, with high linear energy transfer to a depth of several cell diameters without requiring cellular oxygenation. One radionuclide that has been generated and tested in our laboratory in vitro and in vivo is lead 212 (/sup 212/Pb). Intraperitoneal instillation of /sup 212/Pb prolonged survival and totally eradicated tumor in 24% of mice inoculated with the extremely virulent Ehrlich ascites-producing tumor. In vitro /sup 212/Pb was two to four times more effective in killing human ovarian cancer cells than x-rays. Irradiation with /sup 212/Pb increased the radiosensitivity and chromosomal aberrations of cells. In dogs, intraperitoneal instillation of 2.6 mCi of ferrous hydroxide tagged with /sup 212/Pb caused no significant toxicity. It appears that alpha-emitting radionucides such as /sup 212/Pb have the potential to be a new and potent treatment of ovarian carcinoma and could be effective in cases that are resistant to conventional chemotherapy or x-ray therapy.

Rotmensch, J.; Atcher, R.W.; Hines, J.; Grdina, D.; Schwartz, J.S.; Toohill, M.; Herbst, A.L.

1989-04-01

79

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

80

Screening of alpha- and Beta-emitting radionuclides using liquid scintillation counting and monitoring procedures in radiation emergencies.  

PubMed

Urine gross alpha and beta activity analysis was conducted, and an internal contamination screening method was adopted to monitor visitors to Japan after the Fukushima accident. In particular, spot urine samples were used to evaluate internal contamination for 16 mo, and a total of 90 people participated in gross alpha and beta emitter screening. An ultra-low-background liquid scintillation counter was used for measurement, and optimal pulse shape analysis values were determined by measuring alpha- and beta-emitting certified reference materials. Moreover, linearity and reproducibility were assessed to validate the adopted methods, and international intercomparison was conducted using synthetic urine samples by measuring alpha- and beta-emitting radionuclides in multi-contaminated samples. Here, the measurement results of visitors to Japan are discussed, and a screening procedure is established for gross alpha and beta activity analysis during radiation emergencies. PMID:25271927

Yoon, Seokwon; Ha, Wi-Ho; Yoo, Jaeryong; Lee, Seung-Sook

2014-11-01

81

Discrimination of nuclear recoils from alpha particles with superheated liquids  

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

82

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

83

Performance comparison of scintillators for alpha particle detectors  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

84

TWO LENSED LYMAN-{alpha} EMITTING GALAXIES AT z{approx} 5  

SciTech Connect

We present observations of two strongly lensed z {approx} 5 Lyman-{alpha} emitting galaxies that were discovered in the Sloan Giant Arcs Survey (SGAS). We identify the two sources as SGAS J091541+382655 at z = 5.200 and SGAS J134331+415455 at z = 4.994. We measure their AB magnitudes at (i, z) = (23.34 {+-} 0.09, 23.29 {+-} 0.13) mag and (i, z) = (23.78 {+-} 0.18, 24.24{sup +0.18}{sub -0.16}) mag and the rest-frame equivalent widths of the Lyman-{alpha} emission at 25.3 {+-} 4.1 A and 135.6 {+-} 20.3 A for SGAS J091541+382655 and SGAS J134331+415455, respectively. Each source is strongly lensed by a massive galaxy cluster in the foreground, and the magnifications due to gravitational lensing are recovered from strong lens modeling of the foreground lensing potentials. We use the magnification to calculate the intrinsic, unlensed Lyman-{alpha} and UV continuum luminosities for both sources, as well as the implied star formation rates. We find SGAS J091541+382655 and SGAS J134341+415455 to be galaxies with (L{sub Ly-{alpha}}, L{sub UV}) {<=} (0.6 L*{sub Ly-{alpha}}, 2 L*{sub UV}) and (L{sub Ly-{alpha}}, L {sub UV}) = (0.5 L*{sub Ly-{alpha}}, 0.9 L*{sub UV}), respectively. Comparison of the spectral energy distributions of both sources against stellar population models produces estimates of the mass in young stars in each galaxy; we report an upper limit of M {sub stars} {<=} 7.9{sup +3.7} {sub -2.5} x 10{sup 7} M{sub sun} h {sup -1}{sub 0.7} for SGAS J091531+382655 and a range of viable masses for SGAS J134331+415455 of 2 x 10{sup 8} M{sub sun} h {sup -1}{sub 0.7}< M{sub stars} < 6 x 10{sup 9} M{sub sun} h {sup -1}{sub 0.7}.

Bayliss, Matthew B.; Wuyts, Eva; Gladders, Michael D.; Koester, Benjamin P. [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Sharon, Keren [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Hennawi, Joseph F. [Max-Planck-Institut fuer Astronomie Koenigstuhl 17, D-69117, Heidelberg (Germany); Dahle, Haakon, E-mail: mbayliss@oddjob.uchicago.ed [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo (Norway)

2010-09-10

85

Production of ?-particle emitting At using 45 MeV ?-beam.  

PubMed

Among the ?-particle emitting radionuclides, (211)At is considered to be a promising radionuclide for targeted cancer therapy due to its decay properties. The range of alpha particles produced by the decay of (211)At are less than 70 m in water with a linear energy transfer between 100 and 130 keV m(-1), which are about the maximum relative biological effectiveness for heavy ions. It is important to note that at the present time, only a few of cyclotrons routinely produce (211)At. The direct production method is based on the nuclear reactions (209)Bi(?,2n)(211)At. Production of the radionuclide (211)At was carried out using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). To ensure high beam current, the ?-beam was extracted with an initial energy of 45 MeV, which was degraded to obtain the appropriate ?-beam energy. The calculations of beam energy degradation were performed utilizing the MCNPX. Alumina-baked targets were prepared by heating the bismuth metal powder onto a circular cavity in a furnace. When using an E(?, av) of 29.17 MeV, the very small contribution of (210)At confirms the right choice of the irradiation energy to obtain a pure production of (211)At isotope. PMID:24819557

Kim, Gyehong; Chun, Kwonsoo; Park, Sung Ho; Kim, Byungil

2014-06-01

86

Production of ?-particle emitting 211At using 45 MeV ?-beam  

NASA Astrophysics Data System (ADS)

Among the ?-particle emitting radionuclides, 211At is considered to be a promising radionuclide for targeted cancer therapy due to its decay properties. The range of alpha particles produced by the decay of 211At are less than 70 m in water with a linear energy transfer between 100 and 130 keV m-1, which are about the maximum relative biological effectiveness for heavy ions. It is important to note that at the present time, only a few of cyclotrons routinely produce 211At. The direct production method is based on the nuclear reactions 209Bi(?,2n)211At. Production of the radionuclide 211At was carried out using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). To ensure high beam current, the ?-beam was extracted with an initial energy of 45 MeV, which was degraded to obtain the appropriate ?-beam energy. The calculations of beam energy degradation were performed utilizing the MCNPX. Alumina-baked targets were prepared by heating the bismuth metal powder onto a circular cavity in a furnace. When using an E?, av of 29.17 MeV, the very small contribution of 210At confirms the right choice of the irradiation energy to obtain a pure production of 211At isotope.

Kim, Gyehong; Chun, Kwonsoo; Park, Sung Ho; Kim, Byungil

2014-06-01

87

Note: Scanned multi-light-emitting-diode illumination for volumetric particle image velocimetry  

E-print Network

Note: Scanned multi-light-emitting-diode illumination for volumetric particle image velocimetry M-based three-dimensional illumination systems for volumetric particle image velocimetry PIV that uses a single in science and engineering. Hence, particle image velocimetry PIV has been used extensively to investigate

Wettlaufer, John S.

88

Investigation of magnetic nanoparticles for the rapid extraction and assay of alpha-emitting radionuclides from urine: demonstration of a novel radiobioassay method.  

PubMed

In the event of an accidental or intentional release of radionuclides into a populated area, massive numbers of people may require radiobioassay screening as triage for dose-reduction therapy or identification for longer-term follow-up. If the event released significant levels of beta- or alpha-emitting radionuclides, in vivo assays would be ineffective. Therefore, highly efficient and rapid analytical methods for radionuclide detection from submitted spot urine samples (?50 mL) would be required. At present, the quantitative determination of alpha-emitting radionuclides from urine samples is highly labor intensive and requires significant time to prepare and analyze samples. Sorbent materials that provide effective collection and enable rapid assay could significantly streamline the radioanalytical process. The authors have demonstrated the use of magnetic nanoparticles as a novel method of extracting media for four alpha-emitting radionuclides of concern (polonium, radium, uranium and americium) from chemically-unmodified and pH-2 human urine. Herein, the initial experimental sorption results are presented along with a novel method that uses magnetic nanoparticles to extract radionuclides from unmodified human urine and then collect the magnetic field-induced particles for subsequent alpha-counting-source preparation. Additionally, a versatile human dose model is constructed that determines the detector count times required to estimate dose at specific protective-action thresholds. The model provides a means to assess a method's detection capabilities and uses fundamental health physics parameters and actual experimental data as core variables. The modeling shows that, with effective sorbent materials, rapid screening for alpha-emitters is possible with a 50-mL urine sample collected within 1 wk of exposure/intake. PMID:21709509

O'Hara, Matthew J; Carter, Jennifer C; MacLellan, Jay A; Warner, Cynthia L; Warner, Marvin G; Addleman, R Shane

2011-08-01

89

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

90

Making A D-Latch Sensitive To Alpha Particles  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

91

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

E-print Network

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

92

Michrochannel plate for position sensitive alpha particle detection  

SciTech Connect

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

Paul Hurley and James Tinsley

2007-08-31

93

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

SciTech Connect

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

Caryl Gronwall

2012-12-03

94

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

95

An atlas of H-alpha-emitting regions in M33: A systematic search for SS433 star candidates  

NASA Technical Reports Server (NTRS)

We report finding charts and accurate positions for 432 compact H-alpha emitting regions in the Local Group galaxy M 33 (NGC 598), in an effort to isolate candidates for an SS433-like stellar system. The objects were extracted from narrow band images, centered in the rest-frame H-alpha (lambda 6563 A) and in the red continuum at 6100 A. The atlas is complete down to V approximately equal to 20 and includes 279 compact HII regions and 153 line emitting point-like sources. The point-like sources undoubtedly include a variety of objects: very small HII regions, early type stars with intense stellar winds, and Wolf-Rayet stars, but should also contain objects with the characteristics of SS433. This extensive survey of compact H-alpha regions in M 33 is a first step towards the identification of peculiar stellar systems like SS433 in external galaxies.

Calzetti, Daniela; Kinney, Anne L.; Ford, Holland; Doggett, Jesse; Long, Knox S.

1995-01-01

96

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

National Technical Information Service (NTIS)

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

M. Yamagiwa, T. Takizuka

1988-01-01

97

Characterization of particles emitted by domestic heating units fueled by distilled oil  

NASA Astrophysics Data System (ADS)

Aerosol samples were collected from point sources of different capacity fueled by distilled oil, with the aim of determining the amount and composition of particles emitted by domestic units. A physical and chemical characterization of the particles emitted from each source was performed. Mass median aerodynamic diameter and size distributions were determined. Individual particle analyses to examine morphology and elemental composition were performed by scanning electron microscopy with an energy dispersive X-ray analyser. The results evidence the specific differences existing in the aerosol emissions of the sources studied in comparison with other combustion sources.

Sabbioni, C.; Zappia, G.

98

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

99

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

100

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

101

The Physical Nature of Lyman Alpha Emitting Galaxies at z=3.1  

E-print Network

We selected 40 candidate Lyman Alpha Emitting galaxies (LAEs) at z ~=3.1 with observed frame equivalent widths >150A and inferred emission line fluxes >2.5x10^-17 ergs/cm^2/s from deep narrow-band and broad-band MUSYC images of the Extended Chandra Deep Field South. Covering 992 sq. arcmin, this is the largest ``blank field'' surveyed for LAEs at z ~3, allowing an improved estimate of the space density of this population of 3+-1x10^-4 h_70^3/Mpc^3. Spectroscopic follow-up of 23 candidates yielded 18 redshifts, all at z ~=3.1. Over 80% of the LAEs are dimmer in continuum magnitude than the typical Lyman break galaxy spectroscopic limit of R= 25.5 (AB), with a median continuum magnitude R ~=27 and very blue continuum colors, (V-z) ~=0. Over 80% of the LAEs have the right UVR colors to be selected as Lyman break galaxies, but only 10% also have R240A which might imply a non-standard IMF. One candidate is detected by Chandra, implying an AGN fraction of 2+-2% for LAE candidate samples. In summary, LAEs at z ~ 3 have rapid star formation, low stellar mass, little dust obscuration and no evidence for a substantial AGN component.

Eric Gawiser; Pieter G. van Dokkum; Caryl Gronwall; Robin Ciardullo; Guillermo A. Blanc; Francisco J. Castander; John Feldmeier; Harold Francke; Marijn Franx; Lutz Haberzettl; David Herrera; Thomas Hickey; Leopoldo Infante; Paulina Lira; Jose Maza; Ryan Quadri; Alexander Richardson; Kevin Schawinski; Mischa Schirmer; Edward N. Taylor; Ezequiel Treister; C. Megan Urry; Shanil N. Virani; for the MUSYC Collaboration

2006-03-09

102

Galactic winds and stellar populations in Lyman $\\alpha$ emitting galaxies at z ~ 3.1  

E-print Network

We present a sample of 33 spectroscopically confirmed z ~ 3.1 Ly$\\alpha$-emitting galaxies (LAEs) in the Cosmological Evolution Survey (COSMOS) field. This paper details the narrow-band survey we conducted to detect the LAE sample, the optical spectroscopy we performed to confirm the nature of these LAEs, and a new near-infrared spectroscopic detection of the [O III] 5007 \\AA\\ line in one of these LAEs. This detection is in addition to two [O III] detections in two z ~ 3.1 LAEs we have reported on previously (McLinden et al 2011). The bulk of the paper then presents detailed constraints on the physical characteristics of the entire LAE sample from spectral energy distribution (SED) fitting. These characteristics include mass, age, star-formation history, dust content, and metallicity. We also detail an approach to account for nebular emission lines in the SED fitting process - wherein our models predict the strength of the [O III] line in an LAE spectrum. We are able to study the success of this prediction be...

McLinden, Emily M; Malhotra, Sangeeta; Finkelstein, Steven L; Richardson, Mark L A; Smith, Brent; Tilvi, Vithal S

2014-01-01

103

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

104

ELEMENTAL COMPOSITION OF SIZED PARTICLES EMITTED FROM STATIONARY SOURCES  

EPA Science Inventory

This paper discusses several approaches for obtaining the elemental and, in a few cases, inorganic compound identification in sized particles. The elemental analyses are done by wavelength dispersion x-ray fluorescence (WXRF). Fourier Transform infrared is being used for inorgani...

105

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

E-print Network

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

Hudson, Hugh; MacKinnon, Alec; Woods, Tom

2014-01-01

106

Characterization of particles emitted by domestic heating units fueled by distilled oil  

NASA Astrophysics Data System (ADS)

Aerosol samples were collected from point sources of different capacity fueled by distilled oil, with the aim of determining the amount and composition of particles emitted by domestic units. A physical and chemical characterization of the particles emitted from each source was performed. Mass median aerodynamic diameter and size distributions were determined. Individual analyses to examine morphology and elemental composition were performed by scanning electron microscopy with an energy dispersive X-ray analyser. The results evidence the specific differences existing in the aerosol emissions of the sources studied in comparison with other combustion sources.

Sabbioni, C.; Zappia, G.

107

The {alpha} particle as a canonically quantized multiskyrmion  

SciTech Connect

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

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

2006-08-15

108

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

PubMed

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

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

2006-02-01

109

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

Microsoft Academic Search

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

D. Desmarais; J. L. Duggan

1984-01-01

110

Collective transport of alpha particles due to Alfven wave instability  

SciTech Connect

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

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

1993-02-01

111

Collective transport of alpha particles due to Alfven wave instability  

SciTech Connect

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

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

1993-02-01

112

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

113

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

PubMed

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

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

2012-04-01

114

Preliminary results from the lunar prospector alpha particle spectrometer  

SciTech Connect

The Lunar Prospector Alpha Particle Spectrometer (LP APS) builds on Apollo heritage and maps the distribution of outgassing sites on the Moon. The APS searches for lunar surface gas release events and maps their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life) and solid polonium-210 (5.3 MeV, 138 day half-life, but remains on the surface with a 21 year half-life as lead-210), which are radioactive daughters from the decay of uranium-238. Radon is in such small quantities that it is not released directly from the lunar interior, rather it is entrained in a stream of gases and serves as a tracer for such gases. Once released, the radon spreads out by 'bouncing' across the surface on ballistic trajectories in a random-walk process. The 3.8 day half-life of radon-222 allows the gas to spread out by several 100 km before it decays and allows the APS to detect gas release events up to a few days after they occur. The long residence time (10s of years) of the lead-210 precursor to the polonium-210 allows the mapping of gas vents which have been active over the last approximately 50 years. Because radon and polonium are daughter products of the decay of uranium, the background level of alpha particle activity is a function of the lunar crustal uranium distribution. Using radioactive radon and polonium as tracers, the Apollo 15 and 16 Command Module orbital alpha particle experiments obtained evidence for the release of gases at several sites beneath the orbit tracks, especially over the Aristarchus Plateau and Mare Fecunditatis [1]. Aristarchus crater had previously been identified by ground-based observers as the site of transient optical events [2]. The Apollo 17 surface mass spectrometer showed that argon-40 is released from the lunar interior every few months, apparently in concert with some of the shallow moonquakes that are believed to be of tectonic origin [3]. The latter tectonic events could be associated with very young scarps identified in the lunar highlands [4] and are believed to indicate continued global contraction. Such quakes could open fissures leading to the release of gases that are trapped below the surface. The detection of radon-222 outgassing events at the margins of Fecunditatis basin was surprising because the observed surface distribution of uranium and thorium do not extend sufficiently eastward to cover Fecunditatis. If the Apollo detections prove sound, then those alpha particle emissions indicate substantial subsurface concentrations of uranium-238 within Fecunditatis. A primary goal of the APS was to map gas-release events, thus allowing both an appraisal of the current level of tectonic activity on the Moon and providing a probe of subsurface uranium concentrations.

Lawson, S. L. (Stefanie L.)

2001-01-01

115

Particle size distribution of airborne Aspergillus fumigatus spores emitted from compost using membrane filtration  

NASA Astrophysics Data System (ADS)

Information on the particle size distribution of bioaerosols emitted from open air composting operations is valuable in evaluating potential health impacts and is a requirement for improved dispersion simulation modelling. The membrane filter method was used to study the particle size distribution of Aspergillus fumigatus spores in air 50 m downwind of a green waste compost screening operation at a commercial facility. The highest concentrations (approximately 8 10 4 CFU m -3) of culturable spores were found on filters with pore diameters in the range 1-2 ?m which suggests that the majority of spores are emitted as single cells. The findings were compared to published data collected using an Andersen sampler. Results were significantly correlated ( p < 0.01) indicating that the two methods are directly comparable across all particles sizes for Aspergillus spores.

Deacon, L. J.; Pankhurst, L. J.; Drew, G. H.; Hayes, E. T.; Jackson, S.; Longhurst, P. J.; Longhurst, J. W. S.; Liu, J.; Pollard, S. J. T.; Tyrrel, S. F.

116

Ly Alpha-Emitting Galaxies at z=3.1: L* Progenitors Experiencing Rapid Star Formation  

E-print Network

We studied the clustering properties and multiwavelength spectral energy distributions of a complete sample of 162 Ly Alpha-Emitting (LAE) galaxies at z=3.1 discovered in deep narrow-band MUSYC imaging of the Extended Chandra Deep Field South. LAEs were selected to have observed frame equivalent widths >80A and emission line fluxes >1.5E-17 erg/cm^2/s. Only 1% of our LAE sample appears to host AGN. The LAEs exhibit a moderate spatial correlation length of r_0=3.6+0.8-1.0 Mpc, corresponding to a bias factor b=1.7+0.3-0.4, which implies median dark matter halo masses of log10(M_med) = 10.9+0.5-0.9 M_sun. Comparing the number density of LAEs, (1.5+-0.3)E-3/Mpc^3, with the number density of these halos finds a mean halo occupation ~1-10%. The evolution of galaxy bias with redshift implies that most z=3.1 LAEs evolve into present-day galaxies with L3 galaxy populations typically evolve into more massive galaxies. Halo merger trees show that z=0 descendants occupy halos with a wide range of masses, with a median descendant mass close to that of L*. Only 30% of LAEs have sufficient stellar mass (>~3E9 M_sun) to yield detections in deep Spitzer-IRAC imaging. A two-population SED fit to the stacked UBVRIzJK+[3.6,4.5,5.6,8.0]micron fluxes of the IRAC-undetected objects finds that the typical LAE has low stellar mass (1.0+0.6-0.4 E9 M_sun), moderate star formation rate (2+-1 M_sun/yr), a young component age of 20+30-10 Myr, and little dust (A_V<0.2). The best fit model has 20% of the mass in the young stellar component, but models without evolved stars are also allowed.

Eric Gawiser; Harold Francke; Kamson Lai; Kevin Schawinski; Caryl Gronwall; Robin Ciardullo; Ryan Quadri; Alvaro Orsi; L. Felipe Barrientos; Guillermo A. Blanc; Giovanni Fazio; John J. Feldmeier; Jia-Sheng Huang; Leopoldo Infante; Paulina Lira; Nelson Padilla; Edward N. Taylor; Ezequiel Treister; C. Megan Urry; Pieter G. van Dokkum; Shanil N. Virani; for the MUSYC Collaboration

2007-10-14

117

Photodiode radiation hardness, lyman-alpha emitting galaxies and photon detection in liquid argon neutrino detectors  

NASA Astrophysics Data System (ADS)

My dissertation is comprised of three projects: 1) studies of Lyman-alpha Emitting galaxies (LAEs), 2) radiation hardness studies of InGaAs photodiodes (PDs), and 3) scintillation photon detection in liquid argon (LAr) neutrino detectors. I began work on the project that has now become WFIRST, developing a science case that would use WFIRST after launch for the observation of LAEs. The radiation hardness of PDs was as an effort to support the WFIRST calibration team. When WFIRST was significantly delayed, I joined an R&D effort that applied my skills to work on photon detection in LAr neutrino detectors. I report results on a broadband selection method developed to detect high equivalent width (EW) LAEs. Using photometry from the CFHT-Legacy Survey Deep 2 and 3 fields, I have spectroscopically confirmed 63 z=2.5-3.5 LAEs using the WIYN/Hydra spectrograph. Using UV continuum-fitting techniques I computed properties such as EWs, internal reddening and star formation rates. 62 of my LAEs show evidence to be normal dust-free LAEs. Second, I present an investigation into the effects of ionizing proton radiation on commercial off-the-shelf InGaAs PDs. I developed a monochromator-based test apparatus that utilized NIST-calibrated reference PDs. I tested the PDs for changes to their dark current, relative responsivity as a function of wavelength, and absolute responsivity. I irradiated the test PDs using 30, 52, and 98 MeV protons at the IU Cyclotron Facility. I found the InGaAs PDs showed increased dark current as the fluence increased with no evidence of broadband response degradation at the fluences expected at an L2 orbit and a 10-year mission lifetime. Finally, I detail my efforts on technology development of both optical detector technologies and waveshifting light guide construction for LAr vacuum UV scintillation light. Cryogenic neutrino detectors use photon detection for both accelerator based science and for SNe neutrino detection and proton decay. I have developed waveshifter doped cast acrylic light guides that convert scintillation light and guide the waveshifted light to SiPMs detectors.

Baptista, Brian

118

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

E-print Network

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

Richardson, John

119

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

120

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

Microsoft Academic Search

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

D. Sigmar; R. Gormley; G. Kamelander

1993-01-01

121

Enhanced production of low energy electrons by alpha particle impact  

PubMed Central

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

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

2011-01-01

122

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

NASA Astrophysics Data System (ADS)

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

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

1995-02-01

123

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

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

124

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

E-print Network

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

125

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

126

Microdosimetry of radon progeny alpha particles in bronchial airway bifurcations.  

PubMed

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

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

2005-01-01

127

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

SciTech Connect

An escaping alpha collector probe has been developed for TFTR`s DT phase. Energy distributions of escaping alphas have been determined by measuring the range of {alpha}-particles implanted into nickel foils located within the alpha collector. Results at 1.0 MA of plasma current are in good agreement with predictions for first orbit alpha loss. Results at 1.8 MA, however, show a significant anomalous loss of partially thermalized alphas (in addition to the expected first orbit loss), which is not observed with the lost alpha scintillator detectors in DT plasmas, but does resemble the anomalous delayed loss seen in DD plasmas. None of the candidate explanations proposed thus far are fully consistent with the anomalous loss observations. An experiment designed to study the effect of plasma major radius shifts on {alpha}-particle loss has led to a better understanding of {alpha}-particle dynamics in tokamaks. Intuitively, one might suppose that confined marginally passing {alpha}-particles forced to move toward higher magnetic field during an inward major radius shift (i.e., compression) would mirror and become trapped particles, leading to increased alpha loss. Such an effect was looked for during the shift experiment, however, no significant changes in alpha loss to the 90{degree} lost alpha scintillator detector were observed during the shifts. It is calculated that the energy gained by an {alpha}-particle during the inward shift is sufficient to explain this result. However, an unexpected loss of partially thermalized {alpha}-particles near the passing/trapped boundary was observed to occur between inward and outward shifts at an intermediate value of plasma current (1.4 MA). This anomalous loss feature is not yet understood.

Herrmann, H.W.

1997-09-01

128

Measurement of Ultrafine Particles and Other Air Pollutants Emitted by Cooking Activities  

PubMed Central

Cooking emissions show a strong dependence on cooking styles and parameters. Measurements of the average ultrafine particle (UFP) concentration, PM2.5 and black carbon concentrations emitted by cooking activities ranged from 1.34 104 to 6.04 105 particles/cm3, 10.0 to 230.9 ?g/m3 and 0.1 to 0.8 ?g/m3, respectively. Lower UFP concentrations were observed during boiling, while higher levels were emitted during frying. The highest UFP concentrations were observed when using a gas stove at high temperature with the kitchen exhaust fan turned off. The observed UFP profiles were similar in the kitchen and in another room, with a lag of approximately 10 min. PMID:20617057

Zhang, Qunfang; Gangupomu, Roja H.; Ramirez, David; Zhu, Yifang

2010-01-01

129

Coordination chemistry of the {sup 212}Pb/{sup 212}Bi nuclear transformation: Alpha-emitting radiopharmaceuticals. Final technical report  

SciTech Connect

Subdivisions of this project are: (a) the synthesis of prototypical thiolate and dithiocarbamate based hexacoordinate complexes, (b) radiochemical engineering for generation of no-carrier-added lead and bismuth radioelements, (c) the first isolation of bismuth-binding proteins from in vivo studies with cyclotron produced {sup 205/206}Bi tracer, and (d) initial development of transport mechanisms for the intracellular radiobiological study of alpha emitting bismuth, and (e) the initiation of chemical equilibrium studies and biochemical pathways with cyclotron-produced, no-carrier-added, {sup 203}Pb (T{sub 1/2} = 51 hr).

Parks, N.J.; Harris, W.R.; Keen, C.L.; Cooper, S.R.

1992-07-01

130

Synthesis of red-emitting, small particle size luminescent oxides using an optimized combustion process  

Microsoft Academic Search

A novel ceramic synthesis technique, combustion synthesis, was explored to produce red-emitting Cr{sup 3+}-doped YAlO and Eu{sup 3+}-doped YO phosphors with improved physical and luminescent properties. This technique involves the reaction of metal nitrates (oxidizers) and an organic fuel (urea, carbohydrazide, glycine) at 500 C. Resulting powders are well-crystallized, with a large surface area and small particle size. The spectral

Lauren E. Shea; Joanna McKittrick; Olivia A. Lopez; Esther Sluzky

1996-01-01

131

Ly{alpha} EMITTING GALAXIES AS EARLY STAGES IN GALAXY FORMATION  

SciTech Connect

We present optical spectroscopy of two samples of Galaxy Evolution Explorer grism selected Ly{alpha} emitters (LAEs): one at z = 0.195-0.44 and the other at z = 0.65-1.25. We have also observed a comparison sample of galaxies in the same redshift intervals with the same UV magnitude distributions but with no detected Ly{alpha}. We use the optical spectroscopy to eliminate active galactic nuclei and to obtain the optical emission-line properties of the samples. We compare the luminosities of the LAEs in the two redshift intervals and show that there is dramatic evolution in the maximum Ly{alpha} luminosity over z = 0-1. Focusing on the z = 0.195-0.44 samples alone, we show that there are tightly defined relations between all of the galaxy parameters and the rest-frame equivalent width (EW) of H{alpha}. The higher EW(H{alpha}) sources all have lower metallicities, bluer colors, smaller sizes, and less extinction, consistent with their being in the early stages of the galaxy formation process. We find that 75% {+-} 12% of the LAEs have EW(H{alpha}) >100 A and, conversely, that 31% {+-} 13% of galaxies with EW(H{alpha}) >100 A are LAEs. We correct the broadband magnitudes for the emission-line contributions and use spectral synthesis fits to estimate the ages of the galaxies. We find a median age of 1.1 x 10{sup 8} yr for the LAE sample and 1.4 x 10{sup 9} yr for the UV-continuum sample without detected Ly{alpha}. The median metallicity of the LAE sample is 12 + log (O/H) = 8.24, or about 0.4 dex lower than the UV-continuum sample.

Cowie, Lennox L.; Barger, Amy J.; Hu, Esther M. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2011-09-10

132

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

E-print Network

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

133

Technical NoteFEASIBILITY STUDIES OF ALPHA-PARTICLE CHANNELING IN MIRROR MACHINES  

E-print Network

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

134

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

SciTech Connect

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

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

2010-09-15

135

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

Microsoft Academic Search

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

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

1992-01-01

136

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

137

Characterizing gas-particle interactions of phthalate plasticizer emitted from vinyl flooring.  

PubMed

Phthalates are widely used as plasticizers, and improved ability to predict emissions of phthalates is of interest because of concern about their health effects. An experimental chamber was used to measure emissions of di-2-ethylhexyl-phthalate (DEHP) from vinyl flooring, with ammonium sulfate particles introduced to examine their influence on the emission rate and to measure the partitioning of DEHP onto airborne particles. When particles were introduced to the chamber at concentrations of 100 to 245 ?g/m(3), the total (gas + particle) DEHP concentrations increased by a factor of 3 to 8; under these conditions, emissions were significantly enhanced compared to the condition without particles. The measured DEHP partition coefficient to ammonium sulfate particles with a median diameter of 45 5 nm was 0.032 0.003 m(3)/?g (95% confidence interval). The DEHP-particle sorption equilibration time was demonstrated to be less than 1 min. Both the partition coefficient and equilibration time agree well with predictions from the literature. This study represents the first known measurements of the particle-gas partition coefficient for DEHP. Furthermore, the results demonstrate that the emission rate of DEHP is substantially enhanced in the presence of particles. The particles rapidly sorb DEHP from the gas phase, allowing more to be emitted from the source, and also appear to enhance the convective mass-transfer coefficient itself. Airborne particles can influence SVOC fate and transport in the indoor environment, and these mechanisms must be considered in evaluating exposure and human health. PMID:23410053

Benning, Jennifer L; Liu, Zhe; Tiwari, Andrea; Little, John C; Marr, Linsey C

2013-03-19

138

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

E-print Network

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

139

Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere  

NASA Astrophysics Data System (ADS)

During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), a plume of organic aerosol was produced by a smoke generator and emitted into the marine atmosphere from aboard the R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, the plume particles had very low hygroscopic growth factors (GFs): between 1.05 and 1.09 for 30 nm and between 1.02 and 1.1 for 150 nm dry size at a relative humidity (RH) of 92%, contrasted by an average marine background GF of 1.6. New particles were produced in large quantities (several 10 000 cm-3), which lead to substantially increased cloud condensation nuclei (CCN) concentrations at supersaturations between 0.07 and 0.88%. Ratios of oxygen to carbon (O : C) and water-soluble organic mass (WSOM) increased with plume age: from < 0.001 to 0.2, and from 2.42 to 4.96 ?g m-3, respectively, while organic mass fractions decreased slightly (~ 0.97 to ~ 0.94). High-resolution aerosol mass spectrometer (AMS) spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small, new particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions: an average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, and a GF of 1.04 for an organic mass fraction of 0.35.

Wonaschtz, A.; Coggon, M.; Sorooshian, A.; Modini, R.; Frossard, A. A.; Ahlm, L.; Mlmenstdt, J.; Roberts, G. C.; Russell, L. M.; Dey, S.; Brechtel, F. J.; Seinfeld, J. H.

2013-10-01

140

Alpha-particle effects on high-n instabilities in tokamaks  

SciTech Connect

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

Rewoldt, G.

1988-06-01

141

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

142

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

143

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

NASA Technical Reports Server (NTRS)

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

Burgess, D.

1989-01-01

144

On the approximations of the distribution function of fusion alpha particles  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

145

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

146

Hygroscopic properties of organic aerosol particles emitted in the marine atmosphere  

NASA Astrophysics Data System (ADS)

During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), a plume of organic aerosol was produced and emitted into the marine atmosphere from aboard the research vessel R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, hygroscopic growth factors (GFs) at a relative humidity (RH) of 92% were low, but increased at higher plume ages: from 1.05 to 1.09 for 30 nm and from 1.05 to 1.1 for 150 nm dry size (contrasted by an average marine background GF of 1.6). Simultaneously, ratios of oxygen to carbon (O:C) increased from < 0.001 to 0.2, water-soluble organic mass (WSOM) concentrations increased from 2.42 to 4.96 ?g m-3, and organic mass fractions decreased slightly (~ 0.97 to ~ 0.94). New particles were produced in large quantities (several 10 000 cm-3), which lead to substantially increased cloud condensation nuclei (CCN) concentrations at supersaturations between 0.07-0.88%. High-resolution aerosol mass spectrometer (AMS) spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions. An average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, a GF of 1.04 for an organic mass fraction of 0.35.

Wonaschtz, A.; Coggon, M.; Sorooshian, A.; Modini, R.; Frossard, A. A.; Ahlm, L.; Mlmenstdt, J.; Roberts, G. C.; Russell, L. M.; Dey, S.; Brechtel, F. J.; Seinfeld, J. H.

2013-05-01

147

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

SciTech Connect

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

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

1992-12-01

148

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

SciTech Connect

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

Desmarais, D.; Duggan, J.L.

1984-06-01

149

FORMATION OF METAL-POOR GLOBULAR CLUSTERS IN Ly{alpha} EMITTING GALAXIES IN THE EARLY UNIVERSE  

SciTech Connect

The size, mass, luminosity, and space density of Ly{alpha} emitting (LAE) galaxies observed at intermediate to high redshift agree with expectations for the properties of galaxies that formed metal-poor halo globular clusters (GCs). The low metallicity of these clusters is the result of their formation in low-mass galaxies. Metal-poor GCs could enter spiral galaxies along with their dwarf galaxy hosts, unlike metal-rich GCs, which form in the spirals themselves. Considering an initial GC mass larger than the current mass to account for multiple stellar populations, and considering the additional clusters that are likely to form with massive clusters, we estimate that each GC with a mass today greater than 2 Multiplication-Sign 10{sup 5} M{sub Sun} was likely to have formed among a total stellar mass {approx}> 3 Multiplication-Sign 10{sup 7} M{sub Sun }, a molecular mass {approx}> 10{sup 9} M{sub Sun }, and 10{sup 7} to 10{sup 9} M{sub Sun} of older stars, depending on the relative gas fraction. The star formation rate would have been several M{sub Sun} yr{sup -1} lasting for {approx}10{sup 7} yr, and the Ly{alpha} luminosity would have been {approx}> 10{sup 42} erg s{sup -1}. Integrating the LAE galaxy luminosity function above this minimum, considering the average escape probability for Ly{alpha} photons (25%), and then dividing by the probability that a dwarf galaxy is observed in the LAE phase (0.4%), we find agreement between the comoving space density of LAEs and the average space density of metal-poor GCs today. The local galaxy WLM, with its early starburst and old GC, could be an LAE remnant that did not get into a galaxy halo because of its remote location.

Elmegreen, Bruce G. [IBM Research Division, T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Malhotra, Sangeeta; Rhoads, James, E-mail: bge@watson.ibm.com [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)

2012-09-20

150

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

151

Rapid screening and analysis of alpha- and gamma-emitting radionuclides in liquids using a single sample preparation procedure.  

PubMed

A multifaceted radiochemical testing procedure has been developed to analyze a large number of liquid samples and measure a wide range of radionuclides in a short period of time. This method involves a single, unique and fast sample preparation procedure and allows sequential/concurrent determination of analytes with accuracy and precision. The same prepared sample can be selectively analyzed by gross alpha counting, gamma-ray spectroscopy, and alpha spectroscopy. This method is especially attractive in radiological emergency events where analytical data will be needed urgently as a basis for protective action. Given the simplicity and rapidity of the method, it may be suitable for field portable laboratories, which could save time and the cost associated with the transit of samples to a fixed laboratory. A 100 mL aliquot of sample was spiked with Ba and ??Fe tracers and subjected to a chemical separation procedure using a combined BaSO4 and Fe(OH)3 co-precipitation scheme. Then, the gross alpha-particle activity of the prepared sample was measured with a low-background gas-proportional counter, followed by the analysis of its photon-emitters using a gamma-ray spectroscopy system with high-purity intrinsic Ge detectors. Gamma-ray determination of Ba and ??Fe tracers was used to assess the chemical recoveries of BaSO4 and Fe(OH)3 fractions, respectively. Selectivity of the radionuclides for co-precipitation with either BaSO4 or Fe(OH)3 components was also investigated. Alpha mass-efficiency curves were derived using ?Th and ?Am standards as alpha-calibration sources. Various mixtures of radionuclides, including ??Mn, ??Co, ??Co, ??Sr, ??Y, ??Cd, Sn, ?Cs, ?Ce, ?Hg, ??Po, ?Ra, ?Ra, ?Th, ?Am, and natural uranium were used in this study. Most were quantitatively assayed with high chemical recoveries. Alpha-isotope identification and assessment of the prepared sample was achieved by alpha spectroscopy using passivated implanted planar silicon (PIPS) detectors. It has been shown that fission products could potentially be captured and analyzed by this method. PMID:21399430

Parsa, Bahman; Henitz, James B; Carter, Jennifer A

2011-02-01

152

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

153

Enhanced Retention of the ?-particle Emitting Daughters of Actinium-225 by Liposome Carriers  

PubMed Central

Targeted ?-particle emitters hold great promise as therapeutics for micrometastatic disease. Because of their high energy deposition and short range, tumor targeted ?-particles can result in high cancer-cell killing with minimal normal-tissue irradiation. Actinium-225 is a potential generator for ?-particle therapy: it decays with a 10-day half-life and generates three ?-particle emitting daughters. Retention of 225Ac daughters at the target increases efficacy; escape and distribution throughout the body increases toxicity. During circulation, molecular carriers conjugated to 225Ac cannot retain any of the daughters. We previously proposed liposomal encapsulation of 225Ac 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 binding of 225Ac 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 225Ac. PEGylated MUVELs stably retained over time 98% of encapsulated 225Ac. Retention of 213Bi, the last daughter, was 31% of the theoretical maximum retention of 213Bi 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 could be able to deliver higher fractions of generated ?-particles per targeted 225Ac compared to the relative fractions of ?-particles delivered by 225Ac-labeled molecular carriers. PMID:17935286

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

2008-01-01

154

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

SciTech Connect

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

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

2012-11-20

155

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

SciTech Connect

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

Wong, K.L.

1989-07-01

156

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

157

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

158

Targeting of Osseous Sites with Alpha-emitting Ra-223: Comparison with the Beta-emitter Sr-89 in Mice  

SciTech Connect

The bone-seeking property of and the potential to irradiate red marrow by the alpha-particle emitter Ra-223 (t1/2 = 11.43 d) were compared to those of the beta-emitter Sr-89 (t1/2 = 50.53 d). Methods: The biodistributions of Ra-223 and Sr-89 were studied in mice. Tissue uptakes were determined at 1 h, 6 h, 1 d, 3 d, and 14 d after intravenous administration. The potential redistribution of progeny from Ra-223 located in bone was investigated. Radiation absorbed doses were calculated for soft tissues and bone. Doses were also estimated for marrow-containing cavities assuming spheric geometries. Results: We found that both Sr-89 and Ra-223 selectively concentrated on bone surfaces relative to soft tissues. The measured bone uptake of Ra-223 was slightly higher than that of Sr-89. At the 24 h time-point, the femur uptake of Ra-223 was 40.1% of the administered activity per gram tissue. The uptake in spleen and most other soft tissues was higher for Ra-223 than for Sr-89. We observed rapid clearance of Ra-223 from soft tissues within the first 24 hours, but the bone surface uptake of Ra-223 increased with time up to 24 h. Among the soft tissues, the spleen had the greatest accumulation and retention of Ra-223. The femur-to-spleen ratio increased with time, from 6.4 at 6 h to 23.7 at 3 days after injections. We found little redistribution of Ra-223 daughter products away from bone (about 2% at 6 h and less than 1% detectable at 3 d). Estimates of dose to marrow-containing cavities showed that the Ra-223 alpha-emitter might have a marrow-sparing advantage compared to beta-emitters due to high linear-energy-transfer and short alpha range targeting osteoid surfaces. The alpha-emitters irradiate a smaller fraction of the marrow-containing volumes--sparing marrow and enhancing survival of marrow cells. At the same time, the bone surfaces receives a therapeutically effective radiation dose. Conclusion: The results of this study indicate that Ra-223 is a promising candidate for high linear-energy-transfer alpha-particle irradiation of cancer cells on bone surfaces. Radium-223 can, together with its daughter radionuclides, deliver an intense and highly localized field of radiation to bone surfaces with substantially less irradiation of healthy bone marrow dose compared to standard, bone-seeking beta-emitters such as Sr-89.

Henriksen, Gjermund; Fisher, Darrell R.; Roeske, John C.; Bruland, Oyvind S.; Larsen, Roy H.

2003-05-16

159

Chemical characterization of soot particles emitted by Wood-Burning Cook Stoves: A XPS and HRTEM study  

NASA Astrophysics Data System (ADS)

The morphology, microstructure, chemical composition, and electronic structure of soot particles emitted directly from biofuel cook stoves have been studied by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). In order to obtain freshly emitted soot particles, copper grids for Transmission Electron Microscope (TEM) were placed on the last two of an 8-stages MOUDI cascade impactor. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot chain. Additionally, the morphology of soot particles was analyzed calculating the border-based fractal dimension (Df). Particles sampled on the first heating stage exhibit complex shapes with high values of Df, which are present as aggregates formed by carbon ceno-spheres. The XPS survey spectrum for soot particles shows that the main particle composition is carbon. We also observed differences in the carbon/oxygen (C/O) ratio of the particles, which probably depends on the combustion process efficiency of each cook-stove analyzed. The XPS C-1s spectra show carbon with two peaks that correspond to sp2 and sp3 hybridization. Also, real-time absorption (?a) and scattering (?s) coefficients of the particles emitted by cook stoves were measured. The trend in ?a and ?s indicate that the cooking process has two important combustion stages which varied in its flaming strength, being vigorous in the first stage and soft in the second one.

Carabali, Giovanni; Peralta, Oscar; Castro, Telma; Torres, Ricardo; Ruiz, Gerardo; Molina, Luisa; Saavedra, Isabel

2014-05-01

160

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

161

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

162

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

Microsoft Academic Search

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

E. P. Ney; W. A. Stein

1962-01-01

163

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

SciTech Connect

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

Agarwal, S.; Chatterjee, S.N.

1984-11-01

164

Chemical Composition of Aerosol Particles Emitted by a Passenger Car Engine Fueled by Ethanol/Gasoline Mixtures  

NASA Astrophysics Data System (ADS)

With concerns of national security, climate change, and human health, many people have called for oil independence for the United States and for the creation of alternative fuels. Ethanol has been widely praised as a viable alternative to petroleum-based fuels, due to the fact that it can be produced locally. A great deal of work has been done to characterize the energy balance of ethanol production versus consumption, but there have been fewer studies of the environmental and health impacts of emissions from combustion of ethanol/gasoline mixtures such as those burned in the modern vehicle fleet. To study the particulate emissions from such fuels, different ethanol/gasoline fuel mixtures with 0, 20, 40, and 85% ethanol were burned in a dynamometer-mounted automobile engine. The engine exhaust was diluted and sampled with two aerosol Time-of-Flight Mass Spectrometers (TSI 3800 ATOFMS), sampling different particle size ranges (50-500 nm and 150-3000 nm, respectively), to measure size and composition of the emitted aerosol particles. A variety of other aerosol characterization techniques were also employed to determine the size distribution of the aerosol particles, the mass emission rate from the engine, and the concentration of polycyclic aromatic hydrocarbons (PAHs) and elemental carbon (EC) in the particle emissions. Here we will focus on results from the ATOFMS, which provides us with a particle size and mass spectra - for both negative and positive ions - for each particle that is sampled. Particles being emitted were found to contain primarily PAHs, elemental carbon (EC), nitrates, and sulfates. Particles were analyzed to investigate trends in particle composition as a function of fuel ethanol content, particle size, and for the types of particles emitted. A trend in particle type as a function of fuel ethanol content was evident in smaller particles, and trends in composition as a function of particle size were visible across the entire size range sampled.

Medrano, J. M.; Gross, D. S.; Dutcher, D. D.; Drayton, M.; Kittelson, D.; McMurry, P.

2007-12-01

165

Detection and localization of particle-emitting sources with compound-eye inspired detector arrays  

NASA Astrophysics Data System (ADS)

We develop methods to detect and localize particle-emitting sources using detector arrays that are inspired by biological compound eyes. The sources of interest may be optical, nuclear, or cosmic; they emit particles such as visible photons, neutrons, protons, or charged particles. Our results may have wide applications to artificial vision, which can be important in robotics (robot vision) or medicine (e.g., artificial eyes for the blind); security, where the detection of nuclear materials is needed; or astronomy. This dissertation consists of three parts. First, we detect a far-field particle source using two directional detector arrays: cubic and spherical. We propose a mean-difference test (MDT) detector, analyze its statistical performance, and show that the MDT has a number of advantages over the generalized likelihood- ratio test (GLRT). Second, we localize the source by proposing a novel biologically inspired detector array, whose configuration generalizes the compound eye of insects. This array combines the advantages of compound eyes (e.g., large field-of-view) and human eyes (e.g., high angular resolution). Based on a statistical model of the array measurements, we analyze the array performance by computing the Cramrao bound (CRB) on the error in estimating the source direction. We also derive lower bounds on the mean-square angular error (MSAE) of the source localization and investigate the MSAE of two source- direction estimators. Numerical examples, including the optimal array design, are presented to further illustrate the array performance. Third, we derive a statistical angular resolution limit (ARL) on resolving two closely spaced point sources in a three-dimensional frame, which is applicable to various measurement models (e.g., radar, sonar, or astronomy). Using the asymptotic analysis of the GLRT, we derive the ARL with constraints on the probabilities of false alarm and detection. Our results give explicit analytical expression for the ARL that is proportional to the square root of the CRB on the angular source separation, or equivalently to the lower bound on the MSAE.

Liu, Zhi

2007-08-01

166

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

E-print Network

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

167

Discussion of Alpha Particle Physics Issues for AT Burning Plasmas  

E-print Network

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

168

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

Microsoft Academic Search

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

Alkesh Punjabi; Maria Lam; Allen Boozer

1996-01-01

169

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

SciTech Connect

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

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

2008-01-01

170

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

Microsoft Academic Search

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

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

1988-01-01

171

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

172

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

PubMed

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

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

2014-03-01

173

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

174

Monte Carlo simulation of age-dependent radiation dose from alpha- and beta-emitting radionuclides to critical trabecular bone and bone marrow targets  

NASA Astrophysics Data System (ADS)

Alpha (?) particles and low-energy beta (?) particles present minimal risk for external exposure. While these particles can induce leukemia and bone cancer due to internal exposure, they can also be beneficial for targeted radiation therapies. In this paper, a trabecular bone model is presented to investigate the radiation dose from bone- and marrow-seeking ? and ? emitters to different critical compartments (targets) of trabecular bone for different age groups. Two main issues are addressed with Monte Carlo simulations. The first is the absorption fractions (AFs) from bone and marrow to critical targets within the bone for different age groups. The other issue is the application of 223Ra for the radiotherapy treatment of bone metastases. Both a static model and a simulated bone remodeling process are established for trabecular bone. The results show significantly lower AFs from radionuclide sources in the bone volume to the peripheral marrow and the haematopoietic marrow for adults than for newborns and children. The AFs from sources on the bone surface and in the bone marrow to peripheral marrow and haematopoietic marrow also varies for adults and children depending on the energy of the particles. Regarding the use of 223Ra as a radionuclide for the radiotherapy of bone metastases, the simulations show a significantly higher dose from 223Ra and its progeny in forming bone to the target compartment of bone metastases than that from two other more commonly used ?-emitting radiopharmaceuticals, 153Sm and 89Sr. There is also a slightly lower dose from 223Ra in forming bone to haematopoietic marrow than that from 153Sm and 89Sr. These results indicate a higher therapy efficiency and lower marrow toxicity from 223Ra and its progeny. In conclusion, age-related changes in bone dimension and cellularity seem to significantly affect the internal dose from ? and ? emitters in the bone and marrow to critical targets, and 223Ra may be a more efficient radiopharmaceutical for the treatment of bone metastases than 153Sm and 89Sr, if the diffusion of 219Rn to the bone marrow is insignificant.

Dant, James T.; Richardson, Richard B.; Nie, Linda H.

2013-05-01

175

Size distribution, chemical composition, and hygroscopicity of fine particles emitted from an oil-fired heating plant.  

PubMed

Heavy fuel oil (HFO) is a commonly used fuel in industrial heating and power generation and for large marine vessels. In this study, the fine particle emissions of a 47 MW oil-fired boiler were studied at 30 MW power and with three different fuels. The studied fuels were HFO, water emulsion of HFO, and water emulsion of HFO mixed with light fuel oil (LFO). With all the fuels, the boiler emitted considerable amounts of particles smaller than 200 nm in diameter. Further, these small particles were quite hygroscopic even as fresh and, in the case of HFO+LFO emulsion, the hygroscopic growth of the particles was dependent on particle size. The use of emulsions and the addition of LFO to the fuel had a reducing effect on the hygroscopic growth of particles. The use of emulsions lowered the sulfate content of the smallest particles but did not affect significantly the sulfate content of particles larger than 42 nm and, further, the addition of LFO considerably increased the black carbon content of particulate matter. The results indicate that even the fine particles emitted from HFO based combustion can have a significant effect on cloud formation, visibility, and air quality. PMID:24245691

Happonen, Matti; Myllri, Fanni; Karjalainen, Panu; Frey, Anna; Saarikoski, Sanna; Carbone, Samara; Hillamo, Risto; Pirjola, Liisa; Hyrinen, Anna; Kytmki, Jorma; Niemi, Jarkko V; Keskinen, Jorma; Rnkk, Topi

2013-12-17

176

Volatile properties of particles emitted by compressed natural gas and diesel buses during steady-state and transient driving modes.  

PubMed

Volatile properties of particle emissions from four compressed natural gas (CNG) and four diesel buses were investigated under steady-state and transient driving modes on a chassis dynamometer. The exhaust was diluted utilizing a full-flow continuous volume sampling system and passed through a thermodenuder at controlled temperature. Particle number concentration and size distribution were measured with a condensation particle counter and a scanning mobility particle sizer, respectively. We show that while almost all the particles emitted by the CNG buses were in the nanoparticle size range, at least 85% and 98% were removed at 100 and 250 C, respectively. Closer analysis of the volatility of particles emitted during transient cycles showed that volatilization began at around 40 C, with the majority occurring by 80 C. Particles produced during hard acceleration from rest exhibited lower volatility than those produced during other times of the cycle. On the basis of our results and the observation of ash deposits on the walls of the tailpipes, we suggest that these nonvolatile particles were composed mostly of ash from lubricating oil. Heating the diesel bus emissions to 100 C removed ultrafine particle numbers by 69-82% when a nucleation mode was present and just 18% when it was not. PMID:22107263

Jayaratne, E R; Meyer, N K; Ristovski, Z D; Morawska, L

2012-01-01

177

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

E-print Network

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

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

2014-02-10

178

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

179

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

180

Observation of beam-induced changes in the polarization of Balmer-alpha radiation emitted following beam-tilted-foil transmission  

Microsoft Academic Search

Measurements of the circular polarization of Balmer-alpha radiation emitted by excited hydrogen atoms, following the transmission of (20-50)-keV protons through thin, tilted amorphous carbon foils, exhibit markedly unexpected behavior as a function of exposure of the foil to the proton beam. Specifically, the circular polarization changes from an initially well understood tilt-angle dependence to a behavior which, for low tilt

Douglas L. Harper; Royal G. Albridge; Norman H. Tolk; Wang Qi; David D. Allred; Larry V. Knight

1995-01-01

181

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

PubMed Central

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

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

2014-01-01

182

PRESENT-DAY DESCENDANTS OF z = 3 Ly{alpha}-EMITTING GALAXIES IN THE MILLENNIUM-II HALO MERGER TREES  

SciTech Connect

Using the Millennium-II Simulation dark matter sub-halo merger histories, we created mock catalogs of Ly{alpha}-emitting (LAE) galaxies at z = 3.1 to study the properties of their descendants. Several models were created by selecting the sub-halos to match the number density and typical dark matter mass determined from observations of these galaxies. We used mass-based and age-based selection criteria to study their effects on descendant populations at z {approx_equal} 2, 1, and 0. For the models that best represent LAEs at z = 3.1, the z = 0 descendants have a median dark matter halo mass of 10{sup 12.7} M{sub Sun }, with a wide scatter in masses (50% between 10{sup 11.8} and 10{sup 13.7} M{sub Sun }). Our study differentiated between central and satellite sub-halos and found that {approx}55% of z = 0 descendants are central sub-halos with M{sub Median} {approx} 10{sup 12}. This confirms that central z = 0 descendants of z = 3.1 LAEs have halo masses typical of L*-type galaxies. The satellite sub-halos reside in group/cluster environments with dark matter masses around 10{sup 14} M{sub Sun }. The median descendant mass is robust to various methods of age determination, but it could vary by a factor of five due to current observational uncertainties in the clustering of LAEs used to determine their typical z = 3.1 dark matter mass.

Walker-Soler, Jean P.; Gawiser, Eric [Physics and Astronomy Department, Rutgers University, Piscataway, NJ 08854 (United States); Bond, Nicholas A. [Goddard Space Flight Center, Astrophysics Science Division, Observational Cosmology Laboratory, Greenbelt, MD 20771 (United States); Padilla, Nelson; Francke, Harold, E-mail: jpwalker@physics.rutgers.edu [Pontificia Universidad Catolica de Chile, Facultad de Fisica, Santiago (Chile)

2012-06-20

183

Alpha-particle emission probabilities in the decay of 238U  

PubMed

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

Garcia-Torano

2000-03-01

184

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

E-print Network

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

Fu, Guoyong

185

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

SciTech Connect

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

Kerns, J.A.

1986-05-01

186

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

Microsoft Academic Search

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

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

1963-01-01

187

Nuclear Spins and Magnetic Moments by the alpha-Particle Model  

Microsoft Academic Search

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

R. G. Sachs

1939-01-01

188

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

SciTech Connect

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

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

1980-12-01

189

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

190

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

ERIC Educational Resources Information Center

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

Digilov, M.

1991-01-01

191

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

192

Condition for absolute confinement of alpha-particles in axisymmetric tori  

Microsoft Academic Search

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

K. Ikuta

1976-01-01

193

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.

194

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

Microsoft Academic Search

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

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

2003-01-01

195

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

196

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

Microsoft Academic Search

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

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

1991-01-01

197

STACKED REST-FRAME ULTRAVIOLET SPECTRA OF Ly{alpha}-EMITTING AND CONTINUUM-SELECTED GALAXIES AT 2 < z < 3.5  

SciTech Connect

We present properties of individual and composite rest-UV spectra of continuum- and narrowband-selected star-forming galaxies (SFGs) at a redshift of 2 < z < 3.5 discovered by the MUSYC collaboration in the Extended Chandra Deep Field-South. Among our sample of 81 UV-bright SFGs, 59 have R < 25.5, of which 32 have rest-frame equivalent widths of W{sub Ly{alpha}} > 20 A, the canonical limit to be classified as an Ly{alpha}-emitting galaxy. We divide our data set into subsamples based on properties that we are able to measure for each individual galaxy: Ly{alpha} equivalent width, rest-frame UV colors, and redshift. Among our subsample of galaxies with R < 25.5, those with rest frame W{sub Ly{alpha}} > 20 A have bluer UV continua, weaker low-ionization interstellar absorption lines, weaker C IV absorption, and stronger Si II* nebular emission than those with W{sub Ly{alpha}} < 20 A. We measure a velocity offset of {Delta}v {approx} 600 km s{sup -1} between Ly{alpha} emission and low-ionization absorption, which does not vary substantially among any of our subsamples. We find that the interstellar component, as opposed to the stellar component, dominates the high-ionization absorption line profiles. We find that the low- and high-ionization Si ionization states have similar kinematic properties, yet the low-ionization absorption is correlated with Ly{alpha} emission and the high-ionization absorption is not. These trends are consistent with outflowing neutral gas being in the form of neutral clouds embedded in ionized gas as previously suggested by Steidel et al. Moreover, our galaxies with bluer UV colors have stronger Ly{alpha} emission, weaker low-ionization absorption, and more prominent nebular emission line profiles. From a redshift of 2.7 < z < 3.5 to 2.0 < z < 2.7, our subsample of galaxies with W{sub Ly{alpha}} < 20 Angstrom-Sign shows no significant evolution in their physical properties or the nature of their outflows. Among our data set, UV-bright galaxies with W{sub Ly{alpha}} > 20 A exhibit weaker Ly{alpha} emission at lower redshifts, although we caution that this could be caused by spectroscopic confirmation of low Ly{alpha} equivalent width galaxies being harder at z {approx} 3 than z {approx} 2.

Berry, Michael; Gawiser, Eric [Physics and Astronomy Department, Rutgers University, Piscataway, NJ 08854-8019 (United States); Guaita, Lucia [Department of Astronomy, Oskar Klein Cosmology Centre, Stockholm University, Stolkholm (Sweden); Padilla, Nelson; Francke, Harold [Department of Astronomy and Astrophysics, Pontificia Universidad Catolica de Chile, Santiago (Chile); Treister, Ezequiel [Department of Astronomy, Universidad de Concepcion, Concepcion (Chile); Blanc, Guillermo A. [Observatories of the Carnegie Institution for Science, Pasadena, CA (United States); Ciardullo, Robin; Gronwall, Caryl [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

2012-04-10

198

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

199

Factors influencing the number distribution and size of the particles emitted from a modern diesel vehicle in real urban traffic  

NASA Astrophysics Data System (ADS)

Particle emissions from diesel engine cars depend firstly on exhaust aftertreatment systems but the use of the vehicle becomes also crucial. In urban areas, this use depends on: transport demand, route choices, traffic density, street conditions, weather, driver behaviour and topographical characteristics of the roads. Nowadays, most diesel vehicles in urban areas across Europe are equipped with exhaust aftertreatment systems aiming to reduce the total mass of emitted particles. In comparison to earlier aftertreatment systems, the implementation of modern procedures is causing a reduction in the size of the emitted particles up to a nanometric range. The main goal of this work is the characterization of particle size and number distribution in the submicrometric range from a modern diesel vehicle emission in real traffic conditions in the city of Madrid with the purpose of assessing the actual weight of the different city parameters influencing the particle emission. In order to accomplish this objective, up to 12 on board emission measurement experiments have been performed with a Euro IV Diesel passenger car driving along a single urban circuit in Madrid City. To cover the main external factors, stretch, traffic conditions and driving directions have been considered as independent variables for this study. Assuming a proper car operating conditions, the results show that street characteristics, vehicle density and topographic features are the main factors conditioning the particle emission. Extrapolating our results, a diesel standard passenger car circulating across a city like Madrid can emit more nanoparticles per kilometre (up to 114% more in this study) at peak hour than at off peak hour. Moreover, the driving direction can also influence dramatically the emission of nanoparticles per second. This difference in the emission rate depends on the street but in our study it can be higher than 110% depending on the driving direction.

Barrios, C. C.; Domnguez-Sez, A.; Rubio, J. R.; Pujadas, M.

2012-09-01

200

Map model for nonlinear alpha particle interaction with toroidal Alfven waves  

SciTech Connect

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

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

1992-09-01

201

A Luminosity Function of Ly(alpha)-Emitting Galaxies at Z [Approx. Equal to] 4.5(Sup 1),(Sup 2)  

NASA Technical Reports Server (NTRS)

We present a catalog of 59 z [approx. equal to] 4:5 Ly(alpha)-emitting galaxies spectroscopically confirmed in a campaign of Keck DEIMOS follow-up observations to candidates selected in the Large Are (LALA) narrowband imaging survey.We targeted 97 candidates for spectroscopic follow-up; by accounting for the variety of conditions under which we performed spectroscopy, we estimate a selection reliability of approx.76%. Together with our previous sample of Keck LRIS confirmations, the 59 sources confirmed herein bring the total catalog to 73 spectroscopically confirmed z [approx. equal to] 4:5 Ly(alpha)- emitting galaxies in the [approx. equal to] 0.7 deg(exp 2) covered by the LALA imaging. As with the Keck LRIS sample, we find that a nonnegligible fraction of the co rest-frame equivalent widths (W(sub lambda)(sup rest)) that exceed the maximum predicted for normal stellar populations: 17%-31%(93%confidence) of the detected galaxies show (W(sub lambda)(sup rest)) 12%-27% (90% confidence) show (W(sub lambda)(sup rest)) > 240 A. We construct a luminosity function of z [approx. equal to] 4.5 Ly(alpha) emission lines for comparison to Ly(alpha) luminosity function < 6.6. We find no significant evidence for Ly(alpha) luminosity function evolution from z [approx. equal to] 3 to z [approx. equal to] 6. This result supports the conclusion that the intergalactic me largely reionized from the local universe out to z [approx. equal to] 6.5. It is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z approx. 3 an z approx. 6 in continuum-selected Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations.

Dawson, Steve; Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel; Wang, JunXian; Dey, Arjun; Spinrad, Hyron; Jannuzi, Buell T.

2007-01-01

202

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

203

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

204

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

E-print Network

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

Peigney, Benjamin-Edouard; Tikhonchuk, Vladimir

2014-01-01

205

DIFFUSE Ly{alpha} EMITTING HALOS: A GENERIC PROPERTY OF HIGH-REDSHIFT STAR-FORMING GALAXIES  

SciTech Connect

Using a sample of 92 UV continuum-selected, spectroscopically identified galaxies with (z) = 2.65, all of which have been imaged in the Ly{alpha} line with extremely deep narrow-band imaging, we examine galaxy Ly{alpha} emission profiles to very faint surface brightness limits. The galaxy sample is representative of spectroscopic samples of Lyman break galaxies (LBGs) at similar redshifts in terms of apparent magnitude, UV luminosity, inferred extinction, and star formation rate and was assembled without regard to Ly{alpha} emission properties. Approximately 45% (55%) of the galaxy spectra have Ly{alpha} appearing in net absorption (emission), with {approx_equal} 20% satisfying commonly used criteria for the identification of 'Ly{alpha} emitters' (LAEs; W{sub 0}(Ly{alpha}) {>=} 20 A). We use extremely deep stacks of rest-UV continuum and continuum-subtracted Ly{alpha} images to show that all sub-samples exhibit diffuse Ly{alpha} emission to radii of at least 10'' ({approx}80 physical kpc). The characteristic exponential scale lengths for Ly{alpha} line emission exceed that of the {lambda}{sub 0} = 1220 A UV continuum light by factors of {approx}5-10. The surface brightness profiles of Ly{alpha} emission are strongly suppressed relative to the UV continuum light in the inner few kpc, by amounts that are tightly correlated with the galaxies' observed spectral morphology; however, all galaxy sub-subsamples, including that of galaxies for which Ly{alpha} appears in net absorption in the spectra, exhibit qualitatively similar diffuse Ly{alpha} emission halos. Accounting for the extended Ly{alpha} emission halos, which generally would not be detected in the slit spectra of individual objects or with typical narrow-band Ly{alpha} imaging, increases the total Ly{alpha} flux (and rest equivalent width W{sub 0}(Ly{alpha})) by an average factor of {approx}5, and by a much larger factor for the 80% of LBGs not classified as LAEs. We argue that most, if not all, of the observed Ly{alpha} emission in the diffuse halos originates in the galaxy H II regions but is scattered in our direction by H I gas in the galaxy's circum-galactic medium. The overall intensity of Ly{alpha} halos, but not the surface brightness distribution, is strongly correlated with the emission observed in the central {approx}1''-more luminous halos are observed for galaxies with stronger central Ly{alpha} emission. We show that whether or not a galaxy is classified as a giant 'Ly{alpha} blob' (LAB) depends sensitively on the Ly{alpha} surface brightness threshold reached by an observation. Accounting for diffuse Ly{alpha} halos, all LBGs would be LABs if surveys were sensitive to 10 times lower Ly{alpha} surface brightness thresholds; similarly, essentially all LBGs would qualify as LAEs.

Steidel, Charles C.; Bogosavljevic, Milan [California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Shapley, Alice E. [Department of Physics and Astronomy, University of California, Los Angeles, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095 (United States); Kollmeier, Juna A. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Reddy, Naveen A. [National Optical Astronomy Observatories, 950 North Cherry Avenue, Tucson, AZ 85258 (United States); Erb, Dawn K. [Department of Physics, University of California Santa Barbara, Santa Barbara, CA 93106 (United States); Pettini, Max [Institute of Astronomy, Madingley Road, Cambridge CB3 OHA (United Kingdom)

2011-08-01

206

The Apollo Alpha Spectrometer.  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

207

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

SciTech Connect

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

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

2013-07-18

208

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

E-print Network

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

NEXT Collaboration; V. lvarez; F. I. G. M. Borges; S. Crcel; S. Cebrin; A. Cervera; C. A. N. Conde; T. Dafni; J. Daz; M. Egorov; R. Esteve; P. Evtoukhovitch; L. M. P. Fernandes; P. Ferrario; A. L. Ferreira; E. D. C. Freitas; V. M. Gehman; A. Gil; A. Goldschmidt; H. Gmez; J. J. Gmez-Cadenas; D. Gonzlez-Daz; R. M. Gutirrez; J. Hauptman; J. A. Hernando Morata; D. C. Herrera; I. G. Irastorza; M. A. Jinete; L. Labarga; A. Laing; I. Liubarsky; J. A. M. Lopes; D. Lorca; M. Losada; G. Luzn; A. Mar; J. Martn-Albo; T. Miller; A. Moiseenko; F. Monrabal; C. M. B. Monteiro; F. J. Mora; L. M. Moutinho; J. Muoz Vidal; H. Natal da Luz; G. Navarro; M. Nebot-Guinot; D. Nygren; C. A. B. Oliveira; R. Palma; J. Prez; J. L. Prez Aparicio; J. Renner; L. Ripoll; A. Rodrguez; J. Rodrguez; F. P. Santos; J. M. F. dos Santos; L. Segui; L. Serra; D. Shuman; A. Simn; C. Sofka; M. Sorel; J. F. Toledo; A. Toms; J. Torrent; Z. Tsamalaidze; D. Vzquez; J. F. C. A. Veloso; R. Webb; J. T White; N. Yahlali

2012-11-19

209

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

PubMed Central

Ever since the discovery of X-rays was made by Rntgen more than a hundred years ago, it has always been accepted that the deleterious effects of ionizing radiation such as mutation and carcinogenesis are attributable mainly to direct damage to DNA. Although evidence based on microdosimetric estimation in support of a bystander effect appears to be consistent, direct proof of such extranuclear/extracellular effects are limited. Using a precision charged particle microbeam, we show here that irradiation of 20% of randomly selected AL cells with 20 alpha particles each results in a mutant fraction that is 3-fold higher than expected, assuming no bystander modulation effect. Furthermore, analysis by multiplex PCR shows that the types of mutants induced are significantly different from those of spontaneous origin. Pretreatment of cells with the radical scavenger DMSO had no effect on the mutagenic incidence. In contrast, cells pretreated with a 40 ?M dose of lindane, which inhibits cellcell 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 510% 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 cellcell communication process play a critical role in mediating the bystander phenomenon. PMID:10681418

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

2000-01-01

210

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

PubMed

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

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

2002-12-01

211

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

PubMed Central

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

1979-01-01

212

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

SciTech Connect

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

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

1994-09-01

213

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, Sbastien; Sgouros, George

2014-01-01

214

Blue-Emitting Small Silica Particles Incorporating ZnSe-Based Nanocrystals Prepared by Reverse Micelle Method  

PubMed Central

ZnSe-based nanocrystals (ca. 4-5 nm in diameter) emitting in blue region (ca. 445 nm) were incorporated in spherical small silica particles (2040 nm in diameter) by a reverse micelle method. During the preparation, alkaline solution was used to deposit the hydrolyzed alkoxide on the surface of nanocrystals. It was crucially important for this solution to include Zn2+ ions and surfactant molecules (thioglycolic acid) to preserve the spectral properties of the final silica particles. This is because these substances in the solution prevent the surface of nanocrystals from deterioration by dissolution during processing. The resultant silica particles have an emission efficiency of 16% with maintaining the photoluminescent spectral width and peak wavelength of the initial colloidal solution. PMID:18350119

Ando, Masanori; Li, Chunliang; Yang, Ping; Murase, Norio

2007-01-01

215

Bismuth-213 and actinium-225 -- generator performance and evolving therapeutic applications of two generator-derived alpha-emitting radioisotopes.  

PubMed

The alpha emitters (225)Ac and (213)Bi are promising therapeutic radionuclides for application in targeted alpha therapy of cancer and infectious diseases. Both alpha emitters are available with high specific activity from established radionuclide generators. Their favourable chemical and physical properties have led to the conduction of a large number of preclinical studies and several clinical trials, demonstrating the feasibility, safety and therapeutic efficacy of targeted alpha therapy with (225)Ac and (213)Bi. This review describes methods for the production of (225)Ac and (213)Bi and gives an overview of (225)Ac/(213)Bi radionuclide generator systems. Selected preclinical studies are highlighted and the current clinical experience with (225)Ac and (213)Bi is summarized. PMID:22642390

Morgenstern, Alfred; Bruchertseifer, Frank; Apostolidis, Christos

2012-07-01

216

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

E-print Network

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

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

1996-10-06

217

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

218

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

219

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

Microsoft Academic Search

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

C. R. Gruhn; M. D. Edmiston

1978-01-01

220

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

SciTech Connect

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

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

2013-08-15

221

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

Microsoft Academic Search

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

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

1976-01-01

222

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

223

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

SciTech Connect

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

Linfoot, J.A.

1980-01-01

224

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

225

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

SciTech Connect

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

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

2005-07-15

226

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

NASA Astrophysics Data System (ADS)

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

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

1993-07-01

227

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

228

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

E-print Network

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

229

Analysis of Individual Carbonaceous Particles Emitted from the Las Conchas Wildfire, Los Alamos, NM, in June-July 2011  

NASA Astrophysics Data System (ADS)

Carbonaceous aerosol emitted from biomass burning contributes significantly to atmospheric aerosol loadings regionally and globally. The net direct radiative forcing of biomass burning aerosol can be positive and/or negative and this depends on its composition, morphology and mixing state. Biomass burning aerosols can also change the cloud properties as they can act as cloud condensation nuclei. In this study we investigated biomass burning particles emitted from the Las Conchas wildfire in northern New Mexico that started on June 26, 2011 and burned an area of 245 square miles. Aerosol samples were collected on nucleopore filters at the Los Alamos National Laboratory during the third week of the wildfire event. Individual particles (~4000) were investigated using field-emission scanning electron microscopy and energy dispersive X-ray spectroscopy (EDS) to distinguish different carbonaceous particles and their shape, size, elemental composition and mixing state. A thermo-denuder was used to remove compounds that are volatile at temperatures up to 200 C, leaving behind the black carbon and any compounds that did not volatize completely. Smoke particles consisted of a) tar balls, which are amorphous spherical carbonaceous organic aerosols; b) organic particles with inorganic inclusions, c) soot particles and (d) soot with various inclusions. Two distinct kinds of tar balls, "electronically" dark and bright, were found using the field-emission scanning electron microscopy and were characterized for ambient and denuded conditions to understand coating effects and aging. It was found that dark tar balls are generally larger in size than the bright ones. Additionally, the difference between the size of ambient-bright and the size of denuded-bright tar balls was larger than the difference between the size of ambient-dark and the size of denuded-dark tar balls. EDS analysis showed that 70% of the dark tar balls had higher (~60%) relative oxygen content than in the bright tar balls. We conclude that there are two distinct kinds of biomass burning tar balls and that dark tar balls are less volatile than bright tar balls. The morphology of soot particles was also investigated by evaluating their fractal dimension for both ambient (coated with organic and inorganic material) and denuded samples at two different times of the day. The fractal dimension for ambient soot was found to be higher than for denuded soot due to the coating on the ambient soot particles. Finally, the monomer diameter decreased by up to 25% after denuding the particles. This study provides insights on the link between electron microscopy images of single particles and the mixing state, morphology, and evolution of different biomass burning aerosol at the beginning of their lifecycle.

Mazzoleni, C.; China, S.; Gorkowski, K.; Flowers, B. A.; Aiken, A. C.; Dubey, M. K.

2012-12-01

230

Possible stimulation of nuclear alpha decay by superfluid helium.  

PubMed

It is suggested that superfluid helium (condensate of (4)He atoms) may stimulate nuclear alpha decay in a situation when an alpha emitter moves through superfluid helium with fine-tuned velocity, so that the backward-emitted alpha particle is at rest in the laboratory frame. It is shown that the probability of stimulated alpha decay in this case may be sizable enough to be detected. PMID:19792793

Barabanov, A L

2009-08-28

231

Possible stimulation of nuclear alpha-decay by superfluid helium  

E-print Network

It is suggested that superfluid helium (condensate of 4-He atoms) may stimulate nuclear alpha-decay in a situation when an alpha-emitter moves through superfluid helium with fine-tuned velocity, so that the backward-emitted alpha-particle is at rest in the laboratory frame. It is shown that the probability of stimulated alpha-decay in this case may be sizable enough to be detected.

A. L. Barabanov

2009-02-26

232

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

233

A FLUX-LIMITED SAMPLE OF z {approx} 1 Ly{alpha} EMITTING GALAXIES IN THE CHANDRA DEEP FIELD SOUTH ,  

SciTech Connect

We describe a method for obtaining a flux-limited sample of Ly{alpha} emitters from Galaxy Evolution Explorer (GALEX) grism data. We show that the multiple GALEX grism images can be converted into a three-dimensional (two spatial axes and one wavelength axis) data cube. The wavelength slices may then be treated as narrowband images and searched for emission-line galaxies. For the GALEX NUV grism data, the method provides a Ly{alpha} flux-limited sample over the redshift range z = 0.67-1.16. We test the method on the Chandra Deep Field South field, where we find 28 Ly{alpha} emitters with faint continuum magnitudes (NUV > 22) that are not present in the GALEX pipeline sample. We measure the completeness by adding artificial emitters and measuring the fraction recovered. We find that we have an 80% completeness above a Ly{alpha} flux of 10{sup -15} erg cm{sup -2} s{sup -1}. We use the UV spectra and the available X-ray data and optical spectra to estimate the fraction of active galactic nuclei in the selection. We report the first detection of a giant Ly{alpha} blob at z < 1, though we find that these objects are much less common at z = 1 than at z = 3. Finally, we compute limits on the z {approx} 1 Ly{alpha} luminosity function and confirm that there is a dramatic evolution in the luminosity function over the redshift range z = 0-1.

Barger, A. J.; Wold, I. G. B. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Cowie, L. L. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2012-04-20

234

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

E-print Network

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

235

Bremsstrahlung in {alpha} Decay Reexamined  

SciTech Connect

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

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

2007-07-13

236

Bremsstrahlung in alpha decay reexamined.  

PubMed

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

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

2007-07-13

237

Dynamic radioactive particle source  

DOEpatents

A method and apparatus for providing a timed, synchronized dynamic alpha or beta particle source for testing the response of continuous air monitors (CAMs) for airborne alpha or beta emitters is provided. The method includes providing a radioactive source; placing the radioactive source inside the detection volume of a CAM; and introducing an alpha or beta-emitting isotope while the CAM is in a normal functioning mode.

Moore, Murray E.; Gauss, Adam Benjamin; Justus, Alan Lawrence

2012-06-26

238

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

239

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

240

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.

241

Photoluminescence study of gallium arsenide irradiated with 15 MeV alpha particles  

SciTech Connect

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

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

1999-12-01

242

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

243

A Redshift z=5.4 Lyman alpha Emitting Galaxy with Linear Morphology in the GRAPES/UDF Field  

E-print Network

We have discovered an extended Lyman alpha plume associated with a compact source at redshift 5.4 in slitless spectroscopic data from the Grism ACS Program for Extragalactic Science (GRAPES) project. The spatial extent of the emission is about 6 x 1.5 kpc (1 x 0.25 arcsec). Combining our grism data and the broadband images from the Hubble UltraDeep Field (UDF) images, we find a Lyman alpha line flux of 2e-17 erg/cm2/s and surface brightness 7e-17 erg/cm2/s/arcsec2. The UDF images show diffuse continuum emission associated with the Lyman alpha plume (hereafter UDF 5225), with three embedded knots. The morphology of UDF 5225 is highly suggestive of a galaxy in assembly. It is moreover possible that the prominent Lyman alpha emission from this object is due to an active nucleus, and that we are seeing the simultaneous growth through accretion of a galaxy and its central black hole. Followup observations at higher spectral resolution could test this hypothesis.

James E. Rhoads; Nino Panagia; Rogier A. Windhorst; Sangeeta Malhotra; Norbert Pirzkal; Chun Xu; Louis Gregory Strolger; Louis E. Bergeron; Emanuele Daddi; Henry C. Ferguson; Jonathan P. Gardner; Caryl Gronwall; Zoltan Haiman; Anton Koekemoer; Martin Kuemmel; Leonidas A. Moustakas; Anna Pasquali; Adam Riess; Sperello di Serego Alighieri; Massimo Stiavelli; Zlatan Tsvetanov; Joel Vernet; Jeremy Walsh; Haojing Yan

2004-08-02

244

Atmospheric behavior of trace elements on particles emitted from a coal-fired power plant  

NASA Astrophysics Data System (ADS)

Filter and cascade impactor samples of suspended particles were collected in-stack and at distances up to 64 km downwind in the plume of a large western coal-fired power plant equipped with both electrostatic precipitators (ESP) and venturi wet particulate scrubbers (VWS) to investigate modifications of the particulate signatures of minor and trace elements during transport. Samples were analyzed for 40 elements by instrumental neutron activation analysis. Precipitator malfunction during the experiment caused greater than normal emission of large particles, and concentrations of As, Zn, Sb, Mo, Ga, W, U, V and Ba in near-plume particles collected on filters were enriched relative to their concentrations in stack particles by factors of 1.4 to 2.5, presumably because of sedimentation of very large particles. Selenium was enriched by up to 6-fold (plume:stack). However, enrichment of elements in the plume relative to more typical in-stack particles were insignificant for all elements except Se, which was enriched 2.3-fold. Concentrations of Se on particles in the stack and plume suggest that most of the Se vapor in stack gases became associated with aerosol particles soon after emission. Thus although significant post-emission modifications of elemental signatures of particles may occur for poorly controlled plants, little change is expected for well-controlled plants equipped with ESPs except for Se. Source signatures measured for Se must account for vapor deposition. Impactor data showed a preferential decrease in the concentrations of the above elements in submicrometer particles; suggesting that either intermodal coagulation or size selective sampling losses were important. The impactor data further suggest that enrichment-particle-size profiles for VWS emissions were not conservative during transport.

Ondov, J. M.; Choquette, C. E.; Zoller, W. H.; Gordon, G. E.; Biermann, A. H.; Heft, R. E.

245

Modification of arc emitted W particles in a model scrape-off layer plasma  

NASA Astrophysics Data System (ADS)

In fusion machines (like e.g. ASDEX Upgrade and JET) equipped with W-coated plasma facing components (PFCs) arc tracks are observed post-mortem and W particles are identified as a component of the dust. Results from laboratory arcing of W-coated PFC-material concerning the size, velocity and direction of macro-particles are combined with model calculations of the heating, cooling and evaporation of W particles flying through a simplified scrape-off layer (SOL) plasma to assess the role of arc-produced particles as a source of W impurities. W atoms or ions eroded from a macro-particle flying across the SOL plasma are not subject to prompt re-deposition onto a PFC. Therefore, macro-particles constitute an essential source of W in the SOL and may even result in an impurity input into the region of confined plasma if the particle succeeds in pathing the SOL and crosses the last closed flux surface. The main result of the modelling is that a W particle from the large-size end of the distribution obtained in laboratory arcing and having a typical velocity (also known from laboratory experiment) is able to pass a SOL of 10 cm thickness filled with a realistic plasma and, finally, inject a certain amount of W-material into the confined plasma region.

Laux, M.; Balden, M.; Siemroth, P.

2014-04-01

246

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

Microsoft Academic Search

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

Frank Asaro; I. Perlman

1956-01-01

247

Red-Emitting Phosphor Particles with Spherical Shape, Dense Morphology, and High Luminescent Efficiency under Ultraviolet  

NASA Astrophysics Data System (ADS)

Gd2O3:Eu phosphor particles of spherical shape, filled morphology, and high brightness were prepared by large-scale spray pyrolysis. The morphology control of Gd2O3:Eu particles was attempted by adding organic precursors in a spray solution. The influence of chain length of organic additives and introduction of esterification reaction within the droplet on the morphological and luminescent characteristics of Gd2O3:Eu particles was studied. The particles prepared from aqueous solution with no organic additive showed the hollow and porous shell structure and poor brightness, while those particles prepared from solutions with only polyethylene glycol (PEG) exhibited relatively filled structure and high brightness. The longer the chain length of added PEG is, the better morphological and luminescence characteristics the particles showed. The introduction of esterification reaction within the droplet by adding citric acid (CA) and ethylene glycol (EG) or PEG with various molecular weight enhanced the morphological characteristics and significantly improved photoluminescence characteristics regardless of chain length of PEG. The particles prepared from solution containing 0.1 M CA and 0.1 M PEG (M.W. 1500) showed the maximum photoluminescence intensity, which was 148% that of commercial product.

Kang, Yun Chan; Roh, Hyun Sook; Park, Seung Bin; Jung, Kyeong Youl

2004-08-01

248

Analysis of particle-borne odorants emitted from concentrated animal feeding operations.  

PubMed

Airborne particles are known to serve as a carrier of odors emanating from concentrated animal feeding operations (CAFOs). However, limited quantitative data about particle-borne odorants preclude an accurate assessment of the role of particles in odor transport. This study collected total suspended particulates (TSP) and PM10 (particles with aerodynamic diameter smaller than 10 ?m) at the air exhaust of eight types of CAFOs (swine: farrowing, gestation, weaning, and finishing; poultry: manure-belt layer hen, tom turkey, chicken broiler, and cage-free layer hen; in total 20 animal buildings) in multiple seasons, and examined the variability in particle odorant composition with animal operation type, season, and particle size. Fifty-seven non-sulfur-containing odorants were identified and quantitated, including carbonyls, alcohols, acids, phenols, and nitrogen-containing compounds. They in total accounted for 2.191.52% TSP and 4.973.25% PM10 mass. Acetic acid and ethanol were most abundant but less odor-contributing than phenylacetic acid, indole, dodecanoic acid, and (E,E)-2,4-decadienal, as determined by odor activity value. Particle odorant composition varied significantly with animal operation type, season, and particle size. The TSP and PM10 samples from swine gestation buildings, for example, showed distinctly different odorant compositions than those from tom turkey buildings. The summer TSP and PM10 samples contained in general lower concentrations of short-chain fatty acids but higher concentrations of long-chain fatty acids, aldehydes, and short-chain alcohols than the winter samples. Compared to TSP, PM10 samples from different types of CAFOs shared a more similar odorant composition, contained higher odorant concentrations per mass of particles, and accounted for on average 53.2% of the odor strength of their corresponding TSP samples. PMID:24863138

Yang, Xufei; Lorjaroenphon, Yaowapa; Cadwallader, Keith R; Wang, Xinlei; Zhang, Yuanhui; Lee, Jongmin

2014-08-15

249

Effects of Color Temperature and Brightness on Electroencephalogram Alpha Activity in a Polychromatic Light-emitting Diode  

PubMed Central

Objective It has been reported that working and learning efficiency might be increased through artificially controlling the color temperature and brightness of light. However, the neurological bases of these outcomes are not well established. Our study was designed to observe whether electroencephalogram (EEG) alpha frequency, as a candidate biological marker, demonstrates significant changes in response to alterations of specific light parameters. Methods Thirty-two healthy subjects performed cognitive tasks under four different polychromatic light conditions: a combination of two different levels of color temperature (2766K vs. 5918K) and brightness (300 lux vs. 600 lux). Spectrum analyses were performed on alpha frequency. Results Subjects reported that they felt more pleasant in bright conditions and more relaxed in warm color temperature conditions. Our findings indicate that alpha power increases in warm, low-light and cool, high-light conditions, and there is a significant interaction between color temperature and brightness. Conclusion EEGs might serve as a useful biological marker for further research related to the effects of polychromatic light on cognitive function. PMID:24465248

Park, Jin Young; Ha, Ra-Yeon; Ryu, Vin; Kim, Eosu

2013-01-01

250

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

251

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

252

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

SciTech Connect

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

Marsh, S.F.

1991-01-01

253

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

254

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

NASA Technical Reports Server (NTRS)

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

Franco, V.; Yin, Y.

1985-01-01

255

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

256

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

NASA Astrophysics Data System (ADS)

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

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

1991-05-01

257

Feasibility of an alpha particle gas densimeter for stack sampling applications  

E-print Network

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

Johnson, Randall Mark

2012-06-07

258

Damage of EUV optical coatings induced by alpha-particles bombardment  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

259

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

PubMed

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

Ziegler, J F

1999-08-01

260

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

NASA Astrophysics Data System (ADS)

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

Ceperley, D.; Alder, B. J.

1985-04-01

261

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

NASA Astrophysics Data System (ADS)

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

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

262

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

Microsoft Academic Search

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

Eidson

1962-01-01

263

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

E-print Network

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

Yu, K.N.

264

Clinical Experience with a-Particle-Emitting 211At: Treatment of Recurrent Brain Tumor Patients with 211At-Labeled Chimeric Antitenascin Monoclonal Antibody 81C6  

Microsoft Academic Search

a-Particle-emitting radionuclides, such as 211At, with a 7.2-h half-life, may be optimally suited for the molecularly targeted ra- diotherapy of strategically sensitive tumor sites, such as those in the central nervous system. Because of the much shorter range and more potent cytotoxicity of a-particles than of b-particles, 211At-labeled agents may be ideal for the eradication of tumor cells remaining after

Michael R. Zalutsky; David A. Reardon; Gamal Akabani; R. Edward Coleman; Allan H. Friedman; Henry S. Friedman; Roger E. McLendon; Terence Z. Wong; Darell D. Bigner

265

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

266

Pseudorapidity spectra of relativistic particles emitted in the Au and Pb induced reactions at high energies  

E-print Network

The structure of the pseudorapidity spectra of charged relativistic particles with beta > 0.7 measured in Au+Em and Pb+Em collisions at AGS and SPS energies are analyzed using Fourier transformation method and maximum entropy one. The dependences of these spectra on the number of fast target protons (g-particles) are studied. They show visually some plateau and "shoulder" which are at least three selected points on the distributions. The plateau seems wider in Pb+Em reactions. The existing of plateau is expected for the parton models. The maximum entropy method confirms the existence of the plateau and the shoulder of the distributions.

B. Z. Belashev; M. K. Suleymanov; S. Vokl; J. Vrlkov; M. Ajaz; K. H. Khan; Ali Zaman; Z. Wazir

2011-01-22

267

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

SciTech Connect

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

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

2010-02-15

268

TOXICITY OF PARTICLES EMITTED FROM COMBUSTION OF WASTE CRANKCASE OIL: IN VITRO AND IN VIVO STUDIES  

EPA Science Inventory

The ever-rising cost of energy provides incentives for the utilization of waste crankcase oil (WCO) for space heating. The potential health hazards of emissions and waste products resulting from the combustion of WCO are unknown. The toxicity of the emission particles and waste p...

269

CHARACTERIZATION OF INDIVIDUAL FLY ASH PARTICLES EMITTED FROM COAL- AND OIL-FIRED POWER PLANTS  

EPA Science Inventory

Individual particles from coal- and oil-fired power plants were analyzed by a scanning electron microscope equipped with an energy dispersive X-ray spectrometer to investigate the morphology and composition as a function of size. Samples were collected on filters by a dichotomous...

270

The evolution of energetic particles and the emitted radiation in solar flares. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

The evolution of accelerated particle distributions in a magnetized plasma and the resulting radiation are calculated, and the results are applied to solar flares. To study the radiation on timescales of order the particle lifetimes, the evolution of the particle distribution is determined by the use of the Fokker-Planck equation including Coulomb collisions and magnetic mirroring. Analytic solution to the equations are obtained for limiting cases such as homogeneous injection in a homogeneous plasma, and for small pitch angle. These analytic solutions are then used to place constraints on flare parameters such as density, loop length, and the injection timescale for very short implusive solar flares. For general particle distributions in arbitrary magnetic field and background density, the equation is solved numerically. The relative timing of microwaves and X-rays during individual flares is investigated. A number of possible sources for excessive microwave flux are discussed including a flattening in the electron spectrum above hard X-ray energies, thermal synchrotron emission, and trapping of electron by converging magnetic fields. Over shorter timescales, the Fokker-Planck equation is solved numerically to calculate the temporal evolution of microwaves and X-rays from nonthermal thick target models. It is shown that magnetic trapping will not account for the observed correlation of microwaves of approximately 0.15 seconds behind X-rays in flares with rapid time variation, and thus higher energy electrons must be accelerated later than lower energy electrons.

Lu, Edward Tsang

1989-01-01

271

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

NASA Astrophysics Data System (ADS)

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

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

1988-07-01

272

Targeted cytoplasmic irradiation with alpha particles induces mutations in mammalian cells  

PubMed Central

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

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

1999-01-01

273

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

274

A clear patch in the dark age Universe? Looking for reionization sources around two bright Ly-alpha emitting galaxies at z=7  

NASA Astrophysics Data System (ADS)

The last few years have seen a number of discoveries that provided the first glimpse of the Universe at z>7 using both space and ground-based telescopes. The spectroscopic determination of a significant decrease at z>6 of the Ly-alpha emitter fraction among Lyman break galaxies (LBGs) has been interpreted as evidence for a rapid increase of the neutral HI in the inter-galactic medium (IGM). Among the different lines of sight explored so far, the BDF field stands out as a peculiar area since it contains two bright, high EW, Ly-alpha emitting galaxies at z=7.008 and z=7.109. However, their UV luminosity is not sufficient to generate an ionized region large enough to explain the observability of their Ly-alpha lines: the close physical distance between the two objects (4.4Mpc) thus suggests that they might be included in the same, large HII bubble which is ionized thanks to contribution of a yet undetected population of fainter sources. Indeed, theoretical models predict that a factor of 4-10 overdensity of z-dropout galaxies with respect to the available, robust determinations of the z~7 UV LF, should be detected by pushing the detection limits to Y=27.5 (M(UV)=-19.5).A small investment of HST time will allow us to perform a direct test of these theoretical predictions by searching for additional ionizing sources through standard optical/near IR photometric criteria. With the proposed observations we will be able to confirm whether the BDF area is the first re-ionized "bubble'' ever detected in the early Universe. This will help us to understand the earliest phases of galaxy formation and see the process of reionization caught in the act.

Castellano, Marco

2014-10-01

275

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

276

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

277

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

SciTech Connect

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

Sasaki, H.

1984-08-01

278

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

PubMed

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

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

2012-04-01

279

THE EVOLUTION OF Ly{alpha}-EMITTING GALAXIES BETWEEN z = 2.1 AND z = 3.1  

SciTech Connect

We describe the results of a new, wide-field survey for z = 3.1 Ly{alpha} emitters (LAEs) in the Extended Chandra Deep Field South (ECDF-S). By using a nearly top-hat 5010 A filter and complementary broadband photometry from the MUSYC survey, we identify a complete sample of 141 objects with monochromatic fluxes brighter than 2.4 Multiplication-Sign 10{sup -17} erg cm{sup -2} s{sup -1} and observers-frame equivalent widths (EWs) greater than {approx}80 A (i.e., 20 A in the rest frame of Ly{alpha}). The bright end of this data set is dominated by X-ray sources and foreground objects with Galaxy Evolution Explorer detections, but when these interlopers are removed, we are still left with a sample of 130 LAE candidates, 39 of which have spectroscopic confirmations. This sample overlaps the set of objects found in an earlier ECDF-S survey, but due to our filter's redder bandpass, it also includes 68 previously uncataloged sources. We confirm earlier measurements of the z = 3.1 LAE emission-line luminosity function and show that an apparent anticorrelation between EW and continuum brightness is likely due to the effect of correlated errors in our heteroskedastic data set. Finally, we compare the properties of z = 3.1 LAEs to LAEs found at z = 2.1. We show that in the {approx}1 Gyr after z {approx} 3, the LAE luminosity function evolved significantly, with L* fading by {approx}0.4 mag, the number density of sources with L > 1.5 Multiplication-Sign 10{sup 42} erg s{sup -1} declining by {approx}50%, and the EW scale length contracting from 70{sup +7}{sub -5} A to 50{sup +9}{sub -6} A. When combined with literature results, our observations demonstrate that over the redshift range z {approx} 0 to z {approx} 4, LAEs contain less than {approx}10% of the star formation rate density of the universe.

Ciardullo, Robin; Gronwall, Caryl; Wolf, Christopher; McCathran, Emily; Matkovic, Ana [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); and others

2012-01-10

280

The Evolution of Ly-alpha Emitting Galaxies Between z = 2.1 and z = 3.l  

NASA Technical Reports Server (NTRS)

We describe the results of a new, wide-field survey for z= 3.1 Ly-alpha emission-line galaxies (LAEs) in the Extended Chandra Deep Field South (ECDF-S). By using a nearly top-hat 5010 Angstrom filter and complementary broadband photometry from the MUSYC survey, we identify a complete sample of 141 objects with monochromatic fluxes brighter than 2.4E-17 ergs/cm^2/s and observers-frame equivalent widths greater than 80 Angstroms (i.e., 20 Angstroms in the rest-frame of Ly-alpha). The bright-end of this dataset is dominated by x-ray sources and foreground objects with GALEX detections, but when these interlopers are removed, we are still left with a sample of 130 LAE candidates, 39 of which have spectroscopic confirmations. This sample overlaps the set of objects found in an earlier ECDF-S survey, but due to our filter's redder bandpass, it also includes 68 previously uncataloged sources. We confirm earlier measurements of the z=3.1 LAE emission-line luminosity function, and show that an apparent anti-correlation between equivalent width and continuum brightness is likely due to the effect of correlated errors in our heteroskedastic dataset. Finally, we compare the properties of z=3.1 LAEs to LAEs found at z=2.1. We show that in the approximately 1 Gyr after z approximately 3, the LAE luminosity function evolved significantly, with L * fading by approximately 0.4 mag, the number density of sources with L greater than 1.5E42 ergs/s declining by approximately 50%, and the equivalent width scalelength contracting from 70^{+7}_{-5} Angstroms to 50^{+9}_{-6} Angstroms. When combined with literature results, our observations demonstrate that over the redshift range z approximately 0 to z approximately 4, LAEs contain less than approximately 10% of the star-formation rate density of the universe.

Ciardullo, Robin; Gronwall,Caryl; Wolf, Christopher; McCathran, Emily; Bond, Nicholas A.; Gawiser, Eric; Guaita, Lucia; Feldmeier, John J.; Treister, Ezequiel; Padilla, Nelson; Francke, Harold; Matkovic, Ana; Altmann, Martin; Herrera, David

2011-01-01

281

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

PubMed Central

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

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

2012-01-01

282

Combustion particles emitted during church services: implications for human respiratory health.  

PubMed

Burning candles and incense generate particulate matter (PM) that produces poor indoor air quality and may cause human pulmonary problems. This study physically characterised combustion particles collected in a church during services. In addition, the emissions from five types of candles and two types of incense were investigated using a combustion chamber. The plasmid scission assay was used to determine the oxidative capacities of these church particles. The corresponding risk factor (CRf) was derived from the emission factor (Ef) and the oxidative DNA damage, and used to evaluate the relative respiratory exposure risks. Real-time PM measurements in the church during candle-incense burning services showed that the levels (91.6 ?g/m(3) for PM(10); 38.9 ?g/m(3) for PM(2.5)) exceeded the European Union (EU) air quality guidelines. The combustion chamber testing, using the same environmental conditions, showed that the incense Ef for both PM(10) (490.6-587.9 mg/g) and PM(2.5) (290.1-417.2 mg/g) exceeded that of candles; particularly the PM(2.5) emissions. These CRf results suggested that the exposure to significant amounts of incense PM could result in a higher risk of oxidative DNA adducts (27.4-32.8 times) than tobacco PM. The generation and subsequent inhalation of PM during church activities may therefore pose significant risks in terms of respiratory health effects. PMID:21831441

Chuang, Hsiao-Chi; Jones, Tim; BruB, Kelly

2012-04-01

283

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

SciTech Connect

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

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

2009-07-15

284

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

SciTech Connect

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

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

1991-12-01

285

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

286

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

287

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

PubMed

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

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

2006-01-01

288

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

NASA Astrophysics Data System (ADS)

Part of the energy of the Lower Hybrid (LH) waves may be absorbed by the ? particles via the so-called perpendicular landau damping mechanism, which depends on various parameters of fusion reactors and the LH waves. In this article, we calculate the absorption coefficient ?? of LH waves due to ? particles. Results show that, the ?? increases with the parallel refraction index n? while deceases with increasing the frequency of LH waves ?LH over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of ?? when ne?81019m-3 for ITER-like scenario. The thermal corrections to the cold plasma dispersion relation will change the damping rate to a certain extent under some specific conditions. We have also evaluated the fraction of LH power absorbed by the alpha particles, ? ? 0.47% and 4.1% for an LH frequency of 5 GHz and 3.7 GHz respectively for ITER-like scenario. This work gives the effective reference for the choice of parameters of future fusion reactors.

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

2014-02-01

289

THz photoconductivity in light-emitting surface-oxidized Si nanocrystals: the role of large particles  

NASA Astrophysics Data System (ADS)

We propose an analytical description of the role of local depolarization fields in the terahertz conductivity of nanostructured samples and demonstrate this approach in a sample composed of silicon nanocrystals. This helps to uncover the nature of charge carrier transport at nanoscale. Time-resolved terahertz conductivity is investigated in an ensemble of silicon nanocrystals fabricated by electrochemical etching of silicon wafer followed by an H2O2 oxidizing treatment. The post-etching treatment leads to a decrease in the average nanocrystalline Si core size which enhances luminescence in the visible range. We show that the dominating microscopic photoconductive response of photocarriers is essentially Drude-like owing to the presence of a very small amount of large nanocrystals; the macroscopic character of the response is, however, deeply modified by the depolarization fields. Smaller nanocrystals appreciably contribute to the terahertz conductivity only at high photoexcitation densities where the screening due to depolarization fields suppresses the response of the large particles.

Zajac, V.; N?mec, H.; Kadlec, C.; K?sov, K.; Pelant, I.; Kuel, P.

2014-09-01

290

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

Microsoft Academic Search

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

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

1998-01-01

291

THE REST-FRAME ULTRAVIOLET LIGHT PROFILE SHAPES OF Ly{alpha}-EMITTING GALAXIES AT z = 3.1  

SciTech Connect

We present a morphological analysis of the rest-frame ultraviolet emission of 78 resolved, high signal-to-noise z {approx} 3.1 Ly{alpha} emitters (LAEs) in the Extended Chandra Deep Field-South. Using Hubble Space Telescope/Advanced Camera for Surveys V-band images taken as part of the Galaxy Evolution from Morphology and SEDs, Great Observatories Origins Deep Survey, and Hubble Ultra Deep Field surveys, we investigate both single-component and multi-component LAEs, and derive concentration indices, Sersic indices, ellipticities, and half-light radii for all resolved components and systems with a signal-to-noise >30. We show that, although the LAE population is heterogeneous in nature, most LAEs are highly concentrated, with a distribution of C values similar to that measured for field stars; this suggests that the diagnostic is a poor discriminator near the resolution limit. The LAEs also display a wide range of Sersic indices (0 < n < 12), similar to that seen for galaxies in the local neighborhood. However, the majority of LAEs have n < 2, and a visual inspection of the images suggests that the small-n objects have extended or multimodal luminosity profiles, while the LAEs with n > 2 have compact components surrounded by diffuse emission. Moreover, unlike nearby spiral galaxies, whose distribution of ellipticities is flat, the LAE ellipticity distribution peaks near 1 - b/a {approx} 0.55. Thus, the population has more in common with z {approx} 3 Lyman-break galaxies than local star-forming objects.

Gronwall, Caryl; Ciardullo, Robin [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Bond, Nicholas A.; Gawiser, Eric [Physics and Astronomy Department, Rutgers University, Piscataway, NJ 08854 (United States); Altmann, Martin [University of Heidelberg, Center for Astronomy, Moenchhofstrasse 12-14, D-69120 Heidelberg (Germany); Blanc, Guillermo A. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Feldmeier, John J., E-mail: caryl@astro.psu.edu [Department of Physics and Astronomy, Youngstown State University, OH 44555 (United States)

2011-12-10

292

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

USGS Publications Warehouse

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

Martinez, P.; Senftle, F. E.

1960-01-01

293

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

SciTech Connect

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

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

1996-02-01

294

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

NASA Astrophysics Data System (ADS)

An energetic helium neutral beam is involved in the beam neutralization measurement system of alpha particles confined in a DT fusion plasma. A full size strong-focusing He+ ion source (2 A, the beam radius of 11.3 mm, the beam energy less than 20 keV). Present strong-focusing He+ ion source shows an emittance diagram separated for each beamlet of multiple apertures without phase space mixing, despite the space charge of a beamlet is asymmetric and the beam flow is non-laminar. The emittance of beamlets in the peripheral region was larger than that of center. The heat load to the plasma electrode was studied to estimate the duty factor for the ITER application.

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

2012-02-01

295

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

296

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

297

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

NASA Technical Reports Server (NTRS)

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

Bolotnikov, Aleksey; Ramsey, Brian

1999-01-01

298

Gas production due to alpha particle degradation of polyethylene and polyvinylchloride  

SciTech Connect

Alpha particle degradation experiments were performed on polyethylene (PE) and polyvinylchloride (PVC) plastic samples typical of Westinghouse Savannah River Company (WSRC) transuranic (TRU) waste. This was done to evaluate the effects of sealing TRU waste during shipment. Experiments were conducted at three temperatures using low dose rates. Predominant products from both plastics were hydrogen, carbon dioxide, and various organic species, with the addition of hydrochloric acid from PVC. In all experiments, the total pressure decreased. Irradiation at 30 and 60 C and at various dose rates caused small changes for both plastics, but at 100 C coupled thermal-radiolytic effects included discoloration of the material as well as large differences in the gas phase composition.

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

1998-07-01

299

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

NASA Astrophysics Data System (ADS)

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

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

300

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

E-print Network

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

Bacca, Sonia; Leidemann, Winfried; Orlandini, Giuseppina

2014-01-01

301

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

SciTech Connect

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

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

1995-07-01

302

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

SciTech Connect

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

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

1992-01-01

303

Ly{alpha}-EMITTING GALAXIES AT z = 2.1 IN ECDF-S: BUILDING BLOCKS OF TYPICAL PRESENT-DAY GALAXIES?  

SciTech Connect

We discovered a sample of 250 Ly{alpha} emitting (LAE) galaxies at z {approx_equal} 2.1 in an ultra-deep 3727 A narrow-band MUSYC image of the Extended Chandra Deep Field-South. The LAEs were selected to have rest-frame equivalent widths (EWs) >20 A and emission-line fluxes F{sub Ly{alpha}>}2.0 x 10{sup -17} erg cm{sup -2} s{sup -1}, after carefully subtracting the continuum contributions from narrow-band photometry. The median emission-line flux of our sample is F{sub Ly{alpha}} = 4.2 x 10{sup -17} erg cm{sup -2} s{sup -1}, corresponding to a median Ly{alpha} luminosity L{sub Ly{alpha}} = 1.3 x 10{sup 42} erg s{sup -1} at z {approx_equal} 2.1. At this flux, our sample is {>=}90% complete. Approximately 4% of the original NB-selected candidates were detected in X-rays by Chandra, and 7% were detected in the rest-frame far-UV by the Galaxy Evolution Explorer; these objects were eliminated to minimize contamination by active galactic nuclei and low-redshift galaxies. At L{sub Ly{alpha} {>=}} 1.3 x 10{sup 42} erg s{sup -1}, the EW distribution is unbiased and is represented by an exponential with scale-length 83 {+-}10 A. Above this same luminosity threshold, we find a number density of 1.5 {+-} 0.5 x 10{sup -3} Mpc{sup -3}. Neither the number density of LAEs nor the scale-length of their EW distribution show significant evolution from z {approx_equal} 3 to z {approx_equal} 2. We used the rest-frame UV luminosity to estimate a median star formation rate of 4 M{sub sun} yr{sup -1}. The median rest-frame UV slope, parameterized by the color B - R, is typical of dust-free, 0.5-1 Gyr old or moderately dusty, 300-500 Myr old population. Approximately 30% of our sample is consistent with being very young (age <100 Myr) galaxies without dust. Approximately 40% of the sample occupies the z {approx} 2 star-forming galaxy locus in the UVR two-color diagram, but the true percentage could be significantly higher taking into account photometric errors. Clustering analysis reveals that LAEs at z {approx_equal} 2.1 have r{sub 0} = 4.8 {+-} 0.9 Mpc, corresponding to a bias factor b = 1.8 {+-} 0.3. This implies that z {approx_equal} 2.1 LAEs reside in dark matter halos with median masses log(M/M{sub sun}) = 11.5{sup +0.4}{sub -0.5}, which are among the lowest mass halos yet probed at this redshift. We used the Sheth and Tormen conditional mass function to study the descendants of these LAEs and found that their typical present-day descendants are local galaxies with L* properties, like the Milky Way.

Guaita, Lucia; Padilla, Nelson; Francke, Harold [Departmento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Gawiser, Eric; Bond, Nicholas A. [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States); Gronwall, Caryl; Ciardullo, Robin; Sinawa, Shawn [Department of Astronomy and Astrophysics, Penn State University, State College, PA 16802 (United States); Feldmeier, John J. [Department of Physics and Astronomy, Youngstown State University, Youngstown, OH 44555-2001 (United States); Blanc, Guillermo A. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Virani, Shanil, E-mail: lguaita@astro.puc.c [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States)

2010-05-01

304

The assessment of particulate matter emitted from stone-crushing industry by correlating rock textures with particles generated after comminution and dispersed in air environment.  

PubMed

The generation and emission of particulate matter from abrasion industry are subjects of the pollution monitoring by multidisciplinary study involving earth sciences and engineering disciplines. This work investigates the correlation between textural properties of in situ rock with class size distribution and morphology of particles generated after rock comminution and particles emitted in the air. A special comminution-dust sampling architecture was realised. The combined use of scanning electron microscopy and particle size analyser was considered in performing digital image analysis on both crushed products and airborne particles collected onto membrane filters. The results show that the size and morphology of crushed particles are linked to the petrographic rock properties. In particular, particles with fibrous morphology are prominent in rocks showing foliated textures where elongated minerals occurred, with implication for asbestos-bearing rocks. For what concerns the airborne particles, the results show that their aerodynamic diameters are independent of the crusher operating conditions. External parameters probably intervene in the distribution of the airborne particles emission, including the dynamic air fluxes, or environmental conditions. By applying mathematical models, the morphology and size range of airborne particles following the comminution processes can be predicted, and results has implication for pollutants contamination due to particulate matters emitted by crush stone industry. PMID:23292201

Belardi, Girolamo; Vignaroli, Gianluca; Plescia, Paolo; Passeri, Luciano

2013-07-01

305

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

NASA Astrophysics Data System (ADS)

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

Amir, Haider F. Abdul; Chee, Fuei Pien

2012-09-01

306

Lyman alpha radiation in external galaxies  

NASA Technical Reports Server (NTRS)

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

Neufeld, David A.; Mckee, Christopher F.

1990-01-01

307

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

SciTech Connect

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

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

2010-01-15

308

Bremsstrahlung in alpha-Decay Reexamined  

E-print Network

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

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

2007-06-14

309

Bremsstrahlung in alpha-Decay Revisited  

E-print Network

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

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

2007-01-01

310

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

Microsoft Academic Search

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

Loran Bittman; Milton Furst; Hartmut Kallmann

1952-01-01

311

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

E-print Network

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

312

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

313

Time-dependent isospin composition of particles emitted in fission events following Ar40+Au197 at 35 MeV/u  

NASA Astrophysics Data System (ADS)

Fission fragments resulting from the fission of target-like nuclei produced in the Ar40+Au197 reaction at 35 MeV/u are measured in coincidence with the emitted light charged particles (LCPs). Comparison of the N /Z composition of the LCPs at middle and large angles in the laboratory frame shows that particles emitted at smaller angles, which contain a larger contribution from dynamical emission, are more neutron rich. A moving-source model is used to fit the energy spectra of the hydrogen isotopes. A hierarchy from proton to deuteron and triton is observed in the multiplicity ratio between the intermediate velocity source and the compound nucleus source. This ratio is sensitive to the dynamical emission at early stages of the reaction and to statistical emission lasting up to the scission point. Calculations with the improved quantum molecular dynamics (ImQMD) transport-model qualitatively support the picture that more free and bound neutrons are emitted during the early stage, showing a clear dependence of N /Z on the parametrization of the symmetry energy. The time-dependent isospin composition of the emitted particles thus may be used to probe the symmetry energy at subsaturation densities.

Wang, R. S.; Zhang, Y.; Xiao, Z. G.; Tian, J. L.; Zhang, Y. X.; Wu, Q. H.; Duan, L. M.; Jin, G. M.; Hu, R. J.; Wang, S. F.; Li, Z. Y.; Wang, H. W.; Zhang, Z.; Yi, H.; Li, H. J.; Cheng, W. J.; Huang, Y.; L, L. M.

2014-06-01

314

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

PubMed

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

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

2011-04-01

315

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

316

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

317

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

318

The effectiveness of an air cleaner in controlling droplet/aerosol particle dispersion emitted from a patient's mouth in the indoor environment of dental clinics.  

PubMed

Dental healthcare workers (DHCWs) are at high risk of occupational exposure to droplets and aerosol particles emitted from patients' mouths during treatment. We evaluated the effectiveness of an air cleaner in reducing droplet and aerosol contamination by positioning the device in four different locations in an actual dental clinic. We applied computational fluid dynamics (CFD) methods to solve the governing equations of airflow, energy and dispersion of different-sized airborne droplets/aerosol particles. In a dental clinic, we measured the supply air velocity and temperature of the ventilation system, the airflow rate and the particle removal efficiency of the air cleaner to determine the boundary conditions for the CFD simulations. Our results indicate that use of an air cleaner in a dental clinic may be an effective method for reducing DHCWs' exposure to airborne droplets and aerosol particles. Further, we found that the probability of droplet/aerosol particle removal and the direction of airflow from the cleaner are both important control measures for droplet and aerosol contamination in a dental clinic. Thus, the distance between the air cleaner and droplet/aerosol particle source as well as the relative location of the air cleaner to both the source and the DHCW are important considerations for reducing DHCWs' exposure to droplets/aerosol particles emitted from the patient's mouth during treatments. PMID:20031985

Chen, Chun; Zhao, Bin; Cui, Weilin; Dong, Lei; An, Na; Ouyang, Xiangying

2010-07-01

319

The effectiveness of an air cleaner in controlling droplet/aerosol particle dispersion emitted from a patient's mouth in the indoor environment of dental clinics  

PubMed Central

Dental healthcare workers (DHCWs) are at high risk of occupational exposure to droplets and aerosol particles emitted from patients' mouths during treatment. We evaluated the effectiveness of an air cleaner in reducing droplet and aerosol contamination by positioning the device in four different locations in an actual dental clinic. We applied computational fluid dynamics (CFD) methods to solve the governing equations of airflow, energy and dispersion of different-sized airborne droplets/aerosol particles. In a dental clinic, we measured the supply air velocity and temperature of the ventilation system, the airflow rate and the particle removal efficiency of the air cleaner to determine the boundary conditions for the CFD simulations. Our results indicate that use of an air cleaner in a dental clinic may be an effective method for reducing DHCWs' exposure to airborne droplets and aerosol particles. Further, we found that the probability of droplet/aerosol particle removal and the direction of airflow from the cleaner are both important control measures for droplet and aerosol contamination in a dental clinic. Thus, the distance between the air cleaner and droplet/aerosol particle source as well as the relative location of the air cleaner to both the source and the DHCW are important considerations for reducing DHCWs' exposure to droplets/aerosol particles emitted from the patient's mouth during treatments. PMID:20031985

Chen, Chun; Zhao, Bin; Cui, Weilin; Dong, Lei; An, Na; Ouyang, Xiangying

2010-01-01

320

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

NASA Astrophysics Data System (ADS)

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

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

321

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

322

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

323

Treatment of HER2 Positive Breast Carcinomatous Meningitis with Intrathecal Administration of ?-Particle Emitting 211At-labeled Trastuzumab?  

PubMed Central

Introduction Carcinomatous meningitis (CM) is a devastating disease characterized by the dissemination of malignant tumor cells into the subarachnoid space along the brain and spine. Systemic treatment with monoclonal antibody (mAb) trastuzumab can be effective against HER2-positive systemic breast carcinoma but like other therapies, is ineffective against CM. The goal of this study was to evaluate the therapeutic effect of ?-particle emitting 211At-labeled trastuzumab following intrathecal administration in a rat model of breast carcinoma CM. Methods Athymic rats were injected intrathecally with MCF-7/HER2-18 breast carcinoma cells through a surgically-implanted indwelling intrathecal catheter. In Experiment 1, animals received 33 or 66 Ci 211At-labeled trastuzumab, cold trastuzumab, or saline. In Experiment 2, animals were inoculated with a lower tumor burden and received 46 or 92 Ci 211At-labeled trastuzumab, or saline. In Experiment 3, animals received 28 Ci 211At-labeled trastuzumab, 30 Ci 211At-labeled TPS3.2 control mAb or saline. Histopathological analysis of the neuroaxis was performed at the end of the study. Results In Experiment 1, median survival increased from 21 days for the saline and cold trastuzumab groups to 45 and 48 days for 33 and 66 Ci 211At-labeled trastuzumab, respectively. In Experiment 2, median survival increased from 23 days for saline controls to 68 and 92 days for 46 and 92 Ci 211At-labeled trastuzumab, respectively. In Experiment 3, median survival increased from 20 days to 29 and 36 days for animals treated with 211At-labeled TPS3.2 and 211At-labeled trastuzumab, respectively. Long-term survivors were observed exclusively in the 211At-trastuzumab-treated groups. Conclusion Intrathecal 211At-labeled trastuzumab shows promise as a treatment for patients with HER2-positive breast CM. PMID:19647172

Boskovitz, Abraham; McLendon, Roger E.; Okamura, Tatsunori; Sampson, John H.; Bigner, Darell D.; Zalutsky, Michael R.

2009-01-01

324

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

SciTech Connect

The effect of average particle sizes on basic macroscopic properties and heat transfer performance of {alpha}-SiC/water nanofluids was investigated. The average particle sizes, calculated from the specific surface area of nanoparticles, were varied from 16 to 90 nm. Nanofluids with larger particles of the same material and volume concentration provide higher thermal conductivity and lower viscosity increases than those with smaller particles because of the smaller solid/liquid interfacial area of larger particles. It was also demonstrated that the viscosity of water-based nanofluids can be significantly decreased by pH of the suspension independently from the thermal conductivity. Heat transfer coefficients were measured and compared to the performance of base fluids as well as to nanofluids reported in the literature. Criteria for evaluation of the heat transfer performance of nanofluids are discussed and optimum directions in nanofluid development are suggested.

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

2010-01-01

325

Evaluation of beta partical densitometry for determination of self-absorption factors in gross alpha and gross beta radioactivity measurements on air particulate filter samples  

E-print Network

Alpha and beta particles emitted from radioactive material collected on an air filter may be significantly attenuated by the mass (thickness) of collected dust. In this study, we determined the mass or thickness of the simulated dust deposit...

Breida, Margaret A

2012-06-07

326

Advanced alpha spectrum analysis based on the fitting and covariance analysis of dependent variables  

Microsoft Academic Search

The correct handling of statistical uncertainties is crucial especially when unfolding alpha spectra that contain a low number of counts or overlapping peaks from different nuclides. For this purpose, we have developed a new spectrum analysis software package called ADAM, which performs a full covariance calculus for alpha-particle emitting radionuclides. By analyzing a large number of simulated and measured spectra,

S. Ihantola; A. Pelikan; R. Pllnen; H. Toivonen

2011-01-01

327

An alpha scintillation spectrometer  

E-print Network

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

Yates, Ralph Aaron

2012-06-07

328

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

329

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

330

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

SciTech Connect

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

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

2008-01-01

331

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

332

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

SciTech Connect

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

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

1998-12-31

333

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

E-print Network

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

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

2014-01-01

334

Development and characterization of an exposure platform suitable for physico-chemical, morphological and toxicological characterization of printer-emitted particles (PEPs).  

PubMed

An association between laser printer use and emissions of particulate matter (PM), ozone and volatile organic compounds has been reported in recent studies. However, the detailed physico-chemical, morphological and toxicological characterization of these printer-emitted particles (PEPs) and possible incorporation of engineered nanomaterials into toner formulations remain largely unknown. In this study, a printer exposure generation system suitable for the physico-chemical, morphological, and toxicological characterization of PEPs was developed and used to assess the properties of PEPs from the use of commercially available laser printers. The system consists of a glovebox type environmental chamber for uninterrupted printer operation, real-time and time-integrated particle sampling instrumentation for the size fractionation and sampling of PEPs and an exposure chamber for inhalation toxicological studies. Eleven commonly used laser printers were evaluated and ranked based on their PM emission profiles. Results show PM peak emissions are brand independent and varied between 3000 to 1?300?000?particles/cm(3), with modal diameters ranging from 49 to 208?nm, with the majority of PEPs in the nanoscale (<100?nm) size. Furthermore, it was shown that PEPs can be affected by certain operational parameters and printing conditions. The release of nanoscale particles from a nano-enabled product (printer toner) raises questions about health implications to users. The presented PEGS platform will help in assessing the toxicological profile of PEPs and the link to the physico-chemical and morphological properties of emitted PM and toner formulations. PMID:24862974

Pirela, Sandra V; Pyrgiotakis, Georgios; Bello, Dhimiter; Thomas, Treye; Castranova, Vincent; Demokritou, Philip

2014-06-01

335

High-energy resolution alpha spectrometry using cryogenic detectors.  

PubMed

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

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

2006-01-01

336

Influence of ozone concentration and temperature on ultra-fine particle and gaseous volatile organic compound formations generated during the ozone-initiated reactions with emitted terpenes from a car air freshener  

Microsoft Academic Search

Experiments were conducted to identify the emissions from the car air freshener and to identify the formation of ultra-fine particles and secondary gaseous compounds during the ozone-initiated oxidations with emitted volatile organic compounds (VOCs). The identified primary constituents emitted from the car air freshener in this study were ?-pinene, ?-pinene, p-cymene, and limonene. Formation of ultra-fine particles (4.4160nm) was observed

Rheo B. Lamorena; Woojin Lee

2008-01-01

337

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

Microsoft Academic Search

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

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

2001-01-01

338

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

E-print Network

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

Santhosh, K P; Priyanka, B

2014-01-01

339

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

SciTech Connect

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

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

1983-01-01

340

Semiconductor polycrystalline alpha detectors  

NASA Astrophysics Data System (ADS)

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

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

2006-08-01

341

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

SciTech Connect

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

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

2011-01-01

342

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

PubMed

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

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

2008-10-01

343

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

344

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

345

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

PubMed

Proof of principle experiments of neutral helium beam production for alpha particle diagnostics was carried out on a test stand. Negative helium ions were produced in the Li charge exchange cell, in which stable and long time operation was possible. He(-) beam was accelerated to 157 keV. Finally, He(0) beam was successfully produced after the flight in the drift-tube through the auto-electron-detachment process from He(-) to He(0). A neutral beam detector using a pyroelectric device was also developed to measure He(0) beam intensity. The metastable component in the neutral helium beam was found to be less than 2%. PMID:22380272

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

2012-02-01

346

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

SciTech Connect

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

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

2008-10-15

347

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

348

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

349

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

Microsoft Academic Search

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

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

1967-01-01

350

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

E-print Network

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

G. K. Nie

2011-06-19

351

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

PubMed Central

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

2012-01-01

352

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

353

Comparison of PHITS, GEANT4, and HIBRAC simulations of depth-dependent yields of ?+-emitting nuclei during therapeutic particle irradiation to measured data  

NASA Astrophysics Data System (ADS)

For quality assurance in particle therapy, a non-invasive, in vivo range verification is highly desired. Particle therapy positron-emission-tomography (PT-PET) is the only clinically proven method up to now for this purpose. It makes use of the ?+-activity produced during the irradiation by the nuclear fragmentation processes between the therapeutic beam and the irradiated tissue. Since a direct comparison of ?+-activity and dose is not feasible, a simulation of the expected ?+-activity distribution is required. For this reason it is essential to have a quantitatively reliable code for the simulation of the yields of the ?+-emitting nuclei at every position of the beam path. In this paper results of the three-dimensional Monte-Carlo simulation codes PHITS, GEANT4, and the one-dimensional deterministic simulation code HIBRAC are compared to measurements of the yields of the most abundant ?+-emitting nuclei for carbon, lithium, helium, and proton beams. In general, PHITS underestimates the yields of positron-emitters. With GEANT4 the overall most accurate results are obtained. HIBRAC and GEANT4 provide comparable results for carbon and proton beams. HIBRAC is considered as a good candidate for the implementation to clinical routine PT-PET.

Rohling, Heide; Sihver, Lembit; Priegnitz, Marlen; Enghardt, Wolfgang; Fiedler, Fine

2013-09-01

354

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.

355

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

356

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 37C. 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; Pachnerov-Brabcov, Katerina; Czub, Joanna; Braziewicz, Janusz; Nievaart, Sander; Wojcik, Andrzej

2012-09-01

357

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

358

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

359

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

360

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

NASA Astrophysics Data System (ADS)

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

Norrby, Markus

2013-04-01

361

Health effects models for nuclear power plant accident consequence analysis. Modification of models resulting from addition of effects of exposure to alpha-emitting radionuclides: Revision 1, Part 2, Scientific bases for health effects models, Addendum 2  

SciTech Connect

The Nuclear Regulatory Commission (NRC) has sponsored several studies to identify and quantify, through the use of models, the potential health effects of accidental releases of radionuclides from nuclear power plants. The Reactor Safety Study provided the basis for most of the earlier estimates related to these health effects. Subsequent efforts by NRC-supported groups resulted in improved health effects models that were published in the report entitled {open_quotes}Health Effects Models for Nuclear Power Plant Consequence Analysis{close_quotes}, NUREG/CR-4214, 1985 and revised further in the 1989 report NUREG/CR-4214, Rev. 1, Part 2. The health effects models presented in the 1989 NUREG/CR-4214 report were developed for exposure to low-linear energy transfer (LET) (beta and gamma) radiation based on the best scientific information available at that time. Since the 1989 report was published, two addenda to that report have been prepared to (1) incorporate other scientific information related to low-LET health effects models and (2) extend the models to consider the possible health consequences of the addition of alpha-emitting radionuclides to the exposure source term. The first addendum report, entitled {open_quotes}Health Effects Models for Nuclear Power Plant Accident Consequence Analysis, Modifications of Models Resulting from Recent Reports on Health Effects of Ionizing Radiation, Low LET Radiation, Part 2: Scientific Bases for Health Effects Models,{close_quotes} was published in 1991 as NUREG/CR-4214, Rev. 1, Part 2, Addendum 1. This second addendum addresses the possibility that some fraction of the accident source term from an operating nuclear power plant comprises alpha-emitting radionuclides. Consideration of chronic high-LET exposure from alpha radiation as well as acute and chronic exposure to low-LET beta and gamma radiations is a reasonable extension of the health effects model.

Abrahamson, S. [Wisconsin Univ., Madison, WI (United States); Bender, M.A. [Brookhaven National Lab., Upton, NY (United States); Boecker, B.B.; Scott, B.R. [Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States). Inhalation Toxicology Research Inst.; Gilbert, E.S. [Pacific Northwest Lab., Richland, WA (United States)

1993-05-01

362

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

363

Gas-phase and particle-phase organic compounds emitted from motor vehicle traffic in a Los Angeles roadway tunnel  

Microsoft Academic Search

The emission rates for 221 vapor-phase, semivolatile, and particle-phase organic compounds from motor vehicles plus fine particulate matter mass and some inorganic particle-phase species are calculated based on measurements made inside and outside a Los Angeles roadway tunnel in 1993. These emission rates are calculated based on tunnel dilution rates or air circulation. The results show carbon monoxide emissions rates

Matthew P. Fraser; Glen R. Cass; Bernd R. T. Simoneit

1998-01-01

364

Development of an alpha/beta/gamma detector for radiation monitoring  

NASA Astrophysics Data System (ADS)

For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd2SiO5 (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.

Yamamoto, Seiichi; Hatazawa, Jun

2011-11-01

365

Development of an alpha/beta/gamma detector for radiation monitoring  

SciTech Connect

For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd{sub 2}SiO{sub 5} (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.

Yamamoto, Seiichi [Kobe City College of Technology, 8-3, Gakuen-Higashi-machi, Nishi-ku, Kobe, 651-2194 (Japan); Hatazawa, Jun [Osaka University of Graduate School of Medicine, 2-2, Yamadaoka, Suita-shi, Osaka, 565-0871 (Japan)

2011-11-15

366

Advanced simulation code for alpha spectrometry  

E-print Network

A Monte Carlo code, known as AASI, is developed for simulating energy spectra in alpha spectrometry. The code documented here is a comprehensive package where all the major processes affecting the spectrum are included. A unique feature of the code is its ability to take into account coincidences between the particles emitted from the source. Simulations and measurements highlight the importance of coincidences in high-resolution alpha spectrometry. To show the validity of the simulated results, comparisons with measurements and other simulation codes are presented.

T. Siiskonen; R. Pollanen

2005-05-04

367

Conversion efficiency and spectral broadening of the K-{alpha} line emitted from planar titanium targets irradiated with ultra-short laser pulses of high intensity  

SciTech Connect

A study of the conversion efficiency and line shape of the K-{alpha} x-ray line radiation from a planar titanium target irradiated by an ultra-short laser pulse is performed. The conversion efficiency and spectral broadening are studied as a function of laser intensity (5 x 10{sup 16}-10{sup 18} W cm{sup -2}), laser pulse duration (45 fs-800 fs), and laser fluence (2 x 10{sup 3}-4.2 x 10{sup 4} J cm{sup -2}). The K-{alpha}{sub 1} line (4510 eV) is observed to be broadened (up to {approx}9 eV), predominantly towards the higher energy side and strongly depends on the laser fluence rather than on laser intensity. The reason for the spectral broadening is attributed to K-{alpha} emission in warm dense plasma. The role of hot electrons and direct laser heating on spectral broadening is outlined. In addition to this, our observations indicates that the presence of pre-plasma strongly contribute to the observed broadening through the inner-shell transitions in multiply charged titanium ions in the pre-plasma. The appropriate laser irradiation parameters to achieve high conversion efficiency and minimum spectral width of the K-{alpha} radiation are identified. The study is important, since the control of the spectral profile is of general interest for diffraction or scattering experiments in view of its potential in increasing temporal resolution.

Arora, V.; Singhal, H.; Naik, P. A.; Gupta, P. D. [Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

2011-10-15

368

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

PubMed

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

Ishikawa, Y; Wada, I; Fukumoto, M

2001-01-01

369

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

SciTech Connect

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

Bae, Y.K.

1982-08-01

370

A comparative study of the number and mass of fine particles emitted with diesel fuel and marine gas oil (MGO)  

NASA Astrophysics Data System (ADS)

The current investigation reports on diesel particulate matter emissions, with special interest in fine particles from the combustion of two base fuels. The base fuels selected were diesel fuel and marine gas oil (MGO). The experiments were conducted with a four-stroke, six-cylinder, direct injection diesel engine. The results showed that the fine particle number emissions measured by both SMPS and ELPI were higher with MGO compared to diesel fuel. It was observed that the fine particle number emissions with the two base fuels were quantitatively different but qualitatively similar. The gravimetric (mass basis) measurement also showed higher total particulate matter (TPM) emissions with the MGO. The smoke emissions, which were part of TPM, were also higher for the MGO. No significant changes in the mass flow rate of fuel and the brake-specific fuel consumption (BSFC) were observed between the two base fuels.

Nabi, Md. Nurun; Brown, Richard J.; Ristovski, Zoran; Hustad, Johan Einar

2012-09-01

371

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

PubMed

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

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

2009-08-01

372

Use of neutralized knock-on ion fluxes foralpha-particle confinement studies  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

373

Channeling of Fusion Alpha-Particle Power Using Minority Ion Catalysis  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

374

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

375

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

PubMed

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

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

2009-09-15

376

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

377

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

SciTech Connect

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

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

2008-01-01

378

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

379

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

380

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

PubMed

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

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

2013-10-01

381

GROSS ALPHA RADIUM REGULATION  

EPA Science Inventory

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

382

Final Scientific/Technical Report, DE-FG02-08ER41561: "Lyman-alpha Emitting Galaxies at 2  

SciTech Connect

Lyman Alpha Emitting (LAE) galaxies are a powerful tracer of large scale structure, making them an excellent probe of baryonic acoustic oscillations, which constrain the expansion history of the universe and hence the nature of the dark energy. The HETDEX Stage III dark energy experiment will utilize LAEs for this purpose, and they are under consideration as a tracer of structure for Stage IV ground- and space-based dark energy missions. Our successful investigation of LAEs at z=2.1 and z=3.1 now provides the best information on the number density and clustering bias of these galaxies over the redshift range that HETDEX will study. Connecting these star-forming galaxies to their host dark matter halos represents a major increase in scientific understanding, as we can now proceed with confidence in studying the spatial distribution of significantly larger samples. Our data also provided an empirical test of the Lyman Alpha Tomography technique, which has proven effective and can now be used to design future experiments to probe dark energy and dark matter properties.

Eric Gawiser

2010-03-19

383

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

384

EVOLUTION IN THE CONTINUUM MORPHOLOGICAL PROPERTIES OF Ly{alpha}-EMITTING GALAXIES FROM z = 3.1 TO z = 2.1  

SciTech Connect

We present a rest-frame ultraviolet morphological analysis of 108 z {approx_equal} 2.1 Ly{alpha} emitters (LAEs) in the Extended Chandra Deep Field South and compare it to a similar sample of 171 LAEs at z {approx_equal} 3.1. Using Hubble Space Telescope images from the Galaxy Evolution from Morphology and SEDs survey, Great Observatories Origins Deep Survey, and Hubble Ultradeep Field, we measure size and photometric component distributions, where photometric components are defined as distinct clumps of UV-continuum emission. At both redshifts, >80% of LAEs have observed half-light radii <2 kpc, but the median half-light radius rises from 0.95 {+-} 0.04 kpc at z 3.1 to 1.41 {+-} 0.14 kpc at z = 2.1. A similar evolution is seen in the sizes of individual rest-UV components, but there is no evidence for evolution in the number of multi-component systems. In the z = 2.1 sample, we see clear correlations between the size of an LAE and other physical properties derived from its spectral energy distribution (SED). LAEs are found to be larger for galaxies with higher stellar mass, star formation rate, and dust obscuration, but there is no evidence for a trend between equivalent width and half-light radius at either redshift. The presence of these correlations suggests that a wide range of objects are being selected by LAE surveys at z {approx} 2, including a significant fraction of objects for which a massive and moderately extended population of old stars underlies the young starburst giving rise to the Ly{alpha} emission.

Bond, Nicholas A.; Gawiser, Eric [Physics and Astronomy Department, Rutgers University, Piscataway, NJ 08854-8019 (United States); Guaita, Lucia [Department of Astronomy, Stockholm University, AlbaNova Science Center, SE-106 91 Stockholm (Sweden); Padilla, Nelson [Departmento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Gronwall, Caryl; Ciardullo, Robin [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Lai, Kamson [University of California Observatoires/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)

2012-07-10

385

A contribution to improvement of the nuclear data concerning alpha decay of 235U  

Microsoft Academic Search

Compared to other alpha-particle emitting nuclides, for those with long half-lives (T1\\/2>106 years), there is generally some inconsistency and inaccuracy in the associated nuclear data. However, these radionuclides play a major role in modern society and, for a number of reasons, are the subject of widespread interest. The study of their alpha decay, which is more difficult than in the

Fatima Dayras; Nicolas Chauvin

2004-01-01

386

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

E-print Network

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

Yu, K.N.

387

The solar-exoplanet-host-star connection: measurements, reconstruction, and estimates of the UV, Lyman-alpha, and EUV radiation emitted by exoplanet host stars  

NASA Astrophysics Data System (ADS)

One of the important ways in which host stars influence their exoplanets is through photochemistry in their atmospheres. For example, the photodissociation of such important molecules in exoplanet atmospheres as H2O, CO2, and CH4 is primarily controlled by Lymanalpha and FUV radiation from the host stars. Photochemistry of oxygen and ozone is controlled by NUV radiation. EUV radiation photoionizes H and other atoms, heats the outer atmospheres, and thereby drives mass loss from exoplanets. Photodissociation of H2O and CO2 liberates oxygen without the need for life forms and thus complicates the use of oxygen and ozone as biosignatures. The COS instrument on HST has now obtained UV spectra of a number of M dwarfs host stars. The Lyman-alpha line, which is important for G stars but completely dominates the UV emission of M dwarfs, is attenuated by interstellar absorption. I will present techniques for reconstructing or estimating the stellar emission in this line. The EUV emission can be estimated by comparison with Lymanalpha and other emission lines. These recent developments now make it feasible to evaluate the radiation received by exoplanets and to compute realistic models of the chemistry of exoplanet atmospheres.

Linsky, J.

2014-03-01

388

Apparatus for detecting alpha radiation in difficult access areas  

DOEpatents

An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure is disclosed. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure. A voltage source is connected between the indicator means and the electrically conductive enclosure for creating an electric field between the electrically conductive expandable electrode and the enclosure. 4 figs.

Steadman, P.; MacArthur, D.W.

1997-09-02

389

Apparatus for detecting alpha radiation in difficult access areas  

DOEpatents

An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure. A voltage source is connected between the indicator means and the electrically conductive enclosure for creating an electric field between the electrically conductive expandable electrode and the enclosure.

Steadman, Peter (Santa Fe, NM); MacArthur, Duncan W. (Los Alamos, NM)

1997-09-02

390

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

NASA Technical Reports Server (NTRS)

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

Combi, Michael R.; Smyth, William H.

1988-01-01

391

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

NASA Astrophysics Data System (ADS)

When confluent cultures of mammalian cells are irradiated with very low fluences of alpha particles whereby only occasional cells receive any radiation exposure, genetic changes are observed in the non-irradiated ("bystander") cells. Upregulation of the p53 damage-response pathway as well as activation of proteins in the MAPK family occurred in bystander cells; p53 was phosphorylated on the serine 15 residue suggesting that the upregulation of p53 was a consequence of DNA damage. Damage signals were transmitted to bystander cells through gap junctions, as confirmed by the use of genetically manipulated cells including connexin43 knockouts. Expression of connexin43 was markedly enhanced by irradiation. A moderate bystander effect was observed for specific gene mutations and chromosomal aberrations. This effect was markedly enhanced in cells defective in the non-homologous end joining DNA repair pathway. Finally, an upregulation of oxidative metabolism occurred in bystander cells; the increased levels of reactive oxygen species appeared to be derived from flavine-containing oxidase enzymes. We hypothesize that genetic effects observed in non-irradiated bystander cells are a consequence of oxidative base damage; >90% of mutations in bystander cells were point mutations. When bystander cells cannot repair DNA double strand breaks, they become much more sensitive to the induction of chromosomal aberrations and mutations, the latter consisting primarily of deletion mutants. While we propose that the genetic effects occurring in bystander cells are a consequence of oxidative stress, the nature of the signal that initiates this process remains to be determined.

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

2005-02-01

392

Cell Cycle Checkpoint Proteins p21 and Hus1 Regulating Intercellular Signaling Induced By Alpha Particle Irradiation  

NASA Astrophysics Data System (ADS)

In recent years, the attentions for radiation induced bystander effects (RIBE) have been paid on the intercellular signaling events connecting the irradiated and non-irradiated cells. p21 is a member of the Cip/Kip family and plays essential roles in cell cycle progression arrest after cellular irradiation. DNA damage checkpoint protein Hus1 is a member of the Rad9-Rad1-Hus1 complex and functions as scaffold at the damage sites to facilitate the activation of downstream effectors. Using the medium trasfer method and the cells of MEF, MEF (p21-/-), MEF (p21-/-Hus1-/-) as either medium donor or receptor cells, it was found that with 5cGy alpha particle irradiation, the bystander cells showed a significant induction of -H2AX for normal MEFs (p0.05). However, the absence of p21 resulted in deficiency in inducing bystander effects. Further results indicated p21 affected the intercellular DNA damage signaling mainly through disrupting the production or release of the damage signals from irradiated cells. When Hus1 and p21 were both knocked out, an obvious induction of -H2AX recurred in bystander cells and the induction of -H2AX was GJIC (gap junction-mediated intercellular communication) dependent, indicating the interrelationship between p21 and Hus1 regulated the production and relay of DNA damage signals from irradiated cells to non-irradiated bystander cells.

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

393

A single photon emitted by a single particle in free space vacuum modes and its resonant interaction with two- and three-level absorbers  

E-print Network

We consider the time-delayed coincidence counting of two photons emitted in a cascade by a single particle (atom, molecule, nucleus, etc). The time-dependence of the probability amplitude of the second photon in the cascade has a sharply rising leading edge due to the detection of the first photon, as results from causality. If a macroscopic ensemble of resonant two-level absorbers is placed in the path of the second photon between the radiation source and the detector, the photon absorption does not follow Beer's law due to the time-asymmetric shape of the photon. For very short delay times almost no absorption takes place, even in an optically dense medium. We analyze the propagation of such a second photon in a thick resonant three-level absorber if a narrow electromagnetically induced transparency (EIT) window is present at the center of the absorption line. It is shown that the EIT medium can change the asymmetric time dependence of the photon probability amplitude to a bell shape (EIT filtering). This bell-shaped photon interacts much more efficiently with an other ensemble of two-level absorbers chosen, for example, to store this photon and the information it carries.

R. N. Shakhmuratov; J. Odeurs; Paul Mandel

2006-07-12

394

SPECTRAL ENERGY DISTRIBUTION FITTING WITH MARKOV CHAIN MONTE CARLO: METHODOLOGY AND APPLICATION TO z = 3.1 Ly{alpha}-EMITTING GALAXIES  

SciTech Connect

We present GalMC, a Markov Chain Monte Carlo (MCMC) algorithm designed to fit the spectral energy distributions (SEDs) of galaxies to infer physical properties such as age, stellar mass, dust reddening, metallicity, redshift, and star formation rate. We describe the features of the code and the extensive tests conducted to ensure that our procedure leads to unbiased parameter estimation and accurate evaluation of uncertainties. We compare its performance to grid-based algorithms, showing that the efficiency in CPU time is {approx}100 times better for MCMC for a three-dimensional parameter space and increasing with the number of dimensions. We use GalMC to fit the stacked SEDs of two samples of Lyman alpha emitters (LAEs) at redshift z = 3.1. Our fit reveals that the typical LAE detected in the IRAC 3.6 {mu}m band has age = 0.67 [0.37-1.81] Gyr and stellar mass = 3.2 [2.5-4.2] x 10{sup 9} M{sub sun}, while the typical LAE not detected at 3.6 {mu}m has age = 0.06 [0.01-0.2] Gyr and stellar mass = 2 [1.1-3.4] x 10{sup 8} M{sub sun}. The SEDs of both stacks are consistent with the absence of dust. The data do not significantly prefer exponential with respect to constant star formation history. The stellar populations of these two samples are consistent with the previous study by Lai et al., with some differences due to the improved modeling of the stellar populations. A constraint on the metallicity of z = 3.1 LAEs from broadband photometry, requiring Z < Z{sub sun} at 95% confidence, is found here for the first time.

Acquaviva, Viviana; Gawiser, Eric [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States); Guaita, Lucia [Departimento de Astronomia y Astrofisica, Universidad Catolica de Chile, Santiago (Chile)

2011-08-20

395

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

396

Sequential Cytarabine and Alpha-Particle Immunotherapy with Bismuth-213-Lintuzumab (HuM195) for Acute Myeloid Leukemia  

PubMed Central

Purpose Lintuzumab (HuM195), a humanized anti-CD33 antibody, targets myeloid leukemia cells and has modest single-agent activity against acute myeloid leukemia (AML). To increase the antibodys potency without the nonspecific cytotoxicity associated with ?-emitters, the ? particle-emitting radionuclide bismuth-213 (213Bi) was conjugated to lintuzumab. This phase I/II trial was conducted to determine the maximum tolerated dose (MTD) and antileukemic effects of 213Bi-lintuzumab, the first targeted ?-emitter, after partially cytoreductive chemotherapy. Experimental Design Thirty-one patients with newly diagnosed (n = 13) or relapsed/refractory (n = 18) AML (median age, 67 years; range, 3780) were treated with cytarabine 200 mg/m2/day for 5 days followed by 213Bi-lintuzumab 18.546.25 MBq/kg. Results The MTD of 213Bi-lintuzumab was 37 MB/kg; myelosuppression lasting > 35 days was dose-limiting. Extramedullary toxicities were primarily limited to ? grade 2 events, including infusion-related reactions. Transient grade 3/4 liver function abnormalities were seen in 5 patients (16%). Treatment-related deaths occurred in 2 of 21 patients (10%) who received the MTD. Significant reductions in marrow blasts were seen at all dose levels. The median response duration was 6 months (range, 212). Biodistribution and pharmacokinetic studies suggested that saturation of available CD33 sites by 213Bi-lintuzumab was achieved after partial cytoreduction with cytarabine. Conclusions Sequential administration of cytarabine and 213Bi-lintuzumab is tolerable and can produce remissions in patients with AML. PMID:20858843

Rosenblat, Todd L.; McDevitt, Michael R.; Mulford, Deborah A.; Pandit-Taskar, Neeta; Divgi, Chaitanya R.; Panageas, Katherine S.; Heaney, Mark L.; Chanel, Suzanne; Morgenstern, Alfred; Sgouros, George; Larson, Steven M.; Scheinberg, David A.; Jurcic, Joseph G.

2010-01-01

397

Fractionated Therapy of HER2-Expressing Breast and Ovarian Cancer Xenografts in Mice with Targeted Alpha Emitting 227Th-DOTA-p-benzyl-trastuzumab  

PubMed Central

Background The aim of this study was to investigate therapeutic efficacy and normal tissue toxicity of single dosage and fractionated targeted alpha therapy (TAT) in mice with HER2-expressing breast and ovarian cancer xenografts using the low dose rate radioimmunoconjugate 227Th-DOTA-p-benzyl-trastuzumab. Methodology/Principal Findings Nude mice carrying HER2-overexpressing subcutaneous SKOV-3 or SKBR-3 xenografts were treated with 1000 kBq/kg 227Th-trastuzumab as single injection or four injections of 250 kBq/kg with intervals of 45 days, 2 weeks, or 4 weeks. Control animals were treated with normal saline or unlabeled trastuzumab. In SKOV-3 xenografts tumor growth to 10-fold size was delayed (p<0.01) and survival with tumor diameter less than 16 mm was prolonged (p<0.05) in all TAT groups compared to the control groups. No statistically significant differences were seen among the treated groups. In SKBR-3 xenografts tumor growth to 10-fold size was delayed in the single injection and 45 days interval groups (p<0.001) and all except the 4 weeks interval TAT group showed improved survival to the control groups (p<0.05). Toxicity was assessed by blood cell counts, clinical chemistry measurements and body weight. Transient reduction in white blood cells was seen for the single injection and 45 days interval groups (p<0.05). No significant changes were seen in red blood cells, platelets or clinical chemistry parameters. Survival without life threatening loss of body weight was significantly prolonged in 4 weeks interval group compared to single injection group (p<0.05) for SKOV-3 animals and in 2 weeks interval group compared with the 45 days interval groups (p<0.05) for SKBR-3 animals. Conclusions/Significance The same concentration of radioactivity split into several fractions may improve toxicity of 227Th-radioimmunotherapy while the therapeutic effect is maintained. Thus, it might be possible to increase the cumulative absorbed radiation dose to tumor with acceptable toxicity by fractionation of the dosage. PMID:22879947

Heyerdahl, Helen; Abbas, Nasir; Brevik, Ellen Mengshoel; Mollatt, Camilla; Dahle, Jostein

2012-01-01

398

Clinical Experience with ?-ParticleEmitting 211At: Treatment of Recurrent Brain Tumor Patients with 211At-Labeled Chimeric Antitenascin Monoclonal Antibody 81C6  

PubMed Central

?-Particleemitting radionuclides, such as 211At, with a 7.2-h half-life, may be optimally suited for the molecularly targeted radiotherapy of strategically sensitive tumor sites, such as those in the central nervous system. Because of the much shorter range and more potent cytotoxicity of ?-particles than of ?-particles, 211At-labeled agents may be ideal for the eradication of tumor cells remaining after surgical debulking of malignant brain tumors. The main goal of this study was to investigate the feasibility and safety of this approach in patients with recurrent malignant brain tumors. Methods Chimeric antitenascin monoclonal antibody 81C6 (ch81C6) (10 mg) was labeled with 71347 MBq of 211At by use of N-succinimidyl 3-[211At]astatobenzoate. Eighteen patients were treated with 211At-labeled ch81C6 (211At-ch81C6) administered into a surgically created resection cavity (SCRC) and then with salvage chemotherapy. Serial ?-camera imaging and blood sampling over 24 h were performed. Results A total of 96.7% 3.6% (mean SD) of 211At decays occurred in the SCRC, and the mean blood-pool percentage injected dose was ?0.3. No patient experienced dose-limiting toxicity, and the maximum tolerated dose was not identified. Six patients experienced grade 2 neurotoxicity within 6 wk of 211At-ch81C6 administration; this neurotoxicity resolved fully in all but 1 patient. No toxicities of grade 3 or higher were attributable to the treatment. No patient required repeat surgery for radionecrosis. The median survival times for all patients, those with glioblastoma multiforme, and those with anaplastic astrocytoma or oligodendroglioma were 54, 52, and 116 wk, respectively. Conclusion This study provides proof of concept for regional targeted radiotherapy with 211At-labeled molecules in oncology. Specifically, the regional administration of 211At-ch81C6 is feasible, safe, and associated with a promising antitumor benefit in patients with malignant central nervous system tumors. PMID:18077533

Zalutsky, Michael R.; Reardon, David A.; Akabani, Gamal; Coleman, R. Edward; Friedman, Allan H.; Friedman, Henry S.; McLendon, Roger E.; Wong, Terence Z.; Bigner, Darell D.

2010-01-01

399

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

NASA Astrophysics Data System (ADS)

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

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

1985-08-01

400

Observation of alpha particle loss from JET plasmas during ion cyclotron resonance frequency heating using a thin foil Faraday cup detector array  

SciTech Connect

The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of {approx}2 MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential.

Darrow, D. S. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Cecil, F. E. [Physics Department, Colorado School of Mines, Golden, Colorado 80401 (United States); Kiptily, V.; Fullard, K.; Horton, A. [Culham Centre for Fusion Energy, Euratom/CCFE Fusion Assoc., Abingdon, Oxon OX14 3DB (United Kingdom); Murari, A. [Consorzio RFX-Associazione EURATOM ENEA per la Fusione, I-35127 Padova (Italy); Collaboration: JET EFDA Contributors

2010-10-15

401

Observation of alpha particle loss from JET plasmas during ion cyclotron resonance frequency heating using a thin foil Faraday cup detector array.  

PubMed

The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of ? 2?MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential. PMID:21058457

Darrow, D S; Cecil, F E; Kiptily, V; Fullard, K; Horton, A; Murari, A

2010-10-01

402

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

Microsoft Academic Search

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

E. Dobreva; N. Nenoff; B. Zhuikov

1981-01-01

403

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

SciTech Connect

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

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

2011-02-15