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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

Bremsstrahlung in {alpha} Decay of {sup 210}Po: Do {alpha} Particles Emit Photons in Tunneling?  

SciTech Connect

Emission probability of bremsstrahlung in the {alpha} decay of {sup 210}Po was measured in {alpha} -{gamma} coincidence measurements with Si and Ge detectors. It was found that the bremsstrahlung yields are much smaller than those predicted by a Coulomb acceleration model, in which {gamma} rays are emitted during acceleration outside the barrier. This suggests that the radiation amplitude in the barrier cannot be neglected, and the discussion based on a quasiclassical approach is given. {copyright} {ital 1997} {ital The American Physical Society}

Kasagi, J.; Yamazaki, H.; Kasajima, N.; Ohtsuki, T.; Yuki, H. [Laboratory of Nuclear Science, Tohoku University, Mikamine, Taihaku, Sendai 982 (Japan)

1997-07-01

3

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

2007-10-13

4

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

PubMed

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

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

2005-06-29

5

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

PubMed

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

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

6

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.

Lehnert, B E; Goodwin, E H

1997-01-01

7

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

8

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

9

Radioimmunotherapy with alpha-emitting nuclides  

Microsoft Academic Search

. This review discusses the application of alpha particle-emitting radionuclides in targeted radioimmunotherapy. It will outline\\u000a the production and chemistry of astatine-211, bismuth-212, lead-212, actinium-225, bismuth-213, fermium-255, radium-223 and\\u000a terbium-149, which at present are the most promising alpha-emitting isotopes available for human clinical use. The selective\\u000a cytotoxicity offered by alpha particle-emitting radioimmunoconstructs is due to the high linear energy transfer

Michael R. McDevitt; George Sgouros; Ronald D. Finn; John L. Humm; Joseph G. Jurcic; Steven M. Larson; David A. Scheinberg

1998-01-01

10

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

PubMed

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

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

2013-05-28

11

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

SciTech Connect

Anti-Tac, a monoclonal antibody directed to the human interleukin 2 (IL-2) receptor, has been successfully conjugated to the alpha-particle-emitting radionuclide bismuth-212 by use of a bifunctional ligand, the isobutylcarboxycarbonic anhydride of diethylenetriaminepentaacetic acid. The physical properties of 212Bi are appropriate for radioimmunotherapy in that it has a short half-life, deposits its high energy over a short distance, and can be obtained in large quantities from a radium generator. Antibody specific activities of 1-40 microCi/microgram (1 Ci = 37 GBq) were achieved. Specificity of the 212Bi-labeled anti-Tac was demonstrated for the IL-2 receptor-positive adult T-cell leukemia line HUT-102B2 by protein synthesis inhibition and clonogenic assays. Activity levels of 0.5 microCi or the equivalent of 12 rad/ml of alpha radiation targeted by anti-Tac eliminated greater than 98% the proliferative capabilities of HUT-102B2 cells with more modest effects on IL-2 receptor-negative cell lines. Specific cytotoxicity was blocked by excess unlabeled anti-Tac but not by human IgG. In addition, an irrelevant control monoclonal antibody of the same isotype labeled with 212Bi was unable to target alpha radiation to cell lines. Therefore, 212Bi-labeled anti-Tac is a potentially effective and specific immunocytotoxic reagent for the elimination of IL-2 receptor-positive cells. These experiments thus provide the scientific basis for use of alpha-particle-emitting radionuclides in immunotherapy.

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

1986-01-01

12

Temporal change in microdosimetry to bone marrow and stromal progenitor cells from alpha-particle-emitting radionuclides incorporated in bone.  

PubMed

The microdistributions of the alpha-particle-emitting bone surface-seeking radionuclides (239)Pu, (241)Am and (233)U in the mouse femoral shaft have been studied using computer-based image analysis of neutron-induced and alpha-particle track autoradiographs, prepared from femora of CBA/H mice which had been injected with 40 kBq kg(-1) of radionuclide (as citrate solution) at times from 1 to 448 days previously. Employing dosimetric methods, radiation dose rates and cumulative radiation doses to regions of the bone marrow thought to contain hemopoietic and stromal progenitor cells susceptible to neoplastic transformation to leukemia and osteosarcomas have been calculated. It has been shown that the three radionuclides differ in their relative deposition on the bone surfaces, and that patterns of changing redistribution with time are also varied. For stromal progenitor cells, which are thought to be targets for induction of osteosarcoma and are found in proximity to the bone surfaces, cumulative doses showed the trend (239)Pu > (241)Am > (233)U, correlating well with incidences of osteosarcoma observed in mice. Cumulative doses to the primitive hemopoietic stem cells, concentrated in the central marrow and thought to be susceptible to neoplastic transformation to myeloid leukemia, were considerably lower and also showed the trend plutonium > americium > uranium. PMID:10564934

Austin, A L; Ellender, M; Haines, J W; Harrison, J D; Lord, B I

1999-12-01

13

1-15 MeV proton and alpha particle radiation effects on GaAs quantum well light emitting diodes [and QWIPs  

Microsoft Academic Search

Permanent radiation damage was investigated in GaAs quantum well light emitting diodes (QW LEDs) due to protons and alpha particles in the 1-15 MeV energy range. At room temperature, these devices under forward bias emit infrared radiation at 980 mm. Current-voltage (I-V) and light emission characteristics of these devices were studied as a function of fluence and energy of protons

S. M. Khanna; D. Estan; H. C. Liu; M. Gao; M. Buchanan; A. J. SpringThorpe

2000-01-01

14

Production of fast. cap alpha. particles in /sup 20/Ne+ /sup 197/Au collisions studied by counting the simultaneously emitted neutrons  

SciTech Connect

The number of neutrons emitted in heavy-ion reactions is counted eventwise with high efficiency in a 4..pi.. neutron counting device. This number is taken as a measure of the energy converted into internal excitation of the heavy reaction residues produced in /sup 20/Ne+ /sup 197/Au collisions at 220, 290, and 400 MeV. Forward emitted ..cap alpha.. particles are found preferentially with either a low number of coincident neutrons or a high neutron number. The former component is identified with ..cap alpha.. particles produced by projectile breakup, the latter with nonequilibrium emission of ..cap alpha.. particles. The inclusive cross section can be decomposed into the contributions of these two processes, and separate energy distributions and excitation functions are given. The nonequilibrium component is compatible with a massive-transfer picture of the responsible process.

Fuchs, H.; Buergel, M.; Homeyer, H.; Ingold, G.; Jahnke, U.; Thoma, G.

1985-02-01

15

Optimizing the Delivery of Short-Lived Alpha Particle-Emitting Isotopes to Solid Tumors  

SciTech Connect

The underlying hypothesis of this project was that optimal alpha emitter-based radioimmunotherapy (RAIT) could be achieved by pairing the physical half-life of the radioisotope to the biological half-life of the targeting vehicle. The project had two specific aims. The first aim was to create and optimize the therapeutic efficacy of 211At-SAPS-C6.5 diabody conjugates. The second aim was to develop bispecific-targeting strategies that increase the specificity and efficacy of alpha-emitter-based RAIT. In the performance of the first aim, we created 211At-SAPS-C6.5 diabody conjugates that specifically targeted the HER2 tumor associated antigen. In evaluating these immunoconjugates we determined that they were capable of efficient tumor targeting and therapeutic efficacy of established human tumor xenografts growing in immunodeficient mice. We also determined that therapeutic doses were associated with late renal toxicity, likely due to the role of the kidneys in the systemic elimination o f these agents. We are currently performing more studies focused on better understanding the observed toxicity. In the second aim, we successfully generated bispecific single-chain Fv (bs-scFv) molecules that co-targeted HER2 and HER3 or HER2 and HER4. The in vitro kinetics and in vivo tumor-targeting properties of these molecules were evaluated. These studies revealed that the bs-scFv molecules selectively localized in vitro on tumor cells that expressed both antigens and were capable of effective tumor localization in in vivo studies.

Adams, Gregory P.

2004-11-24

16

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

17

Confined alpha particle diagnostics for ITER based on measurements of gamma rays emitted from D({alpha},{gamma}){sup 6}Li reaction  

SciTech Connect

For the diagnosis of confined alpha particles in D-T plasma, we propose the observation of 2.186 MeV gamma ray produced by D({alpha},{gamma}){sup 6}Li reaction. However, there are few nuclear data of the D({alpha},{gamma}){sup 6}Li reaction rate. Therefore, we carried out the experimental verification of the gamma ray diagnostics technique by using an accelerator. Helium ions in the energy range of 2-4 MeV were bombarded into a thick deuterated polyethylene, where the gamma ray spectrum was measured with a Ge detector. Photopeak of the 2.186 MeV gamma ray was clearly observed. From our experiment, the emission rate of the 2.186 MeV gamma ray from the D({alpha},{gamma}){sup 6}Li reaction is estimated to be 10{sup 12}-10{sup 13} s{sup -1} in the ITER typical plasma condition. So we obtained a good prospect of the gamma ray measurement as the confined alpha particle diagnostics by using a high efficiency detector.

Ochiai, K.; Kubota, N.; Taniike, A.; Kitamura, A.; Nishitani, T. [Directorates of Fusion Energy Research, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane-Tokai, Ibaraki 319-1195 (Japan); Department of Environmental Energy Science, Faculty of Maritime Sciences, Kobe University, 5-1-1 Fukaeminami-machi, Higashinada-ku, Kobe 658-0022 (Japan); Directorates of Fusion Energy Research, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane-Tokai, Ibaraki 319-1195 (Japan)

2006-10-15

18

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

19

Alpha-particle microdosimetry.  

PubMed

With the increasing availability of alpha emitters, targeted ?-particle therapy has emerged as a solution of choice to treat haematological cancers and micrometastatic and minimal residual diseases. Alpha-particles are highly cytotoxic because of their high linear energy transfer (LET) and have a short range of a few cell diameters in tissue, assuring good treatment specificity. These radiologic features make conventional dosimetry less relevant for that context. Stochastic variations in the energy deposited in cell nuclei are important because of the microscopic target size, low number of ?- particle traversals, and variation in LET along the ?-particle track. Microdosimetry provides a conceptual framework that aims at a systematic analysis of the stochastic distribution of energy deposits in irradiated matter. The different quantities of microdosimetry and the different methods of microdosimetric calculations were described in the early eighties. Since then, numerous models have been published through the years and applied to analyse experimental data or to model realistic therapeutic situations. Major results have been an accurate description of the high toxicity of ?-particles, and the description of the predominant effect of activity distribution at the cellular scale on toxicity or efficacy of potential targeted ?-particle therapies. This last factor represents a major limitation to the use of microdosimetry in vivo because determination of the source - target distribution is complicated. The future contributions of microdosimetry in targeted ?-particle therapy research will certainly depend on the ability to develop high-resolution detectors and on the implementation of pharmaco-kinetic models at the tumour microenvironment scale. PMID:22201713

Chouin, Nicolas; Bardies, Manuel

2011-07-01

20

Summary of Alpha Particle Transport  

SciTech Connect

This paper summarizes the talks on alpha particle transport which were presented at the 5th International Atomic Energy Agency's Technical Committee Meeting on "Alpha Particles in Fusion Research" held at the Joint European Torus, England in September 1997.

Medley, S.S.; White, R.B.; Zweben, S.J.

1998-08-19

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

Streptavidin in antibody pretargeting. 5. chemical modification of recombinant streptavidin for labeling with the alpha-particle-emitting radionuclides 213Bi and 211At.  

PubMed

We are investigating the use of recombinant streptavidin (rSAv) as a carrier molecule for the short-lived alpha-particle-emitting radionuclides 213Bi ( t 1/2 = 45.6 min) and 211At ( t 1/2 = 7.21 h) in cancer therapy. To utilize rSAv as a carrier, it must be modified in a manner that permits rapid chelation or bonding with these short-lived radionuclides and also modified in a manner that diminishes its natural propensity for localization in the kidney. Modification for labeling with (213)Bi was accomplished by conjugation of rSAv with the DTPA derivative p-isothiocyanato-benzyl-CHX-A'' (CHX-A''), 3a. Modification for direct labeling with 211At was accomplished by conjugation of rSAv with an isothiocyanatophenyl derivative of a nido-carborane (nCB), 3b, or an isothiocyanatophenyl-dPEG/decaborate(2-) derivative, 3c. After conjugation of the chelating or bonding moiety, rSAv was further modified by reaction with an excess (50-100 equivalents) of succinic anhydride. Succinylation of the lysine amines has previously been shown to greatly diminish kidney localization. rSAv modified by conjugation with 3a and succinylated rapidly radiolabeled with 213Bi (<5 min), providing a 72% isolated yield. 211At labeling of modified rSAv was accomplished in aqueous solution using chloramine-T as the oxidant. Astatination of rSAv conjugated with 3b and succinylated occurred very rapidly (<1 min), providing a 50% isolated radiochemical yield. Astatination of rSAv conjugated with 3c and succinylated was also very rapid (<1 min) providing 66-71% isolated radiochemical yields. Astatination of succinylated rSAv, 2a, which did not have conjugated borane cage moieties, resulted in a much lower radiolabeling yield (18%). The 213Bi or 211At-labeled modified rSAv preparations were mixed with the corresponding 125 I-labeled rSAv, and dual-label in vivo distributions were obtained in athymic mice. The in vivo data show that 213Bi-labeled succinylated rSAv [ 213Bi] 6a has tissue concentrations similar to those of 125 I-labeled modified rSAv [ 125 I] 6b, suggesting that (213)Bi is quite stable toward release from the chelate in vivo. In vivo data also indicate that the (211)At-labeled rSAv conjugated with 3b or 3c and succinylated are stable to in vivo deastatination, whereas succinylated rSAv lacking a boron cage moiety is subject to some deastatination. The modified rSAv conjugated with nido-carborane derivative 3b has a higher retention in many tissues than rSAv without the carborane conjugated. Interestingly, the rSAv conjugated with 3c, which also contains an m-dPEG 12 moiety, has significantly decreased concentrations in blood and other tissues when compared with those of direct-labeled rSAv, suggesting that it may be a good candidate for further study. In conclusion, rSAv that has been modified with CHX-A'' and succinylated (i.e., 5a) may be useful as a carrier of 213Bi. The encouraging results obtained with the PEGylated decaborate(2-) derivative 3c and succinylated (i.e., 5c) suggests that its further study as a carrier of 211At in pretargeting protocols is warranted. PMID:18072725

Wilbur, D Scott; Hamlin, Donald K; Chyan, Ming-Kuan; Brechbiel, Martin W

2007-12-12

23

Determination of alpha-emitting Pu isotopes in environmental samples.  

PubMed

This paper presents an improved radiochemical procedure for the determination of alpha-emitting Pu isotopes in environmental samples (soils, sediments, vegetation) by alpha-particle spectrometry. Quantitative Pu recovery yields were obtained (average 60%), 0.1 mBq being the average minimum detectable activity by the complete technique. Special efforts were made to ensure the removal of traces of different natural alpha-emitting radionuclides, which can interfere with the correct determination of 239+240Pu and 238Pu concentrations. The radiochemical procedure was validated by application to reference material and by participation in intercomparison exercises. This radiochemical procedure was applied to the different layers of a high-resolution sediment core taken from a lake in Sweden. The 239+240Pu and 238Pu/239+240Pu profiles obtained in the high-resolution sediment core correctly reproduced the expected evolution of these quantities as observed historically in the atmosphere, validating the procedure for this purpose and showing the power of these radionuclides for dating purposes. PMID:12022654

Vioque, I; Manjn, G; Garca-Tenorio, R; El-Daoushy, F

2002-04-01

24

The measurement of alpha particle emissions from semiconductor memory materials  

Microsoft Academic Search

With the increasing concern for the affects of alpha particles on the reliability of semiconductor memories, an interest has arisen in characterizing semiconductor manufacturing materials for extremely low-level alpha-emitting contaminants. It is shown that four elements are of primary concern: uranium, thorium, radium, and polonium. Measurement of contamination levels are given relevance by first correlating them with alpha flux emission

D. P. Bouldin

1981-01-01

25

Probing preformed {alpha} particles in the ground state of nuclei  

SciTech Connect

In this Rapid Communication, we report on {alpha}-particle emission through the nuclear breakup in the reaction {sup 40}Ca on a {sup 40}Ca target at 50 A MeV. It is observed that, similar to nucleons, {alpha} particles can be 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 and is emitted by the short-range nuclear attraction of the collision partner. A time-dependent theory that describes the {alpha}-particle wave-function evolution is able to qualitatively reproduce the observed angular distribution. This mechanism offers new possibilities for studying {alpha}-particle properties in the nuclear medium.

Scarpaci, J. A.; Fallot, M.; Assie, M.; Lefevre, L.; Frascaria, N.; Beaumel, D.; Bhar, C.; Blumenfeld, Y.; Desesquelles, P.; Idbarkach, H.; Khan, E.; Plagnol, E.; Roynette, J. C.; Shrivastava, A.; Zerguerras, T. [Institut de Physique Nucleaire, Centre National de la Recherche Scientifique/Institut National de Physique Nucleaire et de Physique des Particules (CNRS/IN2P3), Universite Paris-Sud 11, F-91406 Orsay (France); Lacroix, D.; Chbihi, A.; Chomaz, Ph.; Frankland, J.; Laville, J. L. [Grand Accelerateur National d'Ions Lourds (GANIL), Commissariat a l'Energie Atomique et aux Energies Alternatives/Direction des Sciences de la Matiere (CEA/DSM)-CNRS/IN2P3, Bd Henri Becquerel, Boite Postale 55027, F-14076 Caen Cedex 5 (France)

2010-09-15

26

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

Microsoft Academic Search

The high linear energy transfer, alpha-particle-emitting radionuclide astatine-211 (211At) is of interest for certain therapeutic applications; however, because of the 55- to 70-microm path length of its alpha-particles, achieving homogeneous tracer distribution is critical. Hyperthermia may enhance the therapeutic efficacy of alpha-particle endoradiotherapy if it can improve tracer distribution. In this study, we have investigated whether hyperthermia increased the cytotoxicity

ML Hauck; RH Larsen; PC Welsh

1998-01-01

27

Preparation and activity measurement of electrodeposited alpha-emitting sources.  

PubMed

Alpha-emitting 238Pu and 241Am sources on stainless steel substrates have been prepared using a new electrodeposition method based on an ammonium oxalate-ammonium sulfate electrolyte containing diethyl triamino pentaacetic acid. The deposition yield is determined by measuring the activity of the sources using a high-efficiency 2pi alpha proportional counter and a backscattering chamber designed and fabricated for this purpose. Optimal electrodeposition parameters have been determined for 241Am, enabling manufacture of standard alpha-emitting sources with minimal radioactive waste. PMID:16891121

Lee, K B; Man Lee, Jong; Soon Park, Tae; Oh, Phil-Je

2006-08-07

28

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

29

The measurement of alpha particle emissions from semiconductor memory materials  

Microsoft Academic Search

With the increasing concern for the affects of alpha particles on the reliability of semiconductor memories, an interest has\\u000a arisen in characterizing semiconductor manufacturing materials for extremely low-level alpha-emitting contaminants. It is\\u000a shown that four elements are of primary concern: uranium, thorium, radium, and polonium. Measurement of contamination levels\\u000a are given relevance by first correlating them with alpha flux emission

D. P. Bouldin

1981-01-01

30

A High-Throughput Screen for Alpha Particle Radiation Protectants  

PubMed Central

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

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

2010-01-01

31

Actinium-225 in targeted alpha-particle therapeutic applications.  

PubMed

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

Scheinberg, David A; McDevitt, Michael R

2011-10-01

32

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.

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

2007-10-19

34

Scintillation of thin tetraphenyl butadiene films under alpha particle excitation  

Microsoft Academic Search

The alpha induced scintillation of the wavelength shifter\\u000a1,1,4,4-tetraphenyl-1,3-butadiene (TPB) was studied to improve the\\u000aunderstanding of possible surface alpha backgrounds in the DEAP dark matter\\u000asearch experiment. We found that vacuum deposited thin TPB films emit 882\\u000a+\\/-210 photons per MeV under alpha particle excitation. The scintillation pulse\\u000ashape consists of a double exponential decay with lifetimes of 11

Tina Pollmann; Mark Boulay; Marcin Ku?niak

2010-01-01

35

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.

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

2013-01-01

36

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

PubMed

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

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

2008-04-23

37

Nuclear diagnostic for fast alpha particles  

SciTech Connect

We investigate the possibility of seeding a fusion plasma with nuclei which can undergo nuclear reactions with energetic alpha particles to produce product nuclei which are radioactive. If a fraction of these product nuclei can be collected and measured, one can obtain information about the presence of fast alpha particles. It appears that a feasible diagnostic could be based upon the /sup 10/B(..cap alpha..,n)/sup 13/N reaction.

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

1982-12-01

38

Preparation of alpha-emitting nuclides by electrodeposition  

NASA Astrophysics Data System (ADS)

A method is described for electrodepositing the alpha-emitting nuclides. To determine the optimum conditions for plating plutonium, the effects of electrolyte concentration, chelating reagent, current, pH of electrolyte and the time of plating on the electrodeposition were investigated on the base of the ammonium oxalate-ammonium sulfate electrolyte containing diethyl triamino pentaacetic acid. An optimized electrodeposition procedure for the determination of plutonium was validated by application to environmental samples. The chemical yield of the optimized method of electrodeposition step in the environmental sample was a little higher than that of Talvitie's method. The developed electrodeposition procedure in this study was applied to determine the radionuclides such as thorium, uranium and americium that the electrodeposition yields were a little higher than those of the conventional method.

Lee, M. H.; Lee, C. W.

2000-06-01

39

Realistic Density Function of Alpha Particle  

NASA Astrophysics Data System (ADS)

In a framework of the ATMS method, one- and two-body density functions of the alpha particle are derived by using the Reid soft core V_{8} model potential. Deuteron-deuteron spectroscopic amplitudes describing the relative motion between the deuterons in the alpha particle for the (d, alpha) reaction are derived from the alpha and deuteron wave functions generated with the same potential. These functions are well represented as a sum of Gaussian functions. These Gaussian expansions have a real convenience of practical use, because their Fourier transforms can be obtained analytically.

Morita, H.; Akaishi, Y.; Endo, O.; Tanaka, H.

1987-11-01

40

Current status of alpha-particle spectrometry.  

PubMed

This paper describes the status of alpha-particle spectrometry. Some of the main contributions made to this field in the last years are reviewed. Topics covered include instrumentation, source characterization, numerical analysis, Monte Carlo simulations and applications. PMID:16554165

Garca-Torao, Eduardo

2006-03-22

41

Instrument for measuring total alpha particle energies of alpha emitters in ambient air  

NASA Astrophysics Data System (ADS)

This paper describes the design, fabrication, testing and evaluation of a self-reading, carbon fiber, electrometer-type instrument. It is used for measuring the total energy of alpha particles emitted in air by progenies of 222Rn (218Po, 214Pb, and 214Bi), and sometimes by other types of alpha emitters (e.g. 212Pb, 238U, and 239Pu). The purpose of these measurements is to assess the energy delivered by alpha emission from these sources to the lung tissue. A sample (charged progenies attached to aerosols) is collected on filter paper from a known volume of air and placed on the instrument. The discharge rate indicates the alpha energy in MeVl-1 of air per min that is produced by the alpha emitters. The calibration procedure shows that the instrument has an energy sensitivity for alpha particles of 800.5MeV/scale unit. The range of the readout scale is 30 units. Measurements of alpha contamination in air were made using this instrument in buildings, private homes and in a standard chamber. The value of the radon concentration in this chamber is traceable back to the US Environmental Protection Agency (EPA) and to the National Institute of Standards and Technology (NIST).

Kronenberg, S.; Brucker, G. J.; Cummings, B.; Bechtel, E.; Gentner, F.; Horne, S.

2000-11-01

42

Tidal Disruptions In A Lyman-Alpha Emitting Starburst Galaxy  

NASA Astrophysics Data System (ADS)

New VLA HI spectral line observations of ESO400-G043 are presented. This low mass ( 1.5x109 Solar Masses) system is of interest for studies of Lyman-alpha propagation in galaxies due to its relative proximity ( 83 Mpc) and its elevated star formation rate. HI gas kinematics are theorized to be a key factor affecting Ly-? propagation in the ISM: static neutral gas will aide resonant scattering and the efficient absorption of Ly-? photons by dust, while outflowing neutral gas reduces the efficiency of resonant scattering and thus favors the escape of Ly-? photons. Previous HST observations of ESO400-G043 have revealed a strong, asymmetric Ly-? emission line. Our new VLA observations show significant tidal HI gas between ESO400 and its companion galaxy (2MASX J20375125-3529431). These results support the kinematic model described above and are similar to the HI properties of other Ly-a emitting starburst galaxies published in Cannon et al. (2004) and described in the companion poster by Weindling et al.

Meitzner, Seth; Weindling, J.; Cannon, J. M.; Skillman, E.; Walter, F.

2010-01-01

43

Concepts of nuclear {alpha}-particle condensation  

SciTech Connect

Certain aspects of the recently proposed antisymmetrized {alpha}-particle product state wave function, or THSR (Tohsaki-Horiuchi-Schuck-Roepke) {alpha}-cluster wave function, for the description of the ground state in {sup 8}Be, the Hoyle state in {sup 12}C, and analogous states in heavier nuclei are elaborated in detail. For instance, the influence of antisymmetrization in the Hoyle state on the bosonic character of the {alpha} particles is studied carefully. It is shown to be weak. Bosonic aspects in Hoyle and similar states in other self-conjugate nuclei are, therefore, predominant. Another issue is the de Broglie wavelength of {alpha} particles in the Hoyle state, which is shown to be much larger than the inter-{alpha} distance. It is pointed out that the bosonic features of low-density {alpha} gas states have measurable consequences, one of which, enhanced multi-{alpha} decay properties, has likely already been detected. Consistent with experiment, the width of the proposed analog to the Hoyle state in {sup 16}O at the excitation energy of E{sub x}=15.1 MeV is estimated to be very small (34 keV), lending credit to the existence of heavier Hoyle-like states. The intrinsic single-boson density matrix of a self-bound Bose system can, under physically desirable boundary conditions, be defined unambiguously. One eigenvalue then separates out, being close to the number of {alpha} particles in the system. Differences between Brink and THSR {alpha}-cluster wave functions are worked out. No cluster model of the Brink type can describe the Hoyle state with a single configuration. On the contrary, many superpositions of the Brink type are necessary, implying delocalization toward an {alpha}-product state. It is shown that single {alpha}-particle orbits in condensates of different nuclei are almost the same. It is thus argued that {alpha}-particle (quartet) antisymmetrized product states of the THSR type are a very promising novel and useful concept in nuclear physics.

Funaki, Y. [Institute of Physics, University of Tsukuba, Tsukuba 305-8571 (Japan); Horiuchi, H. [Research Center for Nuclear Physics, Osaka University, Osaka 567-0047 (Japan); International Institute for Advanced Studies, Kizugawa 619-0225 (Japan); Oertzen, W. von [Hahn-Meitner-Institut Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany); Freie Universitaet Berlin, Fachbereich Physik, Arnimallee 14, D-14195 Berlin (Germany); Roepke, G. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Schuck, P. [Institut de Physique Nucleaire, F-91406 Orsay CEDEX (France); Universite Paris-Sud, F-91406 Orsay CEDEX (France); Laboratoire de Physique et Modelisation des Milieux Condenses, CNRS et Universite Joseph Fourier, 25 Avenue des Martyrs, BP 166, F-38042 Grenoble CEDEX 9 (France); Tohsaki, A. [Research Center for Nuclear Physics, Osaka University, Osaka 567-0047 (Japan); Yamada, T. [Laboratory of Physics, Kanto Gakuin University, Yokohama 236-8501 (Japan)

2009-12-15

44

Spatially Resolved H(alpha)-Emitting Wind Structure of P Cygni.  

National Technical Information Service (NTIS)

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 interfer...

A. Balan C. Tycner D. J. Hutter J. A. Benson R. T. Zavala

2010-01-01

45

Alpha particle analysis using PEARLS spectrometry  

Microsoft Academic Search

Alpha particle assay by conventional plate-counting methods is difficult because chemical separation, tracer techniques, and\\/or self-absorption losses in the final sample may cause either non-reproducible results or create unacceptable errors. PEARLS (Photon-Electron Rejecting Alpha Liquid Scintillation) Spectrometry is an attractive alternative since radionuclides may be extracted into a scintillator in which there would be no self-absorption or geometry problems and

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

1984-01-01

46

The status of alpha-particle diagnostics  

SciTech Connect

There is a flurry of activity to complete alpha-particle diagnostics so that they can undergo some experimental testing in DT plasmas on JET or TFTR prior to implementation on ITER. Successful measurements of escaping charged fusion products have been made in DD plasmas, and the {alpha}-particle source can be well characterized by neutron profile measurement. These methods can be extrapolated to DT plasmas. Measurement of the confined {alpha}-particles requires a new technique. Collective Thomson scattering, methods involving charge-exchange interactions and nuclear reactions with impurities will be discussed. Some assessment is given of the capabilities of these techniques, bearing in mind the potential for their use in the physics phase of the ITER program.

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

1992-08-01

47

The status of alpha-particle diagnostics  

SciTech Connect

There is a flurry of activity to complete alpha-particle diagnostics so that they can undergo some experimental testing in DT plasmas on JET or TFTR prior to implementation on ITER. Successful measurements of escaping charged fusion products have been made in DD plasmas, and the {alpha}-particle source can be well characterized by neutron profile measurement. These methods can be extrapolated to DT plasmas. Measurement of the confined {alpha}-particles requires a new technique. Collective Thomson scattering, methods involving charge-exchange interactions and nuclear reactions with impurities will be discussed. Some assessment is given of the capabilities of these techniques, bearing in mind the potential for their use in the physics phase of the ITER program.

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

1992-01-01

48

Nuclear Alpha-Particle Condensates  

NASA Astrophysics Data System (ADS)

The ?-particle condensate in nuclei is a novel state described by a product state of ?'s, all with their c.o.m. in the lowest 0S orbit. We demonstrate that a typical ?-particle condensate is the Hoyle state (Ex=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 ? 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 ?-particle condensate states also exist in heavier n? nuclei, like ^{16}O,^{20}Ne, etc. For instance the 0^+_6 state of ^{16}O at Ex=15.1 MeV is identified from a theoretical analysis as being a strong candidate of a 4? condensate. The calculated small width (140 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 ?'s, triton's, and neutrons etc. The relationship of ?-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 ? particle condensation in infinite nuclear matter. The strong qualitative difference with the pairing case is pointed out.

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

49

Sterically stabilized liposomes as a carrier for alpha-emitting radium and actinium radionuclides.  

PubMed

The alpha-particle emitting radionuclides (223)Ra (t(1/2) = 11.4 d), (224)Ra (t(1/2) = 3.6 d), and (225)Ac(t(1/2) = 10.0 d) may have a broad application in targeted radiotherapy provided that they could be linked to vehicles with tumor affinity. The potential usefulness of liposomes as carriers was studied in the present work. Radium and actinium radionuclides could be loaded in good yields into sterically stabilized liposomes. Subsequent coating of the liposomes with a folate-F(ab')(2) construct yielded a product with affinity towards tumor cells expressing folate receptors. Radionuclide loaded liposomes showed excellent stability in serum in vitro. PMID:15093814

Henriksen, Gjermund; Schoultz, B W; Michaelsen, T E; Bruland, S; Larsen, R H

2004-05-01

50

Lunar Surface Outgassing and Alpha Particle Measurements  

Microsoft Academic Search

The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-218 (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

S. L. Lawson; W. C. Feldman; David J. Lawrence; K. R. Moore; R. C. Elphic; S. Maurice; Richard D. Belian; Alan B. Binder

2002-01-01

51

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

52

Realistic Momentum Distributions of the alpha Particle  

NASA Astrophysics Data System (ADS)

We present various types of momentum distributions of the alpha particle using ATMS wave function generated with the Reid soft core V_{8} model potential. Those are the momentum distributions of the single-nucleon, two-nucleon-cluster relative motion, two-nucleon-cluster center of mass, triton-proton relative motion and deuteron-deuteron relative motion. These momentum distributions are well represented as a sum of Gaussian functions. With these Gaussian expansions, the realistic momentum distributions of the alpha particle would become accessible to everyone.

Morita, H.; Akaishi, Y.; Tanaka, H.

1988-04-01

53

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

54

Cross section balance in the 14N + 159Tb reaction and the origin of fast alpha particles  

NASA Astrophysics Data System (ADS)

Exclusive cross sections have been obtained from particle-K X-ray coincidence data measured at 236 MeV for ejectiles ranging from 4He to 15N. Production cross sections for primary fragments and alpha particle multiplicities associated with different channels have been deduced. The major fraction of the alpha particles appears to originate from inelastic (damped) processes in which only light particles with Z <= 2 are emitted. Institute for Nuclear Research, 05-400 Swierk, Poland.

Siemssen, R. H.; Balster, G. J.; Wilschut, H. W.; Bond, P. D.; Crouzen, P. C. N.; Goldhoorn, P. B.; Shukui, Han; Sujkowski, Z.

1985-10-01

55

Alpha-Particles within Nuclei  

NASA Astrophysics Data System (ADS)

We present a formalism describing the bound state of a large number of bosons and apply it to study nuclei consisting of A ? particles. The method has its roots in a few-body approach and is based on the expansion of the many-body Faddeev components in Potential Harmonics, and the subsequent reduction of the Faddeev equation into a two-variable, integro-differential equation. For A ? ? this equation is transformed into a new simpler integro-differential equation, which is easy to use in calculations for A up to as large as 1000. We use both integro-differential equations to investigate the behavior of nuclei subject to the assumption that they are composed of ? particles. Various ? ? forces were employed. For the Ali-Bodmer potential we found that the A = 5 system (i.e. 20Ne) is the most stable, while for the A = 10 system (i.e. 40Ca) the binding energy has a maximum. The formalism predicts ?-decay for larger nuclei, but the value of A where this begins to happen is strongly dependent on the ? ? potential.

Sofianos, S. A.; Lekala, M. L.; Adam, R. M.; Belyaev, V. B.

2013-03-01

56

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

57

Alpha particle analysis using PEARLS spectrometry  

SciTech Connect

Alpha particle assay by conventional plate-counting methods is difficult because chemical separation, tracer techniques, and/or self-absorption losses in the final sample may cause either non-reproducible results or create unacceptable errors. PEARLS (Photon-Electron Rejecting Alpha Liquid Scintillation) Spectrometry is an attractive alternative since radionuclides may be extracted into a scintillator in which there would be no self-absorption or geometry problems and in which up to 100% chemical recovery and counting efficiency is possible. Sample preparation may include extraction of the alpha emitter of interest by a specific organic-phase-soluble compound directly into the liquid scintillator. Detection electronics use energy and pulse-shape discrimination to provide discrete alpha spectra and virtual absence of beta and gamma backgrounds. Backgrounds on the order of 0.01 cpm are readily achievable. Accuracy and reproducibility are typically in the 100 +-1% range. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium, and polonium assay. This paper will review liquid scintillation alpha counting methods and reference some of the specific applications. 8 refs., 1 fig.

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

1984-01-01

58

NOVEL METHOD FOR BEAM DYNAMICS STUDY USING AN ALPHA PARTICLE SOURCE  

Microsoft Academic Search

A new method for beam dynamic study has been devel- oped by using alpha particles emitted from a commercially available radioactive source. The precision of the method is estimated in consideration of an event rate in a reason- able measuring time and statistical accuracy. The method could be applied not only for a circular accelerator but also for a unit

A. Sato; M. Aoki; Y. Arimoto; T. Itahashi; Y. Kuno; T. Oki; M. Yoshida

59

Shielding of Manned Space Vehicles Against Protons and alpha Particles.  

National Technical Information Service (NTIS)

The available information on the shielding of manned space vehicles against protons and alpha particles is summarized. The emphasis is placed on shielding against Van Allen belt protons and against solar-flare protons and alpha particles, but information ...

R. G. Alsmiller R. T. Santoro J. Barish H. C. Claiborne

1972-01-01

60

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

61

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

NASA Astrophysics Data System (ADS)

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

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

62

Design of lost alpha particle diagnostics for JET  

Microsoft Academic Search

In a future magnetic fusion reactor alpha particles will be utlilized for plasma heating. In order to achieve a high efficiency of this process, the aim has to be a good confinement of alpha particles. Therefore, direct measurement of alpha particle losses is of particular interest. Two diagnostics are being prepared for the JET Tokamak that are targeting on exactly

S. Baeumel; A. Werner; R. Semler; S. Mukherjee; D. S. Darrow; R. Ellis; F. E. Cecil; L. Pedrick; H. Altmann; V. Kiptily; J. Gafert

2005-01-01

63

Lunar Surface Outgassing and Alpha Particle Measurements  

NASA Astrophysics Data System (ADS)

The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-218 (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. Radon reaches the lunar surface either at areas of high soil porosity or where fissures release the trapped gases in which radon is entrained. Once released, the radon spreads out by "bouncing" across the surface on ballistic trajectories in a randomwalk process. The half-life of radon-222 allows the gas to spread out by several 100 km before it decays (depositing approximately half of the polonium-218 recoil nuclides on the lunar surface) and allows the APS to detect gas release events up to several days after they occur. The long residence time of the lead-210 precursor to polonium-210 allows the mapping of gas vents which have been active over the last approximately 60 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.

Lawson, S. L.; Feldman, W. C.; Lawrence, D. J.; Moore, K. R.; Elphic, R. C.; Maurice, S.; Belian, R. D.; Binder, A. B.

2002-01-01

64

Alpha-particle-induced cancer in humans.  

PubMed

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

Mays, C W

1988-10-01

65

Effects of inhaled alpha-emitting actinides on mouse alveolar macrophages.  

PubMed Central

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 239PuO2 on murine AM. The effects discussed include changes the 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.

Morgan, A; Talbot, R J

1992-01-01

66

The formation of ultra-fine particles during ozone-initiated oxidations with terpenes emitted from natural paint.  

PubMed

The formation of secondary products during the ozone-initiated oxidations with biogenic VOCs emitted from natural paint was investigated in this study. Mass spectrometry and infrared spectroscopy measurements have shown that the major components of gas-phase chemicals emitted from natural paint are monoterpenes including alpha- and beta-pinenes, camphene, p-cymene, and limonene. A significant formation of gaseous carbonyl products and nano-sized particles (4.4-168nm) was observed in the presence of ozone. Carboxylic acids were also observed to form during the reactions (i.e. formic acid at 0.170ppm and acetic acid at 0.260ppm). The formation of particles increased as the volume of paint introduced into a reaction chamber increased. A secondary increase in the particle number concentration was observed after 440min, which suggests further partitioning of oxidation products (i.e. carboxylic acids) into the particles previously existing in the reaction chamber. The growth of particles increased as the mean particle diameter and particle mass concentrations increased during the reaction. The experimental results obtained in this study may provide insight into the potential exposure of occupants to irritating chemical compounds formed during the oxidations of biogenic VOCs emitted from natural paint in indoor environments. PMID:16908097

Lamorena, Rheo B; Jung, Sang-Guen; Bae, Gwi-Nam; Lee, Woojin

2006-07-04

67

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 229ThO2. Separations of 225Ac were carried out by placing nickel recoil collector foils in firm contact with the 229ThO2 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 ThO2 thickness. The results of the calculations have been benchmarked with recoil separation measurements carried out using ThO2 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

68

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

Microsoft Academic Search

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

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

2004-01-01

69

ANGULAR MOMENTUM MISALIGNMENT IN DEEP INELASTIC PROCESSES AND ANGULAR DISTRIBUTION OF SEQUENTIALLY EMITTED PARTICLES AND GAMMA RAYS  

SciTech Connect

The angular momentum misalignment for fragments produced in deep inelastic scattering is discussed in terms of the thermal excitation of angular-momentum-bearing modes in the intermediate complex. Analytical expressions for the in- and out-of-plane angular distributions are obtained for sequentially emitted particles and fission fragments. The angular momentum dependence of the ratio between particle and neutron decay width is explicitly treated and found to be quite important. Similarly angular distributions are obtained both for dipole and quadrupole gamma decay. The theoretical results are compared with experimental angular distributions of sequential fission fragments, sequential alphas and gamma rays and a good agreement is found.

Moretto, L.G.; Blau, S.; Pacheco, A.

1980-12-01

70

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

71

{alpha}-particle optical potential tests below the Coulomb barrier  

SciTech Connect

The results of two recent papers concerning ({alpha},{gamma}) and ({alpha},n) reaction cross sections close to the reaction thresholds are discussed with regard to predictions of a recent {alpha}-particle regional optical potential. It is found that the new measured cross sections are rather well described especially for the dominant reaction channels. Particular features of the {alpha}-particle optical potential at energies below the Coulomb barrier explain the failure of a former regional potential obtained by analysis of {alpha}-particle elastic scattering alone at higher energies. Additional limitations of statistical model calculations for minor reaction channels are also discussed.

Avrigeanu, M.; Avrigeanu, V. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, P. O. Box MG-6, Bucharest-Magurele (Romania)

2009-02-15

72

The Capture of Electrons by Alpha-Particles  

Microsoft Academic Search

A stream of electrons is superposed upon a beam of alpha-particles. The alpha-particles are then deflected by a magnetic field and counted by the scintillation method. Alpha-particles which have captured electrons will not be deflected to the point where observation is made, and consequently, the decrease in scintillations will indicate the number of captures which occur. Probability of capture as

Arthur H. Barnes

1930-01-01

73

Alpha particle loss in the TFTR DT experiments  

SciTech Connect

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

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

1995-01-01

74

Alpha Particle Induced Reactions on Vanadium  

NASA Astrophysics Data System (ADS)

Alpha particle-induced reactions on the target element vanadium were investigated from threshold up to 55 MeV using the foil-stack activation technique and the Ge(Li) gamma ray spectroscopy method. Excitation functions for the formation of reaction residues 54Mn, 52Mn, 51Cr, 48V, 47Sc, 46Sc were investigated. The experimental cross-sections were compared with the predictions based on updated hybrid model (ALICE/90) using n0=4 (4p0h) and level density parameter a=A/9. A general agreement was found for all the reactions of (?, xn) type. However, the model failed badly in all cases of (?, z?xn) type of reactions.

Rao, A. V. Mohan; Chintalapudi, S. N.

75

Simultaneous determination of alpha-emitting radionuclides of thorium and plutonium in human tissues including bone  

Microsoft Academic Search

A method has been developed for the simultaneous determination of environmental, i.e., non-occupational, levels of ..cap alpha..-emitting isotopes of thorium and plutonium in human lung, lymph nodes, liver, kidney, thyroid, spleen, gonads, and bone. Known amounts of soft tissues (5-850 g) spiked with 1-2 dpm tracers of ²²⁹Th and ²⁴²Pu are wet ashed with nitric acid, and HSO with occasional

Narayani P. Singh; Shawki A. Ibrahim; Norman. Cohen; McDonald E. Wrenn

1979-01-01

76

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

77

Growth retardation and destruction of experimental squamous cell carcinoma by interstitial radioactive wires releasing diffusing alpha-emitting atoms.  

PubMed

In the present study, we examined the antitumoral effects caused by the release of alpha emitting radioisotopes into solid squamous cell carcinoma (SCC) tumors. Using a novel method termed DART (Diffusing Alpha-emitters Radiation Therapy), we assessed the efficacy of short-lived daughters of (224)Ra releasing alpha particles, dispersing in the malignant tissue, to cause tumor growth retardation and destruction. It was carried out using specially designed wires loaded with (224)Ra activities in the range of 7-42 kBq in a set of experiments performed on BALB/c and nude mice bearing metastatic SCC tumors derived from either mouse SQ2 or human CAL27 cell lines. The insertion of a DART wire to the center of 6-7 mm primary tumors, retarded tumor growth, reduced lung metastatic load, prolonged life expectancy and in some cases caused tumor eradication. These effects were enhanced either when treating smaller tumors or treating identical tumors with 2 DART wires. Similar experiments on human-derived SCC tumors in nude mice were consistent with the outcomes of the murine model. Histological assessments revealed the tissue damage pattern, and indicated a role for the tumor vasculature in the dispersion of the atoms and the propagation of the damage. Our findings indicate that Diffusing Alpha-emitting Radiation Therapy is effective in a model system using SCC primary tumors. The in situ destruction of primary solid tumors by DART is evidently a necessary step toward curing cancer and might be augmented by chemotherapy and other modalities such as immunotherapy or antigrowth factors agents. PMID:18059026

Cooks, Tomer; Arazi, Lior; Schmidt, Michael; Marshak, Gideon; Kelson, Itzhak; Keisari, Yona

2008-04-01

78

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

79

Analytic expressions for {alpha} particle preformation in heavy nuclei  

SciTech Connect

Experimental {alpha} decay energies and half-lives are investigated systematically to extract {alpha} particle preformation in heavy nuclei. Formulas for the preformation factors are proposed that can be used to guide microscopic studies on preformation factors and perform accurate calculations of the {alpha} decay half-lives. There is little evidence for the existence of an island of long stability of superheavy nuclei.

Zhang, H. F.; Wang, Y. J.; Dong, J. M. [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Royer, G. [Laboratoire Subatech, UMR IN2P3/CNRS Universite Ecole des Mines, Nantes 44 (France); Zuo, W.; Li, J. Q. [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2009-11-15

80

Faddeev Equations for Deuteron Break-Up on alpha Particles.  

National Technical Information Service (NTIS)

Faddeev equations for deuteron break-up on alpha particles are given. Total cross-sections for the reaction process d+ alpha implies n+p+ alpha are calculated by means of the Faddeev equations and separable potentials. Numerical solution of the resulting ...

A. Osman

1976-01-01

81

Inelastic Scattering of Alpha-Particles from Carbon  

Microsoft Academic Search

The inelastic scattering of alpha particles from C¹² was studied ; by observation of the alpha particles and of the gamma rays from the deexcitation ; of the first excited state, Gamma rays were detected with NaI(Tl) crystals. A ; yield curve from threshold to 17 Mev showed well isolated resonances-in the ; region below 11 Mev. Detailed angular distributions

Gary Earl Mitchell

1962-01-01

82

Coulomb Splitting of Relativistic C Ions into Three alpha -Particles.  

National Technical Information Service (NTIS)

Coulomb splitting of relativistic C ions to three alpha -particles has been considered. The basis of the mechanism is an assumption that the splitting takes place with preliminary excitation of carbon that is followed by its decay to three alpha -particle...

Kaptar L.P A. I. Titov

1978-01-01

83

Quantifying Sulfate, Organics, and Lubrication Oil in Particles Emitted from Military Aircraft Engines.  

National Technical Information Service (NTIS)

1.1 Objectives SERDP Project WP1625 was a multi-component effort to understand volatile contributions to particulate matter (PM) emitted from military aircraft engines. Volatile PM formed when condensable gases emitted in the exhaust form new particles or...

H. Wong J. Peck R. Miake-Lye S. C. Herndon Z. Yu

2012-01-01

84

The genotoxicity of alpha particles in human embryonic skin fibroblasts.  

PubMed

Cell inactivation and induced mutation frequencies at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus have been measured in cultured human fibroblasts (GM10) exposed to alpha particles from 238Pu (LET at the cell surface was 100 keV/microns) and 250 kVp X rays. The survival curves resulting from exposure to alpha particles are exponential. The mean lethal dose, D0, is approximately 1.3 Gy for X rays and 0.25 Gy for alpha particles. As a function of radiation dose, mutation induction at the HGPRT locus was linear for alpha particles whereas the X-ray-induced mutation data were better fitted by a quadratic function. When mutation frequencies were plotted against the log of survival, mutation frequency at a given survival level was greater in cells exposed to alpha particles than to X rays. PMID:6494443

Chen, D J; Strniste, G F; Tokita, N

1984-11-01

85

Genotoxicity of alpha particles in human embryonic skin fibroblasts  

SciTech Connect

Cell inactivation and induced mutation frequencies at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus have been measured in cultured human fibroblasts (GM10) exposed to ..cap alpha.. particles from /sup 238/ Pu and 250 kVp X rays. The survival curves resulting from exposure to ..cap alpha.. particles are exponential. The mean lethal dose, D/sub 0/, is approximately 1.3 Gy for X rays and 0.25 Gy for ..cap alpha.. particles. As a function of radiation dose, mutation induction at the HGPRT locus was linear for ..cap alpha.. particles whereas the X-ray-induced mutation data were better fitted by a quadratic function. When mutation frequencies were plotted against the log of survival, mutation frequency at a given survival level was greater in cells exposed to ..cap alpha.. particles than to X rays.

Chen, D.J.; Strniste, G.F.; Tokita, N.

1984-11-01

86

Evaluation of a photo-electron rejecting alpha liquid scintillation (PERALS) spectrometer for the measurement of alpha-emitting radionuclides  

SciTech Connect

Results from the evaluation of a PERALS spectrometer for alpha particle measurements by liquid scintillation counting in samples from the nuclear fuel cycle are presented. Examples of PERALS spectra of process, waste, and environmental samples containing Th, U, Pu and Am from the Savannah River Site are shown. The advantages, disadvantages, and limitations of the PERALS technique are discussed. 15 refs., 11 figs.

Cadieux, J.R.

1990-01-01

87

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

88

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

SciTech Connect

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

NICOLE Collaboration and ISOLDE Collaboration

1996-12-01

89

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

90

In situ production of alpha particles and alpha recoil particles in quartz applied to ESR studies of oxygen vacancies  

Microsoft Academic Search

The intensity of an ESR signal associated with oxygen vacancies in quartz (E1? center and heat-treated E1? center) are correlated with the radiometric age of their host rocks. Two natural processes are responsible for the production of oxygen vacancies (1) lattice damage along alpha recoil and alpha particle tracks and (2) randomly distributed ionization damage from energetic electrons (beta particles)

S. Toyoda; W. J Rink; C Yonezawa; H Matsue; T Kagami

2001-01-01

91

Morphology and chemistry of fine particles emitted from a Canadian coal-fired power plant  

Microsoft Academic Search

Particles emitted from coal-fired power plants burning subbituminous coal from Alberta, Canada were examined for total particulates (PM) and size fractions PM>10, PM10, and PM2.5. The sampling was carried out following EPA Method 201A. Three tests were performed at each station. The emitted particles were examined using SEM\\/EDX and gravimetric method for the determination of their sizes. The elemental composition

F. Goodarzi

2006-01-01

92

ITER alpha particle diagnostics using knock-on ion tails  

SciTech Connect

Alpha particles will play a critical role in the physics and successful operation of ITER. Achieving fusion ignition requires that the {alpha} particles created by deuterium-tritium (D-T) reactions deposit a large fraction of their energy in the reacting plasma before they are lost. Toroidal field ripple can localize any alpha particle losses and cause first wall damage. We have proposed a new method of measuring the fast confined {alpha}-particle distribution in a reacting plasma. The same elastic collisions that transfer the alpha energy to the D-T plasma ions and allow fusion ignition will also create a high energy tail on the deuterium and tritium ion energy distributions. Some of these energetic tail ions will undergo fusion reactions with the background plasma producing neutrons whose energy is increased significantly above 14 MeV due to the kinetic energy of the reacting ions. Measurement of this high energy tail on the D-T neutron distribution as a function of plasma minor radius would provide information on the alpha density profile with a time response equal to the ion slowing-down time. Although this technique may provide only limited information on the {alpha}-particle energy distribution, experimental studies of fast ions on existing tokamaks have shown that the observed slowing-down is essentially classical. Hence the {alpha}-energy distribution is expected to be classical except in situations where the {alpha}-confinement is poor. The confinement of {alpha}`s can be affected by ripple losses and a number of instabilities. Toroidal field ripple can cause both prompt orbit losses and stochastic ripple diffusion losses. Magnetohydrodynamic activity, including fishbone instabilities, toroidal Alfven eigenmodes, and sawtooth oscillations, may also affect alpha confinement. The diagnostic proposed here, by monitoring the confined alpha population, can provide valuable information on the confinement of fast alphas in a reacting plasma.

Fisher, R.K.; Parks, P.B.; McChesney, J.M. [and others

1995-09-01

93

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

SciTech Connect

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

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

1994-03-01

94

Effect of alpha particles on Toroidal Alfven Eigenmodes  

SciTech Connect

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

Berk, H.L.

1992-11-01

95

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

96

Measurement of alpha particles on PLT  

SciTech Connect

The radial emission profile of the d(/sup 3/He,p)..cap alpha.. fusion reaction was measured on PLT by pitch angle resolution of the escaping 3.7-MeV alphas. The d-/sup 3/He reactions were produced by /sup 3/He minority ICRF and the emission was strongly peaked at the ICRF resonance layer.

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

1984-12-01

97

Observational evidence of alpha-particle capture at Mars  

NASA Astrophysics Data System (ADS)

Solar wind alpha-particles are suggested to be the most important source of helium in the Martian atmosphere. Recent hybrid simulations show that as much as 30% of the alpha-particles passing through the planetary cross section can be lost from the solar wind due to charge-exchange processes associated with the Mars/solar wind interaction. We use ion data from the ASPERA-3 instrument on Mars Express to investigate the penetration of alpha-particles into the Martian atmosphere. We conclude that solar wind alpha-particles contribute to the helium observed in the atmosphere. In accordance with simulations we see an asymmetry in the capture efficiency related to the solar wind convection electric field.

Stenberg, G.; Nilsson, H.; Futaana, Y.; Barabash, S.; Fedorov, A.; Brain, D.

2011-05-01

98

Preliminary Results from the Lunar Prospector Alpha Particle Spectrometer  

NASA Astrophysics Data System (ADS)

Data measured using the Lunar Prospector Alpha Particle Spectrometer were surveyed to search for surface deposits of polonium-210. Preliminary results show that a marginal, yet statistically-significant signal was indeed detected on the lunar front side.

Lawson, S. L.; Feldman, W. C.; Moore, K. R.; Lawrence, D. J.; Maurice, S.; Belian, R. D.; Binder, A. B.

2001-03-01

99

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

Microsoft Academic Search

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

E. R. Crosson; S. K. Lemieux; E. J. Ludwig; W. J. Thompson; M. Bisenberger; R. Hertenberger; D. Hofer; H. Kader; P. Schiemenz; G. Graw; A. M. Eiro; F. D. Santos

1993-01-01

100

Measurement of alpha particle energy using windowless electret ion chambers.  

PubMed

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

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

2002-10-01

101

Genotoxicity of alpha particles in human embryonic skin fibroblasts  

Microsoft Academic Search

Cell inactivation and induced mutation frequencies at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus have been measured in cultured human fibroblasts (GM10) exposed to ..cap alpha.. particles from ²³⁸ Pu and 250 kVp X rays. The survival curves resulting from exposure to ..cap alpha.. particles are exponential. The mean lethal dose, D, is approximately 1.3 Gy for X rays and 0.25

D. J. Chen; G. F. Strniste; N. Tokita

1984-01-01

102

Plastic scintillator with phosphorescent dopants for alpha-particles registration  

Microsoft Academic Search

In the present work we try to study the difference between the conventional scintillator and the scintillator with Eu-organic complexes in response to alpha-particle of 239Pu source. It is shown that polystyrene-based scintillator film with 4 wt% of Eu-organic complex have 5650 photons\\/MeV light output for alpha-particle of 5.4 MeV energy. This is 7 times higher than light output of

A. F. Adadurov; P. N. Zhmurin; V. N. Lebedev; V. V. Kovalenko

2010-01-01

103

Alpha particle effects on the internal kink modes  

SciTech Connect

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

Wu, Yanlin; Cheng, C.Z.

1994-08-01

104

The feasibility of 225Ac as a source of alpha-particles in radioimmunotherapy.  

PubMed

This paper proposes the utilization of 225Ac for the alpha-radioimmunotherapy of cancer. The isotope decays with a radioactive half-life of 10 days into a cascade of short-lived alpha- and beta-emitting isotopes. In addition, when indicated by the pharmacokinetic requirements of particular clinical applications, 213Bi, with a radioactive half-life of 47 min, can be chosen as an alternative source of alpha-particles in radioimmunotherapy. This isotope is the last alpha emitter in the 225Ac decay-cascade and can be extracted from a 225Ac source at the bedside of the patient. 225Ac can quasi ad infinitum be obtained from one of its precursors, 229Th, which can be made available by various means. The indications for the use of alpha-particles as an alternative to more traditional classes of radiation are derived from the particle-kinetic characteristics and the radioactive half-life of their source isotope, as well as from the properties of the target-selective carrier moiety for the source isotope. It may be expected that useful applications, complementary to and/or in conjunction with other means of therapy will be identified. PMID:8429990

Geerlings, M W; Kaspersen, F M; Apostolidis, C; van der Hout, R

1993-02-01

105

Counting Particles Emitted by Stratospheric Aircraft and Measuring Size of Particles Emitted by Stratospheric Aircraft. Final report, 1 May 1990-31 December 1992  

SciTech Connect

There were two principal objectives of the cooperative agreement between NASA and the University of Denver. The first goal was to modify the design of the ER-2 condensation nuclei counter (CNC) so that the effective lower detection limit would be improved at high altitudes. This improvement was sought because, in the instrument used prior to 1993, diffusion losses prevented the smallest detectable particles from reaching the detection volume of the instrument during operation at low pressure. Therefore, in spite of the sensor`s ability to detect particles as small as 0.008 microns in diameter, many of these particles were lost in transport to the sensing region and were not counted. Most of the particles emitted by aircraft are smaller than 0.1 micron in diameter. At the start date of this work, May 1990, continuous sizing techniques available on the ER-2 were only capable of detecting particles larger than 0.17 micron. Thus, the second objective of this work was to evaluate candidate sizing techniques in an effort to gain additional information concerning the size of particles emitted by aircraft.

Wilson, J.C.

1994-04-01

106

Transition radiation emitted by a particle moving along the axis of a perfectly conducting conical surface  

SciTech Connect

The spatial field distribution is determined for the transition radiation emitted by a relativistic particle moving along the axis of a perfectly conducting circular conical surface with a fixed apex. Emission from particles moving away from and towards the apex is examined. Expressions are obtained that can be used to calculate the angular distribution of radiation intensity for various apex angles between 0 and {pi}. Significant differences are demonstrated between the spatial distributions of radiation generated by outgoing and incoming particles.

Kol'tsov, A. V., E-mail: koltsov@x4u.lebedev.ru; Serov, A. V., E-mail: serov@x4u.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

2011-12-15

107

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...

108

In vitro immunotoxic and genotoxic activities of particles emitted from two different small-scale wood combustion appliances  

Microsoft Academic Search

Residential wood combustion appliances emit large quantities of fine particles which are suspected to cause a substantial health burden worldwide. Wood combustion particles contain several potential health-damaging metals and carbon compounds such as polycyclic aromatic hydrocarbons (PAH), which may determine the toxic properties of the emitted particles. The aim of the present study was to characterize in vitro immunotoxicological and

Maija Tapanainen; Pasi I. Jalava; Jorma Mki-Paakkanen; Pasi Hakulinen; Mikko S. Happo; Heikki Lamberg; Jarno Ruusunen; Jarkko Tissari; Kati Nuutinen; Pasi Yli-Piril; Risto Hillamo; Raimo O. Salonen; Jorma Jokiniemi; Maija-Riitta Hirvonen

109

Probing alpha-particle wave functions using (d-->,alpha) reactions  

Microsoft Academic Search

Wave functions of the alpha particle corresponding to different S- and D-state deuteron-deuteron overlaps, , were investigated using exact finite-range distorted-wave Born-approximation (DWBA) analyses of (d-->,alpha) reactions. Cross sections, vector, and tensor-analyzing powers were measured for (d-->,alpha) reactions populating the lowest Jpi=7+ state in 56Co at bombarding energies Ed of 16 and 22 MeV, the lowest 7+ state in 48Sc

E. R. Crosson; S. K. Lemieux; E. J. Ludwig; W. J. Thompson; M. Bisenberger; R. Hertenberger; D. Hofer; H. Kader; P. Schiemenz; G. Graw; A. M. Eir; F. D. Santos

1993-01-01

110

Alpha particle destabilization of the toroidicity-induced Alfven eigenmodes.  

National Technical Information Service (NTIS)

The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped (alpha)-particles through the wave-particle resonances. Satisfying the resonance condition requires that the ...

C. Z. Cheng

1990-01-01

111

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

PubMed

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

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

2007-05-11

112

A model to evaluate the biological effect induced by the emitted particles from a beta-delayed particle decay beam  

NASA Astrophysics Data System (ADS)

Due to their favourable properties such as high dose localization and high RBE heavy-ion beams have attracted increasing interest in cancer treatment. Efforts to exploit these advantages to the maximum extent in cancer therapy have never been given up. A new idea of applying a radioactive ion beam with beta-delayed particle decay such as 9C or 8B to cancer therapy is put forward in this paper. A model to evaluate the biological effect in terms of cell survival induced by the emitted particles from the decays of the stopped ions has been established. Because of the difference of the internally emitted particle irradiation from the external ion beam, the microdosimetric quantity such as specific energy is applied to evaluate the cell surviving effect induced by the emitted particles from the decays of the radioactive ions. Within the framework of this model, the cell-killing effects resulting from the emitted particles were calculated under different conditions. Finally, the potential application of the radioactive ion beam 9C in cancer therapy is demonstrated.

Li, Qiang; Kanai, Tatsuaki; Kitagawa, Atsushi

2003-09-01

113

The evaporation signal from [alpha] particles stopped in superfluid helium  

SciTech Connect

Alpha particles stopped in a 3 liter volume of liquid helium at 30 mK are observed by the calorimetric detection of helium atoms evaporated from the free surface of the liquid. Quantum evaporation of the helium is produced by the rotons that are created by the [alpha] particle. While the energy spectrum of the 5.5 MeV [alpha]'s from the [sup 241]Am source has a width of less than 0.5%, the energy distribution of the observed evaporation signals extends from the low energy threshold of several keV up to a maximum of several 100 keV, depending on geometrical factors and the collection area of the calorimeter. The origin of the observed distribution may result in part from the presence of the substrate and a dependence on the direction of the track of the [alpha] particle. A simple model of the generation of rotons by the [alpha] particle will be discussed.

Bandler, S.R.; Enss, C.; Goldhaber, G.; Lanou, R.E.; Maris, H.J.; More, T.; Porter, F.S.; Seidel, G.M. (Brown Univ., Providence, RI (United States))

1993-11-01

114

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

115

Ionization cluster size distribution for alpha particles: experiment, modelling.  

PubMed

The paper presents data for measured ionization cluster size distributions by alpha particles in tissue equivalent media and comparison with the simulated data for liquid water. The experiments were carried out with a beam of 4.6 MeV alpha particles performed in a setup called the JET Counter. The theoretically derived cluster size distributions for alphas particles were obtained using the K-means algorithm. The simulation was carried out by Monte Carlo track structure calculations using cross sections for liquid water. The first moments of cluster size distributions, derived from K-means algorithm as a function of diameter of cluster centroid, were compared with the corresponding moments derived from the experiments for nitrogen and propane targets. It was found that the ratio of the first moments for water to gas targets correlates well with the corresponding ratio of the mean free paths for primary ionization by alpha particles in the two media. It is shown that the cluster size distributions for alpha particles in water, obtained from K-means algorithm, are in agreement with the corresponding distributions measured experimentally in nitrogen or propane gas targets of nanometer sizes. PMID:17251255

Pszona, S; Bantsar, A; Nikjoo, H

2007-01-24

116

Utility of extracting {alpha}-particle energy by waves  

SciTech Connect

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

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

1994-05-01

117

The energetic alpha particle transport method EATM  

SciTech Connect

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

Kirkpatrick, R.C.

1998-02-01

118

HETDEX: Developing the HET's Second Generation Low Resolution Spectrograph for Probing Lyman-alpha Emitting Galaxies  

NASA Astrophysics Data System (ADS)

HETDEX will map the power spectrum of 0.8 million blindly discovered Lyman-alpha Emitting Galaxies (LAE) using a revolutionary new array of massively replicated fiber-fed spectrographs dubbed the Visible Integral-Field Replicable Unit Spectrograph (VIRUS). In the era of the Hobby-Eberly Telescope wide-field upgrade and VIRUS, the current Low Resolution Spectrograph (LRS) must be replaced with a fiber instrument. We discuss the development of the second generation LRS (LRS2), which is a multi-channel instrument based on the VIRUS design. In its current design phase, it is fed by a 287 fiber microlens coupled integral field unit that covers 7 x 12 with 0.62 resolution. The instrument covers 3720 to 4700 at R ? 1900 and 4600 to 7000 at R ?1200. With the purpose of making the instrument ideal for follow-up observations of LAE in the HETDEX survey, we discuss the science drivers for selecting the instrument's spectral resolution. We test the utility of the instrument and pilot a future study with LRS2 by presenting R ? 2000 spectra taken with the VIRUS prototype spectrograph (VIRUS-P) in a high-resolution mode at the McDonald Observatory Harlan J. Smith 2.7 m telescope. These LAE were originally discovered in the HETDEX Pilot Survey and their Lyman-alpha line profiles are constrained by near-infrared observations of rest-frame optical emission lines that set the systemic redshift of the galaxies. We discuss the velocity offsets of the Lyman-alpha line from the systemic line center and compare the line profiles to theoretical predictions and to similar observations for Lyman-break galaxies. Our observations provide an example of how LRS2 can be used to probe Lyman-alpha emission in 2 < z < 3 star forming galaxies.

Chonis, Taylor S.; Hill, G. J.; Lee, H.; Tuttle, S. E.; Vattiat, B. L.; Gebhardt, K.; Finkelstein, S. L.; Adams, J. J.; HETDEX Collaboration

2012-01-01

119

Tables of average distributions of particles emitted by ionized elements (Z = 6--100)  

SciTech Connect

Tables giving the average division of energy between electrons and x-rays emitted by singly ionized elements undergoing bound-bound transitions are provided. The expected number of particles is also given. This data is tabulated by atomic number and subshell of initial vacancy. A description of the method of calculation is also presented. 2 refs., 1 fig., 1 tab.

Lee, P.; Rathkopf, J.; Cullen, D.; Perkins, S.

1990-01-01

120

Evolution of trace gases and particles emitted by a chaparral fire in California  

Microsoft Academic Search

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 ha prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009.

S. K. Akagi; J. S. Craven; J. W. Taylor; G. R. McMeeking; R. J. Yokelson; I. R. Burling; S. P. Urbanski; C. E. Wold; J. H. Seinfeld; H. Coe; M. J. Alvarado; D. R. Weise

2011-01-01

121

alpha-Particle stopping power for titanium and vanadium  

Microsoft Academic Search

A method for accurate measurement of the specific energy loss dE\\/dx of alpha-particles is described and results are given for titanium in the alpha-energy range 5.25-13 MeV and for vanadium in the range 5.25-12 MeV with uncertainties of about 3%. The results are in excellent agreement with the stopping power predictions of Ziegler and earlier precision measurements of the stopping

R. C. Haight; H. K. Vonach

1984-01-01

122

Morphology of cells malignantly transformed by alpha particle irradiation  

Microsoft Academic Search

The idea that one alpha particle (with LET approximately 100keV\\/micrometers) traversing a cell nucleus would kill a cell has been a concept which has been traditionally accepted by most radiation biologists. It was, therefore, difficult to see how alpha radiation could act directly on nuclear DNA to cause cancer. In experiments where mouse embryo cells (C3H 10T1\\/2) were irradiated with

E. L. Lloyd; C. B. Henning

1981-01-01

123

Radon monitor and control system based upon alpha particle detection  

SciTech Connect

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

Hurst, G.S.

1992-01-01

124

Solar wind alpha particle capture at Mars and Venus  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

125

Structural and fractal properties of particles emitted from spark ignition engines.  

PubMed

Size, morphology, and microstructure of particles emitted from one light-duty passenger vehicle (Buick Century; model year 1990; PM (particulate matter) mass emission rate 3.1 mg/km) and two light-duty trucks (Chevrolet C2; model year 1973; PM mass emission rate 282 mg/km, and Chevrolet El Camino; model year 1976; PM mass emission rate 31 mg/km), running California's unified driving cycles (UDC) on a chassis dynamometer, were studied using scanning electron microscopy (SEM). SEM images yielded particle properties including three-dimensional density fractal dimensions, monomer and agglomerate number size distributions, and three different shape descriptors, namely aspect ratio, root form factor, and roundness. The density fractal dimension of the particles was between 1.7 and 1.78, while the number size distribution of the particles placed the majority of the particles in the accumulation mode (0.1-0.3 microm). The shape descriptors were found to decrease with increasing particle size. Partial melting of particles, a rare and previously unreported phenomenon, was observed upon exposure of particles emitted during phase 2 of the UDC to the low accelerating voltage electron beam of the SEM. The rate of melting was quantified for individual particles, establishing a near linear relationship between the melting rate and the organic carbon 1 to elemental carbon ratio. PMID:17144291

Chakrabarty, Rajan K; Moosmller, Hans; Arnott, W Patrick; Garro, Mark A; Walker, John

2006-11-01

126

{alpha}-Particle Condensation in {sup 16}O  

SciTech Connect

In order to explore the 4{alpha}-particle condensate state in {sup 16}O, we solve a full four-body equation based on the 4{alpha} OCM (Orthogonality Condition Model) in a large 4{alpha} model space spanned by Gaussian basis functions. A full spectrum up to the 0{sub 6}{sup +} state is reproduced consistently with the lowest six 0{sup +} states of the experimental spectrum. It is suggested that the 0{sub 6}{sup +} state is the analog to the Hoyle state of {sup 12}C, to be identified with the well known 0{sub 6}{sup +} state at 15.1 MeV in {sup 16}O.

Schuck, P. [Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406, France Universite Paris-Sud, Orsay, F-91505 (France); Funaki, Y. [Institute of Physics, University of Tsukuba, Tsukuba 305-8571 (Japan); Yamada, T. [Laboratory of Physics, Kanto Gakuin University, Yokohama 236-8501 (Japan); Horiuchi, H.; Tohsaki, A. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 567-0047 (Japan); Roepke, G. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany)

2009-08-26

127

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

PubMed

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

Trknyi, F; Hermanne, A; Kirly, B; Takcs, S; Ignatyuk, A V

2009-12-01

128

Ion cyclotron emission spectroscopy as an. cap alpha. -particle monitor  

SciTech Connect

Since 1981, we have proposed and investigated spectral analysis of the harmonics of ion cyclotron emission (ICE) as a means of monitoring the energy content of ..cap alpha.. particles confined in a magnetic fusion device. A pair of crown probe antennas have been constructed for TFTR to collect ICE spectra and will be installed on that device in the near future. The design of this ICE spectroscopy system is described. Also, some calculations of ICE electromagnetic fluctuations in the ICRF, due to newborn ..cap alpha.. particles with a distribution function appropriate to typical fusion reactor parameters, are discussed. The calculated emission spectra are quite distinct from that of blackbody radiation.

Moses, K.G.; Sperling, J.L.; Dooling, J.C.; Chu, C.

1988-08-01

129

Solar wind alpha particle capture at Mars and Venus  

NASA Astrophysics Data System (ADS)

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

Stenberg, Gabriella; Barabash, Stas; Nilsson, Hans; Fedorov, A.; Brain, David; Andr, Mats

130

Modeling of Alpha Particle Loss from a DT Spherical Tokamak  

NASA Astrophysics Data System (ADS)

A proposed follow-up to the present generation of spherical tokamak experiments (NSTX and MAST) would be a larger ST with parameters on the order of R=1.2 m, a=0.9 m, I_p=18 MA, B_T=1.7 T. Such an ST could be run with a DT fuel mixture and could have a breakeven parameter of 1 <= Q <= 40. For such a device to have high Q, it must confine the fusion-produced alpha particles until their energy has been transferred to cold incoming fuel. We are making an initial assessment of alpha particle confinement in a model DTST configuration by computing their prompt orbit loss fraction. The computation follows the orbits of a representative sample of alpha particles whose birth locations are distributed according to an expected fusion source profile. Orbits are tracked until they intersect the vessel wall or until a maximum orbit length (tilde 1 km, which is much less than the characteristic collisional slowing down distance in these plasmas) is reached. Because the gyroradii of 3.5 MeV alpha particles in such a device are a non-negligible fraction of the minor radius (r/a tilde 0.2), this model follows the full gyro-orbit of each particle. Progress in the modeling effort will be reported.

Wyatt, D.; Darrow, D.; Paoletti, F.

2000-10-01

131

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

132

Alpha-particle condensation in light hypernuclei  

NASA Astrophysics Data System (ADS)

Gas-like ?-cluster states are investigated in light ? hypernuclei. The ? condensate-type microscopic cluster model wave function is introduced to describe ? hypernuclei. In particular, the analogous state to the famous Hoyle state, the second 0+ state in 12C, is investigated in 13?C, with the use of the new type wave function. The Hoyle state is known to have a gas-like 3? cluster structure, where the 3? particles are condensed into an identical S orbit. The second 1/2+ state in 13?C is shown to have the 3?+? structure. A strong shrinkage effect by adding the ? particle is seen for the state, reducing the rms radius from 3.8 fm in the Hoyle state to 2.8 fm. In spite of the shrinkage effect, the ? condensate fraction of about 60% still survives, though it is reduced by about 20% from the Hoyle state.

Funaki, Yasuro; Yamada, Taiichi; Hiyama, Emiko; Ikeda, Kiyomi

2013-09-01

133

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

SciTech Connect

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

Siemssen, R.H.

1985-01-01

134

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.

135

Emitted High Energy Light Particle Data Base Development Using a Thermodynamic Coalescence Model  

NASA Astrophysics Data System (ADS)

In many applications, double-differential (energy and angle) secondary light particle production cross sections must be known for ion energies from tens of MeV/nucleon to tens of GeV/nucleon. Incorporating high energy light particle spectral and angular distribution cross section databases in the transport codes enable them to transport nearly any radiation field, in three dimensions, that humans and instruments might be exposed to in space, near accelerators or during charged particle radiotherapy. In this work a thermodynamics coalescence model is used to estimate the coalescence and emitting source radii for both symmetric and asymmetric heavy ion collision systems.

Arsalan, M. P.; Townsend, L. W.

2013-03-01

136

Toxicity of particles emitted from combustion of waste crankcase oil: in vitro and in vivo studies  

SciTech Connect

The ever-rising cost of energy provides incentives for the utilization of low-cost waste crankcase oil (WCO) for space heating. Although WCO is known to contain toxic heavy metals, the potential health hazards of emissions and waste products resulting from the combustion of WCO are unknown. Thus, the toxicity of the emission particles and waste products from two different types of burners, a Dravo atomizing oil burner (AOB) and a Kroll vaporizing oil burner (VOB), is evaluated using automotive WCO. Samples are characterized by performing elemental analysis and scanning electron microscopy. Both burners emitted fine (less than or equal to 3 microns), respirable particles. The AOB emission particles contained high concentrations of toxic heavy metals, especially Pb, which showed concentrations as high as 7.5%. The VOB retained a significant amount of heavy metals in the burner residue and emitted a much smaller quantity into the air. The toxicity of AOB emission particles, VOB emission particles, and VOB waste residue is evaluated in three bioassay systems, including a rabbit alveolar macrophage (RAM) cytotoxicity in vitro assay, an intratracheal injection infectivity assay, and a peritoneal irritancy test in mice. The emission particles from both burners and leachate from VOB residue produce a dose-related reduction in viability and cellular adenosine triphosphate (ATP) in alveolar macrophages following 20-hr exposure. Acidity of the RAM medium due to the presence of VOB emission particles and waste leachate contributes to its toxicity.

Mumford, J.L.; Hatch, G.E.; Hall, R.E.; Jackson, M.A.; Merrill, R.G. Jr.; Lewtas, J.

1986-07-01

137

Particle Physics Aspects of Antihydrogen Studies with ALPHA at CERN  

Microsoft Academic Search

We discuss aspects of antihydrogen studies, that relate to particle physics ideas and techniques, within the context of the ALPHA experiment at CERN's Antiproton Decelerator facility. We review the fundamental physics motivations for antihydrogen studies, and their potential physics reach. We argue that initial spectroscopy measurements, once antihydrogen is trapped, could provide competitive tests of CPT, possibly probing physics at

M. C. Fujiwara; G. B. Andresen; W. Bertsche; P. D. Bowe; C. C. Bray; E. Butler; C. L. Cesar; S. Chapman; M. Charlton; J. Fajans; R. Funakoshi; D. R. Gill; J. S. Hangst; W. N. Hardy; R. S. Hayano; M. E. Hayden; A. J. Humphries; R. Hydomako; M. J. Jenkins; L. V. Jrgensen; L. Kurchaninov; W. Lai; R. Lambo; N. Madsen; P. Nolan; K. Olchanski; A. Olin; A. Povilus; P. Pusa; F. Robicheaux; E. Sarid; S. Seif El Nasr; D. M. Silveira; J. W. Storey; R. I. Thompson; D. P. van der Werf; L. Wasilenko; J. S. Wurtele; Y. Yamazaki

2008-01-01

138

Particle Physics Aspects of Antihydrogen Studies with ALPHA at CERN  

Microsoft Academic Search

We discuss aspects of antihydrogen studies, that relate to particle physics ideas and techniques, within the context of the ALPHA experiment at CERN's Antiproton Decelerator facility. We review the fundamental physics motivations for antihydrogen studies, and their potential physics reach. We argue that initial spectroscopy measurements, once antihydrogen is trapped, could provide competitive tests of CPT, possibly probing physics at

M. C. Fujiwara; G. B. Andresen; W. Bertsche; P. D. Bowe; C. C. Bray; E. Butler; C. L. Cesar; S. Chapman; M. Charlton; J. Fajans; R. Funakoshi; D. R. Gill; J. S. Hangst; W. N. Hardy; R. S. Hayano; A. J. Humphries; R. Hydomako; M. J. Jenkins; L. V. Jrgensen; L. Kurchaninov; W. Lai; R. Lambo; N. Madsen; P. Nolan; K. Olchanski; A. Olin; A. Povilus; P. Pusa; F. Robicheaux; E. Sarid; S. Seif; D. M. Silveira; J. W. Storey; R. I. Thompson; D. P. van der Werf; L. Wasilenko; J. S. Wurtele; Y. Yamazaki

2009-01-01

139

Fusion-Born Alpha Particle Ripple Loss Studies in ITER.  

National Technical Information Service (NTIS)

Fusion-born alpha particle losses are investigated for two ITER scenarios with and without test blanket modules (TBMs). When the TBMs were present it was found that the losses increased by a factor of two overall with a marked increase in its localization...

G. J. Kramer H. L. Berk R. Nazikian R. B. White

2008-01-01

140

Effect of alpha particles on bacteriophage T4Br(+)  

SciTech Connect

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

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

1983-01-01

141

Stopping Power of Liquid Water for alpha-Particles  

Microsoft Academic Search

THE mean stopping power of liquid water averaged over the whole range has been determined for natural alpha-particles by Michl1 and by Philipp2. These authors find values for the molecular stopping power which are higher by about 20 and 14 per cent respectively than those predicted by the Bragg law and the accepted atomic stopping powers of hydrogen and oxygen.

R. K. Appleyard

1949-01-01

142

Alpha particle collimator for micron-sized beam  

Microsoft Academic Search

A collimated alpha source is constructed from a drawn glass microcapillary and a plated polonium wire source. The shape of the capillary is approximately Gaussian, allowing an analytical model for the collimated flux intensity. The very gradual taper results in a nearly monochromatic beam. Two models are presented characterizing the particle flux intensity and its profile on a surface below

F. J. Henley; W. G. Oldham

1982-01-01

143

Neutron production by alpha particles in thin uranium hexafluoride  

SciTech Connect

Alpha-particle-induced neutrons from UF/sub 6/ serve as an indicator of /sup 235/U enrichment and may be exploited for safeguards purposes. If the UF/sub 6/ density is low enough, neutron production is reduced as a result of alpha-particle escape before (..cap alpha..,n) reactions with /sup 19/F. Calculational methods and results are presented that enable prediction of neutron production in low-density (thin) UF/sub 6/ as encountered in the gas centrifugation method of uranium enrichment. Neutron production is shown to be strongly dependent on average UF/sub 6/ density and weakly dependent on rotational speed in an operating centrifuge.

Stewart, J.E.

1983-07-01

144

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

Microsoft Academic Search

Components of alpha-particle wave functions corresponding to d-d configurations are used to predict analyzing powers in the (d,alpha) reaction. Tensor analyzing powers, especially Axx, are shown to clearly distinguish between wave functions generated by different realistic nucleon-nucleon interactions. Data for the 58Ni(d,alpha)56Co reaction to the 7+ stretched-nucleon-orbital state at 2.283-MeV excitation in 56Co, measured with 22-MeV deuterons, are compared to

E. R. Crosson; R. K. Das; S. K. Lemieux; E. J. Ludwig; W. J. Thompson; M. Bisenberger; R. Hertenberger; D. Hofer; H. Kader; P. Schiemenz; G. Graw; A. M. Eir; F. D. Santos

1992-01-01

145

Characterization of particles emitted by incense burning in an experimental house.  

PubMed

The potential health effects of fine and ultrafine particles are of increasing concern. A better understanding of particle characteristics and dispersion behavior is needed. This study aims at characterizing spatial and temporal variations in fine and ultrafine particle dispersion after emission from a model source in an experimental house. Particles emitted by an incense stick burning for 15 min were characterized. Number concentration, specific surface area and mass were measured. Partial chemical analysis of particles was also realized. Near the burning incense stick, the maximum concentration was 25,500 particles/cm(3); the indoor PM(2.5) concentration reached 197 microg/m(3), and the specific surface area concentration was 180 microm(2)/cm(3). The estimated incense smoke density was 1.1 g/cm(3). Time of Flight Aerosol Mass Spectrometer measurements indicated that the organic fraction was predominant in the aerosol mass detected, and other minor components identified were K(+), NO(3)(-), and Cl(-). The combustion of an incense stick in the living room was associated with significant modifications of the concentrations of particles measured in the different rooms of the house. This demonstration of pollution by particle dispersion by a model source of moderate intensity may have significant implications in terms of assessment of indoor exposure to such particles. Practical Implications The particles emitted in a domestic environment by a source of moderate intensity such as burning incense disperse throughout the house, even in rooms with closed doors and in rooms as far away as the next floor. This dispersion has significant implications in terms of evaluating human indoor exposure to fine and ultrafine particles. PMID:20409193

Ji, X; Le Bihan, O; Ramalho, O; Mandin, C; D'Anna, B; Martinon, L; Nicolas, M; Bard, D; Pairon, J-C

2010-04-01

146

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

147

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

148

Alpha-particle losses in compact torsatron reactors  

SciTech Connect

Loss of alpha particles in compact torsatron reactors is studied. For 6, 9, and 12 field period reactors, the direct loss is a relatively weak function of radius and energy and varies from approx. =33% for M = 6 to approx. =18% for M = 12. Loss of alpha particles through scattering into the loss region is calculated using the Fokker-Plank equation for fast ions and found to contribute an additional alpha-particle energy loss of approx. =15%. The consequences of these relatively large losses for torsatron reactor design are discussed. The relationship between the direct particle losses and the magnetic field structure is also studied. Orbit losses from a variety of stellarator configurations are calculated and a figure-of-merit that characterizes the orbit confinement of a magnetic configuration is deduced from these calculations. This figure-of-merit is used to show how the direct losses might be reduced at low aspect-ratio. Effects of finite beta on the direct particle losses are also addressed, and are shown to significantly increase the direct losses in some configurations. 15 refs., 8 figs.

Painter, S.L.; Lyon, J.F.

1989-01-01

149

Multimodal particle size distributions emitted from HFA-134a solution pressurized metered-dose inhalers.  

PubMed

The purpose of this research was to investigate the measurement and in vitro delivery implications of multimodal distributions, occurring near or in the respirable range, emitted from pressurized metered-dose inhalers (pMDIs). Particle size distributions of solution pMDIs containing hydrofluoroalkane-134a (HFA-134a) and ethanol were evaluated using 2 complementary particle-sizing methods: laser diffraction (LD) and cascade impaction (CI). Solution pMDIs were formulated from mixtures of HFA-134a (50%-97.5% wt/wt) and ethanol. A range of propellant concentrations was selected for a range of vapor pressures. The fluorescent probe, Rhodamine B, was included for chemical analysis. The complementary nature of LD and CI allowed identification of 2 dominant particle size modes at 1 and 10 micro m or greater. Increasing propellant concentrations resulted in increases in the proportion of the size distributions at the 1- micro m mode and also reduced the particle size of the larger droplet population. Despite significant spatial differences and time scales of measurement between the particle-sizing techniques, the fine particle fractions obtained from LD and CI were practically identical. This was consistent with LD experiments, which showed that particle sizes did not decrease with increasing measurement distance, and may be explained by the absence of significant evaporation/disintegration of larger droplets. The fine particle fractions (FPFs) emitted from HFA-134a/ethanol solution pMDI can be predicted on the basis of formulation parameters and is independent of measurement technique. These results highlight the importance of presenting particle size distribution data from complementary particle size techniques. PMID:14621970

Smyth, Hugh D C; Hickey, Anthony J

2003-01-01

150

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

NASA Astrophysics Data System (ADS)

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

Watchman, Christopher J.

151

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.

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

2010-01-01

152

The Origin and Evolution of Low-Redshift (z<2) Lyman Alpha Emitting Galaxies  

NASA Astrophysics Data System (ADS)

Low luminosity galaxies contribute significantly to the mass and star-formation density of the universe at early epochs. Ly(alpha) emitting galaxies (LAEs) are powerful probes of the low-luminosity end of the luminosity function, and are also used to place constraints on the reionization epoch and the early mass assembly of galaxies. Most LAE studies have focused primarily on high redshifts (z~3-7) where the physical nature and large-scale context of LAEs remain largely unconstrained. In order to remedy this situation, we have begun a survey for LAEs at 1.8

Dey, Arjun; Reddy, Naveen; Prescott, Moire; Brodwin, Mark; Xu, Lei

2010-08-01

153

Historical trend in alpha-particle induced soft error rates of the AlphaTM microprocessor  

Microsoft Academic Search

In this work, we present ?-particle induced soft error rates (SER) for several generations of the Alpha microprocessor. In our analysis, we focus in particular on the historical trend of soft error rates for memory cells and random core logic. Our data demonstrate the impact of process, design and packaging material on the SER. The total chip-level SER trend has

N. Seifert; D. Moyer; N. Leland; R. Hokinson

2001-01-01

154

Additional alpha-particle optical potential tests below the Coulomb barrier  

Microsoft Academic Search

New results of (alpha,gamma) and (alpha,n) reaction cross section measurements close to the reaction thresholds support the setting up of recent parameters of the alpha-particle optical model potential (OMP) below the Coulomb barrier. Particular features of the alpha-particle optical potential at energies below the Coulomb barrier explain the failure of using the OMP parameters obtained by analysis of only alpha-particle

M. Avrigeanu; V. Avrigeanu

2010-01-01

155

Additional {alpha}-particle optical potential tests below the Coulomb barrier  

SciTech Connect

New results of ({alpha},{gamma}) and ({alpha},n) reaction cross section measurements close to the reaction thresholds support the setting up of recent parameters of the {alpha}-particle optical model potential (OMP) below the Coulomb barrier. Particular features of the {alpha}-particle optical potential at energies below the Coulomb barrier explain the failure of using the OMP parameters obtained by analysis of only {alpha}-particle elastic scattering at higher energies.

Avrigeanu, M.; Avrigeanu, V. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, RO-077125 Bucharest-Magurele (Romania)

2010-03-15

156

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.

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

157

Alpha particles induce apoptosis through the sphingomyelin pathway.  

PubMed

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

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

2011-06-01

158

Identification of platinum and palladium particles emitted from vehicles and dispersed into the surface environment.  

PubMed

Platinum, palladium, and rhodium are emitted from vehicle catalytic converters. Until now, the form of precious metal particles in road dust and urban waste has not been identified. This study has located, imaged, and analyzed these particles in road dust and gully waste. Two fragments of catalytic converter have been observed in road dust. They are 40-80 ?m in size and covered in many minute particles (<0.3 ?m) of either platinum with minor rhodium or palladium. One fragment identified in gully sediment is smaller, 25 ?m in diameter, hosting only one attached particle of palladium with minor rhodium. As fragments are washed off roads they begin to disintegrate and the precious metals become detached. Also precious metal-bearing particles have been located in incinerated sewage ash including a 20 ?m diameter cluster of <3 ?m sized platinum particles that may be the remains of a catalytic converter fragment that has survived incineration. The form of these precious metal-bearing particles described here reveals that as they are dispersed from roads they are likely to be present predominantly as two particle sizes. Either they are attached to larger fragments of catalytic converter or they are released as individual detached tiny <0.3 ?m to nanoparticle sizes. PMID:22313190

Prichard, Hazel M; Fisher, Peter C

2012-03-07

159

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

PubMed Central

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

Sgouros, George; Song, Hong

2010-01-01

160

Fission studies with 140 MeV {alpha} particles  

SciTech Connect

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

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

2009-09-15

161

Semiconducting detectors of alpha-particles fabricated by ion implantation  

Microsoft Academic Search

The low-energy ion implantation method of boron and phosphorus in p- and n-type silicon is used in conjunction with appropriate methods for mechanical and chemical surface treatments of the materials to fabricate semiconducting detectors for alpha-particle spectrometers. High-quality p-n junctions with low reverse currents were obtained. With a 30-sq-mm sensitive area, the detectors have a resolving power from 17 to

D. Sueva; B. Amov; A. Dzhakov; N. Chikov

1977-01-01

162

Stopping of Protons and alpha -Particles in Compounds. 1.  

National Technical Information Service (NTIS)

The stopping power and ranges of 0.1-100 MeV protons and alpha -particles were calculated in some compounds: air, water, CO, CO sub 2 , CaF sub 2 , LiF, (Csub(2)Fsub(4))sub(n), SiO sub 2 , Al sub 2 O sub 3 , NaCl, KCl, NaI, KI, CsI, C sub 6 H sub 5 CH, C ...

T. D. Chesnokova N. N . Pucherov A. E. Borzakovskij

1981-01-01

163

Stopping power for alpha particles in organic liquids and vapours  

Microsoft Academic Search

The stopping power for 5.5 MeV alpha particles has been studied in liquid and vapour phases of water, methanol, ethanol, propanol, pentane, hexane, cyclohexane, heptane and octane. Experimental values for stopping powers in the range 5.5 MeV to 0.5 MeV have been extracted by fitting the range-energy data with polynomial and inverse stopping power functions, and compared with existing results.

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

1991-01-01

164

Effects of. alpha. -particle radiation on rat tracheal epithelial cells  

SciTech Connect

By a combination of methods, which included flow cytometry and magnetic cell sorting, we have demonstrated that the cells of the rat tracheal epithelium which have the greatest proliferative capacity in culture and in vivo are the basal cells. Because of these findings it seems reasonable to suppose that the basal cells are the most likely target for the action of {alpha}-particle radiation in pseudostratified respiratory epithelium. This hypothesis is further supported by the finding that the basal cells are the cells which appear to respond to the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. The effects of {sup 210}Po {alpha}-particles on the survival and oncogenic transformation of rat tracheal epithelial cells in suspension were investigated. Since these effects were assayed in culture, the results pertain to the reaction of only the basal cells to irradiation. The results indicate that {alpha}-particles are extremely cytotoxic in that a track segment of 4 {mu}m, on average, is sufficient to cause the reproductive death of basal cells. This finding is supported by similar results obtained with two cell lines, Mv1Lu and CHO-K1 BH{sub 4}. Production of proliferating epithelial foci by {alpha}-particles was not distinguishable from control and sham treatments. These results are in direct conflict with many of the results that have been obtained with C3H 1OT1/2 cells in similar transformation assays. Some possible reasons for these disparities are discussed and supporting evidence is provided.

Ford, J.R. Jr.

1992-08-01

165

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

166

{alpha} particle preformation in heavy nuclei and penetration probability  

SciTech Connect

The {alpha} particle preformation in the even-even nuclei from {sup 108}Te to {sup 294}118 and the penetration probability have been studied. The isotopes from Pb to U have been firstly investigated since the experimental data allow us to extract the microscopic features for each element. The assault frequency has been estimated using classical methods and the penetration probability from tunneling through the Generalized Liquid Drop Model (GLDM) potential barrier. The preformation factor has been extracted from experimental {alpha} decay energies and half-lives. The shell closure effects play the key role in the {alpha} preformation. The more the nucleon number is close to the magic numbers, the more the formation of {alpha} cluster is difficult inside the mother nucleus. The penetration probabilities reflect that 126 is a neutron magic number. The penetration probability range is very large compared to that of the preformation factor. The penetration probability determines mainly the {alpha} decay half-life while the preformation factor allows us to obtain information on the nuclear structure. The study has been extended to the newly observed heaviest nuclei.

Zhang, H. F. [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Royer, G. [Laboratoire Subatech, UMR: IN2P3/CNRS-Universite-Ecole des Mines, F-44307 Nantes Cedex 03 (France)

2008-05-15

167

Energetic alpha particle deposition in a magnetized plasma  

SciTech Connect

The problem of energetic alpha particle deposition in a dense, magnetized deuterium-tritium (DT) thermonuclear fuel has been studied numerically for the case of coulomb interactions in cylindrical geometry. This was done by following the particle trajectories initiated at various radii and in different directions through the plasma and its imposed field until they had either left the plasma or deposited all their energy. The resulting complex particle trajectories in the static magnetized fuel make a detailed treatment of the problem computationally intensive. Therefore, we have attempted to use detailed modeling to produce a data base for a neural nets algorithm for incorporation in an ignition critical profile code. While the accuracy of the neutral net in reproducing the detailed calculational results is not high, it is approximately 6000 times faster. 7 refs., 1 fig.

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

1991-01-01

168

An Investigation of Alpha-Particle Groups from Al27(d,alpha)Mg25  

Microsoft Academic Search

The alpha-particle groups produced by the bombardment of aluminum by 10.8-Mev deuterons have been measured using nuclear emulsion plates for detection. Seven new levels in Mg25 were found at 6.98, 7.85, 8.62, 9.06, 975, 10.78, and 11.89 Mev. The previously known level at 4.01 Mev has been resolved into two levels at 3.96 and 4.12 Mev.

E. C. Toops; M. B. Sampson; F. E. Steigert

1952-01-01

169

Alpha particle-driven toroidal rotation in burning plasmas  

NASA Astrophysics Data System (ADS)

The mechanism of a torque intrinsically produced by alpha particles and the subsequent possibility to create significant toroidal rotation and shear are numerically investigated. In steady-state DEMO plasmas, regardless of the magnetic configuration, the orbit-following Monte Carlo code OFMC predicts that co-directed collisional torque and a counter-directed \\vec{j}\\times\\vec{B} torque always emerge due to the gradient of the source profile of alpha particles and both of them virtually cancel each other out, as analytically predicted earlier. The magnitude of each torque is enhanced in the reversed shear configuration compared with the normal shear configuration, provided that the source gradient is finite and similar in both cases. The resultant rotation velocity estimated by the TASK/TX transport code is far below the threshold to stabilize resistive wall modes (RWMs) through intrinsic alpha-driven torque alone. It is estimated that a neutral beam injection at a moderate power level may be capable of producing toroidal rotation sufficient to stabilize RWMs.

Honda, M.; Takizuka, T.; Tobita, K.; Matsunaga, G.; Fukuyama, A.

2011-07-01

170

Alpha-particle Measurements Needed for Burning Plasma Experiments  

SciTech Connect

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

Kenneth M. Young

2001-09-26

171

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

172

Emission of Long-Range Alpha Particles in the Spontaneous Fission of Cf252  

Microsoft Academic Search

An experimental investigation of alpha-particle emission in the spontaneous fission of Cf252 is described. The measured angular distribution and energy distribution of the alpha particles are presented, as well as the mass-ratio distribution of the fission fragments and the single-fragment energy distribution in fission accompanied by long-range alpha particles (LRA fission). Also shown is the angular distribution of the alpha

Z. Fraenkel

1967-01-01

173

p53 gene mutation analysis in tumors of patients exposed to alpha-particles.  

PubMed

The p53 gene was examined for point mutations in archived, alpha-radiation-associated lung and liver cancers. Lung tumors of 50 uranium miners in Germany were screened by restriction fragment length analysis for the putative hotspot mutation at codon 249 (Arg-->Met) previously detected in a significant fraction of miners from the Colorado Plateau, USA. This mutation has been proposed as a marker of radon exposure. None of the tumors we examined harbored the hotspot mutation. Five of the 50 tumors, however, did indeed harbor exon 7 mutations, as determined by subsequent mutation analysis of exon 7. These mutations were dispersed among various codons and may be attributable to heavy tobacco smoking in this cohort. In support of this interpretation, we found no mutations in exons 5-8 of the p53 gene in 13 iatrogenic liver cancers induced by injection of Thorotrast, an alpha-emitting radiocontrast agent. We propose that if the p53 tumor suppressor gene is a target for the carcinogenic action of alpha-particle radiation, loss of suppressor function may occur preferentially by mechanisms such as intrachromosomal deletions, rather than by base substitution mutations. PMID:9067550

Hollstein, M; Bartsch, H; Wesch, H; Kure, E H; Mustonen, R; Mhlbauer, K R; Spiethoff, A; Wegener, K; Wiethege, T; Mller, K M

1997-03-01

174

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

2011-12-06

175

Isotopic uranium and plutonium analysis by alpha-particle spectrometry  

NASA Astrophysics Data System (ADS)

An isotopic uranium analysis of environmental and man-made samples was performed by alpha-particle spectrometry. A fitting technique using blocks of peaks in the spectra measured with silicon detectors was developed. Samples of natural uranium from conventional mines and from the Bangomb natural nuclear reactor were analysed. The isotope composition of depleted and enriched uranium samples was also determined. The technique was applied to determining the isotope composition of plutonium samples, identifying whether the samples were reactor-grade or weapons-grade plutonium. Spectra of soil samples from Palomares and others from an inter-laboratory comparison exercise were analysed, yielding very good results.

Rubio Montero, M. P.; Martn Snchez, A.; Carrasco Lourtau, A. M.

2004-01-01

176

Alpha particle collimator for micron-sized beam  

SciTech Connect

A collimated alpha source is constructed from a drawn glass microcapillary and a plated polonium wire source. The shape of the capillary is approximately Gaussian, allowing an analytical model for the collimated flux intensity. The very gradual taper results in a nearly monochromatic beam. Two models are presented characterizing the particle flux intensity and its profile on a surface below the collimator tip. These models are experimentally verified using spectroscopy and isolated node mapping. Collimators having tip radii ranging from 5 to 25 ..mu.. have been successfully drawn and tested.

Henley, F.J.; Oldham, W.G.

1982-10-01

177

Light charged-particle production from proton- and {alpha}-induced reactions on natSi at energies from 25 to 65 MeV  

SciTech Connect

A series of in-beam experiments using proton and {alpha}-particle projectiles on natSi target has been performed at the Louvain-la-Neuve Cyclotron facility. Inclusive data of double-differential and differential cross sections, as well as total cross sections of all possible light charged particles emitted (p, d, t, 3He, {alpha}) were measured. The data are compared with the predictions of the nuclear-reaction code TALYS. A detailed discussion of the model calculations and the modifications required to improve the description of the data is presented.

Demetriou, P. [Institute of Nuclear Physics, NCSR 'Demokritos', 153.10 Athens (Greece); Institut de Physique Nucleaire, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Dufauquez, Ch.; El Masri, Y. [Institut de Physique Nucleaire, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Koning, A. J. [Nuclear Research and Consultancy Group NRG, P.O. 25, NL-1755 ZG Petten (Netherlands)

2006-04-26

178

Alpha particle response characterization of CdZnTe  

SciTech Connect

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

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

2001-06-28

179

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

180

Coherent intense resonant laser pulses lead to interference in the time domain seen in the spectrum of the emitted particles  

NASA Astrophysics Data System (ADS)

The dynamics of atomic levels resonantly coupled by a coherent and intense short high-frequency laser pulse is discussed and it is advocated that this dynamics is sensitively probed by measuring the spectra of the particles emitted. It is demonstrated that the time envelope of this laser pulse gives rise to two waves emitted with a time delay with respect to each other at the rising and falling sides of the pulse, which interfere in the time domain. By computing numerically and analyzing explicitly analytically a showcase example of sequential two-photon ionization of an atom by resonant laser pulses, we argue that this dynamic interference should be a general phenomenon in the spectroscopy of strong laser fields. The emitted particles do not have to be photoelectrons. Our results allow us also to interpret the already studied resonant Auger effect of an atom by intense free-electron laser pulses, and also to envisage experiments in which photons are emitted.

Demekhin, Philipp V.; Cederbaum, Lorenz S.

2012-12-01

181

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

182

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.

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

2008-01-01

183

Alpha particle loss in TFTR deuterium-tritium plasmas with reversed magnetic shear  

SciTech Connect

The confinement and loss of fusion alpha particles are examined for reversed magnetic shear plasmas in TFTR. Such plasmas, with high central q and non-monotonic q profiles can exhibit remarkably reduced energy and particle transport of the thermal ions. However, these same conditions are theoretically predicted to produce high levels of stochastic ripple loss of suprathermal particles, which may reduce the efficiency of plasma heating by the alpha particles and other heating schemes involving fast ions. This paper presents calculations of guiding-center code alpha particle orbit loss from deuterium-tritium (DT) simulations of TFTR deuterium-only experiments. They are compared to results of measurements made in DT reversed shear plasmas of both the confined alpha particle distribution and the alpha particles lost from the plasma. Large fast particle losses have also been found in reversed shear ITER simulations (up to 20%) and from measurements of triton burnup in reversed shear experiments on JT-60U (12%).

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

1997-06-01

184

The formation of ultra-fine particles during ozone-initiated oxidations with terpenes emitted from natural paint  

Microsoft Academic Search

The formation of secondary products during the ozone-initiated oxidations with biogenic VOCs emitted from natural paint was investigated in this study. Mass spectrometry and infrared spectroscopy measurements have shown that the major components of gas-phase chemicals emitted from natural paint are monoterpenes including ?- and ?-pinenes, camphene, p-cymene, and limonene. A significant formation of gaseous carbonyl products and nano-sized particles

Rheo B. Lamorena; Sang-Guen Jung; Gwi-Nam Bae; Woojin Lee

2007-01-01

185

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

SciTech Connect

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

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

1994-03-01

186

Lifetime-based discrimination between spectrally matching vis and NIR emitting particle labels and probes  

NASA Astrophysics Data System (ADS)

Increasing the information content from bioassays which requires robust and efficient strategies for the detection of multiple analytes or targets in a single measurement is an important field of research, especially in the context of meeting current security and health concerns. An attractive alternative to spectral multiplexing, which relies on fluorescent labels excitable at the same wavelength, yet sufficiently differing in their emission spectra or color presents lifetime multiplexing. For this purpose, we recently introduced a new strategy based on "pattern-matching" in the lifetime domain, which was exemplary exploited for the discrimination between organic dyes and quantum dot labels revealing multi-exponential decay kinetics and allowed quantification of these labels. Meanwhile, we have succeeded in extending this lifetime multiplexing approach to nanometer-sized particle labels and probes absorbing and emitting in the visible (vis) and near-infrared (NIR) spectral region. Here, we present a first proof-of-principle of this approach for a pair of NIR-fluorescent particles. Each particle is loaded with a single organic dye chosen to display very similar absorption and emission spectra, yet different fluorescence decay kinetics. Examples for the lifetime-based distinction between pairs of these fluorescent nanoparticles in solution and in cells are presented. The results underline the potential of fluorescenc lifetime multiplexing in life science and bioanalysis.

Hoffmann, K.; Behnke, T.; Resch-Genger, U.; Drescher, D.; Kneipp, J.

2011-02-01

187

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

Microsoft Academic Search

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

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

2005-01-01

188

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

Microsoft Academic Search

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

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

2005-01-01

189

Self-consistent analysis of alpha-particle heating of a fast-solenoid plasma  

Microsoft Academic Search

A method is formulated to describe the development of the alpha particles produced by fusion in a slender cylindrical plasma column that includes a fusion source and nonuniform thermalization. A numerical technique is presented which makes it possible to determine in a fully self-consistent manner the alpha-particle and background-plasma behavior in the case where the alpha particles transfer energy to

H. J. Willenberg

1979-01-01

190

Enhanced production of low energy electrons by alpha particle impact  

PubMed Central

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

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

2011-01-01

191

Enhanced production of low energy electrons by alpha particle impact.  

PubMed

Radiation damage to living tissue stems not only from primary ionizing particles but to a substantial fraction from the dissociative attachment of secondary electrons with energies below the ionization threshold. We show that the emission yield of those low energy electrons increases dramatically in ion-atom collisions depending on whether or not the target atoms are isolated or embedded in an environment. Only when the atom that has been ionized and excited by the primary particle impact is in immediate proximity of another atom is a fragmentation route known as interatomic Coulombic decay (ICD) enabled. This leads to the emission of a low energy electron. Over the past decade ICD was explored in several experiments following photoionization. Most recent results show its observation even in water clusters. Here we show the quantitative role of ICD for the production of low energy electrons by ion impact, thus approaching a scenario closer to that of radiation damage by alpha particles: We choose ion energies on the maximum of the Bragg peak where energy is most efficiently deposited in tissue. We compare the electron production after colliding He(+) ions on isolated Ne atoms and on Ne dimers (Ne(2)). 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; Schffler, Markus; Trinter, Florian; Waitz, Markus; Voigtsberger, Jrg; Sann, Hendrik; Meckel, Moritz; Stuck, Christian; Lenz, Ute; Odenweller, Matthias; Neumann, Nadine; Schssler, 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-Bcking, Horst; Drner, Reinhard

2011-07-05

192

A self-consistent theory of collective alpha particle losses induced by Alfvenic turbulence  

SciTech Connect

The nonlinear dynamics of kinetic Alfven waves, resonantly excited by energetic ions/alpha particles, is investigated. It is shown that {alpha}-particles govern both linear instability and nonlinear saturation dynamics, while the background MHD turbulence results only in a nonlinear real frequency shift. The most efficient saturation mechanism is found to be self-induced profile modification. Expressions for the fluctuation amplitudes and the {alpha}-particle radial flux are self-consistently derived. The work represents the first self-consistent, turbulent treatment of collective {alpha}-particle losses by Alfvenic fluctuations.

Biglari, H. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Diamond, P.H. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

1992-01-01

193

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

194

Detection of lost alpha particle by concealed lost ion probe  

SciTech Connect

Full orbit-following calculation is performed for the final orbit of the lost alpha particles, showing some orbits escaping from the last closed flux surface could be detected by a concealed lost ion probe (CLIP) installed under the shadow of the original first wall surface. While both passing and trapped orbits hit the same wall panel, detecting a trapped orbit by the CLIP is easier than detecting passing orbits. Whether the final orbit is detected or not is determined by the position of the reflection point. The CLIP successfully detects the trapped orbits, which are reflected before they hit to a first wall. Then the pitch angles of the orbits at the CLIP are close to and smaller than 90 deg. Optimization of the position of the CLIP in terms of broader detection window is investigated.

Okamoto, A.; Kitajima, S.; Sasao, M. [Department of Quantum Science and Energy Engineering, Tohoku University, Sendai 980-8579 (Japan); Isobe, M. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)

2010-10-15

195

Detection of lost alpha particle by concealed lost ion probe.  

PubMed

Full orbit-following calculation is performed for the final orbit of the lost alpha particles, showing some orbits escaping from the last closed flux surface could be detected by a concealed lost ion probe (CLIP) installed under the shadow of the original first wall surface. While both passing and trapped orbits hit the same wall panel, detecting a trapped orbit by the CLIP is easier than detecting passing orbits. Whether the final orbit is detected or not is determined by the position of the reflection point. The CLIP successfully detects the trapped orbits, which are reflected before they hit to a first wall. Then the pitch angles of the orbits at the CLIP are close to and smaller than 90. Optimization of the position of the CLIP in terms of broader detection window is investigated. PMID:21033838

Okamoto, A; Isobe, M; Kitajima, S; Sasao, M

2010-10-01

196

Microscopic approach to the alpha-particle-nucleus optical potential  

NASA Astrophysics Data System (ADS)

A microscopic model for the alpha-particle-nucleus optical potential is presented and applied to ?-40Ca scattering. Starting with the M3Y force as the basic nucleon-nucleon interaction, the single-channel contribution to the optical potential is calculated by means of the fish-bone model which treats the antisymmetrization between the projectile and the target nucleus in an approximate way. The applicability of the fish-bone model to the ?-40Ca system is tested by comparison of resonating group calculations with fish-bone model calculations. The potential terms arising from the coupling of the elastic channel to other reaction channels have been calculated in the framework of the nuclear structure approach using random-phase approximation transition densities for intermediate excited states. The elastic scattering cross sections calculated from the microscopic potentials reproduce gross structures of the experimental data. However, the model cannot account for the whole absorption.

Leeb, H.; Osterfeld, F.

1985-09-01

197

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

198

Portable alpha spectrometer.  

PubMed

Many portable devices have been designed to detect ?-rays or alpha and beta particles. Most of the ?-particle detectors give the total count as a result, without identifying the radionuclides existing in the sample. The development of a device allowing rapid and straightforward ?-particle spectrometry would be very useful for detecting the radioactive contents of unknown samples. This work describes the construction of a portable device using silicon semiconductor detectors designed to rapidly detect and possibly identify alpha-emitting radionuclides. PMID:22405957

Martn Snchez, A; de la Torre Prez, J

2012-03-03

199

A CMOS integrated pulse mode alpha-particle counter for application in radon monitoring  

SciTech Connect

A custom integrated circuit for detecting alpha particles for application in the monitoring of radon has been designed and tested. The design uses the reverse-biased well to a substrate capacitance of a p-n junction in a conventional CMOS process as a sense capacitor for incident alpha particles. A simple CMOS inverter is used as an analog amplifier to detect the small potential change induced by an alpha-particle strike on the sense capacitor. The design was implemented in a 1.2-{micro}m conventional CMOS process with a sense capacitor area of 110 {micro}m{sup 2}. Tests carried out under vacuum conditions using a calibrated {sup 241}Am alpha-particle source showed an output voltage swing of {ge}2.0 V for an alpha event. The detector is also shown to have good immunity to noise and high-quantum efficiency for alpha particles.

Ahmed, A.; Walkey, D.J.; Tarr, N.G. [Carleton Univ., Ottawa, Ontario (Canada). Dept. of Electronics

1997-06-01

200

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

201

Estimating equivalent doses of internal radiation for the alpha-emitting radiopharmaceutical Astatine211  

Microsoft Academic Search

The integral activities of the ?-emitting radiopharmaceutical (RP) Astatine-211 are estimated using empirical data on the\\u000a pharmacokinetics when RP is introduced into the body. The obtained values are compared to the analogous estimates for RP 131I\\u000a in isotonic solution. Linear energy losses are estimated for different organs and tissues of the human body. The linear quadratic\\u000a model [1] is used

E. A. Dashko; E. V. Kizhaev; O. A. Yuminov; A. V. Tultaev; D. O. Eremenko; S. Yu. Platonov; O. V. Fotina; T. V. Pankratova

2010-01-01

202

A system for intercomparing standard solutions of beta-particle emitting radionuclides  

NASA Astrophysics Data System (ADS)

A system for intercomparing standard solutions of pure beta-particle emitting radionuclides is described. The CIEMAT/NIST technique of beta-particle efficiency tracing is based on establishing a parameter in a simple calculational model, using a 3H standard with comparable quenching. To produce a 3H-in-scintillator standard which is reasonably stable over the period of the measurements, we first standardized 3H-hexadecane solution by comparison with 3H-water standardized by gas counting. In the second phase of the work, the 3H-hexadecane solution was used to standardize 14C-hexadecane and 99Tc-tricaprylamine (TCA). Measurements were made under similar geometrical and quenching conditions for each radionuclide with a commercial scintillator and a conventional liquid-scintillation counter with two phototubes operating in coincidence. The technique was then tested at different sites in the area using a set of flame-sealed vials and state-of-the-art liquid-scintillation counters. Initial results for the 99Tc-TCA and the 1981 99Tc, Standard Reference Material (SRM) 4288 show an agreement to within 0.30%.

Calhoun, J. M.; Cessna, J. T.; Coursey, B. M.

1992-02-01

203

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.  

PubMed

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 alpha-pinene, beta-pinene, p-cymene, and limonene. Formation of ultra-fine particles (4.4-160 nm) was observed when ozone was injected into the chamber containing emitted monoterpenes from the air freshener. Particle number concentrations, particle mass concentrations, and surface concentrations were measured in time dependent experiments to describe the particle formation and growth within the chamber. The irritating secondary gaseous products formed during the ozone-initiated reactions include formaldehyde, acetaldehyde, acrolein, acetone, and propionaldehyde. Ozone concentration (50 and 100 ppb) and temperature (30 and 40 degrees C) significantly affect the formation of particles and gaseous products during the ozone-initiated reactions. The results obtained in this study provided an insight on the potential exposure of particles and irritating secondary products formed during the ozone-initiated reaction to passengers in confined spaces. PMID:18336999

Lamorena, Rheo B; Lee, Woojin

2008-02-07

204

EFFECTS OF PARTICLE EVAPORATION ON THE ANGULAR MOMENTUM OF THE EMITTING NUCLEUS FOR DEEP INELASTIC AND COMPOUND NUCLEAR REACTIONS  

SciTech Connect

A model is developed which allows one to calculate analytically the angular momentum removed, and the angular momentum misalignment created by the evaporation of light particles from an excited nucleus. The mass, temperature, and angular momentum of the emitting nucleus are explicitly considered. The formalism applies equally well to heavy ion and compound nuclear reactions.

Blau, S.K.; Moretto, L.G.

1980-09-01

205

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

SciTech Connect

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

Herrmann, Hans W.

1997-06-01

206

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

SciTech Connect

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

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

2006-04-01

207

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

Microsoft Academic Search

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

Bo Li; Xing Li; Nicolas Labrosse

2006-01-01

208

PRODUCTION BY ALPHA PARTICLES OF FUNCTIONALLY STABLE BROKEN CHROMOSOME ENDS IN MAIZE  

Microsoft Academic Search

Maize pollen, carrying the linked dominant markers I Sh 13z Wx, was ; irradiated with alpha particles from an external plutonium source, and was used ; to pollinate plants carrying the corresponding recessives. The resulting marker ; losses and endosperm mosaics were analyzed to ascertain whether alpha particles ; are capable of breaking chromosomes so as to generate functionally stable

Faberge

1959-01-01

209

Detection of Radon Emanation from the Crater Aristarchus by the Apollo 15 Alpha Particle Spectrometer  

Microsoft Academic Search

The alpha particle spectrometer aboard the Apollo 15 command\\/service module was designed to detect alpha particles from radon decay and to locate regions with unusual activity on the moon. A significant increase in radon-222 activity was detected from a region containing the crater Aristarchus. The result is interpreted as probably indicating internal activity at the site. By analogy with terrestrial

Paul Gorenstein; Paul Bjorkholm

1973-01-01

210

{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

211

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

2011-12-12

212

First Gamma-Ray Measurements of Fusion Alpha Particles in JET Trace Tritium Experiments  

Microsoft Academic Search

Gamma-ray spectra from nuclear reactions between fusion-born alpha (alpha) particles and Be impurities were measured for the first time in deuterium-tritium plasmas in the Joint European Torus. The time dependence of the measured spectra allowed the determination of the density evolution of fast alpha particles. Correlation between the decay time of the gamma-ray emission and the plasma parameters in different

V. G. Kiptily; Yu. F. Baranov; R. Barnsley; L. Bertalot; N. C. Hawkes; A. Murari; S. Popovichev; S. E. Sharapov; D. Stork; V. Yavorskij

2004-01-01

213

An accurate method to measure alpha-emitting natural radionuclides in atmospheric filters: Application in two NORM industries  

NASA Astrophysics Data System (ADS)

In this work, an accurate method for the measurement of natural alpha-emitting radionuclides from aerosols collected in air filters is presented and discussed in detail. The knowledge of the levels of several natural alpha-emitting radionuclides (238U, 234U, 232Th, 230Th, 228Th, 226Ra and 210Po) in atmospheric aerosols is essential not only for a better understanding of the several atmospheric processes and changes, but also for a proper evaluation of the potential doses, which can inadvertently be received by the population via inhalation.The proposed method takes into account the presence of intrinsic amounts of these radionuclides in the matrices of the quartz filters used, as well as the possible variation in the humidity of the filters throughout the collection process. In both cases, the corrections necessary in order to redress these levels have been evaluated and parameterized. Furthermore, a detailed study has been performed into the optimisation of the volume of air to be sampled in order to increase the accuracy in the determination of the radionuclides.The method as a whole has been applied for the determination of the activity concentrations of U- and Th-isotopes in aerosols collected at two NORM (Naturally Occurring Radioactive Material) industries located in the southwest of Spain. Based on the levels found, a conservative estimation has been performed to yield the additional committed effective doses to which the workers are potentially susceptible due to inhalation of anthropogenic material present in the environment of these two NORM industries.

Lozano, R. L.; Bolvar, J. P.; San Miguel, E. G.; Garca-Tenorio, R.; Gzquez, M. J.

2011-12-01

214

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

SciTech Connect

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

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

2005-05-24

215

Evolution of trace gases and particles emitted by a chaparral fire in California  

NASA Astrophysics Data System (ADS)

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 hectare prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009. We also measured physical and chemical changes that occurred in the isolated downwind plume in the first ~4 h after emission. The measurements were carried out onboard a Twin Otter aircraft outfitted with an airborne Fourier transform infrared spectrometer (AFTIR), aerosol mass spectrometer (AMS), single particle soot photometer (SP2), nephelometer, LiCor CO2 analyzer, a chemiluminescence ozone instrument, and a wing-mounted meteorological probe. Our measurements included: CO2; CO; NOx; NH3; non-methane organic compounds; organic aerosol (OA); inorganic aerosol (nitrate, ammonium, sulfate, and chloride); aerosol light scattering; refractory black carbon (rBC); and ambient temperature, relative humidity, barometric pressure, and three-dimensional wind velocity. The molar ratio of excess O3 to excess CO in the plume (?O3/?CO) increased from -5.13 (1.13) 10-3 to 10.2 (2.16) 10-2 in ~4.5 h following smoke emission. Excess acetic and formic acid (normalized to excess CO) increased by factors of 1.73 0.43 and 7.34 3.03 (respectively) over the same time since emission. Based on the rapid decay of C2H4 we infer an in-plume average OH concentration of 5.27 (0.97) 106 molec cm-3, consistent with previous studies showing elevated OH concentrations in biomass burning plumes. Ammonium, nitrate, and sulfate all increased over the course of 4 h. The observed ammonium increase was a factor of 3.90 2.93 in about 4 h, but accounted for just ~36% of the gaseous ammonia lost on a molar basis. Some of the gas phase NH3 loss may have been due to condensation on, or formation of, particles below the AMS detection range. NOx was converted to PAN and particle nitrate with PAN production being about two times greater than production of observable nitrate in the first ~4 h following emission. The excess aerosol light scattering in the plume (normalized to excess CO2) increased by a factor of 2.50 0.74 over 4 h. The increase in light scattering was similar to that observed in an earlier study of a biomass burning plume in Mexico where significant secondary formation of OA closely tracked the increase in scattering. In the California plume, however, ?OA/?CO2 decreased sharply for the first hour and then increased slowly with a net decrease of ~20% over 4 h. The fraction of thickly coated rBC particles increased up to ~85% over the 4 h aging period. Decreasing OA accompanied by increased scattering/particle coating in initial aging may be due to a combination of particle coagulation and evaporation processes. Recondensation of species initially evaporated from the particles may have contributed to the subsequent slow rise in OA. We compare our results to observations from other plume aging studies and suggest that differences in environmental factors such as smoke concentration, oxidant concentration, actinic flux, and RH contribute significantly to the variation in plume evolution observations.

Akagi, S. K.; Craven, J. S.; Taylor, J. W.; McMeeking, G. R.; Yokelson, R. J.; Burling, I. R.; Urbanski, S. P.; Wold, C. E.; Seinfeld, J. H.; Coe, H.; Alvarado, M. J.; Weise, D. R.

2012-02-01

216

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

SciTech Connect

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

Ozaki, T.; Goncharov, P.; Sudo, S.; Tamura, N. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Veschev, E. [Graduate University for Advanced Studies, Hayama, Kanagawa, 240-0193 (Japan)

2008-03-12

217

Preliminary study of the transport and distribution of radium, radon and their alpha-emitting daughters using nuclear emulsions and polonium-210. Final report  

Microsoft Academic Search

Semi-quantitative Po-210 measurements were made on near surface soil samples near known uranium ore deposits and on closely related diamond drill cores. The physical distribution of uranium and some of its alpha emitting daughter products in these samples was studied qualitatively using alpha sensitive nuclear emulsions. These nuclear emulsion plates suggest that U-238 and its long lived daughters U-234, Th-230

L. R. Stieff; I. L. Balkissoon; F. M. Barbera

1981-01-01

218

Evolution of trace gases and particles emitted by a chaparral fire in California  

NASA Astrophysics Data System (ADS)

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 ha prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009. We also measured post-emission chemical changes in the isolated downwind plume for ~4 h of smoke aging. The measurements were carried out on board a Twin Otter aircraft outfitted with an airborne Fourier transform infrared spectrometer (AFTIR), aerosol mass spectrometer (AMS), single particle soot photometer (SP2), nephelometer, LiCor CO2 analyzer, a chemiluminescence ozone instrument, and a wing-mounted meteorological probe. Our measurements included: CO2; CO; NOx; NH3; non-methane organic compounds; organic aerosol (OA); inorganic aerosol (nitrate, ammonium, sulfate, and chloride); aerosol light scattering; refractory black carbon (rBC); and ambient temperature, relative humidity, barometric pressure, and three-dimensional wind velocity. The molar ratio of excess O3 to excess CO in the plume (?O3/?CO) increased from -0.005 to 0.102 in 4.5 h. Excess acetic and formic acid (normalized to excess CO) increased by factors of 1.7 0.4 and 7.3 3.0 (respectively) over the same aging period. Based on the rapid decay of C2H4 we infer an in-plume average OH concentration of 5.3 (1.0) 106 molecules cm-3, consistent with previous studies showing elevated OH concentrations in biomass burning plumes. Ammonium, nitrate, and sulfate all increased with plume aging. The observed ammonium increase was a factor of 3.9 2.6 in about 4 h, but accounted for just ~36 % of the gaseous ammonia lost on a molar basis. Some of the gas phase NH3 loss may have been due to condensation on, or formation of, particles below the AMS detection range. NOx was converted to PAN and particle nitrate with PAN production being about two times greater than production of observable nitrate over a 4 h aging period. The excess aerosol light scattering in the plume (normalized to excess CO2) increased by a factor of 2.3 0.7 over 4 h. The increase in light scattering was similar to that observed in an earlier study of a biomass burning plume in Mexico where significant secondary formation of OA closely tracked the increase in scattering. In the California plume, however, ?OA/?CO2 decreased sharply for the first hour and then increased slowly with a net decrease of ~24 % over 4 h. The fraction of thickly coated rBC particles increased almost twofold over the 4 h aging period. Decreasing OA accompanied by increased scattering/coating in the initial aging may be due to a combination of particle coagulation and evaporation processes. Recondensation of species initially evaporated from the particles may have contributed to the subsequent slow rise in OA. We compare our results to observations from other plume aging studies and suggest that differences in environmental factors such as smoke concentration, oxidant concentration, actinic flux, and RH contribute significantly to the variation in plume evolution observations.

Akagi, S. K.; Craven, J. S.; Taylor, J. W.; McMeeking, G. R.; Yokelson, R. J.; Burling, I. R.; Urbanski, S. P.; Wold, C. E.; Seinfeld, J. H.; Coe, H.; Alvarado, M. J.; Weise, D. R.

2011-08-01

219

The microdosimetry of lymphocytes irradiated by alpha-particles.  

PubMed

Although the concept of absorbed dose is commonly used in radiation biology as a parameter for comparing the toxic effect of different levels of radiation on a system, there are situations where the absorbed dose by itself is inadequate, and additional dose distribution information is required to explain the observed biological effects. A good example is the irradiation of cells by alpha-particles. This paper reports the use of internal microdosimetry techniques to reinvestigate the dosimetry to two very similar experiments with apparently contradictory dose-response results. Yields of dicentric chromosome aberrations induced in human blood lymphocytes following in vitro exposure to dissolved americium or plutonium at two separate laboratories produced linear dose-response functions, but the slopes of the best-fit straight lines differed by a factor of 12. Our microdosimetric analysis showed the results of one experiment to be inconsistent with a uniform distribution of activity. It also showed that the difference in slope could be attributed to differences in particulate size and spatial distribution as a result of dissimilarities in procedures used for preparing the actinide solutions. PMID:6978320

Fisher, D R; Harty, R

1982-03-01

220

Stopping power for alpha particles in hot dense Au plasmas  

NASA Astrophysics Data System (ADS)

Self-consistent calculations of the stopping power for alpha particles in hot dense Au plasmas are performed in a wide projectile energy range with a fixed density ?Au = 19.3 g cm?3 and the electron temperature range from 0.4 to 5 keV on the basis of the relativistic ion-sphere model. All the mechanisms, which have strong influences on stopping power, are discussed in detail. The distribution of the free electron velocity component is found to be much flatter than the Maxwellian distribution due to the strong electrostatic field within the ion sphere in the hot dense plasmas, which results in the suppression of the stopping mechanism by plasma polarization and close collision for a projectile energy below 1 MeV u?1. The influence of inelastic scattering is considerably weakened due to the strong neutralization from the impact excitation, ionization and their reverse processes almost in the entire energy range below 10 MeV u?1 although the contribution of each process is quite large. Nuclear stopping is found to increase with the temperature. Our calculations are compared with other models and some explanations are presented for the difference between our results and other models. The Bethe equation is found to overestimate the contribution of inelastic processes by at least 10%. Different mechanisms are found to play their role in different energy ranges and all the mechanisms should be considered in order to get reliable data of stopping power.

He, Bin; Wang, Jian-Guo

2013-09-01

221

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

222

Treatment of neuroblastoma meningeal carcinomatosis with intrathecal application of alpha-emitting atomic nanogenerators targeting disialo-ganglioside GD2.  

PubMed

Labeling of specific antibodies with bifunctional chelated Actinium-225 ((225)Ac; an alpha generator) allows the formation of new, highly potent and selective alpha-emitting anticancer drugs. We synthesized and evaluated a radioimmunoconjugate based on 3F8, an IgG(3) antibody that specifically binds to ganglioside GD2, which is overexpressed by many neuroectodermal tumors including neuroblastoma. The (225)Ac-1,4,7,10-tetra-azacylododecane (DOTA)-3F8 construct was evaluated for radiochemical purity and sterility, immunoreactivity, cytotoxicity in vitro, induction of apoptosis on GD2-positive cells, as well as for pharmacological biodistribution and metabolism of the (225)Ac generator and its daughters in a nude mouse xenograft model of neuroblastoma. The (225)Ac-3F8 showed an IC(50) of 3 Bq/ml (80 pCi/ml) on the neuroblastoma cell line, NMB7, in vitro. Apoptosis of these cells was not observed. Biodistribution in mice showed specific targeting of a subcutaneous tumor; there was redistribution of the (225)Ac daughter nuclides mainly from blood to kidneys and to small intestine. Toxicity was examined in cynomolgus monkeys. Monkeys injected with 1 to 3 doses of intrathecal (225)Ac-3F8 radioimmunoconjugate (80 to 150 kBq/kg total dose) did not show signs of toxicity based on blood chemistry, complete blood counts, or by clinical evaluations. Therapeutic efficacy of intrathecal (225)Ac-3F8 was studied in a nude rat xenograft model of meningeal carcinomatosis. The (225)Ac-3F8 treatment improved survival 2-fold from 16 to 34 days (P = 0.01). In conclusion, in vivo alpha generators targeted by 3F8 warrant additional study as a possible new approach to the treatment of carcinomatous meningitis. PMID:15501978

Miederer, Matthias; McDevitt, Michael R; Borchardt, Paul; Bergman, Ira; Kramer, Kim; Cheung, Nai-Kong V; Scheinberg, David A

2004-10-15

223

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

SciTech Connect

The resonant nuclear reactions D(..cap alpha..,..gamma..)/sup 6/Li, /sup 6/Li(..cap alpha..,..gamma..)/sup 10/B, and /sup 7/Li(..cap alpha..,..gamma..)/sup 11/B are examined as diagnostics of fast-alpha-particle confinement in tokamak plasmas. Gamma rays from these resonant reactions with energies from 2.1 MeV to 9.2 MeV may be used to infer the alpha-particle population between energies of 0.4 MeV and 2.6 MeV. The ratio of these alpha-burnup reactions to the reactions T(D,..gamma..)/sup 5/He and /sup 3/He(D,..gamma..)/sup 5/Li provides a technique for the measurement of alpha confinement.

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

1986-03-01

224

Counting particles emitted by stratospheric aircraft and measuring size of particles emitted by stratospheric aircraft. Final technical report, 1 May 1990-31 December 1992  

SciTech Connect

The ER-2 condensation nuclei counter (CNC) has been modified to reduce the diffusive losses of particles within the instrument. These changes have been successful in improving the counting efficiency of small particles at low pressures. Two techniques for measuring the size distributions of particles with diameters less than 0.17 micrometers have been evaluated. Both of these methods, the differential mobility analyzer (DMA) and the diffusion battery, have fundamental problems that limit their usefulness for stratospheric applications. The authors cannot recommend either for this application. Newly developed, alternative methods for measuring small particles include inertial separation with a low-loss critical orifice and thin-plate impactor device. This technique is now used to collect particles in the multisample aerosol collector housed in the ER-2 CNC-2, and shows some promise for particle size measurements when coupled with a CNC as a counting device. The modified focused-cavity aerosol spectrometer (FCAS) can determine the size distribution of particles with ambient diameters as small as about 0.07 micrometers. Data from this instrument indicates the presence of a nuclei mode when CNC-2 indicates high concentrations of particles, but cannot resolve important parameters of the distribution.

Wilson, J.C.

1994-04-01

225

Preparation of radioactive ''mixed'' waste samples for measurement of RCRA (Resource Conservation and Recovery Act) organic compounds. [Mixed waste containing alpha-, beta-, or gamma-emitting radionuclides  

Microsoft Academic Search

A radioactive ''mixed'' waste typically contains alpha-, beta-, or gamma-emitting radionuclides and varying quantities of semivolatile or volatile organic species, some or all of which may be named specifically by the Resource Conservation and Recovery Act (RCRA). Because there are no acceptable means available currently for disposing of these mixed wastes, they are presently stored above-ground in sealed drums. For

B. A. Tomkins; J. E. Caton

1987-01-01

226

Alpha-particle Monte Carlo simulation for microdosimetric calculations using a commercial spreadsheet.  

PubMed

Alpha-particle emitters are currently being evaluated in the treatment of cancer. Because of the short range and high linear energy transfer (LET) of most therapeutic alpha-particle emitters, there are significant stochastic variations in the energy deposited within the cellular nucleus. Hence microdosimetric spectra are often necessary to interpret biological endpoints. However, alpha-particle microdosimetric codes are not readily available. In this paper, we describe how a commercial spreadsheet may be used to perform a Monte Carlo simulation of alpha-particle transport. Subsequently, this information is used to determine the distribution of path lengths, energy deposited, and specific energy for a single alpha-particle traversal through the cell nucleus. These data may then be used to determine microdosimetric parameters for multiple alpha-particle emissions. In our analysis, comparison of the first and second moments of the single-event spectra with previously published data show agreement on the order of a few per cent. These small discrepancies are due to differences in interpolation of stopping powers between the various algorithms. Thus, the spreadsheet Monte Carlo method represents a simple and efficient method to calculate single-event spectra for alpha-particle emitters. Copies of the spreadsheet are available from the corresponding author upon request. PMID:17374919

Roeske, John C; Hoggarth, Mark

2007-03-12

227

Alpha-particle Monte Carlo simulation for microdosimetric calculations using a commercial spreadsheet  

NASA Astrophysics Data System (ADS)

Alpha-particle emitters are currently being evaluated in the treatment of cancer. Because of the short range and high linear energy transfer (LET) of most therapeutic alpha-particle emitters, there are significant stochastic variations in the energy deposited within the cellular nucleus. Hence microdosimetric spectra are often necessary to interpret biological endpoints. However, alpha-particle microdosimetric codes are not readily available. In this paper, we describe how a commercial spreadsheet may be used to perform a Monte Carlo simulation of alpha-particle transport. Subsequently, this information is used to determine the distribution of path lengths, energy deposited, and specific energy for a single alpha-particle traversal through the cell nucleus. These data may then be used to determine microdosimetric parameters for multiple alpha-particle emissions. In our analysis, comparison of the first and second moments of the single-event spectra with previously published data show agreement on the order of a few per cent. These small discrepancies are due to differences in interpolation of stopping powers between the various algorithms. Thus, the spreadsheet Monte Carlo method represents a simple and efficient method to calculate single-event spectra for alpha-particle emitters. Copies of the spreadsheet are available from the corresponding author upon request.

Roeske, John C.; Hoggarth, Mark

2007-04-01

228

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

SciTech Connect

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

Funaki, Y. [Institute of Physics, University of Tsukuba, Tsukuba 305-8571 (Japan); Yamada, T. [Laboratory of Physics, Kanto Gakuin University, Yokohama 236-8501 (Japan); Tohsaki, A. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 567-0047 (Japan); Horiuchi, H. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 567-0047 (Japan); International Institute for Advanced Studies, Kizugawa 619-0225 (Japan); Roepke, G. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Schuck, P. [Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay F-91406 (France); Universite Paris-Sud, Orsay F-91505 (France); Laboratoire de Physique et Modelisation des Milieux Condenses, CNRS et Universite Joseph Fourier, 25 Av. des Martyrs, BP 166, F-38042 Grenoble Cedex 9 (France)

2010-08-15

229

Potential for irradiation of the lens and cataract induction by incorporated alpha-emitting radionuclides  

SciTech Connect

Data on the uptake and retention of Ra and Pu in ocular tissues are reviewed. These data were used to calculate alpha radiation doses to the lens of the eye for patients injected with /sup 224/Ra and for individuals exposed to one annual limit on intake (ALI) per year of /sup 224/Ra, /sup 226/Ra, /sup 228/Ra and /sup 239/Pu for a period of 50 y. On the basis of this analysis, it is concluded that the induction of lens opacity should not be the factor limiting intake of any radioisotope of Pu or for /sup 224/Ra or /sup 226/Ra. However, for /sup 228/Ra the dose lies within the range of doses received by /sup 224/Ra patients who have developed cataracts.

Taylor, D.M.; Thorne, M.C.

1988-02-01

230

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

231

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

SciTech Connect

The objective of our research work is to provide -- with the aid of biophysical models of radiation action -- information on human risks following exposure to radon alpha particles. The approach proposed consists of (1) developing appropriate models (parametric and non-parametric) for alpha radiation induction of relevant end points (survival, cellular transformation), (2) providing an accurate physical characterization of the particle tracks in terms of nanodosimetric distributions, (3) supporting the models by detailed, molecular studies of the direct and indirect effects of alpha particles on DNA. Activities in the second year of this project are described.

Not Available

1992-01-01

232

alpha-particle nuclear surface absorption below the Coulomb barrier in heavy nuclei  

SciTech Connect

An analysis of all available alpha-particle-induced reaction cross sections on nuclei within the mass number range 121<=A<=197, below the Coulomb barrier, is carried out. This analysis leads to an optical potential that describes the alpha-particle elastic scattering at low energies as well and both elastic-scattering and reaction data for 45<=A<=124. The energy dependence of the surface imaginary potential depth is proved to be essential for understanding alpha-particle interaction behavior below the Coulomb barrier.

Avrigeanu, M.; Avrigeanu, V. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, Post Office Box MG-6, R-077125 Bucharest-Magurele (Romania)

2010-07-15

233

`Lyman Alpha Emitting Galaxies as a Probe of the Young Universe'  

NASA Astrophysics Data System (ADS)

The Wide Field Camera 3 on board of the Hubble Space Telescope has enhanced our ability to observe galaxies at redshifts great than six, so far obtaining 100 likely candidate galaxies at z=7, 8. Future facilities are expected to probe galaxies a few magnitudes deeper, and also to spectroscopically confirm the redshifts of the existing candidates. One of the key predicted properties of young, metal poor galaxies in the high-redshift Universe are prominent nebular emission lines, dominated by hydrogen Lyman Alpha (Ly?). This makes the Ly? emission line an ideal target to search for and study high-redshift galaxies. However, during the epoch of reionization (EoR), the Ly? emission line may be difficult to observe, due to the large opacity of the intervening neutral intergalactic medium. In this talk I will argue that there are several effects that may boost the visibility of the Ly? flux during the EoR. These effects include: (i) source clustering, (ii) the `patchiness' of reionization, and (iii) radiative transfer through galactic outflows. These effects combined imply that the imprint of reionization on various statistics of Ly? selected galaxies may be more subtle than previously thought. In this context, I will discuss the most recent observations of high redshift galaxies that indicate that the Ly? flux from galaxies at z>6 is suppressed significantly more than expected from lower redshift observations.

Dijkstra, Mark

2012-07-01

234

Dose and dose rate effects of beta-particle emitting radioactive stents in a porcine model of restenosis  

Microsoft Academic Search

Background. Radioactive stents have been proposed as a means to prevent in-stent restenosis by inhibiting intimal proliferation with continuous low-dose irradiation.Objectives. The purpose of this study is to determine the effects of cumulative dose and dose-rate delivery on neointimal formation using 32P and 90Y beta-particle emitting radioactive stents in a porcine coronary model of restenosis.Methods and Materials. We compared the

Andrew J. Carter; Stephen Jenkins; William Sweet; Lynn Bailey; Russ Jones; Tim A. Fischell; Renu Virmani

1999-01-01

235

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

236

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

237

MIRD Pamphlet No. 22 (Unabridged): Radiobiology and Dosimetry of alpha-Particle Emitters for Targeted Radionuclide Therapy  

SciTech Connect

The potential of alpha-particle emitters to treat cancer has been recognized since the early 1900s. Advances in the targeted delivery of radionuclides, in radionuclide conjugation chemistry, and in the increased availability of alpha-emitters appropriate for clinical use have recently led to patient trials of alpha-particle-emitter labeled radiopharmaceuticals. Although alpha-emitters have been studied for many decades, their current use in humans for targeted therapy is an important milestone. The objective of this work is to review those aspects of the field that are pertinent to targeted alpha-particle-emitter therapy and to provide guidance and recommendations for human alpha-particle-emitter dosimetry.

Sgouros, George; Roeske, John C.; McDevitt, Michael S.; Palm, Stig; Allen, Barry J.; Fisher, Darrell R.; Brill, Bertrand A.; Song, Hong; Howell, R. W.; Akabani, Gamal

2010-02-28

238

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

NASA Astrophysics Data System (ADS)

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

France, Ralph Hayward, III

1997-11-01

239

mFISH analysis reveals complexity of chromosome aberrations in individuals occupationally exposed to internal plutonium: a pilot study to assess the relevance of complex aberrations as biomarkers of exposure to high-LET alpha particles.  

PubMed

We recently demonstrated that a significant proportion of apparently stable insertions induced after exposure to a mean of one alpha particle/cell, detected using three-color FISH, were part of larger unstable complexes when visualized by 24-color FISH. Interestingly, regardless of the long-term persistence capability of the cell, the complexity of each alpha-particle-induced complex appeared to be specific to the nuclear traversal of a single alpha particle. To assess whether aberrations of a similar complexity are observed in vivo and also to examine the usefulness of detecting such aberrations as a biomarker of chronic exposure to alpha particles, we have carried out a limited pilot study of Russian workers with large body burdens of alpha-particle-emitting plutonium. We found unstable cells containing non-transmissible complex aberrations in all of the plutonium-exposed subjects analyzed by mFISH. In addition, all of the complexes seen were consistent with those previously observed in vitro. Non-transmissible complex aberrations were more common than transmissible-type complexes, consistent with ongoing/chronic exposure, and insertions were dominant features of both types of complex. Accordingly, this preliminary study supports the proposal that aberration complexity and non-transmissibility are the major cytogenetic features of alpha-particle exposure that could potentially be exploited as a specific indicator of chronic exposures to high-LET alpha particles. PMID:15606304

Anderson, Rhona M; Tsepenko, Viktoria V; Gasteva, Galina N; Molokanov, Alexander A; Sevan'kaev, Aleksander V; Goodhead, Dudley T

2005-01-01

240

Sizes and Morphology of z=3.1 Lyman Alpha Emitting Galaxies in the Extended CDF-S  

NASA Astrophysics Data System (ADS)

Lyman Alpha Emitting galaxies LAEs seen at high redshift appear to be galaxies in the act of formation. They are currently the most promising candidates for the progenitors of typical spiral galaxies like the Milky Way. The LAEs tend to be younger, lower in mass, and less chemically evolved than the better-studied Lyman Break Galaxies LBGs. Wide-field ACS imaging allows us to study the physical properties of these objects at kpc scales to gain a better understanding of the interconnected processes of mergers and star formation that play fundamental roles in galaxy formation. We will use archival ACS images of the Extended Chandra Deep Field-South from GEMS, GOODS, and UDF to study the size and morphology of our sample of 162 Lyman Alpha Emitters at z=3.1, 47 of which have confirmed spectroscopic redshifts. We will perform the identical analysis on a sample of 34 spectroscopically confirmed Lyman Break Galaxies at 2.7

Gawiser, Eric

2007-07-01

241

Estimates of alpha particle heating in the solar wind inside 0.3 AU  

Microsoft Academic Search

Observations from the Helios plasma experiment (Rosenbauer et al., 1977) are used to determine the average temperature gradients of protons and alpha particles in the solar wind between 0.3 and 1 AU. It is found that He(2+) ions cool more slowly than adiabatically. The radial gradients of T(alpha) inside 0.3 AU are estimated. Evidence is found for continuous interplanetary alpha

K. M. Thieme; E. Marsch; H. Rosenbauer

1989-01-01

242

Fossil Alpha-Particle Recoil Tracks: A New Method of Age Determination  

Microsoft Academic Search

The discovery of a new type of fossil nuclear track in mica is reported. This track is produced by the recoil nucleus accompanying the alpha -particle decay of uranium and thorium impurities. The tracks are very short and can be seen with phase contrast microscopy. Measurement of fossil alpha -recoil track densities, coupled with determinations of the thorium and uranium

W. H. Huang; R. M. Walker

1967-01-01

243

Ambiguities in the optical-model analysis of alpha-particle scattering  

Microsoft Academic Search

The phase-equivalent discrete ambiguities in the complex potential parameters which are obtained from optical-model analysis of alpha-particle elastic scattering differential cross sections are examined. A detailed analysis of the scattering of 10.8 MeV alpha particles by 24Mg is used to illustrate the discussion of these ambiguities. In principle, one technique for the reduction of the ambiguities is the coupled-equations analysis

W. J. Thompson; G. E. Crawford; R. H. Davis

1967-01-01

244

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

245

alpha-particle nuclear surface absorption below the Coulomb barrier in heavy nuclei  

Microsoft Academic Search

An analysis of all available alpha-particle-induced reaction cross sections on nuclei within the mass number range 121<=A<=197, below the Coulomb barrier, is carried out. This analysis leads to an optical potential that describes the alpha-particle elastic scattering at low energies as well and both elastic-scattering and reaction data for 45<=A<=124. The energy dependence of the surface imaginary potential depth is

M. Avrigeanu; V. Avrigeanu

2010-01-01

246

Physical aspects of precise spectrometry of alpha-particles with silicon pn-junction detectors  

Microsoft Academic Search

Investigations of energy and charge losses have been carried out for silicon planar alpha-particle detectors. The detectors were manufactured by an advanced technology, using ion implantation and various annealing temperatures. A detailed analysis of the recombination processes in alpha-particle tracks with a high electron-hole density and a measurement procedure for the main parameters of charge carrier loss have been developed.

E. Verbitskaya; V. Eremin; N. Strokan; J. Kemmer; B. Schmidt; J. von Borany

1994-01-01

247

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

Microsoft Academic Search

This paper reports on alpha-particle populations that can significantly alter existing magnetohydrodynamic (MHD) instabilities in tokamaks through kinetic effects and coupling to otherwise stable shear Alfven waves. Resonances of the trapped alpha-particle precessional drift, with the usual ballooning mode diamagnetic frequency ({sub *i}\\/2) and the toroidicity-induced Alfven eigenmode (TAE), are considered. These are examined for noncircular tokamaks in the high-n

D. A. Spong; J. A. Holmes; J. N. LeBoeuf; D. J. Christenson

1990-01-01

248

Detection of radon emanation from the crater aristarchus by the apollo 15 alpha particle spectrometer.  

PubMed

The alpha particle spectrometer aboard the Apollo 15 command/service module was designed to detect alpha particles from radon decay and to locate regions with unusual activity on the moon. A significant increase in radon-222 activity was detected from a region containing the crater Aristarchus. The result is interpreted as probably indicating internal activity at the site. By analogy with terrestrial processes, increased radon emanation may be associated with the emission of other volatiles. PMID:17806295

Gorenstein, P; Bjorkholm, P

1973-02-23

249

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

Microsoft Academic Search

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

R. K. Appleyard

1949-01-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

251

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

SciTech Connect

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

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

2007-07-01

252

Differences Between Solar Wind Alpha Particle and Proton Temperatures at Times of Proton Temperature Depressions  

NASA Astrophysics Data System (ADS)

Using ACE SWEPAM measurements from February 5, 1998 through October 30, 2001 we have examined hourly averages of the solar wind alpha particle temperature TA and compared it to the proton temperature TP. The ratio TA/TP ranges from about 1 to 10, with the most probable value near 4, indicating that protons and alpha particles typically have the same thermal speed. We find that this ratio tends to vary with solar wind speed; ratios less than 4 are more common at lower speeds. In this study we investigate the character of the alpha particle temperature during intervals of depressed proton temperature. In general, the solar wind proton temperature increases with increasing flow speed. The temperature is considered depressed when it is much lower (by a factor of approximately 2) than the typical temperature observed at a given speed. For this work, we developed an expression for the expected proton temperature as a function of speed appropriate for the ACE level 2 data, and used this expression to identify intervals of unusually low proton temperature. When proton temperatures are lower than expected, we find that TA/TP tends toward values of 1. We conclude that proton temperature depressions usually have corresponding alpha particle temperature depressions, and the relative difference between typical and depressed temperatures is 4 times greater for alpha particles than for protons. We note that, similar to proton temperature depressions, alpha particle temperature depressions can serve as useful indicators of CME flows.

Steinberg, J. T.; Davenport, T. A.; Reisenfeld, D. B.; Skoug, R. M.

2002-12-01

253

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

254

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

SciTech Connect

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

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

1996-04-01

255

Observation of the alpha particle "Knock-On" neutron emission from magnetically confined DT fusion plasmas  

PubMed

Suprathermal fuel ions from alpha-particle knock-on collisions in fusion DT plasmas are predicted to cause a weak feature in the neutron spectrum of d+t-->alpha+n. The knock-on feature has been searched for in the neutron emission of high ( >1 MW) fusion-power plasmas produced at JET and was found using a magnetic proton recoil type neutron spectrometer of high performance. Measurement and predictions agree both in absolute amplitude and in plasma-parameter dependence, supporting the interpretation and model. Moreover, the results provide input to projecting alpha-particle diagnostics for future self-heated fusion plasmas. PMID:10991523

Kallne; Ballabio; Frenje; Conroy; Ericsson; Tardocchi; Traneus; Gorini

2000-08-01

256

Alpha particle destabilization of the toroidicity-induced Alfven eigenmodes  

Microsoft Academic Search

The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and\\/or trapped α-particles through the wave-particle resonances. Satisfying the resonance condition requires that the α-particle birth speed v{sub α} v{sub A}\\/2{vert bar}m-nq{vert bar}, where v{sub A} is the Alfven speed, m is the poloidal model number, and n is the

1990-01-01

257

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.

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

2007-01-01

258

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

Microsoft Academic Search

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

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

2000-01-01

259

Alfvnic instabilities driven by fusion generated alpha particles in ITER scenarios  

NASA Astrophysics Data System (ADS)

The stability of proposed ITER scenarios with respect to low-medium mode number Alfvnic instabilities driven by fusion-produced alpha particles is investigated by hybrid MHD-particle simulations. Three cases are considered: the monotonic safety factor scenario (SC2), the reversed-shear one (SC4) and a flat safety factor profile 'hybrid' scenario (SCH). All the three cases are found unstable, even though the mode growth rates are quite small. The investigation is extended to cases with larger drive, which could be realistically obtained because of a moderate increase in electron and bulk-ion temperatures as well as by inclusion of energetic particles produced by additional heating methods. It is shown that, in the SCH case, if the drive exceeds the reference value by a factor ~1.6, fast growing energetic-particle modes (EPMs) are driven unstable by the resonance with trapped alpha particles. The effects of nonlinear mode dynamics on the alpha-particle confinement at the reference drive are negligible for the SC2 and the SCH cases. For the SC4 scenario, some broadening of the alpha-particle pressure profile is observed, indicating inconsistency problems of the scenario itself. Simulations performed with increasing drive intensity show that a strong flattening of the alpha-particle pressure profile can occur in the inner plasma region for the SC2 case, while global confinement is not significantly affected. In the SC4 and SCH scenarios nonlinear effects are more pronounced in the outer portion of the discharge, where the modes are localized, with less impact on the on-axis pressure value with respect to the SC2 case. While for SCH such effects are observed only above the threshold for EPM destabilization, in the SC4 case significant alpha particle losses can occur even at moderately increased drive.

Vlad, G.; Briguglio, S.; Fogaccia, G.; Zonca, F.; Schneider, M.

2006-01-01

260

Direct decay of the GQR in 40Ca through alpha-particle emission  

NASA Astrophysics Data System (ADS)

Inelastic scattering of 40Ca on 40Ca at 50 MeV/A has been measured at the GANIL facility in coincidence with light charged particles. For the first time, the SPEG spectrometer was associated with 240 CsI(Tl) scintillators of the INDRA 4? array. The missing energy method, successfully used in previous experiments to study the nucleon decay of collective states is applied to the study of alpha-particle decay of the GQR. A significant direct decay branch by alpha-particles of the GQR in 40Ca is measured for the first time.

Fallot, M.; Scarpaci, J. A.; Frascaria, N.; Blumenfeld, Y.; Chbihi, A.; Chomaz, Ph.; Desesquelles, P.; Frankland, J.; Khan, E.; Laville, J. L.; Plagnol, E.; Pollacco, E. C.; Roussel-Chomaz, P.; Roynette, J. C.; Shrivastava, A.; Zerguerras, T.

2005-05-01

261

Gross alpha, gross beta activities and gamma emitting radionuclides composition of airborne particulate samples in an oceanic island  

NASA Astrophysics Data System (ADS)

The radiometric compositions of airborne particulate samples, collected weekly during a 4 years period (1 January 2000 till 31 December 2003) at a site located 310 m a.s.l. in Tenerife (Canary Islands), are analysed in this paper. To do this, measurements of gross alpha, gross beta, 7Be, 210Pb, 228Ac, 226Ra, 212Pb, 214Pb, 208Tl, 214Bi, 235U, 40K, 131I and 137Cs concentrations were carried out in 376 cellulose and polypropylene filters. The time variations of the different radionuclides concentrations have been discussed in relation with various meteorological factors and the mean values have been compared to those published in recent literature for other sites located at the same altitude but different latitudes. The weekly activities of 7Be correlated linearly with the 210Pb activities ( R=0.59). In disagreement with other published studies, the 7Be activities did not correlate ( R=-0.05) with the temperature and maximum values were not found during summer season. The gross beta activities showed correlations with the gross alpha ( R=0.72) and 210Pb activities ( R=0.52), but not with the 7Be ( R=0.16). The anthropogenic radionuclide 131I, emitted from a nearby hospital, was detected slightly above detection limits (1.7310 -6 Bq m -3) in 88 of the 210 weeks of measurement considered in this work. 137Cs was detected in 31 of those weeks. The 4-year average calculated for 7Be and 210Pb were 3 and 0.3 mBq m -3, respectively. These values are lower than those expected for a site at comparable latitude and altitude. In general, the radionuclides which appeared most frequently in the airborne particulate filters ( 7Be, 210Pb, 212Pb and 40K), did not correlate significantly with any of the meteorological parameters considered: rainfall, temperature, pressure, relative humidity, visibility, wind speed and direction. Therefore, no predictive model could be established with the available data as it has been done for continental sites. The long-range transport of aerosols from the Saharan desert showed to be an important source of 137Cs and 40K in the particulate filters after low-level atmospheric dust intrusions that reached the island.

Hernndez, F.; Hernndez-Armas, J.; Cataln, A.; Fernndez-Aldecoa, J. C.; Karlsson, L.

262

Alpha-Particle Decay Widths of Levels in (19)F.  

National Technical Information Service (NTIS)

Levels of /sup 19/F in the excitation region 4alpha)) reaction, using a recoil-coincidence technique to measure values of (Gamma)/sub (gamma)//(Gamma). The information obtained has been combined...

D. M. Pringle W. J. Vermeer

1989-01-01

263

To Stack or Not to Stack: Lessons from z=2.1 Lyman-Alpha Emitting Galaxies  

NASA Astrophysics Data System (ADS)

Lyman-alpha Emitting (LAE) galaxies have the lowest bolometric luminosity of any well-studied high redshift population and thus provide an ideal probe of the properties of typical high-redshift galaxies, but having such dim continua makes it difficult to study their spectral energy distributions (SEDs). It has therefore been a common procedure to stack the SEDs of many LAEs in order to enhance the signal-to-noise ratio. However, inconsistencies in the literature motivate a study of the validity of the stacking method for SED fitting. We match a sample of LAEs at z=2.1 discovered by the MUSYC collaboration (Guaita et al 2010) with the CANDELS (Grogin et al 2011; Koekemoer et al 2011) GOODS-S multi-wavelength catalog, which offers deep photometry for 18 of these LAEs. We create stacked SEDs using two methods: flux stacking, which takes the median of the flux values from the CANDELS SEDs at each wavelength, and image stacking, where the CANDELS images of the same LAEs are median-combined. To obtain the image stacked SED, SExtractor photometry is performed on the stacked galaxy images in each band. SED fitting is performed on the individual object and stacked SEDs with SpeedyMC (Acquaviva et al 2011). The SED fitting process allows us to infer physical properties including stellar mass, age and dust content. The considerable scatter in each property provides constraints on the nature of z = 2.1 LAEs that cannot be revealed by stacked SEDs. Nonetheless, we find good agreement between the median SED parameters of the 18 LAEs and the median flux-stacked estimate for the same sample. The median image stack, however, does not reproduce the galaxies' properties as a whole, questioning the validity of the image stacking method.

Vargas, Carlos J.; Bish, H.; Gawiser, E. J.; Acquaviva, V.; Finkelstein, S. L.; CANDELS; MUSYC

2013-01-01

264

TOF-SIMS measurements of the exhaust particles emitted from gasoline and diesel engine vehicles  

NASA Astrophysics Data System (ADS)

We obtained the detailed compositional information of diesel and gasoline exhaust particles, and discussed the possibility of the classification into each emission source. The intensities of Ca + and hydrocarbons were relatively high in the TOF-SIMS spectrum of the gasoline exhaust particles. The secondary ions such as NH 4+ and Si(CH 3) 3+ were strongly detected from the diesel exhaust particles. From TOF-SIMS images of each type of exhaust particles, Ca + of the gasoline exhaust particles and Si(CH 3) 3+ of diesel exhaust particles were strongly detected from the large particles with diameter of 0.3 ?m. From these results, the exhaust particles collected in the atmosphere near the traffic route can be classified by their origin by using TOF-SIMS information.

Tomiyasu, B.; Owari, M.; Nihei, Y.

2006-07-01

265

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

266

Photons and particles emitted from cold atmospheric-pressure plasma inactivate bacteria and biomolecules independently and synergistically.  

PubMed

Cold atmospheric-pressure plasmas are currently in use in medicine as surgical tools and are being evaluated for new applications, including wound treatment and cosmetic care. The disinfecting properties of plasmas are of particular interest, given the threat of antibiotic resistance to modern medicine. Plasma effluents comprise (V)UV photons and various reactive particles, such as accelerated ions and radicals, that modify biomolecules; however, a full understanding of the molecular mechanisms that underlie plasma-based disinfection has been lacking. Here, we investigate the antibacterial mechanisms of plasma, including the separate, additive and synergistic effects of plasma-generated (V)UV photons and particles at the cellular and molecular levels. Using scanning electron microscopy, we show that plasma-emitted particles cause physical damage to the cell envelope, whereas UV radiation does not. The lethal effects of the plasma effluent exceed the zone of physical damage. We demonstrate that both plasma-generated particles and (V)UV photons modify DNA nucleobases. The particles also induce breaks in the DNA backbone. The plasma effluent, and particularly the plasma-generated particles, also rapidly inactivate proteins in the cellular milieu. Thus, in addition to physical damage to the cellular envelope, modifications to DNA and proteins contribute to the bactericidal properties of cold atmospheric-pressure plasma. PMID:24068175

Lackmann, Jan-Wilm; Schneider, Simon; Edengeiser, Eugen; Jarzina, Fabian; Brinckmann, Steffen; Steinborn, Elena; Havenith, Martina; Benedikt, Jan; Bandow, Julia E

2013-09-25

267

Alpha particle destabilization of the toroidicity-induced Alfvn eigenmodes  

Microsoft Academic Search

The high-frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) (Phys. Fluids {bold 29}, 3695 (1986)) are shown to be driven unstable by the circulating and\\/or trapped α particles through the wave--particle resonances. Satisfying the resonance condition requires that the α-particle birth speed {ital v}{sub α}{ital v}{sub A}\\/2{vert bar}{ital m}-{ital nq}{vert bar}, where {ital v}{sub A} is the Alfven speed, {ital

C. Z. Cheng

1991-01-01

268

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

SciTech Connect

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

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

2002-03-15

269

Destabilization of planar lipid bilayers by. cap alpha. particles from polonium-210  

SciTech Connect

A system for measuring the interacton between ..cap alpha.. particles from /sup 210/Polonium and planar lipid bilayers is described. Membrane capacitance and conductance were simultaneously measured with a voltage clamp. A micrometer advance mechanism was used to control the position of a /sup 210/Polonium source with respect to a bowed-out bilayer. Conductance records showed an abrupt failure of the bilayer when the source was approximately 30 microns or less from the bilayer. Comparisons of conductance noise characteristics just prior to membrane breakage and noise characteristics with a source - bilayer separation of 50 microns or greater showed no difference. The range of the ..cap alpha.. particles inferred from observations of membrane failure is consistent with the expected maximum range of approximately 35 microns for ..cap alpha.. particles from the particular gold-covered source in water. The breakage mechanism is not directly peroxide-mediated as experiments with added peroxide alone did not show significant alterations. The breakdown of lipid bilayers by ..cap alpha.. particles may be analogous to the observations in a set of experiments which showed ..cap alpha.. particle destabilization of surfactant films in air. Evidence supports the hypothesis that free radicals generated in the bilayer, as opposed to aqueous solution free radicals, are the most important agent for bilayer destabilization.

Nelson, G.A.

1984-01-01

270

Energetic/alpha particle effects on MHD modes and transport  

SciTech Connect

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

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

1995-01-01

271

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

PubMed

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

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

2011-11-11

272

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

273

TOF-SIMS measurements of the exhaust particles emitted from gasoline and diesel engine vehicles  

Microsoft Academic Search

We obtained the detailed compositional information of diesel and gasoline exhaust particles, and discussed the possibility of the classification into each emission source. The intensities of Ca+ and hydrocarbons were relatively high in the TOF-SIMS spectrum of the gasoline exhaust particles. The secondary ions such as NH4+ and Si(CH3)3+ were strongly detected from the diesel exhaust particles. From TOF-SIMS images

B. Tomiyasu; M. Owari; Y. Nihei

2006-01-01

274

Confinement of fusion alpha-particles in JET hollow current equilibrium  

Microsoft Academic Search

The effect of a toroidal current hole on the first orbit (FO) loss and on the collisional loss of alpha particles in JET is investigated. Numerical results of predictive three-dimensional Fokker-Planck modelling of the distribution function of D-T fusion alphas in hollow current JET discharges are presented. If the current hole region is kept reasonably small, it induces only a

V. Yavorskij; V. Goloborod'ko; K. Schoepf; S. E. Sharapov; C. D. Challis; S. Reznik; D. Stork

2003-01-01

275

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

PubMed

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

Sibbens, G; Pomm, S

276

Effect of alpha-particle irradiation on the electrical properties of n-type Ge  

NASA Astrophysics Data System (ADS)

Deep-level transient spectroscopy was used to investigate the effect of alpha particle irradiation on the electrical properties of n-type Ge. The samples were irradiated with alpha particles at room temperature using an americium-241 (Am-241) radionuclide source. The main defects introduced were found to be electron traps with energy levels at EC-0.38, EC-0.21, EC-0.20, EC-0.15, and EC-0.10 eV, respectively. The main defects in alpha particle irradiation are similar to those introduced by MeV electron irradiation, where the main defect is the E-center. A quadratic increase in concentration as a function of dose is observed.

Roro, K. T.; Janse van Rensburg, P. J.; Auret, F. D.; Coelho, S.

2009-12-01

277

Jet Nebulization of Prostaglandin E1 During Neonatal Mechanical Ventilation: Stability, Emitted Dose and Aerosol Particle Size  

PubMed Central

Background We have previously reported the safety of aerosolized PGE1 in neonatal hypoxemic respiratory failure. The aim of this study is to characterize the physicochemical properties of PGE1 solution, stability, emitted dose and the aerodynamic particle size distribution (APSD) of PGE1 aerosol in a neonatal ventilator circuit. Methods PGE1 was diluted in normal saline and physicochemical properties of the solution characterized. Chemical stability and emitted dose were evaluated during jet nebulization in a neonatal conventional (CMV) or high frequency (HFV) ventilator circuit by a High Performance Liquid Chromatography - Mass Spectrometry method. The APSD of the PGE1 aerosol was evaluated with a six-stage cascade impactor during CMV. Results PGE1 solution in normal saline had a low viscosity (0.9818 cP) and surface tension (60.8 mN/m) making it suitable for aerosolization. Little or no degradation of PGE1 was observed in samples from aerosol condensates, the PGE1 solution infused over 24 h, or the residual solution in the nebulizer. The emitted dose of PGE1 following jet nebulization was 3240% during CMV and 0.1% during HFV. The PGE1 aerosol had a mass median aerodynamic diameter of 1.4 m and geometric standard deviation of 2.9 with 90% of particles being < 4.0 m in size. Conclusion Nebulization of PGE1 during neonatal CMV or HFV is efficient and results in rapid nebulization without altering the chemical structure. On the basis of the physicochemical properties of PGE1 solution and the APSD of the PGE1 aerosol, one can predict predominantly alveolar deposition of aerosolized PGE1.

Sood, Beena G.; Peterson, Jennifer; Malian, Monica; Galli, Robert; Geisor-Walter, Maria; McKinnon, Jon; Sharp, Jody; Maddipati, Krishna Rao

2008-01-01

278

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

NASA Astrophysics Data System (ADS)

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

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

2005-09-01

279

Measurement of number and size distribution of particles emitted from a mid-sized transportation multipoint port fuel injection gasoline engine  

Microsoft Academic Search

This study was carried out to characterize the engine-exhaust particulate emissions from a typical multipoint port fuel injection gasoline engine used in transportation sector. Though gasoline engine showed no visible tail pipe emissions yet its particle concentrations were comparable to mineral diesel, particularly at high engine loads. Average sizes of particles emitted in gasoline exhaust are found to be way

Tarun Gupta; Abhishek Kothari; Dhananjay Kumar Srivastava; Avinash Kumar Agarwal

2010-01-01

280

delta 9-(16 alpha-/sup 125/I)iodo-19-nortestosterone: a gamma-emitting photoaffinity label for the progesterone receptor  

SciTech Connect

We have synthesized 16 alpha-iodo-4,9-estradien-17 beta-ol-3-one (delta 9-16 alpha-iodo-19-nortestosterone (delta 9-INT)) labeled with 125I (delta 9-(16 alpha-125I)INT) to provide a new gamma-emitting photoaffinity ligand for the progesterone receptor that has many advantages over the currently available (3H)R5020. We have characterized the interaction of delta 9-(16 alpha-125I)INT with the rabbit uterine progesterone receptor and have demonstrated the usefulness of this compound for studies of receptor structure. The binding of 2 nM (3H)progesterone to receptor in rabbit uterine cytosol was specifically competed for by 19-nortestosterone, 16 alpha-iodo-19-nortestosterone, and delta 9-INT. Scatchard analysis demonstrated that delta 9-(16 alpha-125I)INT and (3H)progesterone estimated the same number of binding sites in rabbit uterine cytosol, with a Kd for delta 9-(16 alpha-125I)INT of about 2.7 nM. The binding of delta 9-(16 alpha-125I)INT was inhibited by both progesterone and R5020, whereas testosterone, estradiol, and 5 alpha-dihydrotestosterone were ineffective. In cytosol, delta 9-(16 alpha-125I)INT covalently labeled the same mol wt receptor forms as (3H)R5020. Although the efficiency of cross-linking was similar for (3H)R5020 (3%) and delta 9-(16 alpha-125I)INT (4%), the radioactivity was 10-fold greater due to the higher specific activity of delta 9-(16 alpha-125I)INT and the lack of sample quench. The use of delta 9-(16 alpha-125I)INT greatly increases the sensitivity and efficiency of the photoaffinity labeling technique; it will provide a valuable tool for further studies of the progesterone receptor, allowing the detection of receptor in dilute cytosol after gel electrophoresis under denaturing conditions.

Lamb, D.J.; Bullock, D.W.; Hoyte, R.M.; Hochberg, R.B.

1988-05-01

281

Theory of energetic/alpha particle effects on magnetohydrodynamic modes in tokamaks  

SciTech Connect

The presence of energetic particles is shown to qualitatively modify the stability properties of ideal as well as resistive magnetohydrodynamic (MHD) modes in tokamaks. Specifically, we demonstrate that, consistent with highpower ICRF heating experiments in JET, high energy trapped particles can effectively stabilize the sawtooth mode, providing a possible route to stable high current tokamak operation. An alternative stabilization scheme employing barely circulating energetic particles is also proposed. Finally, we present analytical and numerical studies on the excitations of high-n MHD modes via transit resonances with circulating alpha particles. 14 refs., 3 figs.

Chen, L.; White, R.B.; Rewoldt, G.; Colestock, P.; Rutherford, P.H.; Chen, Y.P.; Ke, F.J.; Tsai, S.T.; Bussac, M.N.

1989-01-01

282

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

NASA Astrophysics Data System (ADS)

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

Kabadayi, Oe.

2006-06-01

283

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

SciTech Connect

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

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

1999-09-01

284

Excited analog state of 12?C and the alpha-particle model  

NASA Astrophysics Data System (ADS)

The idea that 12?C* is a strangeness analog state is examined using the alpha particle model. Volkov, Gillet, and Brink-Boeker potentials are used for the nucleon-nucleon and lambda-nucleon interactions, to calculate the binding energies of 12C and 12?C*. 12C is described by an equilateral triangle. When an allowance is made for the exchange character of the potentials used, the required potential strengths seem to be consistent with those obtained from low energy and light hypernuclear data, thus supporting the idea of a strangeness analog state. NUCLEAR STRUCTURE 12?C*, binding energy calculated assuming strangeness analog state in alpha particle model.

Mukherjee, Swapna; Panchapakesan, N.

1982-10-01

285

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

SciTech Connect

In this paper a simple fusion experiment for the production and control do deuterium-tritium-ignited plasmas for scientific study is considered. The basic elements of fusion product alpha-particle containment is rather high even with the assumption of significant levels of toroidal asymmetries. Production of thermally stable plasmas is possible because of the low-beta thermal damping provided by electron cyclotron emission. The stability of internal kink modes, high-number ballooning modes, and toroidicity-induced shear Alfven eigen-modes is investigated in the presence of fusion alpha particles. These modes can be either stable or unstable depending on the selected operational regime at ignition.

Carrera, R.; Montalvo, E. (Texas Univ., Austin, TX (United States)); Fu, G.Y. (CRPP, Lausanne (CH)); Miley, G.H. (Illinois Univ., Urbana, IL (United States)); Hively, L.M. (Oak Ridge National Lab., TN (United States)); Rosenbluth, M.N. (California Univ., San Diego, CA (United States)); Tamor, S. (La Jolla Inst., Arlington, VA (United States))

1990-12-01

286

Constraints from Instabilities on Alpha-Particle Temperature Anisotropy in the Solar Wind  

NASA Astrophysics Data System (ADS)

Various dynamic processes in the expanding solar wind produce a range of non-thermal ion and electron properties, which include different velocities, different temperatures, and non-unity temperature anisotropies for each particle species. If these deviations become too severe, a kinetic microinstability can arise, in which exponentially-growing wave modes scatter the particles. In this way, instabilities help to limit the departures of plasma from thermal equilibrium. The work presented here specifically relates to instabilities driven by ion temperature anisotropy: the cyclotron, mirror, and parallel and oblique firehose instabilities. Previous studies have provided strong evidence that instabilities limit proton temperature anisotropy and that the two-dimensional (i.e., mirror and oblique firehose) instabilities are significantly more active in this regard than the one-dimensional (i.e., cyclotron and parallel firehose) instabilities. However, this work considers instabilities driven by alpha-particle temperature anisotropy, which have received far less attention in the literature. Linear Vlasov analysis was used to derive the expected threshold conditions for these alpha-particle instabilities. When data from the Wind spacecraft's Faraday cups was compared to these threshold conditions, it was found to be consistent with instabilities (particularly the mirror and oblique firehose) constraining alpha-particle temperature anisotropy in the solar wind. While this result may seem counterintuitive because of the low alpha-particle relative abundance, the theoretical analysis indicates that the low collision rates in the solar wind often allow protons and alpha-particles to resonate separately and with different wave modes. These results provide new insight into how instabilities redistribute energy in the plasma and have important implication for the interpretation of the observations of minor-ions in the solar wind and corona.

Maruca, B. A.; Kasper, J. C.; Gary, S. P.

2011-12-01

287

Optical properties of green-blue-emitting Ca-{alpha}-Sialon:Ce{sup 3+},Li{sup +} phosphors for white light-emitting diodes (LEDs)  

SciTech Connect

Ce{sup 3+},Li{sup +}-codoped Ca-{alpha}-Sialon phosphors with the formula [Ca{sub (1-2x)}Ce{sub x}Li{sub x}]{sub m/2}Si{sub 12-(m+n)}Al{sub m+n}O{sub n}N{sub 16-n} (0{<=}x{<=}0.25, 0.5{<=}m{<=}3.5, and 0.16{<=}n{<=}2.0) have been synthesized by gas pressure sintering (GPS). The effects of the activator concentration and the overall composition of host lattice on the phase evolution, morphology, and optical properties were investigated. The single-phase Ca-{alpha}-Sialon:Ce{sup 3+},Li{sup +} can be synthesized at x<0.1, 1.0{<=}m{<=}2.5, and n{<=}1.2. The synthesized powders exhibit a relatively dispersive and uniform morphology. Under the near UV excitation, the bright green-blue emission centered at 500-518 nm is observed. The photoluminescence can be tailored by controlling Ce{sup 3+} concentration and the overall composition of the {alpha}-Sialon host lattice. With increasing the Ce concentration and m value both excitation and emission bands show a red shift, which perfectly matches with the near-UV LEDs in the range of 360-410 nm. The strongest luminescence is achieved at x=0.08-0.1, m=2.0-2.5, and n=1.0. Simultaneously, the highest quantum efficiency and better thermal stability are also present. -- Graphical abstract: Dependence of photoluminescence intensity and normalized photoluminescence spectra (the inset) of Ca-{alpha}-Sialon:Ce{sup 3+},Li{sup +} on the host lattice composition: (a) m value and (b) n value Display Omitted Highlights: {yields} The optical properties of [Ca{sub (1-2x)}Ce{sub x}Li{sub x}]{sub m/2}Si{sub 12-(m+n)}Al{sub m+n}O{sub n}N{sub 16-n} (0{<=}x{<=}0.25, 0.5{<=}m{<=}3.5, 0.16{<=}n{<=}2.0) have been investigated. {yields} Excited by near UV, the bright green emission centered at 500-518 nm is observed. {yields} The photoluminescence can be tailored by controlling Ce{sup 3+} content and host lattice composition. {yields} The strongest luminescence is achieved at x=0.08-0.1, m=2.0-2.5, and n=1.0. {yields} The highest quantum efficiency and better thermal stability are also present.

Li, Hui-Li, E-mail: hlli@phy.ecnu.edu.c [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Zhou, Guo-Hong [Structural Ceramics Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Xie, Rong-Jun; Hirosaki, Naoto [Nano Ceramics Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan); Wang, Xiao-Jun; Sun, Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China)

2011-05-15

288

Morphology and mixing state of individual freshly emitted wildfire carbonaceous particles.  

PubMed

Biomass burning is one of the largest sources of carbonaceous aerosols in the atmosphere, significantly affecting earth's radiation budget and climate. Tar balls, abundant in biomass burning smoke, absorb sunlight and have highly variable optical properties, typically not accounted for in climate models. Here we analyse single biomass burning particles from the Las Conchas fire (New Mexico, 2011) using electron microscopy. We show that the relative abundance of tar balls (80%) is 10 times greater than soot particles (8%). We also report two distinct types of tar balls; one less oxidized than the other. Furthermore, the mixing of soot particles with other material affects their optical, chemical and physical properties. We quantify the morphology of soot particles and classify them into four categories: ~50% are embedded (heavily coated), ~34% are partly coated, ~12% have inclusions and~4% are bare. Inclusion of these observations should improve climate model performances. PMID:23824042

China, Swarup; Mazzoleni, Claudio; Gorkowski, Kyle; Aiken, Allison C; Dubey, Manvendra K

2013-01-01

289

Characterization and control of airborne particles emitted during production of epoxy/carbon nanotube nanocomposites.  

PubMed

This work characterized airborne particles generated from the weighing of bulk, multiwall carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. It also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood, and biosafety cabinet) for control of particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured using an optical particle counter (OPC) and a condensation particle counter (CPC), and particle morphology was assessed by transmission electron microscopy. The ratios of the geometric mean (GM) concentrations measured during the process to that measured in the background (P/B ratios) were used as indices of the impact of the process and the LEVs on observed concentrations. Processing CNT-epoxy nanocomposites materials released respirable size airborne particles (P/B ratio: weighing = 1.79; sanding = 5.90) but generally no nanoparticles (P/B ratio ?1). The particles generated during sanding were predominantly micron sized with protruding CNTs and very different from bulk CNTs that tended to remain in large (>1 ?m) tangled clusters. Respirable mass concentrations in the operator's breathing zone were lower when sanding was performed in the biological safety cabinet (GM = 0.20 ?g/m(3) compared with those with no LEV (GM = 2.68 ?g/m(3) or those when sanding was performed inside the fume hood (GM = 21.4 ?g/m(3); p-value < 0.0001). The poor performance of the custom fume hood used in this study may have been exacerbated by its lack of a front sash and rear baffles and its low face velocity (0.39 m/sec). PMID:21253981

Cena, Lorenzo G; Peters, Thomas M

2011-02-01

290

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

PubMed

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

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

2010-08-01

291

[Preparation of alpha-Gd2 (MoO4)3 red emitting phosphor for white light emitting diodes and its luminescence study].  

PubMed

A novel red phosphor alpha-Gd2 (MoO4)3: Eu was synthesized by conventional solid state reaction method with the starting materials: Gd2O3, MoO3 and Eu2O3. The effects of flux and Eu concentration on the crystal structure, morphology and luminescent properties of the phosphors were investigated. The results showed that non-agglomeration phosphors with regular morphology and fine size were produced after the mixture being calcined at 800 degrees C for 4h with 3% NH4F as flux. The main emission peak of the samples is at 613 nm. The excitation spectrum showed that this phosphor can be effectively excited by ultraviolet (UV) (395 nm) and blue (465 nm) light, nicely fitting in with the widely applied output wavelengths of ultraviolet or blue LED chips. The alpha-Gd2 (MoO4)3 phosphor may be a good candidate phosphor for solid state lighting application. PMID:17608161

Zhao, Xiao-Xia; Wang, Xiao-Jun; Chen, Bao-Jiu; Meng, Qing-Yu; Yan, Bin; Di, Wei-Hua

2007-04-01

292

Cross section balance in the 14N + 159Tb reaction and the origin of fast alpha particles  

Microsoft Academic Search

Exclusive cross sections have been obtained from particle-K X-ray coincidence data measured at 236 MeV for ejectiles ranging from 4He to 15N. Production cross sections for primary fragments and alpha particle multiplicities associated with different channels have been deduced. The major fraction of the alpha particles appears to originate from inelastic (damped) processes in which only light particles with Z

R. H. Siemssen; G. J. Balster; H. W. Wilschut; P. D. Bond; P. C. N. Crouzen; P. B. Goldhoorn; Han Shukui; Z. Sujkowski

1985-01-01

293

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

SciTech Connect

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

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

1998-11-01

294

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

SciTech Connect

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

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

2005-05-24

295

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

296

Analysis of Collective Thomson Scattering for alpha Particles Diagnostics on Tokamaks.  

National Technical Information Service (NTIS)

An analysis is carried out of the alpha particles feature of the scattering dynamic form factor in a tokamak configuration. It is shown that the magnetic field in general causes two main effects: (1) a frequency roll-off affects the form factor for small ...

F. P. Orsitto P. Buratti

1989-01-01

297

Diffusive Model for alpha -Particle Energy Transport in a Laser Plasma.  

National Technical Information Service (NTIS)

The ignition of a laser-fusion pellet is essential due to the energy that the alpha -particles yielded by the D-T reactions in a small inner hot spot transfer to the outer cold and dense plasma. It is shown that if the plasma temperature is less than or e...

S. Atzeni A. Caruso

1980-01-01

298

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

NASA Astrophysics Data System (ADS)

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.

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

2002-03-01

299

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

Microsoft Academic Search

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

Robert Baumann; Tim Hossain; Shinya Murata; Hideki Kitagawa

1995-01-01

300

Alpha-particle induced charge transfer between closely spaced trench capacitor memory cells  

Microsoft Academic Search

A detailed analysis of various mechanisms involved in alpha-particle induced charge transfer between two trench type dRAM cells is reported and an analytical model has been developed to represent the transfered charge. The results compare very favorably with detailed simulation results.

J. H. Chern; P. Yang; P. Pattnaik; J. A. Seitchik; K. C.-K. Weng

1985-01-01

301

Quasi-linear absorption of LH waves by fusion generated alpha particles.  

National Technical Information Service (NTIS)

Lower hybrid waves are foreseen to be used in a steady state reactor to produce current and control the current profile and the stability of internal modes. In the ignited phase, however, the presence of energetic alpha-particles may prevent wave-electron...

E. Barbato F. Santini

1989-01-01

302

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

National Technical Information Service (NTIS)

Control of the radial alpha particle transport by using Ion Cyclotron Range of Frequency waves is investigated in a large-aspect-ratio tokamak geometry. It is shown that spatially inhomogeneous ICRF-wave energy with properly selected frequencies and wave ...

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

1990-01-01

303

Synthetic doublets from 234U alpha-particle spectra for assessing accuracy in peak fitting  

NASA Astrophysics Data System (ADS)

A series of well-characterized doublets has been constructed from 234U alpha-particle spectra to compare fitted peak-area ratios and positions with the known values. Results obtained using fitting models at CBNM and CIEMAT are discussed.

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

1990-01-01

304

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

SciTech Connect

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

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

2008-01-01

305

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

Microsoft Academic Search

Past studies of the properties of Alfv6n waves in the solar wind have indicated that: the amplitude of the velocity fluctuations is almost always smaller than expected on the basis of the amplitude of the field fluctuations, even when the anisotropy of the plasma is taken into account, and the alpha particle transverse velocities are less (often close to zero)

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

1996-01-01

306

Binding Energies of the Alpha Particle and the A=3 Isobars from a Theoretical Geometric Model  

Microsoft Academic Search

We assume a triple geometric structure for the electromagnetic nuclear interaction. This nuclear electromagnetism is used to calculate the binding energies of the alpha particle and the A=3 isobar nuclides. The approximation for the resultant wave equation which lead to the deuteron binding energy from the modified Mathieu equation for the radial eigenvalue equation also establishes proton-electron-proton magnetic bonds in

Gustavo R. Gonzalez-Martin

2008-01-01

307

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

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

308

Prediction of lung cancer risk for radon exposures based on cellular alpha particle hits.  

PubMed

To explore the role of the multiplicity of cellular hits by radon progeny alpha particles for lung cancer incidence, the number of single and multiple alpha particle hits were computed for basal and secretory cells in the bronchial epithelium of human airway bifurcations. Hot spots of alpha particle hits were observed at the branching points of bronchial airway bifurcations. The effect of single and multiple alpha particle intersections of bronchial cells during a given exposure period, selected from a Poisson distribution, on lung cancer risk were simulated by a transformation frequency--tissue response model, based on experimentally observed cellular transformation and survival functions. Calculations of lung cancer risk at low radon exposure levels suggest that single hits produce a linear-dose response relationship, while the superposition of single and increasing multiple hits at higher exposure levels may also be approximated by a quasi-linear dose-effect curve. The simulations predict a carcinogenic enhancement effect for radon progeny accumulations at bifurcation branching sites, which may increase current risk estimates. PMID:21471125

Truta-Popa, L-A; Hofmann, W; Cosma, C

2011-04-06

309

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

310

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

311

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

Microsoft Academic Search

The chemical composition of rocks and soils on Mars analyzed during the Mars Exploration Rover Spirit Mission was determined by X-ray analyses with the Alpha Particle X-Ray Spectrometer (APXS). Details of the data analysis method and the instrument calibration are presented. Measurements performed on Mars to address geometry effects and background contributions are shown. Cross calibration measurements among several instrument

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

2006-01-01

312

Variational calculations with correlated basis functions: Three-nucleon and three-alpha-particle systems  

NASA Astrophysics Data System (ADS)

A new variational method is applied to the solution of the Schroedinger equation for interacting few-body systems. The results for three nucleons interacting via the spin-dependent Malfliet-Tjon potential and three alpha particles interacting via the Ali-Bodmer potential are presented and compared with Faddeev and ATMS results, respectively.

Atti, C. Ciofi; Simula, S.

1985-09-01

313

Cancer incidence and lifespan vs. alpha-particle dose in beagles  

SciTech Connect

Young adult beagles were injected with graded activities of /sup 239/Pu, /sup 241/Am, /sup 228/Th, /sup 228/Ra or /sup 226/Ra and observed throughout their lifespans. The vast majority of the dose was from alpha particles. The lifetime incidence of bone sarcoma increased with average skeletal dose, more or less linearly up to high incidence for /sup 239/Pu, /sup 241/Am, /sup 228/Th and /sup 226/Ra, but sigmoid fashion for /sup 228/Ra. Based on average skeletal dose, the toxicity of the emitters relative to /sup 226/Ra = 1.0 was /sup 239/Pu = 16.6 +/- 4.5, /sup 241/Am = 5.4 +/- 1.6, /sup 228/Th = 8.5 +/- 2.3 and /sup 228/Ra = 2.0 +/- 0.5. At the lowest doses, the average lifespans were 97% +/- 3% of that in the controls. If beneficial effects occurred, they may have been overwhelmed by the destructiveness of the densely ionizing alpha particles. A cell nucleus 5 micron in diameter receives a mean dose of about 1 Gy (100 rad) when traversed by a single alpha particle. We found no evidence that alpha-particle doses suppressed cancer or lengthened lifespan in beagles.

Mays, C.W.; Lloyd, R.D.; Taylor, G.N.; Wrenn, M.E.

1987-05-01

314

Electron transport uniformity characterization of CdZnTe using alpha particles  

SciTech Connect

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

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

1998-04-01

315

Simulations of alpha particle ripple loss from the International Thermonuclear Experimental Reactor  

SciTech Connect

Calculations of collisional stochastic ripple loss of alpha particles from the new 20 toroidal field (TF) coil International Thermonuclear Experimental Reactor (ITER) predict small alpha ripple losses, less than 0.4%, close to the loss calculated for the full current operation of the earlier 24 TF coil design. An analytic fit is obtained to the ITER ripple data field demonstrating the nonlinear height dependence of the ripple minimum for D shaped ripple contours. In contrast to alpha loss simulations for the Tokamak Fusion Test Reactor (TFTR), a simple Goldston, White, Boozer stochastic loss criterion ripple loss model is found to require an increased renormalization of the stochastic threshold {delta}{sub s}/{delta}{sub GWB} {ge} 1. Effects of collisions, sawtooth broadening and reversal of the grad B drift direction are included in the particle following simulations.

Redi, M.H.; Budny, R.V.; McCune, D.C.; Miller, C.O.; White, R.B.

1996-05-01

316

Candidate reactions for mercury detection induced by neutron and alpha particles  

NASA Astrophysics Data System (ADS)

This paper summarizes modeling of mercury to activated states with alpha particles, neutrons, or deuterons, and the spectral emission from the activated products. Activation can occur with a neutron source such as 242Cf, 241Am-Be, a neutron generator, or a particle accelerator, and the activation products are measured if sufficient signal is provided. Identification and measurement of mercury by prompt gamma emission, generated by bombardment with neutrons are reported. Activation product reactions of (?, xn) (d, xn) (n, ?) and (n, p) are screened as candidate reactions. In addition to prompt gamma emission, products and cross-sections of delayed activation involving alphas, deuterons and neutrons are also reported. Initial calculations indicate the potential use of either alpha, or 14 MeV neutron activation to assess part per billion concentrations of mercury in the gaseous phase. Ultimately, data from sample analysis of ambient-condition flue gas will be used to assess mercury detection sensitivity and specificity under typical operating conditions.

Toth, James J.; Wittman, Richard; Schenter, Robert E.; Cooper, John A.

2007-03-01

317

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

318

Ionization of the Atmosphere Due to Beta Particles Emitted by Fission Products  

Microsoft Academic Search

Persistent ionization of air at moderate heights, just below the E ; layer, after high-altitude nuclear detonations is predominantly due to radiations ; accompanying radioactive decay of fission products. The most important are BETA ; particles, which are restricted in their movements by the earth's magnetic field ; and thus create ionized clouds of high density in localized regions. A

S. Kownacki

1963-01-01

319

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

320

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

SciTech Connect

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

Wuosmaa, A.H.

1993-12-31

321

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

SciTech Connect

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

Burns, F.J.

1990-01-01

322

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

2005-01-28

323

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

SciTech Connect

Neoclassical simulations of alpha particle density profiles in high fusion power plasmas on the Tokamak Fusion Test Reactor [Phys. Plasmas {bold 5}, 1577 (1998)] are found to be in good agreement with measurements of the alpha distribution function made with a sensitive active neutral particle diagnostic. The calculations are carried out in Hamiltonian magnetic coordinates with a fast, particle-following Monte Carlo code which includes the neoclassical transport processes, a recent first-principles model for stochastic ripple loss and collisional effects. New calculations show that monotonic shear alpha particles are virtually unaffected by toroidal field ripple. The calculations show that in reversed shear the confinement domain is not empty for trapped alphas at birth and allow an estimate of the actual alpha particle densities measured with the pellet charge exchange diagnostic. {copyright} {ital 1999 American Institute of Physics.}

Redi, M.H.; Batha, S.H.; Budny, R.V.; Darrow, D.S.; Levinton, F.M.; McCune, D.C.; Medley, S.S.; Petrov, M.P.; von Goeler, S.; White, R.B.; Zarnstorff, M.C.; Zweben, S.J. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); TFTR Team

1999-07-01

324

Confined alpha particle diagnostic system using an energetic He{sup 0} beam for ITER  

SciTech Connect

The beam neutralization system for measurement of the spatial and velocity distributions of alpha particles of ITER plasmas was studied. As forward angle detection against the beam injection direction is required for effective neutralization, arrangement of the measurement system using possible ports in ITER configuration is proposed. The count rate of neutralized alpha particles produced by the double charge exchange interaction with energetic He{sup 0} beam particles injected is estimated. The ratios of signal to neutron-induced noise are evaluated. When a He{sup 0} beam produced by autodetachment from a 1-1.5 MeV He{sup -} beam of 10 mA is injected, the signal to noise ratio becomes greater than 1 at {rho}<0.4, even without beam modulation. Usage of a lock-in technique at the frequency of radio-frequency quadrapole accelerator will make measurement at the outer region possible.

Sasao, M.; Shinto, K.; Isobe, M.; Nishiura, M.; Kaneko, O.; Wada, M.; Walker, C. I.; Kitajima, S.; Okamoto, A.; Sugawara, H.; Takeuchi, S.; Tanaka, N.; Aoyama, H.; Kisaki, M. [Tohoku University, Aoba, Sendai 980-8579 (Japan); National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan); ITER Joint Work Site, Cadarache, 13108 Saint-Paul-lez-Durance cedex (France); Tohoku University, Aoba, Sendai 980-8579 (Japan)

2006-10-15

325

Dynamic radioactive particle source  

SciTech Connect

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

326

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

SciTech Connect

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

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

2007-06-15

327

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

SciTech Connect

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

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

1999-02-01

328

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

NASA Astrophysics Data System (ADS)

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

Heeter, Robert Franklin

1999-12-01

329

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

SciTech Connect

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

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

1992-09-01

330

Evidence for alpha-particle chain configurations in sup 24 Mg  

SciTech Connect

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

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

1992-01-01

331

Search for Evidence of Alpha-Particle Beams during a Solar Flare Observed by the Coronal Diagnostic Spectrometer aboard the Solar and Heliospheric Observatory  

NASA Astrophysics Data System (ADS)

We observed NOAA Active Region 9090 (N13, W39) with the Coronal Diagnostic Spectrometer (CDS) and the Extreme-Ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory spacecraft between 18:17 and 21:09 UT on 2000 July 24 to search for evidence of alpha-particle beams during solar flares. Theoretically, an alpha-particle beam will manifest itself during the impulsive phase of a flare through an enhancement in the red wing of the He II Ly? (?303.782) emission line without a corresponding blue wing enhancement. This enhancement is due to downstreaming nonthermal alpha particles undergoing charge-exchange with chromospheric neutral hydrogen atoms to form downstreaming nonthermal He II ions. Ly? radiation emitted from these downstreaming ions is Doppler-shifted into the red wing of the Ly? line. Our CDS observing program acquired high time resolution (9.7 s) 4''4' slit spectra between 590 and 630 , where we observed He II Ly? in second order (?607.564). The CDS and EIT observations reveal that AR 9090 underwent significant intensity fluctuations prior to a sudden drastic increase (impulsive phase) around 20:00 UT. The GOES satellite reports a C3.8 event in this region from 19:57 to 20:05 UT. We fitted the spectral background and emission-line profiles for each CDS spectrum in our observed sequence. Density- and temperature-insensitive intensity ratios of O IV and Mg X lines generally agree with their theoretical values before and after the sudden intensity increase, which supports a reliable relative radiometric calibration for CDS, but differ significantly from their theoretical values during the flare impulsive phase. This may indicate line blending with unknown components, line blending with second-order C IV and Fe XV lines, or loss of ionization equilibrium. Most important, however, we find that although the red and blue wing backgrounds for He II Ly? remain relatively constant during most of our observation, the blue wing undergoes a more significant enhancement during the impulsive phase than does the red wing. This effect is opposite to that expected in the presence of an alpha-particle beam. Furthermore, blended spectral line features that mimic the expected nonthermal redshifted He II Ly? beam signal are understood in terms of well-known emission-line components. Thus, we find no evidence for the presence of alpha-particle beams in our observations. We estimate an upper limit of ~250 ergs cm-2 s-1 sr-1 -1 for the nonthermal redshifted peak spectral intensity due to an alpha-particle beam prior to the impulsive phase.

Brosius, Jeffrey W.

2001-07-01

332

Investigation of the airborne submicrometer particles emitted by dredging vessels using a plume capture method  

NASA Astrophysics Data System (ADS)

A method for investigating ship emissions, known as the plume capture and analysis system (PCAS) is described. The PCAS is applied to the task of measuring airborne pollutant emission factors (EFs) and particle size distributions aboard two dredgers, although the technique is also suitable for remote measurements. EFs were measured relative to the fuel consumption using the fuel combustion derived plume CO2. Each measurement typically took 6min to complete and during one day, 4050 measurements were possible. EFs for particle number (PN), NOx, SO2, and PM2.5 were independent within a targeted dilution factor range of 501000 suitable for onboard and remote sampling.For the Amity, the EF ranges were PN: 2.29.6נ1015(kg-fuel)?1; NOx: 3572g(NO2)(kg-fuel)?1, SO2 0.61.1g(SO2)(kg-fuel)?1and PM2.5: 0.76.1g(PM2.5)(kg-fuel)?1. For the Brisbane they were PN: 1.01.5נ1016(kg-fuel)?1, NOx: 3.48.0g(NO2)(kg-fuel)?1, SO2: 1.31.7g(SO2)(kg-fuel)?1 and PM2.5: 1.25.6g(PM2.5)(kg-fuel)?1.Particle number emission factors as a function of size as well as the count median diameter (CMD), and geometric standard deviation of the size distributions are provided. This size distributions were consistently uni-modal in the range below 500nm for both vessels, and this CMD always lay within the accumulation mode range.

Juwono, Alamsyah M.; Johnson, G. R.; Mazaheri, M.; Morawska, L.; Roux, F.; Kitchen, B.

2013-07-01

333

Particles emitted from indoor combustion sources: size distribution measurement and chemical analysis.  

PubMed

This study is primarily focused toward measuring the particle size distribution and chemical analysis of particulate matter that originates from combustion sources typically found in Indian urban homes. Four such sources were selected: cigarette, incense stick, mosquito coil, and dhoop, the latter being actually a thick form of incense stick. Altogether, seven of the most popular brands available in the Indian market were tested. Particle size distribution in the smoke was measured using a scanning mobility particle sizer, using both long and nano forms of differential mobility analyzer (DMA), with readings averaged from four to six runs. The measurable particle size range of the nano DMA was 4.6 nm to 157.8 nm, whereas that of the long DMA was 15.7 nm to 637.8 nm. Therefore, readings obtained from the long and the nano DMA were compared for different brands as well as for different sources. An overlap was seen in the readings in the common range of measurement. The lowest value of peak concentration was seen for one brand of incense stick (0.9 x 10(6) cm(-3)), whereas the highest (7.1 x 10(6) cm(-3)) was seen for the dhoop. Generally, these sources showed a peak between 140 and 170 nm; however, 2 incense stick brands showed peaks at 79 nm and 89 nm. The dhoop showed results much different from the rest of the sources, with a mode at around 240 nm. Chemical analysis in terms of three heavy metals (cadmium, zinc, and lead) was performed using graphite tube atomizer and flame-atomic absorption spectrophotometer. Calculations were made to assess the expected cancer and noncancer risks, using published toxicity potentials for these three heavy metals. Our calculations revealed that all the sources showed lead concentrations much below the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) level. One of the two mosquito coil brands (M(2)) showed cadmium concentrations two times higher than the California Environmental Protection Agency (Cal EPA) reference exposure level (REL). The latter also showed the highest carcinogenic risks of 350 people per million population. The amount of zinc obtained from the sources, however, was found to be quite below the standard limits, implying no risk in terms of zinc. PMID:19591538

Roy, A A; Baxla, S P; Gupta, Tarun; Bandyopadhyaya, R; Tripathi, S N

2009-08-01

334

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

Microsoft Academic Search

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

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

2011-01-01

335

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

336

Alpha migration through air filters: A numerical simulation  

NASA Astrophysics Data System (ADS)

This theoretical study investigates the migration of alpha-emitting particles through high-efficiency particulate air (HEPA) filters. As part of the study, a review of previous research relating to the alpha-migration phenomena was conducted. As a result of the literature review, a numerical model was developed to simulate the migration of alpha-emitting radionuclide aerosols through HEPA filters. This model predicts the filter performance with regard to particle penetration. It can be used to better estimate the penetration of alpha radioactive species through filter systems for environmental concerns, to aid in the use of current filter systems, and to design new filter systems.

Biermann, Arthur H.; Daroza, Robert A.; Chang, Yun

1991-12-01

337

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

SciTech Connect

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

Funaki, Y. [Nishina Center for Accelerator-Based Science, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198 (Japan); Horiuchi, H. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 567-0047 (Japan); International Institute for Advanced Studies, Kizugawa 619-0225 (Japan); Roepke, G. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Schuck, P. [Institut de Physique Nucleaire, F-91406 Orsay Cedex (France); Universite Paris-Sud, F-91406 Orsay-Cedex (France); Tohsaki, A. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 567-0047 (Japan); Yamada, T. [Laboratory of Physics, Kanto Gakuin University, Yokohama 236-8501 (Japan)

2008-06-15

338

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

SciTech Connect

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

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

2010-11-15

339

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

SciTech Connect

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

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

2009-06-03

340

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

SciTech Connect

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

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

2009-01-01

341

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

SciTech Connect

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

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

1989-01-01

342

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

PubMed

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

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

2009-04-27

343

Sequential determination of 210Po and uranium radioisotopes in drinking water by alpha-particle spectrometry.  

PubMed

Procedures for the sequential determination of low level (210)Po and uranium radioisotopes in drinking water by alpha-particle spectrometry are presented. After addition of (208)Po and (232)U tracers, the radionuclides were preconcentrated from water samples by co-precipitation on Fe(OH)(3) or MnO(2) at pH 9 using ammonia solution. The (210)Po source was prepared by spontaneous deposition onto a copper disc either before or after uranium separation. The uranium source for alpha-particle counting was prepared by micro co-precipitation with CeF(3). The procedures were tested on mineral water and the results obtained are compared. PMID:19231220

Benedik, L; Vasile, M; Spasova, Y; Wtjen, U

2009-01-24

344

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

2013-01-05

345

Results from the Lunar Prospector Alpha Particle Spectrometer: Detection of Radon-222 Over Craters Aristarchus and Kepler  

NASA Astrophysics Data System (ADS)

The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-218 (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. Radon reaches the lunar surface either at areas of high soil porosity or where fissures release the trapped gases in which radon is entrained. We have examined APS data within +/- 45 degrees of the equator acquired during periods of low interplanetary alpha particle flux. The spectra were summed over all LP mapping cycles when the instrument was turned on (approximately 229 days over 16 months). To yield lunar alpha particle maps, we summed over a 0.2 MeV energy range centered on each of the three alpha particle energies noted above. The LP APS found only a faint indication of alpha particles resulting from the decay of polonium-218 and only a marginal detection of alpha particles from polonium-210. However, our radon-222 alpha particle map indicates that radon gas is presently emanating from the vicinity of craters Aristarchus and Kepler. The LP gamma-ray spectrometer, which effectively has significantly higher spatial resolution than the APS, identified thorium enrichments at these two craters. Thorium and uranium are both incompatible elements whose lunar surface abundances are highly correlated; thus, it is likely that the radon-222 alpha particles measured using the LP APS originate from Kepler and Aristarchus. Our detection of radon over Aristarchus is consistent with the results of the Apollo 15 APS.

Lawson, S. L.; Feldman, W. C.; Lawrence, D. J.; Moore, K. R.; Belian, R. D.; Maurice, S.; Binder, A. B.

2001-11-01

346

LETTER: Ripple induced stochastic loss of alpha particles in a tokamak  

NASA Astrophysics Data System (ADS)

The Fokker-Planck equation is solved for alpha particles in a tokamak, including both pitch angle scattering and slowing down. Losses of the toroidally trapped particles due to stochastic diffusion related to magnetic ripple are accounted for by assuming that all the stochastic orbits leave the device immediately. This assumption permits the problem to be solved by the introduction of a loss cone corresponding to the stochastic region of the velocity space. The eigenvalue problem is solved numerically, to show that the additional stochastic loss of energy due to scattering into the loss cone substitutes about 30% of the birth energy for typical fusion parameters

Yanashima, K.; Yamasaki, D.; Watabe, S.; Hara, K.; Yoshino, J.; Kukimoto, H.

347

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

PubMed

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

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

2012-05-02

348

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

PubMed

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

Osano, E; Kishi, J; Takahashi, Y

2003-02-01

349

Effects of [alpha]-particle radiation on rat tracheal epithelial cells  

SciTech Connect

By a combination of methods, which included flow cytometry and magnetic cell sorting, the author has demonstrated that the cells of the rat tracheal epithelium which have the greatest proliferative capacity in culture and in vivo are the basal cells. Because of these findings it seems reasonable to suppose that the basal cells are the most likely target for the action of [alpha]-particle radiation in pseudostratified respiratory epithelium. This hypothesis is further supported by the finding that the basal cells are the cells which appear to respond to the tumor promoter 12-O-tetra-decanoylphorbol-13-acetate. The effects of [sup 210]Po [alpha]-particles on the survival and oncogenic transformation of rat tracheal epithelial cells in suspension were investigated. Since these effects were assayed in culture, the results pertain to the reaction of only the basal cells to irradiation. The results indicate that [alpha]-particles are extremely cytotoxic in that a track segment of 4 [mu]m, on average, is sufficient to cause the reproductive death of basal cells. This finding is supported by similar results obtained with two cell lines, Mv1Lu and CHO-K1 BH[sub 4]. Production of proliferating epithelial foci by [alpha]-particles was not distinguishable from control and sham treatments. These results are in direct conflict with many of the results that have been obtained with C3H 10T1/2 cells in similar transformation assays. Some possible reasons for these disparities are discussed and supporting evidence is provided.

Ford, J.R. Jr.

1992-01-01

350

Effects of {alpha}-particle radiation on rat tracheal epithelial cells  

SciTech Connect

By a combination of methods, which included flow cytometry and magnetic cell sorting, we have demonstrated that the cells of the rat tracheal epithelium which have the greatest proliferative capacity in culture and in vivo are the basal cells. Because of these findings it seems reasonable to suppose that the basal cells are the most likely target for the action of {alpha}-particle radiation in pseudostratified respiratory epithelium. This hypothesis is further supported by the finding that the basal cells are the cells which appear to respond to the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. The effects of {sup 210}Po {alpha}-particles on the survival and oncogenic transformation of rat tracheal epithelial cells in suspension were investigated. Since these effects were assayed in culture, the results pertain to the reaction of only the basal cells to irradiation. The results indicate that {alpha}-particles are extremely cytotoxic in that a track segment of 4 {mu}m, on average, is sufficient to cause the reproductive death of basal cells. This finding is supported by similar results obtained with two cell lines, Mv1Lu and CHO-K1 BH{sub 4}. Production of proliferating epithelial foci by {alpha}-particles was not distinguishable from control and sham treatments. These results are in direct conflict with many of the results that have been obtained with C3H 1OT1/2 cells in similar transformation assays. Some possible reasons for these disparities are discussed and supporting evidence is provided.

Ford, J.R. Jr.

1992-08-01

351

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

SciTech Connect

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

Zaider, M.

1992-01-01

352

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

SciTech Connect

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

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

2010-09-15

353

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

Microsoft Academic Search

Neoclassical transport of minority suprathermal alpha particles is investigated. This paper departs from previous investigations in that (a) the banana-width ordering parameter ρ{sub θ}\\/L is not formally restricted to be a small parameter and (b) a linearized collision operator that retains the effects of pitch-angle scattering, electron and ion drag, and speed diffusion is used. A step model approximation for

G. T. Sager; G. H. Miley; K. H. Burrell

1990-01-01

354

Data needs for the track structure of alpha particles and electrons in water  

SciTech Connect

We have made calculations of the ionization spectra for alpha particle and electron tracks in water. We have also computed the number of ions created per micrometre of track length, the energy distribution of the secondaries, and the energy expended per ion pair created. Our aim is less toward theoretical derivations than to obtain a numerically accurate description of the track structure at all energies in a form suitable for biomedical applications. 13 references.

Pagnamenta, A.

1983-01-01

355

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

SciTech Connect

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

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

1994-07-01

356

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

Microsoft Academic Search

The time dependence and the intensity of the primary scintillation light in liquid xenon excited by 241Am alpha particles and 207Bi internal conversion electrons were measured at different electric field strengths. High-purity liquid xenon was used to fill a parallel-plate ionization chamber equipped with a CaF2 window coupled to a UV (ultraviolet) sensitive photomultiplier tube. The effect of the specific

Elena Aprile; Reshmi Mukherjee; Masayo Suzuki

1990-01-01

357

Low-Temperature Electron and Alpha-Particle Irradiation of Titanium  

Microsoft Academic Search

The recovery of point defects produced by 1.2-MeV electron and 40-MeV alpha-particle irradiation has been studied from 50 to 270K. The recovery spectrum qualitatively resembles that of copper, although shifted to higher temperature. The influence of varying irradiation dose, preirradiation at elevated temperatures, predeformation and dilute alloying were also studied. The recovery below 150K is dominated by the annihilation of

Walter Bauer; K. Herschbach; J. J. Jackson

1969-01-01

358

Binding Energies of the Alpha Particle and the A=3 Isobars from a Theoretical Geometric Model  

Microsoft Academic Search

We assume a triple geometric structure for the electromagnetic nuclear\\u000ainteraction. This nuclear electromagnetism is used to calculate the binding\\u000aenergies of the alpha particle and the A=3 isobar nuclides. The approximation\\u000afor the resultant wave equation which lead to the deuteron binding energy from\\u000athe modified Mathieu equation for the radial eigenvalue equation also\\u000aestablishes proton-electron-proton magnetic bonds in

Gustavo R. Gonzalez-Martin

2008-01-01

359

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

Microsoft Academic Search

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

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

1983-01-01

360

Development of ZnO:Ga as an Ultra-Fast Alpha Particle Detector  

Microsoft Academic Search

We report on ZnO:Ga to produce a high luminosity, ultra fast alpha detector as a system component that provides associated particle imaging (API) capability to neutron generators. ZnO:Ga has been shown to be well suited as the scintillator screen of the detector. Fast luminescence is observed but its intensity and decay time is strongly dependent on the method used for

E. D. Bourret-Courchesne; S. E. Derenzo; M. J. Weber

2006-01-01

361

Emission of Neutrons from Argon, Chlorine, Aluminum and Some Heavier Elements Under Alpha-Particle Bombardment  

Microsoft Academic Search

The emission of neutrons from chlorine, argon, scandium, titanium, manganese and iron under alpha-particle bombardment was established. The yield from argon is considerable and enabled a measurement of the energy of the neutrons to be made: the majority are associated with a group of energy change -5.6+\\/-1.0 Mev, but two groups must be present. The excitation curve for these neutrons

Ernest Pollard; Howard L. Schultz; Gordon Brubaker

1938-01-01

362

Accuracy testing using thick source alpha-particle spectroscopy for the U and Th series estimations.  

PubMed

The new technique for the calculation of U and Th based on the alpha particle spectrum taken from a thick sample by using a silicon detector (PIPS) is tested and some technical problems are encountered and also some notifications for better accuracy are addressed. This technique which is mainly developed to be used for dose rate determination in TL, OSL and ESR dating applications, gives also the possibility for detecting and estimating possible disequilibrium in U and Th series. PMID:19900816

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

2009-10-24

363

Fabrication of micropillar substrates using replicas of alpha-particle irradiated and chemically etched PADC films.  

PubMed

We proposed a simple method to fabricate micropillar substrates. Polyallyldiglycol carbonate (PADC) films were irradiated by alpha particles and then chemically etched to form a cast with micron-scale spherical pores. A polydimethylsiloxane (PDMS) replica of this PADC film gave a micropillar substrate with micron-scale spherical pillars. HeLa cells cultured on such a micropillar substrate had significantly larger percentage of cells entering S-phase, attached cell numbers and cell spreading areas. PMID:22130471

Ng, C K M; Chong, E Y W; Roy, V A L; Cheung, K M C; Yeung, K W K; Yu, K N

2011-11-18

364

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

365

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

SciTech Connect

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

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

2009-12-15

366

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

SciTech Connect

Nonlinear electrostatic instabilities have been shown to occur frequently and under very different conditions in plasma with two ion beams such as the fast solar wind. These instabilities can be triggered when the phase velocity of electrostatic ion-acoustic waves propagating forward and backward relative to the interplanetary magnetic field overlaps due to the presence of a finite amplitude of circularly polarized wave. The instabilities can be triggered by waves supported by the same ion component, or by waves supported by different ion components. By assuming a beam of alpha particles moving backward relative to the external magnetic field, as observed in some events in the fast solar wind, it is shown that a very small negative drift velocity of the alpha particle beam relative to the core plasma--a few percent of the local Alfven velocity--can trigger a very rich variety of nonlinear electrostatic acousticlike instabilities. Their growth rates can be rather large and they persist for larger negative alpha particles drift velocities and temperatures.

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

2010-06-15

367

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

NASA Astrophysics Data System (ADS)

The alpha-particle-induced collected charge in undoped LEC semi-insulating GaAs is measured in n+-i-n+ and n+-p-n+ isolation structures and is compared with the results of an analytical model based on a bipolar mechnism. In n+-i-n+ isolation structures, a collected-storage multiplication phenomenon induced by alpha-particle incidence is observed. The measured collected charge is about three times the alpha-particle-generated charge. This phenomenon can be attributed to charge transfer between two adjacent n+ regions. The dominant charge-collection process continues for 2.4 ns in n+-i-n+ isolation structures, but in n+-p-n+ isolation structures, it stops within 0.8 ns. The measured collected charge decreases as the isolation gap and background acceptor concentration increase. These experimental results can be explained semiquantitatively by the analytical model. This suggests that the primary mechanism of soft errors in GaAs ICs is a bipolar mechanism.

Umemoto, Yasunari; Matsunaga, Nobutoshi; Mitsusada, Kazumichi

1989-05-01

368

Ultra-high Resolution Alpha Particle Spectrometry with Transition-Edge Sensor Microcalorimeters  

NASA Astrophysics Data System (ADS)

Alpha particle spectrometry is a powerful analytical tool for nuclear forensics and environmental monitoring. Microcalorimeter detectors have been shown to yield nearly an order of magnitude better energy resolution (1.06 keV FWHM at 5.3 MeV) than current state-of-the-art silicon detectors (8-10 keV FWHM at 5.3 MeV). This superior resolution allows isotopic analysis with a single non-consumptive measurement of samples that contain multiple radioisotopes with overlapping alpha energies. Measurement of such a sample with a silicon detector would require expensive and time-consuming radiochemical separations. We are developing two alpha spectrometer systems with superconducting transition-edge sensor microcalorimeters. The first system has eight independent detector channels that measure eight different alpha sources, and is optimized for detector development experiments. The second system incorporates a prototype cryogenic load lock that allows for rapid exchange of alpha samples. This paper will present results from these two systems.

Croce, M.; Bacrania, M.; Bond, E.; Dry, D.; Moody, W. A.; Rabin, M.; Bennett, D.; Hilton, G.; Horansky, R.; Kotsubo, V.; Schmidt, D.; Ullom, J.; Vale, L.; Cantor, R.

2012-06-01

369

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

370

Alpha-recoil track dating of Quaternary volcanics  

Microsoft Academic Search

Like fission-track dating, alpha-recoil track (ART) dating is based on the accumulation of nuclear particles that are released by natural radioactivity and produce etchable tracks in solids. ARTs are formed during the alpha-decay of uranium and thorium as well as of their daughter nuclei. When emitting an alpha-particle, the heavy remaining nucleus recoils 3040 nm, leaving behind a trail of

K. Ggen; G. A. Wagner

2000-01-01

371

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

NASA Astrophysics Data System (ADS)

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

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

1994-01-01

372

Preliminary study of the transport and distribution of radium, radon and their alpha-emitting daughters using nuclear emulsions and polonium-210. Final report  

SciTech Connect

Semi-quantitative Po-210 measurements were made on near surface soil samples near known uranium ore deposits and on closely related diamond drill cores. The physical distribution of uranium and some of its alpha emitting daughter products in these samples was studied qualitatively using alpha sensitive nuclear emulsions. These nuclear emulsion plates suggest that U-238 and its long lived daughters U-234, Th-230 and Ra-226, deposit on grain surfaces in very low concentrations (U-238 in sub picogram amounts). Concentrations of alpha activity usually associated with discrete uranium were not observed. On the basis of alpha star counts in the emulsion, Ra-226 appears to be more mobile than Rn-222. Measurements of Po-210 provide an indirect means of estimating the number of Rn-222 atoms that have decayed over the last 80 to 100 years. Many Po-210 highs have been observed in the Red Desert (Wyoming) cores; some directly associated with uranium mineralization. Evidence was not found for the predicted Po-210 concentration gradient produced by the decay of mobile, unsupported Rn-222. The Po-210 analyses and microscopic studies suggest that observed Rn-222 and Po-210 surface anomalies may be associated with widely dispersed very low concentrations of Ra-226 or its longer lived parents including uranium which surround the ore as halos or as weak zones of uranium mineralization. The Po-210 sub-surface soil anomaly map from this study was also compared with earlier surface anomaly maps from the same area based on helium, radon by Track-Etch and uranium surveys. Selective chemical leaching experiments undertaken in an effort to enhance the mobile Ra-222/Po-210 signal were not successful.

Stieff, L.R.; Balkissoon, I.L.; Barbera, F.M.

1981-03-01

373

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

ERIC Educational Resources Information Center

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

Ouseph, P. J.; Mostovych, Andrew

1978-01-01

374

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

375

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

2009-08-27

376

Possible Stimulation of Nuclear alpha Decay by Superfluid Helium  

SciTech Connect

It is suggested that superfluid helium (condensate of {sup 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.

Barabanov, A. L. [Kurchatov Institute, Moscow 123182 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny 141700, Moscow Region (Russian Federation)

2009-08-28

377

Preparation and combustion properties of {alpha}-Fe{sub 2}O{sub 3} coated Zr particles  

SciTech Connect

Zirconium particles with irregular morphology and broad size distribution were uniformly coated by spherical {alpha}-Fe{sub 2}O{sub 3} crystal grain via a facile route without polymer or surfactant as directing agents. The synthesized {alpha}-Fe{sub 2}O{sub 3}/Zr composite particles were characterized by X-ray diffraction, scanning electron microscopy, energy dispersion X-ray, UV-vis spectroscopy and Raman spectroscopy. The synthesis mechanism could be explained by cooperated heterogeneous nucleation and solid state transformation reaction. The combustion properties of {alpha}-Fe{sub 2}O{sub 3}/Zr composite particles were investigated. Compared with Zr particles, the combustion lasting time decreased from 16 s of Zr particles to 0.13 s of {alpha}-Fe{sub 2}O{sub 3}/Zr composite particles, and the top point of temperature reached in combustion increased from 2004 deg. C of Zr particles to 2378 deg. C of {alpha}-Fe{sub 2}O{sub 3}/Zr particles.

Lv Baoliang [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100039 (China); Xu Yao [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)], E-mail: xuyao@sxicc.ac.cn; Hou Bo; Wu Dong; Sun Yuhan [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)

2008-10-02

378

Phase relations and probabilities of alpha-particle formation in the surface region of even-even nuclei  

Microsoft Academic Search

The concept of the probability of formation Wc of alpha particles in the surface region of nuclei is used in a classification of alpha transitions of even-even deformed nuclei (226 <= A <= 254) to the first four levels of the ground-state rotational band of the daughter nuclei with allowance for coupling of the decay channels. The calculated values of

S. G. Kadmenskii; S. D. Kurgalin

1980-01-01

379

[Modification of the damaging effect of alpha-particles on Escherichia coli K-12 by low-intensity laser irradiation].  

PubMed

A study was made of the combined effect of laser (helium-neon laser, lambda = 633 nm) and alpha-radiation on survival of Escherichia coli K-12 cells of different genotypes. Pre- and post-irradiation exposures to laser-radiation diminished the damaging effect of alpha-particles. In the latter case, modification of survival was more pronounced. PMID:3526394

Voskanian, K Sh; Simonian, N V; Avakian, Ts M; Arutiunian, A G

380

Variation of luminescence decay in BaF2 crystal excited by electrons, alpha particles and fission fragments  

Microsoft Academic Search

The time dependence of the luminescence from BaF2 crystal excited by electrons, alpha particles and fission fragments has been studied for wavelengths of 180-400 nm by a single-photon counting technique. A (220 +\\/- 10) nm component with a lifetime of 0.88 ns is observed for electron and fission fragment excitation. No 220 nm component is observed for alpha particle excitation.

S. Kubota; M. Suzuki; F. Shiraishi; Y. Takami

1986-01-01

381

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

Microsoft Academic Search

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

George C. Rybicki; Christian A. Zorman

1994-01-01

382

The limitations of associated alpha particle technique for contraband container inspections  

NASA Astrophysics Data System (ADS)

Inspection of a shipping container for the presence of the threat materials has been investigated in the laboratory by using a 14 MeV neutron beam, a BaF2 gamma detector and the associated alpha particle technique. The associated alpha particle technique is proposed as a part of a two sensor system for contraband container inspections. This method is effective in the reduction of background radiation with the possibility of collimating electronically the neutron beam. The intrinsic time resolution has been experimentally estimated to be 1.3 ns (FWHM), which allows inspection of a minimum voxel having 7 cm depth along the neutron flight path. The neutron beam intensity plays a crucial role as a limiting factor for the acquisition time reduction. Single counting rates of the gamma and alpha detector were investigated as a function of the neutron intensity, distance between the gamma detector and the neutron source and the type of shielding. The time and the energy spectra for different neutron intensities were evaluated.

Sudac, Davorin; Blagus, Sasa; Valkovic, Vladivoj

2007-10-01

383

Experimental detection of alpha-particles from the radioactive decay of natural bismuth.  

PubMed

The only naturally occurring isotope of bismuth, 209Bi, is commonly regarded as the heaviest stable isotope. But like most other heavy nuclei abundant in nature and characterized by an exceptionally long lifetime, it is metastable with respect to alpha-decay. However, the decay usually evades observation because the nuclear structure of 209Bi gives rise to an extremely low decay probability and, moreover, generates low-energy alpha-particles difficult to detect. Indeed, dedicated experiments attempting to record the alpha-decay of 209Bi in nuclear emulsions failed. However, scintillating bolometers operated at temperatures below 100 mK offer improved detection efficiency and sensitivity, whereas a broad palette of targets could be available. Here we report the successful use of this method for the unambiguous detection of 209Bi alpha-decay in bismuth germanate detectors cooled to 20 mK. We measure an energy release of 3,137 +/- 1 (statistical) +/- 2 (systematic) keV and a half-life of (1.9 +/- 0.2) x 10(19) yr, which are in agreement with expected values. PMID:12712201

de Marcillac, Pierre; Coron, Nol; Dambier, Grard; Leblanc, Jacques; Moalic, Jean-Pierre

2003-04-24

384

Electron-hole pair generation in SiC high-temperature alpha particle detectors  

NASA Astrophysics Data System (ADS)

We demonstrate alpha-particle detection in an n-type 4H-SiC Schottky diode detector up to a temperature of 500 C using an Am-241 disc source. The measured spectra were used to calculate the electron-hole pair creation energy in 4H-SiC and its non-bandgap contribution, which are both found to decrease with increasing temperature. The full width at half maximum (FWHM) of the measured alpha-energy peaks was found to increase exponentially with temperature due to an exponential increase of leakage current. For our measurement system, above 300 C, where the leakage current was 10-6 A, this increase exceeded the FWHM at room temperature.

Garcia, Timothy R.; Kumar, Ashutosh; Reinke, Benjamin; Blue, Thomas E.; Windl, Wolfgang

2013-10-01

385

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

SciTech Connect

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

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

2008-12-15

386

Cytogenetic effects of extremely low doses of plutonium-238 alpha-particle irradiation in CHO K-1 cells.  

PubMed

CHO K-1 cells were irradiated during the G1 phase with 0.5-6 rad of alpha particles. There was no appreciable cell killing in this low dose range. Significantly increased frequencies of sister-chromatid exchanges were induced by doses as low as 0.5 rad of alpha-particle irradiation, whereas increased numbers of chromosomal aberrations were observed following exposure to 2 rad. These results suggest that very low doses of alpha radiation may lead to radiation-induced genetic alterations. PMID:2366817

Nagasawa, H; Little, J B; Inkret, W C; Carpenter, S; Thompson, K; Raju, M R; Chen, D J; Strniste, G F

1990-07-01

387

The Li⁶(. cap alpha. ,2. cap alpha. )d reaction at 50 to 80 MeV  

Microsoft Academic Search

The Li⁶(..cap alpha..,2..cap alpha..)d reaction was studied at 50.4, 59.0, 60.5, 70.3 and 79.6 MeV bombarding energy. For each bombarding energy, several coincident energy spectra of the two emitted ..cap alpha..-particles were measured. The projected energy spectra were analyzed with the Plane Wave Impulse Approximation. From those points in the projected spectra which corresponded to zero deuteron recoil momentum, off-mass-shell

1970-01-01

388

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.

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

2009-01-01

389

ENGINEERED MODULAR RECOMBINANT TRANSPORTERS: APPLICATION OF NEW PLATFORM FOR TARGETED RADIOTHERAPEUTIC AGENTS TO ?-PARTICLE EMITTING 211At  

PubMed Central

Purpose To generate and evaluate a modular recombinant transporter (MRT) for targeting 211At 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-[211At]astato-5-guanidinomethylbenzoate (SAGMB), its 125I analogue SGMIB, or with 131I 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 1020 times more cytotoxic than [211At]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 ?-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this 211At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor.

Rosenkranz, Andrey A.; Vaidyanathan, Ganesan; Pozzi, Oscar R.; Lunin, Vladimir G.; Zalutsky, Michael R.; Sobolev, Alexander S.

2010-01-01

390

An alpha-particle irradiator for radiobiological research and its implementation for bystander effect studies.  

PubMed

An experimental system based on an improved version of an existing alpha-particle irradiator has been developed for radiobiological studies, in particular those investigating bystander effects. It consists of a 20-mm-diameter stainless steel chamber that can be equipped alternatively with 244Cm or 241Am sources of different activities. Mylar-based petri dishes 56 mm in diameter were specially designed to house adaptors for permeable membrane inserts that reproduce the geometry of commercial cell culture insert companion plates. Characterization of the radiation field at the cell level was performed by experimental measurements and calculations. The average incident LET was about 122 keV/microm for 244Cm and about 125 keV/microm for 241Am. Dose rates at the chosen source-sample distance were 2.8 and 88.6 mGy/min, respectively. These low dose rates are suitable for our planned experiments on low-dose effects. For both sources, the uniformity of the alpha-particle dose was better than +/-7%, and the photon dose calculated at the cell entrance was negligible compared to the alpha-particle dose. The irradiator is small enough to be inserted into a cell incubator for irradiation under physiological conditions or into a refrigerator to prevent metabolic processes during irradiation. Benchmark experiments using the 241Am source to examine DNA double-strand breaks in directly hit and bystander primary human fibroblasts have shown that the irradiator can be used successfully for bystander effect studies. PMID:19883232

Esposito, Giuseppe; Antonelli, Francesca; Belli, Mauro; Campa, Alessandro; Simone, Giustina; Sorrentino, Eugenio; Tabocchini, Maria Antonella

2009-11-01

391

Excited analog state of /sub. lambda. //sup 12/C and the alpha-particle model  

SciTech Connect

The idea that /sub ..lambda..//sup 12/C* is a strangeness analog state is examined using the alpha particle model. Volkov, Gillet, and Brink-Boeker potentials are used for the nucleon-nucleon and lambda-nucleon interactions, to calculate the binding energies of /sup 12/C and /sub ..lambda..//sup 12/C*. /sup 12/C is described by an equilateral triangle. When an allowance is made for the exchange character of the potentials used, the required potential strengths seem to be consistent with those obtained from low energy and light hypernuclear data, thus supporting the idea of a strangeness analog state.

Mukherjee, S.; Panchapakesan, N.

1982-10-01

392

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

NASA Astrophysics Data System (ADS)

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

Campbell, J. L.

2012-10-01

393

Chemistry of rocks and soils in Gusev Crater from the alpha particle x-ray spectrometer.  

PubMed

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. PMID:15297665

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

2004-08-01

394

Chemistry of rocks and soils at Meridiani Planum from the Alpha Particle X-ray Spectrometer.  

PubMed

The Alpha Particle X-ray Spectrometer on the Opportunity rover determined major and minor elements of soils and rocks in Meridiani Planum. Chemical compositions differentiate between basaltic rocks, evaporite-rich rocks, basaltic soils, and hematite-rich soils. Although soils are compositionally similar to those at previous landing sites, differences in iron and some minor element concentrations signify the addition of local components. Rocky outcrops are rich in sulfur and variably enriched in bromine relative to chlorine. The interaction with water in the past is indicated by the chemical features in rocks and soils at this site. PMID:15576611

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

2004-12-01

395

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

396

Optical potentials for alpha particles on Ca isotopes at 1.37 GeV  

Microsoft Academic Search

A phenomenological optical-model analysis is performed for the elastic scattering of alpha particles on 40.42,44,48Ca at 1.37 GeV. Two geometries are considered for optical potentials, i.e., the traditional Woods-Saxon form and the double-Woods-Saxon form which can represent a change of the potential shape from the Woods-Saxon one. Among them, the best-fit potential has a ``Mexican-hat'' shape which is characterized by

M. Nakano; H. Matsuura; T. Maki; M. Matoba; H. Ohgaki

1989-01-01

397

Elevated sodium chloride concentrations enhance the bystander effects induced by low dose alpha-particle irradiation.  

PubMed

Previous studies have shown that high NaCl can be genotoxic, either alone or combined with irradiation. However, little is known about the relationship between environmental NaCl at elevated conditions and radiation-induced bystander effects (RIBE). RIBE, which has been considered as non-targeted bystander responses, has been demonstrated to occur widely in various cell lines. In the present study, RIBE under the elevated NaCl culture condition was assessed in AG 1522 cells by both the induction of gamma-H2AX, a reliable marker of DNA double-strand break (DSB) for the early process (<1h post irradiation), and the generation of micronuclei (MN), a sensitive marker for relative long process of RIBE. Our results showed that in the absence of irradiation, NaCl at elevated concentration such as 8.0, 9.0 and 10.0g/L did not significantly increase the frequency of gamma-H2AX foci-positive cells and the number of foci per positive cell comparing with that NaCl at a normal concentration (6.8g/L). However, with 0.2cGy alpha-particle irradiation, the induced fraction of gamma-H2AX foci-positive cells and the number of induced gamma-H2AX foci per positive cell were significantly increased in both irradiated and adjacent non-irradiated regions. Similarly, the induction of MN by 0.2cGy alpha-particle irradiation also increased with the elevated NaCl concentrations. With N(G)-methyl-l-arginine, an inhibitor of nitric oxide synthase, the induced fraction of foci-positive cells was effectively inhibited both in 0.2cGy alpha-particle irradiated and adjacent non-irradiated regions under either normal or elevated NaCl conditions. These results suggested that the cultures with elevated NaCl medium magnified the damage effects induced by the low dose alpha-particle irradiation and nitric oxide generated by irradiation was also very important in this process. PMID:17560616

Han, Wei; Zhu, Lingyan; Jiang, Erkang; Wang, Jun; Chen, Shaopeng; Bao, Linzhi; Zhao, Ye; Xu, An; Yu, Zengliang; Wu, Lijun

2007-05-05

398

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

SciTech Connect

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

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

1991-10-01

399

Development of a He{sup 0} Source for Confined Alpha Particle Measurement  

SciTech Connect

A probing He{sup 0} beam for confined alpha particle measurement using a double charge exchange process is now under development. A proof of principle experiment for ground-state He{sup 0} beam production will be performed on a test stand. Several methods are developed to measure the metastable fraction of a He{sup 0} beam. A full-size strong-focusing He{sup +} source has been constructed and sufficient beam current was achieved with a beam size tolerable to be used on ITER.

Tanaka, N.; Kisaki, M.; Iwazaki, K.; Kikuchi, M.; Okamoto, A.; Kobuchi, T.; Shinto, K.; Kitajima, S.; Sasao, M. [Tohoku University, Sendai 980-8579 (Japan); Tsumori, K.; Kaneko, O. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Wada, M. [Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan)

2008-03-12

400

Chemistry of Rocks and Soils at Meridiani Planum from the Alpha Particle X-ray Spectrometer  

NASA Astrophysics Data System (ADS)

The Alpha Particle X-ray Spectrometer on the Opportunity rover determined major and minor elements of soils and rocks in Meridiani Planum. Chemical compositions differentiate between basaltic rocks, evaporite-rich rocks, basaltic soils, and hematite-rich soils. Although soils are compositionally similar to those at previous landing sites, differences in iron and some minor element concentrations signify the addition of local components. Rocky outcrops are rich in sulfur and variably enriched in bromine relative to chlorine. The interaction with water in the past is indicated by the chemical features in rocks and soils at this site.

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

2004-12-01

401

THE ROLE OF ALPHA PARTICLES IN THE EVOLUTION OF THE SOLAR-WIND TURBULENCE TOWARD SHORT SPATIAL SCALES  

SciTech Connect

We present a numerical study of the kinetic dynamics of protons and alpha particles during the evolution of the solar-wind turbulent cascade, in which the energy injected in large-scale slab-type Alfvenic fluctuations is transferred toward short spatial scale lengths, across the proton skin depth. We make use of a hybrid Vlasov-Maxwell code that integrates numerically the Vlasov equation for both the ion species, while the electrons are considered as a fluid. The system evolution is investigated in terms of different values of the electron to proton and alpha particle to proton temperature ratios. The numerical results show that the previously studied kinetic dynamics of protons is not strongly affected by the presence of alpha particles, at least when they are present in low concentration. Our simulations not only provide a physical explanation for the generation of beams of accelerated particles along the direction of the ambient magnetic field for both protons and alpha particles, but also show that this mechanism is more efficient for protons than for alpha particles, in agreement with recent solar-wind data analyses.

Perrone, D.; Valentini, F.; Veltri, P. [Dipartimento di Fisica and CNISM, Universita della Calabria, I-87030 Rende (Italy)

2011-11-01

402

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

PubMed

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

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

2007-03-01

403

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

404

DISCOVERY OF STRONG IRON K{alpha} EMITTING COMPTON THICK QUASARS AT z = 2.5 AND 2.9  

SciTech Connect

We report the detection of the 6.4 keV iron K{alpha} emission line in two infrared-luminous, massive, star-forming BzK galaxies at z = 2.578 and z = 2.90 in the CDF-S. The Chandra 4 Ms spectra of BzK 4892 and BzK 8608 show a reflection-dominated continuum with strong iron lines, with rest-frame equivalent widths EW {approx} 2.3 keV and 1.2 keV, respectively, demonstrating Compton thick (CT) obscuration of the central active galactic nucleus (AGN). For BzK 8608, the line identification closely matches the existing photometric redshift derived from the stellar emission. We use the observed luminosities of the iron K{alpha} line, of the rest-frame mid-IR continuum and of the UV rest-frame narrow emission lines to infer intrinsic L{sub 2-10}{sub keV} {approx}> 10{sup 44} erg s{sup -1}, about 1.0-2.5 dex larger than the observed ones, hence confirming the presence of an absorber with N{sub H}>10{sup 24} cm{sup -2}. The two BzK galaxies have stellar masses of 5 x 10{sup 10} M{sub sun} and, based on Very Large Array 1.4 GHz and submillimeter 870 {mu}m observations, they appear to host vigorous starburst activity with star formation rate {approx} 300-700 M{sub sun} yr{sup -1} that is also optically thick. We estimate that the AGN might also conceivably account for an important fraction of the bolometric far-IR emission of the galaxies. The implied volume density of CT AGN with L{sub 2-10}{sub keV}>10{sup 44} erg s{sup -1} is in agreement with predictions from X-ray background synthesis models. These sources provide one of the first clear-cut observations of the long-sought phase of simultaneous, heavily obscured quasar and star formation activity, predicted by models of massive galaxy evolution at high redshifts.

Feruglio, C.; Daddi, E. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d'Astrophysique, CEA Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex (France); Fiore, F.; Piconcelli, E. [INAF-Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone (Italy); Alexander, D. M. [Department of Physics, Durham University, South Road, DH1 3LE (United Kingdom); Malacaria, C., E-mail: chiara.feruglio@cea.fr [Universita' La Sapienza, Piazzale Aldo Moro 5, 00185 Roma (Italy)

2011-03-01

405

Effects of alpha particle radiation on gene expression in human pulmonary epithelial cells.  

PubMed

The general public receives approximately half of its exposure to natural radiation through alpha (?)-particles from radon ((222)Rn) gas and its decay progeny. Epidemiological studies have found a positive correlation between exposure to (222)Rn and lung carcinogenesis. An understanding of the transcriptional responses involved in these effects remains limited. In this study, genomic technology was employed to mine for subtle changes in gene expression that may be representative of an altered physiological state. Human lung epithelial cells were exposed to 0, 0.03, 0.3 and 0.9Gy of ?-particle radiation. Microarray analysis was employed to determine transcript expression levels 4h and 24h after exposure. A total of 590 genes were shown to be differentially expressed in the ?-particle radiated samples (false discovery rate (FDR)?0.05). Sub-set of these transcripts were time-responsive, dose-responsive and both time- and dose-responsive. Pathway analysis showed functions related to cell cycle arrest, and DNA replication, recombination and repair (FDR?0.05). The canonical pathways associated with these genes were in relation to pyrimidine metabolism, G2/M damage checkpoint regulation and p53 signaling (FDR?0.05). Overall, this gene expression profile suggests that ?-particle radiation inhibits DNA synthesis and subsequent mitosis, and causes cell cycle arrest. PMID:22608759

Chauhan, Vinita; Howland, Matthew; Mendenhall, Amy; O'Hara, Shifawn; Stocki, Trevor J; McNamee, James P; Wilkins, Ruth C

2012-05-17

406

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.

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

2011-01-01

407

Partition of thorium between organs of monkeys injected with thorotrast: implications for alpha-particle dosimetry.  

PubMed

Risk estimates for alpha-particle-induced malignancies have been based mainly on studies of Thorotrast patients, but certain aspects of its deposition in the body have been at issue: the partition between the liver, spleen and red bone marrow, and the deposition at lower concentrations in other organs, such as muscle and fat, which may contribute to the risk. To supplement the existing data for humans, thorium concentrations were measured in the organs of two female monkeys 3-4 years after injection with Thorotrast. Relative deposits (liver:spleen:red bone marrow) were 54:6:41 and 75:4:21, in better agreement with the most recent observations in Thorotrast patients than with previous reports. Whereas the human testis had ranked among intermediate-level organs such as the adrenal glands and pancreas, the ovary of the monkey was among the organs with the lowest concentrations. The data suggest that risk factors for induction of malignancies by alpha-particle irradiation should be re-examined. PMID:9728666

Ishikawa, Y; Humphreys, J A; Wesch, H; Priest, N D

1998-09-01

408

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

409

Possible observation of light neutron nuclei in the alpha-particle-induced fission of 238U  

NASA Astrophysics Data System (ADS)

Searches for nuclear-stable multineutrons among products originating from the fission of 238U nuclei that is induced by 62-MeV alpha particles were performed by the activation method. The reaction involving the transfer of four neutrons and occurring on the isotope 88Sr, 88Sr( x n, ( x - 4) n)92Sr?92Y, was used to identify nuclear-stable multineutrons. A line at the energy of E = 1384 keV was found in the measured gamma-ray spectra of irradiated samples. This line, together with the measured time dependence of the decrease in its activity, is indicative of the formation of the beta-active nucleus 92Sr. This result was reproduced in repeated measurements. It suggests the possible existence of nuclear-stable multineutrons ( x n) for x ? 6. The differential cross section for the x n yield at an angle of 30 in the alpha-particle-induced fission of 238U was about 6 10-2 mb/sr.

Novatsky, B. G.; Nikolsky, E. Yu.; Sakuta, S. B.; Stepanov, D. N.

2012-11-01

410

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

PubMed

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

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

2012-03-29

411

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

NASA Astrophysics Data System (ADS)

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

Hellinger, Petr; Trvn?ek, Pavel M.

2013-09-01

412

Targeted Cytoplasmic Irradiation with Alpha Particles Induces Mutations in Mammalian Cells  

NASA Astrophysics Data System (ADS)

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

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

1999-04-01

413

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.

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

1999-01-01

414

Systematics of pre- and near-scission {alpha}-particle multiplicities in heavy-ion-induced fusion-fission reactions  

SciTech Connect

The {alpha}-particle energy spectra have been measured in coincidence with fission fragments over a wide range of relative angles with respect to fragment emission direction in the {sup 11}B (62 MeV) + {sup 232}Th reaction. The {alpha}-particle multiplicity spectra have been fitted with moving source model to extract the precision ({alpha}{sub pre}) and near-scission ({alpha}{sub nse}) components. The present results, along with available data from the literature over a wide range of Z{sup 2}/A and the excitation energy of a compound system, have been analyzed to develop certain global features of the pre- and near-scission emission characteristics. It is seen that {alpha}{sub pre} values when normalized to E{sub CN}{sup 2.3} (E{sub CN} is the compound nucleus excitation energy) show a systematic linearly increasing trend with the {alpha}-particle emission Q value (Q{sub {alpha}}). The fraction of near-scission multiplicity is observed to be nearly the same at around 10% of the total precision multiplicity for all the systems.

Gupta, Y. K.; Biswas, D. C.; Choudhury, R. K.; Saxena, A.; Nayak, B. K.; John, Bency; Ramachandran, K.; Thomas, R. G.; Danu, L. S.; Joshi, B. N.; Mahata, K.; Pandit, S. K.; Chatterjee, A. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2011-09-15

415

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