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1

Effects of Xe-ion irradiation at high temperature on single crystal rutile  

Microsoft Academic Search

Rutile (TiO2) single crystals with (110) orientation were irradiated with 360 keV Xe2+ ions at 923 K to fluences ranging from 7×1014 to 1×1016 Xe\\/cm2. Damage accumulation and evolution were analyzed using Rutherford backscattering spectroscopy combined with ion channeling analysis, and cross-sectional transmission electron microscopy. TiO2 crystals were found to exhibit a layer-like damage structure after irradiation, with up to

Fuxin Li; Ping Lu; K. E Sickafus

2002-01-01

2

TEM study of damage recovery in SiC by swift Xe ion irradiation  

NASA Astrophysics Data System (ADS)

The microstructure of 4H-SiC samples subsequently irradiated with low energy He (10 keV), Ti (220 keV) and high energy (167 MeV) Xe ions has been studied using cross-sectional transmission electron microscopy. It was found that xenon ions with fluences above 1013 cm-2 restore crystallinity in a heavily damaged partially amorphous zone. No, or negligible damage recovery is observed in fully amorphized layers of silicon carbide.

Skuratov, V. A.; O'Connell, J.; Sohatsky, A. S.; Neethling, J.

2014-05-01

3

Teflon impregnated anatase TiO2 nanoparticles irradiated by 80 keV Xe+ ions  

NASA Astrophysics Data System (ADS)

We report the effect of 80 keV Xe+ ion irradiation on the morphological and optical responses of TiO2 nanoparticles spread over commercially available polytetrafluoroethylene (PTFE, Teflon). These nanoparticles were synthesized via a convenient, sol-gel approach with titanium isopropoxide as the main precursor. From X-ray diffraction (XRD) studies we found that, the nanoparticles crystallize in anatase phase and with a preferential orientation of crystallites along (1 0 1) plane. Upon irradiation at a fluence of 1.25 × 1017 ions/cm2, the nanoparticle dimension was found to increase from a value of ˜9 nm to ˜20-30 nm. Essentially, particle growth is predicted as a consequence of swelling behavior accompanied by the formation of Xe van der Waal crystals in isolated regions of nano-titania. Evidence of nanoripples was also witnessed on the surface of the irradiated nano-titania. The morphological evolution was assessed both by atomic force and transmission electron microscopies (AFM and TEM) independently. From the UV-Vis optical absorption studies, the estimated optical band gap was found to drop with increasing fluence, while refractive index exhibited a remarkable improvement. Photoluminescence (PL) studies have revealed that, the band edge emission and those due to the self trapped excitons (STE) and other oxygen vacancy related ones were manifested considerably as a result of Xe ion irradiation.

Khanam, Rizwin; Paul, Nibedita; Kumar, P.; Kanjilal, D.; Ahmed, Gazi A.; Mohanta, Dambarudhar

2014-10-01

4

Irradiation system of ions (H-Xe) for biological studies near the Bragg peak  

NASA Astrophysics Data System (ADS)

We have developed a new system for irradiating biological samples in air with ions from H to Xe below 6.0MeV/nucleon near the Bragg peak. The irradiation system can provide ion beams with 20-mm diameter of which the central area of 100mm2 is uniform in fluence rate within a standard deviation of ±10%. For each ion, the linear energy transfer is selectable by irradiation positions in air, from the lowest at the surface of a vacuum window to the highest at the Bragg peak, for example, from 281 to 977 keV/?m for C ions. A wide range of fluence rates, 10-3-104ions/?m2/s, can be provided by the system, which makes it possible to irradiate a variety of biological samples with different target sizes, from small plasmid DNA to living mammalian cells. The ion fluence irradiated to each sample is calculated from the output of the secondary electron monitor using the linear relationship between the output and ion fluence measured at the sample position by CR-39 track detectors. Survival curves and visualization of NBS1 foci for human cells are presented as examples of preliminary experiments using C ions near the Bragg peak.

Konishi, Teruaki; Yasuda, Nakahiro; Takeyasu, Akihiro; Ishizawa, Sachi; Fujisaki, Takashi; Matsumoto, Kenichi; Furusawa, Yoshiya; Sato, Yukio; Hieda, Kotaro

2005-11-01

5

Irradiation system of ions (H-Xe) for biological studies near the Bragg peak  

SciTech Connect

We have developed a new system for irradiating biological samples in air with ions from H to Xe below 6.0 MeV/nucleon near the Bragg peak. The irradiation system can provide ion beams with 20-mm diameter of which the central area of 100 mm{sup 2} is uniform in fluence rate within a standard deviation of {+-}10%. For each ion, the linear energy transfer is selectable by irradiation positions in air, from the lowest at the surface of a vacuum window to the highest at the Bragg peak, for example, from 281 to 977 keV/{mu}m for C ions. A wide range of fluence rates, 10{sup -3}-10{sup 4} ions/{mu}m{sup 2}/s, can be provided by the system, which makes it possible to irradiate a variety of biological samples with different target sizes, from small plasmid DNA to living mammalian cells. The ion fluence irradiated to each sample is calculated from the output of the secondary electron monitor using the linear relationship between the output and ion fluence measured at the sample position by CR-39 track detectors. Survival curves and visualization of NBS1 foci for human cells are presented as examples of preliminary experiments using C ions near the Bragg peak.

Konishi, Teruaki; Yasuda, Nakahiro; Takeyasu, Akihiro; Ishizawa, Sachi; Fujisaki, Takashi; Matsumoto, Kenichi; Furusawa, Yoshiya; Sato, Yukio; Hieda, Kotaro [Department of Life Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan); National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Department of Life Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan); Department of Physics, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510 (Japan); National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Department of Life Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan)

2005-11-15

6

Anisotropic deformation of Au nanoparticles by highly charged ion Xe21+ irradiation  

NASA Astrophysics Data System (ADS)

We present a detailed study of the deformation of Au nanoparticles (NPs) caused by the irradiation of highly charged ions (HCIs). When spherical Au NPs with a diameter of 19.8 nm were irradiated by 1 MeV Xe21+ ions with a fluence of 2 × 1014 cm-2, their anisotropic deformation was observed by atomic force microscopy. The results show that spherical Au NPs expand perpendicular to the ion beam changing their shape to oblate ellipsoidal. The size aspect ratio (major over minor axis) of the observed deformed Au NPs is about 1.23. The deformation process is described by a viscoelastic thermal spike model. The HCI beam deformation technique provides a unique method to tailor the shape of noble metal NPs.

Liu, Xueliang; Xu, Zhongfeng; Zhao, Yongtao; Liu, Lili; Wang, Yuyu; Chen, Liang; Li, Dehui; Zeng, Lixia; Zhao, Di; Xiao, Guoqing

2013-09-01

7

In situ TEM investigation of Xe ion irradiation induced defects and bubbles in pure molybdenum single crystal  

NASA Astrophysics Data System (ADS)

In order to study irradiation damage and inert gas bubble formation and growth behaviors, and to provide results and insights useful towards the validation of a multi-scale simulation approach based on a newly developed Xe-Mo inter-atomic potential, in situ Transmission Electron Microscopy (TEM) studies of Xe implantations in pure single crystal Molybdenum (Mo) have been conducted. 300 keV and 400 keV Xe+ ion beams were used to implant Xe in pre-thinned TEM Mo specimens. The irradiations were conducted at 300 °C and 600 °C to ion fluence up to 4 × 1016 ions/cm2. In situ TEM characterization allows detailed behaviors of defect clusters to be observed and is very useful in illustrating defect interaction mechanisms and processes. Dislocation loops were found to form at relatively low irradiation fluence levels. The characterization results showed that the free surfaces, formed in the process of producing pre-thinned specimens, play an important role in influencing the behaviors of dislocation loops. Similar characterizations were conducted at high fluence levels where Xe gas bubbles can be clearly observed. Xe gas bubbles were observed to form by a multi-atom nucleation process and they were immobile throughout the irradiation process at both temperatures. Measurements on both the number density and the size of dislocation loops and gas bubbles were taken. The results and implications of the measurements are discussed in this paper.

Yun, Di; Kirk, Marquis A.; Baldo, Peter M.; Rest, Jeffrey; Yacout, Abdellatif M.; Insepov, Zinetula Z.

2013-06-01

8

Evolution of amorphization and nanohardness in SiC under Xe ion irradiation  

NASA Astrophysics Data System (ADS)

Amorphization and nanohardness changes of SiC irradiated with 7 MeV Xenon ions at doses from 0.006 to 2 dpa were investigated. At a dose of 0.6 dpa, the results of Raman spectrum reveal the formation of Si-Si and C-C bonds within the SiC network while TEM results show the appearance of amorphous islands. The hardness of irradiated SiC is regarded as a combined result of covalent-bond damage and hardening effect of defects. In the low dpa regime (<0.06 dpa), the hardness of irradiated SiC increases with increasing dose, which is mainly caused by hardening effect. Up to 0.06 dpa, the hardening increases about 20.3%. And an equilibrium is reached between the covalent-bond damage and the hardening effect when irradiated SiC begins to amorphize (0.6 dpa). Above the dose of 0.6 dpa, the hardness decreases strongly due to the grievous covalent-bond damage.

Li, Jianjian; Huang, Hefei; Lei, Guanhong; Huang, Qing; Liu, Renduo; Li, Dehui; Yan, Long

2014-11-01

9

Effect of 690-keV Xe ion irradiation on the microstructure of amorphous MoSi 2/SiC nanolayer composites  

NASA Astrophysics Data System (ADS)

The effect of 690-keV Xe ion irradiation at three different dosage levels, 1 × 10 15, 5 × 10 15 and 10 × 10 15 /cm 2, on the microstructure of amorphous-MoSi 2/amorphous-SiC nanolayer composites has been studied using transmission electron microscopy. Results show that the depth of radiation damage in this multilayer material is ˜ 80 nm, which agrees qualitatively well with the calculated damage depth calculated by TRIM [1]. A diffraction ring corresponding to the (10 overlinel1) plane of C40 MoSi 2 was found in the electron diffraction pattern taken from the irradiated regions; the C40 phase is also found after thermal annealing of amorphous MoSi 2 at 500°C or above. In the damaged regions SiC layers were found to spheroidize while the nanocrystalline grains in the MoSi 2 layers appeared to coarsen with increasing dose.

Lu, Y.-C.; Kung, H.; Jervis, T. R.; Hirvonen, J.-P.; Rück, D.; Mitchell, T. E.; Nastasi, M.

10

Phase stability, grain growth and photoluminescence property of nanocrystalline yttria-stabilized zirconia film under 500 keV Xe6+ ion irradiation  

NASA Astrophysics Data System (ADS)

Nanocrystalline yttria stabilized zirconia (YSZ) film (with 8 mol% Y2O3) was synthesized via a sol-gel method. Phase stability, grain-growth and defects of the YSZ film were investigated under 500 keV Xe6+ ions irradiation to doses up to an average value of 22.2 displacements per atom (dpa). Atomic force microscope results show that the surface of the as-grown YSZ film is quite smooth and free of cracks. Transmission electron microscope results reveal that the average grain-size of the as-grown samples is around 12.6 nm. With increasing irradiation does up to 22.2 dpa, the average grain size increases, no phase transformation or amorphization is observed, which indicates that the phase structure of the nanocrystalline cubic YSZ film is quite stable. Two strong and broad emission peaks were detected in the YSZ film, and the emission intensity decreases obviously after irradiation. The possible mechanism of the grain growth was also discussed.

Chen, Lin; Chang, Yongqin; Guo, Qiang; Zhang, Jing; Wan, Farong; Long, Yi

2014-06-01

11

Melting and crystallization of Xe nanoprecipitates in Al under 1 MeV electron irradiation  

Microsoft Academic Search

Xe nanoprecipitates have been produced by ion implantation into high purity Al at 300 K. With an off-zone axis high resolution imaging technique, Xe nanocrystals may be clearly structure imaged against a weak structure image of the Al matrix. Under the 1 MeV electron irradiation employed for the HREM observation, the nanoprecipitates exhibit a number of readily observed phenomena including

C. W. Allen; R. C. Birtcher; S. E. Donnelly; M. Song; K. Furuya; K. Mitsuishi; N. Ishikawa

2002-01-01

12

Effect of 690 keV Xe ion irradiation on the microstructure of amorphous MoSi{sub 2}/SiC nanolayer composites  

SciTech Connect

The effect of 690 keV Xe ion irradiation at three different dosage levels, 1, 5 and 10{times}10{sup 15}/cm{sup 2}, on the microstructure of amorphous-MoSi{sub 2}/amorphous-SiC nanolayer composites has been studied using transmission electron microscopy. Results show that the depth of radiation damage in this multilayer material is {approximately}80 nm, which agrees qualitatively well with the calculated damage depth calculated by TRIM. A diffraction ring corresponding to the (10{bar 1}1) plane of C40 MoSi{sub 2} was found in the electron diffraction pattern taken from the irradiated regions; the C40 phase is also found after thermal annealing of amorphous MoSi{sub 2} at 500{degrees}C or above. In the damaged regions SiC layers were found to spherodize while the nanocrystalline grains in the MoSi{sub 2} layers appeared to coarsen with increasing dose.

Lu, Y.C.; Kung, H.; Jervis, T.R.; Mitchell, T.E.; Nastasi, M. [and others

1996-10-01

13

Behavior of nanocrystalline Xe precipitates in Al under 1 MeV electron irradiation.  

SciTech Connect

Crystalline nanoprecipitates of Xe have been produced by ion implantation into high purity Al at 300 K. With an off-zone axis TEM imaging technique, the nanocrystals may be clearly structure imaged against a nearly featureless background. Under the 1 MeV electron irradiation employed for the HREM observation, Xe nanocrystals exhibit a number of readily observed physical phenomena including migration within the matrix, changes in shape, faulting, melting, crystallization and coalescence. The various phenomena observed as changes in the Xe nanocrystals reflect changes of matrix cavity-surface structure. The Xe nanocrystal thus allows investigation indirectly into changes in interface morphology at the atomic level, resulting in this instance from electron irradiation damage. Such changes have heretofore been inaccessible to observation.

Allen, C. W.; Birtcher, R. C.; Donnelly, S. E.; Furuya, K.; Mitsuishi, K.; Song, M.

1999-03-10

14

ion irradiation  

NASA Astrophysics Data System (ADS)

Fine Co and Pt nanoparticles are nucleated when a silica sample is implanted with 400 keV Co+ and 1370 keV Pt+ ions. At the implanted range, Co and Pt react to form small Co x Pt(1- x) nanoparticles during Si+ ion irradiation at 300 °C. Thermal annealing of the pre-implanted silica substrate at 1000 °C results in the formation of spherical nanoparticles of various sizes. When irradiated with Si+ ions at 300 °C, particles in the size range of 5-17 nm undergo rod-like shape transformation with an elongation in the direction of the incident ion beam, while those particles in the size range of 17-26 nm turn into elliptical shape. Moreover, it is suspected that very big nanoparticles (size >26 nm) decrease in size, while small nanoparticles (size <5 nm) do not undergo any transformation. During Si+ ion irradiation, the crystalline nature of the nanoparticles is preserved. The results are discussed in the light of the thermal spike model.

Balaji, S.; Panigrahi, B. K.; Saravanan, K.; David, C.; Amirthapandian, S.; Kalavathi, S.; Nair, K. G. M.; Hübner, René

2014-09-01

15

Xe precipitates at grain boundaries in Al under 1 MeV electron irradiation.  

SciTech Connect

Crystalline nanoprecipitates of Xe have been produced by ion implantation into mazed bicrystalline Al at 300 K, in which the matrix grain boundaries are mainly 90 deg tilt boundaries. Within Al grains, Xe nanocrystals are fee, isotactic with the Al and cuboctohedral in shape with {l_brace}111{r_brace} and {l_brace}100{r_brace} facets. With an off-axial imaging technique, the nanocrystals were structure imaged against a relatively featureless matrix background. In contrast to metal precipitates in Al, such as Pb, Xe precipitates straddling a matrix grain boundary are bicrystals as small as approximately 2 nm in diameter. Larger Xe precipitates tend to avoid boundaries which are inclined away from asymmetrical orientation and which thus have a significant twist component. Under the 1 MeV electron irradiation employed for HREM observation, small Xe nanocrystals near a grain boundary may migrate to the boundary and coalesce with other Xe precipitates. The structural observations are rationalized on a simple geometrical interpretation.

Allen, C. W.

1998-10-23

16

Sputtering of Au induced by single Xe ion impacts  

SciTech Connect

Sputtering of Au thin films has been determined for Xe ions with energies between 50 and 600 keV. In-situ transmission electron microscopy was used to observe sputtered Au during deposition on a carbon foil near the specimen. Total reflection and transmission sputtering yields for a 62 nm thick Au thin film were determined by ex-situ measurement of the total amount of Au on the carbon foils. In situ observations show that individual Xe ions eject Au nanoparticles as large as 7 nm in diameter with an average diameter of approximately 3 nm. Particle emission correlates with crater formation due to single ion impacts. Nanoparticle emission contributes significantly to the total sputtering yield for Xe ions in this energy range in either reflection or transmission geometry.

Birtcher, R. C.; Donnelly, S. E.

1999-12-06

17

Experimental ion mobility measurements in Xe-N2 mixtures  

NASA Astrophysics Data System (ADS)

In this paper we present the results for the ion mobility measurements made in gaseous mixtures of xenon (Xe) and nitrogen (N2) for low reduced electric fields (in the 15 Td to 30 Td range), at room temperature. The choice of reduced electric fields was guided by typical gaseous detector's demands. In the 0-100% range of Xe concentrations in the mixture, only one peak was observed which was attributed to Xe2+; in fact its mobility was found to follow Blanc's law. A typical time-of-arrival spectrum for 90% Xe and 10% N2 is shown. The reduced mobilities, obtained from the peaks, are calculated and presented in this paper.

Garcia, A. N. C.; Neves, P. N. B.; Trindade, A. M. F.; Cortez, A. F. V.; Santos, F. P.; Conde, C. A. N.

2014-07-01

18

Improved field emission of electrons from ion irradiated carbon  

Microsoft Academic Search

Electron field emission from allotropes of carbon (graphite, diamondlike carbon, and diamond) have been reported many times in the literature. This work explores the use of ion irradiation for improving electron field emission from carbon fibers. Carbon fibers have been irradiated with H, C, Ar, and Xe ions. Field emission characteristics have been measured as a function of ion dose.

K. C. Walter; H. H. Kung; C. J. Maggiore

1997-01-01

19

Molecular dynamic studies on anisotropic explosion of laser irradiated Xe cluster  

SciTech Connect

A three dimensional molecular dynamic model is used to investigate the dynamics of Xe clusters of various radii irradiated by laser of moderate intensities ({approx}10{sup 14}-10{sup 16}W/cm{sup 2}). The FWHM pulse duration of the laser is varied from few laser cycles to hundreds of femtosecond. For cluster of radius 50 A irradiated by a laser of 170 fs pulse duration, it is observed that ion yield is more along the direction of laser polarization than perpendicular to it. This trend reverses (more ions are emitted along the direction perpendicular to laser polarization than parallel to it) when laser pulses of few cycles are used. This reversal of anisotropy is explained on the basis of spatial shielding of ions due to the oscillating inner electron cloud along direction of laser electric field. The nature of anisotropy remains same with variations in laser intensity and cluster size.

Mishra, Gaurav; Gupta, N. K. [Theoretical Physics Division, Bhabha Atomic Research Centre, Mumabi-400085 (India)

2012-09-15

20

1.2 MeV/amu Xe ion induced damage recovery in SiC  

NASA Astrophysics Data System (ADS)

The microstructural changes of 4H-SiC samples dual irradiated with either low energy He (10 keV) or Ti (220 keV) and high energy (167 MeV) Xe ions has been studied using cross-sectional transmission electron microscopy. It was found that xenon ions with fluences above 1013 cm-2 restore crystallinity in a heavily damaged partially amorphous zone. No significant damage recovery was observed in fully amorphized layers of silicon carbide apart from a 5% reduction in the amorphous layer thickness.

O'Connell, J. H.; Skuratov, V. A.; Sohatsky, A. S.; Neethling, J. H.

2014-05-01

21

Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation  

NASA Astrophysics Data System (ADS)

This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects.

Chang, Yongqin; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

2014-12-01

22

Zirconium oxidation under high energy heavy ion irradiation N. Brerd, A. Chevarier, N. Moncoffre, H. Jaffrezic,  

E-print Network

Zirconium oxidation under high energy heavy ion irradiation N. Bérerd, A. Chevarier, N. Moncoffre This paper concerns the study of zirconium oxidation under irradiation with high energetic Xe ions oxidation data. 1 #12;I. INTRODUCTION This paper deals with the influence of heavy ion irradiation

Paris-Sud XI, Université de

23

Calculation of Ion Charge State Distributions After Inner-Shell Ionization in Xe Atom  

SciTech Connect

The vacancy cascades following initial inner-shell vacancies in single and multi-ionized atoms often lead to highly charged residual ions. The inner-shell vacancy produced by ionization processes may decay by either a radiative or non-radiative transition. In addition to the vacancy filling processes, there is an electron shake off process due to the change of core potential of the atom. In the calculation of vacancy cascades, the radiative (x-ray) and non-radiative (Auger and Coster-Kronig) branching ratios give valuable information on the de-excitation dynamics of an atom with inner-shell vacancy. The production of multi-charged ions yield by the Auger cascades following inner shell ionization of an atom has been studied both experimentally and theoretically. Multi-charged Xe ions following de-excitation of K-, L{sub 1}-, L{sub 2,3}-, M{sub 1}-, M{sub 2,3}- and M{sub 4,5} subshell vacancies are calculated using Monte-Carlo algorithm to simulate the vacancy cascade development. Fluorescence yield (radiative) and Auger, Coster- Kronig yield (non- radiative) are evaluated. The decay of K hole state through radiative transitions is found to be more probable than non-radiative transitions in the first step of de-excitation. On the other hand, the decay of L, M vacancies through non-radiative transitions are more probable. The K shell ionization in Xe atom mainly yields Xe{sup 7+}, Xe{sup 8+}, Xe{sup 9+} and Xe{sup 10+} ions, and the charged X{sup 8+} ions are the highest. The main product from the L{sub 1}- shell ionization is found to be Xe{sup 8+}, Xe{sup 9+} ions, while the charged Xe{sup 8+} ions predominate at L{sub 2,3} hole states. The charged Xe{sup 6+}, Xe{sup 7+} and Xe{sup 8+} ions mainly yield from 3s{sub 1/2} and 3p{sub 1/2,3/2} ionization, while Xe in 3d{sub 3/2,5/2} hole states mainly turns into Xe{sup 4+} and Xe{sup 5+} ions. The present results are found to agree well with the experimental data.

Mohammedein, Adel M.; Ghoneim, Adel A.; Kandil, Kandil M.; Kadad, Ibrahim M. [Applied Sciences Department, College of Technological Studies, P.O. Box 42325, Shuwaikh 70654 (Kuwait)

2010-01-05

24

Accurate Xe Isotope Measurement Using JPL Ion Trap.  

PubMed

We report an approach for the reproducible and accurate compositional analysis of different mixtures of Xe isotopes using miniature Jet Propulsion Laboratory Quadrupole Ion Trap (JPL-QIT). A major study objective was to validate the recent instrumental improvements to the long-term operational stability under different pressures, temperatures, and trapping conditions. We propose that the present device can be used in certification of trace amounts of isotopes in mixtures dominated by one or more isotopes. Measured isotopic compositions are verified against commercially available standards with accuracy better than 0.07%. To aid the analysis of experimental data, we developed a scalable replica fitting method and use peak areas as descriptors of relative isotopic abundances. This low-power and low-mass device is ideally suited for planetary explorations aimed to enhance quantitative analysis for major isotopes present in small amounts of atmospheric samples. PMID:25216693

Madzunkov, Stojan M; Nikoli?, Dragan

2014-11-01

25

Large-angle xenon ion scattering in Xe-propelled electrostatic thrusters: differential cross sections  

NASA Astrophysics Data System (ADS)

Elastic scattering between xenon ions and xenon atoms can produce ion currents at large angles with respect to the axis of electrostatic thrusters. Differential scattering cross sections are needed to properly predict off-axis currents that can cause significant material erosion due to sputtering. Guided-ion beam differential cross section measurements are presented for Xe+ + Xe and Xe2+ + Xe elastic scattering at laboratory ion energies between 5 and 40 eV per ion charge. For the singly charged system, the experimental absolute differential cross sections are in excellent agreement with classical elastic scattering calculations based on the most recent ab initio ion-atom interaction potentials. The measurements for the doubly charged system are used to derive an approximate effective Xe2+-Xe interaction potential. The potentials are used to calculate absolute differential cross sections for both ion charge states at a typical Hall thruster ion energy of 270 eV per unit charge. The differential cross sections for the doubly charged ions are approximately a factor of 3 smaller than those of the singly charged system at large scattering angles. The importance of doubly charged ions with respect to material erosion is discussed on the basis of known sputtering yields as a function of ion energy for molybdenum and boron nitride. It is concluded that at typical charge-state ratios, doubly charged ions only have an impact at elastic scattering angles where the scattered ion energy in the laboratory (thruster) frame of reference is low and the sputtering yields depend very strongly on ion kinetic energy.

Chiu, Y.-H.; Dressler, R. A.; Levandier, D. J.; Houchins, C.; Ng, C. Y.

2008-08-01

26

Modifications in structure and optical property of Cu nanoparticles in SiO2 by post heavy ion irradiation  

NASA Astrophysics Data System (ADS)

The implantation-synthesized Cu nanoparticles (NPs) in silica were irradiated with 500 keV Xe and Ar ions, respectively. After Xe ion irradiation at a fluence of 2 × 1016/cm2, the average diameter of Cu NPs was increased from 7.3 to 8.5 nm, and especially, Cu NPs with a diameter of 11-14 nm were formed beyond the projected range of Cu ions and nearly aligned at the same depth, which presented a higher volume fraction. As a result, the Cu surface plasmon resonance (SPR) absorption peak was enhanced. However, if Xe ion fluence was less than 1 × 1016/cm2, no clear variation of the Cu SPR absorption peak could be found. Further, it was also revealed that Xe ion irradiation caused the Cu SPR absorption peak to more drastically change than Ar ion irradiation at the same ion fluence. The underlying processes for the above findings were discussed and tentatively proposed.

Liu, Changlong; Wang, Nana; Wang, Jun; Liu, Huixian; Jia, Guangyi; Mu, Xiaoyu

2014-05-01

27

TiO2 films photocatalytic activity improvements by swift heavy ions irradiation  

NASA Astrophysics Data System (ADS)

TiO2 thin films synthesized by sol-gel on glass substrates are irradiated by 90 MeV Xe ions at various fluences and room temperature under normal incidence. The structural, electrical, optical and surface topography properties before and after Xe ions irradiation are investigated. X-ray diffraction (XRD) reveals that the crystallinity is gradually destroyed, and the films become amorphous above 5×1012 ions/cm2. The band gap is not affected by Xe ions irradiation as evidenced from the optical measurements. By contrast, the conductivity increases with raising Xe fluence. The energy band diagram established from the electrochemical characterization shows the feasibility of TiO2 films for the photo-electrochemical chromate reduction. Xe ion irradiation results in enhanced photocatalytic activity in aquatic medium, evaluated by the reduction of Cr(VI) into trivalent state. TiO2 films irradiated at 1013 Xe/cm2 exhibit the highest photoactivity; 69% of chromate (10 ppm) is reduced at pH ~3 after 4 h of exposure to sunlight (1120 mW cm-2) with a quantum yield of 0.06%.

Rafik, Hazem; Mahmoud, Izerrouken; Mohamed, Trari; Abdenacer, Benyagoub

2014-08-01

28

Size Control of Carbon Nanofiber Probes Fabricated by Ion Irradiation  

NASA Astrophysics Data System (ADS)

The effect of ion species and fabrication temperature on the size of ion-induced carbon nanofibers (CNFs) grown on tips of scanning probe microscope cantilevers was investigated in detail. Similarly to that using Ar+ ions, the fabrication of CNF probes using Ne+ and Xe+ ions was possible. Xe+ sputtering yielded the shortest CNF probes owing to its large sputtering effect; however, a significant difference in the size of the CNF probes between Ne+ and Ar+ ion irradiation was not observed. The CNFs increased in length with fabrication temperature owing to the enhanced diffusion of C atoms at elevated temperatures; however, the CNF diameter remained almost constant independent of fabrication temperature. Therefore, the fabrication at elevated temperatures was effective for the rapid fabrication of practical CNF probes. Thus, the CNF probe size was controllable by adjusting the fabrication temperature and ion species.

Inaba, Kazuhisa; Sugita, Yoshitaka; Suzuki, Takahito; Tanemura, Masaki; Hayashi, Akari; Hayashi, Yasuhiko; Kitazawa, Masashi; Ohta, Ryo

2010-08-01

29

Ion acceleration in Ar-Xe and Ar-He plasmas. I. Electron energy distribution functions and ion composition  

SciTech Connect

Electron energy distribution functions (eedf), ion production, and ion composition are studied in Ar-Xe and Ar-He expanding helicon plasmas. It was found that under the conditions of constant total flow rate, Xe, in addition to Ar, changes the eedf from Maxwellian-like to Druyvesteyn-like with a shortening of the high energy tail at {approx}15 eV. The electron temperature exponentially decreases from {approx}7 eV in pure Ar plasma to {approx}4 eV in pure Xe plasma. Xenon ions dominate the ion population for Xe filling fractions greater than 10%. The plasma density increases by {approx}15% with increasing Xe fraction. For an Ar-He plasma, increasing the helium fraction increases the electron temperature from {approx}7 eV in pure Ar plasma to {approx}14 eV for a He filling fraction of 80%. The plasma density drops by more than three orders of magnitude from 1.14x10{sup 11} cm{sup -3} to 6.5x10{sup 7} cm{sup -3}. However, the inferred ion densities indicate that even at a helium fraction of 80%, argon ions significantly outnumber helium ions.

Biloiu, Ioana A.; Scime, Earl E. [Department of Physics, West Virginia University, Morganton, West Virginia 26506 (United States)

2010-11-15

30

Anisotropic proton-conducting membranes prepared from swift heavy ion-beam irradiated ETFE films  

Microsoft Academic Search

Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams of 129Xe23+ with fluences of 0, 3×106, 3×107, 3×108 and 3×109ions\\/cm2, followed by ?-ray pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent

Yosuke Kimura; Jinhua Chen; Masaharu Asano; Yasunari Maekawa; Ryoichi Katakai; Masaru Yoshida

2007-01-01

31

Measurement of a magnetic-dipole transition probability in Xe32+ using an electron-beam ion trap  

E-print Network

The transition probability for the 3d(4) D-5(2) <-- D-5(3) magnetic-dipole transition in Ti-like Xe (Xe32+) has been measured using an electron-beam ion trap. The unusually weak dependence of the transition energy on nuclear charge Z, and the fact...

Serpa, F. G.; Morgan, C. A.; Meyer, E. S.; Gillaspy, J. D.; Trabert, E.; Church, David A.; Takacs, E.

1997-01-01

32

Generation of strongly coupled Xe cluster nanoplasmas by low intensive soft x-ray laser irradiation  

NASA Astrophysics Data System (ADS)

A seeding gas jet including Xe clusters was irradiated with a laser-driven plasma soft x-ray laser pulse (?=13.9 nm, ~7 ps, <=5×109 W/cm2), where the laser photon energy is high enough to ionize 4d core electrons. In order to clarify how the innershell ionization followed by the Auger electron emission is affected under the intense laser irradiation, the electron energy distribution was measured. Photoelectron spectra showed that the peak position attributed to 4d hole shifted to lower energy and the spectral width was broadened with increasing cluster size. Moreover, the energy distribution exhibited that a strongly coupled cluster nanoplasma with several eV was generated.

Namba, S.; Hasegawa, N.; Kishimoto, M.; Nishikino, M.; Kawachi, T.

2012-07-01

33

Ion energy distributions, electron temperatures, and electron densities in Ar, Kr, and Xe pulsed discharges  

SciTech Connect

Ion energy distributions (IEDs) were measured near the edge of Faraday-shielded, inductively coupled pulsed plasmas in Ar, Kr, or Xe gas, while applying a synchronous dc bias on a boundary electrode, late in the afterglow. The magnitudes of the full width at half maximum of the IEDs were Xe > Kr > Ar, following the order of the corresponding electron temperatures in the afterglow, T{sub e}(Xe) > T{sub e}(Kr) > T{sub e}(Ar). The measured decays of T{sub e} with time in the afterglow were in excellent agreement with predictions from a global model. Measured time-resolved electron and positive ion densities near the plasma edge did not decay appreciably, even in the 80 {mu}s long afterglow. This was attributed to transport of ions and electrons from the higher density central region of the plasma to the edge region, balancing the loss of plasma due to diffusion. This provides a convenient means of maintaining a relatively constant plasma density in the afterglow during processing using pulsed plasmas.

Shin, Hyungjoo; Zhu Weiye; Economou, Demetre J.; Donnelly, Vincent M. [Plasma Processing Laboratory, Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204-4004 (United States)

2012-05-15

34

Energy Levels and Observed Spectral Lines of Xenon, Xe I through Xe LIV  

NASA Astrophysics Data System (ADS)

The energy levels and observed spectral lines of the xenon atom, in all stages of ionization for which experimental data are available, have been compiled. Sufficient data were found to generate level and line tables for Xe I-Xe XI, Xe XIX, Xe XXV-Xe XXIX, Xe XLIII-Xe XLV, and Xe LI-Xe LIV. For Xe LIII and Xe LIV theoretical values are compiled for the energy levels. In 15 of the other stages a few lines are reported. Experimental g factors are included for Xe I, Xe II, and Xe III. A value, either experimental, semiempirical, or theoretical, is included for the ionization energy of each ion.

Saloman, E. B.

2004-09-01

35

Valence-shell photoionization of Ag-like Xe$^{7+}$ ions : experiment and theory  

E-print Network

We report on experimental and theoretical results for the photoionization of Ag-like xenon ions, Xe$^{7+}$, in the photon energy range 95 to 145~eV. The measurements were carried out at the Advanced Light Source at an energy resolution of $\\Delta$E = 65 meV with additional measurements made at $\\Delta$E = 28 meV and 39 meV. Small resonance features below the ground-state ionization threshold, at about 106 eV, are due to the presence of metastable Xe$^{7+} (4d^{10} 4f~^2{\\rm F}^{\\circ}_{5/2,7/2})$ ions in the ion beam. On the basis of the accompanying theoretical calculations using the Dirac Atomic R-matrix Codes (DARC), an admixture of only a few percent of metastable ions in the parent ion beam is inferred, with almost 100\\% of the parent ions in the $(4d^{10}5s ~^2{\\rm S_{1/2}})$ ground level. The cross-section is dominated by a very strong resonance associated with $4d \\rightarrow 5f$ excitation and subsequent autoionization. This prominent feature in the measured spectrum is the $4d^95s5f ~^2{\\rm P}^{\\cir...

Mueller, A; Esteves-Macaluso, D; Habibi, M; Aguilar, A; Kilcoyn, A L D; Phaneuf, R A; Ballance, C P; McLaughlin, B M

2014-01-01

36

New process observed in collisions between highly charged protonated protein and Xe8+ Xe5+ He2+ ions  

NASA Astrophysics Data System (ADS)

Electron multicapture processes have been studied in collisions between cytochrome C protein and highly charged Xe and He projectile at keV kinetic energy range. In competition with single and double electron capture, a new and unexpected channel attributed to deprotonation process of the protein has been observed.

Martin, S.; Chen, L.; Brédy, R.; Vernier, A.; Dugourd, P.; Antoine, R.; Ortéga, C.; Ji, M.; Bernard, J.; Gonzalez Maganad, O.; Reitsma, G.; Schlathölter, T.

2014-04-01

37

An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe.  

PubMed

We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope (136)Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight mass spectroscopy for positive identification of the barium decay product. PMID:25273779

Twelker, K; Kravitz, S; Montero Díez, M; Gratta, G; Fairbank, W; Albert, J B; Auty, D J; Barbeau, P S; Beck, D; Benitez-Medina, C; Breidenbach, M; Brunner, T; Cao, G F; Chambers, C; Cleveland, B; Coon, M; Craycraft, A; Daniels, T; Daugherty, S J; Davis, C G; DeVoe, R; Delaquis, S; Didberidze, T; Dilling, J; Dolinski, M J; Dunford, M; Fabris, L; Farine, J; Feldmeier, W; Fierlinger, P; Fudenberg, D; Giroux, G; Gornea, R; Graham, K; Hall, C; Heffner, M; Herrin, S; Hughes, M; Jiang, X S; Johnson, T N; Johnston, S; Karelin, A; Kaufman, L J; Killick, R; Koffas, T; Krücken, R; Kuchenkov, A; Kumar, K S; Leonard, D S; Leonard, F; Licciardi, C; Lin, Y H; MacLellan, R; Marino, M G; Mong, B; Moore, D; Odian, A; Ostrovskiy, I; Ouellet, C; Piepke, A; Pocar, A; Retiere, F; Rowson, P C; Rozo, M P; Schubert, A; Sinclair, D; Smith, E; Stekhanov, V; Tarka, M; Tolba, T; Tosi, D; Vuilleumier, J-L; Walton, J; Walton, T; Weber, M; Wen, L J; Wichoski, U; Yang, L; Yen, Y-R; Zhao, Y B

2014-09-01

38

An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe  

E-print Network

We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope $^{136}$Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight (TOF) mass spectroscopy for positive identification of the barium decay product.

Twelker, K; Díez, M Montero; Gratta, G; Fairbank, W; Albert, J B; Auty, D J; Barbeau, P S; Beck, D; Benitez-Medina, C; Breidenbach, M; Brunner, T; Cao, G F; Chambers, C; Cleveland, B; Coon, M; Craycraft, A; Daniels, T; Daugherty, S J; Davis, C G; DeVoe, R; Delaquis, S; Didberidze, T; Dilling, J; Dolinski, M J; Dunford, M; Fabris, L; Farine, J; Feldmeier, W; Fierlinger, P; Fudenberg, D; Giroux, G; Gornea, R; Graham, K; Hall, C; Heffner, M; Herrin, S; Hughes, M; Jiang, X S; Johnson, T N; Johnston, S; Karelin, A; Kaufman, L J; Killick, R; Koffas, T; Krücken, R; Kuchenkov, A; Kumar, K S; Leonard, D S; Leonard, F; Licciardi, C; Lin, Y H; MacLellan, R; Marino, M G; Mong, B; Moore, D; Odian, A; Ostrovskiy, I; Ouellet, C; Piepke, A; Pocar, A; Retiere, F; Rowson, P C; Rozo, M P; Schubert, A; Sinclair, D; Smith, E; Stekhanov, V; Tarka, M; Tolba, T; Tosi, D; Vuilleumier, J -L; Walton, J; Walton, T; Weber, M; Wen, L J; Wichoski, U; Yang, L; Yen, Y -R; Zhao, Y B

2014-01-01

39

An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe  

NASA Astrophysics Data System (ADS)

We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope 136Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight mass spectroscopy for positive identification of the barium decay product.

Twelker, K.; Kravitz, S.; Díez, M. Montero; Gratta, G.; Fairbank, W.; Albert, J. B.; Auty, D. J.; Barbeau, P. S.; Beck, D.; Benitez-Medina, C.; Breidenbach, M.; Brunner, T.; Cao, G. F.; Chambers, C.; Cleveland, B.; Coon, M.; Craycraft, A.; Daniels, T.; Daugherty, S. J.; Davis, C. G.; DeVoe, R.; Delaquis, S.; Didberidze, T.; Dilling, J.; Dolinski, M. J.; Dunford, M.; Fabris, L.; Farine, J.; Feldmeier, W.; Fierlinger, P.; Fudenberg, D.; Giroux, G.; Gornea, R.; Graham, K.; Hall, C.; Heffner, M.; Herrin, S.; Hughes, M.; Jiang, X. S.; Johnson, T. N.; Johnston, S.; Karelin, A.; Kaufman, L. J.; Killick, R.; Koffas, T.; Krücken, R.; Kuchenkov, A.; Kumar, K. S.; Leonard, D. S.; Leonard, F.; Licciardi, C.; Lin, Y. H.; MacLellan, R.; Marino, M. G.; Mong, B.; Moore, D.; Odian, A.; Ostrovskiy, I.; Ouellet, C.; Piepke, A.; Pocar, A.; Retiere, F.; Rowson, P. C.; Rozo, M. P.; Schubert, A.; Sinclair, D.; Smith, E.; Stekhanov, V.; Tarka, M.; Tolba, T.; Tosi, D.; Vuilleumier, J.-L.; Walton, J.; Walton, T.; Weber, M.; Wen, L. J.; Wichoski, U.; Yang, L.; Yen, Y.-R.; Zhao, Y. B.

2014-09-01

40

Valence-shell photoionization of Ag-like Xe7+ ions: experiment and theory  

NASA Astrophysics Data System (ADS)

We report on experimental and theoretical results for the photoionization of Ag-like xenon ions, Xe7+, in the photon energy range 95–145 eV. The measurements were carried out at the Advanced Light Source at an energy resolution of ?E = 65 meV with additional measurements made at ?E = 28 meV and 39 meV. Small resonance features below the ground-state ionization threshold, at about 106 eV, are due to the presence of metastable Xe7+(4{{d}10}4f{{ }2}f5/2,7/2{^\\circ }) ions in the ion beam. On the basis of the accompanying theoretical calculations using the Dirac atomic R-matrix codes (DARC), an admixture of only a few percent of metastable ions in the parent ion beam is inferred, with almost 100% of the parent ions in the (4{{d}10}5s{{ }2}{{s}1/2}) ground level. The cross section is dominated by a very strong resonance associated with 4d\\to 5f excitation and subsequent autoionization. This prominent feature in the measured spectrum is the 4{{d}9}5s5{{f} 2}{{P}{^\\circ }} resonance located at (122.139 ± 0.01) eV. An absolute peak cross section of 1.2 Gigabarns was measured at 38 meV energy resolution. The experimental natural width ? = 76 ± 3 meV of this resonance compares well with the theoretical estimate of 88 meV obtained from the DARC calculation with 249 target states. Given the complexity of the system, overall satisfactory agreement between theory and experiment is obtained for the photon energy region investigated.

Müller, A.; Schippers, S.; Esteves-Macaluso, D.; Habibi, M.; Aguilar, A.; Kilcoyne, A. L. D.; Phaneuf, R. A.; Ballance, C. P.; McLaughlin, B. M.

2014-11-01

41

Relativistic Many-body Moller-Plesset Perturbation Theory Calculations of the Energy Levels and Transition Probabilities in Na- to P-like Xe Ions  

SciTech Connect

Relativistic multireference many-body perturbation theory calculations have been performed on Xe{sup 43+}-Xe{sup 39+} ions, resulting in energy levels, electric dipole transition probabilities, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, frequency-dependent Breit correction and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.

Vilkas, M J; Ishikawa, Y; Trabert, E

2007-03-27

42

Fullerene ion irradiation to silicon  

NASA Astrophysics Data System (ADS)

Silicon has been irradiated by singly charged C 60 fullerene ions with an ion dose of up to 1 × 10 13 ions/cm 2 at room temperature in order to study the damage formation of cluster ion bombardment on solid surfaces. Singly and doubly charged fullerene ions and some daughter ions of fullerene were observed. Mass separation was accomplished by a 90° sector magnet. The maximum current of the mass-separated singly charged C 60 fullerene ion beam was about 10 nA. RBS (Rutherford backscattering spectrometry) channeling measurement of the Si(100) bombarded by 300 keV C 60 ions (i.e. 5.0 keV per carbon atom) shows a remarkable increase in the surface peak of the defects even at the low atomic dose of 6 × 10 14 atoms/cm 2. The C 60 fullerene ion beam irradiation produced many defects. This is one of the typical non-linear effects of cluster bombardment.

Tanomura, M.; Takeuchi, D.; Matsuo, J.; Takaoka, G. H.; Yamada, I.

1997-01-01

43

Multifragmentation in intermediate energy {sup 129}Xe-induced heavy-ion reactions  

SciTech Connect

The {sup 129}Xe-induced reactions on {sup nat}Cu, {sup 89}Y, {sup 165}Ho, and {sup 197}Au at bombarding energies of E/A = 40 & 60 MeV have been studied theoretically and experimentally in order to establish the underlying mechanism of multifragmentation at intermediate energy heavy-Ion collisions. Nuclear disks formed in central heavy-ion collisions, as simulated by means of Boltzmann-like kinetic equations, break up into several fragments due to a new kind of Rayleigh-like surface instability. A sheet of liquid, stable in the limit of non-interacting surfaces, is shown to become unstable due to surface-surface interactions. The onset of this instability is determined analytically. A thin bubble behaves like a sheet and is susceptible to the surface instability through the crispation mode. The Coulomb effects associated with the depletion of charges in the central cavity of nuclear bubbles are investigated. The onset of Coulomb instability is demonstrated for perturbations of the radial mode. Experimental intermediate-mass-fragment multiplicity distributions for the {sup 129}Xe-induced reactions are shown to be binomial at each transverse energy. From these distributions, independent of the specific target, an elementary binary decay probability p can be extracted that has a thermal dependence. Thus it is inferred that multifragmentation is reducible to a combination of nearly independent emission processes. If sequential decay is assumed, the increase of p with transverse energy implies a contraction of the emission time scale. The sensitivity of p to the lower Z threshold in the definition of intermediate-mass-fragments points to a physical Poisson simulations of the particle multiplicities show that the weak auto-correlation between the fragment multiplicity and the transverse energy does not distort a Poisson distribution into a binomial distribution. The effect of device efficiency on the experimental results has also been studied.

Tso, Kin

1996-05-01

44

Study on ion-irradiation-induced ferromagnetism in FeRh intermetallic compound by means of magnetic Compton scattering  

SciTech Connect

The magnetic Compton profiles of Fe-50 at. % Rh intermetallic compound were measured to study the ferromagnetism induced by 200 MeV Xe ion irradiation. The magnetic effect at 50 K increases with increasing the ion-fluence. The analysis of the experimental result revealed that the values of spin moment induced by the irradiation were close to the values of magnetization obtained by a superconducting quantum interference device magnetometer, suggesting that the ion irradiation mainly induces the spin magnetic moment. The difference in magnetic Compton profiles between the irradiation-induced ferromagnetism and the intrinsic ferromagnetism in pure Fe is also discussed.

Kosugi, S.; Matsui, T.; Aikoh, K.; Shimizu, K.; Tahara, Y.; Hori, F.; Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Ishikawa, N. [Japan Atomic Energy Agency(JAEA-Tokai), Tokai, Ibaraki, 319-1195 (Japan); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute(JASRI), Spring-8, Sayo, Hyogo 679-5198 (Japan)

2011-04-01

45

Production of highly charged ion beams Kr32+, Xe44+, Au54+ with Electron String Ion Source (ESIS) Krion-2 and corresponding basic and applied studies  

NASA Astrophysics Data System (ADS)

Electron String Ion Source (ESIS) Krion-2 (JINR, Dubna) was used for basic and applied research in various aspects of multiply charged heavy ions production. Energy recuperation mode in ESIS has been proofed first and used for production of highly charged ions 84Kr28+÷84Kr32+, 124Xe40÷124Xe44 and Au51+÷ Au54+. Krion-2 ESIS was mounted on high voltage (HV) platform of LU-20 Linac and used as an injector of highly charged ions during Nuclotron run N° 41. Krion-2 ESIS has produced 3.0.107 124Xe42+ ions per pulse of 7 ?s duration. This ion beam was injected into LU-20 and Nuclotron, accelerated up to energy of 186 GeV and the extracted Xe beam was used for physics experiments. Electron String Ion Source Krion-2 demonstrated the high reliability and stability running during 30 days on HV platform. We believe that it is due to an extremely low electron beam power, provided by using the electron string mode of operation: 50 W pulse power and about 10 W average power. Other possible application of ESIS could be its use in injection complexes of synchrotrons and cyclotrons for cancer therapy. Slow and fast extraction of C4+ and C6+ beams from Krion-2 ESIS were preliminary studied towards ESIS optimization for medical accelerators requirements.

Donets, D. E.; Donets, E. D.; Donets, E. E.; Salnikov, V. V.; Shutov, V. B.

2010-09-01

46

Thermal processes in multilayer second-generation HTSC under swift heavy-ion irradiation  

NASA Astrophysics Data System (ADS)

On the basis of the thermal spike model, the estimations with regard to tapes of the second-generation Ag/YBaCuO/MgO/Hastelloy HTSC under irradiation with Ar, Kr, and Xe ions of an energy of about 1.2 MeV/amu have been carried out. The results have been compared with the available experimental data. In addition, the possibility of processes such as melting, recrystallization, amorphization, and other phase transitions in multilayer structures under ion irradiation has been studied.

Didyk, A. Yu.; Semina, V. K.; Hofman, A.; Mikhailova, G. N.; Troitskij, A. V.; Antonova, L. Kh.

2013-09-01

47

Anodic and air oxidation of niobium studied by ion beam analysis with implanted Xe marker  

Microsoft Academic Search

Xe marker implantation and backscattering analysis were used to study the growth mechanism of anodic oxides on niobium. In 5 wt% aqueous ammonium citrate solution, analysis of the Xe marker movement demonstrated that the oxide was formed mainly within the existing oxide through the transport of both niobium cations and oxygen anions from each side when the anodic oxidation was

X. D. Bai; D. H. Zhu; B. X. Liu

1996-01-01

48

Improved field emission of electrons from ion irradiated carbon  

SciTech Connect

Electron field emission from allotropes of carbon (graphite, diamondlike carbon, and diamond) have been reported many times in the literature. This work explores the use of ion irradiation for improving electron field emission from carbon fibers. Carbon fibers have been irradiated with H, C, Ar, and Xe ions. Field emission characteristics have been measured as a function of ion dose. A reversible reduction in the required field for a fixed current level has been observed. The critical dose, D{sub c}, defines the dose corresponding to the lowest field necessary to emit a fixed current (5 {mu}A). The critical dose appears to correlate with the nuclear energy loss (collisions with atoms) of the ion in the carbon fiber. Transmission electron microscopy and parallel electron energy loss spectroscopy analysis indicate an amorphous surface, and an increase in the sp{sup 3} content of the fiber surface to 20{percent}{endash}30{percent}. A corresponding decrease in the work function is expected and may account for the improvement in electron emission. {copyright} {ital 1997 American Institute of Physics.}

Walter, K.C.; Kung, H.H.; Maggiore, C.J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1997-09-01

49

Microstructural modifications in swift ion irradiated PET  

NASA Astrophysics Data System (ADS)

Polyethylene terephthalte (PET) was irradiated with carbon (70 MeV) and copper (120 MeV) ions to analyze the induced modifications with respect to optical, structural and thermal properties. In the present investigation, the fluence for carbon irradiation was varied from 1×10 11 to 1×10 14 ions cm -2, while that for copper beam was kept in the range of 1×10 11 to 1×10 13 ions cm -2. UV-vis, FTIR, XRD and DSC techniques were utilized to study the induced changes. The analysis of UV-vis absorption studies reveals that there is decrease of optical energy gap up to 10% on carbon ion irradiation (at 1×10 14 ions cm -2), whereas the copper beam (at 1×10 13 ions cm -2) leads to a decrease of 49%. FTIR analysis indicated the formation of alkyne end groups along with the overall degradation of polymer with copper ion irradiation. X-ray diffraction analysis revealed that the semi-crystalline PET losses its crystallinity on swift ion irradiation. It was found that the carbon beam (1×10 14 ions cm -2) decreased the crystallite size by 16% whereas this decrease is of 12% in case of the copper ion irradiated PET at 1×10 13 ions cm -2. The loss in crystallinity on irradiation has been supported by DSC thermograms.

Singh, Ravinder; Singh Samra, Kawaljeet; Kumar, Ramneek; Singh, Lakhwant

2008-05-01

50

The energy loss effects on the absorption edge of LiTaO3 irradiated by energetic heavy ions  

NASA Astrophysics Data System (ADS)

The z-cut LiTaO3 single crystals were irradiated by 6 MeV Xe-ion at the fluences in the range from 1.0 × 1012 to 1.0 × 1015 ions/cm2, or 30, 375, 1980 MeV Kr ions at the fluences in the range from 1.0 × 1011 to 1.0 × 1013 ions/cm2. The irradiated samples were analyzed by optical spectrometer and Rutherford backscattering-channeling spectroscopy. It was found that the UV absorption edge of LiTaO3 shifts toward to longer wavelength (red-shift) as a result of heavy-ion irradiation. In 6 MeV Xe-ion irradiated samples, the red-shifts are weak even at a high fluence of 1.0 × 1015 ions/cm2 when the irradiated layer becomes amorphous. However, in 30, 375, 1980 MeV Kr-ion irradiated samples, significant red-shifts were observed even at low fluences. The effects of nuclear energy loss and electronic energy loss on the red-shift of absorption edge in LiTaO3 are discussed.

Pang, L. L.; Wang, Z. G.; Sun, J. R.; Yao, C. F.; Wei, K. F.; Shen, T. L.; Cui, M. H.; Zhu, Y. B.; Sheng, Y. B.; Li, Y. F.; Chang, H. L.; Wang, J.; Zhu, H. P.

2013-07-01

51

TEM, XRD and nanoindentation characterization of Xenon ion irradiation damage in austenitic stainless steels  

NASA Astrophysics Data System (ADS)

Cross-sectional and bulk specimens of a 20% cold-worked 316 austenitic stainless steel (CW 316 SS) has been characterized by TEM, XRD and nanoindentation to determine the microstructural evolution and mechanical property changes of 316 SS after irradiation with 7 MeV Xe26+ ions. TEM results reveal the presence of dislocation loops with a number density of approximately 3 × 1022 m-3 and sizes between 3 to 10 nm due to the collapse of vacancy rich cores inside displacement cascades. Peak broadening observed in XRD diffraction patters reveal systematic changes to lattice parameters due to irradiation. The calculated indentation values in irradiated 316 SS were found to be much higher in comparison to the unirradiated specimen, indicating the dose dependent effect of irradiation on hardness. The relationship between irradiation induced microstructural evolution and the changes to the mechanical properties of CW 316 SS are discussed in the context of fluence and irradiation temperature.

Huang, H. F.; Li, J. J.; Li, D. H.; Liu, R. D.; Lei, G. H.; Huang, Q.; Yan, L.

2014-11-01

52

Absolute cross sections for photoionization of Xe$^{q+}$ ions (1 $\\le$ q $\\le$ 5) at the 3d ionization threshold  

E-print Network

The photon-ion merged-beams technique has been employed at the new Photon-Ion spectrometer at PETRA III (PIPE) for measuring multiple photoionization of Xe$^{q+}$ (q=1-5) ions. Total ionization cross sections have been obtained on an absolute scale for the dominant ionization reactions of the type h\

Schippers, S; Buhr, T; Borovik, A; Hellhund, J; Holste, K; Huber, K; Schäfer, H -J; Schury, D; Klumpp, S; Mertens, K; Martins, M; Flesch, R; Ulrich, G; Rühl, E; Jahnke, T; Lower, J; Metz, D; Schmidt, L P H; Schöffler, M; Williams, J B; Glaser, L; Scholz, F; Seltmann, J; Viefhaus, J; Dorn, A; Wolf, A; Ullrich, J; Müller, A

2014-01-01

53

Dissolution of Olivine Promoted by Ion Irradiation  

NASA Astrophysics Data System (ADS)

Recent laboratory simulations of ion irradiation effects on planetary minerals show changes in the surface composition of surfaces that are different depending on whether the analysis is done in-situ (without removing the sample from vacuum) or ex-situ using an electron microscope. We found that olivine samples that have been irradiated by keV ions show preferential loss of magnesium when exposed to water. Irradiations were done with 4 keV argon ions to fluences between 1015 and 1018 ions/cm2. Soak times in high purity water ranged from minutes to days, and exhibit the same degree of Mg depletion, independent of soak time. The concentration of magnesium on the surface of irradiated natural olivine decreases by 40% upon contact with water, as measured with x-ray photoelectron spectroscopy. This finding is important for laboratory simulations of regolith processes and for establishing procedures for the handling of irradiated samples, including those from sample return missions.

Cantando, E. D.; Dukes, C. A.; Baragiola, R. A.

2006-12-01

54

Ion irradiation-induced diffusion in bixbyite-fluorite related oxides: Dislocations and phase transformation  

NASA Astrophysics Data System (ADS)

Ion-irradiation induced diffusion and the phase transformation of a bixbyite-fluorite related rare earth oxide thin films are studied. This work is focused on yttrium sesquioxide, Y2O3, thin films deposited on Si (1 0 0) substrates using the ion beam sputtering technique (IBS). As-deposited samples were annealed ant then irradiated at cryogenic temperature (80 K) with 260 keV Xe2+ at different fluences. The irradiated thin oxide films are characterized by X-ray diffraction. A cubic to monoclinic phase transformation was observed. Analysis of this phenomenon is done in terms of residual stresses. Stress measurements as a function of irradiation fluences were realised using the XRD-sin2? method. Stress evolution and kinetic of the phase transformation are compared and leads to the role-played by the nucleation of point and extended defects.

Rolly, Gaboriaud; Fabien, Paumier; Bertrand, Lacroix

2014-05-01

55

Anisotropic proton-conducting membranes prepared from swift heavy ion-beam irradiated ETFE films  

NASA Astrophysics Data System (ADS)

Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams of 129Xe 23+ with fluences of 0, 3 × 10 6, 3 × 10 7, 3 × 10 8 and 3 × 10 9 ions/cm 2, followed by ?-ray pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent were examined to determine their effect on the proton conductivity of the resultant membranes. It was found that the polymer electrolyte membrane prepared by grafting the styrene monomer in a mixture of 67% isopropanol and 33% water to the ETFE film with an ion-beam irradiation fluence of 3.0 × 10 6 ions/cm 2 was a highly anisotropic proton-conducting material, as the proton conductivity was three or more times higher in the thickness direction than in the surface direction of the membrane.

Kimura, Yosuke; Chen, Jinhua; Asano, Masaharu; Maekawa, Yasunari; Katakai, Ryoichi; Yoshida, Masaru

2007-10-01

56

Dissociation of CO molecular ions produced in collisions with 2.5 MeV/u Xe(34+)  

NASA Astrophysics Data System (ADS)

The breakup of CO molecular ions following multiple electron removal by 2.5 MeV/u Xe(34+) ions has been re-examined by means of recoil-ion momentum spectroscopy (RIMS) using a position- sensitive 80 mm diam microchannel plate detector backed by a hexagonal delay-line anode. Fragment pairs originating from molecular ions with charge up to 8e were isolated and analyzed in order to determine the distribution of total recoil-ion kinetic energy released in the breakup (KER) and the angular distribution of the ion momenta with respect to the beam direction. The results are significantly improved compared to those reported previously in terms of accuracy, resolution and overall counting statistics. The KER distributions were determined with a resolution of 1 eV (FWHM) or better. While most of the KER distributions displayed only a single broad asymmetric peak, a few of them showed a combination of well- resolved narrow peaks and partially overlapping broader peaks. The angular distributions were found to be essentially isotropic, except for those ion pairs originating from highly charged molecular ions, which indicated a slight preference for emission in the beam direction.

Horvat, Vladimir; Watson, Rand

2010-03-01

57

A new method of chlorophenols decomposition based on UV-irradiation by XeBr-excilamp and their subsequent biodegradation  

NASA Astrophysics Data System (ADS)

The combined decomposition method of chlorophenols (CP) is offered. The method is based on photolysis of CP through XeBr-excilamp UV irradiation at 283 nm in a flow photoreactor with subsequent treatment of photolysis products by microorganism-destructor B. cereus isolated from an aeration pond of Baikal pulp-and-paper mill. At initial concentration of CP of 20 mg/l the polluted solutions can be utilized directly by means of biological treatment using B. cereus under aerobic conditions. However, if the initial CP concentration is higher than 20 mg/l, the polluted solutions are low biodegradable. It is shown, that the combined treatment is most effective method in this case. At initial CP concentration of 50 mg/l and higher it is suggested to use the deep preliminary UV-treatment with the purpose of removal 80-90 % of initial CP. It is revealed, that 4-CP is relatively persistent compound for B. cereus, easily decomposed by UV-radiation of XeBr-excilamp. As a result of subsequent biological treatment during 10 days the utilization of basic CP photoproducts is obtained. Experimentally, the preliminary UV-processing time was essentially less than that found earlier by E. Tamer, Z. Hamid, Aly A. (Chemosphere, 2006), where the half-life periods of initial CP were from 2.2 to 54 hours at the same value of initial concentration of CP. Correspondingly, the total CP decomposition process was accompanied by high power inputs. It is suggested to use mentioned above method for effective CP decomposition at high concentration values.

Sosnin, E. A.; Matafonova, G. G.; Batoev, V. B.; Christofi, N.

2008-01-01

58

Effects of ion irradiation in metallic glasses  

Microsoft Academic Search

Application of metallic glasses as structural materials has been limited by their poor ductility. To overcome brittle failure, nanocrystals are intentionally introduced to stabilize the glasses. In this study, we report on the application of ion irradiation to induce nanocrystalization in a Cu50Zr45Ti5 (CZT) alloy. Transmission electron microcopy, microindentation and nanoindentation have been used to characterize the CZT alloy irradiated

Jesse Carter; E. G. Fu; G. Bassiri; B. M. Dvorak; N. David Theodore; Guoqiang Xie; D. A. Lucca; Michael Martin; Mark Hollander; Xinghang Zhang; Lin Shao

2009-01-01

59

Dependence of cross sections for multi-electron loss by 6 mev/amu xe18+ ions on target atomic number  

E-print Network

for multi-electron loss on target atomic number by using 6 MeV/amu Xe18+ ions and to compare the results with the n-body Classical Trajectory Monte Carlo calculations. A secondary objective of this project is to determine the extent to which the cross...

Peng, Yong

2004-09-30

60

Unexpected transverse velocity component of Xe{sup +} ions near the exit plane of a Hall thruster  

SciTech Connect

The velocity component of singly charged xenon ions in a plane perpendicular to the thrust axis of the 1 kW-class PPS100-ML Hall effect thruster is deduced from laser induced fluorescence measurements on the 5d {sup 2}F{sub 7/2}{yields}6p {sup 2}D{sub 5/2}{sup 0} electronic transition at 834.72 nm. Measurements are carried out at several locations in the near field of the channel exhaust. Thruster operating parameters, such as magnetic field strength, discharge voltage, and xenon mass flow rate, are varied over a wide range. The initial aim of this work was to measure the azimuthal velocity of the ions due to their weak magnetic deflection. Surprisingly, experimental results cannot be explained by the one and only Lorentz force acting on Xe{sup +} ions. A realistic picture of the ion trajectory in the ExB drift plane is obtained when adding a velocity component directed toward the external cathode.

Bourgeois, G.; Mazouffre, S. [ICARE, CNRS, 1C Avenue de la Recherche Scientifique, 45071 Orleans (France); Sadeghi, N. [LSP, Joseph Fourier University and CNRS, 140 Ave. de la Physique, 38402 St. Martin d'Heres (France)

2010-11-15

61

I-Xe systematics in LL chondrites  

NASA Technical Reports Server (NTRS)

A stepwise heating analysis of Ar and Xe data from five neutron-irradiated whole rock LL chondrites (Soko Banja, Alta Ameen, Tuxtuac, Guidder, and Olivenza) is presented, emphasizing the complicated thermal history of ordinary chondrites. None of the present meteorites show a well-defined (Ar-40)-(Ar-39) apparent age plateau comprised of more than two release fractions. Most of the samples are found to yield well-defined high-temperature correlations between Xe-129/Xe-130 and Xe-128/Xe-130, and thus determinations of I-129/I-127 and Xe-129/Xe-130 at the time of isotopic closure for Xe. As in the case of other ordinary chondrites, the I-Xe systematics for LL chondrites correlate neither with a metamorphic grade nor with chronologies based opon other methods.

Bernatowicz, T. J.; Podosek, F. A.; Swindle, T. D.; Honda, M.

1988-01-01

62

Searching for the Mass of the Neutrino (Spectroscopy of Ba+ ions in Liquid ^136Xe)  

NASA Astrophysics Data System (ADS)

The goal of the Enriched Xenon Observatory (EXO) collaboration is to detect neutrino-less double beta decay using a ton size liquid ^136Xenon detector with zero background. Such detection can only be achieved if the daughter ^136Ba^+ ion that is present at decay site is tagged. The EXO collaboration is working towards several techniques to tag the Ba^+ ion. In-situ laser tagging of Ba^+ ions in a liquid xenon test apparatus is being developed at Colorado State University (CSU). Ba^+ ions are implanted in the liquid xenon by ablating a barium sample with a 1064nm Nd-YAG pulsed laser. In-situ laser tagging can only be accomplished if the spectroscopy of Ba^+ ions in liquid xenon is understood. This work's goal is to confirm the spectra of Ba+ ions in liquid xenon. The most recent results of the experiments at CSU will be presented.

Hall, Kendy; Benitez, Cesar; Fairbank, Bill

2009-10-01

63

Chromosomal instability induced by heavy ion irradiation  

NASA Technical Reports Server (NTRS)

PURPOSE: To establish the dose-response relationship for the induction of chromosomal instability in GM10115 cells exposed to high-energy iron ions (1 GeV/nucleon, mean LET 146 keV/microm) and gold ions (11 GeV/nucleon, mean LET 1450 keV/microm). Past work has established that sparsely ionizing X-rays can induce a long-lived destabilization of chromosomes in a dose-dependent manner at an incidence of approximately 3% per gray. The present investigation assesses the capacity of High-Z and High-energy (HZE) particles to elicit this same endpoint. MATERIALS AND METHODS: Clonal populations derived from single progenitor cells surviving heavy-ion irradiation were analyzed cytogenetically to identify those clones showing a persistent destablization of chromosomes. RESULTS: Dose-response data, with a particular emphasis at low dose (< 1.0 Gy), indicate a frequency of approximately 4% per gray for the induction of chromosomal instability in clones derived from single progenitor cells surviving exposure to iron ions. The induction of chromosomal instability by gold ions was, however, less responsive to applied dose, as the observed incidence of this phenotype varied from 0 to 10% over 1-8 Gy. Both iron and gold ions gave dose-dependent increases in the yield of chromosomal aberrations (both chromosome- and chromatid-type) measured at the first mitosis following irradiation, as well as shoulderless survival curves having D0=0.87 and 1.1 Gy respectively. CONCLUSIONS: Based on the present dose-response data, the relative biological effectiveness of iron ions is 1.3 for the induction of chromosomal instability, and this indicates that heavy ions are only slightly more efficient than X-rays at eliciting this delayed phenotype.

Limoli, C. L.; Ponnaiya, B.; Corcoran, J. J.; Giedzinski, E.; Morgan, W. F.

2000-01-01

64

Amorphization and dynamic annealing of hexagonal SiC upon heavy-ion irradiation: Effects on swelling and mechanical properties  

NASA Astrophysics Data System (ADS)

Structural, mechanical, and dimensional evolutions of silicon carbide (SiC) induced by heavy-ion irradiations are studied by means of Rutherford backscattering spectrometry and channeling (RBS/C), nanoindentation, and surface profilometry measurements. 4H- and 6H-SiC single crystals were irradiated with 4 MeV Au2+ and 4 MeV Xe+ ions at room temperature (RT) or 400 °C. Using a Monte Carlo program to simulate the RBS/C spectra (MCCHASY code), we find that Au ion irradiation at RT induces a total silicon sublattice disorder related to full amorphization at a dose of about 0.4 displacement per atom (dpa). A two-step damage process is found on the basis of the disordered fractions deduced from RBS/C data. Complete amorphization cannot be reached upon both Au and Xe ion irradiations at 400 °C up to about 26 dpa because of the dynamic annealing of defects. When complete amorphization is reached at RT, the Young's modulus and Berkovich hardness of irradiated 6H-SiC samples are lower by, respectively, 40% and 45% than those of the virgin crystals. The out-of-plane expansion measured by surface profilometry increases versus irradiation dose and the saturation value measured in the completely amorphous layer (normalized to the ion projected range) is close to 25%. We show that the modifications of the macroscopic properties are mainly due to the amorphization of the material. The macroscopic elasticity constants and dimensional properties are predicted for a composite material made of crystalline matrix containing dispersed amorphous inclusions using simple analytical homogenization models. Voigt's model seems to give the best approximation for disordered fractions larger than 20% in the second step of the damage process.

Kerbiriou, Xavier; Costantini, Jean-Marc; Sauzay, Maxime; Sorieul, Stéphanie; Thomé, Lionel; Jagielski, Jacek; Grob, Jean-Jacques

2009-04-01

65

Amorphization and dynamic annealing of hexagonal SiC upon heavy-ion irradiation: Effects on swelling and mechanical properties  

SciTech Connect

Structural, mechanical, and dimensional evolutions of silicon carbide (SiC) induced by heavy-ion irradiations are studied by means of Rutherford backscattering spectrometry and channeling (RBS/C), nanoindentation, and surface profilometry measurements. 4H- and 6H-SiC single crystals were irradiated with 4 MeV Au{sup 2+} and 4 MeV Xe{sup +} ions at room temperature (RT) or 400 deg. C. Using a Monte Carlo program to simulate the RBS/C spectra (MCCHASY code), we find that Au ion irradiation at RT induces a total silicon sublattice disorder related to full amorphization at a dose of about 0.4 displacement per atom (dpa). A two-step damage process is found on the basis of the disordered fractions deduced from RBS/C data. Complete amorphization cannot be reached upon both Au and Xe ion irradiations at 400 deg. C up to about 26 dpa because of the dynamic annealing of defects. When complete amorphization is reached at RT, the Young's modulus and Berkovich hardness of irradiated 6H-SiC samples are lower by, respectively, 40% and 45% than those of the virgin crystals. The out-of-plane expansion measured by surface profilometry increases versus irradiation dose and the saturation value measured in the completely amorphous layer (normalized to the ion projected range) is close to 25%. We show that the modifications of the macroscopic properties are mainly due to the amorphization of the material. The macroscopic elasticity constants and dimensional properties are predicted for a composite material made of crystalline matrix containing dispersed amorphous inclusions using simple analytical homogenization models. Voigt's model seems to give the best approximation for disordered fractions larger than 20% in the second step of the damage process.

Kerbiriou, Xavier; Costantini, Jean-Marc; Sauzay, Maxime; Sorieul, Stephanie [CEA, DEN, SRMA, F-91191 Gif-sur-Yvette Cedex (France); Thome, Lionel [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CNRS/IN2P3/Univ. Paris-Sud, F-91405 Orsay-Campus (France); Jagielski, Jacek [Institute of Electronic Materials Technology, Wolczynska 133, PL-01-919 Warsaw, Poland and The Andrzej Soltan Institute for Nuclear Studies, 05-400 Swierk/Otwock (Poland); Grob, Jean-Jacques [InESS, 23 Rue du Loess, BP 20 CR, F-67037 Strasbourg (France)

2009-04-01

66

Local brain heavy ion irradiation induced Immunosuppression  

NASA Astrophysics Data System (ADS)

Purpose: To investigate the long term effect of acute local brain heavy ion irradiation on the peripheral immune system in rat model. Methodology: Only the brain of adult male Wistar rats were radiated by heavy ions at the dose of 15 Gy. One, two and three months after irradiation, thymus and spleen were analyzed by four ways. Tunel assay was performed to evaluate the percentage of apoptotic cells in thymus and spleen, level of Inflammatory cytokines (IL-2, IL-6, SSAO, and TNF-?) was detected by ELISA assay, the differentiation of thymus T lymphocyte subsets were measured by flow cytometry and the relative expression levels of genes related to thymus immune cell development were measured by using quantitative real-time PCR. Results: Thymus and spleen showed significant atrophy from one month to three months after irradiation. A high level of apoptosis in thymus and spleen were obtained and the latter was more vulnerable, also, high level of inflammatory cytokines were found. Genes (c-kit, Rag1, Rag2 and Sca1) related to thymus lymphocytes’ development were down-regulated. Conclusion: Local area radiation in the rat brain would cause the immunosuppression, especially, the losing of cell-mediated immune functions. In this model, radiation caused inflammation and then induced apoptosis of cells in the immune organs, which contributed to immunosuppression.

Lei, Runhong; Deng, Yulin; Huiyang Zhu, Bitlife.; Zhao, Tuo; Wang, Hailong; Yu, Yingqi; Ma, Hong; Wang, Xiao; Zhuang, Fengyuan; Qing, Hong

67

Study of damaged depth profiles of ion-irradiated PEEK  

Microsoft Academic Search

Thermal neutron depth profiling (TNDP) was used for the study of the free radical distribution in ion-irradiated poly-aryl-ether-ether ketone (PEEK). The thin PEEK film was irradiated by the 2 MeV O+ ions up to the fluence 6×1014 ions\\/cm2. The depth profiles of the free radicals in the ion-modified PEEK were traced by the Li+ ions incorporated to a damaged area of PEEK

J. Vacík; V. Hnatowicz; J. Cervena; P. Apel; S. Posta; Y. Kobayashi

2007-01-01

68

The interactions of high-energy, highly charged Xe ions with buckyballs  

SciTech Connect

Ionization and fragmentation have been measured for C{sub 60} molecules bombarded by highly charged (up to 35+) xenon ions with energies ranging up to 625 MeV. The observed mass distribution of positively charged fragments is explained in terms of a theoretical model indicating that the total interaction cross section contains roughly equal contributions from (a) excitation of the giant plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule. Preliminary results of measurements on VUV photons emitted in these interactions are also presented.

Ali, R.; Berry, H.G.; Cheng, S. [and others

1994-12-31

69

Enhanced adhesion from high energy ion irradiation  

NASA Technical Reports Server (NTRS)

It has been found that the adhesion of thin metal films on insulators, semiconductors, and metals could be improved by subjecting the material to a high-energy ion bombardment. Griffith et al. (1982) have first suggested a use of this technique with insulators. The present investigation has the objective to determine the mechanism for the adhesion enhancement. A description is presented of a preliminary transmission electron microscopy (TEM) study of thinned bonded samples of silver on silicon using electron diffraction. It is found that irradiation of a variety of thin film-substrate combinations by heavy ion beams will provide a remarkable improvement in the adherence of the film. The evidence for the mechanism involved in the enhancement of adhesion is discussed.

Werner, B. T.; Vreeland, T., Jr.; Mendenhall, M. H.; Qui, Y.; Tombrello, T. A.

1983-01-01

70

Neurite outgrowth on fluorinated polyimide film micropatterned by ion irradiation  

NASA Astrophysics Data System (ADS)

In this study, we investigated neurite outgrowth on a fluorinated polyimide film micropatterned by ion irradiation. We used the fluorinated polyimide because of its excellent thermal and mechanical properties and biocompatibility. Rattus norvegicus chromaphin (PC12) cells were used for in vitro studies. The polyimide films were irradiated with He +, Ne + or Kr + at 1 × 10 14 ions/cm 2 using an ion-beam mask. The lines in the mask were 120 and 160 ?m wide and 120-160 ?m apart. PC12 cells were selectively adhered on the polyimide film micropatterned by Kr +-irradiation. However, the neurite length on the film irradiated by Kr + was shorter than that determined in the film irradiated by He +. On the other hand, neurite outgrowth on the polyimide film micropatterned by He +-irradiation was at least 100 ?m in length. This initial study indicated the enhanced outgrowth of PC12 cells on the fluorinated polyimide film micropatterned by ion irradiation.

Okuyama, Y.; Sato, M.; Nagaoka, S.; Kawakami, H.; Suzuki, Y.; Iwaki, M.

2003-05-01

71

Graphitization of polymer surfaces by scanning ion irradiation  

NASA Astrophysics Data System (ADS)

Graphitization of polymer surfaces was performed by low-energy Ar+ and He+ ion irradiation. A method of scanning irradiation was implemented. It was found that by scanning ion irradiation, a significantly higher electrical conductivity in the graphitized layers can be achieved in comparison with a conventional broad-beam irradiation. The enhancement of the conductance becomes more pronounced for narrower and better collimated ion beams. In order to analyze these results in more detail, the temperature dependence of conductance of the irradiated samples was investigated. The results of measurements are discussed in terms of weak localization corrections to conductance in disordered metals. The observed effects can be explained by enlargement of graphitic patches, which was achieved with the scanning ion irradiation method.

Koval, Yuri

2014-10-01

72

Spectroscopic characterization of ion-irradiated multi-layer graphenes  

NASA Astrophysics Data System (ADS)

Low-energy Ar ions (0.5-2 keV) were irradiated to multi-layer graphenes and the damage process, the local electronic states, and the degree of alignment of the basal plane, and the oxidation process upon ion irradiation were investigated by Raman spectroscopy, soft X-ray absorption spectroscopy (XAS) and in situ X-ray photoelectron spectroscopy (XPS). By Raman spectroscopy, we observed two stages similar to the case of irradiated graphite, which should relate to the accumulations of vacancies and turbulence of the basal plane, respectively. XAS analysis indicated that the number of sp2-hybridized carbon (sp2-C) atoms decreased after ion irradiation. Angle-resolved XAS revealed that the orientation parameter (OP) decreased with increasing ion energy and fluence, reflecting the turbulence of the basal plane under irradiation. In situ XPS shows the oxidation of the irradiated multi-layer graphenes after air exposure.

Tsukagoshi, Akira; Honda, Shin-ichi; Osugi, Ryo; Okada, Hiraku; Niibe, Masahito; Terasawa, Mititaka; Hirase, Ryuji; Izumi, Hirokazu; Yoshioka, Hideki; Niwase, Keisuke; Taguchi, Eiji; Lee, Kuei-Yi; Oura, Masaki

2013-11-01

73

Generation of colour centres in yttria-stabilized zirconia by heavy ion irradiations in the GeV range  

NASA Astrophysics Data System (ADS)

We have studied the colour centre production in yttria-stabilized zirconia (ZrO2:Y3 + ) by heavy ion irradiation in the GeV range using on-line UV-visible optical absorption spectroscopy. Experiments were performed with 11.4 MeV amu - 1 127Xe, 197Au, 208Pb and 238U ion irradiations at 8 K or room temperature (RT). A broad and asymmetrical absorption band peaked at a wavelength about 500 nm is recorded regardless of the irradiation parameters, in agreement with previous RT irradiations with heavy ions in the 100 MeV range. This band is de-convoluted into two broad Gaussian-shaped bands centred at photon energies about 2.4 and 3.1 eV that are respectively associated with the F + -type centres (involving a singly ionized oxygen vacancy, VO·) and T centres (i.e. Zr3 + in a trigonal symmetry) observed by electron paramagnetic resonance (EPR) spectroscopy. In the case of 8 K Au ion irradiation at low fluences, six bands are used at about 1.9, 2.3, 2.7, 3.1 and 4.0 eV. The three bands near 2.0-2.5 eV can be assigned to oxygen divacancies (i.e. F2 + centres). No significant effect of the irradiation temperature is found on the widths of all absorption bands for the same ion and fluence. This is attributed to the inhomogeneous broadening arising from the static disorder due to the native charge-compensating oxygen vacancies. However, the colour centre production yield is strongly enhanced at 8 K with respect to RT. When heating irradiated samples from 8 K to RT, the extra colour centres produced at low temperature do not recover completely to the level of RT irradiation. The latter results are accounted for by an electronically driven defect recovery process.

Costantini, Jean-Marc; Beuneu, François; Schwartz, Kurt; Trautmann, Christina

2010-08-01

74

Concurrent in situ ion irradiation transmission electron microscope  

NASA Astrophysics Data System (ADS)

An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8-30 keV) during high-energy heavy ion irradiation (0.8-48 MeV). Initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

Hattar, K.; Bufford, D. C.; Buller, D. L.

2014-11-01

75

Light-emitting Si nanostructures formed in SiO{sub 2} on irradiation with swift heavy ions  

SciTech Connect

SiO{sub 2} layers containing implanted excess Si are irradiated with Xe ions with an energy of 130 MeV and doses of 3 x 10{sup 12}-10{sup 14} cm{sup -2}. In the samples irradiated with a dose of 3 x 10{sup 12} cm{sup -2}, {approx}10{sup 12} cm{sup -2} segregated clusters 3-4 nm in dimension are detected by transmission electron microscopy. With increasing dose, the dimensions and number of these clusters increase. In the photoluminescence spectrum, a 660- to 680-nm band is observed, with the intensity dependent on the dose. After passivation of the sample with hydrogen at 500 deg. C, the band disappears, but a new {approx}780-nm band typical of Si nanocrystals becomes evident. On the basis of the entire set of data, it is concluded that the 660- to 680-nm band is associated with imperfect Si nanocrystals grown in the tracks of Xe ions due to high ionization losses. The nonmonotonic dependence of the photoluminescence intensity on the dose is attributed to the difference between the diameters of tracks and the diameters of the displacements' cascades responsible for defect formation.

Kachurin, G. A., E-mail: kachurin@isp.nsc.ru; Cherkova, S. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Skuratov, V. A. [Joint Institute for Nuclear Research (Russian Federation); Marin, D. V.; Cherkov, A. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2010-04-15

76

Direct Observation of Ion-irradiation-induced Chemical Mixing  

SciTech Connect

Irradiation-induced dissolution of particles and mixing at heterogeneous interfaces in materials is of importance for ion beam processing and radiation materials sciences. Modeling has predicted dissolution of particles and homogenization at sharp chemical interfaces; imaging and depth profiling techniques have also been used to observe damage and mixing resulting from ion or neutron bombardment. Analytical scanning transmission electron microscopy has been used to directly observe the ion-irradiation induced elemental mixing and dissolution of {approx}25-50 nm titanium oxycarbonitrides in a nanostructured ferritic alloy irradiated at 173 K. The magnitude of the mixed zone is consistent with radiation damage theory.

Parish, Chad M.; Edmondson, P. D.; Zhang, Yanwen; Miller, Michael K.

2011-11-01

77

Direct observation of ion-irradiation-induced chemical mixing  

SciTech Connect

Irradiation-induced dissolution of particles and mixing at heterogeneous interfaces in materials is of importance for ion beam processing and radiation materials sciences. Modeling has predicted dissolution of particles and homogenization at sharp chemical interfaces; imaging and depth profiling techniques have also been used to observe damage and mixing resulting from ion or neutron bombardment. Analytical scanning transmission electron microscopy has been used to directly observe the ion-irradiation induced elemental mixing and dissolution of {approx}25-50 nm titanium oxycarbonitrides in a nanostructured ferritic alloy irradiated at 173 K. The magnitude of the mixed zone is consistent with radiation damage theory.

Edmondson, Philip D [ORNL; Miller, Michael K [ORNL; Parish, Chad M [ORNL; Zhang, Yanwen [ORNL

2011-01-01

78

Swift heavy ion irradiation of crystalline CdTe  

NASA Astrophysics Data System (ADS)

The influence of high electronic energy deposition in cadmium telluride (CdTe) was investigated using Rutherford backscattering spectrometry in channelling configuration as well as high-resolution transmission electron microscopy. Swift heavy ion irradiation was performed at room temperature with 185 MeV Au ions at perpendicular and non-perpendicular ion incidence. Independent of the ion incidence angle, neither ion beam induced point defects nor amorphous ion tracks were observed along the ion path. In contrast, the irradiated layer possesses a high crystalline quality even after irradiation with high ion fluences, i.e. multiple ion overlap. Nevertheless, irradiation with swift heavy ions leads to the formation of extended defects in a thin layer close to the sample surface. With increasing ion fluence the concentration of these extended defects increases continuously. This suggests that high electronic energy deposition causes the formation of defects, however, the combination of the high defect mobility within the thermal spike and the high ionicity of CdTe may benefit an effective recovery of the ionic bonds and consequently an easy recovery of the lattice, i.e. a nearly perfect recrystallization. The experimentally observed high defect resistivity enables a high doping of foreign atoms in CdTe over a wide depth range without the formation of lattice defects which is important for the use of CdTe as an effective absorber for solar cells.

Steinbach, T.; Bierschenk, Th; Milz, S.; Ridgway, M. C.; Wesch, W.

2014-02-01

79

Atomistic simulations of MeV ion irradiation of silica  

SciTech Connect

We used molecular dynamics simulations to study 2.3 MeV Au ion irradiation of silica. In this energy regime, the instantaneous energy loss of the ion is divided almost equally between electronic and nuclear energy loss. The inelastic thermal spike model was used to model the electron-phonon interactions due to the high electronic energy loss. Binary collision approximation calculations provided input for the recoil energies due to MeV ions. We performed simulations of the damage due to the separate damage mechanisms as well as together, and found that the inelastic thermal spike is needed to accurately simulate the irradiation damage from MeV ions.

Backman, Marie [University of Tennessee, Knoxville (UTK); Djurabekova, Flyura [University of Helsinki; Pakarinen, Olli H [University of Helsinki; Nordlund, Kai [University of Helsinki; Zhang, Yanwen [ORNL; Toulemonde, Marcel [CEA-CNRS-ENSICAEN-University of Caen, FRANCE; Weber, William J [ORNL

2013-01-01

80

Amorphization of SiC under ion and neutron irradiation  

Microsoft Academic Search

This paper presents results on the microstructure and physical properties of SiC amorphized by both ion and neutron irradiation. Specifically, 0.56 MeV Si ions have been implanted in single crystal 6H–SiC from ambient through >200°C and the critical threshold for amorphization was measured as a function of the irradiation temperature. From a high resolution transmission electron microscopy (HRTEM) study of

L. L. Snead; S. J. Zinkle; J. C. Hay; M. C. Osborne

1998-01-01

81

Colloidal assemblies modied by ion irradiation E. Snoeks a  

E-print Network

. The 290 nm and 1.1 lm diameter colloids were deposited on a Si substrate and irradiated at 90 K, using for thin-®lm deposition, and in tuning the optical properties of three-dimensional colloidal crystals. �Colloidal assemblies modi®ed by ion irradiation E. Snoeks a , A. van Blaaderen a,b , T. van Dillen

Polman, Albert

82

Heavy-ion irradiation induced diamond formation in carbonaceous materials.  

SciTech Connect

The basic mechanisms of metastable phase formation produced under highly non-equilibrium thermodynamic conditions within high-energy particle tracks are investigated. In particular, the possible formation of diamond by heavy-ion irradiation of graphite at ambient temperature is examined. This work was motivated, in part, by earlier studies which discovered nanometer-grain polycrystalline diamond aggregates of submicron-size in uranium-rich carbonaceous mineral assemblages of Precambrian age. It was proposed that the radioactive decay of uranium formed diamond in the fission particle tracks produced in the carbonaceous minerals. To test the hypothesis that nanodiamonds can form by ion irradiation, fine-grain polycrystalline graphite sheets were irradiated with 400 MeV Kr ions. The ion irradiated graphite (and unirradiated graphite control) were then subjected to acid dissolution treatments to remove the graphite and isolate any diamonds that were produced. The acid residues were then characterized by analytical and high-resolution transmission electron microscopy. The acid residues of the ion-irradiated graphite were found to contain ppm concentrations of nanodiamonds, suggesting that ion irradiation of bulk graphite at ambient temperature can produce diamond.

Daulton, T. L.

1999-01-08

83

The effects of swift heavy-ion irradiation on helium-ion-implanted silicon  

NASA Astrophysics Data System (ADS)

Cross-sectional transmission electron microscopy (XTEM) was used to study the effects of irradiation with swift heavy ions on helium-implanted silicon. <1 0 0>-oriented silicon wafers were implanted with 30 keV helium to a dose of 3 × 1016 He+/cm2 at 600 K. Subsequently, the helium-implanted Si wafers were irradiated with 792 MeV argon ions. The He bubbles and extended defects in the wafers were examined via XTEM analysis. The results reveal that the mean diameter of the He bubbles increases upon Ar-ion irradiation, while the number density of the He bubbles decreases. The microstructure of the He bubbles observed after Ar-ion irradiation is comparable to that observed after annealing at 1073 K for 30 min. Similarly, the mean size of the extended defects, i.e., Frank loops, increases after Ar-ion irradiation. Possible mechanisms are discussed.

Li, B. S.; Du, Y. Y.; Wang, Z. G.; Shen, T. L.; Li, Y. F.; Yao, C. F.; Sun, J. R.; Cui, M. H.; Wei, K. F.; Zhang, H. P.; Shen, Y. B.; Zhu, Y. B.; Pang, L. L.

2014-10-01

84

Ion irradiation tolerance of graphene as studied by atomistic simulations  

SciTech Connect

As impermeable to gas molecules and at the same time transparent to high-energy ions, graphene has been suggested as a window material for separating a high-vacuum ion beam system from targets kept at ambient conditions. However, accumulation of irradiation-induced damage in the graphene membrane may give rise to its mechanical failure. Using atomistic simulations, we demonstrate that irradiated graphene even with a high vacancy concentration does not show signs of such instability, indicating a considerable robustness of graphene windows. We further show that upper and lower estimates for the irradiation damage in graphene can be set using a simple model.

Ahlgren, E. H.; Lehtinen, O. [Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland); Kotakoski, J. [Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland); Department of Physics, University of Vienna, Boltzmanngasse 5, 1190 Wien (Austria); Krasheninnikov, A. V. [Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland); Department of Applied Physics, Aalto University, P.O. Box 1100, 00076 Aalto (Finland)

2012-06-04

85

Formation, Dynamics, and Characterization of Nanostructures by Ion Beam Irradiation  

Microsoft Academic Search

Ion beam irradiation is a potential tool for phase formation and material modification as a non-equilibrium technique. Localized rise in temperature and ultra fast (?10 s) dissipations of impinging energy make it an attractive tool for metastable phase formation. As a matter of fact, a major component of materials science is dominated by ion beam methods, either for synthesis of

S. Dhara

2007-01-01

86

Static electric polarizabilities and first hyperpolarizabilities of molecular ions RgH + (Rg = He, Ne, Ar, Kr, Xe): ab initio study  

NASA Astrophysics Data System (ADS)

Extensive ab initio calculations of static electric properties of molecular ions of general formula RgH + (Rg = He, Ne, Ar, Kr, Xe) involving the finite field method and coupled cluster CCSD(T) approach have been done. The relativistic effects were taken into account by Douglas-Kroll-Hess approximation. The numerical stability and reliability of calculated values have been tested using the systematic sequence of Dunning's cc-pVXZ-DK and ANO-RCC-VQZP basis sets. The influence of ZPE and pure vibrational contribution has been discussed. The component ?zz has increasing trend in RgH + while the relativistic effect on ?zz leads to a small increase of this molecular parameter.

Cukras, Janusz; Antušek, Andrej; Holka, Filip; Sadlej, Joanna

2009-06-01

87

University of Wisconsin Ion Beam Laboratory: A facility for irradiated materials and ion beam analysis  

NASA Astrophysics Data System (ADS)

The University of Wisconsin Ion Beam Laboratory (UW-IBL) has recently undergone significant infrastructure upgrades to facilitate graduate level research in irradiated materials phenomena and ion beam analysis. A National Electrostatics Corp. (NEC) Torodial Volume Ion Source (TORVIS), the keystone upgrade for the facility, can produce currents of hydrogen ions and helium ions up to ~200 ?A and ~5 ?A, respectively. Recent upgrades also include RBS analysis packages, end station developments for irradiation of relevant material systems, and the development of an in-house touch screen based graphical user interface for ion beam monitoring. Key research facilitated by these upgrades includes irradiation of nuclear fuels, studies of interfacial phenomena under irradiation, and clustering dynamics of irradiated oxide dispersion strengthened steels. The UW-IBL has also partnered with the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) to provide access to the irradiation facilities housed at the UW-IBL as well as access to post irradiation facilities housed at the UW Characterization Laboratory for Irradiated Materials (CLIM) and other ATR-NSUF partner facilities. Partnering allows for rapid turnaround from proposed research to finalized results through the ATR-NSUF rapid turnaround proposal system. An overview of the UW-IBL including CLIM and relevant research is summarized.

Field, K. G.; Wetteland, C. J.; Cao, G.; Maier, B. R.; Dickerson, C.; Gerczak, T. J.; Field, C. R.; Kriewaldt, K.; Sridharan, K.; Allen, T. R.

2013-04-01

88

Ar+ and Xe+ Velocities near the Presheath-Sheath Boundary in an Ar\\/Xe Discharge  

Microsoft Academic Search

The velocities of Ar+ and Xe+ ions near the presheath-sheath boundary in an Ar\\/Xe discharge are studied by particle-in-cell Monte Carlo simulation. For a pure argon discharge the argon ion has almost the same velocity profile as it does in the mixture of argon and xenon. Similarly, for a xenon discharge the xenon ion has almost the same velocity profile

J. T. Gudmundsson; M. A. Lieberman

2011-01-01

89

Response of Strontium Titanate to Ion and Electron Irradiation  

SciTech Connect

Response of strontium titanate (SrTiO3) to ion and electron irradiation is studied at room temperature. For an accurate energy to depth conversion and a better determination of ion-induced disorder profile from Rutherford backscattering spectrometry measurement, a detailed iterative procedure is described and applied to ion channeling spectra to determine the dechanneling yield and the disorder profiles for the Sr and Ti sublattices. The result shows a large underestimation in disorder depth, ~ 40% at the damage peak, which indicates a large overestimation of the electronic stopping power for 1.0 MeV Au ions in SrTiO3 predicted by the SRIM (Stopping and Range of Ions in Matter) code. Overestimation of heavy ion stopping power may lead to an overestimation of the critical dose for amorphization. The current study also demonstrates possible ionization effects in SrTiO3 under ion and electron irradiation. Pre-amorphized SrTiO3 exhibits strong ionization-induced epitaxial recovery at the amorphous/crystalline interface under electron irradiation.

Zhang, Yanwen; Lian, Jie; Zhu, Zihua; Bennett, Wendy D.; Saraf, Laxmikant V.; Rausch, Julie L.; Hendricks, Catherine A.; Ewing, R. C.; Weber, William J.

2009-04-20

90

Time-dependent characteristics of the dielectric barrier discharge in Xe-Cl2 mixture and kinetics of the XeCl? molecules  

NASA Astrophysics Data System (ADS)

Time-dependent characteristics of the dielectric barrier discharge in Xe-Cl2 mixture at chlorine concentration of 0.5% and kinetic processes governing the generation of XeCl? molecules are studied using the 1D fluid model. It is shown that at low voltage amplitude (5 kV) a one-peak mode of the discharge is observed and at high voltage amplitude (7 kV) a two-peak mode of the discharge appears. The radiation power of the XeCl? band increases with amplitude of the supply voltage. It is demonstrated that the harpoon reaction Xe? + Cl2 ? XeCl? + Cl provides the greatest contribution into generation of XeCl? exciplex molecules during short current pulses and the ion-ion recombination Xe+ 2 + Cl- ? XeCl* + Xe provides the greatest contribution during afterglow. Quenching of XeCl? molecules is a result of the radiative decay XeCl? ? Xe + Cl + hv (308 nm). During current spike the great contribution into quenching of XeCl? provides also the dissociative ionization e + XeCl? ? Xe+ + Cl + 2e.

Avtaeva, Svetlana

2014-04-01

91

Multiphoton ionization of iodine atoms and CF 3I molecules by XeCl laser radiation  

NASA Astrophysics Data System (ADS)

We report about effective ionization of iodine atoms and CF3I molecules under the action of intense XeCl laser radiation (308 nm). The only ion fragment resulting from the irradiation of the CF3I molecules is the I+ ion. We have studied the influence of the intensity, spectral composition, and polarization of the laser radiation used on the intensity of the ion signal and the shape of its time-of-flight peak. Based on the analysis of the results obtained, we have suggested the mechanism of this effect. The conclusion drawn is that the ionization of the iodine atoms by the ordinary XeCl laser with a nonselective cavity results from a three- (2 + 1)-photon REMPI process. This process is in turn due to the presence of accidental two-photon resonances between various spectral components of the laser radiation and the corresponding intermediate excited states of the iodine atom. The probability of ionization of the atoms from their ground state I(2P3/2) by the radiation of the ordinary XeCl laser is more than two orders of magnitude higher than the probability of their ionization from the metastable state I*(2P1/2). The ionization of the CF3I molecules by the XeCl laser radiation occurs as a result of a four-photon process involving the preliminary one-photon dissociation of these molecules and the subsequent (2 + 1)-photon REMPI of the resultant neutral iodine atoms.

Lokhman, V. N.; Ogurok, D. D.; Ryabov, E. A.

2008-01-01

92

Lithium ion irradiation effects on epitaxial silicon detectors  

Microsoft Academic Search

Diodes manufactured on a thin and highly doped epitaxial silicon layer grown on a Czochralski silicon substrate have been irradiated by high energy lithium ions in order to investigate the effects of high bulk damage levels. This information is useful for possible developments of pixel detectors in future very high luminosity colliders because these new devices present superior radiation hardness

Andrea Candelori; Andreas Schramm; Dario Bisello; Devis Contarato; Eckhart Fretwurst; Gunnar Lindström; Riccardo Rando; Jeff Wyss

2004-01-01

93

Evaporation of ion-irradiated disks  

E-print Network

We calculate the evaporation of a cool accretion disk around a black hole due to the ion-bombardment by an ion supported accretion flow (here ISAF, or optically thin ADAF). As first suggested by Spruit & Deufel (2002), this evaporation takes place in two stages: ion bombardment of the cool disk (Shakura-Sunyaev disk: SSD) produces an intermediate-temperature layer on top of the disk (`warm layer') which constitutes an independent accretion flow on both sides of the SSD. As this warm material accretes inward of the inner radius of the SSD, it becomes thermally unstable by lack of cooling of photons, and evaporates into the ISAF, thereby feeding the latter. Angular momentum conservation forces a certain fraction of the ISAF material to move outward, where it can bombard the SSD with its hot ions. The flow geometry is derived by computing stationary solutions of the continuity- and angular momentum equations for the three components (ISAF, warm flow and SSD). The overall radiative output is dominated by hard X-rays. They are produced mostly from the warm component, rather than the ISAF. The expected time dependence and stability of the flow, not computed here, is discussed briefly.

C. P. Dullemond; H. C. Spruit

2005-01-21

94

Evaporation of ion-irradiated disks  

NASA Astrophysics Data System (ADS)

We calculate the evaporation of a cool accretion disk around a black hole due to the ion-bombardment by an ion supported accretion flow (here ISAF, or optically thin ADAF). As first suggested by Spruit & Deufel (2002), this evaporation takes place in two stages: ion bombardment of the cool disk (Shakura-Sunyaev disk: SSD) produces an intermediate-temperature layer on top of the disk (“warm layer”) which constitutes an independent accretion flow on both sides of the SSD. As this warm material accretes inward of the inner radius of the SSD, it becomes thermally unstable by lack of cooling of photons, and evaporates into the ISAF, thereby feeding the latter. Angular momentum conservation forces a certain fraction of the ISAF material to move outward, where it can bombard the SSD with its hot ions. The flow geometry is derived by computing stationary solutions of the continuity- and angular momentum equations for the three components (ISAF, warm flow and SSD). The overall radiative output is dominated by hard X-rays. They are produced mostly from the warm component, rather than the ISAF. The expected time dependence and stability of the flow, not computed here, is discussed briefly.

Dullemond, C. P.; Spruit, H. C.

2005-05-01

95

Stability of uranium silicides during high energy ion irradiation  

SciTech Connect

Changes induced by 1.5 MeV Kr ion irradiation of both U{sub 3}Si and U{sub 3}Si{sub 2} have been followed by in situ transmission electron microscopy. When irradiated at sufficiently low temperatures, both alloys transform from the crystalline to the amorphous state. When irradiated at temperatures above the temperature limit for ion beam amorphization, both compounds disorder with the Martensite twin structure in U{sub 3}Si disappearing from view in TEM. Prolonged irradiation of the disordered crystalline phases results in nucleation of small crystallites within the initially large crystal grains. The new crystallites increase in number during continued irradiation until a fine grain structure is formed. Electron diffraction yields a powder-like diffraction pattern that indicates a random alignment of the small crystallites. During a second irradiation at lower temperatures, the small crystallizes retard amorphization. After 2 dpa at high temperatures, the amorphization dose is increased by over twenty times compared to that of initially unirradiated material.

Birtcher, R.C; Wang, L.M.

1991-11-01

96

Effects of Ga ion-beam irradiation on monolayer graphene  

SciTech Connect

The effects of Ga ion on the single layer graphene (SLG) have been studied by Raman spectroscopy (RS), SEM, and field-effect characterization. Under vacuum conditions, Ga ion-irradiation can induce disorders and cause red shift of 2D band of RS, rather than lattice damage in high quality SLG. The compressive strain induced by Ga ion decreases the crystalline size in SLG, which is responsible for the variation of Raman scattering and electrical properties. Nonlinear out-put characteristic and resistance increased are also found in the I-V measurement. The results have important implications during CVD graphene characterization and related device fabrication.

Wang, Quan; Mao, Wei; Zhang, Yanmin; Shao, Ying; Ren, Naifei [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China)] [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Ge, Daohan [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China) [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2013-08-12

97

Effects on focused ion beam irradiation on MOS transistors  

SciTech Connect

The effects of irradiation from a focused ion beam (FIB) system on MOS transistors are reported systematically for the first time. Three MOS transistor technologies, with 0.5, 1, and 3 {mu}m minimum feature sizes and with gate oxide thicknesses ranging from 11 to 50 nm, were analyzed. Significant shifts in transistor parameters (such as threshold voltage, transconductance, and mobility) were observed following irradiation with a 30 keV Ga{sup +} focused ion beam with ion doses varying by over 5 orders of magnitude. The apparent damage mechanism (which involved the creation of interface traps, oxide trapped charge, or both) and extent of damage were different for each of the three technologies investigated.

Campbell, A.N.; Peterson, K.A.; Fleetwood, D.M.; Soden, J.M.

1997-04-01

98

Comparison of irradiation hardening and microstructure evolution in ion-irradiated delta and epsilon hydrides  

NASA Astrophysics Data System (ADS)

A ?-Zr-hydride was irradiated with 6.4 MeV Fe3+ ions to clarify the relationship between hardening and microstructural changes of bulk Zr-hydrides under neutron irradiation. Irradiation hardening was measured by nanoindentation tests. Transmission electron microscope cross-sectional observations showed that the deformation mechanism of the ?-Zr-hydride was both slip and twinning. Dislocation loops were observed in the irradiated hydride matrix. These irradiation-induced defects make slip deformation difficult and consequently promote the twin deformation of ?-Zr-hydride. This work is a continuation of the previous our work (J. Nucl. Mater. 419 (2011) 366-370) focused upon ?-Zr-hydride and we discuss a comparison between the two Zr-hydrides. The deformation mechanism involves both slip and twinning. Cracks were formed in both the irradiated and unirradiated area. epsi;-phase (fct structure): Twinning is the dominant deformation mechanism. Some slip deformation was also observed. Cracks were formed at the Berkovich indentations in the irradiated area. Ion irradiation does not change the deformation mechanism in either phase, although twin deformation and crack formation were more frequently observed in the irradiated regions of ?-phase and ?-phase, respectively. The difference of the deformation mechanism between ?-phase and ?-phase can be explained by the difference in the stacking fault energy between the two phases. According to Udagawa et al. [26] the stacking fault energy in the Zr-hydride decreases with increasing the hydrogen content. This indicates that deformation may occur more easily in the ?-phase than in the ?-phase. For the ?-phase, the deformation mechanism is deduced to be the slip system of calcium fluoride, that is to say, {1 1 1}<1 1 0> slip deformation is dominant [27]. Irradiation-induced defects hinder the dislocation glide causing twinning to dominate the deformation.

Oono, Naoko; Kasada, Ryuta; Higuchi, Toru; Sakamoto, Kan; Nakatsuka, Masafumi; Hasegawa, Akiko; Kondo, Sosuke; Iwata, Noriyuki Y.; Matsui, Hideki; Kimura, Akihiko

2013-11-01

99

Observation of Visible and Near-UV M1 Transitions from Highly Charged Kr, Mo and Xe Ions in LHD and its Prospect to Impurity Spectroscopy for D-T Burning Plasmas  

NASA Astrophysics Data System (ADS)

Magnetic dipole (M1) transitions from highly charged heavy impurities have been surveyed in visible and near-UV wavelength ranges longer than 2500 Å using a 1.33 m Czerny-Turner spectrometer in the Large Helical Device (LHD) for use in future visible impurity spectroscopy of D-T burning plasmas. The M1 transitions of KrXXII (Kr21+: P-like) 3s23p3 2D3/2-2D5/2 3463.75 ± 0.05 Å, KrXXIII (Kr22+: Si-like) 3s23p2 3P1-3P2 3841.07 ± 0.03 Å, MoXXIX (Mo28+: Si-like) 3s23p2 3P1-3P2 2842.10 ± 0.05 Å, XeXXXIII (Xe32+: Ti-like) 3d4 5D3-5D2 4139.01 ± 0.02 Å have been successfully observed using an external puff of Kr and Xe and an impurity pellet injection of Mo. As a result, the identication of the Ti-like XeXXXIII M1 transition, as observation for the first time in laboratory fusion plasmas, strongly suggests that the visible impurity spectroscopy of tungsten ions using Ti-like WLIII (W52+: 3626 Å) instead of the conventionally used EUV spectroscopy is possible in future D-T burning plasmas.

Katai, Ryuji; Morita, Shigeru; Goto, Motoshi

100

Kr ion irradiation study of the depleted-uranium alloys  

NASA Astrophysics Data System (ADS)

Fuel development for the reduced enrichment research and test reactor (RERTR) program is tasked with the development of new low enrichment uranium nuclear fuels that can be employed to replace existing high enrichment uranium fuels currently used in some research reactors throughout the world. For dispersion type fuels, radiation stability of the fuel-cladding interaction product has a strong impact on fuel performance. Three depleted-uranium alloys are cast for the radiation stability studies of the fuel-cladding interaction product using Kr ion irradiation to investigate radiation damage from fission products. SEM analysis indicates the presence of the phases of interest: U(Al, Si) 3, (U, Mo)(Al, Si) 3, UMo 2Al 20, U 6Mo 4Al 43 and UAl 4. Irradiations of TEM disc samples were conducted with 500 keV Kr ions at 200 °C to ion doses up to 2.5 × 10 19 ions/m 2 (˜10 dpa) with an Kr ion flux of 10 16 ions/m 2/s (˜4.0 × 10 -3 dpa/s). Microstructural evolution of the phases relevant to fuel-cladding interaction products was investigated using transmission electron microscopy.

Gan, J.; Keiser, D. D.; Miller, B. D.; Kirk, M. A.; Rest, J.; Allen, T. R.; Wachs, D. M.

2010-12-01

101

Kr Ion Irradiation Study of the Depleted-Uranium Alloys  

SciTech Connect

Fuel development for the Reduced Enrichment Research and Test Reactor program is tasked with the development of new low-enriched uranium nuclear fuels that can be employed to replace existing highly enriched uranium fuels currently used in some research reactors throughout the world. For dispersion-type fuels, radiation stability of the fuel/cladding interaction product has a strong impact on fuel performance. Three depleted uranium alloys are cast for the radiation stability studies of the fuel/cladding interaction product using Kr ion irradiation to investigate radiation damage from fission products. SEM analysis indicates the presence of the phases of interest: U(Si, Al)3, (U, Mo)(Si, Al)3, UMo2Al20, U6Mo4Al43, and UAl4. Irradiations of TEM disc samples were conducted with 500 keV Kr ions at 200ºC to ion doses up to 2.5 × 1015 ions/cm2 (~ 10 dpa) with an Kr ion flux of 1012 ions/cm2-sec (~ 4.0 × 10-3 dpa/sec). Microstructural evolution of the phases relevant to fuel-cladding interaction products was investigated using transmission electron microscopy.

J. Gan; D. Keiser; B. Miller; M. Kirk; J. Rest; T. Allen; D. Wachs

2010-12-01

102

Micromechanical tests of ion irradiated materials: Atomistic simulations and experiments  

SciTech Connect

We investigated irradiation effects on Fe-Cr binary alloys by using a nano-indentation combined with a continuous stiffness measurement (CSM) technique. We modeled the nano-indentation test by using a finite element method. We could extract the intrinsic hardness and the yield stress of an irradiation hardened region by using a so-called inverse method. SiC micro-pillars of various sizes were fabricated by mask and inductively coupled plasma etching technique and compressed by using flat punch nano-indentation. Compressive fracture strength showed a clear specimen size effect. Brittle-to-Ductile transition at room temperature was observed as the specimen size decreases. The effect of irradiation on the fracture strength of SiC micro-pillars was evaluated by performing ion irradiation with Si ions. We have performed molecular dynamics simulations of nano-indentation and nano-pillar compression tests. Radiation effect was observed which is found to be due to the interaction of dislocations nucleated by spherical indenter with pre-existing radiation defects (voids). These atomistic simulations are expected to significantly contribute to the investigation of the fundamental deformation mechanism of small scale irradiated materials. (authors)

Shin, C.; Jin, H. H.; Kwon, J. [Nuclear Materials Research Div., Korea Atomic Energy Research Inst., Daejeon, 305-353 (Korea, Republic of)

2012-07-01

103

Elastic wave from fast heavy ion irradiation on solids  

NASA Astrophysics Data System (ADS)

To study the time-dependent mechanical effects of fast heavy ion irradiations, we have irradiated various solids by a short-bunch beam of 95 MeV/u Ar ions and observed elastic waves generated in the bulk. The irradiated targets were square-shaped plates of poly-crystals of metals (Al and Cu), invar alloy, ceramic (Al 2O 3), fused silica (SiO 2) and single crystals of KC1 and LiF with a thickness of 10 mm. The beam was incident perpendicular to the surface and all ions were stopped in the target. Two piezo-electric ultrasonic sensors were attached to the surface of the target and detected the elastic waves. The elastic waveforms as well as the time structure and intensity of the beam bunch were recorded for each shot of a beam bunch. The sensor placed opposite to the beam spot recorded a clear waveform of the longitudinal wave across the material, except for the invar and fused silica targets. From its propagation time along with the sound velocity and the thickness of the target, the depth of the wave source was estimated. The result was compared with ion ranges calculated for these materials by TRIM code.

Kambara, T.; Kageyama, K.; Kanai, Y.; Kojima, T. M.; Nanai, Y.; Yoneda, A.; Yamazaki, Y.

2002-06-01

104

Low energy argon ion irradiation surface effects on triglycine sulfate  

NASA Astrophysics Data System (ADS)

An experimental study of the effects of low energy (1-2 keV) argon ion (Ar+) irradiation on Triglycine Sulfate (TGS) has been performed. Ferroelectric parameters, such as the Curie temperature TC determined from the dielectric constant peaks ?(T), or the remnant polarization Pr, and coercive field Ec, obtained from the hysteresis loops, show interesting differences between samples irradiated in ferroelectric and paraelectric phases, respectively. The radiation damage seems to be superficial, as observed by AFM microscope, and the surface alteration in both phases becomes eventually notorious when the radiation dosage increases.

Aragó, Carmen; Plaza, José L.; Marqués, Manuel I.; Gonzalo, Julio A.

2013-09-01

105

Crystallographic analysis of the amorphization caused by ion irradiation: Self-irradiation  

NASA Astrophysics Data System (ADS)

We have examined a mechanism of Si amorphization, by a classical molecular-dynamics, paying attention to whether or not the self-interstitial atom (SIA) clusters were a precursor to amorphization, when a crystalline Si was self-irradiated by several keV ions at a low temperature of 100 K. The pixel mapping (PM) analyzed crystallographically a crystalline to amorphous (CA) transition caused by ion irradiation by means of a set of long-range-order parameters. The spatial distribution of SIAs were also counted by PM. Throughout the sequential self-irradiation, the fraction of isolated SIAs was dominant. Although the fractions were small, we found the significant increase of small SIA clusters, e.g. I2-I4, as the crystalline state was being collapsed. We conclude that those small SIA clusters can be the trigger to enhance the production of more SIAs, and results in CA transition.

Nakagawa, S. T.

2003-05-01

106

Magnetic properties of graphite irradiated with MeV ions  

SciTech Connect

We have studied the change in the magnetic properties produced on highly oriented pyrolytic graphite samples by irradiation of H, C, and N ions in the mega-electron-volt energy range. The use of specially made sample holders for the magnetic measurements provided high reproducibility allowing us to obtain directly the irradiation effects without any corrections or subtractions. Our results show that three magnetic phenomena are triggered by the defects produced by the irradiation, namely, Curie-type paramagnetism, ferromagnetism and an anomalous paramagnetic state that appears as precursor of the magnetic ordered state. Using SRIM simulations to estimate the amount of vacancies produced by the irradiation, the Curie-type paramagnetic response indicates an effective Bohr magneton number per nominally produced vacancy p=0.27+-0.02mu{sub B}. Direct measurements of the surface sample temperature during irradiation and the decrease in the (as-received) paramagnetic as well as ferromagnetic contributions after irradiation indicate that self-heating is one of the causes for small yield of ferromagnetism. Taking into account the hydrogen distribution in the virgin samples, the obtained results indicate that the induced ferromagnetism appears when the average vacancy distance is {approx}2 nm in the near surface region.

Ramos, M. A.; Munoz-Martin, A.; Climent-Font, A. [CMAM and Instituto de Ciencia de Materiales 'Nicolas Cabrera', Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Barzola-Quiquia, J.; Esquinazi, P. [Division of Superconductivity and Magnetism, Institut fuer Experimentelle Physik II, Universitaet Leipzig, Linnestrasse 5, D-04103 Leipzig (Germany); Garcia-Hernandez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain)

2010-06-01

107

Ion Beams from Short Pulse Laser Irradiation for Fast Ignition  

NASA Astrophysics Data System (ADS)

The ePLAS implicit/hybrid code is being used to model fast ion generation for ignition in targets irradiated by short pulse lasers. The code calculates E&B-Fields by the implicit moment methodootnotetextR. J. Mason, JCP 71, 429 (1987) and R. J. Mason, PRL 96, 035001 (2006). and couples electrons to ions at corrected Spitzer rates with variable Z from the Sesame Tables. The moderate to low Z ions are modeled as either PIC particles or a fluid. Typical laser illumination is from 5 x 10^19 to 3 x 10^20W/cm^2 in 1-10 Picosecond pulses, 7 -- 40 ?m in diameter. We will discuss results for a variety of illumination schemes and tuning options to focus and collect the ions, including the use of multiple shells and beams.

Kirkpatrick, R. C.; Mason, R. J.; Faehl, R. J.

2011-11-01

108

He ion irradiation damage to Al/Nb multilayers  

SciTech Connect

We investigated the evolution of microstructure and mechanical properties of sputter-deposited Al/Nb multilayers with individual layer thickness, h, of 1-200 nm, subjected to helium ion irradiations: 100 keV He{sup +} ions with a dose of 6 x 10{sup 16}/cm{sup 2}. Helium bubbles, 1-2 nm in diameter, were observed. When h is greater than 25 nm, hardnesses of irradiated multilayers barely change, whereas radiation hardening is more significant at smaller h. Transmission electron microscopy and scanning transmission electron microscopy studies reveal the formation of a thin layer of Nb{sub 3}Al intermetallic along the Al/Nb interface as a consequence of radiation induced intermixing. The dependence of radiation hardening on h is interpreted by using a composite model considering the formation of the hard Nb{sub 3}Al intermetallic layer.

Misra, Amit [Los Alamos National Laboratory; Li, Nan [TEXAS A& M; Martin, M S [TEXAS A& M; Anderoglu, Osman [TEXAS A& M; Shao, L [TEXAS A& M; Wang, H [TEXAS A& M; Zhang, X [TEXAS A& M

2009-01-01

109

(Grain boundary and interface kinetics during ion irradiation)  

SciTech Connect

Proposed here is renewed support of a research program focused on interface motion and phase transformation during ion irradiation, with emphasis on elemental semiconductors. Broadly speaking, the aims of this program are to explore defect kinetics in amorphous and crystalline semiconductors, and to relate defect dynamics to interface motion and phase transformations. Over the last three years, we initiated a program under DOE support to explore crystallization and amorphization of elemental semiconductors under irradiation. This research has enabled new insights about the nature of defects in amorphous semiconductors and about microstructural evolution in the early stages of crystallization. In addition, we have demonstrated almost arbitrary control over the relative rates of crystal nucleation and crystal growth in silicon. As a result, the impinged grain microstructure of thin (100 nm) polycrystalline films crystallized under irradiation can be controlled with grain sizes ranging from a few nanometers to several micrometers, which may have interesting technological implications.

Atwater, H.A.

1991-01-01

110

[Grain boundary and interface kinetics during ion irradiation  

SciTech Connect

Proposed here is renewed support of a research program focused on interface motion and phase transformation during ion irradiation, with emphasis on elemental semiconductors. Broadly speaking, the aims of this program are to explore defect kinetics in amorphous and crystalline semiconductors, and to relate defect dynamics to interface motion and phase transformations. Over the last three years, we initiated a program under DOE support to explore crystallization and amorphization of elemental semiconductors under irradiation. This research has enabled new insights about the nature of defects in amorphous semiconductors and about microstructural evolution in the early stages of crystallization. In addition, we have demonstrated almost arbitrary control over the relative rates of crystal nucleation and crystal growth in silicon. As a result, the impinged grain microstructure of thin (100 nm) polycrystalline films crystallized under irradiation can be controlled with grain sizes ranging from a few nanometers to several micrometers, which may have interesting technological implications.

Atwater, H.A.

1991-12-31

111

Ion irradiation induced structural and electrical transition in graphene  

SciTech Connect

The relationship between the electrical properties and structure evolution of single layer graphene was studied by gradually introducing the gallium ion irradiation. Raman spectrums show a structural transition from nano-crystalline graphene to amorphous carbon as escalating the degree of disorder of the graphene sample, which is in correspondence with the electrical transition from a Boltzmann diffusion transport to a carrier hopping transport. The results show a controllable method to tune the properties of graphene.

Zhou Yangbo; Wang Yifan; Xu Jun; Fu Qiang; Wu Xiaosong; Yu Dapeng [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Liao Zhimin [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, Dublin 2 (Ireland); Duesberg, Georg S. [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, Dublin 2 (Ireland); School of Chemistry, Trinity College, Dublin 2 (Ireland)

2010-12-21

112

Respiratory gated irradiation system for heavy-ion radiotherapy  

Microsoft Academic Search

Purpose: In order to reduce the treatment margin of the moving target due to breathing, we developed a gated irradiation system for heavy-ion radiotherapy.Methods and Materials: The motion of a patient due to respiration is detected by the motion of the body surface around the chest wall. A respiratory sensor was developed using an infrared light spot and a position-sensitive

Shinichi Minohara; Tatsuaki Kanai; Masahiro Endo; Kouji Noda; Mitsutaka Kanazawa

2000-01-01

113

Track structure in DNA irradiated with heavy ions.  

PubMed

The spatial properties of trapped radicals produced in heavy-ion-irradiated solid DNA at 77 K have been probed using pulsed electron paramagnetic double resonance (PELDOR or DEER) techniques. Salmon testes DNA hydrated to 12 water molecules per nucleotide was irradiated with 40Ar ions of energy 100 MeV/nucleon and LET ranging from 300 to 400 keV/microm. Irradiated samples were maintained at cryogenic temperature at all times. PELDOR measurements were made using a refocused echo detection sequence that allows dipolar interaction between trapped radicals to be observed. The EPR spectrum is attributed to electron loss/gain DNA base radicals and neutral carbon-centered radicals that likely arise from sugar damage. We find a radical concentration of 13.5 x 10(18) cm(-3) in the tracks and a track radius of 6.79 nm. The cross section of these tracks is 144 nm2, yielding a lineal radical density of 2.6 radicals/nm. Based on the yields determined previously for particles having calculated LET values of 300-400 keV/microm and our measured lineal density, we obtain an LET of 270 keV/microm, which is in good agreement with the calculated range of values. These measurements of radical density and spatial extent provide the first direct experimental determination of track characteristics in irradiated DNA. PMID:15799701

Bowman, Michael K; Becker, David; Sevilla, Michael D; Zimbrick, John D

2005-04-01

114

Synthesis of embedded Au nanostructures by ion irradiation: influence of ion induced viscous flow and sputtering  

PubMed Central

Summary The ion-irradiation induced synthesis of embedded Au nanoparticles (NPs) into glass from islands of Au on a glass substrate is studied in the context of recoiling atoms, sputtering and viscous flow. Cross sectional transmission electron microscopy studies revealed the formation of Au NPs embedded in the glass substrates by the 50 keV Si? ion irradiation of irregularly shaped Au nanostructures on the glass surfaces at a fluence of 3 × 1016 ions/cm2. The depth profiles of Au in the samples were obtained from high-resolution Rutherford backscattering spectrometry studies. The results from TRIDYN simulation reveal the role of various ion-induced processes during the synthesis of the embedded Au NPs, viz. sputtering and recoiling atoms. Simulation and experimental results suggest that the viscous flow is one of the major factors that are responsible for the embedding of Au nanoparticles into the glass substrate. PMID:24605276

Agarwal, D C; Khan, S A; Mohapatra, S; Amekura, H; Datta, D P; Kumar, Ajay; Choudhury, R K; Chan, T K; Osipowicz, Thomas; Avasthi, D K

2014-01-01

115

Simulations of Xe and U diffusion in UO2  

SciTech Connect

Diffusion of xenon (Xe) and uranium (U) in UO{sub 2} is controlled by vacancy mechanisms and under irradiation the formation of mobile vacancy clusters is important. Based on the vacancy and cluster diffusion mechanisms established from density functional theory (DFT) calculations, we derive continuum thermodynamic and diffusion models for Xe and U in UO{sub 2}. In order to capture the effects of irradiation, vacancies (Va) are explicitly coupled to the Xe and U dynamics. Segregation of defects to grain boundaries in UO{sub 2} is described by combining the bulk diffusion model with models of the interaction between Xe atoms and vacancies with grain boundaries, which were derived from atomistic calculations. The diffusion and segregation models were implemented in the MOOSE-Bison-Marmot (MBM) finite element (FEM) framework and the Xe/U redistribution was simulated for a few simple microstructures.

Andersson, Anders D. [Los Alamos National Laboratory; Vyas, Shyam [Los Alamos National Laboratory; Tonks, Michael R. [Idaho National Laboratory; Casillas, Luis [Los Alamos National Laboratory; Uberuaga, Blas P. [Los Alamos National Laboratory; Millett, Paul [Idaho National Laboratory

2012-09-10

116

Diamond-like carbon sputtering by laser produced Xe plasma  

NASA Astrophysics Data System (ADS)

The sputtering of diamond-like carbon (DLC) was investigated using Xe ion bombardment from the laser plasma X-ray source (LPX). The LPX we developed uses a solid Xe target and emits UV-X-rays and Xe ions. Using the LPX as an ion source, we measured etching depths of DLC, Ru, and Au films using a quartz crystal microbalance (QCM) to determine their ion sputtering rates at incident angles of 0° and 70°. The calculated results by the SRIM code were able to predict the measured results, except for the case of the DLC film at 0° incident. Our measured result indicated that the DLC sputtering at 0° was ten times larger than previously reported data, in which an ion gun was used. We consider that the difference was a characteristic effect of the laser plasma, and can be explained as a synergistic effect of ion bombardment and UV radiation from the Xe plasma.

Amano, Sho; Inoue, Tomoaki

2013-11-01

117

Characterization of polymeric films subjected to lithium ion beam irradiation  

SciTech Connect

Two different polymeric materials that are candidate materials for use as binders for mixed uranium–plutonium oxide nuclear fuel pellets were subjected to Li ion beam irradiation, in order to simulate intense alpha irradiation. The materials (a polyethylene glycol 8000 and a microcrystalline wax) were then analyzed using a combination of mass spectrometry (MS) approaches and X-ray photoelectron spectroscopy (XPS). Samples of the irradiated PEG materials were dissolved in H2O and then analyzed using electrospray ionization-MS, which showed the formation of a series of small oligomers in addition to intact large PEG oligomers. The small oligomers were likely formed by radiation-induced homolytic scissions of the C–O and C–C bonds, which furnish radical intermediates that react by radical recombination with Hradical dot and OHradical dot. Surface analysis using SIMS revealed a heterogeneous surface that contained not only PEG-derived polymers, but also hydrocarbon-based entities that are likely surface contaminants. XPS of the irradiated PEG samples indicated the emergence of different carbon species, with peak shifts suggesting the presence of sp2 carbon atoms. Analysis of the paraffinic film using XPS showed the emergence of oxygen on the surface of the sample, and also a broadening and shifting of the C1s peak, demonstrating a change in the chemistry on the surface. The paraffinic film did not dissolve in either H2O or a H2O–methanol solution, and hence the bulk of the material could not be analyzed using electrospray. However a series of oligomers was leached from the bulk material that produced ion series in the ESI-MS analyses that were identified octylphenyl ethoxylate oligomers. Upon Li ion bombardment, these shifted to a lower average molecular weight, but more importantly showed the emergence of three new ion series that are being formed as a result of radiation damage. Surface analysis of the paraffinic polymers using SIMS produced spectra that were wholly dominated by hydrocarbon ion series, and no difference was observed between unirradiated and irradiated samples. The studies demonstrate that for the PEG-based polymers, direct evidence for radiolytic scission can be observed using ESI-MS, and suggests that both radiolytic pathways and efficiencies as a function of dose should be measurable by calibrating instrument response to the small oligomeric degradation products.

Gary S. Groenewold; W. Roger Cannon; Paul A. Lessing; Recep Avci; Muhammedin Deliorman; Mark Wolfenden; Doug W. Akers; J. Keith Jewell

2013-02-01

118

Ion irradiation damage in ilmenite at 100 K  

USGS Publications Warehouse

A natural single crystal of ilmenite (FeTiO3) was irradiated at 100 K with 200 keV Ar2+. Rutherford backscattering spectroscopy and ion channeling with 2 MeV He+ ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 ?? 1015 Ar2+/cm2, considerable near-surface He+ ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 nm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO3) and spinel (MgAl2O4) to explore factors that may influence radiation damage response in oxides.

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A.; Nord, G.L., Jr.

1997-01-01

119

Ion irradiation damage in ilmenite at 100 K  

SciTech Connect

A natural single crystal of ilmenite (FeTiO{sub 3}) was irradiated at 100 K with 200 keV Ar{sup 2+}. Rutherford backscattering spectroscopy and ion channeling with MeV He{sup +} ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 {times} 10{sup 15} Ar{sup 2+} cm{sup {minus}2}, considerable near-surface He{sup +} ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 nm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO{sub 3}) and spinel (MgAl{sub 2}O{sub 4}) to explore factors that may influence radiation damage response in oxides.

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Nord, G.L. Jr. [Geological Survey, Reston, VA (United States)

1997-10-01

120

Ion irradiation damage in ilmenite under cryogenic conditions  

SciTech Connect

A natural single crystal of ilmenite was irradiated at 100 K with 200 keV Ar{sup 2+}. Rutherford backscattering spectroscopy and ion channeling with 2 MeV He{sup +} ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 {times} 10{sup 15} Ar{sup 2+} cm{sup {minus}2}, considerable near-surface He{sup +} ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 mm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO{sub 3}) and spinel (MgAl{sub 2}O{sub 4}) to explore factors that may influence radiation damage response in oxides.

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Nord, G.L. Jr. [Geological Survey, Reston, VA (United States)

1996-11-01

121

Origins of ion irradiation-induced Ga nanoparticle motion on GaAs surfaces  

SciTech Connect

We have examined the origins of ion irradiation-induced nanoparticle (NP) motion. Focused-ion-beam irradiation of GaAs surfaces induces random walks of Ga NPs, which are biased in the direction opposite to that of ion beam scanning. Although the instantaneous NP velocities are constant, the NP drift velocities are dependent on the off-normal irradiation angle, likely due to a difference in surface non-stoichiometry induced by the irradiation angle dependence of the sputtering yield. It is hypothesized that the random walks are initiated by ion irradiation-induced thermal fluctuations, with biasing driven by anisotropic mass transport.

Kang, M.; Wu, J. H.; Chen, H. Y.; Thornton, K.; Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Sofferman, D. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Adelphi University, Garden City, New York 11530-0701 (United States); Beskin, I. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2013-08-12

122

R&D Toward Future Liquid Xe Double Beta Detectors  

NASA Astrophysics Data System (ADS)

We report on several R&D projects aimed at possible future ton-scale Xe detectors for 0nuBB searches. A liquid Xe cell is being developed to measure material reflectivity for Xe scintillation light in liquid Xe, knowledge of which will be important for detector design and optimization. A vacuum test chamber, equipped with with cryogenic cooling and sources of VUV light, is being commissioned for candidate scintillation detectors. Finally, 136Cs, produced by 136Xe(p,n) at an accelerator, is being pursed as a source of Ba+ ions useful to ongoing R&D toward extraction and identification of the double beta decay daughter in ^136Xe.

Daniels, Tim; Bonatt, Joshua; Kumar, Krishna; Lodato, Mark; Mackeen, Cameron; Malone, Kelly; Pocar, Andrea; Wright, David

2012-10-01

123

Microstructure of RERTR DU-Alloys Irradiated with Krypton Ions  

SciTech Connect

Fuel development for reduced enrichment research and test reactor (RERTR) program is tasked with the development of new low enrichment uranium fuels that can be employed to replace existing high enrichment uranium fuels currently used in many research and test reactors worldwide. Radiation stability of the interaction product formed at fuel-matrix interface has a strong impact on fuel performance. Three depleted uranium alloys are cast that consist of the following 5 phases of interest to be investigated: U(Si,Al)3, (U,Mo)(Si,Al)3, UMo2Al20, U6Mo4Al43 and UAl4. Irradiation of TEM disc samples with 500 keV Kr ions at 200?C to high doses up to ~100 dpa were conducted using an intermediate voltage electron microscope equipped with an ion accelerator. The irradiated microstructure of the 5 phases is characterized using transmission electron microscopy. The results will be presented and the implication of the observed irradiated microstructure on the fuel performance will be discussed.

J. Gan; D. Keiser; D. Wachs; B. Miller; T. Allen; M. Kirk; J. Rest

2009-11-01

124

Heavy ion irradiation effects of brannerite-type ceramics  

NASA Astrophysics Data System (ADS)

Brannerite, UTi 2O 6, occurs in polyphase Ti-based, crystalline ceramics that are under development for plutonium immobilization. In order to investigate radiation effects caused by ?-decay events of Pu, a 1 MeV Kr + irradiation on UTi 2O 6, ThTi 2O 6, CeTi 2O 6 and a more complex material, composed of Ca-containing brannerite and pyrochlore, was performed over a temperature range of 25-1020 K. The ion irradiation-induced crystalline-to-amorphous transformation was observed in all brannerite samples. The critical amorphization temperatures of the different brannerite compositions are: 970 K, UTi 2O 6; 990 K, ThTi 2O 6; 1020 K, CeTi 2O 6. The systematic increase in radiation resistance from Ce-, Th- to U-brannerite is related to the difference of mean atomic mass of A-site cation in the structure. As compared with the pyrochlore structure-type, brannerite phases are more susceptible to ion irradiation-induced amorphization. The effects of structure and chemical compositions on radiation resistance of brannerite-type and pyrochlore-type ceramics are discussed.

Lian, J.; Wang, L. M.; Lumpkin, G. R.; Ewing, R. C.

2002-05-01

125

Formation of ion-irradiation-induced atomic-scale defects on walls of carbon nanotubes  

Microsoft Academic Search

Recent experiments on irradiated carbon nanotubes provide evidence that ion bombardment gives rise to nanotube amorphization and dramatic dimensional changes. Using an empirical potential along with molecular dynamics, we study structure and formation probabilities of atomic-scale defects produced by low-dose irradiation of nanotubes with Ar ions. For this, we simulate impact events over a wide energy range of incident ions.

A. V. Krasheninnikov; K. Nordlund; M. Sirviö; E. Salonen; J. Keinonen

2001-01-01

126

Double beta decay searches of Xe-134, Xe-126 and Xe-124 with large scale Xe detectors  

E-print Network

The sensitivity for double beta decay studies of Xe-134 and Xe-124 is investigated assuming a potential large scale Xe experiment developed for dark matter searches depleted in Xe-136. The opportunity for an observation of the 2nu double beta decay of Xe-134 is explored for various scenarios. A positive observation should be possible for all calculated nuclear matrix elements. The detection of 2$\

N. Barros; J. Thurn; K. Zuber

2014-09-29

127

Double beta decay searches of Xe-134, Xe-126 and Xe-124 with large scale Xe detectors  

E-print Network

The sensitivity for double beta decay studies of Xe-134 and Xe-124 is investigated assuming a potential large scale Xe experiment developed for dark matter searches depleted in Xe-136. The opportunity for an observation of the 2nu double beta decay of Xe-134 is explored for various scenarios. A positive observation should be possible for all calculated nuclear matrix elements. The detection of 2$\

Barros, N; Zuber, K

2014-01-01

128

Effect of swift heavy ion-irradiation on Cr/Fe/Ni multilayers  

NASA Astrophysics Data System (ADS)

A multilayer film having overall composition Fe 50Cr 25Ni 25, was irradiated successively by 80 MeV Si ions and Ag ions of 150 and 200 MeV energy. The energy deposited in the multilayer in the form of electronic excitations results in significant modification at the interfaces. The interfacial roughness increases in the system after the irradiations as revealed by X-ray reflectivity measurement. Mössbauer measurements provide evidence of intermixing after the irradiation by 200 MeV Ag ions. Comparison of heavy ion irradiated multilayer has been done with annealed and low energy ion irradiated samples. Results suggest that the phases formed at the interfaces of iron as a result of electronic energy loss are similar to those in the cases of thermal diffusion and keV energy ion beam irradiation.

Gupta, Ratnesh; Gupta, Ajay; Avasthi, D. K.; Principi, G.; Tosello, C.

129

Detection of high-energy heavy ions using piezoelectric lead zirconate titanate  

SciTech Connect

The characteristics of a radiation detector fabricated with stacks of piezoelectric lead zirconate titanate (PZT) elements were studied by irradiating it with a 400 MeV/n xenon (Xe) beam for various beam pulse durations. This detector is referred to as the multilayered detector (MD). To understand the production mechanism behind the output voltage obtained from the MD, measurement of the spatial distribution of the output signals generated in the MD was attempted. It was found that the amplitude observed was dependent on the number of Xe ions per unit time and the amount of ionization loss energy of Xe ions in PZT.

Takechi, Seiji; Morinaga, Shin-ya; Kurozumi, Atsuma [Graduate School of Engineering, Osaka City University, Osaka 558-8585 (Japan); Miyachi, Takashi; Fujii, Masayuki; Hasebe, Nobuyuki [Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Shibata, Hiromi [Graduate School of Engineering, Kyoto University, Kyoto 606-8501 (Japan); Murakami, Takeshi; Uchihori, Yukio [National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Okada, Nagaya [Honda Electronics Co., Ltd., Aichi 441-3193 (Japan)

2009-04-15

130

Detection of high-energy heavy ions using piezoelectric lead zirconate titanate  

NASA Astrophysics Data System (ADS)

The characteristics of a radiation detector fabricated with stacks of piezoelectric lead zirconate titanate (PZT) elements were studied by irradiating it with a 400 MeV/n xenon (Xe) beam for various beam pulse durations. This detector is referred to as the multilayered detector (MD). To understand the production mechanism behind the output voltage obtained from the MD, measurement of the spatial distribution of the output signals generated in the MD was attempted. It was found that the amplitude observed was dependent on the number of Xe ions per unit time and the amount of ionization loss energy of Xe ions in PZT.

Takechi, Seiji; Morinaga, Shin-ya; Kurozumi, Atsuma; Miyachi, Takashi; Fujii, Masayuki; Hasebe, Nobuyuki; Shibata, Hiromi; Murakami, Takeshi; Uchihori, Yukio; Okada, Nagaya

2009-04-01

131

Helium release and amorphization resistance in ion irradiated nanochannel films  

NASA Astrophysics Data System (ADS)

Volumetric swelling, surface blistering, exfoliation and embrittlement partially induced by the aggregation of gas bubbles are serious problems for materials in nuclear reactors. This letter demonstrates that the “vein-like” nanochannel films possess greater He management capability and radiation tolerance. For a given fluence, the He bubble size in the nanochannel film decreases with increasing the nanochannel density. For a given nanochannel density, the bubble size increases with increasing fluence initially but levels off to a maximum value of 0.8 nm after the ion fluence reaches 2\\times10^{17}\\ \\text{ions/cm}^{2} , corresponding to He release ratio of 79% in the irradiated CrN RT films. The abundant surfaces in the nanochannel films are perfect defect sinks and thereby large sized He bubbles and supersaturated defects are less likely to be developed in these high radiation tolerant materials.

Hong, Mengqing; Wang, Yongqiang; Ren, Feng; Zhang, Hongxiu; Fu, Dejun; Yang, Bing; Xiao, Xiangheng; Jiang, Changzhong

2014-04-01

132

Behavior of nuclear materials irradiated with a dual ion beam  

NASA Astrophysics Data System (ADS)

Synergistic effects of nuclear (Sn) and electronic (Se) energy losses are investigated by comparing the damage accumulated in selected oxide (c-ZrO2, MgO, Gd2Ti2O7) and carbide (SiC) single crystals irradiated with single and dual low and high energy ion beams. Channeling results show that the Sn/Se synergy induces a strong decrease of the damage in MgO and SiC (where amorphization is prevented) and almost no effects in c-ZrO2 and Gd2Ti2O7. Raman and TEM results confirm this statement. The healing of defects generated by nuclear collisions in MgO and SiC is due to the electronic excitation produced in the wake of swift ions. These results present a strong interest for technological applications in the nuclear industry where expected cooperative Sn/Se effects may preserve the integrity of nuclear materials.

Thomé, Lionel; Veli?a, Gihan; Debelle, Aurélien; Miro, Sandrine; Garrido, Frédérico; Trocellier, Patrick; Serruys, Yves

2014-05-01

133

Ion beam irradiation effects in strontium zirconium phosphate with NZP-structure type  

NASA Astrophysics Data System (ADS)

Ceramics with the sodium zirconium phosphate or NZP type structure have potential as nuclear waste form and inert matrix materials. For both applications the material will be subjected to self-radiation damage from ?-decay of the incorporated actinides. In this study, ion-beam irradiation using Au- and He-ions has been used to simulate the consequences of ?-decay and the effects of irradiation on the structural and macroscopic properties (density and hardness) have been investigated. Irradiation by Au-ions resulted in a significant volume contraction of ˜7%, a reduction in hardness of ˜30% and a loss in long-range order at fluences above 1014 Au-ions/cm2. In contrast, little effect on the material properties was noted for samples irradiated with He-ions up to a fluence of 1017 ions/cm2. Thermal annealing was investigated for the highest fluence Au-ion irradiated sample and significant decomposition was observed.

Gregg, Daniel J.; Karatchevtseva, Inna; Thorogood, Gordon J.; Davis, Joel; Bell, Benjamin D. C.; Jackson, Matthew; Dayal, Pranesh; Ionescu, Mihail; Triani, Gerry; Short, Ken; Lumpkin, Gregory R.; Vance, Eric R.

2014-03-01

134

The discrepancies in multistep damage evolution of yttria-stabilized zirconia irradiated with different ions  

SciTech Connect

This paper reports a comprehensive investigation of structural damage in yttria-stabilized zirconia irradiated with different ions over a wide fluence range. A similar multistep damage accumulation exists for the irradiations of different ions, but the critical doses for occurrence of second damage step, characterized by a faster increase in damage fraction, and the maximum elastic strain at the first damage step are varied and depend on ion mass. For irradiations of heavier ions, the second damage step occurs at a higher dose with a lower critical elastic strain. Furthermore, larger extended defects were observed in the irradiations of heavy ions at the second damage step. Associated with other experiment results and multistep damage accumulation model, the distinct discrepancies in the damage buildup under irradiations of different ions were interpreted by the effects of electronic excitation, energy of primary knock-on atom and chemistry contributions of deposited ions.

Yang, Tengfei [Peking University; Taylor, Caitlin A. [University of Tennessee, Knoxville (UTK); Kong, Shuyan [Peking University; Wang, Chenxu [Peking University; Zhang, Yanwen [ORNL; Huang, Xuejun [Peking University; Xue, Jianming [Peking University; Yan, Sha [Peking University; Wang, Yugang [Peking University

2013-01-01

135

Double beta decay searches of 134Xe, 126Xe and 124Xe with large scale Xe detectors  

NASA Astrophysics Data System (ADS)

The sensitivity for double beta decay studies of 134Xe and 124Xe is investigated assuming a potential large scale Xe experiment developed for dark matter searches depleted in 136Xe. The opportunity for an observation of the 2??? - decay of 134Xe is explored for various scenarios. A positive observation should be possible for all calculated nuclear matrix elements. The detection of 2? ECEC of 124Xe can be probed in all scenarios covering the theoretical predicted half-life uncertainties and a potential search for 126Xe is discussed. The sensitivity to {{? }+}EC decay of 124Xe is discussed and a positive observation might be possible, while {{? }+}{{? }+} decay still remains unobservable. The performed studies take into account solar pp–neutrino interactions, 85Kr beta decay and remaining 136Xe double beta decay as background components in the depleted detector.

Barros, N.; Thurn, J.; Zuber, K.

2014-11-01

136

Irradiation effect of different heavy ions and track section on the silkworm Bombyx mori  

NASA Astrophysics Data System (ADS)

In order to compare the irradiation effects of different ions, wandering larvae were whole-body exposed or locally irradiated with 50-MeV 4He 2+, 220-MeV 12C 5+, and 350-MeV 20Ne 8+ ions, respectively. For the whole-body-exposed individuals, the survival rates at the cocooning, pupation, and emergence stages all decreased as dose increased, and a range-dependent difference was clearly observed. For local irradiation of ovaries, irradiation effects depend very strongly on the projectile range. In the case of local irradiation of dermal cells by different track sections of heavy ions, the closer the target was to the high-LET section of the track, the more pronounced were the radiation effects. These results indicated that by selectively using ion species and adjusting the irradiation depth to the target, heavy-ion radiosurgery on particular tissues or organs of small experimental animals can be performed more accurately.

Tu, Zhen-Li; Kobayashi, Yasuhiko; Kiguchi, Kenji; Watanabe, Hiroshi

2003-05-01

137

Long-term reliability degradation of ultrathin dielectric films due to heavy-ion irradiation  

Microsoft Academic Search

High-energy ion-irradiated 3.3-nm oxynitride film and 2.2-nm SiO2-film MOS capacitors show premature breakdown during subsequent electrical stress. This degradation in breakdown increases with increasing ion linear energy transfer (LET), increasing ion fluence, and decreasing oxide thickness. The reliability degradation due to high-energy ion-induced latent defects is explained by a simple percolation model of conduction through SiO2 layers with irradiation and\\/or

B. K. Choi; D. M. Fleetwood; R. D. Schrimpf; Lloyd W. Massengill; K. F. Galloway; M. R. Shaneyfelt; T. L. Meisenfieimer; P. E. Dodd; J. R. Schwank; Y. M. Lee; R. S. John; G. Lucovsky

2002-01-01

138

Modifications of optical properties of PC/ABS by dual ions beam irradiation  

NASA Astrophysics Data System (ADS)

Polycarbonate (PC)/acrylonitrile butadien styrene (ABS) blends used in the inner parts of automobiles require a glossy and metallic colored optical property. Such a surface can be produced by ion beam irradiation, but the surface treated by a single ion species irradiation tends to be degraded upon a long term exposure under UV and visible lights, which includes the loss of glossiness and the delamination of the irradiated layer. Such degradations can be prevented or greatly reduced by a combined irradiation of heavy and light ions such as N and He ions. This may be attributable to a graded interface between the irradiation affected layer and the base materials by overlapping penetration depths of the heavy and light ions. This work is motivated by an effort to substitute the conventional Cr plating process with the ion beam process in the automobile industry.

Park, Jae-Won; Lee, Jae-Sang; Lee, Byung-hoon; Kim, Min-kyu; Moon, Byung-Sik; Lee, Chan-Young; Choi, Byung-Ho

2013-03-01

139

Regrowth of heavy-ion implantation damage by electron beams  

Microsoft Academic Search

Electron transparent Si, Ge and GaP samples were implanted with 50keV Xe+ ions to a dose around 1011ions\\/cm2. At this implantation condition, each heavy ion created a small, spatially isolated amorphous zone. Following the ion implantation, the samples were irradiated with electrons having energies from 25 to 300keV at temperatures 90 and 300K. At each electron energy, transmission electron microscopy

I. Jencic; I. M. Robertson

2000-01-01

140

J. Phys. Chem. 1995, 99, 2459-2468 2459 Dynamics of Xe Atoms in NaA Zeolites and the 129XeChemical Shift  

E-print Network

, and chromatography. Due to the combination of their inertness and environmental sensitivity of their NMR spectra, lZ9 try to understand the experimental lZ9XeNMR spectra of zeolite NaA, namely, the Xe chemical shifts. NaA zeolite a cavity. The vertices are positions of aluminum ions, and oxygen ions are approximately

Berry, R. Stephen

141

Surface pattern formation during MeV energy ion beam irradiation  

SciTech Connect

Surface patterning during high energy heavy ion irradiation is a relatively recent observation. We report in this paper the results of a study on the formation of self organized ripple patterns on silica surface irradiated with MeV energy gold ions.

Srivastava, S. K.; Nair, K. G. M.; Kannan, R. Kamala; Kamruddin, M.; Panigrahi, B. K.; Tyagi, A. K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

2012-06-05

142

Carbon nanotubes as masks against ion irradiation: An insight from atomistic simulations  

E-print Network

The key idea is illustrated in Fig. 1. Because car- bon nanotubes are micrometer-long and nanometer-wide that carbon nanotubes can be used as masks against ion irradiation to make metallic nanowires of a few and simulate ion irradiation of multiwalled nanotubes. We derive an equation which for a given nanowire

Krasheninnikov, Arkady V.

143

Microstructural changes induced by low energy heavy ion irradiation in titanium silicon carbide  

E-print Network

Microstructural changes induced by low energy heavy ion irradiation in titanium silicon carbide CNRS 6622, Parc Valrose, 06108 Nice cedex 2, France ABSTRACT Low energy ion irradiation was used, 25.75.Ag, 28.41.Bm, 68.37.Ps, 61.05.J- 1. Introduction The Gas-cooled Fast Reactor (GFR) is one

Boyer, Edmond

144

X-ray photoelectron spectroscopy analysis of organic materials irradiated with gas cluster ion beam  

SciTech Connect

Irradiation effect of gas cluster ion beams (GCIB) on organic materials were studied with X-ray photoelectron spectroscopy by comparison to that with Ar-monomer ions. In the case of polyimide, the intensity of both N-C = O and -C-O- bond decreased with 500 eV Ar monomer ion irradiation. On the other hand, there was no significant change in the XPS spectra after Ar-GCIB irradiation. From the size-selected GCIB irradiation study, the damages in polyimide decreased with increasing the cluster size owing to the reduction of energy per atoms.

Nakagiri, Motohiro; Toyoda, Noriaki; Yamada, Isao [Incubation center, Graduate school of engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo, 671-2280 (Japan)

2011-01-07

145

MASS DISTRIBUTION OF FISSION PRODUCTS PRODUCED BY IRRADIATION OF GOLD AND URANIUM BY NITROGEN IONS  

Microsoft Academic Search

The mass spectrum of fission fragments produced by irradiating thick ; targets of gold and uranium with 115 Mev nitrogen ions was investigated. ; Fourteen different elements were separated from the irradiated targets. The mass ; distribution curve for fission fragments produced by irradiating gold has the ; form of a narrow peak with a haif width of about 20

N. I. Tarantin; Yu. B. Gerlit; L. I. Guseva; B. F. Myasoedov; Fillippova; G. N. K. V. f Flerov

1958-01-01

146

Behavior of Crystalline Xe Nanoprecipitates during Coalescence  

Microsoft Academic Search

In situ high-resolution electron microscopy has been used to observe nanoprecipitates of crystalline Xe in faceted cavities in Al during coalescence induced by 1.0 MeV electron irradiation at 300 K. Atomic-level fluctuations of cavity facets result in shape changes and precipitate motion leading to coalescence. There is no apparent elastic interaction between precipitates separated by as little as 0.5 nm.

R. C. Birtcher; S. E. Donnelly; M. Song; K. Furuya; K. Mitsuishi; C. W. Allen

1999-01-01

147

Ion-irradiation studies of cascade damage in metals  

SciTech Connect

Ion-irradiation studies of the fundamental aspects of cascade damage in metals are reviewed. The emphasis of these studies has been the determination of the primary state of damage (i.e. the arrangement of atoms in the cascade region prior to thermal migration of defects). Progress has been made towards understanding the damage function (i.e. the number of Frenkel pairs produced as a function of primary recoil atom energy), the spatial configuration of vacancies and interstitials in the cascade and the cascade-induced mixing of atoms. It is concluded for these studies that the agitation of the lattice in the vicinity of energetic displacement cascades stimulates the defect motion and that such thermal spike motion induces recombination and clustering of Frenkel defects. 9 figures.

Averback, R.S.

1982-03-01

148

Damage growth in Si during self-ion irradiation: A study of ion effects over an extended energy range  

Microsoft Academic Search

Damage nucleation\\/growth in single-crystal Si during ion irradiation is discussed. For MeV ions, the rate of growth as well as the damage morphology are shown to vary widely along the track of the ion. This is attributed to a change in the dominant, defect-related reactions as the ion penetrates the crystal. The nature of these reactions were elucidated by studying

O. W. Holland; M. K. El-Ghor; C. W. White

1989-01-01

149

Evolution of precipitate in nickel-base alloy 718 irradiated with argon ions at elevated temperature  

NASA Astrophysics Data System (ADS)

Alloy 718 is a nickel-base superalloy whose strength derives from ?'(Ni3(Al,Ti)) and ??(Ni3Nb) precipitates. The evolution of the precipitates in alloy 718 irradiated with argon ions at elevated temperature were examined via transmission electron microscopy. Selected-area electron diffraction indicated superlattice spots disappeared after argon ion irradiation, which showing that the ordered structure of the ?' and ?? precipitates became disordered. The size of the precipitates became smaller with the irradiation dose increasing at 290 °C.

Jin, Shuoxue; Luo, Fengfeng; Ma, Shuli; Chen, Jihong; Li, Tiecheng; Tang, Rui; Guo, Liping

2013-07-01

150

MeV single-ion beam irradiation of mammalian cells using the Surrey vertical nanobeam, compared with broad proton beam and X-ray irradiations  

NASA Astrophysics Data System (ADS)

As a part of a systematic study on mechanisms involved in physical cancer therapies, this work investigated response of mammalian cells to ultra-low-dose ion beam irradiation. The ion beam irradiation was performed using the recently completed nanobeam facility at the Surrey Ion Beam Centre. A scanning focused vertical ion nano-beam was applied to irradiate Chinese hamster V79 cells. The V79 cells were irradiated in two different beam modes, namely, focused single ion beam and defocused scanning broad ion beam of 3.8-MeV protons. The single ion beam was capable of irradiating a single cell with a precisely controlled number of the ions to extremely low doses. After irradiation and cell incubation, the number of surviving colonies as a function of the number of the irradiating ions was measured for the cell survival fraction curve. A lower survival for the single ion beam irradiation than that of the broad beam case implied the hypersensitivity and bystander effect. The ion-beam-induced cell survival curves were compared with that from 300-kV X-ray irradiation. Theoretical studies indicated that the cell death in single ion irradiation mainly occurred in the cell cycle phases of cell division and intervals between the cell division and the DNA replication. The success in the experiment demonstrated the Surrey vertical nanobeam successfully completed.

Prakrajang, K.; Jeynes, J. C. G.; Merchant, M. J.; Kirkby, K.; Kirkby, N.; Thopan, P.; Yu, L. D.

2013-07-01

151

Study on irradiation induced corrosion behavior in austenitic stainless steel using hydrogen-ion bombardment  

NASA Astrophysics Data System (ADS)

In order to study the basic factors in irradiation assisted stress corrosion cracking (IASCC) of austenitic steels, the effects of displacement damage on the corrosion behavior of type 304 stainless steel were investigated by means of an ion irradiation technique. Solution-annealed specimens was irradiated using 1 MeV protons to 0.1, 0.5 and 1.0 dpa at about 573, 673 and 773 K. Electrochemical potentiokinetic reactivation (EPR) testing was carried out before and after the ion irradiation to clarify the effects of irradiation on corrosion behavior. The specimens irradiated at 773 K showed clear etching at grain boundaries and relatively high reactivation ratio, however, the specimens irradiated at 573 and 673 K showed no clear grain boundary etching. It was suggested that the higher irradiation temperature enhanced the radiation induced segregation near grain boundaries.

Kondou, Keietsu; Hasegawa, Akira; Abe, Katsunori

2004-08-01

152

Ion Irradiation Damage in Zirconate and Titanate Ceramics for Pu Disposition  

SciTech Connect

In this paper, we discuss the effect of ion irradiation on pyrochlore-rich titanate and defect-fluorite zirconate ceramics designed for plutonium immobilisation. Samples, with Ce as an analogue for Pu, were made via oxide routes and consolidated by cold-pressing and sintering. Ion irradiation damage was carried out with 2 MeV Au2+ ions to a fluence of 5 ions nm-2 in the accelerator facilities within the Environmental Molecular Sciences Laboratory at Pacific Northwest National Laboratory. Irradiated and non-irradiated samples were examined by x-ray diffraction, scanning and transmission electron microscopy, x-ray photoelectron and infra-red spectroscopy, and spectroscopic ellipsometry. Samples underwent accelerated leach testing at pH 1.75 (nitric acid) at 90°C for 28 days. The zirconate samples were more ion-irradiation damage resistant than the titanate samples, showing little change after ion-irradiation whereas the titanate samples formed an amorphous surface layer ~ 500 nm thick. While all samples had high aqueous durability, the titanate leach rate was ~ 5 times that of the zirconate. The ion-irradiation increased the leach rate of the titanate without impurities by ~ 5 times. The difference in the leach rates between irradiated and unirradiated zirconate samples is small. However, the zirconates were less able to incorporate impurities than the titanate ceramics and required higher sintering temperatures, ~ 1500°C compared to 1350°C for the titanates.

Stewart, Martin W.; Begg, Bruce D.; Finnie, K.; Colella, Michael; Li, H.; McLeod, Terry; Smith, Katherine L.; Zhang, Zhaoming; Weber, William J.; Thevuthasan, Suntharampillai

2004-07-01

153

Superlattice-like stacking fault array in ion-irradiated GaN  

SciTech Connect

Controlling defects in crystalline solids is of technological importance for realizing desirable materials properties. Irradiation with energetic particles is useful for designing the spatial distribution and concentration of defects in materials. Here, we performed ion irradiation into hexagonal GaN with the wurtzite structure and demonstrated the spontaneous formation of superlattice-like stacking fault arrays. It was found that the modulation period can be controlled by irradiation conditions and post-irradiation heat treatments.

Ishimaru, Dr. Manabu [Osaka University; Usov, Igor Olegovich [ORNL; Zhang, Yanwen [ORNL; Weber, William J [ORNL

2012-01-01

154

Multivariate analysis of Ion Beam Induced Luminescence spectra of irradiated silver ion-exchanged silicate glasses.  

PubMed

A multivariate analysis is used for the identification of the spectral features in Ion Beam Induced Luminescence (IBIL) spectra of soda-lime silicate glasses doped with silver by Ag(+)-Na(+) ion exchange. Both Principal Component Analysis and multivariate analysis were used to characterize time-evolving IBIL spectra of Ag-doped glasses, by means of the identification of the number and of the wavelength positions of the main luminescent features and the study of their evolution during irradiation. This method helps to identify the spectral features of the samples spectra, even when partially overlapped or less intense. This analysis procedure does not require additional input such as the number of peaks. PMID:22571943

Valotto, Gabrio; Quaranta, Alberto; Cattaruzza, Elti; Gonella, Francesco; Rampazzo, Giancarlo

2012-09-01

155

Multivariate analysis of Ion Beam Induced Luminescence spectra of irradiated silver ion-exchanged silicate glasses  

NASA Astrophysics Data System (ADS)

A multivariate analysis is used for the identification of the spectral features in Ion Beam Induced Luminescence (IBIL) spectra of soda-lime silicate glasses doped with silver by Ag+-Na+ ion exchange. Both Principal Component Analysis and multivariate analysis were used to characterize time-evolving IBIL spectra of Ag-doped glasses, by means of the identification of the number and of the wavelength positions of the main luminescent features and the study of their evolution during irradiation. This method helps to identify the spectral features of the samples spectra, even when partially overlapped or less intense. This analysis procedure does not require additional input such as the number of peaks.

Valotto, Gabrio; Quaranta, Alberto; Cattaruzza, Elti; Gonella, Francesco; Rampazzo, Giancarlo

156

High-fluence hyperthermal ion irradiation of gallium nitride surfaces at elevated temperatures  

NASA Astrophysics Data System (ADS)

Wurtzitic GaN films deposited on 6H-SiC(0001) substrates by ion-beam assisted molecular-beam epitaxy were irradiated with hyperthermal nitrogen ions with different fluences at different substrate temperatures. In situ observations with reflection high energy electron diffraction showed that during the irradiation process the surface structure of the GaN films changed from two dimensional to three dimensional at elevated temperatures, but not at room temperature. Atomic force microscopy revealed an enhancement of nanometric holes and canyons upon the ion irradiation at higher temperatures. The roughness of the irradiated and heated GaN films was clearly increased by the ion irradiation in accordance with x-ray reflectivity measurements. A sole thermal decomposition of the films at the chosen temperatures could be excluded. The results are discussed taking into account temperature dependent sputtering and surface uphill adatom diffusion as a function of temperature.

Finzel, A.; Gerlach, J. W.; Lorbeer, J.; Frost, F.; Rauschenbach, B.

2014-10-01

157

Formation of ion-irradiation-induced atomic-scale defects on walls of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Recent experiments on irradiated carbon nanotubes provide evidence that ion bombardment gives rise to nanotube amorphization and dramatic dimensional changes. Using an empirical potential along with molecular dynamics, we study structure and formation probabilities of atomic-scale defects produced by low-dose irradiation of nanotubes with Ar ions. For this, we simulate impact events over a wide energy range of incident ions. We show that the maximum damage production occurs for a bombarding ion energy of about 600 eV, and that the most common defects produced at all energies are vacancies, which at low temperatures are metastable but long-lived defects. Employing the tight-binding Green's function technique, we also calculate scanning tunneling microscopy (STM) images of irradiated nanotubes. We demonstrate that irradiation-induced defects may be detected by STM and that isolated vacancies may look like bright spots in atomically resolved STM images of irradiated nanotubes.

Krasheninnikov, A. V.; Nordlund, K.; Sirviö, M.; Salonen, E.; Keinonen, J.

2001-06-01

158

Swift heavy ion irradiation acts as a size filter to Ag nanoparticles embedded in silica glass  

NASA Astrophysics Data System (ADS)

The swift heavy ion (SHI) irradiation using as a tool for the ion-beam-shaping technique has attracted much attention in recently years, which can transform spherical metal nanoparticles (Nps) to prolate spheroids, nanorods or nanowires, with the elongation along the beam direction. In the present paper, we show that SHI irradiation can also act as a size filter to Ag Nps embedded in silica glass. In experiment, Ag Nps were introduced into silica glass by Ag ion implantation. Subsequently, 73 MeV Ca ions were used to irradiate the samples contained Ag Nps to different fluences. The direction of incident ions is perpendicular to sample surface. The surface plasmon resonance (SPR) absorbance peak of Ag Nps shifts to short wavelength with increase of irradiation fluence, meanwhile, the full width at half maximum (FWHM) of SPR peak decreases with increase of irradiation fluence. The decrease of FWHM indicates the reduction of Ag Nps size dispersion. TEM results show that Ag Nps smaller than 2.0 nm dissolve during irradiation, only Ag Nps larger than 2.0 nm survive and distribute in a narrow region. High energy Ca ion irradiation seems to act as a size filter. From TEM micrographs the size dispersion of Ag Nps is reduced comparing with that before irradiation, which is consistent with optical results.

Yang, Yitao; Zhang, Chonghong; Song, Yin; Gou, Jie; Zhang, Liqing; Meng, Yancheng; Zhang, Hengqing; Ma, Yizhun

2013-08-01

159

Thermal stability of ion-irradiated InGaAs with subpicosecond carrier lifetime  

NASA Astrophysics Data System (ADS)

Due to its very short carrier lifetime and its absorption window in the 1550nm spectral range, ion-irradiated InGaAs is a material of choice for opto-electronic telecommunication systems. Ion irradiated-InGaAs is a well adapted material for realizing fast saturable absorbers and fast photoconductive antennas. However, to our knowledge, no detailed experimental study has been reported on the thermal stability of ion-irradiated InGaAs. Post-irradiation annealing of such a material is required to enhance opto-electrical response, and the thermal stability of irradiated devices. Moreover, the study of annealing kinetics provides useful information about the nature of defects and their initial distribution. The carrier lifetime, the mobility and the residual carrier concentration versus anneal in heavy(Au+) and light(H+) ion-irradiated InGaAs samples have been measured. The defect annealing kinetics observed in proton-irradiated samples is described well by a Frenkel pair recombination model, thereby indicating the dominance of isolated point defects. In contrast, the model is not adapted to describe the thermal behavior of Au+-irradiation-induced defects that are clusters of point defects as observed via Transmission Electronic Microscopy. A higher thermal stability for the components based on Au+-irradiated InGaAs than on H+-irradiated ones is then expected.

Mangeney, Juliette; Joulaud, Laurent; Lourtioz, Jean-Michel; Crozat, Paul; Patriarche, Gilles

2004-06-01

160

Swift heavy ions induced irradiation effects in monolayer graphene and highly oriented pyrolytic graphite  

NASA Astrophysics Data System (ADS)

Monolayer graphene and highly oriented pyrolytic graphite (HOPG) were irradiated by swift heavy ions (209Bi and 112Sn) with the fluence between 1011 and 1014 ions/cm2. Both pristine and irradiated samples were investigated by Raman spectroscopy. It was found that D and D? peaks appear after irradiation, which indicated the ion irradiation introduced damage both in the graphene and graphite lattice. Due to the special single atomic layer structure of graphene, the irradiation fluence threshold ?th of the D band of graphene is significantly lower (<1 × 1011 ions/cm2) than that (2.5 × 1012 ions/cm2) of HOPG. The larger defect density in graphene than in HOPG indicates that the monolayer graphene is much easier to be damaged than bulk graphite by swift heavy ions. Moreover, different defect types in graphene and HOPG were detected by the different values of ID/ID?. For the irradiation with the same electronic energy loss, the velocity effect was found in HOPG. However, in this experiment, the velocity effect was not observed in graphene samples irradiated by swift heavy ions.

Zeng, J.; Yao, H. J.; Zhang, S. X.; Zhai, P. F.; Duan, J. L.; Sun, Y. M.; Li, G. P.; Liu, J.

2014-07-01

161

Fragmentation of biomolecules using slow highly charged ions  

SciTech Connect

We present first results of biomolecular fragmentation studies with slow highly charged ions (HCI). A layer of the tripeptide RVA was deposited on gold targets and irradiated with slow (few 100 keV) ions, e.g. Xe{sup 50+} and Xe{sup 15+}, extracted from the LLNL EBIT (electron beam ion trap). The secondary ions released upon ion impact were mass analyzed via Time-Of-Flight Secondary-Ion-Mass-Spectrometry (TOF-SIMS). The results show a strong dependence of the positive and negative ion yields on the charge state of the incident ion. We also found that incident ions with high charge states cause the ejection of fragments with a wide mass range as well as the intact molecule (345 amu). The underlying mechanisms are not yet understood but electron depletion of the target due to the high incident charge is likely to cause a variety of fragmentation processes. 6 refs., 2 figs.

Ruehlicke, C.; Schneider, D.; Balhorn, R. [Lawrence Livermore National Lab., CA (United States); DuBois, R. [Missouri Univ., Rolla, MO (United States). Dept. of Physics

1996-11-01

162

The JANNUS Saclay facility: A new platform for materials irradiation, implantation and ion beam analysis  

NASA Astrophysics Data System (ADS)

The third accelerator of the multi-ion irradiation platform JANNUS (Joint Accelerators for Nanosciences and NUclear Simulation), a 6SDH-2 Pelletron from National Electrostatic Corporation, Middleton was installed at Saclay in October 2009. The first triple beam irradiation combining Fe, He and H ion beams has been performed in March 2010. In the first part of this paper, we give a technical description of the triple beam facility, its performances and experimental capabilities. Typically, damage dose up to 100 dpa can be reached in 10 h irradiation with heavy ion beams, with or without simultaneous bombardment by protons, helium-4 ions or any other heavy ion beam. In the second part of this paper, we illustrate some IBA results obtained after irradiation and implantation experiments.

Pellegrino, S.; Trocellier, P.; Miro, S.; Serruys, Y.; Bordas, É.; Martin, H.; Chaâbane, N.; Vaubaillon, S.; Gallien, J. P.; Beck, L.

2012-02-01

163

Real-Time Scanning Tunneling Microscopy Observation of Si(111) Surface Modified by Au+ Ion Irradiation  

NASA Astrophysics Data System (ADS)

The real-time scanning tunneling microscopy (STM) observation of Au+ ion irradiation effects on a high-temperature Si surface has been performed using our original ion gun and STM combined system. Sequential STM images of a Si(111)-7×7 surface kept at 500 °C have been obtained before, during, and after Au+ ion irradiation with 3 keV. Vacancy islands, which are two-dimensional clusters of surface vacancies, and 5×2-Au structures were formed on the sample surface, and their size were changed during the heat treatment after the ion irradiation. This method enables us to count exact numbers of vacancies and Au atoms on the surface by measuring the sizes of vacancy islands and 5×2-Au reconstructions. The timescale of the growth of the 5×2-Au domain suggests that the implanted Au atoms diffuse to the surface almost without interacting with point defects induced by the ion irradiation.

Kamioka, Takefumi; Sato, Kou; Kazama, Yutaka; Ohdomari, Iwao; Watanabe, Takanobu

2010-01-01

164

Tailoring the Ti/4H-SiC Schottky barrier by ion irradiation  

SciTech Connect

The effects of ion irradiation on the Ti/4H-SiC Schottky barrier are discussed. The Ti/SiC interfacial region was modified by irradiating Schottky diodes with 8 MeV Si{sup +4} ions at fluences between 1x10{sup 9} and 1x10{sup 12} ions/cm{sup 2}. By increasing the ion fluence, an increase of the Schottky barrier {phi}{sub B} occurs, from the value of 1.05 eV after preparation to the value of 1.21 eV after irradiation at a fluence of 1x10{sup 12} ions/cm{sup 2}, without substantial changes in the ideality factor (n=1.09). Along with the barrier height increase, a decrease of the leakage current of about two orders of magnitude was observed after irradiation. The results were interpreted in terms of the structural and electrical modification of the interfacial region.

Roccaforte, Fabrizio; Bongiorno, Corrado; La Via, Francesco; Raineri, Vito [CNR-IMM, Sezione di Catania, Stradale Primosole 50, I-95121 Catania (Italy)

2004-12-20

165

Damage growth in Si during self-ion irradiation: A study of ion effects over an extended energy range  

SciTech Connect

Damage nucleation/growth in single-crystal Si during ion irradiation is discussed. For MeV ions, the rate of growth as well as the damage morphology are shown to vary widely along the track of the ion. This is attributed to a change in the dominant, defect-related reactions as the ion penetrates the crystal. The nature of these reactions were elucidated by studying the interaction of MeV ions with different types of defects. The defects were introduced into the Si crystal prior to high-energy irradiation by self-ion implantation at a medium energy (100 keV). Varied damage morphologies were produced by implanting different ion fluences. Electron microscopy and ion-channeling measurements, in conjunction with annealing studies, were used to characterize the damage. Subtle changes in the predamage morphology are shown to result in markedly different responses to the high-energy irradiation, ranging from complete annealing of the damage to rapid growth. These divergent responses occur over a narrow range of dose (2--3 /times/ 10/sup 14/ cm/sup /minus/2/) of the medium-energy ions; this range also marks a transition in the growth behavior of the damage during the predamage implantation. A model is proposed which accounts for these observations and provides insight into ion-induced growth of amorphous layers in Si and the role of the amorphous/crystalline interface in this process. 15 refs, 9 figs.

Holland, O.W.; El-Ghor, M.K.; White, C.W.

1989-01-01

166

In-situ observation and atomic resolution imaging of the ion irradiation induced amorphisation of graphene  

PubMed Central

Ion irradiation has been observed to induce a macroscopic flattening and in-plane shrinkage of graphene sheets without a complete loss of crystallinity. Electron diffraction studies performed during simultaneous in-situ ion irradiation have allowed identification of the fluence at which the graphene sheet loses long-range order. This approach has facilitated complementary ex-situ investigations, allowing the first atomic resolution scanning transmission electron microscopy images of ion-irradiation induced graphene defect structures together with quantitative analysis of defect densities using Raman spectroscopy. PMID:25284688

Pan, C.-T.; Hinks, J. A.; Ramasse, Q. M.; Greaves, G.; Bangert, U.; Donnelly, S. E.; Haigh, S. J.

2014-01-01

167

Ion irradiation-induced bimodal surface morphology changes in InSb.  

PubMed

High-energy ion irradiation of InSb results in the formation of bimodal surface structures, namely microscale hillock-like structures fully composed of nanoscale fibers. Analysis of the surface structures by a wide range of electron microscopy techniques reveals correlations between the irradiation conditions, such as the ion energy and fluence, and changes in the surface morphology. Sputtering effects play a key role in the integrity of the surface layer with increasing ion fluence. Possible mechanisms responsible for the morphological transformation are discussed, including both irradiation-induced and mechanical effects. PMID:20639585

Perez-Bergquist, Alejandro G; Li, Kundar; Zhang, Yanwen; Wang, Lumin

2010-08-13

168

In-situ observation and atomic resolution imaging of the ion irradiation induced amorphisation of graphene.  

PubMed

Ion irradiation has been observed to induce a macroscopic flattening and in-plane shrinkage of graphene sheets without a complete loss of crystallinity. Electron diffraction studies performed during simultaneous in-situ ion irradiation have allowed identification of the fluence at which the graphene sheet loses long-range order. This approach has facilitated complementary ex-situ investigations, allowing the first atomic resolution scanning transmission electron microscopy images of ion-irradiation induced graphene defect structures together with quantitative analysis of defect densities using Raman spectroscopy. PMID:25284688

Pan, C-T; Hinks, J A; Ramasse, Q M; Greaves, G; Bangert, U; Donnelly, S E; Haigh, S J

2014-01-01

169

Highly Charged Ion Bombardment of Silicon Surfaces  

SciTech Connect

Visible photoluminescence from Si(100) surfaces irradiated by highly charged ions has recently been reported [1]. In an attempt to reproduce these results, highly charged ion-irradiated silicon samples were prepared at the Electron Beam Ion Trap at the National Institute of Standards and Technology. Two highly sensitive fluorescence detection schemes were employed, both using ultraviolet light from an argon-ion laser for excitation. In the first detection scheme, the Xe44+-Si(100) samples were excited by the ultraviolet light while a spectrograph equipped with a liquid nitrogen-cooled charge-coupled device camera detected the fluorescence. The second detection scheme was a high throughput laser-scanning confocal microscope equipped with a photon-counting photomultiplier tube. We characterized the sensitivities in each detection scheme, allowing the assessment of the photoluminescence efficiency of Xe44+-Si(100). No photoluminescence was detected in either setup.

Sanabia, Jason E.; Goldie, Scott N.; Ratliff, Laura P.; Goldner, Lori S.; Gillaspy, John D. [Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

2003-08-26

170

Effect of ion irradiation on the surface, structural and mechanical properties of brass  

NASA Astrophysics Data System (ADS)

Modifications to the surface, structural and mechanical properties of brass after ion irradiation have been investigated. Brass targets were bombarded by carbon ions of 2 MeV energy from a Pelletron linear accelerator for various fluences ranging from 56 × 1012 to 26 × 1013 ions/cm2. A scanning electron microscope and X-ray diffractometer were utilized to analyze the surface morphology and crystallographic structure respectively. To explore the mechanical properties e.g., yield stress, ultimate tensile strength and microhardness of irradiated brass, an universal tensile testing machine and Vickers microhardness tester were used. Scanning electron microscopy results revealed an irregular and randomly distributed sputter morphology for a lower ion fluence. With increasing ion fluence, the incoherently shaped structures were transformed into dendritic structures. Nano/micro sized craters and voids, along with the appearance of pits, were observed at the maximum ion fluence. From X-ray diffraction results, no new phases were observed to be formed in the brass upon irradiation. However, a change in the peak intensity and higher and lower angle shifting were observed, which represents the generation of ion-induced defects and stresses. Analyses confirmed modifications in the mechanical properties of irradiated brass. The yield stress, ultimate tensile strength and hardness initially decreased and then increased with increasing ion fluence. The changes in the mechanical properties of irradiated brass are well correlated with surface and crystallographic modifications and are attributed to the generation, augmentation, recombination and annihilation of the ion-induced defects.

Ahmad, Shahbaz; Bashir, Shazia; Ali, Nisar; Umm-i-Kalsoom; Yousaf, Daniel; Faizan-ul-Haq; Naeem, Athar; Ahmad, Riaz; Khlaeeq-ur-Rahman, M.

2014-04-01

171

Response properties of YAlO3:Ce scintillation crystal under ion irradiation  

NASA Astrophysics Data System (ADS)

A novel ion-scintillator technique used to evaluate the scintillation response is demonstrated using YAlO3:Ce crystal under H+, He+ and O3+ ions irradiation. The experiment setup, including a forward-scatter target and a time-of-flight telescope, allows quantitative measurement of each ion-scintillator interaction event over a continuous ion energy range, and the related response properties of YAlO3:Ce, including the luminescent photon yield, nonlinear response and energy resolution, have been studied by detailed analysis of the total electronic energy deposition, electronic energy loss density and the displacement damage during ion irradiation process. The measured response properties of YAlO3:Ce under ion irradiation are consistent with that from the gamma tests, which demonstrates that this technique, applicable to small crystals or thin films, can rapidly and effectively evaluate the scintillator performance and, therefore, assist accelerated discovery of radiation detection materials.

Liu, Peng; Zhang, Yanwen; Wang, Xuelin; Xiang, Xia; Weber, William J.

2013-07-01

172

Comparison of UV and high-energy ion irradiation of methanol:ammonia ice  

E-print Network

The main goal of this work is to compare the effects induced in ices of astrophysical relevance by high-energy ions, simulating cosmic rays, and by vacuum ultraviolet (UV) photons. This comparison relies on in situ infrared spectroscopy of irradiated CH3OH:NH3 ice. Swift heavy ions were provided by the GANIL accelerator. The source of UV was a microwave-stimulated hydrogen flow discharge lamp. The deposited energy doses were similar for ion beams and UV photons to allow a direct comparison. A variety of organic species was detected during irradiation and later during ice warm-up. These products are common to ion and UV irradiation for doses up to a few tens of eV per molecule. Only the relative abundance of the CO product, after ice irradiation, was clearly higher in the ion irradiation experiments. For some ice mixture compositions, the irradiation products formed depend only weakly on the type of irradiation, swift heavy ions, or UV photons. This simplifies the chemical modeling of energetic ice processing ...

Caro, G M Munoz; Boduch, P; Rothard, H; Domaracka, A; Jimenez-Escobar, A

2014-01-01

173

Comparison of UV and high-energy ion irradiation of methanol:ammonia ice  

NASA Astrophysics Data System (ADS)

Aims: The main goal of this work is to compare the effects induced in ices of astrophysical relevance by high-energy ions, simulating cosmic rays, and by vacuum ultraviolet (UV) photons. Methods: This comparison relies on in situ infrared spectroscopy of irradiated CH3OH:NH3 ice. Swift heavy ions were provided by the GANIL accelerator. The source of UV was a microwave-stimulated hydrogen flow discharge lamp. The deposited energy doses were similar for ion beams and UV photons to allow a direct comparison. Results: A variety of organic species was detected during irradiation and later during ice warm-up. These products are common to ion and UV irradiation for doses up to a few tens of eV per molecule. Only the relative abundance of the CO product, after ice irradiation, was clearly higher in the ion irradiation experiments. Conclusions: For some ice mixture compositions, the irradiation products formed depend only weakly on the type of irradiation, swift heavy ions, or UV photons. This simplifies the chemical modeling of energetic ice processing in space.

Muñoz Caro, G. M.; Dartois, E.; Boduch, P.; Rothard, H.; Domaracka, A.; Jiménez-Escobar, A.

2014-06-01

174

Surface patterning of GaAs under irradiation with very heavy polyatomic Au ions  

NASA Astrophysics Data System (ADS)

Self-organization of surface patterns on GaAs under irradiation with heavy polyatomic Au ions has been observed. The patterns depend on the ion mass, and the substrate temperature as well as the incidence angle of the ions. At room temperature, under normal incidence the surface remains flat, whereas above 200 °C nanodroplets of Ga appear after irradiation with monatomic, biatomic as well as triatomic Au ions of kinetic energies in the range of 10-30 keV per atom. In the intermediate temperature range of 100-200 °C meander- and dot-like patterns form, which are not related to Ga excess. Under oblique ion incidence up to 45° from the surface normal, at room temperature the surface remains flat for mon- and polyatomic Au ions. For bi- and triatomic ions in the range of 60° ? ? ? 70° ripple patterns have been found, which become shingle-like for ? ? 80°, whereas the surface remains flat for monatomic ions.

Bischoff, L.; Böttger, R.; Heinig, K.-H.; Facsko, S.; Pilz, W.

2014-08-01

175

Differential effects of irradiation with carbon ions and x-rays on macrophage function.  

PubMed

Macrophages are potent elicitors of inflammatory reactions that can play both positive and negative roles in radiotherapy. While several studies have investigated the effects of X-rays or gamma-rays on macrophages, virtually no work has been done on the responses of these cells to irradiation with carbon ions. Investigations into the effects of carbon ion irradiation are of particular interest in light of the fact that this type of radiation is being used increasingly for cancer therapy. In the present investigation we compared the effects of 250 kV X-rays with those of 9.8 MeV/u carbon ions on RAW 264.7 macrophages over a wide range of radiation doses. Macrophage functions including vitality, phagocytic activity, production of the proinflammatory cytokines IL-1beta and TNFalpha and production of nitric oxide (NO) were measured. In comparison to lymphocytes and fibroblasts, macrophages showed only a small decrease in vitality after irradiation with either X-rays or carbon ions. Proinflammatory cytokines and NO were induced in macrophages by LPS but not by irradiation alone. X-rays or carbon ions had little modulating effect on LPS-induced TNFalpha production. However, LPS-induced NO increased in a dose dependent manner up to 6-fold after carbon ion irradiation, while X-ray irradiation did not have this effect. Carbon ion irradiation mediated a concomitant decrease in IL-1beta production. Carbon ions also had a greater effect than X-rays in enhancing the phagocytic activity of macrophages. These results underscore the greater potential of carbon ion irradiation with regard to radiobiological effectiveness. PMID:19398853

Conrad, Sandro; Ritter, Sylvia; Fournier, Claudia; Nixdorff, Kathryn

2009-05-01

176

Investigation of the effect of low energy ion beam irradiation on mono-layer graphene  

SciTech Connect

In this paper, the effect of low energy irradiation on mono-layer graphene was studied. Mono-layer graphene films were irradiated with B, N and F ions at different energy and fluence. X-ray photoelectron spectroscopy indicates that foreign ions implanted at ion energies below 35 eV could dope into the graphene lattice and form new chemical bonds with carbon atoms. The results of Raman measurement indicate that ion beam irradiation causes defects and disorder to the graphene crystal structure, and the level of defects increases with increasing of ion energy and fluence. Surface morphology images also prove that ion beam irradiation creates damages to graphene film. The experiment results suggest that low-energy irradiation with energies of about 30 eV and fluences up to 5·10{sup 14} cm{sup ?2} could realize small amount of doping, while introducing weak damage to graphene. Low energy ion beam irradiation, provides a promising approach for controlled doping of graphene.

Xu, Yijun [College of Physics science and technology, Soochow University, Suzhou215006 (China) [College of Physics science and technology, Soochow University, Suzhou215006 (China); II. Physikalisches Institut, Universität Göttingen, Friedrich- Hund- Platz 1, 37077 Göttingen (Germany); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China); Zhang, Kun; Brüsewitz, Christoph; Hofsäss, Hans Christian [II. Physikalisches Institut, Universität Göttingen, Friedrich- Hund- Platz 1, 37077 Göttingen (Germany)] [II. Physikalisches Institut, Universität Göttingen, Friedrich- Hund- Platz 1, 37077 Göttingen (Germany); Wu, Xuemei [College of Physics science and technology, Soochow University, Suzhou215006 (China) [College of Physics science and technology, Soochow University, Suzhou215006 (China); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China)

2013-07-15

177

Effect of gigaelectron volt Au-ion irradiation on the characteristics of ultrananocrystalline diamond films  

SciTech Connect

The effect of 2.245 GeV Au-ion irradiation/postannealing processes on the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films was investigated. Au-ion irradiation with a fluence of around 8.4x10{sup 13} ions/cm{sup 2} is required to induce a large improvement in the EFE properties of the UNCD films. Postannealing the Au-ion irradiated films at 1000 deg. C for 1 h slightly degraded the EFE properties of the films but the resulting EFE behavior was still markedly superior to that of pristine UNCD films. Transmission electron microscopy examinations revealed that the EFE properties of the UNCD films are primarily improved by Au-ion irradiation/postannealing processes because of the formation of nanographites along the trajectory of the irradiating ions, which results in an interconnected path for electron transport. In contrast, the induction of grain growth process due to Au-ion irradiation in UNCD films is presumed to insignificantly degrade the EFE properties for the films as the aggregates are scarcely distributed and do not block the electron conducting path.

Chen, Huang-Chin; Teng, Kuang-Yau; Tang, Chen-Yau; Lin, I-Nan [Department of Physics, Tamkang University, Tamsui, Taiwan 251 (China); Sundaravel, Balakrishnan [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Amirthapandian, Sankarakumar [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen, Universitaet Stuttgart, Allmandring 3, 70569 Stuttgart (Germany)

2010-12-15

178

Confinement Resonances in Photoionization of Xe-C{sub 60}{sup +}  

SciTech Connect

Experimental evidence is presented for confinement resonances associated with photoabsorption by a Xe atom in a C{sub 60} cage. The giant 4d resonance in photoionization of Xe is predicted to be redistributed into four components due to multipath interference of photoelectron waves reflected by the cage. The measurements were made in the photon energy range 60-150 eV by merging a beam of synchrotron radiation with a mass/charge selected Xe-C{sub 60}{sup +} ion beam. The phenomenon was observed in the Xe-C{sub 583}{sup +} product ion channel.

Kilcoyne, A. L. D.; Aguilar, A. [Advanced Light Source, LBNL, MS 7-100, Berkeley, California 94720-8225 (United States); Mueller, A.; Schippers, S. [IAMP, Justus-Liebig-Universitaet, Leihgesterner Weg 217, 35392 Giessen (Germany); Cisneros, C. [Instituto de Ciencias Fisicas, UNAM, A.P. 48-3, Cuernavaca, 62251 (Mexico); Alna'Washi, G. [Hashemite University, P.O. Box 150459, Zarqa 13115 (Jordan); Aryal, N. B.; Baral, K. K.; Esteves, D. A.; Thomas, C. M.; Phaneuf, R. A. [Department of Physics, University of Nevada, Reno, Nevada 89557-0220 (United States)

2010-11-19

179

Resistivity changes and defect mobility in ion-irradiated YBa2Cu3O7-x  

NASA Astrophysics Data System (ADS)

In situ measurements during MeV ion bombardment at room temperature are used to study the superlinear increase of resistivity with fluence which occurs in irradiated YBa2Cu3O7-x. The functional form of the resistivity increase is found to be exactly exponential for O and As ion irradiation, confirming previous results of lower precision. For low ion damage rates we find deviations from the exponential dependence at low doses. We show that these are caused by an unidentified phase transformation, occurring during the irradiation, which lowers the resistivity of the samples. Annealing of resistivity increments caused by brief irradiations occurs at room temperature, indicating that radiation-induced defects are mobile. The rate of annealing is strongly sample dependent, but in all cases the transformation induced by a small dose of irradiation causes a reduction in the resistivity of the sample. We suggest that the reduction in resistivity may be due to ordering on the oxygen sublattice.

Marwick, A. D.; Clark, G. J.; Yee, D. S.; Laibowitz, R. B.; Coleman, G.; Cuomo, J. J.

1989-05-01

180

The influence of ion flux on defect production in MeV proton-irradiated silicon  

E-print Network

The influence of ion flux on defect production in MeV proton-irradiated silicon A. Hall&, D. Fenyli, Universi@ of Virginia, Charlottesville, Virginia 22901 B. G. Svensson Solid State Electronics, The Royal

Johnson, Robert E.

181

Investigation of Current Spike Phenomena During Heavy Ion Irradiation of NAND Flash Memories  

NASA Technical Reports Server (NTRS)

A series of heavy ion and laser irradiations were performed to investigate previously reported current spikes in flash memories. High current events were observed, however, none matches the previously reported spikes. Plausible mechanisms are discussed.

Oldham, Timothy R.; Berg, Melanie; Friendlich, Mark; Wilcox, Ted; Seidleck, Christina; LaBel, Kenneth A.; Irom, Farokh; Buchner, Steven P.; McMorrow, Dale; Mavis, David G.; Eaton, Paul H.; Castillo, James

2011-01-01

182

The influence of fractionation on cell survival and premature differentiation after carbon ion irradiation.  

PubMed

To investigate the influence of fractionation on cell survival and radiation induced premature differentiation as markers for early and late effects after X-rays and carbon irradiation. Normal human fibroblasts NHDF, AG1522B and WI-38 were irradiated with 250 kV X-rays, or 266 MeV/u, 195 MeV/u and 11 MeV/u carbon ions. Cytotoxicity was measured by a clonogenic survival assay or by determination of the differentiation pattern. Experiments with high-energy carbon ions show that fractionation induced repair effects are similar to photon irradiation. The RBE(10) values for clonogenic survival are 1.3 and 1.6 for irradiation in one or two fractions for NHDF cells and around 1.2 for AG1522B cells regardless of the fractionation scheme. The RBE for a doubling of post mitotic fibroblasts (PMF) in the population is 1 for both single and two fractionated irradiation of NHDF cells. Using 11 MeV/u carbon ions, no repair effect can be seen in WI-38 cells. The RBE(10) for clonogenic survival is 3.2 for single irradiation and 4.9 for two fractionated irradiations. The RBE for a doubling of PMF is 3.1 and 5.0 for single and two fractionated irradiations, respectively. For both cell lines the effects of high-energy carbon ions representing the irradiation of the skin and the normal tissue in the entrance channel are similar to the effects of X-rays. The fractionation effects are maintained. For the lower energy, which is representative for the irradiation of the tumor region, RBE is enhanced for clonogenic survival as well as for premature terminal differentiation. Fractionation effects are not detectable. Consequently, the therapeutic ratio is significantly enhanced by fractionated irradiation with carbon ions. PMID:18451608

Wang, Jufang; Li, Renming; Guo, Chuanling; Fournier, Claudia; K-Weyrather, Wilma

2008-07-01

183

Xe(L) x-ray emission from laser-cluster interaction* , O.Gobert4  

E-print Network

Xe(L) x-ray emission from laser-cluster interaction* L. Adoui2 , O.Gobert4 , P. Indelicato3 , E-ray emission yields from (Xe)n clusters (with n in the range 105 ­ 107 atoms/cluster) irradiated by 60. Measurements have been performed as a function of cluster size (backing pressure) and laser peak intensity

184

Properties of indium phosphite and selected compounds under irradiation with swift heavy ions  

NASA Astrophysics Data System (ADS)

Surface and bulk properties of indium phosphate single crystals with initial and previously irradiated by 25 MeV electrons structures were irradiated with 86Kr (253 MeV) and 197Au (200 MeV) up to various fluences. The modern methods of condensed matter studies were used for research of InP property changes before and after irradiation as scanning (SEM) and high resolution transmission electronic microscopy (HTEM), Rutherford backscattering spectroscopy (RBS/C) and atomic force microscopy (AFM). The comparison of obtained results with the results of other authors is carried out. The surface structure change of InP single crystal irradiated by high-energy 86Kr ions and electrons is studied. It is shown the changes of the InP surface have complicated character and caused by inelastic sputtering processes. It is observed the twice irradiated layer swells with the cracks creation on the surface. The swelling with cracks and strong sputtering of twice irradiated by electrons and ions with high energy layers of the InP and GaAs surfaces are explained using the model based on the influence of ionizing energy loss of swift 86Kr ions. The small crystalline objects are detected on the InP surface irradiated with 86Kr ions which may be nano- and micro-crystals of InP. All obtained effects are discussed in frame of models based on ionizing energy loss of swift heavy ions.

Didyk, A. Yu.; Khalil, A. S.

2010-03-01

185

Oxide shell reduction and magnetic property changes in core-shell Fe nanoclusters under ion irradiation  

NASA Astrophysics Data System (ADS)

Ion irradiation effects are studied on the Fe-based core-shell nanocluster (NC) films with core as Fe and shell as Fe3O4/Fe3N. These NC films were deposited on Si substrates to thickness of ˜0.5 ?m using a NC deposition system. The films were irradiated at room temperature with 5.5 MeV Si2+ ions to ion fluences of 1015 and 1016 ions/cm2. It is found that the irradiation induces grain growth, Fe valence reduction in the shell, and crystallization or growth of Fe3N. The film retained its Fe-core and its ferromagnetic properties after irradiation. The nature and mechanism of oxide shell reduction and composition dependence after irradiation were studied by synthesizing additional NC films of Fe3O4 and FeO + Fe3N and irradiating them under the same conditions. The presence of nanocrystalline Fe is found to be a major factor for the oxide shell reduction. The surface morphologies of these films show dramatic changes in the microstructures due to cluster growth and agglomeration as a result of ion irradiation.

Sundararajan, Jennifer A.; Kaur, Maninder; Jiang, Weilin; McCloy, John S.; Qiang, You

2014-05-01

186

Enhancement of electric double layer capacitance of carbon nanotubes by gallium ion irradiation  

SciTech Connect

Irradiation by 30 keV Ga{sup +} ions was used to create defects in multiwalled carbon nanotubes. Damage to the graphitic structure of the nanotube wall resulting from ion irradiation was observed by a transmission electron microscope which was accompanied by corresponding changes in Raman spectra. It was found that ion irradiation at 2 x 10{sup 13} ions/cm{sup 2} cumulative dose increases the electric double layer capacitance of a multiwalled carbon nanotube electrode by a factor of 2.3, followed by a decrease and saturation at higher (2 x 10{sup 14} and 4 x 10{sup 14} ions/cm{sup 2}) doses. This might be a trade-off between the enhancement caused by the tip opening and lowering of the capacitance due to amorphization of carbon nanotubes.

Rai, Padmnabh; Pandey, Srikrishna; Menemparabath, Minimol; Sug Kim, Young; Nikolaev, Pavel; Arepalli, Sivaram [Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Il Ha [Sungkyunkwan Advanced Institute of Nanotechnology, Suwon 440-746 (Korea, Republic of)

2011-02-15

187

Conduction mechanisms in ion-irradiated InGaAs layers  

SciTech Connect

The electrical and optical properties of H{sup +}- and Au{sup +}-irradiated InGaAs layers were studied using Hall-effect, van der Pauw, and relaxation-time measurements. Comparing the different results allows us to obtain information on the nature of the defects created by these two irradiations. Proton irradiation introduces donor-acceptor paired defects. Gold-ion irradiation creates neutral defect clusters and ionized point defects. The carrier mobilities in all of the irradiated materials are degraded, decreasing with increasing irradiation dose. A scattering model taking into account the paired defects is developed and the mobility evolution calculated from this model agrees with the experimental data of both annealed and unannealed samples. The photocurrent spectra reveal a metallic conduction in the band gap in the case of light-ion irradiation, while such type of conduction does not appear for heavy-ion irradiation. This metallic conduction is a consequence of band tailing induced by shallow defects and vanishes when the material is annealed at 400 deg. C. The proton irradiation-induced defects appear to be related to the EL-2-like defects.

Joulaud, L.; Mangeney, J.; Chimot, N.; Crozat, P.; Fishman, G.; Bourgoin, J.C. [Institut d'Electronique Fondamentale, UMR Centre National de la Recherche Scientifique (CNRS) 8622, Universite Paris Sud, bat. 220, 91405 Orsay Cedex (France); Gesec Research and Development, 68 Avenue de la Foret, 77210 Avon (France)

2005-03-15

188

Anisotropic dislocation loop nucleation in ion-irradiated MgAl sub 2 O sub 4  

SciTech Connect

Polycrystalline disks of stoichiometric magnesium aluminate spinel (MgAl{sub 2}O{sub 4}) were irradiated with 2 MeV Al{sup +} ions at 650{degrees}C and subsequently analyzed in cross-section using transmission electron microscopy (TEM). Interstitial dislocation loops were observed on 110 and 11 habit planes. The population of loops on both sets of habit planes was strongly dependent on their orientation with respect to the ion beam direction. The density of loops with habit plane normals nearly perpendicular to the ion beam direction much higher than loops with habit plane normals nearly parallel to the ion beam direction. On the other hand, the loop size was nearly independent of habit plane orientation. This anisotropic loop nucleation does not occur in ion-irradiated metals such as copper. An additional anomaly associated with ion-irradiated spinel is that the loops on 111 planes were partially unfaulted with a Burgers vector of b = a/4<110>. Previous neutron irradiation studies have never reported unfaulted loops in stoichiometric spinel. Possible cause of the unusual response of spinel to ion irradiation are discussed. 12 refs., 14 figs.

Zinkle, S.J.

1991-01-01

189

Low-energy D{sup +} and H{sup +} ion irradiation effects on highly oriented pyrolytic graphite  

SciTech Connect

We have investigated the low-energy (100 eV) D{sup +} and H{sup +} ion irradiation effects on the structural and chemical properties of highly oriented pyrolytic graphite (HOPG). Structural disorder due to the ion irradiation was identified by the Raman spectroscopy, the D{sup +} irradiation giving rise to greater structural disorder than the H{sup +} irradiation. Only sp{sup 2} bonding was identified in the X-ray photoemission spectroscopy of the D{sup +}-irradiated HOPG, indicating no change in the surface chemical structure. The H{sup +} irradiation, on the other hand, gave rise to sp{sup 3} bonding and ???{sup *} transition, the sp{sup 3} bonding increasing with increasing irradiation dose. It is thus shown that the chemical properties of the HOPG surface may be sensitively modified by the low-energy H{sup +} ion irradiation, but not by the low-energy D{sup +} ion irradiation.

Kue Park, Jun; Won Lee, Kyu; Hee Han, Jun; Jung Kweon, Jin; Kim, Dowan; Eui Lee, Cheol [Department of Physics and Institute for Nano Science, Korea University, Seoul 136-713 (Korea, Republic of)] [Department of Physics and Institute for Nano Science, Korea University, Seoul 136-713 (Korea, Republic of); Lim, Sun-Taek; Kim, Gon-Ho [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)] [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Noh, S. J.; Kim, H. S. [Department of Applied Physics, Dankook University, Yongin 448-701 (Korea, Republic of)] [Department of Applied Physics, Dankook University, Yongin 448-701 (Korea, Republic of)

2013-12-07

190

Ion dose dependence of the sputtering yield: Ar{sup +}, Ne{sup +}, and Xe{sup +} bombardment of Ru(0001) and Al(111)  

SciTech Connect

The sputtering yield from clean metal surfaces has long been considered to be insensitive to primary ion dose at moderate ion fluences (< 10{sup 18} ions/cm{sup 2}). Using carefully cleaned and well-characterized targets, the ion dose dependence of the sputtering yield of Ru(0001) and Al(111) has been investigated. The sputtering yield of Ru(0001) is found to decrease substantially following primary ion bombardment at low fluences, while the sputtering yield of Al(111) exhibits no fluence dependence at low primary ion dose. Using secondary neutral mass spectrometry (SNMS), the sputtering yield of ruthenium was observed to decrease following ion bombardment by argon, xenon, and neon. High-detection-efficiency time-of-flight mass spectrometry was coupled with nonresonant laser ionization to allow real-time sputtering yield measurements and to minimize target damage during data collection. The experiments show that the sputtering yield of Ru(0001) decreases by 50%, following a primary ion fluence of, less than 10{sup 16} ions/cm{sup 2} for sputtering by either argon or neon ions and by 25%, following primary ion fluences of less than 10{sup 14} ions/cm{sup 2} for sputtering by xenon. The small size of the experimentally determined damage cross section suggests that microscopic changes in the surface structure cause the observed sputtering yield depression. In contrast to the ruthenium results, the sputtering yield of Al(111) appears to be insensitive to primary ion fluence at low fluences. Calculations using the TRansport of Ions in Matter (TRIM) Monte Carlo sputtering simulation were carried out to investigate the effect of primary ion implantation upon the sputtering yield of ruthenium as well as the effect of a reduced surface binding energy of ruthenium surface atoms. The TRIM results indicate that neither of these mechanisms can explain the experimentally observed fluence dependence of the sputtering yield of ruthenium.

Burnett, J.W.; Pellin, M.J.; Whitten, J.E.; Gruen, D.M. [Argonne National Lab., IL (United States); Yates, J.T. Jr. [Univ. of Pittsburgh, PA (United States)

1994-04-01

191

Kr-86 Ion-Beam Irradiation of Hydrated DNA: Free Radical and Unaltered Base Yields  

PubMed Central

This work reports an ESR and product analysis investigation of Kr-86 ion-beam irradiation of hydrated DNA at 77 K. The irradiation results in the formation and trapping of both base radicals and sugar phosphate radicals (DNA backbone radicals). The absolute yields (G, ?mol/J) of the base radicals are smaller than the yields found in similarly prepared ?-irradiated DNA samples, and the relative yields of backbone radicals relative to base radicals are much higher than that found in ?-irradiated samples. From these results, we have elaborated our radiation chemical model of the track structure for ion-beam irradiated DNA as it applies to krypton ion-beams. The base radicals, which are trapped as ion radicals or reversibly protonated or deprotonated ion radicals, are formed almost entirely in the track penumbra, a region in which radiation chemical effects are similar to those found in ?-irradiated samples. By comparing the yields of base radicals in ion-beam samples to the yields of the same radicals in ?-irradiated samples, the partition of energy between the low-LET region (penumbra) and the core is experimentally determined. The neutral sugar and other backbone radicals, which are not as susceptible to recombination as are ion radicals, are formed largely in the track core. The backbone radicals show a linear dose response up to very high doses. Unaltered base release yields in Kr-86 irradiated hydrated DNA are equal to sugar radical yields within experimental error limits, consistent with radiation-chemical processes in which all base release originates with sugar radicals. Two phosphorus-centered radicals from fragmentation of the DNA backbone are found in low yields. PMID:23106211

Becker, David; Adhikary, Amitava; Tetteh, Smedley T.; Bull, Arthur W.; Sevilla, Michael D.

2012-01-01

192

Controlled optical and magnetic properties of ZnO nanorods by Ar ion irradiation  

SciTech Connect

Herein we report a controlled defect-related emission and magnetization properties of zinc oxide nanorods using low energy (2-5 keV) Ar ion irradiation. The ratio of the defect related emission to the excitonic emission decreases by an order magnitude due to the ion bombardment. The hysteresis loops of pristine and irradiated nanorods show ferromagnetic behavior at room temperature. A sharp decrease in the value of magnetization is due to an enhancement of irradiation time and energy. Combining with x-ray photoelectron spectroscopy results, a direct link between the magnetization and defect-emission of ZnO nanorods is established.

Panigrahy, Bharati; Bahadur, D. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India); Aslam, M. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India)

2011-05-02

193

Characterization of Vacancy Defects in Carbon Ion Irradiated Graphite Using Positrons  

SciTech Connect

Highly Oriented Pyrolytic Graphite samples are irradiated with 200 keV Carbon ions to fluences of 10{sup 14} and 10{sup 15} C{sup +} ions/cm{sup 2}. Depth resolved Doppler lineshape S-parameter exhibited large increase in peak damage regions of the sample, indicating the existence of irradiation induced vacancy defects. The depth profile of the defect region has been deduced from the analysis of the experimental data. It is found that divacancies are the dominant defects in the irradiated samples.

Anto, C. Varghese; Arunkumar, J.; Rajaraman, R.; Nair, K. G. M.; Amarendra, G. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, T.N (India)

2011-07-15

194

DNA-PKcs Inhibition Sensitizes Cancer Cells to Carbon-Ion Irradiation via Telomere Capping Disruption  

PubMed Central

Heavy-ion irradiation induces a higher frequency of DNA double strand breaks (DSBs) which must be properly repaired. Critical shortening of telomeres can trigger DNA damage responses such as DSBs. Telomeres are very sensitive to oxidative stress such as ionizing radiation. The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is the central component in the non-homologous end joining (NHEJ) repair complex and participates in telomere maintenance. Therefore, it is expected to enhance the cell killing effect of heavy-ion irradiation via DNA-PKcs inhibition. To test this hypothesis, cellular radiosensitivity was measured by the clonal genetic assay. DNA damage repair was relatively quantified by long PCR. Apoptosis was quantified by flow-cytometric analysis of annexin V/PI double staining, and senescence was analyzed by galactosidase activity. Telomere length was semi-quantified by real-time PCR. P53 and p21 expression was determined by western blotting. Our data demonstrated that MCF-7 and HeLa cells with DNA-PKcs inhibition were more susceptible to carbon-ion irradiation than Those without DNA-PKcs inhibition. Even though NHEJ was inhibited by the DNA-PKcs specific inhibitor, NU7026, most DNA damage induced by carbon-ion irradiation was repaired within 24 hours after irradiation in both cell lines. However, potential lethal damage repair (PLDR) could not restore cellular inactivation in DNA-PKcs inhibited cells. MCF-7 cells showed extensive senescence and accelerated telomere length reduction, while HeLa cells underwent significant apoptosis after irradiation with NU7026 incubation. In addition, both cell lines with shorter telomere were more susceptible to carbon-ion radiation. Our current data suggested that DNA-PKcs inhibition could enhance cellular sensitivity to carbon-ion radiation via disturbing its functional role in telomere end protection. The combination of DNA-PKcs inhibition and carbon-ion irradiation may be an efficient method of heavy-ion therapy. PMID:24013362

Zhou, Xin; Zhang, Xin; Xie, Yi; Tanaka, Kaoru; Wang, Bing; Zhang, Hong

2013-01-01

195

Time frame for secondary processing through I-Xe chronometry  

NASA Astrophysics Data System (ADS)

As part of an on going program for evaluating the I-Xe chronometer through comparisons with Pb-Pb chronometry on the same mineral phases, we have measured Xe in neutron-irradiated nonmagnetic mineral separates from three meteorites: Acapulco (A), Allegan (H5), and Richardton (H5). The phosphates of these three meteorites have been previously dated and have Pb-Pb ages of 4.557 +/- 0.002, 4.5563 +/- 0.0008, and 4.5534 +/- 0.0006 b.y. respectively. For Pb-Pb work, preparation of the phosphates involves crushing, sieving (38-150 microns), and heavy-liquid separation (bromoform) of the nonmagnetic fraction into more dense (phosphate) and less dense (chiefly feldspar) fractions. However, the use of heavy liquids prior to neutron irradiation contaminates the mineral grains with I, which neutron-captures to Xe-128 during irradiation. Therefore we postponed the final density separation until after the neutron irradiation. This also assures that both density fractions received identical neutron fluences. The samples reported here are high- and low-density fractions from both Acapulco and Allegan, and a single, non-magnetic fraction from Richardton. For the Acapulco phosphates, the Xe-data provide a precise I-Xe isochron, with an uncertainty of less than 90,000 yr. However, Allegan phosphates contain little I-derived Xe, and Richardton was not density separated so its isochron may be dominated by the feldspar-rich (low-density) phase. More interesting is the apparent age difference between the Acapulco phosphates and the low-density (felspar-rich) fraction. The I-Xe isochron obtained for the low-density Acapulco fraction implies Xe closure 4.8 m.y. earlier than closure in the Acapulco phosphates, 3.3 m.y. after Xe closure in Bjurbole. If the earlier (feldspar) phase is associated with primary formation, the 4.8-m.y. interval suggests a timescale for the formation of secondary minerals (apatites) in Acapulco.

Brazzle, R. H.; Gopel, C.; Nichols, R. H., Jr.; Kehm, K.; Hohenberg, C. M.

1994-07-01

196

Microarray Analysis of Human Liver Cells irradiated by 80MeV\\/u Carbon Ions  

Microsoft Academic Search

Objective Biological effect of heavy ion beam has the important significance for cancer therapy and space exploring owing its high LET and RBE, low OER, especially forming Bragg spike at the end of the tracks of charged particles. More serious damage for cells are induced by heavy ions and difficult repair than other irradiation such as X-ray and nu-ray .

Xiao Wang; Xiaoling Tian; Fuquan Kong; Qiang Li; Xiaodong Jin; Zhongying Dai; Hong Zhang; Mingjian Yang; Kui Zhao

2008-01-01

197

EPR study of Ti3+ ions formed under beta irradiation in silicate  

E-print Network

of Rare Earth (RE) and Transition Metals (TM) ions in silicate and borosilicate oxide glasses under1 EPR study of Ti3+ ions formed under beta irradiation in silicate glasses P. Lombard1* , N. Ollier in various silicate glasses have been studied by EPR spectroscopy at 20 K. Different parameters like the [Na

Boyer, Edmond

198

PERMANENT MAGNETS UNDER IRRADIATION AND RADIOACTIVE ALKALI ION BEAM DEVELOPMENT FOR SPIRAL 1  

E-print Network

elements is provided by a cold transfer tube, situated between the target cavity and the source chamber to the permanent magnets of the ion source (Nanogan III), which can then be damaged by neutron irradiation, leading Source Systems (TISSs) have been built and used for the production of radioactive ion beams on SPIRAL 1

Boyer, Edmond

199

Mechanism of Elongation of Gold or Silver Nanoparticles in Silica by Irradiation with Swift Heavy Ions  

E-print Network

was perpendicular to the upper surface of the SiO2. The 12-unit double-Pelletron tandem accelerator nanoparticles oriented parallel to one another can be synthesized in SiO2 by ion irradiation. Our aim in an SiO2 matrix. It was found that Au nanoparticles showed greater elongated with a higher flux of ion

Boyer, Edmond

200

Chemi-luminescence measurements of hyperthermal Xe{sup +}/Xe{sup 2+}+ NH{sub 3} reactions  

SciTech Connect

Luminescence spectra are recorded for the reactions of Xe{sup +}+ NH{sub 3} and Xe{sup 2+}+ NH{sub 3} at energies ranging from 11.5 to 206 eV in the center-of-mass (E{sub cm}) frame. Intense features of the luminescence spectra are attributed to the NH (A {sup 3}{Pi}{sub i}-X {sup 3}{Sigma}{sup -}), hydrogen Balmer series, and Xe I emission observable for both primary ions. Evidence for charge transfer products is only found through Xe I emission for both primary ions and NH{sup +} emission for Xe{sup 2+} primary ions. For both primary ions, the absolute NH (A-X) cross section increases with collision energy before leveling off at a constant value, approximately 9 x 10{sup -18} cm{sup 2}, at about 50 eV while H-{alpha} emission increases linearly with collision energy. The nascent NH (A) populations derived from the spectral analysis are found to be independent of collision energy and have a constant rotational temperature of 4200 K.

Prince, Benjamin D.; Steiner, Colby P. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States); Chiu, Yu-Hui [Busek Co. Inc, Natick, Massachusetts 01760 (United States)

2012-04-14

201

Damage and Microstructure Evolution in GaN under Au Ion Irradiation  

SciTech Connect

Damage and microstructure evolution in gallium nitride (GaN) under Au+ ion irradiation has been investigated using complementary electron microscopy, secondary ion mass spectrometry and ion beam analysis techniques. Epitaxially-grown GaN layers (2-um-thick) have been irradiated by 2.0 MeV Au ions to 1.0 × 1015 and 1.4 × 1015 cm-2 at 155 K and 7.3 × 1015 cm-2 at 200 K. The irradiation-induced damage has been analyzed by Rutherford backscattering spectroscopy in a channeling direction (RBS/C). For a better determination of ion-induced disorder profile, an iterative procedure and a Monte Carlo code (McChasy) are combined to analyze the ion channeling spectra. With increasing irradiation dose, separated amorphous layers develop from the sample surface and near the damage peak region. Formation of large nitrogen bubbles with sizes up to 70 nm is observed in the buried amorphous layer, while the surface layer contains small bubbles with diameter of a few nanometers due to significant nitrogen loss from the surface. Volume expansion from 3% to 25% in the irradiated region is suggested by cross sectional transmission electron microscope and RBS/C measurement. The anomalous shape of the Au distributions under three irradiations indicates out-diffusion of Au toward sample surface. The results from the complementary techniques suggest that nitrogen is retained in the damaged GaN where the crystallinity is preserved. Once the amorphous state is reached in the surface region, GaN starts to decompose and nitrogen escapes from the surface. Furthermore, experimental results show considerable errors in both disorder profile and ion range predicted by the Stopping and Range of Ions in Matter code, indicating a significant overestimation of electronic stopping powers of Au ions in GaN.

Zhang, Yanwen; Ishimaru, Manabu; Jagielski, Jacek; Zhang, Weiming; Zhu, Zihua; Saraf, Laxmikant V.; Jiang, Weilin; Thome, Lionel; Weber, William J.

2010-02-11

202

Ion microbeam irradiation for radiobiology and radical chemistry: status and prospect  

NASA Astrophysics Data System (ADS)

Ion microbeams are commonly used to study local irradiation effects in living cells, as it has been established that ion beam irradiations can lead to deleterious changes in cells that are not struck directly by the microbeam. Such changes, which take place over distances long compared to the size of the irradiation spot and for times long compared to the time of irradiation, are collectively termed radiation-induced bystander effect or RIBE. Free-radical chemistry is frequently invoked to explain the RIBE but no unified model is available at present. Ion microbeams when coupled with advanced methods for observing free radicals are the tools of choice for investigating the chemistry and biological processes governing RIBE.

Khodja, H.

2011-01-01

203

Study on depth profile of heavy ion irradiation effects in poly(tetrafluoroethylene-co-ethylene)  

NASA Astrophysics Data System (ADS)

High linear energy transfer (LET) heavy ion beams were used to irradiate poly(tetrafluoroethylene-co-ethylene) (ETFE) under vacuum and in air. The irradiation effects in ETFE as a function of the depth were precisely evaluated by analyzing each of the films of the irradiated samples, which were made of stacked ETFE films. It was indicated that conjugated double bonds were generated by heavy ion beam irradiation, and their amounts showed the Bragg-curve-like distributions. Also, it was suggested that higher LET beams would induce radical formation in high density and longer conjugated C=C double bonds could be generated by the second-order reactions. Moreover, for samples irradiated in air, C=O was produced correlating to the yield of oxygen molecules diffusing from the sample surface.

Gowa, Tomoko; Shiotsu, Tomoyuki; Urakawa, Tatsuya; Oka, Toshitaka; Murakami, Takeshi; Oshima, Akihiro; Hama, Yoshimasa; Washio, Masakazu

2011-02-01

204

Formation and evolution of ripples on ion-irradiated semiconductor surfaces  

NASA Astrophysics Data System (ADS)

We have examined the formation and evolution of ripples on focused-ion-beam (FIB) irradiated compound semiconductor surfaces. Using initially normal-incidence Ga+ FIB irradiation of InSb, we tuned the local beam incidence angle (?eff) by varying the pitch and/or dwell time. For single-pass FIB irradiation, increasing ?eff induces morphological evolution from pits and islands to ripples to featureless surfaces. Multiple-pass FIB irradiation of the rippled surfaces at a fixed ?eff leads to island formation on the ripple crests, followed by nanorod (NR) growth. This ripple-NR transition provides an alternative approach for achieving dense arrays of NRs.

Kang, M.; Wu, J. H.; Ye, W.; Jiang, Y.; Robb, E. A.; Chen, C.; Goldman, R. S.

2014-02-01

205

High energy ion irradiation induced surface patterning on a SiO2 glass substrate  

NASA Astrophysics Data System (ADS)

Experimental results about formation of self-organized surface patterns on a silica glass substrate due to irradiations with high energy Au ions at various angles of incidences have been reported in this paper. Pattern formations are found to vary significantly from theoretical predictions. Orientation, growth of ripples and ripple characteristics observed here do not conform to established results of low energy heavy-ion irradiation studies. High energy Au ion-induced effects (e.g., surface stress, mass redistribution and surface current) have been suitably invoked to explain observed phenomena.

Srivastava, S. K.; Ganesan, K.; Gangopadhyay, P.; Panigrahi, B. K.; Nair, K. G. M.; Tyagi, A. K.

2014-11-01

206

New ion beam materials laboratory for materials modification and irradiation effects research  

NASA Astrophysics Data System (ADS)

A new multifunctional ion beam materials laboratory (IBML) has been established at the University of Tennessee, in partnership with Oak Ridge National Laboratory. The IBML is currently equipped with two ion sources, a 3 MV tandem accelerator, three beamlines and three endstations. The IBML is primarily dedicated to fundamental research on ion-solid interaction, ion beam analysis, ion beam modification, and other basic and applied research on irradiation effects in a wide range of materials. An overview of the IBML facility is provided, and experimental results are reported to demonstrate the specific capabilities.

Zhang, Y.; Crespillo, M. L.; Xue, H.; Jin, K.; Chen, C. H.; Fontana, C. L.; Graham, J. T.; Weber, W. J.

2014-11-01

207

Nanoindentation and Raman Spectroscopic Study of Graphite Irradiated with Swift U Ions  

Microsoft Academic Search

Modifications of the structure and mechanical properties of the isotropic fine-grained graphite R6650 irradiated with 2.6 GeV U ions at fluences up to 10 ions\\/cm at room temperature are studied. A strong ion-induced increase of Young's modulus and hardness is observed that points to the formation of a hard form of carbon. Raman spectra ascertain the disordering of graphite and

I. Manika; J. Maniks; R. Zabels; J. Gabrusenoks; M. Krause; M. Tomut; K. Schwartz

2012-01-01

208

Influence of Ar, Ne, Xe, and CCl4 impurities on luminescence kinetics of Cd II ions (5 s 2 2 D 5/2-5 p 2 P 3/2 transition, ? = 441.6 nm) in He-Cd mixture  

NASA Astrophysics Data System (ADS)

The luminescence kinetics of the Cd II ion at a wavelength of 441.6 nm has been studied experi-mentally in a high-pressure He-Cd mixture in the presence of Ar, Ne, Xe, and CCl4 impurities. Cadmium ions were excited through the bombardment of a cadmium foil heated up to 240°C by a pulsed electron beam with an electron energy of 150 keV, a pulse duration of 3 ns, and a current of 500 A. The constants of collisional quenching of the Cd II 5 s 2 2 D 5/2 level by Ar, Ne, and Xe atoms and CCl4 molecules and the integral luminescence quenching constants of this level in the helium medium by these impurity gases have been determined. The constants of collisional quenching appeared to be 8.1 × 10-12 (Ar), 1.2 × 10-12 (Xe), 1.5 × 10-13 (Ne), and 1.8 × 10-10 cm3/s (CCl4, for ? = 325 nm), while the integral constants were found to be, respectively, 4.1 × 10-11, 3.4 × 10-11, 9.5 × 10-12, 1.4 × 10-9 cm3/s for Ar, Ne, Xe, and CCl4 at a buffer gas pressure of 1 atm.

Miskevich, A. I.; Liu, Tao

2009-07-01

209

Enhancement of SPHK1 in vitro by carbon ion irradiation in oral squamous cell carcinoma  

SciTech Connect

Purpose The purpose of this study was to assess the gene expression changes in oral squamous cell carcinoma (OSCC) cells after carbon ion irradiation. Methods and Materials Three OSCC cell lines (HSC2, Ca9-22, and HSC3) were irradiated with accelerated carbon ion beams or X-rays using three different doses. The cellular sensitivities were determined by clonogenic survival assay. To identify genes the expression of which is influenced by carbon ion irradiation in a dose-dependent manner, we performed Affymetrix GeneChip analysis with HG-U133 plus 2.0 arrays containing 54,675 probe sets. The identified genes were analyzed using the Ingenuity Pathway Analysis Tool to investigate the functional network and gene ontology. Changes in mRNA expression in the genes were assessed by real-time reverse transcriptase-polymerase chain reaction. Results We identified 98 genes with expression levels that were altered significantly at least twofold in each of the three carbon-irradiated OSCC cell lines at all dose points compared with nonirradiated control cells. Among these, SPHK1, the expression of which was significantly upregulated by carbon ion irradiation, was modulated little by X-rays. The function of SPHK1 related to cellular growth and proliferation had the highest p value (p = 9.25e-7 to 2.19e-2). Real-time reverse transcriptase-polymerase chain reaction analysis showed significantly elevated SPHK1 expression levels after carbon ion irradiation (p < 0.05), consistent with microarray data. Clonogenic survival assay indicated that carbon ion irradiation could induce cell death in Ca9-22 cells more effectively than X-rays. Conclusions Our findings suggest that SPHK1 helps to elucidate the molecular mechanisms and processes underlying the biologic response to carbon ion beams in OSCC.

Higo, Morihiro [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan); Uzawa, Katsuhiro [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan) and Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, Chiba (Japan)]. E-mail: uzawak@faculty.chiba-u.jp; Kawata, Tetsuya [Department of Radiology, Graduate School of Medicine, Chiba University, Chiba (Japan); Kato, Yoshikuni [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan); Kouzu, Yukinao [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan); Yamamoto, Nobuharu [Department of Oral and Maxillo-Facial Surgery, Tokyo Dental College, Chiba (Japan); Shibahara, Takahiko [Department of Oral and Maxillo-Facial Surgery, Tokyo Dental College, Chiba (Japan); Mizoe, Jun-etsu [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Ito, Hisao [Department of Radiology, Graduate School of Medicine, Chiba University, Chiba (Japan); Tsujii, Hirohiko [Center of Excellence (COE) Program in the 21st Century, Graduate School of Medicine, Chiba University, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Tanzawa, Hideki [Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, Chiba (Japan); Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, Chiba (Japan); Center of Excellence (COE) Program in the 21st Century, Graduate School of Medicine, Chiba University, Chiba (Japan)

2006-07-01

210

Etch-free formation of porous silicon by high-energy ion irradiation  

SciTech Connect

In this study, porous silicon was fabricated without any chemical etching by self-ion implantation of crystalline Si performed at high temperature and at high fluences. The irradiated silicon samples, which remained crystalline under high temperature ion irradiation, exhibited an increased porous fraction with increasing sample temperature at a given fluence, up to the maximum tested temperature of 650 C. Extremely high ion fluences of at least 2 1018 ions/cm2 were necessary to produce significant void growth. Comparisons between the porous silicon structures and irradiation-induced porous networks in Ge, GaSb, and InSb are made, and differences in the formation conditions for these porous networks are discussed.

Perez-Bergquist, Dr. Alejandro G. [Los Alamos National Laboratory (LANL); Naab, Fabian U. [University of Michigan; Zhang, Yanwen [ORNL; Wang, Prof. Lumin [University of Michigan

2011-01-01

211

Etch-free Formation of Porous Silicon by High-energy Ion Irradiation  

SciTech Connect

In this study, porous silicon was fabricated without any chemical etching by self-ion implantation of crystalline Si performed at high temperature and at high fluences. The irradiated silicon samples, which remained crystalline under high temperature ion irradiation, exhibited an increased porous fraction with increasing sample temperature at a given fluence, up to the maximum tested temperature of 650º C. Extremely high ion fluences of at least 2 x 10¹? ions/cm² were necessary to produce significant void growth. Comparisons between the porous silicon structures and irradiation-induced porous networks in Ge, GaSb, and InSb are made, and differences in the formation conditions for these porous networks are discussed.

Perez-Bergquist, Alejandro G.; Naab, Fabian U.; Zhang, Yanwen; Wang, Lumin M.

2011-03-15

212

Three-stage structural modification of carbon nanotubes by swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

A study on the structural evolution of carbon nanotubes (CNTs) under irradiation by swift heavy ions (SHIs) of widely varying electronic energy loss (Se) values is presented. The control over Se is exercised through the choice of ion species used for irradiation. The ion beams used are those of nickel and gold with energies 60 and 120 MeV, respectively. Structural changes in CNTs were investigated qualitatively using Raman spectroscopy. Results of irradiation indicate that the structural modifications of CNTs can be broadly divided in three stages. At very low fluences the process of healing occurs; at intermediate fluences damage to the surface of CNTs predominates and nano-graphitic formations are seen; at very high fluences, of the order of 1 × 1014 ions/cm2, the system becomes amorphous. The stable nature of single walled carbon nanotubes compared to multiwalled carbon nanotubes, is also established from the Raman spectroscopy results.

Jeet, Kiran; Jindal, V. K.; Bharadwaj, L. M.; Bhandari, Rajiv; Dharamvir, Keya

2012-08-01

213

Pattern-induced magnetic anisotropy in FePt thin films by ion irradiation  

SciTech Connect

The magnetic properties of FePt thin films have been modified by exposing the samples to irradiation of 4 MeV Cl{sup 2+} ions. Patterned magnetic films, without modified topographical profile, were fabricated by irradiating the films through a shadowing micrometric mask. The structural changes, ascribed to the ion-beam-induced amorphization of the thin films, promote the modification of the magnetic anisotropy. In particular, the out-of-plane component of the magnetization decreases simultaneously with an enhancement of in-plane anisotropy by increasing ion fluence. Moreover, the nonirradiated regions present unexpected anisotropic behavior owing to the stray field of the irradiated regions. The control of this effect, which can have unwished consequences for the patterning of magnetic properties by ion bombardment, needs to be suitably addressed.

Jaafar, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain); Dpto. Fisica de la Materia Condensada, UAM, ES-28049 Madrid (Spain); Sanz, R. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain); Nanoate SL, Poeta Rafael Morales 2, ES-28702 San Sebastian de los Reyes, Madrid (Spain); McCord, J. [Institute of Ion Beam Physics and Materials Research, FZD, D-01314 Dresden (Germany); Jensen, J. [Thin Film Physics, Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Schaefer, R. [Leibniz Institute for Solid State and Materials Research, IFW, Helmholtzstrasse 20, D-01069 Dresden (Germany); Vazquez, M.; Asenjo, A. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain)

2011-03-01

214

Temperature dependence of ion irradiation induced amorphization of zirconolite  

SciTech Connect

Zirconolite is one of the major host phases for actinides in various wasteforms for immobilizing high level radioactive waste (HLW). Over time, zirconolite's crystalline matrix is damaged by {alpha}-particles and energetic recoil nuclei recoil resulting from {alpha}-decay events. The cumulative damage caused by these particles results in amorphization. Data from natural zirconolites suggest that radiation damage anneals over geologic time and is dependant on the thermal history of the material. Proposed HLW containment strategies rely on both a suitable wasteform and geologic isolation. Depending on the waste loading, depth of burial, and the repository-specific geothermal gradient, burial could result in a wasteform being exposed to temperatures of between 100--450 C. Consequently, it is important to assess the effect of temperature on radiation damage in synthetic zirconolite. Zirconolite containing wasteforms are likely to be hot pressed at or below 1,473 K (1,200 C) and/or sintered at or below 1,623 K (1,350 C). Zirconolite fabricated at temperatures below 1,523 K (1,250 C) contains many stacking faults. As there have been various attempts to link radiation resistance to structure, the authors decided it was also pertinent to assess the role of stacking faults in radiation resistance. In this study, they simulate {alpha}-decay damage in two zirconolite samples by irradiating them with 1.5 MeV Kr{sup +} ions using the High Voltage Electron Microscope-Tandem User Facility (HTUF) at Argonne National Laboratory (ANL) and measure the critical dose for amorphization (D{sub c}) at several temperatures between 20 and 773 K. One of the samples has a high degree of crystallographic perfection, the other contains many stacking faults on the unit cell scale. Previous authors proposed a model for estimating the activation energy of self annealing in zirconolite and for predicting the critical dose for amorphization at any temperature. The authors discuss their results and earlier published data in relation to that model.

Smith, K. L.; Blackford, M. G.; Lumpkin, G. R.; Zaluzec, N. J.

1999-12-22

215

The first narrow-band XeCl-excilamp application for complex psoriasis curing  

NASA Astrophysics Data System (ADS)

Clinical efficiency estimation of XeCl-excilamp application for psoriasis curing in comparison with other methods of phototherapy for has been carried out for the first time. Curing psoriasis by XeCl-excilamp assistance is shown to be an effective and present-date method. Such a phototherapy advantages suggested are the good tolerance, and absence of intact skin irradiation. The use of chemicals is no longer relevant, and the total doze of irradiation happens to be rather low.

Dmitruck, Vadim S.; Sosnin, Edward A.; Obgol'tz, Irina A.

2006-05-01

216

In-situ Fe+ Ion Irradiation of an Oxide Dispersion Strengthened Steel  

NASA Astrophysics Data System (ADS)

Oxide Dispersion Strengthened (ODS) reduced activation ferritic steels are promising candidate materials for structural components of both nuclear fission and fusion reactors. However, when irradiated with energetic particles, they may suffer changes on their microstructures that degrade their mechanical performance. In-situ transmission electron microscopy studies on ion-irradiated ODS steels can give remarkable insights into fundamental aspects of radiation damage allowing dynamic observations of defect formation, mobilities, and interactions during irradiation. In this investigation, a commercially available PM2000 ODS steel was in-situ irradiated with 150 KeV Fe+ at room temperature and 700°C. These experiments showed that the oxide nanoparticles in these steels remain stable up to the higher irradiation dose (~ 1.5 dpa), and that these particles seem to be effective sinks for irradiation induced defects.

de Castro, V.; Briceno, M.; Jenkins, M. L.; Kirk, M.; Lozano-Perez, S.; Roberts, S. G.

2014-06-01

217

Microstructural and Mechanical Property Changes in Ion Irradiated Tunsgten  

E-print Network

on the sustainability of tungsten as a plasma facing material (PFM). During operation, PFM must withstand harsh conditions with combined effects from high temperature, mechanical stress, irradiation, transmutation, and the production of hydrogen (H) and helium (He...

General, Michael

2013-04-08

218

Morphological and biochemical responses of Oryza sativa L. (cultivar MR219) to ion beam irradiation*  

PubMed Central

Objective: Heavy ion beam, which has emerged as a new mutagen in the mutation breeding of crops and ornamental plants, is expected to result in the induction of novel mutations. This study investigates the morphological and biochemical responses of Oryza sativa toward different doses of carbon ion beam irradiation. Methods: In this study, the dry seeds of O. sativa were irradiated at 0, 20, 40, 60, 80, 100, and 120 Gy, followed by in-vitro germination under controlled conditions. Morphological and biochemical studies were conducted to investigate the morphological and physiological responses of O. sativa towards ion beam irradiation. Results: The study demonstrated that low doses (10 Gy) of ion beam have a stimulating effect on the height, root length, and fresh weight of the plantlets but not on the number of leaves. Meanwhile, doses higher than 10 Gy caused reductions in all the morphological parameters studied as compared to the control samples. The highest total soluble protein content [(2.11±0.47) mg/g FW] was observed in plantlets irradiated at 20 Gy. All irradiated plantlets were found to have 0.85% to 58.32% higher specific activity of peroxidase as compared to the control samples. The present study also revealed that low doses of ion beam (10 and 20 Gy) had negligible effect on the total chlorophyll content of O. sativa plantlets while 40 Gy had a stimulating effect on the chlorophyll content. Plantlets irradiated between 40 to 120 Gy were shown to be 0.38% to 9.98% higher in total soluble nitrogen content which, however, was not significantly different from the control samples. Conclusions: Carbon ion beam irradiation administered at low to moderate doses of 10 to 40 Gy may induce O. sativa mutants with superior characteristics. PMID:24302713

Ling, Anna Pick Kiong; Ung, Ying Chian; Hussein, Sobri; Harun, Abdul Rahim; Tanaka, Atsushi; Yoshihiro, Hase

2013-01-01

219

Biodamage via shock waves initiated by irradiation with ions  

PubMed Central

Radiation damage following the ionising radiation of tissue has different scenarios and mechanisms depending on the projectiles or radiation modality. We investigate the radiation damage effects due to shock waves produced by ions. We analyse the strength of the shock wave capable of directly producing DNA strand breaks and, depending on the ion's linear energy transfer, estimate the radius from the ion's path, within which DNA damage by the shock wave mechanism is dominant. At much smaller values of linear energy transfer, the shock waves turn out to be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion. PMID:23411473

Surdutovich, Eugene; Yakubovich, Alexander V.; Solov'yov, Andrey V.

2013-01-01

220

Binding of an electron by He and Xe  

NASA Astrophysics Data System (ADS)

A recent theoretical paper [Guo, Wrinn, and Whitehead, Phys. Rev. A 40, 6685 (1989)] predicted the existence of ground-state bound negative ions of all the noble gases. In addition, experimental observations [Haberland, Kolar, and Reiners, Phys. Rev. Lett. 63, 1219 (1989)] suggest the existence of long-lived Xe-. We have examined the cases of He- and Xe-. For He-, we employed Levinson's theorem in conjunction with published and reliable theoretical e-He elastic-scattering phase-shift results. For Xe-, we employed electron-correlation theory in conjunction with multiconfigurational Hartree-Fock and variational bound-state calculations of total energies. We conclude that these ions do not exist in a ground configuration.

Nicolaides, Cleanthes A.; Aspromallis, George

1991-08-01

221

Changes in volume fraction and magnetostriction of iron nanoparticles in silica under swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

Effects of swift heavy ions irradiation on silica films containing Fe under the form of solute ions or metal particles have been investigated, using electron spin resonance and magnetometry. The results indicate that electronic excitations induce the reduction of solute ions and the precipitation of metal particles when the Fe concentration is not too low. The hammering effect of ions on the silica matrix causes a tilt of easy magnetization axis when the volume fraction of particles is of a few percents, but this axis remains in the film plane for fraction over 10%.

Singh, F.; Avasthi, D. K.; Angelov, O.; Berthet, P.; Pivin, J. C.

2006-04-01

222

Automatic system for single ion/single cell irradiation based on Cracow microprobe  

NASA Astrophysics Data System (ADS)

Recently, the Cracow ion microprobe has found its new application as a single ion hit facility (SIHF), allowing precise irradiations of living cells by a controlled number of ions. The instrument enables a broad field of research, such as survival studies, adaptive response investigations, bystander effect, inverse dose-rate effect, low-dose hypersensitivity, etc. This work presents principles of construction and operation of the SIHF based on the Cracow microprobe. We discuss some crucial features of optical, positioning, and blanking systems, including self-developed software responsible for semiautomatic cell recognition, for precise positioning of cells, and for controlling the irradiation process. We also show some tests carried out to determine the efficiency of the whole system and of its segments. In addition, we present results of the first irradiation measurements performed with living cells.

Veselov, O.; Polak, W.; Lekki, J.; Stachura, Z.; Lebed, K.; Stycze?, J.; Ugenskiene, R.

2006-05-01

223

Ion Irradiation of High-Temperature Superconductors and Its Application for Nanopatterning  

NASA Astrophysics Data System (ADS)

Many of the cuprate high-temperature superconductors have transition temperatures well above the boiling point of liquid nitrogen and can be operated under technically viable cooling conditions. On the other hand, they have complex and sensitive crystallographic structures that impose severe restrictions for nano-patterning by the established methods. Ion irradiation of these materials offers a unique possibility to create a wide range of different defects and to tailor the electrical and superconducting properties. Depending on the species of ions used during the irradiation, their energy and fluence, nanoscale columnar pinning centres can be created that enhance the critical current, or randomly distributed point defects that change the superconducting properties. The various effects of ion bombardment on the structural and electrical properties of a representative high-temperature superconductor are reviewed with an emphasis on He+ irradiation with moderate energy and the prospects discussed to create nanostructures in thin films of these superconductors.

Lang, Wolfgang; Pedarnig, Johannes D.

224

Ion irradiation effects on the optical properties of tungsten oxide films  

NASA Astrophysics Data System (ADS)

The optical changes in amorphous WO 3 film prepared by reactive RF sputtering and irradiated by 200-800 keV oxygen ions were measured to study the relationship between coloration and energy deposition. The color centers were effectively created by ion irradiation with contributions from nuclear collisions and electronic energy loss. The increase in the absorption coefficient was reasonably explained by a first order reaction, whose production rate depended roughly on the total deposited energy. During heat treatment in air atmosphere, transmittance recovery started at 400 K and completed at 550 K. No significant difference was found among films irradiated by different incident energies; therefore indicating that the ion-induced damage structure is not strongly influenced by the type of energy loss.

Nagata, S.; Fujita, H.; Inouye, A.; Yamamoto, S.; Tsuchiya, B.; Shikama, T.

2010-10-01

225

First tests of the ion irradiation and implantation beamline at the CMAM  

NASA Astrophysics Data System (ADS)

The implantation and irradiation beamline of the Tandem ion accelerator of the Centro de Micro Análisis de Materiales (CMAM), in Madrid, has been recently completed with a beam sweep and monitoring system, and a cryostat/furnace. These new implementations convert the beamline into a versatile tool to implant ions, between H and Au2, in different materials with precise control of the sample temperature, which may be varied between -180 °C and 600 °C. The size of the swept area on target may be as large as 10 × 10 cm2. The implantation chamber also allows carrying out in situ or/and on line analyses during the irradiations by means of advanced optical measurements, as well as ion beam analyses (IBA). These advancements can be employed in novel applications such as the fabrication of optical waveguides and irradiation tests of structural and functional materials for future fusion reactors. The results of beam tests and first experiments are shown.

Jiménez-Rey, D.; Benedicto, M.; Muñoz-Martín, A.; Bachiller-Perea, D.; Olivares, J.; Climent-Font, A.; Gómez-Ferrer, B.; Rodríguez, A.; Narros, J.; Maira, A.; Álvarez, J.; Nakbi, A.; Zucchiatti, A.; de Aragón, F.; García, J. M.; Vila, R.

2014-07-01

226

Effects of heavy-ion and light-ion irradiation on the room temperature carrier dynamics of InGaAs/GaAs quantum wells  

NASA Astrophysics Data System (ADS)

The effects of irradiation by 59Ni+, 20Ne+, 4He+ and 1H+ ions on the carrier dynamics of InGaAs/GaAs quantum well heterostructures were studied using a femtosecond time-resolved up-conversion photoluminescence method. The carrier capture time for the light ions He+ and H+ was found to be almost independent of the irradiation dose, while for the irradiation with heavy ions Ni+ and Ne+ it decreases with the dose. The most efficient carrier collection into the quantum wells was observed for the Ne+-irradiated sample, with a shortest capture time of about 1 ps. The heavy-ion-irradiated samples exhibited the shortest decay times (lifetime of carriers), which were 0.54 ps for Ne+ and 0.62 ps for Ni+. Irradiation by light ions He+ and H+ was as effective as with the heavy ions in achieving the desired short lifetimes, but for similar nuclear energy deposition and penetration depth for each ion species in the sample, much higher ion doses needed to be applied for lighter ions than did Ne+ or Ni+ to yield the same carrier lifetime. When comparing the results of irradiation for the Ne+-irradiated sample with those of the Ni+-irradiated one, we conclude that although the carrier lifetime and ion doses were about the same for both the methods, the 20Ne+ ions are preferred over 59Ni+ due to the faster carrier capture dynamics and remarkably lower implantation energy (0.4 MeV versus 10 MeV) needed to obtain the desired irradiation induced effects.

Dhaka, V. D. S.; Tkachenko, N. V.; Lemmetyinen, H.; Pavelescu, E.-M.; Guina, M.; Tukiainen, A.; Konttinen, J.; Pessa, M.; Arstila, K.; Keinonen, J.; Nordlund, K.

2006-05-01

227

Correlation between the Atomic Alignment and the Alignment of XeX* (B, C) Rotation in the Reactions of Oriented Xe (3P2, MJ = 2) + Halogen (X)-Containing Molecules  

NASA Astrophysics Data System (ADS)

The polarization of the XeX* (B) and XeX* (C) emissions in the reactions of oriented Xe* (3P2, MJ = 2) + halogen (X)-containing molecules (CCl4, CF3Br, CF3I, CH3I, NF3) has been measured as a function of each magnetic MJ' substate in the collision frame. The parallel polarization of the XeX* (B, C) emissions to the relative velocity vector is commonly observed for all magnetic MJ' substates. The correlation between the atomic alignment (MJ') and the MJ'-dependent alignment (AMJ') of the XeX* (B, C) rotation is found to be extremely different between the XeX* (B) and XeX* (C) channels: For XeX* (B), AMJ' is highest for the MJ' = 0 state, except CCl4, whereas the |MJ'| = 2 states give the highest AMJ' for XeX* (C). Alternatively, the correlation between the configuration (LZ') of the inner 5p orbital and the LZ'-dependent alignment (ALZ') of the XeX* (B, C) rotations is revealed. The collision with |LZ'| = 1 causes a similar positive alignment ALZ' for the XeX* (B) and XeX* (C) channels. The alignment ALZ' at the collision with |LZ'| = 0 is extremely different between the XeX* (B) and XeX* (C) channels. The collision with LZ' = 0 induces no alignment of XeX* (C) except CF3I, that is, ALZ'=0 ? 0, whereas it induces the higher positive ALZ' of XeX* (B). The different MJ' dependence on the alignment of the XeX* (B, C) rotation between the XeX* (B) and XeX* (C) channels can be recognized as the change of reaction mechanism due to the difference in the favorable impact parameter for each MJ' state between the XeX* (B) and XeX* (C) channels, which reflects the ?' conservation in the course of ion-pair (Xe+-RX-) formation.

Ohoyama, H.; Yasuda, K.; Kasai, T.

2009-09-01

228

Infrared spectroscopic investigation of some polymers and polymer blend films irradiated by a Si ion beam  

Microsoft Academic Search

Films of polypropylene, polyimide, and a polymethyl methacrylate\\/polystyrene (PMMA\\/PS) blend were irradiated with a Si ion beam of 60 MeV. The infrared (IR) spectra of these samples before and after irradiation were recorded and, using the spectral information, some structural changes were investigated. The spectra indicated crosslinking in polypropylene, and stability, ordering and conformational changes in polyimide. Based on the

A. Varada Rajulu; R. Lakshminarayana Reddy; D. K. Avasthi; K. Asokan

2000-01-01

229

Defect clustering in copper, silver and aluminum during heavy-ion irradiations at low temperatures  

Microsoft Academic Search

Point defect clustering during heavy-ion irradiation at low temperature was investigated in copper, silver, and aluminum using electrical-resistivity measurements. Clustering effects were studied by determining the average recombination volume per Frenkel defect, V, as a function of defect concentration. Within single unoverlapped displacement cascades, the clustering increased with increased energy density in the cascades. For Ar-irradiated aluminum no clustering was

R. S. Averback; K. L. Merkle; L. J. Thompson

1980-01-01

230

Silicon ion irradiation effects on the magnetic properties of ion beam synthesized CoPt phase  

SciTech Connect

Ion beam mixing of Pt/Co bilayers using self ion (Pt{sup +}) beam results in formation of CoPt phase. Upon ion beam annealing the ion mixed samples using 4 MeV Si{sup +} ions at 300 deg. C, diffusion of Co towards the Pt/Co interface is observed. The Si{sup +} ion beam rotates the magnetization of the CoPt phase from in plane to out of plane of the film.

Balaji, S.; Amirthapandian, S.; Panigrahi, B. K.; Mangamma, G.; Kalavathi, S.; Gupta, Ajay; Nair, K. G. M. [Materials Science group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore.452 017 (India); Materials Science group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

2012-06-05

231

Low energy Ar+ ion irradiation induced surface modification in cadmium zinc telluride (CdZnTe)  

NASA Astrophysics Data System (ADS)

In this paper, we report on modifications in structural, stoichiometry, and optical properties of cadmium zinc telluride (CdZnTe) crystals due to 1 keV Ar+ ion irradiation as a function of ion fluence, using ion flux of 1.7 × 1017 ions cm-2 s-1. The CdZnTe crystals were irradiated at normal incidence, using fluence range of 8 × 1017-3 × 1019 ions cm-2. Atomic force microscopy studies show sequential change in surface structure as a function of ion fluence, from homogeneously populated nano-hole to micron sized holes on the entire CZT crystal surface. These holes are well geometrically defined and most of them are rectangular in shape. X-ray photoelectron spectroscopy studies show a reduction in Zn at % while Raman and photoluminescence studies show almost complete depletion of Te inclusions and slight red shifts, respectively, due to ion irradiations. Schottky diode radiation detectors fabricated from such defect free CZT crystals will show significantly higher energy resolution.

Tripathi, J. K.; Harilal, S. S.; Hassanein, A.

2014-09-01

232

Incorporation of the effect of the composite electric fields of molecular ions as a simulation tool for biological damage due to heavy ion irradiation II  

SciTech Connect

This paper presents a theoretical study of the DNA damage due to the effect of the composite electric fields of H{sub 2}O{sup +} ions produced from the irradiation of a heavy ion onto a cell. It is found that a much larger number of electrons, which are produced from electron impact ionization, is trapped near the track of an incident ion in the case of C{sup 6+} ion irradiation with the energy of 3 MeV/u than that of proton irradiation. Therefore, the irradiation of carbon ions may produce a larger number of cluster DNA damage than that in the irradiation of protons. This may lead to the understanding of relative biological effectiveness (RBE).

Moribayashi, Kengo [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7, Umemidai, Kizugawa-city, 619-0215 (Japan) and Faculty of Life and Medical Sciences, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe City, 610-0394 (Japan)

2012-07-11

233

Electron capture from H-2 to highly charged Th and Xe ions trapped at center-of-mass energies near 6 eV  

E-print Network

#. After production, they were ejected from EBIT by a fast linear ramp of the potential on the center drift tube. These ions were then extracted along the magnetic field lines at a potential near 4.5 kV. A particu- lar charge state q was selected from...#. After production, they were ejected from EBIT by a fast linear ramp of the potential on the center drift tube. These ions were then extracted along the magnetic field lines at a potential near 4.5 kV. A particu- lar charge state q was selected from...

Weinberg, G.; Beck, B. R.; Steiger, J.; Church, David A.; McDonald, J.; Schneider, D.

1998-01-01

234

Fabricating high-density magnetic storage elements by low-dose ion beam irradiation  

SciTech Connect

We fabricate magnetic storage elements by irradiating an antiferromagnetically coupled ferromagnetic/nonmagnetic/ferromagnetic trilayer by a low-dose ion beam. The irradiated areas become ferromagnetically coupled and are capable of storing information if their size is small enough. We employ Fe/Cr/Fe trilayers and a 30 keV focused Ga{sup +}-ion beam to demonstrate the working principle for a storage array with a bit density of 7 Gbit/in.{sup 2}. Micromagnetic simulations suggest that bit densities of at least two magnitudes of order larger should be possible.

Neb, R.; Sebastian, T.; Pirro, P.; Hillebrands, B. [Fachbereich Physik and Research Center Optimas, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 56, 67663 Kaiserslautern (Germany); Pofahl, S.; Schaefer, R. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung Dresden, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany); Reuscher, B. [Institut fuer Oberflaechen-und Schichtanalytik, IFOS, Trippstadter Strasse 120, 67663 Kaiserslautern (Germany)

2012-09-10

235

Effect of energetic ion irradiation on CdI2 films  

Microsoft Academic Search

The effect of energetic argon ion irradiation, using a 3.3 kJ pulsed\\u000a plasma focus device, is studied systematically on a 4H polytype\\u000a (002)-oriented CdI2 stoichiometric film having compressive residual\\u000a stress. The CdI2 films were exposed to energetic ions from the plasma\\u000a focus device at different distances from the top of the central\\u000a electrode. The irradiation was found to change the

R. S. Rawat; P. Arun; A. G. Vedeshwar; P. Lee; S. Lee

2004-01-01

236

Impacts of Ion Irradiation on Hafnium oxide-based Resistive Random Access Memory Devices  

NASA Astrophysics Data System (ADS)

The impacts of ion irradiation on so-called vacancy-change mechanism (VCM) and electrochemical-metallization mechanism (ECM) ReRAM devices based on HfO2 are investigated using various ion sources: H + (1 MeV), He+ (1 MeV), N+ (1 MeV), Ne+ (1.6 MeV) and Ar+ (2.75 MeV) over a range of total doses (105 -- 1011 rad(Si)) and fluences (1012 -- 1015 cm-2). VCM-ReRAM devices show robust resistive switching function after all irradiation experiments. VCM resistive switching parameters including set voltage (V set), reset voltage (Vreset), on-state resistance (R on) and off-state resistance (Roff) exhibited, in most cases, modest changes after irradiation. Decreases in forming voltage (Vf) and initial resistance (Rfresh) of fresh devices were observed after all irradiation experiments on VCM-ReRAM devices with the exception of Ar+ irradiation at the highest fluence (10 15 cm-2). In that case Rfresh increased by an order of magnitude. For VCM-ReRAM devices it was also observed that irradiation beyond a dose threshold of approximately 5 Grad(Si) could induce off-to-on state transition events. This behavior could lead to errors in a VCM-ReRAM memory system. ECM-ReRAM devices (based on HfO2) were also subjected to ion irradiation. Under proton irradiation ECM-ReRAM devices remained functional, but with relatively large positive variations (20-40%) in Vset, Vreset and Ron and large negative variations (˜ -60%) in Roff. In contrast to VCM HfO2-ReRAMs, ECM-based devices exhibited increased V f after irradiation, and no off-to-on transitions were observed. Interestingly, for ECM-ReRAM devices, high-fluence Ar irradiation resulted in a transition of the electrical conduction mechanism associated with the conductive filament forming process from a Poole-Frenkel conduction mechanism (pre-irradiation) to ionic conduction (post-Ar irradiation). ECM-ReRAM devices irradiated with lighter ions did not exhibit this effect. The different ion irradiation responses of the two types of HfO2-ReRAMs studied originate from their distinct switching mechanisms -- vacancy filament switching for VCM-ReRAMs and metal filament switching for ECM-ReRAMs -- which respond differently to the irradiation-induced changes in the vacancy/defect densities and crystallite structures in HfO2. SRIM (Stopping and Range of Ions in Matter) modeling was used to roughly estimate the density of irradiation-induced vacancies. These model results correlated well with experimental observations in terms of vacancy defect density thresholds sufficient to impact ReRAM switching behavior. Physical characterization of pre- and post-irradiation ReRAM devices using techniques including XRD, AES, SEM, EDS, and SIMS were also employed to support the modeling and electrical measurements. This work suggests that HfO2-based ReRAM devices are a promising candidate for space and nuclear applications requiring a 'radiation-hard' memory technology.

He, Xiaoli

237

The effect of microstructure in the morphology and kinetics of amorphization induced by ion irradiation  

SciTech Connect

NiTi was irradiated with Ni ions to study the rate of amorphization as a function of temperature and to determine the temperature cutoff for the crystalline-to-amorphous transition. A series of irradiations was conducted at different temperatures from ambient to 350{degree}C. Prior to irradiation, the specimens contained martensitic plates and austenitic (B2) regions. However, during irradiation at temperatures of 80{degree}C and higher, all the specimens were entirely austenitic. As expected, amorphization was delayed as the irradiation temperature was increased. The fraction of material that became amorphous after irradiation at 250{degree}C to a dose of 0.7 dpa was estimated to be 5 to 10%. Specimens irradiated at higher temperatures remained crystalline, even after doses as high as 4 dpa. Irrespective of the irradiation temperature, we found a non-uniform distribution of amorphous regions that exhibited a morphology closely resembling the shape of the martensitic plates that existed in the material prior to heating it to the irradiation temperature. These observations are discussed in terms of the influence of structural defects on the kinetics of amorphization. 21 refs., 6 figs.

Pedraza, D.F.; Maziasz, P.J.

1989-01-01

238

Ion irradiation induced enhancement of out-of-plane magnetic anisotropy in ultrathin Co films  

SciTech Connect

Ga{sup +} or He{sup +} irradiated MBE grown ultrathin films of sapphire/Pt/Co(d{sub Co})/Pt(d{sub Pt}) were studied using polar Kerr effect in wide ranges of both cobalt d{sub Co} and platinum d{sub Pt} thicknesses as well as ion fluences F. Two branches of increased magnetic anisotropy and enhanced Kerr rotation angle induced by Ga{sup +} or He{sup +} irradiation are clearly visible in two-dimensional (d{sub Co}, LogF) diagrams. Only Ga{sup +} irradiation induces two branches of out-of-plane magnetization state.

Mazalski, P.; Kurant, Z.; Maziewski, A. [Faculty of Physics, University of Bialystok, Bialystok (Poland); Liedke, M. O.; Fassbender, J. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Baczewski, L. T.; Wawro, A. [Institute of Physics, Polish Academy of Science, Warszawa (Poland)

2013-05-07

239

A comparative study of argon ion irradiated pristine and fluorinated single-wall carbon nanotubes  

SciTech Connect

Effect of Ar{sup +} ion irradiation on the structure of pristine and fluorinated single-wall carbon nanotubes (SWCNTs) was examined using transmission electron microscopy (TEM), Raman, and x-ray photoelectron spectroscopy (XPS). The TEM analysis revealed retention of tubular structures in both irradiated samples while Raman spectroscopy and XPS data indicated a partial destruction of nanotubes and formation of oxygen-containing groups on the nanotube surface. From similarity of electronic states of carbon in the irradiated pristine and fluorinated SWCNTs observed by XPS, it was suggested that defluorination of nanotubes proceeded with breaking of C-F bonds.

Fedoseeva, Yu. V.; Bulusheva, L. G.; Okotrub, A. V. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation); Vyalikh, D. V. [Institute of Solid State Physics, Dresden University of Technology, D-01062 Dresden (Germany); Fonseca, A. [NANOPART N.V., Kapeldreef 60, B-3001 Leuven (Belgium)

2010-12-14

240

Formation of nanoparticles by ion beam irradiation of thin films.  

PubMed

The possibility of fabricating nanoparticles by ion bombardment was investigated by the ion bombardment of indium films on oxide covered Si and Cr surfaces. The different masses of implanting specimen ensured the different energy transfer while the same Si substrate ensured the same thermal conductivity for the In and Cr layers. Chromium served as a reference for the effect of ion bombardment and as a substrate as well. The SRIM program was used to simulate the ion surface interaction process. The nanoparticles were detected by scanning electron microscopy (SEM). We found that the melting of the In layer results in the formation of nanoparticles of 50-300 nm diameter and 5-10 nm height. This method can be promising for nanoparticle formation of materials with low melting point. PMID:22905568

Baji, Z; Szanyo, A; Molnár, G; Tóth, A L; Peto, G; Frey, K; Kotai, E; Kaptay, G

2012-06-01

241

Mechanism of silica-metal mixing by ion irradiation  

Microsoft Academic Search

The application of ion-beam mixing to the doping of silica films with metals either in solution or in the form of nanoclusters requires a preliminary investigation of the mixing mechanisms. This was undertaken by means of RBS and XRD for Au, Pt, W, Ag and Cu films mixed with silica by 4.5 MeV Au or 200 keV Ar ions, at

J. C. Pivin; P. Colombo

1997-01-01

242

75 MeV boron ion irradiation studies on Si PIN photodiodes  

NASA Astrophysics Data System (ADS)

The highly sensitive silicon PIN photodiodes were fabricated to use in radiation environments. The Si PIN photodiodes are coated with 150 nm silicon dioxide (SiO2) as anti-reflective (AR) coating. The presence of AR coating on the performance of irradiated PIN photodiodes is studied up to a total dose of 10 Mrad. The effects of 75 MeV boron (B5+) ions and 60Co gamma radiation on the I-V, C-V and spectral responses of PIN photodiodes were studied systematically to understand the radiation tolerance of the devices. The 75 MeV B5+ irradiation results are compared with 60Co gamma irradiated results in the same dose range for 1 mm × 1 mm and 10 mm × 10 mm active area PIN photodiodes. The irradiation results show that the ion irradiated PIN photodiodes show more degradation when compared 60Co gamma irradiated devices. The irradiation results are presented in this paper and the possible mechanism behind the degradation of photodiodes is also discussed in the paper.

Prabhakara Rao, Y. P.; Praveen, K. C.; Rejeena Rani, Y.; Tripathi, Ambuj; Gnana Prakash, A. P.

2013-12-01

243

Anomalous Photoionization in Xe  

NASA Astrophysics Data System (ADS)

Photoionization (PI) cross sections are important components of the opacities that are necessary for the simulation of astrophysical and ICF plasmas. Most of PI cross sections (i) start abruptly at threshold and (ii) decrease as an inverse power (e.g.3^rd) of the photon energy. In the framework of the CRASH project [1] we computed Xe opacities with the STA code [2]. We observed that the PI cross section for the 4d shell has neither of these 2 characteristics. We explain this result as interference between the bound 4d wavefunction (wf), the photon, and the free electron wf. Similar, but less pronounced effects are seen for the 5d and 5p shells. Simplified models of PI not involving the actual wf would not show this effect and would probably be inaccurate.[4pt] [1] Doss, F. W., Drake, R. P., and Kuranz, C. C., High Ener. Dens. Phys. 6, 157-61.[0pt] [2] Busquet, M., Klapisch, M., Bar-Shalom, A., et al., Bull. Am. Phys. Soc. 55, 225 (2010).

Klapisch, Marcel; Busquet, Michel

2012-10-01

244

Static elasticity of cordierite I: Effect of heavy ion irradiation on the compressibility of hydrous cordierite  

NASA Astrophysics Data System (ADS)

The effect of ion beam irradiations on the elastic properties of hydrous cordierite was investigated by means of Raman and X-ray diffraction experiments. Oriented single crystals were exposed to swift heavy ions (Au, Bi) of various specific energies (10.0-11.1 MeV/u and 80 MeV/u), applying fluences up to 5 × 1013 ions/cm2. The determination of unit-cell constants yields a volume strain of 3.4 × 10-3 up to the maximum fluence, which corresponds to a compression of non-irradiated cordierite at ~480 ± 10 MPa. The unit-cell contraction is anisotropic ( e 1 = 1.4 ± 0.1 × 10-3, e 2 = 1.5 ± 0.1 × 10-3, and e 3 = 7 ± 1 × 10-4) with the c-axis to shrink only half as much as the axes within the ab-plane. The lattice elasticity for irradiated cordierite ( ? = 1 × 1012 ions/cm2) was determined from single-crystal XRD measurements in the diamond anvil cell. The fitted third-order Birch-Murnaghan equation-of-state parameters of irradiated cordierite ( V 0 = 1548.41 ± 0.16 Å3, K 0 = 117.1 ± 1.1 GPa, ? K/? P = -0.6 ± 0.3) reveal a 10-11 % higher compressibility compared to non-irradiated cordierite. While the higher compressibility is attributed to the previously reported irradiation-induced loss of extra-framework H2O, the anomalous elasticity as expressed by elastic softening ( ? {a/-1}, ? {b/-1}, ? {c/-1} = 397 ± 9, 395 ± 28, 308 ± 11 GPa, ?( ? -1)/? P = -4.5 ± 2.7, -6.6 ± 8.4, -5.4 ± 3.0) appears to be related to the framework stability and to be independent of the water content in the channels and thus of the ion beam exposure.

Miletich, R.; Scheidl, K. S.; Schmitt, M.; Moissl, A. P.; Pippinger, T.; Gatta, G. D.; Schuster, B.; Trautmann, C.

2014-09-01

245

Tuning the surface properties of hydrogel at the nanoscale with focused ion irradiation.  

PubMed

With the site-specific machining capability of Focused Ion Beam (FIB) irradiation, we aim to tailor the surface morphology and physical attributes of biocompatible hydrogel at the nano/micro scale particularly for tissue engineering and other biomedical studies. Thin films of Gtn-HPA/CMC-Tyr hydrogels were deposited on a gold-coated substrate and were subjected to irradiation with a kiloelectronvolt (keV) gallium ion beam. The sputtering yield, surface morphology and mechanical property changes were investigated using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Monte Carlo simulations. The sputtering yield of the hydrogel was found to be approximately 0.47 ?m(3) nC(-1) compared with Monte-Carlo simulation results of 0.09 ?m(3) nC(-1). Compared to the surface roughness of the pristine hydrogel at approximately 2 nm, the average surface roughness significantly increased with the increase of ion fluence with measurements extended to 20 nm at 100 pC ?m(-2). Highly packed submicron porous patterns were also revealed with AFM, while significantly decreased pore sizes and increased porosity were found with ion irradiation at oblique incidence. The Young's modulus of irradiated hydrogel determined using AFM force spectroscopy was revealed to be dependent on ion fluence. Compared to the original Young's modulus value of 20 MPa, irradiation elevated the value to 250 MPa and 350 MPa at 1 pC ?m(-2) and 100 pC ?m(-2), respectively. Cell culture studies confirmed that the irradiated hydrogel samples were biocompatible, and the generated nanoscale patterns remained stable under physiological conditions. PMID:25225831

Kim, Y; Abuelfilat, A Y; Hoo, S P; Al-Abboodi, A; Liu, B; Ng, Tuck; Chan, P; Fu, J

2014-11-14

246

Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation  

PubMed Central

We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer. PMID:24138985

2013-01-01

247

Microstructural evolution of CANDU spacer material Inconel X-750 under in situ ion irradiation  

NASA Astrophysics Data System (ADS)

Work on Inconel®Inconel® is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys.1 X-750 spacers removed from CANDU®CANDU® is a registered trademark of Atomic Energy of Canada Limited standing for ''CANada Deuterium Uranium''.2 reactors has shown that they become embrittled and there is development of many small cavities within the metal matrix and along grain boundaries. In order to emulate the neutron irradiation induced microstructural changes, heavy ion irradiations (1 MeV Kr2+ ions) were performed while observing the damage evolution using an intermediate voltage electron microscope (IVEM) operating at 200 kV. The irradiations were carried out at various temperatures 60-400 °C. The principal strengthening phase, ??, was disordered at low doses (˜0.06 dpa) during the irradiation. M23C6 carbides were found to be stable up to 5.4 dpa. Lattice defects consisted mostly of stacking fault tetrahedras (SFTs), 1/2<1 1 0> perfect loops and small 1/3<1 1 1> faulted Frank loops. The ratio of SFT number density to loop number density for each irradiation condition was found to be neither temperature nor dose dependent. Under the operation of the ion beam the SFT production was very rapid, with no evidence for further growth once formed, indicating that they probably formed as a result of cascade collapse in a single cascade. The number density of the defects was found to saturate at low dose (˜0.68 dpa). No cavities were observed regardless of the irradiation temperature between 60 °C and 400 °C for doses up to 5.4 dpa. In contrast, cavities have been observed after neutron irradiation in the same material at similar doses and temperatures indicating that helium, produce during neutron irradiation, may be essential for the nucleation and growth of cavities.

Zhang, He Ken; Yao, Zhongwen; Judge, Colin; Griffiths, Malcolm

2013-11-01

248

The Influence of High-Energy Lithium Ion Irradiation on Electrical Characteristics of Silicon and GaAs Solar Cells  

NASA Astrophysics Data System (ADS)

Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models.

Jayashree, B.; Ramani; Radhakrishna, M. C.; Agrawal, Anil; Khan, Saif Ahmad; Meulenberg, A.

2006-12-01

249

The Influence of High-Energy Lithium Ion Irradiation on Electrical Characteristics of Silicon and GaAs Solar Cells  

E-print Network

Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models.

B. Jayashree; Ramani; M. C. Radhakrishna; Anil Agrawal; Saif Ahmad Khan; A. Meulenberg

2006-10-20

250

Probability of divacancy trap production in silicon diodes exposed to focused ion beam irradiation  

NASA Astrophysics Data System (ADS)

We present ion beam induced charge (IBIC) measurements of the critical displacement damage dose Dd values and modeling of the probability of divacancy trap production in p+-n-n+ silicon diodes exposed to megaelectron volt energy ion beam irradiation. The normalized induced charge (Q0/Q) measured by He ion probe in tested silicon diodes irradiated by focused He, Li, O, and Cl ion beams with energies of about 0.3 MeV/u increases linearly with Dd according to the modified radiation damage function and nonionizing energy loss (NIEL) theory. A simple IBIC model based on Gunn theorem showed clear dependence of the induced charge Q and corresponding equivalent damage factor Ked value on both a depth profile of charge created by ionizing particle (probe) and a depth distribution of stable defects created from primary defects produced by damaging ions. The average probability of the divacancy production (defined as the ratio of the final electrical active defect quantity and primary ion induced vacancy quantity for each impinging ion) of 0.18 (18%) was calculated by the IBIC modeling for all damaging ions.

Pastuovi?, Željko; Vittone, Ettore; Capan, Ivana; Jakši?, Milko

2011-02-01

251

Luminescence characteristics of Xe{sub 2}Cl excimer molecules under pumping the dense Xe-CCl{sub 4} gas mixtures with a pulsed electron beam  

SciTech Connect

Temporal and spectral characteristics of the luminescence of dense Xe-CCl{sub 4} gas mixtures of different composition, excited by a 5-ns pulsed electron beam, were measured. The energy of the electrons amounted to 150 keV and the electron beam current pulse amplitude was 5 A. The gas mixtures were used containing Xe (38-700 Torr) and CCl{sub 4} (0.03-0.3 Torr). The studies were performed within the wavelength range 200-1200 nm using a MAYA-2000Pro diffraction grating spectrometer and a RIGOL DS 5022 ME fast digital oscilloscope. The luminescence lifetimes of the excimer molecules XeCl* (band with {lambda}{sub max} = 308 nm) and Xe{sub 2}Cl* (band with {lambda}{sub max} = 486 nm) were measured, as well as the constants of quenching by the components of the gas mixture for Xe{sub 2}Cl* molecules. A model of plasma-chemical processes for dense Xe-CCl{sub 4} gas mixtures with a very low content of the CCl{sub 4} donor is proposed. It is shown that in such 'poor' mixtures Xe{sub 2}Cl* molecules are mainly produced as a result of recombination of the Xe{sub 2}{sup +} and Cl{sup -} ions. (active media)

Mis'kevich, A I; Jinbo, Guo [National Research Nuclear University 'Moscow Engineering Physics Institute', Moscow (Russian Federation)] [National Research Nuclear University 'Moscow Engineering Physics Institute', Moscow (Russian Federation)

2013-05-31

252

Electrical conductivity increase of Al-doped ZnO films induced by high-energy-heavy ions  

NASA Astrophysics Data System (ADS)

We have investigated the effects on electrical properties of Al-doped ZnO (AZO) semiconductor films induced by 90 MeV Ni, 100 MeV Xe and 200 MeV Xe ions. The AZO films with c-axis orientation on SiO 2-glass substrate were prepared by using a RF-sputter-deposition method at 400 °C. We find that the conductivity increases by two order of magnitude under high-energy-heavy ion irradiation, as has already been observed for 100 keV Ne ion irradiation. We also find that the efficiency of the conductivity enhancement, which is defined as the conductivity increment per a unit of ion fluence, scales super-linearly with the electronic stopping power ( Se). The carrier density and mobility for unirradiated and irradiated AZO films are presented.

Sugai, H.; Matsunami, N.; Fukuoka, O.; Sataka, M.; Kato, T.; Okayasu, S.; Shimura, T.; Tazawa, M.

2006-09-01

253

Heats of Formation of XeF??, XeF??, XeF??, XeF??, XeF??,and XeF? from High Level Electronic Structure Calculations  

SciTech Connect

Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for XeF??, XeF??, XeF??, XeF??, and XeF? from coupled cluster theory (CCSD(T)) calculations with effective core potential correlation-consistent basis sets for Xe and including correlation of the nearest core electrons. Additional corrections are included to achieve near chemical accuracy of ±1 kcal/mol. Vibrational zero point energies were computed at the MP2 level of theory. Unlike the other neutral xenon fluorides, XeF? is predicted to be thermodynamically unstable with respect to loss of F? with the reaction calculated to be exothermic by 22.3 kcal/mol at 0 K. XeF?? is also predicted to be thermodynamically unstable with respect to the loss of F? by 24.1 kcal/mol at 0 K. For XeF??, XeF??, XeF??, XeF?? and XeF??, the reactions for loss of F? are endothermic by 14.8, 37.8, 38.2, 59.6, and 31.9 kcal/mol at 0 K, respectively. The F? affinities of Xe, XeF?, XeF?, and XeF? are predicted to be 165.1, 155.3, 172.7, and 132.5 kcal/mol, and the corresponding F? affinities are 6.3, 19.9, 59.1, and 75.0 kcal/mol at 0 K, respectively.

Grant, Daniel J.; Wang, Tsang-Hsiu; Dixon, David A.; Christe, Karl O.

2010-01-04

254

Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties  

SciTech Connect

A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NC) of Fe core-Fe3O4 shell or fully oxidized Fe3O4. Films of these NC on Si(100) or MgO(100)/Fe3O4(100) were irradiated to 1016 Si2+/cm2 near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the nanocluster films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.

McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor; Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You; Burks, Edward; Liu, Kai

2013-08-23

255

Comparative Study of Structural Damage Under Irradiation in SiC Nano-structured and Conventional Ceramics  

SciTech Connect

In the context of research on new materials for next generation nuclear reactors, it becomes more and more interesting to know what can be the advantages of nano-structured materials for such applications. In this study, we performed irradiation experiments on micro-structured and nano-structured {beta}-SiC samples, with 95 MeV Xe and 4 MeV Au ions. The structure of the samples was characterized before and after irradiation by grazing incidence X-ray diffraction and Raman spectroscopy. The results showed the occurrence of a synergy between electronic and nuclear energy loss in both samples with 95 MeV Xe ions, while the nano-structured pellet was found to have a better resistance to the irradiation with 4 MeV Au ions. (authors)

Leconte, Yann; Herlin-Boime, Nathalie; Reynaud, Cecile [dsm/drecam/spam, CEA, Gif sur Yvette (France); Monnet, Isabelle [dsm/drecam/ciril, CEA, Caen (France); Levalois, Marc; Morales, Magali; Portier, Xavier [SIFCOM, CNRS-Universite de Caen, Caen (France); Thome, Lionel [CSNSM, CNRS, Orsay (France)

2008-07-01

256

Atomistic modeling of nanoscale patterning of L1{sub 2} order induced by ion irradiation  

SciTech Connect

Theoretical predictions indicate that ordered alloys can spontaneously develop a steady-state nanoscale microstructure when irradiated with energetic particles. This behavior derives from a dynamical competition between disordering in cascades and thermally activated reordering, which leads to self-organization of the chemical order parameter. We test this possibility by combining molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations. We first generate realistic distributions of disordered zones for Ni{sub 3}Al irradiated with 70 keV He and 1 MeV Kr ions using MD and then input this data into KMC to obtain predictions of steady state microstructures as a function of the irradiation flux. Nanoscale patterning is observed for Kr ion irradiations but not for He ion irradiations. We illustrate, moreover, using image simulations of these KMC microstructures, that high-resolution transmission electron microscopy can be employed to identify nanoscale patterning. Finally, we indicate how this method could be used to synthesize functional thin films, with potential for magnetic applications.

Ye Jia [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Lawrence Berkeley Laboratory, Berkeley, California 94720-8250 (United States); Li Youhong [Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Engineered Material Arresting Systems, Zodiac Aerospace, Logan Township, New Jersey 08085 (United States); Averback, Robert; Zuo Jianmin [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Bellon, Pascal [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2010-09-15

257

Structural behavior of ?-thorium phosphate diphosphate (?-TPD) irradiated with ion beams  

NASA Astrophysics Data System (ADS)

?-thorium phosphate diphosphate ceramic (?-TPD), ?-Th 4(PO 4) 4P 2O 7, was proposed as a potential actinide-bearing phase for nuclear waste storage. Self-irradiation by ?-decays, due to the actinide loading, could affect the good intrinsic performances of this material. The evaluation of irradiation effects on the chemical durability of the ceramic is a crucial issue. Radiation effects were simulated by external ion beam irradiations. Under high-energy ion irradiation, amorphization was achieved above a critical threshold for electronic energy loss ( Se = 5 MeV ?m -1). Thermal annealing enables to fully recover the initial crystalline structure after heating for 15 h above 973 K. Amorphization appears thus completely reversible. The activation energy of annealing is equal to 2.8 eV. Ion beam induced amorphization and recrystallization by thermal annealing were found to be isotropic processes. Irradiations in the nuclear stopping regime lead to a complete amorphization of ?-TPD at a critical dose of 0.2 dpa.

Tamain, C.; Garrido, F.; Thomé, L.; Dacheux, N.; Özgümüs, A.

2008-02-01

258

Effects of ion irradiation on the mechanical properties of several polymers  

NASA Astrophysics Data System (ADS)

The effects of high-energy ion irradiation (8 MeV protons, 30 MeV He 2+, 80 MeV C 4+, and N 4+) on the tensile properties of polymers were studied under conditions in which ions should pass completely through the specimen and the results were compared with 2 MeV electron irradiation effects. Experiments were carried out on polymers having various constituents and molecular structures, i.e. eight aliphatic polymers and four aromatic polymers. In the aliphatic polymers studied (PE, PP, PVdF, ETFE, EVA, nylon-6, EPDM, and PE-TPE), there was scarcely any difference in the dose dependence of the tensile strength and ultimate elongation between proton and electron irradiation. In aromatic polymers (PET, PES, U-PS, and U-polymer), however, the decrements in the tensile strength and ultimate elongation vs proton dose were less than those for electron irradiation. In heavy-ion irradiation, the radiation damage of PE (an aliphatic polymer) decreased with increase of LET, but no obvious LET effects were observed in PES (an aromatic polymer).

Sasuga, Tsuneo; Kawanishi, Shunichi; Nishii, Masanobu; Seguchi, Tadao; Kohno, Isao

259

MeV H+ ion irradiation effect on the stoichiometry of polyethylene terephthalate films  

NASA Astrophysics Data System (ADS)

Appropriate experimental conditions have been chosen to investigate the influence of main H+ ion irradiation parameters on stoichiometry changes induced in polyethylene terephthalate (PET) thin films. Stacks of six self-supporting identical films were irradiated perpendicularly to the target surface. Thus, the irradiations were realized simultaneously at different values of the target electronic stopping power, ?+. Indeed, the initial H+ ion energy of 1.1 MeV incident on the front polymer film was degraded down to 0.48 MeV at the entrance of the rear stacked film, which corresponds to an increase of ?+ from ˜0.22 up to ˜0.41 MeV cm2 mg-1. Ion fluences in the range (0.05-4) × 1015 cm-2 corresponding to an ion dose interval 1.80-263 MGy were used. The (H, O, C) atomic surface densities of the PET polymeric films were quantitatively determined by IBA techniques using a 1.62 MeV deuteron beam leading to the following main results: for each target film stacked at a given position thus fixed ?+, the oxygen atomic density decreases linearly versus ion fluence, ?; for the different ?+, the hydrogen impoverishment of the PET target is insignificant below critical fluence ?c ˜ 1.5 × 1015 cm-2 and becomes substantial above ?c; for fixed ?, the hydrogen and oxygen atomic densities exhibit linear decreases versus ?+; all measured such data versus ? and ?+ merge together into a unique decreasing curve for each (H, O, C) polymer content element when represented in function of the H+ ion dose, D, tightly correlating the latter two parameters; the O content element release from the PET target appears to be the most important, followed by the H content depletion, while the target C content is least affected under H+ ion irradiation.

Abdesselam, M.; Muller, D.; Djebara, M.; Ouichaoui, S.; Chami, A. C.

2013-07-01

260

Activation energy spectra for annealing of ion irradiation induced defects in silica glasses  

E-print Network

Measurements were performed on 150 lm thick rectangular bulk alkali-borosilicate glass samples (6´23 mm2Activation energy spectra for annealing of ion irradiation induced defects in silica glasses T. van 407, 1098 SJ Amsterdam, The Netherlands Abstract In situ stress measurements were performed on alkali-borosilicate

Polman, Albert

261

Amorphization and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions  

NASA Astrophysics Data System (ADS)

In this article, we demonstrate that the thermal conductivity of nanostructured porous silicon is reduced by amorphization and also that this amorphous phase in porous silicon can be created by swift (high-energy) heavy ion irradiation. Porous silicon samples with 41%-75% porosity are irradiated with 110 MeV uranium ions at six different fluences. Structural characterisation by micro-Raman spectroscopy and SEM imaging show that swift heavy ion irradiation causes the creation of an amorphous phase in porous Si but without suppressing its porous structure. We demonstrate that the amorphization of porous silicon is caused by electronic-regime interactions, which is the first time such an effect is obtained in crystalline silicon with single-ion species. Furthermore, the impact on the thermal conductivity of porous silicon is studied by micro-Raman spectroscopy and scanning thermal microscopy. The creation of an amorphous phase in porous silicon leads to a reduction of its thermal conductivity, up to a factor of 3 compared to the non-irradiated sample. Therefore, this technique could be used to enhance the thermal insulation properties of porous Si. Finally, we show that this treatment can be combined with pre-oxidation at 300 °C, which is known to lower the thermal conductivity of porous Si, in order to obtain an even greater reduction.

Newby, Pascal J.; Canut, Bruno; Bluet, Jean-Marie; Gomès, Séverine; Isaiev, Mykola; Burbelo, Roman; Termentzidis, Konstantinos; Chantrenne, Patrice; Fréchette, Luc G.; Lysenko, Vladimir

2013-07-01

262

Amorphization and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions  

SciTech Connect

In this article, we demonstrate that the thermal conductivity of nanostructured porous silicon is reduced by amorphization and also that this amorphous phase in porous silicon can be created by swift (high-energy) heavy ion irradiation. Porous silicon samples with 41%-75% porosity are irradiated with 110 MeV uranium ions at six different fluences. Structural characterisation by micro-Raman spectroscopy and SEM imaging show that swift heavy ion irradiation causes the creation of an amorphous phase in porous Si but without suppressing its porous structure. We demonstrate that the amorphization of porous silicon is caused by electronic-regime interactions, which is the first time such an effect is obtained in crystalline silicon with single-ion species. Furthermore, the impact on the thermal conductivity of porous silicon is studied by micro-Raman spectroscopy and scanning thermal microscopy. The creation of an amorphous phase in porous silicon leads to a reduction of its thermal conductivity, up to a factor of 3 compared to the non-irradiated sample. Therefore, this technique could be used to enhance the thermal insulation properties of porous Si. Finally, we show that this treatment can be combined with pre-oxidation at 300 Degree-Sign C, which is known to lower the thermal conductivity of porous Si, in order to obtain an even greater reduction.

Newby, Pascal J. [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Institut Interdisciplinaire d'Innovation Technologique (3IT), Universite de Sherbrooke, CNRS UMI-LN2, Sherbrooke, Quebec J1K0A5 (Canada); Canut, Bruno; Bluet, Jean-Marie; Lysenko, Vladimir [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Gomes, Severine [Centre de Thermique de Lyon, Universite de Lyon, CETHIL-UMR5008, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Isaiev, Mykola; Burbelo, Roman [Faculty of Physics, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrs'ka St., Kyiv 01601 (Ukraine); Termentzidis, Konstantinos [Laboratoire LEMTA, Universite de Lorraine-CNRS UMR 7563, 54506 Vandoeuvre-les-Nancy cedex (France); Chantrenne, Patrice [Universite de Lyon, INSA de Lyon, MATEIS-UMR CNRS 5510, Villeurbanne 69621 (France); Frechette, Luc G. [Institut Interdisciplinaire d'Innovation Technologique (3IT), Universite de Sherbrooke, CNRS UMI-LN2, Sherbrooke, Quebec J1K0A5 (Canada)

2013-07-07

263

Grain growth in ZrFe thin films during in situ ion irradiation in a TEM  

E-print Network

Laboratory, Argonne, IL 060493, USA Available online 2 November 2005 Abstract In situ ion-beam irradiation to the material from which a TEM sample is subsequently prepared to study grain growth. In this work we examine (for Rutherford Backscattering Spec- troscopy (RBS) characterization) using a dual gun system at a base

Motta, Arthur T.

264

Amorphization of -Thorium Phosphate Diphosphate (-TPD) irradiated with high energy krypton ions  

E-print Network

of nuclear wastes, the -Thorium Phosphate Diphosphate ceramic (-TPD), Th4(PO4)4P2O7, must be resistant as good candidates for nuclear waste immobilization [1-3]. Thorium Phosphate-Diphosphate (-TPD), -Th4(PO4Amorphization of -Thorium Phosphate Diphosphate (-TPD) irradiated with high energy krypton ions C

Paris-Sud XI, Université de

265

Carbon Ion Irradiation Inhibits Glioma Cell Migration Through Downregulation of Integrin Expression  

SciTech Connect

Purpose: To investigate the effect of carbon ion irradiation on glioma cell migration. Methods and Materials: U87 and Ln229 glioma cells were irradiated with photons and carbon ions. Migration was analyzed 24 h after irradiation. Fluorescence-activated cell sorting analysis was performed in order to quantify surface expression of integrins. Results: Single photon doses of 2 Gy and 10 Gy enhanced {alpha}{sub {nu}}{beta}{sub 3} and {alpha}{sub {nu}}{beta}{sub 5} integrin expression and caused tumor cell hypermigration on both vitronectin (Vn) and fibronectin (Fn). Compared to integrin expression in unirradiated cells, carbon ion irradiation caused decreased integrin expression and inhibited cell migration on both Vn and Fn. Conclusion: Photon radiotherapy (RT) enhances the risk of tumor cell migration and subsequently promotes locoregional spread via photon induction of integrin expression. In contrast to photon RT, carbon ion RT causes decreased integrin expression and suppresses glioma cell migration on both Vn and Fn, thus promising improved local control.

Rieken, Stefan, E-mail: Stefan.Rieken@med.uni-heidelberg.de [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Habermehl, Daniel; Wuerth, Lena [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Brons, Stephan [Heavy Ion Therapy Center, University Hospital of Heidelberg, Heidelberg (Germany); Mohr, Angela; Lindel, Katja; Weber, Klaus [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Haberer, Thomas [Heavy Ion Therapy Center, University Hospital of Heidelberg, Heidelberg (Germany); Debus, Juergen; Combs, Stephanie E. [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany)

2012-05-01

266

High electronic excitations and ion beam mixing effects in high energy ion irradiated Fe/Si multilayers  

SciTech Connect

M{umlt o}ssbauer spectroscopy ({sup 57}Fe) shows evidence for mixing effects induced by electronic energy deposition in nanoscale Fe/Si multilayers irradiated with swift heavy ions. A decrease in the mixing efficiency with electronic stopping power is reported; a threshold is found, under which iron environment modifications no longer occur. The kinetics of Fe{endash}Si phase formation after irradiation suggests the existence of three regimes: (i) for high excitation levels, a magnetic amorphous phase is formed directly in the wake of the incoming ion and an almost complete mixing is reached at low fluence (10{sup 13} U/cm{sup 2}); (ii) for low excitation levels, a paramagnetic Si-rich amorphous phase is favored at the interface while crystalline iron subsists at high fluences; (iii) for intermediate excitation levels, saturation effects are observed and the formation rate of both magnetic and paramagnetic phases points to direct mixing in the ion wake but with a reduced track length in comparison to U irradiation. The measured interfacial mixing cross section induced by electronic energy deposition suggests that a thermal diffusion process is mainly involved in addition to damage creation. {copyright} {ital 1997 American Institute of Physics.}

Bauer, P.; Dufour, C. [Laboratoire Metallurgie Physique et Science des Materiaux, Universite Henri Poincare Nancy-1, B.P. 239, 54506 Vandoeuvre Cedex (France)] [Laboratoire Metallurgie Physique et Science des Materiaux, Universite Henri Poincare Nancy-1, B.P. 239, 54506 Vandoeuvre Cedex (France); Jaouen, C. [Laboratoire Metallurgie Physique, Universite de Poitiers, 40 av. du Recteur Pineau, 86022 Poitiers Cedex (France)] [Laboratoire Metallurgie Physique, Universite de Poitiers, 40 av. du Recteur Pineau, 86022 Poitiers Cedex (France); Marchal, G. [Laboratoire Metallurgie Physique et Science des Materiaux, Universite Henri Poincare Nancy-1, B.P. 239, 54506 Vandoeuvre Cedex (France)] [Laboratoire Metallurgie Physique et Science des Materiaux, Universite Henri Poincare Nancy-1, B.P. 239, 54506 Vandoeuvre Cedex (France); Pacaud, J.; Grilhe, J. [Laboratoire Metallurgie Physique, Universite de Poitiers, 40 av. du Recteur Pineau, 86022 Poitiers Cedex (France)] [Laboratoire Metallurgie Physique, Universite de Poitiers, 40 av. du Recteur Pineau, 86022 Poitiers Cedex (France); Jousset, J.C. [C.I.R.I.L., B.P. 5133, 14040 Caen Cedex (France)] [C.I.R.I.L., B.P. 5133, 14040 Caen Cedex (France)

1997-01-01

267

In situ transmission electron microscopy and ion irradiation of ferritic materials.  

PubMed

The intermediate voltage electron microscope-tandem user facility in the Electron Microscopy Center at Argonne National Laboratory is described. The primary purpose of this facility is electron microscopy with in situ ion irradiation at controlled sample temperatures. To illustrate its capabilities and advantages a few results of two outside user projects are presented. The motion of dislocation loops formed during ion irradiation is illustrated in video data that reveals a striking reduction of motion in Fe-8%Cr over that in pure Fe. The development of extended defect structure is then shown to depend on this motion and the influence of nearby surfaces in the transmission electron microscopy thin samples. In a second project, the damage microstructure is followed to high dose (200 dpa) in an oxide dispersion strengthened ferritic alloy at 500 degrees C, and found to be qualitatively similar to that observed in the same alloy neutron irradiated at 420 degrees C. PMID:19189372

Kirk, Marquis A; Baldo, Peter M; Liu, Amelia C Y; Ryan, Edward A; Birtcher, Robert C; Yao, Zhongwen; Xu, Sen; Jenkins, Michael L; Hernandez-Mayoral, Mercedes; Kaoumi, Djamel; Motta, Arthur T

2009-03-01

268

Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine  

SciTech Connect

Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.

Rodriguez-Fernandez, Luis [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Mexico D.F., 01000 (Mexico)

2010-09-10

269

Effects of gamma irradiation on cobalt hexacyanoferrate(II) ion exchangers  

NASA Astrophysics Data System (ADS)

Study was made of the effects of ? irradiation doses of 2.1 and 5.0 MGy on the structure and cesium ion exchange properties of potassium cobalt hexacyanoferrate(II) and a composite ion exchanger, sodium cobalt hexacyanoferrate(II) in a chelating ion exchange resin. In the case of the potassium cobalt hexacyanoferrate only a slight increase in crystal size was observed. The composite exchanger withstood the lower dose, but at the higher dose the organic resin decomposed, leaving a residue of sodium cobalt hexacyanoferrate.

Lehto, J.; Szirtes, L.

1994-03-01

270

Modification and nano-patterning of high-Tc superconducting thin films by masked ion beam irradiation  

NASA Astrophysics Data System (ADS)

Ion irradiation of the high-temperature superconductor (HTS) YBa2Cu3O7 (Y-123) creates different types of defects depending on ion mass, energy and dose. Irradiation with helium ions of moderate energy (75 keV) primarily creates point defects. We measure in situ the modification of electrical transport properties of Y-123 thin films (thickness 310 nm) during ion irradiation. The He ions penetrate thin films and produce collision cascades with small lateral straggle that allow for patterning of nanostructures in the HTS layer. We present features smaller than 100 nm in size produced by masked ion beam irradiation of Y-123 films. Computer simulations indicate that nano-patterning of Y-123 thin films with 10 nm lateral resolution is achievable.

Bodea, M. A.; Pedarnig, J. D.; Siraj, K.; Behbood, N.; Bäuerle, D.; Lang, W.; Hasenfuss, C.; Palmetshofer, L.; Haselgrübler, K.; Kolarova, R.; Bauer, P.

2010-06-01

271

Iron ion irradiation increases promotes adhesion of monocytic cells to arterial vascular endothelium  

NASA Astrophysics Data System (ADS)

Radiation causes inflammation, and chronic, low-level vascular inflammation is a risk factor for atherosclerosis. Consistent with this, exposure to radiation from a variety of sources is associated with increased risk of heart disease and stroke. Part of the inflammatory response to radiation is a change in the adhesiveness of the endothelial cells that line the blood vessels, triggering inappropriate accumulation of leukocytes, leading to later, damaging effects of inflammation. Although some studies have been done on the effects of gamma irradiation on vascular endothelium, the response of endothelium to heavy ion radiation likely to be encountered in prolonged space flight has not been determined. We investigated how irradiation of aortic endothelial cells with iron ions affects adhesiveness of cultured aortic endothelial cells for monocytic cells and the consequences of this for development of atherosclerosis. Aortic endothelial cells were irradiated with 600 MeV iron ions at Brookhaven National Laboratory and adhesion-related changes were measured. Cells remained viable for at least 72 hours, and were even able to repair acute damage to cell junctions. We found that iron ion irradiation altered expression levels of specific endothelial cell adhesion molecules. Further, these changes had functional consequences. Using a flow chamber adhesion assay to measure adhesion of monocytic cells to endothelial cells under physiological shear stress, we found that adhesivity of vascular endothelium was enhanced in as little as 24 hours after irradiation. Further, the radiation dose dependence was not monotonic, suggesting that it was not simply the result of endothelial cell damage. We also irradiated aortic arches and carotid arteries of Apolipoprotein-E-deficient mice. Histologic analysis of these mice will be conducted to determine whether effects of radiation on endothelial adhesiveness result in consequences for development of atherosclerosis. (Supported by NSBRI: NCC-9-58-162)

Kucik, Dennis; Khaled, Saman; Gupta, Kiran; Wu, Xing; Yu, Tao; Chang, Polly; Kabarowski, Janusz

272

Swift heavy ion irradiation induced enhancement in the antioxidant activity and biocompatibility of polyaniline nanofibers  

NASA Astrophysics Data System (ADS)

Polyaniline (PAni) nanofibers doped with HCl and CSA have been irradiated with 90 MeV O7 + ions with fluence of 3 × 1010, 3 × 1011 and 1 × 1012 ions cm - 2. TEM micrographs show a decrease in the fiber diameter with increasing irradiation fluence, which has been explained on the basis of the Coulomb explosion model. XRD analysis reveals a decrease in the crystalline domain length and an increase in the strain. The increase in d-spacing for the (100) reflection with increasing irradiation fluence is ascribed to the increase in the tilt angle of the polymer chain, which is also evident from micro-Raman spectra. UV-vis spectra of the PAni nanofibers exhibit blue-shift in the absorption bands attributed to ?-?* band transitions indicating a reduction in particle size after SHI irradiation; as also observed in TEM micrographs. Micro-Raman spectra also reveal a transition from the benzenoid to quinoid structures in the PAni chain as the fluence is increased. Although the quinoid unit has no hydrogen for DPPH scavenging, the antioxidant activity of PAni nanofibers is found to increase with increasing fluence. This has been attributed to the availability of more reaction sites as a result of fragmentation of the PAni nanofibers which compensates for the benzenoid to quinoid transition after irradiation. The biocompatibility of the PAni nanofibers is also found to increase with increasing irradiation fluence, indicating the possibility of employing swift heavy ion irradiation as an effective technique in order to modify conducting polymer nanostructures for biomedical applications.

Kumar, A.; Banerjee, Somik; Saikia, Jyoti P.; Konwar, B. K.

2010-04-01

273

Changes in metal nanoparticle shape and size induced by swift heavy-ion irradiation  

NASA Astrophysics Data System (ADS)

Changes in the shape and size of Co, Pt and Au nanoparticles induced by swift heavy-ion irradiation (SHII) have been characterized using a combination of transmission electron microscopy, small-angle X-ray scattering and X-ray absorption near-edge structure. Elemental nanoparticles of diameters 2-15 nm were first formed in amorphous SiO 2 by ion implantation and thermal annealing and then irradiated at room temperature with 27-185 MeV Au ions as a function of fluence. Spherical nanoparticles below a minimum diameter (4-7 nm) remained spherical under SHII but progressively decreased in size as a result of dissolution into the SiO 2 matrix. Spherical nanoparticles above the minimum diameter threshold were transformed to elongated rods aligned with the ion beamdirection. The nanorod width saturated at an electronic energy deposition dependent value, progressively increasing from 4-6 to 7-10 nm (at 5-18 keV/nm, respectively) while the nanorod length exhibited a broad distribution consistent with that of the unirradiated spherical nanoparticles. The threshold diameter for spherical nanoparticle elongation was comparable to the saturation value of nanorod width. We correlate this saturation value with the diameter of the molten track induced in amorphous SiO 2 by SHII. In summary, changes in nanoparticle shape and size are governed to a large extent by the ion irradiation parameters.

Ridgway, M. C.; Kluth, P.; Giulian, R.; Sprouster, D. J.; Araujo, L. L.; Schnohr, C. S.; Llewellyn, D. J.; Byrne, A. P.; Foran, G. J.; Cookson, D. J.

2009-03-01

274

In situ luminescence as monitor of radiation damage under swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

In this paper, we discuss the results of recent ionoluminescence experiments concerning the study of radiation dose effects in ?-Al 2O 3, ?-Al 2O 3:Cr and LiF crystals under the irradiation with different swift heavy ions in a wide range of nuclear and electronic stopping powers. To monitor the lattice disorder in alumina and lithium fluoride, the luminescence of F-type centres have been used. It was shown that the degradation stage of the F + centre luminescence signal under 710 MeV Bi ion irradiation begins at a very low damage level and cannot be induced by defects produced by elastic collisions. The observed difference in the evolution of F3+-centre luminescence in LiF by swift heavy ions and conventional radiation is ascribed to the high local concentration of defects in the ion-track region. In experiments with ruby, we explored a well-known piezospectroscopic method for in situ monitoring of the build up and accumulation of mechanical stress under the irradiation with high-energy heavy ion. The obtained data strongly imply that the lattice disorder induced by collective electronic excitations plays a dominant role in generation of mechanical stress in the studied fluence range.

Skuratov, V. A.; Gun, Kim Jong; Stano, J.; Zagorski, D. L.

2006-04-01

275

Amorphization and recrystallization of single-crystalline hydrogen titanate nanowires by N+ ion irradiation  

NASA Astrophysics Data System (ADS)

We report on the phase transformation of hydrogen titanate (H2Ti3O7) nanowires induced by 50 keV N+ ion irradiation at room temperature with fluences of 1 × 1015 ions/cm2 and 1 × 1016 ions/cm2, respectively. Using transmission electron microscopy, the internal structure of the ion irradiated nanowires is analyzed. At low fluence, a transformation from crystalline H2Ti3O7 to amorphous TiO2 is observed. However, at higher fluence, a remarkable crystalline-amorphous TiO2 core-shell structure is formed. At this higher fluence, the recrystallization occurs in the core of the nanowire and the outer layer remains amorphous. The phase transformation and formation of core-shell structure are explained using the thermal spike model, radiation enhanced diffusion, and classical theory of nucleation and growth under non-equilibrium thermodynamics. X-ray photoelectron spectroscopy and Raman scattering reveal further insight into the structure of the nanowires before and after ion irradiation.

Behera, Akshaya K.; Facsko, Stefan; Bandyopadyay, Malay K.; Das, Siddhartha; Chatterjee, Shyamal

2014-06-01

276

Planar patterned media fabricated by ion irradiation into CrPt{sub 3} ordered alloy films  

SciTech Connect

Planar patterned media using CrPt{sub 3} ordered alloy films were fabricated by Ar{sup +} or Kr{sup +} ion irradiation through nanoimprinted or electron beam lithography made masks. CrPt{sub 3} ordered alloy film on fused quartz substrate exhibits a large perpendicular anisotropy of 5x10{sup 6} erg/cc and a large coercivity of 12 kOe, and we found that its magnetic order (magnetization) was completely suppressed by a quite low Ar{sup +} or Kr{sup +} ion dose of about 1-2x10{sup 14} ions/cm{sup 2}. Magnetic force microscope image of the ion-beam patterned CrPt{sub 3} with a bit size of 90x90 nm showed clear magnetic contrast in nonirradiated regions, while no magnetic contrast in irradiated regions. The read-back waveform taken from an ion-beam patterned CrPt{sub 3} disk with 600 nm patterning pitch showed sharp signal transition between irradiated and nonirradiated regions, which indicates the possibility of high-density planar patterned media using CrPt{sub 3} ordered alloy.

Kato, T.; Iwata, S. [Department of Quantum Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Yamauchi, Y.; Tsunashima, S. [Department of Electrical Engineering and Computer Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Matsumoto, K.; Morikawa, T. [Advanced Technology Department, Yamagata Fujitsu Ltd., 5400-2, Higashine-Ko, Higashine, Yamagata 999-3701 (Japan); Ozaki, K. [Storage Technologies Laboratory, Fujitsu Laboratories Ltd., 64, Nishiwaki, Akashi, Hyogo 674-8555 (Japan)

2009-04-01

277

Inactivation, DNA double strand break induction and their rejoining in bacterial cells irradiated with heavy ions  

NASA Technical Reports Server (NTRS)

Besides inactivation one of the major interests in our experiments is to study the primary damage in the DNA double strand breaks (DSB) after heavy ion irradiation. These damages lead not only to cell death but also under repair activities to mutations. In further experiments we have investigated the inactivation with two different strains of Deinococcus radiodurans (R1, Rec 30) and the induction of DSB as well as the rejoining of DSB in stationary cells of E. coli (strain B/r) irradiated with radiations of different quality. In the latter case irradiations were done so that the cell survival was roughly at the same level. We measured the DSB using the pulse field gelelectrophoresis which allows to separate between intact (circular) and damaged (linear) DNA. The irradiated cells were transferred to NB medium and incubated for different times to allow rejoining.

Schaefer, M.; Zimmermann, H.; Schmitz, C.

1994-01-01

278

RAPD analysis of mutants obtained by ion beam irradiation to hinoki cypress shoot primordia  

NASA Astrophysics Data System (ADS)

Mutants were induced by irradiation of the shoot primordia of Hinoki cypress with 50 MeV 4He 2+ heavy ion beam. Fresh shoot primordia on the CD medium in the plastic Petri dish (35 × 10 mm) were irradiated. Xanta mutants were induced from 38 to 266 Gy irradiation. Waxy mutants were induced from 76 to 266 Gy irradiation. Xanta, waxy and control type of regenerated Hinoki cypress in vitro were checked for their DNA level difference using RAPD analysis. Among 81 primers used, 23 primers produced the 68 bands. Among them stable 44 bands produced by 15 primers were compared between mutants and control plant. So far, there is no variation among the RAPD analysis band patterns of those mutants. Bigger test size may detect the gene variation specific for mutants.

Ishii, K.; Yamada, Y.; Hase, Y.; Shikazono, N.; Tanaka, A.

2003-05-01

279

Mechanisms of nanorod growth on focused-ion-beam-irradiated semiconductor surfaces: Role of redeposition  

SciTech Connect

We have examined the formation and evolution of irradiation-induced nanorod (NR) growth through a comparison of focused-ion-beam irradiation of InSb wafers and InSb/GaAs heterostructures. Above a critical ion dose, cone-shaped NRs capped with In islands form on both InSb surfaces. For InSb wafers, the NR base diameter increases with ion energy. In the case of InSb/GaAs heterostructures, as the milled depth approaches the InSb/GaAs interface, the cone-shaped NRs transition to capless NRs with a truncated cone shape. These results suggest a growth mechanism in which both the NR cap and body are supplied by redeposition of atoms sputtered from InSb.

Wu, J. H.; Goldman, R. S.

2012-01-30

280

Visualising discrete structural transformations in germanium nanowires during ion beam irradiation and subsequent annealing.  

PubMed

In this article we detail the application of electron microscopy to visualise discrete structural transitions incurring in single crystalline Ge nanowires upon Ga-ion irradiation and subsequent thermal annealing. Sequences of images for nanowires of varying diameters subjected to an incremental increase of the Ga-ion dose were obtained. Intricate transformations dictated by a nanowire's geometry indicate unusual distribution of the cascade recoils in the nanowire volume, in comparison to planar substrates. Following irradiation, the same nanowires were annealed in the TEM and corresponding crystal recovery followed in situ. Visualising the recrystallisation process, we establish that full recovery of defect-free nanowires is difficult to obtain due to defect nucleation and growth. Our findings will have large implications in designing ion beam doping of Ge nanowires for electronic devices but also for other devices that use single crystalline nanostructured Ge materials such as thin membranes, nanoparticles and nanorods. PMID:25231220

Kelly, Roisin A; Holmes, Justin D; Petkov, Nikolay

2014-10-01

281

Irradiation response in titanium modified austenitic stainless steels prepared by rapid solidification processing. Part II: Dual ion irradiations  

NASA Astrophysics Data System (ADS)

Dual ion irradiations have been performed on Path A PCA and other alloys with increased titanium and carbon content, prepared by rapid solidification processing. Comparison with the neutron response shows many points of similarity. The effect of the amount of Ti and C included, and its initial distribution, is investigated, as is the difference between fully processed material, including consolidation by hot-extrusion, and the as-rapidly-solidified alloy. It is shown that increased TiC content can be effective in controlling swelling both directly, and by increasing the microstructural stability.

Tong, C. H.; Imeson, D.; Megusar, J.; Vander Sande, J. B.; Grant, N. J.; Harling, O. K.

1984-05-01

282

Thermal properties of carbon ion beam-irradiated polycarbonate/polystyrene composite films  

NASA Astrophysics Data System (ADS)

The polycarbonate-polystyrene (PC-PS) composite films were prepared by solvent casting method and these composite films were irradiated by 55 MeV Carbon ions beam at fluences ranging from 1×1011 to 1×1013 ions/cm2. The effect of carbon ions beam on thermal properties of PC-PS composite has been investigated by differential scanning calorimetry (DSC) and thermally stimulated discharge current (TSDC) techniques. DSC and TSDC show that glass transition temperature decreases with increase in the ions fluences. TSDC is also show that the ? and ?-relaxation peaks shifted to lower temperature sides while activation energy, released charge and charge carrier mobility decrease while relaxation time and peak current increases with ion fluences.

Rathore, Bhupendra Singh; Gaur, M. S.; Singh, K. S.

2013-06-01

283

Visualising discrete structural transformations in germanium nanowires during ion beam irradiation and subsequent annealing  

NASA Astrophysics Data System (ADS)

In this article we detail the application of electron microscopy to visualise discrete structural transitions incurring in single crystalline Ge nanowires upon Ga-ion irradiation and subsequent thermal annealing. Sequences of images for nanowires of varying diameters subjected to an incremental increase of the Ga-ion dose were obtained. Intricate transformations dictated by a nanowire's geometry indicate unusual distribution of the cascade recoils in the nanowire volume, in comparison to planar substrates. Following irradiation, the same nanowires were annealed in the TEM and corresponding crystal recovery followed in situ. Visualising the recrystallisation process, we establish that full recovery of defect-free nanowires is difficult to obtain due to defect nucleation and growth. Our findings will have large implications in designing ion beam doping of Ge nanowires for electronic devices but also for other devices that use single crystalline nanostructured Ge materials such as thin membranes, nanoparticles and nanorods.In this article we detail the application of electron microscopy to visualise discrete structural transitions incurring in single crystalline Ge nanowires upon Ga-ion irradiation and subsequent thermal annealing. Sequences of images for nanowires of varying diameters subjected to an incremental increase of the Ga-ion dose were obtained. Intricate transformations dictated by a nanowire's geometry indicate unusual distribution of the cascade recoils in the nanowire volume, in comparison to planar substrates. Following irradiation, the same nanowires were annealed in the TEM and corresponding crystal recovery followed in situ. Visualising the recrystallisation process, we establish that full recovery of defect-free nanowires is difficult to obtain due to defect nucleation and growth. Our findings will have large implications in designing ion beam doping of Ge nanowires for electronic devices but also for other devices that use single crystalline nanostructured Ge materials such as thin membranes, nanoparticles and nanorods. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04513k

Kelly, Roisin A.; Holmes, Justin D.; Petkov, Nikolay

2014-10-01

284

AT cells show dissimilar hypersensitivity to heavy-ion and X-rays irradiation.  

PubMed

Ataxia telangiectasia (AT) cells, with their defective double-strand break (DSB) repair processes, exhibit high sensitivity to low-LET radiation such as X-rays irradiation and gamma beams. Since heavy ion beam treatment for cancer is becoming increasingly common in Japan and elsewhere, it is important to also determine their sensitivity to high-LET radiation. For this purpose we irradiated AT and normal human cells immortalized with the human telomerase gene using high- (24-60 keV/microm carbon and 200 keV/microm iron ions) or low-LET (X-rays) radiation in non-proliferative conditions. In normal cells the RBE (relative biological effectiveness) of carbon and iron ions increased from 1.19 to 1.81 in proportion to LET. In contrast, their RBE in AT cells increased from 1.32 at 24 keV/microm to 1.59 at 40 keV/microm, and exhibited a plateau at over 40 keV/microm. In normal cells most gamma-H2AX foci induced by both carbon- and iron-ion beams had disappeared at 40 h. In AT cells, however, a significant number of gamma-H2AX foci were still observed at 40 h. The RBEs found in the AT cells after heavy-ion irradiation were consistent with the effects predicted from the presence of non-homologous end joining defects. The DSBs remaining after heavy-ion irradiation suggested defects in the AT cells' DSB repair ability. PMID:20197645

Kitajima, Shoichiro; Nakamura, Hideaki; Adachi, Makoto; Ijichi, Kei; Yasui, Yoshihiro; Saito, Noriko; Suzuki, Masao; Kurita, Kenichi; Ishizaki, Kanji

2010-01-01

285

Microstructural evolution of P92 ferritic/martensitic steel under argon ion irradiation  

SciTech Connect

Microstructural evolution of P92 ferritic/martensitic steel irradiated by Ar{sup +} ion beams at doses from 0.6 to 230 displacements per atom (dpa) at room temperature was investigated with conventional transmission electron microscope technique. Selected-area electron diffraction combined with bright-field and dark-field contrast image indicated that carbide/matrix interfaces were more easily damaged. The carbide peripheries became partly amorphous at irradiation dose of 2.3 dpa and were almost complete amorphous at the dose of 11.5 dpa. The small carbides would re-precipitate in matrices at 34.5 dpa. Energy dispersive X-ray analysis revealed that segregation of Cr and W and depletion of Fe in carbides occurred under irradiation. With the irradiation dose increasing, the irradiation induced segregation and depletion became more severe, which would influence mechanical properties of the steel. - Research Highlights: {yields} Carbide/matrix interfaces in P92 ferritic/martensitic steel were easily damaged. {yields} Small carbides re-precipitated in matrices after higher dose irradiation. {yields} Segregation of Cr and W and depletion of Fe in carbides occurred after irradiation.

Jin, S.X. [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Guo, L.P., E-mail: guolp@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Yang, Z.; Fu, D.J.; Liu, C.S. [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Tang, R. [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chendu 610041 (China); Liu, F.H.; Qiao, Y.X.; Zhang, H.D. [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China)

2011-01-15

286

Cross-sectional TEM Observations of Si Wafers Irradiated With Gas Cluster Ion Beams  

SciTech Connect

Irradiation by a Gas Cluster Ion Beam (GCIB) is a promising technique for precise surface etching and planarization of Si wafers. However, it is very important to understand the crystalline structure of Si wafers after GCIB irradiation. In this study, the near surface structure of a Si (100) wafer was analyzed after GCIB irradiation, using a cross-sectional transmission electron microscope (XTEM). Ar-GCIB, that physically sputters Si atoms, and SF6-GCIB, that chemically etches the Si surface, were both used. After GCIB irradiation, high temperature annealing was performed in a hydrogen atmosphere. From XTEM observations, the surface of a virgin Si wafer exhibited completely crystalline structures, but the existence of an amorphous Si and a transition layer was confirmed after GCIB irradiation. The thickness of amorphous layer was about 30 nm after Ar-GCIB irradiation at 30 keV. However, a very thin (< 5 nm) layer was observed when 30 keV SF6-GCIB was used. The thickness of the transition layer was the same both Ar and SF6-GCIB irradiation. After annealing, the amorphous Si and transition layers had disappeared, and a complete crystalline structure with an atomically smooth surface was observed.

Isogai, Hiromichi; Toyoda, Eiji; Senda, Takeshi; Izunome, Koji [Processing Technology, Silicon Business Group, TOSHIBA CERAMICS CO., LTD. 6-861-5 Higashikou, Seiroumachi Kitakanbaragun, Niigata (Japan); Kashima, Kazuhiko [New Buisness Creation, TOSHIBA CERAMICS CO., LTD. 30 Soya, Hadano City, Kanagawa (Japan); Toyoda, Noriaki; Yamada, Isao [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Hyogo (Japan)

2006-11-13

287

Lifetime Measurements in 120Xe  

E-print Network

Lifetimes for the lowest three transitions in the nucleus $^{120}$Xe have been measured using the Recoil Distance Technique. Our data indicate that the lifetime for the $2_{1}^{+} \\to 0_{1}^{+}$ transition is more than a factor of two lower than the previously adopted value and is in keeping with more recent measurements performed on this nucleus. The theoretical implications of this discrepancy and the possible reason for the erroneous earlier results are discussed. All measured lifetimes in $^{120}$Xe, as well as the systematics of the lifetimes of the 2$_{1}^{+}$ states in Xe isotopes, are compared with predictions of various models. The available data are best described by the Fermion Dynamic Symmetry Model (FDSM).

J. C. Walpe; B. F. Davis; S. Naguleswaran; W. Reviol; U. Garg; Xing-Wang Pan; Da Hsuan Feng; J. X. Saladin

1995-03-25

288

Structural Modification of Single Wall and Multiwalled Carbon Nanotubes under Carbon, Nickel and Gold Ion Beam Irradiation  

NASA Astrophysics Data System (ADS)

Thin film samples of carbon nanotubes were irradiated with ion beam of carbon, nickel and gold. The irradiation results were characterized using Raman Spectroscopy. Modifications of the disorder mode (D mode) and the tangential mode (G mode) under different irradiation fluences were studied in detail. Raman results of carbon ion beam indicate the interesting phenomenon of ordering of the system under irradiation. Under the effect of nickel and gold ion irradiation, the structural evolution of CNTs occurs in three different stages. At lower fluences the process of healing occurs; at intermediate fluences damages on the surface of CNTs occurs and finally at very high fluences of the order of 1×1014 ions/cm2 the system gets amorphised.

Jeet, Kiran; Jindal, V. K.; Bharadwaj, L. M.; Dharamvir, Keya

2011-12-01

289

Effects of carbon-ion beam irradiation on the angiogenic response in lung adenocarcinoma A549 cells.  

PubMed

Radiotherapy has been focused mainly on killing cancer cells, and little attention has been paid to the process supporting tumor growth and metastasis, including the process of angiogenesis. To investigate the effects of carbon-ion irradiation on angiogenesis in lung cancer cells, we examined the expression of vascular endothelial growth factor and basic fibroblast growth factor in the tumor conditioned medium (TCM) of A549 cells exposed to carbon-ion or X-ray irradiation, as well as endothelial cell growth, invasion, and tube formation induced by TCM. No changes in vascular endothelial growth factor secretion were detected in the TCM of A549 cells exposed to carbon-ion irradiation at 2 or 4?Gy, whereas 1?Gy of irradiation significantly decreased vascular endothelial growth factor and basic fibroblast growth factor levels. Carbon-ion irradiation at 1?Gy inhibited endothelial cell invasion and tube formation. The TCM from A549 cells irradiated with X-ray promoted angiogenesis, whereas the TCM of A549 cells exposed to carbon-ion irradiation at 2 or 4?Gy had no effect. These findings suggest that carbon-ion irradiation at 1?Gy significantly suppressed the process of angiogenesis in vitro by inhibiting endothelial cell invasion and tube formation, which are related to vascular endothelial growth factor and basic fibroblast growth factor production. PMID:24942319

Liu, Yuanyuan; Liu, Yang; Zhang, Hong; Sun, Chao; Zhao, Qiuyue; Di, Cixia; Li, Hongyan; Gan, Lu; Wang, Yali

2014-11-01

290

Investigation of hydrogen concentration and hardness of ion irradiated organically modified silicate thin films  

NASA Astrophysics Data System (ADS)

A study of the effects of ion irradiation of organically modified silicate thin films on the loss of hydrogen and increase in hardness is presented. NaOH catalyzed SiNa wO xC yH z thin films were synthesized by sol-gel processing from tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) precursors and spin-coated onto Si substrates. After drying at 300 °C, the films were irradiated with 125 keV H + or 250 keV N 2+ at fluences ranging from 1 × 10 14 to 2.5 × 10 16 ions/cm 2. Elastic Recoil Detection (ERD) was used to investigate resulting hydrogen concentration as a function of ion fluence and irradiating species. Nanoindentation was used to measure the hardness of the irradiated films. FT-IR spectroscopy was also used to examine resulting changes in chemical bonding. The resulting hydrogen loss and increase in hardness are compared to similarly processed acid catalyzed silicate thin films.

Qi, Y.; Prenzel, T.; Harriman, T. A.; Wang, Y. Q.; Lucca, D. A.; Williams, D.; Nastasi, M.; Dong, J.; Mehner, A.

2010-06-01

291

Effect of electrode material on the photoconduction behaviour of ion-irradiated kapton-H polyimide  

NASA Astrophysics Data System (ADS)

Photoconduction behaviour of 75 MeV oxygen ion-irradiated (fluence: 1.8×1013 ions/cm2) kapton-H polyimide film in the visible region has been investigated for different electrode materials at various operating temperatures ranging 40-250 °C and at different electric fields (40-400 kV/cm). A photoinduced exciton formation is the major source for providing charge carriers through thermolization and field-assisted dissociation processes. A decrease in the photocurrent in ion-irradiated samples when compared with pristine samples has been associated with the enhancement in the trapping sites, which may deplete the charge carriers and a loss in the photoactive groups owing to radiation-induced demerization. The evidence of Schottky type conduction (based on Schottky's coefficient estimation) mechanism in irradiated samples is observed at moderate temperatures (80-160 °C). A strong dependence of photocurrent on temperature in irradiated samples reconfirms the thermal ionization process of exciton for photogeneration of charge carriers.

Sharma, Anu; Quamara, J. K.

292

Microstructure evolution and hardness change in ordered Ni3V intermetallic alloy by energetic ion irradiation  

NASA Astrophysics Data System (ADS)

Ni3V bulk intermetallic compounds with ordered D022 structure were irradiated with 16 MeV Au ions at room temperature. The irradiation induced phase transformation was examined by means of the transmission electron microscope (TEM), the extended X-ray absorption fine structure measurement (EXAFS) and the X-ray diffraction (XRD). We also measured the Vickers hardness for unirradiated and irradiated specimens. The TEM observation shows that by the Au irradiation, the lamellar microstructures and the super lattice spot in diffraction pattern for the unirradiated specimen disappeared. This TEM result as well as the result of XRD and EXAFS measurements means that the intrinsic D022 structure of Ni3V changes into the A1 (fcc) structure which is the lattice structure just below the melting point in the thermal equilibrium phase diagram. The lattice structure change from D022 to A1 (fcc) accompanies a remarkable decrease in Vickers microhardness. The change in crystal structure was discussed in terms of the thermal spike and the sequential atomic displacements induced by the energetic heavy ion irradiation.

Hashimoto, A.; Kaneno, Y.; Semboshi, S.; Yoshizaki, H.; Saitoh, Y.; Okamoto, Y.; Iwase, A.

2014-11-01

293

Lattice preamorphization by ion irradiation: Fluence dependence of the electronic stopping power threshold for amorphization  

NASA Astrophysics Data System (ADS)

A thermal-spike model has been applied to characterize the damage structure of the latent tracks generated by high-energy ion irradiations on LiNbO3 through electron excitation mechanisms. It applies to ions having electronic stopping powers both below and above the threshold value for lattice amorphization. The model allows to estimate the defect concentrations in the heavily damaged (preamorphized) regions that have not reached the threshold for amorphization. They include the halo and tail surrounding the core of a latent track. The existence of the preamorphized regions accounts for a synergy between successive irradiations and predicts a dependence of the amorphization threshold on previous irradiation fluence. The predicted dependence is in accordance with irradiation experiments using N (4.53MeV ), O (5.00MeV), F (5.13MeV), and Si (5 and 7.5MeV). For electronic stopping powers above the threshold value the model describes the generation of homogeneous amorphous layers and predicts the propagation of the amorphization front with fluence. A theoretical expression, describing this propagation, has been obtained that is in reasonable agreement with silicon irradiation experiments at 5 and 7.5MeV. The accordance is improved by including in a simple phenomenological way the velocity effect on the threshold. At the highest fluences (or depths) a significant discrepancy appears that may be attributed to the contribution of the nuclear collision damage.

Agulló-López, F.; García, G.; Olivares, J.

2005-05-01

294

Irradiation effects in the storage and disposal of radioactive ion-exchange resins  

SciTech Connect

Research is under way to characterize the effects of self-irradiation on radwastes which may be generated when organic ion-exchange media are used in water demineralization or decontamination operations at nuclear facilities. External factors affecting the relation between laboratory evaluations and field performance are emphasized. Initial experiments do not yet indicate substantial radiation dose-rate effects on radiolytic gas yields or acid product formation, when (fully swollen) sulfonic acid resins are irradiated in a sealed air environment. At the same time, oxygen gas is removed from the environment of irradiated resins. Interaction between mild steel coupons and acidic species produced in the irradiation induced decomposition of sulfonic acid resin results in irradiation enhanced corrosion. Corrosion rates depend on radiation dose rate, moisture content and resin chemical loading. In some cases, corrosion rates decrease with time, suggesting depletion of acidic species within the resin bed, or a synergistic interaction between resin and corrosion coupon. Implications of these and other results on evaluating field behavior of radwaste containing ion-exchange media are discussed. 4 figures, 2 tables.

Swyler, K.J.; Dodge, C.E.; Dayal, R.; Weiss, A.J.

1982-01-01

295

Microstructure and Mechanical Properties of Ti3SiC2 Irradiated by Carbon Ions  

NASA Astrophysics Data System (ADS)

Thanks to its noteworthy mechanical properties, excellent damage tolerance and good thermal stability, the Ti3SiC2 ternary compound has attracted great concern and has been considered as a potential structural component material for the 4th generation of reactors (e.g., gas fast nuclear reactors) and future fusion reactors. The outstanding properties are due to the nanolamellar structure which imparts characteristics of both metals and ceramics to this material. In our work, Ti3SiC2 samples have been irradiated by C+ ions with a high fluence of 1.78 × 1017 ions/cm2 at a range of temperatures from 120°C-850°C. Subsequently, series of characterization techniques including synchrotron irradiation x-ray diffraction, scanning electron microscopy and nano-indentation are carried out to understand the changes of microstructure and mechanical properties. The composition exhibits high damage tolerant properties and a high recovery rate through the analysis, especially at high temperature. The minimum damage to an irradiated sample appears around 350°C in the temperature range 120°C-550°C. At a high irradiation temperature, a significant reduction in the damage can be achieved and an almost complete lack of damage compared with an un-irradiated sample is revealed at the temperature of 850°C.

Wang, Kun; Qi, Qiang; Cheng, Gui-Jun; Shi, Li-Qun

2014-07-01

296

Formation of complex precursors of amino acids by irradiation of simulated interstellar media with heavy ions  

NASA Astrophysics Data System (ADS)

A wide variety of organic compounds have been detected in such extraterrestrial bodies as meteorites and comets Amino acids were identified in the extracts from Murchison meteorite and other carbonaceous chondrites It is hypothesized that these compounds are originally formed in ice mantles of interstellar dusts ISDs in molecular clouds by cosmic rays and ultraviolet light UV Formation of amino acid precursors by high energy protons or UV irradiation of simulated ISDs was reported by several groups The amino acid precursors were however not well-characterized We irradiated a frozen mixture of methanol ammonia and water with heavy ions to study possible organic compounds abiotically formed in molecular clouds by cosmic rays A mixture of methanol ammonia and water was irradiated with carbon beams 290 MeV u from a heavy ion accelerator HIMAC of National Institute of Radiological Sciences Japan Irradiation was performed either at room temperature liquid phase or at 77 K solid phase The products were characterized by gel filtration chromatography GFC FT-IR pyrolysis PY -GC MS etc Amino acids were analyzed by HPLC and GC MS after acid hydrolysis or the products Amino acids such as glycine and alanine were identified in the products in both the cases of liquid phase and solid phase irradiation Energy yields G-values of glycine were 0 014 liquid phase and 0 007 solid phase respectively Average molecular weights of the products were estimated as to 2300 in both the case Aromatic hydrocarbons N-containing heterocyclic

Kobayashi, K.; Suzuki, N.; Taniuchi, T.; Kaneko, T.; Yoshida, S.

297

Dynamic response of metals under high-intensity pulsed ion beam irradiation for surface modification  

NASA Astrophysics Data System (ADS)

A piezoelectric transducer based on lead-zirconte-titanate (PZT) piezoelectric ceramic thin plate was applied to characterize the stress waves in titanium targets under high-intensity pulsed ion beam (HIPIB) irradiation at a peak accelerating voltage of 350 kV and an ion current density up to 400 A/cm 2 with pulse duration of about 150 ns. The magnitude of recorded stress wave signals was increased along with the irradiation intensity, presenting a slow growth with a value below 100 V in the range of 200-300 A/cm 2, and then a rapid increase of about four times up to 400 A/cm 2. The measured stress waves were explained by space-time diagram analysis. The generation and propagation of the stress wave can be attributed to the coupled thermal-dynamic effects during HIPIB irradiation onto metallic targets, where the thermal shock due to ultra-fast heating/cooling process and the recoil impulse due to ablation process have a combined contribution to the induced stress waves, dependent on the irradiation intensity. It is indicated that a fast attenuation of stress wave proceeded during its propagation from the irradiated surface to the target/PZT interface. The large amount of energy delivered by the stress wave effectively converted and dissipated into plastic deformation and/or defects formation in target materials. The dynamic response of metallic materials under HIPIB irradiation accounts for the effective surface modification of metals and alloys into a depth well beyond the ion range.

Zhu, X. P.; Zhang, F. G.; Tang, Y.; Xin, J. P.; Lei, M. K.

2012-02-01

298

Laboratory studies of electron and ion irradiation of solid acetonitrile (CH?CN).  

PubMed

The structure and bonding of solid acetonitrile (CH?CN) films on amorphous silica are studied, and chemical and physical processes under irradiation with 200 keV protons and 250-400 eV electrons are quantified using transmission infrared spectroscopy, reflection-absorption infrared spectroscopy and temperature-programmed desorption, with the assistance of basic computational chemistry and nuclear materials calculations. The thermal desorption profiles are found to depend strongly on the balance between CH?CN-surface and CH?CN-CH?CN interactions, passing from a sub-monolayer regime (binding energy: 35-50 kJ mol?¹) to a multilayer regime (binding energy: 38.2±1.0 kJ mol?¹) via a fractional order desorption regime characteristic of islanding as the coverage increases. Calculations using the SRIM code reveal that the effects of the ion irradiation are dominated by electronic stopping of incident protons, and the subsequent generation of secondary electrons. Therefore, ion irradiation and electron irradiation experiments can be quantitatively compared. During ion irradiation of thicker CH?CN films, a cross section for secondary electron-promoted chemical destruction of CH3CN of 4 (±1) × 10?¹? cm² was measured, while electron-promoted desorption was not detected. A significantly higher cross section for electron-promoted desorption of 0.82-3.2 × 10?¹? cm² was measured during electron irradiation of thinner CH?CN films, while no chemical products were detected. The differences between the experimental results can be rationalized by recognizing that chemical reaction is a bulk effect in the CH?CN film, whereas desorption is a surface sensitive process. In thicker films, electron-promoted desorption is expected to occur a rate that is independent of the film thickness; i.e. show zeroth-order kinetics with respect to the surface concentration. PMID:23734051

Abdulgalil, A G M; Marchione, D; Thrower, J D; Collings, M P; McCoustra, M R S; Islam, F; Palumbo, M E; Congiu, E; Dulieu, F

2013-07-13

299

Annealing of the defects observed by Raman spectroscopy in UO2 irradiated by 25 MeV He2+ ions  

NASA Astrophysics Data System (ADS)

Understanding the effect of irradiation in UO2 is a major issue for nuclear industry and for the design of irradiation resistant materials. We have previously evidenced irradiation induced defects in UO2 that can be characterized by Raman spectroscopy. Here we present the Raman characterization of these defects as a function of temperature. UO2 samples were irradiated with 25 MeV He2+ ions at room temperature and then heated at different temperature without irradiation. Some samples were also irradiated at high temperature. Heat treatment after irradiation evidenced one annealing temperature on Raman spectra. This annealing temperature is shifted to higher values when the samples are simultaneously heat treated and irradiated. It is compared to the annealing temperatures that are reported in literature on irradiated UO2. This indicates that Raman observed defects would be point defects on uranium sublattice. This attribution is consistent with the one we previously proposed.

Desgranges, L.; Guimbretière, G.; Simon, P.; Duval, F.; Canizares, A.; Omnee, R.; Jégou, C.; Caraballo, R.

2014-05-01

300

Artificial ion tracks in volcanic dark mica simulating natural radiation damage: A scanning force microscopy study  

NASA Astrophysics Data System (ADS)

A new dating technique uses alpha-recoil tracks (ART), formed by the natural ?-decay of U, Th and their daughter products, to determine the formation age of Quaternary volcanic rocks (<10 6 a). Visualization of etched ART by scanning force microscopy (SFM) enables to access track densities beyond 10 8 cm-2 and thus extend the new ART-dating technique to an age range >10 6 a. In order to simulate natural radiation damage, samples of phlogopite, originating from Quaternary and Tertiary volcanic rocks of the Eifel (Germany) and Kerguelen Islands (Indian Ocean) were irradiated with U, Ni (11.4 MeV/u), Xe, Cr, Ne (1.4 MeV/u) and Bi (200 keV) ions. After irradiation and etching with HF at various etching times, phlogopite surfaces were visualized by SFM. Hexagonal etch pits are typical of U, Xe and Cr ion tracks, but the etch pits of Ni, Ne and Bi ion tracks are triangular. Surfaces irradiated with U, Xe, Cr and Ni ions do not show any significant difference between etch pit density and irradiation fluence, whereas the Ne-irradiated surface show ˜14 times less etch pit density. The etching rate vH (parallel to cleavage) depends on the chemical composition of the phlogopite. The etching rate vT' (along the track) increases with energy loss.

Lang, M.; Glasmacher, U. A.; Moine, B.; Müller, C.; Neumann, R.; Wagner, G. A.

2002-05-01

301

Genetics Home Reference: Fragile XE syndrome  

MedlinePLUS

... condition may be more common than reported. What genes are related to fragile XE syndrome? Fragile XE syndrome is caused by mutations in the AFF2 gene. This gene provides instructions for making a protein ...

302

Irradiation-induced Ag-colloid formation in ion-exchanged soda-lime glass  

NASA Astrophysics Data System (ADS)

Ion-exchanged glass samples were obtained by immersing soda-lime slides in molten salt baths of molar concentration in the range 1-20% AgNO 3 in NaNO 3, at temperatures varying from 320 to 350°C, and processing times of the order of a few minutes. Irradiations of exchanged samples were subsequently performed by using H +m, He +, N + ions at different energies in order to obtain comparable projected ranges. The fluence was varied between 5 × 10 15 and 2 × 10 17 ions/cm 2. Most of the samples were treated at current densities lower than 2 ?A/cm 2, in order to avoid heating effects. Some samples were irradiated with 4 keV electrons, corresponding to a range of 250 nm. The formation of nanoclusters of radii in the range 1-10 nm has been observed after irradiation, depending on the treatment conditions. The precipitation process is governed by the electronic energy deposition of incident particles. The most desirable results are obtained for helium implants. The process was characterized by the use of Secondary Ion Mass Spectrometry (SIMS) and nuclear techniques (Rutherford Backscattering (RBS), Nuclear Reactions (NRA)), in order to determine concentration-depth profiles and by optical absorption and Transmission Electron Microscopy (TEM) measurements for the silver nanoclusters detection and size evaluation.

Caccavale, F.; De Marchi, G.; Gonella, F.; Mazzoldi, P.; Meneghini, C.; Quaranta, A.; Arnold, G. W.; Battaglin, G.; Mattei, G.

1995-03-01

303

Defect accumulation in ThO2 irradiated with swift heavy ions  

NASA Astrophysics Data System (ADS)

Polycrystalline ThO2 was irradiated with 2.2 GeV Au ions and characterized by synchrotron X-ray diffraction, X-ray absorption spectroscopy, and Raman spectroscopy. The diffraction measurements indicated an increase in the unit cell parameter and the accumulation of heterogeneous microstrain with increasing ion fluence, both of which are consistent with a single-impact model of damage accumulation. An analytical fit of the data to a single-impact model yielded a saturation unit cell expansion of 0.049 ± 0.002% and a saturation strain of 10.4 ± 0.2%. Cross-section data determined from the model values yielded effective ion track diameters of 1.9 ± 0.2 nm and 3.2 ± 0.3 nm for the two modifications, respectively, indicating that the tracks consist of a core region in which swelling and strain have occurred and a defect-rich halo in which microstrain is present but the initial unit cell parameter has not changed significantly. The spectroscopic analysis revealed the presence of significant local structural distortion in the irradiated material, but no evidence of systematic modification to the electronic state or chemical environment of the cations. This indicates that swift heavy ion irradiation of ThO2 primarily produces simple point defects or defect agglomerates.

Tracy, Cameron L.; McLain Pray, J.; Lang, Maik; Popov, Dmitry; Park, Changyong; Trautmann, Christina; Ewing, Rodney C.

2014-05-01

304

Damage-depth profiling of an ion-irradiated polymer by monoenergetic positron beams  

SciTech Connect

Poly(aryl-ether-ether ketone) (PEEK) films irradiated with 1-MeV and 2-MeV O{sup +} ions were exposed to positron beams to measure the positron annihilation Doppler broadening as a function of the positron energy. The annihilation lines recorded at relatively low positron energies were found to become broader with increasing irradiation dose, suggesting that positronium (Ps) formation is inhibited in the damaged regions. The positron data were compared with the results of dynamic hardness and electron-spin-resonance measurements. The slow-positron Doppler broadening technique is found to be a useful means for damage-depth profiling of Ps-forming polymers.

Kobayashi, Y.; Kojima, I. [National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305 (Japan)] [National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305 (Japan); Hishita, S. [National Institute for Research in Inorganic Materials, Tsukuba, Ibaraki 305 (Japan)] [National Institute for Research in Inorganic Materials, Tsukuba, Ibaraki 305 (Japan); Suzuki, T. [National Laboratory for High Energy Physics (KEK), Tsukuba, Ibaraki 305 (Japan)] [National Laboratory for High Energy Physics (KEK), Tsukuba, Ibaraki 305 (Japan); Asari, E.; Kitajima, M. [National Research Institute for Metals, Tsukuba, Ibaraki 305 (Japan)] [National Research Institute for Metals, Tsukuba, Ibaraki 305 (Japan)

1995-07-01

305

The effects of high-energy uranium ion irradiation on Au/n-GaN Schottky diodes  

NASA Astrophysics Data System (ADS)

The I-V and C-V characteristics of Au/n-GaN Schottky diodes irradiated with 290-MeV 238U32+ ions are presented. The U ions can penetrate the n-type GaN epi-layer with a thickness about 3 ?m grown on the c-plane of a sapphire substrate using the MOCVD technique, leaving a purely electronic energy deposition. The Au/n-GaN Schottky diodes were irradiated to successively increasing fluences from 1 × 109 to 5 × 1011 ions cm-2. The measured I-V curves show that the height of the Schottky barrier decreases after irradiation and that the Schottky barrier almost disappears when the ion fluence reaches 5 × 1010 ions cm-2. Meanwhile, the irradiation increases the series resistance. The C-V curves show that the capacitance drops sharply when the ion fluence reaches 5 × 1010 ions cm-2. The dielectric constant also decreases following the irradiation. The changes of the electrical properties are ascribed to the neutralization of the donor-like surface state and the acceptor-like surface state due to the migration of Au atoms at the interface of Au/n-GaN under energetic U ions irradiations.

Gou, J.; Zhang, C. H.; Zhang, L. Q.; Song, Y.; Wang, L. X.; Li, J. J.; Meng, Y. C.; Li, H. X.; Yang, Y. T.; Lu, Z. W.

2014-11-01

306

Laser-plasma debris from a rotating cryogenic-solid-Xe target  

SciTech Connect

We investigate the characteristics of laser plasma debris that is responsible for damaging optics. The debris is composed of fast ions, neutral particles, and fragments, and originates from a solid Xe target on a rotating drum that we developed as an extreme ultraviolet (EUV) source. The ice fragments appear to be a problem most notably with solid Xe targets; however, we find that the damage induced by Xe ice fragments can be avoided by simply reducing the laser pulse energy. We find the number of fast neutral particles to be an order of magnitude less than the number of ions, and we clarify that the plasma debris is primarily composed of fast ions. In addition, we find that the number of fast ions having a few dozen keV of energy decreases when using the rotating target compared with the rest target. We attribute this to a gas curtain effect from the Xe gas localized at the rotating target surface. We estimate the sputtering rate of the Mo/Si mirror, which is caused primarily by the fast ions, to be 104 nm/1x10{sup 6} shots at 190 mm from the source plasma and at an 11.25 deg. angle from the incident laser beam. Up to the 1x10{sup 6} shots exposure, remarkable degradation of the mirror reflectivity is not observed though the sputtering damages the mirror. Mitigation of the ions by using gas and/or magnetic fields will further improve the mirror lifetime. By comparing with a liquid jet Xe target, we conclude that the sputtering rate per conversion efficiency when using the solid Xe targets on the rotating drum is the same as that when using the liquid Xe targets. The high conversion efficiency of 0.9% in the rotating drum solid Xe target makes this technique useful for developing laser plasma EUV sources.

Amano, Sho; Inaoka, Yutaka; Hiraishi, Hiroki; Miyamoto, Shuji; Mochizuki, Takayasu [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Ako-gun, Hyogo 678-1205 (Japan)

2010-02-15

307

Virus inactivation studies using ion beams, electron and gamma irradiation  

NASA Astrophysics Data System (ADS)

Known methods of virus inactivation are based on the chemical action of some substances such as acetylethylenimine, betapropiolactone, glycidalaldehyde, formaldehyde, etc. In such a process, the viral suspension should be kept at room or higher temperatures for 24-48 h. Under these conditions, physical and chemical agents act to degrade the virus antigenic proteins. On the contrary with ionizing radiations at low temperatures, the treatment does not cause such degradation allowing the study of different viral functions. In this work, particle (?, d and ß) and ? irradiations were used for partial and total inactivation of Foot and Mouth Disease Virus (FMDV), Rauscher Leukemia Virus (RLV) and Herpes Simplex Virus (HSV). Obtention of the D37 dose from survival curves and the application of the target theory, permitted the determination of molecular weight of the nucleic acid genomes, EBR values and useful information for vaccine preparation. For RLV virus, a two target model of the RNA genome was deduced in accordance with biological information while from data from the literature and our own work on the structure of the scrapie prion, considering the molecular weight obtained by application of the theory, a new model for prion replication is presented, based on a trimer molecule.

Smolko, Eduardo E.; Lombardo, Jorge H.

2005-07-01

308

Radiation hardness of graphene and MoS2 field effect devices against swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

We have investigated the deterioration of field effect transistors based on two-dimensional materials due to irradiation with swift heavy ions. Devices were prepared with exfoliated single layers of MoS2 and graphene, respectively. They were characterized before and after irradiation with 1.14 GeV U28+ ions using three different fluences. By electrical characterization, atomic force microscopy, and Raman spectroscopy, we show that the irradiation leads to significant changes of structural and electrical properties. At the highest fluence of 4 × 1011 ions/cm2, the MoS2 transistor is destroyed, while the graphene based device remains operational, albeit with an inferior performance.

Ochedowski, O.; Marinov, K.; Wilbs, G.; Keller, G.; Scheuschner, N.; Severin, D.; Bender, M.; Maultzsch, J.; Tegude, F. J.; Schleberger, M.

2013-06-01

309

Heavy-Ion Irradiation of Thulium(III) Oxide Targets Prepared by Polymer-Assisted Deposition  

SciTech Connect

Thulium(III) oxide (Tm{sub 2}O{sub 3}) targets prepared by the polymer-assisted deposition (PAD) method were irradiated by heavy-ion beams to test the method's feasibility for nuclear science applications. Targets were prepared on silicon nitride backings (thickness of 1000 nm, 344 {micro}g/cm{sup 2}) and were irradiated with an {sup 40}Ar beam at laboratory frame energy of {approx}210 MeV (50 particle nA). The root mean squared (RMS) roughness prior to irradiation is 1.1 nm for a {approx}250 nm ({approx}220 {micro}g/cm{sup 2}) Tm{sub 2}O{sub 3} target, and an RMS roughness of 2.0 nm after irradiation was measured by atomic force microscopy (AFM). Scanning electron microscopy of the irradiated target reveals no significant differences in surface homogeneity when compared to imaging prior to irradiation. Target flaking was not observed from monitoring Rutherford scattered particles as a function of time.

Garcia, Mitch A.; Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, Tashi; Ashby, Paul D.; Gates, Jacklyn M.; Stavsetra, Liv; Gregorich, Kenneth E.; Nitsche, Heino

2008-09-15

310

Effects of ion bombardment on a two-dimensional target: Atomistic simulations of graphene irradiation  

NASA Astrophysics Data System (ADS)

Using atomistic computer simulations based on analytical potential and density-functional theory models, we study effects of ion irradiation on graphene. We identify the types and concentrations of defects which appear in graphene under impacts of various ions with energies ranging from tens of electron volts to mega-electron volts. For two-dimensional targets, defects beyond single and double vacancies are formed via in-plane recoils. We demonstrate that the conventional approach based on binary-collision approximation and stochastic algorithms developed for bulk solids cannot be applied to graphene and other low-dimensional systems. Finally, taking into account the gas-holding capacity of graphene, we suggest the use of graphene as the ultimate membrane for ion-beam analysis of gases and other volatile systems which cannot be put in the high vacuum required for the operation of ion beams.

Lehtinen, O.; Kotakoski, J.; Krasheninnikov, A. V.; Tolvanen, A.; Nordlund, K.; Keinonen, J.

2010-04-01

311

Radical Formation and Chemical Track Structure in Ion-Beam Irradiated DNA  

NASA Astrophysics Data System (ADS)

Ion-beam irradiation of hydrated DNA at 77 K results in formation of at least three base radicals and a variety of radicals on the sugar phosphate backbone that can be observed using Electron Spin Resonance (ESR) spectroscopy. From dose-response curves for these radicals, we have formulated a radiation-chemical model of the track structure for ion-beam irradiated DNA. The model for chemical behavior posits that the base radicals trapped at 77 K are formed almost entirely in the track penumbra. The lower yields observed in ion-beam irradiated samples results from the fact that only a portion of the energy deposited by the ion beam ends up in this ?-like region. The remainder of the energy is deposited in the core in which the proximity of ion-radical formation results in the fast recombination of oppositely charged radicals, so few survive in the core at 77 K. However, a second group of radicals, neutral sugar radicals, are not as susceptible to recombination as are ion radicals, and can survive after formation in the core; these are presumed to form predominantly in the core. They include the sugar radicals, C1'?C3'?C5'?, formed from oxidative processes, and C3'?dephos and phosphorous radicals which are formed after immediate strand breaks. The later species are thought to result from reductive cleavage by low energy electrons (LEE.) The high energy density in the core results in excited state processes that produce additional sugar radicals. The spatial characteristics of the radicals, deduced from PELDOR experiments, indicates that multiply damaged cluster sites (MDS) are formed in the core; these would be biologically significant, if formed in cells.

Becker, David; Adhikary, Amitava; Khanduri, Deepti; Sevilla, Michael D.

2009-12-01

312

Effects of ion beam irradiation on adventitious shoot regeneration from in vitro leaf explants of Saintpaulia ionahta  

NASA Astrophysics Data System (ADS)

The effects of 960 MeV carbon ion beam and 8 MeV X-ray irradiation on adventitious shoots from in vitro leaf explants of two different Saintpaulia ionahta (Mauve and Indikon) cultivars were studied with regard to tissue increase, shoots differentiation and morphology changes in the shoots. The experimental results showed that the survival fraction of shoot formation for the Mauve and Indikon irradiated with the carbon ion beam at 20 Gy were 0.715 and 0.600, respectively, while those for both the cultivars exposed to the X-ray irradiation at the same dose were 1.000. Relative biological effectiveness (RBE) of Mauve with respect to X-ray was about two. Secondly, the percentage of regenerating explants with malformed shoots in all Mauve regenerating explants irradiated with carbon ion beam at 20 Gy accounted for 49.6%, while that irradiated with the same dose of X-ray irradiation was only 4.7%; as for Saintpaulia ionahta Indikon irradiated with 20 Gy carbon ion beam, the percentage was 43.3%, which was higher than that of X-ray irradiation. Last, many chlorophyll deficient and other varieties of mutants were obtained in this study. Based on the results above, it can be concluded that the effect of mutation induction by carbon ion beam irradiation on the leaf explants of Saintpaulia ionahta is better than that by X-ray irradiation; and the optimal mutagenic dose varies from 20 Gy to 25 Gy for carbon ion beam irradiation.

Zhou, L. B.; Li, W. J.; Ma, S.; Dong, X. C.; Yu, L. X.; Li, Q.; Zhou, G. M.; Gao, Q. X.

2006-03-01

313

Amorphization of zirconolite: alpha-decay event damage versus krypton ion irradiation  

NASA Astrophysics Data System (ADS)

Natural zirconolite (CaZrTi 2O 7) can receive ?-decay event doses of > 10 26 alpha-decay events/m 3 (~2 dpa), and can thus become amorphous (metamict) due to the radioactive decay of 238U, 235U and 232Th and their daughter products which occur as substitutional impurities (the zirconolite contains approximately 20 wt% ThO 2 and is 550 million years old). In this study, the zirconolite sample was recrystallized by thermal annealing at 1130°C for 8 hours in air. Amorphization was induced with 1.5 MeV Kr + ions using the HVEM-Tandem Facility at Argonne National Laboratory. The Kr dose rate used during the irradiation was 3.4 × 10 11 ions/cm 2s. which is a damage rate 2 × 10 12 times higher than that which has occurred in the natural sample due to decay of the actinides. In-situ transmission electron microscopy was completed during the ion irradiation. The recrystallized zirconolite also formed isolated thorianite (ThO 2) crystals, 25-100 nm in size, in the matrix of the polycrystalline zirconolite. After a Kr + dose of 4 × 10 14 ions/cm 2 (= 0.3 dpa). the zirconolite grains were reamorphized: however, the thorianite grains remained crystalline even after a Kr + dose of 6 × 10 14 ions/cm 2.

Ewing, R. C.; Wang, L. M.

1992-03-01

314

Effect of low energy ion irradiation on CdTe crystals: Luminescence enhancement  

SciTech Connect

In this work we show that low energy ion sputtering is a very efficient technique as a cleaning process for CdTe substrates. We demonstrate, by using several techniques like grazing-angle x-ray diffraction, cathodoluminescence, microluminescence, and micro-Raman spectroscopy that the luminescent properties of CdTe substrates can be very much increased when CdTe surfaces are irradiated with low energy Argon ions. We postulate that this enhancement is mainly due to the removal of surface damage induced by the cutting and polishing processes. The formation of a low density of nonluminescent aggregates after the sputtering process has also been observed.

Olvera, J.; Plaza, J. L.; Dios, S. de; Dieguez, E. [Departamento de Fisica de Materiales, Laboratorio de Crecimiento de Cristales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Martinez, O.; Avella, M. [Departamento Fisica Materia Condensada, GdS-Optronlab Group, Universidad de Valladolid, Edificio I-D, Paseo de Belen 1, 47011 Valladolid (Spain)

2010-12-15

315

Stress-induced patterns in ion-irradiated Silicon: a model based on anisotropic plastic flow  

E-print Network

We present a model for the effect of stress on thin amorphous films that develop atop ion-irradiated silicon, based on the mechanism of ion-induced anisotropic plastic flow. Using only parameters directly measured or known to high accuracy, the model exhibits remarkably good agreement with the wavelengths of experimentally-observed patterns, and agrees qualitatively with limited data on ripple propagation speed. The predictions of the model are discussed in the context of other mechanisms recently theorized to explain the wavelengths, including extensive comparison with an alternate model of stress.

Scott A. Norris

2012-07-24

316

Free ion yield observed in liquid isooctane irradiated by gamma rays. Comparison with the Onsager theory  

E-print Network

We have analyzed data on the free ion yield observed in liquid isooctane irradiated by Co60 gamma rays within the framework of the Onsager theory about initial recombination. Several distribution functions describing the electron thermalization distance have been used and compared with the experimental results: a delta function, a Gaussian type function and an exponential function. A linear dependence between free ion yield and external electric field has been found at low electric field values (E<1.2 MV/m) in excellent agreement with the Onsager theory. At higher electric field values we obtain a solution in power series of the external field using the Onsager theory.

Pardo, J; Iglesias, A; Lobato, R; Mosquera, J; Pazos, A; Peña, J; Pombar, M; Rodríguez, A; Sendon, J

2003-01-01

317

Irradiation effect of carbon negative-ion implantation on polytetrafluoroethylene for controlling cell-adhesion property  

NASA Astrophysics Data System (ADS)

We have investigated the irradiation effect of negative-ion implantation on the changes of physical surface property of polytetrafluoroethylene (PTFE) for controlling the adhesion property of stem cells. Carbon negative ions were implanted into PTFE sheets at fluences of 1 × 10 14-1 × 10 16 ions/cm 2 and energies of 5-20 keV. Wettability and atomic bonding state including the ion-induced functional groups on the modified surfaces were investigated by water contact angle measurement and XPS analysis, respectively. An initial value of water contact angles on PTFE decreased from 104° to 88° with an increase in ion influence to 1 × 10 16 ions/cm 2, corresponding to the peak shifting of XPS C1s spectra from 292.5 eV to 285 eV with long tail on the left peak-side. The change of peak position was due to decrease of C-F 2 bonds and increase of C-C bonds with the formation of hydrophilic oxygen functional groups of OH and C dbnd O bonds after the ion implantation. After culturing rat mesenchymal stem cells (MSC) for 4 days, the cell-adhesion properties on the C --patterned PTFE were observed by fluorescent microscopy with staining the cell nuclei and their actin filament (F-actin). The clear adhesion patterning of MSCs on the PTFE was obtained at energies of 5-10 keV and a fluence of 1 × 10 15 ions/cm 2. While the sparse patterns and the uncontrollable patterns were found at a low fluence of 3 × 10 14 ions/cm 2 and a high fluence of 3 × 10 15 ions/cm 2, respectively. As a result, we could improve the surface wettability of PTFE to control the cell-adhesion property by carbon negative-ion implantation.

Sommani, Piyanuch; Tsuji, Hiroshi; Kojima, Hiroyuki; Sato, Hiroko; Gotoh, Yasuhito; Ishikawa, Junzo; Takaoka, Gikan H.

2010-10-01

318

Outgassing and degradation of polyimide induced by swift heavy ion irradiation at cryogenic temperature  

SciTech Connect

Polyimide foils were irradiated with energetic Kr (740 MeV) and Pb (890 MeV) ions at cryogenic temperature (12 K). Beam-induced degradation processes were monitored by residual gas analysis and online infrared spectroscopy. The outgassing components observed at low irradiation temperatures differ in quantity but are similar in mass distribution to those identified at room temperature exposure. Besides CO as major volatile fragment, a significant contribution of short hydrocarbons like C{sub 2}H{sub x} is released. In situ infrared spectroscopy indicates accumulation of CO and CO{sub 2} molecules at 12 K in the foils. During heat-up cycles, most of these frozen gases become mobile and outgas at a temperature between 35 and 55 K. The study is motivated by the application of polyimide foils as insulating material in high radiation environment of the future accelerator facility for antiproton and ion research (FAIR).

Severin, D. [Department of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); GSI-Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt (Germany); Balanzat, E. [CIMAP-CIRIL, CEA-CNRS-ENSICAEN, 14050 Caen cedex 4 (France); Ensinger, W. [Department of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Trautmann, C. [GSI-Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt (Germany)

2010-07-15

319

Optical waveguides in LiTaO3 crystals fabricated by swift C5+ ion irradiation  

NASA Astrophysics Data System (ADS)

We report on the optical waveguides, in both planar and ridge configurations, fabricated in LiTaO3 crystal by using carbon (C5+) ions irradiation at energy of 15 MeV. The planar waveguide was produced by direct irradiation of swift C5+ ions, whilst the ridge waveguides were manufactured by using femtosecond laser ablation of the planar layer. The reconstructed refractive index profile of the planar waveguide has showed a barrier-shaped distribution, and the near-field waveguide mode intensity distribution was in good agreement with the calculated modal profile. After thermal annealing at 260 °C in air, the propagation losses of both the planar and ridge waveguides were reduced to 10 dB/cm.

Liu, Guiyuan; He, Ruiyun; Akhmadaliev, Shavkat; Vázquez de Aldana, Javier R.; Zhou, Shengqiang; Chen, Feng

2014-04-01

320

Structural peculiarities of 4H-SiC irradiated by Bi ions  

SciTech Connect

X-ray diffraction, photoluminescence, micro-cathodoluminescence, and scanning and transmission electron spectroscopy were used to study the 710 MeV Bi ion irradiation effect in the fluence range of 1.4 x 10{sup 9}-5 x 10{sup 10} cm{sup -2} on the structural and optical characteristics of pure high-resistivity n-type 4H-SiC epitaxial layers grown by chemical vapor deposition. It was established that the distribution of structural damage along the ion trajectory follows the computed profile of radiation defects formed in elastic collisions. The high-density ionization effect on the material characteristics has not been found under the irradiation conditions used. Optical methods revealed a wide spectrum of radiation-induced defects, with some of them contributing to the recombination process. The damaged 4H-SiC crystal lattice party recovers after annealing at 500 deg. C.

Kalinina, E. V. [Russian Academy of Sciences, loffe Physicotechnical Institute (Russian Federation)], E-mail: evk@pop.ioffe.rssi.ru; Skuratov, V. A. [Joint Institute for Nuclear Research (Russian Federation); Sitnikova, A. A.; Kolesnikova, E. V.; Tregubova, A. S.; Shcheglov, M. P. [Russian Academy of Sciences, loffe Physicotechnical Institute (Russian Federation)

2007-04-15

321

Direct observations of the primary state of radiation damage of ion-irradiated tungsten and platinum  

SciTech Connect

A brief summary was presented of all the Cornell work on the primary state of radiation damage in ion-irradiated tungsten and platinum. The primary research tool for all this research was the field-ion microscope (FIM); the FIM was ideally suited for this research because of its excellent atomic resolution and the ability to examine the interior of the specimens, as a result of the field-evaporation effect. This paper summarized, in outline form, the following items: (1) the principal experimental quantities determined from the analyses performed on all the individual depleted zones (DZs) observed; (2) the main experimental programs; (3) a number of the more important results and conclusions concerning the vacancy structure of DZs; and (4) the three-dimensional spatial distribution of self-interstitial atoms around DZs in tungsten which had been irradiated and examined in situ at 10/sup 0/K.

Seidman, D. N.; Current, M. I.; Pramanik, D.; Wei, C. Y.

1980-07-01

322

Evolution of nanoripples on silicon by gas cluster-ion irradiation  

SciTech Connect

Si wafers of (100), (110) and (111) orientations were bombarded by gas cluster ion beam (GCIB) of 3000 Ar-atoms/cluster on average at a series of angles. Similar surface morphology ripples developed in different nanoscales. A simple scaling functional satisfactorily describe the roughness and wavelength of the ripple patterns as a function of dosage and angle of incidence. The ripples are formed orthogonal to the incident cluster-ions at large off-normal angles. An ellipsoidal pattern was created by two consecutive irradiations incident in mutually orthogonal directions with unequal exposure times between each irradiation, from 7:1 to 10:1, beyond which the original ripple imprints would be over-written. This work was inspired by use of the ripples to seed growth of controlled nanostructures without patterning by lithography or predeposition of catalysts.

Lozano, Omar; Chen, Q. Y.; Wadekar, P. V.; Chinta, P. V. [Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 88204 (United States); Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Tilakaratne, B. P.; Wang, X. M.; Wijesundera, D.; Chu, W. K. [Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 88204 (United States); Seo, H. W. [Department of Physics and Astronomy, University of Arkansas, Little Rock, AR 72204 (United States); Tu, L. W. [Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Ho, N. J. [Department of Materials and Optoelectronic Sciences and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan (China)

2013-06-15

323

Ion irradiation of Allende meteorite probed by visible, IR, and Raman spectroscopies  

NASA Astrophysics Data System (ADS)

Little is known about carbonaceous asteroids weathering in space as previous studies have struggled to define a general spectral trend among dark surfaces. Here we present experiments on ion irradiation of the Allende meteorite, performed using 40 keV He+ and Ar+ ions, as a simulation of solar wind irradiation of primitive bodies surfaces. We used different fluences up to 3 × 1016 ions/cm2, corresponding to short timescales of ?103-104 yrs in the main asteroid belt. Samples were analyzed before and after irradiation using visible to far-IR (0.4-50 ?m) reflectance spectroscopy, and Raman micro-spectroscopy. Similarly to what observed in previous experiments, results show a reddening and darkening of VIS-NIR reflectance spectra. These spectral variations are however comparable to other spectral variations due to viewing geometry, grain size, and sample preparation, suggesting an explanation for the contradictory space weathering studies of dark asteroids. After irradiation, the infrared bands of the matrix olivine silicates change profile and shift to longer wavelength, possibly as a consequence of a more efficient sputtering effect on Mg than Fe (lighter and more volatile species are preferentially sputtered backwards) and/or preferential amorphization of Mg-rich olivine. Spectral variations are compatible with the Hapke weathering model. Raman spectroscopy shows that the carbonaceous component is substantially affected by irradiation: different degrees of de-ordering are produced as a function of dose, to finally end with a highly disordered carbon. All observed modifications seem to scale with the nuclear elastic dose.

Brunetto, R.; Lantz, C.; Ledu, D.; Baklouti, D.; Barucci, M. A.; Beck, P.; Delauche, L.; Dionnet, Z.; Dumas, P.; Duprat, J.; Engrand, C.; Jamme, F.; Oudayer, P.; Quirico, E.; Sandt, C.; Dartois, E.

2014-07-01

324

Postmortem examination of 22 pancreatic carcinoma patients treated with helium ion irradiation  

SciTech Connect

Postmortem findings are available in this report in 22 patients with pancreatic carcinoma treated with helium ions at Lawrence Berkeley Laboratory; California. This represents the largest group evaluated histologically in the literature and is the first report evaluating effects of particle radiation in pancreatic tissue. Patient survival after therapy averaged 9 months. Most died of infection and/or pulmonary emboli. Local control was achieved in 27%. The pancreatic tumors had histologically more severe radiation changes than nontumor bearing pancreas. Irradiated bone marrow was severely hypocellular, and irradiated skin was atrophic. Five patients had radiation injury in the gastrointestinal tract. The spinal cord, liver, and kidneys showed no damage. This study demonstrates the safety of helium particle irradiation with present therapeutic planning. Injury to tumor was seen without excessive damage to adjacent tissues.

Woodruff, K.H.; Castro, J.R.; Quivey, J.M.; Saunders, W.M.; Chen, G.T.; Lyman, J.T.; Pitluck, S.; Tobias, C.A.; Walton, R.E.; Peters, T.C.

1984-02-01

325

Wide variety of flower-color and -shape mutants regenerated from leaf cultures irradiated with ion beams  

NASA Astrophysics Data System (ADS)

The efficiency of ion-beam irradiation combined with tissue culture in obtaining floral mutants was investigated and compared with those of gamma rays and X-rays in carnation. Leaf segments of carnation plants in vitro were irradiated with the 220 MeV carbon ions, and cultured till the shoot regenerated. The carbon ion had the highest effect in reducing the regeneration frequency, and the RBE value with respect to gamma-rays was four. The higher mutation frequency and the wider mutation spectrum were obtained in plants irradiated with the carbon ions than low LET radiations. Three new carnation varieties developed by ion-beam irradiation were applied for the registration of the Japanese Ministry of Agriculture, Forestry and Fisheries. The results indicate that ion beam irradiation could induce wide variety of flower-color and -shape mutants, and that the combined method of ion-beam irradiation with tissue culture is useful to obtain the commercial varieties in a short time.

Okamura, M.; Yasuno, N.; Ohtsuka, M.; Tanaka, A.; Shikazono, N.; Hase, Y.

2003-05-01

326

Fast-Ion Production from Short-Pulse Irradiation of Ethanol Microdroplets  

Microsoft Academic Search

We report on the first detailed measurements of ion energy distributions from microdroplet targets under ultrashort (100fs), intense (1016 Wcm-2) laser irradiation. Protons with kinetic energies of up to 20keV are produced in a strongly anisotropic microexplosion. Modeling of the incident electromagnetic field indicates strong spatial variations over the surface of the microdroplet. Detailed numerical modeling shows that nonuniform heating

D. R. Symes; A. J. Comley; R. A. Smith

2004-01-01

327

Nanoscale smoothing of plasmonic films and structures using gas cluster ion beam irradiation  

NASA Astrophysics Data System (ADS)

We present a novel method of using gas cluster ion beam irradiation (GCIB) to flatten and widen grains in silver films and structures, while simultaneously, reducing the film thickness with nanometer precision. Ultrathin Ag films produced by GCIB have lower absorbance and better adhesion compared to as-deposited films. By applying the technique post-fabrication to plasmonic color filters, waveguides and disks, we show that an enhanced surface plasmon resonance and propagation length can be achieved.

Teo, Ee Jin; Toyoda, Noriaki; Yang, Chengyuan; Bettiol, Andrew A.; Teng, Jing Hua

2014-08-01

328

Anisotropic evolution of Frank loops in ion-irradiated silicon carbide  

Microsoft Academic Search

Frank loop evolution in highly damaged polycrystalline cubic silicon carbide irradiated with 5.1MeV Si2+ ions at 1673K was studied by transmission electron microscopy (TEM). Individual TEM images of Frank loops formed on each {111} plane revealed that their population strongly depended upon their orientation with respect to the incident beam direction. However, no significant difference in loop growth rates was

S. Kondo; A. Kohyama; T. Hinoki

2007-01-01

329

Effect of intense pulsed ion beams irradiation on the oxidation behavior of ? ?-based superalloy  

Microsoft Academic Search

Intense pulsed ion beams (IPIB) with three different power densities (25, 37.5 and 50 MW\\/cm2) are employed for the surface treatment of ??-based superalloy IC6. The influence of IPIB irradiation on the oxidation behavior of IC6 at 1100 °C for up to 100 h is investigated. It is found that the phase states of IC6 are dramatically changed after IPIB

Hongtao Zhang; Tianmin Wang; Cong Wang; Baoxi Han; Sha Yan; Weijiang Zhao; Yafang Han

2002-01-01

330

Deuterium trapping at defects created with neutron and ion irradiations in tungsten  

NASA Astrophysics Data System (ADS)

The effects of neutron and ion irradiations on deuterium (D) retention in tungsten (W) were investigated. Specimens of pure W were irradiated with neutrons to 0.3 dpa at around 323 K and then exposed to high-flux D plasma at 473 and 773 K. The concentration of D significantly increased by neutron irradiation and reached 0.8 at% at 473 K and 0.4 at% at 773 K. Annealing tests for the specimens irradiated with 20 MeV W ions showed that the defects which play a dominant role in the trapping at high temperature were stable at least up to 973 K, while the density decreased at temperatures equal to or above 1123 K. These observations of the thermal stability of traps and the activation energy for D detrapping examined in a previous study (?1.8 eV) indicated that the defects which contribute predominantly to trapping at 773 K were small voids. The higher concentration of trapped D at 473 K was explained by additional contributions of weaker traps. The release of trapped D was clearly enhanced by the exposure to atomic hydrogen at 473 K, though higher temperatures are more effective for using this effect for tritium removal in fusion reactors.

Hatano, Y.; Shimada, M.; Otsuka, T.; Oya, Y.; Alimov, V. Kh.; Hara, M.; Shi, J.; Kobayashi, M.; Oda, T.; Cao, G.; Okuno, K.; Tanaka, T.; Sugiyama, K.; Roth, J.; Tyburska-Püschel, B.; Dorner, J.; Yoshida, N.; Futagami, N.; Watanabe, H.; Hatakeyama, M.; Kurishita, H.; Sokolov, M.; Katoh, Y.

2013-07-01

331

Influence of light ion irradiation on fatigue crack propagation in austenitic stainless steel  

NASA Astrophysics Data System (ADS)

Fatigue crack growth is considered to be a limiting factor for the life time of the first wall of a Tokamak type controlled thermonuclear reactor. As a result of the high energy neutron spectrum in the D-T fusion reaction not only defects but also large quantities of helium due to nuclear transmutation are produced in the structural materials. One way of simulating the damage of high energy neutrons is to use light ions by means of a charged particle accelerator. In the present work Type 316 stainless steel specimens were irradiated in a suitable irradiation chamber using a variable energy cyclotron. Fatigue crack growth under cyclic tensile stress was measured under simultaneous 18 MeV proton irradiation producing a displacement damage rate of the order of 10 -7dpa s -1. The same type of specimens were implanted with 38 MeV ?-particles and tested after bombardement. It was found that light ions irradiation has only a slight influence on fatigue crack growth at 500°C in type 316 stainless steel.

Fenici, P.

1988-07-01

332

Deuterium trapping at defects created with neutron and ion irradiations in tungsten  

SciTech Connect

The effects of neutron and ion irradiations on deuterium (D) retention in tungsten (W) were investigated. Specimens of pure W were irradiated with neutrons to 0.3 dpa at around 323 K and then exposed to high-flux D plasma at 473 and 773 K. The concentration of D significantly increased by neutron irradiation and reached 0.8 at% at 473 K and 0.4 at% at 773 K. Annealing tests for the specimens irradiated with 20 MeV W ions showed that the defects which play a dominant role in the trapping at high temperature were stable at least up to 973 K, while the density decreased at temperatures equal to or above 1123 K. These observations of the thermal stability of traps and the activation energy for D detrapping examined in a previous study (˜1.8 eV) indicated that the defects which contribute predominantly to trapping at 773 K were small voids. The higher concentration of trapped D at 473 K was explained by additional contributions of weaker traps. The release of trapped D was clearly enhanced by the exposure to atomic hydrogen at 473 K, though higher temperatures are more effective for using this effect for tritium removal in fusion reactors.

Y. Hatano; M. Shimada; T. Otsuka; Y. Oya; V.Kh. Alimov; M. Hara; J. Shi; M. Kobayashi; T. Oda; G. Cao; K. Okuno; T. Tanaka; K. Sugiyama; J. Roth; B. Tyburska-Püschel; J. Dorner; N. Yoshida; N. Futagami; H. Watanabe; M. Hatakeyama; H. Kurishita; M. Sokolov; Y. Katoh

2013-07-01

333

Evolution of microstructure and crack pattern in NiO thin films under 200 MeV Au ion irradiation  

NASA Astrophysics Data System (ADS)

NiO thin films grown on Si (100) substrate by electron beam evaporation method and sintered at 700 °C were irradiated with 200 MeV Au15+ ions. The fcc structure of the sintered films was retained up to the highest fluence (1×1013 ions cm-2) of irradiation. However the microstructure of the pristine film underwent a considerable modification with increasing ion fluence. 200 MeV Au ion irradiation led to compressive stress generation in NiO medium. The diameter of the stressed region created by 200 MeV Au ions along the ion path was estimated from the variation of stress with ion fluence and found to be ˜11.6 nm. The film surface started cracking when irradiated at and above the fluence of 3×1012 ions cm-2. Ratio of the fractal dimension of the cracked surface obtained at 200 MeV and 120 MeV (Mallick et al., 2010a) Au ions was compared with the ratio of the radii of ion tracks calculated based on Coulomb explosion and thermal spike models. This comparison indicated applicability of thermal spike model for crack formation.

Mallick, P.; Agarwal, D. C.; Rath, Chandana; Behera, D.; Avasthi, D. K.; Kanjilal, D.; Mishra, N. C.

2012-06-01

334

Generation of silver nanoparticles with controlled size and spatial distribution by pulsed laser irradiation of silver ion-doped glass.  

PubMed

Silver ions were driven into glass by a direct current electric field-assisted ion exchange technique. The silver ion exchanged glass was then irradiated by laser pulses of 10 ns and 10 ps in length at 355 nm for comparison purposes. In both cases, laser irradiation led to the formation of a metallic-like film at the surface of the ion exchange glass. Scanning electron microscopy showed that the films consist of a very dense single layer of silver nanoparticles with similar particle sizes and separation. Irradiation with different laser parameters shows no significant difference in transmission spectra and modification width between ps- and ns-pulsed lasers. Particle sizes and separation at the surface are increasing with increasing laser power, and are larger for picosecond pulsed laser irradiation. It is also shown that the film formation is a thermal process. PMID:24663847

Wackerow, Stefan; Abdolvand, Amin

2014-03-10

335

Survey and comparison of various sample preparation techniques for the heavy ions backside irradiation of COTS VLSI  

Microsoft Academic Search

Taking into account current and future encapsulation techniques of COTS VLSI components, a survey of state-of-the-art sample preparation techniques for heavy ions backside irradiation has been performed and then evaluated on a SDRAM test vehicle.

F. Courtade; F. Bezerra; S. Duzellier

2005-01-01

336

Resistance switching properties of planner Ag\\/Li:NiO\\/Ag structures induced by swift heavy ion irradiation  

Microsoft Academic Search

We report on the resistance switching induced by swift heavy ion (SHI) irradiation in lithium doped nanostructured NiO thin films grown on MgO (100) substrates by chemical solution deposition. Hysteresis in current-voltage curves were observed for the Ag\\/Li:NiO\\/Ag planner structures irradiated with 100 MeV Ag+14 ions, whereas pristine samples showed only linear I-V characteristics. No preferential oxygen loss from the

S. J. Trivedi; K. H. Bhavsar; U. N. Trivedi; S. A. Khan; D. K. Avasthi

2009-01-01

337

High fluence irradiation effect on the ion beam graft polymerization method  

NASA Astrophysics Data System (ADS)

Radiation graft polymerization method has been applied to make many industrial product. Ion beam graft polymerization method has been developed by Betz and many researchers, and we have also developed the method with proton whose energy is below a few MeV. Using the method, the substrate, e.g. polyethylene film, is graft-polymerized and has the graft chains near the surface. To conduct the method for some times, the structure of graft chains near the surface can be formed. When we want to produce the graft chains inside of the substrate, the graft chains near the surface are unnecessary. One of our objectives is to produce a functional polymer with a structure in the film. When the sample is irradiated in sufficiently high fluence, the sample can't be graft-polymerized in the next irradiation. Comparing the density of radicals and the number of double bond with the degree of grafting, the reason why formation of a part not grafted in high fluence irradiation was discussed. Because the number of the double bond and the allyl radicals in PE are increased for high fluence irradiation, the number of the alkyl radical as a grafting point is decreased. Moreover, the alkyl radical is not produced in following irradiation since existence of double bond and peroxy radical.

Taniike, Akira; Hirooka, Yuya; Nakanishi, Noriaki; Nakamura, Raito; Furuyama, Yuichi

2014-07-01

338

I-V analysis of high-energy lithium-ion-irradiated Si and GaAs solar cells  

E-print Network

Space-grade Si and GaAs solar cells were irradiated with 15 and 40 MeV lithium ions. Dark-IV analysis (with and without illumination) reveals differences in the effects of such irradiation on the different cell types

A. Meulenberg Jr; B. Jayashree; Ramani; M. C. Radhakrishna; A. K. Saif

2007-09-07

339

Development of a facility for high-precision irradiation of cells with carbon ions  

SciTech Connect

Purpose: Compared to photons, using particle radiation in radiotherapy reduces the dose and irradiated volume of normal tissues, potentially reducing side effects. The biological effect of dose deposited by particles such as carbon ions, however, differs from that of dose deposited by photons. The inaccuracy in models to estimate the biological effects of particle radiation remains the most important source of uncertainties in particle therapy. Improving this requires high-precision studies on biological effects of particle radiation. Therefore, the authors aimed to develop a facility for reproducible and high-precision carbon-ion irradiation of cells in culture. The combined dose nonuniformity in the lateral and longitudinal direction should not exceed {+-}1.5%. Dose to the cells from particles than other carbon ions should not exceed 5%. Methods: A uniform lateral dose distribution was realized using a single scatter foil and quadrupole magnets. A modulator wheel was used to create a uniform longitudinal dose distribution. The choice of beam energy and the optimal design of these components was determined using GEANT4 and SRIM Monte Carlo simulations. Verification of the uniformity of the dose distribution was performed using a scintillating screen (lateral) and a water phantom (longitudinal). The reproducibility of dose delivery between experiments was assessed by repeated measurements of the spatial dose distribution. Moreover, the reproducibility of dose-response measurements was tested by measuring the survival of irradiated HEK293 cells in three independent experiments. Results: The relative contribution of dose from nuclear reaction fragments to the sample was found to be <5% when using 90 MeV/u carbon ions. This energy still allows accurate dosimetry conforming to the IAEA Report TRS-398, facilitating comparison to dose-effect data obtained with other radiation qualities. A 1.3 mm long spread-out Bragg peak with a diameter of 30 mm was created, allowing the irradiation of cell samples with the specified accuracy. Measurements of the transverse and longitudinal dose distribution showed that the dose variation over the sample volume was {+-}0.8% and {+-}0.7% in the lateral and longitudinal directions, respectively. The track-averaged LET of 132{+-}10 keV/{mu}m and dose-averaged LET of 189{+-}15 keV/{mu}m at the position of the sample were obtained from a GEANT4 simulation, which was validated experimentally. Three separately measured cell-survival curves yielded nearly identical results. Conclusions: With the new facility, high-precision carbon-ion irradiations of biological samples can be performed with highly reproducible results.

Goethem, Marc-Jan van; Niemantsverdriet, Maarten; Brandenburg, Sytze; Langendijk, Johannes A.; Coppes, Robert P.; Luijk, Peter van [Department of Cell Biology, Section of Radiation and Stress Cell Biology, University Medical Center Groningen, University of Groningen, A. Deusinglaan 1, 9713AV Groningen (Netherlands); Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700RB Groningen (Netherlands); Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747AA Groningen (Netherlands); Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700RB Groningen (Netherlands); Department of Cell Biology, Section of Radiation and Stress Cell Biology, University Medical Center Groningen, University of Groningen, A. Deusinglaan 1, 9713AV Groningen (Netherlands); Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700RB Groningen (Netherlands)

2011-01-15

340

Phase separation in ion-irradiated compound semiconductors: an alternate route to ordered nano-structures  

E-print Network

In recent years, observations of highly-ordered, hexagonal arrays of self-organized nanostructures on binary or impurity-laced targets under normal-incidence ion irradiation have excited interest in this phenomenon as a potential route to high-throughput, low-cost manufacture of nanoscale devices or nanostructured coatings. The currently-prominent explanation for these structures is a morphological instability driven by ion erosion discovered by Bradley and Shipman; however, recent parameter estimates via molecular dynamics simulations suggest that this erosive instability may not be active for the representative GaSb system in which hexagonal structures were first observed. Motivated by experimental and numerical evidence suggesting the possible importance of phase separation in ion-irradiated compounds, we here generalize the Bradley-Shipman theory to include the effect of ion-assisted phase separation. The resulting system admits a chemically-driven finite-wavelength instability that can explain the order of observed patterns even when the erosive Bradley-Shipman instability, and in a relevant simplifying limit, provides an intuitive instability criteria that agrees qualitatively with experimental observations on pattern wavelengths. Finally, we identify a characteristic experimental signature that distinguishes the chemical and morphological instabilities, and highlights the need for specific additional experimental data on the GaSb system.

Scott A. Norris

2012-05-30

341

Studies of the effects of ion irradiation on ferroelectric domains of triglycine sulfate single crystals on a nanometer scale  

NASA Astrophysics Data System (ADS)

The effects of low dose (10 9/cm 2) ion irradiation on the ferroelectric domains and on the ferroelectric?paraelectric phase transition of triglycine sulfate (TGS) single crystals has been studied by using variable temperature dynamic contact electrostatic force microscopy. The evolution with temperature of ferroelectric domains of virgin and ion irradiated samples was observed in situ. In general, the phase transition of ion unirradiated samples is similar to that of virgin samples, which can be well described by Landau's mean field theory. However, on ion irradiated samples, there is a strong asymmetry of spontaneous polarization P for positive and negative domains. This asymmetry is due to the defects produced by ion implantation.

Xie, Z.; Luo, E. Z.; Xu, J. B.; An, J.; Sundaravel, B.; Wilson, I. H.; Wang, Z. Y.; Chen, X. L.; Zhao, L. H.

2003-03-01

342

Temperature-dependent void formation and growth at ion-irradiated nanocrystalline CeO2-Si interfaces  

NASA Astrophysics Data System (ADS)

Ceria is a thermally stable ceramic that has numerous applications in the nuclear industry, including use in nuclear fuels and waste forms. Recently, interest has surged in nanostructured ceria due to its increased mechanical properties and electronic conductivity in comparison with bulk ceria and its ability to self-heal in response to energetic ion bombardment. Here, nanocrystalline ceria thin films grown over a silicon substrate are irradiated to fluences of up to ˜4 × 1016 ions/cm2 under different irradiation conditions: with differing ion species (Si+ and Ni+), different ion energies (1.0-1.5 MeV), and at varying temperatures (160-600 K). While the nanocrystalline ceria is found to exhibit exceptional radiation resistance under all tested conditions, severe ion irradiation-induced mixing, void formation, and void growth are observed at the ceria/silicon interface, with the degree of damage proving to be temperature dependent.

Perez-Bergquist, Alejandro G.; Zhang, Yanwen; Varga, Tamas; Moll, Sandra; Namavar, Fereydoon; Weber, William J.

2014-04-01

343

Comparison of the effects of photon versus carbon ion irradiation when combined with chemotherapy in vitro  

PubMed Central

Background Characterization of combination effects of chemotherapy drugs with carbon ions in comparison to photons in vitro. Methods The human colon adenocarcinoma cell line WiDr was tested for combinations with camptothecin, cisplatin, gemcitabine and paclitaxel. In addition three other human tumour cell lines (A549: lung, LN-229: glioblastoma, PANC-1: pancreas) were tested for the combination with camptothecin. Cells were irradiated with photon doses of 2, 4, 6 and 8 Gy or carbon ion doses of 0.5, 1, 2 and 3 Gy. Cell survival was assessed using the clonogenic growth assay. Treatment dependent changes in cell cycle distribution (up to 12 hours post-treatment) were measured by FACS analysis after propidium-iodide staining. Apoptosis was monitored for up to 36 hours post-treatment by Nicoletti-assay (with qualitative verification using DAPI staining). Results All cell lines exhibited the well-known increase of killing efficacy per unit dose of carbon ion exposure, with relative biological efficiencies at 10% survival (RBE10) ranging from 2.3 to 3.7 for the different cell lines. In combination with chemotherapy additive toxicity was the prevailing effect. Only in combination with gemcitabine or cisplatin (WiDr) or camptothecin (all cell lines) the photon sensitivity was slightly enhanced, whereas purely independent toxicities were found with the carbon ion irradiation, in all cases. Radiation-induced cell cycle changes displayed the generally observed dose-dependent G2-arrest with little effect on S-phase fraction for all cell lines for photons and for carbon ions. Only paclitaxel showed a significant induction of apoptosis in WiDr cell line but independent of the used radiation quality. Conclusions Combined effects of different chemotherapeutics with photons or with carbon ions do neither display qualitative nor substantial quantitative differences. Small radiosensitizing effects, when observed with photons are decreased with carbon ions. The data support the idea that a radiochemotherapy with common drugs and carbon ion irradiation might be as feasible as respective photon-based protocols. The present data serve as an important radiobiological basis for further combination experiments, as well as clinical studies on combination treatments. PMID:24192264

2013-01-01

344

Synthesis of confined electrically conducting carbon nanowires by heavy ion irradiation of fullerene thin film  

SciTech Connect

Conducting nanowires parallel to each other, embedded in fullerene matrix are synthesized by high energy heavy ion irradiation of thin fullerene film at low fluence (up to 5x10{sup 11} ions/cm{sup 2}). The conductivity of the conducting zone is about seven orders of magnitude higher than that of the fullerene matrix. The conducting nanowires are evidenced by conducting atomic force microscopy. The typical diameter of the conducting tracks is observed to be about 40-100 nm. The creation of conducting wires is explained by transformation of fullerene to conducting form of carbon in the ion track, surrounded by the polymerized zone. The polymerization of fullerene is evidenced by Fourier transform infrared spectroscopy.

Kumar, Amit; Avasthi, D. K.; Tripathi, A.; Kabiraj, D.; Singh, F.; Pivin, J. C. [Materials Science Group, Inter University Accelerator Centre, Post Box 10502, New Delhi 110067 (India); CSNSM, Ba circumflex timent 108, 91405 Orsay Campus (France)

2007-01-01

345

Dielectric response of polyethersulphone (PES) polymer irradiated with 145 MeV Ne{sup 6+} ions  

SciTech Connect

Heavy ion irradiation produces modifications in polymers and adapts their electrical, chemical and optical properties in the form of rearrangement of bonding, cross-linking, chain scission and formation of carbon rich clusters. Modification depends on the ion, its energy and fluence and the polymeric material. In the present work, a study of the dielectric response of pristine and heavy ion irradiated Polyethersulphone (PES) polymer film is carried out. 250 {mu}m thick PES films were irradiated to the fluences of 10{sup 12} and 10{sup 13} ions/cm{sup 2} with Ne{sup 6+} ions of 145 MeV energy from Variable Energy Cyclotron Centre, Kolkata On irradiation with heavy ions dielectric constant ({epsilon} Prime ) decreases at higher frequencies and increases with fluences. Variation of loss factor (tan {delta}) with frequency for pristine and irradiated with Si ions reveals that tan {delta} increases as the frequency increases. The tan{delta} also increases with fluence. Tan {delta} has positive values indicating the dominance of inductive behavior.

Ali, S. Asad; Khan, Wasi; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh-202002 (India); Kumar, Rajesh [University School of Basic and Applied Sciences, G.G.S.I.P. University, Delhi-110403 (India); Prasad, R. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh-202002 (India) and Vivekananda College of Technology and Management Aligarh-202002 (India)

2013-02-05

346

Effects of Prenatal Irradiation with an Accelerated Heavy-Ion Beam on Postnatal Development in Rats  

NASA Astrophysics Data System (ADS)

Effects on postnatal neurophysiological development in offspring were studied following exposure of pregnant Wistar rats to accelerated neon-ion beams with a LET value of about 30 keV mu m at a dose range from 0 1 Gy to 2 0Gy on the 15th day of gestation The age at which four physiologic markers appeared and five reflexes were acquired was examined prior to weaning Gain in body weight was monitored until the offspring were 3 months old Male offspring were evaluated as young adults using two behavioral tests The effects of X-rays at 200 kVp measured for the same biological end points were studied for comparison Our previous study on carbon-ion beams with a LET value of about 13 keV mu m was also cited to elucidate a possible LET-related effect For most of the endpoints at early age significant alteration was even observed in offspring prenatally received 0 1 Gy of accelerated neon ions while neither X rays nor carbon-ions under the same dose resulted in such a significant alteration compared to that from the sham-irradiated dams All offspring whose mothers received 2 0 Gy died prior to weaning Offspring from dams irradiated with accelerated neon ions generally showed higher incidences of prenatal death and preweaning mortality markedly delayed accomplishment in their physiological markers and reflexes and gain in body weight compared to those exposed to X-rays or carbon ions at doses of 0 1 to 1 5 Gy Significantly reduced ratios of main organ weight to body weight at postnatal ages of 30 60 and 90 days were also observed

Wang, B.; Murakami, M.; Eguchi-Kasai, K.; Nojima, K.; Shang, Y.; Tanaka, K.; Fujita, K.; Coffigny, H.; Hayata, I.

347

Phase Behavior of Xe Confined in Porous Vycor Glass Probed by 129Xe NMR Chemical Shift  

NASA Astrophysics Data System (ADS)

129Xe NMR spectroscopy is applied for direct observation of Xe confined in the porous Vycor glass. The chemical shifts of bulk and confined Xe are obtained simultaneously in a wide range of density from the gas phase to the liquid phase, including the supercritical region. The temperature and pressure dependences of the chemical shift of confined Xe are different from those of bulk Xe, which are approximately expressed by a linear function of bulk density. The phase transition of confined Xe is detected by the chemical shift, of which the pressure dependence along isotherms shows hysteresis loops.

Hiejima, Yusuke; Kanakubo, Mitsuhiro; Takebayashi, Yoshihiro; Aizawa, Takafumi; Kurata, Yoshiaki; Ikushima, Yutaka

2006-02-01

348

Synchrotron-radiation-stimulated etching of polydimethylsiloxane using XeF2 as a reaction gas  

PubMed Central

The synchrotron radiation (SR) stimulated etching of silicon elastomer polydimethylsiloxane (PDMS) using XeF2 as an etching gas has been demonstrated. An etching system with differential pumps and two parabolic focusing mirrors was constructed to perform the etching. The PDMS was found to be effectively etched by the SR irradiation under the XeF2 gas flow, and the etching process was area-selective and anisotropic. An extremely high etching rate of 40–50?µm (10?min)?1 was easily obtained at an XeF2 gas pressure of 0.2–0.4?torr. This suggests that SR etching using XeF2 gas provides a new microfabrication technology for thick PDMS membranes, which can open new applications such as the formation of three-dimensional microfluidic circuits. PMID:20029113

Chiang, Tsung-Yi; Makimura, Tetsuya; He, Tingchao; Torii, Shuichi; Yoshida, Tomoko; Tero, Ryugo; Wang, Changshun; Urisu, Tsuneo

2010-01-01

349

Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method  

SciTech Connect

Single crystals of sodium potassium niobate (K{sub 0.5}Na{sub 0.5})NbO{sub 3} (KNN) were grown by flux method and crystals were irradiated with 45 MeV Li ions to modify the electrical properties. Energy of the irradiated heavy ion was lower than the threshold energy to produce columnar defect and only clusters of defect was observed. The surface morphology of the irradiated single crystals was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the surface roughness value was found to increase with increasing fluence.

Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R. [Crystal Growth Centre, Anna University, Chennai (India)

2013-02-05

350

Lateral homogeneity of the electronic properties in pristine and ion-irradiated graphene probed by scanning capacitance spectroscopy  

PubMed Central

In this article, a scanning probe method based on nanoscale capacitance measurements was used to investigate the lateral homogeneity of the electron mean free path both in pristine and ion-irradiated graphene. The local variations in the electronic transport properties were explained taking into account the scattering of electrons by charged impurities and point defects (vacancies). Electron mean free path is mainly limited by charged impurities in unirradiated graphene, whereas an important role is played by lattice vacancies after irradiation. The local density of the charged impurities and vacancies were determined for different irradiated ion fluences. PMID:21711643

2011-01-01

351

Ion-irradiation induced reduction in Sr2Fe1.5Mo0.5O6-? perovskite  

NASA Astrophysics Data System (ADS)

The incorporation of radioactive elements in fission products (FPs) into complex oxides, where the elements are constrained in the structure and enhanced leaching and radioactive stability can be obtained, is an active research area in the nuclear fuel cycle. Perovskite structured Sr2Fe1.5Mo0.5O6-? (SFM) has the capability of incorporating several FPs (such as Sr and Mo) into the crystalline network simultaneously while maintaining a stabilized structure. The radiation damage effects on the structure changes of this polycrystalline SFM sample is conducted under various ion irradiations including 200 keV He ions to a fluence of 5 × 1020 ions m-2, 100 keV H to a fluence of 3 × 1021 ions cm-2, and 600 keV Kr ions to a fluence of 2.5 × 1019 ions m-2 at room temperature. Irradiation-induced structural evolution was examined by using grazing incidence X-ray diffraction and cross-sectional transmission electron microscopy. It was found that the irradiated SFM sample decomposed into a layered Sr4FeMoO8-? based phase and a metallic Fe based phase under light ion (He and H) irradiations. Nano-crystallized secondary phase was observed with particle sizes around 7 nm. These results suggest that irradiation-induced reducing atmospheres may affect the stability of crystalline structure in complex oxides. Experiment results also reveal an amorphization in the heavy ion Kr irradiated sample, while no amorphization is observed in He/H irradiated SFM.

Wang, Siwei; Tang, Ming; Brinkman, Kyle S.; Chen, Fanglin (Frank)

2014-05-01

352

Heavy ion irradiation and unloading effects on mouse lumbar vertebral microarchitecture, mechanical properties and tissue stresses.  

PubMed

Astronauts are exposed to both musculoskeletal disuse and heavy ion radiation in space. Disuse alters the magnitude and direction of forces placed upon the skeleton causing bone remodeling, while energy deposited by ionizing radiation causes free radical formation and can lead to DNA strand breaks and oxidative damage to tissues. Radiation and disuse each result in a net loss of mineralized tissue in the adult, although the combined effects, subsequent consequences for mechanical properties and potential for recovery may differ. First, we examined how a high dose (2 Gy) of heavy ion radiation ((56)Fe) causes loss of mineralized tissue in the lumbar vertebrae of skeletally mature (4 months old), male, C57BL/6 mice using microcomputed tomography and determined the influence of structural changes on mechanical properties using whole bone compression tests and finite element analyses. Next, we tested if a low dose (0.5 Gy) of heavy particle radiation prevents skeletal recovery from a 14-day period of hindlimb unloading. Irradiation with a high dose of (56)Fe (2 Gy) caused bone loss (-14%) in the cancellous-rich centrum of the fourth lumbar vertebra (L4) 1 month later, increased trabecular stresses (+27%), increased the propensity for trabecular buckling and shifted stresses to the cortex. As expected, hindlimb unloading (14 days) alone adversely affected microarchitectural and mechanical stiffness of lumbar vertebrae, although the reduction in yield force was not statistically significant (-17%). Irradiation with a low dose of (56)Fe (0.5 Gy) did not affect vertebrae in normally loaded mice, but significantly reduced compressive yield force in vertebrae of unloaded mice relative to sham-irradiated controls (-24%). Irradiation did not impair the recovery of trabecular bone volume fraction that occurs after hindlimb unloaded mice are released to ambulate normally, although microarchitectural differences persisted 28 days later (96% increase in ratio of rod- to plate-like trabeculae). In summary, (56)Fe irradiation (0.5 Gy) of unloaded mice contributed to a reduction in compressive strength and partially prevented recovery of cancellous microarchitecture from adaptive responses of lumbar vertebrae to skeletal unloading. Thus, irradiation with heavy ions may accelerate or worsen the loss of skeletal integrity triggered by musculoskeletal disuse. PMID:20466089

Alwood, J S; Yumoto, K; Mojarrab, R; Limoli, C L; Almeida, E A C; Searby, N D; Globus, R K

2010-08-01

353

Displacement damage-induced electrical and structural effects in gallium arsenide solar cells following ion irradiation  

NASA Astrophysics Data System (ADS)

For nearly two decades, deviations between experimental data and the nonionizing energy loss (NIEL) have been observed for GaAs devices. In particular, previous data has suggested that electrical parameters associated with GaAs solar cells can follow different energy dependences with NIEL but only at the higher proton energies. In this paper, displacement damage-induced electrical and structural effects in GaAs solar cells were monitored before and after irradiation with various ions. The radiation-induced defects responsible for causing electrical changes were characterized using illuminated current-voltage, deep level transient spectroscopy (DLTS), and electron beam induced current (EBIC) while the structural changes were monitored using transmission electron microscopy (TEM). The EBIC images showed the existence of radiation-induced active recombination volumes or defect clusters after irradiation with high energy protons (E ? 10 MeV) and 22 MeV silicon ions, which were not produced by lower energy protons. The TEM images revealed strain related defects that correspond to the same irradiation conditions for which the defect clusters were observed, and therefore, the defects in the TEM images are associated with those observed in the EBIC images. These defects were not observed prior to irradiation so the lattice strain in the material is definitely associated with irradiation-induced lattice defects. HRTEM imaging has shown that the disordered regions are not amorphous but probably most likely a cluster of vacancies and a surrounding region rich in interstitials, which is produced when a large number of neighboring atoms are displaced in collision cascades known as the displacement spike. The formation of the U-band defect as determined by DLTS seems to evolve under the same irradiation conditions as the defects in the images. This very broad U-band peak is consistent with what would be expected from defect clusters. From analyses of the recoil spectra, high energy recoils appear to be responsible for the formation of these disordered regions and these regions are independent of the total displacement damage energy deposited. This study has shown that NIEL scaling is only violated for incident ion energies when the defect clusters are observed.

Warner, Jeffrey Hamilton

354

Mutation effects of C2+ ion irradiation on the greasy Nitzschia sp.  

PubMed

Screening and nurturing algae with high productivity, high lipid content and strong stress resistance are very important in algae industry. In order to increase the lipid content, the Nitzschia sp. was irradiated with a 3MeV C(2+) beam. The sample pretreatment method was optimized to obtain the best mutagenic condition and the survival ratio curve. The positive mutants with a significant improvement in lipid content were screened and their C(2+) mutagenic effects were analyzed by comparing the greasiness and growth characteristics with the wild type algae. Results showed that when the Nitzschia sp. was cultivated in nutritious medium containing 10% glycerol solution, and dried on the filter for 5 min after centrifugation, the realization of the microalgae heavy ion mutagenesis could be done. The survival ratio curve caused by C(2+) irradiation was proved to be "saddle-shaped". A positive mutant was screened among 20 survivals after irradiation, the average lipid content of the mutation increased by 9.8% than the wild type after 4 generations. But the growth rate of the screened mutation didn't change after the heavy ion implantation compared to the wild type algae. PMID:24064032

Yang, Y N; Liu, C L; Wang, Y K; Xue, J M

2013-01-01

355

Induction and rejoining of DNA double-strand breaks in cho cells after heavy ion irradiation  

NASA Astrophysics Data System (ADS)

DNA double-strand breaks (DSBs) are the crucial events ultimately leading to cell inactivation. Aimed at understanding the biological action of the charged particle component of cosmic radiation, the induction of DSBs and their repairability was evaluated in Chinese hamster ovary (CHO-K1) cells after exposure to accelerated particles. Irradiations were performed with various ion species including O, Ni and Ca, covering a LET range from 20 to 2000 keV/mum. DSBs were determined for plateau-phase cells using the electrophoretic elution of radiation-induced DNA fragments in a static electric field combined with fluorescence scanning of ethidium bromide stained gels. Assuming a DSB yield of 22 DSB per Gy per cell, as derived from X-irradiation, cross-sections for DSB production were calculated from the corresponding fluence-effect curves at a fraction of 0.7 of DNA retained. The same ordinate was used as a reference for the calculation of relative biological efficiency (RBE) for DSB induction. At low LETs (<= 20 keV/mum) RBE values slightly above unity were obtained, but a decrease of RBE was observed with increasing LET. In the region of 100-200 keV/mum the RBE for initial DSB induction was clearly below unity. Rejoining of DSBs was assessed by measuring the fraction of DNA retained following post-irradiation incubation of cells under culture conditions. After exposure to Ca ions, DSB rejoining was considerably impaired compared to X-rays.

Taucher-Scholz, G.; Heilmann, J.; Kraft, G.

356

Multiple relaxation processes in high-energy ion irradiated kapton-H polyimide: Thermally stimulated depolarization current study  

NASA Astrophysics Data System (ADS)

High-energy ion irradiation effects on the thermally stimulated depolarization current (TSDC) behaviour of kapton-H samples (12.5 ?m) irradiated with 50 MeV Li ion (fluence 5 × 10 4, 10 5 and 5 × 10 5 ions/cm 2) have been investigated. The TSDC spectra of the irradiated samples reveal that the ?-peak (appearing around 80-110 °C) associated with dipolar relaxation has been significantly affected owing to the demerization of carbonyl groups due to irradiation. The TSDC spectra also reveal a new relaxation process (termed as ?-relaxation) around 30 °C, due to increased water absorptivity in irradiated samples. The peak around 200 °C (?-peak) associated with space charge relaxation process also shows a behavioural change with ion irradiation. The peak not only shifts towards the higher temperature with increasing fluence but also show an increase in its activation energy (0.33-0.99 eV) with increasing polarizing field. The creation of new deep energy trap centers due to the formation of conjugated bonds after irradiation is responsible for this modification. The Cole-Cole distribution curves show the formation of new sub-polar group with different characteristic relaxation time.

Garg, Maneesha; Quamara, J. K.

2006-05-01

357

Late Effects of Heavy Ion Irradiation on Ex Vivo Osteoblastogenesis and Cancellous Bone Microarchitecture  

NASA Technical Reports Server (NTRS)

Prolonged spaceflight causes degeneration of skeletal tissue with incomplete recovery even after return to Earth. We hypothesize that heavy ion irradiation, a component of Galactic Cosmic Radiation, damages osteoblast progenitors and may contribute to bone loss during long duration space travel beyond the protection of the Earth's magnetosphere. Male, 16 week old C57BL6/J mice were exposed to high LET (56 Fe, 600MeV) radiation using either low (5 or 10cGy) or high (50 or 200cGy) doses at the NASA Space Radiation Lab and were euthanized 3 - 4, 7, or 35 days later. Bone structure was quantified by microcomputed tomography (6.8 micron pixel size) and marrow cell redox assessed using membrane permeable, free radical sensitive fluorogenic dyes. To assess osteoblastogenesis, adherent marrow cells were cultured ex vivo, then mineralized nodule formation quantified by imaging and gene expression analyzed by RT PCR. Interestingly, 3 - 4 days post exposure, fluorogenic dyes that reflect cytoplasmic generation of reactive nitrogen/oxygen species (DAF FM Diacetate or CM H2DCFDA) revealed irradiation (50cGy) reduced free radical generation (20-45%) compared to sham irradiated controls. Alternatively, use of a dye showing relative specificity for mitochondrial superoxide generation (MitoSOX) revealed an 88% increase compared to controls. One week after exposure, reactive oxygen/nitrogen levels remained lower(24%) relative to sham irradiated controls. After one month, high dose irradiation (200 cGy) caused an 86% decrement in ex vivo nodule formation and a 16-31% decrement in bone volume to total volume and trabecular number (50, 200cGy) compared to controls. High dose irradiation (200cGy) up regulated expression of a late osteoblast marker (BGLAP) and select genes related to oxidative metabolism (Catalase) and DNA damage repair (Gadd45). In contrast, lower doses (5, 10cGy) did not affect bone structure or ex vivo nodule formation, but did down regulate iNOS by 0.54 - 0.58 fold. Thus, both low and high doses of heavy ion irradiation cause time dependent, adaptive changes in redox state within marrow cells but only high doses (50, 200cGy) inhibit osteoblastogenesis and cause cancellous bone loss. We conclude space radiation has the potential to cause persistent damage to bone marrow derived stem and progenitor cells for osteoblasts despite adaptive changes in cellular redox state.

Tran, Luan Hoang; Alwood, Joshua; Kumar, Akhilesh; Limoli, C. L.; Globus, Ruth

2012-01-01

358

Cavity morphology in a Ni based superalloy under heavy ion irradiation with hot pre-injected helium. II  

NASA Astrophysics Data System (ADS)

In the current investigation, TEM in-situ heavy ion (1 MeV Kr2+) irradiation with helium pre-injected at elevated temperature (400 °C) was conducted to simulate in-reactor neutron irradiation induced damage in CANDU spacer material Inconel X-750, in an effort to understand the effects of helium on irradiation induced cavity microstructures. Three different quantities of helium, 400 appm, 1000 appm, and 5000 appm, were pre-injected directly into TEM foils at 400 °C. The samples containing helium were then irradiated in-situ with 1 MeV Kr2+ at 400 °C to a final dose of 5.4 dpa (displacement per atom). Cavities were formed from the helium injection solely and the cavity density and size increased with increasing helium dosage. In contrast to previous heavy ion irradiations with cold pre-injected helium, heterogeneous nucleation of cavities was observed. During the ensuing heavy ion irradiation, dynamical observation showed noticeable size increase in cavities which nucleated close to the grain boundaries. A "bubble-void" transformation was observed after Kr2+ irradiation to high dose (5.4 dpa) in samples containing 1000 appm and 5000 appm helium. Cavity distribution was found to be consistent with in-reactor neutron irradiation induced cavity microstructures. This implies that the distribution of helium is greatly dependent on the injection temperature, and helium pre-injection at high temperature is preferred for simulating the migration of the transmutation produced helium.

Zhang, He; Yao, Zhongwen; Daymond, Mark R.; Kirk, Marquis A.

2014-03-01

359

Intense ultrashort laser-Xe cluster interaction  

NASA Astrophysics Data System (ADS)

The last several years have witnessed a surge of activity involving the interaction of clusters with intense ultrashort pulse lasers. The interest in laser-cluster interaction has not been only of academic interest, but also because of the wide variety of potential applications. Clusters can be used as a compact source of X-rays, incoherent as well as coherent, and of fast ions capable of driving a fusion reaction in deuterium plasmas. In one set of xenon cluster experiments, in particular, amplification of ˜2.8 Å X-rays has been observed [28]. X-ray amplification in cluster media is a phenomenon of critical importance and may lead to applications such as EUV lithography, EUV and X-ray microscopy, X-ray tomography, and variety of applications in biology and material sciences. However, while amplification of ˜2.8 Å X-rays has been documented in experiments, the mechanism for producing it remains to be fully understood. In this talk, a xenon model of laser-cluster interaction dynamics is presented to shed light on the processes responsible for amplification. The focus of this research is on the feasibility of creating population inversions and gain in some of the inner-shell hole state transitions within the M-shell of highly ionized xenon. The model couples a molecular dynamics (MD) treatment of the explosively-driven, non-Maxwellian cluster expansion to a comprehensive multiphoton-radiative ionization dynamic (ID) model including single- and double-hole state production within the Co- and Fe-like ionization stages of xenon. The hole-state dynamics is self-consistently coupled to a detailed valence-state collisional-radiative dynamics of the Ni-, Co-, and Fe-like ionization stages of xenon. In addition, the model includes tunneling ionization rates that confirm an initial condition assumption that Ni-like ground states can be created almost instantaneously, on the order of a femtosecond or less, i.e., at laser intensities larger than 1019 W/cm2, all of the N-shell, n = 4 electrons are striped from a xenon atom in less than a femtosecond. Because of the abundance of these ground states, large numbers of n = 2, inner-shell hole states and large population inversions can be created when the Ni-like ground states are photo- or collisionally ionized. Once the M-shell is entered, tunneling ionization slows down as does collisional ionization due to the fall in ion density as the cluster expands. Moreover, as the cluster density goes down, our combined MD and ID calculations show that so do the calculated population inversions. Thus, our calculations do not support the initial experimental data interpretations in which the measured gains have been associated with double holes in more highly ionized stages of xenon (Xe32+, Xe34+, Xe35+, and Xe37+), which our calculations suggest would require laser intensities in excess of 1.5 × 1020 W/cm2, for a 248 nm, ˜250 fs laser pulse focused in a gas of xenon clusters. At laser intensities used in the experiment, such ionization stages would be reached, but only later in time when cluster densities have fallen by several orders of magnitude from their initial values to values where pumping rates are too low and gains cannot be generated.

Davis, J.; Whitney, K. G.; Petrova, Tz. B.; Petrov, G. M.

2012-09-01

360

Irradiation induced dissolution of Cu and growth of Ag nanoclusters in Cu\\/Ag ion-exchanged soda-lime glass  

Microsoft Academic Search

Complex metal nanoclusters of Cu\\/Ag are formed in a soda-lime glass matrix by sequential copper and silver ion-exchange followed by ion irradiation. Optical absorption measurements showed signature of copper clusters alone in the Cu\\/Ag ion-exchanged sample. Irradiation of the ion-exchanged sample with He+ ions of energy 100 keV of different fluences resulted in the growth of the silver clusters with,

D. Manikandan; S. Mohan; P. Magudapathy; K. G. M Nair

2002-01-01

361

Electron impact desorption of Xe from the tungsten (110) plane. Technical report  

SciTech Connect

The electron stimulated desorption of Xe on the clean and on oxygen and CO covered tungsten (110) surfaces has been investigated. Only neutral Xe desorption was observed; a very small initial regime with cross section 10 to the minus 17th power sq cm. is followed by a slow decay with cross section 3 x 10 to the minus 19th power sq. cm. The Xe yield varies nonlinearly with coverage, suggesting desorption from edges of islands or from sites with less than their full complement of nearest neighbor Xe atoms. Desorption from oxygen or CO covered surfaces results in an apparent desorption cross section identical to that of the underlying adsorbate. This results from a kicking off of Xe by electron desorbed O or CO. The true cross sections for these processes are approx. 10 to the minus 14th power sq. cm. for Xe-O and approx. 10 to the minus 15th power sq. cm. for Xe-CO. Some speculations about the mechanism, particularly the absence of ions are presented.

Zhang, Q.J.; Gomer, R.

1981-03-01

362

Observations of void swelling in selected austenitic alloys during ion irradiation under a rising temperature ramp  

NASA Astrophysics Data System (ADS)

Results are given of a TEM study of the void swelling behaviour of CW AISI 321 (En58B), CW FV548 stainless steel and STA Nimonic PE16 alloy during 46 MeV nickel ion irradiation under a near-linear rising temperature ramp. The dose range for the ramp was 0-75 dpa and four temperature ranges were investigated using 50 ° C intervals from 500-550 ° C, 525-575 ° C, 575-625 ° C and 625-675 ° C. Swelling in CW 321 was found to be no greater than that observed after isothermal irradiation to 75 dpa at temperatures corresponding to the end-of-ramp temperatures. This was not the case for CW FV548 where the swelling for the temperature ranges of 525-575 ° C and 575-625 ° C was slightly greater than that observed under isothermal irradiation to 75 dpa. Swelling in STA PE16 in the lower temperature ranges of 500-550 ° C and 525-575°C was much higher than corresponding isothermal values but in the 600-700 ° C temperature range the swelling was close to isothermal values. The results on PE16 indicate that a steady increase in irradiation temperature from just below or just above the low temperature cut-off into the void swelling region produces a significant increase in swelling with respect to that expected under isothermal conditions. Possible interpretations of the observed swelling behaviour in these alloys are discussed.

Mazey, D. J.; Williams, T. M.; Bolster, D. E. J.

1988-07-01

363

Enhancement of impact-induced mechanoluminescence for structure health monitoring using swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

Mechanoluminescence (ML) materials have recently attracted considerable attention due to their potential applications as an imaging sensor for detecting damages and measuring stress distributions in complex structures, which is difficult for conventional methods. SrAl2O4:Eu2+ (SAOE) is a ML material with the best performance but it hydrolyzes rapidly under humid environment, which limits the scope of its applications especially in outdoor environments, e.g. structural health monitoring for buildings, bridges and tunnels. Thus ML materials with water resistance such as silicates and aluminosilicates have been developed, but the brightness of which is still much lower than SAOE. In this study, we report a novel method to improve the impact-induced ML in ML materials using the swift heavy ion (SHI) irradiation. The impact-induced ML intensity of CaSrAl2Si2O8:Eu2+ was dramatically enhanced by about one order of magnitude using SHI irradiation. Furthermore, higher electronic stopping power and higher irradiation fluence were found to be more effective for improving the impact-induced ML. It is considered that the trap density suitable for the impactinduced ML was increased by the SHI irradiation, resulting in the impact-induced ML enhancement. The underlying mechanism was discussed, which is of great importance for developing new ML materials for structure health monitoring.

Zhan, T. Z.; Xu, C. N.; Yamada, H.; Terasawa, Y.; Zhang, L.; Iwase, H.; Kawai, M.

2012-04-01

364

Micro-Raman study of the carbonization of polyimide induced by swift heavy ion irradiations  

NASA Astrophysics Data System (ADS)

We have done an extensive study of damage of polyimide (Kapton-H) thin films by heavy ion irradiations in the 1 MeV amu -1 energy range. We found that the irradiation-induced insulator-conductor transition proceeds through four stages on the basis of the progressive formation of a 3D graphite-like structure when track overlaps increase. All bulk dc conductivity and paramagnetic center volume density data were rescaled on a plot versus fluence ( ?t) times electronic stopping power ( Se) squared i.e. ?tSe2. Visible micro-Raman spectra were recorded in order to monitor the ion-induced modifications. It is seen that the spectral features of the pristine polymer progressively disappear during stages I and II, and that only two broad peaks at around 1360 and 1580 cm -1, corresponding respectively to the well-known D and G bands of disordered graphitic materials, remain in stages III and IV regardless of the ion. We address the evolution of the polymer material according to the four stages of the transition versus ?tSe2.

Costantini, J.-M.; Couvreur, F.; Salvetat, J.-P.; Bouffard, S.

2002-08-01

365

Structural characterization of TiN coatings on Si substrates irradiated with Ar ions  

SciTech Connect

The present study deals with TiN/Si bilayers irradiated at room temperature (RT) with 120 keV Ar ions. The TiN layers were deposited by d.c. reactive sputtering on Si(100) wafers to a thickness of {approx} 240 nm. After deposition the TiN/Si bilayers were irradiated to the fluences of 1 x 10{sup 15} ions/cm{sup 2} and 1 x 10{sup 16} ions/cm{sup 2}. Structural characterization was performed with Rutherford backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (XTEM), grazing angle X-ray diffraction (XRD) and atomic force microscopy (AFM). The results showed that the variation of the lattice constants, mean grain size and micro-strain can be attributed to the formation of the high density damage region in the TiN film structure. It has been found that this damage region is mainly distributed within {approx} 100 nm at surface of the TiN layers.

Popovic, M.; Novakovic, M. [Vinca Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Bibic, N., E-mail: natasabi@vinca.rs [Vinca Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia)

2009-12-15

366

Structural, thermal and optical behavior of 84 MeV oxygen and 120 MeV silicon ions irradiated PES  

NASA Astrophysics Data System (ADS)

In order to study structural, thermal and optical behavior, thin flat samples of polyethersulfone were irradiated with oxygen and silicon ions. The changes in properties were analyzed using different techniques viz: X-ray diffraction, thermo-gravimetric analysis, Fourier transform infrared, UV-visible and photoluminescence spectroscopy. A noticeable increase in the intensity of X-ray diffraction peaks was observed after irradiation with 84 MeV oxygen ions at low and medium fluences, which may be attributed to radiation-induced cross-linking in polymer. Fourier transform infrared and thermo-gravimetric analysis corroborated the results of X-ray diffraction analysis. No noticeable change in the Fourier transform infrared spectra of oxygen ion irradiated polyethersulfone were observed even at the highest fluence of 1 × 10 13 ions cm -2, but after irradiation with silicon ions, a reduction in intensity of almost all characteristic bands was revealed. An increase in the activation energy of decomposition of polyethersulfone was observed after irradiation with 84 MeV oxygen ions up to medium fluences but degradation was revealed at higher fluences. Similar trends were observed by photoluminescence analysis.

Samra, Kawaljeet Singh; Thakur, Sonika; Singh, Lakhwant

2011-03-01

367

Radiation blistering in inconel-625 due to 100 keV helium ion irradiation  

NASA Astrophysics Data System (ADS)

The objective of this study was to determine whether the change of angle of incidence of an ion beam impinging on surface blisters during their growth phase (before exfoliation) could influence the blister skin thickness and the blister crater depth. Polished, polycrystalline Inconel-625 samples were irradiated at room temperature and at normal incidence to the major sample surface with 100 keV helium ions to a total dose of 6.24 × 10 18 ions/cm 2. The results revealed that many exfoliated blisters leave craters which have two or three concentric pits. The blister skin thickness near the center of the blister was found to agree well with the calculated projected range of 100 keV He ions in nickel. However, the blister skin thickness of some exfoliated blisters along the edge of the fracture surface showed different thicknesses. A model is proposed to explain the observed blister crater/blister skin fracture features in terms of a change of angle of incidence of the incident ions to the surface during the growth phase of surface blisters.

Whitton, J. L.; Rao, A. S.; Kaminsky, M.

1988-05-01

368

Trapping of hydrogen isotopes in radiation defects formed in tungsten by neutron and ion irradiations  

NASA Astrophysics Data System (ADS)

Retention of D in neutron-irradiated W and desorption were examined after plasma exposure at 773 K. Deuterium was accumulated at a relatively high concentration up to a large depth of 50-100 ?m due to the trapping effects of defects uniformly induced in the bulk. A significant D release in a vacuum continued to temperatures ?1173 K because of the small effective diffusion coefficient and the long diffusion distance. Exposure of ion-irradiated W to D2 gas showed a clear correlation between concentrations of trapped and solute D as determined by the trapping-detrapping equilibrium. These observations indicated that the accumulation of tritium in high concentrations is possible even at high temperatures if the concentration of solute tritium is high, and baking at moderate temperatures is ineffective for removal of tritium deeply penetrating into the bulk. Nevertheless, clear enhancement of D release was observed under the presence of solute H.

Hatano, Y.; Shimada, M.; Alimov, V. Kh.; Shi, J.; Hara, M.; Nozaki, T.; Oya, Y.; Kobayashi, M.; Okuno, K.; Oda, T.; Cao, G.; Yoshida, N.; Futagami, N.; Sugiyama, K.; Roth, J.; Tyburska-Püschel, B.; Dorner, J.; Takagi, I.; Hatakeyama, M.; Kurishita, H.; Sokolov, M. A.

2013-07-01

369

Transformation of multiwalled carbon nanotubes to amorphous carbon nanorods under ion irradiation  

NASA Astrophysics Data System (ADS)

Amorphous carbon nanorods were synthesized from hollow multiwalled carbon nanotubes (MWCNTs) by low-energy Ar ion irradiation at room temperature. The obtained nanorods were investigated by Raman spectroscopy, transmission electron microscopy (TEM), soft X-ray photoelectron spectroscopy (XPS), and soft X-ray absorption spectroscopy (XAS). It was found that the diameter of the MWCNTs significantly increased with increasing the fluence. Finally, the original hollow structure and the graphite (002) TEM diffraction spots of MWCNTs completely disappeared and a broadening of Raman spectra occurred, indicating the amorphization of MWCNTs. The increase in the diameter by the irradiation can be explained by the bending and the randomization of the broken carbon hexagonal networks, and the accumulation of knocked-on atoms. The XPS and XAS measurements also support the formation of amorphous carbon nanorods.

Honda, Shin-ichi; Tamura, Ryosuke; Nosho, Yusuke; Tsukagoshi, Akira; Niibe, Masahito; Terasawa, Mititaka; Hirase, Ryuji; Izumi, Hirokazu; Yoshioka, Hideki; Niwase, Keisuke; Taguchi, Eiji; Lee, Kuei-Yi; Oura, Masaki

2014-02-01

370

Single phase formation of Co-implanted ZnO thin films by swift heavy ion irradiation: Optical studies  

SciTech Connect

Low temperature photoluminescence and optical absorption studies on 200 MeV Ag{sup +15} ion irradiated Co-implanted ZnO thin films were studied. The Co clusters present in as implanted samples were observed to be dissolved using 200 MeV Ag{sup +15} ion irradiation with a fluence of 1x10{sup 12} ions/cm{sup 2}. The photoluminescence spectrum of pure ZnO thin film was characterized by the I{sub 4} peak due to the neutral donor bound excitons and the broad green emission. The Co-doped ZnO films show three sharp levels and two shoulders corresponding to 3t{sub 2g} and 2e{sub g} levels of crystal field splitted Co d orbitals, respectively. The ultraviolet-visible absorption spectroscopy also shows the systematic variation of band gap after 200 MeV Ag{sup +15} ion irradiation.

Kumar, Ravi; Singh, Fouran; Angadi, Basavaraj; Choi, Ji-Won; Choi, Won-Kook; Jeong, Kwangho; Song, Jong-Han; Khan, M. Wasi; Srivastava, J. P.; Kumar, Ajay; Tandon, R. P. [Materials Science Division, Inter-University Accelerator Centre, P.O. Box 10502, Aruna Asaf Ali Marg, New Delhi 110067 (India); Thin Films Materials Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Institute of Physics and Applied Physics, Yonsei University, Shincheon-dong 134, Seoul 120-749 (Korea, Republic of); Advanced Analysis Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Department of Physics and Astrophysics, Delhi University, Delhi 110007 (India)

2006-12-01

371

4D particle therapy PET simulation for moving targets irradiated with scanned ion beams  

NASA Astrophysics Data System (ADS)

Particle therapy positron emission tomography (PT-PET) allows for an in vivo and in situ verification of applied dose distributions in ion beam therapy. Since the dose distribution cannot be extracted directly from the ?+-activity distribution gained from the PET scan the validation is done by means of a comparison between the reconstructed ?+-activity distributions from a PT-PET measurement and from a PT-PET simulation. Thus, the simulation software for generating PET data predicted from the treatment planning is an essential part of the dose verification routine. For the dose monitoring of intra-fractionally moving target volumes the PET data simulation needs to be upgraded by using time resolved (4D) algorithms to account correctly for the motion dependent displacement of the positron emitters. Moreover, it has to consider the time dependent relative movement between target volume and scanned beam to simulate the accurate positron emitter distribution generated during irradiation. Such a simulation program is presented which properly proceeds with motion compensated dose delivery by scanned ion beams to intra-fractionally moving targets. By means of a preclinical phantom study it is demonstrated that even the sophisticated motion-mitigated beam delivery technique of range compensated target tracking can be handled correctly by this simulation code. The new program is widely based on the 3D PT-PET simulation program which had been developed at the Helmholtz-Zentrum Dresden-Rossendorf, Germany (HZDR) for application within a pilot project to simulate in-beam PET data for about 440 patients with static tumor entities irradiated at the former treatment facility of the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany (GSI). A simulation example for a phantom geometry irradiated with a tracked 12C-ion beam is presented for demonstrating the proper functionality of the program.

Laube, K.; Menkel, S.; Bert, C.; Enghardt, W.; Helmbrecht, S.; Saito, N.; Fiedler, F.

2013-02-01

372

4D particle therapy PET simulation for moving targets irradiated with scanned ion beams.  

PubMed

Particle therapy positron emission tomography (PT-PET) allows for an in vivo and in situ verification of applied dose distributions in ion beam therapy. Since the dose distribution cannot be extracted directly from the ?(+)-activity distribution gained from the PET scan the validation is done by means of a comparison between the reconstructed ?(+)-activity distributions from a PT-PET measurement and from a PT-PET simulation. Thus, the simulation software for generating PET data predicted from the treatment planning is an essential part of the dose verification routine. For the dose monitoring of intra-fractionally moving target volumes the PET data simulation needs to be upgraded by using time resolved (4D) algorithms to account correctly for the motion dependent displacement of the positron emitters. Moreover, it has to consider the time dependent relative movement between target volume and scanned beam to simulate the accurate positron emitter distribution generated during irradiation. Such a simulation program is presented which properly proceeds with motion compensated dose delivery by scanned ion beams to intra-fractionally moving targets. By means of a preclinical phantom study it is demonstrated that even the sophisticated motion-mitigated beam delivery technique of range compensated target tracking can be handled correctly by this simulation code. The new program is widely based on the 3D PT-PET simulation program which had been developed at the Helmholtz-Zentrum Dresden-Rossendorf, Germany (HZDR) for application within a pilot project to simulate in-beam PET data for about 440 patients with static tumor entities irradiated at the former treatment facility of the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany (GSI). A simulation example for a phantom geometry irradiated with a tracked (12)C-ion beam is presented for demonstrating the proper functionality of the program. PMID:23306167

Laube, K; Menkel, S; Bert, C; Enghardt, W; Helmbrecht, S; Saito, N; Fiedler, F

2013-02-01

373

Cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with accelerated 56Fe ions  

NASA Technical Reports Server (NTRS)

We examined cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with high-energy 56Fe ions. Cells were irradiated with graded doses of 56Fe ions (1 GeV/nucleon) accelerated with the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The survival curves for cells plated 1 h after irradiation (immediate plating) showed little or no shoulder. However, the survival curves for cells plated 24 h after irradiation (delayed plating) had a small initial shoulder. The RBE for 56Fe ions compared to 137Cs gamma rays was 1.99 for immediate plating and 2.73 for delayed plating at the D10. The repair ratio (delayed plating/immediate plating) was 1.67 for 137Cs gamma rays and 1.22 for 56Fe ions. The dose-response curves for initially measured and residual chromatid fragments detected by the Calyculin A-mediated premature chromosome condensation technique showed a linear response. The results indicated that the induction frequency for initially measured fragments was the same for 137Cs gamma rays and 56Fe ions. On the other hand, approximately 85% of the fragments induced by 137Cs gamma rays had rejoined after 24 h of postirradiation incubation; the corresponding amount for 56Fe ions was 37%. Furthermore, the frequency of chromatid exchanges induced by gamma rays measured 24 h after irradiation was higher than that induced by 56Fe ions. No difference in the amount of chromatid damage induced by the two types of radiations was detected when assayed 1 h after irradiation. The results suggest that high-energy 56Fe ions induce a higher frequency of complex, unrepairable damage at both the cellular and chromosomal levels than 137Cs gamma rays in the target cells for radiation-induced lung cancers.

Suzuki, M.; Piao, C.; Hall, E. J.; Hei, T. K.

2001-01-01

374

Comparing the biological washout of ?(+)-activity induced in mice brain after (12)C-ion and proton irradiation.  

PubMed

In clinical ion beam therapy, protons as well as heavier ions such as carbon are used for treatment. For protons, ?(+)-emitters are only induced by fragmentation reactions in the target (target fragmentation), whereas for heavy ions, they are additionally induced by fragmentations of the projectile (further referred to as autoactivation). An approach utilizing these processes for treatment verfication, by comparing measured Positron Emission Tomography (PET) data to predictions from Monte Carlo simulations, has already been clinically implemented. For an accurate simulation, it is important to consider the biological washout of ?(+)-emitters due to vital functions. To date, mathematical expressions for washout have mainly been determined by using radioactive beams of (10)C- and (11)C-ions, both ?(+)-emitters, to enhance the counting statistics in the irradiated area. Still, the question of how the choice of projectile (autoactivating or non-autoactivating) influences the washout coefficients, has not been addressed.In this context, an experiment was carried out at the Heidelberg Ion Beam Therapy Center with the purpose of directly comparing irradiation-induced biological washout coefficients in mice for protons and (12)C-ions. To this aim, mice were irradiated in the brain region with protons and (12)C-ions and measured after irradiation with a PET/CT scanner (Siemens Biograph mCT). After an appropriate waiting time, the mice were sacrificed, then irradiated and measured again under similar conditions. The resulting data were processed and fitted numerically to deduce the main washout parameters.Despite the very low PET counting statistics, a consistent difference could be identified between (12)C-ion and proton irradiated mice, with the (12)C data being described best by a two component fit with a combined medium and slow washout fraction of 0.50 ± 0.05 and the proton mice data being described best by a one component fit with only one (slow) washout fraction of 0.73 ± 0.06. PMID:25383509

Ammar, C; Frey, K; Bauer, J; Melzig, C; Chiblak, S; Hildebrandt, M; Unholtz, D; Kurz, C; Brons, S; Debus, J; Abdollahi, A; Parodi, K

2014-12-01

375

Mass spectrometry analysis of etch products from CR-39 plastic irradiated by heavy ions  

NASA Astrophysics Data System (ADS)

As a feasibility study, gas chromatography-mass spectrometry (GC-MS) and matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) have been applied to analyze etch products of CR-39 plastic (one of the most frequently used solid states nuclear track detector) for the understanding of track formation and etching mechanisms by heavy ion irradiation. The etch products of irradiated CR-39 dissolved in sodium hydroxide solution (NaOH) contain radiation-induced fragments. For the GC-MS analysis, we found peaks of diethylene glycol (DEG) and a small but a definitive peak of ethylene glycol (EG) in the etch products from CR-39 irradiated by 60 MeV N ion beams. The etch products of unirradiated CR-39 showed a clear peak of DEG, but no other significant peaks were found. DEG is known to be released from the CR-39 molecule as a fragment by alkaline hydrolysis reaction of the polymer. We postulate that EG was formed as a result of the breaking of the ether bond (C-O-C) of the DEG part of the CR-39 polymer by the irradiation. The mass distribution of polyallylalcohol was obtained from the etch products from irradiated and unirradiated CR-39 samples by MALDI-MS analysis. Polyallylalcohol, with the repeating mass interval of m/z = 58 Da (dalton) between m/z = 800 and 3500, was expected to be produced from CR-39 by alkaline hydrolysis. We used IAA as a matrix to assist the ionization of organic analyte in MALDI-MS analysis and found that peaks from IAA covered mass spectrum in the lower m/z region making difficult to identify CR-39 fragment peaks which were also be seen in the same region. The mass spectrometry analysis using GC-MS and MALDI-MS will be powerful tools to investigate the radiation-induced polymeric fragments and helping to understand the track formation mechanism in CR-39 by heavy ions.

Kodaira, S.; Nanjo, D.; Kawashima, H.; Yasuda, N.; Konishi, T.; Kurano, M.; Kitamura, H.; Uchihori, Y.; Naka, S.; Ota, S.; Ideguchi, Y.; Hasebe, N.; Mori, Y.; Yamauchi, T.

2012-09-01

376

Nanostructuring of high-TC superconductors via masked ion irradiation for efficient ordered vortex pinning  

NASA Astrophysics Data System (ADS)

We studied vortex dynamics in a YBa2Cu3O7-? thin film with two different sources of pinning: intrinsic random defects and an artificial square array of defects created by masked ion irradiation. We study commensurability effects between the vortex lattice and the pinning array as a function of the vortex velocity v and the temperature. We find that at low temperatures the commensurability effects (magneto-resistance drop at the matching fields) are stronger at low velocities, in contrast with the behavior previously observed in low-critical-temperature superconductors.

Trastoy, J.; Rouco, V.; Ulysse, C.; Bernard, R.; Faini, G.; Lesueur, J.; Briatico, J.; Villegas, J. E.

2014-11-01

377

Lateral Electron Transport in High-Intensity Laser-Irradiated Foils Diagnosed by Ion Emission  

SciTech Connect

An experimental investigation of lateral electron transport in thin metallic foil targets irradiated by ultraintense ({>=}10{sup 19} W/cm{sup 2}) laser pulses is reported. Two-dimensional spatially resolved ion emission measurements are used to quantify electric-field generation resulting from electron transport. The measurement of large electric fields ({approx}0.1 TV/m) millimeters from the laser focus reveals that lateral energy transport continues long after the laser pulse has decayed. Numerical simulations confirm a very strong enhancement of electron density and electric field at the edges of the target.

McKenna, P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX (United Kingdom); Carroll, D. C.; Ledingham, K. W. D.; McCanny, T.; Robson, L. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Clarke, R. J.; Neely, D.; Robinson, A. P. L. [CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX (United Kingdom); Evans, R. G. [CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX (United Kingdom); Department of Physics, Imperial College, London, SW7 2AZ (United Kingdom); Lindau, F.; Lundh, O.; Wahlstroem, C.-G. [Department of Physics, Lund University, P.O. Box 118, S-22100 Lund (Sweden); Simpson, P. T.; Zepf, M. [Department of Physics and Astronomy, Queen's University Belfast, Belfast BT7 1NN (United Kingdom)

2007-04-06

378

Effects of carbon ion beam irradiation on lung injury and pulmonary fibrosis in mice  

PubMed Central

Radiation-induced lung injury is a well-described complication of nuclear accidents, marrow-transplant pretreatment and thoracic radiotherapy. The mechanism is complex and no special therapy for it is available at present. To study radiation pulmonary injury following heavy ion radiotherapy for thoracic tumors, Kunming mice were randomly divided into 4 groups: normal control and 2, 4 and 6 Gy irradiation groups which underwent whole-body exposure to 235 MeV/u 12C6+ administered at the Heavy Ion Research Facility in Lanzhou (HIRFL). The pathological changes were observed by hematoxylin and eosin staining and the hydroxyproline (HP) content was assessed by spectrophotometry at months 1, 2, 3, 4, 5 and 6 after radiation exposure. In addition, the expression of tumor necrosis factor (TNF)-? and transforming growth factor (TGF)-? in the lung tissues was measured. The results showed that, compared with the control group, the lung tissue HP content was increased following irradiation but did not statistically significantly change after 4 months in the 4- and 6-Gy-treated groups. However, in the 2-Gy-treated group, the HP content was markedly increased between months 1 and 4 and decreased after month 4. The extent of the lung injury was significantly increased by the higher radiation dosages but was relieved in the 2 Gy group as the time since irradiation increased. The results also revealed that the levels of TNF-? were upregulated and reached a maximum at month 2, but decreased noticeably 2 months later in the experimental groups. The expression of TGF-? increased markedly in month 4 and was altered little in the 4- and 6-Gy-treated groups but decreased sharply in the 2 Gy irradiation group after month 4. These findings suggest that heavy ion radiotherapy for chest tumors causes lung injury to a certain extent, while there is likely to be little injury to lungs treated with <2 Gy, which provides scientific evidence for the use of heavy ion therapy for thoracic tumors. PMID:23407465

WU, ZHENHUA; WANG, XINYU; YANG, RONG; LIU, YANG; ZHAO, WEIPING; SI, JIN; MA, XIAOFEI; SUN, CHAO; LIU, YUANYUAN; TAN, YONG; LIU, WEI; ZHANG, XIN; DI, CUIXIA; WANG, ZHENHUA; ZHANG, HONG; ZHANG, ZHONGXIANG

2013-01-01

379

The aXe SIMulation package aXeSIM User manual version 1.4  

E-print Network

for supporting the slitless spectroscopic modes of the Hubble instruments ACS and WFC3 until late 2010The aXe SIMulation package aXeSIM User manual version 1.4 M. K¨ummel and J.R. Walsh, H. Kuntschner-code . . . . . . . . . . . . . . . . . . . . . . . . 15 2.4 aXeSIM Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3 Illustrated a

Sirianni, Marco

380

Surface morphology, microstructure and properties of as-cast AZ31 magnesium alloy irradiated by high intensity pulsed ion beams  

NASA Astrophysics Data System (ADS)

High intensity pulsed ion beam (HIPIB) irradiation was performed as surface modification to improve the properties of as-cast AZ31 magnesium (Mg) alloys. The surface morphology and microstructure of the irradiated Mg alloys were characterized and their microhardness, wear resistance and corrosion resistance before and after HIPIB irradiation were measured. The results show that the formation of crater on the surface was attributed to the particles impacted from the irradiated cathode material. HIPIB irradiation resulted in more vacancy defects on the surface of the material. Moreover, new dislocations were generated by the reaction between vacancies, and the dislocation configuration was also changed. These variations caused by the HIPIB are beneficial for improving the material properties. After 10 shots of irradiation, the average microhardness increased by 27.1% but the wear rate decreased by 38.5%. The corrosion rate was reduced by 24.8% according to the salt spray corrosion experiment.

Ma, Xuesong; Zhang, Gang; Wang, Guotian; Zhu, Guoliang; Zhou, Wei; Wang, Jun; Sun, Baode

2014-08-01

381

Correlation between structure and electrical transport in ion-irradiated graphene grown on Cu foils  

SciTech Connect

Graphene grown by chemical vapor deposition and supported on SiO{sub 2} and sapphire substrates was studied following the controlled introduction of defects induced by 35 keV carbon ion irradiation. Changes in Raman spectra for fluences ranging from 10{sup 12} to 10{sup 15} cm{sup -2} indicate that the structure of graphene evolves from a highly ordered layer, to a patchwork of disordered domains, to an essentially amorphous film. These structural changes result in a dramatic decrease in the Hall mobility by orders of magnitude while, remarkably, the Hall concentration remains almost unchanged, suggesting that the Fermi level is pinned at a hole concentration near 1x10{sup 13} cm{sup -2}. A model for scattering by resonant scatterers is in good agreement with mobility measurements up to an ion fluence of 1x10{sup 14} cm{sup -2}.

Buchowicz, Grant; Stone, Peter R.; Dubon, Oscar D. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Robinson, Jeremy T.; Cress, Cory D. [Naval Research Laboratory, Washington, D.C. 20375 (United States); Beeman, Jeffrey W. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2011-01-17

382

C/CrC nanocomposite coating deposited by magnetron sputtering at high ion irradiation conditions  

SciTech Connect

CrC with the fcc NaCl (B1) structure is a metastable phase that can be obtained under the non-equilibrium conditions of high ion irradiation. A nano-composite coating consisting of amorphous carbon embedded in a CrC matrix was prepared via the unbalanced magnetron sputtering of graphite and Cr metal targets in Ar gas with a high ionized flux (ion-to-neutral ratio Ji/Jn = 6). The nanoscale amorphous carbon clusters self-assembled into layers alternated by CrC, giving the composite a multilayer structure. The phase, microstructure, and composition of the coating were characterized using x-ray diffraction, transmission electron microscopy, and aberration corrected scanning transmission electron microscopy coupled with electron energy loss spectroscopy. The interpretation of the true coating structure, in particular the carbide type, is discussed.

Zhou, Z.; Rainforth, W. M. [Department of Materials Science and Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom); Gass, M. H.; Bleloch, A. [SuperSTEM at Daresbury Laboratory, Daresbury, Cheshire, WA4 4AD (United Kingdom); Ehiassarian, A. P.; Hovsepian, P. Eh. [Materials Engineering Research Institute, Sheffield Hallam University, Sheffield, S1 1WB (United Kingdom)

2011-10-01

383

Correlation between structure and electrical transport in ion-irradiated graphene grown on Cu foils  

SciTech Connect

Graphene grown by chemical vapor deposition and supported on SiO2 and sapphire substrates was studied following controlled introduction of defects induced by 35 keV carbon ion irradiation. Changes in Raman spectra following fluences ranging from 1012 cm-2 to 1015 cm-2 indicate that the structure of graphene evolves from a highly-ordered layer, to a patchwork of disordered domains, to an essentially amorphous film. These structural changes result in a dramatic decrease in the Hall mobility by orders of magnitude while, remarkably, the Hall concentration remains almost unchanged, suggesting that the Fermi level is pinned at a hole concentration near 1x1013 cm-2. A model for scattering by resonant scatterers is in good agreement with mobility measurements up to an ion fluence of 1x1014 cm-2.

Buchowicz, G.; Stone, P.R.; Robinson, J.T.; Cress, C.D.; Beeman, J.W.; Dubon, O.D.

2010-11-04

384

Effects of carbon ion beam irradiation on the shoot regeneration from in vitro axillary bud explants of the Impatiens hawkeri  

NASA Astrophysics Data System (ADS)

Accelerated ion beams is an excellent mutagen in plant breeding which can induce higher mutation frequencies and wider mutation spectrum than those of low linear energy transfer (LET) irradiations, such as X-rays (Okamura et al. 2003, Yamaguchi et al. 2003). Mutation breeding operation of two Saintpaulia ionahta cultivars using the method combining plant tissue culture technique and carbon ion beam irradiations were set out at Institute of Modern Physics from 2005 (Zhou et al. 2006). The effects of 960 MeV carbon ion beam and 8 MeV X-ray irradiations on regenerated shoots of Impatiens hawkeri from another kind of explants named in vitro axillary buds explants were studied recently. The biology endpoints in this study included relative number of roots (RNR), relative length of roots (RLR), relative height of shoots (RHS), relative number of nodes (RNN), survival fraction (SF) and morphology changes in the regenerated shoots. The experimental results showed that carbon ion beams inhibited the root and stem developments of axillary bud explants more severely than X-rays did. And the 50% lethal dose (LD50 ) is about 23.3 Gy for the carbon ion beam and 49.1 Gy for the X-rays, respectively. Relative biological effectiveness (RBE) of Impatiens hawkeri with respect to X-rays according to 50% SF was about two. Secondly, the percentage of shoots regenerated with malformed shoots including curliness, carnification, nicks in all Impatiens hawkeri axillary bud explants irradiated with carbon ion beam at 20 Gy accounted for 55.6%, while the highest number for the 40 Gy X-ray irradiation was 40%. Last, many regenerated shoots whose vascular bundle fused together were obtained only from explants irradiated with carbon ion beams. Based on the results above, it can be concluded that the effect of mutation induction by carbon ion beam irradiation on the axillary explants of Impatiens hawkeri is better than that by X-ray irradiation; and the optimal mutagenic dose varies from 20 Gy for carbon ion beam irradiation.

Zhou, Libin; Zhou, Libin; Li, Wenjian; Li, Ping; Dong, Xicun; Qu, Ying; Ma, Shuang; Li, Qiang

385

160 MeV Ni12+ ion irradiation effects on the structural, optical and electrical properties of spherical polypyrrole nanoparticles  

NASA Astrophysics Data System (ADS)

In this study we report 160 MeV Ni12+ swift heavy ion irradiation induced enhancement in the structural, optical and electrical properties of spherical polypyrrole (PPy) nanoparticles. High resolution transmission electron microscope results show that the pristine PPy nanoparticles have an average diameter of 11 nm while upon irradiation the average diameter increases to 18 nm at the highest ion fluence of 1 × 1012 ions/cm2. X-ray diffraction studies show an enhancement of crystallinity and average crystallite size of PPy nanoparticles with increasing fluence. Studies of Fourier transform infrared spectra suggest the structural modifications of different functional groups upon irradiation. It also reveals that different functional groups have different sensitivity to irradiation. The infrared active N-H vibrational band at 3695 cm-1 is more sensitive to irradiation with a formation cross-section of 5.77 × 10-13 cm2 and effective radius of 4.28 nm. The UV-visible absorption spectra of PPy nanoparticles show that the absorption band undergoes a red shift with increasing fluence. Moreover upon irradiation the optical band gap energy decreases and Urbach's energy increases with fluence. Thermo-gravimetric analysis studies suggest that upon irradiation the thermal stability of PPy nanoparticles increases which may be attributed to their enhanced crystallinity. Current-voltage characteristics of PPy nanoparticles exhibit non-Ohmic, symmetric behavior which increases with fluence.

Hazarika, J.; Kumar, A.

2014-01-01

386

Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties  

SciTech Connect

A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NCs) of Fe core-Fe{sub 3}O{sub 4} shell or fully oxidized Fe{sub 3}O{sub 4}. Films of these NC on Si(100) or MgO(100)/Fe{sub 3}O{sub 4}(100) were irradiated to 10{sup 16} Si{sup 2+}/cm{sup 2} near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the NC films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.

McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor [Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, Washington 99352 (United States)] [Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, Washington 99352 (United States); Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You [Department of Physics, University of Idaho, Moscow, Idaho 83844 (United States)] [Department of Physics, University of Idaho, Moscow, Idaho 83844 (United States); Burks, Edward C.; Liu, Kai [Department of Physics, University of California, Davis, California 95616 (United States)] [Department of Physics, University of California, Davis, California 95616 (United States)

2013-08-28

387

Antiradiation Vaccine: Technology Development- Radiation Tolerance,Prophylaxis, Prevention And Treatment Of Clinical Presentation After Heavy Ion Irradiation.  

NASA Astrophysics Data System (ADS)

Introduction: Research in the field of biological effects of heavy charged particles is necessary for both heavy-ion therapy (hadrontherapy) and protection from the exposure to galactic cosmic radiation in long-term manned space missions.[Durante M. 2004] In future crew of long-term manned missions could operate in exremely high hadronic radiation areas of space and will not survive without effective radiation protection. An Antiradiation Vaccine (AV) must be an important part of a countermeasures regimen for efficient radiation protection purposes of austronauts-cosmonauts-taukonauts: immune-prophylaxis and immune-therapy of acute radiation toxic syndromes developed after heavy ion irradiation. New technology developed (AV) for the purposes of radiological protection and improvement of radiation tolerance and it is quite important to create protective immune active status which prevent toxic reactions inside a human body irradiated by high energy hadrons.[Maliev V. et al. 2006, Popov D. et al.2008]. High energy hadrons produce a variety of secondary particles which play an important role in the energy deposition process, and characterise their radiation qualities [Sato T. et al. 2003] Antiradiation Vaccine with specific immune-prophylaxis by an anti-radiation vaccine should be an important part of medical management for long term space missions. Methods and experiments: 1. Antiradiation vaccine preparation standard, mixture of toxoid form of Radiation Toxins [SRD-group] which include Cerebrovascular RT Neurotoxin, Cardiovascular RT Neurotoxin, Gastrointestinal RT Neurotoxin, Hematopoietic RT Hematotoxin. Radiation Toxins of Radiation Determinant Group isolated from the central lymph of gamma-irradiated animals with Cerebrovascular, Cardiovascular, Gastro-intestinal, Hematopoietic forms of ARS. Devices for radiation are "Panorama", "Puma". 2. Heavy ion exposure was accomplished at Department of Research Institute of Nuclear Physics, Dubna, Russia. The heavy ions irradiation was generated in heavy ion (Fe56) accelerator - UTI. Heavy Ion linear transfer energy - 2000- 2600 KeV -mkm, 600 MeV -92U. Absorbed Dose - 3820 Rad. Experimental Design: Rabbits from all groups were irradiated by heavy ion accelerator. Group A: control-10 rabbits; Group B: placebo-5 rabbits; Group C: Radioprotectant Cystamine (50 mg-kg)-5 rabbits, 15 minutes before irradiation - 5 rabbits; Group D: Radioprotectant Gammafos (Amifostine 400mg -kg ) - 5 rabbits; Group E: Antiradiation Vaccine: subcutaneus administration or IM - 2 ml of active substance, 14 days before irradiation Results: Group A 100% mortality within two hours after heavy ion irradiation with clinical symptoms of Acute Cerebro- and Cardio-Vascular Radiation syndromes. Group B 100% mortality within 15 hours following irradiation. Group C 100% mortality within 14-15 hours after irradiation. Group D 100% mortality within 15-16 hours after irradiation. In groups A- D registered the development of acute radiation cerebrovascular and cardiovascular syndromes and also extensive burns. of skin produced rapid death. Group E -100% mortality in 280-290 hours (12 days) following heavy ion irradiation with animals exhibiting a combination or individual forms of Acute Cerebrovascular, Cardiovascular, and Gastrointestinal forms and focal skin burns. Discussion Antiradiation vaccine and immune-prophylaxis is an effective method of neutralization of Radiation Toxins. Vaccination before irradiation extended survival time after irradiation with heavy ions from two hours up to 300 hours. Clinical signs, clinical features, symptoms were somewhat attenuated. Degree of clinical forms of Acute Radiation Syndromes were diminished in their clinical manifestation and severity. Groups A-D demonstrated extremely severe level of Cerebrovascular and Cardiovascular forms of Acute Radiation Syndromes and lethality 100% was registered in short time after irradiation. Radiation induced burns in this groups (with Cutaneous sub-syndrome of ARS - Degree 4, that diffuse deep into soft tissues with extensi

Popov, Dmitri; Maliev, Slava; Jones, Jeffrey

388

Single-cell/Single-particle Irradiation Using Heavy-ion Microbeams  

NASA Astrophysics Data System (ADS)

Heavy charged particles transfer their energy to biological organisms through high-density ionization along the particle trajectories. The population of cells exposed to a very low dose of heavy-ion beams contains a few cells hit by a particle, while the majority of the cells receive no radiation damage. At somewhat higher doses, some of the cells receive two or more events according to the Poisson distribution of ion injections. This fluctuation of particle trajectories through individual cells makes interpretation of radiological effects of heavy ions difficult. Furthermore, there has recently been an increasing interest in ionizing radiation-induced “bystander effects”, that is, radiation effects transmitted from hit cells to neighboring un-hit cells. Therefore, we have established a single-cell/single-particle irradiation system using a heavy-ion microbeam apparatus at JAEA-Takasaki to study radiobiological processes in hit cells and bystander cells exposed to low dose and low dose-rate high-LET radiations, in ways that cannot be achieved using conventional broad-field exposures.

Kobayashi, Yasuhiko

389

Radiosensitizing effect of gold nanoparticles in carbon ion irradiation of human cervical cancer cells  

SciTech Connect

Noble metal nanoparticles have received considerable attention in biotechnology for their role in bio sensing due to surface plasmon resonance, medical diagnostics due to better imaging contrast and therapy. The radiosensitization effect of gold nanoparticles (AuNP) has been gaining popularity in radiation therapy of cancer cells. The better depth dose profile of energetic ion beam proves its superiority over gamma radiation for fighting against cancer. In the present work, the glucose capped gold nanoparticles (Glu-AuNP) were synthesised and internalized in the HeLa cells. Transmission electron microscopic analysis of ultrathin sections of Glu-AuNP treated HeLa cells confirmed the internalization of Glu-AuNPs. Control HeLa cells and Glu-AuNp treated HeLa cells were irradiated at different doses of 62 MeV 12C ion beam (LET - 290keV/{mu}m) at BIO beam line of using 15UD Pelletron accelerator at Inter University Accelerator Centre, New Delhi, India. The survival fraction was assessed by colony forming assay which revealed that the dose of carbon ion for 90% cell killing in Glu-AuNP treated HeLa cells and control HeLa cells are 2.3 and 3.2 Gy respectively. This observation shows {approx} 28% reduction of {sup 12}C{sup 6+} ion dose for Glu-AuNP treated HeLa cells as compared to control HeLa cells.

Kaur, Harminder; Avasthi, D. K.; Pujari, Geetanjali; Sarma, Asitikantha [Inter University Accelerator Centre, Aruna Asaf Ali Marg, Post box-10502, New Delhi-110067 (India)

2013-07-18

390

56Fe ion irradiation enhances angiogenesis and other inter-cellular determinants of carcinogenesis risk  

PubMed Central

In the assessment of radiogenic cancer risk from space flight, it is imperative to consider effects not only on the creation of cancer cells (initiation) but also on cell–cell interactions that play an important and often decisive role in the promotion and progression phases. Autopsy results confirm that most adults carry fully malignant tumors that are held in check at a small size and will never become symptomatic [ 1, 2]. This introduces the possibility that cosmic radiation may significantly influence cancer risk through alteration of the bottleneck inter-tissue interactions responsible for maintaining this dormant state. One such bottleneck is the growth limitation imposed by the failure of the tumor to induce blood vessels (angiogenesis). Other deciding events are the ability of a tumor to proliferate and invade. We have previously shown that proton radiation, the most prevalent radiation in space, has a suppressive effect on all three of these functional responses. It down-regulates angiogenic genes like VEGF and HIF-1? and impairs cell invasion and tumor growth [ 3]. We decided to test these responses after 56Fe irradiation, an HZE radiation type present in the cosmic environment with presumably high carcinogenic potential [ 4]. Human microvascular endothelial cells (HMVEC) and normal human dermal fibroblast (NHDF) cells were irradiated with different doses of 56Fe ion radiation (1 GeV/n) at Brookhaven National Laboratory and RNA was extracted 6 h later. Genomic-wide array analysis was done on the isolated RNA through the Agilent Platform. It was observed that several pro-angiogenic genes like VEGF, IL-6 and HIF-1? were significantly up-regulated after treatment with 56Fe ion radiation (Fig.  1). These results were also confirmed at the mRNA and protein levels with the human and murine lung cancer lines, A549 and LLC, respectively. Additional verification of modulation of these key genes was also observed when lungs of C57BL/6 mice treated with 56Fe ion radiation showed an increase in VEGF and MMP9 mRNA and protein expression 6 h post-irradiation (Fig.  2). Cell invasion was shown to be increased by 56Fe ion radiation in various cell types, including fibroblast, tumor and endothelial progenitor cells. 56Fe ion irradiation also modulated functional processes crucial to angiogenesis. It enhanced the ability of untargeted (bystander) endothelial cells to invade and proliferate in response to factors produced by targeted fibroblast or cancer cells in vitro. Results also carry over to in vivo. C57BL/6 mice exposed to whole-body irradiation with 0.2 Gy dose of 56Fe and injected subcutaneously with LLC tumor cells showed a significant augmentation in tumor growth and growth rate in the irradiated group. Additionally, nude mice exposed to whole-body 56Fe radiation and injected intravenously with A549 cancer cells 3 h post-irradiation demonstrated a significant enhancement in lung colonization capacity when compared with the sham-irradiated control mice injected. These results together suggest cell and tissue-level responses to 56Fe irradiation may act to overcome major cancer progression-level bottlenecks including those related to angiogenesis, cell proliferation and invasion. This is of significant concern for cancer risk estimations pertinent to NASA as achieving these cancer hallmark processes can make the difference between a radiation-induced cancer cell progressing to a clinically detectable cancer in astronauts or not. In conclusion, we demonstrate a strong radiation quality dependence for space radiation carcinogenesis risk manifested through influences on intercellular interactions in the progression phase of carcinogenesis. Fig. 1.Heatmaps of selected differentially regulated major angiogenesis genes after proton and 56Fe ion radiation in HMVECs and NHDF. Cells were treated with either 0, 0.5, 1 or 2 Gy of proton radiation or 0, 0.2, 0.4 or 1 Gy of 56Fe ion dose. Among the major regulated genes were VEGF, HIF-1A and IL-6; they were down-regulated

Girdhani, Swati; Lamont, Clare; Peluso, Michael; Sun, Maoyun; Hlatky, Lynn

2014-01-01

391

Impurities Si interstitials interaction in Si doped with B or Ga during ion irradiation  

NASA Astrophysics Data System (ADS)

Substitutional impurities (B, Ga) in Si experienced an off-lattice displacement during ion-irradiation using a H+ or He+ beam at room temperature in random incidence. Samples were prepared by solid phase epitaxy (SPE) of pre-amorphized Si subsequently implanted with B and Ga at a concentration of about 1 × 1020 at. cm-3 confined in a 300 nm thick surface region. The lattice location of impurities was performed by a channelling technique along different axes (\\langle 100\\rangle , \\langle 110\\rangle ) using the 11B(p,?)8Be reaction and standard RBS for B and Ga, respectively. The normalized channelling yield ? of the impurity signal increases with the ion fluence, indicating a progressive off-lattice displacement of the dopant during irradiation in random incidence, until it saturates at ?F<1, suggesting a non-random displacement of the dopant. In particular, at saturation the off-lattice displacement of B and Ga was investigated by angular scanning, revealing different positions for each dopant. This effect has been related to the interaction of impurities with the Si self-interstitials (SiI) generated by the impinging beam in the doped region.

Romano, L.; Piro, A. M.; Grimaldi, M. G.; Rimini, E.

2005-06-01