Find best premium and free Magento themes at Design4Magento.com

Posters

POSTER SESSION III: 26-07-2012 (16h15-18h00)
[Poster session I] [Poster session II]

LCD-A: Materials Sciences & Microelectronics

1.(#64) Ion beam analysis of gas turbine blades: Evaluation of refurbishment quality
Omidreza Kakuee
Hot components of gas turbines exposed in highly aggressive environments are always prone to damages for a number of reasons such as particle erosion, different types of corrosion and oxidation, and increasing effects due to the combination of these damage modes [1]. Applying a protective coating layer and also refurbishment of these components has always been of considerable importance from technical and economic points of view. To protect hot components of gas turbines, MCrAlY (M=Co, Ni) alloy is conventionally used as a protective coating layer against oxidation. In this research work, the outer surface layers of a corroded gas turbine blade used in power generation industry as well as a refurbished blade by applying a coating of MCrAlY were investigated using conventional PIXE and RBS performed in a home-made reaction chamber [2]. Moreover, four other samples of turbine blades already cut, mounted and polished were investigated using a nuclear proton microprobe. In this investigation, the influence of type and distribution of elements used in protective coatings on the quality of coatings were studied. Impurity elements present in the coatings which could have a significant effect on the quality of coating layers and on the life time of turbine gas blades were identified and characterized as the undesired factors. The results of micro-PIXE analysis also reveal the distribution of large amounts of clustered Si in the protective coating. This unwanted distribution of Si which could considerably reduce the life time of protective layer seems to originate from the sandblast process during the pre-treatment of the blades. As a general conclusion, removing the uppermost surface layer carrying light elements and also pre-coating surface treatments were found to have great importance in the development of proper protective layer.

[1] M. J. Pomeroy, Materials & Design 26 (2005) 223-231.
[2]O.R. Kakuee, V. Fathollahi, D. Agha-Aligol, M. Farmahini-Farahani, P. Oliaiy, M. Lamehi-Rachti, Nucl. Inst. and Meth. B 266 (2008) 1132-1136.
2.(#159) Spatially-resolved analysis of natural minerals as carriers of high-tech metals and
Rare Earth Elements: comparison of EPMA, PIXE and Sy-μXRF
Frans Munnik
The assessment of supply risk of high technology elements requires quality assurance of their natural carriers such as ores at low levels and micrometer scales. One path to achieve this goal is through the use of reference materials (RMs). Providing reliable data on elemental concentrations at the μg/g level and on their spatial distribution is achieved by employing spatially-resolved micro-analytical methods. In order to produce synthetic RMs with optimized chemical composition, three natural mineral analogues (sanidine, pyrite, columbite) have been tested for chemical homogeneity with three methods based on X-ray detection: EPMA (Electron Probe Micro Analyzer), Sy-μXRF (Synchrotron radiation-induced X-ray Fluorescence) and PIXE. EPMA analyses were carried out at the TU Bergakademie Freiberg using a wavelength dispersive detector and an accelerating voltage of 20 keV and a beam size of 2 µm. Sy-μXRF measurements were performed at the hard X-ray beamline “BAMline” at the synchrotron facility BESSY in Berlin. Samples were exposed in atmosphere to monochromatic X-rays of 20 keV focused with a compound refractive lens to 3x3 μm2. PIXE data were obtained using a 3 MeV proton beam of about 5x5 µm2 from a 3 MV tandem accelerator at the HZDR, Dresden. Quantitative (EPMA, PIXE) and qualitative (Sy-μXRF) elemental distribution maps have been obtained for major, minor and trace elements for each scan. At least five trace elements were detected in each of the matrices, showing irregular distribution patterns. Compared to PIXE, Sy-μXRF spectra were characterized by lower peak to background ratios, thus, better detection limits could be achieved and more trace elements identified, such as Ge and Pb in sanidine, Hf and Yb in columbite, and Zn and Se in pyrite. The use of several analytical techniques is necessary for the quality assurance of synthetic candidate RMs since it provides complementary information, e.g. Sy-μXRF is very sensitive, detecting more trace elements, EPMA provides more results for light elements since it operates under vacuum and PIXE is sensitive for medium heavy elements.


5.(#172) Ion Microscopy of Hydrogen retention in heavy metals
Katrin Peeper
Degradation of wall materials used in fission and fusion reactors due to extreme conditions and radiation is investigated in order to develop improved materials. Hydrogen plays a key role in metal embrittlement and is trapped at various natural and ion induced defects. We present detailed study of the hydrogen retention in heavy metals in 3 dimensions and its correlation with structural features e.g. grain boundaries and blisters performed by proton-proton-scattering at the proton microprobe SNAKE. For low Z sample material like diamond, sensitivity of 5x1013 at/cm2 is possible, resolving hydrogen enhancement even on grain boundaries of diamond [1]. High Z material is much more complex to analyse due to strong background from accidental coincidences induced by nuclear reactions and due to larger small angle scattering effects and large matrix atoms scattering cross section. We show that we obtain a sensitivity better than ~1015 at/cm2 (~2at-ppm) is possible even for steel or tungsten. At SNAKE with high proton energies up to 25 MeV we are able to analyse even up to 50 μm thick tungsten targets. We utilised 22 MeV protons to study hydrogen distributions in 50 μm Stainless Steel and 25 μm Tungsten samples. The steel samples have been implanted with 2 MeV protons at a fluence of around 7x1019 H+/cm2. The depth profiles show that less than 0.3% of the implanted hydrogen is retained and is localized mostly in the end of range peak. The same depth resolution and a detection limit of 1016 at/cm2 were obtained for tungsten implanted with a 1.8 MeV proton beam. Other Tungsten samples have been implanted at the high current ion source at IPP Garching using a H3+ ion beam with the energy of 200 eV/H at a fluence of 2x1020H+/cm2. At these conditions, which mimic the conditions in future fusion reactors, blisters and cracks are created in the near-surface layer due to hydrogen-induced stress in the material. With pp-scattering at SNAKE we are able to image the damaged area and quantify the retained hydrogen.

[1] P. Reichart, et al. Science 306 (2004) 1537.

8.(#184) Corteo Simulations for Quantitative Hydrogen Analysis using Proton-Proton Scattering
Marcus Moser
Proton-proton (pp) scattering has proven to be the most sensitive ion beam method for hydrogen analysis [1]. For microscopic hydrogen imaging in 3 dimensions it is in fact the only method because of its low radiation damage potential [2]. The high sensitivity is achieved by coincident detection of both protons from a pp-scattering event using an angular resolving strip detector, where the 90° scattering angle of both protons to each other is well defined due to equal masses of the scattered particles. Multiple (small angle) scattering effects cause a deviation of the 90° angular condition for long path length of the scattered protons through the sample, in particular for high Z materials. Hence, the detection efficiency for hydrogen coincidence events is a function of depth. We use the CORTEO [3] Monte Carlo code in order to calculate the dependence of this depth dependent detection efficiency that also depends on the atomic number Z, the tolerance of the angular filter condition and other geometric effects like misalignment of the detector position. Calculations are compared to experimental performed on multilayered sandwich targets using a simple 2-fold detector setup as well as the current multistrip setup at SNAKE (see Fig. 1). The CORTEO Monte Carlo Code has been adapted to coincident pp-scattering analysis in order to simulate the depth dependent detection efficiency that also depends on the atomic number Z of the target material, the tolerance of the angular filter conditions and the geometrical effects like misalignment of the detector position.

[1] P. Reichart, et al., Science 306 (2004) 1537.
[2] P. Reichart, et al., Nucl. Instr. and Meth. B197 (2002), pp. 134-149.
[3] F. Schiettekatte, Nucl. Instr. and Meth. B266 (2008), pp. 1880–1885.
9.(#160) Charge collection study in the interstrip region of DSSSD using proton microbeam
Laura Grassi
According to the experience in nuclear physics experiments, the efficiency of Double Sided Silicon Strip Detector (DSSSD) may be affected by anomalous charge collection effects for ions entering detector in the interstrip region. This can take place due to the inhomogeneous electric field in the region, lost charge in dead layers and due to different ionization profiles that detected ions may have. When a charged particle hits the interstrip region effects such as charge sharing, pulse height deficits as well as inverse polarity pulses on adjacent strips can occur [1, 2, 3]. In order to clarify this behaviour, an experiment was performed at the scanning proton microbeam of the Ruer Boškovi Institute (RBI). Low proton microbeam currents (~fA) were use to probe behaviour of two DSSSDs (thickness 72 μm and 1000 μm). The response of these two detectors was studied as a function of the position, at different beam energies (0.8, 1.7, 3, 6 MeV) and bias voltages. Results show that the effective region area, where insufficient charge collection occurred, is not constant with respect to the ion penetration depths. Moreover the behaviour of the charge collection in this region is depending in a complex way to the amplitude of the inverse polarity pulses. Different mechanisms of this behaviour as well as implications for the DSSSD use in nuclear physics experiments are discussed.

[1] J. Yorkston and A.C Shotter, Nuclear Instrument and Method A 262 (1987) 353.
[2] Y. Blumenfeld et al., Nuclear Instrument and Method A421 (1999) 471.
[3] Eremin et al., Nuclear Instrument and Method A 500 (2003) 121.

LCD-B: Earth & Environmental Sciences

1.(#72) A study of calcium varieties of uraninite and uranyl minerals by EPMA and micro-PIXE techniques to develop nuclear forensic signatures
Aleksandr Ponomarev
This work is a comparative study of the composition of select uranium minerals from a selection of uranium ores by EPMA and by μ-PIXE techniques. Investigations were performed on Ca-uraninite and Ca-bearing uraninite, Ca-boltwoodite (Ukrainian deposits), uranophane and β-uranophane (Um-Ara, Egypt [1]), and weeksite (Hanneshin, Afganistan [2]). The mineral grains present in the raw ores are known to display micro-scale phase heterogeneities. Quantification of the sources of these heterogeneities and host-relationships is difficult, particularly with respect to trace element impurities. The μ-PIXE technique was used to examine the uranium mineral grains by scanning them with a focused 1.7 MeV proton beam (2-3 μm resolution) extracted from the IAP NASU Nuclear Scanning Microprobe (Sumy, Ukraine). The measured PIXE spectra were processed with a GUPIXWIN program to quantify the elemental composition, and to generate maps of elemental profiles within minerals. EPMA analysis applied conventional techniques using a Camscan-S4 (Oxford) microscope equipped with energy-dispersion and wave-dispersion detectors, and was used to support and validate μ-PIXE results. The major element contents determined by μ-PIXE were found to agree with EPMA data. μ-PIXE was then used for the first time to detect and quantify trace elements within the same mineral grains. Characteristic impurities measured by μ-PIXE in weeksite include (in ppm): Cl 1800±450; Fe 1900±450; Cu 540±120; Pd 6500±700; Pt 1000±300; Bi 850±100. The high concentrations of Pd and Pt may be a result of sorption in concrete deposits. Characteristic impurities measured by PIXE in uranophane and β-uranophane include (in ppm): P 2500±450; Fe 2500±450; Pb 19000±5000. In minerals from Ukrainian ores, measured impurities include (ppm): Ca-bearing uraninite: V 4500±450; Fe 1550±150; Pb 9500±500. The high Pb content is consistent with the age of the ore reflecting radioactive equilibrium. Indirectly, this may also be a signature of geolocation. In the mineral uraninite-(Ca), the element V 3500 ± 500 was determined, but Pb was not detected. This may reflect radioactive disequilibrium in the ores, and/or a very young geological age of ore formation. These results are useful in understanding the sources and processes contributing to the formation of these ores, as well as whether characteristics of these rare and localized uranium ore minerals can be used for unambiguous identification of more refined ore products. The authors thank G.K.E. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

[1] A.A. Valter et al., Mineralogical Study of Um-Ara Uranium Ore Occurrence (Egypt) Scientific report, Sumy, Kiev, 2003.
[2] G.K. Erjomenko, Report on VIII Meeting of Ukrainian Mineralogical Society, Kiev 6.09.2011.
[3] Valter, A.A., K.B. Knight, “New characterization of uranium mineralogy in Ukrainian ores”, 21st VM Goldschmidt Conference, LLNL-ABS-48076, 2011.

3.(#140) Quantitative hydrogen analysis in minerals based on a semi-empirical approach
Per Kristiansson
Hydrogen normally occurs as hydroxyl ions related to defects at specific crystallographic sites in the structures, and is normally characterised by infrared spectroscopy (FTIR). For quantification purposes the FTIR technique has proven to be less precise since calibrations against independent methods are needed. Hydrogen analysis by the NMP technique can solve many of the problems, due to the low detection limit, high lateral resolution, insignificant matrix effects and possibility to discriminate surface-adsorbed water. The technique has been shown to work both on thin samples and on thicker geological samples [1-3]. In this work we will present an upgraded version of the technique using two sets of mineral standards combined with pre-sample charge normalization to achieve quantitative analysis. The first part of this work was presented as a poster on the ICNMTA conference 2010 [4]. To avoid disturbance from surface contamination the hydrogen is analysed inside semi-thick geological samples. The technique used is an elastic recoil technique where both the incident scattered projectile (proton) and the recoil hydrogen is detected in coincidence with a double sided silicon strip detector (DSSSD) [5].

[1] M. Wegdén, P. Kristiansson, Z. Pastuovic, H. Skogby, V. Auzelyte, M. Elfman, K. Malmqvist, C. Nilsson, J. Pallon, A. Shariff, Nucl.Ins.Meth.B219-220 (2004) 550-554.
[2] M. Wegdén, P. Kristiansson, H. Skogby, V. Auzelyte, M. Elfman, K.G. Malmqvist, C. Nilsson, J. Pallon and A. Shariff, Nucl. Instr. Meth. B231 (2005) 524-529.
[3] K. A. Sjöland, P. Kristiansson, M. Elfman, K.G. Malmqvist, J. Pallon, R.J. Utui and C. Yang, Nucl.Ins.Meth.B124(1997)639.
[4] P. Kristiansson, H. Skogby, N. Arteaga-Marrero, M.Borysiuk, M. Elfman, E.J.C. Nilsson, C. Nilsson, J. Pallon and Naseem Salim, Poster presented at ICNMTA 2010 in Leipzig, Germany.
[5] M. Borysiuk et.al. To be presented at ICNMTA 2012.
5.(#219) A mineralogical application of micro-PIXE technique: the Ni-Mo-PGE polymetallic layer of black shales in Zunyi region, South China
Hao Shen
The past decade saw a rapid growth in mineralogical applications of the nuclear microprobe, particularly as an in-situ trace-analyser using the PIXE technique. The success of micro-PIXE stems directly from the sensitivity for trace element detection at the parts-per-million concentration level and microns space resolution [1]. Selected samples of polymetallic layers from Southern China (Huangjiawan mine, Zunyi region, northern part of the Guizhou Province) were analyzed [2]. They are known to be enriched with acidic elements and basic elements. Some of them, like Ag. Au, Pt. Pd. Se and Mo, are of big economic value. We examined the distributions of Pd as well as Fe, Mo, Ni, As and Se in black shale samples with 3 MeV focused proton beam. It can be found that the peak of Pd can be visible clearly in the PIXE energy spectrum, which helps the investigation of the noble metal in the mineralogical samples. Trace element data from minerals, the noble metals' residence status and relationship with major elements, are all useful in studies of the genesis of the deposit, which can aid the exploration strategy [3].

[1] S.H.Sie, Nucl. Instr. and Meth. B 130 (1997) 592-607.
[2] A. Borghi, R. Cossio, C. Mazzoli, Nucl. Instr. and Meth. B 189 (2002) 412-417.
[3] W. Przybylowicz, A. Piestrzynski, K. Traxel, and S. Bajt, Nucl. Instr. and Meth. B 49 (1990) 509-513.

7.(#233) Hydrogen microscopy on natural and synthetic minerals
Patrick Reichart
Minerals from the earth crust and mantle contain hydrogen in form of hydroxyl or water. For certain types of minerals or in dependence of their origin an exact quantification is still not possible, leaving some theories about tectonic movement or earth history unconfirmed. Standard analysis methods like IR absorption or SIMS suffer from the problem that quantification is dependent from the matrix structure and composition of the sample. Natural mineral samples are a composite of microscopically fragmented granular mixture of different mineral types (see Fig. 1). HPHT synthesis is used to generate minerals in the lab in order to simulate temperature and pressure conditions of the Earth's deep interior. The output samples often are – as rare natural samples - tiny synthetic crystals (Fig. 2) that need microscopic imaging tools, like the natural samples do. Ion beam analysis methods are quantitative, but only coincident proton-proton-scattering analysis has the potential to image hydrogen with ppm-sensitivity in microscopic dimensions. At the microprobe SNAKE high proton energies up to 25 MeV are available so that samples up to 100-200 μm thickness, that is often the limit to prepare, can be analyzed in the required transmission geometry. We present microscopy maps of hydrogen distributions and quantitative analysis in both natural and synthetic mineral samples. Natural surface contaminations of 1016...1017 H-atoms/cm2 can be separated hence giving the true inner bulk content. Additionally, the signal from backscattering protons (non-Rutherford elastic scattering) can be used to correlate the hydrogen events to the location of other elements.

9.(#190) Micro-ionoluminescence and micro-PIXE in natural diopside: activators and ion damaging effects
Alessandro Lo Giudice
Diopside is a mineral belonging to the pyroxene family, in particular it is an inosilicate with single chains whose chemical formula is CaMgSi2O6. Natural diopside displays a large variety of luminescence centres: at room temperature main features are a 450 nm band, that can be ascribed to the silicate-based network [1-3] and an intense band at 585 nm that can be ascribed to Mn2+ ions in M2 (Ca2+) sites [4]. Also Ti3+ and Fe-related impurities have a role as activators of luminescence [5,6]. The main purpose of the present work is to study the radiation hardness of several of such centres by following the evolution of ionoluminescence upon proton and helium irradiation at different energies and fluences. Moreover an attempt was made to correlate the trace elements to the centres of luminescence by means of micro-PIXE. As this work falls in the framework of the provenance study of lapis lazuli used for artworks we are carrying on since 2008 [7], all analysed natural diopside crystals were found in lapis lazuli rocks.

[1] L.H. Abu-Hassan L., P.D. Townsend, Nucl. Instr. Meth. B, 32 (1988) 293-298.
[2] K. Moritani, I. Takagi, H. Moriyama, Journal of Nuclear Materials, 312 (2003) 97-102.
[3] S.I. Kitazawa, S. Yamamoto, M. Asano, S. Ishiyama, Physica B, 349 (2004) 159-165.
[4] A.L. Smith, Journal of The Electrochemical Society, 96(5) (1949) 287-296.
[5] A. Quaranta A. et al., Nucl. Instr. Meth. B, 254 (2007) 289-294.
[6] C.D.K. Herd, R.C. Peterson, G.R. Rossman, The Canadian Mineralogist, 38 (2000) 1193-1199.
[7] A. Lo Giudice et al., Analytical and Bioanalytical Chemistry, 395 (2009) 2211-2217.

LCD-C: Microprobe Technology + Biology & Biomedicine

1.(#196) Elemental characterization of cunshot residues generated by brazilian manufactured ammunition
Anaí Duarte
The finding of GSR (waste shooting of a firearm) in the hands or clothing of a suspect is of high interest for police authorities [1]. These residues identified by the presence of Pb, Ba and Sb in a single particle of generally spherical geometry are condensation products of material from the primer, projectile, cartridge case and the gun barrel. Therefore, its composition varies according to the gun and the ammunition used [2]. The most accepted technique for the detection of GSR in Brazil nowadays is the Scanning Electron Microscope Energy Dispersive X-Ray Spectrometry (SEM-EDS) since it is a non-destructive technique and capable of specifying whether the characteristics elements (Pb, Ba and Sb) are in the same particle, ensuring that it is really GSR and not from contamination from another source [1,2]. However, in most cases is not possible to discriminate waste from different sources using SEM, because this technique is not sufficiently sensitive to trace elements [2]. The objective of this study is to establish the elemental characterization of GSR generated by ammunition made in Brazil, and determine the level of dependence of its composition with the firearm used. To that end, PIXE and micro-PIXE were carried out. GSR samples from the firing of a gun Taurus (38 special), with cartridges CBC (38 SPL+P+), were collected on paper directly into the output barrel. The measurements were performed at The Ion Implantation Laboratory of the Physics Institute (UFRGS). The samples were irradiated with an average current of 6.1 pA for 600 seconds with beam 4x4 mm. Preliminary results show a correlation between Pb and Ba in the same particle. However, the presence of Sb was not detected.

[1] M.J. Bailey and C. Jeynes, Nuclear Instruments and Methods in Physics Research B, 267, (2009), 2265-2268.
[2] M.J. Bailey, K.J. Kirkby and C. Jeynes, X-Ray Spectrometry, 38, (2009), 190-194.
3.(#217) Electronic behavior of polymer foils irradiated with nuclear microprobe
Cláudia Telles de Souza
The presence of intrinsic ionic impurities in commercial polymer foils makes them electroactive by changing their electronic properties from simply insulating to a frequencydependent behavior (from capacitive to memristive as the frequency increases). The polymers can uptake additional ions when being submerged in an electrolyte. Usually, this uptake is limited due to the protective action of the polymeric surface, that behaves like a diffusion barrier for external penetrants. When irradiated by a microbeam, the electrolyte uptake capability of the foils is however perturbed due to radiation damage and morphological changes (i.e. holes) introduced by the beam. In this work, the electronic behavior of polymers structured by a 3 MeV H+ microbeam was investigated. Commercial poly(ethylene terephthalate) foils were irradiated with a 2.5 x 2.5 μm2 proton beam of 3.0 MeV and subjected to chemical etching to create a single rectangular hole of ~1000 μm2 in the foils. The microstructured polymers were immersed in a salt electrolyte and excited by an AC function generator to measure their current response in a frequency range of 1mHz to 1MHz. We show that ion microbeam irradiation facilitates the in-diffusion of excess ions from the surrounding electrolyte, increasing the polymer's electrolyte uptake capability by a large amount. A hole as small as 10-6 cm2 on a 0.28 cm2 PET foil (~0.004% of the foil surface) is sufficient to change the electronic properties of the whole foil remarkably in the entire frequency range investigated. We also compared such results with those of polymer foils irradiated by swift heavy ions.
4.(#239) PIXE, RBS and SEM analysis to quantify the effect of Zr on Ti-alloy wires to be used as orthodontic material
Khaled Abdela Mahdi Ali
Recent developments in material science have presented newer archwire materials as well as improvements in the properties of existing ones. Proper selection and understanding of the biomechanical requirement of each case requires proper characterization studies on archwire alloys [1]. Use of orthodontic archwires has some disadvantages such as high surface roughness, which increases friction at the wire-brace interface during the wire sliding process [2]. The surface quality and the surface roughness of dental materials are of utmost importance; these properties determine the area of the contact surface and thus influence on the friction [3]. Two orthodontic archwires preformed rectangular beta titanium III orthodontic archwires (0.43 × 0.64 mm) and Timolium orthodontic archwires (0.040 × 0.64 mm). In addition, pure zirconium was deposited over the archwires. Several thin films of Zr were deposited over titanium orthodontic archwires. Determination of composition and surface roughness of orthodontic wires were performed with Particle-induced X-ray emission (PIXE) [4] and Backscattering Spectrometry (BS). SEM analysis was performed to determine the major element composition. In this study the effects of the various thicknesses of the Zr layers deposited onto the Ti-alloy mires to improve the surface roughness of the archwire are investigated. Also reported is the strength of archwires before and after deposition with zirconium and immersion with artificial saliva.

[1] Krishnan et. al. (2004) Angle Orthodontist, vol. 74 (6). pp. 825-31.
[2] Kappert et. al. (1988). Fortschritte der Kieferorthopadie, vol. 49 (4), pp. 358-367.
[3] Tecco et. al. (2009). The Angle Orthodontist, vol. 79 (1), pp. 111-116.
[4] Ryan et. al. (1995) NIMB, vol. 104, pp. 157-165.

5.(#244) Construction of a time-of-flight telescope for MeV SIMS at Jožef Stefan Institute
Luka Jeromel
Elemental mapping in biological tissue with micro-PIXE is intensively ongoing at Ljubljana nuclear microprobe for external users from biomedical research. For better understanding of biochemical processes in the tissue, additional information on chemical bonding or molecular distribution in the tissue is required. Such information can be obtained with MeV SIMS method. This motivated a construction of a linear Time-Of-Flight telescope at JSI. MeV focused ion beam will be used to desorb molecular fragments from the sample. The process of desorption is equal as in the Plasma Desorption Mass Spectrometry (PDMS), which is known as a technique capable of desorbing large intact molecular ions from the surface of organic materials by electronic sputtering mechanism [1]. It has been shown by Nakata et al. [2] that electronic sputtering induced by MeV heavy ions offers higher yields of the high mass molecules in comparison with ordinary SIMS. These high mass molecules are of the main interest in biological research. Using microprobe scanning in combination with the pulsed beam, we will be able to obtain a 2-dimensional distributions of molecules with resolution limited by the diameter of the focused ion beam. TOF spectrometer consists of a 1 meter long drift tube and a micro channel plate (MCP) to provide a stop signal. Positively charged molecular fragments are accelerated towards the MCP detector by a positive voltage applied to the sample.

[1] R.D. Macfarlane, D.F. Torgerson, Science 191 (1976) 920–925.
[2] Y. Nakata, Y. Honda, S. Ninomiya, T. Seki, T. Aoki, J. Matsuo, Applied Surface Science 255 (2008), 1591-1594.
6.(#225) An electrostatic quadrupole lens for focusing swift heavy ions in MeV-SIMS
Toshio Seki
The technique called secondary ion mass spectrometry (SIMS) is based―as the name implies―on mass spectrometry. In conventional SIMS with keV-energy ion beams, elastic collisions occur between projectiles and constituent atoms in molecules. The reaction breaks the molecules and produces fragments, and this acquisition of molecular information is difficult. In contrast, MeV-energy ion beams excite electrons and enhance the ionization of high-mass molecules, and a SIMS spectrum of ionized molecules can be obtained. Imaging of molecular species over 500 Da was successful in SIMS using MeV ions [1]. However, obtaining molecular imaging data at present, takes a long time, because the current density of the primary beam is not high enough. We have developed an electrostatic quadrupole lens to focus the swift heavy ion beam and reduce measurement time. Fig.1 is a schematic representation of a double quadrupole lens (Q lens). To characterize the properties of this lens, we tested it with a 6 MeV Cu ion beam with an initial beam diameter of 0.5 mm. We applied 1120 V to the Q1 lens and 1430 V to the Q2 lens, and the current density increased by a factor of ~70. Using this arrangement, we obtained an MeV-SIMS image of 100 x 100 pixels of protonated distearoyl phosphatidylcholine (DSPC) (m/z = 790.6) over a 4 mm x 4 mm field of view with a pixel size of 40 μm within 5 min, showing that the Q lens reduces measurement time of current imaging by a factor of ~30.

[1] Y. Nakata, et al. J. Mass Spectrom. (2009) 44, 128-136.
7.(#234) Quantification of micro-PIXE by Si(Li) X-ray detector for the elements with characteristic K X-ray energies below the silicon absorption edge
Primož Vavpetic
The objective of the presented work is to determine the efficiency of Si(Li) X-ray detector for the x-ray energies under the silicon K absorption edge in order to allow quantified micro-PIXE mapping in biological tissue for the elements with characteristic K X-ray energies below the silicon absorption edge at 1.84 keV. At this energy, increased absorption and incomplete charge collection in the detector uppermost layer of the Si crystal next to the front ohmic contact results in descrete jump in the detection efficiency. In addition, the efficiency function drops fast below 2 keV due to absorption in the detector window and ohmic contact, which makes the accurate efficiency description even more demanding. Measurements were conducted on various monoelemental and multielemental samples with known thickness and composition. Proton dose delivered to the sample was controlled by a chopping device [1]. Measured spectra were analyzed by deconvolution programs GUPIXWIN [2] and GEOPIXE [3]. We tried to describe the detector with a physical model, that would describe well the efficiency in both deconvolution programs, that are used for micro-PIXE quantification at Jožef Stefan Institute in biological tissue mapping [4]. The resulting physical model for Si(Li) detector is the same for both programs and gives matching quantification results for the reference samples analyzed, regardless of their thickness and composition, within maximum statistical error of 5% throughout the energy range of interest (0.7 to 13 keV).

[1] K. Vogel-Mikuš, P. Pelicon, P. Vavpetič, I. Kreft, M. Regvar, Elemental analysis of edible grains by micro-PIXE: Common buckwheat case study, Nucl. Instr. Meth. B 267 (2009), 2884–2889.
[2] J. L. Campbell, N I. Boyd, N. Grassi, P. Bonnick, J. A. Maxwell, The Guelph PIXE software package IV. Nucl. Instrum. Meth. B268 (2010) 3356-3363.
[3] C.G. Ryan, "Quantitative Trace Element Imaging using PIXE and the Nuclear Microprobe", International Journal of Imaging Systems and Technology (Special issue on Quantitative Imaging) 11, (2000) 219-230.
[4] L. Lyubenova, P. Pongrac, K. Vogel-Mikuš, G. Kukec Mezek, P. Vavpetič, N. Grlj, P. Kump, M. Nečemer, M. Regvar, P. Pelicon and P. Schroeder, Localization and quantification of Pb and nutrients in Typha latifolia by micro-PIXE, Metallomics, 2012, DOI:0.1039/c2mt00179a.

8.(#258) ToF-SIMS molecular imaging of fingerprints using pulsed 4 MeV oxygen ions with the Surrey Ion Beam Centre nuclear microprobe
Brian Jones
The microprobe equipment used for ion beam analysis at the Surrey Ion Beam Centre has been modified to perform time-of-flight secondary ion mass spectrometry (ToF-SIMS) using a focussed beam of 4 MeV oxygen ions. To obtain good mass resolution for the ToF-SIMS measurement the primary ions were pulsed to a width of 30 ns using a modified on-demand beam deflection system. The SIMS spectra acquired were recorded using the OMDAQ software. These measurements, performed in a high-vacuum chamber, are being used to assess the practicality of using high-energy primary ion beams for atmospheric pressure mass spectrometry studies, which is a technique currently under development. Previously we have demonstrated that the time sequence of fingerprints and ink could be determined from mass spectral imaging using MeV-SIMS if the fingerprints are pre-doped with hand cream [1]. More recently, we have developed a protocol to determine the order with un-doped latent prints using conventional keV SIMS [2]. We demonstrate here that this protocol with latent prints can also be used with MeV-SIMS. This opens the way to performing this same analysis in air without having to sample a document or wait long periods of time for the sample to outgas before starting the analysis. We also present analysis of different overlapping ink signals on paper and explore the possibility to image different overlapping fingerprints.

[1] MJ.Bailey, B.N.Jones, S.Hinder, J.Watts, S.Bleay, R.P.Webb, Nucl. Instrum. & Meths. B, 268(11), 1929-1932, (2010).
[2] N.J.Bright, R.P.Webb, S.Bleay, S.Hinder, N.I.Ward, J.F.Watts, K.J.Kirkby, M.J.Bailey, Determination of Deposition Order of Overlapping Latent Fingerprints and Inks Using Secondary Ion Mass Spectrometry (SIMS), Analytical Chemistry (in press 2012).

9.(#83) Approximating the physiological elemental composition of freeze dried, thin mouse brain sections using Geo-PIXE
Rainer Siegele
A critical factor in Particle induced X-ray emission (PIXE) spectroscopy is the sample thickness.1 It is advantageous to use sufficiently thin samples so that energy loss of the particles associated with travelling through the sample is negligible. The selected thickness, density and composition of the sample are required to calculate the theoretical yields during spectral analysis. This is due to self absorption of excited X-rays as they travel out through the sample.2 Density values can be accurately measured by simply measuring the sample mass and volume; however, this can become quite a challenge with thin biological sections which are freeze dried. The end goal of any PIXE analysis will be to determine the elemental composition of the sample, with the best result being relevant to the original state of the sample. For biological samples, this is when the organism from which the sample had been collected from, was still alive. This work investigates the level of error associated with using the physiological density in calculations rather than the density for freeze dried sections. The difference in theoretical yield values which can arise from using a density of 1.05 g/cm3 (fresh brain density), and 0.23 g/cm3 (calculated freeze dried density) was calculated over a range of thicknesses (1-15 μm). The level of error between the two values was found to increase with sample thickness and was higher with the heavier elements; however, several biologically important elements were found to have an error less than 5 percent at a 5 μm thickness. These results indicate that using the biological density may be a valuable tool for estimating the physiological concentration of biological samples without the need to accurately measure the density of each freeze dried sample.

[1] Campbell, J. L. Specimen preparation in PIXE analysis. Nuclear Instruments and Methods 1977, 142, 263-273.
[2] Pallon, J.; Ryan, C. G.; Arteaga Marrero, N.; Elfman, M.; Kristiansson, P.; Nilsson, E. J. C.; Nilsson, C. STIM evaluation in GeoPIXE to complement the quantitative dynamic analysis. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 2009, 267, 2080-2084.


LCD-D: Imaging & Tomography

1.(#112) Surface topography of 1€ coin measured by stereo-PIXE
Ebrahim Gholami Hatam
PIXE and RBS analysis could be used in parallel to investigate the elemental contents of metallic objects, including coins [1]. The reconstruction of the topography of buried interfaces of multilayer sample is demanding task and may be accessed by a combination of RBS, XRD and AFM techniques [2]. A novel approach to deal with interface topography has been recently developed using stereo-PIXE technique [3]. In this work, we demonstrate the ability of stereo-PIXE method by measurement of surface topography of the relief details on one euro coin. Two X-ray elemental maps were simultaneously recorded by two X-ray detectors positioned at the left and the right side of the proton microbeam. The asymmetry of the yields in the pixels of the two X-ray maps arised due to different photon attenuation on the exit travel path of the characteristic X-rays from the point of origin to the detectors. To reconstruct the surface topography of the coin quantitatively, a flat surface model was at first applied for the sample in which the matrix composition and the depth elemental concentration profile was determined by conventional PIXE in combination with RBS measurement. After that, the yield asymmetry in each image pixel was transferred into corresponding local inclination angle using calculated dependence of the asymmetry on the surface inclination. Finally, the quantitative topography profile was revealed by integrating the local inclination angle over the lateral displacement of the probing beam.

[1] C.J. Tavares, L. Reboutaa, E. Alves, N.P. Barradas, J. Pacaud, J.P. Riviere, Nucl. Instr. And Meth. B 188 (2002) 90.
[2] M. Roumie, B. Nsouli, G. Chalhoub, M. Hamdan, Nucl. Instr. Meth. B 268 (2010) 1916. [3] E. Gholami Hatam, P. Pelicon, M. Lamehi-Rachti, P. Vavpetič, O. R. Kakuee, N. Grlj, M. Čekada, V. Fathollahi, Surface topography reconstruction by stereo-PIXE, J. Anal. At. Spectrom., DOI:10.1039/C2JA10373G.
2.(#120) Quantitative IBA microscopy on lateral highly inhomogeneous meteorite samples
Ralf Wunderlich
Extraterrestrial research is dominated by high-tech, like spacecrafts or telescopes and therefore highly cost-intensive. On the other side, meteorites provide a cheap source of information about the creation and development of our and other solar systems. Of particular interest is the concentration of trace elements in the rock building crystals of meteorites. The knowledge of trace the element concentration in certain crystals enables to reconstruct the geological history of minerals, like temperature and pressure conditions during growing and alteration. These crystals can often be found in close proximity to massive iron-nickel grains. A challenge for ion beam analysis methods, like particle induced x-ray emission (PIXE) or Rutherford backscattering spectrometry (RBS), on such inhomogeneous samples is strongly varying dead time of detector electronics leading to incorrect concentration mapping on a local scale. To solve this problem, a noise triggered setup was developed that generates defined pulses, which are fed into the preamplifier of the detector electronics and act as pseudo events in the data processing. A comparison of the number of generated and processed pulses allows the computation of a dead time map for the correction of the collected spectrum on a pixel per pixel basis. The iron distribution of a chondrule of the meteorite sample PL90305 of Acfer 094 shown below illustrates the benefits from a lateral dead time mapping. The corrected false colour map seems to contain less structural information, but in fact now displays the correct concentration values and puts them in proper relation.
3.(#130) 3D analysis of an induced murine atherosclerotic lesion by PIXE stacking
Nirav Barapatre
Particle Induced X-Ray Emission (PIXE) is one of the few methods capable of quantifying multiple elements simultaneously with high sensitivity. Combined with an energetic microbeam, it provides 2D quantitative element distribution maps with sub-micron spatial resolution. It has, thus, manifold applications in biomedical research. However, the specimens to be analysed have to be thin (5-15 μm), in order to avoid deterioration of beam resolution due to straggling over the specimen thickness. A three dimensional volumetric analysis of thicker specimens is possible by PIXE tomography. But, due to high fluences during the tomographic experiments, there is considerable specimen damage. Further, there are certain limitations on the specimen geometry, which makes this method unsuitable for the analysis of many biological samples. A mouse artery is around 800 μm in diameter and an induced atherosclerotic lesion is spread several hundred micrometers across the length of the artery. We present an alternative way of 3D analysis by means of stacking the areal quantitave maps of cross-sections of the lesion. The lesion was induced in a LDL-receptor deficient mouse by feeding it on high cholesterol semi-synthetic diet. At the age of 20 weeks it was sacrificed. The brachiocephalic artery was removed and frozen in mounting medium. At least, 40 adjacent sections of 10 μm thickness each were prepared and analysed with PIXE. The resulting 2D quantitative element maps were stacked and aligned with a purpose-written software to reconstruct a 3D quantitative element visualisation.

[1] T. Reinert, et al., Nucl. Inst. Meth. B249 (2006), 734.
[2] Aldons J. Luis, Nature, 407 (2000), 233.
[3] F. Watt, et al., Nucl. Inst. Meth. B249 (2006), 646.
[4] D. Teupser, et al., Arterioscl. Thromb. Vasc. Biol., 23 (2003), 1913.
4.(#131) Microscopic imaging approach to aerosol particles by using in-air micro-IL analysis combined with micro-PIXE
Wataru Kada
Growing interests are being paid for the behaviour of several kinds of aerosols, known as a long-distance transmission medium of microbes and the viruses in the atmosphere. Researchers had related these kinds of aerosols, called as bio-aerosols, with the infection expansions [1]. The detection techniques were therefore intensively developed for the prevention of the pandemic expansion of infections and revealed that the peculiar fluorescence is released from these organic-inorganic complex particulate targets by the external excitations. However, it was quite difficult to analyze fluorescence from individual particles with conventional fluorescence analysis because of the size of particulate aerosols. The microscopic spectroscopy and imaging system of ion-microbeam-induced luminescence (Ion-Luminescence, IL) is being developed on the beam line of micro-PIXE analysis system of a 3 MV single-ended accelerator at Takasaki TIARA facility, TARRI, JAEA [2], In this study, individual imaging and analysis of specific kind of aerosols targets were performed using this system for the characterization of fluorescence properties of micrometer-sized particulate aerosols. Then the monochromatic IL images were obtained from several aerosol particles with wavelength at a band around 415nm and 430 nm. The IL spectra obtained from aerosol target were also observed to be clearly different from other silicon dioxide particles. Results will be discussed in the presentation

[1] Y. Iwasaka, G.-Y. Shi, M. Yamada, F. Kobayashi, M. Kakikawa, T. Maki, T. Naganuma, B. Chen, Y. Tobo and C. S. Hong, Air Quality Atmosphere and Health 2(2009) 29.
[2] W. Kada, A. Yokoyama, M. Koka, T. Satoh, and T. Kamiya, Int. J. of PIXE 21 (2011) 1.

6.(#175) Fast Simulation of Proton Induced X-Ray Emission Tomography Using CUDA
Daniel Beasley
Simultaneous Proton Induced X-Ray Emission Tomography, Scanning Transmission Ion Microscopy and Rutherford Backscattering Spectroscopy were performed at the Instituto Tecnológico e Nuclear. To combine into a quantitative 3D image, various algorithms have been developed. The most complete is the Discrete Image Space Reconstruction Algorithm developed by Sakelleriou [1]. This iterative algorithm simulates PIXE Tomography and the X-ray attenuation by segmenting the Si(Li) detector and determining the attenuation from each voxel to each segment for each projection and for each characteristic X-ray produced. A demanding challenge is to get sufficient counts while retaining a small beam. Therefore a high geometric efficiency is required. However, as the detector solid angle increases, the calculations required increase substantially. The Common Unified Device Architecture (CUDA) is the NVIDIA GPU architecture to enable easy general purpose programming of GPU's and to enable massively parallel programming. Since DISRA was developed, memory of computers has increased substantially. Therefore some of the techniques to save memory in DISRA are no longer significantly important. To simplify the development of PIXE tomography simulation, a new simulation of 3D PIXE has been written in Java and CUDA to calculate X-ray attenuation using large detector areas The results of a simulation of a phantom are presented, using DISRA, a Java-based simulation using the CPU and using CUDA. The simulation is also applied to a real data. This work is supported by PTDC/FIS/115089/2009.

[1] A. Sakellariou, D.N. Jamieson, G.J.F. Legge. Nucl. Instr. and Meth. B, 181 (2001) 211.
8.(#207) Use of STIM for Morphological Studies of Microstructured Polymer Foils
Elis Stori
Proton Beam Writing is an important technique for fabrication of various devices with applications on different areas such as microfluidics, tissue engineering substrates and microphotonics, among others. The characterization of structures made through this technique is important for improving their overall quality, thus ensuring the best possibilities for the application of interest. Scanning Transmission Ion Microscopy (STIM) is a powerful tool for morphological characterization of such structures due to its sensitivity to local mass density and thickness. Moreover, it is relatively fast and non destructive. In an homogeneous substrate, this technique can contrast the fabricated structures from the non irradiated portion of the sample, thus enabling the determination of the structural dimensions. This work presents the morphological characterization of microstructures produced on commercial polyethylene terephthalate foils by STIM using on-line and off-axis detection and a 1MeV H+ beam. Lines of ~110 x 10 μm were structured on the foils by a combination of proton beam writing and chemical etching in a 6M NaOH solution. The foils were irradiated with 3 MeV protons and subsequently etched for times varying from 5 to 60 min. STIM data was used to determine the influence of fluence and etching time on the size of the microstructures and the thickness of the pristine and processed polymers. Moreover, STIM images clearly revealed a distribution of internal cavities along the structured walls for etching times above 20 min. This is attributed to thermal effects and outgassing during the ion beam writing, which probably create voids that are enlarged by the long exposure to the etching solution.
9.(#249) 3D elemental reconstruction of a micro-particle with confocal PIXE
Nataša Grlj
The confocal PIXE method has proven useful for depth and three-dimensionally resolved analysis of different objects. Initially, the technique was studied at JSI by an improvised confocal system [1,2]. Recently, a dedicated system for confocal measurements was put in operation [3]. The new confocal PIXE set-up at JSI consists of a silicon-drifted detector, specially designed polycapillary lens and a snout-alignment interface, which enables fast and precise confocal alignment. The combination of beam scanning and sample translation opens a possibility of elemental tomography of microparticles. Standard sample mounting for micro-PIXE or EDX is used. Various types of polycapillary lenses were attached to the confocal system in order to determine their physical characteristics. Emphasis was given to the transmission efficiency of the X-ray lenses, as the information on the efficiency enables quantitative confocal PIXE analysis. Three-dimensional elemental reconstruction of a gunshot residue particle, composed mainly of two X-ray visible elements Ti and Zn, was carried out. The 3D reconstruction of microparticle composition consisted of two visible elements from a sequence of X-ray maps recoded at the specific geometry requires a generalisation of the reconstruction algorithm [4].

[1] A-G. Karydas, D. Sokaras, Ch. Zarkadas, N. Grlj, P. Pelicon, M. Žitnik, R. Schütz, W. Malzer, B. Kanngießer, J. Anal. At. Spectrom., 22 (2007) 1260.
[2] M. Žitnik, P. Pelicon, K. Bučar, N. Grlj, A-G. Karydas, D. Sokaras, R. Schütz, B. Kanngießer, X-Ray spectrom., 38 (2009) 526.
[3] N. Grlj, P. Pelicon, M. Žitnik, P. Vavpetič, D. Sokaras, A-G. Karydas, B. Kanngießer, Nucl. Instrum. Methods Phys. Res., Sect. B, 269 (2011) 2237.
[4] M. Žitnik, N. Grlj, P. Vavpetič, P. Pelicon, K. Bučar, D. Sokaras, A.G. Karydas, B. Kanngießer, J. Anal. At. Spectrom. 25 (2010) 28.

 

 

[Poster session I] [Poster session II]