| 1. |
- Whitlow, Harry J, et al.
(författare)
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Measurements of Si ion stopping in amorphous silicon
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 190:1-4, s. 84-88
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Tidskriftsartikel (refereegranskat)abstract
- The stopping of Si-28 ions in polycrystalline Si foils has been measured over the energy range 0.1-3.3 MeV per nucleon. For the low energy interval (0.1-0.5 MeV per nucleon), time of flight-energy elastic recoil detection analysis method was used, whilst for the high energy region (1.2-3.3 MeV per nucleon) the energy loss in the same foil was measured using a Si p-i-n diode with the Si-28 ions directly incident on the foil following acceleration. Below the stopping maximum the results are in good agreement with literature data based on Doppler shift measurements of short nuclear lifetimes but are about 20%, smaller than the SRIM prediction. Above the stopping maximum the data are in agreement with SRIM within the limits of statistical uncertainty.
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| 2. |
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| 3. |
- Timmers, H, et al.
(författare)
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Threshold stoichiometry for beam induced nitrogen depletion of SiN
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 190, s. 428-432
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of the stoichiometry of silicon nitride films as a function of the number of incident ions using heavy ion elastic recoil detection (ERD) show that beam-induced nitrogen depletion depends on the projectile species. the beam energy, and the initial stoichiometry. A threshold stoichiometry exists in the range 1.3 > N/Si greater than or equal to 1, below which the films are stable against nitrogen depletion. Above this threshold, depletion is essentially linear with incident fluence. The depletion rate correlates non-linearly with the electronic energy loss of the projectile ion in the film. Sufficiently long exposure of nitrogen-rich films renders the mechanism, which prevents depletion of nitrogen-poor films, ineffective. Compromising depth-resolution. nitrogen depletion from SiN films during ERD analysis can be reduced significantly by using projectile beams with low atomic numbers. (C) 2002 Published by Elsevier Science B.V.
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| 4. |
- Weijers-Dall, T D M, et al.
(författare)
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Measurements of the stopping forces for heavy ions in Ge, Ag and Au using novel 'polka-dot' detectors
- 2006
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 251:2, s. 352-360
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of the stopping forces for C-14, N-14 and O-16 ions in Ge and Au, for N-14 and F-19 ions in Ag, as well as for F-19 ions in Au have been made, respectively. A novel technique, reported recently, using PIN diodes coated directly with the stopping medium in a polka dot pattern was used. This provided a set of precise, self-consistent measurements on the same stopping medium. Results show small but significant deviations from SRIM stopping predictions and are also compared to a recently-developed empirical stopping force predictor.
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| 5. |
- Whitlow, Harry J., et al.
(författare)
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Dynamic Analysis of major elements in biological tissue validating quantification of trace life elements in MeV ion beam microscopy
- 2024
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier. - 0168-583X .- 1872-9584. ; 554
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Tidskriftsartikel (refereegranskat)abstract
- MeV ion microprobe measurements of the lesser and trace life element concentrations in biological tissues are challenging because of complex spatial inhomogeneities in these types of samples. Measurements on ex vivo tissue sections require determination of the matrix element composition and the tissue section thickness. For these reasons, in this work, we adapted the Dynamic Analysis approach known from literature, to interpret the MeV ion microscopy data to determine concentrations of H, C, O, and N as well as the thickness of different tissue regions in Non Human Primate (NHP) mesenteric lymph node section. The results showed no strong variations of the matrix element contents regardless of section thickness variations in the tissue. The matrix information was used to quantify total-Ca molarities and a significant ∼30 mM Ca concentration hotspot was observed at the edge of sinus structure in the mesenteric lymph node as compared to the 3-4 mM total-Ca levels in the surrounding tissues. Thus, MeV ion microprobe imaging combined with dynamic analysis comprise a novel chemometric approach paving a way for quantitative analysis of similarly complicated animal and plant biological tissue sections.
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| 6. |
- Zhang, Yanwen, et al.
(författare)
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Radiation detector resolution over a continuous energy range
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:9
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Tidskriftsartikel (refereegranskat)abstract
- An ion approach is demonstrated to determine energy resolution in both semiconductor detectors and scintillators over a continuous energy range. For semiconductors, the energy resolution of a silicon detector was measured as a function of helium ion energy, and the values from extrapolation to high energies are in good agreement with the literature data from alpha measurements. For scintillators, benchmark crystals subject to He+ irradiation were investigated, and the agreement of energy resolution between the ion and gamma measurements indicates that the ion approach can be used to predict the energy resolution of the candidate materials in thin-film form or small crystals when large crystals necessary for gamma-ray measurements are unavailable.
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| 7. |
- Banerjee, Sanjana, et al.
(författare)
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Invasive or Biomonitoring Species? Use of Pomacea maculata Operculum as a Tool to Determine Metal Pollutants : a Micro-PIXE Investigation
- 2023
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Ingår i: Water, Air and Soil Pollution. - : Springer Nature. - 0049-6979 .- 1573-2932. ; 234:6
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Tidskriftsartikel (refereegranskat)abstract
- Pomacea maculata is a widely distributed agricultural and environmental pest in Asia. It is also causing ecological damage and threatening human health in the Southeastern United States. However, its limited mobility and fast consumption of aquatic vegetation may make it an excellent biomonitor to evaluate the pollution status of freshwater coastal ecosystems. This work investigated the capability of the operculum of this snail to accumulate toxic metals in a laboratory environment. We measured the elemental composition of the nucleus and edge regions on the varnish layer of the operculum by employing a MeV ion microprobe instrument. Iron, copper, and zinc were present in the operculum at trace levels. Copper was present at elevated levels in the operculum of snails exposed to copper for 2 weeks. Additionally, heterogeneity in the distribution of major and trace elements within the gastropod's operculum was revealed by 2D elemental images obtained using microparticle-induced X-ray emission spectrometry. On average, the nucleus of the operculum showed a higher accumulation of copper than did the edge. These results demonstrate that micro-PIXE can be used to look at the within-tissue distribution of toxic metals in hard tissues like a snail's operculum. We propose that the operculum metal concentrations can be used as a bioindicator capable of providing information on the ecosystem's health and potentially reveal temporal changes in this health.
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| 8. |
- Carlén, Lars, et al.
(författare)
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CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. III. readout system
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 516:2-3, s. 327-347
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Tidskriftsartikel (refereegranskat)abstract
- (CHICSi) Celsius Heavy Ion Collaboration Si detector system is a high granularity, modular detector telescope array for operation around the cluster-jet target/circulating beam intersection of the CELSIUS storage ring at the The. Svedberg Laboratory in Uppsala, Sweden. It is able to provide identity and momentum vector of up to 100 charged particles and fragments from proton-nucleus and nucleus-nucleus collisions at intermediate energies, 50-1000A MeV. All detector telescopes as well as the major part of electronic readout system are placed inside the target chamber in ultra-high vacuum (UHV, 10(-9)-10(-7) Pa). This requires Very Large Scale Integrated (VLSI) microchip for the spectroscopic signal processing and the generation and transport of digital control signals. Eighteen telescopes, read out with chip-on-board technique by ceramics Mother Boards (MB) and corresponding 18 microchips are mounted on a 450 x 45 mm(2) Grand Mother Board (GMB), processed on FR4 glass-fibre material. Each of these 28 GMB units contains a daisy-chain organisation of the VLSI chips and associated protection circuits. Analogue-to-digital conversion of the spectroscopic signals is performed on a board outside the chamber which is connected on one side to a power distribution board, directly attached to a UHV mounting flange, and on the other side to the VME-based data acquisition system (CHICSiDAQ). This in its turn is connected via a fibre-optic link to the general TSL acquisition system (SVEDAQ), and in this way data from auxiliary detector systems, read out in CAMAC mode, can be stored in coincidence with CHICSi data.
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| 9. |
- Ekman, Jörgen, et al.
(författare)
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Retention of Pb isotopes in glass surfaces for retrospective assessment of radon exposure
- 2006
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier. - 0168-583X .- 1872-9584. ; 249:1-2, s. 544-547
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Tidskriftsartikel (refereegranskat)abstract
- In recent years there has been increasing interest in radio-epidemiological techniques to retrospectively measure the radon dose exposure by determining the activity of 210Pb, the longest-lived 222Rn progeny, in glass surface layers. In this study the diffusion of 39 keV 209Pb+ ions implanted into glass using the IGISOL facility has been studied under conditions that mimic the recoil implantation of 210Pb from 222Rn. The resulting depth distributions of 209Pb were then measured after heat treatment in vacuum at different temperatures by a sputter erosion technique. The diffusion coefficient could be described by an Arrhenius equation D = D0exp(−H/kT) where and H = 2.81 ± 0.11 eV. No statistically significant loss of 209Pb from the sample was observed for annealing between 470 and 600 °C.
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| 10. |
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| 11. |
- Golubev, Pavel, et al.
(författare)
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CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. II. Detectors
- 2003
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 500:1-3, s. 96-115
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Tidskriftsartikel (refereegranskat)abstract
- We describe the detectors for identification of charged particles and fragments in CHICSi, a large solid angle multitelescope system mounted inside an ultra-high vacuum (UHV), cluster-jet target chamber. CHICSi performs nuclear reaction experiments at storage rings. The telescopes consist of a first very thin, 10-14 mum Si detector, a second 300 mum (or possibly 500 pm) ion implanted Si detector supplemented by a 6 mm GSO(Ce) scintillator read out by a photodiode (PD) or by a third 300 mum Si detector. The telescopes provide full charge separation up to Z = 17 and mass resolution up to A = 9 in the energy range 0.7-60A MeV. The thin p-i-n diode detector, etched out from a 280 mum Si wafer, and the GSO/PD detector, both exclusively developed for CHICSi, provide an energy resolution less than or equal to 8%, while the standard 300 mum detectors have less than or equal to 2% energy resolution. Radiation stability of the Si detectors is confirmed up to an integrated flux of 10(10) alpha particles. The GSO detector has 70% light collection efficiency with the optical coupling to the PD a simple open, 0.2 mm, gap. A new method, developed to perform absolute energy calibration for the GSO/PD detector is presented. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 12. |
- Gorelick, Sergey, et al.
(författare)
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Growth of osteoblasts on lithographically modified surfaces
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier. - 0168-583X .- 1872-9584. ; 260:1, s. 130-135
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Tidskriftsartikel (refereegranskat)abstract
- Here we report about preliminary investigations on developing substrates for culturing osteoblasts, the cells responsible for production of mineralised bone, by lithographically modifying the surfaces of several materials. The proton beam writing system at the National University of Singapore was used to fabricate high aspect ratio structures in PMMA, while two-dimensional low aspect ratio structures were fabricated using conventional electron beam lithography (EBL) and UV lithography (UVL) in SU-8. It was found that oxygen plasma treatment of structured SU-8 surfaces changed the surface layer and significantly improved cell attachment and proliferation. Cells grown on patterned thick PMMA exhibit a remarkable geometry-dependent behaviour.
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| 13. |
- Hellborg, Ragnar, et al.
(författare)
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Direct Current Accelerators for Industrial Applications
- 2011
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Ingår i: Reviews of Accelerator Science and Technology. - 1793-8058. ; 4:1, s. 183-212
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined Direct current accelerators form the basis of many front-line industrial processes. They have many advantages that have kept them at the forefront of technology for many decades, such as a small and easily managed environmental footprint. In this article, the basic principles of the different subsystems (ion and electron sources, high voltage generation, control, etc.) are overviewed. Some well-known (ion implantation and polymer processing) and lesser-known (electron beam lithography and particle-induced X-ray aerosol mapping) applications are reviewed.
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| 14. |
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| 15. |
- Joensson, C T, et al.
(författare)
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Synthesis and characterization of cobalt silicide films on silicon
- 2006
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Ingår i: Ion Beam Analysis - Proceedings of the Seventeenth International Conference on Ion Beam Analysis (Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms). - : Elsevier BV. - 0168-583X. ; 249, s. 532-535
-
Konferensbidrag (refereegranskat)abstract
- Cobalt silicide has emerged as a leading contact material in silicon technology due to its low resistivity, high stability and small lattice mismatch. In this study, 0.2-0.4 mu m thick Co films were deposited on Si(100) wafers by RF magnetron sputtering at room temperature, and annealed at temperatures from 600 to 900 degrees C in vacuum. As-deposited and annealed samples were characterized by Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Although the Si substrates were sputter cleaned before the deposition, all the samples showed a thin oxide layer at the Si/Co interfaces. Annealing up to 700 degrees C did not alter the composition at the interface except small amount Co diffusion into Si. Annealing at 800 degrees C promotes the evaporation of the oxides from the interface and, as a result, clean CoSi2 films were formed. Although the interface appeared to be sharp within the RBS resolution after high temperature annealing, the surface topography was relatively rough with varying size of crystal grains. (c) 2006 Elsevier B.V. All rights reserved.
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| 16. |
- Laitinen, Mikko, et al.
(författare)
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Mobility determination of lead isotopes in glass for retrospective radon measurements
- 2008
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 131:3, s. 212-216
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Tidskriftsartikel (refereegranskat)abstract
- In retrospective radon measurements, the 22-y half life of Pb-210 is used as an advantage. Pb-210 is often considered to be relatively immobile in glass after alpha recoil implanted by Rn-222 progenies. The diffusion of Pb-210 could, however, lead to uncertain wrong retrospective radon exposure estimations if Pb-210 is mobile and can escape from glass, or lost as a result of cleaning-induced surface modification. This diffusion was studied by a radiotracer technique, where Pb-209 was used as a tracer in a glass matrix for which the elemental composition is known. Using the ion guide isotope separator on-line technique, the Pb-209 atoms were implanted into the glass with an energy of 39 keV. The diffusion profiles and the diffusion coefficients were determined after annealing at 470-620 degrees C and serial sectioning by ion sputtering. In addition, the effect of surface cleaning on diffusion was tested. From the Arrhenius fit, the activation enthalpy (H) was determined, which is equal to 3.2 +/- 0.2 eV, and also the pre-exponential factor D-0, in the order of 20 m(2)s(-1). This result confirms the assumption that over a time period of 50 y Pb-209 (and Pb-210) is effectively immobile in the glass. The boundary condition obtained from the measurements had the characteristic of a sink, implying loss of Pb-209 in the topmost surface at high temperatures.
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| 17. |
- Nagy, Gyula, et al.
(författare)
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The scanning light ion microprobe in Uppsala - Status in 2022
- 2022
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier. - 0168-583X .- 1872-9584. ; 533, s. 66-69
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Tidskriftsartikel (refereegranskat)abstract
- The Scanning Light Ion Microprobe in Uppsala (SLIM-UP) was originally installed during 1989/90. Since then, the microprobe has undergone several minor and major modifications. The present configuration is a re-build of the SLIM-UP, that is now connected to the 5 MV tandem Pelletron (R) accelerator of the Tandem Laboratory, Uppsala University. We give an overview of the present status of the Uppsala microprobe facility, including a detailed description of the components and a recent resolution test. In addition, we present the most recent technical developments whereby, the system is able to quickly image large area samples, to reliably identify individual microparticles, and to analyse them separately. Optimal parameters for a certain system can be found by simple test measurements on dummy samples. Our test scenario comprises of Fe particles embedded in a light matrix, representing human tissue. We found a good compromise between the required analysis time and particle detection efficiency.
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| 18. |
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| 19. |
- Timmers, H, et al.
(författare)
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Energy loss measurements for mass-14 ions using a patterned stopping medium on a PIN diode
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 219-20, s. 263-267
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Tidskriftsartikel (refereegranskat)abstract
- A new experimental technique to measure stopping forces for swift heavy ions was tested and has been found effective. A commercial PIN photodiode was coated with a patterned stopping medium of gold. This allowed the simultaneous detection of stopped- and reference-ions of C-14 and N-14 in the energy range E = 6.4-10.4 MeV. The stopping forces of these ions in gold have been measured with excellent accuracy. They are up to 10% larger than expected from present tabulations. It would be straightforward to use the same modified PIN diode in other experiments providing direct comparisons for an identical stopping medium.
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| 20. |
- Vockenhuber, Christof, et al.
(författare)
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Energy-loss straggling of 2–10 MeV/u Kr ions in gases
- 2013
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Ingår i: European Physical Journal D. - : EDP Sciences: EPJ. - 1434-6060 .- 1434-6079. ; 67:7
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Tidskriftsartikel (refereegranskat)abstract
- Measurements have been performed on a time-of-flight setup at the Jyväskylä K130 cyclotron, aiming at energy-loss straggling of heavy ions in gases. Theoretical predictions based on recently developed theory as well as an empirical interpolation formula predict that straggling can be more than ten times higher than Bohr straggling in the MeV/u regime. Our measurements with up to 9.3 MeV/u Kr ions on He, N2, Ne and Kr targets confirm this feature. Our calculations show the relative contributions of linear straggling, bunching including packing, and charge exchange. Our results for stopping cross sections are compatible with values from the literature.
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| 21. |
- Westerberg, L, et al.
(författare)
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CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. I. General structure, mechanics and UHV compatibility
- 2003
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 500:1-3, s. 84-95
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Tidskriftsartikel (refereegranskat)abstract
- CELSIUS Heavy-Ion Collision Silicon detector system (CHICSi) is a large solid angle, barrel-shaped detector system, housing up to 600 detector telescopes arranged in rotational symmetry around the beam axis. CHICSi measures charged particles and fragments from nuclear reactions. It operates at internal targets of storage rings. In order to optimize space and momentum-space coverage and minimize the low-energy detection limits, CHICSi is designed for use in ultra-high vacuum (UHV, similar to 10(-8) Pa) inside a cluster-jet target chamber. This calls for materials in mechanical support, detectors, Very Large Scale Integrated (VLSI) electronics, connectors, cables and other signal transport devices with very low outgassing. Two auxiliary detector systems, which will operate in coincidence with CHICSi, a heavy-recoil, time-of-flight system (HR-TOF) also placed inside the target chamber and a projectile fragmentation wall (PF-WALL) located outside the chamber, have also been constructed. In total, this combined system registers more than 80% of all charged particles and fragments from typical heavy-ion reactions at energies of a few hundreds of MeV per nucleon. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 22. |
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| 23. |
- Whitlow, Harry J
(författare)
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Application Specific Integrated Circuit (ASIC) Readout Technologies for Future Ion Beam Analytical Instruments
- 2000
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - 0168-583X .- 1872-9584. ; 161-163, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- New possibilities for ion beam analysis (IBA) are afforded by recent developments in detector technology which facilitate the parallel collection of data from a large number of channels. Application specific integrated circuit (ASIC) technologies, which have been widely employed for multi-channel readout systems in nuclear and particle physics, are more net-cost effective (160 /channel for 1000 channels) and a more rational solution for readout of a large number of channels than afforded by conventional electronics. Based on results from existing and on-going chip designs, the possibilities and issues of ASIC readout technology are considered from the IBA viewpoint. Consideration is given to readout chip architecture and how the stringent resolution, linearity and stability requirements for IBA may be met. In addition the implications of the restrictions imposed by ASIC technology are discussed.
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| 24. |
- Whitlow, Harry J, et al.
(författare)
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Formation of cobalt silicide from filter metal vacuum arc deposited films
- 2006
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 247:2, s. 271-278
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Tidskriftsartikel (refereegranskat)abstract
- The thermal reaction of Co film deposited on Si(111) surfaces by a high current filter metal vacuum arc (FMEVAD) system has been studied. After deposition the films were annealed over the 400-900 degrees C temperature range for 30 min. Rutherford backscattering spectrometry (RBS) was used to characterize the elemental depth distributions in the films subjected to different annealing temperatures. Ordered chemical phases were determined by glancing-incidence X-ray diffraction (GIXRD) and the morphology was determined by cross section transmission electron microscopy (TEM). The results show that the phases formed are Co2Si at 400 degrees C, CoSi + Coo at 500 degrees C, CoSi + CoSi2 at 600 degrees C and CoSi2 at (700-800 degrees C). At 900 degrees C, CiSi(2) was formed with a mixture of cubic cobalt and probably an amorphous cobalt oxide surface layer. The interface morphology was a rough cusp-like crenelation at 600 degrees C which became less pronounced after annealing at 800 degrees C. (c) 2006 Elsevier B.V. All rights reserved.
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| 25. |
- Whitlow, Harry J, et al.
(författare)
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Fundamental effects and non-linear Si detector response
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 190:1-4, s. 375-378
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Tidskriftsartikel (refereegranskat)abstract
- Non-linearity in the energy response of a Si p-i-n charged particle detector has been studied for incident particles with Z(1) between 3 and 26, and energies between 0.1 and 0.7 MeV per nucleon. Although the data closely followed a straight line relations, fitting of the data to a third order polynomial revealed that the response exhibited a persistent curvature that acted to reduce the energy interval spanned by a channel as the energy increased. The curvature increased as Z(1) increased from 4 to 8 and then systematically decreased. The curvature is larger and has the opposite energy dependence to the stopping in a dead entrance window and the energy deposited in non-ionising processes within the active layer. The plasma recombination dependence on the average stopping along the plasma column may account for the reduction in curvature as Z(1) increases from 9 to 25 but cannot explain the net effect. The low-energy increase in energy channel span, which has also been reported by others, might be associated with electron excitation in resonant and direct classical quasi-elastic collisions for low-energy ions, or less likely, electronic non-linearity's associated with Z(1) and energy dependent time structure in the current pulse from the detector. Simple interpolation of the window-loss corrected polynomial coefficients is the best approach if the calibration for Z(1) cannot be established directly.
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| 26. |
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| 27. |
- Whitlow, Harry J, et al.
(författare)
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Lithography of high spatial density biosensor structures with sub-100 nm spacing by MeV proton beam writing with minimal proximity effect
- 2004
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 15:1, s. 223-226
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Tidskriftsartikel (refereegranskat)abstract
- Metal electrode structures for biosensors with a high spatial density and similar to85 nm gaps have been produced using focused megaelectronvolt (MeV) proton beam writing of poly-(methyl methacrylate) positive resist combined with metal lift-off. The minimal proximity exposure and straight proton trajectories in (similar to100 nm) resist layers for focused MeV proton beam writing are strongly indicative that ultimate electrode gap widths approaching a few nanometres are achievable.
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| 28. |
- Whitlow, Harry J, et al.
(författare)
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Measurement and uncertainties of energy loss in silicon over a wide Z(1) range using time of flight detector telescopes
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 195:1-2, s. 133-146
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Tidskriftsartikel (refereegranskat)abstract
- The energy loss of projectiles with Z(1) in the range 3-26 has been experimentally measured in the 0.1-0.7 MeV per nucleon energy range in the same Si stopping foil of 105.5 mug cm(-2) thickness using a time of flight-energy (ToF-E) elastic recoil detection analysis (ERDA) setup. A detailed study of the experimental uncertainties for ToF-E and ToF-ToF-E configuration has been made. For ERDA configurations where the energy calibration is taken against the edge positions small uncertainties in the angle at which recoils are detected can introduce significant, absolute uncertainty. The relative uncertainty contribution is dominated by the energy calibration of the Si E detector for the ToF-E configuration and the position of the second ToF detector in ToF-ToF-E measurements. The much smaller calibration uncertainty for ToF-ToF-E configuration implies this technique is superior to ToF-E measurements with Si E detectors. At low energies the effect of charge changing in the time detector foils can become important. It was found that empirical stopping numbers which include the effect of effective-charge were more closely clustered about a trend line when plotted against the Bohr parameter than the corresponding Bethe parameter. Study of the deviations from the trend line showed evidence of a shell dependant effect that exceeded the anticipated maximum relative uncertainties.
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| 29. |
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| 30. |
- Whitlow, Harry J., et al.
(författare)
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Micro-Particle Induced X-ray Emission Study of Lead-Free and Lead-Based Solders and Interactions with Copper Wires
- 2023
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlagsgesellschaft. - 1862-6300 .- 1862-6319. ; 220:10
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Tidskriftsartikel (refereegranskat)abstract
- Pb-free electrical solders, such as Cu-Sn alloys, work well for reflow soldering under tightly controlled conditions. Hand soldering, however, often results in poor quality joints compared to conventional Pb-Sn solders. To investigate this under realistic workshop conditions, micro-particle induced X-ray emission (micro-PIXE) with 2 MeV protons has been employed. Commercial flux-cored Cu-Sn and Pb-Sn solder wires are studied. Solder blobs under two cooling conditions as well as tinning Restriction of Hazardous Substances (RoHS)-compliant and legacy component wires are investigated. The results show that the long heating and slow cooling of Cu-Sn solder blobs lead to formation of an acicular precipitate that can be ascribed to Cu-6 Sn-5. Pb-Sn solder under the same conditions shows phase separation with regions of high Sn and regions with high Pb. In the case of rapidly cooled blobs where a shiny surface is produced, no phase separation in either solder is observed. Tinning of RoHS-compliant and legacy Cu component wires with the two solders produce significantly different interfacial depth profiles with varying degrees of grading, indicative of intermetallic phase formation.
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| 31. |
- Whitlow, Harry J.
(författare)
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On quantitative off-axis Scanning Transmission Ion Microscopy (STIM)
- 2023
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 540, s. 51-61
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Tidskriftsartikel (refereegranskat)abstract
- Spurred by a need to determine major (C, H, N and O) contents in biological tissue sections, a formalism for quantitative off-axis Scanning Transmission Ion Microscopy (OA-STIM) has been established. This can be used with, or without, simultaneous Elastic Backscattering Spectroscopy (EBS) to provide quantitative major element composition and thickness information. As part of the work, an empirical predictor with one free parameter for the proton-proton differential scattering cross section was implemented. The predictor values were in extremely close agreement with high accuracy literature data. For 2 MeV p(-12)C elastic scattering at forward angles <= 45 degrees an interpolation procedure was used to determine the relative deviations from the Rutherford cross sections were determined to be <= 6.4%. The interpolation was based on a Coulomb field, angular momentum quantum number and nuclear structure dependent nuclear penetration factor. Finally, the quantitative combination of simultaneous OA-STIM and EBS data is discussed.
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| 32. |
- Whitlow, Harry J., et al.
(författare)
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Proton beam induced degradation of Pioloform & REG; (polyvinyl butyral (PVB)) support films used for analysis of biomedical tissue sections
- 2023
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 539, s. 136-140
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Tidskriftsartikel (refereegranskat)abstract
- Pioloform & REG;, an often used support film for ion microprobe research is a terpolymer of polyvinyl butyral (PVB) and 18 mass % polyvinyl alcohol (PVA). Simultaneous off-axis Scanning Transmission Ion Microscopy (OA-STIM) and Elastic Backscattering Spectrometry (EBS) measurements have been used to measure the evolution of the C, H and O contents for an increasing proton fluence. The results showed that the composition at zero proton-fluence was in close agreement with the theoretical atomic composition. This strongly suggests OA-STIM measurements. With increasing proton fluences preferential loss of H and O was observed from the films.
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| 33. |
- Whitlow, Harry J., et al.
(författare)
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Sequestration of Ca in simian nasal mucosa : Determination of Ca molarity in ex vivo tissue by simultaneous off-axis Scanning Transmission Ion Microscopy, Particle Induced X-Ray Emission and Elastic Backscattering Spectrometry
- 2023
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 539, s. 152-161
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Tidskriftsartikel (refereegranskat)abstract
- A technique to determine the molar concentration of elements in ex vivo tissue sections by Particle Induced X-ray Emission (PIXE) has been developed. The method is based on simultaneous off-axis scanning transmission ion microscopy (OA-STIM) and Elastic Backscattering Spectrometry (EBS) measurement of the sample thickness and major element (H, C, N, O) composition. The method was applied to determine the molarity of localised Ca concentration hot-spots in the outer epithelium tissue of nasal mucosa of a rhesus macaque subject infected with simian immunodeficiency virus (SIV). The results show Ca sequestration in concentration hot-spots and outer epithelial tissue that significantly exceeded the Ca concentration in the surrounding tissues. This may originate from mineralisation and/or Ca enhancement in goblet cells.
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| 34. |
- Zhang, YW, et al.
(författare)
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Electronic stopping powers for heavy ions in silicon
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 215:1-2, s. 48-56
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Tidskriftsartikel (refereegranskat)abstract
- The stopping powers in silicon of heavy ions, with atomic numbers ranging from 4 to 29, have been determined using a time-of-flight elastic recoil detection analysis (TOF ERDA) set-up. In transmission geometry, the energy loss of heavy elastic recoils in the self-supporting silicon foil of known thickness is measured over a continuous range of recoil energies using time-of-flight (TOF) spectrometry. By essentially calibrating the Si detector for each channel over the measured energy region using the TOF spectrometer, an uncertainty of less than 4% is achieved. The stopping powers are parameterized using a sixth order polynomial and compared with the limited experimental data in the literature. In the energy regimes Where experimental data exist, the present data exhibit good agreement with most data. Stopping powers predicted by SRIM (the stopping and range of ions in matter) are in reasonable agreement with much of the experimental data, and SRIM-2003 predictions are in somewhat better agreement than SRIM-2000. There are, however, still some discrepancies between SRIM predictions and the experimental data. (C) 2003 Elsevier B.V. All rights reserved.
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| 35. |
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| 36. |
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| 37. |
- Zhang, Y W, et al.
(författare)
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Response of Si p-i-n diode and Au/n-Si surface barrier detector to heavy ions
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 190:1-4, s. 383-386
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Tidskriftsartikel (refereegranskat)abstract
- Pulse height versus energy calibrations of a Si p-i-n diode and a Au-/n-Si surface barrier detector have been studied for heavy ions with atomic number (Z(1)) from 3 to 79 in a range from 0.1 to 0.8 MeV per nucleon as a function of bias voltage and detector tilting angle. The detector response is simultaneously measured using a time of flight-energy elastic recoil detection analysis set-up with recoils produced over a wide energy range from a thick target of each element. Prior to impinging on the Si detector, the individual recoil is tagged by its energy determined from the time of flight and tabulated isotopic mass. For both detectors, the pulse height-energy calibration for recoils with a given Z(1) is described well by a linear relationship with small systematic deviations. The linear-fit parameters show similar, but not identical dependence on both Z(1) and bias voltage (collecting field strength) for the surface barrier detectors and the p-i-n diode. These results suggest that the efficiency of electron-hole pair collection is markedly dependent on the different electric field configurations for the two detector structures.
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